Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The present paper gathers the main insights obtained during the numerical simulation of a 10 % main steam line break (MSLB) in a generic German PWR KONVOI reactor with the thermal-hydraulic system code ATHLET 3.1 A. The contents of this paper are focused first on the transient thermal-hydraulic calculation during affected steam generator (SG) 1 boil-off and subsequently on the multidimensional fluid mixing study of the overcooled water stream and the coolant in the reactor pressure vessel. With this aim, the boundary conditions from the test PKL G3.1, carried out at the PKL test facility in the framework of the OECD/PKL-II project, are implemented in the simulation over the plant nominal parameters from the KONVOI reactor. The thermal-hydraulic and fluid mixing results obtained in the simulations are qualitatively assessed against suitable experimental data from the PKL and ROCOM test facilities, showing a good agreement between simulation and test behaviour.

Annular-dispersed two-phase flow in pipes consists of a thin wavy liquid film covering the pipe wall and a gas core with entrained liquid droplets. Knowledge of the film thickness and entrained liquid fraction is of importance in numerous industrial applications, such as the thermal design of heat exchangers.
The application of X-ray microtomography to obtain these parameters in case of small diameter pipes is presented here. The three-dimensional, time-averaged liquid fraction distribution has been measured in air-water annular flow in a horizontal pipe. In combination with pressure drop measurements, the film and entrained liquid mass flow rates are derived using a simple annular flow model. The portrayed method may also serve as a basis for the validation of computational fluid dynamics simulations of annular flow.

The long‐term availability of minerals and metals from primary (i.e. geogenic) and secondary (i.e. recycling) resources is not only the key to most economic activity, but also to the realization of important societal developments, such as the transition to a renewables‐based energy system and the rollout of e‐mobility. Due to several factors, the utilization of raw materials from geogenic sources will continue to form an essential part of the raw materials supply for a growing global population. In order to develop a highly skilled work force, to develop novel approaches for raw materials utilization, approaches that deploy resource‐ and energy‐efficient technologies for the delineation, extraction and beneficiation of mineral resources, while at the same time minimizing environmental risks, the Helmholtz International Research School for Predictive Geometallurgy (PREDICT) provides the first‐ever training programme dedicated to predictive geometallurgy and adaptive processing. PREDICT has pooled the interdisciplinary and intersectoral expertise of leading German and South African research institutes, world‐leading mining and metallurgical companies, covering all the links in the raw materials chain from exploration to mineral beneficiation and mine planning. PREDICT not only develops cuttingedge methodologies to take geometallurgical resource potential models to an entire new level but also implements and tests an optimal adaptive processing approach for a beneficiation plant model. In addition, we will combine both models by establishing feedback loops for model reconciliation.
Furthermore, PREDICT will close the loop by implementation of the model results in a simulation‐based mine‐planning block model.

This part of a series of two papers compares CFD simulation results of a boron dilution scenario with experimental results. The simulation was carried out with ANSYS CFX using the SST turbulence scheme, experimental data were produced in the ROCOM test facility, experiment E2.3. The main features of the scenario are asymmetric, transient mass flow conditions in the affected loops 1 and 2 of a KONVOI-type reactor vessel and reduced density of the underborated coolant slugs fed into the reactor trough the cold legs of both loops. The CFD simulation was able to capture the density stratification in the loops affected by underboration and the mixing in the downcomer and in the lower plenum. Good agreement with the experiment was obtained for the temporal evolution of average boron concentration in several measuring sections of the reactor vessel and of the boron distribution in the core inlet. In general, minimal values of boron concentration were found to be lower in the simulation than in the experiment.

The modern mining industry faces a number of important technical challenges, such as declining ore grades, complex mineral associations, fine-grain size and increasing geological variability. To meet these challenges geometallurgical models are constructed to quantita-tively predict how ores will behave during extraction and beneficiation. Current geometal-lurgical programs carried out by industry, focus on the definition of larger spatial domains that have similar characteristics. However, a consequent application and further develop-ment of geometallurgical programs should lead to an implementation of spatially more highly resolved geometallurgical resource models that are truly predictive for each mined block (including uncertainty), in order to improve raw material quality control and the process efficiency of mining operations. Such an approach would also enable the targeted recovery of by-products, which may generate significant additional revenue and improve overall efficiency. In order to construct relevant resource models, detailed quantitative information on the spatial distribution and geometallurgical behaviour of the by-products within the deposit is crucial.
The aim of this thesis is the development and creation of a predictive geometallurgical model by means of a case study and the presentation of the resulting advantages for the extraction of ores. Based on this, a general structure for the development of predictive geo-metallurgical models is developed, which can be applied to different types of commodities, as well as by-products, is cost-efficient, able to adapt to future data, and predicts metallurgi-cal parameters. As the case study serves the Thaba Chromium Mine in the western Bushveld Complex (South Africa), which is operated by Cronimet Chrome Mining SA (Pty) Ltd. In par-ticular, this thesis focusses on four distinct chromitite seams of the Lower and Middle Groups (LG and MG) at Thaba Mine, namely the LG-6, LG-6A, MG-1 and MG-2, which are considered as target seams for an open-cast and future underground mining scenario.
In order to understand the geological and geochemical architecture of the Thaba Mine deposit and as a foundation of the predictive geometallurgical model, an extensive geo-chemical dataset as well as logging and drill core data provided by Cronimet was evaluated and a 3D geological model was developed. A statistical assessment was performed to evalu-ate the variability within and between the chromitite seams and to separate the mine lease area into distinct geochemical clusters. The distribution of the samples belonging to the dif-ferent geochemical clusters was then transposed onto the geology of the mine lease area. This allowed the definition of spatial domains. These spatial domains, recognized by the as-sessment of assay data only, are then validated by mineralogical attributes; implications for mineral beneficiation are tested and verified.
According to this assessment, the chromitites of the Thaba Mine area can be subdivided into three distinct geochemical domains, domains that constitute the suitable foundation for a geometallurgical model. An extensive supergene altered domain or weathered domain is distinguished from a domain affected by hydrothermal alteration. The latter domain occurs below the depth of modern weathering, but in obvious proximity to faults and around a prominent dunite pipe. The third domain is represented by ores least affected by post-magmatic alteration processes. This domain occupies the centre of fault blocks below the extent of modern weathering.
Furthermore, the geochemical data is used to develop a tailored and easy-to-use multi-variate classification scheme for the chromitite layers in the Thaba Mine, based on a com-prehensive classification routine for the LG and MG chromitites. This routine allows a clear attribution with known uncertainty of all relevant chromitite layers. It comprises of a hierar-chical discrimination approach relying on linear discriminant analysis and involves five dis-tinct steps. Overall classification results for unknown samples belonging to one of the layers are 81 %. The approach may, however, be extended across the entire Bushveld, provided that an appropriate geochemical data set is available.
For detailed characterization of the mineral assemblages in the chromitite ores, selected core samples of the target layers were analysed in detail by various analytical methods, such as Mineral Liberation Analysis and Electron Probe Microanalysis. Therefore, we extended the common measurement protocols for electron probe microanalysis to ensure applicability to a wider range of PGM compositions and its overall accuracy as well as consistency. Based on the results two distinct major mineral assemblages are defined: The first assemblage is rich in platinum group element-sulphides, along with variable proportions of malanite/ cu-prorhodsite and alloys of Fe and Sn. The associated base metal sulphides are dominated by chalcopyrite and pentlandite, along with pyrite and subordinate millerite/ violarite. Associ-ated silicates are mainly primary magmatic orthopyroxene and plagioclase. The second as-semblage is rich in platinum group element-sulpharsenides and -arsenides as well as -antimonides and -bismuthides, which are associated with a base metal sulphide assemblage dominated by pentlandite and Co-rich pentlandite. The assemblage is also marked by an abundance of alteration minerals, such as talc, serpentine and/or carbonates, which are closely associated with the platinum group minerals. Statistical evaluation reveals that these two mineral assemblages cannot be attributed to their derivation from different chromitite layers, but document the effects of pervasive hydrothermal alteration.
The knowledge of the detailed mineralogical investigation was transferred to a large da-taset comprising similar mineralogical data for unweathered ore of the deposit. Hence, it was possible to identify seven distinct ore types via statistical assessment, subsequently val-idated through beneficiation tests of drill core material. In addition, metallurgical test work for large batch samples of the weathered domain was carried out. Furthermore, beneficia-tion tests were aligned with process chemistry and mineralogy to monitor the results.
The predictive geometallurgical model aims to express the recoverability of PGE as by-product from the chromite processing stream. Within this context, the weathered ores were regarded as a single domain, as chromite ores from this oxidized zone were consistently found to have very low PGE recoveries. Any attempt to recover PGE by flotation from this zone appears to be challenging. For unweathered ores, the approach towards a predictive geometallurgical model needs to be somewhat more complex. The following steps were performed:
(i) Building a predictive model of the recoverability of PGE as a function of chemical composition, i.e. establish a chemical proxy for PGE recoverability;
(ii) Performing a geostatistical modelling of the geochemical dataset, i.e. interpolation through cokriging, and
(iii) Combining step (i) and (ii) to generate a spatially-resolved geometallurgical model able to predict the potential to recover PGE by flotation in terms of probabilities.
The resultant predictive, spatially-resolved geometallurgical model displays the PGE pro-cessing potential in terms of probabilities and therefore incorporates uncertainty.
Based on the work flow applied in this study, a more generic framework towards a predictive geometallurgical model can be proposed that can be applied to different commodities, is able to adapt to future data, and predicts metallurgical parameters, e.g. the recoverability of an ore as probabilities (and therefore including uncertainty). Furthermore, the model can be applied to main as well as by-product and therefore represents a holistic modelling approach. Most of the modelled parameters are derived from primary ore properties (e.g. rock or particle stream), e.g. modal mineralogy, mineral association, densities, etc., combined with a minimum of empirical test work.

In the effort to become more sustainable the mining industry currently faces a number of important challenges. One important direction of change would be to achieve a more holistic use of mineral resources, i.e., by considering the efficient extraction and beneficiation of all possible valuable constituents – rather than only focusing on the major commodity. Thus, geometallurgical models need to be adapted accordingly. Instead of only centring on the efficient extraction and beneficiation of a single (economically most relevant) commodity, future geometallurgical models should be expanded to consider all potential products.
In the present contribution, a generic framework is proposed that can be applied to a large variety of different commodities; it is able to adapt to future data, predicts metallurgical parameters, e.g. the recoverability of an ore as probabilities, and can be extended to include environmental footprint calculations. Most of the parameters are derived from primary ore properties (e.g. rock or particle streams), e.g. modal mineralogy, mineral association, densities, etc., combined with a minimum of conventional test work. The work flow is demonstrated with a case study, in which the beneficiation potential of PGE as a by-product in an existing chromite mine in the Bushveld Complex of South Africa is considered. All available data were incorporated in a geological block model and interpreted to form geometallurgical domains of sufficient size to be considered during mine planning. The resultant predictive, spatially-resolved geometallurgical model displays the PGE processing potential in terms of probabilities and therefore incorporates uncertainty. The viability of the geometallurgical model relates well to the original geological architecture, is cost- and time-effective and highly versatile to form a foundation for further use and development during exploitation.

Non-collinear antiferromagnets are revealing many unexpected phenomena and they became crucial for the field of antiferromagnetic spintronics. To visualize and prepare a well-defined domain structure is of key importance. The spatial magnetic contrast, however, remains extraordinary difficult to be observed experimentally. Here, we demonstrate a magnetic imaging technique based on a laser induced local thermal gradient combined with detection of the anomalous Nernst effect. We employ this method in one the most actively studied representative of this class of materials - Mn₃Sn. We undoubtedly proof that the observed contrast is of magnetic origin. We further show an algorithm to prepare a well defined domain pattern at room temperature based on heat assisted recording principle. Our study opens a prospect to study spintronics phenomena in non-collinear antiferromagnets with spatial resolution.

We investigate magnetization dynamics in asymmetric interlayer exchange coupled Py/Ru/Py trilayers using both vector network analyzer-based and electrically-detected ferromagnetic resonance techniques. Two different ferromagnetic resonance modes, in-phase and out-of-phase, are observed across all three regimes of the static magnetization configurations, through antiparallel alignment at low fields, the spin-flop transition at intermediate fields and the parallel alignment at high fields. The non-monotonic behavior of the modes as a function of the external field is explained in detail by analyzing the interlayer exchange and Zeeman energies, and is found to be solely governed by the interplay of their dynamical components. In addition, the linewidths of both modes were determined across the three regimes and the different behaviors of the linewidths versus external magnetic field are attributed to mutual spin pumping induced in the samples. Interestingly, the difference between the linewidths of the out-of-phase and in-phase modes decreases at the spin-flop transition and is reversed between the antiparallel and parallel aligned magnetization states.

Zur Untersuchung der ablaufenden Prozesse in großen Behältern, wie z. B. Biogasfermentern, Bioreaktoren und Belebtschlammbecken, wurde am HZDR das Konzept instrumentierter, strömungsfolgender Sensorpartikel entwickelt [1],[2]. Bisher wurden damit die Strömungsverhältnisse mit probabilistischen Auswertemethoden ausschließlich basierend auf der Messung der vertikalen Position als Funktion des hydrostatischen Drucks charakterisiert und Parameter einfacher Prozessmodelle für Anlagen im Labor- und Pilotmaßstab bestimmt.
Derzeit wird das Konzept des Sensorsystems mit dem Ziel weiterentwickelt, eine räumliche Lage- und Bewegungsverfolgung für Bioreaktoren basierend auf Inertialsensoren zu realisieren. Dies umfasst sowohl die dafür zu qualifizierenden Sensoren für Beschleunigung, Drehrate, Magnetfeld sowie Umgebungsdruck als auch die Softsensor-Algorithmen zur Bestimmung der Lage und der Bewegung. Damit sollen zukünftig Auftriebsmanöver der Sensorpartikel autonom ablaufen und die räumliche Strömungscharakterisierung erfolgen.
Im Beitrag werden drei Softsensor-Algorithmen zur Bewegungsverfolgung vorgestellt und verglichen. Diese sind ein linearisiertes Kalman-Filter (Error State Kalman Filter ESKF) und zwei nichtlineare Komplementärfilter (Direct und Passive Complementary Filter DCF, PCF) nach [3]. Diese Algorithmen wurden mit praxisrelevanten simulierten Strömungsbewegungen (siehe Abb. 1) unter Berücksichtigung von Unsicherheiten der Sensoren und realen Sensordaten analysiert. Die Simulationsergebnisse zeigen, dass durch die genaue Lagebestimmung, die Beschleunigung permanent im Koordinatensystem des Behälters nahezu driftfrei bestimmt wird (Abb. 1 und 2). Der Beitrag führt einen umfassenden Vergleich anhand simulierter und gemessener Referenztrajektorien von drei qualifizierten, kommerziellen Inertialsensoreinheiten und diskutiert die relevanten Implikationen für die Auslegung des Sensorsystems.

