Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31745 Publications
Use of animal PET/MR for radiotracer development and molecular imaging
Brust, P.;
Es ist kein Abstract vorhanden.
  • Invited lecture (Conferences)
    TransportDementia2, 02.-06.09.2016, Oslo, Norway

Publ.-Id: 24637 - Permalink


Effiziente Nutzung mineralischer und metallhaltiger Rohstoffe
Reuter, M. A.;
Ziel dieses Workshops ist es, programmübergreifende Schnittstellen in der Materialforschung zu stärken und Synergien zu nutzen.
  • Invited lecture (Conferences)
    Materialien und Modelierung - Workshop, 08.-09.11.2016, Berlin, Deutschland

Publ.-Id: 24636 - Permalink


Challenges in the analysis of mineral surfaces in flotation technology
Firkala, T.; Lederer, F.; Pollmann, K.; Rudolph, M.;
Flotation is one of the most traditional and widely used technologies in industrial mineral processing. This methodology is based on changing the hydrophobic behaviour of the mineral surfaces using organic flotation collector molecules. The mineral – collector interactions in the flotation interface are very important for the detailed understanding of the technology, but presently they are practically unexplored. We present our concepts to study the flotation interface applying some ultrasensitive nanospectroscopic facilities of Helmholtz Institute Freiberg for Resource Technology and Helmholtz-Zentrum Dresden-Rossendorf.
  • Lecture (others)
    University of Applied Sciences Wildau, Department Seminar, 12.12.2016, Wildau, Deutschland

Publ.-Id: 24635 - Permalink


Experimental study on rise velocities of single bubbles in liquid metal under the influence of strong horizontal magnetic fields in a flat vessel
Strumpf, E.;
The ascent of single argon bubbles with equivalent diameters (deq) between 3.43 and 6.28 mm is investigated at room temperature in a flat, cubic vessel by means of Ultrasound Doppler Velocimetry (UDV). GaInSn is used as a working liquid and magnetic flux intensities up to B ≈ 0.918 T are applied. A decelerating effect on the rise velocity is observed at lower, an accelerating effect at medium and a reduction at higher field strengths. Maximum velocities are achieved when N/CD ≈ 1, bubble paths are substantially rectilinear at N/CD > 2. The mean ascent velocities are compared with literature and data of this work as well of other publications is provided in tables.
Keywords: bubble, rise velocity, liquid metal, magnetic field, ultrasound

Downloads:

Publ.-Id: 24634 - Permalink


Alpaka - One Programming Model for Parallel Kernel Acceleration of Heterogeneous Systems
Matthes, A.; Zenker, E.; Worpitz, B.; Widera, R.; Huebl, A.; Juckeland, G.; Knüpfer, A.; Nagel, W.; Bussmann, M.;
Alpaka provides a uniform, abstract C++ interface to a range of parallel programming models. It can express multiple levels of parallelism and allows for generic programming of kernels either for a single accelerator device or a single address space with multiple CPU cores. The Alpaka abstraction of parallelization is influenced by and based on the groundbreaking CUDA abstraction of a multidimensional grid of blocks of threads. The four main execution hierarchies introduced by Alpaka are called grid, block, thread, and element level. The element level denotes an amount of work a thread needs to process sequentially. These levels describe an index space which is called work division.

Alpaka does not dictate any memory containers nor memory iterators, instead it is based on a simple pointer based memory model, allowing to allocate memory buffers device-wise and copy them between devices. This model provides full power over data structures and their data access and is totally data structure agnostic.

Separating parallelization abstraction from specific hardware capabilities allows for an explicit mapping of these levels to hardware. The current implementation includes mappings to programming models, called back-ends, such as OpenMP, CUDA, C++ threads, and boost fibers. Nevertheless, mapping implementations are not limited to these choices and can be extended or adapted for application-specific optimizations. Which back-end and work division to utilize is parameterized per kernel within the user code.

We have demonstrated platform and performance portability for the DGEMM benchmark, which provides consistently 20% of the theoretical peak performance on AMD, Intel, IBM, and NVIDIA hardware, being on par with the respective native implementations. Moreover, performance measurements of a real world application (PIConGPU, HASEonGPU, ISAAC) translated to Alpaka unanimously demonstrated that Alpaka can be used to write performance portable code.
Keywords: Heterogeneous computing, HPC, C++, CUDA, OpenMP, platform portability, performance portability
  • Lecture (others)
    GPU Technology Conference Europe, 28.-29.09.2016, Amsterdam, Niederlande

Publ.-Id: 24633 - Permalink


Quasiparticle Excitations in the Superconducting State of FeSe Probed by Thermal Hall Conductivity in the Vicinity of the BCS–BEC Crossover
Watashige, T.; Arsenijevic, S.; Yamashita, T.; Terazawa, D.; Onishi, T.; Opherden, L.; Kasahara, S.; Tokiwa, Y.; Kasahara, Y.; Shibauchi, T.; von Löhneysen, H.; Wosnitza, J.; Matsuda, Y.;
There is growing evidence that the superconducting semimetal FeSe (Tc ∼ 8 K) is in the crossover regime between weak-coupling Bardeen–Cooper–Schrieffer (BCS) and strong-coupling Bose–Einstein-condensate (BEC) limits. We report on longitudinal and transverse thermal conductivities, κxx and κxy, respectively, in magnetic fields up to 20 T. The field dependences of κxx and κxy imply that a highly anisotropic small superconducting gap forms at the electron Fermi-surface pocket whereas a more isotropic and larger gap forms at the hole pocket. Below ∼1.0 K, both κxx and κxy exhibit distinct anomalies (kinks) at the upper critical field Hc2 and at a field H* slightly below Hc2. The analysis of the thermal Hall angle (κxyxx) indicates a change of the quasiparticle scattering rate at H*. These results provide strong support to the previous suggestion that above H* a distinct field-induced superconducting phase emerges with an unprecedented large spin imbalance.

Publ.-Id: 24631 - Permalink


Ultrafast electronic response of graphene to a strong and localized electric field
Gruber, E.; Wilhelm, R. A.ORC; Petuya, R.; Smejkal, V.; Kozubek, R.; Hierzenberger, A.; Bayer, B. C.; Aldazabal, I.; Kazansky, A. K.; Libisch, F.; Krasheninnikov, A. V.; Schleberger, M.; Facsko, S.; Borisov, A. G.; Arnau, A.; Aumayr, F.
The way conduction electrons respond to ultrafast external perturbations in low dimensional materials is at the core of the design of future devices for (opto)electronics, photodetection and spintronics. Highly charged ions provide a tool for probing the electronic response of solids to extremely strong electric fields localized down to nanometre-sized areas. With ion transmission times in the order of femtoseconds, we can directly probe the local electronic dynamics of an ultrathin foil on this timescale. Here we report on the ability of freestanding single layer graphene to provide tens of electrons for charge neutralization of a slow highly charged ion within a few femtoseconds. With values higher than 1012 A cm 2, the resulting local current density in graphene exceeds previously measured breakdown currents by three orders of magnitude. Surprisingly, the passing ion does not tear nanometre-sized holes into the single layer graphene. We use time-dependent density functional theory to gain insight into the multielectron dynamics.
  • Open Access LogoNature Communications 7(2016), 13948
    DOI: 10.1038/ncomms13948
  • Lecture (Conference)
    Ionenstrahltreffen, 13.-15.02.2017, Göttingen, Deutschland
  • Lecture (Conference)
    Frühjahrestagung der Deutschen Physikalischen Gesellschaft, Sektion Kondensierte Materie, 20.-24.03.2017, Dresden, Deutschland
  • Invited lecture (Conferences)
    Optical NanoSpectroscopy IV, 28.-31.03.2017, Lissabon, Portugal

Publ.-Id: 24630 - Permalink


Electronic structure of UN based on specific heat and field-induced transitions up to 65 T
Troc, R.; Samsel-Czekala, M.; Pikul, A.; Andreev, A. V.; Gorbunov, D. I.; Skourski, Y.; Sznajd, J.;
The 5f electrons of uranium in the uranium mononitride (UN) compound are described in the literature as either localized or fully itinerant. Motivated by these contradictory statements, we studied low-temperature specific heat and high-field magnetization of single-crystalline UN in magnetic fields up to 9 and 65 T, respectively. Our detailed analysis of the magnetic contribution to the specific heat of UN revealed that its real ground state is complex and the 5f electrons seem to have a dual nature; i.e., they possess simultaneously local and itinerant characters in two substates. High-field experiments allowed us to construct a tentative magnetic phase diagram of UN with a metamagnetic transition from antiferromagnetism to ferrimagnetism at a magnetic field as high as 58 T at 2 K. Such a field only enables a reversal of 1 of the 12 antiferromagnetically coupled ferromagnetic layers in the direction of the magnetic field. Any further steplike transitions require application of ever higher magnetic fields, which is beyond the experimental possibilities. We show that the magnetic phase diagram can be successfully reproduced considering a layer model of the Ising spins. That model allows rough estimation of a phase transition into fully induced ferromagnetism at a field as high as about 258 T. It gives rise to a giant coupling between ferromagnetically ordered layers in UN. The obtained characteristics are presented, together with the results of recent x-ray photoemission spectroscopy and transport property measurements. They are analyzed and compared with a number of earlier experiments and band structure calculations that were performed for this compound and are widely described in the literature. We show that different experiments probe different substates of the uranium 5f electrons in UN (itinerant or localized), which supports our hypothesis on their dual nature.

Publ.-Id: 24629 - Permalink


Ultrasonic flow measurements in a 1:6 downscaled water mockup of the DRESDYN dynamo experiment
Gundrum, T.; Vogt, T.; Giesecke, A.; Herault, J.; Stefani, F.;
The project DRESDYN (DREsden Sodium facility for DYNamo and thermohydraulic studies) conducted at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) provides a platform for a variety of liquid sodium experiments. Most ambitious experiment will be a precession driven dynamo experiment which consists of a large cylindrical cavity filled with liquid sodium that will simultaneously rotate around two axis. The experiment is motivated by the idea of a precession-driven flow as a complementary energy source for the geodynamo or the ancient lunar dynamo. The detailed knowledge of the flow structure in the precessing cylindrical vessel is of key importance for the prediction of the dynamo action. My presentation addresses experimental examinations with ultrasonic Doppler velocimetry in the low Reynolds region to validate numerical simulations.
Keywords: DRESDYN, sodium experiments, precession driven dynamo, ultrasonic Doppler velocimetry
  • Lecture (Conference)
    17th MHD Days, 30.11.-02.12.2016, Göttingen, Deutschland

Publ.-Id: 24628 - Permalink


Comparison of single-field and robust multi-field IMPT plans for oropharynx carcinoma by an enhanced method of robustness analysis
Stützer, K.; Lin, A.; Kirk, M.; Lin, L.;
Purpose:
Presentation of an enhanced robustness analysis and its application on single-field (SFO) and robust multi-field optimized (rMFO) plans for intensity modulated proton therapy (IMPT).

Material/Methods:
rMFO IMPT plans were optimized (Eclipse v13.7, Varian, Palo Alto, CA) for 11 oropharynx carcinoma patients, which had been treated post-surgery with SFO IMPT with simultaneous integrated boost prescription. Expected mean dose per voxel is calculated for minimal, 0% and maximal range uncertainty (RU), considering 19 setup error (SE) scenarios and their likelihood of occurrence. Voxel-wise boundary dose distributions are created from all 57 scenarios including systematic RU and random SE while also taking into account the averaging effect of fractionation to approximate realistic worst cases for the total treatment course. Dose error distributions for under- and overdosage with according ROI-specific metrics are derived from these boundary doses.

Results:
Nominal rMFO plans show improved CTV coverage and homogeneity while simultaneously reducing the average mean dose to the constrictor muscles, larynx and ipsilateral middle ear by 5.6Gy(RBE), 2.0Gy(RBE) and 3.9Gy(RBE), respectively. The comparison of SFO and rMFO boundary doses reveals slightly larger differences for these organs, and significantly lower brainstem maximum and ipsilateral parotid mean dose in rMFO plans. Many dose error metrics are significantly superior for rMFO plans.

Conclusions:
The nominal benefit of better CTV coverage and OAR dose sparing by rMFO compared to SFO plans is preserved under considerations of SE and RU. DVH bands and dose metrics from the boundary dose distributions will help to judge plan robustness in clinical routine.
  • Lecture (Conference)
    56th Annual Conference of the Particle Therapy Co-Operative Group, 08.-13.05.2017, Chiba, Yokohama, Nihon

Publ.-Id: 24627 - Permalink


Recycling 4.0 A metallurgical perspective
Reuter, M. A.;
Der Umgang mit Rohstoffen und Energie spielt für die industrielle Entwicklung Europas eine entscheidende Rolle. Darüber hinaus beeinflussen Entwicklungstrends wie Industrie 4.0, Energiewende, E-Mobility, Wasserstofftechnologie usw. die Nichteisenmetallurgie im Bereich der Prozesstechnik und Produkte. Dies wird in den nächsten Jahren neben einer rascheren Veränderung auf Verfahrensebene ebenfalls zu einer verstärkten Vernetzung von Disziplinen, wie der Rohstofftechnik, der Metallurgie sowie den Werkstoffwissenschaften führen, sodass auf dem Gebiet des Recyclings von komplexen Reststoffen und Produkten zukünftig ein entscheidender Schritt hinsichtlich höherer Ressourcen- und Energieeffizienz gelingen könnte. Daneben ist es besonders wichtig, dass Lehre und Forschung als Einheit weiterhin bestehen bleiben, um den Anforderungen in den erwähnten Bereichen hinsichtlich einer hochqualitativen Ausbildung gerecht zu werden.
  • Invited lecture (Conferences)
    Treffen der Nichteisenmetallurgie, 26.11.2015, Leoben, Österreich

Publ.-Id: 24626 - Permalink


Platinum-group mineral distribution of LG6 and LG6a chromitites of the western Bushveld Complex, South Africa
Bachmann, K.; Osbahr, I.; Gutzmer, J.;
The Bushveld Complex (BVC) in South Africa hosts the majority of global resources of chromium and platinum group elements (PGE). A correlation between chromitite seams and PGE is exceptionally well expressed as all chromitite layers carry elevated levels of PGE. Furthermore, the Bushveld chromitite seams show a progressive and massive increase in PPGE (Pt, Pd, Rh) contents up sequence, whereas the IPGE (Os, Ir, Ru) values remain broadly constant or rise only slightly. This trend coincides with decreasing Cr/Fe of the chromitites resulting in a focus of mining the upper seams, namely the upper group (UG)-2 for PGE and the middle groups (MG)/ lower groups (LG) for chromite. In recent years, companies already commenced extracting PGE from the MGs and LGs as a by-product during and/or after chromite production. However, only few mineralogical studies about the siting of the PGE (in silicates, sulfides or discrete platinum-group minerals (PGM)) in the LGs and MGs are available. Furthermore, information about parameters such as variation of the proportions of PGM within the chromitite seams, PGM association and grain sizes are scarce. From a geometallurgical perspective, these fundamental parameters about modal mineralogy and microfabric of the PGM in the chromite ores are crucial.
The purpose of this study is to fill this knowledge gap for the western limb of the BVC by investigating drill cores of the LG6 and LG6a seams from the Thaba mine near Thabazimbi. The study follows systematic studies of Voordouw et al.. More than 30 polished thin sections from three drill cores were analyzed by mineral liberation analysis to determine both, the modal mineralogy and the contained PGM (>100 grains per section in average) as well as base metal sulfides in-situ. This work was complemented by detailed analysis of the silicates by electron probe microanalyzer. The PPGE-bearing minerals include various Pt-Pd-Rh sulfides and -alloys as well as a significant amount of PPGE arsenides, bismuthides, and antimonides. IPGE are bound in laurite as well as sulfarsenides with various composition. The PGM are associated with sulfides as well as chromite and minor silicates. Grain-sizes are typically small (below 10 µm, usually c. 5 µm and smaller).
Keywords: -
  • Lecture (Conference)
    1st GOOD meeting, 15.-18.03.2016, Freiberg, Deutschland

Publ.-Id: 24625 - Permalink


Platinum-group mineral composition and mineralogy of LG6 and LG6a chromitites of the western Bushveld Complex, South Africa
Bachmann, K.; Osbahr, I.; Krause, J.; Gutzmer, J.;
The Bushveld Complex (BVC) in South Africa hosts the majority of global resources of chromium and platinum group elements (PGE). A correlation between chromitite seams and PGE is exceptionally well expressed as all chromitite layers carry elevated levels of PGE. Furthermore, the Bushveld chromitite seams show a progressive and massive increase in PPGE (Pt, Pd, Rh) contents up sequence, whereas the IPGE (Os, Ir, Ru) values remain broadly constant or rise only slightly. This trend coincides with decreasing Cr/Fe of the chromitites resulting in a focus of mining the upper seams, namely the upper group (UG)-2 for PGE and the middle groups (MG)/ lower groups (LG) for chromite. In recent years, companies already commenced extracting PGE from the MGs and LGs as a by-product during and/or after chromite production. However, only few mineralogical studies about the siting of the PGE (in silicates, sulfides or discrete platinum-group minerals (PGM)) in the LGs and MGs are available. Furthermore, information about parameters such as variation of the proportions of PGM within the chromitite seams, PGM association and grain sizes are scarce. From a geometallurgical perspective, these fundamental parameters about modal mineralogy and microfabric of the PGM in the chromite ores are crucial.


