Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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34122 Publications

Magnetocaloric effect and spin-strain coupling in the spin-nematic state of LiCuVO4

Gen, M.; Nomura, T.; Gorbunov, D.; Yasin, S.; Cong, P. T.; Dong, C.; Kohama, Y.; Green, E. L.; Law, J. M.; Henriques, M. S.; Wosnitza, J.; Zvyagin, A. A.; Cheranovskii, V. O.; Kremer, R. K.; Zherlitsyn, S.

We report on the magnetocaloric effect and ultrasound studies of the frustrated quasi-one-dimensional spin-1/2 compound LiCuVO4, evidencing a spin-nematic state. The magnetic Grüneisen parameter diverges at the transition to the spin-nematic phase, μ0Hc3 ≈ 40 T, showing quantum criticality accompanied by entropy accumulation. The observed high-field anomalies in the acoustic properties clearly evidence a strong involvement of the lattice in the spin dynamics. The theoretical approach, based on exchange-striction coupling with dipolar and quadrupolar contributions, suggests that the spin-dipole-strain and quadrupole-strain interactions govern the
spin-nematicity in LiCuVO4.

Permalink: https://www.hzdr.de/publications/Publ-29892
Publ.-Id: 29892


Fermi surface of LaFe2P2—a detailed density functional study

Förster, T.; Kraft, I.; Sheikin, I.; Bianchi, A. D.; Wosnitza, J.; Rosner, H.

Angular-dependent de Haas-van Alphen measurements allow the mapping of Fermi surfaces in great detail with high accuracy. Density functional electronic-structure calculations can be carried out with high precision, but depend crucially on the used structural information and the applied calculational approximations. We report in a detailed study the sensitivity of the calculated electronic band structure of the 122 compound LaFe2P2 on (i) the exact P position in the unit cell, parametrized by a so-called z parameter, and on (ii) the treatment of the La 4f states. Depending on the chosen exchange and correlation-potential approximation, the calculated z parameter varies slightly and corresponding small but distinctive differences in the calculated band structure and Fermi-surface topology appear. Similarly, topology changes appear when the energy of the mostly unoccupied La 4f states is corrected regarding their experimentally observed position. The calculated results are compared to experimental de Haas-van Alphen data. Our findings show a high sensitivity of the calculated band structure on the pnictide z position and the need for an accurate experimental determination of this parameter at low temperatures, and a particular need for a sophisticated treatment of the La 4f states. Thus, this is not only crucial for the special case of LaFe2P2 studied here, but of importance for the precise determination of the band structure of related 122 materials and La containing compounds in general.

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  • Secondary publication expected from 18.10.2020

Permalink: https://www.hzdr.de/publications/Publ-29891
Publ.-Id: 29891


The Helmholtz Innovation Lab for ultra-short time annealing

Rebohle, L.; Begeza, V.; Garcia Munoz, A.; Schumann, T.; Neubert, M.; Xie, Y.; Prucnal, S.; Grenzer, J.; Hübner, R.; Zhou, S.; Skorupa, W.

Der Vortrag stellt das Helmholtz Innovation Lab für Ultrakurzzeitausheilung vor. Im zweiten Teil werden experimentelle Ergebnisse bei der Kristallisation von dünnen amorphen Halbleiterschichten (Si, Ge, NiGe) mittels magnetron sputtering und Blitzlampenausheilung diskutiert.

Keywords: Helmholtz Innovation Lab; flash lamp annealung; ultra-short time annealing; magnetron sputtering; nickel germanide

  • Lecture (Conference)
    43. Nutzertreffen Heißprozesse und RTP, 23.10.2019, Stuttgart, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29890
Publ.-Id: 29890


Crystallization of thin Si, Ge and NiGe films on SiO2 by flash lamp annealing

Rebohle, L.; Begeza, V.; Garcia Munoz, A.; Schumann, T.; Neubert, M.; Xie, Y.; Prucnal, S.; Grenzer, J.; Hübner, R.; Zhou, S.; Skorupa, W.

There is a broad palette of applications for thin Si and Ge films ranging from photovoltaics over various microelectronic devices to sensor applications. Both amorphous and polycrystalline thin films are of interest for thin film photovoltaics, and thin film poly-Si transistors are the heart piece for driving LCDs and OLEDs [1]. In addition, the ability to deposit SiO2 and Si layers in an alternating order and to process them allows to extend the device density without further downscaling [2]. Amorphous thin film deposition methods are the most cost-effective ones, the subsequent crystallization is the most critical process step with regard to microstructure, defect density, and electrical properties.

Potentially, flash lamp annealing (FLA) is a very suitable method due to the short process time, the qualification for temperature-sensible substrates and the possibility to take advantage of non-equilibrium crystallization modes [3]. In this work thin amorphous Si and Ge films have been deposited on SiO2 by DC-magnetron sputtering and crystallized by in-situ FLA in a new FLA sputter tool recently installed by the Rovak GmbH at HZDR (Fig. 1). The in-situ-processing suppresses the influence of surface oxidation effects after deposition prior to FLA. In order to investigate the crystallization behaviour, the thin films have been characterized by Raman spectroscopy, X-ray diffraction, ellipsometry, current-voltage and Hall effect measurements. Based on these results and in combination with temperature simulations, a model for the crystallization of thin amorphous Si and Ge films is derived.

Keywords: flah lamp annealing; magnetron sputtering, nickel germanide, crystallization

  • Lecture (Conference)
    Gettering and Defect Engineering in Semiconductor Technology 2019, 22.-27.09.2019, Zeuthen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29888
Publ.-Id: 29888


Hydrodynamic experimental benchmark data of bubbly two-phase pipe flow around a semi-circular constriction

Neumann-Kipping, M.; Hampel, U.

For the investigation of bubbly two-phase flow, which should serve as a future benchmark experiment for CFD code validation, an experimental study has been conducted at the Transient Two-Phase Flow (TOPFLOW) facility at Helmholtz-Zentrum Dresden – Rossendorf (HZDR) using ultrafast electron beam X-ray tomography (UFXRAY). In this study, flow constrictions were installed into a pipe to create a generic three-dimensional flow field as an advanced test case for CFD codes. UFXRAY provide valueable data of the gas phase dynamics with high temporal and spatial resolution.

The provided data set contains the entire results of the experimental series L30 that uses a semi-circular flow constriction with a blockage ratio of 0.5. 

An additional info.txt file provides all required information (e.g. nomenclature or binary file structure) and is, thus, necessary for interpretation of the experimental data.

Keywords: ultrafast X-ray computed tomography; bubbly two-phase flow; three-dimensional flow field; two-phase pipe flow; flow constriction; experimental benchmark data

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-12-01
    DOI: 10.14278/rodare.195
    License: CC-BY-NC-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29887
Publ.-Id: 29887


Hydrodynamic experimental benchmark data of bubbly two-phase pipe flow around a ring-shaped constriction

Neumann-Kipping, M.; Hampel, U.

For the investigation of bubbly two-phase flow, which should serve as a future benchmark experiment for CFD code validation, an experimental study has been conducted at the Transient Two-Phase Flow (TOPFLOW) facility at Helmholtz-Zentrum Dresden – Rossendorf (HZDR) using ultrafast electron beam X-ray tomography (UFXRAY). In this study, flow constrictions were installed into a pipe to create a generic three-dimensional flow field as an advanced test case for CFD codes. UFXRAY provide valueable data of the gas phase dynamics with high temporal and spatial resolution.

The provided data set contains the entire results of the experimental series L32 that uses a ring-shaped flow constriction with a blockage ratio of 0.5. 

An additional info.txt file provides all required information (e.g. nomenclature or binary file structure) and is, thus, necessary for interpretation of the experimental data.

Keywords: ultrafast X-ray computed tomography; bubbly two-phase flow; three-dimensional flow field; two-phase pipe flow; flow constriction; experimental benchmark data

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-12-01
    DOI: 10.14278/rodare.197
    License: CC-BY-NC-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29886
Publ.-Id: 29886


Ultrafast X-ray tomography image data of bubbly two-phase pipe flow around a semi-circular constriction

Neumann-Kipping, M.; Hampel, U.

For the investigation of bubbly two-phase flow, which should serve as a future benchmark experiment for CFD code validation, an experimental study has been conducted at the Transient Two-Phase Flow (TOPFLOW) facility at Helmholtz-Zentrum Dresden – Rossendorf (HZDR) using ultrafast electron beam X-ray tomography (UFXRAY). In this study, flow constrictions were installed into a DN50 pipe to create a generic three-dimensional flow field as an advanced test case for CFD codes. UFXRAY CT scans were performed in dual-imaging mode and 9 imaging planes for 15 s with a temporal resolution of 1.0 kHz and 2.5 kHz to provide valuable data of the gas phase dynamics.

The provided data set contains tomographic image data for the experimental series L30 that uses a semi-circular flow constriction with a blockage ratio of 0.5. Here, all image stacks for a given operating point are stored in a single HDF5 file with a spatial resolution of 0.5 mm/pixel (Images are stacked as time series). Further attributes (e.g. reconstruction parameters) are available for each image stack and are accessible e.g. using Matlab or Octave. The relative distance of the each respective scanning position is defined in an additional info.txt. 

Keywords: ultrafast X-ray computed tomography; bubbly two-phase flow; three-dimensional flow field; two-phase pipe flow; tomographic image data

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-08-01
    DOI: 10.14278/rodare.137
    License: CC-BY-NC-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29885
Publ.-Id: 29885


Structural, Magnetocaloric, and Critical Behavior of La0.5Ca0.5Mn1−xVxO3 Manganites Prepared by High-Energy Ball Milling

Mansouri, M.; Fallarino, L.; M'Nassri, R.; Cheikhrouhou-Koubaa, W.; Cheikhrouhou, A.

The high-energy ball milling method has been used to synthesize the polycrystalline powders La0.5Ca0.5Mn1−xVxO3 (x = 0.05, x = 0.10). The Rietveld refinement technique shows that the samples crystallized in the orthorhombic structure with the Pbnm space group. The La0.5Ca0.5Mn0.95V0.05O3 exhibits a second-order phase transition from paramagnetic (PM) to ferromagnetic (FM) state at TC = 208 ± 1 K followed by a second one from FM to charge ordering–antiferromagnetic state at TN = 150.0 ± 0.1 K when decreasing temperature. The substituted sample with 10% amount of vanadium dopant corresponds to the disappearance of the charge-order phase; meanwhile, it was suppressed for 5% of the vanadium in the solid-state route. The Curie temperature TC increases with vanadium content from 208 ± 1 K for x = 0.05 to 255 ± 1 K for x = 0.10. The values of the maximum of the magnetic entropy change under a magnetic field change of 5 T are found to be 2.95 ± 0.04 J kg−1 K−1 and 5.42 ± 0.07 J kg−1 K−1 corresponding to a relative cooling power RCP = 128.4 ± 0.3 and 220.8 ± 0.7 for x = 0.05 and x = 0.10 respectively. The order of phase transition has been determined. The critical exponent study has been performed for La0.5Ca0.5Mn0.9V0.10O3 by using the Arrott plot, Kouvel–Fisher method, and critical isotherm analysis. The measured β, γ, and δ values are in agreement with those expected for the tricritical mean-field model.

Keywords: Critical exponents; High-energy ball milling; Magnetocaloric effect; Manganites

Permalink: https://www.hzdr.de/publications/Publ-29884
Publ.-Id: 29884


The formation of Ni germanides by magnetron sputtering and flash lamp annealing

Rebohle, L.; Begeza, V.; Garcia Munoz, A.; Neubert, M.; Xie, Y.; Prucnal, S.; Grenzer, J.; Hübner, R.; Zhou, S.

Silicides have been widely used for CMOS devices in order to provide a stable Ohmic contact with a low contact resistivity. With the integration of Ge on Si the focus also shifted to germanides as a low resistivity contact material. In addition, ferromagnetic germanides may serve as spin injector materials for Ge-based spintronic devices. Usually, germanides have been fabricated by furnace or rapid thermal annealing in literature.

In this contribution we investigate the formation process of Ni germanides using a combination of magnetron sputtering and flash lamp annealing (FLA). Three different types of Ge served as a substrate for the deposition of the transition metal: amorphous Ge made by magnetron-sputtering on a SiO2-Si substrate, polycrystalline Ge made by magnetron-sputtering followed by FLA, and monocrystalline Ge in the form of a (100) Ge wafer. After metal deposition samples are in-situ annealed by FLA without breaking the vacuum, which triggers the formation of germanides and prevents a possible, but unwanted oxidation. In order to investigate the crystallization behavior, the structures have been characterized by Raman spectroscopy, X-ray diffraction, ellipsometry, current-voltage and Hall effect measurements.

Keywords: flash lamp annealing; magnetron sputtering; nickel germanide

  • Lecture (Conference)
    EMRS 2019 Fall Meeting, 16.-19.09.2019, Warsaw, Poland

Permalink: https://www.hzdr.de/publications/Publ-29883
Publ.-Id: 29883


Ultrafast X-ray tomography image data of bubbly two-phase pipe flow around a ring-shaped constriction

Neumann-Kipping, M.; Hampel, U.

For the investigation of bubbly two-phase flow, which should serve as a future benchmark experiment for CFD code validation, an experimental study has been conducted at the Transient Two-Phase Flow (TOPFLOW) facility at Helmholtz-Zentrum Dresden – Rossendorf (HZDR) using ultrafast electron beam X-ray tomography (UFXRAY). In this study, flow constrictions were installed into a DN50 pipe to create a generic three-dimensional flow field as an advanced test case for CFD codes. UFXRAY CT scans were performed in dual-imaging mode and 9 imaging planes for 15 s with a temporal resolution of 1.0 kHz and 2.5 kHz to provide valuable data of the gas phase dynamics.

The provided data set contains tomographic image data for the experimental series L32 that uses a ring-shaped flow constriction with a blockage ratio of 0.5. Here, all image stacks for a given operating point are stored in a single HDF5 file with a spatial resolution of 0.5 mm/pixel (Images are stacked as time series). Further attributes (e.g. reconstruction parameters) are available for each image stack and are accessible e.g. using Matlab or Octave. The relative distance of the each respective scanning position is defined in an additional info.txt. 