The gas and ice giants in our solar system can be seen as a natural laboratory for the physics of highly compressed matter at temperatures of a few thousand kelvins. In turn, our understanding of their structure and evolution depends critically on our ability to model such matter. One key aspect is the miscibility of the elements in their interiors. Here, we demonstrate the feasibility of X-ray Thomson scattering to quantify the degree of species separation in a 1:1 carbon-hydrogen mixture at a pressure of ~150GPa and a temperature of ~5,000 K. Our measurements provide absolute values of the structure factor that encodes the microscopic arrangement of the particles. From these data, we find a lower limit of 24+6-7 % of the carbon atoms forming isolated carbon clusters. In principle, this procedure can be employed for investigating the miscibility behaviour of any binary mixture at the high-pressure environment of planetary interiors, in particular, for non-crystalline samples where it is difficult to obtain conclusive results from X-ray diffraction. Moreover, this method will enable unprecedented measurements of mixing/demixing kinetics in dense plasma environments, e.g., induced by chemistry or hydrodynamic instabilities.

We apply density functional theory molecular dynamics (DFT-MD) simulations to calculate the ionization degree of plasmas in the warm dense matter regime. Standard descriptions of the ionization potential depression (IPD) have been challenged recently by experiments approaching unprecedentedly high densities indicating that improved IPD models are required to describe warm dense matter. We propose a novel ab initio method to calculate the ionization degree directly from the dynamic electrical conductivity using the Thomas-Reiche-Kuhn (TRK) sum rule. This approach is demonstrated for carbon at a temperature of 100 eV and pressures in the Gbar range. We find substantial deviations from widely applied IPD models like Stewart-Pyatt and Ecker-Kröll implying that condensed matter and quantum effects like band structure and Pauli blocking need to be included explicitly in ionization models. Our results will help to precisely model matter under conditions occurring, e.g., during inertial confined fusion implosions or inside astrophysical objects such as brown dwarfs and low-mass stars.

The TELBE Terahertz (THz) facility at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) offers narrowband high-field high-repetition rate THz radiation for driving low-energy excitations in matter in the spectral region between 0.1 THz and 1.5 THz [1]. In combination with our pulse-resolved data acquisition and the numerous available probing techniques based on table-top laser systems, we can resolve THz-driven dynamics with few 10 fs time resolution and high dynamic range of up to 120 dB [2]. This makes TELBE a unique facility for exploring low-energy THz excitations offering (resonant) access to a multitude of fundamental modes, e.g., lattice vibrations, molecular rotations, spin precession and the motion of free electrons [3]. Recently, we demonstrated THz high harmonic generation (HHG) in the model 2D material graphene [4]. Here, the ultrafast collective thermal response of free background electrons near the Dirac point [5] enables very efficient generation of harmonics in the technologically relevant THz frequency range. We further show that the underlying principle of the collective response can be generalized to other 2D and 3D Dirac materials, such as CdAs. The crucial role of doping in graphene can be exploited by, e.g. electrochemical gating, which allows tuning of the HHG efficiency by almost two orders of magnitude. The corresponding setup for phase-resolved nonlinear THz spectroscopy further enables a novel technique: Higgs spectroscopy, which offers new ways for understanding unconventional superconductivity. Using this technique, we recently discovered a new collective mode distinct from the heavily damped Higgs mode in different families of cuprates [6]. Our results establish Higgs spectroscopy as a new approach to uncover interactions directly relevant to superconductivity.
In this contribution, I will also discuss experiments on the selective THz control of magnetic properties in a number of different materials [7], which is enabled by probing techniques, such as Faraday Rotation or MOKE, using the NIR and UV output from our table-top sources.
[1] B. Green et al., Sci. Rep. 6, 22256 (2016)
[2] S. Kovalev et al., Struct. Dyn. 4, 024301 (2017)
[3] T. Kampfrath et al. Nat. Photonics 7, 680–690 (2013)
[4] H. Hafez et al., Nature 561, 507 (2018)
[5] Z. Mics et al., Nature Communications 6, 7655 (2015)
[6] H. Chu et al., arXiv preprint, arXiv:1901.06675 (2019)
[7] S. Kovalev et al., J. Phys. D: Appl. Phys. 51, 114007 (2018)

How does functionality in quantum devices emerge? The answer lies in the numerous elementary processes, the interactions and correlations of (quasi-)particles that happen on timescales of femtoseconds. Thorough understanding of these processes can eventually lead to more efficient OLEDs, faster microprocessors, and other functional materials. A complex, but highly insightful method to access the required spectral and dynamic information in solid state systems is time- and angle-resolved photoemission spectroscopy. This lecture attempts to give an overview on this powerful technique for exploring non-equilibrium properties of matter. This includes discussions of elementary scattering processes, experimental techniques, and latest results on optoelectronic systems and correlated materials.

The exploration of nonlinear optical phenomena has not only deepened the understanding of light-matter interaction, but it also enabled novel technologies that make use of the resulting synthesis of electromagnetic radiation at new frequencies. Whereas the nonlinear responses of matter in the microwave and optical regimes are well explored, research addressing the intermediate Terahertz (THz) regime is still largely in its infancy, despite its high technological relevance, e.g. for novel high-speed (opto-)electronics.
For these future applications in the THz range, graphene is a highly promising material, because of the unique optical properties originating from its prototypical Dirac-type electronic structure. Soon after its discovery, there have multiple predictions of efficient harmonic generation in the THz range [1, 2], but experimental evidence has remained incomplete. Recently, we experimentally demonstrated the highly efficient THz harmonics generation (HG) in a single layer graphene sample (up to 7th order) at ambient conditions upon excitation with a moderate THz field of only 85 kV/cm (see Fig. 1) [3]. Our observations have been successfully described by a thermodynamic model, which clearly explains the experimentally observed crucial role of the graphene doping level for THz HG [3, 4]. By using gated graphene samples and multilayer structures, we are able to predictably modify the HG efficiency and thereby corroborate the thermodynamic model.

In addition, we employed the same experimental scheme to other Dirac materials, such as topological insulators and Dirac/Weyl semimetals, showing that THz HG is a rather universal phenomenon based on the linear band dispersion in the vicinity of the Dirac point.

[1] S. Mikhailov et al., Microelectron. J. 40 (2009) 712.
[2] I. Al-Naib, Phys. Rev. B, 90 (2014) 245423
[3] H. Hafez, S. Kovalev et al., Nature, 561 (2018) 507
[4] Z. Mics et al., Nat. Commun., 6 (2015) 7655

Activations with neutrons in the keV energy range were routinely performed at the Karlsruhe Institute of Technology (KIT) in Germany in order to simulate stellar conditions for neutron-capture cross sections. A quasi-Maxwell-Boltzmann neutron spectrum of kT = 25 keV, being of interest for the astrophysical s-process, was produced by the ⁷Li(p,n) reaction utilizing a 1912 keV proton beam at the Karlsruhe Van de Graaff accelerator. Activated samples resulting in long-lived nuclear reaction products with half-lives in the order of yr - 100 Myr were analyzed by Accelerator Mass Spectrometry (AMS). Comparison of this data to cross sections from Time-of-Flight (ToF) measurements showed that the selected AMS data is systematically lower than the ToF data. To investigate this discrepancy, ⁵⁴Fe(n,gamma)⁵⁵Fe and ³⁵Cl(n,gamma)³⁶Cl reaction cross sections were newly measured at the Frankfurt Neutron Source (FRANZ) in Germany. To complement the existing data, an additional neutron activation of ⁵⁴Fe and ³⁵Cl at a proton energy of 2 MeV was performed. The results will give implications for the stellar environment at kT = 90 keV, reaching the yet not experimentally explored high-energy s-process range. AMS measurements of the activated samples are scheduled.

The Lower and Middle Group chromitites of the Bushveld Complex are the source of a very large portion of the global chrome supply. Yet, the effectiveness of chromite beneficiation circuits is highly sensitive to mineralogical and textural variations in feed composition. The use of geochemical proxies, based on data acquired routinely during the exploration and mining process may provide a cost- and time-efficient alternative to more time-consuming and expensive mineralogical analyses. Such an approach is presented in this study, which focuses on the LG-6, LG-6A, MG-1 and MG-2 chromitite seams at the Thaba mine located on the western limb of the Bushveld Complex. According to a sound statistical assessment, the chromitites of the Thaba mine area can be subdivided into three distinct domains, domains that constitute the suitable fundament for a geometallurgical model. Accordingly, a least altered (orthomagmatic) domain is distinguished from a supergene altered domain and a domain affected by widespread hydrothermal alteration. The latter domain occurs below the depth of modern weathering, but in obvious proximity to faults and around a prominent dunite pipe. The orthomagmatic domain is represented by ores least affected by post-magmatic alteration processes. This domain occupies the centre of fault blocks below the extent of modern weathering.

The Bushveld Complex in South African contains vast resources of Cr, PGE and V. Currently, the Merensky Reef, the Platreef and the UG-2 chromitite seam are the major mining targets for PGE, although chromitites of the Lower Group (LG) and Middle Group (MG) may also contain concentrations up to several ppm PGE.
In a suite of chromitite samples from the Thaba Mine in the western Bushveld Complex it was shown that Pt concentrations in weathered chromitite seams (LG-6 to MG-4) generally exceed those of Pd. However, differences are observed by comparing individual chromitite seams as total PGE concentrations of weathered chromitites from the LG-6 to MG-4 range between 760 and 1300 ppb. Elevated concentrations of Pt and Pd are also present in hanging and footwalls of chromitite seams (median 333 ppb Pt). The PPGE (Rh, Pt, Pd) contents of weathered ores are generally lower than those of the pristine ores. The IPGE (Os, Ir, Ru) are very similar in both pristine and weathered ores. Particularly, Ru concentration are in the same range as the pristine ores.
Platinum concentrations increase from LG-6 to MG-4, whereas Pd remains at near-constant levels, resulting in a strong increase of the Pt/Pd ratio from 2.2 to 15.3. Platinum, largely remains within the chromitite seams and is only locally mobilized within the chromitites and their surrounding hanging and footwalls, whereas a large proportion of the Pd is leached out. Weathering causes mobilization of Pt and Pd out of the chromitites, locally into the hanging and footwall. The general decrease (in particular of Pd) can also be observed by comparing the average Pt/Pd ratio of pristine chromitites from the Thaba Mine. The IPGE are generally less affected by weathering processes which may be explained by the fact that laurite [(Ru,Os,Ir)S2] commonly occurs as inclusions in chromite, and PGM incorporated in chromite are largely unaffected by weathering processes.

All major sources of economically important platinum-group elements (PGE) are associated with sulfides and chromite in mafic-ultramafic rocks. The Bushveld Complex in South Africa is the largest PGE deposit worldwide. Chromitites of the Lower Group (LG) and Middle Group (MG) of the Bushveld Complex hold PGE contents of a few ppm. However, these chromitites are mainly mined for chromium only and extraction of PGE as a by-product is limited. Surface weathering in the area of the Bushveld Complex is up to 50 m down from surface. Attempts to recover Pt and Pd from these weathered ores lead to recoveries of <30 %, despite that Pt and Pd concentrations are similar in pristine and weathered ores. The recovery of PGE from near-surface chromitites of the LG and MG would increase the resource efficiency of current mining operations.. Therefore, an efficient utilization of these ores requires geochemical and mineralogical characterization of the PGE within these ores and the development of novel approaches of mineral beneficiation.

The tailings of industrial mineral production are a major environmental and financial burden for mining operations. Because most historic and current beneficiation plants extract only one – or few – commodities contained in the ore, tailings dams should be regarded as anthropogenic ore deposits, i.e., potential sources of raw materials. Their recovery would have a number of associated benefits: effectively reducing the waste volume as well as the environmental burden whilst simultaneously increasing the efficiency of metal / mineral production from a non-renewable resource. In some cases, this may be achieved at minimal cost, since raw materials in tailings dams are already mined, milled and deposited at surface.
Yet, most tailings are low-grade resources; technologies applied in beneficiating tailings need to be well-selected and highly efficient. For this purpose, a sound understanding of the beneficiation characteristics of such tailings needs to be developed. With the latest advances of mineral characterization and data mining techniques, the Helmholtz Institute Freiberg for Resource Technology has been developing a framework that enables predictive geometallurgical studies of tailings materials. This presentation will illustrate three particular parts of this framework, namely (i) resource models that account for mineral processing properties, (ii) economic evaluation of by-product recovery in early stages of projects, and (iii) the use of single particles’ information for modelling mineral processing units. By combining these techniques, we are able to quantify the potential of transforming tailings into valuable resources.

A new analytical tool for mineral analysis will be introduced: Laboratory-based Spectral 3D X-ray Computed Tomography (Sp-CT). Results from a spectral imaging detector, prototype installed inside a TESCAN CoreTOM micro-CT system, will be presented and discussed in the context of mineralogical and chemical analysis of geological materials. The technique will be demonstrated to allow:

a) 3D mineral classification from the transmitted energy spectrum characteristic of a mineral phase.
b) Quick bulk chemical quantification of heavy elements with K-edge > 20 keV at high concentrations that are difficult to analyse by other methods.
c) Reducing common CT artefacts such as scattering and beam hardening, as well as improved contrast by selectively choose the most convenient energy range.
The advantages of Sp-CT will open new possibilities in geometallurgy and minerals processing research to move from the predominant 2D based image characterization towards more representative 3D characterization. These are fundamental steps to enable automated and routine 3D characterization that ultimately has the potential to provide faster and lower cost analysis to, for example, the mining industry, as well as more comprehensive rock characterization technique for Earth sciences research.

This contribution presents and validates a new method to correct for the main limitations of volume quantification using X-ray computed tomography: limited spatial resolution and lack of mineralogical classification. The volume of a phase of interest (cassiterite, SnO2) is calculated using the intensity of voxels at interphases, which are typically the regions of main uncertainty in 3D imaging. Instead of traditional segmentation methods that define boundaries between phases, our method considers interphases as regions that can be several voxels across. The method is validated using a feedback loop between 2D scanning electron microscopy-based image analysis and bulk chemical analysis where the advantages of each technique are used to correct for the limitations of another. The percent of cassiterite derived from our method are within 10% deviation from those measured by scanning electron microscopy-based image analysis and bulk chemical analysis, when the P50 of the particle size distribution is at least 5 times the voxel size of the scan, which is a better agreement than results derived from other segmentation methods. Therefore, our method reduces the uncertainty of volume quantification and lowers the limit of grain sizes for which volumes can be reliably measured using computed tomography. The reduced uncertainty and bias can contribute to broadening the application of 3D imaging to mineral engineering as complementary to well established techniques.

Fluid flows in liquid metal batteries can be generated by a number of effects. We start with a short overview of different driving mechanisms and then address questions specific to the metal pad role instabilities in three-layer systems. We focus on the role of the conductivity distribution in the cell, noting at the same time that interfacial tension should be considered as well for smaller cells. Following this discussion, numerical results on the excitation of interfacial waves in two-layer liquid metal systems with miscibility gaps bearing an interface normal electric current are presented. Confirming recent results from the literature, we find that magnetic damping plays a decisive role for strong vertical magnetic fields. In addition, boundary conditions for the electric field strongly influence critical currents and growth rates.

