Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Multiferroic BiFeO3 (BFO) shows several phonon modes at infrared (IR) to THz energies, which are expected to carry information on any sample property coupled to crystal lattice vibrations. While macroscopic IR studies of BFO are often limited by single-crystal size, scattering-type scanning near-field optical microscopy (s-SNOM) allows for IR thin film spectroscopy of nanoscopic probing volumes with negligible direct substrate contribution to the optical signal. In fact, polaritons such as phonon polaritons of BFO introduce a resonant tip–sample coupling in s-SNOM, leading to both stronger signals and enhanced sensitivity to local material properties. Here, we explore the near-field response of BFO thin films at three consecutive resonances (centered around 5 THz, 13 THz, and 16 THz), by combining s-SNOM with a free-electron laser. We study the dependence of these near-field resonances on both the wavelength and tip–sample distance. Enabled by the broad spectral range of the measurement, we probe phonon modes connected to the predominant motion of either the bismuth or oxygen ions. Therefore, we propose s-SNOM at multiple near-field resonances as a versatile and very sensitive tool for the simultaneous investigation of various sample properties.

UCoAl with the hexagonal ZrNiAl-type structure shows an itinerant metamagnetic phase transition at 0.7 T in the magnetic field along the c-axis. Whereas, this compound becomes to undergo a ferromagnetic phase transition in zero field by substituting Os for Co. UCo_0.995Os_0.005Al exhibits the ferromagnetic phase transition at T_C = 8 K. At high temperatures, the temperature dependence of the transverse elastic modulus C₄₄ in UCo_0.995Os_0.005 Al shows a slight softening below 50 K. The softening turns to an abrupt hardening below 30 K. With further decreasing temperature, a bending is observed at T_C. Although T_C changes sensitively by applying the magnetic fields, the temperature of the elastic hardening is robust in the magnetic fields. This elastic hardening is not caused by a magnetic origin. We measured ultrasonic frequency dependences of C₄₄ and found that the temperature of the elastic hardening increases with increasing ultrasonic frequency. We propose that this ultrasonic frequency dependence is due to a large amplitude atomic motion of constituent atoms.

Overexpression of monocarboxylate transporters (MCTs) has been shown for a variety of human cancers (e.g. colon, brain, breast, and kidney) and inhibition resulted in intracellular lactate accumulation, acidosis and cell death. Thus, MCTs are promising targets to investigate tumor cancer metabolism with positron emission tomography (PET). Here, the organ doses (OD) and the effective dose (ED) of the first 18F-labeled MCT1/MCT4 inhibitor were estimated in juvenile pigs. Whole-body dosimetry was performed in three piglets (age: ~6 weeks, weight: ~13-15 kg). The animals were anaesthetized and subjected to sequential PET/CT up to 5h after i.v. injection of 156 ± 54 MBq [18F]FACH. All relevant organs were defined by volumes of interest. Exponential curves were fitted to the time-activity data. Time and mass scales were adapted to the human order of magnitude and the ODs calculated using the ICRP 89 adult male phantom with OLINDA 2.1. The ED was calculated using tissue weighting factors as published in the ICRP103. The highest organ dose was received by the urinary bladder (62.6 ± 28.9 µSv/MBq), followed by the gall bladder(50.4 ± 37.5 µSv/MBq) and the pancreas (30.5 ± 27.3 µSv/MBq). The highest contribution to the ED was by the urinary bladder (2.5 ± 1.1 µSv/MBq) followed by the red marrow (1.7 ± 0.3 µSv/MBq) and the stomach (1.3 ± 0.4 µSv/MBq). According to this preclinical analysis,the ED to humans is 12.4 µSv/MBq when applying the ICRP103 tissue weighing factors. Taking into account that preclinical dosimetry underestimates the dose to humans by up to 40%, the conversion factor applied for estimation of the ED to humans would raise to 20.6 µSv/MBq. Resultantly, the ED to humans upon an i.v. application of ~300 MBq [18F]FACH would be about 6.2mSv. This risk assessment encourages to translate [18F]FACH to clinical study phases and to further investigate its potential as a clinical tool for cancer imaging with PET.

We report on the magnetic and elastic properties of Er₃Ru₄Al₁₂ in static and pulsed magnetic fields up to 58 T. From the ultrasound results, we obtain evidence for a phase transition at 2 K related to magnetic ordering. Furthermore, in the paramagnetic state, Er₃Ru₄Al₁₂ shows pronounced anomalies in the magnetization and elastic moduli as a function of temperature and magnetic field. We explain our findings using a crystal-electricfield (CEF) model that includes quadrupolar interactions and propose a CEF level scheme for this material. However, the CEF effects cannot explain all field-induced anomalies, which indicates that refined models are needed for explaining these.

The rare-earth ferromagnet Nd₃Ru4Al₁₂ has Curie temperature T_C= 39 K and crystallizes in the hexagonal Gd₃Ru₄Al₁₂-type structure (space group P6₃/mmc), which is a non-caged structure. A previous measurement of the elastic moduli has shown an upturn around 10 K in the temperature dependence of the longitudinal modulus C₃₃. The upturn is not caused by any phase transition. To investigate the origin of the upturn in Nd₃Ru₄Al₁₂, we have measured the temperature dependence of C₃₃ at various ultrasonic frequencies. The temperature of the upturn increases with increasing ultrasonic frequency indicating the ultrasonic dispersion, and it does not change under applied magnetic fields. These results suggest that the upturn originates from the rattling effect at one of the aluminium sites in the crystal structure. Assuming a Debye-type relaxation for the elastic modulus and an Arrhenius-type relaxation time for the rattling, the activation energy was estimated as E = 115 K and the relaxation time as Ƭ₀ = 1.5 x 10^-13s.

Finned tube bundle heat exchangers are used in a variety of applications with the plain circular fin being the most common design. In the present investigation we proposed two novel heat exchanger designs integrated pins, which improve the heat conduction from the fin base to the fin tip as well as the convective heat transfer along the fin surface. Tubes with conventional circular plain fins (CPF) as well as novel circular integrated pin fins (CIPF) and serrated integrated pin fins (SIPF) were additively generated by a Selective Laser Melting (SLM) process. They were tested in a flow channel in a 2-row and a 3-row configuration under forced convection with Reynolds numbers between 1600 and 6600. For the new SIPF and CIPF designed we found an improved Nusselt number compare to the CPF and higher Nusselt number for the 2-row compared to the 3-row configuration. From the analysis of the single tube rows it was found that the Nusselt number is highest for the first row and reduces downstream. The friction factor was lowest for the SIPF at all Reynolds number and the CIPF gave lower friction factor compared to CPF for Reynolds numbers up to approximately Re=4000. Furthermore, the performance of the heat transfer surface was evaluated by the performance evaluation criterion. Hence, an enhancement of 72.6 % and 33.6 % for the 2-row configuration as well as 63.4 % and 29.1 % for the 3-row configuration for the SIPF and CIPF compared to the CPF was found. The compactness of the heat exchanger was evaluated by the volumetric heat flux density, which was greatest for the CIPF followed by the SIPF and lowest for the conventional CPF design. In general the 2-row heat exchanger configuration reached greater performance and volumetric heat flux density than the 3-row configuration. The global performance criterion strongly depends on the flow conditions. Thus, the SIPF heat exchanger performs best at lower and intermediate Reynolds numbers up to Re=5000 and the CPF design is best at higher Reynolds numbers. Eventually, the surface area and the volume of the heat exchanger with SIPF are 30.7 % and 6.9 % lower compared to the conventional heat exchanger. Based on the experimental results an empirical heat transfer correlation was derived, which includes Nusselt number, Reynolds number, Prandtl number, fin design and tube row number.

We studied the thermal and flow performance of tube heat exchangers with novel fin designs for tube tilt angles of "0°,20°,30°" and "40°" to the horizontal. The novel fin designs target to enhance the conduction heat transfer within the fin and the convective heat transfer along the fin surface simultaneously. Tubes with three different fin designs, the circular plain fin (CPF), the circular integrated pin fin (CIPF) and the serrated integrated pin fin (SIPF), were additively manufactured by selective laser melting and experimentally investigated in an air flow channel for Reynolds number between "1800" and "7800" . We analysed the performance evaluation criterion, the volumetric heat flux density and the global performance criterion. It was found, that the SIPF achieves highest performance evaluation criterion and the CPF performs worst. Thus, the SIPF is recommended, when the required surface area, the material cost and the weight of the finned tube heat exchanger are relevant. Highest heat transfer per volume heat exchanger and temperature difference was achieved for the CIPF at highest tube tilt angle. The value of the global performance criterion strongly depends on the fin design and the tube tilt angle. For the horizontal orientation the CPF reaches highest global performance and for the 40° tube tilt angle the CIPF gives best performance. From the experimental data we derived appropriate heat transfer correlations for Reynolds number, Prandtl number, tube tilt angle and fin designs.

Radiolabelled fluorescent dyes are decisive for bimodal imaging and currently in demand for scintigraphic and optical imaging. This powerful method allows the combination of nuclear imaging (e.g. SPECT-imaging) and optical imaging which leads to synergistic effects, resulting in high spatial resolution and high tissue penetration from the whole body to the subcellular level. The new approaches in tumor imaging and its resection enables the accurate differentiation of healthy and diseased (e.g. tumor) tissues. Organic dyes belonging to the rhodamine family show unique optical properties such as high quantum yields, large extinction coefficients, absorption and emission properties in the optical window. The goal of this work was the development of small molecule near-infrared (NIR) light-emitting silicon-rhodamines (SiR) for scintigraphic and optical imaging. We utilized the dyes for copper(I)-catalyzed alkyne-azide [3+2]-cycloaddition to receive respective 1,2,3-triazoles for complexing the prominent SPECT-radiometal 99mTc(I)- and rheniumtricarbonyl core using the click-to-chelate concept from Mindt et al. The dyes were fully characterized using NMR-, UV/VIS/NIR-spectroscopy, IR and mass spectrometry. The presented silicon rhodamines with optical properties in the near-infrared region with emission wavelengths of ca. 650 nm and quantum yields in aqueous solution of up to 0.10 were received in seven reaction steps. The determined extinction coefficients of ca. 150.000 M-1cm-1 show promising results, making them potentially useful for bimodal imaging. Furthermore the dyes were prepared as precursors for radiolabelling with the SPECT-compatible radiometal technetium-99m. Corresponding rhenium-Si-rhodamines [used as a non-radioactive technetium-surrogate] were chemically characterized as well. Subsequently perfomed radiolabelling experiments have shown radiochemical yields of up to 59% and a radiochemical purity greater than 98%. The complexes show high stability both in aqueous solution and even in challenging experiments with histidine under physiological conditions. The first-in-class dyes have been synthesized to elucidate their potential for fluorescence- and radio-guided surgery. The non-targeted radiolabelled rhodamine dyes are subject of ongoing biological evaluations and the incorporation of biovectors into the dye for selective (tumor) targeting are topics of current research.

Structural characterization of actinide nanoparticles (NPs) is of primary importance and hard to achieve, especially for non‐homogeneous samples with NPs below 3 nm. By combining High Energy X‐ray Scattering (HEXS) and High‐Energy‐Resolution Fluorescence Detected X‐ray Near‐Edge Structure (HERFD XANES), we characterized for the first time both short‐ and medium‐range order of ThO₂ NPs obtained by chemical precipitation. With this methodology, a novel insight into the structure of NPs at different steps of their formation process is achieved. The Pair Distribution Function (PDF) reveals a high concentration of ThO₂ small units similar to Th hexamer clusters mixed with 1 nm ThO₂ NPs in the initial steps of formation. Drying the precipitates at ⁓150 °C promotes recrystallization of the smallest units into more thermodynamically stable ThO₂ NPs. HERFD XANES at Th M₄ edge, a direct probe of the f states, shows variations that we correlate to the break of the local symmetry around Th atoms, which most likely concerns surface atoms. Together, HEXS and HERFD are a powerful methodology to investigate actinide NPs and their formation mechanism.

The conversion of optical and electrical energies in novel materials is key to modern optoelectronic and light-harvesting applications. Here, we investigate the equilibration dynamics of photoexcited 2,7-bis(biphenyl-4-yl)-2′,7′-ditertbutyl-9,9′-spirobifluorene (SP6) molecules adsorbed on ZnO(10-10) using femtosecond time-resolved two-photon photoelectron and optical spectroscopies. We find that, after initial ultrafast relaxation on femtosecond and picosecond time scales, an optically dark state is populated, likely the SP6 triplet (T) state, that undergoes Dexter-type energy transfer (rDex = 1.3 nm) and exhibits a long decay time of 0.1 s. Because of this long lifetime, a photostationary state with average T–T distances below 2 nm is established at excitation densities in the 1020 cm−2 s−1 range. This large density enables decay by T–T annihilation (TTA) mediating autoionization despite an extremely low TTA rate of kTTA = 4.5 ⋅ 10−26 m3 s−1. The large external quantum efficiency of the autoionization process (up to 15%) and photocurrent densities in the mA cm−2 range offer great potential for light-harvesting applications.

Drones are becoming important tools for mineral exploration by contributing to the safe, efficient and sustainable provision of the high-tech metals that are required by modern society.

