Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Ga2O3 is emerging as an excellent potential semiconductor for high power and optoelectronic devices.
However, the successful development of Ga2O3 in a wide range of applications requires a full understanding of the role and nature of its point and extended defects. In this work, high quality epitaxial Ga2O3 films were grown on sapphire substrates by metal-organic chemical vapor deposition and fully characterized in terms of structural, optical, and electrical properties. Then defects in the films were investigated by a combination of depth-resolved Doppler broadening and lifetime of positron annihilation spectroscopies and thermally stimulated emission (TSE). Positron annihilation techniques can provide information about the nature and concentration of defects in the films, while TSE reveals the energy level of defects in the bandgap. Despite very good structural properties, the films exhibit short positron diffusion length, which is an indication of high defect density and long positron lifetime, a sign for the formation of Ga vacancy related defects and large vacancy clusters. These defects act as deep and shallow traps for charge carriers as revealed from TSE, which explains the reason behind the difficulty of developing conductive Ga2O3 films on non-native substrates. Positron lifetime measurements also show nonuniform distribution of vacancy clusters throughout the film depth. Further, the work investigates the modification of defect nature and properties through thermal treatment in various environments. It demonstrates the sensitivity of Ga2O3 microstructures to the growth and thermal treatment environments and the significant effect of modifying defect structure on the bandgap and optical and electrical properties of Ga2O3

Our research aligns to conditions reported by the 'AnSichT' project, which evaluated the feasibility of a repository in German clay formations [1]. According to the developed site model 'NORD', Ca-bentonite and concrete will be used in the geo-engineered barrier as buffer and borehole sealing material as well as for stabilization of disposal tunnels. Pore waters of the North German clay deposits are characterized by high ionic strengths up to 4 M [2, 3]. The contact of such saline formation waters with concrete can result in an enhanced corrosion of concrete which will lead to formation of secondary phases and to the evolution of highly alkaline cement pore waters (10 < pH < 13). The hyperalkaline solutions, in turn, can influence the retention potential of the bentonite buffer as well as of the surrounding clay host rock towards radionuclides.
The U(VI) retention on Ca-bentonite at hyperalkaline conditions in mixed electrolyte solutions (‘diluted Gipshut solution’, I = 2.6 M) was found to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species [4]. Above a certain pH, depending on the concentration of carbonate in solution, carbonate does not play a role in the aqueous U(VI) speciation anymore due to the predominance of hydrolysis. Two U(VI) surface complexes were identified by site-selective TRLFS and XAS.
The stability of U(VI) and Cm(III) doped calcium (aluminate) silicate hydrate (C-(A-)S-H) phases, as main phases of hardened cement paste, at high ionic strengths conditions was studied applying leaching solutions which simulate the contact with North German claystone formation water [5, 6]. With regard to C-S-H stability and radionuclide release, differences were found in dependence on C/S ratio, composition of leaching solution and kind of radionuclide. The high retention capability of C-S-H gel towards U(VI) and Cm(III) remained constant in NaCl- and Na2SO4-containing solutions with increased ionic strength. In the presence of carbonate, however, U(VI) retention was coupled to the alteration stage of the C-S-H structure as well as to pH evolution of leaching solution. The Cm(III) mobilization from C-S-H gel was very low due to additional Cm(III) incorporation into secondary phases as shown by site-selective TRLFS and XRD.
The results show that both bentonite and cementitious material constitute an important retention barrier for radionuclides under hyperalkaline conditions and increased ionic strength.

We investigate here terahertz enhancement effects arising from micrometer and nanometer structured electrode features of photoconductive terahertz emitters. Nanostructured electrode based emitters utilizing the palsmonic effect are currently one of the hottest topics in the research field. We demonstrate here that even in the absence of any plasmonic resonance with the pump pulse, such structures can improve the antenna effect by enhancing the local d.c. electric field near the structure edges. Utilizing this effect in Hilbert-fractal and grating-like designs, enhancement of the THz field of up to a factor of ~ 2 is observed. We conclude that the cause of this THz emission enhancement in our emitters is different from the earlier reported plasmonic-electrode effect in a similar grating-like structure. In our structure, the proximity of photoexcited carriers to the electrodes and local bias field enhancement close to the metallization cause the enhanced efficiency. Due to the nature of this effect, the THz emission efficiency is almost independent of the pump laser polarization. Compared to the plasmonic effect, these effects work under relaxed device fabrication and operating conditions.

At the ELBE high power radiation facility, the second version of a superconducting radio frequency (SRF) photoinjector has been put into operation and is now routinely applied for user operation at the ELBE electron accelerator. SRF guns are suitable for generating continuous wave (CW) electron beam with high average currents and high beam brightness. The SRF gun at ELBE has the goal to generate short electron pulses with bunch charges of 200-300 pC at typical repetition rates of 100 kHz for the production of super radiant, coherent terahertz radiation. The SRF gun includes a 3.5-cell, 1.3 GHz niobium cavity and a superconducting solenoid. A support system with liquid nitrogen (LN2) cooling allows the operation of normal-conducting, high quantum efficiency photo cathodes. In the paper we present the design and performance of the SRF gun as well as beam measurements for the operation with Mg photocathodes and an acceleration gradient of 8 MV/m (4 MeV kinetic energy). Finally, we discuss the SRF gun application for production of coherent terahertz radiation at the ELBE facility.

Wire-mesh sensors are well-established scientific instruments for measuring the spatio-temporal phase distribution of two-phase flows based on different electrical conductivities of the phases. Presently, these instruments are also applied in industrial processes and need to cope with dynamic operating conditions increasingly. However, since the quantification of phase fractions is achieved by normalizing signals with respect to a separately recorded reference measurement, the results are sensitive to temperature differences in any application. Therefore, the present study aims at proposing a method to compensate temperature effects in the data processing procedure. Firstly, a general approach is theoretically derived from the underlying measurement principle and compensation procedures for the electrical conductivity from literature models. Additionally, a novel semi-empirical model is developed on the basis of electrochemical fundamentals. Experimental investigations are performed using a single-phase water loop with adjustable fluid temperature in order to verify the theoretical approach for wire-mesh sensor applications and to compare the different compensation models by means of real data. Finally, the preferred model is used to demonstrate the effect of temperature compensation with selected sets of experimental two-phase data from a previous study. The results are discussed in detail and show that temperature effects need to be handled carefully --- not merely in industrial applications, but particularly in laboratory experiments.

Metalliferous process wastewater not only represents a major ecotoxicological burden but can also serve as a secondary raw material source for the recovery of critical raw materials (CRM) like gallium. Smart, innovative strategies are needed for the economic recovery of industrial metals from such CRM sources. Biotechnological approaches are powerful tools to develop effective, selective and eco-friendly strategies in resource recovery. A particularly promising approach utilizes tailor-made biomolecules (such as peptides), that can be engineered to aid in the targeted extraction of individual metals. The application of phage Surface Display technology allows the directed molecular evolution of peptide ligands. This method has been used to identify the Ga-binding peptides TMHHAAIAHPPH, NYLPHQSSSPSR, SQALSTSRQDLR, HTQHIQSDDHLA and NDLQRHRLTAGP. In this study, the metal-binding properties of these peptides were further characterized. The peptides differed decisively in their interaction with gallium; in some cases, complex formation with gallium was strongly dependent on the surrounding buffer conditions. The peptide with the amino acid sequence NYLPHQSSSPSR showed the most promising gallium-binding properties. The site-selective and covalent immobilization of the gallium-binding peptide on polystyrene beads resulted in a robust and efficient material. It is suitable for the selective adsorption and desorption of gallium from industrial wastewater utilizing citric acid as environmentally friendly eluent. Biosorption studies performed with model and real water samples showed an up to ten-fold better adsorption of gallium as well as its effective separation from other contaminants like arsenic. Computer modeling suggests the probable structure of the peptide in aqueous solution and postulate a possible binding site for gallium.

We present a numerical modeling workflow based on machine learning which reproduces the total energies produced by Kohn-Sham density functional theory (DFT) at finite electronic temperature to within chemical accuracy at negligible computational cost. Based on deep neural networks, our workflow yields the local density of states (LDOS) for a given atomic configuration. From the LDOS, spatially resolved, energy-resolved, and integrated quantities can be calculated, including the DFT total free energy, which serves as the Born-Oppenheimer potential energy surface for the atoms. We demonstrate the efficacy of this approach for both solid and liquid metals and compare results between independent and unified machine-learning models for solid and liquid aluminum. Our machine-learning density functional theory framework opens up the path towards multiscale materials modeling for matter under ambient and extreme conditions at a computational scale and cost that is unattainable with current algorithms.

Fast chemical deposition of uranium(IV) under reducing conditions at pH 8-11 results in the formation of highly crystalline UO2 nanoparticles (NPs) with sizes of 2-3 nm, which is similar to the formation mechanism of PuO2 NPs. UO2 NPs are characterized by various microscopic and spectroscopic techniques including high energy transmission electron microscopy (HRTEM), high energy resolution fluorescence detection (HERFD) X-ray absorption spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. Despite U(IV) being the dominant oxidation state of the freshly prepared UO2 NPs, they readily oxidize to U4O9 with time and under the X-ray beam. This oxidation of NPs is accompanied by their growth in size to 6 nm. The high tendency of UO2 NPs towards oxidation differs from PuO2 NPs’ behaviour due to the extremely high stability of Pu(IV) and much lower stability of oxidized Pu(V/VI) as compared to U(V/VI).

Pd(II) chloride complexes were anchored using magnesium-aluminum layered double
hydroxides (LDHs) with interlayer anions 3 2 and ), which possess different exchange properties, and MgAl mixed oxide during its rehydration. It was shown that the catalysts of the same chemical composition with different size, morphology and electronic state of supported palladium particles can be synthesized by varying the localization of Pd precursor. The properties of Pd/MgAlOx catalysts were studied in aqueous-phase hydrogenation of furfural.
Anchoring of the Pd precursor in the interlayer space of LDHs is accompanied by the formation of non-isometric agglomerated palladium particles which contain less oxidized metal and show a higher activity toward hydrogenation of furfural. Magnesium-aluminum oxides in Pd/MgAlOx catalysts are rehydrated in the aqueous-phase reaction to yield the activated MgAl-LDH species as a support, which promotes the furfural conversion via hydrogenation of the furan cycle.

Multi- and hyperspectral (MS and HS) imaging are currently deployed at a wide range of spatial dimensions (“scales”), ranging from satellites observing the Earth and other planets down to lab-scale sensing for small sample spectral analysis. New techniques such as UAS-borne imaging or terrestrial scanning of vertical targets are emerging and allow to observe any target at a wide and contiguous range of scales. Deploying spectral imaging on unmanned aerial platforms or drones creates one of the most promising application fields of spectral imaging in the last decade. Lightweight, low-cost, customizable and usable by anyone and nearly anywhere, UAS close the scale gap between airborne and ground-based spectroscopy and offer individual solutions for the respective application. The following chapter will give an insight on the principles of multi- and hyperspectral imaging that are required to understand the physical nature of spectroscopic processes as well as sensor-specific and external influence factors during the acquisition of spectral data. In later sections, the state of the art on drone-borne multi-and hyperspectral sensors, common and application-specific data correction and processing workflows are given to outline remaining challenges.

In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements like boron (B), which is known as an inhibitor of grain growth obtained by pinning grain boundaries, and complex oxide compounds (Y-Ti-Zr-O) have been introduced to the 14Cr prealloyed powder by using mechanical alloying (MA) and were further consolidated by spark employing plasma sintering (SPS). Techniques such as x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to study the obtained microstructures.
Micro-tensile tests and microhardness measurements were carried out at room temperature to analyze the mechanical properties of the differently developed microstructures, which was considered to result in a better strength in the ODS steels containing the complex oxide Y-Ti-Zr-O. In addition, small punch (SP) tests were performed to evaluate the response of the material under high temperatures conditions, under which promising mechanical properties were attained by the materials containing Y-Ti-Zr-O (14Al-X-ODS and 14Al-X-ODS-B) in comparison with the other commercial steel, GETMAT. The differences in mechanical strength can be attributed to the precipitate’s density, nature, size, and to the density of dislocations in each ODS steel.