Keywords: ultrafast X-ray computed tomography; bubbly two-phase flow; three-dimensional flow field; two-phase pipe flow; tomographic image data

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-08-01
    DOI: 10.14278/rodare.139
    License: CC-BY-NC-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29882
Publ.-Id: 29882


Measurement of f orbital hybridization in rare earths through electric dipole-octupole interference in X-ray Absorption Spectroscopy

Juhin, A.; Collins, S. P.; Joly, Y.; Diaz-Lopez, M.; Kvashnina, K.; Glatzel, P.; Brouder, C.; de Groot, F.

This work provides a direct route to measure the degree of hybridization of f states in rare earths. The interference between electric dipole and octupole transitions is measured at the L1 edge of Gd in Gd3Ga5O12 using X-ray Natural Linear Dichroism (XNLD) and high energy resolution fluorescence detection. The Gd 4f-6p admixture is quantiffed through the integral of the dipole-octupole XNLD using a new sum rule easily applicable to experimental data. The mixing of the Gd valence states with the O ligand orbitals, calculated from first-principles, reveals that despite their localized character, the Gd 4f orbitals mix with the O 2p and 2s orbitals with an antibonding and bonding character, respectively.

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Permalink: https://www.hzdr.de/publications/Publ-29881
Publ.-Id: 29881


Nanoscale mechanism of UO2 formation through uranium reduction by magnetite

Pan, Z.; Bártová, B.; Lagrange, T.; Shen, T.; Tileli, V.; Butorin, S.; Hyatt, N. C.; Stennett, M. C.; Kvashinina, K. O.; Bernier-Latmani, R.

Significance:
Uranium (U) biogeochemical behavior is constrained by redox transformations. In anoxic environments, soluble hexavalent U is reduced and immobilized as tetravalent U. During abiotic U reduction, the formation of tetravalent U oxide (UO2) has been demonstrated and the persistence of an intermediate (pentavalent) valence state invoked. However, despite decades of study, there is little insight into the molecular mechanistic details of UO2 formation. Here, we show the formation of transient nanowires composed of randomly oriented UO2 nanoparticles followed by rearrangement into ordered UO2 nanoclusters. We also evidence the persistence of pentavalent U on the magnetite surface. These findings have implications for uranium isotopic fractionation, nuclear waste, and uranium remediation.

Abstract:
Uranium (U) is a ubiquitous element, present in the Earth’s crust at ~2 ppm. In anoxic environments, soluble hexavalent uranium (U(VI)) is reduced and immobilized. The underlying reduction mechanism is unknown but is likely of critical importance to explain variability in isotopic fractionation depending on the reducing agent and the chemical conditions. Here, we tackle the mechanism of reduction of U(VI) by the mixed-valence iron oxide, magnetite (Fe3O4). Through a combination of high-end spectroscopic and microscopic tools, we demonstrate that the reduction of U(VI) proceeds first through surface-associated U(VI) to form pentavalent U, U(V). U(V) persists on the surface of magnetite and is further reduced to tetravalent UO2 in the form of nanocrystals (~1-2 nm) arranged at random orientations in nanowires that extend hundreds of nanometers from the magnetite surface. Through re-orientation of the nanoparticles and their coalescence into larger nanoparticles, the nanowires collapse after several weeks to generate ordered UO2 nanoclusters. Thus, this work provides evidence for a transient U nanowire structure that may have implications for uranium isotope fractionation as well as for molecular-scale understanding of nuclear waste temporal evolution and the reductive remediation of uranium contamination.

Permalink: https://www.hzdr.de/publications/Publ-29880
Publ.-Id: 29880


Pathways to a nuclear waste repository in Germany

Foerstendorf, H.

Pathways to a nuclear waste repository in Germany

  • Invited lecture (Conferences)
    The Chemistry of f-Elements Autumn School, 12.-16.11.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29879
Publ.-Id: 29879


Stratified & Segregated Flow Modelling – Algebraic Interfacial Area Density

Höhne, T.

Optimization of large-scale multiphase processes requires adequate and efficient CFD-tools.
• Large scales flow behavior depend on sub-grid physical phenomena that have to be described by closure models.
• Different models necessary for dispersed particles and separated continuous phases (interfacial drag etc.)
• Applications: Flow patterns in horizontal pipes, separation processes in rectification columns, stirred tank reactors etc.

Keywords: AIAD; Two phase flow; CFD; stratified; Gas; Liquid

  • Lecture (Conference)
    17th Multiphase Flow Conference and Short Course, 11.-15.11.2019, Dresden, Deutschland
  • Poster
    17th Multiphase Flow Conference and Short Course, 11.-15.11.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29878
Publ.-Id: 29878


Neuroprogressive character of sigma-1 receptor pathophysiology in unmedicated patients with acute major depressive disorder as investigated by (-)-[18F]Fluspidine PET

Meyer, P.; Strauss, M.; Becker, G.; Hesse, S.; Bednasch, K.; Ettrich, B.; Wilke, S.; Zientek, F.; Rullmann, M.; Luthardt, J.; Fischer, S.; Patt, M.; Wünsch, B.; Brust, P.; Sabri, O.

Aim/Introduction:
We have previously shown that the sigma-1 receptor(Sig-1R) availability is increased in unmedicated acute MDD (MDD) using (-)-[18F]Fluspidine PET. In order to assess whether this pathophysiology is progressive, we investigated the relationship between Sig-1R availability and duration of disease (DD), number of depressive episodes (DE) and severity of acute depressive symptoms (Hamilton Depression Rating Scale, HAMD) in this now completed first-in-human (-)-[18F]Fluspidine PET trial.
Materials and Methods:
Patients with moderate to severe MDD (n=18; 32±12 years; 9 females; DD 6±8 years; DE 3±1 years; HAMD: 20±4) were studied using (-)-[18F]Fluspidine PET (300 MBq, ECAT Exact HR+) and compared with sex-/age-matched healthy controls (HC; n=16; 32±13ys [n.s.]; 9 females [n.s.]). VOI analyses were performed and regional distribution volumes (VT) were estimated by kinetic modeling (0-210 min p.i.; 2TCM; metabolite correction).
Results:
In MDD, compared with HC, VT was higher especially within the fronto-temporal, anterior cingulate and insular cortices, amygdala, striatum, thalamus and ncl. raphe (P<0.005). Positive correlations were found between HAMD and VT within the anterior and posterior cingulate and insular cortices, ncl. caudatus and thalamus (r=0.43 to 0.57, P<0.05, adjusted for DD, BMI).Negative correlations were found between DD and VT within the orbitofrontal cortex and hypothalamus (r=-0.40 to -0.47, P<0.05, adjusted for severity of MDD) and between DE and VT within the hypothalamus, orbitofrontal, temporo-parietal and cingulate cortices, striatum, thalamus and cerebellum (r=-0.42 to -0.60, P<0.05, adjusted for severity of MDD).
Conclusion:
Using (-)-[18F]Fluspidine PET, we showed for the first time increased cortico-(para-)limbic Sig-1R availability during the DE of MDD, as compared with HC, that was associated with the severity of acute depressive symptoms (HAMD). Remarkably, in MDD, there is a negative correlation between DE or DD and Sig1-R availability, especially within orbitofrontal cortices and hypothalamus as well as within various (sub)cortical-(para)limbic and cerebellar brain regions. Although verification by longitudinal (-)-[18F]Fluspidine PET studies is needed, our findings suggest a neuroprogressive character of Sig-1R pathophysiology in MDD.

Keywords: sigma-1 receptor; acute major depressive disorde; (-)-[18F]Fluspidine; PET

  • Lecture (Conference)
    Annual Congress of the European Association of Nuclear Medicine, 12.-16.10.2019, Barcelona, Barcelona, Spain
    DOI: 10.1007/s00259-019-04486-2

Permalink: https://www.hzdr.de/publications/Publ-29877
Publ.-Id: 29877


Low damping and microstructural perfection of sub-40nm-thin yttrium iron garnet films grown by liquid phase epitaxy

Dubs, C.; Surzhenko, O.; Thomas, R.; Osten, J.; Schneider, T.; Lenz, K.; Grenzer, J.; Hübner, R.; Elke, W.

The field of magnon spintronics is experiencing increasing interest in the development of solutions for spin-wave-based data transport and processing technologies that are complementary or alternative to modern CMOS architectures. Nanometer-thin yttrium iron garnet (YIG) films have been the gold standard for insulator-based spintronics to date, but a potential process technology that can deliver perfect, homogeneous large-diameter films is still lacking. We report that liquid phase epitaxy (LPE) enables the deposition of nanometer-thin YIG films with low ferromagnetic resonance losses and consistently high magnetic quality down to a thickness of 10 nm. The obtained epitaxial films are characterized by an ideal stoichiometry and perfect film lattices, which show neither significant compositional strain nor geometric mosaicity, but sharp interfaces. Their magneto-static and dynamic behavior is similar to that of single crystalline bulk YIG. We found, that the Gilbert damping coefficient  is independent of the film thickness and close to 1  10-4, and that together with an inhomogeneous peak-to-peak linewidth broadening of H0|| = 0.4 G, these values are among the lowest ever reported for YIG films with a thickness smaller than 40 nm. Only for the 10-nm-thin film a significantly reduced saturation magnetization was observed. These results suggest, that nanometer-thin LPE films can be used to fabricate nano- and micro-scaled circuits with the required quality for magnonic devices. The LPE technique is easily scalable to YIG sample diameters of several inches.

Keywords: YIG; ferromagnetic resonance; linewidth; damping; thin films; liquid phase epitaxy

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Permalink: https://www.hzdr.de/publications/Publ-29876
Publ.-Id: 29876


Spektroskopische Methoden für die Endlagerforschung

Drobot, B.

Spektroskopische Methoden generieren molekulares Prozessverständnis. Dies ist wichtig für die Erhöhung der Belastbarkeit von Risokoanalysen im Endlager-Kontext.

Keywords: Endlager; Spektroskopie

  • Invited lecture (Conferences)
    Kraftwerkstechnisches Kolloquium, 23.10.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-29875
Publ.-Id: 29875


HZDR Data Management Strategy — Top-Level Architecture

Knodel, O.; Gruber, T.; Müller, S.; Juckeland, G.

Top-Level Architecture of the proposed HZDR Data Management Strategy

Keywords: data management

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-02-12
    DOI: 10.14278/rodare.193
    License: CC-BY-NC-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29873
Publ.-Id: 29873


Hydrodynamic investigations of gas-liquid two-phase flow in centrifugal pumps - reconstructions (selected data)

Schäfer, T.; Bieberle, A.; Hampel, U.

This data repository contains reconstructed and quantitatively analyzed gas-liquid two-phase distributions obtained from a centrifugal pump mock-up whose geometry is related to a commercially available industrial centrifugal pump. As measurement system the ultrafast electron beam X-ray CT scanner (UFXCT) is applied with a frame rate of 2,500 Hz, single-plane mode and a total scanning interval of 5 seconds. The data repository contains:

  • Reconstructed raw data (FBP) sets for selected two-phase flow operating conditions at constant 1480 rpm with static and rotating impeller, respectively
  • Corresponding quantitative gas fraction data sets (for static impeller position)
  • Averaged gas fraction distributions
  • Standard deviations of the gas fraction mean values
  • Data evaluation scripts

Keywords: centrifugal pump; gas-liquid two-phase flow; ultrafast X-ray computed tomography

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-10-30
    DOI: 10.14278/rodare.189

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29872
Publ.-Id: 29872


Cross section of α-induced reactions on 197Au at sub-Coulomb energies

Szücs, T.; Mohr, P.; Gyürky, G.; Halász, Z.; Huszánk, R.; Kiss, G. G.; Szegedi, T. N.; Török, Z.; Fülöp, Z.

Statistical model calculations have to be used for the determination of reaction rates in large-scale reaction networks for heavy-element nucleosynthesis. A basic ingredient of such a calculation is the a-nucleus optical model potential. Several different parameter sets are available in literature, but their predictions of a-induced reaction rates vary widely, sometimes even exceeding one order of magnitude.
This paper presents the result of a-induced reaction cross-section measurements on gold which could be carried out for the first time very close to the astrophysically relevant energy region. The new experimental data are used to test statistical model predictions and to constrain the a-nucleus optical model potential.
For the measurements the activation technique was used. The cross section of the (a,n) and (a,2n) reactions was determined from g-ray counting, while that of the radiative capture was determined via X-ray counting.
The cross section of the reactions was measured below Ea=20.0~MeV. In the case of the 197Au(a,2n)199Tl reaction down to 17.5~MeV with 0.5-MeV steps, reaching closer to the reaction threshold than ever before. The cross section of 197Au(a,n)200Tl and 197Au(a,g)201Tl was measured down to Ea=13.6 and 14.0~MeV, respectively, with 0.5-MeV steps above the (a,2n) reaction threshold and with 1.0-MeV steps below that.
The new dataset is in agreement with the available values from the literature, but is more precise and extends towards lower energies. Two orders of magnitude lower cross sections were successfully measured than in previous experiments which used g-ray counting only, thus providing experimental data at lower energies than ever before. The new precision dataset allows us to find the best-fit a-nucleus optical model potential and to predict cross sections in the Gamow window with smaller uncertainties.

Keywords: Nuclear Astrophysiscs; Heavy element nucleosynthesis; Alpha induced reactions

Permalink: https://www.hzdr.de/publications/Publ-29871
Publ.-Id: 29871


Impact of milling condition on the flotation of Vietnamese silicaceous carbonaceous apatite ore

Hoang, D. H.; Saquran, S. S.; Hassanzadeh, A.; Kupka, N.; Michaux, B.; Schach, E.; Sprenger, H.; Rudolph, M.

This study aims to endeavor the role of milling environment on the output particle properties and on the batch flotation behavior of a siliceous carbonaceous sedimentary apatite ore. For this purpose, the milling prior to the flotation was performed in three conditions, i.e. dry, wet and wet-conditioned using a rod mill and finding the milling times in order to have the same particle size distribution (PSD). Flotation experiments were carried out in a 4 L agitating mechanical cell at pH10 adjusted by Na2CO3, sodium silicate (400 g/t) and corn starch (200 g/t) as depressants. Atrac 922 (350 g/t) and MIBC (15 g/t) were added as collector and frother, respectively. Concentrates and tailings were mineralogically and chemically characterized by automated mineralogy (Mineral Liberation Analyzer - MLA) and inductively coupled plasma - optical emission spectrometry (ICP - OES), respectively. It was shown that the flotation feed particle size distributions (PSDs), apatite and dolomite liberation degrees (LDs) and water properties were remained constant for all three milling configurations which allowed to eliminate their effectiveness on floatability responses.
The experimental results showed that the different particle properties (i.e., particle size, mineral liberation), pulp/ froth properties (Ca2+/ Mg2+ ions concentration, pulp rheology, froth structure) under different milling conditions, which in turn influences on the flotation response (grade, recovery, flotation kinetics and selectivity between apatite and carbonate minerals). A feed ore containing about 12.4 % P2O5 and 7.3 % MgO, after rougher flotation, achieved concentrates with a P2O5 content of about 16.7-17 % at the recoveries of 88.6-92.3 %. However, the MgO content of 7.9-8.3 % in the apatite concentrates is higher compared to the feed, where only 24-29 % of dolomite was removed. Hence, the separation between apatite-carbonates is very challenging for fine intergrowth sedimentary siliceous carbonaceous apatite ores, which will need further investigation on optimization of reagent regime, especially, depressants of carbonates minerals.