Induction or selection of radioresistant cancer (stem) cells following standard radiotherapy is presumably one of the major causes for recurrence of metastatic disease. One possibility to prevent tumor relapse is application of targeted immunotherapies including e.g. chimeric antigen receptor (CAR) T cells. In light of long-term remissions it is highly relevant to clarify whether radioresistant cancer cells are susceptible to CAR T cell-mediated killing. To answer this question, we evaluated the anti-tumor activity of the switchable universal chimeric antigen receptor (UniCAR) system against highly radioresistant head and neck squamous cell carcinoma cells both in vitro and in vivo. Following specific UniCAR T cell engagement via EGFR or CD98 target modules, T cell effector mechanisms were induced including secretion of pro-inflammatory cytokines, up-regulation of granzyme B and perforin as well as T cell proliferation. CD98- or EGFR-redirected UniCAR T cells further possess the capability to efficiently lyse radioresistant tumor cells. Observed anti-tumor effects were comparable to those against the radiosensitive parental cell lines. Finally, redirected UniCAR T cells significantly inhibited growth of radioresistant cancer cells in immunodeficient mice. Taken together, our obtained data underline that the UniCAR system is able to overcome radio-resistance. Thus, it represents an attractive technology for the development of combined radioimmunotherapeutic approaches that might improve the outcome of patients with metastatic radioresistant tumor diseases.

Statusreport SiPM readout for NeuLAND

The material-efficient monolayers of transition-metal dichalcogenides (TMDs) are a promising class of ultrathin nanomaterials with properties ranging from insulating through semiconducting to metallic, opening a wide variety of their potential applications from catalysis and energy storage to optoelectronics, spintronics, and valleytronics. In particular, TMDs have a great potential as emerging inexpensive alternatives to noble metal-based catalysts in electrochemical hydrogen evolution. Herein, we report a straightforward, low-cost, and general colloidal synthesis of various 2D transition-metal disulfide nanomaterials, such as MoS₂, WS₂, NiS_x, FeS_x, and VS₂, in the absence of organic ligands. This new preparation route provides many benefits including relatively mild reaction conditions, high reproducibility, high yields, easy upscaling, no post-thermal annealing/treatment steps to enhance the catalytic activity, and, finally, especially for molybdenum disulfide nanosheets, high activity in the hydrogen evolution reaction. To underline the universal application of the synthesis, we prepared mixed Co_xMo_1-xS₂ nanosheets in one step to optimize the catalytic activity of pure undoped MoS₂, which resulted in an enhanced hydrogen evolution reaction performance characterized by onset potentials as low as 134 mV and small Tafel slopes of 55 mV/dec.

Noble metal aerogels (NMAs) are an emerging class of porous materials. Embracing nano-sized highly-active noble metals and porous structures, they display unprecedented performance in diverse electrocatalytic processes. However, various impurities, particularly organic ligands, are often involved in the synthesis and remain in the corresponding products, hindering the investigation of the intrinsic electrocatalytic properties of NMAs. Here, starting from laser-generated inorganic-salt-stabilized metal nanoparticles, various impurity-free NMAs (Au, Pd, and Au-Pd aerogels) were fabricated. In this light, we demonstrate not only the intrinsic electrocatalytic properties of NMAs, but also the prominent roles played by ligands in tuning electrocatalysis through modulating the electron density of catalysts. These findings may offer a new dimension to engineer and optimize the electrocatalytic performance for various NMAs and beyond.

The advent of noble metal aerogels (NMAs), that feature the high catalytic activity of noble metals and unique structural attributes of aerogels, has stimulated research on a new class of outstanding electrocatalysts. However, limited by the available compositions, the explored electrocatalytic reactions on NMAs are highly restricted and certain important electrochemical processes have not been investigated. Here, an effective gelation approach is demonstrated by using a strong salting-out agent (i.e., NH₄F), thereby expanding the composition of NMAs to various multimetallic systems and providing a platform to investigate composition-dependent electrocatalytic performance of NMAs. Combining structural features of aerogels and optimized chemical compositions, the Au-Pt and Au-Rh aerogel catalysts manifest remarkable pH-universal (pH = 0-14) performance surpassing commercial Pt/C and many other nanoparticle (NP)-based catalysts in the electrocatalytic oxygen reduction reaction, hydrogen evolution reaction, and water splitting, displaying enormous potential for the electrochemical hydrogen production, fuel cells, etc.

Two-phase flow is to be found in many situations of nuclear reactor operation and accident sequences. Examples are loss of coolant accidents and boiling in fuel assemblies. Hence, mod-elling of two-phase flow is a primary concern in nuclear safety research. Model development and code validation frequently require experimental data, preferably taken under plant ther-mal-hydraulic conditions. Tomographic imaging techniques provide a way to analyze two-phase flow with high spatial resolution. In this paper we introduce recent developments in X-ray tomography and its application to three different problems related to nuclear safety.

The paper presents a statistical study of nanoindentation results obtained in seven European laboratories which have joined a round robin exercise to assess methods for the evaluation of indentation size effects. The study focuses on the characterization of ferritic/martensitic steels T91 and Eurofer97, envisaged as structural materials for nuclear fission and fusion applications, respectively. Depth-controlled single cycle measurements at various final indentation depths, force-controlled single cycle and force-controlled progressive multi-cycle measurements using Berkovich indenters at room temperature have been combined to calculate the indentation hardness and the elastic modulus as a function of depth applying the Oliver and Pharr method. Intra- and inter-laboratory variabilities have been evaluated. Elastic modulus corrections have been applied to the hardness data to compensate for materials related systematic errors, like pile-up behaviour, which is not accounted for by the Oliver and Pharr theory, and other sources of instrumental or methodological bias. The correction modifies the statistical hardness profiles and allows determining more reliable indentation size effects.

Zusammenfassung: Sensorgestützte Sortierung ist eine Technologie, die in zunehmendem Maße zur Aufbereitung von Primärrohstoffen verwendet wird. Mit dem hier vorgestellten simulations-basierten Ansatz ist es möglich, den optimalen Sensor durch quantitative Analysen der Mineralogie und Datenverwertung in Kombination mit Maschinellem Lernen (ML) gezielt zu bestimmen. Dieses Vorgehen ist generisch und kann auf viele Rohstofftypen angepasst werden. Darüber hinaus birgt das Vorgehen das Potenzial, eine Schlüsseltechnologie zur Optimierung von Aufbereitungsprozessen zu werden.

Summary: Sensor-based sorting is a technology which is increasingly used for processing primary raw materials. With the simulation-based approach presented in this paper, it is possible to specifically determine the optimal sensor based on quantitative analyses of the mineralogy and data utilization in combination with machine learning (ML). This approach is generic and can be adapted to many types of raw material. Moreover, the approach has the potential to become a key technology for the optimization of processing operations.

Two approaches for the use of the Electric Pulse Fragmentation (EPF) in the beneficiation of a low-grade cassiterite schist ore were investigated through pilot-scale tests performed on samples of about 270 kg. The first approach used EPF treatment for pre-concentration while in the second approach the EPF technology was mostly used for crushing. Comparison with the use of conventional crushers was performed.
Results showed that the EPF pre-treatment led to a decrease of the Bond rod mill work index while the Bond ball mill work index remained unchanged. This means that the decrease in the energy consumption requested to grind the material down to 1.18 mm (closing screen of the Bond rod mill work index) is no longer noticeable with additional grinding stage to reach a size down to 106 μm (closing screen of the Bond ball mill work index).
This may be due to the fracture network generated during EPF being consumed immediately in the subsequent comminution step. Alternatively, it may be that the Bond ball mill work index is not appropriate for exhibiting the weakening effect of the EPF technology when the mineral liberation size is coarser than the closing screen size used for the test. Concentration tests performed on the sample treated with the first approach for EPF showed no marked change in separation performance. However, a higher concentrate grade was obtained when using this EPF pre-treatment, indicating a probable potential for improvement.

We have extended the study of the Kuramoto model with additive Gaussian noise running on the KKI-18 large human connectome graph. We determined the dynamical behavior of this model by solving it numerically in an assumed homeostatic state, below the synchronization crossover point we determined previously. The desynchronization duration distributions exhibit power-law tails, characterized by the exponent in the range 1.1 < τ_t < 2, overlapping the in vivo human brain activity experiments by Palva et al. We show that these scaling results remain valid, by a transformation of the ultra-slow eigen-frequencies to Gaussian with unit variance.
We also compare the connectome results with those, obtained on a regular cube with N = 10⁶ nodes, related to the embedding space, and show that the quenched internal frequencies themselves can cause frustrated synchronization scaling in an extended coupling space.

Due to their unique photophysical properties, upconverting nanoparticles (UCNPs), i.e. particles capable of converting near-infrared (NIR) photons into tunable emissions in the range of ultraviolet (UV) to NIR, have great potential for use in various biomedical fields such as bioimaging, photodynamic therapy and bioanalytical applications. As far as biomedical applications concerned, these materials have a number of advantageous properties such as brilliant luminescence and exceptional photo-stability. Very small “stealth” particles (sub-10 nm), which can circulate in the body largely undetected by the immune system, are particularly important for in vivo use. The fabrication of such particles, which simultaneously have a defined (ultrasmall) size and the required optical properties, is a great challenge and an area that is in its infancy. This minireview provides a concise overview of recent developments on appropriate synthetic methodologies to produce such UCNPs. Particular attention was given to the influence of both surfactants and dopants used to precisely adjust size, crystalline phase and optical properties of UCNPs.

We demonstrate a novel type of spin Hall nano-oscillators (SHNOs) that allow for efficient tuning of magnetic auto-oscillations over an extended range of gigahertz frequencies, using bipolar direct currents at constant magnetic fields. This is achieved by stacking two distinct magnetic materials with a platinum layer in between. In this device, the orientation of the spin polarised electrons accumulated at the top and bottom interfaces of platinum is switched upon changing the polarity of the direct current. As a result, the effective anti-damping required to drive large amplitude auto-oscillations can appear either at the top or bottom magnetic layer. Tuning of the auto-oscillation frequencies by several gigahertz can be obtained by combining two materials with suffciently different saturation magnetization. Here we show that the combination of NiFe and CoFeB can result in 3 GHz shifts in the auto-oscillation frequencies. Bipolar SHNOs as such may bring enhanced synchronisation capabilities to neuromorphic applications.

Here, structural parameters of various structure reports on RSi2 and R2TSi3 compounds [where R is an alkaline earth metal, a rare earth metal (i.e. an element of the Sc group or a lathanide), or an actinide and T is a transition metal] are summarized. The parameters comprising composition, lattice parameters a and c, ratio c/a, formula unit per unit cell and structure type are tabulated. The relationships between the underlying structure types are presented within a group–subgroup scheme (Bärnighausen diagram). Additionally, unexpectedly missing compounds within the R2TSi3 compounds were examined with density functional theory and compounds that are promising candidates for synthesis are listed. Furthermore, a correlation was detected between the orthorhombic AlB2-like lattices of, for example, Ca2AgSi3 and the divalence of R and the monovalence of T. Finally, a potential tetragonal structure with ordered Si/T sites is proposed.

A mobile X-ray microtomography (µCT) system was developed which enables 3D scanning of horizontal and vertical test sections. The µCT system has been applied to measure the local, time-averaged volume fraction distribution of developing annular air-water flow in a horizontal pipe with µm spatial resolution. Based on the volume fraction data the liquid film thickness profile is computed and the accumulation, stripping and renewal of the annular liquid film at a circular orifice is studied. The development length of the annular flow downstream of the orifice is evaluated based on the integral volume fraction and the change of the film thickness profile along the pipe axis. Both parameters give a consistent result, indicating that liquid film renewal can be judged based on integral measurement techniques in this case. The detailed 3D data is intended for validation of computational fluid dynamics codes based on phase-averaged variables such as the Euler-Euler approach.

High-mountain environments in an active tectonic setting are prone to landsliding. The triggering mechanisms are still a challenge as these areas are influenced by several pre-conditioning factors coupled with active seismicity and climatic forcings. Understanding the intrinsic and external mechanisms in which these events are influenced would help to establish better constraints onto their timing and periodicity and, eventually, hazard assessment and prediction. Glacially eroded valleys are especially prone as they deeply incise mountain ranges leaving unstable slopes once they retreat. Establishing the timing of such events enables to link the causality and comprehend in a deeper level the triggering and pre-conditioning factors of landslides. To this aim, ¹⁰Be and ²⁶Al cosmogenic age determinations were performed in three landslide deposits in a poorly studied area of San Juan province, all of which are novel to the area. Coupled with remote sensing techniques, field observations and detailed stratigraphic and sedimentological studies, these new large landslides represent a first approach to understand this dynamic environment. The three landslides were categorized as rock avalanches found in the middle and lower reaches of the Blanco River, sourced from the Choiyoi Group with evidence of hydrothermal alteration and including/deforming moraine deposits during their fall. Ages range from 20.9±1.4, 10.8±0.7 and 12.8±0.9 ka from the lowermost deposit to the highest, respectively. Even though one sample per deposit is not enough to have statistically significant exposure ages, these values, along with the established chronostratigraphy, allow first order assumptions on the link between deglaciation processes and readjustment of the slopes via large landslide events.

Mit der verlängerten Zwischenlagerung von abgebrannten Brennelementen ergeben sich verschie-dene regulatorische und sicherheitstechnische Fragestellungen. Eine davon ist die nach der Lang-zeitintegrität der Brennelemente in den Trockenlagerbehältern. Ihre Beantwortung hat direkte Relevanz für den späteren Transport zum Endlager und die Umladung des abgebrannten Kernbrennstoffs in andere Behälter. In dem Verbundvorhaben untersuchten die TU Dresden und die Hochschule Zittau/Görlitz Potenziale und Grenzen von nichtinvasiven Verfahren zur Überwachung des Zustands des radioaktiven Inventars von Trockenlagerbehältern. Als solche wurden Thermographie, strahlungsbasierte Messverfahren sowie akustische Messverfahren betrachtet. Für diese erfolgte eine Bewertung der Empfindlichkeit und Nachweisgrenzen mittels numerischer Simulationen und Durchführung von Experimenten an skalierten Behältermodellen. Es stellte sich heraus, dass insbesondere die Myonenbildgebung und die Analyse der Gamma- und Neutronenstrahlungsfelder am Behälter für ein Überwachungskonzept geeignet sind. Mit diesen Verfahren können Brennstoffverlagerungen ortsaufgelöst detektiert werden.

