Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Foam processes are essential in many industrial applications e.g., in froth flotation for material
separation. A detailed understanding of foam flows is vital for improvements in process efficiency. X-
Ray and Neutron imaging can measure flow fields in foam, but require a complex setup and cannot be
performed in-situ. Magnetic particle tracking (MPT) is an alternative approach, that measures the
trajectory of a small magnetic tracer particle inside the foam as a representation of its movement.
Different magnetic field sensors can be applied to detect the magnetic tracer particle. We chose thin film
sensors based on the planar Hall effect (PHE) due to their small size, high sensitivity, high signal-to-
noise ratio and low cost. Our sensors have a size of only 2 mm x 2 mm and are capable of measuring
magnetic fields as low as 10 nT at a sampling frequency of 1 Hz. A sensitivity of 20 V/T at a driving
current of 1 mA was achieved by means of sensor bridging. Our PHE-sensors are almost as precise as
currently used Fluxgate probes, but offer several advantages due to their reduced size. This includes
being installed closer to the area to be measured, enabling finer grids of sensors and decreasing the
detection volume, which increases the precision of the MPT as well as other tomographic methods.

We present a portable multiplexed biosensor platform based on the extended gate field-effect transistor and demonstrate its amplified response thanks to gold nanoparticle-based bioconjugates introduced as a part of the immunoassay. The platform comprises a disposable chip hosting an array of 32 extended gate electrodes, a readout module based on a single transistor operating in constant charge mode, and a multiplexer to scan sensing electrodes one-by-one. Although employing only off-the-shelf electronic components, our platform achieves sensitivities comparable to fully customized nanofabricated potentiometric sensors. In particular, it reaches a detection limit of 0.2 fM for the pure molecular assay when sensing horseradish peroxidase-linked secondary antibody (∼0.4 nM reached by standard microplate methods). Furthermore, with the gold nanoparticle bioconjugation format, we demonstrate ca. 5-fold amplification of the potentiometric response compared to a pure molecular assay, at the detection limit of 13.3 fM. Finally, we elaborate on the mechanism of this amplification and propose that nanoparticle-mediated disruption of the diffusion barrier layer is the main contributor to the potentiometric signal enhancement. These results show the great potential of our portable, sensitive, and cost-efficient biosensor for multidimensional diagnostics in the clinical and laboratory settings, including e.g., serological tests or pathogen screening.

Froth flotation is one of the most important techniques in the mining industry to efficiently separate particles with sizes between 10 μm and 200 μm. The particles are separated according to their difference in wettability, as hydrophobic particles attach to gas bubbles and are recovered in a froth, whereas hydrophilic particles tend to stay in the pulp. Although, the wettability is the most prominent separation feature, other particle properties, such as size, morphology, surface energy or the dispersion state also affect the separation process since it includes a number of complex micro processes with specific particle-bubble interactions that occur in the pulp and in the froth phase. Low ore grades and very fine composite particles in electronic devices are forcing the industry to adapt and improve existing flotation techniques to the processing of ultrafine particles (< 10 μm), as the material needs to be milled down to finer size fractions to obtain sufficient liberation of the valuable minerals. For that reason, the project “MultiDimFlot”, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”, investigates the separation of ultrafine particles (< 10 μm) based on multiple particle properties. A novel separation apparatus is used that combines the advantages of a mechanical flotation cell that comes with a high particle-bubble collision rate (thus a high recovery) with those from a flotation column with a fractionating effect due to its deep froth (thus a high grade). A well-characterised model particle system, consisting of glass spheres and glass fragments as the floatable fraction and magnetite as the non-floatable fraction is used for the separation tests. These investigations will help to further understand the behaviour of ultrafine particles during flotation and how certain particle properties affect the separation process. Furthermore, the possibilities and limitations of different analysis techniques, e.g. coupled SEM-EDX, flow cytometry or inverse gas chromatography are investigated for their use in ultrafine particle characterization.

Froth flotation is one of the most important beneficiation techniques in the mining industry. For particles with sizes ranging from 10 μm to 200 μm it efficiently separates the valuable minerals from unwanted gangue according to their differences in the particle wettabilities. For an efficient flotation separation of ultrafine particles (< 10 μm) existing techniques need to be adapted and improved in order to maintain an efficient separation. Furthermore, there is a potential in separating particles not only by wettability (surface energy) and size but also by their morphology. To investigate this is the aim of this project, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”. A well-characterised model particle system consisting of ultrafine size fractions of glass particles as the floatable and magnetite as the non-floatable fraction is used for this study. The wettability of the glass particles is modified via an esterification reaction using alcohols with differing chain length and the resulting wettability states are analysed using inverse gas chromatography as well as analytic particle solvent extraction. Information on the particle size and shape are obtained via a combination of laser diffraction and microscopic analysis. All separation tests are carried out in batch mode using a novel separation apparatus, specifically designed for the flotation of ultrafine particles by combining advantages from machine-type froth flotation and column flotation and the separation process is evaluated using multidimensional tromp maps. This investigation will help to further understand the recovery of particles with variable properties in flotation, as well as other separation processes. In this way, the separation of ultrafine particles will become more efficient, which will play an important role in the recycling of secondary materials and in the processing of ultrafine particles in the chemical industry.

Presentation on the recycling of graphite from spent lithium ion batteries, including the characterization of surface properties that are important for the separation process of flotation, by which the graphite is separated effectively from the remaining metal oxides.

Presentation about Li-ion battery characterization with a focus on the characterization of the anode and cathode active materials using different techniques such as inverse gas chromatography, dynamic vapour sorption, contact angle measurement.

High bandwidth instruments (data production rates of GB/s) have proliferated in photon science experimental facilities in the last years across the globe. Some of them are planned to be operated 24/7. Data volumes thus produced exceed both the budget of storage facilities and sometimes even the ingest capacities of hardware. In this talk, I'd like to highlight key challenges when considering both lossless and lossy compression in photon science. I will highlight data science approaches to characterize or preprocess data. The talk will also showcase advances in finding optimal encoding parameters to achieve high data ingest bandwidths at high compression ratios. In addition, I'd like to introduce challenges for lossy compression with respect to good scientific practice and our advances to mitigate them without regressing to data quality metrics.

The presentation was given at the 2023 European HDF User Group (HUG) plugins and data compression summit. For more information on the event, see https://indico.desy.de/event/39343/

Electron dynamics of anatase TiO2 under the influence of ultrashort and intense laser field is studied using the real-time time-dependent density functional theory (TDDFT). Our findings demonstrate the effectiveness of TDDFT calculations in modeling the electron dynamics of solids during ultrashort laser excitation, providing valuable insights for designing and optimizing nonlinear photonic devices. We analyze the perturbative and non-perturbative responses of TiO2 to 30 fs laser pulses at 400 and 800 nm wavelengths, elucidating the underlying mechanisms. At 400 nm, ionization via single photon absorption dominates, even at very low intensities. At 800 nm, we observe ionization through two-photon absorption within the intensity range of 1×1010 to 9×1012 W/cm2, with a transition from multiphoton to tunneling ionization occurring at 9×1012 W/cm2. We observe a sudden increase in energy and the number of excited electrons beyond 1×1013 W/cm2, leading to their saturation and subsequent laser-induced damage. We estimate the damage threshold of TiO2 for 800 nm to be 0.1 J/cm2. In the perturbative regime, induced currents exhibit a phase shift proportional to the peak intensity of the laser pulse. This phase shift is attributed to the intensity-dependent changes in the number of free carriers, indicative of the optical Kerr effect. Leveraging the linear dependence of phase shift on peak intensities, we estimate the nonlinear refractive index (n2) of TiO2 to be 3.54×10−11 cm2/W.

Practical 30min guide into ASL basics and its use in clinics and clinical research with focus given on the most important guidelines for practical use.

The higher beam intensity available for Mu2e-II will require a substantially different target design. This paper discusses our recent advances in conceptual R&D for a Mu2e-II target station. The design is based on energy deposition and radiation damage simulations, as well as thermal and mechanical analyses, to estimate the survivability of the system. We considered rotated targets, fixed granular targets and a novel conveyor target with tungsten or carbon spherical elements that are circulated through the beam path. The motion of the spheres can be generated either mechanically or both mechanically and by a He gas flow. The simulations identified the conveyor target as the preferred approach, and that approach has been developed into a prototype. We describe this first prototype for the Mu2e-II target and report on its mechanical tests performed at Fermilab, which indicate the feasibility of the design, and discuss its challenges as well as suggest directions for further improvement.

We present two types of pump-probe spectroscopy on single core-shell III-V nanowires: while the pump is either interband or intraband, a broad-band mid-infrared beam is used as probe. This provides interesting insight into carrier heating and relaxation.

Semiconductor spin qubits combine excellent quantum performance with the prospect of manufacturing quantum devices using industry-standard metal-oxide-semiconductor (MOS) processes. This applies also to ion-implanted donor spins, which further afford exceptional coherence times and large Hilbert space dimension in their nuclear spin. Here we demonstrate and integrate multiple strategies to manufacture scale-up donor-based quantum computers. We use 31PF2 molecule implants to triple the placement certainty compared to 31P ions, while attaining 99.99% confidence in detecting the implant. Similar confidence is retained by implanting heavier atoms such as 123Sb and 209Bi, which represent high-dimensional qudits for quantum information processing, while Sb2 molecules enable deterministic formation of closely-spaced qudits. We demonstrate the deterministic formation of regular arrays of donor atoms with 300 nm spacing, using step-and-repeat implantation through a nano aperture. These methods cover the full gamut of technological requirements for the construction of donor-based quantum computers in silicon.

Software developed in the process of doing research is receiving increased attention. It is now more and more often considered a genuine research output next to scientific articles and research data publications. Based on representative user stories we identify and characterize the different phases and stages that the research software development process can go through thereby defining the “Research Software Lifecycle”. Different approaches to software development such as product-, project- or platform-orientation are also outlined. We close with recommendations on EOSC infrastructure components needed to support the identified processes and platforms.

Overcoming PARPi resistance is a high clinical priority. We established and characterized comparative in vitro models of acquired PARPi resistance, derived from either a BRCA1-proficient or BRCA1-deficient isogenic background by long-term exposure to olaparib. While parental cell lines already exhibited a certain level of intrinsic activity of multidrug resistance (MDR) proteins, resulting PARPi-resistant cells from both models further converted toward MDR. In both models, the PARPi-resistant phenotype was shaped by (i) cross-resistance to other PARPis (ii) impaired susceptibility toward the formation of DNA-platinum adducts upon exposure to cisplatin, which could be reverted by the drug efflux inhibitors verapamil or diphenhydramine, and (iii) reduced PARP-trapping activity. However, the signature and activity of ABC-transporter expression and the cross-resistance spectra to other chemotherapeutic drugs considerably diverged between the BRCA1-proficient vs. BRCA1-deficient models. Using dual-fluorescence co-culture experiments, we observed that PARPi-resistant cells had a competitive disadvantage over PARPi-sensitive cells in a drug-free medium. However, they rapidly gained clonal dominance under olaparib selection pressure, which could be mitigated by the MRP1 inhibitor MK-751. Conclusively, we present a well-characterized in vitro model, which could be instrumental in dissecting mechanisms of PARPi resistance from HR-proficient vs. HR-deficient background and in studying clonal dynamics of PARPi-resistant cells in response to experimental drugs, such as novel olaparib-sensitizers.

A review of single photon emitters in silicon based on ion-induced defects is provided. Fabrication methods and current state of the art are discussed.

The structural stability of DNA origami nanostructures in various chemical environments is an important factor in numerous applications, ranging from biomedicine and biophysics to analytical chemistry and materials synthesis. In this work, the stability of six different 2D and 3D DNA origami nanostructures is assessed in the presence of three different chatropic salts, i.e., guanidinium sulfate (Gdm2SO4), guanidinium chloride (GdmCl), and tetrapropylammonium chloride (TPACl), which are widely employed denaturants. Using atomic force microscopy (AFM) to quantify nanostructural integrity, Gdm2SO4 is found to be the weakest and TPACl the strongest DNA origami denaturant, respectively. Despite different mechanisms of actions of the selected salts, DNA origami stability in each environment is observed to depend on DNA origami superstructure. This is especially pronounced for 3D DNA origami nanostructures, where mechanically more flexible designs show higher stability in both GdmCl and TPACl than more rigid ones. This is particularly remarkable as this general dependence has previously been observed under Mg2+-free conditions and may provide the possibility to optimize DNA origami design toward maximum stability in diverse chemical environments. Finally, it is demonstrated that melting temperature measurements may overestimate the stability of certain DNA origami nanostructures in certain chemical environments, so that such investigations should always be complemented by microscopic assessments of nanostructure integrity.