The aim of this work is to compare and improve optical and structural properties of GaN layers prepared using TMGa or TEGa precursors. MOVPE grown GaN buffer layers on sapphire substrates are usually grown from TMGa precursor at the temperatures above 1000 °C. These layers contain deep and shallow acceptor levels which are responsible for blue and yellow defect bands in luminescent spectra. Both defect bands are detrimental for all major nitride device applications. Especially n-doped GaN layers suffer from strong yellow defect bands. In this work, it is shown that yellow band photoluminescence intensity can be suppressed by using TEGa precursor during the growth of n–doped GaN layers. Different kinds of growth parameters, such as growth temperature or growth rate, have been studied. It is also shown that the change of carrier gas (H2 or N2) has very strong influence on the layer quality. H2 carrier gas increased intensity of yellow band in sample grown from TEGa precursor while N2 carrier gas had the same effect for sample grown from TMGa precursor. Variable energy positron annihilation spectroscopy showed creation of single VGa in H2 atmosphere and clustering of VGa to big complexes ((VGa)3(VN)n) in N2 atmosphere.

Striving to improve the critical current density Jc of superconducting YBa 2 Cu 3 o 6+x (YBCO) thin films via enhanced vortex pinning, the interplay between film growth mechanisms and the formation of nanosized defects, both natural and artificial, is systematically studied in undoped and BaZrO 3 (BZO)-doped YBCO thin films. The films were grown via pulsed laser deposition (PLD), varying the crystal grain size of the targets in addition to the dopant content. The microstructure of the PLD target has been observed to have a great impact on that of the deposited thin films, including the formation of vortex pinning centers, which has direct implications on the superconducting performance, especially on the isotropy of flux pinning properties. Based on experimentally measured angular dependencies of Jc, coupled with a molecular dynamics (MD) simulation of flux pinning in the YBCO films, we present a quantitative model of how the splay and fragmentation of BZO nanorods artifically introduced into the YBCO film matrix explain the majority of the observed critical current anisotropy. To obtain the freedom to engineer future high-temperature superconductor (HTS) applications for desired operating magnetic field and temperature ranges, it is necessary to optimize the vortex pinning landscape for an enhanced, isotropic flux pinning performance 1-6. In addition to naturally formed crystalline defects, which typically have spatial dimensions distinctly below the superconducting coherence length, defect-engineering with artificially produced pinning centers (APCs) with dimensionalities of 1D-3D have been observed to be extremely effective 7-10. However, the complex nucleation process of YBCO during PLD process, that leads to growth island size variation, and the manner in which this could affect the size and distribution of the nanoscale structural defects is chiefly neglected. Especially, a clear gap exists in the current literature regarding how ordered arrays of nanoscale defects can also influence and regulate the distribution and growth of more effective APCs and thus decrease the anisotropy by allowing vortices to be trapped in a wider angular range 11. Partly, the clear lack of information on the subject is arguably be due to the rather general assumption that during PLD process, the film growth method of our choice, the target material is largely decomposed on the atomic level, and thus its properties should not have an effect on the formation and nucleation of particles on the substrate surface. This assumption, which our studies have led us to challenge, would precariously force one to downplay the potential importance of target microstructure on the functional properties of derived films. The angular dependence of the J c has an excellent physical importance providing an approach to the problem of flux pinning and vortex dynamics anisotropy in HTSs, both from the experimental and theoretical point of view. For instance, in the angular dependent critical current plots, one can easily observe how the various types of pinning centers such as correlated linear, columnar or planar defects and, on the other hand, defects based on growth mechanisms together with YBCO's intrinsic pinning can dramatically alter the angular dependence of J c (B) 4. For understanding the origin of angular dependent flux pinning J c (θ), experimental tools like transmission electron microscopy (TEM) are often exploited to probe the structural properties and features, such as the defects naturally formed during the film growth, as well as the size, shape, orientation and distribution of the artificially produced and self-assembled pinning centers 5,12,13. However, methods like positron annihilation spectroscopy,

We present an innovative multi-sensor system, based on non-invasive optical spectroscopy for the characterization of material streams. The novel hardware and software set-ups are explained in detail and first results from RGB stereoscopy and object detection are shown.

A systematic study of the influence of interstitial hydrogen on the structure, morphology of surface, magnetic and magnetothermal properties in multicomponent (Nd_0.5Pr_0.5)₂Fe₁₄BH_x (x = 0; 2.7; 4.3) are reported. Partial substitution of Pr for Nd allows a decrease of the spin-reorientation transition temperature from 135 K for Nd₂Fe₁₄B to 73 K for (Nd_0.5Pr_0.5)₂Fe₁₄B. Hydrides (Nd_0.5Pr_0.5)₂Fe₁₄BH_x crystallize in a tetragonal crystal structure (space group P42/mnm) of the Nd₂Fe₁₄B-type. Both lattice constants and unit cell volume increase upon hydrogen absorption. It was also found that the surface of the hydrogenated sample was very severely damaged by the introduction of hydrogen. Magnetic studies of both initial compound and the hydrides were performed on bulk and powder samples in static and pulsed magnetic fields up to 14 and 58 T, respectively. Hydrogenation has a significant effect on magnetic properties of a multicomponent alloy (Nd_0.5Pr_0.5)₂Fe₁₄B: Curie temperature and saturation magnetization increase, while temperature of SRT decreases (T_SRT = 63 K for (Nd_0.5Pr_0.5)₂Fe₁₄BH_x with x = 2.7 and 4.3). The magnetocaloric effect (MCE) in the range of spin-reorientation transition also decreases significantly. We analyzed magnetic properties of (Nd_0.5Pr_0.5)₂Fe₁₄BH_x and compare them with that of Nd₂Fe₁₄BH_x. Magnetic phase diagrams are constructed.

We report on low-temperature heat-transport properties of the spin-1/2 triangular-lattice antiferromagnet Cs₂CuCl₄. Broad maxima in the thermal conductivity along the three principal axes, observed at about 5 K, are interpreted in terms of the Debye model, including the phonon umklapp scattering. For thermal transport along the b axis, we found a pronounced field-dependent anomaly, close to the transition into the three-dimensional long-range-ordered state. No such anomalies were found for the transport along the a and c directions.We argue that this anisotropic behavior is related to an additional heat-transport channel through magnetic excitations, that can best propagate along the direction of the largest exchange interaction. In addition, peculiarities of the heat transport of Cs₂CuCl₄ in magnetic fields up to the saturation field and above are discussed.

Liquid metal electrodes are one of the key components of different electrical energy storage technologies. The understanding of transport phenomena in liquid electrodes is mandatory in order to ensure efficient operation. In the present study we focus our attention on the positive electrode of the Li||Bi liquid metal battery. Starting from a real experimental setup, we numerically investigate the charge transfer in a molten salt electrolyte and the mass transport in the positive electrode. The two phenomena are tightly coupled, because the current distribution influences the concentration field in the positive electrode. The cell is studied during charging when compositional convection becomes apparent. First results of compositional convection from a non-uniform current distribution are presented, highlighting its capability to affect the flow in the positive electrode and the cell performance.

The present work initially studies the impact of a laboratory microwave (MW)’s location (before and after a jaw crusher) on grindability of a copper ore. Additionally, the role of MW’s radiation time (15–150 sec) and grinding time (13, 15 and 17 min) on the produced particle size distribution (PSD), mineral liberation degree (LD) and energy consumption are investigated. relative work index (RWI), standard Bond work index (Wi), and grindability index (GI) together with the breakage and selection functions were utilized to assess the grinding efficiency and its kinetics of the untreated and MW-pretreated (at a constant power of 0.9 kW) samples. Bond work indices were obtained 13.70, 13.04 and 10.86 kWh/t for the untreated, MW-treated uncrushed and MW-treated crushed samples, respectively. Besides, the results confirmed that the microwave pretreatment was comparatively effective at the shortest grinding time (13 min). Furthermore, locating the microwave after the crushing stage indicated substantial improvements in the sample’s grindability and its kinetics rate. The product size (P80) of the MW-treated crushed sample (13 min, 0.9 kW, 150 sec) showed enhancements of 27% and 17% in comparison with the un-microwaved and MW-treated uncrushed samples. Finally, the comparative GIs acquired in the entire spectrum of the particle range were reasonably higher if the microwave was located after the jaw crusher, particularly for the coarse fraction sizes.

The present work aims at investigating the effect of microwave local positions (i.e. before crushing (BC), after crushing (AC) and after milling (AM)) on microwave-assisted flotation of chalcopyrite and pyrite in a porphyry copper complex deposit. Individual given samples for each state were pre-treated with a variable power microwave at a power level of 90 to 900W for 15, 30, and 60s. Furthermore, froth floatation experiments were carried out using a laboratory mechanical Denver flotation cell on both microwave-treated and untreated samples. Particle surface properties were characterized by a scanning electron microscopy (SEM) and an energy-dispersive X-ray spectroscopy (EDX) analysis. The results showed that the chalcopyrite and pyrite floatabilities increased monotonically by rising the exposure time and power level for the uncrushed preconditioned samples (BC) due to the enhancement of mineral liberation degrees together with the formation of sulphide species and polysulphides on the mineral surfaces. However, flotation results of treated samples for the crushed one (AC) revealed an optimum range. Formation of intensive oxide layers on the mineral surfaces of milled samples (AM) led to a substantial reduction in their recoveries by increasing the microwave’s power level and the sample’s exposure time. The results obtained from mineral’s floatabilities in recleaner stage showed that the microwave-assisted sample at 900W for 30s at BC state favourably provided 5% higher S.E.’s than that of the untreated sample. Finally, it was concluded that the microwave pretreatment of samples induced the best floatability responses if it located before the crusher.

By means of Rutherford backscattering spectrometry, electron microscopy, and energy-dispersive X-ray spectroscopy, the distribution and interaction of In and As atoms implanted into thermally grown SiO2 films to concentrations of about 1.5 at % are studied in relation to the temperature of subsequent annealing in nitrogen vapors in the range of T = 800–1100°C. It is found that annealing at T = 800–900°C results in the segregation of As atoms at a depth corresponding to the As+-ion range and in the formation of As nanoclusters that serve as sinks for In atoms. An increase in the annealing temperature to 1100°C yields the segregation of In atoms at the surface of SiO2 with the simultaneous enhanced diffusion of As atoms. The corresponding diffusion coefficient is DAs = 3.2 × 10–14 cm2 s–1.

Hyperspectral image (HSI) classification has become a hot topic in the field of remote sensing. In general, the complex characteristics of hyperspectral data make the accurate classification of such data challenging for traditional machine learning methods. In addition, hyperspectral imaging often deals with an inherently nonlinear relation between the captured spectral information and the corresponding materials. In recent years, deep learning has been recognized as a powerful feature-extraction tool to effectively address nonlinear problems and widely used in a number of image processing tasks. Motivated by those successful applications, deep learning has also been introduced to classify HSIs and demonstrated good performance. This survey paper presents a systematic review of deep learning-based HSI classification literature and compares several strategies for this topic. Specifically, we first summarize the main challenges of HSI classification which cannot be effectively overcome by traditional machine learning methods, and also introduce the advantages of deep learning to handle these problems. Then, we build a framework that divides the corresponding works into spectral-feature networks, spatial-feature networks, and spectral-spatial-feature networks to systematically review the recent achievements in deep learning-based HSI classification. In addition, considering the fact that available training samples in the remote sensing field are usually very limited and training deep networks require a large number of samples, we include some strategies to improve classification performance, which can provide some guidelines for future studies on this topic. Finally, several representative deep learning-based classification methods are conducted on real HSIs in our experiments.

By considering the spectral signature as a sequence, recurrent neural networks (RNNs) have been successfully used to learn discriminative features from hyperspectral images (HSIs) recently. However, most of these models only input the whole spectral bands into RNNs directly, which may not fully explore the specific properties of HSIs. In this paper, we propose a cascaded RNN model using gated recurrent units to explore the redundant and complementary information of HSIs. It mainly consists of two RNN layers. The first RNN layer is used to eliminate redundant information between adjacent spectral bands, while the second RNN layer aims to learn the complementary information from nonadjacent spectral bands. To improve the discriminative ability of the learned features, we design two strategies for the proposed model. Besides, considering the rich spatial information contained in HSIs, we further extend the proposed model to its spectral-spatial counterpart by incorporating some convolutional layers. To test the effectiveness of our proposed models, we conduct experiments on two widely used HSIs. The experimental results show that our proposed models can achieve better results than the compared models.

Spectral features cannot effectively reflect the differences among the ground objects and distinguish their boundaries in hyperspectral image (HSI) classification. Multi-scale feature extraction can solve this problem and improve the accuracy of HSI classification. The Gaussian pyramid can effectively decompose HSI into multi-scale structures, and efficiently extract features of different scales by stepwise filtering and downsampling. Therefore, this paper proposed a Gaussian pyramid based multi-scale feature extraction (MSFE) classification method for HSI. First, the HSI is decomposed into several Gaussian pyramids to extract multi-scale features. Second, we construct probability maps in each layer of the Gaussian pyramid and employ edge-preserving filtering (EPF) algorithms to further optimize the details. Finally, the final classification map is acquired by a majority voting method. Compared with other spectral-spatial classification methods, the proposed method can not only extract the characteristics of different scales, but also can better preserve detailed structures and the edge regions of the image. Experiments performed on three real hyperspectral datasets show that the proposed method can achieve competitive classification accuracy.

Colourless crystalline compounds of centrosymmetric [Np(NO3)6]2− were yielded from 3 M HNO3 aq under presence of double-headed 2-pyrrolidone derivatives (L). In the obtained crystal structures, H+ was also involved as a countercation to compensate the negative charge of [Np(NO3)6]2−, where initial hydration around H+ was fully removed during crystallization despite its strongest hydration enthalpy. Instead, such an anhydrous H+ was captured by L to form a [H+···L]n hydrogen bond polymer. In [Np(NO3)6]2−, Np4+ centre is twelve-coordinated with 6 bidentate NO3−, and therefore, present in an icosahedral geometry bearing inversion centre. In such a centrosymmetric system, any f-f transitions stemming from 5f3 electronic configuration of Np4+ are electric-dipole forbidden. This is the reason why the compounds currently obtained were colourless unlike ordinary Np(IV) species with olive-green.

We report the optical and magneto-optical properties of amorphous and crystalline Co60Fe20B20 films with thicknesses in the range of 10 nm to 20 nm characterized using spectroscopy ellipsometry (SE) and magneto-optical Kerr effect (MOKE) spectroscopy. We derived the spectral dependence of the dielectric tensor from experimental data for samples prior and after annealing in vacuum. The features of the dielectric function can be directly related to the transitions between electronic states and the observed changes upon annealing can be ascribed to an increase of the crystalline ordering of CoFeB.