We use density functional molecular dynamics (DFT-MD) to study the effect of finite temperature exchange-correlation (xc) in Hydrogen. Using the Kohn-Sham approach, the xc energy of the system, $E_{xc}(r_{s})$ is replaced by the xc free energy $f_{xc}(r_{s},\theta)$ within the local density approximation (LDA) based on parametrized path integral Monte Carlo (PIMC) data for the uniform electron gas (UEG) at warm dense matter (WDM) conditions. We observe insignificant changes in the equation of state (EOS) at the region of metal-insulator transition compared to the regular LDA form, whereas significant changes are observed for T>10000 K, i.e., in the important WDM regime. Thus, our results further corroborate the need for temperature-dependent xc functionals for DFT simulations of WDM systems. Moreover, we present the first finite-temperature DFT results for the EOS of Hydrogen in the electron liquid regime up to $r_{s}=14$ and find a drastic impact (the EOS changes by more than 20%) of thermal xc effects, which manifests at lower temperatures compared to WDM. We expect our results to be important for many applications beyond DFT, like quantum hydrodynamics and astrophysical models.

We present resistivity and thermal-conductivity measurements of superconducting FeSe in intense magnetic fields up to 35 Tapplied parallel to the ab plane. At low temperatures, the upper critical field μ₀H^ab _c2 shows an anomalous upturn, while thermal conductivity exhibits a discontinuous jump at μ₀H* ≈ 24 T well below μ₀H^ab _c2, indicating a first-order phase transition in the superconducting state. This demonstrates the emergence of a distinct field-induced superconducting phase. Moreover, the broad resistive transition at high temperatures abruptly becomes sharp upon entering the high-field phase, indicating a dramatic change of the magnetic-flux properties.We attribute the high-field phase to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, where the formation of planar nodes gives rise to a segmentation of the flux-line lattice. We point out that strongly orbital-dependent pairing as well as spin-orbit interactions, the multiband nature, and the extremely small Fermi energy are important for the formation of the FFLO state in FeSe.

Recently, a Verwey-type transition in the mixed-valence alkali sesquioxide Cs₄O₆ was deduced from the charge ordering of molecular peroxide O²⁻ ₂ and superoxide O⁻ ₂ anions accompanied by the structural transformation and a dramatic change in electronic conductivity [Adler et al., Sci. Adv. 4, eaap7581 (2018)]. Here, we report that in the sister compound Rb₄O₆, a similar Verwey-type charge ordering transition is strongly linked to O⁻ ₂ orbital and spin dynamics. On cooling, a powder neutron diffraction experiment reveals a charge ordering and a cubic-to-tetragonal transition at T_CO = 290 K, which is followed by a further structural instability at T_s = 92 K that involves an additional reorientation of magnetic O⁻ ₂ anions. Magnetic resonance techniques supported by density functional theory computations suggest the emergence of a peculiar type of π*-orbital ordering of the magnetically active O⁻ ₂ units, which promotes the formation of a quantum spin state composed of weakly coupled spin dimers. These results reveal that as in 3d transition-metal compounds, also in the π* open-shell alkali sesquioxides the interplay between Jahn-Teller-like electron-lattice coupling and Kugel-Khomskii-type superexchange determines the nature of orbital ordering and the magnetic ground state.

The strongly coupled electron liquid provides a unique opportunity to study the complex interplay of strong coupling with quantum degeneracy effects and thermal excitations. To this end, we carry out extensive ab initio path integral Monte Carlo (PIMC) simulations to compute the static structure factor, interaction energy, density response function, and the corresponding static local field correction in the range of 20≤rs≤100 and 0.5≤θ≤4. We subsequently compare these data to several dielectric approximations and find that different schemes are capable to reproduce different features of the PIMC results at certain parameters. Moreover, we provide a comprehensive data table of interaction energies and compare those to two recent parametrizations of the exchange-correlation free energy, where they are available. Finally, we briefly touch upon the possibility of a charge-density wave. The present study is complementary to previous investigations of the uniform electron gas in the warm dense matter regime and, thus, further completes our current picture of this fundamental model system at finite temperature. All PIMC data are available online.

Clinical Nuclear Medicine, 2nd ed., Chapter 2 Radiopharmaceutical Sciences
Abstract: Chapter 2 Radiopharmaceutical Sciences
Chapter 2 elucidates the field Radiopharmaceutical Sciences from the perspective of its clinical relevance. Radiopharmaceutical Sciences summarize all scientific aspects comprising chemistry, physics and biology/pharmacology that deal with incorporating a suitable radionuclide into a pharmaceutical or other biologically active molecule or molecular entity. The resulting radiopharmaceuticals are used in Nuclear Medicine applications both for diagnosis [meaning non-invasive scintigraphic imaging] and for internal radiotherapy. Internal radiotherapy is nowadays called radioligand therapy (RLT) or endoradiotherapy and altogether is summarized under the term radiothera(g)nostics.
To transfer Radiopharmaceutical Sciences into Clinical Nuclear Medicine first of all radionuclides with corresponding decay characteristics are demanded making these suitable for diagnostic or therapeutic applications. Depending on the short physical half-lives of the radionuclides fast and efficient radiolabeling strategies are required that can be also transferred into the GMP-compliant production of radiopharmaceuticals.
The major challenges in the development of a new radiopharmaceuticals include i.a. the identification of an adequate ligand that specifically binds to the biological target of interest, the chemical modification of the ligand to enable radiolabeling while preserving the binding affinity to the biological target, and the translation of the preclinical evaluations into first in-human studies.
In summary this chapter summarises in a concise manner the current status of clinically relevant radionuclides, SPECT and PET tracers as well as the introduced thera(g)nostic classes of radiopharmaceuticals through the eyes of eight representative radiopharmaceutical scientists.

Helium ions are alternative imaging probes to electrons, offering lower de Broglie wavelengths at the same energies and the possibility for different contrast mechanisms [1] [2][3]. A prototype Transmission Helium Ion Microscope (THIM) has been constructed at the Luxembourg Institute of Science and Technology (LIST) [4]. The use of post sample deflection allows the detection of the transmitted ions and neutrals or neutrals only (Figure 1 A). The source is a duo plasmatron with a spot size on the sample of approximately 100 µm and a beam current between 0.1-2nA. There are 2 Einzel lenses and 3 XY deflectors along the column to guide the beam. A MCP detector behind the sample can be used in one of 4 different output mechanisms. Firstly a phosphor screen can be used to produce a transmission helium ion image (THIM) directly which can be captured by an external CCD. Secondly, an anode plate can be used to collect the current directly whilst the beam is scanned, the current recorded at each pixel can then form a scanning image (STHIM). Thirdly, fast electronics are used to blank the beam and provide the start signal for time of flight (TOF) measurements, whilst the anode signal can be used as the stop signal [5]. This allows the generation of TOF-STHIM data. Finally, a delay line detector (DLD) can be placed behind the MCP, from which location and time of flight, of individual particles, can be recorded simultaneously, producing energy spectra and images at the same time. The prototype can image in different modes, THIM , STHIM (scanning THIM), THIM TOF and STHIM TOF. When scanning the beam a secondary electron image can be recorded at the same time (Figure 1 B). In THIM mode the formation of spot patterns due to sample charging was seen when imaging insulating inorganic crystal samples with a stationary broad beam. This was found to be due to unexpectedly large sample charging. We will present preliminary TOF spectra for the transmitted helium ion signal recorded with an anode plate detector and a position sensitive delay line detector. Images formed from different time windows from the TOF spectra show different contrast (Figure 2B) and the spectra for a single layer graphene sample showed increased counts after the main peak (Figure 3), indicative of processes causing energy loss.

[1] Scipioni,L.;, Sanford,C. A.;, Notte,J.;, Thompson,B.;, McVey,S.;, J. Vac. Sci. Technol. B Microelectron. Nanom. Struct., 2009, vol. 27, no. 6, p. 3250, 10.1116/1.3258634.
[2] Kavanagh,K. L.;, Herrmann,C.;, Notte,J. A.;, J. Vac. Sci. Technol. B, Nanotechnol. Microelectron. Mater. Process. Meas. Phenom., 2017, vol. 35, no. 6, p. 06G902, 10.1116/1.4991898.
[3] Wirtz,T.;, De Castro,O.;, Audinot,J.-N.;, Philipp,P.;, Annu. Rev. Anal. Chem., 2019, vol. 12, no. 1, 10.1146/annurev-anchem-061318-115457.
[4] Mousley,M.;, Eswara,S.;, De Castro,O.;, Bouton,O.;, Klinger,N.;, Koch,C. T.;, Hlawacek,G.;, Wirtz,T.;, Submitt. to MRS Commun., vol. 1, pp. 1–10.
[5] Klingner,N.;, Heller,R.;, Hlawacek,G.;, Borany,J. von;, Notte,J.;, Huang,J.;, Facsko,S.;, Ultramicroscopy, 2016, vol. 162, pp. 91–97, 10.1016/j.ultramic.2015.12.005.

Figure 1: A) transmission images formed with ions and neutrals of a copper grid with a single layer graphene membrane pitch 85µm (31µm bar 54µm hole). B) Secondary electron and transmission ion images recorded concurrently in scanning mode.

Figure 2: A) The effect of offsetting the beam aperture on zero loss peak width B) STHIM images, of a 200 mesh copper grid, formed from two different peaks in the TOF spectrum.

Figure 3: The TOF spectrum for a single layer graphene sample on a 300 mesh copper grid, shows extra peaks compared to a background spectrum without a sample.

Combined morphological and chemical analysis of ultrastructures is gaining more and more attention in both material and life sciences. Especially the detection of nanoparticles within biological tissue has become a hot topic in environmental research, ecology, nanotoxicology, but also medicine and life science using nanoparticles as carriers for therapeutic drugs. Usually, several highly specialised instruments have to be used to investigate the respective key features of the sample.
Here, a new prototype instrument is presented that combines sub20nm SIMS on a helium ion microscope [HIM; 1] with dark and bright field imaging in one tool – the npSCOPE [2]: the multi-modal instrument couples a Gas Field Ion Source (GFIS) as primary ion beam source with a secondary ion mass spectrometer (SIMS) system featuring a continuous focal plane detector (FPD) and a STHIM detector for imaging the transmitted helium beam. The latter allows investigation of thin samples like biological tissue sections. For morphological/topographical analysis of charging and non-charging bulk samples with sub-nm resolution, the instrument is also equipped with a secondary electron detector and a flood gun. This setup allows (a) higher sensitivity than analytical electron microscopy combined with (b) better spatial resolution than available with other SIMS methodologies typically used for life science questions. The FPD yields a full mass spectrum per scanned pixel featuring the possibility of post hoc analysis of all elements/ion species detected.
Several examples will be presented to show how thin tissue sections can first be investigated with transmitted ions for proper contrast of biological membranes followed by chemical characterization of associated or ingested nanoparticles without the need to transfer samples between different instruments. Specific localisation of the nanoparticles outside the cell membrane or within the cytoplasm or subcellular compartments can be obtained.

In summary, a unique tool for all-in-one physico-chemical characterisation of nanoparticles both before contact to a living organism and after incorporation is presented. Pixel by pixel correlation of the different datasets are directly obtained by image fusion or co-registration methods. For future analysis of frozen-hydrated samples, a cryo-stage is currently being integrated into the npSCOPE. It will yield close to native chemical analysis of diagnostic, environmental and nanotoxicology samples with decreased experiment times and without artefacts due to sample transfer.
References:
[1] T. Wirtz, O. De Castro, J.-N. Audinot, P. Philipp. Imaging and analytics on the Helium Ion Microscope. Annual Review of Analytical Chemistry 12 (2019) 523-543

[2] This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 720964.

In various research areas ranging from materials science to life sciences it becomes more and more important to be able to analyze the structure as well as the chemical composition at the nano-scale. For example, the size of electronic components becomes smaller and smaller increasing the need of having techniques to precisely follow dopant distributions with high spatial resolution. In the field of renewable energy devices, e.g. solar cells and batteries, the performance typically depends on the chosen material composition and distribution. Linking the underlying structure and composition at the nano-scale to the device’s performance is therefore of utmost importance [1,2]. Similar needs for having high spatial resolution and high-sensitivity chemical information can be found in life sciences [3]. In nano-toxicology for instance, it is important to be able to reveal sub-cellular structures and simultaneously determine their chemical, elemental or isotopic composition in order to better understand relevant processes [4]. In most of the afore mentioned studies a number of different instruments is nowadays used to perform these investigations using correlative approaches. Being able to do such correlative studies in one single instrument is definitely beneficial for reducing the analysis time, speeding up the throughput as well as for facilitating the precise localization of the region of interests on the investigated samples.
Therefore, we developed a multimodal nano-analytical platform allowing in-situ analysis of a same sample using different information channels. The instrument is equipped with the ultra-high resolution Gas Field Ion Source (GFIS) technology [5] allowing the sample to be irradiated with very finely focused He+ and Ne+ primary ion
beams. This allows sub-nanometer spatial resolution when working with the secondary electron (SE) detection mode as imaging mode. Furthermore, the instrument incorporates a compact secondary ion mass spectrometer (SIMS) for chemical analysis of samples with excellent sensitivity and high dynamic range. The mass spectrometer is based on a double focusing magnetic sector design and allows sub-20 nm chemical imaging resolution [6-8]. Moreover, the SIMS system incorporates a new kind of detector for parallel mass detection providing a full mass spectrum for each analyzed pixel. The third newly developed detection mode available within the instrument is a position sensitive transmission detector located at the backside of the sample in order to detect the transmitted He beam. This scanning transmission helium ion microscopy (STHIM) mode provides further in-situ structural/compositional data with tomographic capabilities.
In order to optimize the analysis of biological samples, one further key feature of the instrument is a 5-axis cryo-stage along with cryo-capabilities for sample transfers. This cryo-capability allows biological samples to be analyzed in a frozen-hydrated state, thus avoiding artefacts caused by classical sample preparation (e.g. chemical fixation) used for HV or UHV imaging of biological specimens at room temperature. Moreover, the cryo-mode can be beneficial for analyzing beam sensitive samples in materials science such as OLEDs and polymers.
In this work we will present the npSCOPE concept and the instrument’s overall setup, report on the performance of the different detection modes and discuss the correlative microscopy capabilities. We will present results from case studies in different fields, with a particular focus on nanoparticles (see Figure 1) [9].