Hyperspectral (HS) imaging holds great potential for the mapping of geological targets. Innovative acquisition modes such as drone-borne or terrestrial remote sensing open up new scales and angles of observation, which allow to analyze small-scale, vertical, or difficult-to-access outcrops. A variety of available sensors operating in different spectral ranges can provide information about the abundance and spatial location of various geologic materials. However geological outcrops are inherently uneven and spectrally heterogeneous, may be covered by dust, lichen or weathering crusts, or contain spectrally indistinct objects, which is why classifications or domain mapping approaches are often used in geoscientific and mineral exploration applications as a means to discriminate mineral associations (e.g. ore or alteration zones) based on overall variations in HS data. Feature extraction (FE) algorithms are prominently used as a preparatory step to identify the first order variations within the data and, simultaneously, reduce noise and data dimensionality. The most established FE algorithms in geosciences are, by far, Principal Component Analysis (PCA) and Minimum Noise Fraction (MNF). Major progress has been conducted in the image processing community within the last decades, yielding innovative FE methods that incorporate spatial information for smoother and more accurate classification results. In this paper, we test the applicability of conventional (PCA, MNF) and innovative FE techniques (OTVCA: Orthogonal total variation component analysis and WSRRR: Wavelet-based sparse reduced-rank regression) on three case studies from geological HS mapping campaigns, including drone-borne mineral exploration, terrestrial paleoseismic outcrop scanning and thermal HS lithological mapping. This allows us to explore the performance of different FE approaches on complex geological data with sparse or partly inaccurate validation data. For all case studies, we demonstrate advantages of innovative FE algorithms in terms of classification accuracy and geological interpretability. We promote the use of advanced image processing methods for applications in geoscience and mineral exploration as a tool to support geological mapping activities.

The annual waste heat available from industry in the European Union is more than 2,700 PJ. Consequently, the utilization of the unexploited thermal energy will decisively contribute to a reduced overall power consumption and lower greenhouse gas emissions. Supercritical carbon dioxide (sCO2) power cycles offer a variety of advantages for that purpose compared to established power cycles. Such are a high conversion efficiency and a turbomachinery with high power density. The pre-cooler is one of the essential components in a sCO2 power cycle and the prediction of the flow and heat transfer characteristics is a challenging task. In the present investigation, cycle layouts were developed for two waste heat sources: a cement plant and a gas compressor station. The pre-cooler design as well as the boundary conditions of the numerical simulation were assessed by an analytical model. The most promising design was the printed circuit heat exchanger with inlet temperatures of 209 °C and 352 °C for the cement kiln and the gas turbine respectively. Subsequently, these heat exchangers were examined in more detail by the numerical code ANSYS CFX for sCO2 mass fluxes between 100 kg/(m^2 s) and 900 kg/(m^2 s). The pressure drop along the sCO2 channel was found insensitive to the channel diameter, but increased with the channel length and mass flux. However, the pressure drop of the coolant stream significantly depends on the channel diameter and thus a larger coolant channel diameter is recommended to maintain a reasonably low pressure drop. The overall heat transfer coefficient is limited by the heat transfer on the coolant side. Ultimately, pre-cooler designs were proposed for both waste heat systems, consisting of compact modular stainless steel plates with an sCO2 channel diameter of 0.5 mm, a coolant channel diameter of 0.8 mm, an sCO2 mass flux of 700 kg/(m^2 s) and a coolant mass flux of 1029 kg/(m^2 s). Based on these results more complex channels having internal fins were studied. The connection angle and the fin height was optimized, in order to improve the heat transfer performance.

The development, verification and validation of Computational Fluid Dynamics (CFD) codes in reference to nuclear power plant (NPP) safety has been a focus of many research organizations over the last decades. Therefore, a collection of Rossendorf Coolant Mixing Test Facility (ROCOM) CFD-grade experiments were made obtainable to line up a global International Atomic Energy Agency (IAEA) benchmark regarding Pressurized Thermal Shock (PTS) situations. The benchmark experiment describes the complicated flow structures in mixed convection zones of the RPV during PTS events. The experiments were utilized to validate CFD codes. Additionally a test suit with no buoyancy forces was elite to point out the influence of density variations. Compared to the sooner studies, the turbulence models of the CFD code improved a lot. The turbulence modelling approaches show a respectable agreement with the experimental data.

Studies of flotation kinetics are essential for understanding, predicting, and optimizing the selective recovery of minerals and metals through flotation. Recently, much effort has been made to use intrinsic ore properties to model flotation behavior. Particle-based characterization methods, e.g. SEM-based image analysis, has enabled much of this development. However, currently available methods for studies of flotation kinetics can not accommodate single-particle data, resulting in incomplete use of data that is readily available today. In this contribution, a method is introduced to fit kinetic flotation models to individual particles. This method, based on lasso-regularized multinomial logistic regression, allows for an in-depth understanding of particle flotation behavior as a function of all measured particle characteristics. With the proposed method, the joint influences of particle size, shape, as well as modal and surface compositions on the recovery of individual particles can be taken into unprecedented consideration. The results of the simulated particle behavior showed a very good agreement to the outcome of experimental works and follow well-described froth-flotation recovery behavior.

The uptake of the fission product technetium (Tc) by chukanovite, an Fe(II) hydroxy carbonate mineral formed as a carbon steel corrosion product in anoxic and carbonate-rich environments, was studied under anoxic, alkaline to hyperalkaline conditions representative for nuclear waste repositories in deep geological formations with cement-based inner linings. The retention potential of chukanovite towards Tc(VII) is high in the pH range 7.8 to 12.6, evidenced by high solid-water distribution coefficients, log Rd ~ 6, and independent of ionic strength (0.1 or 1 M NaCl). Using Tc K-edge X-ray absorption spectroscopy (XAS) two series of samples were investigated, Tc chukanovite sorption samples and coprecipitates, prepared with varying Tc loadings, pH values and contact times. From the resulting 37 XAS spectra, spectral endmembers and their dependence on chemical parameters were derived by self-organizing (Kohonen) maps (SOM), a neural network-based approach of machine learning. X-ray absorption near-edge structure (XANES) data confirmed the complete reduction of Tc(VII) to Tc(IV) by chukanovite under all experimental conditions. Consistent with mineralogical phases identified by X-ray diffraction (XRD), SOM analysis of the extended X-ray absorption fine-structure (EXAFS) spectra revealed the presence of three species in the sorption samples, the speciation predominately controlled by pH: Between pH 7.8 and 11.8, TcO₂-dimers form inner-sphere sorption complexes at the surface of the initial chukanovite as well as on the surface of secondary magnetite formed due to redox reaction. At pH ≥11.9, Tc(IV) is incorporated in a mixed, chukanovite-like, Fe/Tc hydroxy carbonate precipitate. The same species formed when using the coprecipitation approach. Reoxidation of sorption samples resulted in a small remobilization of Tc, demonstrating that both the original chukanovite mineral and its oxidative transformation products, magnetite and goethite, contribute to the immobilization of Tc in the long term, thus strongly attenuating its environmental transport.

Copper losses into slag within the flash furnace settler is an economically important topic for the primary copper production. Since the settler is not easily accessible to experimental studies due to harsh reaction conditions, numerical simulations are a promising alternative to obtain more insights into the settling behavior of matte. This study aims to increase the process understanding by developing a CFD flash furnace settler model of an industrial flash furnace. Thereby, the CFD model accounts for bath level changes, polydispersity and coalescence of matte. Coalescence is modeled by an own empirical model focusing on gravitational coalescence. Matte settling shows size-dependent sedimentation within the slag layer, as supported by an own sampling study. Lowering the slag viscosity by a third decreases the copper loss by approximately 37%, while slightly increasing it leads to comparable results. Finally, average copper losses of 0:98wt.% are estimated, finding good agreement with industrial data.

Purpose: To determine the effect of Cystus® tea (Naturprodukte Dr. Pandalis GmbH & Co. KG) as mouthwash compared to sage tea on oral mucositis in patients undergoing radio(chemo)therapy for head and neck cancer. Methods: In this randomized, prospective phase III study, 60 head and neck cancer patients with primary or postoperative radio(chemo)therapy were included between 04/2012 and 06/2014. They received either sage or Cystus® tea for daily mouthwash under therapy. Mucositis was scored twice a week following the Radiation Therapy Oncology Group and the European Organization for Research and Treatment Cancer (RTOG/EORTC) scoring system. Dental parameters were also recorded. Statistical evaluation of the primary endpoint was performed using t test and log rank test. Results: Data from 57 patients could be evaluated. Patient characteristics showed no significant difference between the two groups (n = 27 sage; n = 30 Cystus®). A total of 55 patients received the prescribed dose (60–66 Gy postoperative; 70–76.8 Gy primary). Mucositis grade 3 was observed in 23 patients (n = 11 sage; n = 12 Cystus®) and occurred between day 16 and 50 after start of therapy. There was no significant difference between the two groups in latency (p = 0.75) and frequency (p = 0.85) of the occurrence of mucositis grade 3. The self-assessment of the oral mucosa and the tolerability of the tea also showed no significant differences. Occurrence of dental pathologies appeared to increase over time after radiotherapy. Conclusion: Cystus® and sage tea have a similar effect on the occurrence of radiation-induced mucositis regarding latency and incidence. Cystus® tea mouthwash solution is tolerated well and can be applied in addition to intensive oral care and hygiene along with the application of fluorides. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

Recently, several putative quantum spin liquid (QSL) states were discovered in S󠆶 = 1/2 rare-earth based triangular-lattice antiferromagnets (TLAF) with the delafossite structure. In order to elucidate the conditions for a QSL to arise, we report here the discovery of a long-range magnetic order in the Ce-based TLAF KCeS₂ below T_N = 0.38 K, despite the same delafossite structure. Finally, combining various experimental and computational methods, we characterize the crystal electric field scheme, the magnetic anisotropy and the magnetic ground state of KCeS₂.

With the research on inorganic 2D semiconductors reaching its zenith, the search for new materials beyond these traditional 2D materials is at a rapid pace. In this article, we present an emerging class of 2D semiconductors, so-called metal-organic frameworks, in terms of their synthesis, intrinsic properties, and underlying charge transport mechanisms. Further, we discuss their potential as active elements in optical applications.

Die externe Strahlentherapie ist eine wesentliche Komponente bei der Behandlung von Tumoren. Üblicherweise wird dafür Photonenstrahlung verwendet. Jedoch hat sich die Protonentherapie auf Grund ihrer physikalischen Eigenschaften zu einer attraktiven Alternative entwickelt. Vor allem ihre überlegene Dosisverteilung ermöglicht im Vergleich zur herkömmlichen Strahlentherapie eine bessere Normalgewebsschonung, wodurch potentiell das Risiko von Nebenwirkungen und Toxizitäten sinkt. Wir geben hier einen einleitenden Überblick zu den physikalischen Protoneneigenschaften und den Möglichkeiten der Dosisformierung. Insbesondere werden auch spezielle Herausforderungen in der Protonentherapie und damit verbundene aktuelle Forschungsschwerpunkte vorgestellt.

Purpose: Proton therapy is a limited resource, which is not available to all patients who may benefit from it. We investigate combined proton-photon treatments, in which some fractions are delivered with protons and the remaining fractions with photons, as an approach to maximize the benefit of limited proton therapy resources at a population level.
Methods: To quantify differences in normal tissue complication probability (NTCP) between protons and photons, we consider a cohort of 45 head-and-neck cancer patients for which IMRT and IMPT plans were previously created, in combination with NTCP models for xerostomia and dysphagia considered in the Netherlands for proton patient selection. Assuming limited availability of proton slots, we develop methods to optimally assign proton fractions in combined proton-photon treatments to minimize the average NTCP on a population level. Such combined treatments are compared to patient selection strategies in which patients are assigned to single-modality proton or photon treatments.
Results: There is a benefit of combined proton-photon treatments over patient selection due to the nonlinearity of NTCP functions, i.e. the initial proton fractions are the most beneficial whereas additional proton fractions have a decreasing benefit when a flatter part of the NTCP curve is reached. This effect was small for the patient cohort and NTCP models considered, but may be larger if dose-response relationships are better known. In addition, when proton slots are limited, patient selection methods face a tradeoff between leaving slots unused and blocking slots for future patients who may have a larger benefit. Combined proton-photon treatments with flexible proton slot assignment provide a method to make optimal use of all available resources.
Conclusions: Combined proton-photon treatments allow for a better utilization of limited proton therapy resources. The benefit over patient selection schemes depends on the NTCP models and the dose differences between protons and photons.