The purpose of this study is to fill this knowledge gap for the western limb of the BVC by investigating drill cores of the LG6 and LG6a seam from the Thaba mine near Thabazimbi. Currently, the deposit is mined for chromite by CRONIMET Chrome SA (Pty.) Ltd. The study follows systematic studies of Voordouw et al. More than 60 polished thin sections from three drill cores were analyzed by mineral liberation analysis to determine both, the modal mineralogy and the contained PGM (>100 grains per section in average) as well as base metal sulfides in-situ. This work was complemented by detailed analysis of the PGM, base metal sulfides (pentlandite, pyrite, pyrrhotite) and silicates by electron probe microanalyzer. The PPGE-bearing minerals include various Pt-Pd-Rh sulfides and -alloys as well as a significant amount of PPGE arsenides, bismuthides, and antimonides. IPGE are bound in laurite as well as sulfarsenides with various composition. The PGM are associated with sulfides as well as chromite and minor silicates. Grain-sizes are typically small (below 10 µm, usually c. 5 µm and smaller). Furthermore, feed, concentrate and tailings from the Thaba mine processing plant were investigated to estimate the mineralogical controls on the distribution of the PGM during chromite processing.
Keywords: -
  • Lecture (Conference)
    35th INTERNATIONAL GEOLOGICAL CONGRESS, 27.08.-04.09.2016, Kapstadt, Südafrika

Publ.-Id: 24624 - Permalink


Advanced discrimination of In-bearing minerals by automated mineralogy
Bachmann, K.; Frenzel, M.; Krause, J.; Gutzmer, J.;
The identification and accurate characterization of discrete Indium minerals is usually a very cumbersome procedure due to their small grain size (typically below 10 μm) and complex mineral assemblage in massive sulfide mineralizations. A novel strategy for finding discrete In minerals and quantifying their composition was developed by using a mineral liberation analyzer (MLA) and an electron microprobe analysis (EPMA). The method was successfully applied to polymetallic massive sulfide ores with an incompletely known mineralogical composition from the Neves-Corvo deposit in Portugal. The occurrence of roquesite and sakuraiite could be systematically detected, their concentration quantified by MLA measurements, and their identity later confirmed by EPMA analyses. Based on the results obtained, an almost complete deportment of In was obtained for the six samples studied. This supports the approach taken, combining automated mineralogical data with electron microprobe analysis. A similar approach can be easily applied to other common minor and trace elements in complex base-metal sulfide ores, e.g. Se, Ge, Sb, or Ag, thus permitting targeted development of resource technologies suitable for by-product recovery.
Keywords: MLA, automated mineralogy, Indium, Neves Corvo, roquesite, sakuraiite

Publ.-Id: 24623 - Permalink


Particle-based Sb distribution model for Cu–Pb flotation as part of geometallurgical modelling at the polymetallic Rockliden deposit, north-central Sweden
Minz, F. E.; Bolin, N.-J.; Lamberg, P.; Wanhainen, C.; Bachmann, K.; Gutzmer, J.;
The polymetallic Cu–Zn ore of the Rockliden massive sulphide deposit in the Skellefte District in north-central Sweden contains a number of deleterious elements in relevant concentrations. Of particular concern is the amount of antimony (Sb) reporting to the Cu–Pb concentrate. The aim of this study was to compare different model options to simulate the distribution of Sb minerals in a laboratory flotation test based on different degrees of details in the mineralogical information of the flotation feed. Experimental data obtained from four composites were used for the modelling and simulation. The following different simulation levels were run (sorted from least to highest level of detail of their mineralogical information): chemical assays, unsized bulk mineralogy, sized bulk mineralogy and particle information. It was shown that recoveries simulated based on bulk mineralogy are mostly within the error margin acceptable in the exploration stage of the Rockliden deposit. Unexpected high deviation in the simulation using particle information from the original recovery has been partly attributed to the fact that recovery of non-liberated particles cannot be modelled appropriately in the present version of the modelling and simulation software. It is expected that the implementation of full particle information in simulation will improve the Sb distribution model for the mineralogically complex Rockliden deposit.
Keywords: Flotation kinetics, Mineral floatability, Modelling, Sulphide ores, Antimony, Liberation

Publ.-Id: 24622 - Permalink


Lead, Zinc and their minor elements: enablers of a circular economy
Reuter, M. A.; Matusewicz, R.; van Schaik, A.;
In their own right, both lead and zinc are crucial everyday metals playing their well-known roles in our society. Increasingly, they are linked in concert with the other base metals, copper, nickel and cobalt, which together form the crucial carrier metals for a sustainable society – the Web of Metals (WoM). This paper examines the special and crucial role both lead and zinc have in acting as enablers in any recycling efforts as they carry and release important and vital minor elements. Through examination of the rising needs for such carriers, this paper examines the approach and technologies which need to be considered by any producer of lead or zinc. Attention is paid to the limits and extent of this carrier role in the typical processing of materials. Examples of specialised technology and flow sheet needs are presented with consideration given to a “whole of chain” or systems-integrated metal production (SIMP) approach as a cornerstone of a circular economy. Also outlined are the challenges facing not only producers, but legislators who need to consider the balance between providing our societal needs with baseline technology infrastructure requirements for valuable metals extraction. A number of conclusions after each section summarize the message of this paper, which states simply that not only is the criticality of metals important but the criticality of the infrastructure (Infrastructure Criticality) that can recover metals from complex mixtures. Lead and zinc are metals at the heart of a Circular Economy, therefore key enablers of the Internet-of-Things (IoT).
Keywords: Resource efficiency – Lead – Zinc – Gallium – Indium – Antimony – Recycling – System integration – Design for Recycling (DfR)
  • World of Metallurgy - Erzmetall 68(2015)3, 132-146

Publ.-Id: 24620 - Permalink


The role of temporal contrast for proton acceleration experiments at Draco
Obst, L.; Metzkes, J.; Zeil, K.; Schlenvoigt, H.; Kraft, S.; Rehwald, M.; Bock, S.; Helbig, U.; Gebhardt, R.; Schramm, U.;
The role of temporal contrast and a possible diagnostics in the experimental area are presented.
Keywords: Laser, Plasma, Contrast, Proton Acceleration
  • Lecture (others)
    Draco Workshop, 19.12.2016, Dresden, Deutschland

Publ.-Id: 24619 - Permalink


High-contrast laser-proton acceleration from condensed hydrogen jet and ultra-thin foils
Rehwald, M.; Zeil, K.; Obst, L.; Schlenvoigt, H.-P.; Brack, F.; Metzkes, J.; Kluge, T.; Kraft, S.; Sommer, P.; Loeser, M.; Ziegler, T.; Schramm, U.; Goede, S.; Wolter, S.; Kazak, L.; Gauthier, M.; Curry, C.; Macdonald, M.; Schumaker, W.; Mishra, R.; Ruyer, C.; Fiuza, F.; Roedel, C.; Glenzer, S.;
Demanding applications like radiation therapy of cancer have pushed the development of laser plasma proton accelerators and defined levels of control and necessary proton beam stability in laser plasma experiments. The presentation will give an overview of the recent experiments for laser driven proton acceleration with high contrast at the high power laser Draco at HZDR, delivering pulses of 30fs and 5J. We present results of an experimental campaign employing a pure condensed hydrogen jet as a renewable target. The jet's nominal electron density is approximately 30 times the critical density and its diameter can be varied to be 2µm, 5µm or 10µm and thus allowing to study the regime of relativistic transparency. Different ion diagnostics reveal mono-species proton acceleration in the laser incidence plane around the wire-like target. Radiochromic film stacks in forward direction display signatures of filament-like structures, stemming from a Weibel-like instability generated at the rear side of the target in the underdense plasma region. A comparison of the data with results obtained using ultra-thin foils at high-contrast provided by a single plasma-mirror will be given.
Additionally, the expanding jet could be monitored on-shot with a temporally synchronized probe beam perpendicular to the pump laser axis. Recorded probe images resemble those of z-pinch experiments with metal wires and indicate sausage-like instability along the jet axis.
Keywords: Z-pinch, laser proton acceleration, cryogenic hydrogen jet, laser plasma
  • Lecture (Conference)
    34-th European Conference on Laser Interaction with Matter, 18.09.-23.12.2016, Moscow, Russia

Publ.-Id: 24618 - Permalink


Synthesis and in vitro evaluation of new fluorinated quinoline derivatives with high affinity for PDE5: Towards the development of new PET neuroimaging probes
Liu, J.; Maisonial-Besset, A.; Wenzel, B.; Canitrot, D.; Baufond, A.; Chezal, J. M.; Brust, P.; Moreau, E.;
The increasing incidence of Alzheimer’s disease (AD) worlwide is a major public health problem. Current treatments provide only palliative solutions with significant side effects. Therefore, new efficient treatment options and novel early diagnosis tools are urgently needed. Recently, strong pre-clinical evidences suggested that phosphodiesterase 5 (PDE5) may be clinically relevant both as biomarker and drug-target in AD. In this study, we intended to develop a new radiofluorinated tracer for the visualisation of PDE5 in brain using PET imaging. Based on currently known PDE5 inhibitors, a series of novel fluorinated compounds bearing a quinoline core have been synthesised via multi-steps reaction pathways. Their affinity for PDE5 and selectivity over other PDE families have been investigated. According to the data collected from this in vitro screening, fluorinated derivatives 24a, b bearing a fluoroethoxy group at the C-3 position of the quinoline core appeared to be the most promising structures and will be further radiolabelled with fluorine-18 for in vitro and in vivo evaluations as PET radiotracer for neuroimaging of PDE5.

Downloads:

Publ.-Id: 24617 - Permalink


A small animal tumour model for low-energy laser-accelerated particles
Pawelke, J.; Brüchner, K.; Krause, M.; Leßmann, E.; Schmidt, M.; Beyreuther, E.;
no abstract available
Keywords: no keywords available
  • Open Access LogoAbstract in refereed journal
    Radiotherapy and Oncology 123(2017)Suppl. 1, S87-S87
    DOI: 10.1016/S0167-8140(17)30612-6
  • Invited lecture (Conferences)
    ESTRO 36, 05.-09.05.2017, Vienna, Austria

Publ.-Id: 24616 - Permalink


Gold: A key enabler of a Circular Economy
Reuter, M. A.;
This lecture discusses facetes of the book chapter below.

Metals are an essential and critical component of today's society: a moment's reflection on their ubiquitous presence in virtually all energy and material production processes is sufficient to confirm this. Metals play a key role in enabling sustainability through various high-tech applications in society. However, the resources of our planet are limited, as is the strain to which we can subject it in terms of emissions, pollution, and disposal of waste. For these reasons, finding ways to lower the environmental footprint of our collective existence and therefore lowering greenhouse gas and other emissions is a vital priority. The principal theme of this contribution is the maximization of resource efficiency as well as enabling a circular economy (CE) through the recycling of waste electric and electronic equipment, with a focus on precious metals (PMs) (incorporating gold, silver, and the platinum group metals [PGMs]) and the base-metal industry that enables their recycling. The detailed and deep knowledge that is required to systemically fully understand resource efficiency in the context of a CE are discussed and the concepts of design for resource efficiency and design for recycling elaborated on. Specifically, the understanding of product-centric recycling is highlighted, setting it apart from the usual material-centric recycling approaches. The latter focus more on bulk materials and therefore inherently limit the maximal recovery of technologically critical elements in particular, as well as PMs and PGMs. The base metals – principally, copper, cobalt, lead, nickel, tin, and zinc – all play a crucial part in the present society. Increasingly, these are linked in concert to form the crucial carrier metals for the sustainable CE society termed the “web of metals” and “web of products” or, in a more modern paradigm, system integrated metal production–in other words, the process metallurgical Internet of things. This chapter also examines the special and crucial role base metals have in acting as enablers in any recycling efforts, as they also play a key role during recycling, such as copper and lead being the solvent of gold and other PMs and PGMs and release them during refining. Above all, the PMs are key economic enablers for the economic viability of recycling as well as the metallurgical infrastructure (system integrated metal production/Internet of things) that makes it possible to recover PMs and PGMs and their other associated elements.
Keywords: Critical metals; Design for recycling; Furnace technology; Gold; Hydrometallurgy; Internet-of-things; Precious metals; Process metallurgy; Pyrometallurgy; Recycling; System integrated Metal production; WEEE
  • Invited lecture (Conferences)
    World Gold Conference, 29.09.-01.10.2015, Johannesburg, South Africa

Publ.-Id: 24615 - Permalink


Resource efficiency and circular economy - understanding the concepts
Reuter, M. A.;
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Global Network Conference on Resource Efficient and Cleaner Production, 12.-16.10.2015, Davos, Switzerland

Publ.-Id: 24614 - Permalink


Metallurgical restrictions for WEEE recycling – consequences for the product design
Reuter, M. A.;
This lecture discusses facets of the article below.

Metals are an essential and critical component of today’s society: a moment’s reflection on their ubiquitous presence in virtually all energy and material production processes is enough to confirm this. Metals play a key role in Enabling Sustainability through societies various high-tech applications. However, the resources of our planet are limited, as is the strain to which we can subject it in terms of emissions, pollution, and disposal of waste. For these reasons, finding ways to lower the environmental footprint of our collective existence and therefore lowering greenhouse gas emissions and help mitigate climate change is a vital priority ([1], [2]). The maximization of resource efficiency [3] is the principal theme of this contribution. It will be shown in depth the detail that is required to systemically fully understand resource efficiency in the context of material use, illustrating this by example of E-waste recycling. The opportunities and limits of recycling are discussed with a specific emphasis on the physics and related economics of recycling. Through this Design for Resource Efficiency is elaborated on. In support of this, the detailed data that are required, the technological understanding and design rules are among others implicitly highlighted that impact on resource efficiency. Specifically the understanding of Product-Centric recycling is highlighted setting it apart from the usual Material-Centric recycling approaches (which focus more on bulk materials) and therefore inherently limit especially the maximal recovery of technologically critical elements - these limitations will be discussed.
  • Invited lecture (Conferences)
    Resources from Waste: Sorting and Treatment Techniques / ISWA Beacon Conference 2015, 14.-16.10.2015, Hamburg, Deutschland

Publ.-Id: 24613 - Permalink


Thermoacoustic MHD generator prototyping and experiments
Brekis, A.; Freibergs, J.; Gailitis, A.; Roy, E.; Jeantet, P.; Poli, G.; Zeminiani, E.; Francoism, M.-X.; Gerbeth, G.; Eckert, S.;
This paper describes a machine based on coupled thermo acoustic (TAc) and magnetohydrodynamic (MHD) generators, which are an innovating technology ideally free of moving parts. In Europe there is a strong expertise in thermo acoustic and MHD. But these technologies have never been coupled. Both engines have been manufactured and tested in Institute of Physics of University of Latvia (IPUL). At first MHD generator and TAc generator were tested separately and then both together. The aim of these tests was a validation of possibility of making sodium oscillations with external force, testing free surface stability of gas-liquid sodium and studying of TAc generator working principles in different conditions.
Keywords: MHD generator; thermo acoustic
  • Contribution to proceedings
    10. PAMIR International Conference, 20.-24.06.2016, Cagliari, Italien, 606-610

Publ.-Id: 24612 - Permalink


Focused Helium and Neon Ion Beam Modification of High-Tc Superconductors and Magnetic Materials
Cybart, S. A.; Bali, R.; Hlawacek, G.; Röder, F.; Fassbender, J.ORC
The ability of gas field ion sources (GFIS) to produce controllable inert gas ion beams with atomic level precision opens up new applications in nanoscale direct-write material modification. Two areas where this has recently been demonstrated is focused helium ion beam production of high-transition temperature (high-TC) superconductor electronics and magnetic spin transport devices. The enabling advance in the case of superconducting electronics is the ability to use the GFIS to make features on the small length-scale of quantum mechanical tunnel barriers. Because the tunneling probability depends exponentially on distance, tunnel barriers must be less than a few nanometers wide, which is beyond the limits of other nanofabrication techniques such as electron beam lithography. In magnetism, the GFIS has recently been used to generate chemical disordering and modify magnetic properties at the nanoscale. The strongest effect is observed in materials where ion-induced chemical disordering leads to increased saturation magnetization, enabling positive magnetic patterning. In this chapter, we review the latest results and progress in GFIS ion beam modification of (high-TC) superconductors and magnetic materials.
Keywords: GFIS-assisted modifications, superconductivity, magnetism
  • Book chapter
    Hlawacek, Gregor, Gölzhäuser, Armin: NanoScience and Technology, Heidelberg: Springer-Verlag GmbH, 2016, 978-3-319-41990-9, 415-445
    DOI: 10.1007/978-3-319-41990-9_17
  • Lecture (Conference)
    International Conference on Surface Modification of Materials by Ion Beams (SMMIB-2017), 09.-14.07.2017, Lisboa, Portugal
  • Lecture (Conference)
    International Baltic Conference on Magnetism 2017, 20.-24.08.2017, Kaliningrad, Russia

Publ.-Id: 24611 - Permalink


Measuring liquid flow in structured packings using gamma and x-ray tomography
Hoffmann, R.; Boden, S.; Schubert, M.; Hampel, U.;
Detailed knowledge of the liquid distribution in structured packings is an essential requirement for developing high-performance columns. Two different tomographic technologies are used to resolve the liquid distribution on different length scales. A variety of hydrocarbons, silicone oil and water can be used as model fluids.