Indistinguishable single-photon sources at telecom wavelengths are the key photonic qubits for transmitting quantum information over long distances in standard optical fibers with minimal transmission losses and high fidelity. This enables secure quantum communication over the quantum internet and, in turn, a modular approach to quantum computing. The monolithic integration of single-photon sources with reconfigurable photonic elements and single-photon detectors in a silicon chip is a key enabling step toward demonstrating scalable quantum hardware such as quantum photonic integrated circuits (QPICs). Nowadays, nearly all the necessary components for QPICs are available such as superconducting single-photon detectors, low-loss photonic waveguides, delay lines, modulators, phase shifters, and low-latency electronics. Yet, the practical implementation of scalable quantum hardware has been largely hampered by the lack of on-chip single-photon emitters in silicon that can be created at desired locations on the nanoscale.
Here, we demonstrate two complementary wafer-scale protocols for the quasi-deterministic creation of single G and W telecom-wavelength color centers in silicon with a probability exceeding 50%. Both approaches are fully compatible with current silicon technology and enable the fabrication of single telecom quantum emitters at desired nanoscale positions on a silicon chip. These results unlock a clear and easily exploitable pathway for industrial-scale photonic quantum processors with technology nodes below 100 nm.

Our research aims at a better understanding of fundamental processes defining transport and accumulation of radiotoxic elements such as U, Np, Pu, Am, Cm, as well as Tc and Se. This requires knowledge of their mobility in the environment and of their (radio)ecological behavior. The results will help to develop biochemically and radiochemically founded risk assessment schemes, remediation procedures in areas affected by uranium mining, and help to assess the long-term safety of final disposal sites for nuclear waste in geologic formations.
Therefore, we apply solution- and solid-state NMR to various simple and complex systems. Occasionally, lanthanide ions, Ln(III), are used as non-radioactive, isoelectronic analogs for trivalent actinides, An(III). Radionuclide complexation by small molecules is studied for, e.g., citrate [1,2], glutathione (GSH/GSSG) [3,4], as well as 2-phosphonobutane-1,2,4,-tricarbox-ylate (PBTC) [5] and nitrilotriacetate (NTA) [6]. Selenium and (organo)borates were subject of NMR studies, too [7–9]. Comprehensive kinetic and thermodynamic studies were performed for water addition to PQQ, a redox cofactor in Ln(III)-dependent alcohol dehydrogenases [10]. Indicator molecules excreted from carrot cells or fungi upon treatment with uranium were identified also by NMR [11,12]. Furthermore, the bulk structure as well as the interaction of organics (e.g., gluconate, PBTC) and/or radionuclides with calcium (aluminate) silicate hydrate (C (A )S H) phases related to cementitious materials critical for nuclear waste disposal infrastructures were characterized by 13C, 31P, 27Al, and 29Si MAS NMR [13,14].

Literature:

[1] J. Kretzschmar et al., Chem. Commun. 2020, 56, 13133. [2] J. Kretzschmar et al., Inorg. Chem. 2021, 60, 7998. [3] J. Kretzschmar et al., Chem. Commun. 2018, 54, 8697. [4] J. Kretzschmar et al., Inorg. Chem. 2020, 59, 4244. [5] J. Kretzschmar et al., Molecules 2022, 27, 4067. [6] S. Friedrich et al., Molecules 2023, submitted. [7] J. Kretzschmar et al., Dalton Trans. 2015, 44, 10508. [8] J. Schott et al., Dalton Trans. 2014, 43, 11516. [9] J. Schott et al., Dalton Trans. 2015, 44, 11095. [10] N. Al Danaf et al., Phys. Chem. Chem. Phys., 2022, 24, 15397. [11] J. Jessat et al., J. Hazard. Mater. 2022, 439, 129520. [12] A. Wollenberg et al., J. Hazard. Mater. 2021, 411, 125068. [13] S. Dettmann et al., Front. Nucl. Eng. 2023, 2, 1124856. [14] K. Schmeide et al., in preparation.

We studied the high-field phase diagram of a chiral-lattice antiferromagnet Sr(TiO)Cu₄PO₄)₄ by means of ultrasound, dielectric, and magnetocaloric-effect measurements. These experimental techniques reveal two new phase transitions at high fields, which have not been resolved by previous magnetization experiments. Specifically, the c₆₆ acoustic mode shows drastic changes with hysteresis for magnetic fields applied along the c axis, indicating a strong magnetoelastic coupling. Combined with cluster mean-field theory, we discuss the origin of these phase transitions. By considering the chiral-twist effect of Cu₄O₁₂ cupola units, which is inherent to the chiral crystal structure, the phase diagram is reasonably reproduced. The agreement between experiment and theory suggests that this material is a unique quasi-two-dimensional spin system with competing exchange interactions and chirality, leading to a rich phase diagram.

Flashing flows of initially sub-cooled water in a converging–diverging nozzle is investigated numerically in the framework of the two-fluid model (TFM). The thermal non-equilibrium effect of phase change is considered by an interfacial heat transfer model, while the pressure jump across the interface is ignored. The bubble size distribution induced by nucleation, bubble growth/shrinkage, coalescence, and breakup is described based on the interfacial area transport equation (IATE) and constant bubble number density model (CBND), respectively. The results are compared with the experimental data. Satisfactory prediction of the axial pressure distribution along the nozzle as well as the flashing inception, is achieved by the TFM-IATE coupling method. It was also found that the vapor production in the diverging section was overpredicted, and the radial gas volume fraction distribution deviated from the experiment. The radial diameter profiles exhibit opposite patterns at the nozzle throat and near the outlet, and similar trends can be observed for the superheated degree. A poly-disperse method is suggested to be introduced to describe the evolution of interfacial area concentration.

The behaviour of any physical system is determined by the order parameter whose distribution is governed by the geometry of the physical space of the object, in particular its dimensionality and curvature [1]. Curvilinear magnetism is a framework, which helps understanding the impact of geometrical curvature on complex magnetic responses of curved 1D wires and 2D shells [2-4]. The lack of inversion symmetry and emergence of curvature induced anisotropy and Dzyaloshinskii-Moriya interaction (DMI) stemming from the exchange interaction [5,6] are characteristic of curved surfaces. Recently, a non-local chiral symmetry breaking was discovered [7], which is responsible for the coexistence and coupling of multiple magnetochiral properties within the same magnetic object [8]. Regarding antiferromagnets, it is demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [9-11]. This positions curvilinear antiferromagnets as a platform for geometrically tunable antiferromagnetic spinorbitronics.

[1] P. Gentile et al., “Electronic materials with nanoscale curved geometries”. Nature Electronics (review) 5, 551 (2022).
[2] D. Makarov et al., “Curvilinear micromagnetism: from fundamentals to applications” (Springer, Zurich, 2022).
[3] D. Makarov et al., “New dimension in magnetism and superconductivity: 3D and curvilinear nanoarchitectures”. Adv. Mat. (review) 34, 2101758 (2022).
[4] D. Sheka et al., “Fundamentals of curvilinear ferromagnetism: statics and dynamics of geometrically curved wires and narrow ribbons”. Small (review) 18, 2105219 (2022).
[5] Y. Gaididei et al., “Curvature effects in thin magnetic shells”. Phys. Rev. Lett. 112, 257203 (2014).
[6] O. Volkov et al., “Experimental observation of exchange-driven chiral effects in curvilinear magnetism”. Phys. Rev. Lett. 123, 077201 (2019).
[7] D. Sheka et al., “Nonlocal chiral symmetry breaking in curvilinear magnetic shells”. Commun. Phys. 3, 128 (2020).
[8] O. Volkov et al., “Chirality coupling in topological magnetic textures with multiple magnetochiral parameters”. Nature Com. 14, 1491 (2023).
[9] O. Pylypovskyi et al., “Curvilinear one-dimensional antiferromagnets”. Nano Lett. 20, 8157 (2020).
[10] O. Pylypovskyi et al., “Curvature-driven homogeneous Dzyaloshinskii-Moriya interaction and emergent weak ferromagnetism in anisotropic antiferromagnetic spin chains”. Appl. Phys. Lett. 118, 182405 (2021).
[11] Y. Borysenko et al., “Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains”. Phys. Rev. B 106, 174426 (2022).

In this lecture for magnetism students, we cover different fabrication methods to produce bulk, thin film, composites, 3D magnetic functional samples.

In this lecture for magnetism students we review different magnetic materials with focus on their functionality and related application directions. Bulk, thin films, 2D materials, heterostructures, 3D magnetic architectures are addressed in the lecture.

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe_1.908Ni_0.092As₂ single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10^–4) was observed in the direction of twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe_1.908Ni_0.092As₂ can be well explained by a flux-pinning-induced mechanism.

The accurate determination of light absorption in the material is necessary to understand the photocatalytic mechanism. Here, we present the systematic study of light absorption in the prototypical Van derWaals (vdW) heterostructure PtS2-SnS2 by including the electron-hole interaction in the computational calculation by the GW Bethe Salpeter Equation (GW-BSE) approach. The GGA-PBE level bandgap of the PtS2 -SnS2 vdW heterostructure is calculated to be 1.09 eV which is less than that of monolayers of PtS2 and SnS2. Later, GW-BSE absorption spectra pointed out the bound excitonic peaks of PtS2-SnS2 vdW heterostructure which have significant impact on the light absorption property of the material. The first excitonic peak of this vdW heterostructure obtained at the 2.17 eV which is in the low energy range compared to monolayers of PtS2 and SnS2. This low energy shift of the first excitonic peak will be favourable for better light absorption as well as boosted photoconversion efficiency of the PtS2-SnS2 vdW heterostructure.

The newly discovered monolayer selenium from group VI elements gains prominence due to its potential application in diverse fields including optoelectronics. In this work we have performed a systematic first principles study on the structural, electronic, linear and nonlinear optical characteristics of selenium Van der Waals (vdW) heterostructure with noble metal chalcogenide PtS2. The GW-Bethe-Salpeter Equation (GW-BSE) approach was used to accurately treat the quasiparticle and excitonic spectra. The optimized heterostructure shows the indirect band gap of 0.82 eV at GGA-PBE level. The newly designed interface shows type II band alignment. GW-BSE absorption spectra show a bound excitonic peak at 1.40 eV as compared with 1.28 eV in monolayer Se. The exciton binding energy of the Se-PtS2 vdW interface is 0.35 eV compared with the 0.45 eV for monolayer Se. The strong excitonic visible light absorption together with the type II band alignment makes the Se-PtS2 vdW heterostucture suitable candidate for the photovoltaic and photocatalytic applications.

Electron correlation microscopy experiments were conducted on amorphous germanium (a-Ge) and amorphous silicon (a-Si) with the goal to study self-diffusion. For this purpose, a series of tilted dark-field images were acquired during in situ heating of the samples in a transmission electron microscope. These experiments show that the measurements are greatly affected by artefacts. Contamination, crystallization, electron beam-induced sputtering, and macroscopic bending of the samples pose major obstacles to the measurements. Other, more subtle experimental artefacts could occur in addition to these which makes interpretations regarding the structural dynamics nearly impossible. The data were nonetheless evaluated to see if some useful information could be extracted. One such result is that the distribution of the characteristic times τ(KWW⁠), which were obtained from stretched exponential fits to the intensity autocorrelation data, is spatially heterogeneous. This spatial heterogeneity is assumed to be caused by a potential nonergodicity of the materials, the artefacts or an inhomogeneous amorphous structure. Further data processing shows that the characteristic times τ(KWW) are moreover temperature independent, especially for the a-Ge data. It is concluded that the structural rearrangements over time are primarily electron beam-driven and that diffusive dynamics are too slow to be measured at the chosen, experimentally accessible annealing temperatures.