The second law of thermodynamics, through exergy analysis, is commonly applied to quantify process inefficiencies in metallurgical reactors, however, it is not yet being used to understand physical processes and changes in particle-based systems. Correlating the state of mixing of particle texture and homogeneous liquid mixtures is of importance. This paper applies the exergy analysis and excess entropy method to two sets of experiments highlighting the differential breakage as microwave pre-treatment is applied to a gold-copper ore. Grinding kinetic properties were measured following the top-size fraction method and calculated using the population balance model. The approach combines the mixing entropy on the system level (streams) and the entropy for multicomponent particle systems, using automated mineralogy data to quantify the effects of intergrowth and improvements in grinding performance. This is a first step towards understanding mineral processing not only in terms of energy conservation (first law of thermodynamics) but also in terms of the quality of energy available at multicomponent systems (second law of thermodynamics). When applied to comminution processes, this methodology enables us to understand the change in particle composition (its degree of liberation) as well as changes in particle size, being an important measure of process efficiency and selectivity.

New measurements of the 7Be(n,α)4He and 7Be(n,p)7Li reaction cross sections from thermal to keV neutron energies have been recently performed at CERN/n_TOF. Based on the new experimental results, astrophysical reaction rates have been derived for both reactions, including a proper evaluation of their uncertainties in the thermal energy range of interest for big bang nucleosynthesis studies. The new estimate of the 7Be destruction rate, based on these new results, yields a decrease of the predicted cosmological 7Li abundance insufficient to provide a viable solution to the cosmological lithium problem.

Since the start of its operation in 2001, based on an idea of Prof. Carlo Rubbia [1], the neutron time of-flight facility of CERN, n_TOF, has become one of the most forefront neutron facilities in the world for wide-energy spectrum neutron cross section measurements. Thanks to the combination of excellent neutron energy resolution and high instantaneous neutron flux available in the two experimental areas, the second of which has been constructed in 2014, n_TOF is providing a wealth of new data on neutron-induced reactions of interest for nuclear astrophysics, advanced nuclear technologies and medical applications. The unique features of the facility will continue to be exploited in the future, to perform challenging new measurements addressing the still open issues and long-standing quests in the field of neutron physics. In this document the main characteristics of the n_TOF facility and their relevance for neutron studies in the different areas of research will be outlined, addressing the possible future contribution of n_TOF in the fields of nuclear astrophysics, nuclear technologies and medical applications. In addition, the future perspectives of the facility will be described including the upgrade of the spallation target, the setup of an imaging installation and the construction of a new irradiation area.

Although the 12C(n,p)12B and 12C(n,d)11B reactions are of interest in several fields of basic and applied Nuclear Physics the present knowledge of these two cross-sections is far from being accurate and reliable, with both evaluations and data showing sizable discrepancies. As part of the challenging n_TOF program on (n,cp) nuclear reactions study, the energy differential cross-sections of the 12C(n,p)12B and 12C(n,d)11 B reactions have been measured at CERN from the reaction thresholds up to 30 MeV neutron energy. Both measurements have been recently performed at the long flight-path (185 m) experimental area of the n_TOF facility at CERN using a pure (99.95%) rigid graphite target and two silicon telescopes. In this paper an overview of the experiment is presented together with a few preliminary results.

The design and operation of innovative nuclear systems requires a better knowledge of the capture and fission cross sections of the Pu isotopes. For the case of capture on 242Pu, a reduction of the uncertainty in the fast region down to 8-12% is required. Moreover, aiming at improving the evaluation of the fast energy range in terms of average parameters, the OECD NEA High Priority Request List (HPRL) requests high-resolution capture measurements with improved accuracy below 2 keV. The current uncertainties also affect the thermal point, where previous experiments deviate from each other by 20%. A fruitful collaboration betwen JGU Mainz and HZ Dresden-Rossendorf within the EC CHANDA project resulted in a 242Pu sample consisting of a stack of seven fission-like targets making a total of 95(4) mg of 242Pu electrodeposited on thin (11.5 μm) aluminum backings. This contribution presents the results of a set of measurements of the 242Pu(n, γ) cross section from thermal to 500 keV combining different neutron beams and techniques. The thermal point was determined at the Budapest Research Reactor by means of Neutron Activation Analysis and Prompt Gamma Analysis, and the resolved (1 eV - 4 keV) and unresolved (1 - 500 keV) resonance regions were measured using a set of four Total Energy detectors at the CERN n_TOF-EAR1.

The low-dimensional magnetic systems tend to reveal exotic spin-liquid ground states or form peculiar types of long-range order. Among systems of vivid interest are those characterized by the triangular motif in two dimensions. The realization of either ordered or disordered ground state in triangular, honeycomb, or kagome lattices is dictated by the competition of exchange interactions, also being sensitive to anisotropy and the spin value of magnetic ions.While the low-spin Heisenberg systems may arrive to a spin-liquid long-range entangled quantum state with emergent gauge structures, the high-spin Ising systems may establish the rigid noncollinear structures. Here, we present the case of chiral noncoplanar inverted umbrella-type ferrimagnet formed in cobalt nitrate Co(NO₃)₂ below T_C = 3 K with the comparable spin and orbital contributions to the total magnetic moment.

The field of two-dimensional (2D) materials has stimulated considerable interest in the scientific community. Owing to quantum confinement in one direction, intriguing properties have been reported in 2D materials that cannot be observed in their bulk form. The advent of semiconducting 2D materials with a broad range of electronic properties has provided fascinating opportunities to design and configure next-generation electronics. One such emerging class is the family of III–VI monochalcogenides, the two prominent members of which are indium selenide (InSe) and gallium selenide (GaSe). In contrast to transition metal dichalcogenides (TMDCs), their high intrinsic mobility and the availability of a direct bandgap at small thicknesses have attracted researchers to investigate the underlying physical phenomena as well as their technological applications. However, the sensitivity of InSe and GaSe to environmental influences has limited their exploitation in functional devices. The lack of methods for their scalable synthesis further hinders the realization of their devices. This review article outlines recent advancements in the synthesis and understanding of the charge transport properties of InSe and GaSe for their integration into technological applications. A detailed summary of the improvements in the device structure by optimizing extrinsic factors such as bottom substrates, metal contacts, and device fabrication schemes is provided. Furthermore, various encapsulation techniques that have been proven effective in preventing the degradation of InSe and GaSe layers under ambient conditions are thoroughly discussed. Lastly, this article presents an outlook on future research ventures with respect to ongoing developments and practical viability of these materials.

Rare Earth Elements (REEs) supply is important to ensure the energy transition, e-mobility and ultimately to achieve the sustainable development goals of the United Nations. Conventional exploration techniques usually rely on substantial geological field work including dense in-situ sampling with long delays until provision of analytical results. However, this approach is limited by land accessibility, financial status, climate and public opposition. Efficient and innovative methods are required to mitigate these limitations. The use of lightweight Unmanned Aerial Vehicles (UAVs) provides a unique opportunity to conduct rapid and non-invasive exploration even in socially sensitive areas and in relatively inaccessible locations. We employ drones with hyperspectral sensors to detect REEs at the Earth’s surface and thus contribute to a rapidly evolving field at the cutting edge of exploration technologies. We showcase for the first time the direct mapping of REEs with lightweight hyperspectral UAV platforms. Our solution has the advantage of quick turn-around times (<1d), low detection limits (<200ppm for Nd) and is ideally suited to support exploration campaigns. This procedure was successfully tested and validated in two areas: Marinkas Quellen, Namibia, and Siilinjärvi, Finland. This strategy should invigorate the use of drones in exploration and for the monitoring of mining activities.

Froth flotation is an efficient and well-established separation technique for particles with sizes ranging from 10 µm to 200 µm, but when it comes to the separation of ultrafine particles (< 10 µm) there are still some challenges. This research is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart” and aims at developing a method for the separation of ultrafine particles based on multiple particle properties, such as wettability, morphology (shape or roughness) and size. In this study, the focus lies on the investigation of the effect of particle size on the flotation outcome.
A system consisting of ultrafine size fractions of glass particles as the valuable material and magnetite as the gangue material is used for testing. Wettability analysis is carried out using inverse gas chromatography, whereas size and shape properties are obtained via a combination of laser diffraction and microscopic analysis. In order to investigate the effect of particle size, the magnetite is selectively flocculated using macromolecules as flocculants. A novel flotation apparatus, designed for the flotation of ultrafine particles by combining advantages from column flotation and machine-type froth flotation, is used for all flotation tests.

Mineralogische und geochemische Untersuchungen an Proben des Leisniger Porphyrs sowie von Gangporphyren, Pechsteinen und Lithophysen (Hochtemperatur-Kristallisationsdomänen) im entsprechenden Verbreitungsgebiet wurden durchgeführt, um eine mineralogisch-petrographische Charakteristik dieser vulkanischen Bildungen und deren Zuordnung zu möglichen vulkanischen Edukten zu erarbeiten. Phasenanalytische Untersuchungen (Röntgendiffraktometrie, Mikroskopie, Kathodolumineszenz - KL) erbrachten eine monotone Mineralzusammensetzung, die von Quarz, den beiden Kalifeldspat-Phasen Sanidin und Orthoklas sowie Biotit dominiert ist. Anhand der geochemischen Charakteristika (Röntgenfluoreszenzanalyse - RFA) lassen sich die untersuchten Vulkanite überwiegend als Rhyolithe einstufen. Das Vorkommen von hypidiomorphen Quarzphänokristen, z.T. mit Einbuchtungen, gut erhaltenen Kalifeldspäten, sowie das Fehlen von Glas-Shards und Fiamme (Bimsfetzen) deuten darauf hin, dass es sich bei den vulkanischen Ablagerungen im Untersuchungsgebiet um keine Pyroklastite (Ignimbrite) handelt. Neuere Untersuchungen (Rehda 2018) gehen davon aus, dass es sich bei den Gesteinen nicht um klassische Fließlaven handelt, sondern um einen Lakkolith, der sich unter den Rochlitz-Ignimbrit eingeschoben hat. Damit müsste auch die bisherige stratigraphische Einordnung des Leisniger Porphyrs in die KohrenFormation korrigiert werden und eine Einordnung in die frühe Oschatz-Formation erfolgen. Die deutlichen Übereinstimmungen aller Gesteinstypen hinsichtlich mineralogischer Zusammensetzung, chemischer Charakteristik, Ausbildung der Phänokristen sowie deren KL-Eigenschaften deuten auf die Herkunft aus einem gemeinsamen Magmenreservoir hin. Auftretende Unterschiede sind im Wesentlichen auf sekundäre Alterationen zurückzuführen. Allerdings zeigen Geländebefunde und vertikal ausgerichtete Gefüge in Pechsteinen und Gangporphyren, dass diese vulkanischen Bildungen den eigentlichen Leisniger Porphyr wahrscheinlich zu einem späteren Zeitpunkt in Form vertikaler Gangstrukturen durchschlagen haben. Aufgrund der mineralogischen und geochemischen Ähnlichkeiten der Kristallisationsdomänen der Lithophysen und aller Gesteinstypen im Verbreitungsbereich des Leisniger Porphyrs kann bisher keine eindeutige Zuordnung
der Lithophysen- und Achatbildungen zu einer speziellen Gesteinsgruppe erfolgen. Aus Geländebefunden ist eine Häufung in Kreuzungsbereichen von Gangporphyren und Pechsteinen mit dem eigentlichen Leisniger Porphyr zu beobachten, was allerdings im Anstehenden oder in Bohrproben nicht direkt nachgewiesen werden
konnte. Die Bildung der Lithophysen im Bereich einer glasigen Fazies konnte ebenfalls bisher nicht bestätigt werden, da keine randlichen Anhaftungen von Pechsteinrelikten an den Lithophysen (wie im Fall des Kemmlitzer Porphyrs) beobachtet wurden. Auf Grund spezifischer textureller und mineralogischer Unterschiede kann allerdings eine Zuordnung der Lithophysen zum Seifersdorfer Porphyr im Liegenden bzw. zum Rochlitz-Ignimbrit im Hangenden ausgeschlossen werden.