For macroscopic measurements of the whole column cross-section (up to Ø 750 mm) a gamma tomograph has been built. The tomograph is qualified to operate in ATEX areas and can resolve liquid flow phenomena like wall flow, inlet flow distribution, crossover between packing blocks etc.

For microscopic measurements of flow details x-ray tomography is used. Using a voxel size of 41 μm the influence of the packing's geometry parameters on the liquid flow can be analyzed. The resulting data is also used for verification of corresponding two-phase flow CFD simulations.
Keywords: Structured packings, gamma tomography, x-ray tomography
  • Contribution to proceedings
    International Conference on Multiphase Flow, ICMF 2016, 22.-27.05.2016, Firenze, Italy
    ICMF2016 Proceedings
  • Lecture (Conference)
    International Conference on Multiphase Flow, ICMF 2016, 22.-27.05.2016, Firenze, Italy

Publ.-Id: 24610 - Permalink


Raw materials demand in a circular, low-carbon economy
Reuter, M. A.;
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    4th annual High-Level Conference of the European Innovation Partnership on Raw Materials / Raw Materials Week, 28.11.-02.12.2016, Brüssel, Belgien

Publ.-Id: 24609 - Permalink


Perspektiven einer Entsorgungsindustrie und Kreislaufwirtschaft 4.0
Reuter, M. A.;
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Industrie 4.0. - Chancen und Risiken für die Umwelt, 18.11.2016, Dessau-Roßlau, Deutschland

Publ.-Id: 24608 - Permalink


Short-pulse laser-driven x-ray radiography
Brambrink, E.; Baton, S.; Koenig, M.; Yurchak, R.; Bidaut, N.; Albertazzi, B.; Cross, J. E.; Gregori, G.; Rigby, A.; Falize, E.; Pelka, A.; Kroll, F.; Pikuz, S.; Sakawa, Y.; Ozaki, N.; Kuranz, C.; Manuel, M.; Li, C.; Tzeferacos, P.; Lamb, D.;
We have developed a new radiography setup with a short-pulse laser-driven x-ray source. Using a radiography axis perpendicular to both long- and short-pulse lasers allowed optimizing the incident angle of the short-pulse laser on the x-ray source target. The setup has been tested with various x-ray source target materials and different laser wavelengths. Signal to noise ratios are presented as well as achieved spatial resolutions. The high quality of our technique is illustrated on a plasma flow radiograph obtained during a laboratory astrophysics experiment on POLARs.
Keywords: laboratory astrophysics; short-pulse laser; x-ray radiography

Publ.-Id: 24607 - Permalink


Dispersion of nanaoparticles in metals using pulsed electromagnetic interaction
Bojarevics, A.; Kaldre, I.; Beinerts, T.; Grants, I.; Milgravis, M. M.; Kalvans, M.;
This research work is done to investigate the possibilities how to mix and disperse ceramic nanoparticles in liquid metals and keep them dispersed during solidification. We investigate contactless electromagnetic methods to produce metal matrix nano-composites. Dispersed particles improves mechanical and thermal properties of the metals by refining metallic grains and limiting crack propagation. We use intensive electromagnetic interaction from capacitor bank discharge to create pressure oscillations liquid metal which induces acoustic cavitation which then causes intensive micro-scale jet which is able to break particle agglomerates.
Keywords: liquid metals
  • Contribution to proceedings
    10. PAMIR International Conference, 20.-24.07.2016, Cagliari, Italy, 266-361

Publ.-Id: 24606 - Permalink


Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in an conductor
Grants, I.; Bojarevics, A.; Gerbeth, G.;
Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.
Keywords: magnetic field

Publ.-Id: 24605 - Permalink


Herausforderungen bei der bruchmechanischen Prüfung von oxiddispersionsverfestigten (ODS)-Cr-Stählen
Viehrig, H.-W.; Das, A.; Houska, M.; Hoffmann, J.;
Different oriented 0.25T- and 0.16T-C(T) specimens of hot rolled- and hot extruded 14Cr ODS steel were tested within the temperature range from 20°C to 700°C. Elastic-plastic fracture toughness values were estimated according to ASTM E1820 15 on J-∆a curves measured by the unloading compliance method. The rolled plate of 13Cr ODS had higher fracture toughness in L-T than in T-L orientation. The rolled ODS shows secondary cracks which were more pronounced for the L-T oriented C(T) specimens than for T-L orientation. The secondary cracks strongly influence the propagation of the main crack. The fracture toughness of the hot extruded 14 Cr ODS also strongly depend on the specimen orientation.
Keywords: ODS steel, temperature, C(T) specimen, crack extension curve, unloading compliance, fracture toughness
  • Contribution to proceedings
    49. Tagung des DVM Arbeitskreises Bruchmechanik und Bauteilsicherheit Bruchmechanische Werkstoff- und Bauteilbewertung: Beanspruchungsanalyse, Prüfmethoden und Anwendungen, 14.-15.02.2017, Mittweida, Deutschland, Berlin: DVM

Publ.-Id: 24604 - Permalink


Geometallurgie als integrative Prozessoptimierung
Reuter, M. A.;
Prof. Dr. Dr. h.c. Markus Reuter stellte in seinem Vortrag eine durchgeführte Bewertung der Ressourceneffizienz am Beispiel von LED-Lampen vor. In der Vorgehensweise wurden verschiedene Konstruktionen sowie Materialzusammensetzung untersucht und simuliert. Prof. Reuter betonte dabei, dass für den Vergleich komplexer Produkte auch komplexe Simulationen notwendig seien. Durch Simulationen unter Berücksichtigung des gesamten Lebenszyklus ließen sich bereits in der Entwicklungsphase von Produkten Konstruktion und Materialauswahl hinsichtlich der Recyclingfähigkeit optimieren. Da aufgrund technischer und chemischer Einschränkungen nicht alle Bestandteile vollständig zurückgewonnen werden könnten, sei eine Betrachtung von Recyclingprozessen auf metallurgischer Ebene notwendig, um ein ressourceneffizientes Recycling zu realisieren.
  • Invited lecture (Conferences)
    Produktentwicklung als Hebel für Ressourceneffizienz – Potenziale im Dialog zwischen Politik, produzierenden Unternehmen und Recyclingwirtschaft / 18. NeRess-Konferenz, 05.12.2016, Berlin, Deutschland

Publ.-Id: 24603 - Permalink


Geochemical analysis of the European Kupferschiefer – from method development to data assessment
Rahfeld, A.; Wiehl, N.; Möckel, R.; Gutzmer, J.;
The European Kupferschiefer is currently the world’s most important source of Ag and an important source of Cu, Au, Mo, Ni, Pb, Se and Re. Cu is the main product, with grades of 2.5 wt% Cu and 62 ppm Ag on average. The Kupferschiefer sensu strictu is a very fine-grained, finely laminated and fissile carbonaceous shale. Complex sulphide mineralogy, a great variety of clay minerals and very high organic carbon contents render mineralogical as well as geochemical characterization of the Cu-rich Kupferschiefer difficult. The availability of high quality whole rock geochemical data sets in the published literature is strictly limited. A detailed geochemical study was thus undertaken within the framework of the Ecometals project [1]. Within the context of this study, different analytical methods were compared and a suitable approach for a routine analytical protocol developed.

X-ray fluorescence (XRF) and inductively coupled plasma optical emission spectrometry (ICP-OES) were tested as potential techniques based on their availability and adaptability to analyse main (Al, Ca, Cu, Fe, K, Mg, Pb, Si, Zn) and trace (Ag, As, Ba, Co, Mo, Ni, Ti, V) element concentrations. It is known that both techniques can be susceptible to errors either caused by matrix effects in the material itself, sample preparation or interferences. To ascertain the accuracy of XRF and ICP-OES analysis, instrumental neutron activation analysis (INAA) was carried out at the TRIGA research reactor in Mainz.

Two approaches were tested in the digestion process for this material. Especially the organic carbon in the samples is known to be resistant, which is why Na-peroxide digestion within an HCl solution was used in addition to classic acid digestion based on HF and HNO3. The ICP-OES results show great accordance to the ones measured by INAA for both acid and peroxide digestion, although a complete digestion was only achieved by peroxide digestion and is reflected in slightly increased Cu concentrations.

Further information needs to be taken into consideration when working with XRF pressed pellets. To process the data correctly, knowledge about the mineralogical composition is necessary to distinguish between oxide and sulphide compounds. The total organic carbon content (TOC) needs to be determined independently and used to correct the XRF data. A preceding calcination of the material can not be recommended and should be approached with caution. The copper sulphides start sintering at temperatures above 780°C and ruin any crucible.

In accordance with the results, both acid and peroxide digestion with subsequent ICP-OES analysis can be recommended for the analysis of Kupferschiefer. Whilst ICP-OES measurements and the sample preparation through digestion are more time consuming compared to the ones used for XRF, the data quality is better and there is no explicit requirement for additional TOC data, mineralogical measurements or data correction.
  • Lecture (Conference)
    International Geological Congress, 28.08.-02.09.2016, Cape Town, South Africa

Publ.-Id: 24602 - Permalink


Organische Chemie VI - Stoffklassen und funktionelle Gruppen V
Mamat, C.;
Im letzten Studienheft des großen ersten Abschnittes der organischen Chemie wollen wir uns mit wichtigen Stoffklassen beschäftigen, die auch in Molekülen aus der Natur vorhanden sind. Sie werden staunen, dass die funktionellen Gruppen, die wir uns bisher angeschaut haben, zu einem Großteil in diesen biologisch aktiven Molekülen wiederzufinden sind. Zwei große Klassen von Biomolekülen stehen da im Vordergrund: die Kohlenhydrate und die Aminosäuren bzw. deren makromolekulare Kondensationsverbindungen, die Peptide und Proteine. Ausgehend davon werden wir noch einen Blick auf die Heterocyclen werfen, da sie ebenfalls in einer Vielzahl von Biomolekülen und auch pharmazeutischen Produkten und Verbindungen vorkommen und damit eine große Rolle als Wirkstoffe in der Biochemie spielen.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0034 Seiten

Publ.-Id: 24601 - Permalink


Organische Chemie V - Stoffklassen und funktionelle Gruppen IV
Mamat, C.;
Im 4. Studienheft haben wir wichtige Reaktionen rund um die Carbonylgruppe kennengelernt. Generell beginnen alle Reaktionen immer mit einem nucleophilen Angriff auf das sp2-hybridisierte und elektrophile Carbonyl-C-Atom unter Ausbildung eines sp3-hybridiserten C-Atoms. Die Hybridisierung des C-Atoms bleibt erhalten (Reduktion, Hydrierung, Acetalisierung) oder sie wird wieder zurückgebildet zu sp2, wie bei Veresterungen oder Amidierungen im Sinne eines Additions-Eliminierungs-Mechanismus. Dieser Austausch am Carbonyl-C-Atom unterscheidet sich mechanistisch jedoch grundlegend von den SN-Reaktionen am gesättigten (sp3) C-Atom. Bitte beachten Sie das!
Des Weiteren haben wir ausgearbeitet, dass die α-Position (also die Position in Nachbarschaft der C=O-Gruppe) der Ketone und Aldehyde eine ganz besondere Reaktivität besitzt, im Vergleich zu den restlichen C-Atomen der organischen Substituenten an der C=O-Gruppe.
Genau an dieser Stelle wollen wir ansetzen und weitere wichtige Reaktionen und damit verbundene Stoffklassen kennenlernen, die auch mehr als eine funktionelle Gruppe tragen.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0032 Seiten

Publ.-Id: 24600 - Permalink


Organische Chemie IV - Stoffklassen und funktionelle Gruppen III
Mamat, C.;
Im letzen Heft haben wir gelernt, welche Reaktionen an nicht-aktivierten (einfachen) Doppelbindungen durchgeführt werden und welche Verbindungen daraus entstehen. In diesem Heft wollen wir schauen, was für Reaktionen möglich sind, wenn die Doppelbindung aus einem Kohlenstoffatom und einem Heteroatom (in der Hauptsache: Sauerstoff) besteht. Die Grundlagen dieser aktivierten Doppelbindungen dem 1. Studienheft wollen wir jetzt erweitern und schauen wie der gebildete Dipol die Reaktivität und Reaktionen an diesen Doppelbindungen beeinflusst. Wir suchen Analogien und Unterschiede zu den Reaktionen am gesättigten C-Atom und wollen sehen, wie wir zu solchen ungesättigten Systemen ausgehend aus den gesättigten kommen. Daraus ergeben sich weitere, neue funktionelle Gruppen und Substanzklassen, die wir ebenfalls beleuchten wollen.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0034 Seiten

Publ.-Id: 24599 - Permalink


Organische Chemie III - Stoffklassen und funktionelle Gruppen II
Mamat, C.;
Die einfachen Kohlenwasserstoffe haben wir im letzten Heft kennengelernt, und auch welche generelle Reaktionen am gesättigten C-Atom möglich sind. Dabei sind wir auf die große Gruppe der Halogenalkane gestoßen und haben deren Eigenschaften und Reaktionen angeschaut und ebenfalls die Eigenschaften und Grundreaktionen mit ungesättigten Verbindungen ohne Heteroatom. Wir haben auch gesehen, dass Heteroatome in Abhängigkeit von ihrer Elektronegativität zur Polarisierung der Bindung beitragen. Somit kann diese heterolytisch gespalten werden. Unter dieser Voraussetzung sind nucleophile Substitutionen an diesem Kohlenstoffatom möglich, aber auch Eliminierungsreaktionen zur Erzeugung von Mehrfachbindungen.
In diesem Heft wollen wir uns speziell mit Stoffeigenschaften der Alkohole, Ether, Thioalkohole, Thioether und Amine beschäftigen und wie wir diese Verbindungen generell synthetisieren bzw. diese funktionellen Gruppen erhalten können. Die Grundlage für dieses Heft bilden die zuvor besprochenen nucleophilen Substitutionsreaktionen. Des Weiteren werden wir sehen, welche Nebenreaktionen bei der Synthese dieser Verbindungsklassen auftreten und unter welchen Bedingungen sie verhindert oder begünstigt werden können.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0030 Seiten

Publ.-Id: 24598 - Permalink


Organische Chemie II, Stoffklassen und funktionelle Gruppen I
Mamat, C.;
Ab jetzt geht es in die Tiefe. Nach den allgemeinen Grundlagen und Informationen rund um den Kohlenstoff wollen wir uns im zweiten Heft ausführlich mit den einfachen Kohlenwasserstoffen und deren Reaktionsmöglichkeiten auseinandersetzen und schauen, was es mit Doppel- und Dreifachbindungen auf sich hat. Dann werfen wir einen Blick auf die Auswirkungen auf Reaktionen, insbesondere wenn Halogene am Kohlenstoff gebunden sind. Wir werden sehen, welche generellen Möglichkeiten es für Reaktionen am gesättigten Kohlenstoffatom gibt. Neben diesen Austausch- bzw. Substitutionsreaktionen lassen sich aus Halogenalkanen oder Alkoholen auch Eliminierungen durchführen unter Abspaltung von kleinen Molekülen und unter Bildung von Alkenen und Alkinen, wodurch ungesättigte Derivate entstehen. Welche Auswirkungen die Doppel- und Dreifachbindungen auf den Kohlenstoff und auf seine Reaktionen haben, besonders wenn elektronegative Atome in Nachbarschaft zu dieser Mehrfachbindung stehen, sehen wir uns an. Aromaten sind die letzte Stoffklasse in diesem Heft. Auf deren Eigenschaften und besondere Reaktionen im Vergleich zu den nichtaromatischen und/oder acyclischen Kohlenwasserstoffen gehen wir ebenfalls ein.
  • Book (Authorship)
    Heidelberg: Springer-Verlag, 2016
    0034 Seiten