Uranium(VI) and Europium(III) can interact with Brassica napus suspension cell cultures. This can lead to bioassociation (immobilisation of metals due to the cell metabolism), which is discussed in more detail here. Heavy metal stress can also lead to the formation of protective metabolites by the plant cells, whose complex formation behaviour with U(VI) has been investigated.

Resonant X-ray absorption, where an X-ray photon excites a core electron into an unoccupiedvalence state, is an essential process in many standard X-ray spectroscopies. With increasingX-ray intensity, the X-ray absorption strength is expected to become nonlinear. Here, wereport the onset of such a nonlinearity in the resonant X-ray absorption of magnetic Co/Pdmultilayers near the Co L3edge. The nonlinearity is directly observed through the change ofthe absorption spectrum, which is modified in less than 40 fs within 2 eV of its threshold.This is interpreted as a redistribution of valence electrons near the Fermi level. For ourmagnetic sample this also involves mixing of majority and minority spins, due to sampledemagnetization. Ourfindings reveal that nonlinear X-ray responses of materials may alreadyoccur at relatively low intensities, where the macroscopic sample is not destroyed, providinginsight into ultrafast charge and spin dynamics.

In the present work, single-crystalline quasi-van der Waals ferromagnet Fe0.26TaS2 was successfully synthesized with Fe atoms intercalated at ordered positions between TaS2 layers. Its critical behavior was systematically studied by measuring the magnetization around ferromagnetic to paramagnetic phase transition temperature, TC∼100.7K, under different magnetic fields. The critical exponent β for the spontaneous magnetization below TC, γ for the inverse initial susceptibility above TC, and δ for the magnetic isotherm at TC were determined with modified Arrott plots, the Kouvel-Fisher method, the Widom scaling law, and critical isotherm analysis, and found to be the following values: β=0.459(6),γ=1.205(11), and δ=3.69(1). The obtained critical exponents are self-consistent and follow the scaling equation, indicating the reliability and intrinsicality of these parameters. A close analysis within the framework of renormalization group theory reveals that the spin coupling inside Fe0.26TaS2 crystal is of the three-dimensional Heisenberg ({d:n}={3:3}) type with long-range magnetic interaction and that the exchange interaction decays with distance as J(r)∼r-4.71

This work presents new calibration tools in the pyFAI suite for processing scattering experiments acquired with area detectors: a new graphical user interface for calibrating the detector position in a scattering experiment performed with a fixed, large area detector as well as a library to be used in Jupyter notebooks for calibrating the motion of a detector on a goniometer arm (or any other moving table) to perform diffraction experiments.

Rare earth elements (REE) are a group of seventeen elements consisting of scandium, yttrium as well as what are known as lanthanides. These elements are found only in a few regions worldwide in quantities worth mining. REEs are considered key components in the high-tech industry and are utilized, for example, in wind turbines, smartphones and energy-saving lamps.

Noble-metal chalcogenides, dichalcogenides and phosphochalcogenides are an emerging class of two- dimensional materials. Their properties can be broadly tuned via quantum confinement (number of layers) and defect engineering, including metal-to-semiconductor transitions, magnetic ordering, and topological surface states. They possess various polytypes, often of similar formation energy, which can be assessed by selective synthesis approaches. They excel in mechanical, optical and chemical sensing applications, and feature long-term air- and moisture stability. In this review, we summarize the recent progress in the field of noble metal chalcogenides and phosphochalcogenides and highlight the structural complexity and its impact on applications.

The energy-intensive dewatering of algae biomass, the first step of most downstream processes, remains one of the big challenges for economically relevant photoautotrophic bioprocesses. Due to its scalability and easy construction, froth flotation using the interactions between cells and bubbles shows considerable potential for this type of cost-efficient initial dewatering step. Comprehensive knowledge on both the physico-chemical conditions and the cellular surface properties are an important precondition to harvest cells by flotation. This study investigates the impact of changing the medium composition, specifically varying the pH and adding (bio-) collectors, on the zeta potential of Chlorella vulgaris SAG 211-1b. Decreasing the pH value from physiological to acidic conditions (pH 1–1.5) resulted in a strongly reduced cellular zeta potential. As validated by dispersed-air flotation, this yields a significantly enhanced cell recovery R > 95 %. The impact of the synthetic collector cetyltrimethylammonium bromide and the biopolymer chitosan on the cellular zeta potential and flotation performance was studied, resulting in a 3.3-fold decrease in the surfactant dose when chitosan was used . The basic mechanisms of cell-chitosan interaction were analysed in terms of particle size distribution and surface tension measurements, revealing interactions between flocculation and adsorption during the dispersed-air flotation of C.vulgarisSAG 211-1b.

Gold, Kupfer, Palladium und Seltene Erden sind wichtige Bestandteile von Smartphones und anderen Geräten unseres täglichen Lebens. Jedes dieser Metalle erfüllt ganz gezielt Aufgaben im Gerät und ist daraus nicht wegzudenken. Ihre Gewinnung aus den Bergbauminen dieser Erde ist häufig mit enormen Schäden für Mensch und Natur verbunden. Die Verwendung von recycelten Metallen bietet dazu eine deutlich umweltfreundlichere Alternative. Da die Metalle aber in sehr kleinen Mengen und fein verteilt im Gerät verbaut sind, ist ihr Recycling häufig nicht wirtschaftlich. Hier können neue biologische Recyclingwege Abhilfe leisten. Forscher des Helmholtz Instituts Freiberg für Ressourcentechnologie arbeiten an der Entwicklung von Metallspezifischen Antikörpern, welche gezielt ein Wertmetall nach dem anderen auch in kleinsten Konzentrationen in Form von Bioangeln aus einem Metallgemisch herausfischen können.

Präsentation der Arbeiten der Abteilung Biotechnologie des Helmholtz Institut Freiberg für Ressourcentechnologie sowie der Arbeiten der Nachwuchsforschergruppe BioKollekt

Recycling high-value products is a pivotal part of a circular economy. Current high-tech products contain a highly complex mixture of elements in low concentrations. Elements in these mixtures usually possess similar chemical and physical properties, which poses technical difficulties when considering a potential recycling process. Currently, only 22% terbium, 1% cerium and 1% lanthanum used in electronic devices like fluorescent light bulbs is recycled.1 A large proportion of these precious elements is lost. There is a need for novel techniques to be developed in order to recycle elements that are in low concentrations and in a complex matrix. Junior research group BioKollekt has begun the design and development of highly selective bio-based collector materials for a more sustainable recycling process of these elements. Biological peptide structures were identified in a highly competitive process for their selectivity and affinity for the fluorescent phosphor lanthanum phosphate doped with cerium and terbium (LAP). LAP-selective binding peptides coupled to a carrier material could be used in the future as separation tools for the selective recycling of LAP from lamp phosphors of fluorescent light bulbs. The BioKollekt approach uses LAP as a “proof of principle” to show the efficiency of biocollector materials. Figure 1 demonstrates the BioKollekt concept. The identification of highly selective biomolecules for preferred target materials (step 1) has been already achieved. In the second step, carrier materials (e.g. hydrophobic beads) will be functionalized with material binding-selective peptides. Biocollectors will interact selectively with their target material in a separation process (step 3-4). Finally, the target material and biocollector will be recycled and reused (step 5). The talk will present the BioKollekt concept and its achievements.

(0001) c-plane, (11-20) a-plane, and m-plane (10-10) ZnO bulk crystals were implanted with 400-keV Gd+ ions using fluences of 5 × 10¹⁴, 1 × 10¹⁵, 2.5 × 10¹⁵, and 5 × 10¹⁵ cm^-2. Structural changes during the implantation and subsequent annealing were characterized by Rutherford backscattering spectrometry in channeling mode (RBS-C); the angular dependence of the backscattered ions (angular scans) in c-, a-, and m-plane ZnO was realized to get insight into structural modification and dopant position in various crystallographic orientations. X-ray diffraction (XRD) with mapping in reciprocal space was also used for introduced defect identification. Defect-accumulation depth profiles exhibited differences for c-, a-, and m-plane ZnO, with the a-plane showing significantly lower accumulated disorder in the deeper layer in Zn-sublattice, accompanied by the preservation of ion channeling phenomena in a-plane ZnO. Enlargement of the main lattice parameter was evidenced, after the implantation, in all orientations. The highest was evidenced in a-plane ZnO. The local compressive deformation was seen with XRD analysis in polar (c-plane) ZnO, and the tensile deformation was observed in nonpolar ZnO (a-plane and m-plane orientations) being in agreement with RBS-C results. Raman spectroscopy showed distinct structural modification in various ZnO orientations simultaneously with identification of the disordered structure in O-sublattice. Nonpolar ZnO showed a significant increase in disorder in O-sublattice exhibited by E₂(high) disappearance and enhancement of A₁(LO) and E₁(LO) phonons connected partially to oxygen vibrational modes. The lowering of the E₂(low) phonon mode and shift to the lower wavenumbers was observed in c-plane ZnO connected to Zn-sublattice disordering. Such observations are in agreement with He ion channeling, showing channeling effect preservation with only slight Gd dopant position modification in a-plane ZnO and the more progressive diminishing of channels with subsequent Gd movement to random position with the growing ion fluence and after the annealing in c-plane and m-plane ZnO.

The periventricular region (PVR) has been shown to have an increased susceptibility to dose-dependent brain injury after proton therapy of gliomas (Eulitz 2019, Harrabi 2019). However, the PVR has not been considered in proton treatment planning so far. Here, we present an approach for incorporating the PVR as a novel organ at risk in proton treatment planning.

The PVR was defined as a 4 mm uniformly expanded margin around the ventricular system. The PVR tolerance dose was estimated as the observed near-min dose derived within late post-treatment radiation-associated contrast-enhancements (CE) on T1wCE-follow up images. All grade II/III glioma patients treated between 2014 and 2018 with (adjuvant) proton radio(chemo)therapy to 54/60 Gy(RBE), respectively, were analyzed. Retrospective PVR-sparing treatment planning was performed for 11 (4/7) consecutive glioma patients (Fig.1). Patient-wise comparison to the clinically delivered plans considered the near-max dose D2% and the volume Vx that received more than x% of prescribed dose in PVR tissue outside the target boost volume.

The median distance of the observed CE lesion centers to the cerebral ventricles was 2.5 mm. The median and near-min CE lesion dose was 57.6 Gy(RBE) and 53.0 Gy(RBE), respectively. PVR-sparing treatment planning reduced D2% and V90% by 4.3 (±1.4)% and 53.2 (±22.4)%, respectively, while maintaining clinical goals (Fig.1).

PVR-sparing in treatment planning is a promising approach to reduce late brain injury. In many cases this should be possible without compromising target coverage and field homogeneity. Further experience will improve the arrangement of PVR-sparing in the priority order of planning goals.

Introduction
The impact of adenosine A2A receptors (A2AR) in heart diseases is discussed diversely and only a few preclinical models are available. Therefore, we generated a transgenic mouse (TG) model with heart-specific overexpression of the human A2AR (hA2AR). The overexpressed hA2AR exhibited a cardioprotective, but proarrhythmic function, and A2AR agonists exerted a positive inotropic effect in vitro [1, 2]. Here, we show, that our new radioligand [18F]FLUDA can be used to assess hA2AR overexpression in murine heart by PET and to proof specific A2AR binding in human atrial samples by autoradiography.

Methods
FVB/N mice overexpressing the hA2AR under control of a α-MHC promotor were studied. Receptor autoradiography was used to determine Kd and Bmax of [18F]FLUDA in hearts of WT and TG mice (n=3). A 90 min dynamic µPET acquisition was performed to determine the biodistribution of [18F]FLUDA (7.4±3.4 MBq i.v.; Am=23-154 GBq/µmol) in wildtype (WT) and TG (n=3-5) after preinjection of vehicle or the A2AR antagonist tozadenant (2.5 mg/kg bw). The PET images were attenuation corrected by a T1-weighted MRI and list mode data were reconstructed (dynamic, 3D-OSEM algorithm). For activity quantification in tissues VOIs were determined by MRI images (Fig. 2A). In addition, the impact of 1µM FLUDA on the force of contraction (FOC) in isolated electrically driven atrial preparation was investigated.

Results
In vitro autoradiography of [18F]FLUDA in cryosections of hearts (Fig. 1) revealed a KD of 5.9 ± 1.6 nM and Bmax of 455 ± 78 fmol/mg protein in TG, whereas in WT the receptor density was too low for exact quantification. Using ZM241385 as competitor 36.3 ± 5.3 % specific binding of [18F]FLUDA was demonstrated in normal human atrial samples. PET/MR analyses revealed a 26 % (p<0.05) higher SUV ratio (SUVR) of myocard/blood (Fig.2B) in TG vs. WT mice. In TG mice the SUVR was reduced by tozadenant pre-treatment by 6 % (p<0.05) while no change in WT was observed. In electrically driven atrial preparations of TG (but not WT), FLUDA reduced the increase of FOC after CGS 2180 stimulation by about 20% (p<0.05), indicating a functional antagonism of FLUDA at the human cardiac A2AR.

Conclusion
FVB/N mice overexpressing the hA2AR are a useful model for non-invasive investigation of this receptor function with [18F]FLUDA PET. The demonstration of specific radiotracer binding in the human heart provides evidence that [18F]FLUDA might be a suitable radiotracer for assessment the A2AR status of human heart with PET. Our next steps will focus on the disease-related changes of the A2AR expression in human atrial samples with [18F]FLUDA.

Acknowledgments
The authors thank the European Regional Development Fund and Sächsische Aufbaubank (SAB) for financial support (project no. 100226753).

Keywords: [18F]FLUDA, adenosine, A2AR, heart

References
1. Boknik P, Drzewiecki K, Eskandar J, et al (2018) Phenotyping of mice with heart specific overexpression of A2A-adenosine receptors: Evidence for cardioprotective effects of A2A-adenosine receptors. Front Pharmacol 9:1–12. https://doi.org/10.3389/fphar.2018.00013
2. Boknik P, Drzewiecki K, Eskandar J, et al (2019) Evidence for arrhythmogenic effects of A2A-adenosine receptors. Front Pharmacol 10:1–12. https://doi.org/10.3389/fphar.2019.01051

Fig. 1: Representative autoradiography of 20 µm cryosections of a FVB/N mouse heart overexpressing the human adenosine A2AR (A2AR-TG), showing the total binding of [18F]FLUDA (left) and the non-homologous competition of [18F]FLUDA with the A2AR specific antagonist ZM241385 (right).


Fig. 2: A) Representative MR image (left), PET image (middle) and merged overlay (right) of one slice in the short axis orientation of TG mouse heart used for the determination of VOIs.; B) standardized uptake value ratio (SUVR) of myocard over blood under baseline (veh – vehicle) and blocking conditions (toz- tozadenant) in wildtype (WT) and myocard specific hA2AR overexpressing mice (TG); n=3-5, *p≤0.05 WT vs. TG and #p≤0.05 veh vs. toz.