Mineralogical and geochemical investigations were carried out on samples of the Leisnig porphyry including certain vein-like porphyries, pitchstones and lithophysae (HTCD - high temperature crystallization domains) in the distribution area to get information about mineralogical and petrographical characteristics of the volcanic rocks and their origin. Analytical results of X-ray diffraction, microscopy and cathodoluminescence (CL) revealed a monotonous mineral composition dominated by quartz, orthoclase/sanidine and biotite. The volcanic rocks can be classified as rhyolite according to geochemical characteristics (X-ray fluorescence – XRF). Hypidiomorphic quartz phenocrysts, partially with embayments, well preserved K-feldspar, and the absence of glass shards and fiamme disclose a pyroclastic formation (ignimbrite) of the rocks of the Leisnig porphyry in contrast to the Rochlitz ignimbrite in the same area. Recent results of Rehda (2018) indicate that the volcanic rocks of the Leisnig porphyry were not formed by flowing lava, but represent a laccolith that emplaced below the volcanic rocks of the Rochlitz ignimbrite. This consideration would result in a stratigraphic position of the Leisnig porphyry in the early Oschatz Formation instead of the previously assumed position in the Kohren Formation. The common mineralogical and chemical composition of all rock types, as well as similar characteristics of phenocrysts including their CL properties, indicate an origin from the same magma chamber or at least a melt with similar composition. Detected differences can mainly be related to secondary alteration processes. Field observations and vertically oriented textures in pitchstones and vein porphyries show that these volcanic rocks subsequently penetrated the Leisnig porphyry as vertical vein structures. Up to now, no unambiguous assignment of the lithopysae and associated agates can be done to one of the rock types in the distribution area of the Leisnig porphyry because of their similarities in mineralogy and geochemistry with the crystallization domains of the lithophysae. Based on field observations, a preferred occurrence of lithophysae in cross areas of vein porphyries and pitchstones with the Leisnig porphyry is assumed. However, this assumption could not be proven directly in outcrops or drilling samples. Although the formation of lithophysae in a glassy facies is most likely (as it was proven for the Kemmlitz porphyry), this assumption could not be confirmed due to the lack of adherent pitchstone relics on the lithophysae. However, mineralogical and textural differences to the underlying Seifersdorf porphyry and the overlying Rochlitz ignimbrite disclose an assignment of the lithophysae in the area of the Leisnig porphyry to these volcanic rocks.

Hematite (α-Fe₂O₃) is an Earth-abundant indirect n-type semiconductor displaying a band gap of about 2.2 eV, useful for collecting a large fraction of visible photons, with frontier energy levels suitably aligned for carrying out the photoelectrochemical water oxidation reaction under basic conditions. The modification of hematite mesoporous thin film photoanodes with Ti(IV), as well as their functionalization with an oxygen evolving catalyst, leads to a six-fold increase in photocurrent density with respect to the unmodified electrode. In order to provide a detailed understanding of this behavior, we report a study of Ti-containing phases within the mesoporous film structure. Using X-ray absorption fine structure and high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy, we find that Ti(IV) ions are incorporated within ilmenite (FeTiO₃) near-surface layers, thus modifying the semiconductor-electrolyte interface. To the best of our knowledge, this is the first time that a FeTiO₃/α -Fe₂O₃ composite is used in a photoelectrochemical set-up for water oxidation. In fact, previous studies of Ti(IV)-modified hematite photoanodes reported the formation of pseudobrookite (Fe₂TiO₅) at the surface. By means of transient absorption spectroscopy, transient photocurrent experiments, and electrochemical impedance spectroscopy, we show that the formation of the Fe₂O₃/FeTiO₃ interface passivates deep traps at the surface and induce a large density of donor levels, resulting in a strong depletion field that separates electron and holes, favoring hole injection in the electrolyte. Our results provide the identification of a phase coexistence with enhanced photoelectrochemical performance, allowing for the rational design of new photoanodes with improved kinetics.

The transport properties of novel device architectures depend strongly on the morphology and the quality of the interface between contact and channel materials. In silicon nanowires with nickel silicide contacts, NiSi 2-Si interfaces are particularly important as NiSi 2 is often found as the phase adjacent to the silicide-silicon interface during and after the silicidation. The interface orientation of these NiSi 2-Si interfaces as well as the ability to create abrupt and flat interfaces, ultimately with atomic sharpness, is essential for the properties of diverse emerging device concepts. We present a combined experimental and theoretical study on NiSi 2-Si interfaces. Interfaces in silicon nanowires were fabricated using silicidation and characterized by high-resolution (scanning) transmission electron microscopy. It is found that {111} interfaces occur in 〈110»nanowires. A tilted interface and an arrow-shaped interface are observed, which depends on the nanowire diameter. We have further modeled NiSi 2-Si interfaces by density functional theory. Different crystallographic orientations and interface variations, e.g., due to interface reconstruction, are compared with respect to interface energy densities. The {111} interface is energetically most favorable, which explains the experimental observations. Possible ways to control the interface type are discussed.

Manufactured nanomaterials (NMs) are materials in which 50% or more of the particles have one or more dimensions between 1 nm and 100 nm. These NMs show interesting properties. However, the same properties that motivate their use in applications are also reason for concern, as NMs can cause toxic reactions and have mobilities in the environment different from bulk materials of the same elements. Despite considerable scientific efforts, the selective detection of manufactured NMs in environmental compartments is still a very complex and challenging task. An expert review of the literature has been conducted on behalf of the German Environment Agency (UBA) to identify relevant methods for nanomaterial detection in complex media in the context of environmental monitoring and a need for action was concluded from the existing body of work.

The employment of radiotracers is a versatile tool for the detection of nano-particulate materials in complex systems such as environmental samples or organisms. The monitoring of nanoparticles (NPs) in such complex natural systems as soil, natural waters, plants, sewage sludge, etc. very is challenging using conventional methods, especially at environmentally relevant concentrations. This obstacle can be overcome by the use of radiolabeling which provides an easy way of accurately quantifying nanoparticles in complex systems without extensive sample preparation, regardless of any particulate or elemental background.
We have developed various methods of introducing radiotracers into the most common nanoparticles, such as Ag, carbon, SiO2, CeO2 and TiO2 nanoparticles.

In this study, a conceptually different approach for investigating magnetic phase transitions in ultra-thin films is presented. THz emission from a laser-excited material is used to monitor the magnetization dynamics during the laser-driven antiferromagnetic to ferromagnetic transition in FeRh. The emitted THz signal is calibrated against static magnetometry data measurements, giving a direct measure of the absolute magnetic moment of the sample on the sub-picosecond timescale. The technique is, therefore, highly complementary to conventional time-resolved experiments such as time resolved magneto-optic Kerr effect (MOKE) or x-ray magnetic circular dichroism.

Nonlinear optics is an increasingly important field for scientific and technological applications, owing to its relevance and potential for optical and optoelectronic technologies. Currently, there is an active search for suitable nonlinear material systems with efficient conversion and small material footprint. Ideally, the material system should allow for chip-integration and room-temperature operation. Two-dimensional materials are highly interesting in this regard. Particularly promising is graphene, which has demonstrated an exceptionally large nonlinearity in the terahertz regime. Yet, the light-matter interaction length in two-dimensional materials is inherently minimal, thus limiting the overall nonlinear-optical conversion efficiency. Here we overcome this challenge using a metamaterial platform that combines graphene with a photonic grating structure providing field enhancement. We measure terahertz third-harmonic generation in this metamaterial and obtain an effective third-order nonlinear susceptibility with a magnitude as large as 3·10−⁸ m² /V² , or 21 esu, for a fundamental frequencyof 0.7 THz. This nonlinearity is 50 times larger than what we obtain for graphene without grating. Such an enhancement corresponds to third-harmonic signal with an intensity that is three orders of magnitude larger due to the grating. Moreover, we demonstrate a field conversion efficiency for the third harmonic of up to ∼1% using a moderate field strength of ∼30 kV/cm. Finally we show that harmonics beyond the third are enhanced even more strongly, allowing us to observe signatures of up to the 9th harmonic. Grating-graphene metamaterials thus constitute an outstanding platform for commercially viable, CMOS compatible, room temperature, chip-integrated,THz nonlinear conversion applications.

Soil samples from different locations with varied cultivation histories of soybeans were taken from arable fields in 2018 in East Germany and Poland (Lower Silesia) to evaluate the specific microsymbionts of the soybean, Bradyrhizobium japonicum, over the years after inoculation. Soybean was grown in the selected farms between 2011 and 2017. The aim of the experiment is to investigate whether there is a difference in rhizobia content in soils in which soybean was grown over a different period of time and whether this might lead to differences in plant growth of soybean. The obtained soil samples were directly transferred into containers, then sterilized soybean seeds were sown into pots in the greenhouse. After 94 days of growth, the plants were harvested and various parameters such as nodular mass, number of nodules and dry matter in the individual plant parts were determined. In addition, the relative abundance of Bradyrhizobium sp. in soil samples was determined identified by sequencing. No major decline in Bradyrhizobia could be observed due to a longer interruption of soybean cultivation. Soil properties such as pH, P and Mg content had no significant influence on the formation of nodule mass and number, but seem to have an influence on the relative abundance of Bradyrhizobium sp. The investigations have shown that Bradyrhizobium japonicum persists longer in arable soils even under the site conditions of Central Europe and forms an effective symbiosis with soybeans.