Publ.-Id: 24597 - Permalink


Two-dimensional oscillations in MHD Rayleigh-Benard convection
Tasaka, Y.; Fujita, K.; Yanagisawa, T.; Vogt, T.; Sakuraba, A.; Eckert, S.;
Short-period oscillations on convection rolls in Rayleigh-Bénard convection affected by a horizontal magnetic field confined in moderate aspect ratio box were invested experimentally. Detailed measurements of temperature and velocity fluctuations corresponding to the oscillations elucidated that the oscillation around its onset is two dimensional and may be originated in absolute instability of recirculation vortices formed flow separations due to large inertia of the main convection rolls restricted by Lorenz force.
Keywords: Rayleigh-Benard convection, liquid metal, magnetic field, flow measurements, ultrasound Doppler method
  • Lecture (Conference)
    24th International Congressof Theoretical and Applied Mechanics, 21.-26.08.2016, Montreal, Canada

Publ.-Id: 24596 - Permalink


Recycling’s Opportunities and Limits for a Circular Economy
Reuter, M. A.;
This lecture discusses facetes of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Opportunities and Limits of Recycling / Recycling Valley Innovative Reverse Metallurgy in Wallonia and in Europe, 21.11.2016, Liège, Belgium
  • Invited lecture (Conferences)
    Recycling von Edel- und Sondermetallen voranbringen / UBA-Workshop, 02.11.2015, Berlin, Deutschland

Publ.-Id: 24595 - Permalink


Measurements of a three-dimensional flow in a cube by means of an ultrasound array Doppler velocimeter (UADV)
Nauber, R.; Galindo, V.; Franke, S.; Räbiger, D.; Büttner, L.; Thieme, N.; Beyer, H.; Czarske, J.; Eckert, S.;
Velocity measurements were carried out in a cube filled with the liquid metal GaInSn using a dual plane, two-component ultrasound array Doppler velocimeter. The liquid metal was suddenly exposed to an azimuthal body force generated by a rotating magnetic field (RMF). The measurements show a similar flow structure compared to the case of the RMF-driven flow in a cylindrical container, in particular the so-called initial adjustment phase followed by an inertial phase which is dominated by inertial oscillations of the secondary flow. The interest was especially focused on the onset of unsteady flow regimes. The transition from the steady double vortex structure of the secondary flow to an oscillating regime was detected at a magnetic Taylor number of Ta > 1.3  105. A detailed analysis of the flow structure was done by means of the Proper Orthogonal Decomposition (POD). Corresponding numerical simulations were performed showing an excellent agreement with the experimental data.
Keywords: Flow measurements, liquid metal, Ultrasound Doppler method, sensor array, rotating magnetic field
  • Lecture (Conference)
    10th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 28.-30.09.2016, Tokyo, Japan
  • Contribution to proceedings
    10th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 28.-30.09.2016, Tokyo, Japan

Publ.-Id: 24594 - Permalink


Circular Economy: New wording or Real Policy?
Reuter, M. A.;
This lecture discusses facets of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions. The author stands humbly on the shoulders of these developments and their distinguished developers. This award lecture article implicitly also refers to work done while working for Ausmelt (Australia), Outotec (Finland and Australia), Mintek (South Africa), and Anglo American Corporation (South Africa), honoring the many colleagues the author has worked with over the years.
  • Invited lecture (Conferences)
    Resourcing the Future / Beacon Conference on Waste Minimisation and Recycling, 15.-17.06.2016, Oslo, Norway

Publ.-Id: 24593 - Permalink


Metallurgy a key enabler of a Circular Economy Challenges & Developments
Reuter, M. A.;
This lecture discusses facets of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Metallische Rohstoffe in der Zukunft - Prozessvisionen für Ressourceneffizienz / 55. Tutzing-Symposion 2016, 06.-07.06.2016, Tutzing, Deutschland

Publ.-Id: 24592 - Permalink


Aufbereitung und Recycling – Schlüsselfaktoren der Gewinnung primärer und sekundärer Rohstoffe – Herausforderungen und Entwicklungen
Reuter, M. A.;
This lecture discusses facets of the article below.

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions.
  • Invited lecture (Conferences)
    Die Zukunft beginnt mit dem Rohstoff – Herausforderungen für die internationale Rohstoffwirtschaft / 10. Sächsischer Rohstofftag, 25.05.2016, Dresden, Deutschland

Publ.-Id: 24591 - Permalink


Öffentliche Abendvorträge - "Wir kommen wieder!"
Merchel, S.; für die Veranstalter;
Naturwissenschaftliche Einsichten in Kunst- und Kulturgut
Keywords: Archäometrie
  • Mitteilungsblatt der Fachgruppe Analytische Chemie der Gesellschaft Deutscher Chemiker (2016)04, 14-15

Publ.-Id: 24590 - Permalink


Fragmentation-driven grain refinement in directional solidification of AlCu10wt-% alloy at low pulling speeds
Zimmermann, G.; Pickmann, C.; Hamacher, M.; Schaberger-Zimmermann, E.; Neumann-Heyme, H.; Eckert, K.; Eckert, S.;
The formation of the grain structure in Al-10wt%Cu alloy during directional solidification was investigated experimentally. The alloy composition was chosen because of its special feature that both the initial melt composition and the solidifying primary Al dendrites have almost identical densities. Therefore, gravity-related effects such as buoyancy or sedimentation acting on nucleated or fragmented solid particles in the melt are expected to be minor. In 3D bulk samples at low solidification velocities, unexpected equiaxed grain growth was found instead of columnar growth. This behavior was investigated in accompanying solidification experiments with thin samples using in-situ X-ray diagnostics. It is demonstrated that fragments detach from the dendrite tip region and move slightly ahead of the solid-liquid interface as they grow. As a result, a dendritic microstructure consisting of elongated equiaxed grains is developed. Accordingly, fragmentation was identified as responsible for grain refinement in the given parameter range.
Keywords: solidification, fragmentation, grain refinement, X-ray radiography

Publ.-Id: 24589 - Permalink


A generalized multi-field two-fluid concept for numerical simulation of two-phase flows
Oertel, R.; Lucas, D.; Schlegel, F.;
Multiphase flows occur in a variety of industrial applications, e.g. in chemical engineering or in nuclear research. An important feature of these flows is the formation of different flow patterns depending on the relative flow rates of the phases. These patterns are not explicitly defined by the and have different characteristics. Past research on the simulation of multiphase flows mainly focused on establishing methods that are appropriate within a well-defined flow regime. The present contribution aims at the development of a generalized framework in OpenFOAM for the simulation of industrial scale multiphase flows with largely varying interfacial length scales, which has the capability to reproduce the mechanisms of flow pattern transitions. For the simulation of disperse flows, the two-fluid approach, where each phase is represented by its own phase-averaged velocity field, is widely accepted. This concept serves as a basis and is extended to allow interface-resolving simulations for large gas structures, while disperse phase elements are still represented in terms of a number density function. The present contribution focuses on two parts. Firstly, one feature of multiphase flow pattern transitions is the inherent polydispersity of the occurring gas structures. The difference in diameter between the smallest and the largest elements spans over at least one order of magnitude. In general, this aspect is taken into account by population balance modeling. A successful and stable method for this purpose is the method of classes which will be utilized here, following the ideas of the GENTOP-approach of Hänsch et al. (2012). Since lift-force induced separation of bubbles according to their size is considered as an important mechanism for the transition from bubbly to slug flow, particular emphasis is put on employing a class method which also takes different velocity fields for the disperse phase into account. The second part focuses on the handling of interface-resolving gas structures within the two-fluid model. Beside the aspect of interface sharpening to counteract the numerical diffusion, the momentum exchange between the separate velocity fields is important. In reality, the phases share a single velocity field and a no-slip condition is present at the interface. This condition can also be met in a two-fluid model by forcing the velocity of the two phases to be equal at interface. However, as such a method requires a high grid resolution, we introduce a direction depended model for the momentum exchange at the interface, that accounts separately for pressure and friction induced drag. Finally, the presented framework allows the simulation of multiphase flow problems close to an industrial scale and gives realistic predictions, even on a coarse grid.
  • Lecture (Conference)
    4th OpenFOAM User Conference 2016, 11.-13.10.2016, Köln, Deutschland

Publ.-Id: 24588 - Permalink


Electrically Tunable Nd:YAG waveguide laser based on Graphene
Ma, L.; Tan, Y.; Akhmadaliev, S.; Zhou, S.; Chen, F.;
We demonstrate a tunable hybrid Graphene-Nd:YAG cladding waveguide laser exploiting the electrooptic and the Joule heating effects of Graphene. A cladding Nd:YAG waveguide was fabricated by the ion irradiation. The multi-layer graphene were transferred onto the waveguide surface as the saturable absorber to get the Q-switched pulsed laser oscillation in the waveguide. Composing with appropriate electrodes, graphene based capacitance and heater were formed on the surface of the Nd:YAG waveguide. Through electrical control of graphene, the state of the hybrid waveguide laser was turned on or off. And the laser operation of the hybrid waveguide was electrically tuned between the continuous wave laser and the nanosecond pulsed laser.

Publ.-Id: 24587 - Permalink


INTRA r³+ - Integration und Transfer der r³ Fördermaßnahme
Dürkoop, A.; Büttner, P.; Albrecht, S.; Brandstetter, C. P.; Erdmann, M.; Gräbe, G.; Moller, B.; Höck, M.; Kleeberg, K.; Rentsch, L.; Schneider, K.; Ostertag, K.; Pfaff, M.; Sartorius, C.; Tercero Espinoza, L.; Szurlies, M.; Wilken, H.;
Die r³ Fördermaßnahme wurde von Ende 2011 bis Anfang 2016 durch das Bundesministerium für Bildung und Forschung (BMBF) mit 30 Mio. € gefördert. Zusätzlich wurden 12 Mio. € Industriemittel in den r³ Verbundprojekten eingesetzt. Die insgesamt 28 r³ Verbundprojekte forschten daran, wie nicht-energetische mineralische Rohstoffe zukünftig effizienter genutzt werden können (Bild 1). Bundesweit waren mehr als 120 Partner in r³ eingebunden, darunter zahlreiche Forschungseinrichtungen und Behörden sowie 69 Industrieunternehmen. Der Fokus von r³ lag auf den für Deutschland wirtschaftsstrategisch wichtigen Metallen [BMBF 2012] wie z.B. Indium, Germanium, Gallium und seltene Erden (SEE), aber auch Industrieminerale wie beispielsweise Flussspat, die zukünftig effizienter gewonnen, recycelt und in Produkten verwendet werden sollen. Diese strategischen Metalle und Mineralien werden vor allem für die Herstellung von Hightech-Produkten (Handys, Laptops, Touchscreens, LCDs usw.) und Energiesparlampen, aber auch für Dauermagnete benötigt.
Wenn auch die metallischen Ressourcen nicht in großen Mengen verwendet werden, so sind sie doch wirtschaftsstrategisch von großer Bedeutung [BMBF 2010]. Eine unsichere Versorgungslage für diese strategischen Rohstoffe in Deutschland könnte zu Versorgungsengpässen im Rohstoffimportland Deutschland führen. Die Ergebnisse aus r³ zeigen, dass die Versorgungslage für einige dieser Rohstoffe für Deutschland zukünftig verbessert werden könnte.
Die Bewertung der Ergebnisse aus r³ erfolgte im Rahmen des Projekts INTRA r³+ (Bild 2) unter Leitung des Helmholtz-Instituts Freiberg für Ressourcentechnologie (HIF). Zur Bewertung der Nachhaltigkeit der r³ Ergebnisse wurden zum einen ökonomisch-ökologisch-soziale Aspekte analysiert und zum anderen gesamtwirtschaftliche Betrachtungen durchgeführt sowie die Versorgungssicherheit bewertet. Zudem wurde die Vernetzung der r³ Verbundprojekte untereinander aber auch mit externen Initiativen und Projekten mit diversen Maßnahmen angeregt. Darüber hinaus wurden Arbeiten und Ergebnisse öffentlichkeitswirksam publiziert und ein Technologietransfer in die Wirtschaft vorbereitet. Partner von INTRA r3+ sind neben dem HIF die Technische Universität Bergakademie Freiberg (TUBAF), die Abteilung Ganzheitliche Bilanzierung des Lehrstuhls für Bauphysik (LBP) der Universität Stuttgart, das Fraunhofer Institut für System- und Innovationsforschung (ISI), das Fraunhofer-Institut für Chemische Technologie (ICT) und die Deutsche Rohstoffagentur (BGR/DERA).
Keywords: Ressourcentechnologie, Nachhaltigkeit, strategische Metalle
  • Open Access LogoBook chapter
    A. Dürkoop, C. P. Brandstetter, G. Gräbe, L. Rentsch: Innovative Technologien für Ressourceneffizienz - Strategische Metalle und Mineralien, Stuttgart: Fraunhofer Verlag, 2016, 978-3-8396-1102-9

Publ.-Id: 24585 - Permalink


Non-ferrous metallurgy: Key enabler of a circular economy
Reuter, M. A.;
Base metals such as copper, lead, nickel, cobalt, zinc etc. form the basic crucial carrier metals for a sustainable society – the Web of Metals. The lecture discusses the special and crucial role these metals have in acting as enablers in any recycling efforts as they carry and release important and vital minor elements at the heart of high-tech applications and products. Through examination of the rising needs for such carriers, this lecture examines the approach and technologies which need to be considered by any producer of base metals. Attention is paid to the limits and extent of this carrier role in the typical processing of materials.
Examples of specialised technology and flowsheet needs are presented with consideration given to a “whole of chain” or Systems-Integrated Metal Production (SIMP) approach as a cornerstone of a circular economy. Also outlined are the challenges facing not only producers, but legislators who need to consider the balance between providing our societal needs with baseline technology infrastructure requirements for valuable metals extraction. In summary, the message of this paper states simply that not only is the criticality of metals important but the criticality of the infrastructure (Infrastructure Criticality) that can recover metals from complex designed “mineral” mixtures. Base metals are at the heart of a Circular Economy, therefore key enablers of the Internet-of-Metallurgical-Things.
Keywords: Resource efficiency base metals, Recycling, System integration, Design for Recycling (DfR)
  • Invited lecture (Conferences)
    International Conference Recycling of Non-Ferrous Metals under the Patronage of President of KGHM Polska Miedz S. A. Herbert Wirth, 02.-04.03.2016, Krakow, Polen

Publ.-Id: 24584 - Permalink


Qualifizierung von CFD-Methoden für die Nukleare Sicherheitsforschung
Lucas, D.;
The presentation gives an overview about the actual work in the department "Computationa Fluid Dynamics" of the Institute of Fluid Dynamics
Keywords: CFD, two phase flow, model development
  • Invited lecture (Conferences)
    Fachtagung der KTG-Fachgruppen, 17.-18.11.2016, KIT, Eggenstein-Leopoldshafen, Deutschland

Publ.-Id: 24583 - Permalink


Model Developments to predict the Critical Heat Flux
Krepper, E.; Ding, W.;
The presentation gives an overview on CFD-model delvelopments to predict the critical heat flux. Boiling is a very effective heat transfer mechanism but limited to the critical heat flux. The correct simulation of this phenomenon contributes to the safely and economical operation of energy generating facilities. Heat flux partition algorithms are presented. A more detailed description of the phenomena in the bulk is shown. Actual tendencies for the correct simulation of the microscopic phenomena by sublayer models are described.
Keywords: CFD, two phase flow, heat and mass transfer, boiling, critical heat flux
  • Invited lecture (Conferences)
    Fachtagung der KTG-Fachgruppen, 17.-18.11.2016, KIT, Eggenstein-Leopoldshafen, Deutschland

Publ.-Id: 24582 - Permalink


Quantum Interference Controlled Current in InSb Injected by intense Terahertz Radiation
Bühler, J.; Schmidt, C.; Fischer, J.; Leitenstorfer, A.; Schneider, H.; Helm, M.; Pashkin, A.; Seletskiy, D. V.;
Quantum interference between one- and two-photon absorption pathways is exploited for all-optical injection of charge current in InSb at 10 K. Polar-asymmetric excitation is synthesized by superposing intense output from a free electron laser centered at 31 THz with the phase-locked second harmonic. The relative phase between the two frequency components controls the directionality of the injected current. This demonstration motivates applications of intense synthetic pulses for resonant excitation, control and probing of various low-energy and correlated degrees of freedom.
Keywords: free-electron laser, optical current injection, coherent control