The electronic, thermodynamic, and optical properties of a new type of twodimensional Janus layer (JL) consisting exclusively of chalcogens are investigated using first principles calculations. The permutations on atomic sites provide increased stability due to the multi-valency of chalcogens, and a heavier central atom further stabilizes the layer due to the increased coordination number. The investigated JLs are indirect bandgap materials with a bandgap larger than 1.23 eV, making them suitable for photocatalytic activity. Different feasible chemical potentials are analyzed, and chalcogens’ poor limits are proposed to fabricate the JLs. Based on the comparison of the formation energy, the energetic profile of the JLs is identified as Ef(TeSeS) < Ef(SSeTe) < Ef(SeSTe), irrespective of the chemical potentials of chalcogen. Hence, TeSeS is more stable than the JL arrangements SSeTe and SeSTe. The flat bands around the Fermi energy level and the reduction in path length between the maximum of conduction and minimum of valence bands explain the magnitude of multiple peaks observed in the optical spectra of the JLs. These absorptions turn the studied JLs into potential candidates for water splitting. The optimized bandgap reveals that the band edges efficiently straddle the water redox potentials at different pH levels. In addition, the positive vibrational frequencies depict the stability of these layers. Because of the minimal formation energy requirement, higher density of states around the Fermi level, as well as enhanced optical absorption compared to other JL, TeSeS JLs may lead to enhanced performance in photovoltaic and photocatalytic applications. These results add new members to the JL family of pure chalcogens and pave the way toward novel materials for respective applications.

Cone-beam CTs are a promising solution for fast imaging required by Online Adaptive Proton Therapy. Verifying adapted treatment plans with prompt-gamma-imaging (PGI) requires a reference simulation on the respective planning image. Cone-beam CTs and conventional fan-beam CTs were acquired for a homogeneous PMMA cylinder and an antropomorphic head phantom. Two RayStation algorithms were used to create a corrected cone-beam CT and a virtual CT for each phantom. PGI simulations were performed on all datasets and compared to a corresponding dose evaluation. CBCT data was shown to be suitable for PGI reference simulations if range prediction is correct, which is a requirement for plan adaptation. Uncertainty in material assignment due to noise in CBCT does not worsen PGI emission signal.

ThTi2O6 derived compounds with the brannerite structure were designed, synthesised, and characterised with the aim of stabilising incorporation of U5+ or U6+, at dilute concentration. Appropriate charge compensation was targeted by co-substitution of Gd3+, Ca2+, Al3+, or Cr3+, on the Th or Ti site. U L3 edge X-ray Absorption Near Edge Spectroscopy (XANES) and High Energy Resolution Fluorescence Detected U M4 edge XANES evidenced U5+ as the major oxidation state in all compounds, with a minor fraction of U6+ (2–13%). The balance of X-ray and Raman spectroscopy data support uranate, rather than uranyl, as the dominant U6+ speciation in the reported brannerites. It is considered that the U6+ concentration was limited by unfavourable electrostatic repulsion arising from substitution in the octahedral Th or Ti sites, which share two or three edges, respectively, with neighbouring polyhedra in the brannerite structure.

Technetium-99 (⁹⁹Tc) is a radioactive isotope with a long half-live (211,000 a). It is produced in nuclear power plants and nuclear weapon detonation since it is a fission product of U-235 and Pu-239. In addition, 99Tc forms after gamma ray emission of metastable technetium-99 (99mTc), which is the most used isotope for cancer diagnosis at hospitals [1]. The emission of ⁹⁹Tc in the environment is hazardous for living organisms and depends on its chemical speci-ation, being especially decisive the oxidation state. Thus, several works focused on the speciation (e.g., [2–4]) and immobilization of Tc (e.g., [5,6]) based on redox changes.
The nuclear properties of Tc99 make it suitable to study Tc molecular structures by NMR [7,8] and, depending on the oxidation state and thus electron configuration, also by EPR [9] spec-troscopies. Despite the power of both these methods, they have been rarely used for envi-ronmental studies.
In this work we reduced KTcO₄ electrochemically in carbonate solutions in dependence on pH (8.2–10.0), Tc concentration (0.5–9.5 mM), carbonate concentration (5–1000 mM), and the applied potential. Tc(VII) reduction was monitored in the UV-vis range in situ using a spec-tro-electrochemical cell. At -0.85 V a pink solution (λmax 512 nm) was obtained, corresponding to a Tc(IV) carbonate species [2], whereas reduction at -0.95 V yields a bluish green solution (λmax 630 nm), associated with a Tc(III) carbonate complex [2]. The obtained solutions were then investigated by ⁹⁹Tc NMR. The −0.85 V solution reveals a resonance at ~1600 ppm, indicative of a carbonate species of Tc(V) since the chemical shift range is characteristic for Tc in +V oxidation state [7]. The other specimen yielded at −0.95 V, in addition to the former Tc(V) signal at about 1600 ppm, gives rise to one additional signal at ~152 ppm, which is in the chemical shift range expected for Tc(III) [7].
These are unprecedented NMR data on aqueous Tc carbonate species, which advance the mechanistic understanding of Tc redox behavior and help to improve safety and risk analyses for nuclear waste management.
Literature:
[1] A.H. Meena et al., Env. Chem Lett. 2017, 15, 241.
[2] J. Paquette et al., Can. J. Chem. 1985, 63, 2369.
[3] M. Chotkowski et al., J. Electroanal. Chem. 2018, 814, 83.
[4] D.M. Rodríguez et al, Inorg. Chem. 2022, 61, 10159.
[5] N. Mayordomo et al., Chem. Eng. J. 2021, 408, 127265.
[6] C.I. Pearce et al., Sci. Total Environ. 2020, 716, 132849.
[7] V.A. Mikhalev, Radiochemistry 2005, 47, 319.
[8] G.B. Hall et al., Inorg. Chem. 2016, 55, 8341.
[9] U. Abram et al., Radiochim. Acta. 1993, 63, 139.

The migration behaviour of different grain boundaries with misorientations close to the Σ3 CSL orientation relationship in
high purity Al bicrystals under the capillary driving force and applied mechanical stress was investigated. The experiments
were performed by an in-situ technique to observe and measure the boundary migration with a scanning electron
microscope. The ability of the nearly Σ3 60°〈111〉 incoherent {110} and {112} boundaries to move under capillary driving
force was found to depend critically on the initial boundary inclination. While boundaries with inclinations near {112} can
easily assume a curved shape and migrate, boundaries with an initial {110} plane remain stationary or form non-mobile
facets. This is attributed to the essential anisotropy of the inclination dependence of the energy γ(ψ) of 60°〈111〉 tilt
boundaries with differently high torque dγ/dψ around {112} and {110} inclinations, as revealed by atomistic simulations of the
respective boundaries. The Σ3 70.5°〈110〉 tilt boundary with the geometry corresponding to the coherent {111} twin
boundary, was found to be immobile under both driving forces applied. The 59.2° 〈111〉 tilt grain boundary with geometry
near the Σ3 {110} incoherent twin boundary was found to be quite mobile under applied shear stress. The measured
migration activation enthalpy H = 0.45 eV for this boundary is the lowest among the values obtained in previous experiments
for any other stress driven grain boundary in Al bicrystals of the same purity. Moreover, this boundary migrated with a zero
coupling factor, i.e. without producing any measurable shear parallel to the boundary plane.

As well known, the quality of the photocathodes is critical for the stability and reliability of photo-injector operation. Especially for the superconducting rf guns, the photocathode is one of the most important parts. In last years, thanks to the developed photocathode technology, several SRF guns were successfully operated or tested for the beam generation at kHz-MHz repetition rate. In this review, the achievements as well as open questions for the cathode requirements of the reliable SRF gun operation will be reviewed, and the possible improvement from photocathodes point of view for the future application will be discussed.

Quasi-2D (q2D) conjugated polymers (CPs) are polymers that consist of linear CP chains assembled through non-covalent interactions to form a layered structure. In this work, the synthesis of a novel crystalline q2D polypyrrole (q2DPPy) film at the air/H2SO4 (95%) interface is reported. The unique interfacial environment facilitates chain extension, prevents disorder, and results in a crystalline, layered assembly of protonated quinoidal chains with a fully extended conformation in its crystalline domains. This unique structure features highly delocalized π-electron systems within the extended chains, which is responsible for the low effective mass and narrow electronic bandgap. Thus, the temperature-dependent charge-transport properties of q2DPPy are investigated using the van der Pauw (vdP) method and terahertz time-domain spectroscopy (THz-TDS). The vdP method reveals that the q2DPPy film exhibits a semiconducting behavior with a thermally activated hopping mechanism in long-range transport between the electrodes. Conversely, THz-TDS reveals a band-like transport, indicating intrinsic charge transport up to a record short-range high THz mobility of ≈107.1 cm2*V^{−1}*s^{−1}.

Die EU ist bei Rohstoffen für Energiewende und Digitalisierung vom Ausland abhängig. Eine EU-Rohstoffagentur soll das ändern, fordern Jakob Kullik und Jens Gutzmer.

In this work, the range of alumina (Al₂O₃) and yttrium aluminum garnet (YAG) aerogels was extended by doping them with lanthanide ions. The aerogels were synthesized by using a universal, epoxide-assisted sol−gel method. They were thermally treated to induce structural changes, which were characterized in more detail by using X-ray diffraction and electron microscopy. The alumina samples showed topotactic phase transformations from boehmite, via γ-alumina to a mixed alumina phase, while the YAG started as an amorphous mixed oxide phase, which crystallized at 1000 °C into pure crystalline YAG. In order to expand the functionalities of the aerogels, they were doped with the rare-earth ions Eu³⁺ and Tb³⁺ (3 mol %). The red or green photoluminescence could be observed only starting from a temperature treatment of 550 °C, which can be related to the defect reduction and crystallinity increase due to phase transformations and sintering processes occurring. For the first time, the photoluminescence quantum yields of luminescent aerogels could be determined. The highest quantum yield of 25.5 ± 1.1 % was achieved for the Al₂O₃-Tb-1000 sample.

Die Lange Nacht der Wissenschaft und Wirtschaft ist seit 2007 eine Institution in Freiberg und begeistert alle zwei Jahre Groß und Klein bei spannenden Experimenten, Vorträgen und Führungen. Das Virus ließ die Neugierigen nun noch ein Jahr länger warten, aber am 18. Juni war es endlich so weit. Über 1.000 Besucher zog es ans Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF), um hautnah zu erleben, womit sich die Forschenden an einem Institut des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) so beschäftigen. Zahlreiche Experimente, Mitmach-Aktionen und Führungen begeisterten die Wissenschaftsinteressierten trotz der sommerlich heißen Temperaturen.

From microplastics to pollen grains resuspending into the atmosphere, the resuspension of microparticles by a turbulent gas flow occurs in many natural, environmental and industrial systems. A subtle interplay between drag, lift and adhesion forces occur during the particle detachment. In this lecture, the role of turbulence and wall roughness on particle deposition and resuspension will be explained. I will also showcase how can one measure aerosol deposition and resuspension in opaque and complex geometries.

The small modular reactor (SMR) NuScale is modelled by Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in the framework of the EU H2020 McSAFER project. NuScale is a SMR of integral pressurized water reactor (iPWR) type, operated by light water driven by natural circulation in all operation modes. This work summarizes the modelling approach of NuScale SMR with the coupled thermalhydraulic/neutronic code ATHLET-DYN3D. The 3-D neutronic calculation is performed with a XS-library developed with Serpent based on 4-neutron group homogenized nuclear constants for fuel and heavy reflector. The paper presents results and discussion from a non-isolable double-ended steam line break (SLB) sequence, based on the Design Certification Application (DCA) report. The simulation results at steady-state show agreement with the reference values from the DCA report. The transient calculation shows that both steam generators (SGs) boil-off and the reactor is tripped upon “low main steam pressure” function. The rapid depressurization and high steam rates towards the break lead to enhanced primary-tosecondary heat removal. However, the reactor symmetry imposed by the arrangement of the two compact SGs enhances flow mixing and limits coolant temperature reduction at the core inlet, thereby preventing a
power excursion and highlighting the inherent safety of this reactor design. Acceptance criterion is met
regarding pressure increase below acceptable limits inside the intact SG after steam isolation valve closure.