Every year 12,000 metric tonnes of high-level radioactive waste (HLW) are produced worldwide. For the long-term storage of this highly radiotoxic waste, a deep geological disposal by using multiple barriers is favored. Bentonite is proposed as a potential material for sealing the space between the canister containing the HLW and the surrounding host rock. In order to investigate the microbial diversity and metabolic activity of naturally occurring microorganisms as well as their time-dependent evolution, we conducted anaerobic microcosm experiments containing bentonite and a synthetic Opalinus Clay pore water solution. During the one-year incubation at 30 and 60 °C, lactate- or H2-stimulated microcosms at 30 °C showed the dominance and activity of strictly anaerobic, sulfate-reducing and spore-forming microorganisms. The subsequent generation of hydrogen sulfide gas in the respective set ups, led to the formation of fractures and iron-sulfur precipitations. In microcosms that incubated at 60 °C, thermophilic bacteria dominated, independent from the availability of substrates. In the respective microcosms, no significant metabolic activity was detected and there was no change in the analyzed bio-geochemical parameters. Our results show that indigenous microorganisms evolve in a temperature- and substrate-dependent manner. Potentially formed metabolites could affect the dissolution behavior of minerals and ions within the bentonite as well as the corrosion process of the canister material and require further investigations.

The main challenge in scheelite flotation lies in the contamination of the concentrate by other calcium-bearing minerals, mainly calcite. To remedy this problem, sodium silicate is frequently used as a depressant. According to the literature, one hypothesis for the mechanism of water glass consists in its absorption onto calcite through colloidal silica formation, preventing hydrophobization by the collector. This short communication presents research conducted on the direct use of colloidal silica as a depressant in scheelite flotation. Colloidal silica is shown to have an impact on scheelite flotation, especially by depressing silicates.

To improve the performance of sodium silicate in scheelite flotation and allow the selective separation of scheelite from other semi-soluble salt-type minerals such as calcite, three acids, sulfuric, oxalic and for the first time hydrochloric are used to acidify sodium silicate (also called water glass). A literature review of previous usage of acidified water glass shows that no comparison between acids was made before, that comparisons with alkaline water glass were limited and that the idea that acidified water glass is more efficient at lower dosages has not been proven in scheelite flotation. As a consequence, the impact of the acid type, the ratio between acid and sodium silicate and acid dosage is tested in single mineral flotation and batch flotation experiments. All three acids allow a higher performance of acidified water glass compared to alkaline water glass at lower dosages and with little addition of acid: the tungsten recovery and grade are improved while silicates and to a lesser extent calcium-bearing minerals float less. The dosage of acid is less determining than the mass ratio of the acid to sodium silicate, except in the case of hydrochloric acid. Overall, the acid type does not matter as all three acids perform well in flotation, whereby oxalic and hydrochloric acid are better.

A phosphinate-bearing picolinic acid-based chelating ligand (H6dappa) was synthesized and characterized to assess its potential in a bifunctional chelator (BFC) for inorganic radiopharmaceuticals. Nuclear magnetic resonance (NMR) spectroscopy was employed to investigate the chelator coordination chemistry with a variety of nonradioactive trivalent metal ions (In3+, Lu3+, Y3+, Sc3+, La3+, Bi3+). Density functional theory (DFT) calculations explored the coordination environments of aforementioned metal complexes. The thermodynamic stability of H6dappa with four metal ions (In3+, Lu3+, Y3+, Sc3+) was deeply investigated via potentiometric and spectrophotometric (UV-vis) titrations, employing a combination of acidic in-batch, joint potentiometric/spectrophotometric, and ligand-ligand competition titrations; high stability constants and pM values were calculated for all four metal complexes. Radiolabeling conditions for three clinically relevant radiometal ions were optimized ([111In]In3+, [177Lu]Lu3+, [90Y]Y3+), and the serum stability of [111In][In(dappa)]3- was studied. Through concentration-, time-, temperature-, and pH-dependent labeling experiments, it was determined that H6dappa radiolabels most effectively at near-physiological pH for all radiometal ions. Furthermore, very rapid radiolabeling at ambient temperature was observed, as maximal radiolabeling was achieved in less than one minute. Molar activities of 29.8 GBq/mol and 28.2 GBq/mol were achieved for [111In]In3+ and [177Lu]Lu3+, respectively.

This is the second part of a special issue of the American Journal of Science examining a problem that defines, perhaps more than any other, the state-of-the-art in the geochemistry of fluid-solid interaction: how to integrate data from both observations and modeling of events of brief duration at essentially atomic scales (for example, attachment, diffusion, detachment, hydrolysis), to that of mesoscale, ensemble processes (crystal dissolution, growth, alteration). The ultimate goal is an understanding of the long-term, phenomenological consequences of these interactions, often termed “upscaling”. Success in predicting and constraining these latter outcomes determines the larger value of this field, both to neighbors in environmental sciences and engineering, as well as to the public in terms of policy, education, and support. Nanoscale observation of mineral surfaces via instruments such as AFM and VSI is now widespread; increases in resolution and analytical capability of these instruments have also evolved in tandem with advances in the power and resolution of simulation and modeling approaches. Closely tied to an emerging theoretical framework, this “soft” progress in simulation and modeling was the focus of the first part of this issue.

The Roast-Leach-Electrowinning process generates considerable quantities of iron-rich precipitates that must be landfilled, potentially causing a problem for the zinc smelters as well as negatively affecting the society and the environment. The integration of pyrometallurgical flowsheets into existing Roast-Leach-Electrowinning plants is evaluated in this paper. Ten different cases, including Direct Zinc Smelting, ferrite fuming or pyrometallurgical treatment of iron-rich residue, are assessed to find the most resource efficient and environmentally friendly solution to minimize the hydrometallurgical precipitates of the electrolytic process for the zinc production. The simulation-based methodology used provides indicators to evaluate the material recovery and losses, residue production, resource consumption, exergy destruction, and environmental impacts, which are used to find the best alternative that improves the resource efficiency and the environmental impact of the Roast-Leach-Electrowinning process. Furthermore, the social, environmental, and economic impacts associated to the different alternatives are discussed based on the indicators provided by the simulation.

Radiotherapy is one of the pillars in the multimodal therapy of sarcomas of the extremities or pelvis/retroperitoneum. It can be delivered prior to or following surgery. Novel radiation techniques, such as intensity-modulated radiotherapy using high-energy photons or protons, contribute to the reduction of acute and late toxicities. This review article summarizes these concepts.

Many solid tumors, including ovarian cancer, contain small populations of cancer stem cells (CSCs). These cells are usually resistant against conventional cancer therapies and play a role in disease recurrence. We demonstrated that the L1 cell adhesion molecule (L1CAM) is a new CSC target in ovarian cancer, triggering radioresistance. Using fluorescence-activated cell sorting, specific cell populations expressing L1CAM alone or in combination with the established CSC marker CD133 were isolated from three ovarian cancer cell lines. Double-positive L1CAM+/CD133+ cells displayed higher spherogenic and clonogenic properties in comparison to L1CAM−/CD133− cells. Furthermore, L1CAM+/CD133+ cells retained highest clonogenic capacity after irradiation and exhibited up-regulation of some CSC-specific genes, enhanced tumor-initiating capacity, selfrenewal and higher tumor take rate in nude mice when compared with other cell populations. Superior radioresistance by L1CAM expression was confirmed by deletion of L1CAM using CRISPR-Cas9 technology. Moreover, we found expression signatures associated with epithelial-tomesenchymal transition phenotype in L1CAM deleted cells. These results indicate that L1CAM in combination with CD133 defines a new cancer cell population of ovarian tumor-initiating cells with the implication of targeting L1CAM as a novel therapeutic approach for ovarian CSCs.

A new parameter (degree of randomness (DR)) was defined for the identification of the main transition velocities, Utrans. The new method reconstructs the time series into multiple state vectors, thus generating non-overlapping vector pairs and then compares the distance between them with a pre-selected cut-off length. The DR values were extracted from gauge and differential pressure fluctuations as well as x-ray tomographic scans. At every Utrans value, the DR index exhibited a well-pronounced local minimum. Three cylindrical bubble columns (BCs) with various diameters (0.1, 0.14, and 0.45 m in ID) and one rectangular BC (width = 0.2 m, depth = 0.04 m) were used. They were aerated by means of different perforated plate gas distributors. It was found that in the cylindrical BCs the disintegration of the bubbly flow regime took place always at Utrans = 0.04 m/s. In the case of the rectangular BC the first critical velocity appeared at Utrans = 0.012 m/s. The lower boundary of the churn-turbulent regime was identified at Utrans = 0.11 m/s in the smallest cylindrical BC and at about Utrans = 0.095 m/s in the other two cylindrical BCs. In the case of the rectangular BC, the second critical velocity was identified at Utrans = 0.039 m/s. The low Utrans in the rectangular BC imply that the hydrodynamic regimes are less stable in this particular column due to higher degree of liquid turbulence. The calculated DR values from the gauge pressure fluctuations successfully distinguished the upper boundary of the gas maldistribution and the first transition sub-regime.

We study the thermodynamic and high-magnetic-field properties of the magnetic insulator Ba₅CuIr₃O₁₂, which shows no magnetic order down to 2 K, consistent with a spin-liquid ground state. While the temperature dependence of the magnetic susceptibility and the specific heat shows only weak antiferromagnetic correlations, we find that the magnetization does not saturate up to a field of 59 T, leading to an apparent contradiction. We demonstrate that the paradox can be resolved, and all of the experimental data can be consistently described within the framework of random singlet states. We demonstrate a generic procedure to derive the exchange coupling distribution P(J ) from the magnetization measurements and use it to show that the experimental data are consistent with the power-law form P(J ) ∼ J^−α with α ≈ 0.6. Thus, we reveal that high-magnetic-field measurements can be essential to discern quantum spin-liquid candidates from disorder dominated states that do not exhibit long-range order.

Purpose: The technical feasibility of simultaneous proton beam irradiation and magnetic resonance (MR) imaging has recently been demonstrated by phantom experiments performed on a 0.22 T open MR scanner that was integrated with a static proton beam line in a clinical environment [1]. Since the scanner and Faraday cage were mounted together on a mobile transport platform, the whole setup is movable to a pencil beam scanning beam line that allows for volumetric irradiation. In perspective, this setup may be used for first in-beam MR-guided proton therapy of patients with soft-tissue sarcoma of the forearm. However, the geometry of the Faraday cage and the MR scanner limits the patient’s freedom of positioning. Patients can only be treated in a seated position with the affected arm extended sideways into the imaging and irradiation field. However, the CT scan used for treatment planning is acquired in supine position with the arm extended over the head. An in-house developed prototype CT-MR compatible positioning aid was used for reproducible positioning of the forearm in the seated position at the in-beam MR scanner as well as in supine position at the CT scanner. The aim of the present study was to assess the accuracy of arm positioning using this novel immobilization device.
Materials and Method: Six healthy volunteers (4 male, 2 female) were included in this study, that was approved by the local ethics committee. To mimic the setup at the CT scanner, they first underwent a T1-weighted gradient echo MRI scan at a clinical 3T system in supine position while being positioned on a flat tabletop overlay with their forearm fixed in the device. Secondly, the 3T MR image was digitally merged with a 0.22 T MR image of fiducial markers which have a fixed position relative to the beam in the irradiation room and are always within the field of view at the 0.22 T system. The merged image is considered the reference image prescribing the position of the forearm in the irradiation position planned for the future and is the aim of the positioning process. Thirdly, the volunteers underwent a T1-weighted gradient echo MRI scan at the 0.22 T system in seated position with their arm extended sideways in the device. In-house developed image processing software was used to rigidly co-register the locations of the markers in the latter MR image to those in the reference image. The forearm was repositioned in the device not more than twice to match the position in the reference image. The residual positioning difference of the radial bone was a measure of the positioning accuracy. Additionally, the distance of the bones to the skin surface was assessed as a measure for deformation of the arm.
Results: In 5 out of 6 the volunteers the largest positioning error in one dimension was less than 3 mm, which is comparable to that currently achieved in the clinic. The average time needed for repositioning was approximately 20 min, which is substantially longer than in routine clinical practice. Furthermore, the arm underwent a deformation that changed the skin-surface-to-bone distance mostly by approximately 3 mm.
Lastly, the device was not tolerated well by 5 volunteers due to uncomfortable arm positioning.
Conclusions: The positioning accuracy of a prototype CT-MR compatible arm holder device for in-beam MR-guided proton therapy of patients with a soft-tissue sarcoma of the forearm was evaluated. The device enables the immobilization of the forearm both in supine and seated position, with a clinically acceptable repositioning accuracy. Adjustments of the prototype holder are required to improve the patient’s comfort and to avoid the deformation of the arm.