Ein maßgebliches medizinisches Problem unserer Gesellschaft sind Krebs- und Tumor-erkrankungen. Aus diesem Grund sind die verbesserte Diagnose und Früherkennung von Krebserkrankungen sowie die Entwicklung neuer und effizienterer Therapiemöglichkeiten ein wichtiger Aspekt der gegenwärtigen medizinischen Forschung.
Die zielgerichtete α-Partikel Therapie (TAT, engl. Targeted Alpha-particle Therapy) ist eine spezielle Form der nuklearmedizinischen Behandlung von Krebserkrankungen und ordnet sich im Feld der Radionuklidtherapie ein. Die TAT hebt sich gegenüber anderen Radionuklidtherapien, wie der Behandlung mit β--oder Auger-Elektronen-Emittern, dadurch hervor, dass sie Chemo- und Strahlungsresistenzen überwinden kann, eine hohe biologische Wirksamkeit zeigt, und dabei gesundes Gewebe vergleichsmäßig wenig belastet.
Bei der TAT werden α-emittierende Radionuklide, hauptsächlich Radiometalle, mittels eines Radiopharmakons zielgerichtet an oder in die Krebszellen transportiert, welche dort hochenergetische α-Partikel emittieren, die zum Absterben des entarteten Gewebes führen. Um ein Radiopharmakon auf Basis eines Radiometalls herzustellen, werden die entsprechenden Radionuklide mittels eines Chelators stabil gebunden, welcher wiederum mit einem Vektormolekül verknüpft ist. Vektormoleküle können dabei monoklonale Antikörper oder niedermolekulare Verbindungen sein, welche spezifische Eigenschaften der Krebszelle adressieren und damit das selektive Binden an diese ermöglichen.
Nur wenige α-Emitter erfüllen die Voraussetzungen, um in der TAT eingesetzt werden zu können. Aus der Reihe der schweren Erdalkalimetalle stammen die beiden α-Emitter Radium 223 und Radium-224, welche großes Potential für eine solche radiopharmazeutische Anwendung besitzen. Zusätzlich kann der γ Emitter Barium 131, dessen Element das nächst leichtere Homologe des Radiums ist, zum Therapie-Monitoring eingesetzt werden. Aufgrund der chemischen Ähnlichkeit der Elemente Barium und Radium können beide mittels des gleichen Chelators gebunden und deren Radionuklide im Rahmen eines kombinierten diagnostischen und therapeutischen – eines so genannten theranostischen – Ansatzes in der Onkologie genutzt werden. Da von Radium keine stabilen Isotope existieren, dient Barium auch als ein nicht-radioaktives Surrogat, um Chelatoren initial bezüglich ihrer Komplex-bildungseigenschaften zu untersuchen.
Ziel dieser Arbeit war es, das Potential ausgewählter Radionuklide aus der Gruppe der schweren Erdalkalimetalle für die radiopharmazeutische Anwendung zu erschließen, und dafür die Möglichkeit ihrer stabilen Bindung in einem Radiopharmakon mittels eines geeigneten Chelators zu untersuchen. Der Fokus lag dabei auf Barium 131 und Radium 224. Als potentielle Chelatoren wurden die beiden Substanzklassen der Calix[4]aren-krone-6-Derivate und der Cavitanden untersucht.
Bei diesen Verbindungen handelt es sich um Makrozyklen, welche aus vier aromatischen Einheiten aufgebaut sind. Ihre Anordnung formt eine Kavität, welche auf die Ionengrößen von Barium und Radium zugeschnitten ist. Die beiden Grundstrukturen verfügen jeweils über acht Sauerstoffatome, die für die Koordination an Ba²⁺- beziehungsweise Ra²⁺-Ionen, ideale Donoratome darstellen.
Um die Interaktion der Liganden mit (nicht-radioaktiven) Bariumionen untersuchen zu können, wurden analytische Verfahren auf der Basis von NMR- und UV/Vis-Spektroskopie etabliert. Bei diesen Untersuchungen wurde für die Cavitanden trotzt weitreichender Optimierungsversuche keine Einlagerung von Bariumionen festgestellt.
Für die Calix[4]krone-6-basierten Derivate wurden die entsprechenden 1:1 Metallion-Ligand-Chelate mit Bariumionen hergestellt und nachgewiesen. Die Stabilität der Chelate wurde mit einer Titrationsmethode auf Basis von NMR- und UV/Vis Detektion bestimmt. Aufgrund der geringen Wasserlöslichkeit der gewählten Verbindungen wurden die initialen Versuche im Lösungsmittel Acetonitril durchgeführt. In nachfolgenden Optimierungsschritten wurden Calix[4]krone-6-basierte Chelatoren hergestellt, welche in Hinblick auf das HSAB-Konzept noch besser auf schwere Erdalkalimetalle abgestimmt waren. Zusätzlich wurden diese Chelatoren über funktionelle Gruppen mit einem Vektormolekül verknüpft, welches die Wasserlöslichkeit erhöhte.
Für nachfolgende Radiomarkierungsversuche wurden Dünnschichtchromatographie-Systeme etabliert, welche die Untersuchung von [¹³¹Ba]Ba²⁺- und [²²⁴Ra]Ra²⁺-Chelaten im wässrigen Medium sowie unter kompetitiven Bedingungen ermöglichten. Es konnten jedoch für alle Calix[4]krone-6-Derivate unter wässrigen Bedingungen keine Chelate nachgewiesen werden. Anschließende Untersuchungen legten nahe, dass das Radiometall kinetisch nicht ausreichend stabil in den Calix[4]krone-6-Derivate gebunden ist

We realize an ultracompact nanocytometer for real-time impedimetric detection and classification of subpopulations ofliving cells. Nanoscopic nanowires in a microfluidic channel act asnanocapacitors and measure in real time the change of theamplitude and phase of the output voltage and, thus, the electricalproperties of living cells. We perform the cell classification in thehuman peripheral blood (PBMC) and demonstrate for thefirsttime the possibility to discriminate monocytes andsubpopulationsof lymphocytes in a label-free format. Further, we demonstrate thatthe PBMC of acute myeloid leukemia and healthy samples grantthe label free identification of the disease. Using the algorithmbased on machine learning, we generatedspecific data patternstodiscriminate healthy donors and leukemia patients. Such a solutionhas the potential to improve the traditional diagnostics approaches with respect to the overall cost and time effort, in a label-freeformat, and restrictions of the complex data analysis.

Exfoliation of atomically-thin layers from non-van der Waals bulk solids gave rise to the emergence of a new class of two-dimensional (2D) materials, such as hematene (Hm), a structure just a few atoms thick obtained from hematite. Due to a large number of unsaturated sites, Hm surface can be passivated under ambient conditions. Using density functional theory calculations, we investigate the effects of surface passivation with H and OH groups on Hm properties and demonstrate that the passivated surfaces are energetically favorable under oxygen-rich conditions. While the bare sheet is antiferromagnetic and possesses an indirect band gap of 0.93 eV, the hydrogenated sheets are half-metallic with a ferromagnetic ground state, and the fully hydroxylated sheets are antiferromagnetic with a larger band gap as compared to the bare system. The electronic structure of Hm can be further tuned by mechanical deformations. The band gap of fully passivated Hm increases monotonically with biaxial strain, hinting at potential applications of Hm in electromechanical devices.

The Eddy Current Flow Meter is a reliable and robust inductive sensor for the measurement of flowrates in liquid metal flows. This kind of sensor is usually being used in pipe flows where the flow is mostly parallel to the sensor axis. When this sensor is used as part of the safety instrumentation above the subassemblies in liquid metal cooled fast reactors, the flow angle may change rapidly according to the conditions within the reactor. In this paper we investigate the performance of the Eddy Current Flow Meter in flows inclined to the sensor axis by numerical simulations as well as model experiments. We demonstrate that the Eddy Current Flow Meter yields reliable results for flow angles up to 30° while the sensitivity of the sensor is significantly reduced for larger angles.

We demonstrate the manipulation of magnetic phasesin FeRh thin filmsthrough atomic displacementsand the distributionof structural defects. Atomic scale disorder can be controlled via irradiation withlight noble gas ions, producingdepth-varying nanoscale phase configurationsof distinct antiferromagnetic, ferromagnetic and paramagnetic regions. Here, we perform a spatial characterization of the magnetic phasesandthe local magnetic environment around the Fe atoms,as well as the variation ofthe open-volumes around atomic sites. Thus,a direct correspondence between the existence of the three magnetic phases andlattice defects is revealed. By careful selection of the irradiating fluence, we show that it is possible to produce simple and thermally stable magnetic configurations, such as uniform magnetisation or a bilayer phase structure.Furthermore, the thin film surface and interfaces are observed as the nucleation sites for the transitions between the phases. These results demonstrate a sensitive nanoscale manipulation of magnetic properties, shedding light on magnetic ordering in alloy lattices and broadening the scope for applications.

This guideline on current good radiopharmacy practice (cGRPP) for small-scale preparation of radiopharmaceuticals represents the view of the Radiopharmacy Committee of the European Association of Nuclear Medicine (EANM). The guideline is laid out in the format of the EU Good Manufacturing Practice (GMP) guidelines as defined in EudraLex volume 4. It is intended for non-commercial sites such as hospital radiopharmacies, nuclear medicine departments, research PET centres and in general any healthcare establishments. In the first section, general aspects which are applicable to all levels of operations are discussed. The second section discusses the preparation of small-scale radiopharmaceuticals (SSRP) using licensed generators and kits. Finally, the third section goes into the more complex preparation of SSRP from non-licensed starting materials, often requiring a purification step and sterile filtration. The intention is that the guideline will assist radiopharmacies in the preparation of diagnostic and therapeutic SSRP´s safe for human administration.

We have investigated the field direction dependence of thermo-magnetic behavior in single crystalline Mn₅Ge₃. The adiabatic temperature change ΔTad in pulsed fields, the isothermal entropy change ΔS_iso calculated from static magnetization measurements, and heat capacity have been determined for fields parallel and perpendicular to the easy magnetic direction [001]. The isothermal magnetization measurements yield, furthermore, the uniaxial anisotropy constants in second and fourth order, K₁ and K₂. We discuss how the anisotropy affects the magneto-caloric effect (MCE) and compare the results to the related compound MnFe₄Si₃, which features an enhanced MCE, too, but instead exhibits strong easy plane anisotropy. Our study reveals the importance of magnetic anisotropy and opens new approaches for optimizing the performance of magnetocaloric materials in applications.

The majority of thin film studies that were devoted to Fe-oxyarsenides has focused so far on F-substituted (i.e. indirectly electron doped) LnOFeAs (Ln = La, Nd, Sm). Here we turn our attention towards Co-substituted (i.e. directly electron doped) LaOFeAs and SmOFeAs in order to investigate its growth on different substrate materials by using pulsed laser deposition (PLD). We detected dominant LnOFeAs phase formation and discuss the occurrence of minor impurity phases in the different films on different substrates. The lack of a superconducting transition in LnOFe_0.85Co_0.15As films on MgO(100) could be due to strain, since we observe an onset of superconductivity in SmOFe_1−xCo_xAs (x = 0.07, 0.15) films on other oxide substrates. In addition, Co-substitution (i.e. within the Fe2As2 layers) and F-substitution (i.e. within the Ln₂O₂ layers) leading to direct and indirect electron doping respectively, appears for films deposited on CaF₂ substrates. In contrast to the F-substituted but Co-free Fe-oxyarsenides, the co-doped SmO_1−xF_xFe_0.85Co_0.15As film has experimentally accessible upper critical fields down to the lowest temperatures and may serve as an ideal test bed for further theoretical modeling of Fe-oxyarsenides.

This work describes an effective method for the preparation of open-cell ceramic foams for their further use as catalyst supports. The polyurethane sponge replica technique was applied using a ceramic suspension based on a mixture of α-alumina, magnesia and titania and polyvinyl alcohol solution as a liquid component. The polyurethane sponge was etched with NaOH and covered with colloidal silica to obtain better adhesion of the slurry to the walls of the polymeric material onto it. The surface area of the ceramic carrier was increased by adding a layer of γ-alumina. Deposition of an active catalytic phase (Pt) was done by impregnation. Properties of the carriers and the final catalyst were investigated by a number of physico-chemical methods such as TEM, SEM, XRD and computer tomography. Hydrogenation of ethyl benzoylformate was performed to elucidate the catalytic properties of foam catalysts illustrating their applicability.

In this study, a detailed investigation of the dynamics of the generation of pre-pulse bypost-pulses is presented, using single-shot self-referenced spectral interferometry (SRSI). The capabilityof SRSI in terms of the single-shot measurement of the temporal contrast of high-power lasersystems has been experimentally demonstrated. The results confirm that the energy levels of thepre-pulses increase proportional to the square of the B-integral parametrizing the nonlinearity of theamplifier chain.

At the HZDR TO-AC contrast measurement tools and newly developed single-shot diagnostics characterizing laser pulses are applied for laser improvements and particle acceleration experiments. An overview of the applied techniques and recent results is presented.

The adsorption of chiral molecules was recently shown to trigger a change in the magnetisation of mesoscopic magnetic domains in a ferromagnetic underlayer. In this work, we investigated the macroscopic (magneto-)optical response of chemisorbed α-helical polyalanine self-assembled monolayers (SAMs) on a gold and gold-capped-cobalt thin film on Au substrates using spectroscopic ellipsometry and magneto-optical Kerr effect spectroscopy and microscopy. The optical and magneto-optical spectra reveal selective chemisorption of the α-helical polyalanine molecules depending on the orientation of the substrate remanent magnetisation during the SAMs process. Moreover, a sign change of the magneto-optical response was observed in some of the magnetic substrates after the chiral SAMs formation.