Auf eine der drängendsten Fragen unserer modernen Gesellschaft, nämlich nach einem nachhaltigen, verantwortungsbewussten Umgang mit unseren natürlichen Rohstoffquellen, ist der Aufbau einer effizienten Kreislaufwirtschaft eine mögliche Antwort. Den Ressourceneinsatz, die Emissionen und den Energieverbrauch gilt es durch den Einsatz geschlossener Stoffkreisläufe zu minimieren. Das bedeutet, dass wir uns neben einer effizienten Nutzung der Rohstoffe auch mit einer exponentiell steigenden Abfallmenge auseinandersetzen müssen. Bisher wird allerdings nur ein kleiner Anteil aller Abfälle recycelt. Ein Grund dafür ist die zunehmende Komplexität der global anfallenden Recycling-Stoffströme, die eine rasche Weiterentwicklung der Inline-Rohstoffcharak-
terisierung unabdingbar macht.

Am 9. September 2021 wurde das neugebaute Metallurgie-Technikum am Standort des Helmholtz-Instituts Freiberg für Ressourcentechnologie (HIF), das
zum Helmholtz-Zentrum Dresden-Rossendorf (HZDR) gehört und eine gemeinsame Gründung des HZDR und der TU Bergakademie Freiberg (TU BAF) ist, eingeweiht. In der neuen Versuchshalle werden künftig Forschungsergebnisse zur pyro- bzw. hydrometallurgischen Rückgewinnung wirtschaftsstrategischer Metalle zum (Wieder-) Einsatz in modernen Schlüsseltechnologien aus dem Labor- in den Pilotmaßstab überführt und so für den Transfer in die Industrie vorbereitet. Dazu werden innovative Verfahren miteinander kombiniert und digital untereinander vernetzt. Das Technikum bietet damit exzellente Voraussetzungen, um neue Technologien und Prozesse zu erproben, zu automatisieren und zu optimieren.

Als Professor der Geognosie an der Bergakademie Freiberg gilt Bernhard von Cotta als Begründer der Erzlagerstättenlehre. Dieser Ruf wird zumeist zurückgeführt auf die Publikation des Lehrbuchs „Die Lehre von den Erzlagerstätten" im Jahr 1850 (von Cotta, 1859). Darüber hinaus hat Prof. von Cotta aber auch durch die Publikation der als „Gangstudien“ betitelten vier Bände in den Jahren 1850-1862 Herausragendes für die Erzlagerstättenlehre geleistet. Im Vorwort zum ersten Band definiert von Cotta sehr klar als Zweck der Gangstudien „über die Bedingungen der Erzführung womöglich einiges Licht zu verbreiten; also Materialien zu einer wissenschaftlichen Wünschelruthe zu liefern, welche künftig dem Bergmann auf seinen dunklen Pfaden als eine Leitschnur dienen könnte.” Motiviert wurde die Publikation der Gangstudien dabei insbesondere durch die proaktive Rolle des Oberbergamts, welches „eine sorgfältige Untersuchung der hiesigen Erzgänge und vorzüglich ihrer Veredelungs- oder Verunedelungsursachen angeordnet” hatte. Daher richtete von Cotta den Fokus der Gangstudien zunächst klar auf die Bildung der Erzlagerstätten in der Region. In der durch Bernhard von Cotta zusammengestellten
Publikationsreihe findet sich in der Folge eine große Zahl von Beiträgen, welche durchaus als bahnbrechend für ihre Zeit gelten.
Die vorerst letzte Phase des Bergbaus in Freiberg endete im Jahre 1969; der Bergbau im Erzgebirge fand mit der deutschen Wiedervereinigung im Jahr 1991 ein unvermitteltes Ende. In den seither vergangenen Jahrzehnten hat die Kenntnis um die Entstehung der Erzlagerstätten im Erzgebirge mit modernen geowissenschaftlichen Erkenntnissen und Konzepten nicht mitgehalten. Dadurch ging viel Kompetenz verloren – aus modellbasierten Annahmen früherer Bearbeiter wurden „in Stein gehauene” Paradigmen, die weitestgehend unkritisch weitergegeben wurden. Mit dem Ziel, diesen offensichtlichen und eklatanten Missstand zu beheben, wurde im Jahr 2018 die ESF Nachwuchsforschergruppe „Mineral Systems Analysis” gegründet. Ermöglicht durch öffentliche Fördermittel der Europäischen Union und des Freistaats Sachsen haben sich seither zwei Doktorandinnen und zwei Doktoranden, flankiert durch eine Vielzahl von Master- und Bachelor-Student*innen unter der Leitung von Mathias Burisch mit der Entstehung verschiedener hydrothermaler Lagerstättentypen im Erzgebirge befasst. Die Arbeiten der Nachwuchsgruppe am Institut für Mineralogie der TU Bergakademie Freiberg wurden durch Max Frenzel und Jens Gutzmer am Helmholtz-Institut Freiberg für Ressourcentechnologie unterstützt. Die Forschung basierte dabei zum Teil auf dem Studium von hervorragenden Proben der geowissenschaftlichen Sammlungen der TU Bergakademie Freiberg, der Wismut GmbH und dem Bohrkernarchiv des
Sächsischen Landesamts für Umwelt, Landwirtschaft und Geologie. Die enge und vertrauensvolle Zusammenarbeit mit den Firmen, die aktuell im Bereich von Rohstofferkundung und -abbau im Erzgebirge beteiligt sind, lieferte einen weiteren wichtigen Baustein für den Erfolg der Gruppe. Die Entwicklung eines modernen Verständnisses der räumlich-zeitlichen Entwicklung der Erzlagerstätten im Erzgebirge und die Integration der lagerstättenbildenden Prozesse mit relevanten Prozessen der regional- und lokalgeologischen Entwicklung stand im Fokus der Forschung – ganz im Sinne von Bernhard von Cotta. Daher sind die wichtigsten Resultate der Arbeit der Nachwuchsforschergruppe, die im Folgenden vorgestellt werden sollen, in das aktuelle Verständnis der geotektonischen Entwicklung eingebettet. Hier werden insgesamt 10 peer-review Artikel der Mineral Systems Analysis Gruppe zusammengefasst, die alle in der Referenzliste aufgeführt sind und bei Interesse zur weiteren Vertiefung gelesen werden können.

Wenn wir die negativen Auswirkungen menschlicher Aktivitäten auf Klima und Umwelt reduzieren wollen, müssen wir uns zwangsläufig mit einer exponentiell steigenden Abfallmenge auseinandersetzen. Solche Abfälle beinhalten nicht nur die Reste unseres alltäglichen Konsums wie z. B. Elektroschrott. Im Bergbau wird beispielsweise nur ein kleiner Teil des geförderten Gesteins tatsächlich für die Gewinnung neuer Rohstoffe genutzt, der größere Rest landet auf Halden. Zusätzlich zu solchen primären Abfällen fallen große Mengen an Sekundärabfällen wie Verbrennungsrückstände und Schlacken an. Ein besseres Recycling unserer Reststoffe ist zu einer dringlichen Aufgabe geworden, und auch wenn eine vollständige Kreislaufwirtschaft in Zukunft Utopie bleiben muss, so sollten wir uns doch so viel wie möglich daran annähern.

Neue Wege im Umgang mit Bergbaualtlasten
In den vergangenen zehn Jahren befassten sich mehrere nationale und europäische Förderprogramme mit dem Ressourcenpotenzial von Bergbauabfällen (Grobbergematerial, Spülhalden und Hüttenschlacken), wobei der Schwerpunkt auf der Erschließung neuer Quellen für kritische Rohstoffe lag, die von
der Europäischen Kommission als äußerst wichtig für die europäische Hightech-Industrie definiert wurden. Sie beruhen auf der europäischen und nationalen Ressourcenstrategie. Eines dieser Programme in Deutschland war das vom Bundesministerium für Bildung und Forschung (BMBF) geförderte Programm
„r3 - Strategische Metalle und Mineralien - Innovative Technologien für Ressourceneffizienz", das im Jahr 2012 startete. Ziel war es, die Versorgung der deutschen Wirtschaft mit strategisch bedeutsamen Metallen und Mineralien zu sichern und Projekte in den Bereichen Recycling, Substitution und reduziertem Ressourcenverbrauch, Urban Mining und Methoden zur Bewertung der Ressourceneffizienz zu fördern.

Die Entwicklung, die das Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF) seit seiner Gründung genommen hat, ist eine Erfolgsgeschichte. Denn wer hätte vor 10 Jahren gedacht, dass die Idee, ein Institut für Ressourcentechnologie zu gründen, so schnell Früchte tragen würde! Eine wesentliche Rol-
le spielt dabei, dass es ein Helmholtz-Institut geworden ist, denn Institute dieses Namens geben strategischen Partnerschaften zwischen Zentren der Helmholtz-Gemeinschaft und Universitäten eine besondere Intensität. In unserem Fall ist es die dauerhaft enge Zusammenarbeit auf dem Gebiet der Ressourcentechnologie zwischen dem Helmholtz-Zentrum Dresden-Rossendorf (HZDR) und der TU Bergakademie Freiberg. Der Namensgeber der Gemeinschaft, Hermann von Helmholtz, vertrat eine Naturwissenschaft, die Brücken zwischen Medizin, Physik und Chemie schlägt. Seine bahnbrechenden Forschungen und Entwicklungen verknüpften Theorie, Experiment und praktische Anwendung miteinander. Diesen bewährten Ansatz möchte das HIF mit dem Ausbau eines Campus für Ressourcentechnologie und Nachhaltigkeit am Standort Chemnitzer Straße 40 in Freiberg fortschreiben und auch damit ein national sowie international ausgerichtetes Kompetenzzentrum zur Erforschung, Entwicklung und Bewertung innovativer Ressourcentechnologien im Kontext einer dem Nachhaltigkeitsprinzip verpflichteten Kreislaufwirtschaft sein. Mit dem Forschungscampus wird es möglich, Innovationen für den nachhaltigen Umgang mit komplex zusammengesetzten Rohstoffen bzw. Stoffströmen voranzutreiben und die Aufbereitung und Rückgewinnung dieser
Rohstoffe auf hohem wissenschaftlich-technischen Niveau vom Labor- in den Pilotmaßstab zu überführen. Ziel ist es dabei, die entsprechenden Technologieentwicklungen zeitnah in die industrielle Praxis zu bringen. Damit steigt die Attraktivität des Standorts Freiberg nicht nur als Forschungspartner der TU Bergakademie Freiberg, sondern auch hinsichtlich der Zusammenarbeit mit sächsischen, nationalen und internationalen Partnern aus Wissenschaft und Wirtschaft.

Jedes technische Gerät, das in unserer Gesellschaft eingesetzt wird, benötigt Materialien, die entweder aus unserer natürlichen Umwelt („Primärrohstoffe“)
oder aus der Wiederverwendung von Materialien in bestehenden Produkten (Recycling, „Sekundärrohstoffe“) gewonnen werden. Darüber hinaus nimmt die von der Industrie benötigte Materialmenge in dem Maße zu, wie der menschliche Reichtum und die Bevölkerung wachsen. Selbst in einer Kreislaufwirtschaft müssen die Bodenschätze die Sekundärrohstoffe ergänzen und eine grundlegende Basis für unseren materiellen Wohlstand bilden. Natürlich stellen die Gewinnung von Primärrohstoffen, die Notwendigkeit eines effizienteren Recyclings und die Entsorgung von Abfällen, die nicht effizient genutzt oder recycelt werden können, unsere Gesellschaft vor große und komplexe Herausforderungen. Zum Beispiel sind Rohstoffe für die Herstellung
von Batterien, die eine Schlüsseltechnologie für den Energiewandel darstellen, unerlässlich. Während in den kommenden Jahren mit einem exponentiellen Anstieg der Nachfrage nach Batterien gerechnet wird, war die Entwicklung einer wettbewerbsfähigen und lebensfähigen Batterieherstellungsindustrie noch nie so wichtig wie heute, und in ihrem Kern die Versorgung mit sogenannten „kritischen“ Metallen. Auf der anderen Seite steht die starke Nachfrage nach Rohstoffen in unserer postindustriellen Gesellschaft im Gegensatz zu den zunehmenden Schwierigkeiten bei der Suche und Erschließung neuer Mineralvorkommen.

