Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Without submitted and only approved publications
Only approved publications

34121 Publications

The tectono-sedimentary evolution of a major seismogenic zone with low slip rate activity: A geochronological and sedimentological investigation of the Dobrá Voda Depression (Western Carpathians)

Šujan, M.; Braucher, R.; Šujan, M.; Hók, J.; Povinec, P. P.; Šipka, F.; Rugel, Georg; Scharf, A.

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

Keywords: Depth profile exposure dating of 10Be; 26Al and 36Cl; AMS

Downloads:

  • Secondary publication expected from 12.02.2021

Permalink: https://www.hzdr.de/publications/Publ-30788
Publ.-Id: 30788


Positron annihilation analysis of nanopores and growth mechanism of oblique angle evaporated TiO₂ and SiO₂ thin films and multilayers

García-Valenzuela, A.; Butterling, M.; Liedke, M. O.; Hirschmann, E.; Trinh, T. T.; Elsherif, A. G. A.; Wagner, A.; Alvarez, R.; Gil-Rostra, J.; Rico, V.; Palmero, A.; González-Elipe, A. R.

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

Keywords: Positron annihilation; Nanopores; OAD thin films; TiO₂; SiO₂; Growing mechanism

Permalink: https://www.hzdr.de/publications/Publ-30787
Publ.-Id: 30787


Revealing the defect-dominated oxygen evolution activity of hematene

Bishnupad, M.; Wei, Y.; Ghorbani Asl, M.; Krasheninnikov, A.; Parasmani, R.; Bikash, K. J.

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

Keywords: hemetene; defect; electrocatalysis; oxygen evolution reaction

Downloads:

  • Secondary publication expected from 03.03.2021

Permalink: https://www.hzdr.de/publications/Publ-30786
Publ.-Id: 30786


Chelation in One Fell Swoop: Optimizing Ligands for Smaller Radiometal Ions

Choudhary, N.; Jaraquemada-Pelaez, M.; Zarschler, K.; Wang, X.; Radchenko, V.; Kubeil, M.; Stephan, H.; Orvig, C.

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

Permalink: https://www.hzdr.de/publications/Publ-30785
Publ.-Id: 30785


Numerical simulation of formation and growth of fractal-like aggregates in a tubular aerosol reactor

Lehnigk, R.; Niemi, T.; Peltola, J.; Schlegel, F.

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

  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung, 09.-11.03.2020, Bamberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30784
Publ.-Id: 30784


Spin-polarized positrons. Who cares?

Wagner, A.; Butterling, M.; Liedke, M. O.; Hirschmann, E.; Elsherif, A. G. A.

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

Keywords: spin-polarized positrons

  • Lecture (others)
    Treffen deutschsprachiger Positronengruppen, 13.-14.02.2020, Halle (Saale), Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30783
Publ.-Id: 30783


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

Wagner, A.

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

Keywords: Materials Research Positrons atomic defects nano-scale porosimetry

  • Invited lecture (Conferences)
    Spectroscopic methods and synchrotron XRD for materials characterization, 05.03.2020, Kista, Sweden

Permalink: https://www.hzdr.de/publications/Publ-30782
Publ.-Id: 30782


P1817 - Sensor zur Vermessung von Strömungsprofilen in großen Kolonnen und Apparaten

Vishwakarma, V.; Schleicher, E.; Schubert, M.; Tschofen, M.; Löschau, M.

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

  • Patent
    DE102018124501 - Erteilung 13.02.2020

Permalink: https://www.hzdr.de/publications/Publ-30778
Publ.-Id: 30778


Essential Role of Heterocyclic Structure of N-Alkylated 2-Pyrrolidone Derivatives for Recycling Uranium from Spent Nuclear Fuels

Inoue, T.; Kazama, H.; Tsushima, S.; Takao, K.

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

Permalink: https://www.hzdr.de/publications/Publ-30776
Publ.-Id: 30776


Annual Report 2019 - Institute of Resource Ecology

Stumpf, T.; Foerstendorf, H.; Bok, F.; Richter, A.

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

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-110 2020
    ISSN: 2191-8708, eISSN: 2191-8716

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30774
Publ.-Id: 30774


Magnetic response of FeRh to static and dynamic disorder

Eggert, B.; Schmeink, A.; Lill, J.; Liedke, M. O.; Kentsch, U.; Butterling, M.; Wagner, A.; Pascarelli, S.; Potzger, K.; Lindner, J.; Thomson, T.; Fassbender, J.; Ollefs, K.; Keune, W.; Bali, R.; Wende, H.

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

Permalink: https://www.hzdr.de/publications/Publ-30773
Publ.-Id: 30773


Accurate MR image registration to anatomical reference space for diffuse glioma

Visser, M.; Petr, J.; Müller, D. M.; Eijgelaar, R. S.; Hendriks, E. J.; Witte, M.; Barkhof, F.; van Herk, M.; Mutsaerts, H. J.; de Munck, J. C.; Vrenken, H.; de Witt Hamer, P. C.

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

Permalink: https://www.hzdr.de/publications/Publ-30772
Publ.-Id: 30772


On the O-rich domain of the U-Am-O phase diagram

Epifano, E.; Vauchy, R.; Lebreton, R.; Lauwerier, F.; Joly, A.; Scheinost, A.; Guéneau, C.; Valot, C.; Martin, P. M.

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

Keywords: transmutation; nuclear fuel; XANES; EXAFS

Downloads:

  • Secondary publication expected from 11.01.2021

Permalink: https://www.hzdr.de/publications/Publ-30771
Publ.-Id: 30771


Terahertz absorption-saturation and emission from electron-doped germanium quantum wells

Ciano, C.; Virgilio, M.; Bagolini, L.; Baldassarre, L.; Pashkin, O.; Helm, M.; Montanari, M.; Persichetti, L.; Di Gaspare, L.; Capellini, G.; Paul, D. J.; Scalari, G.; Faist, J.; de Seta, M.; Ortolani, M.

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

Permalink: https://www.hzdr.de/publications/Publ-30769
Publ.-Id: 30769


Strömungsmorphologie flashender Feeds bei kritischen Stoffwerten

Döß, A.; Schubert, M.; Wiezorek, M.; Hampel, U.; Flegiel, F.; Windmeier, C.; Schleicher, E.

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

  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik, Adsorption und Extraktion 2020, 25.-28.02.2020, Berchtesgaden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30768
Publ.-Id: 30768


Formation of Thin NiGe Films by Magnetron Sputtering and Flash Lamp Annealing

Begeza, V.; Mehner, E.; Stöcker, H.; Xie, Y.; García, A.; Hübner, R.; Erb, D.; Zhou, S.; Rebohle, L.

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

Keywords: germanium; germanides; nickel; thin films; sputtering; flash lamp annealing

Permalink: https://www.hzdr.de/publications/Publ-30767
Publ.-Id: 30767


In-depth 3D characterization of sieve tray hydrodynamics

Vishwakarma, V.; Abdul Haq, S.; Schubert, M.; Schleicher, E.; Hampel, U.

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

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

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

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

  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik, Adsorption und Extraktion, 26.-28.02.2020, Berchtesgaden, Germany

Permalink: https://www.hzdr.de/publications/Publ-30764
Publ.-Id: 30764


Application of Positron Emission Particle Tracking (PEPT) to measure the bubble-particle interaction in a turbulent and dense flow

Sommer, A.-E.; Ortmann, K.; van Heerden, M.; Richter, T.; Leadbeater, T.; Cole, K.; Heitkam, S.; Brito-Parada, P. R.; Eckert, K.

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

Keywords: Positron Emission Particle Tracking (PEPT); tomographic Particle Image Velocimetry (PIV); bubble-particle interaction; grid turbulence; dense flow; flotation

Downloads:

  • Secondary publication expected from 01.09.2021

Permalink: https://www.hzdr.de/publications/Publ-30763
Publ.-Id: 30763


2D and 3D convolutional neural networks for outcome modelling of locally advanced head and neck squamous cell carcinoma

Starke, S.; Leger, S.; Zwanenburg, A.; Leger, K.; Lohaus, F.; Linge, A.; Schreiber, A.; Kalinauskaite, G.; Tinhofer, I.; Guberina, N.; Guberina, M.; Balermpas, P.; von der Grün, J.; Ganswindt, U.; Belka, C.; Peeken, J. C.; Combs, S. E.; Böke, S.; Zips, D.; Richter, C.; Troost, E. G. C.; Krause, M.; Baumann, M.; Löck, S.

These are the results from the analyses presented in a paper submitted to Scientific Reports.

The zip file contains the trained model files and the plots that were used in the manuscript.

Code for reproduction of our analyses can be obtained from https://github.com/oncoray/cnn-hnscc. There, you also find instructions on how to load our models.

Keywords: convolutional neural networks; Keras; Deep learning; head and neck cancer; loco-regional-recurrence; Cox proportional hazards

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-02-27
    DOI: 10.14278/rodare.254
    License: CC-BY-NC-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30759
Publ.-Id: 30759


Preface of a special issue of the American Journal of Science

Fischer, C.; Arvidson, R. S.

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

Permalink: https://www.hzdr.de/publications/Publ-30758
Publ.-Id: 30758


Crystal surface reactivity analysis using a combined approach of X-ray micro-computed tomography and vertical scanning interferometry

Kahl, W.-A.; Yuan, T.; Bollermann, T.; Bach, W.; Fischer, C.

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

Keywords: crystal surface reactivity; rate map; dissolution rate variability; X-ray micro-computed tomography (µ-CT); vertical scanning interferometry (VSI); reactive transport; fluid-rock interaction

Permalink: https://www.hzdr.de/publications/Publ-30757
Publ.-Id: 30757


Recombinant expression of ecto-nucleotide pyrophosphatase/phosphodiesterase 4 (NPP4) and development of a luminescence-based assay to identify inhibitors

Lopez, V.; Lee, S.-Y.; Stephan, H.; Müller, C. E.

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

Keywords: Antithrombotic drugs; assay development; ectonucleotidase; recombinant enzyme expression; high-throughput screening; luminescence detection; NPP4 inhibitors

Permalink: https://www.hzdr.de/publications/Publ-30756
Publ.-Id: 30756


Entwicklung eines Modells zur Grobstruktursimulation der Gas-Flüssigkeits-Strömung auf Querstromböden mit Hochleistungsventilen

Wiedemann, P.; Schubert, M.; Schleicher, E.; Hampel, U.

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

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

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

  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Computational Fluid Dynamics und Gasreinigung, 10.-11.03.2020, Bamberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30751
Publ.-Id: 30751


Development of tailored packings for Rotating Packed Beds

Gładyszewski, K.; Gross, K.; Qammar, H.; Kamiński, K.; Bieberle, A.; Schubert, M.; Skiborowski, M.; Górak, A.

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

Keywords: Rotating packed beds; HIGEE; anisotropic; foam packings; mass transfer; hydrodynamic; computer tomography

  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik, Adsorption und Extraktion, 26.-28.02.2020, Berchtesgaden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30749
Publ.-Id: 30749


Proton number fluctuations in sqrt(s_NN)= 2.4 GeV Au+Au collisions studied with HADES

Adamczewski-Musch, J.; Arnold, O.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Biernat, J.; Blanco, A.; Blume, C.; Böhmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Deveaux, C.; Dreyer, J.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzon, J. A.; Gernhäuser, R.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Höhne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kämpfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kohls, M.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Mangiarotti, A.; Markert, J.; Matulewicz, T.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morozov, S.; Müntz, C.; Münzer, R.; Naumann, L.; Nowakowski, K.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Piasecki, K.; Pietraszko, J.; Przygoda, W.; Ramos, S.; Ramstein, B.; Reshetin, A.; Rodriguez-Ramos, P.; Rosier, P.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Siebenson, J.; Silva, L.; Sobolev, Y. G.; Spataro, S.; Spies, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Zanevsky, Y.; Zumbruch, P.

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

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30746
Publ.-Id: 30746


Holographic vector meson melting in a thermal gravity-dilaton background related to QCD

Zöllner, R.; Kämpfer, B.

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

Permalink: https://www.hzdr.de/publications/Publ-30742
Publ.-Id: 30742


Temperature-dependent luminescence spectroscopic investigations of U(VI) complexation with the halides F- and Cl-

Demnitz, M.; Hilpmann, S.; Lösch, H.; Bok, F.; Steudtner, R.; Patzschke, M.; Stumpf, T.; Huittinen, N. M.

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

Keywords: uranyl; luminescence; complexation; halides; quenching

Downloads:

  • Secondary publication expected from 01.05.2021

Permalink: https://www.hzdr.de/publications/Publ-30741
Publ.-Id: 30741


Steel related activities and capabilities at HZDR

Gerbeth, G.

  • Invited lecture (Conferences)
    Sino-German Symposium „Future Steel“, 18.07.2019, Shanhai, China

Permalink: https://www.hzdr.de/publications/Publ-30740
Publ.-Id: 30740


Synthesis, radiolabeling and first biological characterization of 18F-labeled xanthine derivatives for PET imaging of Eph receptors

Pretze, M.; Neuber, C.; Kinski, E.; Belter, B.; Köckerling, M.; Caflisch, A.; Steinbach, J.; Pietzsch, J.; Mamat, C.

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

Keywords: RTK imaging; cancer; malignant melanoma; radiolabeling; kinase inhibitors

Downloads:

  • Secondary publication expected from 28.04.2021

Permalink: https://www.hzdr.de/publications/Publ-30738
Publ.-Id: 30738


Numerical investigation on the effect of transversal fluid field deformation on heat transfer in a rod bundle with mixing vanes

Tas-Köhler, S.; Lecrivain, G.; Krepper, E.; Unger, S.; Hampel, U.

Spacer grids of fuel rod assemblies are equipped with vanes, which promote flow mixing and turbulence within and across the sub-channels, thereby enhancing the heat transfer. First, a literature study about the various effect of the spacer grid has on the sub-channel thermo-hydrodynamics is provided. It follows, that the multiple effects on the vane angle are insufficiently understood. The effect of the vane angle on design parameters, namely the evolution of the Nusselt number, the pressure drop, the cross and swirl flows, is here further discussed and supplemented by own simulations. The effect of the velocity gradient tensor ∇⊗u, decomposed into a strain and a vorticity contribution, is also looked at downstream of the spacer grid. The RNG k-ε turbulence model was found to provide results best matching the experimental data available in the literature. The use of vanes results in the formation of a downstream vortex. As the flow develops downstream of the spacer grid, the vortex migrates away from the sub-channel center and eventually weakens. In line with the presented literature survey, it is confirmed that a vane angle of about 30° provides optimal swirl and cross flows, resulting in an enhanced heat transfer.

Keywords: Literature analysis; Vortex generator; Vane angle; Rod bundle; Vorticity; Turbulent flow; Heat transfer

Permalink: https://www.hzdr.de/publications/Publ-30737
Publ.-Id: 30737


Understanding the local structure of Eu3+ and Y3+ stabilized zirconia – Insights from luminescence and X–ray absorption spectroscopic investigations

Eibl, M.; Shaw, S.; Prieur, D.; Roßberg, A.; Wilding, M. C.; Hennig, C.; Morris, K.; Rothe, J.; Stumpf, T.; Huittinen, N. M.

This study combines bulk structural and spectroscopic investigations of Eu3+ or Y3+/Eu3+ co–doped tetragonal and cubic zirconia polymorphs to an gain in–depth understanding of the solid solution formation process. Our bulk structural characterizations show that the dopant is homogenously distributed in the ZrO2 host structure resulting in an increase of the bulk symmetry with increasing dopant substitution (from 8 mol% to 26 mol%). The local site–symmetry around the Eu3+–dopant, however, determined with luminescence spectroscopy (TRLFS), remains low in all samples. Results obtained with X–ray pair distribution function (XPDF) and X–ray absorption spectroscopy (EXAFS) show that the average coordination environment in the stabilized zirconia structures remains practically unchanged. Despite of this very constant average dopant environment, site–selective TRLFS data show the presence of three non–equivalent Eu3+ environments in the ZrO2 solid structures. These Eu3+ environments are assumed to arise from Eu3+ incorporation at superficial sites which increase in abundance as the size of the crystallites decrease, and incorporation on two bulk sites differing in the location of the oxygen vacancies with respect to the dopant cation.