Publ.-Id: 24581 - Permalink


Nonlinear Multi-Terahertz Excitation of Strongly Correlated Materials
Pashkin, A.;
Invited talk at the Gordon Reserach Conference "Ultrafast Phenomena in Cooperative Systems"
Keywords: nonlinear THz spectroscopy, strongly correlated systems, high-field THz pulses
  • Invited lecture (Conferences)
    Gordon Research Conference "Ultrafast Phenomena in Cooperative Systems", 14.-19.02.2016, Lucca (Barga), Italy

Publ.-Id: 24580 - Permalink


FEL-based nonlinear THz spectroscopy at the ELBE accelerator
Pashkin, A.;
Invited talk at the workshop on an accelerator based source for nonlinear THz science at SwissFEL. Organized by the Paul-Scherrer-Institut.
Keywords: free-electron laser, high-field THz spectroscopy
  • Invited lecture (Conferences)
    Workshop on an accelerator based source for nonlinear THz science @ SwissFEL, 03.-04.10.2016, Windisch, Switzerland

Publ.-Id: 24579 - Permalink


Recycling 4.0: Circular Economy Engineering & Metallurgy
Reuter, M. A.;
CE: Circular Economy
Energy and materials: Product Centric Recycling–
Circular Economy within a Corporation

SIMP: System Integrated Metal Production
- Metallurgical infrastructure & knowledge of key importance
- Internet-of-Metallurgical-Things – Web of Metals

CEE: Circular Economy Engineering – Recycling 4.0
– Digitalized link of all stakeholders
– Quantification of resource efficiency
– Informing society in an understandable CE-paradigm
  • Invited lecture (Conferences)
    Sustainable metals recovery from electronic waste, 08.-10.02.2016, Perth, Australien

Publ.-Id: 24578 - Permalink


Process Metallurgy: A key enabler of a Circular Economy
Reuter, M. A.;
Base metals such as copper, lead, nickel, cobalt, zinc etc. form the basic crucial carrier metals for a sustainable society – the Web of Metals. This paper discusses the special and crucial role these metals have in acting as enablers in any recycling efforts as they carry and release important and vital minor elements at the heart of high-tech applications and products. Through examination of the rising needs for such carriers, this paper examines the approach and technologies which need to be considered by any producer of base metals. Attention is paid to the limits and extent of this carrier role in the typical processing of materials.
Examples of specialised technology and flowsheet needs are presented with consideration given to a “whole of chain” or Systems-Integrated Metal Production (SIMP) approach as a cornerstone of a circular economy. Also outlined are the challenges facing not only producers, but legislators who need to consider the balance between providing our societal needs with baseline technology infrastructure requirements for valuable metals extraction. In summary, the message of this paper states simply that not only is the criticality of metals important but the criticality of the infrastructure (Infrastructure Criticality) that can recover metals from complex designed “mineral” mixtures. Base metals are at the heart of a Circular Economy, therefore key enablers of the Internet-of-Metallurgical-Things.
Keywords: Resource efficiency base metals, Recycling, System integration, Design for Recycling (DfR)
  • Invited lecture (Conferences)
    Resourcing Future Generations Symposium / International Geological Conference ICG35, 27.08.-04.09.2016, Kapstadt, Südafrika

Publ.-Id: 24577 - Permalink


Formation of Co nanodisc with enhanced perpendicular magnetic anisotropy driven by Ga+ ion irradiation on Pt/Co/Pt films
Sakamaki, M.; Amemiya, K.; Sveklo, I.; Mazalski, P.; Liedke, M. O.; Fassbender, J.ORC; Kurant, Z.; Wawro, A.; Maziewski, A.
The origin of magnetic phase transition from in-plane to perpendicular magnetic anisotropy (PMA) of Pt/Co/Pt thin film by Ga+ ion irradiation at fluences of 1-5 x 10(15) ions/cm(2) is investigated by means of x-ray magnetic circular dichroism (XMCD) and extended x-ray absorption fine structure (EXAFS) analyses. We find that Pt and Co atoms are mixed with each other and that Co is oxidized near the surface due to removal of the Pt overlayer. Furthermore, polarization-dependent EXAFS analysis shows that Co is firstly dispersed as separated single-atom-thick sheets in a Pt matrix at 1 x 10(15) ions/cm(2), then the Co sheets are divided into a few angstrom clusters at 5 x 10(15) ions/cm(2), which are regarded as nanodiscs parallel to the film plane. This process is accompanied by the appearance of an out-of-plane magnetization component and a remanence peak is observed. Because we do not observe an enhancement in anisotropy of Co orbital moment which leads to change in magnetic anisotropy through the transition at about 5 x 10(15) ions/cm(2), it might be possible that such nanodisc formation induces increase of magnetic anisotropy via a shape effect. By comparing with the phase transition observed at lower fluence [Phys. Rev. B 86, 024418 (2012)], we find that the mechanism of two transitions is different, i.e., the transition at lower fluence is caused by anisotropy of orbital moment due to structural strain, while the present transition is possibly by shape effect due to nanodisc formation.

Downloads:

Publ.-Id: 24576 - Permalink


Opportunities and limits of metal recycling within a circular economy
Reuter, M. A.;
Metallurgy is at the heart of developing a circular economy as metals all have strong intrinsic recycling potentials. Moving towards closed material-loops requires for the metallurgical industry to continue to refine its processing methods and adapt to the changing and ever complicating waste fractions.
  • Invited lecture (Conferences)
    Metal recycling, opportunities and limits / MiMa Meeting, 26.05.2016, Copenhagen, Denmark

Publ.-Id: 24575 - Permalink


Stability of uranium(VI) doped CSH phases in high saline water
Wolter, J.-M.; Schmeide, K.; Stumpf, T.;
To evaluate the long-term stability of U(VI) doped CSH phases at high saline conditions, leaching experiments with NaCl, NaCl/Na2SO4 and NaCl/NaHCO3 containing solutions were performed. Time-resolved laser-induced fluorescence spectroscopy (TRLFS), infrared spectroscopy (IR) and X-ray powder diffraction (XRD) were applied to study the U(VI) binding onto the CSH phases and to get a deeper understanding of structural changes due to leaching. Results indicate that neither NaCl nor Na2SO4 affect the structural stability of CSH phases and their retention potential for U(VI). However, carbonate containing solutions lead to a decomposition of CSH phases and thus, to a release of uranium.
Keywords: CSH, stability, uranium, U(VI), saline water, sodium chloride, carbonate, sulfate, TRLFS, IR, PXRD
  • Lecture (others)
    Kompetenzzentrum Ost für Kerntechnik Seminar für Doktoranden und Nachwuchswissenschaftler, 08.12.2016, Dresden-Rossendorf (HZDR), Deutschland

Publ.-Id: 24574 - Permalink


Transient eddy current flow metering: a calibration-free measurement technique for liquid metals
Krauter, N.; Forbriger, J.; Stefani, F.;
Eddy Current Flow Meters (ECFM) are widely used for the contactless measurement of the velocity of conductive fluids, but extensive calibration is necessary in order to get accurate results. The measured magnitudes or phase shifts are also influenced by the temperature dependent electrical conductivity. A new approach to this kind of velocity measurement is Transient Eddy Current Flow Metering (TEC-FM), which yields the fluid velocity without prior calibration. With this sensor concept it is possible to track the position of an imprinted eddy current system, which is moving with the same velocity as the conductive fluid, and thereby eliminating the need for additional calibration and temperature compensation. We delineate the basic principle of the technique, present one specific sensor configuration, and discuss first experimental results.
Keywords: inductive flow measurement, eddy current, calibration-free
  • Contribution to proceedings
    10th PAMIR International Conference Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italien
    Proceedings of the 10th PAMIR International Conference Fundamental and Applied MHD, University of Cagliari: Department Electrical and Electronic Engineering, 978-88-90551-93-2, 48-51
  • Lecture (Conference)
    10th PAMIR International Conference Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italien

Publ.-Id: 24573 - Permalink


Accumulative Magnetic Switching of Ultrahigh-Density Recording Media by Circularly Polarized Light
Takahashi, Y. K.; Medapalli, R.; Kasai, S.; Wang, J.; Ishioka, K.; Wee, S. H.; Hellwig, O.; Hono, K.; Fullerton, E. E.;
Magnetization control of ferromagnetic materials only by circularly polarized light has received increasing attention both as a fundamental probe of the interactions of light and magnetism but also for future highdensity magnetic recording technologies. Here we show that for granular FePt films designed for ultrahighdensity magnetic recording, the optical magnetic switching by circularly polarized light is an accumulative effect from multiple optical pulses. The measured results can be reproduced by a simple statistical model where the probability of switching a grain depends on the helicity of the optical pulses.We further show the deterministic switching of high-anisotropy materials by the combination of circularly polarized light and modest external magnetic fields, thus, revealing a pathway towards technological implementation.

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Publ.-Id: 24572 - Permalink


Helicity and field dependent magnetization dynamics of ferromagnetic Co/Pt multilayers
Tsema, Y.; Kichin, G.; Hellwig, O.; Mehta, V.; Kimel, A. V.; Kirilyuk, A.; Rasing, T.;
We present helicity and field dependent magnetization dynamics of ferromagnetic Co/Pt multilayers, suitable for all-optical helicity-dependent switching. Employing single-shot time-resolved magnetooptical Kerr effect imaging, our study demonstrates an ultra-fast quenching of the magnetization after a single 60 fs laser pulse excitation followed by a recovery. Full demagnetization occurs within 1 ps after laser excitation. The magnetization dynamics reveals a small helicity dependence caused by magnetic circular dichroism. When an external magnetic field is applied, a heat-assisted magnetization reversal occurs on a nanosecond time scale.

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Publ.-Id: 24571 - Permalink


Untersuchungen zum Komplexierungsverhalten modifizierter Calix[4]arene gegenüber Uran(VI) und Thorium(IV)
Bauer, A.; Schmeide, K.;
Projekttreffen des BMBF Verbundprojektes "SE-FLECX"
Präsentation spektroskopischer und mikrokalorimetrischer Studien zur Wechselwirkung von Calix[4]aren-basierten Liganden mit Uran(VI) und Thorium(IV).
Keywords: Calix[4]arene, Uran(VI), Thorium(IV)
  • Lecture (others)
    Projekttreffen des BMBF Verbundprojektes "SE-FLECX", 15.11.2016, Dresden-Rossendorf, Deutschland

Publ.-Id: 24570 - Permalink


Influence of chemical ordering on the thermal conductivity and electronic relaxation in FePt thin films in heat assisted magnetic recording applications
Giri, A.; Hunwee, S.; Jain, S.; Hellwig, O.; Hopkins, P. E.;
We report on the out-of-plane thermal conductivities of tetragonal L10 FePt (001) easy-axis and cubic A1 FePt thin films via time-domain thermoreflectance over a temperature range from 133K to 500K.
The out-of-plane thermal conductivity of the chemically ordered L10 phase with alternating Fe and Pt layers is ~23% greater than the thermal conductivity of the disordered A1 phase at room temperature and below. However, as temperature is increased above room temperature, the thermal conductivities of the two phases begin to converge. Molecular dynamics simulations on model FePt structures support our experimental findings and help shed more light into the relative vibrational thermal transport properties of the L10 and A1 phases. Furthermore, unlike the varying temperature trends in the thermal conductivities of the two phases, the electronic scattering rates in the out-of-plane direction of the two phases are similar for the temperature range studied in this work.

Publ.-Id: 24569 - Permalink


Model-based magnetization retrieval from holographic phase images
Röder, F.; Vogel, K.; Wolf, D.; Hellwig, O.; Wee, S. H.; Wicht, S.; Rellinghaus, B.;
The phase shift of the electron wave is a useful measure for the projected magnetic flux density of magnetic objects at the nanometer scale. More important for materials science, however, is the knowledge about the magnetization in a magnetic nano-structure. As demonstrated here, a dominating presence of stray fields prohibits a direct interpretation of the phase in terms of magnetization modulus and direction. We therefore present a model-based approach for retrieving the magnetization by considering the projected shape of the nano-structure and assuming a homogeneous magnetization therein. We apply this method to FePt nano-islands epitaxially grown on a SrTiO3 substrate, which indicates an inclination of their magnetization direction relative to the structural easy magnetic [001] axis. By means of this real-world example, we discuss prospects and limits of this approach.
Keywords: off-axis electron holography, magnetic imaging, FePt nano-structured film

Publ.-Id: 24568 - Permalink


Ultrafast dynamics in VO2 under high pressures
Braun, J. M.; Schneider, H.; Helm, M.; Boatner, L. A.ORC; Marvel, R. E.; Haglund, R. F.; Pashkin, A.
Ultrafast dynamics in VO2 under high pressures
Keywords: optical pump - THz probe spectroscopy, insulator-to-metal transition, high pressure, diamond anvil cell, vanadium dioxide, VO2, pressure-induced metallization
  • Poster
    NextGen@Helmholtz 2016 Conference, 28.-30.09.2016, Braunschweig, Deutschland

Publ.-Id: 24567 - Permalink


Structural and functional properties of ion-irradiated graphene-reinforced elastomers
Jagielski, J.; Ostaszewska, U.; Kozinski, R.; Hassa-Zaloba, A.; Romaniec, M.; Kurpaska, L.; Kosinska, A.; Grambole, D.; Jozwik, I.;
Since more than half century ion beams are used for modification of functional properties of various materials: after semiconductors, metals and ceramics ion irradiation appeared recently as an interesting method of modification of organic materials, especially for friction and wear properties. Among polymeric materials the newest area of applications of ion beams is their use for modification of elastomers, commonly known as rubbers. Main structural effect caused by heavy ions in polymers is a massive loss of hydrogen from the surface layer, this leads to a smoothening and shrinking of the sample surface. The paper describes the results obtained in several rubbers modified by ion beams. Both, pristine and graphene-reinforced rubber samples were used, graphene doping led to the strengthening of the material bulk whereas ion irradiation allowed for surface property improvement. In the first part of the paper the hydrogen release from irradiated elastomers is shortly presented. Mechanical properties (hardness and friction) are discussed in the second part.