Die Flotation, ein Trennprozess basierend auf der unterschiedlichen Benetzbarkeit von Mikropartikeln und wichtigster Vertreter der Heterokoagulationstrennprozesse, erwuchs seit Ende des 19. Jahrhunderts zu einem der bedeutesten Aufbereitungsprozesse für verschiedenste Erztypen. Es wird sogar davon ausgegangen, dass ohne die Flotation die Versorgung des wachsenden Bedarfs vieler wichtiger Rohstoffe, z. B. Kupfer, gegen Mitte des 20. Jahrhunderts zum Erliegen gekommen wäre. Freiberg war bis zu Zeiten der deutschen Wiedervereinigung ein weltweit führender Standort in der Flotationsforschung sowohl in ihren Grundlagen als auch für die industrielle Anwendung. Mit der Gründung des Helmholtz-Instituts Freiberg für
Ressourcentechnologie (HIF) des Helmholtz-Zentrums Dresden-Rossendorf (HZDR) an der TU Bergakademie Freiberg im Jahr 2011 wurde begonnen, diese Kernkompetenz in Freiberg und Dresden wiederaufzubauen. In diesem Artikel werfen wir einen Blick auf den regional historischen Bezug zum Flotati-
onsprozess und dessen Erforschung, beschreiben den Neuaufbau der Flotationsforschung von 2011 bis heute, stellen das wichtige vom HZDR koordinierte EU-Projekt „FineFuture“ vor und geben einen Einblick in die aktuellen Forschungsakzente im Bereich Flotation.

Mit dem regionalen Verbundvorhaben "rECOmine - Ressourcenorientierte Umwelttechnologien für das 21. Jahrhundert" beteiligen sich die TU Bergakademie Freiberg und das Helmholtz-Institut Freibger für Ressourcentechnologie (HIF) gemeinsam mit weiteren Partnern am BMBF-Programm "WIR! - Wandel durch Innovation in der Region". Mit diesem Programm sollen durch die Förderung regionaler themenbezogener Innovationscluster Leuchttürme für den Strukturwandel geschaffen werden, von denen Impulse für die wirtschaftliche Entwicklung ganzer Regionen ausgehen, wobei in der aktuellen Ausschreibung der Fokus vor allem bei den strukturschwachen ländlichen Regionen in Ostdeutschland liegt. Von ursprünglich 105 eingereichten Konzepten wurden 32 Vorhaben mit besonders guten Erfolgsaussichten ausgewählt und aufgefordert, sich mit entsprechend fundierten Innovationskonzepten für eine Förderung im Umfang von bis zu 15 Mio. EUR zu bewerben, darunter auch das Bündnis rECOmine.

Recycling ist eine wichtige Komponente der Kreislaufwirtschaft, um Ressourcen zu schonen. Auch die Biologie wird dazu zukünftig ihren Beitrag leisten. Dabei steht das Recycling von Edelmetallen und Seltenen Erdelementen (SEE), welche in Elektronikprodukten verbaut sind, im Mittelpunkt eines Forschungszweiges der Abteilung Biotechnologie am Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF). Die Wissenschaftler erforschen biologie-basierte Prozesse zum Recycling wirtschaftsstrategischer Metalle aus z. B. Smartphones oder Windturbinen. Ziel der Forschung ist es, Bioreagenzien für Flotationsverfahren – also die Aufbereitung feinster Teilchen – zu entwickeln. Die Phagen, also Viren die Bakterien als Wirtsorganismus nutzen, liefern dabei die erforderliche Materialspezifität und Affinität, um die Metalle selektiv aus einem Materialgemisch abzutrennen und gleichzeitig den bisher notwendigen Einsatz giftiger Trennchemikalien zu reduzieren.

Im Jahr 2018 feiert die Stadt Freiberg das 850. Jubiläum des ersten Silberfundes im Jahre 1168. Dieses Ereignis gilt als Auslöser für den intensiven Bergbau im Freiberger Distrikt, der von 1168 bis 1969 andauerte. Trotz des langanhaltenden Silberabbaus ist das Ressourcenpotential des Freiberger Distriktes keineswegs erschöpft, da die meisten Bergbaubetriebe aus politischen, technischen oder auch ökonomischen Faktoren eingestellt wurden und nicht etwa deswegen, weil kein Erz mehr vorhanden gewesen sei. Die aktuelle Explorationstätigkeit von Globex Mining Inc. in den nördlichen Randgebieten verdeutlicht dieses Potential (http://www.globexmining.com).
Neben dem Bergbau und der damit verbundenen sozio-ökonomischen Bedeutung für die Region war der Silberbergbau maßgeblicher Grund für die Entstehung und Entwicklung der TU Bergakademie Freiberg (TUBAF) in 1756. Auch die Entstehung der Lagerstättenforschung als wissenschaftliche Fachrichtung ist letztlich eine Konsequenz des ersten Silberfundes. Speziell in Bezug auf die Lagerstättenforschung im Freiberger Distrikt sind Werner (1791), Breithaupt (1849), von Cotta (1850), Müller (1901) und Baumann (1965) zu nennen, wobei von Cotta (1850) das weltweit erste Buch zur Lagerstättenforschung als Fach- und Lehrrichtung verfasste. Ohne die Leistung dieser Vorreiter schmälern zu wollen, sind deren Arbeiten überwiegen beschreibend, was dem damaligen Kenntnisstand und den begrenzten analytischen Möglichkeiten entsprach. Gerade weil viele der Bergwerke heute nicht mehr für die Beprobung zugänglich sind, bilden diese beschreibenden Arbeiten dennoch ein essentielles Fundament des Wissens für moderne Forschungsprojekte. Ziel aktueller Forschungsarbeiten ist es, die geologischen Bildungsbedingungen (Druck, Temperatur, Zusammensetzung der erzbildenden hydrothermalen Lösungen), Bildungsprozesse (Quelle, Transport und Ausfällung) und absoluten Alter der jeweiligen Mineralisationsphasen genauer zu bestimmen. Es sind eben diese Kenntnisse, die dazu dienen, genetische Modelle für den Freiberger Distrikt zu entwickeln. Letztere sind die Grundlage für eine erfolgreiche Neubewertung und Neuerkundung (McCuaig et al., 2010; Occhipinti et al., 2016).
Die Professur für Lagerstättenlehre und Petrologie der TU Bregakademie Freiberg und das Helmholtz-Institut Freiberg für Ressourcentechnologie haben mehrere gemeinsame Forschungsprojekte ins Leben gerufen, die die eklatanten Wissenslücken zur Genese des Freiberger Distrikts schließen wollen. Mit sorgfältig angelegten Studien und modernen Analyseverfahren soll das Verständnis der Entstehung der Freiberger Gänge auf einen aktuellen Forschungsstand gebracht werden. Konkret wird dabei ein starker Fokus auf die Analyse von Flüssigkeitseinschlüssen, Haupt- und Spurenelementanalysen von Erzmineralen und die Altersbestimmung von Erz- und Begleitmineralen (radiogene Isotopenanalysen) gelegt.

Obwohl Europa über ein enormes Innovationspotenzial verfügt, entstehen besonders im Rohstoffsektor nur wenige Start-up-Unternehmen. Neuartige Technologien und Prozesse schaffen – trotz exzellenter Forschung – zu selten den Sprung auf den Markt. Zwar stehen den meisten Start-ups in der frühen Entwicklungsphase öffentliche Fördermittel, wie z. B. Gründer-Fonds, zur Verfügung, doch fehlt ihnen danach oft das nötige Geld für den entscheidenden Wachstumsschub hin zu einer kapitalmarktbasierten Eigenfinanzierung. Häufig wird diese Phase als „Tal des Todes“ bezeichnet. Ein Unternehmen, das sie überlebt, erhält Zugang zu einem Markt, der Investoren bereithält, die voraussichtlich tragfähige Geschäftsmodelle im Weiteren unterstützen.
Damit mehr Start-up-Unternehmen zukünftig dieses Tal des Todes überwinden und so das Innovationspotenzial des europäischen Rohstoffsektors auch ausgeschöpft werden kann, wollen 115 europäische Partner – zu denen das zum Helmholtz-Zentrum Dresden-Rossendorf gehörige Helmholtz-Institut Freiberg für Ressourcentechnologie und die TU Bergakademie Freiberg zählen – gemeinsam einen wichtigen Paradigmenwechsel anstoßen. Wettbewerbsfähigkeit, Wachstum und Attraktivität des europäischen Rohstoffsektors sollen durch radikale Innovation, aber auch Unternehmergeist gesteigert werden. Ziel ist es, diesen wichtigen Industriesektor zu einer strategischen Säule der Wirtschaft der EU zu machen. Das Europäische Institut für Innovation und Technologie (EIT) – eine Organisation der EU – teilt diese Vision. Es hat deshalb Anfang Dezember 2014 ein Konsortium, koordiniert vom Helmholtz-Zentrum Dresden-Rossendorf und von der Fraunhofer-Gesellschaft, damit beauftragt, eine Wissens- und Innovationsgemeinschaft (Knowledge and Innovation Community, KIC) für den Rohstoffsektor zu etablieren. Das neue KIC trägt den Namen „EIT Raw Materials“. Es bringt Unternehmen und Forschungseinrichtungen aus 22 EU-Mitgliedsstaaten unter einem Dach zusammen. Damit ist EIT Raw Materials das größte Rohstoffnetzwerk der Welt, das
auf ideale Weise ein für alle KIC charakteristisches Wissensdreieck aus Ausbildung, Forschung und Industrie erzeugt. Durch seine enorme Anzahl von Partnern verfügt das Netzwerk über Kompetenzen aus dem gesamten Spektrum des Wissens und Forschens über die mineralischen und metallhaltigen Rohstoffe und deckt alle Glieder der Rohstoff-Wertschöpfungskette vollständig ab – von der Erkundung über die Aufbereitung bis hin zu Recycling und
der Substitution von Ressourcen. Diesen strategischen Vorteil will das Institut dazu nutzen, um Barrieren, die die Zusammenarbeit zwischen Hochschulen, Forschungseinrichtungen und Unternehmen behindern, zu überwinden. Auf diese Weise soll der Dialog zwischen den involvierten Potenzialen und Bereichen vor allem durch Verständigung über jeweils anzugehende Ziele sowie durch den Austausch von Ideen und Forschungsergebnissen vereinfacht werden. Nur so kann sich der europäische Rohstoffsektor und können sich auch die an ihn angrenzenden Branchen in einen Wachstumsmarkt für
Investitionen, Innovationen und talentierte Entrepreneure verwandeln. Damit dies gelingt, müssen sich Politiker, Unternehmer und Wissenschaftler
darüber im Klaren sein, welche Herausforderungen der europäische Rohstoffsektor zu bewältigen hat. Denn im Vergleich zu Ländern wie China, Russland oder den USA ist die EU bei der Versorgung mit existenziell wichtigen mineralischen und metallischen Rohstoffen noch deutlich stärker vom globalen Handel abhängig. Eine der wichtigsten Aufgaben des EIT Raw Materials wird es deshalb sein, neue ökonomisch und ökologisch fundierte Konzepte
zu entwickeln: für die Nutzung heimischer Lagerstätten, den Bergbau unter schwierigen, oft urbanen Bedingungen – ebenso wie für den Ausbau einer wettbewerbsfähigen rohstoffverarbeitenden und sonstigen rohstoffnahen Industrie. Eine weitere Herausforderung wird sein, mit neuen Technologien und Nutzungskonzepten den Weg für eine effiziente und nachhaltige Kreislaufwirtschaft zu ebnen. Ausgediente Hightech-Produkte etwa, wie Smartphones oder Laptops, dürfen nicht mehr als Müll angesehen werden, sondern vielmehr als Quelle für die Rückgewinnung wertvoller Rohstoffe.
Um diese und weitere Aufgaben meistern zu können, gilt es, alle Partner des KIC optimal miteinander zu verknüpfen. In lokalen Zentren, den sog. Co-Location Centers (CLC), bündelt das Netzwerk dafür transnationale Regionen mit thematischen Schwerpunkten. Insgesamt gibt es sechs solcher Zentren, und zwar in Italien, Frankreich, Polen, Belgien, Finnland und Schweden. Das EIT Raw Materials koordiniert sie von seinem Hauptsitz in Berlin aus. Die deutschen Partner beteiligen sich an den drei CLC in Frankreich, Belgien und Polen.