Question
We have shown that A2A adenosine receptors (A2A-AR) are functionally active in human hearts. Moreover, we generated a transgenic mouse model with heart specific overexpression of the human A2A-AR (TG), which responded to agonists with a positive inotropic effect in vitro. Overexpressed A2A-AR were cardioprotective but also proarrhythmic in TG (Boknik et al. Front Pharmacol 2018, 2019). Here, we focused on the question if a cardiac A2A-AR expression could be assessed in vivo utilizing PET imaging in this model.

Methods
The impact of FLUDA (7-(3-(4-(2-(fluoro)ethoxy-1,1,2,2-d4)phenyl)propyl)-2-(furan-2-yl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine; patent: DE 10 2019 116 986.0) on the force of contraction (FOC) in isolated electrically driven (1 Hz) atrial preparation after stimulation with the A2A–AR-agonist CGS 2180 (10 µM, in the presence of the A1A-AR antagonist DPCPX 1 µM) was measured. On cryosections of mouse hearts the KD and Bmax values of [18F]FLUDA were determined by autoradiography. A small animal PET/MRI scanner (nanoscan, Mediso) was used for in vivo imaging of mice under isoflurane anaesthesia. [18F]FLUDA (7.4±3.4 MBq) was applied via the tail vein 20 s after starting the 90-minute PET measurement. A2A-AR specificity of [18F]FLUDA was determined by application of 2.5 mg/kg body weight Tozadenant 10 minutes prior to tracer administration.

Results
FLUDA was able to reduce (p<0.05) the increase of FOC after CGS 2180 stimulation by about 20 % (p<0.05) in isolated electrically driven atrial preparation in TG (but not WT), indicating a functional antagonism of FLUDA at the human cardiac A2A-AR. By in vitro autoradiography of [18F]FLUDA a KD (5.9±1.6 nM) and Bmax (455±78 fmol/mg protein) could be determined in the A2A-AR-TG hearts, whereas in the control hearts the receptor density was below the detection limit. Using PET/MR, an SUV ratio (SUVR) myocardial/cardiac ventricle of ≥1,0 was determined for the A2A-AR-TG animals at 15-30 min p.i.. Tozadenant reduced SUVR by 6 % (p<0.05).

Conclusion
These data suggest that A2A-AR can be in principle quantified in vivo in the heart.

A2AR-Liganden sind bei ischämischen Reperfusionsschäden kardioprotektiv wirksam (1). Somit ist eine Diagnose der kardialen A2AR-Verfügbarkeit für die Behandlung von Patienten mit koronaren Erkrankungen bedeutsam. Unser Ziel war es, anhand eines transgenen Mausmodells mit einer kardialen Überexpression des humanen A2AR das Potential von [18F]FLUDA als potentielles Radiopharmakon für die Darstellung des A2AR zu evaluieren.
Es wurden 4-6 Monate alte FVB/N Mäuse mit einer Kardiomyozyten-spezifischen Überexpression des humanen A2AR (A2AR TG) bzw. Kontrolltiere untersucht. Die Bestimmung der KD- und Bmax-Werte von [18F]FLUDA erfolgte autoradiographisch an Kryoschnitten von Herzexplantaten. Die In-vivo-Untersuchungen fanden unter Isoflurannarkose in einem Kleintier-PET/MRT-Scanner (nanoscan, Mediso) statt. [18F]FLUDA (7,4±3,4 MBq) wurde i.v. über die Schwanzvene 20 s nach Start der 90-minütigen PET-Messung appliziert. Die A2AR-Spezifität von [18F]FLUDA wurde durch Applikation von 2,5 mg/kg Tozadenant 10 min vor der Tracer Gabe bestimmt. Für die anatomische Korrelation und Schwächungskorrektur der PET-Aufnahmen erfolgte eine T1-gewichtete MRT. Die dynamische Rekonstruktion der Listenmodus-Daten erfolgte durch einen 3D-OSEM-Algorithmus. Die Quantifizierung der aufgenommenen Aktivität erfolgte mit PMOD.
Mittels In-vitro-Autoradiografie von [18F]FLUDA konnten in den A2AR-TG Herzen die Rezeptorparameter KD (5,9 ± 1,6 nM) und Bmax (455 ± 78 fmol/mg Protein) bestimmt werden, während in den Herzen der Kontroll-Tiere die Rezeptordichte unter der Nachweisgrenze lag. Mittels PET/MR wurde 15–30 min p.i. für die A2A-R TG Tiere ein SUV-Verhältnis (SUVR) Myokard/Herzventrikel von ≥1,0 bestimmt. Tozadenant verminderte das SUVR um 6 % (p < 0.05).
[18F]FLUDA ist ein vielversprechender Radiotracer zur Untersuchung der A2AR Verfügbarkeit im Herzen.
(1) Boknik P, et al., Front Pharmacol. 2018; 9:1–12.

Multiconfigurational wavefunction based methods are the state of the art methods to quantitatively compute excited state energies and transition moments for heavy element systems where the inclusion of electron correlation and relativistic effects is crucial. Since the advent of these methods, e.g. the complete active-space self-consistent field (CASSCF) method and the density-matrix renormalization group (DMRG) method, it is possible to accurately interpret and predict the UV-Vis spectra of these heavy element systems.
In this talk the CASSCF and DMRG methods are introduced and used to simulate the UV-Vis spectrum of the Uranium-bissalen complex. The active space is set up and varied to accurately describe the wavefunction. CASPT2 and RASSI are used to obtain quantitative results for excited state energies and transition moments.

The contribution of the f-orbitals to chemical bonding leads to the rich chemistry of the actinides. This is in contrast to the lanthanides, where it is known that this contribution is less important. Of special interest is the influence of these orbitals on the bonding character of actinides and lanthanides with organic ligands reflecting natural binding motifs.
This study compares the different bonding behavior of tetravalent actinides and lanthanides with the Schiff base salen by means of real-space bonding analysis. Our approach makes use of the quantum theory of atoms in molecules (QTAIM), non-covalent interaction (NCI) analysis and density differences complemented by natural population analysis (NPA). Especially the local properties at the bond critical points, for instance charge, density, ellipticity and others, can be used to characterize a bond’s order, strength, and covalent contribution.
First results reveal a strong interaction of the actinides, i.e. Th to Pu, with the oxygen of salen characterized by a high electron density concentration between the atoms. In contrast, the interaction between the actinides and the nitrogen of salen is much weaker. The delocalization index, density and Laplacian reveal a significant increase of covalency for Pa to Pu compared to Th and Ce being an indicator of the contribution of the f-electrons. Tetravalent Ce as a lanthanide analogue of Th is expected to show a similar bonding behavior, but, surprisingly, this is not the case for all investigated bonding properties.
This detailed analysis of the electronic properties of actinide compounds will help to improve understanding of their behavior in the environment as well as in technical processes and leads to the possibility to predict properties of unknown complexes.

The calculation of the excited states of actinide systems is a challenging task because of the delicate influence of electron correlation and relativistic effects. Density functional theory is not applicable for obtaining quantitative results, hence multiconfigurational wavefunction based methods have to be used. State of the art is a combination of spinfree CASSCF and CASPT2/NEVPT2 and a following inclusion of spin-orbit coupling.
This talk presents quantitative excited state energy calculations of simple Protactinium and Uranium systems in comparison with qualitative group-theoretical considerations.

The contribution of the f-orbitals to chemical bonding leads to the rich chemistry of the actinides. This is in contrast to the lanthanides, where it is known that this contribution is less important. Of special interest is the influence of these orbitals on the bonding character of actinides and lanthanides with organic ligands reflecting natural binding motifs.
This study compares the different bonding behavior of tetravalent actinides and lanthanides with the Schiff base salen by means of real-space bonding analysis. Our approach makes use of the quantum theory of atoms in molecules (QTAIM), non-covalent interaction (NCI) analysis and density differences complemented by natural population analysis (NPA). Especially the local properties at the bond critical points, for instance charge, density, ellipticity and others, can be used to characterize a bond’s order, strength, and covalent contribution.
First results reveal a strong interaction of the actinides, i.e. Th to Pu, with the oxygen of salen characterized by a high electron density concentration between the atoms. In contrast, the interaction between the actinides and the nitrogen of salen is much weaker. The delocalization index, density and Laplacian reveal a significant increase of covalency for Pa to Pu compared to Th and Ce being an indicator of the contribution of the f-electrons. Tetravalent Ce as a lanthanide analogue of Th is expected to show a similar bonding behavior, but, surprisingly, this is not the case for all investigated bonding properties.
This detailed analysis of the electronic properties of actinide compounds will help to improve understanding of their behavior in the environment as well as in technical processes and leads to the possibility to predict properties of unknown complexes.

Traditional exploration techniques usually rely on extensive field work supported by geophysical ground surveying. However, this approach can be limited by several factors such as field accessibility, financial cost, area size, climate, and public disapproval. We recommend the use of multiscale hyperspectral remote sensing to mitigate the disadvantages of traditional exploration techniques. The proposed workflow analyzes a possible target at different levels of spatial detail. This method is particularly beneficial in inaccessible and remote areas with little infrastructure, because it allows for a systematic, dense and generally noninvasive surveying. After a satellite regional reconnaissance, a target is characterized in more detail by plane-based hyperspectral mapping. Subsequently, Remotely Piloted Aircraft System (RPAS)-mounted hyperspectral sensors are deployed on selected regions of interest to provide a higher level of spatial detail. All hyperspectral data are corrected for radiometric and geometric distortions. End-member modeling and classification techniques are used for rapid and accurate lithological mapping. Validation is performed via field spectroscopy and portable XRF as well as laboratory geochemical and spectral analyses. The resulting spectral data products quickly provide relevant information on outcropping lithologies for the field teams. We show that the multiscale approach allows defining the promising areas that are further refined using RPAS-based hyperspectral imaging. We further argue that the addition of RPAS-based hyperspectral data can improve the detail of field mapping in mineral exploration, by bridging the resolution gap between airplane- and ground-based data. RPAS-based measurements can supplement and direct geological observation rapidly in the field and therefore allow better integration with in situ ground investigations. We demonstrate the efficiency of the proposed approach at the Lofdal Carbonatite Complex in Namibia, which has been previously subjected to rare earth elements exploration. The deposit is located in a remote environment and characterized by difficult terrain which limits ground surveys.

Active tumor targeting involves the decoration of nanomaterials (NM) with oncotropic vector biomolecules that selectively recognize certain antigens on malignant cells or in the tumor microenvironment. This strategy can facilitate intracellular uptake of NM through specific interactions such as receptor-mediated endocytosis and can lead to prolonged retention in the malignant tissues by preventing rapid efflux from the tumor. Here, the design of actively targeting, renally excretible bimodal dendritic polyglycerols (dPGs) for diagnostic cancer imaging is described. Single-domain antibodies (sdAb) specifically binding to the epidermal growth factor receptor (EGFR) are employed herein as targeting warheads owing to their small size and high affinity for their corresponding antigen. The dPGs equipped with EGFR-targeting feature are compared head-to-head with their non-targeting counterparts in terms of interaction with EGFR-overexpressing cells in vitro as well as accumulation at receptor-positive tumors in vivo. Experimental results reveal a higher specificity and preferential tumor accumulation for the α-EGFR dPGs, resulting from the introduction of active targeting capabilities on their backbone. These results highlight the potential for improving the tumor uptake properties of dPGs by strategic use of sdAb functionalization, which could ultimately prove useful to the development of ultrasmall NM with highly specific tumor accumulation.

Transmission imaging in the helium ion microscope allows to measure mass-thickness contrast and reveal crystallographic information. We recently customized a microchannel plate followed by a delay line readout structure especially for this application. This system can correlate the scanning transmission ion image to the angular distribution of the transmitted ions. An in-vacuum linear support is used to place the detector at different distances from the sample, adjusting the maximum collection angle. Post-processing allows the reconstruction of images for selected scattering angles. The first results show images with nanometer resolution, material contrast, and identification of sub-surface features in biological tissues. This work has been supported by the H2020 Project npSCOPE under grant number 720964.

We report time-resolved X-ray Absorption Near Edge Spectroscopy (XANES) measurements of warm dense MgO. We used a high power nanosecond pulse to drive a strong uniform shock wave into an MgO sample, and a picosecond pulse to generate a broadband X-ray source near the Mg K-edge. We used this setup to obtain XANES spectra across a large area of the phase diagram, with densities up to 6.8 g/cc and temperatures up to 30 000 K, conditions at which no prior investigations of electronic and ionic structure exist. Our XANES results, together with quantum molecular dynamic simulations, demonstrate that the sample metallizes due to the bandgap closure as it melts, after which it shows typical behavior for a disordered ionic liquid.

The presentation gives an overview of the NORM research at the HZDR

Inside evaporators of air-conditioning systems, uneven mass flow distribution of refrigerant leads to a loss of efficiency and finally a reduction of comfort in passenger compartments. The distribution is influenced by the flow field and two-phase distribution (flow pattern) in various elements, comprising developing and developed two-phase flow in straight and angled ducts, headers, flat tubes and the connection between these.
This talk presents on-going efforts to predict this type of flow with CFD.
In a first step, extensive experimental investigations on generic geometries are done using advanced measurement techniques. This data are then used to develop and validate numerical models capable of reproducing the relevant physics.
Important two-phase phenomena are: multiple regimes (continuous-disperse + separated flow), wall films, stripping/impingement, particle size distribution, two-phase heat transfer, boiling/condensation. In a final step, the developed modeling strategy is applied to real evaporators.
In comparing simulation results to experimental data, we find both good agreement as well as discrepancies which confirm that there is still more work on developing appropriate models to do.

The trans influence is an extensively investigated electronic concept in transition metal chemistry. It can be defined as the extent to which a bond in trans position to a ligand L is weakened.[1,2] In contrast, f-block elements exhibit an opposite effect, meaning a bond shortening and thus strengthening can be observed in the trans position to a strongly donating ligand. This is established as the inverse trans influence (ITI),[3–5] and is commonly assumed to be most prominent for actinides in high oxidation states.
A novel UIVbis(carbene) complex [UIV(L¹)₂(TMSA)Cl₃] 1 (L¹ = iPr₂Im, TMSA = (N(SiMe₃)₂)−) was synthesized by salt metathesis from UCl4 in the presence of iPrImHCl and TMSA. In the complex, the U centre is surrounded by two carbenes, three chloro- and one TMSA-ligand. The U–Cl bond in trans position to the TMSA is slightly shorter (0.01 Å) compared to the other U–Cl bonds, indicating an TMSA-induced ITI. However, this change is very small. For comparison, a structural optimization based on the SC-XRD data of 1 was carried out using tetravalent tungsten as a d-block analogue, because of its similar ionic radius to UIV. Tungsten’s transition metal behaviour should result in a trans influence. In the WIVbis(carbene) complex 2, the W–Cl bond trans to the TMSA ligand is indeed 0.05 Å longer than the other W–Cl bonds. This large change expresses the existence of a strong trans influence in 2 and hence ITI in 1.
References:
[1] A. Pidcock, R. E. Richards, L. M. Venanzi, J. Chem. Soc. Inorg. Phys. Theor. 1966, 0, 1707–1710.
[2] T. G. Appleton, H. C. Clark, L. E. Manzer, Coord. Chem. Rev. 1973, 10, 335–422.
[3] R. G. Denning, J. Phys. Chem. A 2007, 111, 4125–4143.
[4] H. S. La Pierre, K. Meyer, Inorg. Chem. 2013, 52, 529–539.
[5] M. Gregson, E. Lu, D. P. Mills, F. Tuna, E. J. L. McInnes, C. Hennig, A. C. Scheinost, J. McMaster, W. Lewis, A. J. Blake, et al., Nat. Commun. 2017, 8, 14137.