Keywords: Eu3+; Y3+; incorporation; stabilized ZrO2; TRLFS; EXAFS; XPDF

Permalink: https://www.hzdr.de/publications/Publ-30736
Publ.-Id: 30736


Conductive ITO interfaces for optoelectronic applications based on highly ordered inverse opal thin films

Galle, L.; Ehrling, S.; Lochmann, S.; Kaskel, S.; Bischoff, L.; Grothe, J.

A three-step fabrication process for optically transparent, conducting ITO thin films with an intrinsic inverse opal structure is described. The preparation is based on colloidal crystal templating using polystyrene microspheres (100 nm - 600 nm). For the realization of varying periodicities in this structure, different sphere sizes were assembled to monolayers on a substrate by spin coating and infiltrated afterwards similarly. The influence of rotation parameters as well as dispersion concentration was studied. Using this approach different geometries of the surface are accessible by systematically varying the rotation parameters and infiltration volume. The thin films show excellent anti-reflection behavior, good transmission ( >80 % in the visible range) as well as a low resistance of 200 Ω/sq compared to other porous ITO interfaces. The properties are very promising for several optoelectronic applications such as in- or out-coupling structures in solar cells and organic light emitting diodes.

Keywords: ITO thin films; conducting; transmission; optoelectronics

Permalink: https://www.hzdr.de/publications/Publ-30734
Publ.-Id: 30734


Sputtering of nanostructured tungsten and comparison to modelling with TRI3DYN

Stadlmayr, R.; Szabo, P. S.; Mayer, D.; Cupak, C.; Dittmar, T.; Bischoff, L.; Möller, S.; Rasinski, M.; Wilhelm, R. A.; Möller, W.; Aumayr, F.

He-induced nanostructured tungsten (so called W-fuzz) was bombarded with Ar ions under 60 degree and the dynamic erosion behaviour experimentally investigated. By using a highly sensitive quartz-crystal-microbalance technique in a particle catcher configuration the sputtered particles distribution of Wfuzz could be evaluated. In contrast to a at sample, where sputtered particles are emitted primarily in forward direction, we find that W-fuzz samples emit sputtered particles preferably in backward direction (i.e. in the direction of the incident ion beam). After continuous Ar irradiation of a W-fuzz sample the distribution approaches that of a at sample. In addition to experimental data we also show modelling results obtained with a state-of-the-art Monte-Carlo (MC) binary collision approximation (BCA) code TRI3DYN in full 3D. Surface morphology changes as monitored by SEM as well as the dynamic sputtering behaviour can be well reproduced by the full 3D MC-BCA code.

Keywords: Erosion; Quartz crystal microbalance; TRI3DYN; Surface roughness; Sputtering; nanostructured tungsten; W-fuzz

Downloads:

  • Secondary publication expected from 07.02.2021

Permalink: https://www.hzdr.de/publications/Publ-30733
Publ.-Id: 30733


Hollow Au@TiO2 porous electrospun nanofibers for catalytic applications

Kumar, L.; Singh, S.; Horechyy, A.; Formanek, P.; Hübner, R.; Albrecht, V.; Weißpflog, J.; Schwarz, S.; Puneet, P.; Nandan, B.

Catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles were fabricated using a combination of sol-gel chemistry and coaxial electrospinning technique. We report the fabrication of catalytically active porous and hollow titania nanofibers encapsulating gold nanoparticles (AuNPs) using a combination of sol-gel chemistry and coaxial electrospinning technique. The coaxial electrospinning involved the use of a mixture of poly(vinyl pyrrolidone) (PVP) and titania sol as the shell forming component, whereas a mixture of poly(4-vinyl pyridine) (P4VP) and pre-synthesized AuNPs constituted the core forming component. The core-shell nanofibers were calcined stepwise up to 600 °C which resulted in decomposition and removal of the organic constituents of the nanofibers. This led to the formation of porous and hollow titania nanofibers, where the catalytic AuNPs were embedded in the inner wall of the titania shell. The catalytic activity of the prepared Au@TiO2 porous nanofibers was investigated using a model reaction of catalytic reduction of 4-nitrophenol and Congo red dye in the presence of NaBH4. The Au@TiO2 porous and hollow nanofibers exhibited excellent catalytic activity and recyclability, and the morphology of the nanofibers remained intact after repeated usage. The presented approach could be a promising route for immobilizing various nanosized catalysts in hollow titania supports for the design of stable catalytic systems where the added photocatalytic activity of titania could further be of significance.

Permalink: https://www.hzdr.de/publications/Publ-30732
Publ.-Id: 30732


The role of boron on exchange coupling in NiFe/Ru1−xBx/FeCo trilayer structures

Mckinnon, T.; Hübner, R.; Heinrich, B.; Girt, E.

In this work, we study the interlayer exchange coupling, J, between two NiFe and FeCo layers in a series of NiFe/Ru1-xBx(d)/FeCo synthetic antiferromagnet (SAF) samples, where the thickness of the spacer layer, d, is varied from 0.4 nm to 0.9 nm, and the boron concentration, x, is varied from 0 to 15 at. %. The samples are studied as deposited and after being annealed at 250 °C. B is deposited into the Ru spacer layer to investigate what occurs after annealing a FeCoB/Ru/FeCoB SAF structure, which is commonly used in modern nanoscale magnetic devices, in which the FeCoB layer crystallizes to FeCo and B diffuses to adjacent layers. We find that J in as-deposited samples is relatively unaffected by adding up to 15% B into the Ru spacer layer. However, after annealing at 250 °C, J changes the sign from antiferromagnetic coupling to ferromagnetic coupling for spacer layers thinner than 0.45 nm for 5% and 10% B and thinner than 0.525 nm for 15% B. We used transmission electron microscopy energy-dispersive x-ray spectroscopy in order to investigate the diffusion of atoms within a similar Ta(2.5 nm)/NiFe(0.8 nm)/Ru1-xBx(23 nm) layer structure. We find that after annealing at 250 °C, the sample containing 15% B within the Ru85B15 layer had significantly more diffusion of Fe into the Ru85B15 layer, from the NiFe layer, as compared to the sample with 0% B. Thus, the presence of B within the spacer layer enhances diffusion of Fe into the spacer layer.

Permalink: https://www.hzdr.de/publications/Publ-30731
Publ.-Id: 30731


Electric and magnetic dipole strength in 54Fe

Schwengner, R.; Massarczyk, R.; Bemmerer, D.; Beyer, R.; Bhike, M.; Brown, B. A.; Butterling, M.; Derya, V.; Dietz, M.; Fiedler, F.; Frotscher, A.; Gayer, U.; Grieger, M.; Hartmann, A.; Junghans, A. R.; Kögler, T.; Krishichayan, F.; Ludwig, F.; Lutz, B.; Pai, H.; Römer, K.; Sieja, K.; Szücs, T.; Takacs, M.; Tornow, W.; Wagner, A.

The dipole strength of the N=28 nuclide 54Fe was studied in photon-scattering experiments using bremsstrahlung produced with electron beams of energies of 7.5 and 13.9 MeV at the gELBE facility as well as using quasi-monoenergetic and linearly polarized photon beams of 26 energies within the range from 5.5 to 11.4 MeV at the HIgS facility. About 100 J=1 states were identified, out of them 19 with 1+ and 30 with 1- assignment. The quasicontinuum of unresolved transitions was included in the analysis of the spectra and the intensities of branching transitions were estimated on the basis of simulations of statistical γ-ray cascades. As a result, the photoabsorpton cross section up to the neutron-separation energy was determined and compared with predictions of statistical reaction codes. The experimental M1 strengths from resolved 1+ states are compared with results of large-scale shell-model calculations.

Keywords: Photon scattering; nuclear resonance fluorescence; angular distributions; polarization; statistical gamma-ray cascades; photoabsorption cross section; dipole excitations; shell model

Permalink: https://www.hzdr.de/publications/Publ-30730
Publ.-Id: 30730


Thermodynamic Reference Database (THEREDA) – Present activities

Moog, H. C.; Bok, F.; Freyer, D.; Gaona, X.; Thoenen, T.

The THEREDA project [1] aims at providing an extensive thermodynamic database for the modeling of solubility equilibria in aqueous solutions within the context of nuclear waste disposal. Focus is laid on saline solutions, typically with an ionic strength > 1M, using the Pitzer approach [2].
THEREDA is operated by five research institutions. A web-based user interface is used for data capture and documentation. The primary products, however, are ready-to-use data files for PHREEQC, Geochemist’s Workbench, CHEMAPP, and (to a limited extent) EQ3/6. In addition, a code-independent, generic format (JSON) is available for download. Before release, data sets are subject to rigid, internal checks. More than 200 test calculations are used to continously ensure the correctness of calculated results, both in terms of earlier test runs and between different codes.
While extending the database, experimental data for various chemical systems are recorded. The agreement with model calculations using THEREDA are documented. This “positive list” is continously being extended.
In response to the limited lifetime of existing codes and to extend our user base, efforts are undertaken to support two additional codes, GEMS and TOUGHREACT.

[1] H. C. Moog et al. (2015): Appl. Geochem. (55) 72-84. http://dx.doi.org/10.1016/j.apgeochem.2014.12.016.
[2] K. S. Pitzer (1991): Activity Coefficients in Electrolyte Solutions (2nd ed.). CRC Press, ISBN 0-8493-5415-3.

Keywords: THEREDA; Pitzer; Thermodynamic Reference Database

  • Lecture (Conference) (Online presentation)
    Goldschmidt2020, 21.-26.06.2020, Honolulu, USA
  • Contribution to proceedings
    Goldschmidt2020, 21.-26.06.2020, Honolulu, USA
    Golschmidt2020: Geochemical Society

Permalink: https://www.hzdr.de/publications/Publ-30728
Publ.-Id: 30728


Microstructure, texture and hardness of a metastable β-titanium alloy after bar-rolling and annealing

Gu, B.; Chekhonin, P.; Schaarschuch, R.; Oertel, C.-G.; Xin, S. W.; Ma, C. L.; Zhou, L.; Gan, W. M.; Skrotzki, W.

The microstructure and texture evolution of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe alloy during bar-rolling and after various thermal treatments was investigated by high-energy synchrotron diffraction and electron backscatter diffraction. Bar-rolling is applied in the (α+β)-phase field in order to achieve a bi-modal (duplex) microstructure. The effect of dynamic recrystallized and recovered zones on texture of Ti5321was analyzed separately, as well as the texture of primary α-precipitates and secondary α-lamellae. The texture of the recovered zones is characterized by a cube component ({001}<100>) plus α- and γ-fibre with dominant {100}<110>, {112}<110>, {111}<110> components, while the texture of the recrystallized zones is a strong cube texture. After aging or recrystallization plus aging, this texture component remains, while it disappears after solution treatment. The primary α-precipitates have their c-axes perpendicular to the rolling direction and do not follow the Burgers orientation relationship. This texture characteristics remains after various thermal heat treatments. Secondary α-lamellae obey the Burgers orientation relationship. Moreover, a variant selection of secondary α-lamellae occurs. The mechanism of texture formation of the β-phase and the precipitation behavior of the α-phase is discussed.
The hardness increase can be attributed to size, shape and volume fraction of the α-precipitates.
Different combinations of primary α- and secondary α-precipitates make an increase in hardness of about 11%.

Keywords: Metastable β-titanium alloy; Bar-rolling; Microstructure; Texture; Microhardness

Downloads:

  • Secondary publication expected from 06.02.2021

Permalink: https://www.hzdr.de/publications/Publ-30724
Publ.-Id: 30724


Regulation of bone regeneration

Jung, F.; Pietzsch, J.

This editorial presents three comprehensive reviews of recent preclinical and clinical findings supporting the healing of critical bone defects through adjuvant therapy approaches, which have been published in a special issue. In summary, these articles highlight current concepts that attempt to improve osteogenesis and bone healing using small molecule drugs and intelligent drug delivery methods. The main conclusions lead to an evaluation of the modulation of angiogenesis and microcirculation as a very promising concept. The modulation of inflammation, on the other hand, was evaluated as critical with respect to the start and duration of therapy. Novel solutions are expected from a targeted modulation of bone metabolism, the use of bifunctional or hybrid compounds, appropriate drug combinations and delivery systems.

Keywords: Adjuvant drug-assisted bone healing; angiogenesis; anti-resorptive drugs; bone metabolism; critical bone defect; compound fracture; drug release; inflammation; local therapy; systemic therapy; osteoconductive drugs; osteoinductive drugs; pleiotropic effects; targeted therapy; tissue regeneration

  • Clinical Hemorheology and Microcirculation 73(2020)3, 379-380
    DOI: 10.3233/CH-199101

Downloads:

  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30722
Publ.-Id: 30722


Relationships between depth-resolved primary radiation damage, irradiation-induced nanostructure and nanoindentation response of ion-irradiated Fe-Cr and ODS Fe-Cr alloys

Vogel, K.; Heintze, C.; Chekhonin, P.; Akhmadaliev, S.; Altstadt, E.; Bergner, F.

Ion irradiations are indispensable for exploring radiation effects on materials, for example, radiation hardening. However, the extraction of radiation hardening as function of displacement damage from the nanoindentation (NI) response of self-ion-irradiated metallic alloys is a challenge. In particular, recent attempts suffer from interference with contributions arising from injected self-interstitial atoms. Moreover, instances of available microstructural evidence and NI results reported for the same material and same irradiation are rare. In order to tackle these issues, the depth-dependent irradiated microstructure and the NI response were analyzed for Fe-9Cr and oxide dispersion strengthened Fe-Cr alloys irradiated with 5 MeV iron ions. Cross-sectional transmission electron microscopy indicated the appearance of irradiation-induced dislocation loops but no other types of visible microstructural changes. NI indicated maxima of the radiation hardening as function of contact depth. Links between the depth-resolved primary radiation damage, the observed depth-dependent characteristics of loops and the measured hardening are considered. As a key point, the link between loops and hardening requires the integration of the local hardening contributions over the indentation plastic zone. Calculations and measurements are compared with respect to both the depth position of maximum hardening and the substrate effect. The role of the model assumptions is discussed with special emphasis on the plastic zone size and the superposition of hardening contributions. The latter is found to be material-specific. The model also allows hardening contributions arising from displacement damage and injected interstitials to be separated.

Keywords: Fe-alloys; ion irradiation; TEM; nanoindentation; irradiation hardening

Related publications

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30720
Publ.-Id: 30720


HIM and AFM Data set from first AFM in the HIM test

Hlawacek, G.; Andany, S.

In this work, the integration of an atomic force microscope (AFM) into a helium ion microscope
(HIM) is reported for the first time. The helium ion microscope is a powerful instrument, capable of sub-
nanometer resolution imaging and machining nanoscale structures, while the AFM is a well-established
versatile tool for multiparametric nanoscale metrology. Combining the two techniques opens the way for
unprecedented, in-situ, correlative analysis at the nanoscale. Nanomachining and analysis can be
performed without contamination of the sample as well as avoiding environmental changes between
processing steps. The practicality of the resulting tool lies in the complementarity of the two techniques as
the AFM offers not only true 3D topography maps---something the HIM can only provide in an indirect
way---but also allows for nanomechanical property mapping, as well as electrical and magnetic
characterisation of the sample after focused ion beam materials modification with the HIM. The
experimental setup is described and evaluated through a series of correlative experiments, demonstrating
the feasibility of the integration.

Keywords: Helium Ion Microscopy; Atomic Force Microscopy

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-02-04
    DOI: 10.14278/rodare.249

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30718
Publ.-Id: 30718


Dynamics of Bubble Formation at Micro-orifices under Constant Gas Flow Conditions

Mohseni, E.; Jose Kalayathine, J.; Reinecke, S.; Hampel, U.

Fine gas dispersion into a liquid is requested in a number of industrial applications. One way to achieve finer gas dispersion is to downsize the openings at which the gas bubbles are generated. Accordingly, we have investigated the dynamics of bubble formation from submerged orifices ranging from 0.04 to 0.8 mm at a comprehensive range of gas flow rates for a system of air and deionized water. In this range of orifice size, we observe a different mechanism of bubble formation compared with millimeter-range orifices. We discuss the observations on the basis of temporal change of the bubble shape, bubble base expansion, and detachment criteria. At submillimeter orifices, the mechanism of bubble formation is highly influenced by the capillary pressure and the gas kinetic energy. The latter results in congregation of small bubbles in the vicinity of the orifice, even at very small gas flow rates. Moreover, we studied the evolution of individual forces applied to the surface of bubbles during their formation. We found that the formation of bubbles at submillimeter orifices cannot be described with a quasi-static force balance. Finally, we present a bubbling regime map using proper dimensionless numbers.