We report on a new approach to measure the accumulated B-integral in the regenerative and multipass amplifier stages of ultrashort-pulse high-power laser systems by B-integral-induced coupling between delayed test post-pulses and the main pulse. A numerical model for such non-linear pulse coupling is presented and compared to data taken at the high-power laser Draco with self-referenced spectral interferometry (SRSI). The dependence of the B-integral accumulated in the regenerative amplifier on its operation mode enables optimization strategies for extracted energy vs. collected B-integral. The technique presented here can, in principle, be applied to characterize any type of ultrashort pulse laser system and is essential for pre-pulse reduction.

The quest for renewable energy sources entails an increasingly intermittent electricity supply.
Transmission grid updates can only partially account for balancing the resulting variations and large-scale stationary storage will gain importance in future energy landscapes dominated by volatile sources.
Today’s battery technologies were, with the notable exception of redox-flow batteries, mainly designed for and driven by mobile applications. Those prioritize properties (energy density, power rating) that are less important for stationary storage. Thus, battery technologies developed from the ground up to meet the needs of stationary storage have the potential to much better address the specifics of huge capacity installations.
Liquid metal batteries (LMBs) are a new technology for grid-scale energy storage, see [1] for a comprehensive review. They consist of all liquid cells that operate with liquid metals as electrodes and molten salts as electrolytes. The liquids separate into three stably stratified layers by virtue of density and mutual immiscibility (see the two upper left inserts in Fig. 1a). This conceptually very simple and self-assembling structure has the unique advantage to allow for an easy scale-up at the cell level: single-cell cross sections can potentially reach several square-meters. Such cell sizes enable highly favourable and otherwise unattainable ratios of active to construction material because of the cubic scaling (volume) of the former and the quadratic scaling (surface) of the latter. The total costs should therefore largely be determined by those of the active materials.
The talk will start with a general introduction to LMBs and then focus on the fluid mechanics in these devices [2]. Electric currents, magnetic fields, and heat and mass transfer are tightly coupled with the cells’ electrochemistry. First a number of fluid dynamic instabilities will be discussed in relation to operational safety. The remainder of the talk will deal with transport phenomena in the positive electrode. While transport in most modern battery systems is typically dominated by diffusion and migration in micrometer-scale liquid layers and solids, convection - with exception of the aforementioned redox-flow batteries - rarely plays a role. This is in stark contrast to LMBs were mediated by the fully liquid interior fluid flow can be driven by various mechanisms. The influence of solutal convection on the cycling behavior of a cell (Fig. 1a) will be demonstrated. Electromagnetically induced convection can be used to improve mixing (Fig. 1b) thereby mitigating diffusion overpotentials.

Polyoxometalates (POMs) represent a fascinating class of inorganic cluster compounds. Due to the almost unlimited possibilities to tailor size, shape and charge of this compound class and to perform various surface functionalization, they are discussed for different applications, especially in the fields of catalysis, material sciences and biomedicine. In contrast, the systematic study of extraction and sorption properties of POMs has received relatively little attention so far. This review article provides a brief overview of relevant POM structures used for effective and selective phase transfer of metal ions from aqueous into organic media as well as for the development of efficient sorption processes. The use of inorganic-organic POM-based hybrid materials for extraction and sorption processes is also discussed.

In modern biomaterial-based electronics, conductive and flexible biomaterials are gaining increasing attention for their wide range of applications in biomedical and wearable electronics industries. The ecofriendly, biodegradable, and self-resorbable nature of these materials makes them an excellent choice in fabricating green and transient electronics. Surface functionalization of these biomaterials is required to cater to the need of designing electronics based on these substrate materials. In this work, a low-temperature atomic layer deposition (ALD) process of platinum (Pt) is presented to deposit a conductive thin film on collagen biomaterials, for the first time. Surface characterization revealed that a very thin ALD-deposited seed layer of TiO2 on the collagen surface prior to Pt deposition is an alternative for achieving a better nucleation and 100% surface coverage of ultrathin Pt on collagen surfaces. The presence of a pure metallic Pt thin film was confirmed from surface chemical characterization. Electrical characterization proved the existence of a continuous and conductive Pt thin film (∼27.8 ± 1.4 nm) on collagen with a resistivity of 295 ± 30 μΩ cm, which occurred because of the virtue of TiO2. Analysis of its electronic structures showed that the presence of metastable state due to the presence of TiO2 enables electrons to easily flow from valence into conductive bands. As a result, this turned collagen into a flexible conductive biomaterial.

The present work deals with the corrosion of mild steel (1.0037) used as the outer construction material of the preheater of a modern industrial cement production facility. The facility uses secondary fuels, which introduce considerable amounts of corrosive species. The situation at the examination sites in the preheater zone is tracked over a period of two years including operation and shut-down periods. The investigation is focused on (i) the acquisition of the underlying physicochemical conditions, such as moisture, temperature, and contamination data at the examination site of the preheater, (ii) the multianalytical identification of the formed corrosion products using scanning electron microscopy combined with energy-dispersive X-ray analysis, infrared spectrometry, Raman spectrometry, X-ray diffractometry, and Möβbauer spectrometry, and (iii) voltammetric and EIS laboratory investigations using model solutions. It was evidenced that corrosion takes place at a temperature level of about 100°C in the presence of moisture and oxygen as well as chloride ion as a consequence of the usage of secondary fuels. Typical hot-gas corrosion could be excluded under the current conditions. Appearance, structure, and nature of the corrosion products were found to be not mainly dependent on the varied length of exposure, but on the conditions of the hosting preheater intake. In addition to different FeOOH phases and hematite, magnetite was found, dependent on the oxygen concentration in the process gas. The decisive role of oxygen as key factor for the corrosion rate was electrochemically confirmed.

The concept of an active dosimetry system for pulsed radiation dose rate measurements is presented. Real-time distinction of pulsed and non-pulsed radiation contributions is based on the time structure of a single interaction. A fast tissue equivalent plastic scintillator is exploited to minimize the pile-up effect influence on absorbed energy measurements. Being connected to a fully digital signal processing board, the detector creates an active dosimetry system with adjustable parameters. With this system, absorbed dose rate measurements were carried out in a photon field with a time structure mimicking a radiotherapeutic beam, but also in the presence of a constant radiation field. Measurements show a linear dependence of a pulsed radiation contribution on the accelerator current in the investigated range of the total dose rate up to 8 μGy h⁻¹. While increasing the accelerator current by 1 μA, the pulsed radiation dose rate grows by (26.2±0.9) nGy h⁻¹ when considering pile-up events.

Radiomics aims to characterise the tumour phenotype using advanced image features to predict patient-specific outcome. ...

Background
The limited availability of proton beam therapy (PBT) requires individual treatment selection strategies, such as the model-based approach. We compared PBT and photon therapy using several normal tissue complication probability (NTCP) models to assess the feasibility of this approach in brain tumour patients.
Methods
For 92 patients treated at two PBT centres, volumetric modulated arc therapy treatment plans were retrospectively created for comparison with the clinically applied PBT plans. Several dosimetric parameters for the brain excluding tumour and margins, cerebellum, brain stem, frontal and temporal lobes, hippocampi, cochleae, chiasm, optic nerves, lacrimal glands, lenses, pituitary gland, and skin were compared between both modalities using Wilcoxon signed-rank tests. NTCP differences (ΔNTCP) were calculated for 11 models predicting brain necrosis, delayed recall, temporal lobe injury, hearing loss, tinnitus, blindness, ocular toxicity, cataract, endocrine dysfunction, alopecia, and erythema. A patient was assumed to be selected for PBT if ΔNTCP exceeded a threshold of 10 percentage points for at least one of the side-effects.
Results
PBT substantially reduced the dose in almost all investigated OARs, especially in the low and intermediate dose ranges and for contralateral organs. In general, NTCP predictions were significantly lower for PBT compared to XRT. Considering ΔNTCP of all models, 80 patients (87.0%) would have been selected for PBT in this in-silico study, mainly due to predictions of a model on delayed recall (51 patients). In contrast to the dosimetric analysis, NTCP was substantially reduced in ipsilateral organs.
Conclusion
This study underlines that physical dose-volume parameters alone may not be sufficient to describe the clinical relevance between different reatment techniques and highlights potential benefits of NTCP models. Further NTCP models for different modern treatment techniques are mandatory and existing models have to be externally validated in order to implement the model-based approach in clinical practice.

Introduction
The immunocytokine L19-IL2 delivers interleukin-2 to the tumor by exploiting the selective L19-dependent binding of extradomain B of fibronectin on tumor blood vessels. In preclinical models, L19-IL2 has been shown to enhance the local and abscopal effects of radiotherapy. The clinical safety of L19-IL2 monotherapy has been established previously. In this study, the safety and tolerability of L19-IL2 following Stereotactic Body Radiotherapy (SBRT) was assessed.
Materials and methods
Patients with oligometastatic solid tumors received radical SBRT to all visible metastases. Within one week following SBRT, intravenous L19-IL2 using a 3+3 dose escalation design was administered. Safety and tolerability were analyzed as the primary endpoint using the CTCAE4.03 scoring system, progression-free and overall survival as secondary endpoints.
Results
A total of 6 patients in two L19-IL2 dose levels were included. The 15 Mio International Units (IU) dose level was well tolerated with no dose limiting toxicity. The most frequently reported adverse events were chills, noninfectious fever, fatigue, edema, erythema, pruritus, nausea/vomiting as well as cough and dyspnea. Blood analysis revealed abnormalities in liver function tests, anemia, hypoalbuminemia, and hypokalemia. At the second dose level (i.e., 22.5 Mio IU), which is the recommended dose for L19-IL2 monotherapy, all three included patients experienced dose-limiting toxicity, but toxicities recovered without sequelae. We documented two long-term progression-free responders both having non-small cell lung cancer as primary tumor.
Conclusion
Based in the results of this phase I clinical trial, the recommended phase II dose for SBRT combined with L19-IL2 is 15 Mio IU. The therapeutic efficacy of this combination is currently being evaluated in the multicentric EU-funded phase II clinical trial, ImmunoSABR.

Objective To implement Computed Tomography (CT)-based attenuation maps of radiotherapy (RT) positioning hardware and radiofrequency (RF) coils to enable hybrid positron emission tomography/magnetic resonance imaging (PET/MRI)-based RT treatment planning. Materials and Methods The RT positioning hardware consisted of a flat RT table overlay, coil holders for abdominal scans, coil holders for head and neck scans and an MRI compatible hip and leg immobilization system. CT images of each hardware element were acquired on a CT scanner. Based on the CT images, attenuation maps of the devices were created. Validation measurements were performed on a PET/MR scanner using a 68Ge phantom (48 MBq, 10 min scan time). Scans with each device in treatment position were performed. Then, reference scans containing only the phantom were taken. The scans were reconstructed online (at the PET/MRI scanner) and offline (via e7tools on a PC) using identical reconstruction parameters. Average reconstructed activity concentrations of the device and reference scans were compared. Results The device attenuation maps were successfully implemented. The RT positioning devices caused an average decrease of reconstructed PET activity concentration in the range between -8.3 ± 2.1 % (mean ± SD) (head and neck coil holder with coils) to -1.0 ± 0.5 % (abdominal coil holder). With attenuation correction taking into account RT hardware, these values were reduced to -2.0 ± 1.2 % and 0.6 ± 0.5 %, respectively. The results of the offline and online reconstructions were nearly identical, with a difference of up to 0.2 %. Conclusion The decrease in reconstructed activity concentration caused by the RT positioning devices is clinically relevant and can successfully be corrected using CT-based attenuation maps. Both the offline and online reconstruction methods are viable options.

