Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Pristine diorite drill cores, obtained from the Äspö Hard Rock Laboratory (HRL, Sweden), were used to study the retention behavior of fresh, anoxic crystalline rock material towards the redox-sensitive uranium. Batch sorption experiments and spectroscopic methods were applied for this study. The impact of various parameters, such as solid-to-liquid ratio (2 to 200 g/L), grain size (0.063 – 0.2 mm, 0.5 – 1 mm, 1 – 2 mm), temperature (room temperature and 10 °C), contact time (5 to 108 days), initial U(VI) concentration (3x10^-9 to 6x10^-5 M), and background electrolyte (synthetic Äspö groundwater and 0.1 M NaClO₄) on the U(VI) sorption onto anoxic diorite was studied under anoxic conditions (N₂). Comparatively, U(VI) sorption onto oxidized diorite material was studied under ambient atmosphere (pCO₂ = 10^-3.5 atm). Conventional distribution coefficients, K_d, and surface area normalized distribution coefficients, K_a, were determined. The K_d value for the U(VI) sorption onto anoxic diorite in Äspö groundwater under anoxic conditions by investigating the sorption isotherm amounts to 3.8 ± 0.6 L/kg which corresponds to K_a = 0.0030 ± 0.0005 cm (grain size 1 – 2 mm). This indicates a weak U sorption onto diorite which can be attributed to the occurrence of the neutral complex Ca₂UO₂(CO₃)₃(aq) in solution. This complex was verified as predominating U species in synthetic Äspö groundwater by time-resolved laser-induced fluorescence spectroscopy (TRLFS). Compared to U sorption at room temperature under anoxic conditions, U sorption is further reduced at decreased temperature (10 °C) and under ambient atmosphere. The U species in aqueous solution as well as sorbed on diorite were studied by in situ time-resolved attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy. A predominant sorbing species containing a UO₂(CO₃)₃ ^4- moiety was identified. The extent of U sorption onto diorite was found to depend more on the low sorption affinity of the Ca₂UO₂(CO₃)₃(aq) complex than on reduction processes of uranium.

The development of new two-phase flow CFD models is an important goal for industry and research. Such new CFD models have to be validated with suitable experimental quantitative data with high spatial and temporal resolution. Such data are generated by wide experimental series at the vertical titanium pipe test section of the TOPFLOW test facility. Using ultrafast X-ray tomography, air-water and steam-water experiments at co-current upward and downward flows were performed as soon as counter current flows. These generated data were segmentated and analyzed with in-house codes into quantitative data like gas hold ups, velocity profiles, bubble size distributions or interfacial area densities.
In this publication, different methods for determining bubble velocities are presented. The results are discussed as soon as compared.

This paper describes key open issues which are being debated nowadays by experts in the field, and for which clarification is essential for a safe operation of the nuclear power plants during life extension. Notably: late blooming effects in low Cu steels; effects of Cu, Ni, Mn, and P on the irradiated microstructure and on hardening and embrittlement; use of material test reactor data for assessment in power reactors (including flux and spectrum effects); Master Curve versus Unified Curve and fracture toughness behavior of highly irradiated material; embrittlement in RPV zones out of the traditional beltline (“the expanding beltline”); embrittlement trend curves at high neutron fluence, where data are scarce; re-embrittlement after annealing.

This paper presents guidelines to monitor radiation embrittlement of reactor pressure vessels (RPV) during life extension periods (to 60 or 80 years) or for the long term operation of nuclear power plants (NPP). The guidelines were developed in 2012-2013 by a Task Group of the international project LONGLIFE. The work performed responds to the need of guidance to treat long term irradiation effects within the ageing management of NPPs, since the standard RPV surveillance programmes were designed only to cover a time period of 40 years. The guidelines intend to support specialists in the field and managers in the plant to choose among the most adequate techniques and methods available today to extend the use of their current RPV surveillance programme beyond design life, or implement a new programme when needed. The study performed identifies weaknesses of the standard surveillance programmes in providing data needed for long term operation, and proposes solutions and tools to solve and/or mitigate the lack or scarcity of surveillance material for their use in life extension. Guidance is also given on methods and strategies to generate reliable surveillance data in the high fluence range.

Cadmium telluride (CT) and Zn-doped (similar to 4 at%) CT (CZT) crystals grown by the Bridgman method were mechanically polished to achieve mirror-like surfaces and subsequently irradiated with medium-energy (30-200 keV) Ar+ ions under oblique incidence (60 degrees with respect to the target normal). Atomic force microscopy shows that ion sputtering induces the formation of self-organized ripple nanopatterns with wavevector parallel to the ion beam projection on the surface on both CT and CZT targets. The ripple wavelength and amplitude (surface roughness) increase with ion energy. Even with such low doping level, the pattern formation dynamics differs between both materials and, in general, CZT surfaces roughen more easily than CT. In addition, an orthogonal ripple mode develops for extended irradiation, which is more prominent in CZT crystals. Spectroscopic ellipsometry reveals that the C(Z) T crystals have a high radiation hardness since ion bombardment does not induce an amorphized surface layer. This fact also implies that the nanostructured surfaces have significant photoluminescence response, one to two orders of magnitude larger than from as-prepared crystals. These results show that large-area (similar to cm(2)) surface nanostructuring by ion beams can be implemented in the fabrication of future C(Z) T-based devices.

In order to increase the polarity of the potent CB₂ ligand 1a, the homologous hydroxyalkyl carbazoles 2a–c were prepared and pharmacologically evaluated. An important step in the synthesis is the hydroxyalkylation of carbazole with cyclic sulfates providing the 2-hydroxyethyl and 3-hydroxypropyl derivatives 5a and 5b in a one-step reaction. The final propionamides 2a–c were prepared using the recently reported coupling reagent COMU1. The X-ray crystal structure of 2c displays an almost coplanar arrangement of the 3-phenyl-1,2,4-oxadiazole biaryl system. The increased polarity of 2a is associated with an almost 100-fold reduced CB₂ affinity. The 3-hydroxypropyl derivative 2b represents the best compromise between lipophilicity and CB₂ affinity (K_i=33 nM).

We have measured the elastic constant (C ₁₁-C ₁₂)/2 in URu₂Si₂ by means of high-frequency ultrasonic measurements in pulsed magnetic fields H ║ [001] up to 61.8 T in a wide temperature range from 1.5 to 116 K. We found a reduction of (C ₁₁-C ₁₂)/2 that appears only in the temperature and magnetic field region in which URu₂Si₂ exhibits a heavy-electron state and hidden order. This change in (C ₁₁-C ₁₂)/2 appears to be a response of the 5f electrons to an orthorhombic and volume conservative strain field ε_xx -ε_yy with Γ₃ symmetry. This lattice instability is likely related to a symmetry-breaking band instability that arises due to the hybridization of the localized f electrons with the conduction electrons and is probably linked to the hidden-order parameter of this compound.

We present a comprehensive macroscopic thermodynamic study of the quasi-one-dimensional (1D) s =½ frustrated spin-chain system linarite. Susceptibility, magnetization, specific heat, magnetocaloric effect, magnetostriction, and thermal-expansion measurements were performed to characterize the magnetic phase diagram. In particular, for magnetic fields along the b axis five different magnetic regions have been detected, some of them exhibiting short-range-order effects. The experimental magnetic entropy and magnetization are compared to a theoretical modeling of these quantities using density matrix renormalization group (DMRG) and transfer matrix renormalization group (TMRG) approaches.Within the framework of a purely 1D isotropic model Hamiltonian, only a qualitative agreement between theory and the experimental data can be achieved. Instead, it is demonstrated that a significant symmetric anisotropic exchange of about 10% is necessary to account for the basic experimental observations, including the three-dimensional (3D) saturation field, and which in turn might stabilize a triatic (three-magnon) multipolar phase.

Ziel/Aim:

Phosphodiesterasen (PDE´s) sind Enzyme, die in allen menschlichen Zellen exprimiert werden und die zyklischen Nucleotide cAMP und/oder cGMP hydrolysieren. PDE-Inhibitoren verzögern den Abbau dieser sekundären Botenstoffe und beeinflussen physiologische Prozesse. Die PDE2A zeigt eine hohe, spezifische Expression im Gehirn sowie in bestimmten Tumoren und ist vermutlich an der Pathophysiologie entsprechender Erkrankungen beteiligt. Ziel unserer Arbeiten ist die Darstellung eines radiomarkierten PDE2A-Inhibitors für die Bildgebung der PDE2A mittels PET.

Methodik/Methods:

Ausgehend von einer Triazin-Leitstruktur (1) wurden ein neues Fluorpropyl-Derivat* als Referenzverbindung für Affinitätsstudien sowie der entsprechende Tosylat-Präkursor für eine einstufige F-18-Markierung entwickelt. Die nukleophile F-18-Fluorierung erfolgte in Acetonitril bei 80°C in 15 Minuten. Der Radioligand wurde mittels semi-präparativer HPLC isoliert, über eine RP18 light SPE-Kartusche gereinigt und in 0,9%iger NaCl-Lösung formuliert. Die Analytik des Endproduktes erfolgte mittels Radio-DC und Radio-HPLC.
* 9-(2-Fluor-5-(3-fluorpropoxy)phenyl)-2-methoxy-7-methylimidazo[5,1-c]pyrido[2,3-e][1,2,4]triazin

Ergebnisse/Results:

Die Leitstruktur (IC50: 4,12 nM**), das neue Fluorpropyl-Derivat (IC50: 11,4 nM**) und der Tosylat-Präkursor wurden mit einer Gesamtsyntheseausbeute von je 70 - 80% erhalten. Der Radioligand wurde mit einer Markierungsausbeute von 75,4 ± 4,9% (n = 5), einer radiochemischen Ausbeute von ~ 57% (n = 2), einer spezifischen Aktivität von ~ 54 GBq/µmol (n = 2) und einer radiochemischen Reinheit von ≥ 99,5% erfolgreich synthetisiert.
** Enzymassay (1)

Schlussfolgerungen/Conclusions:

Die bisherigen Ergebnisse zeigen, dass ein neuartiger F-18-markierter und hochaffiner PDE2A-Radioligand erfolgreich dargestellt werden kann. Die Charakterisierung dieses neuen F-18-Propyl-Derivates wird mittels TierPET/MR und Untersuchungen zur Metabolisierung sowie Autoradiographie erfolgen.

Literatur/References:

(1) Patent WO2010/054253 A1

In this paper, we present the investigation of the axial and radial magnetic-field distribution inside and outside of the bore of a nondestructive pulsed-field coil presently installed at the Dresden High Magnetic Field Laboratory (HLD). The array used for these magnetic-field measurements was made up of three CMR-B-scalar sensors based on nanostructured La-Sr-Mn-O films. The investigations were performed at a temperature of 270 K and at a peak field of 46 T. The experimental results fit well with calculations obtained using ANSYS code based on the finite element method (FEM). It is concluded that the CMR-B-scalar sensors can be successfully used for the investigation of the magnetic-field distribution in pulsed high magnetic field coils.