Keywords: Bubble Formation; Submillimeter Orifices; Bubbling Regime; Bubbling Dynamics; Stainless Steel Orifice

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-02-03
    DOI: 10.14278/rodare.247

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30717
Publ.-Id: 30717


The Late Paleozoic tectonometamorphic evolution of Patagonia revisited: Insights from the pressure-temperature-deformation-time (P-T-D-t) path of the Gondwanide basement of the North Patagonian Cordillera (Argentina)

Oriolo, S.; Schulz, B.; Gonzalez, P. D.; Bechis, F.; Olaizola, E.; Krause, J.; Renda, E. M.; Vizàn, H.

Combined field structural analysis with in situ EPMA (electron probe microanalysis) Th-U-Pb monazite dating, petrologic and microstructural data provide a reconstruction of the pressure-temperature-deformation-time (P-T-D-t) path of the Gondwanide basement of the North Patagonian Cordillera. For samples from the Challhuaco hill, the timing of development of the metamorphic S2 foliation and associated L2 lineation and tight to isoclinal F2 folds is constrained by monazite ages of 299 ± 8 and 302 ± 16 Ma during peak metamorphic conditions of ca. 650 °C and 11 kbar, achieved during prograde metamorphism and progressive deformation. Metamorphism and deformation of metamorphic complexes of the North Patagonian Andes seem to record Late Paleozoic crustal thickening and are coeval with metamorphism of accretionary complexes exposed further west in Chile, suggesting a coupled Late Devonian-Carboniferous evolution. Instead of the result of continental collision, the Gondwanide orogeny might thus be essentially linked to transpression due to advancing subduction along the proto-Pacific margin of Gondwana. On the other hand, a second generation of monazite ages of 171 ± 9 and 170 ± 7 Ma constrain the timing of low-grade metamorphism related to kink band and F3 open fold development during Jurassic transtension and emplacement of granitoids. Finally, a Cretaceous overprint, likely resulting from hydrothermal processes, is recorded by monazite ages of 110 ± 10 and 80 ± 20 Ma, which might be coeval with deformation along low-grade shear zones during the onset of Andean transpression.

Keywords: EPMA Th-U-Pb monazite dating; in situ petrochronology; garnet metapelite thermobarometry; Upper Paleozoic; Terra Australis; southwestern Gondwan

Permalink: https://www.hzdr.de/publications/Publ-30714
Publ.-Id: 30714


Epithermal Ag-(Au)-Zn-Pb mineralisation in the northern part of the Freiberg District, Germany

Swinkels, L.; Rossberg, C.; Schulz-Isenbeck, J.; Frenzel, M.; Gutzmer, J.; Burisch, M.

The polymetallic veins in the Freiberg district form one of the largest epithermal systems in Europe. It produced over 5600 t of Ag during active mining between 1168 and 1969. Historically, exploration focused on the centre of the district, with peripheral sub-districts exploited only to shallow depth. Recent exploration activity focuses on these peripheral regions, yet only a limited amount of modern geochemical data is available and the underlying ore-forming processes are insufficiently understood. Here, we present preliminary geochemical, fluid inclusion, and petrographic data for 55 samples from the historical mine camps of Reinsberg and Kleinvoigtsberg (northern peripheral sub-district). Samples were selected from the scientific collections of the TU Bergakademie Freiberg and collected from outcrops in the field. They include vertical profiles of two major veins extending from 18 to 532 meters below ground level. The data is combined with previous literature descriptions to develop a genetic model for the northern sector of the Freiberg district. Mineralisation in the Reinsberg and Kleinvoigtsberg mine camps is hosted by polystadial Ag-(Au)-Zn-Pb veins. The paragenetically oldest mineralisation, Stage I, is dominated by base metal sulphides and quartz; it has been encountered most prominently in the deepest levels of the historic mines. The occurrence of carbonates and the introduction of Ag-Sb sulphides and sulfosalts mark the transition to Stage IIa. At shallower mining levels, carbonate recedes and quartz returns as the major gangue mineral, indicating the transition to Stage IIb. Stage IIb vein infill is often breccia-textured and carry the highest silver grades. At the present day surface, veins consist of quartz and host rock fragments, forming a cockade breccia texture (stage III). Although no visible sulphides are present, such quartz breccias contain up to 2.5 g/t Au. Recent studies show that the main ore-forming process in the northern district seems to be cooling - causing distinct district and vein-scale zoning. Effervescence of CO2 is most likely the underlying process behind the transition from quartz to carbonate gangue. An understanding of mineral zonation and its underlying ore-forming processes can be translated into mappable exploration criteria. In this case, the highest ore grades (Ag and Au) are associated with Stage IIb (Ag-Sb-sulfosalts-quartz assemblage). This assemblage occurs always wedged between the carbonate-rich assemblage of Stage IIa (below) and the sulphide-poor quartz Stage III (above). This systematic relation may well constitute an important exploration vector for the Freiberg district.

  • Lecture (Conference)
    Geomünster 2019, 22.-25.09.2019, Münster, BRD

Permalink: https://www.hzdr.de/publications/Publ-30713
Publ.-Id: 30713


Mineralogical zoning within the Freiberg epithermal Ag- (Au)-Pb-Zn-Cu system, Germany

Swinkels, L.; Rossberg, C.; Schulz-Isenbeck, J.; Burisch, M.; Frenzel, M.; Gutzmer, J.

The Freiberg epithermal system comprises numerous hydrothermal veins with rich Ag-(Au)-Pb-Zn-Cu mineralisation. Even after more than 800 years of extensive mining, substantial resources remain in the northern sub-districts. This area is subject to recent exploration activity. Preliminary petrographic data of two vertical profiles from the northern part of the district are presented and a new model for the district-scale zoning is proposed. The highest Ag grades occur in Ag-Sb-S-quartz veins and seem to systematically occur above an Ag-Sb-S-Carbonate stage and below Sb-S-quartz mineralisation. This high-grade Ag mineralisation is relatively distal, shallow, and abundant in the northwest sector of the Freiberg district. This, and similar insights may be used to develop new exploration vectors for the Freiberg district.

  • Poster
    15th Biennial Meeting of the Society for Geology Applied to Mineral Deposits, 26.-30.08.2019, Glasgow, UK

Permalink: https://www.hzdr.de/publications/Publ-30712
Publ.-Id: 30712


Explaining metal zonation at the Lisheen Zn-Pb deposit, Ireland

Frenzel, M.; Röhner, M.; Gutzmer, J.; Burisch, M.; Cook, N. J.; Gilbert, S.; Ciobanu, C. L.; Güven, J.

Metal zonation is an important feature of low-temperature carbonate-hosted Zn-Pb deposits. Its origin, however, remains poorly understood. In this article, we use the Lisheen deposit in Ireland as a case study to show how thermodynamic modelling can explain these zonation patterns. Based on input data derived from fluid inclusion studies, bulk ore geochemistry and accepted models of ore formation in the Irish Orefield we construct a reaction path model that successfully accounts for the major features of the mineralisation, most importantly the presence of Cu-Ni-As-rich core zones around hydrothermal feeder structures, surrounded by more distal Fe-Zn-Pb-rich mineralisation. The outcomes of this study strongly support current metallogenetic models for Irish-type deposits and have implications for near-deposit exploration.

  • Lecture (Conference)
    15th Biennial Meeting of the Society for Geology Applied to Mineral Deposits, 26.-30.08.2019, Glasgow, UK
  • Lecture (Conference)
    Geomünster 2019, 22.-25.09.2019, Münster, BRD

Permalink: https://www.hzdr.de/publications/Publ-30711
Publ.-Id: 30711


Radionuclides from Space

Merchel, S.; Lachner, J.; Rugel, G.; Wallner, A.

The determination of long-lived radionuclides by means of accelerator mass spectrometry (AMS) is usually outstandingly successful when an interdisciplinary team comes together. The “heart” of AMS research is of course an accelerator equipped with sophisticated ion sources, analytical tools and detectors run by experienced and ambitious physicists. Setting-up and further developing AMS systems is one of the most interesting and challenging topics.
Another essential part in AMS research is the radiochemical sample preparation preceding the measurement where the goals are: 1.) Enrichment of nuclides of interest by reduction of the matrix. 2.) Depletion of isobars. 3.) Production of a thermally stable chemical compound such as AgCl, AgI, Al₂O₃, BeO, CaF₂, Fe₂O₃, MnO₂ etc. of relatively high purity.
One of the most interesting applications of AMS is the analysis of extraterrestrial material such as meteorites. While being at the surface of their so-called parent body (asteroids, Moon, Mars,…) and again while travelling through space as a so-called meteoroid, these unique pieces are bombarded by high-energy particles from the cosmic radiation. Long-lived radionuclides are produced in the material by nuclear reactions in both stages potentially until saturation. However, they start decaying in a third stage, when meteorites have landed on Earth because the cosmic radiation is shielded by the Earth’s atmosphere and magnetic field. Hence, the concentrations of radionuclides are records of all three stages allowing the reconstruction of the exposure history (duration, shielding, size,…) of the individual meteorite and the cosmic radiation itself.
Meteorite projects and projects with artificially-irradiated targets are also well-suited to develop measurements of “new” AMS radionuclides as the isotopic ratios are at much higher levels (up to 10-10 radioactive/stable) than e.g. in terrestrial natural samples (10-14-10-16). The AMS community is very open to any input and questions from “outside”. The DREsden AMS (DREAMS) and other European AMS facilities offer researchers from academia free measurements via a Trans-National-Access proposal program (www.ionbeamcenters.eu) and also national access (www.dresden-ams.de; DREAMS only).

Keywords: AMS; meteorite; cosmogenic; cosmic radiation; radionuclide

  • Poster
    53rd Annual Conference of the German Society for Mass Spectrometry DGMS including 27th ICP-MS User´s Meeting, 01.-04.03.2020, Münster, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30709
Publ.-Id: 30709


Modelling indium deportment in a polymetallic sulfide ore

Frenzel, M.; Bachmann, K.; Carvalho, J.; Relvas, J.; Pacheco, N.; Gutzmer, J.

Based on a combination of bulk-ore geochemistry and mineralogical and microanalytical data, this study is the first to develop a quantitative model of indium deportment in massive sulfide ores, demonstrating how regularities in indium partitioning between different minerals can be used to predict its mineralogical deportment in individual drill-core samples. Bulk-ore assays of As, Cu, Fe, Pb, S, Sb, Sn, Zn, and In are found to be sufficient for reasonably accurate predictions. The movement of indium through the ore processing plants is fully explained by its mineralogical deportment, allowing for specific mine and process planning. The novel methodologies implemented in this contribution for (1) the assessment of analytical uncertainties, (2) the prediction of complex mineralogical deportments from bulk geochemical data, and (3) the modeling of byproduct recoveries from individual mining blocks, are of general applicability to the geometallurgical assessment of many other byproduct metals in polymetallic sulfide ores, including Ga, Ge, Mo, Re, Se, Te, as well as the noble metals.

  • Lecture (others)
    Geometallurgy Workshop, 15th SGA Biennial Meeting, Glasgow, 26.08.2019, Glasgow, UK

Permalink: https://www.hzdr.de/publications/Publ-30708
Publ.-Id: 30708


Laser ablation ICP-MS trace element systematics of hydrothermal pyrite in gold deposits of the Kalgoorlie district, Western Australia

Godefroy-Rodríguez, M.; Hagemann, S.; Frenzel, M.; Evans, N. J.

The Kalgoorlie district in the Archean Yilgarn Craton of Western Australia containstwoworld-classgolddeposits:thegiant Golden Mile shear-zone system and the Mt Charlotte quartz-vein stockworks. Mineralization occurs in three styles:(a) Fimiston style is characterized by ankerite-pyrite ± hematite-magnetite-gold replacement, (b) Oroya style overprintsFimiston ore in the shear zones and is characterized by silica-ankerite-V-muscovite-pyrite ± pyrrhotite-gold-telluridereplacement and (c) Mt. Charlotte style is characterized by veins with ankerite-sericite ± albite-pyrite-pyrrhotite-goldselvages. Hydrothermal pyrite is ubiquitous in all styles and occurs in several stages. Laser ablation inductively coupledplasma mass spectrometry (LA-ICP-MS) spot analyses (n= 652) were collected on 54 representative samples of pyritefrom three deposits. Smooth sections in the ablation spectra were selected for quantitative analysis excluding peakscaused by micron-sized inclusions. Linear mixed effects (LME) modeling of the analytical results indicates no system-atic differences between the Fimiston, Oroya and Mt Charlotte styles. The variance introduced to the dataset bygeological variability reflected in random differences between samples and deposits is large. This may be a major reasonfor difficulties in distinguishing the differences due to mineralization style. However, there are clear differences betweenpyrites co-existing with different mineral assemblages. These indicate a strong control on pyrite chemistry by thecomposition of the hydrothermal fluids. Finally, Au-Te-As systematics show that a substantial proportion of the analyzedpyrites in all deposits fall into the field of gold saturation consistent with the known metallurgical character of the ores.Mineralogical studies, ultra-fine grinding and recovery by cyanide leach show that > 82% of all gold is present in nativegrains or in Au-Ag-tellurides. The refractory nature of theFimiston pyrite concentrates is due to clusters of micron- tonano-sized inclusions rather thandue to abundant lattice-bound gold.

Keywords: Kalgoorlie; trace elements; LA-ICP-MS; gold; pyrite

Permalink: https://www.hzdr.de/publications/Publ-30707
Publ.-Id: 30707


Halogens in hydrothermal sphalerite record origin of ore-forming fluids

Frenzel, M.; Cook, N. J.; Ciobanu, C. L.; Slattery, A.; Wade, B.; Gilbert, S.; Ehrig, K.; Burisch, M.; Verdugo-Ihl, M. R.; Voudouris, P.

The halogens Cl and Br are sensitive indicators for the origin of ore-forming fluids. Here, we use a combination of microchemical and microscopic methods to show that measurable concentrations of these elements commonly occur as atomic-scale substitutions within hydrothermal sphalerite. Furthermore, the Cl/Br ratios of the halogen-rich sphalerites investigated in this study are indistinguishable from those of the corresponding ore fluids. Thus, they record fluid compositions, which are in turn closely related to fluid origin. Given the abundance of sphalerite in hydrothermal base-metal deposits, as well as the relative ease of conducting in-situ microchemical analyses, the halogen signature of sphalerite has the potential to become a sensitive proxy to distinguish between different ore-forming environments.

Downloads:

  • Secondary publication expected from 12.05.2021

Permalink: https://www.hzdr.de/publications/Publ-30705
Publ.-Id: 30705


Nanoscale compositional segregation in complex In-bearing sulfides

Krause, J.; Reddy, S. M.; Rickard, W. D. A.; Saxey, D.; Fougerouse, D.; Bauer, M. E.; Seifert, T.; Gutzmer, J.

Indium-bearing sphalerites from the Hämmerlein skarn deposit, located in the western Erzgebirge (Germany), show complex distribution patterns of major and minor elements on a micrometer to sub-micrometer scale. However, with the spatial resolution of traditional analytical methods, such as SEM-based image analysis and field emission electron probe microanalysis (FE-EPMA), many features in these samples cannot be resolved. It remains unclear whether Cu, In and Fe are in solid solution in the sphalerite or form discrete phases.
Atom probe tomography combined with transmission Kikuchi diffraction has been used to resolve the compositional heterogeneity and the nanostructure of these complex In-Cu-Fe-sphalerites. The obtained data indicate a complex structure with micro- to nanometer sized, plate-shaped inclusions of chalcopyrite in the sphalerite. In addition, a nanometer scale In-Cu-sulfide phase forms plate-like segregations in the sphalerite. All types of segregations have similar crystal structure and record the same crystal orientation indicating that they likely formed by exsolution.
The results indicate that complex sulfides containing cations of more than one element as minor or major constituents may represent discrete, exsolved phases, rather than solid solutions. This heterogeneous nature will affect the nanoscale properties of the sphalerite, which may have implications for the economic extraction of precious elements such as In. Furthermore these nanoscale properties will open up new perspectives on formation processes of In-Cu-Fe-sphalerites, which might be relevant for other chemically complex minerals as well.

  • Open Access Logo Contribution to proceedings
    Goldschmidt Barcelona 2019, 18.-23.08.2019, Barcelona, Spanien

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30700
Publ.-Id: 30700


Mineralogy of the polymetallic Waschleithe Zn-Pb-(W) skarn – implications for skarn genesis in the Schwarzenberg district, western Erzgebirge, Germany

Reinhardt, N.; Frenzel, M.; Gutzmer, J.; Meinert, L. D.; Gerdes, A.; Burisch, M.