Keywords: Dry and wet milling; Ca2+/ Mg2+ concentration; flotation; calcium-bearing minerals; carbonate depressant

  • Open Access Logo Contribution to proceedings
    IMPC-Eurasia 2019, 31.10.-02.11.2019, Antalya, Turkey
    IMPC-Eurasia 2019, 1st regional Mineral Processing Conference, 978-975-7946-44-1

Permalink: https://www.hzdr.de/publications/Publ-29870
Publ.-Id: 29870


Interactive effect of particle size, liberation and hydrophobicity on the flotation kinetics of a carbonaceous phosphate deposit

Hoang, D. H.; Schach, E.; Hassanzadehmahaleh, A.; Kupka, N.; Pereira, L.; Rudolph, M.

Selective separation of apatite from the associated minerals (quartz, calcite and dolomite) in a carbonaceous phosphate ore type strongly depends on the interactive effect of particle size, hydrophobicity and mineral liberation degree (LD). This study aims to investigate these parameters by paying close attention to distinguishing true flotation (attachment) and entrainment phenomena respectively in pulp and froth zones. Modified flotation kinetics (kM) were used for estimating flotation rates of the different minerals on size-by-liberation in terms of taking the combination of infinitive recovery (Rmax) and k into account. The results indicate that the LD plays an insignificant role on kM of fine apatite particles (< 20 µm) due to transporting to the concentrate by both true flotation and entrainment mechanisms. In contrast, kM of the coarse apatite particles (> 20 µm) is strongly influenced by the LD. Additionally, the recovery of fully liberated apatite in the four studied size ranges was found fairly similar. However, both size and LD are significantly affecting the recovery of liberated gangue minerals where both true flotation and entrainment occurred for carbonates and entrainment for silicates.

  • Contribution to proceedings
    Procemin-Geomet 2019, 20.-22.11.2019, Santiago, Chile
    Procemin-Geomet 2019

Permalink: https://www.hzdr.de/publications/Publ-29868
Publ.-Id: 29868


Neutron radiography of particle-laden liquid metal flow driven by an electromagnetic induction pump

Lappan, T.; Sarma, M.; Heitkam, S.; Trtik, P.; Mannes, D.; Eckert, K.; Eckert, S.

Ladle metallurgy treatment affects the chemical composition and the impurities in molten steel. To remove non-metallic inclusions, gas injection into the ladle and intense stirring by bubbly flows are essential in the refining process. This paper reports on a model experiment that provides an insight into the bubble – particle interaction in liquid metal at room temperature. We apply neutron radiography as imaging technique for particle-laden liquid metal flow around a cylindrical obstacle representing a single rising bubble. The experimental setup is tailored to both the measurement principle of neutron transmission imaging and the design of the disc-type induction pump driving the flow. A liquid metal loop of 30 mm x 3 mm rectangular cross section is filled with low-melting gallium-tin alloy. Gadolinium oxide particles (0.3 – 0.5mm) are employed because of their superior neutron attenuation compared to liquid gallium-tin. The neutron image sequences visualise the particle trajectories in the opaque liquid metal with high temporal resolution (100 fps). Up- and downstream the cylindrical obstacle, we analyse the velocity field as a function of the pump’s rotational speed by particle image velocimetry (PIV). The time-averaged particle velocity measured by PIV is lower than the circumferential velocity of the pump’s discs. This velocity deficit arises from the particles’ buoyancy and the pressure drop in the liquid metal loop. In the further analysis of these neutron image data, we will focus on the fluid flow in the wake of the cylindrical obstacle.

Keywords: neutron radiography; liquid metal; gadolinium oxide; induction pump; particle image velocimetry

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-29867
Publ.-Id: 29867


X-ray particle tracking velocimetry in liquid foam flow

Lappan, T.; Franz, A.; Schwab, H.; Kühn, U.; Eckert, S.; Eckert, K.; Heitkam, S.

In this work, we introduce a novel approach to measure the flow velocity of liquid foam by tracking custom-tailored 3D-printed tracers in X-ray radiography. In contrast to optical observations of foam flow in flat cells, the measurement depth equals 100mm in X-ray beam direction. Light-weight tracers of millimetric size and tetrapod-inspired shape are additively manufactured from stainless steel powder by selective laser melting. Matching with the foam structure and bubble size, these tracers follow the foam flow minimally invasively. An X-ray beam passes through the radiotransparent foam channel and is detected by an X-ray image intensifier. The X-ray transmission images show the two-dimensional projections of the radiopaque tracers. Employing particle tracking velocimetry algorithms, the tracer trajectories are measured with both high spatial (0.2 mm) and temporal (25 fps) resolution. Fine-pored and coarse-pored liquid foam flow of different velocities are studied in a partly curved channel with rectangular cross section. The simultaneous time-resolved measurement of the tracers' translational motion and their intrinsic rotation reveal both the local velocity and vorticity of the foam flow. In the semi-circular curved channel section, the rigid-body-like flow pattern is investigated. Moreover, a relaxation of the foam structure in the transition zone between straight and curved section is observed.

Keywords: X-ray radiography; particle tracking velocimetry; liquid foam; flow tracer

  • Soft Matter 16(2020)8, 2093-2103
    DOI: 10.1039/C9SM02140J
  • Lecture (Conference) (Online presentation)
    EUFoam 2020, 07.-10.07.2020, Aberystwyth, United Kingdom

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  • Secondary publication expected from 04.02.2021

Permalink: https://www.hzdr.de/publications/Publ-29866
Publ.-Id: 29866


Status and innovations in pre-treatment CT imaging for proton therapy

Wohlfahrt, P.; Richter, C.

Pre-treatment CT imaging is a topic of growing importance in particle therapy. Improvements in the accuracy of stopping-power prediction are demanded to allow for a dose conformality that is not inferior to state-of-the-art image-guided photon therapy. Although range uncertainty has kept practically constant over the last decades, recent technological and methodological developments, like the clinical application of dualenergy CT, have been introduced or arise at least on the horizon to improve the accuracy and precision of range prediction. This review gives an overview of the current status, summarizes the innovations in dual-energy CT and its potential impact on the field as well as potential alternative technologies for SPR prediction.

Keywords: Dual-energy CT; range prediction; stopping-power ratio; stopping-power prediction; SPR; proton therapy

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  • Secondary publication expected from 11.11.2020

Permalink: https://www.hzdr.de/publications/Publ-29865
Publ.-Id: 29865


Dynamical freeze-out phenomena: The case of K±,ϕ transverse momentum spectra in collisions of Au(1.23 A GeV) + Au

Rabe, B.; Kämpfer, B.

We argue on a continuous (dynamical) kinetic freeze-out of K±,ϕ observed at midrapidity in collisions Au(1.23 A GeV) + Au. The simulations by means of a transport model of BUU type point to time independent transverse momentum slope parameters after 20 fm/c. The complex interplay of expansion dynamics and strangeness production/exchange/absorption as well as elastic scatterings involved in the reaction network does not support the previous interpretation of a late freeze-out of K− due to larger cross sections.

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Permalink: https://www.hzdr.de/publications/Publ-29863
Publ.-Id: 29863


Entangling continuous variables with a qubit array

Navez, P.; Sowa, A.; Zagoskin, A.

We show that an array of qubits embedded in a waveguide can emit entangled pairs of microwave photon beams. The quadratures obtained from the homodyne detection of these outputs beams form a pair of correlated continuous variables similar to the Einstein-Podolsky-Rosen experiment. The photon pairs are produced by the decay of plasmonlike collective excitations in the qubit array. The maximum intensity of the resulting beams is bounded by only the number of emitters. We calculate the excitation decay rate both into a continuum of the photon state and into a one-mode cavity. We also determine the frequency of Rabi-like oscillations resulting from a detuning.

Permalink: https://www.hzdr.de/publications/Publ-29862
Publ.-Id: 29862


Plasmonic nonlinearity in GaAs/In0.20Ga0.80As core/shell nanowires

Rana, R.; Balaghi, L.; Fotev, I.; Schneider, H.; Helm, M.; Dimakis, E.; Pashkin, O.

We have investigated the plasmonic response of GaAs/In0.20Ga0.80As core/shell nanowires driven resonantly by strong THz fields with the amplitude of few MV/cm. The plasmon mode exhibits a systematic redshift with the suppression of the spectral weight with the increase of the driving THz field. Interestingly, the scaling of the plasmon parameters does not follow the usual quadratic behavior, indicating an inhomogeneous intervalley electron scattering across the nanowire.

Keywords: Plasmons; Nanowires; Nonlinear optics

  • Contribution to proceedings
    44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 01.-06.09.2019, Paris, France
    2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), IEEE Xplore: IEEEE, 978-1-5386-8285-2
    DOI: 10.1109/IRMMW-THz.2019.8874085

Permalink: https://www.hzdr.de/publications/Publ-29861
Publ.-Id: 29861


Mobility of radionuclides enhanced by complexing agents used in a repository: Modeling sorption and transport

Karimzadeh, L.; Lippold, H.; Fischer, C.

Among the organic inventory of a nuclear waste repository, aminopolycarboxylic acids, which are used as decontamination agents during operation, are of particular concern in view of their chelating capability and high persistence, but data regarding their impact on the mobility of radionuclides in geological barriers are missing so far. Migration in the host rock is controlled by sorption reactions on mineral surfaces, potentially affected by organic complexing ligands. As a case study, using 152Eu as a short-lived tracer analogue of actinides, we investigated sorption of Eu(III) onto quartz surfaces as a function of pH in the absence and presence of the complexant diethylenetriaminepentaacetic acid (DTPA). The transport behavior was studied in column experiments (up- and down-flooding) at neutral pH in order to detect possible inconsistencies between sorption in batch systems and retardation in dynamic systems.
The effect of DTPA on sorption of Eu(III) was found to be strongly dependent on pH. At neutral and alkaline conditions, sorption is considerably decreased, resulting in accelerated breakthrough and facilitated elution in column experiments. Sorption as a function of DTPA concentration and pH was completely described by surface complexation modeling based on the Diffuse Double Layer Model of Dzombak and Morel, using the speciation program PHREEQC coupled with the parameter estimation code PEST. Results of column experiments were simulated in 1D calculations by means of the obtained surface complexation parameters. Breakthrough and elution curves were perfectly reproduced without readjustments.

  • Poster
    Jahrestagung der GDCh, Fachgruppe Nuklearchemie, 25.-27.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29859
Publ.-Id: 29859


Thermo-physical properties of coatings in the Ti(B,N) system grown by chemical vapor deposition

Kainz, C.; Schalk, N.; Tkadletz, M.; Saringer, C.; Winkler, M.; Stark, A.; Schell, N.; Julin, J.; Czettl, C.

Hard protective coatings are commonly subjected to temperatures exceeding 1000 °C, which has significant influence on their thermo-physical properties and the associated performance in application. Within the present work, temperature dependent physical properties of coatings within the Ti(B,N) system grown by chemical vapor deposition were correlated with their chemical composition. High-energy X-ray diffraction experiments in inert atmosphere proved that TiN, TiB₂ and ternary TiBxNy coatings with varying B contents are thermally stable up to 1000 °C. First order lattice strains of TiN and TiBxNy coatings diminish during heating, whereas TiB₂ exhibits compressive strain enhancement up to the deposition temperature. Nanocrystalline TiB₂ exhibits more pronounced grain growth during annealing compared to coarse grained columnar TiN. Within the investigated coatings, the mean thermal expansion coefficient decreases as the B content increases. The same trend was observed for the thermal conductivity, which correlates with the grain size of the coatings.

Keywords: Chemical vapor deposition; X-ray diffraction; Ti(B,N); thermal conductivity; strain

Permalink: https://www.hzdr.de/publications/Publ-29858
Publ.-Id: 29858


Produktion und Reinigung von n.c.a. 48V am Leipziger Zyklotron für Extraktionsstudien

Mansel, A.; Franke, K.

Vanadium ist ein Bestandteil in Eisen-Chromschlacken und gilt als strategisches Wertmetall. Um effiziente Abtrennungsverfahren von fünfwertigem Vanadium vom dreiwertigen Chrom bzw. sechswertigem Chromat mit Hilfe der Ionenchromatographie zu entwickeln, wurde die Radiotracertechnik eingesetzt [48V; T1/2 = 15,97 d; E = 984 keV; 99,97 %]. Die Produktion dieses Radionuklides wurde am Leipziger Zyklotron CYCLONE 18/9® durch die Kernreaktion natTi(p,n)48V realisiert. Eine Titanfolie (natürliche Isotopenzusammensetzung; 140 mg) wurde mit Protonen der Energie 12 MeV bei einem Strom von 22 µA für zwei Stunden bestrahlt. Das bestrahlte Target wurde für einen Tag zum Abklingen des kurzlebigen Radionuklides 47V (T1/2 = 32,6 min) aufbewahrt und anschließend in konzentrierter Schwefelsäure und wenigen Tropfen Flußsäure in einem Teflonbecher aufgelöst. Nach dem Eindampfen wurde der Rückstand mit 3 g Natriumcarbonat / 80 mg Natriumnitrat in einem Platintiegel für 30 Minuten bei 800 °C aufgeschlossen. Durch mehrmaliges Anlösen mit Wasser wurde das 48V in Form von Natriumvanadat vom Targetmaterial Titandioxid herausgelöst. Spuren von Titan wurden mit Hilfe eines Kationenaustauschers (DOWEX 50 W X-8) bei pH 3 abgetrennt und das Vanadylion in Form von Vanadat mit 20 %igem Ammoniak eluiert. Die radiochemische Ausbeute betrug (95 ± 8) %. Die Aktivität betrug fünf Stunden nach Bestrahlungsende ~ 245 MBq und die Nachweisgrenze wurde zu 8 fM (~0,4 pg/L) für n.c.a. 48V ermittelt.