In antiferromagnets, the interplay of spin frustration and spin-lattice coupling has been extensively studied as the source of complex spin patterns and exotic magnetism. Here, we demonstrate that, although neglected in the past, the spin-lattice coupling is essential to ferrimagnetic spinels as well. We performed ultrahigh-field magnetization measurements up to 110 T on a Yafet-Kittel ferrimagnetic spinel, MnCr₂S₄, which was complemented by measurements of magnetostriction and sound velocities up to 60 T. Classical Monte Carlo calculations were performed to identify the complex high-field spin structures. Our minimal model incorporating spin-lattice coupling accounts for the experimental results and corroborates the complete phase diagram, including two new high-field phase transitions at 75 and 85 T.Magnetoelastic coupling induces striking effects: An extremely robust magnetization plateau is embedded between two unconventional spin-asymmetric phases. Ferrimagnetic spinels provide a new platform to study asymmetric and multiferroic phases stabilized by spin-lattice coupling.

The high-field (H,T) phase diagram of the multiferroic lacunar spinel GeV₄S₈ has been studied by ultrasound, magnetization, and pyrocurrent experiments in magnetic fields up to 60 T. The title compound consists of molecular building blocks, with vanadium V4 clusters characterized by a unique electron density. These vanadium tetrahedra constitute a Jahn-Teller active entity, which drive an orbital-ordering transition at 30K with the concomitant appearance of ferroelectricity. Ultrasound and magnetization experiments reveal sharp anomalies in magnetic fields of 46 T, which are associated with a first-order phase transition into an orbitally disordered state characterized by significant field and temperature hystereses. We report a sequence of complex magnetic, polar, and orbitally ordered states, i.e., the appearance of two orbitally ordered phases OO1 and OO2 for μ₀H < 45 T and T < 30K. Beyond the paraelectric phase we further evidenced three ferroelectric phases, FE1, FE2, and FE3. Finally, antiferromagnetic (AFM) order (T < 15 K) and fully polarized ferromagnetic order (μ₀H > 60 T) have been observed in GeV₄S₈. At low temperatures and for fields below 40 T, AFM order coexists with the polar phase FE3 identifying a multiferroic state. Our results demonstrate a fascinating competition of the different orders, which the material manifests in high magnetic fields and at low temperatures.

The structural and magnetic properties of the compound Sm_1.2Ho_0.8Fe₁₇ and the nitride powders Sm_1.2Ho_0.8Fe₁₇N_2.4 prepared by high energy ball milling under various milling regimes are reported. Magnetic properties of the samples are investigated at 2–300 K in steady magnetic field up to 70 kOe and in pulsed magnetic field up to 600 kOe. The application of high magnetic field reveals the presence of the second-order transition in Sm_1.2Ho_0.8Fe₁₇N_2.4 at 500 kOe. Magnetic hysteresis properties study shows that ball milling enhances magnetic performance of Sm_1.2Ho_0.8Fe₁₇N_2.4 making it perspective for the magnets fabrication.

We report an unexpected magnetic-field-driven magnetic structure in the 5 f -electron Shastry-Sutherland system U₂Pd₂In. This phase develops at low temperatures from a noncollinear antiferromagnetic ground state above the critical field of 25.8 T applied along the a axis. All U moments have a net magnetic Moment in the direction of the applied field, described by a ferromagnetic propagation vector q_F = (0 0 0) and an antiferromagnetic component described by a propagation vector q_AF = (0 0.30 1/2 ) due to a modulation in the direction perpendicular to the applied field. We conclude that this surprising noncollinear magnetic structure is due to a competition between the single-ion anisotropy trying to keep moments, similar to the ground state, along the [110]-type directions, Dzyaloshinskii-Moryia interaction forcing them to be perpendicular to each other and application of the external magnetic field attempting to align them along the field direction.

A Docker image with a Slurm setup to enable testing of HPC software in a container.

GitLab HPC Driver prototype implementation.

Um gute Performance und Skalierbarkeit von hochparalleler wissenschaftlicher Software sicherzustellen, ist es wichtig, diese in einer möglichst realitätsnahen Umgebung zu testen. Wünschenswert ist dabei ein möglichst einfacher Zugriff auf die HPC-Ressourcen über ein bereits etabliertes System wie GitLab CI. Dafür wurde ein Driver für den GitLab-Runner entwickelt, der es erlaubt Continuous-Integration-Jobs auf Hochleistungsrechnern auszuführen. Der Driver wird vom GitLab-Runner-Service aufgerufen und kann vom Nutzer auf die gleiche Art und Weise verwendet werden, wie andere im GitLab-Ökosystem bekannte CI-Systeme. Es werden HPC-Ressourcen unterstützt, die vom Batchsystem Slurm verwaltet werden.

To ensure high performance and scalability in scientific software, a realistic testing environment plays an important role. Preferably, easy access to HPC resources is enabled via an established tool like GitLab CI. For that, a driver for GitLab runner has been developed that allows the execution of CI jobs on a supercomputer. The driver is called by GitLab runner service and can be used in the same way as other tools in the GitLab ecosystem. It supports HPC resources managed by the Slurm batch system.

High-statistics π−π− HBT data for non-central Au + Au collisions at 1.23A GeV, measured with HADES at SIS18/GSI, are presented. The three-dimensional emission source is studied in dependence on pair transverse momentum and centrality. A tilt of the source relative to the beam axis is observed. The spatial extension and the tilt magnitude of the source decrease with transverse momentum. The spatial extension decreases and the tilt magnitude increases going from central to peripheral collisions. The derived eccentricity perpendicular to the beam axis fits well to the initial nucleonic overlap region at high transverse momentum.

Seismically active fault zones receive a great deal of attention due to their potential for quantification of seismic hazards. Zones with low slip rates pose a challenge, however, since their poor topographic expression is related to difficulties in the quantification of fault movement. This study focuses on the Dobrá Voda Depression, an area with the highest level of seismic activity in the Western Carpathians. The Quaternary tectono-sedimentary evolution of the small intramontane basin was investigated with the use of facies analysis of cores, dated with the use of cosmogenic nuclide depth profiles (¹⁰Be, ²⁶Al and ³⁶Cl), together with ²⁶Al/¹⁰Be burial dating and radiocarbon dating. A set of archived boreholes and geoelectric survey data was used for the correlation of results with those from new boreholes across the depression. Four facies associations were distinguished: (FA1) Colluvial deposits that comprise subaerial debris flows and mudflows; (FA2) Fluvial deposits with high sediment supply: accommodation ratio, composed mostly of sandy-gravelly channel fill facies; (FA3) Fluvial deposits with low sediment supply: accommodation ratio, consisting mostly of floodplain muds, overbank heterolithic facies and minor sandy-gravelly channel fills; and (FA4) Swamp deposits, which are mostly made up of peat. Geochronological results suggest that the studied part of FA3 was deposited before 1.0 Ma due to a rise in the base level following a major incision event. Overbank-dominated deposits of FA3 covered an incision surface, resulted in a difference of ca. 65 m of elevation of these strata, which represents the minimal thickness of FA3. The second phase of incision was related to reactivation of Miocene normal faults resulting in further topographic differentiation. The initiation of fault activity is recorded by the deposition of colluvial FA1 before ca. 250 ka. FA2 accumulated between ca. 160 and 100 ka, mostly at the toes of slopes bounding the fault scarps on the basin margins. The last documented phase of evolution represents an increase of accommodation, which was connected to the deposition of Holocene peat in swamps as well as floodplain muds of FA4 above FA2. The observed settings imply that variation between incision and accumulation in a scale of hundreds of thousands of years is characteristic for low relief tectonically active zones. The presented research demonstrates the significance of sedimentological analysis for reconstruction of tectonic evolution in areas with low slip rate activity.

The nano-porosity embedded into the tilted and separated nanocolumns characteristic of the microstructure of evaporated thin films at oblique angles has been critically assessed by various variants of the positron annihilation spectroscopy. This technique represents a powerful tool for the analysis of porosity, defects and internal interfaces of materials, and has been applied to different as-deposited SiO₂ and TiO₂ thin films as well as SiO₂/TiO₂ multilayers prepared by electron beam evaporation at 70° and 85° zenithal angles. It is shown that, under same deposition conditions, the concentration of internal nano-pores in SiO₂ is higher than in TiO₂ nanocolumns, while the situation is closer to this latter in TiO₂/SiO₂ multilayers. These features have been compared with the predictions of a Monte Carlo simulation of the film growth and explained by considering the influence of the chemical composition on the growth mechanism and, ultimately, on the structure of the films.

Oxygen electrocatalysis is vital for advanced energy technologies, but inordinate challenges remain due to the lack of highly active earth-abundant catalysts. Herein, by nanostructuring and defect engineering, we enhance the catalytic properties of naturally occurring, but normally inactive ore hematite (Ht) by converting it to hematene (Hm) with oxygen vacancies (Ov-Hm), that becomes an efficient oxygen evolution reaction (OER) catalyst, being even superior to the state-of-the-art catalyst IrO2/C, with a current density of 10 mA/cm2 at a lower overpotential of 250 mV. The first-principles calculations reveal that the reduced dimensionality and defects on the Hm surface locally modify the charge around the adsorption sites, which results in a reduction of the potential barrier in the OER process. Our experimental and theoretical insights suggest a promising route to the development of a highly active electrocatalyst from the naturally occurring and abundant material for OER applications.

44/47Sc3+, 68Ga3+ and 111In3+ are the three most attractive trivalent smaller radiometalnuclides, offering a wide range of distinct properties (emission energies and types) in the toolbox of nuclear medicine. In this study, all three of the metal ions are successfully chelated using a new oxine-based hexadentate ligand, H3glyox, which forms thermodynamically stable and kinetically inert neutral complexes with exceptionally high pM values [pIn (34) > pSc (26) > pGa (24.9)]. X-ray diffraction single crystal structures with stable isotopes revealed that the ligand is highly preorganized and has a perfect fit to size cavity to form [Sc(glyox)(H2O)] and [In(glyox)(H2O)] complexes. Quantitative radiolabeling of 68Ga (RCY > 95%, [L]= 10-5 M) and 111In (RCY > 99%, [L]= 10-8 M) was achieved at ambient conditions (RT, pH 7 and 15 min) with very high apparent molar activities of 750 MBq/mol and 650 MBq/nmol, respectively. Preliminary quantitative radiolabeling of 44ScCl3 (RCY > 99%, [L] = 10-6 M) was fast at room temperature (pH 7 and 10 min). In vitro experiments revealed exceptional stability of both 68Ga(glyox) and 111In(glyox) complexes against human serum (rate of transchelation < 2%) and its suitability for biological applications. Additionally, on chelation with metal ions, H3glyox exhibits enhanced fluorescence which was employed to determine the stability constants for Sc(glyox) complex in addition to the in-batch UV-vis spectrophotometric titrations; as a proof-of-concept these complexes were used to obtain fluorescence images of live HeLa cells using natSc(glyox) and natGa(glyox), confirming the viability of the cells. These initial investigations suggest H3glyox to be a valuable chelator for radiometalbased diagnosis (nuclear and optical imaging) and therapy.

Ceramic powders produced by gas phase synthesis frequently consist of non-spherical, fractal-like particle aggregates. Their shape is a result of the simultaneous action of particle coagulation and sintering. Coagulation describes the process of particle agglomeration, e.g. due to ballistic or diffusion-limited collisions, whereas sintering stands for coalescence of primary particles and acts to create denser aggregates. A low density aggregate has a larger collisional cross-section and thus is more likely to collide with other particles or aggregates, which is reflected in the development of the aggregate size distribution and should be taken into account when modeling the process. To this end, a class method based population balance modeling approach available in OpenFOAM was extended to allow for a simplified bivariate treatment. Among the many shape-characterizing parameters, the average surface-area-to-volume ratio of each size class is tracked by a separate transport equation. Together with a fixed fractal dimension, it can be translated into a collisional diameter and further used when calculating coagulation rates. The functionality is showcased by a simulation of the vapor synthesis of Titania in a tubular aerosol reactor [Akhtar et al., AlChE J., 37(10): 1561-1570, 1991]. Data from a differential mobility sizer is used to validate the approach.

Proposal for a spin-polarized positron beam facility at the upcoming DALI facility

Materials Research with Positrons – From atomic defects to nano-scale porosimetry

Lake Mweru, located between the Northern Province of Zambia and the south-eastern Katanga Province of the Democratic Republic of Congo, is part of the southwest extension of the East African Rift System (EARS). Fault analyses have revealed that the Mweru-Mweru Wantipa fault system (MMFS) was formed due to the NW-SE rotation of the extension direction of the EARS and is responsible for the reorganization of the drainage system of the area since the Miocene, creating knickpoints as a result of intense seismic activity. Twenty-six quartzitic bedrock samples were collected predominantly from knickpoints across the Mporokoso Plateau (south of Lake Mweru, Zambia) and the eastern part of the Kundelungu Plateau (north of Lake Mweru, DRC). These samples were analyzed for in-situ cosmogenic ¹⁰Be and ²⁶Al using Accelerator Mass Spectrometry. Samples from the Mporokoso Plateau and close to the MMFS provide evidence of temporary cover. Samples located far from the MMFS have consistent ¹⁰Be and ²⁶Al exposure ages ranging up to ~830 ka, indicating that these surfaces were never covered since their initial exposure. The observed burial patterns, combined with morphotectonic analyses of the drainage system and evidence of lacustrine sediments, reveal the existence of an extensive paleo-lake during the Pleistocene.
Elevational analyses of the dated knickpoints constrain the level of the paleo-lake to around 1200 m asl and its area to around 40000 km².
Calculated high denudation rates (up to ~40 mm ka^-1) along the eastern Kundelungu Plateau suggest that tectonic forcing caused the breaching of the paleo-lake. Ensuing outflow gouged a deep-sided canyon, today occupied by the underfitting Luvua River. The complex exposure histories recorded in our study area by ¹⁰Be and ²⁶Al can be a result of waterlevel fluctuations caused by intense climate variations across southeastern Africa, coupled with active rifting along the MMFS.