The Schwarzenberg district (SD) in the western Erzgebirge comprises a series of polymetallic skarn bodies with significant resource potential for Sn, W, Zn, and In. Skarn mineralisation in the SD is hosted by low- to medium-grade metasedimentary units forming the so-called Schwarzenberg Gneiss Dome (SGD). Recent exploration, mainly for Sn, W, and In, targeted the large Globenstein, Hämmerlein and Tellerhäuser skarn bodies (several km strike length). Fertile skarn mineralisation in these skarns is related to the late- to post-collisional phase of the Variscan Orogeny (325-295 Ma). Economically important large skarn bodies as well as smaller satellites of the SGD have thus far only been investigated individually, rather than being considered part of a potentially district-wide mineralizing system (~ 12 x 15 km). The Waschleithe skarn in the far north of the SGD is a typical example for a smaller skarn body. Considering its distal position within the SGD it provides valuable insight into district-scale mineral zoning. Mineralisation occurs within two skarn horizons hosted by marble interlayered with mica schists. The sharp contact between skarn and marble is well exposed in historical mine workings. Coarse-grained pyroxene (hedenbergite-diopside), finer-grained subordinate yellowish-green andraditic garnet and Mn-rich pyroxenoids are the dominant constituents of the prograde skarn mineral assemblage. All of them overprint the metamorphic microfabric of the marble. A retrograde skarn assemblage is only weakly developed and consists mainly of ilvaite, epidote, vesuvianite, amphibole, chlorite, quartz, fluorite and hydrothermal calcite. Ore minerals associated with the retrograde mineral assemblage may be grouped into three different assemblages: 1) magnetite, 2) sphalerite, galena, pyrite, and chalcopyrite and 3) scheelite. The retrograde ore mineral assemblages show no association with paragenetically late chlorite, indicating that they formed relatively early during retrograde skarn formation. The marble front, dark pyroxenes, relatively low garnet/pyroxene ratios and the presence of Mn-bearing pyroxenoids indicate that the Waschleithe skarn formed distal to its fluid source relative to skarns with a more proximal mineralogy, such as Hämmerlein. Thus, Waschleithe represents a distal equivalent to the larger skarns of the SGD situated farther to the south. A genetic link between the skarns of the SGD requires a substantial re-evaluation of the size and exploration potential of this mineral system. To test this hypothesis a comprehensive set of mineralogical, geochemical and geochronological data from several skarn bodies of the SGD is currently being acquired.

  • Lecture (Conference)
    Geomünster 2019, 22.-25.09.2019, Münster, BRD

Permalink: https://www.hzdr.de/publications/Publ-30699
Publ.-Id: 30699


The Waschleithe W-skarn - a distal relative of skarns in the Schwarzenberg district, western Erzgebirge, Germany?

Reinhardt, N.; Burisch, M.; Frenzel, M.; Gutzmer, J.; Meinert, L. D.; Gerdes, A.

The Waschleithe skarn located near Schwarzenberg in eastern Germany hosts sub-economic polymetallic W-Zn-Pb-Cu-Fe mineralisation. Its mineralogy is dominated by prograde clinopyroxene and subordinate garnet. The garnet and pyroxene colours of this skarn as well as low garnet/pyroxene ratios are typical for distal skarn settings. Ore minerals (magnetite, sphalerite, galena, chalcopyrite, pyrite, scheelite) in the prograde skarn do not show a clear association with the weakly developed retrograde overprint consisting mainly of late chlorite and calcite.

  • Poster
    15th Biennial Meeting of the Society for Geology Applied to Mineral Deposits, 28.08.2019, Glasgow, UK

Permalink: https://www.hzdr.de/publications/Publ-30698
Publ.-Id: 30698


Assessing the global availability of by-product metals – The cases of Ga, Ge and In

Frenzel, M.

Recently, considerable concerns have been raised about the supply security of certain high-tech elements produced as by-products. To determine in how far these concerns are justified by the actual availability of these elements, a new method was developed to estimate supply potentials, including statistical uncertainties. This was applied to three relevant examples – Ga, Ge and In – to compare their global availability to current and historic production volumes. The assessment is based on detailed estimates of the amounts extractable from various raw material streams given contemporary market prices and technologies. The results show that the supply potentials of all three elements significantly exceed current primary production. However, the degree to which this is the case varies from element to element. Differences also exist in historic growth trends, with indium showing the fastest growth rate of production relative to supply potential at the time of analysis.

Keywords: By-products; Hi-tech metals; Supply security

  • Lecture (others)
    USGS Eastern Competence Center on Mineral Resources - Seminar, 17.12.2019, Reston, VA, USA

Permalink: https://www.hzdr.de/publications/Publ-30697
Publ.-Id: 30697


Avoiding amorphization during semiconductor nanostructure ion beam irradiation

Hlawacek, G.; Xu, X.; Möller, W.; Engelmann, H.-J.; Klingner, N.; Gharbi, A.; Heinig, K.-H.; Facsko, S.; Borany, J.

Ion beam induced amorphization of semiconductor nanostructures limits the applicability of ion beam processing to semiconductor nanostructures. Here, we present an approach that not only avoids this amorphization but in addition allows to tailor the lateral device dimensions of pillars and fins used in modern GAA and Fin-FET designs. Si nanopillars (diameter: 25–50 nm) have been irradiated by either 50 keV broad beam Si + or 25 keV focused Ne + beam from a helium ion microscope (HIM) at various temperatures using fluences of 2×10 16 cm −2 and higher. While at room temperature strong deformation of the nanopillars has been observed, the pillar shape is preserved above 325 ∘ C. This is attributed to ion beam induced amorphization of Si at low temperatures allowing plastic flow due to the ion hammering effect and surface capillary forces. Plastic deformation is suppressed for irradiation at elevated temperatures. Above 325 ∘ C, as confirmed by diffraction contrast in BF-TEM, the nanopillars remain crystalline, and are continuously thinned radially with increasing fluence down to 10 nm. This is due enhanced forward sputtering through the sidewalls of the pillar, and agrees well with 3D ballistic computer simulations.
Supported by the H-2020 under Grant Agreement No. 688072.

Keywords: HIM; silicon; ion beam mixing; amorphization

  • Lecture (Conference)
    DPG Frühjahrstagung, 15.-20.03.2020, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30696
Publ.-Id: 30696


On the effect of liquid viscosity, density and surface tension on the hydrodynamics of TSL injection systems

Reuter, M. A.; Obiso, D.; Stelter, M.; Kriebitzsch, S.

On the effect of liquid viscosity, density and surface tension on the hydrodynamics of TSL injection systems,
Main features
Top-submerged gas injection
Submerged combustion
Smelting of non-ferrous metals
Example: copper from chalcopyrite (CuFeS2 )
Importance of hydrodynamics:
gas-liquid interface
intensity of mixing
splashing
lance cooling/coating

Keywords: TSL

  • Lecture (Conference)
    EXTRACTION, 26.-29.08.2019, Ottawa, Canada

Permalink: https://www.hzdr.de/publications/Publ-30695
Publ.-Id: 30695


Raw data of liquid saturation, pressure drop and porosity of an inclined rotating fixed-bed reactor with inner tube

Timaeus, R.; Schleicher, E.; Bieberle, A.; Hampel, U.; Schubert, M.

The hydrodynamic raw data of an inclined rotating fixed-bed reactor with different inner tubes are given. The phase distributions of nitrogen and cumene in the cross-section of the reactor filled with porous alumina particles were measured via a capacitance wire-mesh sensor. Besides, the the raw data of the specific pressure drops for the investigated operating points are described. Additionally, the attenuation coefficients of different configurations (different particle and inner tube diameter) are collected, which were measured by gamma-ray computed tomography. This publication contains the raw data of the publication "Hydrodynamic data of an inclined rotating fixed-bed reactor" (10.14278/rodare.203).

Keywords: Hydrodynamic analysis; Wire-mesh sensor; Raw data; Gamma-ray computed tomography

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-02-03
    DOI: 10.14278/rodare.243

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30694
Publ.-Id: 30694


CFD modeling of combustion and heat transfer in the TSL smelter

Reuter, M. A.; Obiso, D.; Kriebitzsch, S.; Stelter, M.

CFD modelling of combustion and heat transfer in the TSL smelter.
The importance of viscous and interfacial forces on the hydrodynamics of the TSL furnace
An experimental and numerical investigation of TSL gas injection in liquid metal

Keywords: CFD modelling; TSL; metal

  • Lecture (Conference)
    EMC19, European Metallurgical Conference, 23.-26.06.2019, Düsseldorf, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30693
Publ.-Id: 30693


Validation of a VOF approach for the Top-Submerged gas injection in liquid metal

Reuter, M. A.; Obiso, D.; Richter, A.; Akashi, M.; Eckert, S.

The main goal of this work is to prove the reliability of the Volume of Fluid (VOF) model for a top-submerged-lance (TSL) gas injection in a liquid metal bath, therefore trying to close the gap between the modelling of common air/water lab setups and real TSL slag-bath furnaces. Suitable validation data were provided by HZDR, where X-ray imaging was applied to picture the multiphase flow in an Argon - Ga77.2In14.4Sn8.4 system [1].

Keywords: Volume of Fluid; op-submerged-lance; metal; X-ray

  • Lecture (Conference)
    17th Multiphase Flow Conference HZDR, 13.-15.11.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30692
Publ.-Id: 30692


Editorial for World of Metallurgy

Reuter, M. A.

The title of a paper we wrote for this journal in 2014 "Copper: A Key Enabler of Resource Efficiency", or to rephrase it in light of the present Circular Economy (CE) paradigm "Copper: A Key Enabler of the Circular Economy", rings as true as ever.

Keywords: Copper; Resource Efficiency; Circular Economy

  • Erzmetall - World of Metallurgy 72(2019)6, 307-308

Permalink: https://www.hzdr.de/publications/Publ-30691
Publ.-Id: 30691


An atomic force microscope integrated with a helium ion microscope for correlative nanocharacterization

Andany, S. H.; Hlawacek, G.; Hummel, S.; Brillard, C.; Kangül, M.; Fantner, G. E.

In this work, the integration of an atomic force microscope (AFM) into a helium ion microscope (HIM) is reported for the first time. The helium ion microscope is a powerful instrument, capable of sub-nanometer resolution imaging and machining nanoscale structures, while the AFM is a well-established versatile tool for multiparametric nanoscale metrology. Combining the two techniques opens the way for unprecedented, in-situ, correlative analysis at the nanoscale. Nanomachining and analysis can be performed without contamination of the sample as well as avoiding environmental changes between processing steps. The practicality of the resulting tool lies in the complementarity of the two techniques as the AFM offers not only true 3D topography maps---something the HIM can only provide in an indirect way---but also allows for nanomechanical property mapping, as well as electrical and magnetic characterisation of the sample after focused ion beam materials modification with the HIM. The experimental setup is described and evaluated through a series of correlative experiments, demonstrating the feasibility of the integration.

Keywords: AFM; HIM; Correlative Microscopy

Related publications

Permalink: https://www.hzdr.de/publications/Publ-30689
Publ.-Id: 30689


The Application Of Subspace Clustering Algorithms In Drill-Core Hyperspectral Domaining

Rafiezadeh Shahi, K.; Khodadadzadeh, M.; Tolosana Delgado, R.; Tusa, L.; Gloaguen, R.

Diamond drilling is used in the mining industry to extract drill-cores for characterising mineral deposits. Traditionally, drill-cores are visually analysed by an on-site geologist, subjected to geochemical analyses, and then, few representative samples subjected to additional high-resolution mineralogical studies. However, the choice in samples is frequently subjective and the mineralogical analyses are highly time-consuming. In order to optimize the choice of samples and accelerate the analyses, drill-cores can be partitioned into domains, and then, laboratory analyses can be carried out on selected domains. Nevertheless, in the mining industry, automatic drill-core domaining still remains a challenge. Recently, hyperspectral imaging has become an important technique for the analysis of drill-cores in a non-invasive and non-destructive manner. Several clustering algorithms of hyper-spectral data are proposed for automatic drill-core domaining. In this paper, we suggest using advanced subspace clustering algorithms (i.e., sparse subspace clustering algorithm, spectral-spatial sparse subspace clustering algorithm). These algorithms work based on the self-representation property of the hyperspectral data. The clustering methods are tested on two drill-core samples which present different mineralogical and structural features. The subspace clustering algorithms are compared with the result of the K-means clustering algorithm. Our experimental results show that subspace clustering algorithms provide accurate drill-core domains and it is shown that including spatial information significantly improves the clustering results.

Keywords: Clustering algorithms; Hyperspectral imaging; Veins; Minerals; Signal processing algorithms; Clustering methods

  • Contribution to proceedings
    2019 10th Workshop on Hyperspectral Imaging and Signal Processing: Evolution in Remote Sensing (WHISPERS), 24.-26.09.2019, Amsterdam, Netherlands

Permalink: https://www.hzdr.de/publications/Publ-30688
Publ.-Id: 30688


A subspace clustering algorithm with spatial regularization for mineral mapping.

Rafiezadeh Shahi, K.; Khodadadzadeh, M.; Tolosana Delgado, R.; Gloaguen, R.

Determination of the mineral compositions of an ore deposit is a vital task in exploration campaigns. HyperSpectral (HS) imaging is an emerging technology that is becoming popular in the mining industry. Specially, analyzing drill core HS data enables geologists to map minerals in mining projects in a fast and non-destructive manner. There are several methods to analyze the acquired drill cores. While traditional approaches such as X-Ray diffraction (XRD) can be subjective and are time consuming, the new machine learning based techniques applied on drill core HS scans have shown promising results. By using machine learning techniques, geologists are able to identify representative areas of drill core samples to apply traditional laboratory analysis.In recent studies, advanced unsupervised learning techniques to cluster HS data have shown great performance. Specially subspace clustering methods (i.e., sparse subspace clustering, low rank representation clustering) obtained more accurate results than the traditional clustering methods (e.g. K-means) for the analysis of this data. This is mainly because of the fact that each pixel may contain several minerals rather than a single phase. Therefore, the drill core HS data can be better represented as a union of low dimensional subspaces.In this work, we propose a new subspace-based method to cluster drill core HS data. It has been shown in the literature that incorporating spatial information will improve the classification results of HS data. Thus, in this work, we suggest including spatial information in the sparse subspace clustering method. In the classical sparse clustering method, only spectral information being used to cluster HS data. While, by adding information from the surrounding of each pixel in the classical sparse formula, the performance of the subspace clustering method will be improved. The method was applied to VNIR-SWIR hyperspectral data. Qualitative validation was provided by scanning electron microscopy based Mineral Liberation Analysis (SEM-MLA) on some areas of interest. Results indicate that the proposed method is promising, compared to existing clustering methods

Keywords: PIXELS; DRILL cores; REGULARIZATION (Mathematics); ORE deposits; SCANNING electron microscopy; MINERAL analysis

  • Open Access Logo Contribution to proceedings
    EGU General Assembly 2019, 07.-12.04.2019, Vienna, Austria
    Geophysical Research Abstracts

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30686
Publ.-Id: 30686


Local vibrational modes of Si vacancy spin qubits in SiC

Shang, Z.; Hashemi, A.; Berencen, Y.; Komsa, H.-P.; Erhart, P.; Zhou, S.; Helm, M.; Krasheninnikov, A.; Astakhov, G.

Silicon carbide is a very promising platform for quantum applications because of the extraordinary spin and optical properties of point defects in this technologically friendly material. These properties are strongly influenced by crystal vibrations, but the exact relationship between them and the behavior of spin qubits is not fully investigated. We uncover the local vibrational modes of the Si vacancy spin qubits in as-grown 4H-SiC. We apply microwave-assisted spectroscopy to isolate the contribution from one particular type of defects, the so-called V2 center, and observe the zero-phonon line together with seven equally separated phonon replicas. Furthermore, we present first-principles calculations of the photoluminescence line shape, which are in excellent agreement with our experimental data. To boost up the calculation accuracy and decrease the computation time, we extract the force constants using machine-learning algorithms. This allows us to identify the dominant modes in the lattice vibrations coupled to an excited electron during optical emission in the Si vacancy. A resonance phonon energy of 36 meV and a Debye-Waller factor of about 6% are obtained. We establish experimentally that the activation energy of the optically induced spin polarization is given by the local vibrational energy. Our findings give insight into the coupling of electronic states to vibrational modes in SiC spin qubits, which is essential to predict their spin, optical, mechanical, and thermal properties. The approach described can be applied to a large variety of spin defects with spectrally overlapped contributions in SiC as well as in other threeand two-dimensional materials.