Indium, ein silberfarbenes, weiches, dem Zinn sehr ähnliches Metall, hat eine ganz besondere Beziehung zu Freiberg: nicht nur, dass es im Jahr 1863 von Reich und Richter an der Bergakademie entdeckt wurde; auch das für die Arbeit der beiden Entdecker verwendete Probenmaterial entstammte dem lokalen
Bergbau. Heutzutage kommt Indium große Bedeutung als einem der wichtigsten Hochtechnologiemetalle zu, ohne das der weltweit verbreitete Einsatz von Smartphones und Flachbildschirmen nicht möglich wäre. Gewonnen wird es hauptsächlich als Beiprodukt aus Zinkund untergeordnet auch aus Kupfererzen. D. h. es gibt keine Indiumbergwerke, sondern Indium wird bei der Verhüttung der Erze dieser beiden Hauptmetalle gewonnen. Da aber der Wert des in den Erzen enthaltenen Indiums oft sehr viel geringer ist als der der Hauptmetalle (< 10 %), hat seine Konzentration keinen Einfluss darauf, welche Erze abgebaut werden. Das führt dazu, dass die weltweit zur industriellen Verfügung stehende Menge an Indium letztendlich durch den Umfang der (Kupfer- und) Zinkproduktion begrenzt ist. Diese Limitation erzeugt ein großes pozenzielles Versorgungsrisiko. Indium ist damit ein typisches Beispiel eines Hochtechnologiemetalls, das ausschließlich als Beiprodukt gewonnen werden kann.
Am Beispiel der polymetallischen Lagerstätte Neves-Corvo in Portugal soll in diesem Beitrag dargestellt werden, welche Informationen zur Verfügung stehen müssen, um die Nutzung von Beiprodukten – wie eben von Indium – zu ermöglichen. Die Lagerstätte Neves-Corvo beherbergt mit einem zzt. noch verbliebenen Gesamtinhalt von > 1.000 t Indium die größte bekannte Konzentration dieses Elements in einer abbauwürdigen Lagerstätte in Europa. Jedoch profitiert das Unternehmen Somincor, das die Lagerstätte Neves-Corvo abbaut, momentan nicht von diesem Reichtum: Die in Neves-Corvo produzierten Cu- und Zn-Konzentrate erreichen in der Regel nicht die von den Hütten für die Vergütung verlangten Indium-Mindestgehalte. Ziel der in diesem Artikel beschriebenen Arbeit ist es, auf geometallurgischen Untersuchungen aufbauend Nutzungskonzepte zu entwickeln, die dem Unternehmen bei der vollen
Ausschöpfung seines Indiumpotenzials helfen können. Die dazu durchgeführte Studie ist – unseres Wissens – die weltweit erste ausführliche geometallurgische Studie zur Konzentrationsverteilung und Gewinnbarkeit von Indium als Beiprodukt. Da diese Studie noch nicht abgeschlossen ist, werden im Folgenden nur vorläufige Ergebnisse präsentiert.

Metal aerogels (MAs) are emerging porous materials displaying unprecedented potential in catalysis, sensing, plasmonic technologies, etc. However, the lack of efficient regulation of their nano-building blocks (NBBs) remains a big hurdle that hampers the in-depth investigation and performance enhancement. Here, by harmonizing composition and ligand effects, Pt- and Bi-based single- and bimetallic aerogels bearing NBBs of controlled dimensions and shapes are obtained by facilely tuning the metal precursors and the applied ligands. Particularly, by further modulating the electronic and optic properties of the aerogels via adjusting the content of the catalytically active Pt component and the semiconducting Bi component, both the electrocatalytic and photoelectrocatalytic performance of the Pt–Bi aerogels can be manipulated. In this light, an impressive catalytic performance for electro-oxidation of methanol is acquired, marking a mass activity of 6.4-fold higher under UV irradiation than that for commercial Pt/C. This study not only sheds light on in situ manipulating NBBs of MAs, but also puts forward guidelines for crafting high-performance MAs-based electrocatalysts and photoelectrocatalysts toward energy-related electrochemical processes.

Compared to the lanthanides, which primarily exhibit the oxidation state +III, the early actinides up to plutonium can display a diverse range of oxidation states spanning from +I to +VII. In the context of exploring oxidation states and covalency of actinides complexes, it would be intriguing and valuable to compare compounds that share the same molecular scaffold but differ in their oxidation states. Amidinate ligands have been widely studied in the field of coordination chemistry due to their excellent capability to stabilize transition metal complexes in various oxidation states, including some early actinide metal complexes. Thus, N,N'-diisopropylbenzamidinate (iPr2BA) was selected as an appropriate model N-donor ligand for the current study. Our goal was to test the ligand’s ability to stabilize actinides in various oxidation states as well as its synthetic flexibility.
In order to gain insight into the bonding trends and electronic structures of each oxidation state, series of tetravalent actinide tris-iPr2BA chloride complexes [AnIVCl(iPr2BA)3] (An = Th, U, Np) were synthesized via salt metathesis, followed by subsequent synthetic transformations to obtain (pseudo)halide congeners and complexes in the +III and +V oxidation states. The synthesized complexes were analyzed by single crystal X-ray diffraction (SC-XRD) to examine their molecular structures in solid state. Furthermore, the combination of paramagnetic NMR experiments in solution and quantum chemical calculations enabled the comparison of the overall degree of covalency between different oxidation states within the same tris-amidinate complex scaffold.

Octa- and specifically nonadentate ligands with a bispidine scaffold (3,7-diazabicyclo[3.3.1]nonane) are known to be efficiently coordinated to a range of metal ions of
interest in radiopharmaceutical chemistry and lead to exceedingly stable and inert complexes. The nonadentate bispidine L2 (with a tridentate bipyridine acetate appended to N3 and a
picolinate at N7) has been shown before to be an ideal chelator for 111In3+, 177Lu3+ and 225Ac3+, nuclides of interest for diagnosis and therapy, and a proof-of-principle study with an SSTR2-specific octreotate has shown potential for theranostic applications. We now have extended these studies in two directions. Firstly, we present the ligand derivative L3, where the bipyridine acetate is substituted with terpyridine, a softer donor for metal ions with a preference for more covalency. L3 did not fulfill the hopes because complexation is much less efficient: while for Bi3+ and Pb2+ the ligand is an excellent chelator with similar properties to L2, Lu3+ and La3+ show very slow and inefficient complexation with L3 in contrast to L2, and 225Ac3+ is not fully coordinated, even at an elevated temperature (92% radiochemical yield (RCY) at 80 °C, 60 min, [L3] = 10-4 M). These observations have led to a hypothesis for the complexation pathway that is in line with all experimental data and supported by a preliminary DFT analysis, which is of importance for the design of further optimized bispidine chelators. Secondly, the coordination chemistry of L2 has been extended to Bi3+, La3+ and Pb2+, including solid state and solution structural work, complex stabilities, radiolabeling and radiostability studies. All complexes of this ligand (La3+, Ac3+, Lu3+, Bi3+, In3+, Pb2+), including nuclides for targeted alpha therapy (TAT), single photon emission computed tomography (SPECT), and positron emission tomography (PET) are formed efficiently at physiological conditions, i.e., suitable for the labeling of delicate biological vectors such as antibodies, and the complexes are very stable and inert. Importantly, for TAT with 225Ac, the daughter nuclides 213Bi and 209Pb also form stable complexes, and this is of importance to reduce damage to healthy tissue.

Prozesse wie sie in großen Behältern, etwa in Biogasfermentern, Biorektoren oder Belebtschlammbecken ablaufen, haben ein hohes Optimierungspotenzial hinsichtlich der Energieeffizienz der Vermischung. Schlechtes Mischen im Behälter führt zu zu Totzonen und einer ineffizienten Nutzung der eingetragenen Energie. Messungen in diesen Behältern sind aufgrund des opaken Fluids und der Größe und Beschaffenheit der Behälter mit konventioneller Messtechnik nur an lokalen Messstellen möglich. Um ortsaufgelöst Prozessparameter und die Strömung zu messen, wurde am HZDR das Konzept instrumentierter, strömungsfolgender Sensorpartikel entwickelt. Strömungsfolgende Sensoren werden derzeit von einigen Gruppen weltweit entwickelt. Ausgestattet sind sie mit mindestens einem Druck– und einem Temperatursensor. Auswerteschwerpunkt ist die vertikale Position (Tauchtiefe) im Behälter basierend auf einer Messung des hydrostatischen Drucks. Analysiert werden typischerweise vertikale Aufenthaltswahrscheinlichkeiten, vertikale Geschwindigkeitsprofile, Zirkulationszeiten, aus denen ein Zusammenhang mit der globalen Mischzeit des Reaktors hergestellt wird, sowie ein automatisiertes Einteilen des Behälters in vertikale Mischbereiche als neueste Analysemethode.

GeSn alloys hold great promise as high-performance, low-cost, near- and short-wavelength infrared photodetectors with the potential to replace the relatively expensive and currently market-dominant InGaAs- and InSb-based photodetectors. In this Letter, we demonstrate room-temperature GeSn pn photodetectors fabricated by a complementary metal-oxide-semiconductor compatible process, involving Sn and P ion implantation and flash-lamp annealing prior to device fabrication. The fabrication process enables the alloying of Ge with Sn at concentrations up to 4.5% while maintaining the high-quality single-crystalline structure of the material. This allows us to create Ge0.955Sn0.045 pn photodetec-tors with a low dark current density of 12.8 mA/cm2 and a relatively high extended responsivity of 0.56 A/W at 1.71 l m. These results pave the way for the implementation of a cost-effective, scalable, and CMOS-compatible short-wavelength infrared detector technology.

Using the external field method, {\it i.e.\/} evaluating the effective action $V_{\mathrm{eff}}$ for an arbitrarily strong constant and homogeneous field, we explore nonperturbative properties of QED allowing arbitrary gyromagnetic ratio $g$. We find a cusp at $g = 2$ in: a) The QED $b_0$-renormalization group coefficient, and in the infinite wavelength limit in b) a subclass containing the pseudoscalar ${\cal P}^{2n}= (\vec E\cdot\vec B)^{2n} $ of light-light scattering coefficients. Properties of $b_0$ imply for certain domains of $g$ asymptotic freedom in an Abelian theory.

We study the impact of axions or axion-like particles on birefringent (i.e., polarization changing) scattering of x-ray photons at the Coulomb field of nuclei superimposed by optical lasers of ultra-high intensity. Applying the specifications of the Helmholtz International Beamline for Extreme Fields (HIBEF), we find that this set-up can be more sensitive than previous experiments such as PVLAS in a large domain of parameter space. Furthermore, by changing the pump and probe laser orientations and frequencies, one can scan different axion masses.

We implement a longstanding proposal by Weisskopf to apply virtual polarization corrections to
the in/out external fields in study of the Euler-Heisenberg-Schwinger effective action. Our approach
requires distinguishing the electromagnetic and polarization fields based on mathematical tools
developed by Bia lynicki-Birula, originally for the Born-Infeld action. Our solution is expressed
as a differential equation where the one-loop effective action serves as input. As a first result of
our approach, we recover the higher-order one-cut reducible loop diagrams discovered by Gies and
Karbstein.

On May 9, 2023, the Helmholtz Open Science Office organized the Forum "Research Evaluation, Reputation Systems, and Openness". On this occasion, experts from Helmholtz and the scientific community presented current developments in the field of research evaluation and reflected on the connection between reputation systems and openness. The event focused on three main topics: 1) Development of Helmholtz quality indicators for data and software products, 2) 10 years Declaration on Research Assessment (DORA) and 3) Coalition for Advancing Research Assessment (CoARA). A central subject in the discussion and presentations was the issue of the use and definitions of indicators which foster Open Science. The discussion centered on what appropriate incentives look like in order to make research evaluation fair and appreciative. Furthermore, the relevance of these questions from the perspective of early-career scientists was highlighted.