The inverse trans influence (ITI) is an effect well-known to occur in high valent U(V/VI) complexes. It appears as a shortening of the M–L bond in trans position to a strongly donating ligand. The effect can be explained by electron density donation from the strong ligand to the metal center, which fills up the electron hole formed through electron density transfer from semi-core 6p to vacant 5f orbitals.[1,2] This results in the observed contraction and strengthening of the bond trans to the donating ligand.
To compare the ITI in UIV and UV complexes, the U compounds UIV(L¹)₂(TMSA)Cl₃] 1 (L¹ = iPr₂Im, TMSA = (N(SiMe₃)₂)−) and [UV(TMSI)Cl₅, but is in the same range as the other chloro ligands. The absence of a notable ITI can be attributed to intermolecular interactions in the crystal structure of 2. Structure optimization of the molecular UV complex dianion by DFT yield a U–Cl5 bond length of 2.55 Å, shorter than any other U–Cl bond by 0.02 Å. The difference between experiment and theory results from a great number of electrostatic interactions and hydrogen bonding between the complex dianion and the carbene counterions in 2. Similar intermolecular interactions are not present in the crystal structure of 1, which is why the ITI could be observed for this compound.
The results demonstrate that the ITI affects complex structures for both, UIV and UV compounds, but additional effects, such as the intermolecular network observed in the structure of 2 can surpass its relatively small structural contribution.

References
[1] M. Gregson, E. Lu, D. P. Mills, F. Tuna, E. J. L. McInnes, C. Hennig, A. C. Scheinost, J. McMaster, W. Lewis, A. J. Blake, et al., Nat. Commun. 2017, 8, 14137.
[2] B. Kosog, H. S. La Pierre, F. W. Heinemann, S. T. Liddle, K. Meyer, J. Am. Chem. Soc. 2012, 134, 5284–5289.

The inverse trans influence (ITI) is an effect well-known to occur in high valent U(V/VI) complexes. It appears as a shortening of the M–L bond in trans position to a strongly donating ligand. The effect can be explained by electron density donation from the strong ligand to the metal center, which fills up the electron hole formed through electron density transfer from semi-core 6p to vacant 5f orbitals.[1,2] This results in the observed contraction and strengthening of the bond trans to the donating ligand.
To compare the ITI in UIV and UV complexes, the U compounds UIV(L¹)₂(TMSA)Cl₃] 1 (L¹ = iPr₂Im, TMSA = (N(SiMe₃)₂)−) and [UV(TMSI)Cl₅, but is in the same range as the other chloro ligands. The absence of a notable ITI can be attributed to intermolecular interactions in the crystal structure of 2. Structure optimization of the molecular UV complex dianion by DFT yield a U–Cl5 bond length of 2.55 Å, shorter than any other U–Cl bond by 0.02 Å. The difference between experiment and theory results from a great number of electrostatic interactions and hydrogen bonding between the complex dianion and the carbene counterions in 2. Similar intermolecular interactions are not present in the crystal structure of 1, which is why the ITI could be observed for this compound.
The results demonstrate that the ITI affects complex structures for both, UIV and UV compounds, but additional effects, such as the intermolecular network observed in the structure of 2 can surpass its relatively small structural contribution.

References
[1] M. Gregson, E. Lu, D. P. Mills, F. Tuna, E. J. L. McInnes, C. Hennig, A. C. Scheinost, J. McMaster, W. Lewis, A. J. Blake, et al., Nat. Commun. 2017, 8, 14137.
[2] B. Kosog, H. S. La Pierre, F. W. Heinemann, S. T. Liddle, K. Meyer, J. Am. Chem. Soc. 2012, 134, 5284–5289.

Introduction
Due to the beneficial inverse physical depth-dose profile, proton radiotherapy (RT) offers the potential to reduce normal tissue toxicity by depositing the maximum dose within the tumor volume while sparing the surrounding tissue. However, range uncertainties and necessary clinical safety margins in combination with varying relative biological effectiveness (RBE) may result in a critical dose in tumor-surrounding normal tissue. Dedicated preclinical studies have been proposed to assess and better understand potential adverse effects of proton RT using image-guided proton irradiation of mouse brain. Here, we present the entire workflow from pre-treatment imaging, over treatment planning, mouse brain irradiation as established at the University Proton Therapy Center Dresden as well as first results from subsequent DNA damage analysis.

Materials & Methods
An experimental setup was designed and characterized to shape proton beams with 7 mm range in water and 3 mm diameter allowing for irradiation of the mouse brain´s right hemisphere. To simulate the dose distributions in vivo, a Monte Carlo model of the proton beam was designed in the simulation toolkit TOPAS, experimentally commissioned and validated. Cone-beam computed tomography (CT) and orthogonal X-ray imaging were used to delineate the hippocampus as target and position the mice at the proton beam. Mouse brains of C3H and C57BL/6 mice were irradiated with 4 Gy or 8 Gy in a single fraction and excised at different timepoints after irradiation. The number of remaining DNA double-strand break repair proteins was visualized by staining brain sections for cell nuclei and H2AX. Imaged sections were analyzed with an automated and validated processing pipeline to provide quantitative data on spatially resolved radiation damage distributions.
Results
Animals were planned and treated for proton irradiation of the right hippocampus with a proton beam stopping in the center of the brain. The analysis of irradiated brain sections revealed well-delimited sub-volumes of pronounced DNA damage in the right brain hemisphere. The registration of the brain sections with the CT anatomy revealed that the measured DNA damage pattern were in good spatial agreement with the planned dose distributions simulated in individual mouse brains. The cellular radiation response could be correlated with dose and LET on a sub-milimeter scale.
Conclusion:
Image-guided proton irradiation of mouse brains was established with a clinically oriented workflow that facilitates (back-) translational studies. The geometric accuracy, detailed Monte Carlo dose simulations and cell-based assessment enable a biologically and spatially resolved analysis of radiation response and RBE.

The incorporation of trivalent lanthanides and actinides into zirconia (ZrO₂) was studied using PXRD and spectroscopic methods (EXAFS, TRLFS). In highly doped cubic zirconia three Eu(III) incorporation species could be found using TRLFS. A surface associated species with an excitation maximum of 578.1 nm and two bulk incorporation species with excitation maxima at 579.0 and 579.7 nm were found.

The incorporation of trivalent lanthanides and actinides into zirconia (ZrO₂) was studied using PXRD and spectroscopic methods (EXAFS, TRLFS). In highly doped cubic zirconia three Eu(III) incorporation species could be found using TRLFS. A surface associated species with an excitation maximum of 578.1 nm and two bulk incorporation species with excitation maxima at 579.0 and 579.7 nm were found.

Introduction
The integration of real-time MRI is expected to improve the targeting precision of proton therapy. We have developed a first prototype setup of an in-beam MRI scanner at a proton pencil beam scanning (PBS) beam line. The aim of this study was to investigate the effects of the dynamic magnetic fringe fields of the PBS beam steering magnets on the MR image quality during simultaneous irradiation and MR image acquisition.
Materials and methods
A 0.22 T open MR scanner was positioned in front of the horizontal PBS research beam line. 2D planar dose spot application was achieved by magnetic beam steering in horizontal and vertical direction through a pair of fast scanning magnets.
A proton pencil beam of 220 MeV was subsequently scanned along a horizontal and vertical central line in the MR imaging field. The irradiation time matched the acquisition time of a single-slice gradient echo sequence, while imaging a homogeneous transversal slice of the ACR Small Phantom. The image quality was evaluated qualitatively and compared to reference images acquired without beam scanning.
Results and conclusions
MR images acquired during vertical beam scanning showed no visual differences to reference images, whereas images acquired during horizontal beam scanning showed coherent ghosting artefacts in phase encoding direction. The artefacts exhibit a systematic behavior in which the number of ghosts is inversely proportional to the number of dose spots scanned. The phase maps of the k-space data prove that the artefacts are caused by phase offsets between adjacent lines, which result from changes in the MR resonance frequency due to the dynamic fringe fields of the beam scanning magnets in the PBS nozzle.
Now the origin of the ghosting artefacts is well understood, appropriate means for magnetic shielding or k-space data post-processing have to be implemented and studied to eliminate these artefacts.

Due to its relevance for technical applications, experimental and theoretical investigation on flashing flows through nozzles and tubes has gained great attention. Most of them have focused on area-averaged quantities such as mass flow rate and pressure drop, while little attention has been paid to the internal flow structure and interfacial exchanging processes. More recently, computational fluid dynamics is frequently utilized to explore the phase distribution in the flashing flows. Various gas-liquid mixture or two-fluid models have been proposed in the literature. However, knowledge on the non-equilibrium effects, interphase transfer as well as bubble dynamics under different flashing conditions is still insufficient, and a general and precise definition of the problem in numerical simulations remains a challenge. A broad consensus on the numerical methods for flashing flows is not available. Guidelines for selecting an appropriate model are desirable, which is, however, not an easy task due to the complex physics and lack of insights. The talk is focused on the elucidation of important interfacial processes such as interfacial area density, interfacial heat transfer, bubble nucleation, coalescence and breakup as well as available modelling approaches. Numerical simulations for various flashing scenarios, i.e. converging-diverging flow, pipe-blowdown, natural circulation loop and pressure release transient, are presented. The influence of chosen numerical methods is discussed, especially the mixture model versus two-fluid ones and mono-disperse versus poly-disperse approaches. Progresses towards developing a general framework for modelling of complex gas-liquid flows are demonstrated.

Introduction: We established a 4D logfile-based dose reconstruction for monitoring and potential intervention during intensity-modulated proton therapy (IMPT) of moving tumors. Before clinical application, we assessed the validity of reconstructed doses and the sensitivity against changes of selected input parameters by phantom experiments.
Material/Methods: A dynamic thorax phantom (CIRS, USA) with a soft-tissue target and radiochromic film insert was imaged by 4DCT and irradiated with either quasi-monoenergetic fields or 4D optimized proton plans. The surrogate signal (ANZAI, Japan) of the regular motion was recorded in synchronization with the machine logfiles. Reconstructions were performed with different dose grid resolutions (1mm/3mm), deformable image registrations (DIR; manually defined or automatically generated vector-fields) and artificial asynchronies between machine and motion logfiles.
Results: Characteristic dose patterns on radiochromic films were well reconstructed (Fig.1A). Gamma pass rates (2mm, 2%) for extracted characteristic profiles of the reconstructed and measured doses were >98% under static conditions, ranged between 99% and 86% for 5mm motion depending on applied reconstruction parameters, especially the DIR, and were about 80% for 30mm motion due to the predominant residual motion in the 4DCT (Fig.1B). Fig.1C demonstrates the robustness against potential minor asynchronies (≈5ms) between machine and motion logfiles. A workflow test during a pancreatic cancer IMPT treatment (Fig.2) revealed a data processing time of approximately 20min/fraction.
Conclusions: Due to satisfying accuracy and robustness for clinically aimed motion amplitudes (≤5mm), IMPT treatment of non-small cell lung cancer accompanied by daily 4D logfile-based dose monitoring will start in our institute within the first months of 2020.

Tri- and tetravalent actinide amidinates have been synthesized and characterized in solid state and in solution.

Recently, based on data from Direct Numerical Simulations (DNS), Ma et al. (Phys. Rev. Fluids 2, 034301, 2017) proposed a model for closing the bubble-induced turbulence (BIT) in a typical Euler-Euler two-equation model, which appears to yield improved performance for predicting $k$ and $\varepsilon$ over the previous models. The present study departures from this BIT model and purpose to use the same DNS data to investigate the behavior of the $C_\mu$ constant and standard eddy viscosity definition. It can be shown that $C_\mu$ constant computed using the DNS database has a very different behavior than that in single-phase flow. Checking closely, the deficiency originates from the description of the standard eddy viscosity that is intrinsic to this general hierarchy of Euler-Euler $k-\varepsilon$ type model, hence, cannot be overcome by a more complex correction function for $C_\mu$. Departing from this point, a modification to the definition of the eddy viscosity in bubbly flows is derived for the Euler-Euler two-equation models. The new expression is based on the bubble length-scale and its corresponding velocity scale. We focus on the intermediate region -- a region extended from the core region, where bubble-induced production and dissipation are nearly in balance, and find that the modified model can lead to significantly improved predictions for the mean liquid, when compared with DNS data.

Industrial applications feature a huge variety of different flow patterns, such as bubbly flow, slug flow or annular flow. Thereby a broad range of flow morphologies and different physical scales is involved. With the objective of reproduction of occurring phenomena with one single multi-fluid solver, we present an Euler-Euler-approach, which combines a number of different methods for treatment of the partial aspects. The implementation into OpenFOAM is always with focus on sustainable research, including a state-of-the-art IT concept. A segregated approach is used for treatment of the phase momentum equations, phase fraction equations and the pressure equation, featuring a consistent momentum interpolation scheme (Cubero et al., 2014). To fulfil the kinematic condition at resolved interfaces between different continuous phases, the latter may be coupled either by an isotropic (Strubelj and Tiselj, 2011) or by an anisotropic drag. In both cases, the immensely strong phase coupling requires an adapted numerical method. State and evolution of bubble size distribution in disperse phase context is solved with either class or moment methods.
The overall objective is to take interactions between the all different aspects, such as disperse phases, resolved interfaces and turbulence with effects on momentum and mass transfer into account.

The reactingEulerFoam framework included in OpenFOAM releases since 3.0.0 provides a highly flexible platform for the modelling of multiphase flows. Extensive selection of interfacial force models is provided along with alternate turbulence models. The thermal phase change capability [1,2] was first introduced in OpenFOAM 3.0.1 [3] and has since been extended and refined in subsequent releases.
The current OpenFOAM 7 release features include support for non-equilibrium wall boiling, n-phase thermal phase change and for bubble diameter modelling algebraic, IATE and inhomogeneous class method models are supported.The present simulations have been carried out with the OpenFOAM Foundation development release [4]. The goal is to aid those that intend to use the publicly available reactingEulerFoam by providing a summary of the models and demonstrations of a few modelling details by expanding upon tutorials recently added to the OpenFOAM Foundation development line.
DEDALE experiments [5] are used as a reference for the non-drag interfacial force modelling.
Subcooled nucleate boiling simulation results with different models combinations are compared to the DEBORA experiments [6,7]. Finally, a more complex direct contact condensation simulation of SEF-POOL test facility [8] is presented and results are compared to the experiment.