Keywords: Silicon carbide; Spin qubits; Defects; Vibrational modes; Quantum

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30685
Publ.-Id: 30685


UAS aeromagnetic survey and hyperspectral data for mineral exploration

Madriz Diaz, Y. C.; Jackisch, R.; Zimmermann, R.; Gloaguen, R.

Geophysical methods for mineral exploration require cost- and time-effective ways to acquire high resolution data to supplement field mapping. During the last few years, lightweight magnetometers and hyperspectral imaging (HSI) sensors have been increasingly and independently developed for their use on unmanned aerial systems (UAS). We propose that the combination of hyperspectral images and UAS aeromagnetic surveys can provide a rapid and cost-effective technology to improve the detection of shallow targets and to delineate mineral structures in potentially hazardous terrains where traditional techniques cannot be operated safely. With low altitude flights and tight flight lines, UAS aeromagnetic surveys can help overcome the scale gap between ground and air-borne magnetics and deliver high resolution maps. However, data corrections are required for UAS aeromagnetic data to achieve valid observations and reliable maps. For this study the main magnetic compensations applied to the magnetics were meant to attenuate temporal variations, headings and maneuvering errors. The interpretation of accurate total field maps can be improved with the aid of hyperspectral images. HSI are widely used in geological mapping and mineral exploration (e.g., van der Meer et al., 2012, Jakob et al., 2016). A comprehensive data set including hyperspectral images and handheld spectral measurements of the study area in Siilinjärvi, Finland, was acquired before the UAS aeromagnetic survey was performed. The UAS magnetics was acquired at 40 m height, with a line spacing of 20 m, covering an area of 3.894 ha.
Data processing of the UAS aeromagnetic data revealed the importance of making appropriate corrections for the reliability of the total magnetic intensity (TMI) and derived maps. Results suggest that UAS aeromagnetic data captured the main geological trends of the area by applying pertinent corrections. Aided by the HSI information, the sources of the magnetic anomalies were identified. A high magnetic contrast created by a syenite intrusion located in a glimmeritic carbonatite complex is consistently delineated by the UAS aeromagnetic data. Outcropping areas of the syenite intrusion can also be identified in the available hyperspectral image of Siilinjärvi.

Keywords: Airborne magnetics; magnetometer; hyperspectral; mineral exploration; UAS

  • Open Access Logo Invited lecture (Conferences)
    AGU-SEG Airborne Geophysics Workshop, 11.-13.06.2019, Davie, Florida, United States

Permalink: https://www.hzdr.de/publications/Publ-30684
Publ.-Id: 30684


Carboranyl Derivatives of Rofecoxib with Cytostatic Activity Against Human Melanoma and Colon Cancer Cells

Buzharevski, A.; Paskas, S.; Sárosi, M.-B.; Laube, M.; Lönnecke, P.; Neumann, W.; Murganić, B.; Mijatović, S.; Maksimović-Ivanić, D.; Pietzsch, J.; Hey-Hawkins, E.

Due to the involvement of cyclooxygenase-2 (COX-2) in carcinogenesis, COX-2-selective inhibitors are increasingly studied for their potential cytotoxic properties. Moreover, the incorporation of carboranes in structures of established anti-inflammatory drugs can improve the potency and metabolic stability of the inhibitors. Herein, we report the synthesis of carborane-containing derivatives of rofecoxib that display remarkable cytostatic activity in the micromolar range with excellent selectivity for melanoma and colon cancer cell lines over normal cells. Furthermore, it was shown that the carborane-modified derivatives of rofecoxib displayed different modes of action that was dependent on the cell type.

Keywords: cancer; rofecoxib; carborane; cytostatic drugs; NO-releasing drug

Permalink: https://www.hzdr.de/publications/Publ-30682
Publ.-Id: 30682


UAS aeromagnetic survey for mineral exploration using a fluxgate triaxial magnetometer.

Madriz Diaz, Y. C.; Jackisch, R.; Zimmermann, R.; Gloaguen, R.

Unmanned aerial systems (UASs) for aeromagnetic surveying are currently an advantageous and suitable alternative for a large variety of geophysical applications, such as mineral exploration. UASs equipped with lightweight fluxgate magnetometers can rapidly provide high resolution magnetic data under conditions where traditional surveys cannot operate safely. Furthermore, UAS-borne magnetic acquisition offer a new mapping scale to overcome the gap between terrestrial and manned airborne surveys in a cost-effective way. However, there are several sources of magnetic interferences that compromise the measurements of the Earth's magnetic field, affecting the validity of observations and causing the development of unreliable maps. We address magnetic interference at the initial stages of survey planning and later on during processing. Fluxgate triaxial magnetometers can simultaneously measure the three components of the geomagnetic field but the sensor must be oriented and the heading of the aircraft plays an important role. To characterize the heading error it was essential to perform a compensation test including the possible flight directions before or after survey acquisition. To best adjust to the specific conditions of this case study, a processing tool was designed and programmed to compute suitable corrections and attenuate magnetic interferences. The three main corrections applied to the data included the removal of temporal variations, maneuvering noise and heading errors.
To test the potential of UAS for mineral exploration we selected a former mine in Otanmäki, Finland, as study site. To explore the contribution of low altitude UAS flights to characterize and improve the detection of geological structures, the study area was surveyed at three different heights: 60 m, 40 m and 15 m. For validation purposes, previous aeromagnetic studies in the area were employed, among them a ground magnetic survey. With regards to the efficiency of the UASs for aeromagnetic surveying it is worth mentioning that none of the flights lasted more than 15 minutes. The validation revealed that the total magnetic field maps consistently delineate the iron-ilmenite-magnetite deposits that enclose the test area. As expected, the superior spatial resolution was reached by the 15 m flight survey. Corrections played an important role during data processing. Nevertheless magnetic interference by heading errors was crucial for the reliability of this study. Our results suggest that after applying the pertinent magnetic compensations, UAS aeromagnetic surveys constitute a robust tool for mineral exploration.

Keywords: Unmanned aircraft systems; Magnetic survey; Magnetometer; Airborne surveying

  • Invited lecture (Conferences)
    EGU General Assembly 2019, 08.-12.04.2019, Wien, Austria

Permalink: https://www.hzdr.de/publications/Publ-30680
Publ.-Id: 30680


The sigma-1 receptor: potential role in the modulation of cellular radiation sensitivity

Belter, B.; Deuther-Conrad, W.; Hofheinz, F.; Bachmann, M.; Brust, P.; Pietzsch, J.

Direct interaction of the sigma-1 (σ1) receptor, an endoplasmic reticulum chaperone located in close vicinity to the mitochondrion, with a variety of proteins involved in essential processes regulating proliferation, survival, and death of cells, indicates a role of this protein in tumor biology. Since tumor therapies address precisely these processes to stop the growth of tumor cells, the σ1 receptor could be a suitable modulator of the effectiveness of selected therapies. Recent initial studies have shown not only antiproliferative effects of ligands targeting this protein, but also modulating effects in both chemotherapy and radiotherapy. However, in this regard the influence of functional expression of the σ1 receptor has not yet been fully clarified. The purpose of this pilot experiment was to investigate the role of σ1 receptor on cellular radiosensitivity in an in vitro model. Therefore, clonogenic assays were performed to assess the susceptibility of HEK293 cells, stably transfected with human σ1 receptor, towards irradiation (X-ray) in comparison to non-transfected cells. Moreover, irradiation combined with pharmacological treatment should prove whether agonistic and antagonistic ligand binding to σ1 receptor influences the effectiveness of radiation treatment. The data obtained are not fully conclusive by indicating, on the one hand, an involvement of σ1 receptor in radiation-induced effects along with pharmacological effects independent from the σ1 receptor level, on the other hand, suggesting limitations of the model used herein. Consequently, subsequent work will focus on the investigation of tumor cells with different receptor densities.

Keywords: Chaperone protein; clonogenic assay; endoplasmatic reticulum; intracellular transmembrane receptors; radioresistance; sigma-1 receptor ligands

Downloads:

  • Secondary publication expected from 23.07.2021

Permalink: https://www.hzdr.de/publications/Publ-30679
Publ.-Id: 30679


CFD modelling of the combustion and heat transfer in the Top-Submerged-Lance smelter

Reuter, M.; Obiso, D.; Stelter, M.; Kriebitzsch, S.

The growth outlook for the circular economy in the metallurgical industry has to be built on the deep knowledge of the secondary processes involved in the chain: metal recycling and waste recov-ery play a significant role to successfully close the loop in the metal cycle.
The top-submerged-lance (TSL) furnace technology, primarily designed for metal extraction, is gradually making headway on that perspective because of its technical and economical flexibility. To push the market in that direction, an intense research effort has to be put in the understanding of the fundamentals, from chemical-physical to the engineering aspects.
In the present work, the authors investigate the lance combustion and the heat transfer in a TSL fur-nace. The submerged combustion is a crucial aspect of this technology. The correct design and ap-plication of the lance and the appropriate gas flow conditions must ensure a well-defined value of the partial pressure of oxygen pO2, which drives the smelting reaction process of the mineral con-centrate in the liquid slag bath.
A CFD investigation of the lab-scale TSL furnace, located at TU Bergakademie Freiberg, is per-formed using ANSYS Fluent®: the furnace setup includes the submerged combustive injection into a Cu-slag bath, in absence of the concentrate stream. The analysis provides detailed insights of the fuel combustion and the interaction with the liquid slag. Besides that, the evaluation of the pO2 at the lance tip and the temperature distribution in the bath and in the lance wall represent an added value for the furnace controlling and optimization.

Keywords: TSL smelting; submerged combustion; CFD; pyrometallurgy

  • Poster
    TMS - The Mineral Society Annual Meeting, 10.-14.03.2019, San Antonio, Texas, Texas, USA
  • Contribution to proceedings
    10th European Metallurgical Conference, EMC 2019, 23.-26.06.2019, Düsseldorf, Germany
    Proceedings of the 10th European Metallurgical Conference, EMC 2019, Volume 2(2019), 631-638

Permalink: https://www.hzdr.de/publications/Publ-30678
Publ.-Id: 30678


Line-scan detection system to identify rare earth elements in rocks

Abend, T.; Sharma, S. K.; Fuchs, M.; Beyer, J.; Heitmann, J.; Gloaguen, R.

We develop an integrated sensor system to detect rare earth elements (REE) in natural minerals on-site. The system combines reflectance and photoluminescence (PL) spectroscopy in order to present a noninvasive alternative to conventional time-consuming and costly chemical analysis of drill cores in mineral exploration. The major benefit lies in the rapid gathering of continuous spatial information on the type and abundance of the REEs in drill cores. Additionally the sample material remains unharmed during the whole process. To maximise scan speed and sample throughput, our system operates in continuous line scan mode, with continuous sample flow beneath the detector.

Keywords: Photoluminescence (PL); rare earth elements (REE); line-scan; system integration

  • Lecture (Conference)
    IEEE Sensors 2019, 27.-30.10.2019, Montreal, Canada

Permalink: https://www.hzdr.de/publications/Publ-30677
Publ.-Id: 30677


Dynamic model of a TSL furnace, developed with SimuSageTMsoftware

van Schalkwyk, R. F.; Stelter, M.; Rezende, J.; Reuter, M.; To Baben, M.

A dynamic model was developed in SimuSageTM, of a Top Submerged Lance (TSL) furnace in a lead smelting application. The objectives of the model are to create a tool for process control and optimisation, and to describe the complex metallurgical process which results from increasingly complex feed materials (from primary and secondary sources). Thermodynamic equilibrium models, e.g. created from FactSage, can be used to estimate the distributions of elements between phases. Likewise, laboratory equilibrium measurements for many elements are available. However, a dynamic model is required to address the fact that mass transfer processes are probably controlling smelting processes, especially in the TSL where evaporation of volatile elements should be taken into account. SimuSageTM is a flowsheet software package dedicated to modelling metallurgical processes by the Connected Local Equilibria method. Equilibrium compositions in process nodes are calculated by means of a Gibbs Energy Minimisation (GEM) approach and material can flow between these nodes by streams. In our model, the furnace is divided into a number of zones, e.g. a slag zone, metal zone etc. These zones are represented by nodes in a flowsheet, with mass flow between the nodes. Therefore, the chemistry in the reactor nodes is modelled by the GEM, while the mass transfer is handled by flow between the zones. It is thus possible to model the furnace without solving a large number of rate parameters for individual elements.

Keywords: Kinetics; Technology Elements; Lead; Pyrometallurgy; TSL; SimuSage

  • Contribution to proceedings
    European Metallurgical Conferrence EMC 2019, 23.-26.06.2019, Düsseldorf, Deutschland
    Dynamic model of a TSL furnace, developed with SimuSageTM software, Clausthal-Zellerfeld: GDMB Verlag GmbH, 78-3-940276-88-9, 697-710

Permalink: https://www.hzdr.de/publications/Publ-30676
Publ.-Id: 30676


Ice Complex formation on Bol’shoy Lyakhovsky Island (New Siberian Archipelago, East Siberian Arctic) since about 200 ka

Wetterich, S.; Rudaya, N.; Kuznetsov, V.; Maksimov, F.; Opel, T.; Meyer, H.; Guenther, F.; Bobrov, A.; Raschke, E.; Zimmermann, H.; Strauss, J.; Starikova, A.; Fuchs, M.; Schirrmeister, L.

Late Quaternary landscapes of unglaciated Beringia were largely shaped by ice-wedge polygon tundra. Ice Complex (IC) strata preserve such ancient polygon formations. Here we report on the Yukagir IC from Bol'shoy Lyakhovsky Island in northeastern Siberia and suggest that new radioisotope disequilibria (230Th/U) dates of the Yukagir IC peat confirm its formation during the Marine Oxygen Isotope Stage (MIS) 7a–c interglacial period. The preservation of the ice-rich Yukagir IC proves its resilience to last interglacial and late glacial–Holocene warming. This study compares the Yukagir IC to IC strata of MIS 5, MIS 3, and MIS 2 ages exposed on Bol'shoy Lyakhovsky Island. Besides high intrasedimental ice content and syngenetic ice wedges intersecting silts, sandy silts, the Yukagir IC is characterized by high organic matter (OM) accumulation and low OM decomposition of a distinctive Drepanocladus moss-peat. The Yukagir IC pollen data reveal grass-shrub-moss tundra indicating rather wet summer conditions similar to modern ones. The stable isotope composition of Yukagir IC wedge ice is similar to those of the MIS 5 and MIS 3 ICs pointing to similar atmospheric moisture generation and transport patterns in winter. IC data from glacial and interglacial periods provide insights into permafrost and climate dynamics since about 200 ka.

Keywords: Cryostratigraphy; ice wedges; stable isotopes; pollen; radioisotope disequilibria dating; Beringia

Downloads:

  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-30675
Publ.-Id: 30675


Geochemical Characterization of Tea Leaves (Camellia sinensis) and Soils for Provenance Studies based on Compositional Data Analysis

Pospiech, S.

Provenance studies on tea (Camellia sinensis) are an important tool to reconstruct the origin of tea products. This thesis explores the potential of using solely the ionome (main and trace element concentrations) of tea shoot tips for provenance studies. The emphasize of the thesis is to find element subcompositions which are robust in respect to the various parameters of tea cultivation and production, such as the area, their soils, soil fertilizer and applications of foliar sprays, tea cultivars, plucking/harvesting techniques, manufacturing or leaf grade of the processed tea. For specific discrimination tasks these robust subcompositions can be combined with element subcompositions which are sensitive to one or several tea cultivation and production parameters. The data set consists of ca. 300 leaf and processed tea samples and ca. 130 soil samples. The sampling areas are located in Darjeeling, Assam and Nilgiris in India, in Paraná and São Paulo in Brazil and in Uji and Shizuoka in Japan. All samples, plants and soils, had been treated with four acid digestion methods with HNO3, HCl, HClO4 and HF to achieve a total dissolution. The sample solutions had been analyzed by ICP-MS and ICP-OES. The element concentrations of the leaf and processed tea samples had been corrected for adhering (soil) particles. Hence, all statistical analysis are based on the corrected concentrations values of Al, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sc, Sr, Tl, Y and Zn. The element concentrations are converted into log-ratios by additive, centered or isometric log-ratio transformations prior to statistical analysis to avoid spurious correlations and to enhance the signal-noise ratio for e.g. the trace elements concentrations. The comparison of the geochemical composition of topsoils, subsoils, mature leaves, shoot tips and processed tea samples is used to establish for each element a qualitative index of robustness with respect to cultivation and production parameters. The elements with a high robustness are considered as very suitable for a provenance analysis without further knowledge about the tea samples. The thesis exemplary shows that with already small element subcompositions a good discrimination by geographical origin is possible if the elements are chosen in terms of their suitability for provenance studies of tea including their sensitivity in respect to specific parameters. The geological source rocks of the tea plantations is one of the major factors for discrimination of tea origin.