  • Poster
    GDCh Jahrestagung der Fachgruppe Nuklearchemie, 24.-27.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29857
Publ.-Id: 29857


Coupled processes across a claystone-concrete interface: results of a combined X-ray CT and PET transport experiment

Mäder, U.; Bernard, E.; Kulenkampff, J.; Jenni, A.

Interfaces between dense clay materials and cementitious materials are studied in the context of deep disposal of radioactive waste for one main reason: mineral reactions due to contrasting chemistries will modify the pore network and affect transport of water, solutes and gas. Substantial research efforts were directed towards mineralogical and physical characterisation of interface regions (e.g. Mäder et al. 2018) but little evidence exists on direct observations of transport behaviour across such skins. This study aims at providing evidence on how mineralogical-physical changes at such an interface affect transport of water and solutes, and linking mineralogical-physical characterisation, X-ray computed tomography and positron emission tomography (PET).

We developed an X-ray transparent core infiltration apparatus whereby a sample core subject to a hydraulic confining pressure can be tested with a hydraulic gradient (Mäder, 2018, for details of method and design in steel and titanium). This compact apparatus uses a carbon fibre tube as pressure vessel and various polymer plastics for other components. Several small pressure tanks integrated into the apparatus allow for self-contained operation for several days, and switching of the percolating fluid. A further extension in form of an integrated lead-shielded pressure container allows also for using radioactive tracers such that the equipment can be used for positron-emission tomography (PET). PET is a superb method to directly image the mobile phase in 3D, and its time evolution (Kuhlenkampff et al., 2017).

A 14 year-old sample core was recovered by stabilized drilling from a long term in situ experiment (CI) at the Mont Terri rock laboratory (Mäder et al., 2018), containing a physically preserved interface between Opalinus Clay and OPC concrete. This larger sample (101 mm DM) was sub-sampled and a 50x50 mm core was stabilised and cored from it. The clay part shows pre-existing bedding-parallel weak jointing that can also be seen in high resolution X-ray CT. The aged interface shows mineral transformations at the mm scale with complex mineral alteration patterns in both clay and cement matrix at a sub-mm scale, including porosity re-distribution and net reduction. The OPC concrete contains aggregate and gas pores. The compound sample may represent a repository situation of a claystone somewhat disturbed by excavation, in contact with a concrete liner, with pore water transport from clay across concrete.

A long-term transport experiment was set up by injecting a synthetic claystone pore water into the core sample on the clay-side, and force advection/diffusion across the interface and out of the cement-side. The fluid is traced with deuterium as water tracer, and periodically sampled for chemical and isotopic analysis. The sample was monitored frequently by high resolution X-ray CT during the first few days, and then regularly for the first 4 months. The running experiment was then transported to Leipzig and prepared for PET. 124I was used as PET tracer, and the chosen dose allowed for continuous PET scanning during two weeks, initially every 3 hrs.

A very large data set of 2D interface characterisation (SEM/EDX mapping, etc.) and time-resolved 3D CT and PET is presently being evaluated, enhanced, imaged and interpreted. Preliminary results document an initial self-sealing effect of the joint system in the Opalinus Clay, permeation into the diffusion-controlled pore network in claystone and cement matrix, and partial filling of gas pores. PET captures some preferential flow across claystone along some remaining joints, a spreading of the tracer plume at the clay/cement interface, and some moderate preferential flow across OPC.

This approach provides much more detailed information of coupled processes in complex porous media by imaging both the stationary and the mobile phase. Compared to summation parameters, such as tracer breakthrough, there is infinitely more information obtained about the localisation of flow and the nature of the pore network and its temporal evolution.

The research leading to these results has also received funding from the European Union's European Atomic Energy Community's (Euratom) Horizon 2020 Programme (NFRP-2014/2015) under grant agreement, 662147 – Cebama. Uni Bern acknowledges funding contributions by Nagra and the Mont Terri Consortium (CI Experiment).



Kulenkampff, J., Gründig, M., Zakhnini, A., Lippmann-Pipke, J. (2016). Geoscientific process monitoring with positron emission tomography (GeoPET). Solid Earth 7, 1207-2015.
U. Mäder (2018). Advective Displacement Method for the Characterisation of Pore Water Chemistry and Transport Properties in Claystone, Geofluids, 2018.
U. Mäder, A. Jenni, C. Lerouge, S. Gaboreau, S. Miyoshi, Y. Kimura, V. Cloet, M. Fukaya, F. Claret, T. Otake, M. Shibata, B. Lothenbach (2017). 5-year chemico-physical evolution of concrete-claystone interfaces, Swiss Journal of Geosciences, 110, 307-327.

Keywords: radioactive waste disposal; clay-cement interface; transport experiments; positron emission tomography; x-rax computed tomography

  • Open Access Logo Lecture (Conference)
    Decovalex 2019, 04.-05.11.2019, Brugg, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-29855
Publ.-Id: 29855


Lichtinduzierte Freisetzung von Kohlenstoffmonoxid aus Ruthenium(II)-Komplexen und deren biologische Bewertung

Geri, S.

Der Schwerpunkt der vorliegenden Masterarbeit liegt auf der Synthese neuer Ru(II)-basierter PhotoCORMs der Summenformel [RuL(CO)2Cl2] (L = Ligand). Als Liganden sollen 4,4‘-substituierte Derivate des 2,2‘-Bipyridins verwendet werden. 2,2‘-Bipyridine sind zweizähnige Lewis-Basen mit σ-Donor-Charakter, die mit Ruthenium in der Oxidationsstufe II stabile Chelatkomplexe bilden. Geeignete Funktionalisierung und strukturelle Erweiterung an den 4,4‘-Positionen des 2,2‘-Bipyridins soll den entstehenden PhotoCORMs neue Eigenschaften verleihen.
Der Schwerpunkt dieser Masterarbeit wird zunächst auf die Synthese eines Alkin-funktionalisierten PhotoCORMs gelegt. Alkin-Gruppen stellen eine Basis für die Bindung eines Azid-funktionalisierten Peptides mittels kupferkatalysierter Azid-Alkin 1,3-dipolarer Cycloaddition (CuAAC, „Click-Reaktion“) dar. Peptide geeigneten Designs können eine erhöhte Spezifität gegenüber bestimmtem Zelltyp induzieren, sodass das Peptid-funktionalisierte PhotoCORM bevorzugt in diesen Zellen angereichert wird.
Auch im zweiten Teil dieser Masterarbeit steht die Synthese eines Alkin-funktionalisierten PhotoCORMs im Vordergrund, allerdings soll hierbei der Fokus auf dessen Weiterfunktionalisierung mit einem Fluoreszenzfarbstoff gelegt werden. Durch direkte Substitution eines Fluoreszenzfarbstoffes am Grundgerüst des Bipyridins soll eine Erweiterung des bestehenden π-Systems erzielt werden. Als Folge werden eine bathochrome Verschiebung der MLCT-Bande, größere Quantenausbeuten sowie starke Fluoreszenz des neu synthetisierten PhotoCORMs erwartet. Letztere soll eine einfache visuelle Verfolgung der zellulären Aufnahme des in vitro verabreichten PhotoCORMs ermöglichen. Alternativ zu dieser Herangehensweise soll ein PhotoCORM synthetisiert werden, bei dem der Fluoreszenzfarbstoff mit dem Bipyridin-Grundgerüst über einen Amid-Linker verbunden ist.

Keywords: CO; Ru(II)-Komplexe; Therapie

  • Master thesis
    TU Dresden, 2019
    Mentor: Dr. Manja Kubeil / Dr. habil. Constantin Mamat
    108 Seiten

Permalink: https://www.hzdr.de/publications/Publ-29852
Publ.-Id: 29852


Neuartige Calix[4]benzokronen zur Komplexierung von schweren Erdalkalimetallionen

Blumberg, M.

Der Fokus dieser Arbeit liegt auf der Synthese neuer Chelatoren für die Komplexierung der schweren Erdalkalimetallionen Sr2+, Ba2+ und Ra2+. Ein besonderes Augenmerk liegt hierbei auf den für die Krebstherapie interessanten Radiumisotopen 223Ra und 224Ra und dem SPECT-Nuklid 131Ba als Matched Pair. Strontium besitzt mit 89Sr ebenfalls ein in der Nuklearmedizin nutzbares Nuklid. Außerdem kann auf Grundlage der Untersuchung der drei Erdalkalimetalle der Einfluss des Ionenradius auf die Komplexierungseigenschaften der Chelatoren bewertet werden. Zudem soll auch die Komplexierung mit dem ebenfalls zweiwertigen Pb2+ untersucht werden. Der β--Strahler 212Pb wird in der Radiopharmazie als in vivo-Generator des kurzlebigen α-Strahlers 212Bi in der Immuntherapie genutzt. 212Pb kommt wie 224Ra in der natürlichen Zerfallsreihe des 232Th vor.
Für die Komplexierung der genannten Metallionen sollen neuartige Calix[4]kronen synthetisiert werden, die nach dem Vorbild von Zhou et al. mit sauren Sulfonamidseitenketten funktionalisiert sind. Vorherige Extraktionsexperimente unserer Arbeitsgruppe haben gezeigt, dass Derivate mit perfluorierten Isopropylresten am Sulfonamid die effektivste Extraktion von Ba2+ und Ra2+ erlauben. Daher sollen Derivate mit diesen Seitenketten synthetisiert werden.
In dieser Arbeit soll die Modifizierung der Kronenetherüberbrückung der Calixarenderivate untersucht werden. Dafür soll ein aromatisches System in Form einer Benzokrone in den Chelator eingebaut werden. Eine solche Benzokrone bietet gegenüber der Krone-6 den Vorteil, dass sie mit zusätzlichen funktionellen Gruppen ausgestattet werden kann, um daran biologisch aktive Vektormoleküle zu binden. Die Einführung einer Amin-, Azid- oder Säurefunktion ermöglicht eine Kupplung an Peptide, Proteine oder Antikörper.

Keywords: Calixarene; Barium; Radium; Alpha-Therapie

  • Master thesis
    TU Dresden, 2019
    Mentor: Dr. habil. Constantin Mamat
    135 Seiten

Permalink: https://www.hzdr.de/publications/Publ-29851
Publ.-Id: 29851


Neuartige Käfigverbindungen zur Komplexierung von Barium und Radium

Eiselt, E.

Calixarene sind eine Gruppe von Verbindungen, welche eine vielseitige Nutzung zur Komplexierung von Ionen und kleinen Molekülen ermöglichen. Unter anderem können sie, durch die Einführung von Donorgruppen als Chelatoren für Gruppe-2-Metalle eingesetzt werden. Für eine zielgerichtete interne α-Therapie mit den therapeutisch zugänglichen Radiumisotopen 223Ra und 224Ra, ist es von Nöten, diese ausreichend stabil zu komplexieren. Damit soll eine unerwünschte Freisetzung und Anreicherung an anderen Orten im Körper weitgehend unterbunden werden.
Im Rahmen dieser Arbeit sollen Chelatoren entwickelt werden, welche Ba2+ als Surrogat für Ra2+ stabil und selektiv binden und eine weitere Funktionalisierung mit biologisch aktiven, zielsuchenden Molekülen zulassen. Auf Basis, der von Steinberg et al. veröffentlichten Ergebnisse sollen Verbindungen synthetisiert werden, welche statt einer Krone-6-Überbrückung offenkettige Etherfunktionen als Strukturmerkmal aufweisen. Dabei sollen sowohl Derivate mit zyklischen Amidfunktionen, als auch mit verschiedenen fluorierten Sulfonamiden funktionalisierte Verbindungen hergestellt werden. Weiterhin sollen Vorstufen für Liganden synthetisiert werden, welche über eine kurze Seitenkette mit zyklischen tertiären Aminen verfügen.
Alle Liganden sowie deren Vorstufen sollen mittels NMR-Spektroskopie und Massenspektrometrie eingehend charakterisiert werden. Die fertiggestellten Chelatoren werden mit der Methode der UV-Vis-Titration hinsichtlich ihrer Komplexbildungseigenschaften mit Ba2+, Sr2+ und Pb2+ untersucht. Die ermittelten Komplexstabilitäten sollen mit den analogen Krone-6-überbrückten Derivaten verglichen werden.

Keywords: Calixarene; Barium; Radium; Alpha-Therapie

  • Master thesis
    HTW Dresden, 2019
    Mentor: Dr. habil. Constantin Mamat (HZDR) / Prof. Dr. Marina Vogel (HTW)
    94 Seiten

Permalink: https://www.hzdr.de/publications/Publ-29850
Publ.-Id: 29850


The High-Energy-Density Physics at FAIR Collaboration: Unique Capabilities for HEDM Science

Schoenberg, K.; Bagnoud, V.; Blazevic, A.; Fortov, V. E.; Gericke, D. O.; Golubev, A.; Hoffmann, D. H. H.; Kraus, D.; Lomonosov, I. V.; Mintsev, V.; Neff, S.; Neumayer, P.; Piriz, A. R.; Redmer, R.; Rosmej, O.; Roth, M.; Schenkel, T.; Tahir, N. A.; Varentsov, D.; Zhao, Y.

The High-Energy-Density Science collaboration at the Facility for Antiproton and Ion Research (HED@FAIR) will utilize the World’s highest intensity relativistic beams of heavy nuclei to uniquely create and investigate highly energetic and dense-plasma states of cubic millimeter sized matter for durations of approximately 100 ns. Four principal themes of research have been identified by the HED@FAIR collaboration: Properties of materials driven to extreme conditions of pressure and temperatures, Shocked matter and material equation of state (EOS), Basic properties of strongly-coupled plasma and warm dense matter, and Nuclear photonics with a focus on the excitation of nuclear processes in plasmas, laser-driven particle acceleration, and neutron production. Collaboration research will develop over the next decade as the FAIR project is completed and the heavy ion beam and experimental capabilities evolve. The so-called "FAIR Phase 0" experiments officially began in 2018 to test the components and detectors prepared for FAIR. The HEDM Phase-0 research effort will utilize the existing and enhanced GSI infrastructure of the SIS-18 synchrotron coupled with the PHELIX laser. The FAIR experimental program, presently scheduled to begin in 2025, will commence the use of the SIS-100 synchrotron coupled with new experimental and diagnostic infrastructure to realize the envisaged unique HEDM research program.