Radiation therapy with proton beams allows the deposition of high doses to the tumour while minimising dose to the surrounding tissue. During such treatment the patient is also exposed to secondary radiation which produces an out-of-field dose that affects healthy tissue. The largest contribution to this out-of-field dose comes from neutron radiation; therefore, it is of interest to fully characterise the neutron field in the therapy room with measurements. This is usually done with Bonner sphere spectrometers using active detectors, typically ³He-filled proportional counters, as central thermal neutron sensors. Under the experimental conditions encountered in proton therapy facilities, a proper analysis of the measurements is impossible unless dead time corrections are implemented. In this paper, we present a method using a paralysable dead time model for carrying out such corrections for Bonner sphere measurements with ³He-filled proportional counters and apply it to data taken at the University Proton Therapy Dresden (UPTD) facility in double scattering mode. The neutron events were recorded with time stamps and, based on this time-resolved data, the measured neutron rate distribution was sampled. Since the neutron flux is proportional to the proton flux, the integral neutron flux is directly related to the proton dose. Hence, we were able to estimate the detector dead time from the measured rate distributions recorded for a set of measurements with different proton dose rates. Experimental measurements with different intensities of the proton field show that the corrections are in agreement within 0.5% for measured signal rates smaller than 15×10³ counts per second and do not exceed 1% at 25×10³ counts per second.

4H-silicon carbide-on-insulator (4H–SiCOI) serves as a novel and high efficient integration platform for nonlinear optics and quantum photonics. The realization of wafer-scale fabrication of single-crystalline semi-insulating 4H–SiC film on Si (100) substrate using the ion-cutting and layer transferring technique was demonstrated in this work. The thermodynamics of 4H–SiC surface blistering is investigated via observing the blistering phenomenon with a series of implanted fluences and annealing temperatures. Surface tomography and the depth dependent film quality of the 4H–SiC have been extensively studied by employing scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, X-ray diffraction (XRD) was carried out and the diffraction spectrum reveals a narrow peak with a full width at half maximum (FWHM) of 75.6 arcsec, indicating a good maintenance of the single-crystalline phase for the prepared thin film of 4H–SiC as compared to its bulk counterpart. With the single-crystalline 4H–SiCOI, we have successfully fabricated a micro-ring resonator with a quality factor as high as 6.6 × 104. The reported 4H–SiCOI wafer provides a feasible monolithic platform for integrated photonic applications.

Compositional data carry their relevant information in the relationships (logratios) between the compositional parts. It is shown how this source of information can be used in regression modeling, where the composition could either form the response, or the explanatory part, or even both. An essential step to set up a regression model is the way how the composition(s) enter the model. Here, balance coordinates will be constructed that support an interpretation of the regression coefficients and allow for testing hypotheses of subcompositional independence. Both classical least-squares regression and robust MM regression are treated, and they are compared within different regression models at a real data set from a geochemical mapping project.

Few-layer PtSe2 films are promising candidates for applications in high-speed electronics, spintronics and photodetectors. Reproducible fabrication of large-area highly crystalline films is, however, still a challenge. Here, we report the fabrication of epitaxially aligned PtSe2 films using one-zone selenization of pre-sputtered platinum layers. We have studied the influence of growth conditions onstructural and electrical properties of the films prepared from Pt layers with different initial thickness. The best results were obtained for the PtSe2 layers grown at elevated temperatures (600 °C). The films exhibit signatures for a long-range in-plane ordering resembling an epitaxial growth. The charge carrier mobility determined by Hall-effect measurements is up to 24 cm²/V.s

Two series of isostructural tetravalent actinide amidinates [AnX((S)-PEBA)3] (An = Th, U, Np; X = Cl, N3) bearing the chiral (S,S)-N,N’-bis-(1-phenylethyl)benzamidinate ((S)- PEBA) ligand have been synthesized and thoroughly characterized in solid and in solution. This study expands the already reported tetravalent neptunium complexes to the lighter actinides thorium and uranium. Furthermore, a rare Ce(IV) amidinate [CeCl((S)-PEBA)3] was synthesized to compare its properties to those of the analogous tetravalent actinide complexes. All compounds were characterized in the solid state using single crystal XRD and infrared spectroscopy and in solution using NMR spectroscopy. Quantum chemical bonding analysis including also the isostructural Pa and Pu complexes was used to characterize the covalent contributions to any bond involving the metal cation. Th shows the least covalent character throughout the series, even substantially smaller than for the Ce complex. For U, Np, and Pu similar covalent bonding contributions are found, but a natural population analysis reveals different origins. The 6d participation is the highest for U and decreases afterwards, whereas the 5f participation increases continuously from Pa to Pu.

The actinide-containing mineral monazite–(Ce) is a common accessory rock component that bears petrogenetic information, is widely used in geochronology and thermochronology, and is considered as potential host material for immobilisation of radioactive waste. Natural samples of this mineral show merely moderate degrees of radiation damage, despite having sustained high self-irradiation induced by the decay of Th and U (for the sample studied herein 8.9 ± 0.3 × 10¹⁹ α/g). This is assigned to low damage-annealing temperature of monazite–(Ce) and “alpha-particle-assisted reconstitution”.
Here we show that the response of monazite–(Ce) to alpha radiation changes dramatically, depending on the damage state. Only in radiation-damaged monazite–(Ce), ⁴He ions cause gradual structural restoration. In contrast, its high-temperature annealed (i.e. well crystalline) analogue and synthetic CePO₄ experience He-irradiation damage. Alpha-assisted annealing contributes to preventing irradiation-induced amorphisation (“metamictisation”) of monazite–(Ce); however, this process is only significant above a certain damage level.

Detailed derivation of the analytical, reciprocal-space approach of Hessian calculation within the self- consistent-charge density functional based tight-binding framework (SCC-DFTB) is presented. This ap- proach provides an accurate and efficient way for obtaining the SCC-DFTB Hessian of periodic systems. Its superiority with respect to the traditional numerical force differentiation method is demonstrated for doped graphene, graphene nanoribbons, boron-nitride nanotubes, bulk zinc-oxide and other systems.

Zur Zeit werden in Deutschland noch 6 Kernkraftwerke zur Stromerzeugung betrieben. Bis 2022 soll das letzte Kernkraftwerk abgeschaltet werden – Deutschlands Ausstieg aus der Atomkraft. Der Atomausstieg ist ein wichtiger Schritt für die Energiewende mit dem Ziel einer langfristigen und vollständigen Umstellung auf erneuerbare Energien wie z. B. Wasserkraft, Sonnen- und Windenergie.
Der Ausstieg aus der Kernenergie bringt auch einige Konsequenzen mit sich, für welche wir die Verantwortung übernehmen müssen. Eine der größten Herausforderungen ist dabei die sichere und langfristige Lagerung des Atommülls. Weltweit hat sich hierbei das Konzept einer tiefen-geologischen Lagerung – etwa 500 m bis 1000 m unter der Erde – durchgesetzt. Die unterschiedlichen Materialien und Gesteine werden momentan auf ihre Eignung für das Endlager in Deutschland untersucht. Viele verschiedene Fachdisziplinen sind dafür relevant: Geologie, Mineralogie, (Radio-)Chemie, Physik, Mathematik, Materialwissenschaften, Architektur – um hier nur einige zu nennen.
Interessanterweise spielt auch die Biologie bei der Planung des Endlagers eine Rolle. Lebewesen können auf verschiedene Art und Weise mit den hier verwendeten Materialien – sogar mit dem Atommüll selbst – interagieren. Zu den hauptsächlich hier betrachteten Lebewesen zählen Pflanzen, Pilze und Mikroorganismen (Bakterien, Archaeen, einzellige Eukaryota). Bedingt durch ihren Stoffwechsel sind Mikroorganismen in der Lage, Materialien und deren Eigenschaften zu verändern. Da die Lagerung des Atommülls sicher und langfristig sein muss, ist es wichtig zu erforschen, inwiefern Mikroorganismen die verwendeten Materialien verändern und deren Eigenschaften möglicherweis beeinflussen.

Der Vortrag gibt einen Einblick in die faszinierende Welt der Mikroorganismen und zeigt zugleich deren Relevanz für die sichere und langfristige Lagerung des Atommülls.

Au-silica core-shell nanoparticles have been irradiated with 20 keV He+ ions up to a maximum fluence of 4.7x10(17) ions/cm(2). The nanoscale structural and crystallographic evolution induced by He+ ion irradiation was followed at various stages using Transmission Electron Microscopy (TEM). During irradiation satellite Au clusters are formed around the main Au core, which remained crystalline even after the maximum He+ ion fluence. The spherical silica shell deformed into a hemisphere due to He+ ion irradiation. Three dimensional Monte-Carlo simulations, based on the binary collision approximation, have been performed on stacked infinite layers and an individual particle. The stacked layers results show that the He+ beam interacts with most of the nanoparticle and Au migrates in the direction of beam incidence agreeing with experimental findings. The individual particle results match the experiment in terms of the volume which is sputtered away however additional mechanisms, not included in the simulations, are present in the experiment during the satellite formation and silica shell deformation. These results show the ability for 20 keV He+ ions to be used for the modification of nanostructures. Furthermore, these results contribute to a quantitative understanding of the dynamic evolution of materials observed using microscopy techniques based on He+ ions.

A deep geological disposal by using multiple barriers is favored for the long-term storage of high-level radioactive waste. A safe long-term storage means to analyze the applied materials according to their structural properties and stability in order to identify potential risks that could evolve during the operational phase and on the long run. So far, several concepts in Europe prefer cast iron and copper as canister materials (technical barrier) and bentonite as backfill- and buffering-/sealing material in between the canister and the host rock formation. In order to analyze the influence of naturally occurring microorganisms in bentonite on the respective barrier materials, different microcosm experiments were set up. These slurry experiments contain the Bavarian B25 bentonite, synthetic Opalinus Clay pore water or cap rock solution as well as copper- or cast iron plates in various combinations. During an incubation time of 400 days under anaerobic conditions at 37 °C, several bio-geochemical parameters (e.g. pH, redox potential and the concentration of minerals, sulfate, iron(II/III) and organic acids) were analyzed as well as the development of microbial diversity and incubated metal plates in the respective experiments. The obtained results provide insights into the complex interplay between bentonite, pore water, metals and microorganisms and can help to get a deeper understanding of the corrosion process of canister materials under the applied conditions.

In a previous study, EphB4 was demonstrated to be a positive regulator of A375 melanoma growth but a negative regulator of tumor vascularization and perfusion. To distinguish between EphB4 forward and ephrinB2 reverse signaling, we used the commercially available EphB4 kinase inhibitor NVP BHG712 (NVP), which was later identified as its regioisomer NVPiso. Since there have been reported significant differences between the inhibition profiles of NVP and NVPiso, we compared the influence of NVP and NVPiso on tumor characteristics under the same experimental conditions. Despite of different inhibitory profiles of NVP and NVPiso, the comparative study conducted here showed the same EphB4-induced effects in vivo as in the previous investigation. This confirmed the conclusion that EphB4-ephrinB2 reverse signaling is responsible for increased tumor growth as well as decreased tumor vascularization and perfusion. These results are further substantiated by microarrays showing differences between mock-transfected and EphB4-transfected (A375-EphB4) cells with respect to at least 9 angiogenesis-related proteins. Decreased expression of VEGF, Ang-1, and Akt/PKB, together with the increased expression of TIMP-1 and TGF-2, is consistent with the impaired vascularization of A375-EphB4 xenografts. Functional overexpression of EphB4 in A375-EphB4 cells was confirmed by activation of a variety of signaling pathways including JAK/STAT, Ras/Raf/MEK, and NFkB.

We conduct magnetic spherical Couette (MSC) flow experiments in the return flow instability regime with GaInSn as the working fluid, and the ratio of the inner to the outer sphere radii rᵢ/rₒ= 0.5, the Reynolds number Re = 1000, and the Hartmann number Ha ∈ [27.5, 40]. Rotating waves with different azimuthal wavenumbers m ∈ {2, 3, 4} manifest in certain ranges of Ha in the experiments, depending on whether the values of Ha were fixed or varied from different initial values. These observations demonstrate the multistability of rotating waves, which we attribute to the dynamical system representing the state of the MSC flow tending to move along the same solution branch of the bifurcation diagram when Ha is varied. In experiments with both fixed and varying Ha, the rotation frequencies of the rotating waves are consistent with the results of nonlinear stability analysis. A brief numerical investigation shows that differences in the azimuthal wavenumbers of the rotating waves that develop in the flow also depend on the azimuthal modes that are initially excited.