Keywords: tea; Camellia sinensis; compositional data; soil-plant interaction; plant analysis; plant ionom; provenance; Darjeeling

  • Doctoral thesis
    Georg-August-Universität Göttingen, 2019
    Mentor: Prof. H. Ruppert
    267 Seiten

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30674
Publ.-Id: 30674


TWEAC - Energy-efficient Laser-plasma acceleration beyond the dephasing and depletion limits

Debus, A.; Pausch, R.; Hübl, A.; Steiniger, K.; Widera, R.; Cowan, T.; Schramm, U.; Bussmann, M.

We present Traveling-Wave Electron Acceleration (TWEAC), a novel compact electron accelerator scheme based on laser-plasma acceleration. While laser-plasma accelerators provide multi-GeV electron beams today, the acceleration to higher energies is limited. The sub-luminal group-velocity of plasma waves let electrons outrun the accelerating field.

In order to control the speed of the accelerating plasma cavity, TWEAC utilizes two pulse-front tilted laser pulses whose propagation directions enclose an acute angle. The accelerating cavity is created along their overlap region in the plasma and can move at the vacuum speed of light. The oblique laser geometry enables to constantly cycle different laser beam sections through the interaction region, hence providing quasi-stationary conditions of the wakefield driver. Thus, TWEAC offers constant acceleration without a dephasing electron beam while avoiding usual laser pump depletion within the interaction region. This opens the way for electron energies beyond 10 GeV, possibly towards TeV class electron beams, without the need for multiple laser-accelerator stages.

In this poster we study the energy efficiency of TWEAC compared to LWFA. We find that for low-angle TWEAC setups, it is possible to accelerate high-charge bunches with laser to electron beam energy efficiencies close to 50%, which exceeds energy efficiencies typically attained with LWFA.

Keywords: Laser-produced plasmas; Plasma-based accelerators; Laser-wakefield acceleration; Traveling-wave electron acceleration; TWEAC

  • Poster
    5. Annual MT Meeting, 05.-7.3.2019, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30673
Publ.-Id: 30673


vdar - Discriminant Analysis Incorporating Individual Uncertainties

Pospiech, S.

The qda() function from package 'MASS' is extended to calculate a weighted linear (LDA) and quadratic discriminant analysis (QDA) by changing the group variances and group means based on cell-wise uncertainties. The uncertainties can be derived e.g. through relative errors for each individual measurement (cell), not only row-wise or column-wise uncertainties. The method can be applied compositional data (e.g. portions of substances, concentrations) and non-compositional data.

Keywords: R-Package; QDA; LDA; compositional data; weighted QDA; weighted LDA

Related publications

  • Software in external data repository
    Publication year 2020
    Programming language: R
    System requirements: R (>= 3.6.0)
    License: GPL-3
    Hosted on CRAN: Link to location

Permalink: https://www.hzdr.de/publications/Publ-30671
Publ.-Id: 30671


Scaling EUV and X-ray Thomson Sources to Optical Free-Electron Laser Operation with Traveling-Wave Thomson-Scattering

Debus, A.; Steiniger, K.; Albach, D.; Bussmann, M.; Löser, M.; Pausch, R.; Röser, F.; Schramm, U.; Siebold, M.

Traveling-Wave Thomson-Scattering (TWTS) is a novel Thomson scattering geometry which allows for orders of magnitude higher photon yields than classic head-on Thomson sources. TWTS thereby remains compact and provides narrowband and ultra-short ultraviolet to γ-ray radiation pulses just as classic Thomson sources. Even the realization of optical free-electron lasers is possible with the TWTS geometry since it provides both optical undulators with thousands of periods needed to microbunch the electron beam and a reduction of electron beam quality requirements compared to classic Thomson scattering to a level technically feasible today. TWTS employs a side-scattering geometry depicted in fig. 1. Laser and electron propagation direction of motion enclose the interaction angle ϕ. Tilting the laser pulse front with respect to the wave front by half the interaction angle ensures continuous overlap of electrons and laser pulse over the whole laser pulse width while the laser pulse crosses the electron beam trajectory. In this way the interaction length becomes controllable by the laser pulse width and independent of the laser pulse duration. Utilizing wide, petawatt class laser pulses for TWTS allows to realize thousands of optical undulator periods. The variability of TWTS with respect to the interaction angle can be used to control the radiation wavelength even for electron sources with fixed energy. For a fixed target wavelength on the other hand, the free choice of interaction angle enables control over electron beam quality requirements. Small interaction angle scenarios (ϕ∼10°) typically yield the best trade-off between requirements on electron beam quality, laser power and laser intensity stability. In the talk we will show that TWTS OFELs emitting extreme ultraviolet radiation are realizable today with existing technology for electron accelerators and laser systems. We detail an experimental setup to generate the tilted TWTS laser pulses which aims at compactness and provides focusing of these high-power pulses and compensation of dispersion accompanying pulse-front tilts. The method presented for dispersion compensation is especially relevant when building high yield X- and γ-ray sources in large interaction angle setups of TWTS.

Keywords: optical FEL; traveling-wave; Thomson scattering; pulse-front tilt; out-of-focus interaction; EUV; X-ray

  • Poster
    5. Annual MT Meeting, 05.-7.3.2019, Helmholtz Institut Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30670
Publ.-Id: 30670


Influence of LWFA injection schemes on temporal pulse structure and peak current

Debus, A.; Zarini, O.; Laberge, M.; Couperus Cabadağ, J. P.; Köhler, A.; Kurz, T.; Schöbel, S.; Krämer, J.; Hannasch, A. J.; Zgadzaj, R.; Mewes, H.; Meißner, H.; Bussmann, M.; Downer, M.; Schramm, U.; Irman, A.

Laser wakefield accelerators (LWFA) feature unique electron bunch characteristics, namely micrometer beam size with duration ranging from a few fs to tens of fs. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future table-top x-ray light-sources.
Spectral measurements of broadband transition radiation from LWFA electron bunches passing through a metal foil are especially promising for non-destructively analyzing ultrashort longitudinal bunch characteristics with single-shot capability.

Our broadband, single-shot spectrometer combines the TR spectrum in UV/VIS (200-1000nm), NIR (0.9-1.7μm) and mid-IR (1.6-12μm). A complete characterization and calibration of the spectrometer have been done with regard to wavelengths, relative spectral sensitivities, and absolute photometric sensitivity. Our spectrometer is able to characterize electron bunches with charges as low as 1 pC and resolve time-scales from 0.4 to 40 fs. In addition, complementary data on the transverse bunch profile is provided by simultaneously imaging the CTR in the far- and near-field.

We present recent experimental results of different LWFA injection mechanisms, such as self-truncated ionization-injection and self-injection. By analyzing the transition radiation spectra and reconstructing electron bunch profiles including error analysis, we determine electron bunch profiles and peak currents of the respective injection regimes. In addition to bunch durations and peak currents, we show sub-fs beam micro-structures and systematic experimental scans of the nitrogen doping concentration for ionization-induced injection.

Keywords: LWFA; Laser-wakefield acceleration; peak current; injection scheme; broadband spectrometer; single-shot bunch length measurement; coherent transition radiation; absolute calibration; electron bunch duration; longitudinal profile; absolute calibration; UV; VIS; NIR; MIR

  • Lecture (Conference)
    5. Annual MT Meeting, 05.-7.3.2019, Jena, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30669
Publ.-Id: 30669


Scalable laser-plasma acceleration using Traveling-Wave Electron Acceleration

Debus, A.; Pausch, R.; Hübl, A.; Steiniger, K.; Widera, R.; Cowan, T.; Schramm, U.; Bussmann, M.

While laser-plasma accelerators provide multi-GeV electron beams today, the acceleration to higher energies is limited. The sub-luminal group-velocity of plasma waves let electrons outrun the accelerating field. We present Traveling-Wave Electron Acceleration, a novel compact laser-plasma accelerator scheme which circumvents the LWFA constraints of electron beam dephasing, laser pulse diffraction and depletion.

For controlling the speed of the accelerating plasma cavity, TWEAC utilizes two pulse-front tilted lasers whose propagation directions enclose a configurable angle. The accelerating cavity is created along their overlap region in the plasma and can move at the vacuum speed of light. Such guiding-structure-free, lateral coupling of lasers into the plasma allows the field within this overlap region to be continuously replenished by the successive parts of the laser pulse. Supported by 3D particle-in-cell simulations, we show that this leads to quasi-stationary acceleration conditions for electron bunches along the total acceleration length, such that TWEAC is in principle scalable to arbitrarily long acceleration stages.

We discuss scaling laws and detail experimental design considerations. We find that for low-angle TWEAC setups, it is possible to accelerate nanocoulomb-class bunches with laser to electron beam energy efficiencies close to 50%, thus exceeding energy efficiencies typically attained with LWFA.

Keywords: Laser-produced plasmas; Plasma-based accelerators; Laser-wakefield acceleration; Traveling-wave electron acceleration; TWEAC

  • Lecture (Conference)
    4th European Advanced Accelerator Concepts Workshop (EAAC 2019), 15.-21.9.2019, La Biodola Bay, Isola d'Elba, Italy

Permalink: https://www.hzdr.de/publications/Publ-30668
Publ.-Id: 30668


Modeling the L|PWFA hybrid accelerator using PIConGPU

Debus, A.; Pausch, R.; Steiniger, K.; Hübl, A.; Widera, R.; Kurz, T.; Schöbel, S.; Chang, Y.-Y.; Couperus Cabadağ, J. P.; Köhler, A.; Heinemann, T.; Ding, H.; Döpp, A.; Giljohann, M.; Kononenko, O.; Gaurav, R.; Corde, S.; Hidding, B.; Karsch, S.; Martinez De La Ossa, A.; Irman, A.; Schramm, U.

The hybrid L|PWFA acceleration scheme combines laser- (LWFA) with plasma-wakefield acceleration (PWFA) to provide an ultra-compact, high-brightness electron source. Recently, the acceleration of a witness bunch using this hybrid scheme was demonstrated at HZDR. In this talk, we present recent start-to-end simulations, that accompanied the experimental campaign, and provided fundamental insights into the injection and acceleration process of this novel, compact accelerator. These accompanying simulations were performed using the 3D3V particle-in-cell code PIConGPU. A significantly enhanced agreement between theoretical predictions and experimental measurements could be achieved by resembling the experiment to a very high degree. Modeling the geometry, density distributions, laser modes, and gas dopings as measured in the experiments provided good comparability between experiment and simulation. With that degree of agreement, the wealth of information provided by the in-situ data analysis of PIConGPU provided insight into the plasma dynamics, otherwise inaccessible in experiments. The talk will not only focus on explaining the fundamental physical process behind this hybrid scheme but will further elaborate on the essential details that produce the quasi-monoenergetic witness bunches seen in experiment. Furthermore, we will discuss the associated challenges in maintaining numerical stability and experimental comparability of these long-duration simulations.

Keywords: LWFA; PWFA; laser wakefield acceleration; plasma wakefield acceleration; particle-in-cell simulations; PIC; hybrid L|PWFA; start-to-end simulation

  • Lecture (Conference)
    4th European Advanced Accelerator Concepts Workshop (EAAC 2019), 15.-21.9.2019, La Biodola Bay, Isola d'Elba, Italy

Permalink: https://www.hzdr.de/publications/Publ-30667
Publ.-Id: 30667


A spectral library for Smithsonian rare-earth element phosphate standards using laser-induced fluorescence

Fuchs, M.; Beyer, J.; Lorenz, S.; Sharma, S.; Renno, A.; Heitmann, J.; Gloaguen, R.

Innovation in raw material exploration relies on efficient and non-invasive technologies. Spectroscopy based methods have proven great potential to deliver instant and spatially continuous information on the composition of an investigated surface. Several studies successfully applied laser-induced fluorescence (LIF) for rare-earth element (REE) identification in natural rocks. However, the diagnostic assignment of detected emission lines remains a complex task, because of the highly variable composition of natural rocks. It needs a transfer of the profound knowledge from the field of applied physics and synthetic materials to the natural rock material under investigation. The evaluation of measured spectra and robust assignment of REEs requires reference data, yet usually based on tables of published emission lines, while data of complete reference spectra are not available.
We present a library of reference spectra for all luminescent rare-earth elements using the Smithsonian rare-earth phosphate standards for electron microprobe analysis. We employ laser-induced fluorescence at three commonly used laser wavelengths (325 nm, 442 nm, 532 nm) to acquire reference spectra for REE phosphate minerals in the visible to near-infrared spectral range (350 – 1080 nm). Excitation at all three laser wavelengths yielded spectra with distinct REE-related emission lines for EuPO4, TbPO4, DyPO4 and YbPO4. Lower energy laser excitation at 442 nm showed successful especially for suppressing non-REE-related broadband defect emission. Resulting REE-reference spectra include those from PrPO4, SmPO4 and ErPO4. For NdPO4 and HoPO4 most efficient excitation was achieved with 532 nm. The diagnostic emission lines of GdPO4 lie outside the detection range and none of the three laser wavelengths was appropriate for TmPO4 excitation.
Our results demonstrate the suitability of LIF for REE detection and especially the possibility of selective element excitation. Our reference spectra provide the full spectral information at high resolution (0.13nm) as a basis for an improved evaluation of REE-bearing natural rocks allowing for data analysis of emission line positions, emission line intensity ratios and splitting into emission line sub-levels. The spectral library data support the use of LIF for REE analysis in natural samples and its application in raw material exploration.

Keywords: spectroscopy; laser-induced fluorescence; rare-earth elements

  • Open Access Logo Contribution to proceedings
    European Geoscience Union, 12.04.2019, Vienna, Austria

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30666
Publ.-Id: 30666


Erfassung hydrodynamischer Kenngrößen in großen Prozessbehältern mittels instrumentierter Strömungsfolger

Hampel, U.

This keynote presentation introduces the concept of instrumented flow followers for determination of hydrodynamic parameters in large process vessels. Instrumented flow followers are medium size particles that drift with the flow in a vessel. They actively adjust buoyancy with an electromechanical mechanisms and comprise sensors for temperature, pressure, acceleration and further parameters. Furthermore, novel concepts of data transfer, communication and positioning are being presented.

Keywords: instrumented flow followers; autonomous sensors; process measurement; process engineering

  • Invited lecture (Conferences)
    Campus Mehrphasenreaktoren, 31.01.2020, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30665
Publ.-Id: 30665


Sensorik für die Digitalisierung chemischer Produktionsanlagen

Hampel, U.; Schütze, A.; Rädle, M.; Rück, T.; Krawczyk-Becker, M.; Musch, T.; Maiwald, M.; Fröhlich, H. J.; Zeck, S.