Publ.-Id: 24566 - Permalink


TOPFLOW-Experimente, Modellentwicklung und Validierung zur Qualifizierung von CFD-Codes für Zweiphasenströmungen - Abschlussbericht
Lucas, D.; Beyer, M.; Banowski, M.; Seidel, T.; Krepper, E.; Liao, Y.; Apanasevich, P.; Gauß, F.; Ma, T.;
Der vorliegende Bericht gibt einen zusammenfassenden Überblick der im Vorhaben erreichten Ergebnisse. Ziel war die Qualifikation von CFD-Methoden für Zweiphasenströmungen mit Phasenüber¬gang. Dafür werden neuartige experimentelle Daten benötigt. Diese können an der TOPFLOW-Anlage des HZDR generiert werden, da die Anlage Experimente in für die Reaktorsicher-heits¬forschung relevanten Skalen und Parametern mit innovativen Messtechniken verbindet.
Die experimentellen Arbeiten umfassen Untersuchungen zu Strömungen in vertikalen Rohren mit Hilfe der ultraschnellen Röntgentomographie, zu Strömungen mit und ohne Phasenübergang in einem Testbassin sowie zur Gegenstrombegrenzung in einem Heißstrangmodell. Diese werden im vorliegenden Bericht nur kurz dargestellt, da es zu allen 3 Versuchsserien ausführliche Dokumentationen in separaten Berichten gibt.
Ein wichtiges Ergebnis der Arbeiten zur CFD-Qualifizierung ist der Erstellung des Baseline-Modellkonzepts sowie die Erstellung des Baseline-Modells für polydisperse Blasenströmungen. Damit wird ein wesentlicher Beitrag zur Erhöhung der Vorhersagefähigkeit von CFD-Codes auf Basis des Zwei- oder Mehr-Fluid-Modells erreicht.
Das innovative Generalized Two-Phase Flow Konzept (GENTOP) zielt hingegen auf eine Erweiterung der Einsatzmöglichkeiten der Zweiphasen-CFD. In vielen Strömungen treten unterschiedlicher Morphologien der Phasen bzw. Strömungsformen parallel in einer Strömungsdomäne auf. Außerdem gibt es Übergänge zwischen diesen Morphologien. Mit dem GENTOP-Konzept wurde erstmals ein Rahmen geschaffen der die Simulation solcher Strömungen auf konsistente Art und Weise ermöglicht. Spezielle Modellentwicklungen erfolgten mit dem Ziel einer besseren Modellierung des Phasenübergangs.
Keywords: CFD, Zweiphasenströmung, Experiment, Phasenübergang, Blasenströmung, separierte Strömung
  • Open Access LogoWissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-077 2016
    ISSN: 2191-8708

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Publ.-Id: 24565 - Permalink


Two-Phase Flow Experiments on Counter-Current Flow Limitation in a model of the Hot Leg of a Pressurized Water Reactor (2015 test series)
Beyer, M.; Lucas, D.; Pietruske, H.; Szalinski, L.;
Counter-Current Flow Limitation (CCFL) is of importance for PWR safety analyses in several accident scenarios connected with loss of coolant. Basing on the experiences obtained during a first series of hot leg tests now new experiments on counter-current flow limitation were conducted in the TOPFLOW pressure vessel. The test series comprises air-water tests at 1 and 2 bar as well as steam-water tests at 10, 25 and 50 bar. During the experiments the flow structure was observed along the hot leg model using a high-speed camera and web-cams. In addition pressure was measured at several positions along the horizontal part and the water levels in the reactor-simulator and steam-generator-simulator tanks were determined.
This report documents the experimental setup including the description of operational and special measuring techniques, the experimental procedure and the data obtained.
From these data flooding curves were obtained basing on the Wallis parameter. The results show a slight shift of the curves in dependency of the pressure. In addition a slight decrease of the slope was found with increasing pressure. Additional investigations concern the effects of hysteresis and the frequencies of liquid slugs. The latter ones show a dependency on pressure and the mass flow rate of the injected water.
The data are available for CFD-model development and validation.
Keywords: experiment, CFD, two-phase flow, counter-current flow limitation, flooding characteristic, slug frequency
  • Open Access LogoWissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-076 2016
    ISSN: 2191-8708

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Publ.-Id: 24564 - Permalink


Experiments on vertical gas-liquid pipe flows using ultrafast X-ray tomography
Banowski, M.; Beyer, M.; Lucas, D.; Hoppe, D.; Barthel, F.;
For the qualification and validation of two-phase CFD-models for medium and large-scale industrial applications dedicated experiments providing data with high temporal and spatial resolution are required. Fluid dynamic parameter like gas volume fraction, bubble size distribution, velocity or turbulent kinetic energy should be measured locally. Considering the fact, that the used measurement techniques should not affect the flow characteristics, radiation based tomographic methods are the favourite candidate for such measurements. Here the recently developed ultrafast X-ray tomography, is applied to measure the local and temporal gas volume fraction distribution in a vertical pipe. To obtain the required frame rate a rotating X-ray source by a massless electron beam and a static detector ring are used.
Experiments on a vertical pipe are well suited for development and validation of closure models for two-phase flows. While vertical pipe flows are axially symmetrically, the boundary conditions are well defined. The evolution of the flow along the pipe can be investigated as well.
This report documents the experiments done for co-current upwards and downwards air-water and steam-water flows as well as for counter-current air-water flows. The details of the setup, measuring technique and data evaluation are given. The report also includes a discussion on selected results obtained and on uncertainties.
Keywords: experiment, CFD, two-phase flow, pipe flow, tomography
  • Open Access LogoWissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-075 2016
    ISSN: 2191-8708

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Publ.-Id: 24563 - Permalink


Major and Trace Element Geochemistry of the European Kupferschiefer – An Evaluation of Analytical Techniques
Rahfeld, A.; Wiehl, N.; Dreßler, S.; Möckel, R.; Gutzmer, J.;
Simple and rapid techniques are needed for routine quantitative chemical bulk-rock analyses of Kupferschiefer, a black shale containing variable amounts of silicates, base metal sulphides, carbonates and an organic content of up to 30 weight percent. In this study, WD-XRF, TXRF, and ICP-OES of acid- as well as peroxide-digested samples were tested as potential techniques based on their availability and adaptability to analyse major (Si, Ti, Al, Mg, Ca, Fe, K, but also Cu, Zn, Pb) and selected trace (Ag, As, Ba, Co, Mo, Ni, V) element concentrations. Because of the absence of a suitable reference material, a comparative study was undertaken using instrumental neutron activation analysis to ascertain the accuracy of different approaches. Our results suggest that data from ICP-OES were much higher in accuracy compared to INAA than those from WD-XRF and TXRF, independent of the digestion procedure. The choice of digestion procedure is reflected in low detection limits but an underestimation of Cu, Ag, Co, and V concentrations reported by ICP-OES relative to those obtained by INAA in the case of acid digestion and increased detection limits coupled with a loss of over 25 % Ag relative to INAA for peroxide digestion.
Keywords: black shale, ICP-OES, WD-XRF, INAA, whole-rock geochemistry, sulphides, copper ores

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Publ.-Id: 24562 - Permalink


Untersuchungen zum Komplexierungsverhalten der modifizierten Calix[4]arene gegenüber Uran(VI)
Bauer, A.; Schmeide, K.;
Vortrag zum Projekttreffen des BMBF Verbundprojektes "SE-FLECX".
Präsentation erster Ergebnisse zu Wechselwirkungsstudien von Uran(VI) mit Calix[4]arenen in nichtwässrigen Sytemen.
  • Lecture (others)
    Projekttreffen des BMBF-Verbundprojektes "SE-FLECX", 26.11.2015, Leipzig, Deutschland

Publ.-Id: 24561 - Permalink


Numeric simulations of a liquid metal model of a bloom caster under the effect of rotary electromagnetic stirring
Barna, M.; Javurek, M.; Willers, B.; Eckert, S.; Reiter, J.;
At the voestalpine Stahl Donawitz GmbH the continuous casting of round steel blooms is commonly supported by electromagnetically induced stirring of the liquid steel flow. A number of beneficial effects are attributed to electromagnetic stirring in the mould region (M-EMS), e.g. the enhanced transition from columnar to equiaxed solidification, the homogenization of the liquid steel flow or the reduction of surface and subsurface defects. Although the positive effects of M-EMS can be seen on the blooms (e.g. in etchings), the link between electromagnetic stirring of the steel melt and the quality of the solidified bloom is not sufficiently understood. Theoretical considerations are often limited to general cases and their results are therefore not directly applicable to real continuous casting geometries. On the other hand, plant measurements can only be performed to a limited extent due to the harsh conditions and other restrictions (e.g. safety regulations). In this work an alternative approach is used to investigate the steel flow in a round bloom caster under the influence of M-EMS. In a 1:3 scale Perspex model of a round bloom strand, measurements of the flow under the influence of a rotating magnetic field can be conducted. These measurements provide a validation benchmark for the numeric simulations. A numeric model of the before mentioned 1:3 scale model is implemented, encompassing the strand, the submerged entry nozzle as well as the M-EMS device. In the modelling approach, the bidirectional coupling between liquid steel flow and the electromagnetic field/forces has to be considered because otherwise the resulting tangential velocities will be overestimated. With the validated modelling approach, simulations of real casting machines can then be conducted, stirring parameter influences can be shown and conclusions for the real casting process can be drawn.
Keywords: electromagnetic stirring, round bloom caster, numeric simulations, tangential velocities, eutectic alloy GaInSn, flow measurement, ultrasound doppler velocimetry

Publ.-Id: 24560 - Permalink


Hydrometallurgy: It’s role in a Circular Economy
Reuter, M. A.;
Metals play a significant role in industrialisation and technological advancements.
The depletion of natural rich ore deposits coupled with a fall in grade, a decline in productivity, rising operational and energy costs, concerns on sustainability and environmental impact of mining and metal related activities have been affecting the mining and metals industry in the recent past. Unless innovative methods that look at the smart use and recovery of metals from metal resources are developed, the world will be faced by a metal supply risk that will impact on future economic growth and technological development.
  • Invited lecture (Conferences)
    Sustainable Hydrometallurgical Extraction of Metals / Hydrometallurgy Conference 2016, 31.07.-03.08.2016, Cape Town, South Africa

Publ.-Id: 24559 - Permalink


Possibilities and limitations of cfd simulation for flashing flow scenarios in nuclear applications
Liao, Y.; Lucas, D.;
The flashing phenomenon is relevant to nuclear safety analysis for example by loss of coolant accident and safety release scenarios. It has been studied intensively by means of experiments and simulations with system codes, but CFD simulation is still at the embryo stage. Rapid increasing computer speed makes it possible to apply the CFD technology in such complex flow situations. Nevertheless, a thorough evaluation on the limitation and restriction is still missing, which is however indispensable for the further development. In the present work, the commonly used two-fluid model with different mono-disperse assumptions are used to simulate various flashing scenarios. With the help of available experimental data, the results are evaluated and limitations are discussed. A poly-disperse method is found necessary for a reliable prediction of mean bubble size and phase distribution. First attempts to trace the evolution of bubble size distribution by means of poly-disperse simulations are made.
Keywords: Flashing; CFD simulation; Two-Fluid-Model; Mono-disperse; Poly-disperse

Publ.-Id: 24558 - Permalink


Distinguishing magmatic and metamorphic processes in peralkaline rocks of the Norra Kärr complex (Southern Sweden) using textural and compositional variations of clinopyroxene and eudialyte-group minerals.
Atanasova, P.; Marks, M. A. W.; Kraise, J.; Gutzmer, J.; Markl, G.; Heinig, T.;
The 1.49 Ga old Norra Kärr complex in Southern Sweden contains rocks characterized by a very high ratio of (Na+K)/Al ≥ 1.2 and a complex and highly unusual mineralogy, including rock-forming catapleiite, eudialyte-group minerals as well as minor rinkite- and britholite-group minerals. In contrast to other well-studied examples of agpaitic rocks, the Norra Kärr rocks have been deformed and partially metamorphosed during the Sveconorvegian/Grenvillian orogeny, and are now preserved in a westward dipping synform.
Magmatic and metamorphic processes at the Norra Kärr complex are distinguished by combining rock fabrics of clinopyroxene and eudialyte-group minerals. Both mineral groups are stable over a large P-T range, which makes them excellent monitors of the geochemical evolution of such systems and enables the reconstruction of magmatic and subsequent metamorphic conditions.
The magmatic mineral assemblage crystallized from a subsolvus syenite at continuously decreasing temperatures (700 - 450ºC) and silica activity (0.6 - 0.3). Due to initially relatively low peralkalinity and reducing conditions, Zr was first incorporated in Zr-aegirine. Subsequent destabilization of the latter indicates increasing peralkalinity, oxygen fugacity and water activity, which resulted in the crystallization of early magmatic catapleiite. Crystallization of presumably later magmatic Mn- and REE-poor eudialyte-group minerals, happened as soon as sufficient Cl, REE and HFSE were enriched in the residual melt.
Metamorphic conditions during the Sveconorvegian/Grenvillian orogeny are constrained to T between 400 - 550ºC and aSiO2 range of 0.25 - 0.4. Due to deformation and interaction with fluids, post-magmatic Al-rich aegirine as well as post-magmatic eudialyte-group minerals enriched in REE, Y and Mn formed. Subsequently, the eudialyte-group minerals were destabilized and decomposed to post-magmatic catapleiite and secondary REE-bearing minerals. During the whole history of the complex, aSiO2 remains very similar, indicating very little interaction with the surrounding granitic rocks.
Regardless of the intense deformation due to folding of the Norra Kärr body during the Sveconorvegian/Grenvillian orogeny, indications for primary magmatic layering of the intrusion are retained on the deposit scale. In addition, the compositional changes of magmatic eudialyte-group minerals from the outer to the inner subunit indicate a primary geochemical evolution feature due to fractional crystallization.
Keywords: deformed nepheline syenite; rare earth elements; clinopyroxene, eudialyte-group minerals

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Publ.-Id: 24557 - Permalink


Deutschland auf dem Weg in die Kreislaufwirtschaft?
Reuter, M. A.;
In Anbetracht des Wachstums der Weltbevölkerung, des wirtschaftlichen Aufholens der Schwellen- und Entwicklungsländer sowie der fehlenden Entkopplung des Wachstums vom Ressourcenverbrauch in den Industrieländern kommt der Kreislaufwirtschaft eine entscheidende Rolle zu: Sie ist mehr als nur die konsequente und umfassende Erfassung und Wiederverwertung aller Wertstoffe. Kreislaufwirtschaft beginnt bereits beim intelligenten Design von Produkten und Werkstoffen, das es ermöglicht, ein Produkt am Ende seines Lebenszyklus möglichst vollständig zu verwerten und die in ihm enthaltenen Rohstoffe zurückzugewinnen. Insbesondere für Deutschland als hochindustrialisiertes Land liegen hier enorme ökonomische Potentiale. Die Ressourcenproduktivität stellt auch zukünftig ein wichtiges Element der Wettbewerbsfähigkeit deutscher Firmen und der Sicherung von Beschäftigung dar. Je nach Perspektive ergibt sich ein differenziertes Bild über die deutschen Fortschritte in diesem Bereich. Mit Blick auf die abfallwirtschaftliche Seite der Kreislaufwirtschaft gehört Deutschland in Bezug auf Recyclingquoten zu den absoluten Vorreitern. Ein deutlich anderes Bild ergibt sich jedoch, wenn man den Blick weitet und die tatsächliche Kreislaufführung von Abfällen betrachtet: Zwei Drittel aller Abfälle werden noch nicht als Ressource genutzt. Auch im Bereich der inneren Kreisläufe besteht in Deutschland noch Nachholbedarf, im Fokus stehen hier Aktivitäten wie die Reparatur und Verlängerung der Nutzungsdauer von Produkten.
Eine neue Studie der Friedrich-Ebert-Stiftung hat den Stand der Kreislaufwirtschaft in Deutschland untersucht, bislang noch ungenutzte Potentiale identifiziert und Handlungsempfehlungen gemacht, wie die Ressourcenproduktivität verbessert werden kann.
  • Invited lecture (Conferences)
    Deutschland auf dem Weg in die Kreislaufwirtschaft?, 10.06.2016, Berlin, Deutschland

Publ.-Id: 24556 - Permalink


Metamorphic control on REE redistribution in alkaline complexes – the Norra Kärr example
Atanasova, P.; Marks, M. A. W.; Krause, J.; Gutzmer, J.; Markl, G.;
During the last decade the economic interest on rare earth elements (REE) rapidly increased due to their broad application in high-tech products. Beside carbonatites and lateritic deposits, alkaline and peralkaline rocks comprise one of the most promising sources for future REE supply, in particular heavy REE (HREE). As a reaction of global demand, a large amount of relatively unknown and/or difficult to access occurrences have been intensely explored and large geological data sets have been generated providing detailed insight into hidden/unknown geologic formations.
The Norra Kärr alkaline complex in Southern Sweden is a very good example of this development. It represents one of the largest resources of (REE) in Europe. The Norra Kärr rocks are characterized by a very high ratio of (Na+K)/Al ≥ 1.2 and a complex and highly unusual mineralogy, including rock-forming catapleiite, eudialyte group minerals (EGM) as well as minor rinkite and britholite group minerals. EGM incorporate significant concentrations of more than 30 different elements, including the group of 14 naturally occurring lanthanides, Y and Zr. Catapleiite hosts large amounts of Zr, but is essentially REE-free. The Norra Kärr body intruded at around 1.49 ± 0.01 Ga [2]. In contrast to other well-studied examples of so-called agpaitic rocks, such as the Ilímaussaq complex (Greenland) or the Lovozero Complex (Kola peninsula/Russia), it has been deformed during the Sveconorvegian/Grenvillian orogeny and is preserved within a westwards dipping synform. This specific feature has now been used to amplify the restricted knowledge on the behavior of agpaitic rocks during metamorphism. Earlier work on deformed agpaitic rocks in Canada and Malawi (e.g. [1] & [3]) mainly used compositional changes of clinopyroxene (CPX) to trace magmatic and metamorphic processes in agpaitic rocks. Our study investigates additionally textural and compositional features of the main ore-forming minerals (EGM) to provide direct insight into ore formation and subsequent REE (re-)distribution due to metamorphism.
Magmatic and metamorphic processes in the Norra Kärr complex are distinguished based on rock textures and textural and compositional changes of CPX and EGM. CPX is invariably sodic, but is characterized by early magmatic Zr-rich cores, overgrown by presumably late magmatic Zr-poor aegirine. Both are anhedrally overgrown by Al-rich aegirine (jadeite) of metamorphic origin. EGM show complex distribution patterns of major and minor elements suggesting multiphase influence of fractional crystallization, recrystallization, fluid-induced re-mobilization and late-stage alteration. Oscillatory and sector zoned as well as porous areas of EGM are enriched in Zr, but depleted in Si, Ca, REE, Y, and Cl and are interpreted to be of magmatic origin. In contrast, presumably metamorphosed areas are characterized by either Ce-rich flamy textures or Y-rich, but Ce-depleted poikilitic textures, cracks, veins and/or vugs, and rim areas of single crystals. Furthermore, we observe a general increase of REE, Y, Nb and/or Mn content with increasing degree of deformation.
  • Lecture (Conference)
    35th International Geological Congress, 27.08.-04.09.2016, Cape Town, Republic of South Africa
  • Poster
    Gordon Research Conference on Geochemistry of Mineral Deposits, 19.-24.06.2016, Les Diablerets, Schweiz