A generalized model for bubble coalescence and breakup has been developed, which is based on a comprehensive survey of existing theories and models. One important feature of the model is that all important mechanisms leading to bubble coalescence and breakup in a turbulent gas-liquid flow are considered. The new model is tested extensively in a 1D Test Solver and a 3D CFD code ANSYS CFX for the case of vertical gas-liquid pipe flow under adiabatic conditions, respectively. Two kinds of extensions of the standard multi-fluid model, i.e. the discrete population model and the inhomogeneous MUSIG (multiple-size group) model, are available in the two solvers, respectively. These extensions with suitable closure models such as those for coalescence and breakup are able to predict the evolution of bubble size distribution in dispersed flows and to overcome the mono-dispersed flow limitation of the standard multi-fluid model.
For the validation of the model the high quality database of the TOPFLOW L12 experiments for air-water flow in a vertical pipe was employed. A wide range of test points, which cover the bubbly flow, turbulent-churn flow as well as the transition regime, is involved in the simulations. The comparison between the simulated results such as bubble size distribution, gas velocity and volume fraction and the measured ones indicates a generally good agreement for all selected test points. As the superficial gas velocity increases, bubble size distribution evolves via coalescence dominant regimes first, then breakup-dominant regimes and finally turns into a bimodal distribution. The tendency of the evolution is well reproduced by the model. However, the tendency is almost always overestimated, i.e. too much coalescence in the coalescence dominant case while too much breakup in breakup dominant ones. The reason of this problem is discussed by studying the contribution of each coalescence and breakup mechanism at different test points. The redistribution of the gaseous phase from the injection position at the pipe wall to the whole cross section is overpredicted by the Test Solver especially for the test points with high superficial gas velocity. Besides the models for bubble forces, the simplification of the Test Solver to a 1D model has an influence on the redistribution process. Simulations performed using CFX show that a considerable improvement is achieved with comparison to the results delivered by the standard closure models. For the breakup-dominant cases, the breakup rate is again overestimated and the contribution of wake entrainment of large bubbles is underestimated. Furthermore, inlet conditions for the liquid phase, bubble forces as well as turbulence modeling are shown to have a noticeable influence, especially on the redistribution of the gaseous phase.

Theoretically, exploitation of an ore deposit could be optimized by adapting the beneficiation processes to the properties of each individual ore block being extracted. Such an adaptation can involve switching on and off certain processes, or setting their controlling parameters. These decisions depend typically on physical and chemical attributes. Physical parameters are relevant both at macroscopic and microscopic scale, whereas chemical attributes include both the concentration of the value element, and the presence and abundance of penalty elements. As a first step towards adaptive processing, this contribution explores mapping those adaptive decisions which are based on the composition in value and penalty elements of the selective mining unit or mining block.

Cokriging and geostatistical simulation are reasonable tools to provide information about the concentration of these elements, both in expected value and uncertainty. However, when the sum of total penalty and value elements approaches 100%, it is mandatory that geostatistical results do not exceed that sum. Moreover, some processing techniques work by applying a filter to the composition of material that is being processed, so that their partial output concentration can be taken as a known portion of their input concentration. In such a context, the use of geostatistics on the raw data will deliver inconsistent results, which can be avoided via log-ratio methods: a one-to-one log-ratio transformation is applied to the raw data, followed by modelling via classical multivariate geostatistical tools, and subsequent back-transform of predictions and simulations. Results satisfy the constant sum constraints by construction, even in simulations. Furthermore, filtering processes behave linearly if expressed in terms of log-ratios.

To illustrate the approach, a toy example is used, where a 4-component system (consisting of a value element, two penalty elements and some liberable material, each representing a material type or a set of minerals) is beneficiated through a chain of technical processes. A sequence of milling, desliming and flotation is applied to separate most of the value element, and the product is classified in three qualities. Knowing all processing costs and selling prices, a compositional geostatistical simulation framework can be run to map the best processing choices and qualities as a function of the available measurements of the percentages of the four components, instead of mapping these percentages themselves. In doing so, the uncertainty about gains can be quantified at the same time.

We have performed measurements of the turbulent mixing in the upper plenum of the ROCOM test facility sometimes ago (Grunwald et al., 2003). Since the data reflects the phenomenon very clearly, we are convinced that the results of the experiments can be used for the code validation with regard to the described effect.

Fracture toughness of the multi-layer beltline welding seam of the Biblis C reactor pressure vessel was characterized by the test standard ASTM E1921. The reference temperature, T0, was determined for different thickness positions of the multi-layer welding seam. Additionally, the influence of the specimen orientation on T0 was investigated. In contrast to the T-S orientation (crack extension through the thickness) the crack front of the T-L oriented specimens (crack extension in welding direction) penetrates several welding beads. By means of fractographic and metallographic analyses it was shown that the distribution of the crack initiation sites is not necessarily correlated to the structure of the different welding beads along the crack front. Furthermore, it was found that the scatter of the KJc values determined with T-S specimens is significantly higher than in case of the T-L specimens. T0 values measured at different thickness locations of the multi-layer welding seam vary in a range of about 40 K.

The department of Neuroradiopharmaceuticals is part of the Helmholtz-Zentrum Dresden-Rossendorf and deals with the development of radiotracers for brain research using positron emission tomography (PET).
Those tracers are ligands labelled with radioactive isotopes which bind to selected biomolecules in brain. Due to this specific binding it is possible to visualise neurotransmission processes in living organisms. For the development of such ligands it is necessary to synthesise various organic compounds and to determine their in-vitro binding affinity to the desired biological target. Afterwards, a promising candidate is selected for labelling with a short-lived radioactive nuclide such as fluorine-18.
The vesicular acetylcholine transporter (VAChT) is located in cholinergic areas in brain and is an interesting target for the in-vivo imaging of neuronal deficits as observed in Alzheimer’s disease. It is known that vesamicol (2-(4-phenylpiperidin-1-yl)cyclohexanol) acts as a high-potential inhibitor for this transporter and thus represents the chemical lead for the development of VAChT-radioligands. The aim of our studies is to develop a selective ligand by varying the vesamicol-skeleton in a systematic manner at its’ three ring structures and determining the binding profile of the resulting derivatives. These in-vitro data are correlated with the various chemical structures leading to a three dimensional computational model, a so-called quantitative structure affinity relationship (QSAR). Based on those results, we will be able to find a promising candidate for radiolabelling studies and further investigations.

Phosphodiesterasen (PDE´s) sind Enzyme, die in allen menschlichen Zellen exprimiert werden und die zyklischen Nucleotide cAMP und/oder cGMP hydrolysieren. PDE-Inhibitoren verzögern den Abbau dieser sekundären Botenstoffe und beeinflussen physiologische Prozesse. Die PDE2A zeigt eine hohe, spezifische Expression im Gehirn sowie in bestimmten Tumoren und ist vermutlich an der Pathophysiologie entsprechender Erkrankungen beteiligt. Ziel unserer Arbeiten ist die Darstellung eines radiomarkierten PDE2A-Inhibitors für die Bildgebung der PDE2A mittels Positronen-Emissions-Tomographie (PET).
Auf Grundlage des Patents WO2010/054253 A1 wurde eine für die PDE2A hochaffine und selektive Triazin-Leitstruktur (TA-05, IC50: 4,12 nM) ausgewählt. Diese Leitstruktur wurde in einer fünfstufigen, optimierten Syntheseroute dargestellt und vollständig charakterisiert. Ausgehend von TA-05 wurden ein neues Fluorpropyl-Derivat (TA-P2) als Referenzverbindung für Affinitätsstudien sowie der entsprechende Tosylat-Präkursor (TA-P4) für eine einstufige ¹⁸F-Markierung entwickelt. Die nukleophile ¹⁸F-Fluorierung von TA-P4 führte zu einem neuen, hochaffinen PDE2A-Radioliganden (¹⁸F-TA-P2), der erfolgreich isoliert, gereinigt und mittels Radio-DC sowie Radio-HPLC analysiert wurde. Die biologische Charakterisierung von ¹⁸F-TA-P2 wird derzeit mittels TierPET/MR und Untersuchungen zur Metabolisierung sowie Autoradiographie bearbeitet.

The controlled positioning of DNA nanostructures on technologically-relevant surfaces represents a major goal along the route toward the full-scale integration of DNA-based materials into nanoelectronic and sensoric devices. Previous attempts to arrange DNA nanostructures into defined arrays mostly relied on top-down lithographic patterning techniques combined with chemical surface functionalization. Here we combine two bottom-up techniques for nanostructure fabrication, i.e., self-organized nanopattern formation and DNA origami self-assembly, in order to demonstrate the electrostatic self-alignment of DNA nanotubes on topographically patterned silicon surfaces. Self-organized nanoscale ripple patterns with periodicities ranging from 20 nm to 50 nm are fabricated by low-energy ion irradiation and serve as substrates for DNA origami adsorption. Electrostatic interactions with the charged surface oxide during adsorption direct the DNA origami nanotubes to the ripple valleys and align them parallel to the ripples. By optimizing the pattern dimensions and the Debye length of the adsorption buffer, we obtain an alignment yield of ~ 70 %. Since this novel and versatile approach does not rely on any chemical functionalization of the surface or the DNA nanotubes, it can be applied to virtually any substrate material and any top-down or bottom-up nanopatterning technique. This technique thus may enable the wafer-scale fabrication of ordered arrays of functional DNA-based nanowires.

Um die Versorgung mit metallischen Rohstoffen für Deutschland zukünftig nachhaltig zu sichern, hat das BMBF im Jahr 2012 die r3-Fördermaßnahme mit dem Fokus auf strategische Metalle und Mineralien ins Leben gerufen. Die nichtenergetischen Rohstoffe sind von zunehmender Wichtigkeit für die internationale Wettbewerbsfähigkeit der deutschen Wirtschaft. Die Versorgungssicherheit dieser Rohstoffe nimmt jedoch in den letzten Jahren stark ab, da zum Einen der Bedarf an beispielsweise Hightech-Metallen steigt wodurch Verknappungen am Markt drohen und zum Anderen ist Deutschland im hohen Maße von Importen aus dem Ausland abhängig. Sekundärrohstoffe sind hingegen in Deutschland vorhanden, werden aber derzeit hinsichtlich Hightech-Metalle nicht ausgeschöpft.
Aus diesen Gründen setzt sich die Bundesregierung mit der Hightech-Strategie 2020 (2010a) und der Rohstoffstrategie (2010b) dafür ein, neue Technologien und innovative Verfahren mit dem Ziel des effizienten Umgangs mit diesen Rohstoffen zu entwickeln.
Ein zentraler Leitgedanke der Hightech-Strategie 2020 ist, die Wettbewerbsfähigkeit in Deutschland durch eine erhöhte Innovationskraft zu stärken. Dafür fördert das Bundesministerium für Bildung Forschung innerhalb des Rahmenprogrammes „Forschung für nachhaltige Entwicklung“ die Fördermaßnahme r³ mit 30 Millionen €. Die Fördermaßnahme „r³ – Innovative Technologie für Ressourceneffizienz – Strategische Metalle und Mineralien“ umfasst insgesamt 28 Verbundforschungsprojekte, die mit max. drei Jahren Laufzeit zwischen 2012 und Anfang 2016 auf den Themenfeldern Recycling, Einsparung und Substitution, städtischer Bergbau (Urban Mining) und Bewertungsmethoden forschen. Insgesamt umfasst r³ mehr als 128 Einzelprojekte, davon 69 Industrieprojekte. So wird die Förderung durch BMBF von 30 Millionen € durch den zusätzlichen Eigenanteil der Industrieunternehmen von 12 Millionen € auf insgesamt 42 Millionen € erhöht.

A systematic structural analysis of of FePt, CuAu and Au icosahedral nanoparticles is presented. The uncovered particles are prepared by inert gas condensation and thermally equilibrated through in-flight optical annealing. Aberration-corrected high resolution Transmission electron microscopy reveals that the crystal lattice is significantly expanded near the particle surface. These experimental findings are corroborated by molecular statics simulations which show that this near-surface strain originates from both intrinsic strain due to the icosahedral structure and a partial segregation of the larger of the two alloy constituents to the particle surface.

In this paper, we propose a new approach using structural information of spectral data during a preprocessing procedure to upgrade the ability of subsequent analysis methods. A composite data set of measured spectra is given, which contains dierent mixtures of a few spectral components. Using chemical knowledge and a small subset of the mixture information, we are able to evaluate these spectral components out of the given data set and use this information in addition for the following analysis of the composite data set. In our case, we apply the Self-Organizing Map according to Kohonen to predict the unknown mixture subset of the dierent spectral components within the measured data.