INTRODUCTION
The disposal of nuclear waste including the assessment of long-term safety is still an open question in Germany. In addition to the pending decision about the repository host rock (salt, granite, or clay) and the associated site selection, the basic necessity of a consistent and obligatory thermodynamic reference database persists. Such a database is essential to assess potential radionuclide migration scenarios accurately and to make well-founded predictions about the long-term safety up to one million years. Specific challenges are comprehensive datasets covering also elevated temperatures and high salinities. Concerning the required elements (actinides, fission products as well as matrix and building materials), no other thermodynamic database is available that is compatible with the expected conditions. Due to these deficiencies THEREDA, a joint project of institutions leading in the field of safety research for nuclear waste disposal in Germany and Switzerland, was started in the year 2006.

DATABASE FEATURES

THEREDA offers evaluated thermodynamic data for many compounds (solid phases, aqueous species, or constituents of the gaseous phase) of elements relevant according to the present state of research. In particular, all oxidation states expected for disposal site conditions are considered. In the present release, THEREDA includes data for actinides and their chemical analogues (Th, U, Np, Pu, Am, Cm & Nd), fission products (Se, Sr, Tc & Cs) and matrix elements (Na, K, Mg, Ca, Al, Si | Cl, SO4, CO3). For the calculation of cementitious phases the current version of CEMDATA (18.1) was integrated.
THEREDA is based on a relational databank whose structure intrinsically ensures the internal consistency of thermodynamic data. Data considered respond to the needs of both Gibbs Energy Minimizers (ChemApp, GEMS) and Law-of-Mass-Action codes (Geochemist’s Workbench, PHREEQC, ToughReact). The database is designed generically so that it can store interaction parameters for various models. Namely, the PITZER ion interaction approach to describe activity coefficients of hydrated ions and molecules in saline solutions as well as ideal and non-ideal solid solution approaches are considered in the actual dataset.
After free registration, THEREDA is accessible via internet through www.thereda.de. This is not only a portal to view the data itself, their uncertainties and the primary references of the data; it provides also additional information on issues concerning the database. Ready-to-use parameter files are available for download in a variety of formats (geochemical code specific formats and generic ASCII type). They are also used for internal test calculations – an essential element of the quality assurance scheme. The capabilities of THEREDA are demonstrated using approx. 400 application case calculations, whose results were compared with experimental values published in literature.

The release of uranium from waste repositories into the ground water and surrounding soil can have adverse effects on the biomes of affected sites. The bioavailability and chemical toxicity of U(VI) species, which are the most prevalent in oxic environments of soils and water bodies, can pose serious threats as they are transferred through the food chain. Despite remediation strategies employing the cultivation of crop plants to sequester uranium, little is known of the mechanisms used by plants in processing the uranium species that they encounter. The aim of this research therefore has been to shed light on the pathways involved in the uptake and processing of uranium by plant cells, using the undifferentiated tobacco BY-2 cells as model plant cells. Former experiments showing increases in the cytoplasmic glutathione pools upon exposure of Brassica napus cell cultures to uranium have led us to the hypothesis that tobacco cells are able to reduce U(VI) to U(IV). This research describes a novel method of exposing BY-2 cells to U(VI) in phosphate deficient medium, which maintains relatively high cell viability under phosphate deficient conditions, and reveals differentially expressed proteins in the presence of uranium. Uranium-spiked culture medium was seen to affect the uptake of trace elements and minerals as well as show changes in the profiles of polyacrylamide-resolved proteins. Proteomics is being used to identify candidate proteins involved in the processing of uranium by the cells and microscopic visualization techniques are utilized to confirm these pathways and mechanisms.

Acknowledgments: This work is funded by the German Federal Ministry of Education and Research under the contract number 02NUK051B.

Gegenstand der vorliegenden Erfindung ist eine Vorrichtung zur Bestimmung des Strömungsprofils von Mehrphasenströmungen mit mindestens einer Flüssigkeitskomponente mit vorgegebener Strömungsrichtung. Die Vorrichtung weist eine Mehrzahl von stabförmigen Sonden auf. Jede der Sonden weist zwei parallel verlaufende Elektroden aus, die in einer gemeinsamen elektrisch isolierenden Umhüllung angeordnet sind. Darüber hinaus weist jede Sonde mindestens eine Abschirmelektrode auf. Eine Elektrode jeder Sonde fungiert als Transmitter (Sender) und die zweite Elektrode jeder Sonde als Receiver (Empfänger). Eine Auswerteeinheit ist dazu eingerichtet, die Transmitterelektrode jeder Sonde mit elektrischer Spannung als Messspannung zu beaufschlagen und das Ergebnissignal an der Receiverelektrode derselben Sonde zu erfassen. Mindestens zwei Sonden sind zu einer Gruppe zusammengefasst, wobei die Auswerteeinheit zum gleichzeitigen Beaufschlagen der Sonden dieser Gruppe mit der Messspannung ausgebildet ist.

In a simple and versatile reprocessing method for recycling U and Pu from spent nuclear fuels, cyclic amides like N-alkylated 2-pyrrolidone derivatives (NRPs) are exclusively employed. However, there have been no convincing rationales why such a heterocyclic structure is required. To answer this question, we employed N-cyclohexyl-2-pyrrolidone (NCP) and N-cyclohexylformamide (NCF) as cyclic and acyclic monodentate amides, and focused on the following 3 topics in this study; (1) structural chemistry of their uranyl dinitrato complexes, (2) precipitation behavior of UO22+ from HNO3(aq) by using these amides, and (3) their chemical stability in HNO3(aq) simulating the reprocessing process for spent nuclear fuels. Fundamental coordination chemistry of UO2(NO3)2(L)2 (L = NCP, NCF) were found to be common to both L, regardless of the presence or absence of the pyrrolidone ring. Furthermore, both L exhibit comparable capability in precipitation of UO22+ from HNO3(aq). The most critical difference between NCP and NCF was found in their chemical stability in HNO3(aq), where NCF was gradually decomposed through acid-catalyzed hydrolysis, while NCP remained intact for at least 4 h. In conclusion, the pyrrolidone ring of NRPs plays an important role to protect the carbonyl C from nucleophilic hydrolysis which initiates the amide C(=O)−N bond cleavage.

The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden –Rossendorf (HZDR). Our research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Ra-diation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. The program NUSAFE, and therefore all work which is done at IRE, belong to the research field “Energy” of the HGF...

Atomic scale defects generated using focused ion as well as laser beams can activate ferromagnetism in initially non-ferromagnetic B2 ordered alloy thin film templates. Such defects can be induced locally, confining the ferromagnetic objects within well-defined nanoscale regions. The characterization of these atomic scale defects is challenging, and the mechanism for the emergence of ferromagnetism due to sensitive lattice disordering is unclear. Here we directly probe a variety of microscopic defects in systematically disordered B2 FeRh thin films that are initially antiferromagnetic and undergo a thermally-driven isostructural phase transition to a volatile ferromagnetic state. We show that the presence of static disorder i.e., the slight deviations of atoms from their equilibrium sites is sufficient to induce a non-volatile ferromagnetic state at room temperature. A static mean square relative displacement of 9.10^-4 Å^-2 is associated with the occurrence of non-volatile ferromagnetism and replicates a snapshot of the dynamic disorder observed in the thermally-driven ferromagnetic state. The equivalence of static and dynamic disorder with respect to the ferromagnetic behavior can provide insights into the emergence of ferromagnetic coupling as well as achieving tunable magnetic properties through defect manipulations in alloys.

To summarize the distribution of glioma location within a patient population, registration of individual MR images to anatomical reference space is required. In this study, we quantified the accuracy of MR image registration to anatomical reference space with linear and non-linear transformations using estimated tumor targets of glioblastoma and
lower-grade glioma, and anatomical landmarks at pre- and post-operative time-points using six commonly-used registration packages (FSL, SPM5, DARTEL, ANTs, Elastix, and NiftyReg). Routine clinical pre- and post-operative, post-contrast T1-weighted images of 20 patients with glioblastoma and 20 with lower-grade glioma were collected. The 2009a
Montreal Neurological Institute brain template was used as anatomical reference space. Tumors were manually segmented in the patient space and corresponding healthy tissue was delineated as a target volume in the anatomical reference space. Accuracy of the tumor alignment was quantified using the Dice score and the Hausdorff distance. To measure the accuracy of general brain alignment, anatomical landmarks were placed in patient and in anatomical reference space, and the landmark distance after registration was quantified. Lower-grade gliomas were registered more accurately than glioblastoma. Registration accuracy for pre- and postoperative MR images did not differ. SPM5 and DARTEL registered tumors most accurate, and FSL least accurate. Non-linear transformations resulted in more accurate general brain alignment than linear transformations, but tumor alignment was similar between linear and non-linear transformation. We conclude that linear transformation suffices to summarize glioma locations in anatomical reference space.

Uranium–Americium oxides U1−yAmyO2±x are promising candidates as possible transmutation targets for next generation nuclear reactors. In the context of a comprehensive investigation of their thermodynamic and thermal properties, the behaviour in oxidizing conditions is here studied. In a recent work, the behaviour in air of stoichiometric and sub-stoichiometric U1−yAmyO2−x compounds, with various Am content, was investigated by high-temperature X-ray Diffraction. Herein, the hyper-stoichiometric oxides obtained from that study are investigated by X-ray Absorption Spectroscopy. The new data, together with the previous XRD results, allow determining the exact compositions of the samples and hence obtaining phase diagram points in the O-rich domain of the U-Am-O system. Indeed, five phase diagram points at 1473 K are obtained: two tie-lines in the M4O9-M3O8 domain, for Am/(Am + U) = 0.10 and 0.15, one tie line in the MO2+x-M3O8 domain, for Am/(Am + U) = 0.28, and two points in the single phase MO2±x domain, for higher americium concentration. From these data, it is also concluded that trivalent americium has a small solubility in the M4O9 and M3O8 phases.

We study radiative relaxation at terahertz frequencies in n-type Ge/SiGe quantum wells, optically pumped with a terahertz free electron laser. Two wells coupled through a tunneling barrier are designed to operate as a three-level laser system with non-equilibrium population generated by optical pumping around the 1→3 intersubband transition at 10 THz. The non-equilibrium subband population dynamics are studied by absorption-saturation measurements and compared to a numerical model. In the emission spectroscopy experiment, we observed a photoluminescence peak at 4 THz, which can be attributed to the 3→2 intersubband transition with possible contribution from the 2→1 intersubband transition. These results represent a step towards silicon-based integrated terahertz emitters.

Eine gängige Methode zur Konditionierung von Zulaufströmen in Rektifikations-kolonnen ist die Entspannungsverdampfung (flash) des Feedstroms mit nachgeschalteter oder integrierter Separation der kontinuierlichen und dispersen Phasenanteile. Die Gestaltung der Einspeisung in die Kolonne sowie die Auswahl von Einleitorganen erfordert eine möglichst exakte Vorhersage der sich einstellenden Strömungsmorphologie in der Feedleitung. Verfügbare Strömungsdaten beschränken sich fast ausschließlich auf Wasser-Luft-Systeme bei geringen Rohrdurchmessern (< DN100) und großen Einlauflängen (> 40 D). Deren Übertragbarkeit auf organische oder kryogene Systeme mit z. B. deutlich geringeren Grenzflächenspannungen für praxisnahe Rohrdimensionen unterliegt dabei großen Unsicherheiten. Zur Untersuchung flashender Feeds wurde daher ein Kältemittel-Versuchsstand im Technikums¬maßstab entwickelt. Das Arbeitsfluid wird durch eine Armatur in eine horizontale Feedleitung (DN200, Länge 20 D) entspannt und tritt als Zweiphasenströmung in die nachgeschaltete Kolonne ein. Die Dampfanteile nach der Entspannungsverdampfung werden über die jeweiligen Betriebsdrücke und -temperaturen mittels Elektroerhitzer und Kreislaufpumpe eingestellt, während der Betriebsdruck in der Teststrecke über einen Kondensator im Kopfstrom der Kolonne geregelt wird. Als Betriebsmedium wird das Kältemittel 3M™ Novec™649 eingesetzt, dessen Grenzflächenspannung in einem Bereich von 2 bis 8 mN m-1 bei einer Dichtedifferenz zwischen Dampf und Flüssigkeit von 800-1500 kg m-3 bei Betriebstemperaturen bis 140 °C eingestellt werden kann. Die Charakterisierung der sich entwickelnden Strömungsmorphologie in der horizontalen Feedleitung erfolgt mittels zeitlich und räumlich hochauflösender Gittersensormesstechnik. Schwerpunkte der Untersuchungen sind dabei die axiale Entwicklung der Strömungsform zwischen Entspannungsarmatur und Kolonneneintritt sowie die Bestimmung der Phasenanteile und Strömungs¬druck¬ver-luste
Diese Arbeit findet im Rahmen des Projektes TERESA statt und wird durch das Bundesministerium für Wirtschaft und Energie (BMWI) gefördert (FKZ 03ET1395D).

The nickel-monogermanide (NiGe) phase is known for its electrical properties such as low ohmic and low contact resistance in group-IV-based electronics. In this work, thin films of nickel germanides (Ni-Ge) were formed by magnetron sputtering followed by flash lamp annealing (FLA). The formation of NiGe was investigated on three types of substrates: on amorphous (a-Ge) as well as polycrystalline Ge (poly-Ge) and on monocrystalline (100)-Ge (c-Ge) wafers. Substrate and NiGe structure characterization was performed by Raman, TEM, and XRD analyses. Hall Effect and four-point-probe measurements were used to characterize the films electrically. NiGe layers were successfully formed on different Ge substrates using 3-ms FLA. Electrical as well as XRD and TEM measurements are revealing the formation of Ni-rich hexagonal and cubic phases at lower temperatures accompanied by the formation of the low-resistivity orthorhombic NiGe phase. At higher annealing temperatures, Ni-rich phases are transforms into NiGe, as long as the supply of Ge is ensured. NiGe layer formation on a-Ge is accompanied by metal-induced crystallization and a decline of its electrical conductivity compared with that of poly-Ge and c-Ge substrates. Specific resistivities for 30 nm Ni on Ge were determined to be 13.5 uOhm cm for poly-Ge, 14.6 uOhm cm for c-Ge and 20.1 uOhm cm for a-Ge.