Permalink: https://www.hzdr.de/publications/Publ-29849
Publ.-Id: 29849


Combining trace element measurements with analytical uncertainties for a better characterization of plant geochemistry

Pospiech, S.; van den Boogaart, K. G.; Tolosana Delgado, R.; Wiebke, F.

Trace element analysis in plants is often subject to a high measurement uncertainty and accordingly the variability of the geochemical composition of trace elements in plants is – especially close to the detection limit - very high. In this contribution we propose a method to estimate models respecting the uncertainty and capable of treating values below and around the detection limit. We suggest to use all measurement signals, but report it alongside with the individual uncertainties for each value. The standard descriptive and statistical analysis mainly ignores these uncertainties by simply reporting if a signal value is below the detection limit (BDL) or above. BDL-values are either ignored or replaced by an arbitrary small value. In both cases this can substantially distort the analysis. Our methodology could substantially reduce this bias.
In order to take into account the constraints of concentration data we use methods of compositional data analysis, i.e. represent population by their compositional expectation, typically represented in an log-ratio transform. The uncertainties are incorporated in statistical methods by estimating the reported value not by a simple mean, but by an estimation procedure using the model assumption that a signal observed in the geochemical analysis has two components of variability: i) A population spread that could e.g. be modeled by a compositional distribution, and ii) a signal variability to be modeled according to the measurement instrument, typically assuming additive normal or Poisson errors and calibration errors. The parameters for the model of the signal variability are estimated from blind values, duplicate analysis as well as precision and accuracy of repeatedly measured reference samples.
We will present the change of results produced by the methodology over a standard approach with reporting BDL-values by demonstrating the applicability of the methodology with simulated data and a dataset of rye, ryegrass, faba bean, triticale and amaranth from two agricultural test sites in Germany. All samples had been treated by a four-acid digestion and analyzed by ICP-MS and ICP-OES.

Keywords: plant geochemistry; compositional data; uncertainty; analytics; ICP-MS; ICP-OES; Bayesian statistics

  • Open Access Logo Poster
    Goldschmidt Conference, 18.-23.08.2019, Barcelona, Spain

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Permalink: https://www.hzdr.de/publications/Publ-29847
Publ.-Id: 29847


Microresonator-integrated magnetic tunnel junctions allowing for thermal gradient sign reversal designed using COMSOL simulations

Cansever, H.; Lindner, J.; Huebner, T.; Niesen, A.; Reiss, G.; Fassbender, J.; Deac, A. M.

In magnetic tunnel junctions (MTJs), it was theoretically predicted that magnetization dynamics can be induced by thermal gradients via thermal-spin transfer torques (T-STTs), similar to STTs induced by applied voltages[1]. We recently proposed an approach based on microresonators (µR) in order to detect T-STT terms acting on the free layer of an MTJ device by means of investigating the ferromagnetic response of an MTJ exposed to a cw laser in open-circuit conditions. The linewidth of the ferromagnetic signal is modified by the damping-like torque induced by thermal gradient, while the frequency is subject to changes induced by the field-like torque[2]. Here, we used COMSOL simulations to determine the temperature profile of Co2FeAl/MgO/CoFeB MTJs, when the MR structure is considered, see Fig 1. In this design, the structure is defined with laterally larger Co2FeAl (CFA) layer below CoFeB (CFB) layer. This allows for the laser beam to be focused on the CFA layer surface, in order to heat the bottom electrode of the MTJ rather than the top, as commonly investigated[3-6]. The temperature of both layers and temperature differences (ΔT) as a function of lateral width are shown in Fig 2. The temperature on the CFA layer decreases laterally about 25K towards to center of the structure and yields a ΔT over the barrier of about 680mK, if a gold pad is placed on the CFA layer, in the position where the laser is shined on (Fig 2). Without the gold pad and leaving the MgO on the CFA unpatterned, the ΔT over the barrier is reduced almost by factor of 2, and is estimated to be around 320mK and 270mK respectively. When both layers have gold contacts, ΔT drops to 20mK (Fig 2). Consequently, the magnitude and the sign of ΔT over the barrier can be engineered by appropriately designing the design of the device, which would allow for T-STTs induced by thermal gradients of different sign to be investigated experimentally in a single MTJ.

*Figure 1 2D sketch of an MTJ structure considered for COMSOL modelling, where the loop of µR was taken into account and only the bottom layer is exposed to the laser.

*Figure 2 Temperature profile of the MTJ versus lateral size, ΔT dependence on designed structure.
References
[1] Jia X, Xia K and Bauer G E W 2011 Phys. Rev. Lett.107 176603
[2] H. Cansever, R. Narkowicz, K. Lenz, C. Fowley, L. Ramasubramanian, O. Yildirim, A. Niesen, T. Huebner, G. Reiss, J. Lindner, J. Fassbender, A. M. Deac, 2018 J. Phys. D: Appl. Phys. 51 22400
[3] N. Liebing, S. Serrano-Guisan, K. Rott, G. Reiss, J. Langer, B. Ocker, H. W. Schumacher, 2011, Phys. Rev. Lett. 107, 177201.
[4] J. C. Leutenantsmeyer, M. Walter, V. Zbarsky, M. Münzenberg, R. Gareev, K. Rott, A. Thomas, G. Reiss, P. Peretzki, H. Schuhmann, M. Seibt, M. Czerner, C. Heiliger, 2013, Spin 3, 1350002.
[5] A. Boehnke, M. Milnikel, M. Ehe, C. Franz, V. Zbarsky, M. Czerner, K. Rott, A. Thomas, C. Heiliger, G. Reiss, M. Münzenberg, 2015, Sci. Rep. 5, 8945.
[6] H. Cansever, J. Lindner, T. Huebner, A. Niesen, G. Reiss, J. Fassbender, A. M. Deac, 2019, IEEE Trans.Magn. 51(17) Early Access

Keywords: COMSOL; thermal spin-transfer torque; magnetic tunnel junction; microresonator

  • Lecture (Conference)
    Annual Conference on Magnetism and Magnetic Materials, MMM Las Vegas 2019, 04.-08.11.2019, Las Vegas, USA

Permalink: https://www.hzdr.de/publications/Publ-29846
Publ.-Id: 29846


Spectral Random Masking für PIV in Mehrphasenströmung

Anders, S.; Noto, D.; Eckert, S.

Im vorliegenden Beitrag wird eine neuartige Maskierungsmethode für die Particle Image Velocimetry (PIV) von Mehrphasenströmungen vorgestellt. Mit diesem neuen Ansatz können Geschwindigkeitsfelder einer unmaskierten Partikelfraktion (z. B. PIV-Tracer) unabhängig von der Bewegung einer zweiten, maskierten Partikel-Fraktion (z. B. Blasen oder Feststoffpartikel) bestimmt werden.
Ausgehend von einer segmentierten Bilderserie in welcher die verschiedenen Partikelfraktionen für alle Einzelbilder detektiert wurden, werden verschiedene Maskierungsverfahren diskutiert. Hierbei werden die Probleme, welche durch Standardverfahren für den Fall dynamischer Maskierung unter realen Belichtungsbedingungen entstehen besonders hervorgehoben. Als entsprechende Lösung stellen wir unseren Ansatz des Spectral Random Masking (vgl. Anders et al. 2019) vor, bei welchem maskierte Bildbereiche durch spektral angepasste, zufällige Intensitätsverteilungen ersetzt werden. Damit sollen die maskierten Bereiche für eine anschließende PIV-Analyse “unsichtbar” gemacht werden. Die Vorteile dieser Methode gegenüber konventionellen Maskierungsverfahren werden anhand eines Modellexperimentes dargestellt, bei welchem wässrige Ammonium-Chlorid Lösungen (NH₄Cl(aq)) durch Unterkühlung erstarrt werden. Dabei treten unter anderem verschiedene Konvektionsströmungen zeitgleich mit kolumnarer und äquiaxialer Kristallisation von NH₄Cl auf.

Keywords: Bild Segmentierung; dynamische Bildmaskierung; Mehrphasenströmung; Particle Image Velocimetry

  • Open Access Logo Contribution to proceedings
    Experimentelle Strömungsmechanik, 27. Fachtagung, 03.-05.09.2019, Erlangen, Deutschland
    Spectral Random Masking für PIV in Mehrphasenströmung, 978-3-9816764-6-4, 20.1-20.7
  • Lecture (Conference)
    Experimentelle Strömungsmechanik, 27. Fachtagung, 03.-05.09.2019, Erlangen, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-29844
Publ.-Id: 29844


Comparative Study of Monosalen Complexes with Tetravalent Actinides

Radoske, T.

Two series of tetravalent actinide complexes with the salen ligand were synthesized. The coordination sphere supports two labile positions for small neutral solvent molecules, which were filled with either methanol or acetonitrile molecules. Solid state characterization reveals additional interactions of U(IV) and Np(IV) with the organic ligands.

  • Poster
    Migration 2019, 15.-20.09.2019, Kyoto, Japan

Permalink: https://www.hzdr.de/publications/Publ-29842
Publ.-Id: 29842


Tetravalent Actinide N-Donor Affinity in Monosalen Complexes

Radoske, T.

Complexes with a range of differently substituted pyridines were synthesized using tetravalent actinides. The affinity of actinides for N-donors is discussed.

  • Lecture (others)
    FENABIUM Projekttreffen, 28.06.2019, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29841
Publ.-Id: 29841


Tetravalent Actinide Complexes with Schiff bases: Comparison with Isostructural Transition Metal and 4f Element Compounds

Radoske, T.

Isostructural complex series with tetravalent actinides were characterized and results are discussed for observable trends.

  • Lecture (others)
    FENABIUM Projekttreffen, 27.02.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29840
Publ.-Id: 29840


Amidinates as Versatile Ligands for Tetravalent Actinides

Schöne, S.; März, J.; Kaden, P.

A summary of work based on the synthesis and characterization of tetravalent actinide amidinates is given. Structural features are compared in solid and in solution phase. Comprehensive quantum chemical calculations support the findings.

  • Lecture (others)
    FENABIUM Projekttreffen, 28.06.2019, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29839
Publ.-Id: 29839


Relative Stability of Actinide(IV) Bissalen Complexes

Radoske, T.; Schöne, S.; Kloditz, R.; März, J.; Stumpf, T.; Ikeda-Ohno, A.

Schiff bases of salen-type have a wide range of applications and have proven to be a versatile ligand system for the investigation of complexation behavior. In particular, due to its hetero N/O-donor coordination properties, the salen ligands are often considered as a simplified analog of naturally-occuring organic ligands, which have potential implications for the migration behavior of radionuclides under geochemical conditions We have investigated the complexation behavior of salen ligands (L, H2salen = N,N’-bis(salicyliden)ethylenediamine) towards tetravalent metal cations and synthesized a series of complexes of tetravalent actinides (Th, U, Np, and Pu) as well as analogous tetravalent metals (Zr, Ce, and Hf). In all cases, the ligand forms bissalen ML2 complexes (M = metal). When the ML2 compound is treated with an equimolar amount of the metal tetrachloride, some metals also form M:L = 1:1 complexes with additional two Cl- in the primary coordination shell to form MLCl2. Based on this observation, we assume a trilateral equilibrium between the starting materials of metal tetrachlorides, the 1:1, and the 1:2 complex (Scheme 1), being similar to the study by Calderazzo et al.[1] This equilibrium holds even if ML2 is insoluble in the reaction medium and, therefore, we can apply the exchange reactions to determine the relative stability of the An(IV)-bissalen complexes when more than one types of metal are used. The relative stability of the complexes can then be directly compared to the results from quantum chemical calculations based on DFT. Hence, this study aims to understand the reaction mechanism and stability of salen complexes with a series of tetravalent metals, in particular tetravalent actinides (An(IV)).

  • Lecture (Conference)
    Fachtagung Nuklearchemie, 25.-27.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29838
Publ.-Id: 29838


Tetravalent Actinide and Transition Metal Amidinates – Trends and Perspectives

Schöne, S.

A series of tetravalent actinide amidinates with chiral (S)-HPEBA ligands is presented. The complexes are structurally characterized in solid state and in solution. Further reactivity is proved by reduction to trivalent homoleptic complexes.

  • Lecture (others)
    Challenges in f-element chemistry - Bilaterales Meeting HZDR/KIT, 10.01.2019, Karlsruhe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29837
Publ.-Id: 29837


Amidinates – Versatile Ligands for Tetravalent Actinides

Schöne, S.; Kloditz, R.; März, J.; Kaden, P.; Patzschke, M.; Roesky, P. W.; Stumpf, T.

Amidinates, a group of heteroallylic nitrogen donor ligands of type [RC(NR‘)2]–, have been used in a widespread manner in coordination chemistry and organometallics. They usually coordinate in a N,N’-bidendate mode to almost all metals in the periodic table including lanthanides and early actinides. The steric and electronic properties can be easily tuned by varying the substituents R and R’ to make them a valuable class of spectator ligands.
We have expanded the rich chemistry of amidinates to the tetravalent transuranic elements Np and Pu and compared the results to the earlier actinides Th and U and other tetravalent analogues. The focus of our investigations lies in the comprehensive characterization of An(IV) complexes with amidinates, both in the solid state and in solution. A comparison within the series enables us to perform a detailed structural analysis, which is complemented by high-level quantum chemical calculations to gain deeper insight into the bonding properties of tetravalent actinides (An(IV)).
Several An(IV) amidinate complexes have been synthesized including a series of chiral complexes using the chiral benzamidine, (S,S)-N,N‘-Bis-(1-phenylethyl)-benzamidine ((S)-HPEBA) [1]. We obtained the first enantiopure amidinate complexes [AnIVCl((S)-PEBA)3] (An = Th, U, and Np) as well as the analogous Ce(IV) compound, a chemical analog of An(IV). The tris-amidinate complexes have been structurally characterized in solid state and in solution showing a comparable complex geometry.
The presence of one chloro ligand in addition to three stabilizing amidinate ligands in the An coordination sphere points to complex reactivity. This could indeed be demonstrated by reduction to homoleptic trivalent actinide amidinates [An((S)-PEBA)3] (An = U, Np) as well as halogen exchange with pseudo-halogenides (i.e. N3–).