A magnetization study of a Tm₂Fe₁₇ single crystal and aligned powder of the deuteride Tm₂Fe₁₇D_3.2 has been carried out in steady (14 T) and pulsed (60 T and, in one case, up to 74 T) magnetic fields at temperatures between 1.5 and 300 K. Tm₂Fe₁₇ is a ferrimagnet with T_C = 295 K and a spontaneous moment of 22 μ_B /f.u. at T = 4.2 K. Of particular interest are low-temperature magnetization curves along the sixfold crystal axis c, which is an easy direction in Tm₂Fe₁₇ and a hard direction in the deuteride. In either case the magnetization increases with magnetic field undulatorily in broad steps whose height is a multiple of the atomic moment of Tm, μ _Tm = 7 μ_B . In Tm₂Fe₁₇, the positions of the steps yield information on the Fe-Tm molecular field, 48 T on the Tm 2d site and 60 T on the Tm 2b site, whereas the crystal field parameter A₆₆ is found from the widths of the steps: A₆₆(b) = −35 Ka ₀ ⁻⁶ and A₆₆(d) = −26 Ka ₀ ⁻⁶ (here a ₀ is the Bohr radius). It also proves possible to estimate the other sixth-order crystal field parameter: A₆₀ ∼ −4 Ka ₀ ⁻⁶ (on average for both sites). Less information can be extracted from the powder data for the deuteride. Thus, the mean molecular field on Tm in Tm₂Fe₁₇D_3.2 is found to be 49 T or 9% less than in the parent binary compound.

This report is a comparative review of several particle transport experiments, which were performed within the framework of the two large scale European projects namely THINS (Thermal Hydraulics of Innovative Nuclear Systems) and ARCHER (Advanced Reactor for Cogeneration of Heat & Electricity R&d). Background motivation is the carbonaceous dust issue of the High Temperature Reactor (HTR). Radio-contaminated dust was found deposited all over the inner surfaces in the primary circuit of different HTR research reactors after a certain operational time. In case of an accidental scenario such as the depressurisation of the primary circuit the dust may be remobilised by the turbulent flow and becomes a considerable source term when escaping the system boundaries. The safety assessment requires a fundamental understanding of the interaction between the wall-deposited particle multilayer and the turbulent flow field. Thus, we performed a set of experiments to explore the particle deposition and resuspension characteristics in various geometries by means of high-end measurement instrumentation.
Two air-driven small-scale test facilities were designed to generate a particle laden turbulent flow field under well-defined conditions. The flow was downscaled using Reynolds similarity and the aerosol particles were described by its aerodynamic mobility. The first facility was designed for the THINS project and is called Gas Particle Loop. Here, the particle deposition and resuspension was studied in a horizontal turbulent duct flow. The flow field was captured by means of a stereoscopic Particle Image Velocimetry system. The airborne particles were classified using Aerodynamic Particle Sizer spectrometry and the wall deposited particles were captured by means of optical microscopy and laser distance sensors. It was found that the deposition of micron-sized particles mainly depends on the aerodynamic particle size and the fluid friction velocity. Particle resuspension was found to take place in intermittent events once a critical friction velocity was exceeded. The second facility was constructed for the ARCHER project and is called Pebble Bed Loop. Here, a particle laden turbulent flow in a pebble bed was generated. The aerosol particles were radio-labelled with the isotope fluorine 18 and the spatiotemporal distribution of the particle deposits in the pebble bed was recorded by means of positron emission tomography (PET) during various flow regimes. Assuming a homogeneous distribution of the initial activity over the particles, the activity recorded by the PET scanner directly correlates to the amount of deposited particles. The geometry of the pebble bed was captured by means of a gamma ray computed tomography (CT) scan. The result of this campaign is a time resolved 3D PET-CET overlay. Basic characteristics of the particle deposition and resuspension behaviour in the GPLoop were relocated in the results of the experiments in the PBLoop. The available data set provides a new insight into the particle transport behaviour in turbulent flows and may be used for the development of numerical methods for the prediction of the dust behaviour during accidental scenarios of HTRs.

The tetragonal compound TbCoGa₅ exhibits two successive magnetic transitions at T _N1 = 36.2 and T _N2 = 5.4 K. The results of the measurement of the magnetic susceptibility and specific heat indicate that the c- and ab-components of the magnetic moments of Tb³⁺ show independent antiferromagnetic orderings at T _N1 and T _N2, respectively. In this work, we have investigated the physical properties of TbCoGa₅ in a magnetic field. Single crystals of TbCoGa₅ were grown and their specific heat, electrical resistivity, magnetization and elastic constant were measured. The magnetic exchange interactions in TbCoGa₅ are discussed referring to the result of the magnetization process. Additionally, the present and previous results are summarized in a magnetic phase diagram. The magnetic phase diagram indicates that the behavior of T _N1 in a changing magnetic field is similar to that of an Ising spin system, and the behavior of T _N2 is similar to that of an XY spin system. Thus, we conclude that Ising and XY spin systems coexist on a single Tb atom in TbCoGa₅.

This report describes the application of gamma-ray computed tomography (CT) and positron emission tomography (PET) for the investigation of particle transport in a model of a High Temperature Reactor (HTR) pebble bed. Micron sized liquid and graphite particles were radioactively labelled and the deposition and resuspension of particle multilayers in the pebble bed was studied. The particle laden turbulent flow in a model pebble bed was scaled by Reynolds similarity and was generated by an air driven small-scale test facility at ambient conditions. The pebble bed geometry was recorded by a CT to determine the bed porosity and pebble orientation. Two sets of experiments were performed. Firstly, radio-labelled liquid particles were dispersed into the flow to study pure particle deposition over a wide fluid velocity range. In a second set of experiments, radio-labelled graphite particles were injected into the flow and particle deposition and resuspension was studied in succession. Activity spots appeared on the front sides of the single pebbles indicating the formation of particle multilayers on the pebble surfaces. After the deposition experiment, the aerosol generator was switched off and the fan speed was stepwise increased to induce particle resuspension. A time resolved 3D PET-CT overlay provides a completely new insight into the particle multilayer formation and removal.

Magnetism in SmPd₂Al₃ was investigated on a single crystal by magnetometry and neutron diffraction. SmPd₂Al₃ represents a distinctive example of a Sm magnetism exhibiting complex magnetic behavior at low temperatures with four consecutive magnetic phase transitions at 3.4, 3.9, 4.4, and 12.5 K. The rich magnetic phase diagram of this compound reflects the specific features of the Sm³⁺ ion, namely, the energy nearness of the ground-state multiplet J = 5/2 and the first excited multiplet J = 7/2 in conjunction with strong crystal field influence. Consequently, a significantly reduced Sm magnetic moment in comparison with the theoretical Sm³⁺ free-ion value is observed. Despite the strong neutron absorption by natural samarium and the small Sm magnetic moment (∼0.2 μ _B), we have successfully determined the magnetic k vector (1/3, 1/3, 0) of the phase existing in the temperature interval 12.5–4.4 K. This observation classifies the SmPd₂Al₃ compound as a magnetically frustrated system. The complex magnetic behavior of this material is further illustrated by kinetic effects of the magnetization, inducing a rather complicated magnetic structure with various metastable states.

The resuspension of spherical single particles from a hydraulically smooth wall into a turbulent flow is studied. Special attention is given to the particle diameter, the material composition, the critical friction velocity and the inceptive motion of the resuspending particles. The experiments were performed in an air-driven small-scale test facility. The particles on the channel floor were detected and classified by means of an optical microscope combined with a digital camera. Furthermore, the turbulent flow field was recorded using a conventional Particle Image Velocimetry (PIV) system. A statistical sufficient monolayer of spherical particles was generated on the channel floor by dispersing the particles into the flow during a pure deposition regime. Afterwards, particle resuspension was induced by the stepwise increase of the fluid velocity. The resuspension was quantified by the fraction of resuspended particles against the friction velocity for a diameter range between 3 and 45 µm. It was found that particles begin to resuspend when a critical friction velocity is exceeded. A decreasing tendency between the particle diameter and the critical friction velocity was found for particles in the present size range and the results are in good consistency to other investigations.

This report describes an experimental study about graphite particle multilayer deposition and resuspension between periodic steps in turbulent channel flows. Background motivation is the carbonaceous dust safety issue in the High Temperature Reactor. In the present study the particle deposition and resuspension scenarios were fluid dynamically downscaled and were reproduced under simplified conditions in an air-driven small-scale test facility. Periodic steps were placed in a square duct test section to induce a complex flow field characterized by flow separations, recirculation and reattachment zones.
The turbulent flow field was recorded by means of a stereo Particle Image Velocimetry system. Polydisperse graphite particles matching the size range of HTR dust were dispersed into the flow field during a pure deposition regime. The multilayer build up between the periodic steps was measured using a laser distance sensor coupled with a linear stage. The particle layer build up showed a linear tendency against time and the deposition velocities are in good agreement with similar investigations. After the deposition scenario the aerosol generator was switched off and the fan speed of the test facility was stepwise increased to initiate particle resuspension. It was found that the resuspension started to begin in the reattachment area between the steps. The entire multilayer was already removed by the flow at friction velocities at which single particle resuspension starts to begin. Furthermore, particle bed porosity determinations were performed by gravimetrical and x-ray methods to characterize the packing properties. The present results indicate similarities between the single and the multilayer particle deposition and resuspension process.

An orthorhombic DyMnO₃ single crystal has been studied in magnetic fields up to 14 T and between 3 K and room temperature. The field dependent ordering temperature of Dy moments is deduced. The paramagnetic Curie Weiss behavior is related mainly to the Dy³⁺ sublattice whereas the Mn sublattice contribution plays a secondary role. DC magnetization measurements show marked anisotropic features, related to the anisotropic structure of acubic system stretched along a body diagonal, with a magnetic easy axis parallel to the crystallographic b axis. A temperature and field dependent spin flop transition is observed below 9 K, when relatively weak magnetocrystalline anisotropy is overcome by magnetic fields upto 1.6 T.

This work describes an experimental study about the transport behavior of carbonaceous dust in a High Temperature Reactor (HTR) pebble bed. Carbonaceous dust may be formed during reactor operation and deposits on the inner surfaces of the HTR primary circuit. In case of a loss of coolant accident (LOCA) this dust may be resuspended and released into the environment. Since the dust is a carrier of fission products this dust is a considerable source term and has to be analyzed with respect to such accidental scenarios.
The particle deposition and resuspension behavior was experimentally investigated in a pebble bed by means of Positron Emission Tomography (PET). The turbulent flow field was generated by an air-driven small scale test facility. The pebble bed was fluid mechanically downscaled by the pebble bed related Reynolds number. The pebble bed geometry was analyzed by a 3D gamma ray computed tomography scan for the precise determination of the pebble orientation and the bed porosity.
Two sets of PET experiments were conducted. First, monodisperse liquid aerosol particles were labeled with the radioisotope (18F) and dispersed into the turbulent flow field. PET was used for the temporal and spatial recording of the particle deposition process.
In the second set of PET measurements, the liquid particles were replaced by technical graphite dust matching the particle size distribution usually found in the HTR primary circuit. The graphite dust was also labeled with 18F before being dispersed into the turbulent flow field. Deposition experiments were conducted at rather low fluid velocities to purely study the particle precipitation. Subsequently, the fan power of the facility was stepwise increased and the PET scanner recorded the particle resuspension process online. The existing data sets give a unique 3D and time resolved insight into the particle transport process in such a complex geometry. The data can be further used for CFD code development to predict the particle behavior during a LOCA in an HTR.