Thermo-mechanical behavior of ablated reactor pressure vessel (RPV) during in-vessel melt retention is assessed. Specifically, we provide a preliminary synthesis of a benchmark exercise on a generic Pressurized Water Reactor (PWR) RPV with external water cooling. A two-layer pool configuration with a molten metal layer atop, reaching a local heat flux of 2 MW/m² on the vessel wall is assumed reflecting a focusing effect which in turn results in a thin ablated wall with remaining thickness of 16 mm. The aim is to investigate the effect of internal pressure on the structural integrity of the RPV. A total of 7 contributions from different organizations using 5 different codes are analyzed. The results are divided into low internal pressure cases where no vessel failure is expected, and high internal pressure cases where vessel failure is found based on specific failure criteria applied by the users. At 3 bar internal pressure, all the results reflecting stresses and strains indicate no vessel failure. Four contributions found vessel failures at internal pressure of 40, 45, 50, and 52 bars. The mode of failure in all calculations is the same, which is plastic instability caused by high stresses, although the failures are indicated by different criteria. Further, the results are compared against a simplified approach and reasonable agreement is found. Finally, a preliminary failure map is generated to demonstrate the applicability of a previously proposed methodology that utilizes a safety criterion based on the relation between the minimum vessel thickness and the maximum internal load.

One highly relevant challenge in flotation is the recovery of fine particles. Due to their low inertia, these particles are mostly pushed aside by rising bubbles. Consequently, they typically exhibit low probability for bubble-particle collision and thus, a poor recovery rate. In this work, the trajectories of fine particles in the vicinity of rising bubbles were investigated. The measurements considered a chain of millimetric bubbles within a rectangular container filled with deionized water. The flow field near the bubbles was measured by tomographic particle image velocimetry (TPIV), employing fluorescent tracer particles of 33µm diameter. Subsequently, trajectories of larger particles and bubble-particle collision events are recorded with 4D particle tracking velocimetry using a high temporal and spatial resolution. The results reproduce the well-known collision of particles on the leading edge of a rising bubble. Additionally, collisions on the tailing edge were observed in cases with a low Stokes number. The TPIV results demonstrate, that the high turbulent kinetic energy in the bubble wake allows particles to divert from the fluid streamlines and collide with the tailing edge of the bubble. The tailing edge collision probability increases with the Reynolds number and with decreased particle inertia. Overall, the investigation shows that the collision of fine particles in the bubble wake should be considered for the development of further collision probability models. Furthermore, the importance of turbulence on the fine particle flotation was demonstrated.

Understanding the tray hydrodynamics is important for their effective design as well as for the assessment of their separation performance. Currently, the clear liquid height is considered as one of the most important hydrodynamic parameters [1]. For example, it is utilized to correlate dispersion density, liquid entrainment rate, weeping flux and flow regime transitions. This height is usually measured at a point on the tray floor by continuously flushing out the liquid into the manometer. It is debatable whether such point reading is representative for the true liquid content on large trays or three-dimensional analyses should be performed. For this purpose, a sieve tray column (800 mm dia.) mockup facility is used in this work with air and tap water at respective loadings of 1.4 – 2.0 Pa0.5 and 1.0 – 3.0 m3/h that correspond to the froth regime.

A novel conductivity-based sensor [2] is developed for the 3D two-phase flow quantification at high spatial and temporal resolution. Basically, the local phase holdups at multiple locations along the sensor measurement plane and at different dispersion heights are determined here. It is assessed if the integration of the holdup profiles can lead to better estimates of the clear liquid height. Pressure drops and weeping rates are also measured. Furthermore, stimulus-response experiments with de-ionized water as tracer are performed at selective dispersion heights for identifying the flow profiles via residence time distribution.

These new 3D tray hydrodynamic data may also serve as a reference for establishing CFD models in the future, which so far have largely relied either on clear liquid height data only or on the low resolution data of Solari and Bell [3].

[1] Lockett, M.J., 1986. Distillation tray fundamentals.
[2] Vishwakarma, V., Schleicher, E., Schubert, M., Tschofen, M. and Löschau, M., Deutsche Patentanmeldung DE 10 2018 124 501.7, Sensor zur Vermessung von Strömungsprofilen in großen Kolonnen und Apparaten.
[3] Solari, R.B. and Bell, R.L., 1986. Fluid flow patterns and velocity distribution on commercial‐scale sieve trays. AIChE journal, 32(4), pp.640-649.

In a flotation cell, turbulence influences the motion of solid particles relative to the bubble surface, and, thus, affects the recovery rate. But, the impact of turbulence on the probability of a bubble-particle aggregation is still difficult to measure, especially in a dense flow. Therefore, the focus of this work was to apply PEPT as a method to investigate the effect of turbulence on the particle movement and bubble-particle interaction in an opaque flow. Single air bubbles (db=2.5 mm) were generated on a needle in a water flow channel. Upstream, a grid produced an isotropic turbulent flow with 5% to 15% turbulence intensity and a Kolmogorov microscale of 20µm. Depending on the distance to the grid, the flow near the captive bubble (Reb~450) was characterized by eddies of different length scales and magnitude with tomographic PIV. The solid suspension contained up to 0.3% PMMA particles (dp=200-400µm) and up to six radiolabelled particles (dp=300-400µm) coated with PMMA. The trajectories of the labelled particles were used to determine the average particle distribution in the turbulent field and describe the bubble-particle interactions. These results provide valuable information on the applicability of PEPT in turbulent and dense flow fields as well as on particle trajectories close to bubbles, enhancing our understanding of key flotation phenomena.

Purpose: Emerging clinical evidence supports the variability of relative biological effectiveness (RBE) in proton radiotherapy. This poses the need to account for RBE variability in proton planning. However, no harmonized concept exists on how to calculate the RBE-driving linear energy transfer (LET) in clinical practice. Therefore, a multi-centric study was set up with the objective to standardize clinical LET calculations in Europe.

Methods: Eight European institutions generated non-robust SOBP plans using common strict dose objectives. Multiple treatment field arrangements (single-field SOBP, perpendicular fields, opposing fields) were employed to cover a target cube in a water phantom. Each institution used its preferred treatment planning software and provided dose and corresponding LET distributions for a joint analysis.
Subsequently, RBE-weighted dose (DRBE) distributions were calculated for the single-field SOBP of one institution assuming the Wedenberg RBE model using Monte Carlo calculated unrestricted dose- and track-averaged LET (LETd/LETt) distributions considering (1) only primary protons, (2) all protons, (3) all particles with Z≤2.

Results: Institutional SOBP ranges and target average doses agreed within 2%. In contrast, near-minimum, average and near-maximum LETd differed up to 30%, 19% and 5% in the target, respectively. These discrepancies could partially be explained by different algorithms (Monte Carlo/analytical) and by different ions included in the LETd calculations.
LETd calculations were more sensitive to the considered secondary particle spectrum than LETt. Deriving DRBE using LETd yielded 0-11%, 4-12% and 12-45% higher DRBE in the entrance, target and distal edge regions, respectively, compared to LETt. The biological range extension using LETd (and LETt) was approximately 3 mm (and 1 mm).

Conclusions: Despite comparable dose distributions, substantial LET differences occurred among the participating institutions. These differences hamper the consistent analyses of clinical follow-up data as they translate to substantial discrepancies in predicted DRBE. Therefore, standardization of clinical LET calculations is of utmost importance.

This is the second part of a special issue of the American Journal of Science examining a problem that defines, perhaps more than any other, the state-of-the-art in the geochemistry of fluid-solid interaction: how to integrate data from both observations and modeling of events of brief duration at essentially atomic scales (for example, attachment, diffusion, detachment, hydrolysis), to that of mesoscale, ensemble processes (crystal dissolution, growth, alteration). The ultimate goal is an understanding of the long-term, phenomenological consequences of these interactions, often termed “upscaling”. Success in predicting and constraining these latter outcomes determines the larger value of this field, both to neighbors in environmental sciences and engineering, as well as to the public in terms of policy, education, and support. Nanoscale observation of mineral surfaces via instruments such as AFM and VSI is now widespread; increases in resolution and analytical capability of these instruments have also evolved in tandem with advances in the power and resolution of simulation and modeling approaches. Closely tied to an emerging theoretical framework, this “soft” progress in simulation and modeling was the focus of the first part of this issue.

Dissolution rates of porous crystalline materials reflect the superposition of transport and surface control, mainly via the parameters saturation of the ambient fluid and distribution of surface energy. As a result, reacting surfaces evolve over time showing a heterogeneous distribution of surface rates. The spatiotemporal heterogeneity of surface reaction rates is analyzed using the rate map and rate spectra concept. Here, we quantify the dissolution rate variability covering the nm- to mm-scale of dissolving single-crystal and polycrystalline calcite samples, using a combined approach of X-ray micro-computed tomography (µ-CT) and vertical scanning interferometry (VSI). The dissolution experiments cover reaction periods from 15 minutes up to 54 days. The observed rate ranges are remarkably consistent over the entire reaction period but include a variability of about two orders of magnitude (10-9 - 3 * 10-7 mol m-2 s-1). The rate map data underscore the concurrent and superimposing impact of surface- vs. fluid flow controlled rate portions. The impact of fluid flow on reactivity at the mm-scale in the transport-controlled system is confirmed by 2-D reactive transport modeling. The sub-mm spatial heterogeneity of low vs. high reactivity surface portions of polycrystalline calcite is clearly below the mean crystal size. This suggests the dominant impact of highly reactive surface portions irrespective of the orientation of larger crystals on the overall surface reactivity. Correspondingly, the overall range of intrinsic reactivity heterogeneity as observed using singly crystal material is not further expanded for polycrystalline material. As a general conclusion, numerical reactive transport concepts would benefit from the implementation of a reactivity term resembling the experimentally observed existence of multiple rate components.

Nucleotide pyrophosphatase/phosphodiesterase 4 (NPP4) is a membrane-bound enzyme that hydrolyzes extracellular diadenosine polyphosphates such as Ap3A and Ap4A yielding mononucleotides. NPP4 on the surface of endothelial cells was reported to promote platelet aggregation by hydrolyzing Ap3A to ADP, which activates pro-thrombotic G protein-coupled P2Y1 and P2Y12 receptors. Thus, NPP4 inhibitors have potential as novel antithrombotic drugs. In the present study we expressed soluble human NPP4 in Sf9 insect cells and established an enzyme assay using diadenosine tetraphosphate (Ap4A) as a substrate. The reaction product ATP was quantified by luciferin-luciferase reaction in a 96-well plate format. The sensitive method displayed a limit of detection (LOD) of 14.6 nM, and a Z’-factor of 0.68 indicating its suitability for high-throughput screening. The new assay was applied for studying enzyme kinetics and led to the identification of the first NPP4 inhibitors.

Artificial ferromagnetic (FM)/nonmagnetic multilayers, with large enough FM thickness to prevent the dominance of interface anisotropies, offer a straightforward insight into the understanding and control of perpendicular standing spin wave (PSSW) modes. Here we present a study of the static and dynamic magnetic properties of [Co(3.0nm)/Au(0.6nm)]1≤N≤30 multilayer systems. Magnetometry reveals that the samples exhibit magnetization reversal properties typical of an effective single layer with weak perpendicular anisotropy, with the distinctive thickness-dependent magnetization reorientation transition from in-plane to out-of-plane. When such multilayer systems are out-of-plane saturated however, the dynamic response reveals the existence of several different ferromagnetic resonances in the form of PSSW modes that strongly depend on the material modulation characteristics along the total thickness. These modes are induced by the layer stacking itself as the effective single layer model fails to describe the complex dynamics observed in the system. In contrast to most systems considered in the past, described by a dynamic model of a single effectively homogeneous thick layer, the specific structures investigated here provide a unique platform for a large degree of tunability of the mode frequencies and amplitude profiles. We argue that the combination of periodic magnetic properties with vertical deformation gradients, arising from heteroepitaxial strain relaxation, generates a vertical regular array of two-dimensional pinning sites for the PSSW modes, which promotes the complex dynamics observed in the system.

In the framework of the EU H2020 IVMR project, the applicability and technical feasibility of In-Vessel Melt Retention (IVMR) for high power reactors is assessed. HZDR contribution to the project was the investigation of the IVMR strategy for German Pressurized Water Reactor of type Konvoi (high power reactor with 1300 MWe). Four different severe accident scenarios with core material relocation to the lower head have been studied with the severe accident code ATHLET-CD, including Station Blackout (SBO), and Loss-of-Coolant accidents (LOCA) of various leak sizes in combination with SBO. The molten corium pool formed in the lower head and the ablation of vessel wall have been studied. The observed maximum heat flux on the outer surface of the wall is in the range between 1.47 MW/m² (SBO) and 1.67 MW/m² (LOCA). The corresponding minimum wall thickness is 25 mm and 21 mm, respectively. The simulations showed that with the assumptions made, IVMR seems to be possible for the investigated accident scenarios without vessel failure.