Publ.-Id: 24555 - Permalink


Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions
Kraus, D.; Vorberger, J.; Pak, A.; Hartley, N. J.; Fletcher, L. B.; Frydrych, S.; Galtier, E.; Gamboa, E. J.; Gericke, D. O.; Glenzer, S. H.; Granados, E.; Macdonald, M. J.; Mackinnon, A. J.; Mcbride, E. E.; Nam, I.; Neumayer, P.; Roth, M.; Saunders, A. M.; Sun, P.; van Driel, T.; Döppner, T.; Falcone, R. W.;
The effects of hydrocarbon dissociation and subsequent diamond precipitation on the internal structure and evolution of icy giant planets like Neptune and Uranus have been discussed for more than three decades. Inside these celestial bodies, gravity compresses mixtures of light elements to densities of several grams per cubic centimeter while the temperature reaches thousands of Kelvins resulting in thermal energies on the order of chemical bonding and above.
Under these conditions, simple hydrocarbons like methane, which are highly abundant in the atmospheres of these planets, are believed to undergo structural transitions that release molecular hydrogen from deeper layers and may lead to compact stratified cores. Indeed, the isentropes of Uranus and Neptune intersect temperature-pressure conditions where first polymerization occurs, and then, in deeper layers, a phase separation into diamond and hydrogen may be possible.
Here we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene samples dynamically compressed to 150GPa and 5000 K, which resembles the environment ~10,000 km below the surfaces of Neptune and Uranus. Our findings demonstrate the necessity of high pressures for initiating carbon-hydrogen demixing and imply that diamond precipitation may require ~10x higher pressures than previously suggested by experiments investigating non-isolated hydrocarbons. Besides underlining the general importance of chemical processes inside giant planets, these results will inform evolutionary models of Uranus and Neptune, where carbon-hydrogen demixing can be a significant source for the convection necessary to explain their unusual magnetic fields.
Additionally, our experiment demonstrates an alternative path for producing nanodiamonds for scientific and industrial applications that may be superior to current methods using oxygen-deficient explosives.
Keywords: x-ray scattering, x-ray free electron laser, shock compression, warm dense matter, mixtures, phase separation, demixing, planets, neptune, uranus, carbon, hydrogen, diamond, nano-diamond

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Publ.-Id: 24554 - Permalink


Organische Chemie I, Struktur, Nomenklatur und Analyse
Mamat, C.;
Liebe Studierende,
mit diesem und den folgenden Studienheften tauchen Sie in die wundervolle Welt der organischen Chemie ein. Wir werden uns sehr intensiv damit beschäftigen, was organische Chemie überhaupt ist. Sie werden am Anfang die wichtigsten Stoffklassen kennen lernen und wie organische Verbindungen generell bezeichnet werden. Wir werden uns Grundreaktionen anschauen, mit denen Sie über 90% der organischen Chemie beschreiben können. Am Ende werden wir an die klassischen Grenzen der organischen Chemie gelangen und sehen, wie sie korrespondiert und überlappt beispielsweise mit der anorganischen Chemie, der physikalischen Chemie, der analytischen Chemie oder auch der Biochemie.
  • Book (Authorship)
    Heidelberg: Springer Verlag, 2016
    0036 Seiten

Publ.-Id: 24553 - Permalink


Ultrafast dynamics in VO2 under high pressures
Braun, J. M.; Schneider, H.; Helm, M.; Boatner, L. A.ORC; Marvel, R. E.; Haglund, R. F.; Pashkin, A.
Vanadium dioxide (VO2) is a classic example of a strongly correlated system demonstrating a sharp insulator-to-metal transition (IMT) at Tc = 340 K. Since the IMT occurs just above room temperature, VO2 has a high potential for applications in optoelectronic and electrical devices. Nevertheless, the microscopic mechanism of the IMT in VO2 is not yet fully understood. In particular, the roles played by the electronic correlation and the lattice distortion during the IMT are still under debate.
A pressure-induced metallization of VO2 above 10 GPa has been reported by Arcangeletti et al. using infrared spectroscopy [1]. Remarkably, high-pressure Raman spectra do not reveal qualitative changes indicating that the pressure-driven IMT in VO2 is not coupled to any structural distortion. Recently, the first time-resolved pump-probe study of VO2 under pressure has, indeed, revealed a nonequilibrium metallic phase with the monoclinic structure inherent to the insulating phase. [2]
Here, we report a systematic study of ultrafast pump-probe response in VO2 under pressure at different excitation fluences in order to clarify the nature of the pressure-induced changes in this material. The pump-probe measurements with 400 nm pump and 800 nm probe wavelengths were performed on single VO2 crystals mounted inside a diamond anvil cell. CsI has been used as a pressure-transmitting medium in order to ensure contact between the sample and the diamond anvil.
At low pressures of a few GPa, the photoexcited electrons relax on a time scale of about 0.5 ps. With increasing pressure, the relaxation time gradually becomes faster reaching the value of about 0.15 ps beyond 10 GPa. Furthermore, the application of pressure reduces the amount of pump energy which is required to induce a metastable metallic state. However, even close to 12 GPa, the sample demonstrates a dynamics typical of the insulating VO2. These preliminary results agree with recent high-pressure resistivity measurements that show a gradual crossover to the metallic state which is reached only above 30 GPa. [3]
References:
[1] E. Arcangeletti et al., Phys. Rev. Lett. 98, 196406 (2007).
[2] W.-P. Hsieh et al., Appl. Phys. Lett. 104, 021917 (2014).
[3] L. Bai et al., Phys. Rev. B. 91, 104110 (2015).
Keywords: pump-probe spectroscopy, insulator-to-metal transition, high pressure, diamond anvil cell, vanadium dioxide, VO2, pressure-induced metallization
  • Poster
    54th European High Pressure Research Group (EHPRG) International Meeting on High Pressure Science and Technology, 04.-09.09.2016, Bayreuth, Deutschland

Publ.-Id: 24552 - Permalink


Ultrafast nonlinear response of GaAs under high pressures
Braun, J. M.; Schmidt, J. F.; Seletskiy, D. V.ORC; Schneider, H.; Helm, M.; Pashkin, A.
Applying hydrostatic pressure leads to dramatic changes in the band structure of semiconductors. In particular, it enables a continuous tuning of the bandgap energy. Here we study the nonlinear response of bulk gallium arsenide (GaAs) in the vicinity of its bandgap. The optical pump-probe experiment is performed in a non-collinear reflection geometry at pressures up to 3GPa generated inside a diamond anvil cell. By increasing pressure we observe pronounced slowing down of the relaxation dynamics of photoexcited charge carriers: the time constant of the dominating relaxation process increases from about 10 ps at ambient pressure to 35 ps above 0.7GPa. These time scales are by an order of magnitude shorter than the recombination time determined using optical pump - THz probe spectroscopy. Thus, the fast dynamics observed in the optical pump-probe measurements is governed by the cooling of hot electron distribution and not by the recombination process. Furthermore, at pressures above 2GPa the bandgap energy of GaAs is above the excitation spectrum of our experiment. The sample becomes transparent for the femtosecond pulses leading to a transient pump-probe signal with a negative sign due to the third order nonlinear response of GaAs.
Keywords: pump-probe spectroscopy, recombination dynamics, high pressure, diamond anvil cell, gallium arsenide, GaAs
  • Lecture (Conference)
    DPG-Frühjahrstagung 2016, 06.-11.03.2016, Regensburg, Deutschland

Publ.-Id: 24551 - Permalink


Interaction of hydrogen with Fe60Al40 thin films
Ehrler, J.; Bali, R.; Grenzer, J.; Böttger, R.; Potzger, K.;
The effects of ion implantation on the structural and magnetic properties of Fe60Al40 films, possessing A2 and B2 structure respectively, have been investigated by means of X-ray diffraction and Vibrating sample magnetometry. The studies show that the magnetic properties of the 250 nm thick Fe60Al40 films depend on the structural order only. The chemical disorder induced evolution of ferromagnetism comes along with an abrupt disappearance of the (100)-superlattice peak.
The irradiation of paramagnetic B2 Fe60Al40 with H+, He+ or Ne+ ions with different fluences at low temperatures led to an increase of saturation magnetization (MS) going along with a lattice expansion induced by structural disorder. This effect did not appear for proton irradiation at elevated temperatures (250 ∘C) where the ordered B2 phase was retained. Upon low temperature hydrogen implantation of disordered A2 Fe60Al40 films, on the other hand, unlike for helium or neon irradiation, the lattice parameter and MS decreased indicating a little ordering. This might offer the possibility of H+ irradiation induced ordering of chemically disordered alloy thin films well below the ordering temperature.
  • Lecture (Conference)
    HZDR PhD Seminar, 17.-19.10.2016, Oberwiesenthal, Germany

Publ.-Id: 24550 - Permalink


Interaction of hydrogen with Fe60Al40 thin films
Ehrler, J.; Bali, R.; Grenzer, J.; Böttger, R.; Potzger, K.;
The effects of ion implantation on the structural and magnetic properties of Fe60Al40 films, possessing A2 and B2 structure respectively, have been investigated by means of X-ray diffraction and Vibrating sample magnetometry. The studies show that the magnetic properties of the 250 nm thick Fe60Al40 films depend on the structural order only. The chemical disorder induced evolution of ferromagnetism comes along with an abrupt disappearance of the (100)-superlattice peak.
The irradiation of paramagnetic B2 Fe60Al40 with H+, He+ or Ne+ ions with different fluences at low temperatures led to an increase of saturation magnetization (MS) going along with a lattice expansion induced by structural disorder. This effect did not appear for proton irradiation at elevated temperatures (250 ∘C) where the ordered B2 phase was retained. Upon low temperature hydrogen implantation of disordered A2 Fe60Al40 films, on the other hand, unlike for helium or neon irradiation, the lattice parameter and MS decreased indicating a little ordering. This might offer the possibility of H+ irradiation induced ordering of chemically disordered alloy thin films well below the ordering temperature.
  • Lecture (Conference)
    Seminar der Professur für Werkstofftechnik, 18.-19.11.2016, Altenberg, Germany

Publ.-Id: 24549 - Permalink


Interaction between hydrogen and Fe based ally thin films: Influence of defects
Ehrler, J.; Bali, R.; Otalora, C.; Yildirim, O.; Anwand, W.; Trinh, T. T.; Liedke, M. O.; Böttger, R.; Heller, R.; Cornelius, S.; Yuan, Y.; Grenzer, J.; Potzger, K.;
The effect of H treatment on the magnetic properties and the defect concentration of Fe60Al40 films, possessing A2 and B2 structure respectively, have been investigated. The treatment was realized by H+ irradiation as well as by reactor loading. Ferromagnetic A2-Fe60Al40 films of 250 nm thickness were irradiated with protons at an energy of 17 keV and fluences of up to 1.46 E18 ions cm−2. Magneto-optical Kerr effect showed a variation of coercivity and an increase of saturation magnetization (MS) as a function of ion fluence. Positron annihilation spectroscopy (PAS) indicates an increase of the open volume defect concentration. Superparamagnetic B2-Fe60Al40 films were annealed at 423 K in 30 bar H atmosphere. PAS shows that the H-annealing process led to a decrease in the open volume defect concentration. H-treatment caused a small increase in MS from 0.013 to 0.017 µb/Fe atom, as well as a shift in the blocking temperature from 85 to 115 K respectively. While H treatment significantly modifies the magnetic properties of Fe60Al40, elastic recoil detection suggests that the hydrogen is not retained in the vacancies present in the film, suggesting that the variations may be mostly due to structural changes.
  • Lecture (Conference)
    Seminar der Professur Werkstofftechnik, 01.-02.04.2016, Krippen, Germany

Publ.-Id: 24548 - Permalink


Influence of Hydrogen on Magnetic and Defect Properties of Fe60Al40 thin films
Ehrler, J.; Bali, R.; Anwand, W.; Trinh, T. T.; Liedke, M. O.; Böttger, R.; Yuan, Y.; Grenzer, J.; Potzger, K.;
The effect of hydrogen treatment on the magnetic properties and the defect concentration of Fe60Al40 films, possessing A2 and B2 structure respectively, have been investigated. The H treatment was realized by proton irradiation as well as by reactor loading. Ferromagnetic A2-Fe60Al40 films of 250 nm thickness were irradiated with protons at an energy of 17 keV and fluences of up to 1.46 E18 ions cm-2. Magneto-optical Kerr effect showed a variation of coercivity and an increase of saturation magnetization (MS) as a function of ion fluence. Positron annihilation spectroscopy (PAS) indicates an increase of the open volume defect concentration.
Superparamagnetic B2-Fe60Al40 films were capped with 10 nm Pd and annealed at 423 K in 30 bar H atmosphere. PAS shows that the H-annealing process led to a decrease in the open volume defect concentration. H-treatment caused a small increase in MS from 0.013 to 0.017 µb/Fe atom, as well as a shift in the superparamagnetic blocking temperature from 85 to 115 K respectively. While H treatment significantly modifies the magnetic properties of Fe60Al40, elastic recoil detection suggests that the hydrogen is not retained in the vacancies present in the film, suggesting that the variations in magnetic properties may be mostly due to structural changes.
  • Poster
    International Hydrogen Conference, 11.-14.09.2016, Jackson Lake, Wyoming, USA

Publ.-Id: 24547 - Permalink


Rapid Data Processing for Ultrafast X-Ray Computed Tomography Using Scalable and Modular CUDA based Pipelines
Frust, T.; Wagner, M.; Stephan, J.; Juckeland, G.; Bieberle, A.;
Ultrafast X-ray tomography is an advanced imaging technique for the study of dynamic processes basing on the principles of electron beam scanning. A typical application case for this technique is e.g. the study of multiphase flows, that is, flows of mixtures of substances such as gas-liquid flows in pipelines or chemical reactors. At Helmholtz-Zentrum Dresden-Rossendorf (HZDR) a number of such tomography scanners are operated. Currently, there are two main points limiting their application in some fields. First, after each CT scan sequence the data of the radiation detector must be downloaded from the scanner to a data processing machine. Second, the current data processing is comparably time-consuming compared to the CT scan sequence interval. To enable online observations or use this technique to control actuators in real-time, a modular and scalable data processing tool has been developed, consisting of user-definable stages working independently together in a so called data processing pipeline, that keeps up with the CT scanner's maximal frame rate of up to 8 kHz. The data processing stages are arbitrarily programmable and combinable. In order to achieve the highest processing performance all relevant data processing steps, which are required for a standard slice image reconstruction, were individually implemented in separate stages using Graphics Processing Units (GPUs) and NVIDIA's CUDA programming language. Data processing performance tests on different high-end GPUs (Tesla K20c, GeForce GTX 1080) and external computer clusters (Tesla P100) showed excellent performance.
Keywords: Computed tomography; Image reconstruction; Multithreading; Parallel algorithms; Pipeline processing; Real-time systems

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Publ.-Id: 24546 - Permalink


Hydrogen treatment of Fe60Al40 thin films
Ehrler, J.; Bali, R.; Otalora, C.; Anwand, W.; Trinh, T. T.; Liedke, M. O.; Böttger, R.; Yuan, Y.; Grenzer, J.; Cornelius, S.; Potzger, K.;
The effect of hydrogen treatment on the magnetic properties and the defect concentration of Fe60Al40 films, possessing A2 and B2 structure respectively, have been investigated. The H treatment was realized by proton irradiation as well as by reactor loading. Ferromagnetic A2-Fe60Al40 films of 250 nm thickness were irradiated with protons at an energy of 17 keV and fluences of up to 1.46 E18 ions cm-2. Magneto-optical Kerr effect showed a variation of coercivity and an increase of saturation magnetization (MS) as a function of ion fluence. Positron annihilation Spectroscopy (PAS) indicates an increase of the open volume defect concentration.
Superparamagnetic B2-Fe60Al40 films were capped with 10 nm Pd and annealed at 423 K in 30 bar H atmosphere. PAS shows that the H-annealing process led to a decrease in the open volume defect concentration. H-treatment caused a small increase in MS from 0.013 to 0.017 μb/Fe atom, as well as a shift in the superparamagnetic blocking temperature from 85 to 115 K respectively. While H treatment significantly modifies the magnetic properties of Fe60Al40, elastic recoil detection suggests that the hydrogen is not retained in the vacancies present in the film, suggesting that the variations in magnetic properties may be mostly due to structural changes.
  • Poster
    IEEE Magnetics Society Summer School 2016, 10.-16.07.2016, Tohoku University, Sendai, Japan

Publ.-Id: 24545 - Permalink


Sloshing instability and electrolyte layer rupture in liquid metal batteries
Weber, N.; Beckstein, P.; Herreman, W.; Horstmann, G. M.; Nore, C.; Stefani, F.; Weier, T.;
Liquid metal batteries (LMBs) are discussed today as a cheap grid scale energy storage, as required for the deployment of fluctuating renewable energies. Built as a stable density stratification of two liquid metals separated by a thin molten salt layer, LMBs are susceptible to short-circuit by fluid flows. Using direct numerical simulation, we study a sloshing long wave interface instability in cylindrical cells, which is already known from aluminium reduction cells. After characterising the instability mechanism, we investigate the influence of cell current, layer thickness, density, viscosity, conductivity and magnetic background field. Finally we study the shape of the interface and give a dimensionless parameter for the onset of sloshing as well as for the short-circuit.