Multiphase computational fluid dynamics (CFD) simulation is a useful tool to study the hydrodynamics in a bubble column if
appropriate closure models are known. Systematic assessment of different models is an ongoing venture that benefits from
improved validation data. The present study accumulates a database on two-phase flow experiments in a bubble column.
This is achieved by using a combination of particle image velocimetry and shadowgraphy to measure the liquid velocity field
and gas dispersion properties simultaneously. This methodology is applied for different needle diameters and gas flow rates.
The experimental data are compared with CFD simulations which show good predictions. A systematic investigation of the
three-phase flow in the bubble column will appear as a sequel.

The SPEChpc™ 2021 suites are application-based benchmarks de-
signed to measure performance of modern HPC systems. The bench-
marks support MPI, MPI+OpenMP, MPI+OpenMP target offload,
MPI+OpenACC and are portable across all major HPC platforms.

With the development of advanced biomedical theragnosis and bioengineering tools, smart and soft responsive microstructures and nanostructures have emerged. These structures can transform their body shape on demand and convert external power into mechanical actions. Here, we survey the key advances in the design of responsive polymer−particle nanocomposites that led to the development of smart shapemorphing microscale robotic devices. We overview the technological roadmap of the field and highlight the emerging opportunities in programming magnetically responsive nanomaterials in polymeric matrixes, as magnetic materials offer a rich spectrum of properties that can be encoded with various magnetization information. The use
of magnetic fields as a tether-free control can easily penetrate biological tissues. With the advances in nanotechnology and manufacturing techniques, microrobotic devices can be realized with the desired magnetic reconfigurability. We emphasize that future fabrication techniques will be the key to bridging the gaps between integrating sophisticated functionalities of
nanoscale materials and reducing the complexity and footprints of microscale intelligent robots.

Silicon layers with a selenium impurity concentration up to 1021 cm–3, which exceeds the equilibrium solubility limit of this
impurity in silicon by four orders of magnitude, were obtained by high-dose ion implantation followed by pulsed laser
annealing at pulse energy densities from 0.5 to 2.5 J/cm2. Rutherford backscattering of He+ ions showed that up to 70% of
the implemented impurity atoms were localized at silicon crystal-lattice sites after laser annealing. The Se-hyperdoped Si
layers were characterized by increased (up to 45–55%) absorption in the spectral range 1100–2400 nm. Thermal treatment
(550°C for 30 min followed by 850°C for 5 min) did not increase the IR absorption as compared with the initial Si, which was
explained by Se losses resulting from diffusional redistribution. Recrystallization of Si layers amorphized by Se ions and
redistribution of the dopant with equilibrium thermal treatment were theoretically evaluated.

This work demonstrates the novel concept of a mixed-dimensional reconfigurable field effect transistor (RFET) by combining a one-dimensional (1D) channel material such as a silicon (Si) nanowire with a two-dimensional (2D) material as a gate dielectric. An RFET is an innovative device that can be dynamically programmed to perform as either an n- or p-FET by applying appropriate gate potentials. In this work, an insulating 2D material, hexagonal boron nitride (hBN), is introduced as a gate dielectric and encapsulation layer around the nanowire in place of a thermally grown or atomic-layer-deposited oxide. hBN flake was mechanically exfoliated and transferred onto a silicon nanowire-based RFET device using the dry viscoelastic stamping transfer technique. The thickness of the hBN flakes was investigated by atomic force microscopy and transmission electron microscopy. The ambipolar transfer characteristics of the Si-hBN RFETs with different gating architectures showed a significant improvement in the device’s electrical parameters due to the encapsulation and passivation of the nanowire with the hBN flake. Both n- and p-type characteristics measured through the top gate exhibited a reduction of hysteresis by 10–20 V and an increase in the on–off ratio (ION/IOFF) by 1 order of magnitude (up to 108) compared to the values measured for unpassivated nanowire. Specifically, the hBN encapsulation provided improved electrostatic top gate coupling, which is reflected in the enhanced subthreshold swing values of the devices. For a single nanowire, an improvement up to 0.97 and 0.5 V/dec in the n- and p-conduction, respectively, is observed. Due to their dynamic switching and polarity control, RFETs boast great potential in reducing the device count, lowering power consumption, and playing a crucial role in advanced electronic circuitry. The concept of mixed-dimensional RFET could further strengthen its functionality, opening up new pathways for future electronics.

During pandemics like COVID-19, both the quality and quantity of services offered by businesses and organizations have been severely impacted. They often have applied a hybrid home office setup to overcome this problem, although in some situations, working from home lowers employee productivity. So, increasing the rate of presence in the office is frequently desired from the manager's standpoint. On the other hand, as the virus spreads through interpersonal contact, the risk of infection increases when workplace occupancy rises.
Motivated by this trade-off, in this paper, we model this problem as a bi-objective optimization problem and propose a practical approach to find the trade-off solutions. We present a new probabilistic framework to compute the expected number of infected employees for a setting of the influential parameters, such as the incidence level in the neighborhood of the company, transmission rate of the virus, number of employees, rate of vaccination, testing frequency, and rate of contacts among the employees. The results show a wide range of trade-offs between the expected number of infections and productivity, for example, from 1 to 6 weekly infections in 100 employees and a productivity level of 65\% to 85\%. This depends on the configuration of influential parameters and the occupancy level.
We implement the model and the algorithm and perform several experiments with different settings of the parameters. Moreover, we developed an online application based on the result in this paper which can be used as a recommender for the optimal rate of occupancy in companies/workplaces.

The new benchmark for VVER-1000 control rod ejection transient was published recently. One of the assumptions proposed in the benchmark is given fixed values for fuel-cladding gas gap thermal conductivity and thermo-physical properties of fuel and cladding materials. In this paper, authors investigate an impact of this assumption on simulation results.

Unraveling the metal sources of Zn-Pb deposits is vital to understand the genetic types and ore-forming processes. The Sichuan-Yunnan-Guizhou metallogenic province (SYGMP) hosts abundant Zn-Pb deposits that are variably rich in critical metals such as Ga, Ge, Cd and Tl. However, sources of these critical metals and main metal Zn are still unclear. The Liangyan Cd-rich Zn-Pb deposit as a representative in the SYGMP is hosted in a carbonate sedimentary sequence and controlled by the regional Yadu-Wogong anticline and Yadu-Mangdong thrust fault. SZn-Cd isotopes of sulfide minerals from this deposit are obtained in order to understand the sources of metals and origin of the deposit. Sulfur isotopic results of pyrite and sphalerite reveal that sulfur was produced by thermochemical sulfate reduction (TSR) of sulfates from the Carboniferous dolostone and mudstone and the Ediacaran-Devonian carbonates. Sphalerite grains have δ66ZnJMC values that are negatively correlated with the δ114Cd spex values, implying different sources for both Zn and Cd. The variation trend of δ66ZnJMC and Cd/Zn
suggests that Zn was mainly sourced from the Neoproterozoic basement with minor from the Carboniferous wallrocks. Besides, sphalerite grains show a negative correlation between δ114Cdspex and Zn/Cd, and these values fall in the field close to the Carboniferous carbonates, but away from the Permian Emeishan basalts, indicating that Cd was derived mainly from the Carboniferous wallrocks with minor from the Emeishan basalts. Together with geological evidence, the multi-isotope data suggest that the Liangyan deposit belongs to a thrust-controlled MVT Zn-Pb deposit.

Following several previous European projects (EFR, CP-ESFR and ESFR-SMART), a new project ESFR-SIMPLE has been proposed in response to the HORIZON-EURATOM call on “Safety of advanced and innovative nuclear designs and fuels”. The new project aims at challenging the Generation IV ESFR (European Sodium Fast Reactor) designed in the ESFR-SMART project, to improve its safety and economics thanks to innovative technologies. The project high-level objectives and actions are: 1) Challenge the ESFR design to simplify the reactor, through reducing its size, which could allow taking advantage of SMRs (Small Modular Reactors) in terms of transportability, modularization, standardization, flexible operation and machine learning, all ultimately leading to improved economics. 2) Propose, develop and assess advanced methods of monitoring and processing operational data using Artificial Intelligence, e.g., to optimize fault detection in the steam generators at an early stage. 3) Produce new experimental data in order to support calibration and validation of the computational tools such as properties measurements of irradiated and non-irradiated MOX fuel including fuel with optimized micro-structures, and to assist in qualification of innovative components, such as expansion bellows, thermo-electric pumps and accident tolerant core-catcher. 4) Assess alternative technologies, such as the use of metallic fuel and compact secondary system design, for the large-size ESFR to improve the economics and safety. 5) Ensure that the knowledge generated in the project will be shared not only among the project partner institutions, but also among as wide a range of stakeholders as possible in Europe and internationally. The project relies on a consortium of 16 partners and will benefit from different skills and experiments available in Europe and in the US. It started in October 2022 and will end in September 2026. In addition to the technical details, this paper also briefly outlines the organization of the project.

The rate of the final step in the astrophysical αp process, the 34Ar(α,p)37K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. We present the first direct measurement constraining the 34Ar(α,p)37K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the 34Ar,Cl(α,p)37K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The 34Ar(α,2p)36Ar cross section, which can be exclusively attributed to the 34Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.

Artificial intelligence (AI) is proliferating and developing faster than any domain scientist can adapt. To support the scientific enterprise in the Helmholtz association, a network of AI specialists has been set up to disseminate AI expertise as an infrastructure among domain scientists. As this effort exposes an evolutionary step in science organization in Germany, this article aspires to describe our setup, goals, and motivations. We comment on past experiences, current developments, and future ideas as we bring our expertise as an infrastructure closer to scientists across our organization. We hope that this offers a brief yet insightful view of our activities as well as inspiration for other science organizations.

Background:

Decreased cerebral blood flow (CBF) and deterioration of blood-brain barrier (BBB) are suggested to be precursor conditions of cognitive impairment. Using a novel multi-echo-time arterial spin labelling (ASL) protocol, we examined the time of exchange (Tex) of water across the BBB as a measurement of BBB permeability. We further examined the association of cardiovascular risk factors with Tex in an ongoing cohort study.
Method:
Data (n=29, mean age: 55.9±6.1years, 69% women) were drawn from Neurological biomarkers of Blood, MRI and Cognition (NEURO-BMC) study performed at National University of Singapore. NEURO-BMC is an ongoing prospective cohort study (age: 45-65 years) on brain changes in a subclinical phase of cognitive impairment. A multi-echo, Hadamard-encoded multi-post-labelling-delay pseudo-continuous ASL (PCASL) protocol was used on a 3T scanner. ExploreASL was used with a modified version of FSL FABBER(4) to quantify cerebral blood flow (CBF), arterial transit time (ATT), and Tex. ASL-extracted parameters were compared with cardiovascular risk parameters such as blood pressure (BP), BMI and smoking status.
Result:
High systolic and diastolic BP were associated with significantly reduced Tex (Fig 1). Additionally, higher systolic and diastolic BP showed a trend of increased ATT and reduced CBF, though the associations were not statistically significant (Table 1). High BMI had a significant association with increased ATT and reduced CBF. However, no trend was observed between BMI and Tex. Participants who ever smoked were observed to have a reduced Tex and CBF and increased ATT, but statistical significance was only found for CBF (Fig 1).
Conclusion:
In this pilot study, we showed that BBB-ASL-derived parameters - ATT, CBF, and Tex - were associated with BP, BMI, and smoking status. While the sample size for this preliminary analysis was too small to make a definitive conclusion as not all associations were statistically significant, all studied cardiovascular risk factors showed their potential in increasing the risk of BBB deterioration. Further investigation with a larger sample size and other health risk factors to assess these observations is warranted.

This study aimed to verify and validate the transient simulation capability of the hybrid code system RAST-F for fast reactor analysis. For this purpose, control rod (CR) drop experiments of eight CRs and six control groups in the China Experimental Fast Reactor (CEFR) start-up tests were utilized to simulate the CR drop transient. The RAST-F numerical solution, including the neutron population, time-dependent reactivity, and CR worth, was compared against the measurement values obtained from two out-of-core detectors. Moreover, the time-dependent reactivity and CR worth from RAST-F were verified against the results obtained by the Monte Carlo code Serpent using continuous energy nuclear data. A code-to-code comparison between Serpent and RAST-F showed good agreement in terms of time-dependent reactivity and CR worth. The discrepancy was less than 160 pcm for reactivity and less than 110 pcm for CR worth. RAST-F solution was almost identical to the measurement data in terms of neutron population and reactivity. All the calculated CR worth results agreed with experimental results within two standard deviations of experimental uncertainty for all CRs and control groups. This work demonstrates that the RAST-F code system can be a potential tool for analyzing time-dependent phenomena in fast reactors.