References

[1] Peltola, J., & Pättikangas, T.J.H. Development and validation of a boiling model for OpenFOAM multiphase solver. CFD4NRS-4 Conference Proceedings, Daejeon, Korea, paper 59, (2012).
[2] Peltola, J., Pättikangas, T., Bainbridge, W., Lehnigk, R., Schlegel, F., On development and validation of subcooled nucleate boiling models for OpenFOAM Foundation release. NURETH-18 Conference Proceedings, Portland, Oregon, United States (2019).
[3] OpenFOAM Foundation, “OpenFOAM 3.0.1,” http://openfoam.org/version/3.0.1/ (2015).
[4] OpenFOAM Foundation, “OpenFOAM-dev,” https://openfoam.org/version/dev/ (2014-2019).
[5] Grossetete, C., Experimental investigation and numerical simulations of void profile development in a vertical cylindrical pipe (No. EDF--96-NB-00120). Electricite de France (EDF), (1995).
[6] E. Manon, Contribution à l’anayse et à la modélisation locale des écoulements boillants sous-saturésdans les conditions des Réacteurs à Eau sous Pression, PhD thesis, Ecole Centrale Paris (2000).
[7] J. Garnier, E. Manon, G. Cubizolles, “Local measurements on flow boiling of refrigerant 12 in avertical tube”, Multiphase Science and Technology, pp. 1-111 (2001).
[8] M. Puustinen, J. Laine, A. Räsänen, E. Kotro, and K. Tielinen, “Characterizing tests in SEF-POOLfacility,” Technical Report, Lappeenranta University of Technology, Nuclear Engineering, INSTAB3/2017 (2017).

The presentation gives a detailed insight into the OpenFOAM Developments for Euler-Euler simulations at HZDR, i.p. the multi-field two-fluid model approach, LES simulations, stratified flow simulations, entrainment modelling and more. Furthermore, the successfull development strategy and co-working with the OpenFOAM Foundation is explained.

The AER Working Group D on VVER reactor safety analysis held its 28th meeting in Garching, Germany, during the period 26-27 June, 2019. The meeting was hosted by GRS Garching and was held in conjunction with the second workshop on multi-physics MPMV-2 and the first workshop on the ROSTOV-2 benchmark. Altogether 20 participants from eleven AER member organizations and seven guests attended the meeting of the working group D. The co-ordinator of the working group, Mr. S. Kliem, served as the chairperson of the meeting.

The meeting started with a general information exchange about the recent activities in the participating organizations.

The given 12 presentations and the discussions can be attributed to the following topics:

• Safety analyses methods and results
• Code development and benchmarking
• Future activities

A list of the participants and a list of the handouts distributed at the meeting are attached to the report. The corresponding PDF-files of the handouts can be obtained from the chairperson.

An extensive understanding about the microstructural evolution and thermal stability of the metastable AlCr(Si)N coating system is of considerable importance for applications facing high temperatures, but it is also a challenging task since several superimposed processes simultaneously occur at elevated temperatures. In this work, three AlCr(Si)N coatings with 0 at.%, 2.5 at.% and 5 at.% Si were investigated by in-situ high-temperature high-energy grazing incidence transmission X-ray diffraction (HT-HE-GIT-XRD) and complementary differential scanning calorimetry and thermogravimetric analysis measurements combined with conventional ex-situ X-ray diffraction. The results revealed (i) a change in the microstructure from columnar to a fine-grained nano-composite, (ii) a reduced decomposition rate of CrN to Cr₂N, also shifted to higher onset temperatures from ∼ 1000 ℃ to above 1100 ℃ and (iii) an increase of lattice defects and micro strains resulting in a significant increase of compressive residual strain with increasing Si content. While the Si-containing coatings in the as-deposited state show a lower hardness of 28 GPa compared to AlCrN with 32 GPa, vacuum annealing at 1100℃ led to an increase in hardness to 29 GPa for the coatings containing Si and a decrease in hardness to 26 GPa for AlCrN. Furthermore, the in-situ HT-HE-GIT-XRD method allowed for simultaneously accessing temperature-dependent variations of the coating microstructure (defect density, grain size), residual strain state and phase stability up to 1100℃. Finally, the results established a deeper understanding about the relationships between the elemental composition of the materials, the resulting microstructure including crystallographic phases and residual strain state, and the coating properties from room temperature up to 1100℃.

Purpose
Emerging clinical evidence for a varying relative biological effectiveness (RBE) in proton therapy poses the urgent need to consider RBE-driving physical parameters such as the linear energy transfer (LET). However, no harmonized concept exists on how to calculate the LET in clinical practice. Therefore, a multi-centric study was set up with the objective to standardize LET-calculations in Europe.

Materials and Methods
Eight European proton therapy institutions generated non-robust single-field-uniform-dose PBS treatment 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. The institutions provided their dose and corresponding LET distributions. Here, four different LET-calculation methods (including analytical codes, dedicated LET scripts, Monte Carlo engines) were analyzed.

Results
Single-field SOBP ranges (distal R80) and average dose (range: D99 to D1) in the target volume agreed within 2% (Fig.1). In contrast, the corresponding near minimum LET values (LET99), average LET and near maximum LET (LET1) in the target volume differed up to 30%, 19% and 5%, respectively. In the volume 1 cm distal to the target, absolute (relative) LET1 values differed by up to 1.63 keV/µm (17%) in voxels with average physical dose above 40 Gy. Individual institutions included different ions in their LET-calculations partially explaining the observed differences in LET-values and LET-distributions (Fig.2).

Conclusion
Despite comparable dose distributions, substantial LET-differences occurred among the participating institutions. They hamper the consistent analyses of clinical follow-up data and might lead to discrepancies in predicting variable RBE. Therefore, standardized clinical LET-calculations are recommended.

The aim of the present report was to obtain an overview of current strategies and methods for the detection of (manufactured) nanomaterials (NMs) in the environmental compartments surface water, soil, sediment, air, biota and sewage sludge. Based on this several recommendations for future needs of action in the short to long term are derived in order to establish a standardized detection of NMs in the environment that is necessary in order to check the pollution in the environment, to check whether or not potential risk management measures take the intended effect and to validate NM release models with real data.
A literature review was performed using predominantly “Web of Science” and screening for literature, such as review articles summarising the state of the art of NM detection techniques for environmental samples. More than 160 scientific publications were evaluated concerning NM detection methods. Results of the literature survey clearly show that a combination of detection techniques is necessary in order to detect and identify NMs, and to differentiate between natural NMs and manufactured NMs. The crucial step is accurate sample preparation for the selected detection method which means in most cases complete removal of the (disturbing) matrix and transfer of the NM in appropriate media for measurement. So far field studies in terms of detection of unknown amounts of unspecific engineered NMs in natural samples are rare and only existing for a few compartments, mainly surface waters.
Hence, it is concluded that the need of action is focused on the development, standardization and validation of existing methods in a combinatory approach.

Despite being a member of the zircon type silicate family, the conditions allowing the hydrothermal synthesis of HfSiO4 were not well constrained. A multiparametric study was performed in order to follow the synthesis of this phase under soft hydro-thermal conditions and thus to determine the most efficient conditions to form single phase samples. Among the experi-mental parameters investigated, concentration of reactants, pH of the reactive media, temperature and duration of the hydrothermal treatment impacted significantly the formation rate of hafnon and its crystallization state. Pure HfSiO4 was obtained in acid reactive media with an acidity ranging from CHCl = 1.5 M to pH = 1.0 and for CSi ≈ CHf ≥ 0.21 mol·L 1. The silicate phase was prepared after a 24-hours treatment at temperatures ranging from 150°C to 250°C. However, rise of tem-perature and extension of the duration of the hydrothermal treatment favored the crystallization state of the final HfSiO4 samples.

Solutal buoyancy has a large impact on the flow of the alloy phase composing the positive electrode in liquid metal batteries. During discharge solutal buoyancy creates a stabilizing stratification, during charge it creates a vigorous solutal convection. In this article we provide new physical understandings of the role of solutal buoyancy during both charge and discharge. In particular we find that during discharge the electrovortex mechanism is in general not strong enough to counter the stabilizing effect of solutal buoyancy, and therefore this mechanism cannot be used to mix the alloy as is sometimes suggested in the literature. We show that the mixing capability of a generic flow in the alloy phase can be estimated by comparing the typical flow magnitude U to two velocity scales: Up and Um. Below Up the flow cannot mix the alloy, and above Um the flow significantly opposes solutal buoyancy. Although we focus on Li||Pb-based batteries, these simple mixing criteria can be used during the discharging phase in other types of liquid batteries. We also present new, fully three-dimensional simulations of solutal convection during the charging cycle. These simulations suggest scaling laws for the magnitude of the convective flow, the time for the onset of solutal convection, and the typical inhomogeneity level in the alloy during charge. We propose physical arguments to explain these scaling laws.

A natural silicon target was investigated in a natSi(gamma,gamma' ) photon-scattering experiment using fully polarised, quasi-monochromatic gamma rays in the entrance channel. The mean photon energies used were = 9.33, 9.77, 10.17, 10.55, 10.93, and 11.37 MeV, while the relative energy spread (Full Width Half Maximum) of the incident beam amounts to dE / E ~ 3.5 - 4 %. The observed angular distribution in the ground-state decay channel allows to propose a firm spin and parity assignment for several levels of the stable even-even silicon isotopes.

The adenosine A2A receptor (A2AR) is regarded as a particularly appropriate target for non-dopaminergic treatment of Parkinson’s disease (PD). An increased A2AR availability has been found in the human striatum at early stages of PD and in patients with PD and dyskinesias. The aim of this small animal positron emission tomography/magnetic resonance (PET/MR) imaging study was to investigate whether rotenone-treated mice reflect the aspect of striatal A2AR upregulation in PD. For that purpose, we selected the known A2AR-specific radiotracer [18F]FESCH and developed a simplified two-step one-pot radiosynthesis. PET images showed a high uptake of [18F]FESCH in the mouse striatum. Concomitantly, metabolism studies with [18F]FESCH revealed the presence of a brain-penetrant radiometabolite. In rotenone-treated mice, a slightly higher striatal A2AR binding of [18F]FESCH was found. Nonetheless, the correlation between the increased A2AR levels within the proposed PD animal model remains to be further investigated.

Alterations in mechano-physiological properties of a tissue instigate cancer burdens in parallel to common genetic and epigenetic alterations. The chronological and mechanistic interrelation between the various extra- and intracellular aspects remains largely elusive. Mechano-physiologically, integrins and other cell adhesion molecules present the main mediators for transferring and distributing forces between extracellular matrix (ECM), via focal adhesomes to cytoskeleton and nucleus and vice versa of the single cell thereby affecting the pathophysiology of multicellular cancer tissues. In combina-tion with simultaneous activation of diverse downstream signaling pathways, the phenotypes of can-cer cells are created and driven characterized by deregulated transcriptional and biochemical cues that elicit the hallmarks of cancer. It, however, remains unclear how elastostatic modifications, i.e. stiffness, in the extracellular, intracellular and nuclear compartment contribute and control the re-sistance of cancer cells to therapy. In this review, we discuss how stiffness of unique tumor compo-nents dictates therapy response and what is known about the underlying molecular mechanisms.

In the geosciences it is still uncommon to include measurement uncertainties into numerical analysis such as discriminant analysis. The implementation of uncertainties is not trivial because data sets in geosciences often present a compositional nature, e.g. they are given as concentrations, proportions, percentages or any other form of information about the relative abundance of a set of components forming a whole. For these data the respective uncertainties are nearly never considering their compositional nature. The uncertainties can be incorporated in discriminant analysis either by each measured variable, by each observation or by using the individual, cell-wise uncertainties (each observation has for each variable an individual uncertainty). Most DA methods incorporating uncertainties use the uncertainties as weights for the variables or observations of the data set. In contrast, the here proposed method uses uncertainties to calculate a better estimation of the group variances and group means, which then influence the decision rules of quadratic respectively linear discriminant algorithm. This methodological framework does not only allow to incorporate cell-wise uncertainties, but also would largely be valid if the information about the co-dependency between uncertainties within each observation is reported.

Tracking in magnetic fields with the FLUKA radiation transport and reaction code

Usage of the FLAIR Geometry-Editor
(Lecture given at the 5th Advanced FLUKA Course at NEA, Paris)

The adjustment of photoluminescence emission spectrum and an enhancement in the thermal stability of red/orange-red emitting phosphors is an important issue for the whole lighting industry. Herein, we present our results on the luminescence spectroscopy of a single crystal sample of SmPO4 exhibiting a prominent orange-red emission at 597 nm, along with a charge-transfer absorption (O2− → Sm3+) around 200 nm. We study the temperature dependence of emission spectra in SmPO4 for excitations at 365 and 455 nm, to mimic experimental conditions for phosphor converted light emitting diodes, to show that the sample has a non-quenching photoluminescence emission up to at least 865 K for an excitation at 365 nm, and ∼865 K for an excitation at wavelength, 455 nm. The thermal stability of SmPO4 was found to be much higher than its structural analogue, EuPO4, which is also an orange-red emission phosphor, but possesses a thermal quenching temperature of 710 K (exc. 365 nm), and 735 K (exc. 455 nm). The extraordinary thermal stability of SmPO4 is a result of the energy transfer from deep defects to the Sm3+ ions at high temperatures. The color purity of SmPO4 (65%) was found to be slightly lower than the EuPO4 sample (70%), at room temperature. The results suggests that the rare earth orthophosphate, SmPO4, has a large potential for near-UV excited phosphor converted solid state lighting devices.

The X2 VVER-1000 benchmark provides a unique set of VVER-1000 plant data: the detailed core definition, operational history of the first four fuel cycles and various measurement results. This paper presents the second revision of the benchmark specification with significant improvements such as detailed reflector definition, corrected material compositions, clear illustrations etc. The reference solution for the hot zero power experiments conducted during the fresh core start-up was obtained with the Serpent-2 Monte Carlo code. The calculated and measured values of a critical boron concentration, temperature reactivity effect, and control rod worth are in a very good agreement while the deviations lay within the measurement uncertainties. Further extension of the benchmark definition is foreseen for a future work.

The electronic structure and dielectric properties of the diamond, body centered cubic diamond (bc8), and hexagonal diamond (lonsdaleite) phases of carbon are computed using density functional theory and many-body perturbation theory with the emphasis on the excitonic picture of the solid phases relevant in the regimes of high-pressure physics and warm dense matter. We also discuss the capabilities of reproducing the inelastic x-ray scattering spectra in comparison with the existing models in light of recent x-ray scattering experiments on carbon and carbon bearing materials in the Megabar range.