DNA nanotechnology holds great promise for the fabrication of novel plasmonic nanostructures and the potential to carry out single-molecule measurements using optical spectroscopy. Here, we demonstrate for the first time that DNA origami nanostructures can be exploited as substrates for surface-enhanced Raman scattering (SERS). Gold nanoparticles (AuNPs) have been arranged into dimers to create intense Raman scattering hot spots in the interparticle gaps. 15 nm AuNPs covered with TAMRA-modified DNA have been placed at a nominal distance of 25 nm to demonstrate the formation of Raman hot spots. To control the plasmonic coupling between the nanoparticles and thus the field enhancement in the hotspot, the size of AuNPs has been varied from 5 nm to 28 nm by electroless Au deposition. By the precise positioning of a specific number of TAMRA molecules in these hot spots, surface-enhanced Raman scattering (SERS) with highest sensitivity down to the few-molecule level is obtained.

We present results of specific heat measurements on a Ce₃Pd₂₀Si₆ single crystal and construct the magnetic phase diagram for the three cubic principal directions [100], [110] and [111]. The highly anisotropic phase diagram is discussed and can be qualitatively explained by the Zeeman splitting at the 8c-site. For B ‖ [100], the present study found two different quadrupolar ordered phases, which meet the paramagnetic phase at a tri-critical point and establish the new phase boundaries.

In this work we report on systematic field-cooled magnetization experiments in melt-textured YBa₂Cu₃O_7−δ samples containing Y211 precipitates. Magnetic fields up to 14 T were applied either parallel or perpendicular to the ab planes and a strong paramagnetic response related to the superconducting state was observed. This effect is known as paramagnetic Meissner effect (PME). The magnitude of the PME increases when the field is augmented. This effect shows a strong paramagnetic relaxation, such that the paramagnetic moment increases as a function of the time. The pinning by the Y211 particles plays a crucial role in the explanation of this effect and our results suggest that the pinning capacity can produce a strong flux compression into the sample, originating the PME and the strong time dependence.

High field magnetization measurements up to 60 T on free powder samples from GdCo_12-xFe_xB₆ (x = 0-3) compounds are reported. The data were used to evaluate the microscopic exchange interaction integral, J_Gd-3d, between Gd and 3d (Co,Fe) spins. The systems are ferrimagnets; they order magnetically between T_C = 95 K for x = 3 and T_C = 165 K for x = 0. The low temperature magnetization curves as well as the temperature dependence of intrinsic magnetic parameters are determined by magnetic measurements in pulsed magnetic field. The average magnetic moment µ_Co+Fe per mean transition metal atom (Co + Fe) is small and increases with increasing Fe concentration from 0.44 µ _B for x = 0 to 0.51 µ_B for x = 3 at T = 4 K. From high field magnetization curves, a value of J_Gd-3d/k_B = -4.65 K is derived for x = 0, whereas mean field approximation yields a much larger 3d-3d exchange integral of J_Co-Co/k_B = 105 K. The obtained results reveal an increase of J_Gd-3d/k_B with Fe concentration. For x = 0.5, the intersublattice coefficient n_Gd-3d is found to keep an almost constant value of 5.87 ± 0.13 T*f.u.*µ_B ^-1 whatever the temperature in the 2 to 60 K range.

We have carried out low-temperature ultrasonic measurements using shear-mode ultrasound to clarify the quantum state of a vacancy orbital in boron-doped silicon grown by the floating zone (FZ) method. The elastic constants (C₁₁ - C₁₂)/2 and C₄₄ of the transverse mode exhibit considerable softening below 2 and 5 K down to the base temperature of 30 mK, respectively. The elastic constant C₄₄ measured by the three ultrasonic modes (k_x, u_y), (k_z, u_x), and (k_x, u_z) shows the different magnetic field dependences among the configurations under applied magnetic fields along the z-axis. The elastic softening and the magnetic field dependence of the elastic constants are accounted for by the quadrupole susceptibility based on the energy level scheme of the vacancy orbital with a Γ₈ quartet ground state and Γ₇ doublet excited state located at an energy of 1 K. The difference in C₄₄ between the two ultrasonic modes (k_z, u_x) and (k_x, u_z) at fields along the z-axis indicates that the Γ₈ quartet ground state is slightly split by local strain in the silicon sample. The quantum state of the vacancy orbital is expected to be sensitive to strain because of the extremely large quadrupole-strain coupling energy of g_Γ ≈ 10⁵ K due to the extensively spreading orbital radius of r ≈ 1 nm. The differences in variation of the low-temperature softening and magnetic field dependence among eight samples cut out from different locations of the present boron-doped FZ silicon ingot evidence the inhomogeneous distribution of the vacancy concentration.

Der Vortrag geht auf die Probleme des Ga-Recyclings aus Rückständen der GaAs-Wafererzeugung ein. Daraufhin werden ein gesamtheitliches Konzept für die Zusammenlegung der Abwässer sowie ein neu entwickeltes Dialyseverfahren zur weiteren Behandlung dieser vorgestellt. Aktuelle Ergebnisse zur dialytischen Trennung des Galliums von der Hauptverunreinigung Arsen werden ausführlich diskutiert und ein Ausblick auf weitere Untersuchungen gegeben.

The use of liquid metal batteries is considered as one promising option for electric grid stabilisation. While large versions of such batteries are preferred in view of the economies of scale, they are susceptible to various magnetohydrodynamic instabilities which imply a risk of short-circuiting the battery due to the triggered fluid flow. Here we focus on the current driven Tayler instability and give critical electrical currents for its onset as well as numerical estimates for the appearing flow structures and speeds. Scaling laws for different materials, battery sizes and geometries are found. We further discuss and compare various means for preventing the instability.

Silicic volcanic ash deposits investigated at 14 localities between 22° and 25°S in the Chilean Coastal Cordillera are found to be the distal ash fall from supereruptions in the Central Andean cordillera several hundreds of kilometers to the east. Depositional textures, modal composition and granulometry of the ashes and tuffs (the latter lithified by halite and gypsum under ultra-arid conditions) allow for a distinction between primary fallout/aeolian deposits (mean 4 - 5 Φ, sorting 1.5 - 2Φ) and secondary deposits that formed by down wash from hill slopes during local rain fall. Primary volcanic components comprise two types of glass shards (with small stretched vesicles and coarse-walled with rounded to elliptic vesicles), and biotite. Previously published studies on ash deposits in the north Chilean Coastal Cordillera reported 14 ⁴⁰Ar/³⁹Ar and K/Ar ages on biotite or sanidine ranging between 6.66 ± 0.13 and 0.6 ± 0.4 Ma. In this project, three ⁴⁰Ar/³⁹Ar ages on biotite have been determined for samples from the Cuenca del Tiburón, the northern margin of Salar de Navidad and from the Quebrada de la Chimba (3.9 ± 0.1 Ma, 4.1 ± 0.1 Ma, 6.0 ± 0.1 Ma, respectively). The range of the 17 ages coincides with the Late Miocene to Quaternary ages of the major ignimbrite-forming eruptions of the high Andes to the east such as the Altiplano Puna Volcanic Complex (APVC). Electron microprobe data of glass and biotite of the Coastal Cordillera ashes have been compared with data from major ignimbrites of the APVC, of other major Central Andean volcanic fields, and of marine ashes (ODP Leg 201). Additional new biotite microprobe data from three APVC ignimbrites (Pastos Grandes, Pujsa and Guacha) have been included in the present study. Biotite composition of the investigated Coastal Cordillera ashes is similar to those of ignimbrites from the APVC. In particular, based in Fe, Mg, Mn and Ti, distal equivalents of the 3.96 ± 0.08 Ma Atana and/or 4.09 ± 0.02 Ma Puripicar and of the 5.6 ± 0.2 Ma Pujsa and/or the 5.56 ± 0.01 Ma Guacha eruptions can be identified. In addition, based only on age relations, distal ash units of the Pastos Grandes, Tatio and Purico eruptions may be present in the Coastal Cordillera. Composition of glass is comparable to APVC ignimbrite matrix glass and to marine glass, however, significant alkali depletion and SiO₂ enrichment is attributed to in situ alteration. The identification of these ashes demonstrates for the first time that the supereruptions in the southern Central Andes gave rise to voluminous ash clouds, most likely co-ignimbrite. The present outcrops represent ash dispersed by easterly winds, consistent with atmospheric models that show favorable westward-directed winds existing in the upper troposphere/stratosphere during the southern summer in the southern Central Andes. This requires that current volume estimates for the major eruptions to be considered minima with a significant augmentation likely.

EBIS/T systems provide ions of intermediate up to the highest ion charge states via electron impact ionization by a dense electron beam. In order to produce highly charged ions in an EBIS/T high electron beam densities of several hundred A/cm2 are necessary to realize high ionization factors and compensate for charge destructive processes such as charge exchange etc. The required electron beam compression is realized via an axial magnetic field. Two different EBIS/T magnet design approaches have been established over the past decades: Superconducting magnets with high magnetic fields of several Tesla (significant initial and maintenance costs), Compact permanent magnets with magnetic fields of Sub-Tesla (low initial and maintenance costs). Comparing both solutions shows that the produced ion species and current output of the permanent magnet EBIS/T suits most of the user requirements.

Electron Beam Ion Sources (EBIS) were originally developed to produce highly charged ions (HCI) [1]. For this purpose, high density electron beams at electron beam energies higher than the ionization potential of the desired ion species are required leading to the development of high energy and high current devices working with superconducting magnet coils.
For applications with focus on low and intermediate charge states EBIS/T with high-energy density rare-earth permanent magnets are an economic and compact alternative [2-5]. EBIS/T setups for electron beam energies of 2 keV and below have become more interesting recently. They can be used as sources of electromagnetic radiation in the UV, EUV, and visible light region for calibration purposes, as reference source for emission and absorption spectroscopy with ions of intermediate charge states in astrophysical experiments, as ion sources for research in radiation biology and medicine, and for the diagnostics of plasmas in fusion devices in the low energy range.

Cyclotrons and first generation synchrotrons are the commonly applied accelerators in medical particle therapy nowadays. Next generation accelerators such as Rapid Cycling Medical Synchrotrons (RCMS), direct drive accelerators, or dielectric wall accelerators have the potential to improve the existing accelerator techniques in this field. Innovative accelerator concepts for medical particle therapy can benefit from ion sources which meet their special requirements. In the present paper we report on measurements with a superconducting Electron Beam Ion Source, the Dresden EBIS-SC, under the aspect of application in combination with RCMS as a well proven technology. The measurements indicate that this ion source can offer significant advantages for medical particle therapy. We show that a superconducting EBIS can deliver ion pulses of medically relevant ions such as protons, C4 + and C6 + ions with intensities and frequencies required for RCMS [S. Peggs and T. Satogata, “A survey of Hadron therapy accelerator technology,” in Proceedings of PAC07, BNL-79826- 2008-CP, Albuquerque, New Mexico, USA, 2007; A. Garonna, U. Amaldi et al., “Cyclinac medical accelerators using pulsed C6 +/ H+2 ion sources,” in Proceedings of EBIST 2010, Stockholm, Sweden, July 2010]. Ion extraction spectra as well as individual ion pulses have been measured. For example, we report on the generation of proton pulses with up to 3 × 109 protons per pulse and with frequencies of up to 1000 Hz at electron beam currents of 600 mA.

Experimental charge exchange and energy loss data for the transmission of slow highly charged Xe ions through ultra thin polymeric carbon membranes are presented. Surprisingly, two distinct exit charge state distributions accompanied by charge exchange dependent kinetic energy losses are observed. The energy loss for ions exhibiting large charge loss shows a quadratic dependency on the incident charge state, indicating that equilibrium stopping force values do not apply in this case. Additional angle resolved transmission measurements and reduction of the layer thickness due to a structural phase transition of the membrane lead to the conclusion that a charge state enhanced elastic scattering potential is the main reason for the increase in energy loss rather than charge state enhanced inelastic losses. Thus, the presented results connect scattering experiments of ions on gaseous and on solid targets.