Room temperature ferromagnetism has been reported in chemical vapor deposition-grown mixed-phase MoS2-MoOx thin films after Xe ion irradiation. Magnetic moment has significantly been enhanced after ion irradiation. Deterioration in crystallinity after ion irradiation has been shown by X-ray diffraction and Raman spectroscopy measurements. The variation in the surface morphology and/or formation of edge states can be observed by secondary electron microscopy images. The reduction in the oxygen vacancy concentration, probed by analysis of the O 1s core level X-ray photoelectron spectrum for the film with the maximum magnetic moment, rules out the possibility of ferromagnetism due to oxygen vacancy. Enhancement in the Mo content in 5+ and 6+ oxidation states due to the occupation of sulfur vacancy sites by oxygen after ion irradiation, calculated from X-ray photoelectron spectroscopy core level of Mo 3d and S 2p and valence band spectra, has been observed. Density functional theory (DFT) calculations also show the one-to-one correspondence of saturation magnetic moment with Mo6+ content. So, the enhancement in the ferromagnetism in mixed-phase of MoS2-MoOx thin films is due to the increase of Mo in 6+ oxidation state and exchange interaction between the different oxidation states of Mo via p-orbital of anion and formation of edged states.

Hybrid waveguides consisting of two-dimensional layered materials pad on the surface of optical waveguides suffer from a nonuniform and loose contact between the two-dimensional material and the waveguide, which can reduce the efficiency of the pulsed laser. Here, we present high-performance passively Q-switched pulsed lasers in three distinct structures of monolayer graphene-Nd:YAG hybrid waveguides irradiated by energetic ions. The ion irradiation enables the monolayer graphene a tight contact and strong coupling with the waveguide. As a result, Q-switched pulsed lasers with narrow pulse width and high repetition rate are obtained in three designed hybrid waveguides. The narrowest pulse width is 43.6 ns, provided by the ion-irradiated Y-branch hybrid waveguide. This study paves the way toward developing on-chip laser sources based on hybrid waveguides by using ion irradiation.

Layered magnetic materials are becoming a major platform for future spin-based applications. Particularly the air-stable van der Waals compound CrSBr is attracting considerable interest due to its prominent magneto-transport and magneto-optical properties. In this work, we observe a transition from antiferromagnetic to ferromagnetic behavior in CrSBr crystals exposed to high-energy, non-magnetic ions. Already at moderate fluences, ion irradiation induces a remanent magnetization with hysteresis adapting to the easy-axis anisotropy of the pristine magnetic order up to a critical temperature of 110 K. Structure analysis of the irradiated crystals in conjunction with density functional theory calculations suggest that the displacement of constituent atoms due to collisions with ions and the formation of interstitials favors ferromagnetic order between the layers.

The sigma2 receptor (TMEM97) expression correlates well with the Ki67 expression in tumours [1, 2] and therefore represents an attractive marker for the proliferative status. We developed the 18F-labelled radioligand [18F]RM273 for sigma2 receptor imaging in brain tumours.
[18F]RM273 (2-[4-(6-[18F]fluoro-1H-pyrrolo[2,3-b]pyridin-1-yl)butyl]-6,7-dimethoxy-1,2,3,4-tetra-hydroisoquinoline) has been obtained by automated synthesis by Cu-mediated oxidative radiofluorination of the aryl boronic acid pinacol ester precursor. Radiometabolite analysis was performed in mouse plasma samples 30 min p.i. The target specificity was investigated by in vitro autoradiographic studies with or without the sigma2 receptor antagonist ISO-1 in rat brain cryosections with a stereotactically implanted F98 glioma [3]. The biodistribution of [18F]RM273 in healthy mice (female, CD1; n = 4; 7.2 ± 1.1 MBq) and the tumour uptake into the F98 glioma (male, Fischer rats; n = 2; 21 and 25 MBq) were investigated by dynamic PET imaging for 60 min (nanoScan®PET-1T MRI, Mediso).
Polar radiometabolites of [18F]RM273 (AM 69 – 233 GBq/μmol, RCY 8%) were detectable in plasma, but not in brain extracts. We determined a 3-times higher density of binding sites in tumour compared to healthy brain in vitro [3]. PET studies revealed a TAC peak value of 1.3 at 2.25 min p.i. followed by a wash out in the brain of healthy mice [3]. In the F98 glioma brain region a two times higher uptake (SUVmean of 0.8–1.3 at 30–60 min p.i.) compared to contralateral was observable. Therefore, [18F]RM273 could potentially be used to determine the proliferative status of brain tumours.
Acknowledgements: This work was supported by the Deutsche Forschungsgemeinschaft (DFG: BR 1360/13-1).
References: [1] Shoghi et al. Plos One 2013, 8: e74188; [2] Yang et al. Molecules 2020, 25 (22): 5439 [3] Moldovan et al. Int. J. Mol. Sci. 2021, 22: 5447

The long-lived and optically addressable spin states of silicon vacancies (VSi) in 4H-SiC make them promising qubits for quantum communication and sensing. These color centers can be created in both the hexagonal (V1) and in the cubic (V2) local crystallographic environments of the 4H-SiC host. While the spin of the V2 center can be efficiently manipulated by optically detected magnetic resonance at room temperature, spin control of the V1 centers above cryogenic temperatures has been elusive. Here, we show that the dynamic strain of surface acoustic waves can overcome this limitation and efficiently excite magnetic resonances of V1 centers up to room temperature. Based on the width and temperature dependence of the acoustically induced spin resonances, we attribute them to transitions between spin sublevels in the excited state. The acoustic spin control of both V1 and V2 centers in their excited states opens new ways for applications in quantum technologies based on spin-optomechanics.

Numerical Simulation of Particles in Rising Gas Bubbles

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review current application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions [4] and enables fundamentally new non-local chiral symmetry breaking effect [5,6]. Application potential of geometrically curved magnetic architectures is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics relying on thin films [7,8] as well as printed magnetic composites [9] with appealing self-healing performance [10].

Reference list
[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
[5] D. D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020).
[6] O. M. Volkov et al., Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nature Communications 14, 1491 (2023).
[7] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[8] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[9] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[10] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and temperatures---has emerged as one of the most active frontiers in plasma physics and material science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied experimentally in large facilities around the globe, and new techniques have facilitated unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical modeling, which is a notoriously difficult task [1].

In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo (PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get new insights into the behavior of WDM. This includes recent results for various density response properties [3] such as the exchange—correlation (XC) kernel [2,4], and the utility of PIMC reference data to assess the accuracy of different XC functionals [5].

Finally, I will show how switching to the imaginary-time representation allows us to significantly improve the interpretation of X-ray Thomson scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will present a model-free temperature diagnostic [6] based on the well-known principle of detailed balance, but available for all wave numbers, and a new idea to directly extract the electron—electron static structure factor from an XRTS measurement [7]. As an outlook, I will show how new PIMC capabilities [8] will allow to give us novel insights into electronic correlations in warm dense quantum plasmas, leading to unprecedented agreement between experiments [9] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] T. Dornheim et al., Physics of Plasmas 30, 032705 (2023)
[4] Zh. Moldabekov et al., Journal of Chemical Theory and Computation 19, 1286-1299 (2023)
[5] Zh. Moldabekov et al., arXiv:2308.07916 (submitted)
[6] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[7] T. Dornheim et al., arXiv:2305.15305 (submitted)
[8] T. Dornheim et al., arXiv:2308.06071 (submitted)
[9] T. Döppner et al., Nature 618, 270-275 (2023)

Nonlinear density response theory is revisited focusing on the harmonically perturbed finite temperature uniform electron gas. Within the non-interacting limit, brute force quantum kinetic theory calculations for the quadratic, cubic, quartic and quintic responses reveal a deep connection with the linear response. Careful analysis of the static long wavelength limit led us to conjecture a canonical non-interacting form that expresses arbitrary order nonlinear responses as the weighted sum of the linear responses evaluated at all multiple harmonics. This harmonic expansion is successfully validated against ab initio path integral Monte Carlo simulations.

Anhand des Beispiels Mobiltelefon wird erklärt, wie viele wertvolle Rohstoffe in elektronischen Geräten stecken und wie die Forschenden am HIF mit der Etablierung neuer (bio)technologischer Methoden dazu beitragen, dem Ziel einer geschlossenen Kreislaufwirtschaft näher zu kommen.

The objective of this study was to assess the prognostic value of asphericity (ASP) and standardized uptake ratio (SUR) in cervical cancer patients. Retrospective analysis was performed on a group of 508 (aged 55 ± 12 years) previously untreated cervical cancer patients. All patients underwent a pretreatment [18F]FDG PET/CT study to assess the severity of the disease. The metabolic tumor volume (MTV) of the cervical cancer was delineated with an adaptive threshold method. For the resulting ROIs the maximum standardized uptake value (SUVmax) was measured. In addition, ASP and SUR were determined as previously described. Univariate Cox regression and Kaplan–Meier analysis with respect to event free survival (EFS), overall survival (OS), freedom from distant metastasis (FFDM) and locoregional control (LRC) was performed. Additionally, a multivariate Cox regression including clinically relevant parameters was performed. In the survival analysis, MTV and ASP were shown to be prognostic factors for all investigated endpoints. Tumor metabolism quantified with the SUVmax was not prognostic for any of the endpoints (p > 0.2). The SUR did not reach statistical significance either (p = 0.1, 0.25, 0.066, 0.053, respectively). In the multivariate analysis, the ASP remained a significant factor for EFS and LRC, while MTV was a significant factor for FFDM, indicating their independent prognostic value for the respective endpoints. The alternative parameter ASP has the potential to improve the prognostic value of [18F]FDG PET/CT for event-free survival and locoregional control in radically treated cervical cancer patients.

The capabilities of the DYN3D/ATHLET coupled code system were recently extended to allow for 3D neutron kinetics/thermal hydraulics analyses of Sodium cooled Fast Reactors at reactor system level. In this paper, the DYN3D/ATHLET coupled code system was applied to analyze the Superphenix reactor transient benchmark. The benchmark comprises six operational transients initiated during the SPX reactor start-up tests, covering a wide range of reactor operating states. The peculiarity of these transients is the necessity to consider thermal expansions of major structural elements of the primary system, which significantly influence the transient position of control rods in the core. The paper includes a brief summary of the benchmark specifications, description of the neutron kinetics and thermal hydraulics models, an analysis of the simulation results, and a comparison to the experimental data.

This contribution presents new insights into the origin and age relationships of the Geyer tin deposit in the Erzgebirge, Germany. Tin mineralization occurs in skarns, greisen, and in cassiterite-bearing fluorite-quartz veins. Skarn alteration replaces marble layers of the Cambrian Jáchymov Group and occurs in two clearly distinct stages. The first skarn stage forms skarnoid textured assemblages of clinopyroxene, garnet, and wollastonite with no tin phases recognized. Garnet U-Pb ages of this skarn stage (~322 Ma) relate the earlier skarn stage to the emplacement of the Ehrenfriedersdorf granite (~324 to 317 Ma). The second stage of skarn alteration is marked by the occurrence of malayaite and cassiterite associated with garnet recording ages of 307 to 301 Ma. Greisen- and skarn-hosted cassiterite-bearing veins provide U-Pb ages in the range of 308 to 305 Ma, relating greisenization and vein formation to the same magmatic-hydrothermal event as the second skarn stage. This suggests that tin mineralization at Geyer is related to a distinctly younger magmatic-hydrothermal event, clearly postdating the Ehrenfriedersdorf granite, which was previously assumed as the source of the tin-rich fluids. Fluid inclusions show salinities in the range of 1.0 to 31.5 % eq. w(NaCl±CaCl2) and homogenization temperatures between 255 and 340 °C. Cassiterite-associated fluid inclusions show indications for heterogeneous entrapment and dilution of hydrothermal with meteoric fluids. Dilution of high-salinity fluids with low-salinity fluids and cooling of the system was probably a decisive process in the precipitation of cassiterite in the Geyer Sn system.