The China Institute of Atomic Energy (CIAE) proposed some of the China Experimental Fast Reactor (CEFR) neutronics start-up test data for the IAEA benchmark within the scope of the IAEA’s coordinated research activity. The coordinated research project (CRP) on “Neutronics Benchmark of CEFR Start-Up Tests” was launched in 2018. This benchmark aims to perform validation and verification of the physical models and the neutronics simulation codes by comparing calculation results against collected experimental data. Twenty-nine participating research organizations finished performing independent blind calculations and are refining their calculation results by referring to measurement data. The main objective of this benchmark is to improve understanding of the start-up of SFRs and validate the state-of-the-art fast reactor analysis computer codes against the recent experimental data obtained at the modern experimental SFR.
This paper introduces the following three kinds of reactivity measurements in the CEFR start-up test and presents the results by participants: temperature coefficient, sodium void reactivity, and swap reactivity. The measurements were done at the basic core in operation loading with fuel assemblies. First, for the measurement of temperature coefficients, ten sets of data were obtained by increasing and decreasing the temperature. For each temperature, the control rod position is changed to maintain the reactor as a critical. Second, sodium void reactivity is measured by replacing a fuel SA by vacuum-sealed SA and searching for the critical position of control rods. Third, for the measurement of the swap reactivity, fuel subassembly is replaced by SS subassembly, and SS subassembly is switched with one fuel subassembly. Swap reactivities are measured in two ways, with more than two control rods moving to find the criticality of the core in ‘Multiple Rods’ case, and only one control rod moving in the ‘Single Rod’ case. All three reactivities are obtained by a combination of control rod worth for changed rod position and criticality difference. Therefore, accuracy on control rod worth is important for benchmark calculation.
The comparison shows that uncertainty of calculations, modeling errors, and inaccurately determined control assembly worths make it challenging to calculate the temperature coefficient precisely. Depending on how modeling a vacuum-sealed fuel SA, the sodium void reactivity results from participants show large deviations. For swap reactivity calculation, the reactivity induced by the assembly swap is relatively larger than the temperature coefficient measurement. The swap reactivity calculation results from participants have similar trends and show good agreement with measurement.

Paper considers results of control rods worth calculation tests which have been done in IAEA coordinate research project (CRP) of China Experimental Fast Reactor (CEFR). Obtained results of more than 20 participants from 17 countries include neutronic calculations by using deterministic and stochastic codes. During RCM these results been compared by method of calculation and between it.
Calculation performed for all types of control rods used in CEFR as “light” for power control and “heavy” rods for shutdown and fuel burning compensation. Summary values of k-eff and rods worth are closed to each other, of course the some difference can be seen in comparison of two different methods of calculation but, in general, this difference not more 2 percent. For light rods relative deviation from average value is not more 10 % mostly. For heavy rods such deviation is not more 5%. Considering calculation results for group rods worth can be saying that difference between codes not more 2% in most cases.

From the analysis of the cyclotron resonance, we experimentally obtain the band structure of the threedimensional topological insulator based on a HgTe thin film. Top gating was used to shift the Fermi level in the film, allowing us to detect separate resonance modes corresponding to the surface states at two opposite film interfaces, the bulk conduction band, and the valence band. The experimental band structure agrees reasonably well with the predictions of the k · p model. Due to the strong hybridization of the surface and bulk bands, the dispersion of the surface states is close to parabolic in the broad range of the electron energies.

The objective of this WP is to identify and explain synergetic effects of VVER-1000 typical alloying elements in terms of irradiation-induced microstructures and mechanical property changes. Suitable materials are available in the neutron-irradiated condition from the LYRA-10 irradiation experiment. The approach is based on the application of complementary microstructural characterization techniques such as SEM, (S)TEM, APT, SANS, PAS to study low-Cu base and weld materials of intentionally varied contents of Ni, Mn and Si. In order to identify a synergetic effect of elements X and Y, low-X/low-Y, high-X/low-Y, low-X/high-Y and high-X/high-Y materials are to be compared and statistically evaluated with respect to mechanical property changes as well as type, composition, volume fraction, number density and size of irradiation-induced nano-features. Post-irradiation annealing allows the thermal stability of the defects to be evaluated. An additional objective is to provide a link between irradiated microstructures and mechanical property changes for highly irradiated VVER-1000 type steels.

In this talk, selected results of nanoindentation testing of unirradiated, neutron irradiated and ion irradiated (1 and 5 MeV) Fe-based materials are presented. The Nix-Gao approach is applied in order to extract the bulk-equivalent hardenss. Cross-sectional transmission electron microscopy shows how ion-irradiated microstructures look like. The available information is used to develop a microstructure-informed prediction model of irradiation hardening.

The talk presents the goals and intended work within the EU ENTENTE project. The focus is on work package 3, task 3.2 regarding microstructural characterisation planned within the project.

The talk presents the goals and intended work within the EU ENTENTE project. The focus is on work package 2, task 2.4 regarding the data collection contribution within the project.

We investigate AlN grown on 4H- and 6H-SiC substrates using Raman spectroscopy. We obtain the Raman peak shifts in 4H- and 6H-SiC substrates across the heterointerface and along the entire depth of the SiC layer. Using the earlier experimental prediction for the phonon deformation potential constants, we determine the stress tensor components in the 4H-SiC layer as a function of the distance from the AlN/SiC heterointerface and estimate the stress tensor value along the entire depth of the 6H-SiC layer. The maximum compressing stress values lie in the range of -1.7 GPa for the 4H-SiC/AlN heterostructure and in the range of -1.5 GPa for the 6H-SiC/AlN heterostructure.

In contrast to all other members of the RMn₂O₅ family with nonzero 4 f electrons (R = Nd to Lu), PrMn₂O₅ does not show any spin driven ferroelectricity in the magnetically ordered phase. By means of high-field electric polarization measurements up to 45 T, we have found that this exceptional candidate undergoes a spin driven multiferroic phase under magnetic field. X-ray magnetic circular dichroism studies up to 30 T at the Pr L₂ edge show that this ferroelectricity originates from and directly couples to the ferromagnetic component of the Pr³⁺spins. Experimental observations along with our generalized gradient-approximation+U calculations reveal that this exotic ferroelectric-ferromagnetic combination stabilizes through the exchange-striction mechanism solely driven by a 3d-4f-type coupling, as opposed to the other RMn₂O₅ members with 3d-3d driven ferroelectric-antiferromagnetic-type conventional type-II multiferroicity.

The correlative approach of real-time aerosol measurements with offline filter analysis and ParticleInduced X-ray Emission (PIXE) can significantly enhance the scope of aerosol studies. Aerosol particles have diverse physical and chemical properties, thus having a direct impact on air quality, cloud nucleation the planetary radiation balance, public health, etc. Essential information on the chemical composition of aerosol particles can be deduced from the elemental concentrations measured simultaneously for many elements by non-destructive and undemanding PIXE (Lucarelli, 2018). Furthermore, PIXE measurements can be performed with a focused beam allowing the analysis of individual particles (Biancato, 2006). Determining elemental concentrations is also important input information for aerosol source apportionment models and consequently abatement measures in order to improve air quality (Artaxo, 1999). Complementary information of aerosol particles structure down to nm scale, can be obtained with a Helium Ion Microscope (HIM), which, to our knowledge, has never been used before for aerosol characterization. The detection of secondary electrons and backscattered ions enables sub nm lateral resolution and large depth-of-field, also on insulating samples. In addition, a concurrent secondary ion mass spectrometry (ToF-SIMS) integrated in the HIM can provide insights of the composition of elements and molecules with imaging capabilities of sub 8 nm (Klingner, 2019).
In this study we coupled real-time measurements of optical properties of aerosols with an Aethalometer (Drinovec, 2015) and their carbon content with a Total Carbon Analyzer (Rigler, 2019) with PIXE and HIM analysis. Ambient aerosols were collected on quartz filters and quartz filters with Teflon coating during different pollution events (traffic or biomass burning dominated, Saharan dust dominated, etc.) at an urban background sampling site in Ljubljana, Slovenia (46o04’17’’N, 14o30’06’’E). The PM2.5 inlet was used for sampling carbonaceous aerosol while a virtual impactor was used for concentrating coarse particles during Saharan dust events.
PIXE measurements have been performed on these collected samples and compared to optical properties and source apportionment obtained by the online instruments. The PIXE measurements were performed across several hundred-micrometer regions and on individual points and results are presented including a description of the procedures for quantification. Complementary high-resolution imaging and sputtered ion analysis on single black carbon and Saharian dust aerosol particles was done on the HIM to study their structure and coating composition. The combination of all methods yields a comprehensive view of the aerosol particles.

HIFIS aims to ensure an excellent information environment for outstanding research in all Helmholtz research fields and a seamless and performant IT-infrastructure connecting knowledge from all centres. It will build a secure and easy-to-use collaborative environment with efficiently accessible ICT services from anywhere. HIFIS will also support the development of research software with a high level of quality, visibility and sustainability.
In this talk we will present current offers of the HIFIS platform. The focus is on the Software Services pillar of HIFIS.

Next generation sequencing (NGS) in combination with phage surface display (PSD) are powerful tools in the newly equipped molecular biology toolbox for the identification of specific target binding biomolecules. Application of PSD led to the discovery of manifold ligands in clinical and material research. However, limitations of traditional phage display hinder the identification process. Growth-based library biases and target-unrelated peptides often result in the dominance of parasitic sequences and the collapse of library diversity. This study describes the effective enrichment of specific peptide motifs potentially binding to arsenic as proof-of-concept using the combination of PSD and NGS. Arsenic is an environmental toxin, which is applied in various semiconductors as gallium arsenide and selective recovery of this element is crucial for recycling and remediation. The development of biomolecules as specific arsenic-binding sorbents is a new approach for its recovery. Usage of NGS for all biopanning fractions allowed for evaluation of motif enrichment, in-depth insight into the selection process and the discrimination of biopanning artefacts, e.g., the amplification-induced library-wide reduction in hydrophobic amino acid proportion. Application of bioinformatics tools led to the identification of an SxHS and a carboxy-terminal QxQ motif, which are potentially involved in the binding of arsenic. To the best of our knowledge, this is the first report of PSD combined with NGS of all relevant biopanning fractions.

A detection system based on a microchannel plate with a delay line readout structure has been developed to perform scanning transmission ion microscopy (STIM) in the helium ion microscope (HIM). This system is an improvement over other existing approaches since it combines the information of the scanning beam position on the sample with the position (scattering angle) and time of the transmission events. Various imaging modes such as bright and dark field or the direct image of the transmitted signal can be created by post-processing the collected STIM data. Furthermore, the detector has high spatial and time resolution, is sensitive to both ions and neutral particles over a wide energy range, and shows robustness against ion beam-induced damage. A special in-vacuum movable support gives the possibility of moving the detector vertically, placing the detector closer to the sample for the detection of high-angle scattering events, or moving it down to increase the angular resolution and distance for time-of-flight measurements. With this new system, we show composition-dependent contrast for amorphous materials and the contrast difference between small and high angle scattering signals. We also detect channeling related contrast on polycrystalline silicon, thallium chloride nanocrystals, and single crystalline silicon by comparing the signal transmitted at different directions for the same data set

We are daily exposed to a multitude of health hazardous airborne particulate matter with notable deposition in the fragile alveolar region of our lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modelling, we have here determined that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows us to predict the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modelling potentially relating outcomes to material properties for large number of materials thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, our work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.

In order to determine the magnesium level in a titanium reduction retort by inductive methods, many interfering influences have to be considered to achieve precise measurement results. By using a look-up-table method, the magnesium level can be identified while taking into account the interfering effects of titanium sponge rings that are forming at the walls of the retort during the reduction process with their unknown geometrical and electrical parameters. This new method uses a combination of numerical simulations and measurements, whereby the simulation model is calibrated so that it represents the experimental setup as closely as possible. Previously we have presented purely theoretical studies on this method. Here, we demonstrate the practical feasibility of that method by performing measurements on a model experiment. This method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.