Die chemische Industrie steht derzeit, wie viele andere Industriebereiche, vor den Herausforderungen einer Digitalisierung der Produktion. Sie ist der Schlüssel für die Flexibilisierung von Prozessen und Anlagen, für die Verkürzung von Produkteinführungszeiten sowie für den Zuschnitt der Produktion auf wechselnde Nachfrage und kürzere Produktlebenszyklen. In einer vernetzten Welt werden Informationen über Rohstoffe, Energieträger und Marktbedingungen instantan verfügbar. Sie können damit direkt in Prozessabläufe einfließen und bei der Erstellung von Marktprognosen helfen. Allerdings ergeben sich für die Digitalisierung von Produktionsprozessen in der chemischen Industrie besondere Herausforderungen durch ein oftmals sehr produktspezifisches Anlagendesign sowie die komplexe stoffliche und energetische Verkettung von Grundoperationen.
Die Messtechnik und Sensorik spielt neben der intelligenten Datenverarbeitung eine Schlüsselrolle für die Digitalisierung. Flexiblere Anlagen benötigen Sensorik zur Überwachung des Anlagenzustandes, zur Früherkennung nicht bestimmungsgemäßer Betriebszustände sowie für eine bedarfsgerechte Wartung. Neben der Zustandsüberwachung ist ebenfalls eine verbesserte Sensorik für die Erfassung von stoffbezogenen Daten essenziell, um Einbußen der Produktqualität, etwa durch Verunreinigungen und Spurstoffe, schwankende Eduktzusammensetzungen oder degradierte Katalysatoren frühzeitig zu erkennen. Dafür geeignete spektroskopische Messtechniken sind heute fast immer noch ausschließlich für den Laborbereich verfügbar und müssen auf die Prozessebene übertragen werden.
Für diese Herausforderungen ist die in heutigen Prozessanlagen vorhandene betriebliche Instrumentierung sowohl bezüglich der von ihr erfassten Informationen als auch bezüglich der von ihr bereitgestellten Schnittstellen und Datenformate nicht ausreichend. Eine Weiterentwicklung der Prozessmesstechnik und Prozessanalysentechnik in Richtung der Erfassung sekundärer Prozess-parameter, einer intelligenten multimodalen Sensordatenverarbeitung, standardisierter digitaler Schnittstellen sowie Sensorintelligenz ist unabdingbar. Schließlich ist beim verstärkten Einsatz neuer Sensorik der Sensorrobustheit, der Eigensicherheit im Prozess sowie der einfachen, auch nachträglichen oder temporären, Installierbarkeit von Sensoren in großen Anlagen und rauen Prozessumgebungen Rechnung zu tragen.
Da die Entwicklung neuer und verbesserter Messtechnik und Sensorik grundlegend aus verschiedenen Richtungen gedacht werden muss, haben sich Akteure aus verschiedenen Branchen zusammengetan und dieses Positionspapier erstellt. Es basiert auf einer grundlegenden Analyse des Ist-Stands sowie des Bedarfs der Industrie, die unter anderem auf einem eigens dafür durchgeführten Workshop mit Sensorentwicklern, Anlagenherstellern sowie Anlagenbetreibern am 18. Juni 2019 bei der DECHEMA in Frankfurt a. M. diskutiert wurden. Diese Aktivitäten wurden maßgeblich von der Initiative Wanted Technologies der ProcessNet sowie dem AMA Verband für Sensorik und Messtechnik e.V. initiiert.

Keywords: Messtechnik; Sensorik; Datenverarbeitung; chemische Industrie; Digitalisierung; Industrie 4.0

  • Other report
    Frankfurt am Main: DECHEMA e.V., 2020
    18 Seiten

Permalink: https://www.hzdr.de/publications/Publ-30664
Publ.-Id: 30664


Metallurgy: key enabler of the Circular Economy HSC Sim as a tool for the analysis of large CE SYSTEMS

Reuter, M. A.

The complexity of metal and material mixtures in products
Simulation-based quantification of the resource efficiency of very large - Circular Economy (CE) systems
Various industrial examples for footprinting the CE e.g.
Copper rock to metal – exergy dissipation of the system
PV life cycle linked to energy system: exergy dissipation in the system
Zinc and lead processing systems
Product design for circularity for OEMs (mobile, LED, laptops etc.)
Battery recycling,
Water systems optimization, and
…many more, also developed during my time @ Outotec, also in client solution development, sales, etc.
Challenges?
Too many not yet accepting the above state-of-the-art in the CE discussion, leading to critical and sub-optimal discussions, policy, etc.

Keywords: Circular Economy; resource efficiency; HSC

  • Lecture (others)
    Outotec celebrates 70 years of technology innovation at Pori ORC, 15.-16.10.2019, Pori, Finnland

Permalink: https://www.hzdr.de/publications/Publ-30662
Publ.-Id: 30662


Challenges of the circular economy - A metallurgical perspective

Reuter, M. A.

Circular economy's (CE) noble aims maximize resource efficiency (RE) by, for example, extending product life cycles and using wastes as resources. Modern society's vast and increasing amounts of waste and consumer goods, their complexity, and functional material combinations are challenging the viability of the CE despite various alternative business models promising otherwise. The metallurgical processing of CE-enabling technologies requires a sophisticated and agile metallurgical infrastructure. The challenges of reaching a CE are highlighted in terms of, e.g., thermodynamics, transfer processes, technology platforms, digitalization of the processes of the CE stakeholders, and design for recycling (DfR) based on a product (mineral)-centric approach, highlighting the limitations of material-centric considerations. Integrating product-centric considerations into the water, energy, transport, heavy industry, and other smart grid systems will maximize the RE of future smart sustainable cities, providing the fundamental detail for realizing and innovating the United Nation's Sustainability Development Goals.

Keywords: circular economy; process metallurgy; thermoeconomics; exergy; design for recycling

  • Lecture (others)
    10. Scientific Exchange Day 2019, 07.02.2019, Linz, Österreich

Permalink: https://www.hzdr.de/publications/Publ-30661
Publ.-Id: 30661


Metallurgical Recycling infrastructure of THE circular economy (CE)

Reuter, M. A.

Circular Economy (CE)
Digitalization in the metallurgical industry within the CE system
Metallurgical reactor technology
Design for recycling
Various literature and other detail

Keywords: Circular Economy; HSC; Copper; energy & resource efficiency

  • Lecture (others)
    Atlantic Copper Meeting, 13.12.2019, Madrid, Spanien

Permalink: https://www.hzdr.de/publications/Publ-30660
Publ.-Id: 30660


Steigender Energieaufwand bei der Gewinnung von Metallen – Möglichkeiten und Grenzen des Metallrecyclings

Reuter, M. A.

Ein Abschied ist zugleich ein Neuanfang. Der Ausstieg aus den fossilen Energieträgern ist klimapolitisch überfällig. Das aktive Phase-Out des fossilen Erdöls erfordert zugleich einen Einstieg, ein aktives Phase- In von noch mehr Metallen. Beides, Einstieg und Ausstieg, zusammenzuhalten ist der Schwerpunkt unserer Veranstaltung.

Auch das postfossile Zeitalter braucht Energie. Der Ersatz für die fossilen Energieträger beim Übergang zu regenerativen Energien sind die mehr als ausreichenden Energieströme von der Sonne. Zukünftig primäre Bedeutung wird daher die Elektroenergie haben. Für die Energiewende brauchen wir mehr Metalle: Ob klassische Basismetalle wie Kupfer oder etwa Seltenerdmetalle wie Neodym für die Permanentmagneten moderner Windkraftanlagen. Auch die Mobilitätswende erfordert eine zunehmende Elektrifizierung des motorisierten Straßenverkehrs, sei es direktelektrisch oder mit Wasserstoff / Brennstoffzelle. Mit der Digitalisierung kommt nochmals eine weitere Dimension an Metallbedarf auf uns zu. Metalle sind die Voraussetzung für die Energiewende, die Mobilitätswende und die digitale Transformation. Dazu braucht es alle Metalle im Periodensystem – wir sind im „All Metals Age“ angekommen.

Es geht dabei nicht nur um Lithium, um Kobalt, wozu gelegentlich Meldungen aufgrund von Menschenrechtsverletzungen und Auseinandersetzungen im Kongo bei uns aufschlagen. Oder nur um Seltenerdmetalle, die im Handelskonflikt zwischen den USA und China eine starke Stellung Chinas signalisieren. Wir brauchen ein umfassendes Problemverständnis für die Metalle.

Der klimapolitisch überfällige Übergang ist somit, recht betrachtet, einer vom Zugriff auf einen Bodenschatz zu einem anderen. Der Unterschied in den Eigenschaften dieser beiden Typen von Bodenschätzen wird die zukünftige Geschichte der Menschheit prägen, sowohl die wirtschaftliche als auch die politische. Im Gegensatz zum fossilen Erdöl können wir aus der Nutzung von Metallen nicht aussteigen.

Keywords: fossiles Erdöl; Metalle; Elektroenergie; Metalle; Kupfer; Seltenerdmetalle

  • Invited lecture (Conferences)
    Kobalt, Kupfer, Lithium & Co.: Phase-Out von Erdöl und Phase-In von Metallen, 21.-22.11.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30659
Publ.-Id: 30659


Combined utilization of strategic minerals and construction material from tailings – chances and risks from technological, environmental and economic viewpoint

Dirlich, S.; Łuszak, R.

The presentation deals with the results generated in the frame of the German-Polish research project NOMECOR. The technical feasibility of the combined utilization of valueable elements and mineral compartments of tailing material from the flotation pond Zelazny Most could be proven. The suggested process steps could, however, not be implemented due to economic constraints. The project consortium nevertheless managed to suggest an implementation of the novel processing technologies in a lighter, more simple type.

Keywords: tailings material; metal recovery; construction material; combined utilization; hydrometallurgy; bioleaching

  • Lecture (others)
    STAIR-II Final Conference, 25.-26.09.2019, Warsawa, Polska

Permalink: https://www.hzdr.de/publications/Publ-30658
Publ.-Id: 30658


Pilot Plant for Metal Recovery from Flotation Tailings

Aubel, T.; Thürigen, F.; Kermer, R.; Fischer, H.; Janneck, E.; Dirlich, S.; Chmielarz, A.; Mayer, R.

Processing residues and waste rock are prominent features of mining activities. Especially flota-tion tailings lead to huge land consumption and are a potential source of environmental hazards. In addition, their geotechnical handling is very challenging. On the other hand, the tailings often comprise remains of valuable metals, which more and more came into the focus of scientific investigations and technology developments due to decreasing metal concentrations in the raw ores. G.E.O.S. engaged in the metal recovery from tailings in the frame of several projects with different partners. The scientific approach in these projects concentrated on combination of metal recovery with the removal of contaminants. In the ideal scenario the residues from these approaches can be utilized for underground backfilling or dump construction. So these projects can be regarded as a holistic approach for remediation. Based on laboratory scale results a pilot plant for metal recovery from flotation tailings was developed which comprises several mod-ules.
The first project concentrated on bioleaching of flotation tailings material from an old Freiberg Pb-Zn-ore processing facility (closed in 1968) by an airlift reactor (100 L). As a result, up to 90 % In and almost 100 % Zn were leached from the material which showed initial concentra-tions of 14 ppm In and 10,000 ppm Zn. In another project together with Polish partners an am-moniac leaching process for processing of carbonatic tailings material from Cu concentrate flota-tion was developed. By leaching untreated homogenized tailings material a Cu recovery of 45 % was achieved. After pre-concentration of the material through re-grinding and flotation the re-covery could even be increased to 85 – 90 %.
Motivated by these results a pilot plant was designed consisting of three modules: a) leaching module, b) metal recovery module and c) environmental module. The leaching module compris-es a 1.5 m³ airlift reactor, one decanter centrifuge for effective solid/liquid separation and sever-al stirring and storage tanks needed for continuous process operation and for washing the leach-ing residue. In the metal recovery module (feed 5-10 L/h) are integrated as main processing stages: solvent extraction, absorber columns (activated carbon, IX resin) and one electrolysis cell. Iron can be precipitated as schwertmannite or ferrihydrite (biological/chemical oxidation). The environmental module is designed as classical precipitation, flocculation and sedimentation unit for treatment of remaining liquids from the metal recovery module to meet the discharge parameters. The pilot plant is currently under construction. The commissioning is planned for May 2019.

Keywords: tailings; tailings material; metal recovery; pilot plant; environmental protection

  • Lecture (Conference)
    IMWA2019: Mine Water: Technological and Ecological Challenges, 15.-19.07.2019, Perm, Russland

Permalink: https://www.hzdr.de/publications/Publ-30657
Publ.-Id: 30657


Main technology trends in processing – Data integration of LCA, materials modelling, process flowsheets

Reuter, M. A.

The harmony and complexity of metal and material mixtures: Their value
Simulation-based quantification of the resource efficiency of very large - Circular Economy (CE) systems
Various industrial examples for understanding very large CE systems:
A policy brief informing society: Lead key enabler of the circular economy
Car recycling: Design for recycling SEAT
PV resource life cycle linked to energy system: Exergy dissipation in large systems
Various EU & EIT Rawmaterials projects as well as BMBF and B2B:
PreMa: Low CO2 production of FeMn, incl. solar heat
GUCCIS: Product design for circularity
B2B: Fairphone
Circular by Design: BMBF Germany
Submitted project: SiSal Pilot
INFACT: EU project

Keywords: Circular Economy; Car recycling; resource systems

  • Invited lecture (Conferences)
    Innovation, new technology trends and Skills for Raw Materials“New technology trends in exploration, mining and processing, Skills for Raw Materials, Horizon 2020 Raw Materials Information and Brokerage Event”, 18.-22.11.2019, Brüssel, Belgien

Permalink: https://www.hzdr.de/publications/Publ-30656
Publ.-Id: 30656


Laser-driven strong shocks with infrared lasers at intensity of 1016 W/cm2

Antonelli, L.; Trela, J.; Barbato, F.; Boutoux, G.; Nicolaï, P.; Batani, D.; Tikhonchuk, V.; Mancelli, D.; Tentori, A.; Atzeni, S.; Schiavi, A.; Baffigi, F.; Cristoforetti, G.; Viciani, S.; Gizzi, L. A.; Smid, M.; Renner, O.; Dostal, J.; Dudzak, R.; Juha, L.; Krus, M.

We present the results of an experiment on laser-driven shock waves performed at the Prague Asterix Laser system (PALS), where the fundamental frequency of the laser (1315 nm) is used to launch a strong shock in planar geometry. The experiment aims to characterize both shock waves and hot electrons generated at intensities of ’ 1016 W=cm2 . It is shown that, in these interaction conditions, hydrodynamics is strongly impacted by noncollisional mechanisms, and the role of the hot electrons, generated by parametric instabilities, is essential in determining shock dynamics.

Permalink: https://www.hzdr.de/publications/Publ-30655
Publ.-Id: 30655


Smart Kd-concept as efficient approach to improve geochemistry in reactive transport modelling

Stockmann, M.; Noseck, U.; Britz, S.; Flügge, J.; Becker, D.-A.; Brendler, V.

Understanding and appropriate modelling of geochemical processes is essential for predicting the contaminant transport in groundwater systems and, therefore, important in many application areas such as groundwater prediction, environmental remediation, or disposal of hazardous waste. One important natural retardation process is sorption on mineral surfaces of rocks or sediments. In order to treat the radionuclide sorption processes in natural systems more realistically, we developed the smart Kd-concept (www.smartkd-concept.de) to predict variations in sorption as consequence of changing physicochemical conditions which have to be considered in long-term safety assessments for radioactive waste repositories (Noseck et al., 2012, 2018; Stockmann et al., 2017).
In this presentation, we describe the fundamental strategy of the smart Kd-concept to calculate distribution coefficients (referred to as smart Kd-values) for a wide range of important environmental parameters. This mechanistic approach mainly based on surface complexation models and is combined with the “Component Additivity” approach to describe a natural system close to reality. This bottom-up approach based on the principle that the sorption of contaminants can be determined based on the competitive mineral-specific sorption of dissolved species on surfaces. Therefore, a full thermodynamic description of both the aqueous, solid and interface reactions is required. Using the geochemical speciation code PHREEQC (Parkhurst and Appelo, 2013), multidimensional smart Kd-matrices are computed as a function of varying (or uncertain) input parameters such as pH, ionic strength, concentration of competing cations and complexing ligands, e.g. calcium (Ca) and dissolved inorganic carbon (DIC). On the one hand, sensitivity and uncertainty statements for the distribution coefficients can be derived. On the other hand, smart Kd-matrices can be used in reactive transport codes (see abstract Noseck et al. 2020). This strategy has various benefits: (1) rapid computation of Kd-values for large numbers of environmental parameter combinations; (2) variable geochemistry is taken into account more realistically; (3) efficiency in computing time is ensured, and (4) uncertainty and sensitivity analysis are accessible. It is worth mentioning that the basic methodology described here can be transferred to any other transport code relying on conventional distribution coefficients as well as to any other complex natural site.
Results of a case study (serving as a comprehensive proof-of-concept) for a typical sedimentary rock system in Northern Germany as natural geological barrier for a deep geological repository site showed that the smart Kd approach goes considerably beyond the conventional concepts. We can illustrate that constant Kd values (see for U(VI) in Fig. 1, right, green line) previously used in transport simulations are a crude assumption, as in reality they rather range over several orders of magnitude. Moreover, with the results from the sensitivity analyses (SA) (Becker, 2016), the most important input parameters influencing the radionuclide retardation can be identified (key parameters of the model). The calculated sensitivity indices allowed us to assess the most and less sensitive parameters. From the visualized smart Kd matrix for U(VI) (Fig. 1, left) it is obvious that mainly the pH value and the DIC influences the sorption of U(VI) under the given conditions. SA is a useful means for reducing the complexity of a geochemical model by focusing on the most important input parameters.