For practical applications the Euler-Euler two-fluid model relies on suitable closure relations describing interfacial exchange processes. In dispersed gas-liquid multiphase flow, closures are needed for bubble forces, bubble-induced turbulence, as well as bubble-coalescence and -breakup. The quest for models with a broad range of applicability allowing predictive simulations is an ongoing venture. Reasonable success has been achieved so far for flows that are amenable to a monodisperse approximation for the bubble size which limits the latter to no more than a few mm.
In the present work we extend the validation to flow in which bubbles with a broad distribution of sizes up to ~10mm are present, but the shape of the distribution remains unchanged during the flow development. The existence of such conditions which we term “fixed polydispersity” is deduced from the experimental data. For this kind of situation the complexity of the closure problem is reduced since a balance between bubble-coalescence and -breakup prevails that allows to neglect these processes and simply impose a fixed bubble size distribution. Conclusions towards best practice guidelines for modeling bubbly flows are drawn and needs for further research identified.

The formation of Pu(IV)-oxo-nanoparticles from Pu(III) solutions by a surface- enhanced redox/polymerization reaction at the muscovite (001) basal plane is reported, with a continuous increase in plutonium coverage observed in situ over several hours. The sorbed Pu extends > 70 Å from the surface with a maximum concentration at 10.5 Å and a total coverage of >9 Pu atoms per unit cell area of muscovite (0.77 µg Pu/cm²) (determined independently by in situ resonant anomalous x-ray reflectivity and by ex situ alpha-spectrometry). The presence of discrete nanoparticles is confirmed by high resolution atomic force microscopy. We propose that the formation of these Pu(IV) nanoparticles from an otherwise stable Pu(III) solution can be explained by the combination of a highly concentrated interfacial Pu-ion species, the Pu(III) – Pu(IV) redox equilibrium, and the strong proclivity of tetravalent Pu to hydrolyze and form polymeric species. These results are the first direct observation of such behavior of plutonium on a naturally occurring mineral, providing insights into understanding the environmental transport of plutonium and other contaminants capable of similar redox/polymerization reactions.

Mineralische sowie insbesondere metallhaltige Rohstoffe sind für die Wertschöpfung aller hochentwickelten Volkswirtschaften von elementarer Bedeutung. Gleichzeitig entstammen diese Rohstoffe letztlich alle der Erdkruste – und damit einem Reservoir von endlicher Größe. Auch wenn die gesamte Größe dieses Reservoirs, auch Geopotenzial genannt, für keinen mineralischen oder metallhaltigen Rohstoff bisher ausgeschöpft wird, so werden die zur Verfügung stehenden Rohstoffkörper (Lagerstätten) zunehmend minderwertiger und teurer in ihrer Erschließung, ihrem Abbau und ihrer Verarbeitung.
Durch den technischen Fortschritt wird sich die Rohstoffabhängigkeit noch weiter verschärfen, wobei insbesondere der Bedarf an bislang technologisch wenig genutzten Metallen dramatisch steigen wird. Wurden in den 1980er-Jahren für die Herstellung eines Computerchips noch zwölf verschiedene Rohstoffe benötigt, sind es heute bis zu sechzig. Prognosen zufolge lassen technischer Wandel und Innovationen den Bedarf an Technologiemetallen wie Gallium (Ga), Neodym (Nd), Indium (In), Germanium (Ge), Scandium (Sc), Platin (Pt) oder Tantal (Ta) bis 2030 auf ein Vielfaches der heutigen Weltproduktionsmenge steigen (Angerer et al. 2009).
Nicht nur technischer Wandel und Innovationen katapultieren den internationalen Rohstoffbedarf nach oben. Auch die steigende Weltbevölkerung gerade in Entwicklungs- und Schwellenländern wie China und Indien oder die Wachstumssprünge in der Wirtschaftsleistung vieler dieser Länder beeinflussen den weltweiten Bedarf nach metallhaltigen Rohstoffen dramatisch. So ist schon jetzt klar, dass die Wirtschaftsmacht China ihren eigenen immens ansteigenden Rohstoffbedarf nicht nur aus eigenen, teilweise bereits heute schon nach außen hin reglementierten Rohstoffvorkommen decken kann, sondern bei weiter steigendem volkswirtschaftlichem Wachstum alle Kategorien mineralischer und metallischer Rohstoffe in zunehmendem Maße auch von außen zukaufen muss.
In letzter Instanz führen diese globalen Entwicklungen zu Lieferrestriktionen, sich verteuernden Rohstoffen und zu Rohstoffknappheit. Rohstoffe, deren Verfügbarkeit für Zukunftstechnologien gesichert werden muss, die eine große Hebelwirkung für die Wirtschaft haben und von denen bereits ein relativ geringer Mengeneinsatz damit zu einer hohen zusätzlichen Wertschöpfung in Hochtechnologiebereichen beiträgt, werden als „wirtschaftsstrategische“ Rohstoffe bezeichnet (BMBF 2012). Rohstoffe, deren Versorgungslage sich für die Wirtschaft mittel- bis langfristig als kritisch erweisen könnte, sind als „kritisch“ zu bezeichnen (ebd.), sodass die vorliegende Studie in Anlehnung an beide Definitionen von „wirtschaftskritischen Rohstoffen“ spricht. Was genau macht jedoch einige der bereits genannten Rohstoffe wirtschaftskritischer als andere, und wie kann auf unterschiedlichen gesellschaftlichen Ebenen mit dieser Rohstoffkritikalität umgegangen werden? Dieser Frage widmet sich die vorliegende Studie.

Experimental results for the Xe depletion in high burn-up fuel are presented from the High Burnup Rim Project (HBRP). In this project a number of UO2 fuel discs with 235U enrichment of 25.8 wt% were irradiated. The Xe content of the fuel discs was analysed by means of electron probe microanalysis (EPMA) with respect to burn-up and temperature. The influence of the burn-up and temperature on Xe concentration was investigated using a multi-physics approach involving various simulation tools. The temperature influence was modelled by the means of the temperature dependent effective burn-up. Good agreement was found between the modelled temperature threshold of the effective burn-up and the experimental temperature threshold between un- and restructured fuel in the HBRP. However, a systematic difference is observed between the onset burn-up derived from the Xe measurements in highly enriched discs such as those of HBRP and the corresponding values derived from irradiated Light Water Reactor (LWR) fuel rods and reported in the open literature. A sensitivity study identified the neutron flux spectrum and the fission product yields as main reasons for the observed differences.

This paper presents the methodology developed for the Serpent 2 Monte Carlo code for the calculation of adjoint-weighted reactor point kinetics parameters: effective generation time and delayed neutron fractions. The calculation routines were implemented at the Politecnico di Milano, and they are based on the iterated fission probability (IFP) method. The developed methodology is mainly intended for the modeling of small research reactor cores, and the results are validated by comparison to experimental data and MCNP5 calculations in 31 critical configurations.

Self-organization of surface patterns on GaAs under irradiation with very heavy polyatomic Au ions has been found. The patterns depend on the ion mass, the substrate temperature as well as the incidence angle of the ions. At room temperature, under normal incidence the surface remains flat, whereas above 200 °C nanodroplets of Ga appear after irradiation with monatomic, biatomic as well as triatomic Au ions of kinetic energies in the range of 10 to 30 keV per atom. In the intermediate temperature range of 100 to 200 °C meander- and dot-like patterns form, which are not related to Ga excess. Under oblique ion incidence up to 45° from the surface normal, at room temperature the surface remains flat for mon- and polyatomic Au ions. For bi- and triatomic ions, in the range 60° ≤ a ≤ 70° ripple patterns have been found, which become shingle-like for a ≥ 80°, whereas the surface remains flat for monatomic ions.

The TRANSURANUS fuel performance code, which is developed at the JRC-ITU and in collaboration with many partner institutes since more than three decades, has been adapted in order to be able to simulate design basis accident (DBA) conditions.

In a first step, the developments and associated validation work will be summarised for LOCA conditions. This part includes modifications in the model for large strains, for the crystallographic phase transition in zircaloy, and for burst release and large cladding deformations.

In a second step, the ongoing work for simulations of RIA conditions will be outlined that include the model for the plenum temperature, along with the separate effect studies and detailed model developments made in parallel by means of multi-scale and multi-physics tools for the high burnup structure.

Finally, the perspectives of model developments and needs for further verification and validation in the frame of international benchmark exercises dedicated to DBA simulations and the first phase of a sever accident, i.e. when the cylindrical fuel rod geometry is preserved, will be presented for discussion.

After a short introduction about the research activities of the Experimental Thermal Fluid Dynamics Department the new reactor concept "inclined rotating fixed bed reactor" is presented.
The idea and the benefits as well as selected aspects of the design are explained in detail.
Selected results from hydrodynamic experiments coupled with tomographic imaging are presented.
Furthermore, the evaluation of the new reactor concept by gas-liquid mass transfer studies is presented.

Results on Lambda hyperon production are reported for collisions of p (3.5~GeV) + Nb, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18 at GSI Helmholtzzentrum for Heavy-Ion Research, Darmstadt. The transverse mass distributions in rapidity bins are well described by Boltzmann shapes with a maximum inverse slope parameter of about 90\,MeV at a rapidity of y=1.0, i.e. slightly below the center-of-mass rapidity for nucleon-nucleon collisions, y_{cm}=1.12. The rapidity density decreases monotonically with increasing rapidity within a rapidity window ranging from 0.3 to 1.3. The Lambda phase-space distribution is compared with results of other experiments and with predictions of two transport approaches which are available publicly. None of present versions of the employed models is able to fully reproduce the experimental distributions, i.e. in absolute yield and in shape. The present high-statistics data allow for a genuine two-dimensional investigation as a function of phase space of the self-analyzing Lambda polarization in the weak decay Lambda\rightarrow p pi^-. Finite negative values of the polarization in the order of 5-20 % are observed over the entire phase space studied. The magnitude of the polarization increases almost linearly with increasing transverse momentum, {\cal P}(p_t) = (-0.19 \pm 0.02)~(GeV/c)^{-1}p_t, and increases with decreasing rapidity for y < 0.8.

After several years of planning, development, and tests, in August 2012 a new laser cooling experiment (E089) has been performed at the ESR. One essential goal of this beamtime was to demonstrate that the initially ‘hot’ ions can be collected inside the rf-bucket using just the laser, i.e. without changing the bucket frequency and without electron cooling. This scheme can namely be used to cool relativistic ion beams in future storage rings and synchrotrons, such as the HESR and SIS-100 at FAIR.

We consider an experiment to test nonlinear QED by light-by-light-scattering: An intense optical laser pulse generates in a perfect vacuum a field which induces birefringence of the vacuum. That birefringence is measured with an XFEL beam and state-of-the-art X-ray polarimetry. We calculate for planned facilitites the phase shift, ellipticity and photon numbers per shot. In addition, we consider shot-to-shot fluctuations and beam-arrival-jitter, and derive required integration times.

Phosphodiesterases (PDEs) are a class of enzymes heavily involved in cellular signaling by inactivating the second messenger cAMP and cGMP. So far, 11 different PDE families are known, of which one, the dual substrate enzyme PDE10A is abundantly expressed in the striatum. Since this brain region is thought to be involved in the pathomechanism of schizophrenia, PDE10A inhibition represents an approach in the treatment of this disease. In-vivo imaging via positron emission tomography (PET) of PDE10A would allow investigating the enzyme and its expression in neuropathological processes. Therefore our group is focused on the development of a F18-labeled PET tracer for PDE10A. Recently reported 1-arylimidazoquinoxaline inhibitors have been chosen as lead structure.
Based on this scaffold we synthesized a series of new fluorinated compounds as possible PET tracer candidates for PDE10A. To enable an easy F-18 incorporation, fluorine was chosen to be in the 2-position of the pyridine ring. The key step to introduce these different 2-fluoropyridines is the Pd-catalyzed Suzuki-coupling. 2-Fluoropyridines can be localized in two different positions of the arylimidazoquinoxaline scaffold leading to three different types of inhibitors (type A, type B, type C). The inhibitory potency of these compounds was tested towards human, recombinant PDE10A and other PDE-families. All synthesized compounds showed a high inhibitory potency. The most selective inhibitor was chosen to be further developed as PET tracer for PDE10A.