  • Lecture (Conference)
    GdCh Fachgruppentagung Nuklearchemie, 25.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29836
Publ.-Id: 29836


La–Sr–Mn–Co–O Films for High Pulsed Magnetic Field Measurements at Cryogenic Temperatures

Rudokas, V.; Zurauskiene, N.; Lukose, R.; Kersulis, S.; Stankevic, V.; Pavilonis, D.; Balevicius, S.; Plausinaitiene, V.; Vagner, M.; Skapas, M.; Arsenijevic, S.

The magnetoresistance of nanostructured La1−xSrx(Mn1−yCoy)zO3±δ (La–Sr–Mn–Co–O) films with substitution of Co for Mn with amount of Co/(La + Sr) = 0.12 and different Mn excess Mn/(La + Sr) = 1.05, 1.07, nd 1.11 was investigated at temperatures of 4–230 K in pulsed magnetic fields up to 60 T. It was found that the manganite–cobaltite films exhibit larger magnetoresistance in comparison with manganite films without Co doping. The largest magnetoresistance values and sensitivity to the magnetic field are obtained for La–Sr–Mn–Co–O films having Mn Content close to the stoichiometric ratio for manganites: Mn/(La + Sr) = 1.05. It was found that magnetoresistance at high fields (20–60 T) has a minimum at (50–80 K) and increases with the decrease of temperature. The possibility to use these films for magnetic field measurements at cryogenic temperatures is demonstrated.

Permalink: https://www.hzdr.de/publications/Publ-29835
Publ.-Id: 29835


Microorganisms for biological remediation of uranium contaminated sites – a microscopic and spectroscopic approach

Krawczyk-Bärsch, E.; Gerber, U.; Müller, K.; Rossberg, A.; Merroun, M. L.

Environmental pollution by metals and radionuclides is one of the biggest challenges. For remediation of contaminated environments after activities such as uranium mining and uranium processing, microorganisms could be important due to their ability to immobilize radionuclides and heavy metals. Bioremediation strategies can be improved by a better understanding of binding mechanisms on the molecular level. Therefore, we applied uranium interaction experiments with Acidovorax facilis, an aerobic, Gram-negative Betaproteobacteria, which is commonly found in soils but also in the mine water of uranium mines. For spectroscopic and microscopic studies, kinetic uranium(VI) sorption experiments were performed under aerobic conditions with an Acidovorax facilis strain by adjusting an initial uranium(VI) concentration to 0.1 mM to the batch culture at a neutral pH range. A high-resolution image of the cellular localization of uranium by A. facilis was achieved by using electron microscopy (STEM/HAADF). The elemental distribution analysis of phosphorus and uranium clearly indicates that uranium is entirely present in the cell membrane and only with minor amounts in the poly-phosphate granules (PPGs) during the first hour of incubation (s. Fig.1). By cryo-Time-resolved laser-induced fluorescence spectroscopy (cryo-TRLFS) studies it was shown that the local coordination of uranium species associated with the cells depends upon time contact. Uranium is bound mainly to phosphate groups of lipopolysaccharide [1] at the outer membrane within the first hour. And, that both, phosphoryl and carboxyl functionality groups of LPS and peptidoglycan of A. facilis cells may effectuate the removal of high uranium amounts from solution at 24–48 h of incubation. These results support those obtained by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS), where a relative short average U-Oeq bond length of 2.35 Å was observed for the uranium(VI) interaction with lipopolysaccharide indicating a binding of the uranium(VI) via organic phosphate groups in a monodentate fashion. Our results clearly demonstrate that A. facilis may play an important role in predicting the transport behaviour of uranium in the environment and that the results will contribute to the improvement of bioremediation methods of uranium-contaminated sites.

Keywords: uranium; sorption; Acidovorax facilis; STEM; EXAFS

  • Lecture (Conference)
    3rd International Caparica Conference on Polutant Toxic Ions and Molecules, 04.-07.11.2019, Costa da Caparica, Portugal

Permalink: https://www.hzdr.de/publications/Publ-29833
Publ.-Id: 29833


Superconductivity of Organic Charge-Transfer Salts

Wosnitza, J.

Forty years after the discovery of the first organic superconductor, the nature of the superconducting state in these materials is still not fully understood. Here, I present an overview on the historical developments and current knowledge on this topic for the quasi-one- and quasi-two-dimensional (2D) organic charge-transfer salts. Thereby, I focus on the prototype materials based on the donor molecules tetramethyltetraselenafulvalene (TMTSF) and bisethylenedithio-tetrathiafulvalene (BEDT-TTF or ET for short). 2D organic superconductors based on the latter molecule are found to show Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) states at high magnetic fields and low temperatures. Thermodynamic and nuclear magnetic resonance data give robust evidence for the existence of this FFLO state with modulated order parameter.

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Permalink: https://www.hzdr.de/publications/Publ-29831
Publ.-Id: 29831


A numerical simulator for modeling the coupling processes of subsurface fluid flow and reactive transport processes in fractured carbonate rocks

Yuan, T.; Wei, C.; Zhang, C.-S.; Qin, G.

Water–rock interactions can alter rock properties through chemical reactions during subsurface transport processes like geological CO2 sequestration (GCS), matrix acidizing, and waterflooding in carbonate formations. Dynamic changes in rock properties cause a failure of waterflooding and GCS and could also dramatically affect the efficiency of the acidizing. Efficient numerical simulations are thus essential to the optimized design of those subsurface processes. In this paper, we develop a three-dimensional (3D) numerical model for simulating the coupled processes of fluid flow and chemical reactions in fractured carbonate formations. In the proposed model, we employ the Stokes–Brinkman equation for momentum balance, which is a single-domain formulation for modeling fluid flow in fractured porous media. We then couple the Stokes–Brinkman equation with reactive-transport equations. The model can be formulated to describe linear as well as radial flow. We employ a decoupling procedure that sequentially solves the Stokes–Brinkman equation and the reactive transport equations. Numerical experiments show that the proposed method can model the coupled processes of fluid flow, solute transport, chemical reactions, and alterations of rock properties in both linear and radial flow scenarios. The rock heterogeneity and the mineral volume fractions are two important factors that significantly affect the structure of conductive channels.

Keywords: reactive-transport; fracture evolution; mineral dissolution; fractured carbonate formations

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Permalink: https://www.hzdr.de/publications/Publ-29830
Publ.-Id: 29830


Population balance modelling of isothermal and non-isothermal bubbly flows

Liao, Y.

In bubbly flows, bubble size may vary with time and space as the result of coalescence and breakage, shrinkage and growth due to mass and/or heat transfer as well as other dynamic and transport processes occurring at the interface. One major task and challenge in modelling of bubbly flows is to reconstruct these processes and trace the change of local bubble size, since it is crucial in affecting the rate of all interfacial transfers. The population balance equation provides the basis for the description of the dynamics of particulate systems. It has become of great interest in a number of scientific disciplines or application fields. Different forms of the population balance models have been presented, and they all allow one to take into account above bubble size change mechanisms through so-called kernels. Nevertheless, continuous efforts are needed in developing, calibrating and validating the kernels. In addition, reliable and efficient solution of the population balance equation is not trivial. The presentation will focus on the class method of population balance modelling, its coupling with the two-fluid-model and application to adiabatic air-water, condensing and evaporating steam-water bubbly flows as well as recent progresses in developing coalescence and breakup kernels.

Keywords: Bubbly flow; Coalescence and breakup; CFD-PBM coupled method; Phase change; Population balance model

  • Invited lecture (Conferences)
    NSFC-DEG International Workshop on Three-Phase Flow Modelling and Simulation, 23.-25.10.2019, Ningbo, China

Permalink: https://www.hzdr.de/publications/Publ-29825
Publ.-Id: 29825


The intensive DT neutron generator of TU Dresden

Klix, A.; Döring, T.; Domula, A.; Zuber, K.

TU Dresden operates an accelerator-based intensive DT neutron generator. Experimental activities comprise investigation into material activation and decay, neutron and photon transport in matter and R&D work on radiation detectors for harsh environments. The intense DT neutron generator is capable to produce a maximum of 1012 n/s. The neutron source is a solid-type water-cooled tritium target based on a titanium matrix on a copper carrier. The neutron yield at a typical deuteron beam current of 1 mA is of the order of 1011 n/s in 4Π. A pneumatic sample transport system is available for short-time irradiations and connected to wo high-purity germanium detector spectrometers for the measurement of induced activities. The overall design of the experimental hall with the neutron generator allows a flexible setup of experiments including the possibility of investigating larger structures and cooled samples or samples at high temperatures.

Permalink: https://www.hzdr.de/publications/Publ-29823
Publ.-Id: 29823


ATM controls DNA repair and mitochondria transfer between neighboring cells

Jin, S.; Cordes, N.

Intercellular communication is essential for multicellular tissue vitality and homeostasis. We show that healthy cells message protective signals through direct cell–cell connections to adjacent DNA–damaged cells in a microtubule–dependent manner. In DNA–damaged cells, mitochondria restoration is facilitated by fusion with undamaged mitochondria from healthy cells and their DNA damage repair is optimized in presence of healthy cells. Both, mitochondria transfer and intercellular signaling for an enhanced DNA damage response are critically regulated by the activity of the DNA repair protein ataxia telangiectasia mutated (ATM). These healthy–to–damaged prosurvival processes sustain normal tissue integrity and may be exploitable for overcoming resistance to therapy in diseases such as cancer.

Keywords: Cell–cell communication; genotoxic stress; mitochondria exchange; DNA damage repair; ataxia telangiectasia mutated (ATM)

Permalink: https://www.hzdr.de/publications/Publ-29822
Publ.-Id: 29822


Studies on Flat Sandwich-type Self-Powered Detectors for Flux Measurements in ITER Test Blanket Modules

Raj, P.; Angelone, M.; Döring, T.; Eberhardt, K.; Fischer, U.; Klix, A.; Schwengner, R.

Neutron and gamma flux measurements in designated positions in the test blanket modules (TBM) of ITER will be important tasks during ITER's campaigns. As part of the ongoing task on development of nuclear instrumentation for application in European ITER TBMs, experimental investigations on self-powered detectors (SPD) are undertaken. This paper reports the findings of neutron and photon irradiation tests performed with a test SPD in flat sandwich-like geometry. Whereas both neutrons and gammas can be detected with appropriate optimization of geometries, materials and sizes of the components, the present sandwich-like design is more sensitive to gammas than 14 MeV neutrons. Range of SPD current signals achievable under TBM conditions are predicted based on the SPD sensitivities measured in this work.

Permalink: https://www.hzdr.de/publications/Publ-29821
Publ.-Id: 29821


Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature

Obraztsova, O.; Ottaviani, L.; Klix, A.; Döring, T.; Palais, O.; Lyoussi, A.

Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C) and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV), wide band gap energy (3.27 eV) and high thermal conductivity (4.9 W/cm·K), SiC can operate in harsh environment (high temperature, high pressure and high radiation level) without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV), higher threshold displacement energy (40-50 eV) and thermal conductivity (22 W/cm·K), which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD) diamond detectors irradiated with 14 MeV neutrons at room temperature.

Permalink: https://www.hzdr.de/publications/Publ-29820
Publ.-Id: 29820


Comparing the Response of a SiC and a sCVD Diamond Detectors to 14-MeV Neutron Radiation

Obraztsova, O.; Ottaviani, L.; Klix, A.; Döring, T.; Palais, O.; Lyoussi, A.

Radiation detectors based on wide-bandgap semiconductors have received considerable attention in many applications such as the experiments in material testing reactors, high energy particle physics experiments, or fusion facilities for plasma diagnostics. In this paper, we compared a 4H-silicon-carbide (SiC)-based detector with a single crystal chemical vapor deposited (sCVD) diamond-based detector for 14-MeV neutron detection. For this purpose, the deuterium- tritium neutron generator of Technical University of Dresden with 14-MeV neutron output up to 10 11 n/sin 4π has been used. In this paper, we interpret the results of our first measurements with both 4H-SiC and sCVD diamond detectors at low neutron flux of 9.4 × 10 6 n/(cm 2 · s) and at room temperature.

Permalink: https://www.hzdr.de/publications/Publ-29819
Publ.-Id: 29819


Neutron flux measurements on a mock-up of a storage cask for high-level nuclear waste using 2.5 MeV neutrons

Saurí Suárez, H.; Becker, F.; Klix, A.; Pang, B.; Döring, T.

To store and dispose spent nuclear fuel, shielding casks are employed to reduce the emitted radiation. To evaluate the exposure of employees handling such casks, Monte Carlo radiation transport codes can be employed. Nevertheless, to assess the reliability of these codes and nuclear data, experimental checks are required. In this study, a neutron generator (NG) producing neutrons of 2.5 MeV was employed to simulate neutrons produced in spent nuclear fuel. Different configurations of shielding layers of steel and polyethylene were positioned between the target of the NG and a NE-213 detector. The results of the measurements of neutron and γ radiation and the corresponding simulations with the code MCNP6 are presented. Details of the experimental set-up as well as neutron and photon flux spectra are provided as reference points for such NG investigations with shielding structures.

Permalink: https://www.hzdr.de/publications/Publ-29818
Publ.-Id: 29818


Radiosynthesis and Biological Investigation of a Novel Fluorine-18 Labeled Benzoimidazotriazine- based Radioligand for Imaging of Phosphodiesterase 2A with Positron Emission Tomography

Ritawidya, R.; Wenzel, B.; Teodoro, R.; Toussaint, M.; Kranz, M.; Deuther-Conrad, W.; Dukic-Stefanovic, S.; Ludwig, F.-A.; Scheunemann, M.; Brust, P.

A specific radioligand for imaging of cyclic nucleotide phosphodiesterase 2A (PDE2A) via positron emission tomography (PET) would be helpful for research on the physiology and disease-related changes in the expression of this enzyme in the brain. In this report, the radiosynthesis of a novel PDE2A radioligand and the subsequent biological evaluation is described. Our prospective compound 1-(2-chloro-5-methoxy phenyl)-8-(2-fluoropyridin-4-yl)-3- methylbenzo[e]imidazo[5,1-c][1,2,4]triazine, BIT1 (IC50 PDE2A = 3.33 nM; 16-fold selectivity over PDE10A) was fluorine-18 labeled via aromatic nucleophilic substitution of the corresponding nitro precursor using the K[18F]F‐K2.2.2‐carbonate complex system. The new radioligand [18F]BIT1 was obtained with a high radiochemical yield (54 ± 2%, n = 3), a high radiochemical purity (≥99%) and high molar activities (155‐175 GBq/μmol, n = 3). In vitro autoradiography on pig brain cryosections exhibited an heterogenous spatial distribution of [18F]BIT1 corresponding to the known pattern of expression of PDE2A. The investigation of in vivo metabolism of [18F]BIT1 in mouse revealed a sufficient metabolic stability. PET studies in mouse exhibited a moderate brain uptake of [18F]BIT1 with a maximum standardized uptake value of ~0.7 at 5 minutes p.i. However, in vivo blocking studies revealed a non-target specific binding of [18F]BIT1. Therefore, further structural modifications are needed to improve target selectivity.