  • Lecture (others)
    International Workshop on "How to integrate geochemistry at affordable costs into reactive transport for large-scale systems", 05.-07.02.2020, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-30654
Publ.-Id: 30654


Metallurgy as the key enabler in Circular Economy, and bottlenecks by REACH and other policies on metal banning

Reuter, M. A.

The complexity of metal and material mixtures in products
Simulation-based quantification of the resource efficiency of very large - Circular Economy (CE) systems
Various industrial examples for understanding very large CE systems e.g.
A policy brief informing society: Lead key enabler of the circular economy
PV life cycle linked to energy system: exergy dissipation in the system
Car recycling – design for recycling
Challenges?

Keywords: resource efficiency; Circular Economy; metallurgy; Socrates; recycling

  • Invited lecture (Conferences)
    CICERONE - Funding the Circular Economy, 19.-20.11.2019, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30651
Publ.-Id: 30651


Spin dynamics in strongly-correlated spin systems: physics and methodology

Zvyagin, S.

für diesen Vortrag hat keine inhaltliche Kurzfassung vorgelegen

  • Invited lecture (Conferences)
    Heinz Maier-Leibnitz Zentrum User Meeting, 10.-11.12.2019, Garching, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30650
Publ.-Id: 30650


Si nanopillar deformation by heavy polyatomic ion impacts

Bischoff, L.; Pilz, W.; Engelmann, H.-J.; Xu, X.; Möller, W.; Heinig, K.-H.; Ghaderzadeh, S.; Hlawacek, G.; Gharbi, A.; Tiron, R.

Si nanopillars for the fabrication of vertical nanowire gate-all-around Single Electron Transistors [1], have been irradiated with Si++, Pb+, Pb++, Au +, Au++, Au2 +, and Au3 + ions accelerated by 30 kV. A FIB of mass separated ions, extracted from a Liquid Metal Alloy Ion Source [2], has been scanned over regular arrays of Si nanopillars of different diameters and pillar distances. The irradiations have been performed at RT and 400∘C. Different morphological changes of the pillars like thinning, height reduction, tilting etc. have been observed which can be attributed to ion erosion (sputtering), impact-induced viscous flow or even transient nanosecond-scale melting [3]. The pillars were imaged by AFM, SEM, TEM and HIM. 3D Monte Carlo
simulations [4] of ion and recoil trajectories based on the Binary Collision Approximation and Molecular Dynamics calculations have been carried out in order to discriminate the dominating processes.
[1] EU project Ions4SET, Horizon 2020 grant No. 688072
[2] L.Bischoff, et al., Appl. Phys. Rev. 3 (2016) 021101
[3] C. Anders, K.-H. Heinig, H. Urbassek, Phys. Rev. B87 (2013) 245434
[4] W. Möller,NIM B322 (2014) 23

Keywords: Si nanopillars; Single Electron Transistors; FIB; Liquid Metal Alloy Ion Source [

  • Lecture (Conference)
    DPG conference, 15.-20.03.2020, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-30649
Publ.-Id: 30649


Metall-Kreislaufwirtschaft - Potentiale und Grenzen // Smartphone: IconographiC example for digital transformation

Reuter, M. A.

The complexity of metal and material mixtures in products
Simulation-based quantification of the resource efficiency of very large Circular Economy (CE) systems
Various industrial examples for understanding very large CE systems e.g.
A policy brief informing society: Lead key enabler of the circular economy
PV life cycle linked to energy system: exergy dissipation in the system
Car recycling – design for recycling
Many more, also developed during my time @ Outotec, also in client solution development, sales, etc.:
Copper rock to metal – exergy dissipation of the system
Battery recycling
Zinc and lead processing systems
Product design for circularity for OEMs (mobile, LED, laptops etc.)
Water systems optimization e.g. on concentrator plants
Challenges?
Background information

Keywords: Circular Economy; SOCRATES; Recycling; footprint of minor metals; car recycling; emobility

  • Invited lecture (Conferences)
    Metalle – Voraussetzung der digitalen Transformation, 08.-09.11.2019, Tutzingen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30645
Publ.-Id: 30645


Smelters and refineries strategies to mitigate impact of minor metal increase in feed

Reuter, M. A.

The importance of metals in society /
The fundamental role of metals in a circular society /
Metallurgical infrastructure criticality in a circular society – recovering the minor elements /
Our actions as industry?

Keywords: circular society; emobility; recycling; circular economy; process metallurgy

  • Invited lecture (Conferences)
    Third Minor Metal Symposium: Multi Metal Management and Sustainable Processing of Complex Sulfide Materials, 19.-21.10.2019, Lissabon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-30644
Publ.-Id: 30644


The eco-footprint of raw materials. Current limits.

Reuter, M. A.

The complexity of metal and material mixtures in products
Simulation-based quantification of the resource efficiency of very large - Circular Economy (CE) systems
Applying the tools of process metallurgy to quantify CAPEX and OPEX of CE system
Various industrial examples for footprinting the CE e.g.
PV life cycle linked to energy system: exergy dissipation in the system
Various other examples among many:
Copper rock to metal – exergy dissipation of the system (industry)
Product design for circularity for OEMs (mobile, LED, laptops etc.)
Water systems optimization (industry)
Zinc and lead processing systems (industry)
Challenges?

Keywords: ecological footprint; circular SOCIETY; emobility; resource efficiency; Circular Economy

  • Invited lecture (Conferences)
    4th Expert Forum on Sustainable Materials for Future Mobility/Electrification and Lightweight Design, 07.-09.10.2019, Nizza, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-30643
Publ.-Id: 30643


Testing cave ice deposits as archives of past atmospheric ¹⁰Be deposition

Kern, Z.; Ruszkiczay-Rüdiger, Z.; Perșoiu, A.; Merchel, S.; Gärtner, A.; Rugel, G.; Lachner, J.; Steier, P.

INTRODUCTION
Depositional records of atmospheric cosmogenic radionuclides play an important role in the reconstruction of fluctuations of the solar activity over millennial timescales (Beer, 2000). However, sedimentary ¹⁰Be records reflect partly the local depositional conditions such as precipitation patterns. Therefore, a cross-check of ¹⁰Be records obtained from different geographical locations with distinct precipitation regimes is important. To meet this demand, as polar ice cores proved to be invaluable archives of atmospheric ¹⁰Be deposition, increasing scientific interest turned to ¹⁰Be records of mid-latitude glaciers (Inceoglu et al., 2016). Conversely, while presently surface glaciation is mostly absent at mid-latitudes, subterranean glaciation (i.e., ice caves) is a common feature, even on low-elevation karstic areas. Once it forms, cave ice can preserve the deposition record of ¹⁰Be similarly to surface ice bodies, so it has the potential to be a useful complementary archive providing comparable records of past atmospheric ¹⁰Be deposition.
We present here a record of atmospheric ¹⁰Be locked in the millennial old ice deposits from Scărișoara Ice Cave, Romania. To our knowledge, our project is the very first in measuring atmospherically-produced ¹⁰Be in cave ice deposits.

SAMPLING STRATEGY and METHODOLOGY
A ~6 m long, 10 cm diameter ice core was extracted from the ice block of the Scărișoara Ice Cave (Apuseni Mts, Romania, Fig. 1) in 2015 in segments each between 5 and 30 cm long. The outer surface of the core was immediately cleaned in the field using sterilized plastic knives, subsequently wrapped in clean plastic bags and stored at temperatures between -20°C and -40°C prior to analysis. The ice cores were transported frozen to the Cosmogenic Nuclide Sample Preparation Laboratory in Budapest (http://www.geochem.hu/kozmogen/Lab_en.html) in 2018. Nine ice core sections, each weighing ~300 g, were selected for a pilot study. Radiochemical sample processing including addition of defined amounts of stable ⁹Be followed the methodology of Zipf et al. (2016) and was carried out at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Accelerator Mass Spectrometry (AMS) measurements of the ¹⁰Be/⁹Be ratio of the samples were performed also there. Data were normalized to SMD-Be-12 (Akhmadaliev et al., 2013), which is traceable to the NIST4325 standard.
The processing and measurement of these pilot samples was successful: all samples provided measurable and distinct ¹⁰Be/⁹Be ratios. The performance of five out of nine samples was excellent. Although the chemical yield of four samples was lower than expected (except for one sample) uncertainties remained below 5% (range between 2.3 and 5.1%; mean 3.5%).
An additional set of nine samples was selected for analysis in 2019, with the aim of using a slightly modified radiochemistry method to achieve increased and more stable chemical yield for all samples and to provide more details of the variations of atmospheric ¹⁰Be concentrations along the core. This sample set was radiochemically processed by the same people but at the University of Vienna. These samples were investigated by AMS out at the Vienna Environmental Research Accelerator (Steier et al., 2019). The data were again normalized to the secondary standard SMD-Be-12 to allow direct comparability between the two datasets.
The age of the ice core was determined by transferring the depth-age model of the Perșoiu et al. (2017) record, based on 26 ¹⁴C ages, to the present core. Four ¹⁴C measurements of this new core were used as anchor points for the older chronology. The chronological framework has been assigned to the cave ice derived ¹⁰Be results following the synchronization of the depth-scales of the two cores.

RESULTS and DISCUSSION
Due to successfully-improved chemical preparation, the chemical yield could be increased for all samples, hence, leading to smaller overall uncertainties of the ¹⁰Be data of the second sample set (1.9-3.6% (mean 2.7%). The measured ¹⁰Be/⁹Be ratio of the samples and processing blanks are in the same range for both sample sets (Fig. 2).
The ¹⁰Be concentrations range from (0.52±0.02)×10⁴ at/gice to (4.17±0.16)×10⁴ at/gice in the combined dataset (Fig. 2). This concentration range is comparable to those found in polar ice cores (Berggren et al., 2009, von Albedyll et al., 2017) but slightly lower than in the high-elevation Asian mountains (Inceoglu et al., 2016).
Based on the ¹⁴C measurements, the maximum age of the 6 m core is estimated to be 900 years. The ¹⁰Be concentrations of the studied section covers the upper 1.5 m of the ice core and corresponds to the ~1630 AD to ~1850 AD time interval.
The main trend in the cave ice derived ¹⁰Be concentration mirrors quite well the ¹⁰Be concentration profiles obtained from polar ice cores for the same period (von Albedyll et al., 2017, Berggren et al., 2009). The ¹⁰Be concentration peak (3.96±0.20)×10⁴ at/gice, Fig. 2) in the Dresden data found at the depth range of ~97-103 cm below surface corresponding to the late 1680s AD might reflect the Maunder Minimum documented as peak concentration both in the Akademii Nauk ice core (von Albedyll et al., 2017) and the NGRIP ice core (Berggren et al., 2009).
The data looks very promising, but further data evaluation and interpretation is still needed.

ACKNOWLEDGEMENTS
This research was funded by the National Research, Development and Innovation Office of Hungary grant OTKA FK 124807 (ZsRR), and UEFISCDI Romania through grant number PN-III-P1-1.1-TE-2016-2210 (AP). Parts of this research were carried out at the Ion Beam Centre (IBC) at the Helmholtz-Zentrum Dresden-Rossendorf e. V., a member of the Helmholtz Association. AMS measurements at VERA facility (University of Vienna) were supported by the Radiate Transnational Access 19001687-ST. This is contribution No.71 of the 2ka Palæoclimatology Research Group.

References
von Albedyll, L., Opel, T., Fritzsche, D., Merchel, S., Laepple, T., Rugel, G. 2017. ¹⁰Be in the Akademii Nauk ice core – first results for CE 1590–1950 and implications for future chronology validation. Journal of Glaciology 63, 514-522.
Akhmadaliev et al. 2013. The new 6 MV AMS-facility DREAMS at Dresden. Nucl. Instr. and Meth. Phys. Res. B 294, 5–10.
Beer, J. 2000. Long-term indirect indices of solar variability. Space Science Reviews 94 (1-2), 53-66.
Berggren et al., 2009. A 600-year annual ¹⁰Be record from the NGRIP ice core, Greenland. Geophysical Research Letters 36 (11), L11801.
Inceoglu, F., Knudsen, M. F., Olsen, J., Karoff, C., Herren, P. A., Schwikowski, M., Aldahan, A., Possnert, G. 2016. A continuous ice-core ¹⁰Be record from Mongolian mid-latitudes: influences of solar variability and local climate. Earth and Planetary Science Letters 437, 47-56.
Perşoiu, A., Onac, B.P., Wynn, J.G., Blaauw, M., Ionita, M., Hansson, M. 2017. Holocene winter climate variability in Central and Eastern Europe. Scientific Reports 7, 1196.
Steier, P., Martschini, M., Buchriegler, J., Feige, J., Lachner, J., Merchel, S., Michlmayr, L., Priller, A., Rugel, G., Schmidt, E., Wallner, A., Wild, E.M., Golser, R. 2019. Comparison of methods for the detection of 10Be with AMS and a new approach based on a silicon nitride foil stack. International Journal of Mass Spectrometry, 444, 116175.
Zipf, L., Merchel, S., Bohleber, P., Rugel, G., Scharf, A. 2016. Exploring ice core drilling chips from a cold Alpine glacier for cosmogenic radionuclide (¹⁰Be) analysis. Results in Physics 6, 78-49.

Keywords: AMS; ice; cave; dating; cosmogenic

  • Aragonit Journal 25(2020)1, 45-47

Permalink: https://www.hzdr.de/publications/Publ-30642
Publ.-Id: 30642


Boron Liquid Metal Alloy Ion Sources for Special FIB Applications

Bischoff, L.; Klingner, N.; Mazarov, P.; Pilz, W.; Meyer, F.

Focused Ion Beam (FIB) processing has been established as a well-suited and promising technique in R&D in nearly all fields of nanotechnology for patterning and prototyping on the µm-scale and below. Liquid Metal Alloy Ion Sources (LMAIS) represent an alternative to expand the FIB application fields beside all other source concepts. The need of light elements like B was investigated using various alloys. A promising solution was found in a Co31Nd64B5 based LMAIS which should be introduced in more detail. Beside Co ions as a ferromagnetic element and the rare earth element Nd especially B is interesting for special FIB applications with a best obtained resolution of about 30 nm so far.

Keywords: Boron Liquid Metal Alloy Ion Source; Focused Ion Beam

  • Open Access Logo Journal of Vacuum Science & Technology B 38(2020)4, 042801-1-042801-5
    DOI: 10.1116/6.0000073

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30640
Publ.-Id: 30640


Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air

Unger, S.; Krepper, E.; Beyer, M.; Hampel, U.

This is the data set for the corresponding journal publication " Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air".

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-01-24
    DOI: 10.14278/rodare.235
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30638
Publ.-Id: 30638


Pages: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] [64] [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] [76] [77] [78] [79] [80] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] [96] [97] [98] [99] [100] [101] [102] [103] [104] [105] [106] [107] [108] [109] [110] [111] [112] [113] [114] [115] [116] [117] [118] [119] [120] [121] [122] [123] [124] [125] [126] [127] [128] [129] [130] [131] [132] [133] [134] [135] [136] [137] [138] [139] [140] [141] [142] [143] [144] [145] [146] [147] [148] [149] [150] [151] [152] [153] [154] [155] [156] [157] [158] [159] [160] [161] [162] [163] [164] [165] [166] [167] [168] [169] [170] [171] [172] [173] [174] [175] [176] [177] [178] [179] [180] [181] [182] [183] [184] [185] [186] [187] [188] [189] [190] [191] [192] [193] [194] [195] [196] [197] [198] [199] [200] [201] [202] [203] [204] [205] [206] [207] [208] [209] [210] [211] [212] [213] [214] [215] [216] [217] [218] [219] [220] [221] [222] [223] [224] [225] [226] [227] [228] [229] [230] [231] [232] [233] [234] [235] [236] [237] [238] [239] [240] [241] [242] [243] [244] [245] [246] [247] [248] [249] [250] [251] [252] [253] [254] [255] [256] [257] [258] [259] [260] [261] [262] [263] [264] [265] [266] [267] [268] [269] [270] [271] [272] [273] [274] [275] [276] [277] [278] [279] [280] [281] [282] [283] [284]