Motivation und Ziel
Trennkolonnen zur Separation von Mehrkomponentenströmen finden vielfältigen Einsatz in der chemischen Industrie. Für den Betrieb solcher Apparate ergeben sich im Zusammenhang mit der zunehmenden Energiebereitstellung aus erneuerbaren Quellen wachsende Anforderungen im Hinblick auf eine flexible Fahrweise. Vor allem vergrößerte Über- und Unterlastbereiche, in denen dennoch eine hohe Trenneffizienz gewährleistet werden soll, stellen für die Auslegung eine Herausforderung dar. Insbesondere für Querstromböden mit sogenannten Fixed- und Push-Valves mangelt es bislang an verlässlichen Methoden, um den Einfluss des Bodendesigns auf die komplexe Zweiphasenströmung von Flüssigkeit und Dampf abzuschätzen.
Im Rahmen eines AiF-Forschungsvorhabens verfolgt das hier vorgestellte Teilprojekt das Ziel, ein Simulationsmodell bereitzustellen, mit welchem die Einflüsse von Ventilart, -anzahl und -anordnung sowie verschiedener Betriebsbedingungen auf die makroskopische Strömungsausbildung auf dem Querstromboden untersucht werden können.

Strategie und Methoden
Ausgangspunkt für die Modellentwicklung bildet zunächst die Simulation der Strömung am Einzelventil unter Nutzung des am HZDR entwickelten Mehrfeld-Zweifluid-Konzeptes (GENTOP, vgl. [1]). Hiermit werden sowohl großräumig separierte als auch disperse Phasenverteilungen sowie Übergänge zwischen diesen Strömungsmorphologien erfasst. Nach einer Validierung mit experimentell ermittelten Vergleichsdaten dienen die für vielfältige Betriebsbedingungen vorliegenden Simulationsergebnisse als Basis für die Ableitung von Feinstrukturmodellen für einen grobskaligen Modellierungsansatz. Für letzteren wird ein Euler-Euler-Modell favorisiert, in welchem die Effekte der nicht aufgelösten Phaseninteraktion über pragmatische Schließungsgleichungen integriert werden und die Abbildung der Ventile mittels punktartiger Massen- und Impulsquellen realisiert werden kann. Zur Validierung dieses Modells werden zunächst Simulationen für einzelne Ventile und Ventilgruppen durchgeführt und diese mit experimentellen Daten verglichen. Dazu wird ein Versuchsstand aufgebaut, an dem die Zweiphasenströmung an Einzelventilen oder Ventilgruppen unter definierten Betriebsbedingungen untersucht werden kann. Hierbei ist u. a. der Einsatz bildgebender Messverfahren geplant, um detaillierte Informationen über die Strömungsfelder und -regime zu erhalten. Um die Eignung des Grobstukturmodells zu demonstrieren, sind abschließend Vergleiche mit Experimentaldaten einer Versuchsanlage im industriellen Maßstab geplant.

Literatur
[1] Hänsch, S.; Lucas, D.; Krepper, E.; Höhne, T.: A multi-field two-fluid concept for transitions between different scales of interfacial structures. International Journal of Multiphase Flow 47 (2012) 171-182

For treatment individualisation of patients with locally advanced head and neck squamous cell carcinoma (HNSCC) treated with primary radiochemotherapy, we explored the capabilities of different deep learning approaches for predicting loco-regional tumour control (LRC) from treatment-planning computed tomography images. Based on multicentre cohorts for exploration (206 patients) and testing (85 patients), multiple deep learning approaches including extraction of deep features, transfer learning and complete training from scratch with 2D and 3D convolutional layers were assessed and compared to a clinical model including the tumour volume. Analyses were based on Cox proportional hazards regression and performance was assessed by the concordance index (C-index). While all 2D approaches showed similar or worse performance than the clinical model on the test cohort (C-index 0.39), 3D convolutional neural networks achieved improved discrimination (C-index 0.31) and patient stratification into high and low risk groups of tumour recurrence (p=0.001), in particular when using model ensembles instead of single models. Prospective validation of this result is planned.

Contribution to Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik, Adsorption und Extraktion

This work aims at investigating the production feasibility of a high yield product from a landfill suitable for feeding to an iron concentration plant. For this purpose, the samples were taken from tailing dumps of 3 Chahoun mine contained less than 10% iron content. After primary sample preparations, the representative samples were divided into two parts i.e. coarser and finer than 4 mm. it was concentrated by a medium intensity magnetic separator (MIMS) with a velocity of 1.5 m/s at rougher stage. The tailing and product were crushed by a jaw crusher down to 10, 6, 2 mm and followed by a low intensity magnetic separator (LIMS) with speeds of 1.5, 3, 4 m/s in the cleaner and scavenger stages. The results show that iron recovery is most likely to occur in samples with coarse grain size in the tailings. The highest weight recovery, iron and iron oxide content were obtained in low intensity magnetic separator at a velocity of 1.5 m/s in the cleaner stage that was about 18 and 35%, respectively, with dimensions less than 2 mm, which it has the highest iron and iron oxide separation rates of 46 and 54%, respectively.

Despite the four-decade study on ultrasound’s (US) impact on mineral’s floatabilities, there is still not a clear image regarding its role in mineral surface wettability. For this purpose, the current investigation endeavours the wettability and floatability characteristics of a chalcopyrite-pyrite-quartz (Cp-Py-Qtz) system in the presence and absence of an ultrasonic pre-treatment. The ultrasonic process was carried out by a Sonopuls at a constant frequency of 20 kHz with an adjustable power level from 30 to 200 W. Initially, impact of sonication time (15, 30, 45, 60 and 90 s as well as 10, 20 and 30 min) and power level (30, 60, 90, 120 and 180 W) were evaluated while the dissolved oxygen, temperature, conductivity and pH were monitored. Collector-less micro-flotation tests were carried out on the non-pre-treated and the US pre-treated samples at 60 W and 15 s. The samples’ hydrophobicities were determined by the drop shape analysis approach. The dissolved-oxygen level was varied using a mini bench pressurized water reactor to study the effect of O2(aq) concentration on the chalcopyrite and pyrite wettability characteristics. The results showed that the minerals’ hydrophilicities were relatively sensitive to the sonication’s time than its power that resulted in reducing all three minerals’ hydrophilicities. In addition, it was found that the dissolved oxygen content and creation of sub-micron sized bubbles led to an improvement on chalcopyrite and pyrite’ hydrophobicities. Finally, we proved that the Cp’s floatability increased and Qtz’s recovery reduced while being subjected to the ultrasonic irradiation (15 s at 60 W), however, Py’s recovery remained constant. This conclusion confirmed possibility of a selective separation in ultrasound-assisted copper ore flotation. We recommend further advanced investigations are highly required e.g. using an X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and atomic force microscopy (AFM) to profoundly understand the surface modification induced by the ultrasonication.

We present an analysis of proton number fluctuations in sqrt(s_NN) = 2.4 GeV Au+Au collisions measured with the High-Acceptance DiElectron Spectrometer (HADES) at GSI. With the help of extensive detector simulations done with IQMD transport model events including nuclear clusters, various nuisance effects influencing the observed proton cumulants have been investigated. Acceptance and efficiency corrections have been applied as a function of fine grained rapidity and transverse momentum bins, as well as considering local track density dependencies. Next, the effects of volume changes within particular centrality selections have been considered and beyond-leading-order corrections have been applied to the data. The efficiency and volume corrected proton number moments and cumulants Kn of orders n = 1, . . . , 4 have been obtained as a function of centrality and phase-space bin, as well as the corresponding correlators C_n . We find that the observed correlators show a power-law scaling with the mean number of protons, i.e. Cn∝n, indicative of mostly long-range multi-particle correlations in momentum space. We also present a comparison of our results with Au+Au collision data obtained at RHIC at similar centralities, but higher sqrt(s_NN).

Biomaterials with attenuated adverse host tissue reactions, and meanwhile, combining biocompatibility with mimicry of mechanical and biochemical cues of native extracellular matrices (ECM) to promote integration and regeneration of tissues are important for many biomedical applications. Further, the materials should also be tailorable to feature desired application-related functions, like tunable degradability, injectability, or controlled release of bioactive molecules. Herein, a non-covalently assembled, injectable hydrogel system based on oligopeptides interacting with sulphated polysaccharides is reported, showing high tolerability and biocompatibility in immunocompetent hairless mice. Altering the peptide or polysaccharide component considerably varies the in vivo degradation rate of the hydrogels, ranging from a half-life of three weeks to no detectable degradation after three months. The hydrogel with sulphated low molecular weight hyaluronic acid exhibits sustained degradation-mediated release of heparin-binding molecules in vivo, as shown by small animal magnetic resonance imaging and fluorescence imaging, and enhances the expression of vascular endothelial growth factor in hydrogel surrounding. In vitro investigations indicate that M2-macrophages could be responsible for the moderate difference in pro-angiogenic effects. The ECM-mimetic and injectable hydrogels represent tunable bioactive scaffolds for tissue engineering, also enabling controlled release of heparin-binding signalling molecules including many growth factors.

Radioactive contamination resulting from major 29 nuclear accidents presents harsh environmental conditions. Inside the Chernobyl exclusion zone, even more than 30 years after the accident, the resulting contamination levels still does not allow land-use or human dwellings. To study the potential of basidiomycete fungi to survive the conditions, a field trial was set up 5 km south-south-west of the destroyed reactor unit. A model basidiomycete, the lignicolous fungus Schizophyllum commune, was inoculated and survival in the soil could be verified. Indeed, one year after inoculation, the fungus was still observed using DNA dependent techniques. Growth led to spread at a high rate, with approximately 8 mm per day. This shows that also white-rot basidiomycetes can survive the harsh conditions in soil inside the Chernobyl exclusion zone. The resistance against radiation was higher than 20 μSv/day with this unadapted fungal strain.

A holographic model of probe vector mesons (quarkonia) is presented, where the dynamical gravity-dilaton background is adjusted to the thermodynamics of 2 +1 flavor QCD with physical quark masses. The vector meson action is modified to account for various quark masses. We focus on the Φ, J/ψ and Υ meson melting in agreement with hadron phenomenology in heavy-ion collisions at LHC, that is the formation of hadrons at the observed freeze-out temperature of 155 MeV.

In the present study we have investigated the complexation of uranyl(VI) with chloride and fluoride using luminescence spectroscopy (TRLFS, time-resolved laser-induced fluorescence spectroscopy). At 25 °C, in the presence of 0 − 0.175 M fluoride, the first single-component emission spectra for all four U(VI)-fluoride complexes, i.e. UO2F+, UO2F2, UO2F3−, and UO2F42− could be extracted. Based on the aqueous speciation derived from the TRLFS data, logK* values at I = 1 M were calculated for all these complexes and extrapolated to infinite dilution using the SIT approach. In the case of chloride, however, quenching of the U(VI)-luminescence hampered the experiments. Thus, U(VI)-complexation was studied with TRLFS at liquid nitrogen temperatures. Samples were prepared at 25 °C with chloride concentrations ranging from 0 to 1.0 M followed by instantaneous freezing and subsequent luminescence spectroscopic measurements at −120 °C. This allowed for the determination of the first luminescence spectra for the UO2Cl+ complex with the TRLFS method. The chloride quench reaction was further studied in the temperature range 1 – 45 °C using Stern-Volmer analysis. By applying the Arrhenius and the Eyring equations we obtained the first thermodynamic parameters for the dynamic quench process, i.e. the activation energy (Ea = 55.0 ± 12.9 kJ/mol), enthalpy (ΔHǂ = 52.5 ± 13.0 kJ/mol), and entropy (ΔSǂ = 103.9 ± 42.8 J/mol∙K).

The contactless inductive flow tomography is a measurement technique for the determination of the flow structure of an electrically conducting liquid. The procedure is based on the measurement of the magnetic field and can potentially be applied for visualisation and online-monitoring of industrial processes as, for example, continuous steel casting or the production of mono-crystalline silicon using the Czochralski crystal growth method. With the aid of the measured field values, the velocity field is reconstructed by solving a linear inverse problem that is described by a system of coupled integral equations. The frame rate of the field measurement is typically in the order of one frame per second, whereas the inversion of the integral equations usually takes about twenty times as long, since a regularisation parameter needs to be determined for each reconstruction. In order to reduce this discrepancy, a new algorithm is introduced in this article. The algorithm relies on the pre-computation of inverted matrices, so that the inversion can be determined solely by performing matrix-vector products. This technique reduces the time required for the inversion process at each reconstruction to same length of time a measurement cycle takes, i.e. about one second. The efficiency of the method will be demonstrated using a modified Rayleigh-Bénard experiment with liquid metal at room temperature.

Eph receptor tyrosine kinases, particulary EphA2 and EphB4, represent promising candidates for molecular imaging due to their essential role in cancer progression and therapy resistance. Xanthine derivatives were identified to be potent Eph receptor inhibitors with IC₅₀ values in the low nanomolar range (1-40 nm).These compounds occupy the hydrophobic pocket of the ATP-binding site in the kinase domain. Based on lead compound 1, we designed two fluorine-18-labeled receptor tyrosine kinase inhibitors ([¹⁸F]2/3) as potential tracers for positron emission tomography (PET). Docking into the ATP-binding site allowed us to find the best position for radiolabeling. The replacement of the methyl group at the uracil residue ([¹⁸F]3) rather than the methyl group of the phenoxy moiety ([¹⁸F]2) by a fluoropropyl group was predicted to preserve the affinity of the lead compound 1. Herein, we point out a synthesis route to [¹⁸F]2 and [¹⁸F]3 and the respective tosylate precursors as well as a labeling procedure to insert fluorine-18. After radiolabeling, both radiotracers were obtained in approximately 5% radiochemical yield with high radiochemical purity (>98%) and a molar activity of >10 GBq/µmol. In line with the docking studies, first cell experiments revealed specific, time-dependent binding and uptake of [¹⁸F]3 to EphA2 and EphB4 overexpressing A375 melanoma cells, whereas [¹⁸F]2 did not accumulate at these cells. Since both tracers [¹⁸F]3 and [¹⁸F]2 are stable in rat blood, the novel radiotracers might be suitable for in vivo molecular imaging of Eph receptors by, e.g., PET.