Keywords: cyclic nucleotide phosphodiesterase; PDE2A radioligand; nitro-precursor; fluorine-18; in vitro autoradiography; PET imaging

Permalink: https://www.hzdr.de/publications/Publ-29817
Publ.-Id: 29817


Ferromagnetic resonance detection in magnetic single objects via a novel microresonator and microantenna approach

Cansever, H.; Lenz, K.; Narkowicz, R.; Kowalska, E.; Faßbender, J.; Deac, A. M.; Lindner, J.

Ferromagnetic resonance has been commonly used as a spectroscopic technique investigating the fundamental properties of ferromagnetic materials, such as magnetization, g-factor, magnetic anisotropy and damping (relaxation) parameters [1-4].Conventionally, an FMR spectrometer is operating at a fixed microwave frequency to detect the microwave absorption of the magnetic object by sweeping an external magnetic field through the resonance. The sensitivity of this weak absorption process is typically enhanced by using a microwave bridge setup. However, for a reliable quantification of key magnetic parameters like the g-factor or spin relaxation times, the measurements should be performed within a broad range of frequencies. This is achieved by broadband FMR spectrometers which employ vector network analyzers (VNA) that detect the microwave transmission or reflection parameters of the sample [5-6]. However, neither conventional cavities nor broadband FMR spectrometers are able to detect signals of micro/nano size samples due to the tiny sample volume. To achieve optimal sensitivity for small objects, planar microresonators were introduced for electron paramagnetic resonance (EPR) experiments [7]. Microresonators have been used to investigate magnetization dynamics of magnetic object to understand uniform and spin wave modes [8], as well as the spin-Seebeck effect in magnetic tunnel junctions [9.] The microresonator approach allows producing rf magnetic fields homogeneously concentrated inside a metallic loop, thereby increasing the filling factor of the resonator. Here, we explain the novel microesonator approach in detail and introduce moreover a microantenna approach which allows to perform experiments in the range of 8-18 GHz employing a co-planar layout. We investigate magnetization dynamics within Permalloy (Ni80Fe20) wires by using both, microresonator and microantenna approach.

[1] P. E. Wigen, C.F. Kooi, M. R Shanaberger, T. R. Rosing, Phys. Rev. Lett. 9, 206, 1962.
[2] P. E. Wigen, Z. Zhang, Braz. J. Phys. 22, 267, 1992.
[3] M. Farle, “Rep. Prog. Phys. 61, 755, 1998.
[4] J. R. Fermin, A. Azevedo, F. M. Aguiar, B. Li, S. M. J. Rezende, Appl. Phys. 85, 7316, 1999.
[5] M. Vroubel, Y. Zhuang, B. Rejaei, J. N. Burghartz, J. Appl. Phys. 99, 08P506, 2006.
[6] C. Nistor, K. Sun, Z. Wang, M. Wu, C. Mathieu, M. Hadley Appl. Phys. Lett. 95, 012504, 2009.
[7] R. Narkowicz, D. Suter, I. Niemeyer, Rev. Sci. Instrum. 79, 084702, 2008.
[8] A Banholzer, R Narkowicz, C Hassel, R Meckenstock, S Stienen, O Posth, D Suter, M Farle, J Lindner, Nanotechnology, 22, 295713, 2011.
[9] H. Cansever, R. Narkowicz, K. Lenz, C. Fowley, L. Ramasubramanian, O. Yildirim, A. Niesen, T. Huebner, G. Reiss, J. Lindner, J. Fassbender, A. M. Deac, J. Phys. D: Appl. Phys. 51, 22400, 2018.

Keywords: ferromagnetic resonance; microresonator; microantenna

  • Invited lecture (Conferences)
    9th APMAS 2019 - International Advances in Applied Physics & Materials Science Congress & Exhibition, 20.-28.10.2019, Fethiye- Mugla, Turkey

Permalink: https://www.hzdr.de/publications/Publ-29814
Publ.-Id: 29814


The quest for AMS of ¹⁸²Hf - why poor gas gives pure beams

Martschini, M.; Lachner, J.; Merchel, S.; Priller, A.; Steier, P.; Wallner, A.; Wieser, A.; Golser, R.

The trace isotope ¹⁸²Hf (T1/2 = 8.9 Ma) is of high astrophysical interest as its potential abundance in environmental archives would provide rare insight into heavy element nucleosynthesis in recent r-process events in the vicinity of our planet. Despite substantial efforts, however, it could not be measured at its natural abundance level with conventional AMS so far due to strong isobaric interference from stable ¹⁸²W.
The new Ion Laser InterAction Mass Spectrometry (ILIAMS) technique at VERA tackles the problem of elemental selectivity in AMS with a novel approach. It achieves near-complete suppression of isobar contaminants via selective laser photodetachment of decelerated anion beams in a gas-filled radio frequency quadrupole (RFQ). The technique exploits differences in electron affinities (EA) within elemental or molecular isobaric systems neutralizing anions with EAs smaller than the photon energy. Alternatively, these differences in EA can also result in anion separation via chemical reactions with the buffer gas.
In this contribution, we present first results with this approach on AMS-detection of ¹⁸²Hf. With He +O₂ mixtures as buffer gas in the RFQ, suppression of ¹⁸²WF₅- vs ¹⁸⁰HfF₅- by >10⁵ has been demonstrated. Mass analysis of the ejected anion beam identified the formation of oxyfluorides as an important reaction channel.
The overall Hf-detection effciency at VERA presently is 1.4 x 10-3 and the W-corrected blank value is ¹⁸²Hf/¹⁸⁰Hf = (3.4 + 2.1) x 10-14. In addition, a survey of several sputter materials for highest negative ion yields of HfF₅- has been conducted.

Keywords: AMS; Laser; astrophysics

Permalink: https://www.hzdr.de/publications/Publ-29813
Publ.-Id: 29813


Enhanced Fiberoptical Dosimetry through Time-resolved Single Photon Detection in Proton Fields

Kormoll, T.; van der Graaf, E. R.; van Goethem, M. J.; Gonzalez Torres, M. J.; Lachmann, P.; Pausch, G.; Majchrowski, A.; Makarevich, K.; Weinberger, D.; Zuber, K.; Teichmann, T.

Fiberoptical dosimetry uses compact solid state radioluminescence probes coupled to long to flexible light guides. Such probes are convenient, robust small. Especially in the presence of magnetic fields, such optical probes can be advantageous over the transmission of a current signal, e.g. from a photodiode directly attached to a scintillator. These characteristics make such probes attractive for emerging medical applications like particle therapy in combination with MRI. Challenging remains the discrimination of so called “stem” effect light which is generated in the fiber from the actual signal light from the probe. In this work, fiber probes attached to a single photon sensor have been exposed to a proton beam from a proton cyclotron in order to study the feasibility of fiber dosimetry in therapeutic proton fields. Probes with different luminophores have been placed in the beam within a PMMA holder of 1 cm thickness. The light guide was coupled to a Hamamatsu H12386-210 single photon detector. For timing information, the pulse was sampled and analyzed with a Serious Dynamics DAQ125 board. This is a 16 bit sampling ADC board which was running synchronous to the cyclotron. An interpolated time stamp with a resolution of 30 ps was calculated in realtime. It could be shown that a time resolved measurement of the single luminescence photons exhibits the time structure of the luminophore, e.g. the long decay which appears uncorrelated of beryllium oxide or lithium tetraborate or the decay in the ns range of plastic scintillators. Blank fiber measurements exhibit the microbunch width of the accelerator. Thereby, stem identification in therapeutic hadron fields is possible without further reference measurements. Additionally, the issue of quenching of many luminophores in hadron fields can be addressed. A further beamtime at the AGOR cyclotron in Groningen will be conducted in May 2019 and recent results will be presented at the conference.

Keywords: Fiberoptical dosimetry; radioluminescence; magnetic fields; scintillator; MRI; proton beam; therapeutic proton fields; timing; ADC; beryllium oxide; lithium tetraborate; therapeutic hadron fields

  • Contribution to proceedings
    2019 IEEE Nuclear Science Symposium & Medical Imaging Conference, 26.10.-02.11.2019, Manchester, UK
    Proceedings of the 2019 IEEE Nuclear Science Symposium & Medical Imaging Conference

Permalink: https://www.hzdr.de/publications/Publ-29812
Publ.-Id: 29812


Crystal size versus paddle wheel deformability: selective gated adsorption transitions of the switchable metal–organic frameworks DUT-8(Co) and DUT-8(Ni)

Ehrling, S.; Senkovska, I.; Bon, V.; Evans, J. D.; Petkov, P.; Krupskaya, Y.; Kataev, V.; Wulf, T.; Krylov, A.; Vtyurin, A.; Krylova, S.; Adichtchev, S.; Slyusareva, E.; Weiss, M. S.; Büchner, B.; Heine, T.; Kaskel, S.

Switchable pillared layer metal–organic frameworks M₂(2,6-ndc)₂(dabco) (DUT-8(M), M = Ni, Co, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]octane, DUT – Dresden University of Technology) were synthesised in two different crystallite size regimes to produce particles up to 300 μm and smaller particles around 0.1 μm, respectively. The textural properties and adsorption-induced switchability of the materials, obtained from both syntheses, were studied by physisorption of N2 at 77 K, CO2 at 195 K and n-butane at 273 K, revealing pronounced differences in adsorption behavior for Ni and Co analogues. While the smaller nano-sized particles (50–200 nm) are rigid and show no gating transitions confirming the importance of crystallite size, the large particles show pronounced switchability with characteristic differences for the two metals resulting in distinct recognition effects for various gases and vapours. Adsorption of various vapours demonstrates consistently a higher energetic barrier for the “gate opening” of DUT-8(Co) in contrast to DUT-8(Ni), as the “gate opening” pressure for Co based material is shifted to a higher value for adsorption of dichloromethane at 298 K. Evaluation of crystallographic data, obtained from single crystal and powder X-ray diffraction analysis, showed distinct geometric differences in the paddle wheel units of the respective MOFs. These differences are further disclosed by solid-state UV-vis, FT-IR and Raman spectroscopy. Magnetic properties of DUT-8(Co) and DUT-8(Ni) were investigated, indicating a high-spin state for both materials at room temperature. Density functional theory (DFT) simulations confirmed distinct energetic differences for Ni and Co analogues with a higher energetic penalty for the structural “gate opening” transformation for DUT-8(Co) compared to DUT-8(Ni) explaining the different flexibility behaviour of these isomorphous MOFs.

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Permalink: https://www.hzdr.de/publications/Publ-29811
Publ.-Id: 29811


Testing RPC Performance with Discharges Ignited by UV Laser Pulses: Precise measurement of gas parameters in approximately realistic RPC configurations

Fan, X.

This thesis is devoted in two associated topics: a unique laser facility for researches of gaseous detectors; the investigations of Resistive Plate Chamber (RPC) detectors and the measurement of gas parameters in a realistic condition of timing RPC.
A pulsed UV laser test facility has been assembled in HZDR. The focus of pico-second laser pulses is placed in a specific position in a gaseous detector sample to produce laser plasma, where free electrons are generated in ionizations with well defined number, micro-meter spatial accuracy in a volume of micro-meter scale. It provides a method, independent from accelerators, to make investigations with gaseous detectors in a laboratory.
Samples of RPC detectors are designed and assembled for experiments with the laser test facility. Methods are developed to acquire the waveforms of electron avalanches for different drift lengths and to obtain the key gas parameters: the effective Townsend coefficient and the electron drift velocity. We have succeeded in the direct measurement of gas parameters at the field strength of timing RPC under atmospheric pressure for the first time in experimental conditions.
The research has obtained different achievements. The laser test facility is proven to be qualified for the measurement of gas parameters, and has a potential to contribute to the eco-gas research for future RPC. The possible measurement range of electric field of gas parameter at atmospheric pressure is extended by a factor of two, from the range of trigger RPC to timing RPC. The results of experiments have revealed some fundamental mechanisms, which will extend the understanding of RPC performance and electron avalanche process.

Keywords: Laser; Resistive Plate Chamber; Electron Avalanche

  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-106 2019
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-29810
Publ.-Id: 29810


Comparison of Gas-Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

Putra, R. A.; Neumann-Kipping, M.; Schäfer, T.; Lucas, D.

The gas-liquid flow characteristics for the blade, the single and the double-helical swirl elements were numerically investigated and compared in this work. The Euler-Euler model assuming bi-modal bubble size distributions was used. The experiment conducted in a vertical pipe equipped with a static blade swirl element is used as the basis for the CFD simulations. In the experiment, the high-resolution gamma-ray computed tomography (HireCT) was used to measure the gas volume fractions at several planes within the blade swirl element. The resulting calculated profiles of the pressure, liquid and gas velocities, as well as the gas fraction, show a large influence of the swirl elements geometry. The evolution and the characteristic of the calculated gas/liquid phase distributions in different measurement planes are found to be unique for each type of swirl elements. A single gas core in the center of the pipe is observed from the simulation of the blade element while multiple cores are observed from the simulation of the single and double helix elements. The cross-sectional gas distribution downstream the single and double helical elements change drastically within a relatively short distance downstream the elements. In contrast, the single gas core downstream the blade element is more stable.

Keywords: Swirling flow; Multiphase flow; Inline separator; Static mixer; CFD simulation, Euler-Euler

Permalink: https://www.hzdr.de/publications/Publ-29809
Publ.-Id: 29809


Modular Digital Low Level Radio Frequency Control (LLRF) for CW Operation at ELBE

Zenker, K.

A digital LLRF control has been implemented at the CW linac ELBE at Helmholtz-Zentrum Dresden-Rossendorf. The system is based on the MicroTCA.4 standard and drives four superconducting TESLA cavities and two normal conducting buncher cavities. The system enables a higher flexibility of the field control, improved diagnostics and field stability compared to the analogue system which was used before. The presentation will give an overview on the design specification, detailed system structure, software architecture and latest performance test results.