We have studied the inelastic scattering of neutrons from 56Fe in the energy range from about 0.5 to 10 MeV at the photoneutron source nELBE. The neutron energies were determined on the basis of a time-of-flight measurement. Gamma-ray spectra were measured with an HPGe detector defining the energy resolution to about 10 ns. We deduced scattering cross sections for the 2+, 4+ and 6+ yrast states in 56Fe by applying feeding corrections. The gross features of the total scattering cross section can be described within the statistical code Talys, whereas the scattering cross sections of individual states represent new information that may be used to improve the description within statistical models.

We report a combined experimental and theoretical study of the spin S = ½ nanomagnet Cu₅(OH)₂(NIPA)₄·10H_2O (Cu₅-NIPA). Using thermodynamic, electron spin resonance, and ¹H nuclear magnetic resonance measurements on one hand, and ab initio density-functional band-structure calculations, exact diagonalizations, and a strong-coupling theory on the other, we derive amicroscopicmagnetic model of Cu₅-NIPA and characterize the spin dynamics of this system. The elementary fivefold Cu²⁺ unit features an hourglass structure of two corner-sharing scalene triangles related by inversion symmetry. Our microscopic Heisenberg model comprises one ferromagnetic and two antiferromagnetic exchange couplings in each triangle, stabilizing a single spin S = ½ doublet ground state (GS), with an exactly vanishing zero-field splitting (by Kramers’ theorem), and a very large excitation gap of ∆ ≈ 68 K. Thus, Cu₅-NIPA is a good candidate for achieving long electronic spin relaxation (T ₁) and coherence (T ₂) times at low temperatures, in analogy to other nanomagnets with low-spin GS’s. Of particular interest is the strongly inhomogeneous distribution of the GS magnetic moment over the five Cu²⁺ spins. This is a purely quantum-mechanical effect since, despite the nonfrustrated nature of the magnetic couplings, the GS is far from the classical collinear ferrimagnetic configuration. Finally, Cu₅-NIPA is a rare example of a S = ½ nanomagnet showing an enhancement in the nuclear spin-lattice relaxation rate 1/T ₁ at intermediate temperatures.

Magnetic and electrical properties of electron-doped manganites Ca_0.88Ce_0.12MnO₃ and Ca_0.90Ce_0.10MnO₃ were studied in pulsed magnetic fields up to 60 T in the temperature range T = 1.5–260 K. Metamagnetic transition caused by the melting of the charge/orbital ordering and martensitic structural transition in a magnetic field was revealed. The transition is accompanied by a change in electrical resistivity of the sample by three orders. A magnetic phase diagram in the plane of the H–T was constructed. Higher values of the critical transition fields for the system Ca_1-ΧCe_ΧMnO₃, compared to the known system Ca_1-ΧSm_ΧMnO₃ are explained by a narrower range of phase separation and a bigger difference between the Néel temperatures of the C and G-type antiferromagnetic phases, which originated from the difference between the valence of the Ce⁴⁺ and Sm³⁺ ions.

The semi-arid region of the Dead Sea heavily relies on groundwater resources. This dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management. Yet, information on groundwater discharge as one main component for a sustainable management varies significantly in this area. Moreover, discharge locations, volume and temporal variability are still only partly known. A multi-temporal thermal satellite approach is applied to localise and semi-quantitatively assess groundwater discharge along the entire coastline. The authors use 100 Landsat ETM + band 6.2 data, spanning the years between 2000 and 2011. In the first instance, raw data are transformed to sea surface temperature (SST). To account for groundwater intermittency and to provide a seasonally independent data set ∆T (maximum SST range) per-pixel within biennial periods is calculated subsequently. Groundwater affected areas (GAA) are characterised by ∆T < 8.5 °C. Unaffected areas exhibit values >10 °C. This allows the exact identification of 37 discharge locations (clusters) along the entire Dead Sea coast, which spatially correspond to available in situ discharge observations. Tracking the GAA extents as a direct indicator of groundwater discharge volume over time reveals (1) a temporal variability correspondence between GAA extents and recharge amounts, (2) the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge, (3) a certain variability in discharge locations as a consequence of the Dead Sea level drop, and finally (4) the assumed flushing effect of old Dead Sea brines from the sedimentary body to have occurred at least during the two series of 2000–2001 and 2010–2011.

We present specific heat and magnetic studies as a function of temperature and magnetic field for U₂(Ni_1−xFe_x)₂Sn alloys (x = 0.0, 0.05, 0.1, 0.15, 0.2, 0.4, 0.6 and 0.8) and their hydrides (absorption of ≈ 2 H/f.u.). For the parent alloys, antiferromagnetic order is rapidly suppressed with increasing Fe concentration and non-Fermi-liquid behavior was found for x = 0.2. Hydrogenation of the parent alloys causes a substantial increase of T_N in Fe-low hydrides (x < 0.2), while Fe-rich hydrides show an unexpected appearance of ferromagnetism in the range 0.4 ≤ x ≤ 0.8. Some of the findings are compared with similar studies in U₂Co₂Sn and U₂Co₂InH_1.9.

The ELBE facility with its 40 MeV C.W. LINAC has recently received an upgrade in terms of new secondary radiation sources and beam lines, while advancing the accelerator infrastructure towards 1.6 mA C.W. operation (1.0 mA before). Therefore, the machine interlock system (MIS) was in parts redesigned to meet the new timing requirements resulting from the increased overall beam power. It comprises fast beam loss detection and a PLC based equipment protection system (EPS), tripping the key components of the electron sources. The former tripping system using PLC interrupts was replaced by an in-house developed staggered CPLD based system with optical transmission and a PROFINET IO interface for control system integration. The EPS is distributed on several PLCs and has been improved in terms of M2M communication. Further, the vacuum inrush protection was completely renewed using brought-in equipment.
This contribution depicts the technical features and performance of the MIS subsystems, as well as the challenges posed by the project track of the ELBE upgrade during implementation.

For a parametric family of four-dimensional linear dynamical systems determined by a matrix A(m) with A(0) in 1 : 1 semi-simple resonance, we have established that the central singularity on the stability boundary has codimension 8, ie the centralizer unfolding of the family needs 8 parameters. By recognizing equivalence classes in the centralizer unfolding we reduced the codimension to 5 and finally by using the homogeneity properties to 3. This allowed us to find explicitly the boundary of the stability domain and list all its singularities including six self-intersections and four ’Whitney umbrellas’. We have proposed an algorithm of approximation of the stability boundary near singularities and applied the results to the study of enhancement of the modulation instability with dissipation as well as to the study of stability of a nonconservative system of rotor dynamics.

Bringing together 18 chapters written by leading experts in dynamical systems, operator theory, partial differential equations, and solid- and fluid mechanics, this book presents state-of-the-art approaches to a wide spectrum of new and challenging stability problems.

Nonlinear Physical Systems: Spectral Analysis, Stability & Bifurcations focuses on problems of spectral analysis, stability and bifurcations arising in the nonlinear partial differential equations of modern physics. Bifurcations and stability of solitary waves, geometrical optics stability analysis in hydro- and magnetohydrodynamics, and dissipation-induced instabilities are treated with the use of the theory of Krein and Pontryagin space, index theory, the theory of multi-parameter eigenvalue problems and modern asymptotic and perturbative approaches.

Each chapter contains mechanical and physical examples, and the combination of advanced material and more tutorial elements make this book attractive for both experts and non-specialists keen to expand their knowledge on modern methods and trends in stability theory.

List of authors

Anatoly Anikin, Davide Bigoni, Jean-Francois Bony, Radomir Bosak, Richard Cushman, Olivier Doare, Sergey Dobrokhotov, Nir Dror, Setsuro Fujiie, Yasuhide Fukumoto, George Hagstrom, Makoto Hirota, Igor Hoveijn, Oleg Kirillov, Richard Kollar, Paolo Luzzatto-Fegiz, Boris Malomed, Sherwin Maslowe, Philip Morrison, Youichi Mie, Diego Misseroni, Francis Nier, Giovanni Noselli, Michael Overton, Dmitry Pelinovsky, Thierry Ramond, Jonathan Robbins, Dmitrii Sadovskii, Emanuele Tassi, Cesare Tronci, Charles Williamson, Zensho Yoshida, Daniele Zaccaria, Mather Zerzeri

The radiosynthesis of [¹⁸F]Fluspidine, a potent σ₁ receptor imaging probe for preclinical/clinical studies, was implemented on a TRACERlabTM FX F-N synthesizer. [¹⁸F]2 was synthesized in 15 min at 85 °C starting from its tosylate precursor. Purification via semipreparative RP-HPLC was investigated using different columns and eluent compositions and was most successful on a polar RP phase with acetonitrile/water buffered with NH4OAc.
After solid phase extraction, [¹⁸F]Fluspidine was formulated and produced within 59 ± 4 min with an overall radiochemical yield of 37 ± 8%, a radiochemical purity of 99.3 ± 0.5% and high specific activity (176.6 ± 52.0 GBq/μmol).1 receptor imaging probe for preclinical/clinical studies, was implemented on a TRACERlabTM FX F-N synthesizer. [¹⁸F]2 was synthesized in 15 min at 85 °C starting from its tosylate precursor. Purification via semipreparative RP-HPLC was investigated using different columns and eluent compositions and was most successful on a polar RP phase with acetonitrile/water buffered with NH4OAc.
After solid phase extraction, [¹⁸F]Fluspidine was formulated and produced within 59 ± 4 min with an overall radiochemical yield of 37 ± 8%, a radiochemical purity of 99.3 ± 0.5% and high specific activity (176.6 ± 52.0 GBq/μmol).

Der Aufsatz beleuchtet die Anwendung von Dialyseverfahren am Beispiel eines Projektes zur Trennung von Gallium und Arsen aus verbrauchten Beizlösungen der GaAs-Waferproduktion. Der Einsatz von Diffusions- und Elektrodialyse kann durch geringere Chemikalienverbräuche sowie einen einfacheren Aufbau deutliche Vorteile gegenüber Fällungs- und Extraktionsverfahren besitzen und auf diese Weise bisher nicht ökonomisch schließbare Stoffstromketten schließen.
Während Dialyseverfahren zur Laugenregeneration, Metallrückgewinnung oder Säurerückgewinnung in der Galvanotechnik bereits seit Jahren etabliert sind und sich ständig weiter entwickeln [1], sind aus der Halbleiterindustrie kaum Anwendungsfälle bekannt. In Folge der Verknappung von Seltenen Metallen und der Debatte zur Ressourceneffizienz besteht hier ein Forschungs- und Handlungsbedarf.

Der gegenwärtig anfallende Akkumulatorenschrott besitzt höhere Zinngehalte als die Bleilegierungen moderner Akkumulatoren. Dadurch fallen bei der Aufarbeitung des Akkuschrotts blei/zinnhaltige Raffinationsprodukte an, die nicht in den Wertstoffkreislauf zurückgeführt werden können. Es wird eine Möglichkeit zur Trennung dieser Produkte beschrieben. Damit hat der Recycler die Möglichkeit, die Wertstoffe Zinn und Blei der Wirtschaft wieder getrennt zur Verfügung zu stellen.

The mining and smelting region of Freiberg is well-known for its Pb-Zn-Ag lodes. These have been mined for their high silver contents since 1180. From the 18th century on, Pb, Zn, Sn and Ni became increasingly important as by-products. But the hydrothermally formed deposit also contains rare metals as In and Ge at unusually high concentrations.
Although metal prices decreased at the end of the 19th century and the operation of mines and smelters was more and more dependent of federal subsidization, parts of the research and industrial landscape were preserved. With semiconductor industry, a second economic pillar was established. The recent rise of metal prices may give a further momentum for economic growth.