In this paper, a mechanistic analysis of the adsorption and reduction of gold(III) chloride complex ions on the activated carbon surface were described. All experiments were performed in the presence of nickel ions. Obtained results confirm that there is no influence of light and heavy cations on the adsorption process. From the Arrhenius equation, activation parameters such as activation energy (17.53±0.98 kJ/mol) and pre-exponential (28.7±8.91 min-1 ) factor were determined. SEM and XRD, as well as XPS analysis, have confirmed the presence of metallic gold on the surface of activated carbon. The concentration distribution of gold inside activated carbon after adsorption process both for continuous stirred tank reactor and continuous flow reactor was determined. New estimator for interfacial area of mass transfer was defined.

Today’s mechanical fluid separators in industry are mostly operated without any control to maintain efficient separation for varying inlet conditions. Controlling inline fluid separators, on the other hand, is challenging for two reasons: the process is very fast and measurements in the multiphase stream are difficult as conventional sensors typically fail here. With recent improvement of process tomography sensors alongside with an increase in processing power of smart computers, such sensors can now be potentially used in inline fluid separation. Within the European Innovative Training Network TOMOCON we develop concepts for tomography-controlled inline fluid separation. It comprises of electrical tomography and wire-mesh sensors, a fast and massive data processing and an appropriate control strategy to control the process via valve action or alternative actuation principles. Solutions and ideas presented in this paper base on process models derived from theoretical investigation, numerical simulations and analysis of experimental data.

An important parameter for the safety assessment of radioactive waste repositories is the prediction and modelling of aqueous complex formation reactions between actinides (An) and common dissolved inorganic or organic ligands.Alteration processes at the contact zone between the backfill material, bentonite, or the clay host rock and the cementitious materials of the geotechnical barrier will lead to high silicate concentrations in the groundwater, which may strongly influence the aqueous speciation of actinides[1]. A detailed knowledge of the An–silicate complex formation is therefore very important. In the present study, we have investigated the U(VI)-complexation in with aqueous silicates using two approaches: 1) Time-resolved laser-induced luminescence spectroscopy(TRLFS) in the acidic pH-range (pH 3.5)was used to determine the in-situU(VI) speciation in dependency of temperature(1-25°C)and silicon concentration, 2) the Schubert method was used to acquire the U(VI)-silicate complexation constant and stoichiometryin the alkaline pH-range where no literature data for U(VI)-silicates currently exists. For the TRLFS studythe uranium concentration was fixed at 5×10-6Mwith an ionic strength of 0.2 M (NaClO4),while the silicon concentration was varied between 3×10-4and1.5×10-3M. In the absence of silicate the 1:1 U-hydroxo complex was found to play a significant role in the U-speciationin the acidic pH-range. With increasing silicon concentration an increase of the luminescence intensity and a bathochromic shift of the emission spectra couldbe observed. Based on the peak deconvolution the free component spectra of U-hydroxo and U-silicate complexeswere extracted. The following slope analysis resulted in aslope close to 1 for all temperatures, confirming the formation of the UO2OSi(OH)3+complex at pH 3.5. The temperature dependent measurements enabledthe determination of the thermodynamicparameters ΔrH0=46.3kJ∙mol-1and ΔrS0=154.1J∙K-1∙mol-1. For the Schubert method, the U(VI) sorption distribution coefficient Rdon ZrO2was determined by LSC-measurements as a function of the ligand concentration and the pH in the alkaline pH range. By plotting the Rd-values as a function of the ligand concentration, information about the number of involved ligands in the U(VI)-silicate complex could be obtained. When further plotting the fitting constant (obtained from the Rd-plot) as a function of log[H+], the number of protons involved in the complexation reaction and the conditional complexation constant could be determined. With the obtained stoichiometry, two possible complexes could be proposed in the alkaline pH-range.DFT-calculations supportedthe formation of the UO2(OH)2OSi(OH)3complex.References:[1]D. Savage, Mineral. Mag., 2011, 75

An important parameter for the safety assessment of radioactive waste repositories is the prediction and modelling of aqueous complex formation reactions between actinides (An) and common dissolved inorganic or organic ligands. Alteration processes at the contact zone between the backfill material, bentonite, or the clay host rock and the cementitious materials of the geotechnical barrier will lead to high silicate concentrations in the groundwater, which may strongly influence the aqueous speciation of actinides such as uranium, which is stable in the hexavalent oxidation state under oxidizing conditions. [1]. A detailed knowledge of the U(VI) –silicate complex formation is therefore very important.
Depending on the used host rock and backfill material, the pH of the groundwater will be in the neutral to alkaline range. However, in this pH-range, reliable thermodynamic data for aqueous An(VI) - silicate complexes are scarce. In the acidic pH-range, only the 1:1 An(VI)-Si complex, i.e. An(VI)O2OSiOH3+, has been determined for U(VI), Np(VI), and Pu(VI), and the complex formation constants differ by almost two orders of magnitude (Table 1) [2].
Table 1: Complex formation constants for An(VI)-Si complexes [2].
An logK0
U(VI) -1,86
Np(VI) -2,61
Pu(VI) -3,65

In the alkaline pH-range (pH ~8), Yusov et al. [3] postulated the formation of either a ternary Pu-OH-Si complex: (PuO2(H2O)3(OH)OSi(OH)3) with the H3SiO4- ligand or a binary Pu-Si complex (PuO2(H2O)3O2Si(OH)2) with H2SiO42-. For other hexavalent actinides, no complexes in the alkaline pH-range have been reported, however, in analogy with Pu(VI), comparable complexes should also exist for U(VI) and Np(VI).
This contribution reports on a study of the U(VI) complexation with silicate in the pH range between 3.4 and 11.5. Two approaches were used: 1) Time-resolved laser-induced luminescence spectroscopy (TRLS) was applied to determine the in situ U(VI) speciation in U(VI) solutions with various silicate concentrations and various pH. 2) U(VI)-silicate complexation constants and complex stoichiometries were determined using Schubert’s method. For the TRLFS measurements, a U(VI) concentration of 5×10-6 M (pH = 3.5) or 1×10-7 M (pH = 9) was used, while the silicon concentration was varied between 3×10-4 and 1.5×10-3 M. To determine the thermodynamic parameters ΔrH0 and ΔrS0, temperature dependent measurements were performed in the range from 1°C to 25°C. The ionic strength was fixed with NaClO4 at 0.2 M. The Schubert method allows determination of complex stoichiometry and complexation constant by measuring the solid/liquid distribution ratio (Rd value) for the U(VI) sorption on a solid phase in absence and in the presence of increasing concentrations of silicate. Here, monoclinic ZrO2 was used as a solid phase. The U(VI) concentration in the experiments was 1×10-7 M and silicate concentrations were varied between 5×10-5 and 5×10-3 M, at pH values ranging from 6.0 to 11.5 at an ionic strength of 0.1 M NaCl. LSC measurements of the 233U activity were used to determine the U(VI) concentration in solution.
In the absence of aqueous silicates, the 1:1 uranium hydrolysis species UO2OH+ plays a significant role in the speciation starting from a pH of 3.5. Therefore, this species has to be taken into account in the speciation. Figure 1 shows the luminescence spectra with increasing Si-concentration at different temperatures. The obtained spectra show a bathochromic shift and an increase in the luminescence intensity with increasing silicate concentration. Based on peak deconvolution, the pure component spectra of the UO2OSi(OH)3+ and UO2OH+ complex were extracted. The species distributions were calculated by a least-square fit method. The following slope analysis resulted in a slope close to 1 for all temperatures, confirming the formation of a UO2OSi(OH)3+ complex at pH 3.5. The obtained complexation constants were corrected to standard conditions using the Davies equation. The obtained stability constant at 25°C is significantly higher than the literature values due to the consideration of the hydroxo complex and the solubility limit of the aqueous silicates [2]. A van’t Hoff plot was used to extract the reaction enthalpy and entropy, which were found to be ΔrH0 = 46.3 kJ∙mol-1 and ΔrS0 = 154.1 J∙K-1∙mol-1.

Figure 1: Emission spectra of the U-Si complexation at pH 3.5 with varying [Si] between 3×10-4 and 1.5×10-3 M, [U] = 5×10-6 M, fixed [NaClO4] = 0.2 M, in the temperature range between 1°C to 25°C.
For the Schubert method, the U(VI) sorption distribution coefficient Rd on ZrO2 was determined by LSC-measurements as a function of the ligand concentration and the pH in the alkaline pH range. By plotting the Rd-values as a function of the ligand concentration, information about the number of involved ligands in the U(VI)-silicate complex could be obtained. When further plotting the fitting constant (obtained from the Rd-plot) as a function of corrected pH, the number of protons involved in the complexation reaction and the conditional complexation constant could be determined. With the obtained stoichiometry, two possible complexes could be proposed in the alkaline pH-range, (i) UO2(OH)O2Si(OH)2- or (ii) UO2(OH)2OSi(OH)3-. DFT-calculations support the formation of the second complex with a corrected stability constant of logK0 = -16.30.

[1] D. Savage, Mineral. Mag.,2011, 75, 2401-2418.
[2] R. Guillaumont et al., Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium, 2003, NEA-TBD.
[3] A. B. Yusov, A. M. Fedoseev, Russ. J. Coord. Chem., 2003, 29, 625-634.

Background: Changes in the expression of homomeric α7 nicotinic acetylcholine receptors (α7 nAChR) in the human brain are widely assumed to be associated with neuropsychiatric and neurooncologial processes. Indeed, thoroughly performed studies have shown the ability of α7 nAChR modulators to minimise the extent of cell death as well as to promote synaptic plasticity in different diseases including depression, schizophrenia, stroke and Alzheimer´s disease. Nonetheless, up to date, the clinical meaningful findings obtained with these agents were not always supported by a complete understanding of the downstream effects initiated by α7 nAChR modulators.
Methods: To help understanding these processes an extensive work has been done by our and other groups on the development of positron emission tomography (PET) α7 nAChR agents labeled with the radioisotopes fluorine-18 (18F) and carbon-11 (11C). So far two main classes of α7 nAChR PET tracers have advanced to clinical trials: scaffolds composed of a three-side binding mode to the receptor (e.g., hydrogen bond acceptor, hydrophobic element and a rigid basic amine as the cationic centre), and the scaffolds containing fused functionalities belonging to the interferon inducer tilorone class of derivatives.
Results and Discussion: Structure-activity relationship studies on these two classes have been the subject of continuous research aiming at the development of highly affine and selective α7 nAChR PET tracers with suitable pharmacokinetic properties for an accurate receptor occupancy quantification and distribution of α7 nAChR in the brain. As a result, [18F]NS10743, [18F]NS14490, [11C]NS14992, [18F]DBT10 and its ortho isomer [18F]ASEM emerged as the most promising α7 nAChR PET tracers developed so far. Studies in piglets were done for [18F]NS10743 and [11C]NS14992. Ongoing clinical trials have been reported using [18F]ASEM. Efforts to translate [18F]DBT10 into the clinics have been initiated with its transfer onto an automated synthesis in compliance to clinical production. The results of a successful pre-clinical imaging study, including dosimetry in piglets and evaluation in monkeys suggests the suitability of [18F]DBT10 for imaging α7 nAChR. Very recently a pilot study in a large animal model of ischemic stroke in sheep revealed a high inflammation-related specific uptake of [18F]DBT10 in the stroke border 14 days after permanent middle cerebral artery occlusion.
Conclusion: Among the receptor-specific α7 nAChR PET tracers developed so far, the dibenzothiophene isomers [18F]DBT10 and [18F]ASEM are under continuous investigation due to their suitable pharmacokinetics and high target-specific signal. More proof-of-concept studies are required to support the usefulness of these tracers for sensitive and specific α7 nAChR PET imaging.

Introduction: The monoamine oxidase B (MAO B) isoenzyme is known to be involved in the oxidative deamination of biogenic amines. While the use of MAO B inhibitors is already well-established for the treatment of Parkinson’s disease, recent reports suggest its involvement in certain types of brain tumors.1 We herein aim at the synthesis and preclinical evaluation of fluorinated indanone-based derivatives targeting MAO B in the brain via positron emission tomography (PET).
Methods: A small series of fluorinated indanone derivatives was obtained via the O-alkylation or esterification starting with the commercially available 6-hydroxy-2,3-dihydro-1H-inden-1-one in two steps. Binding affinities towards the human MAO isoenzymes were estimated in vitro by radioligand displacement. HL126 was selected for radiofluorination via its corresponding boronic acid pinacol ester. In vitro autoradiography of [18F]HL126 was performed in mice brain slices. In vivo evaluation of [18F]HL126 in CD-1 mice was carried out and metabolism studies were performed in plasma and brain samples via radio-HPLC.
Results: The fluorinated indanone derivatives were synthesized in yields ranging from 65-89%. The fluorophenyl ether derivative, HL126, was further selected for radiofluorination based on its high binding affinity towards MAO B (Ki = 6.9 ± 5.33 nM). [18F]HL126 was obtained by an alcohol-enhanced copper-mediated approach via the corresponding boronic acid pinacol ester precursor with radiochemical yields of about 11 ± 3%, high radiochemical purities (≥99%) and molar activities in the range of 20 GBq/mol. In vitro autoradiography showed a specific blockade with selective MAO-A/B inhibitors. PET/MRI analyses revealed that [18F]HL126 readily enters the brain. Some radiometabolites do cross the blood-brain barrier.
Conclusion: Although metabolism studies with [18F]HL126 revealed the presence of radiometabolites in the brain, the high binding affinity towards MAO B and the pronounced selectivity in in vitro autoradiography studies encourage further derivatization of indanone-based scaffolds for targeting MAO B.
Acknowledgments
The authors thank the Deutscher Akademischer Austausch Dienst (DAAD) for financial support.
References
1. Tripathi, R. K. P. and Ayyannan, S. R. Med. Res. Rev., 39, p.1603, 2019.

This work consists of a Computational Fluid Dynamics (CFD) modeling of a reference experiment on boron dilution in the Rossendorf coolant mixing Model (ROCOM) as part of a coordinated research project of the International Atomic Energy Agency, namely, “Application of numerical codes of fluid dynamics to the design of nuclear power plants”. This coordinated project aims to address the application of CFD codes to the process of optimizing the design of nuclear power plants related to pressurized water reactors and to evaluate the performance and predictive capabilities of these codes and to contribute to their validation. In this context, a three-dimensional numerical simulation study was carried out using CFD code ANSYS CFX v14.5, to study the boron mixing phenomenon at the core inlet and the downcomer of the ROCOM test facility. The phenomenon of experimental mixing occurs by the injection of a tracer (sodium chloride) into one of the loops of the ROCOM installation mainly containing demineralized water in its primary circuit. The concentration field of the tracer is measured and simulated at the entrance of the heart and in the lowering. The SST-kω turbulence model used in this study could reasonably predict the distribution of the injected tracer in measurement locations within the test facility. The results of this numerical simulation were compared to the Benchmark data provided by the ROCOM experimental facility of the Helmholtz-Zentrum Dresden-Rossendorf Institute.