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Publ.-Id: 24544 - Permalink


Hydrogen treatment of Fe60Al40 thin films
Ehrler, J.; Bali, R.; Otalora, C.; Yildirim, O.; Anwand, W.; Trinh, T. T.; Liedke, M. O.; Böttger, R.; Heller, R.; Cornelius, S.; Yuan, Y.; Grenzer, J.; Potzger, K.;
The effect of H treatment on the magnetic properties and the defect concentration of Fe60Al40 films, possessing A2 and B2 structure respectively, have been investigated. The treatment was realized by H+ irradiation as well as by reactor loading. Ferromagnetic A2-Fe60Al40 films of 250 nm thickness were irradiated with protons at an energy of 17 keV and fluences of up to 1.46 E18 ions cm−2. Magneto-optical Kerr effect showed a variation of coercivity and an increase of saturation magnetization (MS) as a function of ion fluence. Positron annihilation spectroscopy (PAS) indicates an increase of the open volume defect concentration. Superparamagnetic B2-Fe60Al40 films were annealed at 423 K in 30 bar H atmosphere. PAS shows that the H-annealing process led to a decrease in the open volume defect concentration. H-treatment caused a small increase in MS from 0.013 to 0.017 µb/Fe atom, as well as a shift in the blocking temperature from 85 to 115 K respectively. While H treatment significantly modifies the magnetic properties of Fe60Al40, elastic recoil detection suggests that the hydrogen is not retained in the vacancies present in the film, suggesting that the variations may be mostly due to structural changes.
  • Poster
    80. Jahrestagung der DPG und DPG-Frühjahrstagung, 06.-11.03.2016, Regensburg, Germany

Publ.-Id: 24543 - Permalink


Thermal Rayleigh-Marangoni convection in a three-layer liquid-metal-battery model
Köllner, T.; Boeck, T.; Schumacher, J.;
The combined effects of buoyancy-driven Rayleigh-B\'{e}nard convection (RC) and surface tension-driven Marangoni convection (MC) are studied in a triple-layer configuration which serves as a simplified model for a liquid metal battery (LMB). The three-layer model consists of a liquid metal alloy cathode, a molten salt separation layer, and a liquid metal anode at the top. Convection is triggered by the temperature gradient between the hot electrolyte and the colder electrodes, which is a consequence of the release of resistive heat during operation. We present a linear stability analysis of the state of pure thermal conduction in combination with three-dimensional direct numerical simulations of the nonlinear turbulent evolution on the basis of a pseudospectral method. Five different modes of convection are identified in the configuration, which are partly coupled to each other: RC in the upper electrode, RC with internal heating in the molten salt layer, MC at both interfaces between molten salt and electrode as well as anti-convection in the lower electrode. The linear stability analysis confirms that the additional Marangoni effect in the present setup increases the growth rates of the linearly unstable modes, i.e. Marangoni and Rayleigh-B\'{e}nard instability act together in the molten salt layer.
The critical Grashof and Marangoni numbers decrease with increasing middle layer thickness. The calculated thresholds for the onset of convection are found for realistic current densities of laboratory-sized LMBs. The global turbulent heat transfer follows scaling predictions for internally heated RC. The global turbulent momentum transfer is comparable with turbulent convection in the classical Rayleigh-B\'{e}nard case. In summary, our studies show that incorporating Marangoni effects generates smaller flow structures, alters the velocity magnitudes, and enhances the turbulent heat transfer across the triple-layer configuration.
Keywords: Marangoni convection, Free convection, Interfacial flows, Turbulent convection

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Publ.-Id: 24542 - Permalink


Evaluating Moisture and Geometry Effects on L-Band SAR Classification Performance over a Tropical Rain Forest Environment
Liesenberg, V.; Souza Filho, C. R.; Gloaguen, R.;
Multitemporal single (HH) and dual-polarization (i.e., HH, HV) L-band spaceborne synthetic aperture radar (SAR) scenes were evaluated under different moisture conditions caused by precipitation prior to data acquisition at varying incidence angles. The changes affecting backscattering intensity, polarimetric decomposition, backscattering mechanism, and land use/land cover classification performance were evaluated. The study area is a shifting-cultivation environment in the eastern Amazon (Brazil). Several data input scenarios were proposed in the classification scheme (i.e., backscattering intensity alone and combined with alpha/entropy decomposition parameters, band ratios, and textural parameters) using a random forest classifier framework. Integration with optical data was also examined. The classification accuracy scores were then compared with accumulated precipitation data. The results showed that the variation in both the vegetation moisture and incidence angle increases the backscattering intensity for pasture, riparian forest and young regenerated forest by at least 1 dB compared with old successional forest stages due to its more uniform vertical structure and the landscape's increased dielectric constant. The overall classification accuracy proved low for each SAR acquisition date compared with the performance of the Landsat data. Based on SAR data, misclassification occurs for the young successional forest stages and increases in scenes with higher moisture conditions. The classification performance benefits from data integration only for one SAR scene acquired in the dry season. The results highlight the importance of selecting proper temporal intervals for the different SAR polarization modes of the forthcoming SAR missions. Further investigations should address both multitemporal at a single frequency as well as multifrequency SAR approaches.
Keywords: secondary forest, Advanced land observing satellite (ALOS)-phased-arrayed L-band synthetic aperture radar (PALSAR), eastern Amazon, L-band, polarization modes, random forest
  • IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 9(2016)12, 5357-5368
    DOI: 10.1109/JSTARS.2016.2617120

Publ.-Id: 24541 - Permalink


Cenozoic intracontinental deformation and exhumation at the northwestern tip of the India-Asia collision—southwestern Tian Shan, Tajikistan, and Kyrgyzstan
Käßner, A.; Ratschbacher, L.; Jonckheere, R.; Enkelmann, E.; Khan, J.; Sonntag, B.-L.; Gloaguen, R.; Gadoev, M.; Oimahmadov, I.;
Along the Ghissar-Alai Range of the southwestern Tian Shan (southwestern Kyrgyzstan, northern Tajikistan), the deformation front of the India-Asia collision—the Pamir-Tibet orogen—is interacting with the intracontinental Tian Shan orogen without the intervening Tarim Craton. Apatite fission track (n = 33, ~3.3–145.6 Ma, 27% <10 Ma) and (U-Th)/He (n = 32, ~1.9–26.1 Ma, 56% <10 Ma) thermochronologic ages suggest approximate isothermal holding (very slow cooling to weak reheating) during relative tectonic quiescence between ~150 and 15 Ma. Accelerated exhumation (~0.2–1.0 km/Myr, median ~0.5 km/Myr) and cooling (11–16°C/Myr) occurred over the last ~10 Myr. Geomorphologic parameters—incision, river steepness, and concavity—confirm the youth of the southwestern Tian Shan's mountain building. High exhumation/cooling rates are correlated with pronounced local relief, produced by Cenozoic faults reactivating inherited (Late Paleozoic) structures. Regions with similarly young exhumation are centered along rims of rigid crustal blocks in the central and eastern Tian Shan. Structurally, the Ghissar-Alai Range is a broad, east trending zone of dextral transpression that includes the northern Tajik Basin (Illiak Fault Zone) and the Pamir Thrust System of the frontal northern Pamir. It is the particular deformation field at the northwestern tip of the India-Asia collision—the interaction of the westward gravitational collapse of the Pamir Plateau into the Tajik Basin with the bulk northward motion of the Pamir—that transformed the southwestern Tian Shan into a dextral transpression belt. The dextral transpression in the southwestern Tian Shan contrasts with sinistral strike-slip shear localized along inherited fault zones, accommodating dominant north-south shortening, in the central and eastern Tian Shan. The deformation field influenced by the Pamir and the associated young exhumation make the Ghissar-Alai Range a unique feature in the Tian Shan orogen.

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Publ.-Id: 24540 - Permalink


10Be Surface-Exposure Age Dating of the Last Glacial Maximum in the Northern Pamir (Tajikistan)
Grin, E.; Ehlers, T. A.; Schaller, M.; Sulaymonova, V.; Ratschbacher, L.; Gloaguen, R.;
Knowledge of the spatial and temporal variations in Alpine glaciations is essential for reconstructing the regional and global timing of ice ages. This study investigates glacial deposits at the mouth of the Muksu catchment in the northern Pamir using 10Be surface-exposure age dating. We sampled boulders from the furthest downstream recessional moraine (20 samples) and five lateral moraines (41 samples) near the former terminus of the Fedchenko Glacier, the longest (∼72 km) present-day Alpine glacier of the Pamir. After the identification of outliers, the boulder population of the recessional moraine yielded a mean exposure age of 17.5 ± 1.9 ka. The maximum exposure age of the lateral moraines, collected ∼5 km up-valley of the recessional moraine, is 18.2 ± 1.7 ka. The boulder ages reflect glacial deposition during the Last Glacial Maximum (Marine Isotope Stage 2) in the region; they are in accordance with published glacial deposition ages in the western Tian Shan.
Keywords: Moraine; Cosmogenic radionuclides; Exposure-age dating; Last glacial maximum; Pamir; Fedchenko Glacier

Publ.-Id: 24539 - Permalink


Evaluation of a deformable registration algorithm for subsequent lung computed tomography imaging during radiochemotherapy
Stützer, K.; Haase, R.; Lohaus, F.; Barczyk, S.; Exner, F.; Löck, S.; Rühaak, J.; Lassen-Schmidt, B.; Corr, D.; Richter, C.;
Purpose:

Rating both a lung segmentation algorithm and a deformable image registration (DIR) algorithm for subsequent lung computed tomography (CT) images by different evaluation techniques. Furthermore, investigating the relative performance and the correlation of the different evaluation techniques to address their potential value in a clinical setting.
Methods:

Two to seven subsequent CT images (69 in total) of 15 lung cancer patients were acquired prior, during, and after radiochemotherapy. Automated lung segmentations were compared to manually adapted contours. DIR between the first and all following CT images was performed with a fast algorithm specialized for lung tissue registration, requiring the lung segmentation as input. DIR results were evaluated based on landmark distances, lung contour metrics, and vector field inconsistencies in different subvolumes defined by eroding the lung contour. Correlations between the results from the three methods were evaluated.
Results:

Automated lung contour segmentation was satisfactory in 18 cases (26%), failed in 6 cases (9%), and required manual correction in 45 cases (66%). Initial and corrected contours had large overlap but showed strong local deviations. Landmark-based DIR evaluation revealed high accuracy compared to CT resolution with an average error of 2.9 mm. Contour metrics of deformed contours were largely satisfactory. The median vector length of inconsistency vector fields was 0.9 mm in the lung volume and slightly smaller for the eroded volumes. There was no clear correlation between the three evaluation approaches.
Conclusions:

Automatic lung segmentation remains challenging but can assist the manual delineation process. Proven by three techniques, the inspected DIR algorithm delivers reliable results for the lung CT data sets acquired at different time points. Clinical application of DIR demands a fast DIR evaluation to identify unacceptable results, for instance, by combining different automated DIR evaluation methods.
Keywords: lung segmentation, deformable lung registration, landmarks, inconsistency vector field

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Publ.-Id: 24538 - Permalink


Structural control on drainage network and catchment area geomorphology in the Dead Sea area: an evaluation using remote sensing and geographic information systems in the Wadi Zerka Ma’in catchment area (Jordan)
Odeh, T.; Gloaguen, R.; Mohammada, S. H.; Schirmer, M.;
The geology of Jordan is characterized by fault systems with three major trends: (1) NW–SE, the oldest, (2) WNW–ESE, and (3) NNW–SSE, the youngest. The drainage network of the Wadi Zerka Ma’in catchment area, located in the middle of the Dead Sea rift, parallels these structural orientations. A regional transtensive fault, with embedded normal faults, bounds the lower and middle part of the catchment area. The topographic profile of the Zerka Ma’in River exhibits two major knickpoints where it crosses two major embedded normal faults. The second major knickpoint developed as a result of the dramatic lowering of the Lisan Lake water level, a lake that pre-dates the Dead Sea. The decreased water level triggered river incision into the clastic sandstone units of Wadi Zerka Ma’in. We performed a morphotectonic analysis study to investigate how the rock structures control the drainage network and the catchment area geomorphology. According to the transverse topographic symmetry factor (T), the catchment area is highly asymmetric. The major basin asymmetry trend is SE-oriented, parallel to the oldest set of fault systems. The catchment area displays a convex hypsometric curve indicating a very recent stage in the geomorphologic cycle. Our study indicates that the Lisan Lake catchment area shrinkage and structures growth controlled and shaped the Wadi Zerka Ma’in catchment area geomorphology. The combined use of a geographic information system (GIS) and remote sensing was shown to be very efficient in unraveling the evolution of the drainage network and catchment area geomorphology.

Publ.-Id: 24537 - Permalink


Recent progress in pulsed laser deposition of iron based superconductors
Haindl, S.; Molatta, S.; Hiramatsu, H.; Hosono, H.;
Pulsed laser deposition (PLD) is the most commonly used deposition technique for Fe-based superconductor thin films today. The number of grown compounds using PLD is still quite limited to so-called 11 compounds (FeTexSy, FeSe1−xTex) and 122 compounds (primarily Co-and P-substituted BaFe2As2). Especially in the growth of Fe-chalcogenides, PLD is challenged by the strong volatility of the elements and their non-negligible vapour pressure. In addition, in situ PLD of the high-temperature superconducting F-doped iron oxypnictides seemed to be feasible only under reactive deposition and stayed disregarded for some time. Here, we summarise the progress that was recently made in the growth of Fe-based superconducting thin films towards an improved control of thin film stoichiometry and the in situ growth of F-doped iron oxypnictides. The presented new ideas deviate from the standard approach of an adjustment of target composition. We first focus on the growth of FeSe1−xTex films, where the introduction of a buffer layer of same composition decreased surface roughness and allowed epitaxial film growth at reduced deposition temperatures with enhanced reproducibility. Second, we illustrate how F-doping in iron oxypnictide thin films can be obtained during in situ PLD using a diffusive reaction between substrate and the growing film.

Publ.-Id: 24536 - Permalink


Reply to the comment of Mitchell et al. on “Geomorpho-tectonic evolution of the Jamaican restraining bend” by L. Domínguez-González, L. Andreani, K.P. Stanek and R. Gloaguen [Geomorphology, 228 (2015) 320–334]
Domínguez-González, L.; Andreani, L.; Stanek, K. P.; Gloaguen, R.;
We reply to the comments of Mitchell et al. on our paper entitled “Geomorpho-tectonic evolution of the Jamaican restraining bend”. The comments contain statements about the methods that need to be balanced. We agree that the interpretation of the modeled drainage network in some karstified parts of the Jamaican island is difficult, but this does not affect the validity of our analysis elsewhere. We consider that our geomorphic analyses (which also include topographic profiles and morphometric maps) are still valid. The view expressed by Mitchell et al. that we used serially developed landscapes to ‘date’ progressive uplift is an oversimplification of our discussion. We highlighted the differences between the geomorpho-tectonic provinces of Jamaica, and we proposed to explain these differences by a model which involves (1) a westward propagation of the restraining bend and (2) a difference in tectonic styles between the different provinces of Jamaica. Our interpretation does not contradict existing models based on seismotectonic data, provenance analysis or on the origin of Jamaican bauxite. There is a disagreement between James-Williamson et al. (2014), which suggested that central Jamaica was already being uplifted by the end of the Late Miocene, and Domínguez-González et al. (2015), which proposed a Pliocene to present onset of the NE-trending compression toward the SW. However, the timing of the deformation in central and western Jamaica is still poorly constrained and, at this time, any interpretation of the uplift history of central Jamaica should be considered as hypothetical.
Keywords: Landscape models; GIS; Digital elevation models

Publ.-Id: 24535 - Permalink


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