Bemühungen zur Rückgewinnung von seltenen Metallen beschränken sich derzeit meist auf die Verwertung von End-of-life Produkten. In Produktionsprozessen dagegen gehen oft erhebliche Mengen dieser Wertstoffe verloren, die aus technologischen oder wirtschaftlichen Gründen nicht zurück gewonnen werden. In dem vorliegenden Beitrag werden die Möglichkeiten der Rückgewinnung von Gallium, über den bisherigen Stand der Technik hinaus, in der Halbleiterindustrie dargestellt. Als Beispiel dient das Recycling von Gallium aus Ätzlösungen der GaAs-Wafer und -Chipproduktion. Die Galliumverluste über Abwasserbehandlung und Reststoffrecycling der Waferproduktion belaufen sich auf etwa 150 g Gallium pro kg im produzierten Wafer. Ein wesentlicher Grund sind die hohen Kosten für eine umfassende selektive Rückgewinnung des Galliums aus dem Abwasser. Die TU Bergakademie Freiberg, das Helmholtz-Institut Freiberg und die Freiberger Compound Materials GmbH forschen an einem neuartigen und kostengünstigen Abwasserbehandlungsverfahren mit geringem Chemikalienverbrauch, um die Recyclingrate für Gallium wesentlich zu erhöhen und dabei die Qualität des Abwassers weiter zu verbessern. Zum Einsatz kommen sollen dabei Membranverfahren wie Dialyse und Elektrodialyse.

Previous work on low-Cu RPV steels JPB and JPC irradiated at 255 °C indicated an acceleration of the increase of both yield stress and total SANS intensity as functions of neutron fluence. A new algorithm was used to analyze the original SANS data as well as SANS data obtained for new BR2-irradiations at 290 °C of the same materials. Both data sets are compared with one another and correlated with the respective mechanical test results. Additional evidence is provided on the basis of SANS experiments performed for the RPV steels irradiated at 255 °C and post-irradiation annealed at 290 °C.

Elevated by the support: 2-Alkynyl aniline cycloisomerization to indole is catalyzed by cationic Au NPs on a carbon support. Electroneutral and rich 2-aryl indoles are further converted into 3,3′-biindoles by oxidative homocoupling that is readily catalyzed by the Au NPs on carbon, and exclusively but also somewhat sluggishly by the carbon support.

Emerging new technologies in plasma simulations allow tracking billions of particles while computing their radiative spectra. We present a visualization of the relativistic Kelvin-Helmholtz Instability from a simulation performed with the fully relativistic particle-in-cell code PIConGPU powered by 18,000 GPUs on the USA’s fastest supercomputer Titan.

Abstract: It is widely accepted that sigma (σ) receptors represent a new and different avenue in the possible pharmacological treatment of cancer and several brain-related disorders. Of the two different σ receptor types the σ₁1 receptors are assumed to be of major impact for brain diseases. Molecular imaging of brain σ₁ receptors with positron emission tomography (PET) or single photon emission computed tomography (SPECT) may provide a significant contribution to the understanding of the cross-talk between σ₁ receptors and inter- and intracellular signalling systems. New insights into These functional interrelationships will allow a better diagnosis of brain and cancerous diseases and direct a rational development of new therapeutic concepts.

In this study, we present results of the chemical composition of the moraine cover from the Inylchek Glacier in Kyrgyzstan using observations from three field campaigns between 2010 and 2012. The sample locations were selected based on high-resolution remote sensing data. Sampling included the main profile from Lake Merzbacher to Station “Hochgebirgsobservatorium Gottfried Merzbacher”, which is about 8 km in length trending in N-S-direction. Chemical analyses of more than 60 elements, including Rare Earth Elements (an important tool for the discrimination and localisation of source areas of sediments, boulders and outcropping rocks) were carried out.
Based on these data different geochemical material streams have been identified. Generally, two chemical groups of sediments, the North Type/Lake Merzbacher and the South Type/Southern Inylchek can be distinguished. The Lake Merzbacher Type sediments are characterised by a uniform chemical composition, whereas the South Inylchek Type is geochemically more heterogeneous. Toxic elements in the sediments, such as Ni, As, Cd, Tl and U, are moderately enriched. The low sulphur concentration suggests that the main water transport is caused by suspended matter.
One erratic granite block was analysed for in situ cosmogenic ¹⁰Be for exposure age dating. The age of 330 ± 90 a is conform to a glacier high stand during the “Maunder“ minimum of the solar activity.

Biosorption of actinides like uranium by fungal cells can play an important role in the mobilization or immobilization of these elements in nature. Sorption experiments of U(VI) with Schizophyllum commune at different initial uranium concentrations and varying metal speciation showed high uranium sorption capacities in the pH range of 4 to 7. A combination of High Angle Annular Dark-Field (HAADF) and Scanning Transmission Electron Microscopy (STEM) analysis showed that living mycelium cells accumulate uranium at the cell wall and intracellular. For the first time the fluorescence properties of uranium accumulates were investigated by means of time-resolved laser-induced fluorescence spectroscopy (TRLFS) beside the determination of corresponding structural parameters using X-ray absorption fine structure spectroscopy (EXAFS). While the oxidation state of uranium remained unchanged during sorption, uranium speciation changed significantly. Extra and intracellular phosphate groups are mainly responsible for uranium binding. TRLFS spectra clearly show differences between the emission properties of dissolved species in the initial mineral medium and of uranium species on fungi. The latter were proved to be organic and inorganic uranyl phosphates formed depending on the uranyl initial concentration and in some cases on pH.

Magnetic properties of compacted Sm_0.27Ca_0.73MnO₃ nanoparticles with average particle size ranging from 20 to 80 nm have been investigated in wide temperature and magnetic field range. It has been found that charge ordering transition gradually shifts to lower temperatures with decreasing particle size and almost disappears for 20 nm particles. At the same time, the relative volume of the ferromagnetic phase increases monotonously. Field-induced transition from antiferromagnetic to ferromagnetic state in 80 nmparticles appears at the same magnetic field as in the bulk. In small 20 nm particles, the transition is strongly suppressed by increasing surface spins disorder. Magnetic hysteresis loops show size-dependent exchange bias effect with exchange field, remanence asymmetry, and magnetic coercivity that depend on cooling magnetic field and temperature. Magnetic training effect has been observed in 20 nm particles and analyzed using a spin relaxation model. The thermoremanence and isothermoremanence curves have provided fingerprints of irreversible magnetization originating from the glassy component. Analysis of remanence curves has showed that the inner core of small 20 nm particles behaves as a two-dimensional diluted antiferromagnet.

The iron-rich intermetallics R ₂Fe₁₇ (where R is a rare-earth element) proved unamenable to anisotropy control via interstitial doping. There is only one precedent, Sm₂Fe₁₇N_3−δ (Sm₂Fe₁₇C_3−δ ), where interstitial modification has stabilized an easy-axis anisotropy at all temperatures up to T_C. All previous attempts to prepare a usable easy-axisR₂Fe₁₇ hydride have failed. Now we have succeeded in preparing a high-quality single-phase Tb₂Fe₁₇H₃ single crystal,which has the required easy-axis anisotropy between 0 K and T_C =560 K. At T =300 K, Tb₂Fe₁₇H₃ has the spontaneous magnetic moment M_s of 22.5 μ_B per formula unit and anisotropy field μ₀H_a of 2.5 T. The main mechanism stabilizing the easy-axis anisotropy in hydrides is the same as in other similar compounds by way of boosting the leading crystal field parameter A₂₀. Terbium is rather special in having the Stevens factors such that α_J < 0 and β_J > 0, which is why the easy-axis anisotropy in Tb₂Fe₁₇ hydrides is also assisted by the fourth-order parameter A₄₀. This proves a decisive advantage over the compounds with R = Pr, Nd, Dy, or Ho where β_J < 0 and A₄₀ is a hindrance.

We investigated an antiferromagnet UCo₂Si₂ by use of magnetization and ultrasound measurements in pulsed magnetic fields up to 60 T. It is found that the crystal UCo₂Si₂, which has the antiferromagnet type-I magnetic structure in zero field below T_N = 83 K, undergoes the metamagnetic phase transition to ferrimagnetic structure ++− type similarly to the UNi₂Si₂ with substitution of 10%–15% Ni by Pd or UPd₂Si₂. Therefore, similar phase transitions take place in the compounds with expected essentially different strength of the 5 f -d electron hybridization. In UCo₂Si₂, the transition occurs when the magnetic field is applied along the c axis at 45 T (at 1.5 K). The transition is extremely sharp and exhibits a small but non-negligible hysteresis. With increasing temperature, it becomes broader and vanishes at T_N. In our ultrasound measurements, the metamagnetic transition appears as anomalies in the sound velocity and attenuation. Our analysis suggests that the low-temperature changes in the sound velocity and attenuation predominantly are determined by an exchange renormalization caused by the sound waves.

We study the ternary clathrate Pr₃Pd₂₀Si₆ in specific heat and ac susceptibility measurements on a highquality single crystal, distinguishing antiferromagnetic and antiferroquadrupolar ordering, as well as a hitherto unknown magnetic low-temperature transition. The specific heat shows the direct involvement of nuclear spin degrees of freedom in the antiferromagnetic ordering, which is well supported by our calculation of the hyperfine level scheme without adjustable parameters. Pr₃Pd₂₀Si₆ is, therefore, one of the rare materials where the nuclear moments are involved in the formation of the magnetic ground state.

Magnetic, thermal, and transport properties of a U₃Fe₄Ge₄ single crystal have been studied. The compound crystallizes in the orthorhombic Gd₃Cu₄Ge₄ structure type. U₃Fe₄Ge₄ displays ferromagnetic order below the Curie temperature T_C = 18 K. The magnetism originates from the uranium sublattice, as iron atoms have no ordered magnetic moments. U₃Fe₄Ge₄ exhibits a pronounced easy-axis anisotropy with the anisotropy field exceeding 60 T. The spontaneous magnetic moment is M_s = 1.2 µ_B/f.u. at T = 2 K. Magnetic contribution to specific heat shows a gap excitation behavior with D = 4 meV, which can be related to the magnon gap due to the anisotropy. The Sommerfeld coefficient of the electronic specific heat is \gamma = 57 mJ/(mol-U K²) in the ordered state, whereas it is much higher (145 mJ/(mol-U K²) if derived from the paramagnetic state. Electrical resistivity has very high values on the mΩ cm range.

The magnetization of a DyFe₅Al₇ single crystal with the tetragonal ThMn₁₂-type structure was measured in pulsed fields up to 60 T along the principal axes. The compound orders ferrimagnetically at T_C = 231 K and exhibits a compensation of the Dy and Fe sublattices at T_comp = 93 K. DyFe₅Al₇ displays a high magnetic anisotropy of the easy-plane type, the [100] axis is the easy magnetization direction with the spontaneous magnetic moment M_s = 2.1 µ_B/f.u. at T = 2 K. In a field applied along the easy axis, two field-induced hysteretic transitions are observed at 30 and 53 T at T = 2 K. The critical field H of the first transition depends strongly on temperature, whereas H_cr2 is practically temperature-independent. Above the transitions the magnetization continues to grow as a function of field, as the sublattice moments continue to rotate. To reach the full saturation (forced ferromagnetic state), fields of several Tesla higher than 60 T are required. The field dependence of magnetization along the easy [100] axis was analyzed within a model for a ferrimagnet with an anisotropic dominant sublattice. The model correctly reproduces the behavior of magnetization in a magnetic field. The intersublattice molecular field on Dy and the basal-plane anisotropy constant of the Dy sublattice have been determined.

Im Rahmen eines Workshops zur "Analyse von Spurenverunreinigungen auf Oberflächen und in Gasen" werden in einer Übersicht die ionenanalytischen Verfahren vorgestellt.

Field-induced magnetic ordering in the Haldane chain compound SrNi₂V₂O₈ and the effect of anisotropy have been investigated using single crystals. Static susceptibility, inelastic neutron scattering, high-field magnetization, and low-temperature heat-capacity studies confirm a nonmagnetic spin-singlet ground state and a gap between the singlet ground state and triplet excited states. The intrachain exchange interaction is estimated to be J ∼ 8.9 ± 0.1meV. Splitting of the dispersions into two modeswithminimum energies 1.57 and 2.58 meV confirms the existence of single-ion anisotropy D(Sz)2. The value of D is estimated to be −0.51 ± 0.01 meV and the easy axis is found to be along the crystallographic c axis. Field-induced magnetic ordering has been found with two critical fields (μ₀ H _c ^⊥c = 12.0 ± 0.2 T and μ₀ H _c ^IIc = 20.8 ± 0.5 T at 4.2 K). Field-induced three-dimensional magnetic ordering above the critical fields is evident from the heat-capacity, susceptibility, and high-field magnetization study. The phase diagram in the H-T plane has been obtained from the high-field magnetization. The observed results are discussed in the light of theoretical predictions as well as earlier experimental reports on Haldane chain compounds.

The E1 strength distribution in 68Ni has been investigated using Coulomb excitation in inverse kinematics at the R3B-LAND setup and by measuring the invariant mass in the one and two Neutron decay channels.The GDR and a low-lying peak (PDR) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic RPA calculations yielding a neutron-skin thickness of 0.175(21) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.

This paper investigates the dependence of background limited performance (BLIP) temperature of quantum well infrared photodetectors (QWIPs) on doping density. In contrast to the generally accepted optimal doping condition EF = k_B TBLIP, our theoretical prediction shows that lower doping densities should slightly increase the BLIP temperature TBLIP taking into account the temperature dependence of the Fermi energy EF, a factor neglected in previous analyses. Numerical modeling results are used to reinterpret the reported TBLIP measurements for a series of QWIPs of typical design for 9 μm peak wavelength with different doping values. In addition, based on the same general expression for the Fermi energy, the optimized sheet doping concentration to achieve maximum detectivity is given by EF = 1.37 kBT, a revision to the previous EF = 2kBT condition.

The speciation, coverage, and thermodynamics of trivalent Y³⁺ adsorbed at a negatively charged muscovite (001)–water interface were measured to investigate electrostatic ion–ion correlations in a strong coupling regime. In situ specular crystal truncation rod and resonant anomalous X-ray reflectivity data show that Y³⁺ adsorbs as three distinct species (inner-sphere, adsorbed outer-sphere, and extended outer-sphere) among which the fractional coverage of the inner-sphere species (10%) is the smallest. Uptake measurements show that the maximum Y³⁺ coverage is higher by 50% than the amount needed to satisfy the muscovite surface charge in the absence of background electrolyte, but this overcharging is largely suppressed in the presence of 0.1 m NaCl. The measured intrinsic standard-state Gibbs free energy for Y³⁺ adsorption (−36.9 ± 0.9 kJ/mol) is smaller than that expected solely on the basis of its charge, and this discrepancy can be partly explained by the difference in adsorbed cation speciation at the charged interface.

The geochemistry of the actinides is of utmost importance in understanding and predicting their behavior in contaminated legacy sites as well as nuclear waste storage facilities. The unique chemistry of this group of elements including strong hydrolysis, complex redox chemistry, and the potential for polymerization reactions in combination with the actinides’ inherent radioactivity and toxicity makes studies challenging. However, especially for artificial elements like Pu and other transuranics, no natural analogues are available and homologues frequently fall short in accurately reproducing the actinides’ behavior.
We will present and discuss recent results from in situ resonant anomalous x-ray reflectivity (RAXR) and crystal truncation rod (CTR) experiments, shedding light on the inter-action of Th(IV) as well as Pu(III) and Pu(IV) with the negatively charged muscovite (001) basal plane. The example of Th(IV) demonstrates how the strong hydration of the highly charged cations prevents a close approach to the surface, instead favoring adsorption as a highly hydrated extended outer sphere complex. Subsequently, it will be shown how similar adsorption behavior in combination with the complex redox chemistry of plutonium, leads to a surface-enhanced formation of nanoparticles.
Results from surface x-ray scattering will be supplemented by ex situ alpha-spectrometry quantification and atomic force microscopy (AFM), to yield a more complete understanding of the interfacial structure.

Abstract: Resistive switching devices are considered as one of the most promising candidates for the next generation memories and nonvolatile logic applications. In this paper, we present BiFeO3:Ti/BiFeO3 (BFTO/BFO) bilayer structures with optimized BFTO/BFO thickness ratio which show symmetric, bipolar, and nonvolatile resistive switching. The resistive switching mechanism is understood by a model of flexible top and bottom Schottky-like barrier heights in the BFTO/BFO bilayer structures. For the nonvolatile logic applications, the polarity of reading bias can be used as an additional logic variable, which makes it feasible to program and store all 16 Boolean logic functions into a single cell of a BFTO/BFO bilayer structure in three logic cycles. In comparison to standard logic hardware solutions, the proposed memristive bilayer structures allow for simplified parallel, sequential, and looped logical processing.

The employment of the high-magnetic-field resonance spectroscopy to probe magnetic excitations in the THz frequency range is reported. To illustrate the great potential of this technique in solid state physics, we present results of recent electron spin resonance studies of the quantum-tunneling effect in the single-molecule magnet Mn12tba and of the soliton–magnon crossover in Cu-PM, a spin-1/2 Heisenberg chain system with a staggered transverse field. Among others, we report on the successful use of the THz-range timedomain and free electron laser spectroscopy to study magnetic excitation spectra in pulsed magnetic fields.

In this work we investigate the present capabilities of CFD for wall boiling. The computational model used combines the Euler / Euler two-phase flow description with heat flux partitioning. Very similar modelling was previously applied to boiling water under high pressure conditions relevant to nuclear power systems. Similar conditions in terms of the relevant non-dimensional numbers have been realized in the DEBORA tests using Dichlorodifluoromethane (R12) as the working fluid. This facilitated measurements of radial profiles for gas volume fraction, gas velocity, liquid temperature and bubble size.
Robust predictive capabilities of the modelling require that it is validated for a wide range of parameters. In previous studies (Krepper and Rzehak, 2011, 2013) it was shown that a careful calibration of correlations used in the wall boiling model is necessary to obtain agreement with the measured data. We here consider tests under a variety of conditions concerning liquid subcooling, flow rate and heat flux. It is investigated to which extent a set of calibrated model parameters suffices to cover at least a certain parameter range.
In the paper the potential of the application of a population balance model is demonstrated. The measured gas bubble size profiles show an increase of the bubble size with increased distance from the heated wall caused by bubble coalescence. Furthermore the model framework is shown to be able to describe a shift from wall peak to core peak in the radial gas volume fraction profiles with increasing inlet temperature respective decreasing subcooling temperature, which was observed in some test series.

A convergent strategy was followed to modify systematically carbazole based CB₂ receptor ligands. The length of the N-(fluoroalkyl) group (n in 7), the length of the alkanamide (m in 7) and the substitution pattern of the phenyl moiety (X and Y in 7) were varied systematically. The highest CB₂ affinity was found for the 2-fluoroethyl substituted carbazole derivative 20a (K_i = 5.8 nM) containing the propionamide and the 2-bromo-4-fluorophenyl moiety. According to docking studies 20a fits nicely into the binding pocket of the CB₂ receptor, but elongation of the fluoroethyl side chain leads to a different binding mode of the ligands. The high CB₂ affinity together with the high selectivity over the CB₂ subtype qualifies the fluoroethyl derivative 20a to be developed as a PET tracer.

ohne Abstract, da eingeladener Vortrag

These proceedings shall give an overview over the rapidly growing number of super-radiant linac-based THz sources which have been developed and designed over the past 13 years following the seminal pilot experiment at the Jefferson lab energy recovery linac in 2001 [1]. More than 20 super-radiant THz facilities already exist or are planned worldwide and are listed together with a set of fundamental parameters in the appendix of this paper.

[1] G.L. Carr et. al., “High power terahertz radiation from relativistic electrons” Nature 420 (2001), 153.

Periodical arrangements of magnetic nanostructures offer very exciting and new features that do not exist in thin films. They range from dipolar interactions leading to two-magnon scattering in periodically perturbed films to the opening of magnonic band gaps in a magnonic crystal acting as e.g. filters - analog to a photonic crystal.
I will present experimental data from ferromagnetic resonance (FMR) experiments of two types of periodic nanostructures, which depict the transition region from a thin film to an array of separated magnetic elements. The structures were created (i) by ion beam erosion in a self-organizing process or (ii) by local magnetic property patterning using ion beam implantation in conjunction with lithographic masks. Both methods allow for easy tailoring of the magnetic dimensions.
The FMR data shows a splitting of the uniform resonance mode into several modes due to the dipolar stray fields of the nanostructures, which can be imaged by transmission electron holography. The results are corroborated by an analytical perturbation theory of two-magnon scattering developed by P. Landeros and D.L. Mills. This extended model allows for calculating the resonance response function of 1D and 2D periodically perturbed ferromagnetic films in almost perfect agreement to the FMR experiments.

Channeling radiation is an appealing radiation process to produce x-ray radiation with low-energy electron beams.
In this contribution we describe the anticipated performance and preliminary results from a channeling-radiation experiment
to produce ~1,2-keV radiation from a ~4-MeV electron beam at Fermilab’s high-brightness electron source lab (HBESL).
We also discuss plans to produce x-ray radiation ([10; 80]-keV photon energy) at Fermilab’s advanced superconducting
test accelerator (ASTA).

Modern compute hardware allows for simulating laser plasma interaction interactively and for integrating physical effects that could not be accounted for previously. I will show how efficient plasma simulations may pave the way towards predictive simulations of laser matter interaction.

We present results on laser cooling of heavy ion beams at ESR and discuss prospects for laser cooling at CSRe.

We present results on laser cooling of ion beams at storage rings and discuss their relevance for future facilities.

In order to understand what happens when jets of hot, streaming gas are ejected at high speed into the cosmos, we are bound to rely on m easuring the radiation emitted by the particles in the jet. Astrophysical jets can originate from a variety of sources such as stars, black holes and even galaxies. In such jets, the plasma flow can become unstable, generating characteristic patterns of p article flows. Using our particle-in-cell code PIConGPU utilizing the complete TITAN supercomputer system at Oak Ridge National Laboratory, we were able, for the first time, to not only simulate the particle dynamics but also the radiation emitted during the formation of such an instability, the Kelvin-Helmholtz instability.

We present a particle-in-cell simulation of the relativistic Kelvin-Helmholtz Instability (KHI) that for the first time delivers angularly resolved radiation spectra of the particle dynamics during the formation of the KHI. This enables studying the formation of the KHI with unprecedented spatial, angular and spectral resolution. Our results are of great importance for understanding astrophysical jet formation and comparable plasma phenomena by relating the particle motion observed in the KHI to its radiation signature. The innovative methods presented here on the implementation of the particle-in-cell algorithm on graphic processing units can be directly adapted to any many-core parallelization of the particle-mesh method. With these methods we see a peak performance of 7.176 PFLOP/s (double-precision) plus 1.449 PFLOP/s (single-precision), an efficiency of 96% when weakly scaling from 1 to 18432 nodes, an efficiency of 68.92% and a speed up of 794 (ideal: 1152) when strongly scaling from 16 to 18432 nodes.

We present live visualization of large-scale plasma simulations with PIConGPU.

We present results of our PIConGPU KHI simulation on TITAN at ORNL.