  • Invited lecture (Conferences)
    19th International Conference on RF Superconductivity, 30.06.-05.07.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29805
Publ.-Id: 29805


ELBE and DALI at HZDR

Zenker, K.; Evtushenko, P.; Schwarz, A.; Kuntzsch, M.; Schneider, C.; Kovalev, S.

Facility status report for ELBE and TELBE

  • Invited lecture (Conferences)
    MT ARD ST3 Annual Meeting, 16.-18.10.2019, Darmstadt, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29803
Publ.-Id: 29803


Proximity effect in crystalline framework materials: stacking-induced functionality in MOFs and COFs

Kuc, A. B.; Springer, M.; Batra, K.; Juarez-Mosqueda, R.; Wöll, C.; Heine, T.

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) consist of molecular building blocks being stitched together by strong bonds. They are well known for their porosity, large surface area, and related properties. The electronic properties of most MOFs and COFs are the superposition of those of their constituting building blocks. If crystalline, however, solid-state phenomena can be observed, such as electrical conductivity, substantial dispersion of electronic bands, broadened absorption bands, formation of excimer states, mobile charge carriers, and indirect band gaps. These effects emerge often by the proximity effect caused by the van-der-Waals interactions between stacked aromatic building blocks. This Progress Report shows how functionality is imposed by this proximity effect, that is, by stacking aromatic molecules in such a way that extraordinary electronic and optoelectronic properties emerge in MOFs and COFs. After discussing the proximity effect in graphene-related materials, its importance for layered COFs and MOFs is shown. For MOFs with well-defined structure, the stacks of aromatic building blocks can be controlled via varying MOF topology, lattice constant, and by attaching steric control units. Finally, an overview of theoretical methods to predict and analyze these effects is given, before the layer- by-layer growth technique for well-ordered surface-mounted MOFs is summarized.

Permalink: https://www.hzdr.de/publications/Publ-29800
Publ.-Id: 29800


Morphology modification of Si nanopillars under ion irradiation at elevated temperatures: plastic deformation and controlled thinning to 10 nm

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

Si nanopillars of less than 50 nm diameter have been irradiated in a helium ion microscope with a focused Ne+ beam. The morphological changes due to ion beam irradiation at room temperature and elevated temperatures have been studied with the transmission electron microscope. We found that the shape changes of the nanopillars depend on irradiation-induced amorphization and thermally driven dynamic annealing. While at room temperature, the nanopillars evolve to a conical shape due to ion-induced plastic deformation and viscous flow of amorphized Si, simultaneous dynamic annealing during the irradiation at elevated temperatures prevents amorphization which is necessary for the viscous flow. Above the critical temperature of ion-induced amorphization, a steady decrease of the diameter was observed as a result of the dominating forward sputtering process through the nanopillar sidewalls. Under these conditions the nanopillars can be thinned down to a diameter of ∼10 nm in a well-controlled manner. A deeper understanding of the pillar thinning process has been achieved by a comparison of experimental results with 3D computer simulations based on the binary collision approximation.

Keywords: helium ion microscopy; Monte Carlo simulation; sub-10 nm fabrication; ion beam damage; amorphization

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Permalink: https://www.hzdr.de/publications/Publ-29799
Publ.-Id: 29799


Interaction of curium(III) with surface-layer proteins from Lysinibacillus sphaericus JG-A12

Moll, H.; Lehmann, F.; Raff, J.

Trivalent actinides such as Cm(III) are able to occupy natural Ca(II) binding sites in biological systems. For this investigation, we studied the formation of aqueous Cm(III) complexes with S-layer proteins by time-resolved laser-induced fluorescence spectroscopy (TRLFS). S-layer proteins serve as protective biointerfaces in bacteria and archaea against the surrounding solution. Experimental assays were performed at a fixed total concentration of Cm(III) (0.88 µM) using an S-layer protein (5 g/L / 39.6 µM) at varying pH levels (2.0 to 9.0), as well as several types of S-layer proteins of L. sphaericus JG-A12. Based on resulting luminescence spectra and lifetime data, specific and unspecific binding sites could be distinguished. Notably, specific Cm(III) binding to S-layer proteins was confirmed by the appearance of a sharp emission band at 602.5 nm, combined with a long lifetime of 310 µs. The high affinity of these specific binding sites was also verified using competing EDTA, wherein only a high EDTA concentration (40 µM) could efficiently remove Cm(III) from S-layer proteins.

Keywords: curium; S-layer proteins; Lysinibacillus sphaericus; luminescence spectroscopy, speciation

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  • Secondary publication expected from 05.03.2021

Permalink: https://www.hzdr.de/publications/Publ-29798
Publ.-Id: 29798


Automated SEM Mineral Liberation Analysis (MLA) with Generically Labelled EDX Spectra in the Mineral Processing of Rare Earth Element Ores

Schulz, B.; Merker, G.; Gutzmer, J.

Many rare earth element (REE) deposits have experienced multistage geological enrichment processes resulting in REE bearing mineral assemblages of considerable complexity and variability. Automated scanning electron microscopy (SEM) mineral liberation analysis of such REE ores is confronted by the difficult assignment of energy-dispersive X-ray (EDX) spectra to REE mineral names. To overcome and bypass this problem, a generic and reliable labelling of EDX reference spectra obtained from REE-bearing minerals based on their contents of Si, Ca, F and P in a bulk normalised analysis is proposed. The labelled spectra are then combined into groups of REE-P (similar to monazite), REE-Ca-Si-P (similar to britholite), REE-Ca-F (similar to synchysite) and REE-F (similar to bastnaesite, parisite, fluocerite). Mixed spectra with low counts for REE from minute REE mineral grains are combined into a separate group. This classification scheme is applied to automated SEM mineral liberation analysis (MLA) data from beneficiation products by comminution and multistage flotation of REE carbonatite ores. Mineral modes, mineral grain size distribution, mineral liberation, mineral locking and mineral grade versus recovery curves based on the analysis of >200,000 particles in a sample can be recognised and interpreted in virtual grain size fractions. The approach as proposed here will allow future process mineralogical studies of REE deposits to be robust and comparable.

Permalink: https://www.hzdr.de/publications/Publ-29796
Publ.-Id: 29796


Uranium and neptunium retention mechanisms in Gallionella ferruginea / ferrihydrite systems for remediation purposes

Krawczyk-Bärsch, E.; Scheinost, A. C.; Roßberg, A.; Müller, K.; Lehrich, J.; Bok, F.; Hallbeck, L.; Schmeide, K.

The ubiquitous β-Proteobacterium Gallionella ferruginea is known as stalk-forming, microaerophilic iron(II) oxidizer, which rapidly produces iron oxyhydroxide precipitates. Uranium and neptuniump sorption to the resulting intermixes of G. ferruginea cells, stalks, extracellular exudates and precipitated iron oxyhydroxides (BIOS) was compared to sorption to abiotically formed iron oxides and oxyhydroxides. The results show a high sorption capacity of BIOS towards radionuclides at circumneutral pH values with an apparent bulk distribution coefficient (Kd) of 1.23×10 E4 L/kg for uranium and 3.07×10 E5 L/kg for neptunium. The spectroscopic approach by XAS and ATR FT-IR spectroscopy, which was applied on BIOS samples, showed the formation of inner-sphere complexes. The structural data obtained at the uranium LIII-edge and the neptunium LIII-edge indicate the formation of bidentate edge-sharing surface complexes which are known as the main sorption species on abiotic ferrihydrite. Since the rate of iron precipitation in G. ferruginea dominated systems is 60 times faster than in abiotic systems, more ferrihydrite will be available for immobilization processes of heavy metals and radionuclides in contaminated environments and even in the far-field of high-level nuclear waste repositories.

Keywords: actinides; sorption; microorganism; bacteriogenic iron oxyhydroxides; XAS; ATR FT-IR spectroscopy

Permalink: https://www.hzdr.de/publications/Publ-29795
Publ.-Id: 29795


Independent Geometrical Control of Spin and Charge Resistances in Curved Spintronics

Das, K. S.; Makarov, D.; Gentile, P.; Cuoco, M.; van Wees, B. J.; Ortix, C.; Vera-Marun, I. J.

Spintronic devices operating with pure spin currents represent a new paradigm in nanoelectronics, with a higher energy efficiency and lower dissipation as compared to charge currents. This technology, however, will be viable only if the amount of spin current diffusing in a nanochannel can be tuned on demand while guaranteeing electrical compatibility with other device elements, to which it should be integrated in high-density three-dimensional architectures. Here, we address these two crucial milestones and demonstrate that pure spin currents can effectively propagate in metallic nanochannels with a three-dimensional curved geometry. Remarkably, the geometric design of the nanochannels can be used to reach an independent tuning of spin transport and charge transport characteristics. These results laid the foundation for the design of efficient pure spin current-based electronics, which can be integrated in complex three-dimensional architectures.

Keywords: curved nanoarchitectures; electrical and spin resistance; geometrical control; nonlocal spin valves; Spintronics

Permalink: https://www.hzdr.de/publications/Publ-29794
Publ.-Id: 29794


Numerical and Experimental Investigation of Electro-Vortex Flow in a Cylindrical Container

Liu, K.; Stefani, F.; Weber, N.; Weier, T.; Li, B.-W.

In a cylindrical container filled with an eutectic GaInSn alloy, an electro-vortex flow (EVF) is generated by the interaction of a non-uniform current with its own magnetic field. In this paper, we investigate the EVF phenomenon numerically and experimentally. Ultrasound Doppler Velocimetry (UDV) is applied to measure the velocity field in a cylindrical vessel. Second, we enhance an old numerical solver by taking into account the effect of Joule heating, and employ it for the numerical simulation of the EVF experiment. Special focus is laid on the role of the magnetic field, which is the combination of the current induced magnetic field and the external geomagnetic field. For getting a higher computational efficiency, the so-called parent-child mesh technique is applied in OpenFOAM when computing the electric potential, the current density and the temperature in the coupled solid-liquid conductor system. The results of the experiment are in good agreement with those of the simulation. This study may help to identify the factors that are essential for the EVF phenomenon, and for quantifying its role in liquid metal batteries.

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  • Secondary publication expected from 30.04.2021

Permalink: https://www.hzdr.de/publications/Publ-29793
Publ.-Id: 29793


Effects of Magnetic Field on Hydrogen Bubble Detachment during Water Electrolysis

Yang, X.; Mutschke, G.; Margitta, U.; Eckert, K.

Water electrolysis is a promising option for hydrogen production from renewable resources. One main challenge in making water electrolysis economically competitive is to raise its efficiency by decreasing the cell voltage. In this respect, electrode coverage by gas bubbles is one of the key sources which creates undesired overpotential.

Better understanding of the fundamentals of bubble nucleation, growth, and detachment in detail might bring new ideas in such effective manipulating of bubbles and substantially accelerate a way toward advanced electrolysis. Despite extensive efforts in the past, important aspects of bubble dynamics, such as the interaction/coalescence of bubbles significantly affecting their evolution or different growth modes of the bubbles themselves, are not yet fully understood. To provide that necessary information on the bubble shape profile, including the contact angle, the contact line the bubble forms with the electrode [1], the Marangoni convection[2], we use a micro electrode to produce single hydrogen bubbles. Water electrolysis was carried out under potentiostatic conditions in a 1 M H2SO4 solution in a small electrochemical cell ([2], [3], [4]). The behavior of a single hydrogen bubble evolving on a microelectrode (100 µm in diameter) was analyzed by measurements of the current transient as well as by microscopic high speed imaging. Tracer particles were additionally added to the solution to measure the flow in the vicinity of the bubble.

The contribution will present experimental results of the hydrogen bubble release size and the bubble growing mechanism at two different magnetic field orientations and at different field intensities. As shown in Fig.1, the bubble departure size decreased with increase of the magnetic field intensity when the magnetic field was applied parallel to the electrode surface. However, an increase of the departure size was observed when the field was applied perpendicular to the electrode surface. The effects were further explained by the MHD convection around the bubble. A comparison of the flow field by measurements and numerical simulation will be presented.

  • Lecture (Conference)
    The 8th International Conference on Magneto-Science, 10.-14.10.2019, Hefei, China

Permalink: https://www.hzdr.de/publications/Publ-29792
Publ.-Id: 29792


The effect of hypoxia on the induction of strand breaks in plasmid DNA by alpha-, beta- and Auger electron-emitters 223Ra, 188Re, 99mTc and DNA-binding 99mTc-pyrene

Reissig, F.; Wunderlich, G.; Runge, R.; Freudenberg, R.; Lühr, A.; Kotzerke, J.

Radiation-induced DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The induction mechanism of DNA damage is mainly influenced by the physical characteristics of the radiation quality, especially the linear energy transfer. In general, hypoxia reduces the effect of irradiation treatment in tumor cells and leads to poor patient outcomes. Emitters with high linear energy transfer (alpha- or Auger-electron-emitters) can overcome this obstacle. Our aim is to demonstrate the influence of hypoxia on the interaction between different radiation qualities with DNA by using a cell free plasmid model modulated by the free radical scavenger dimethyl sulfoxide (DMSO).
Plasmid DNA was irradiated with 223Ra, 188Re, 99mTc and DNA-binding 99mTc-pyrene in the absence or presence of DMSO and either under normoxic or hypoxic conditions. The resulting DNA damage in form of single- (SSB) and double strand breaks (DSB) was analyzed by agarose gel electrophoresis. Applied radiation doses of up to 200 Gy of 223Ra, 188Re or 99mTc or 60 Gy of 99mTc-pyrene led to maximal yields of SSB (80%) in plasmid DNA. Irradiation with 223Ra, 188Re or 99mTc at 200 Gy induced 30%, 28% and 32% linear plasmid conformations, respectively, which are associated with DSB. Hypoxia had a minor effect on SSB and DSB induction from 223Ra but a small enhancement in DSB for 188Re and 99mTc. DMSO could prevent DSB completely and SSB DNA damage from the three “free” radionuclides to comparable levels. DNA-binding 99mTc-pyrene induced less SSB and DSB compared to free 99mTcO4- due to its own radical scavenging properties. However, an additional incubation of DMSO could prevent the SSB and DSB induction only to a minor extent. Direct insults of Auger-electrons from 99mTc-pyrene are more effective than high-energy electrons or alpha particles due to the minimal distance between the radionuclide and the DNA.
We conclude that hypoxia does not limit DNA damage in plasmids induced by 223Ra, 188Re, 99mTc and 99mTc-pyrene. Dose-dependent radiation effects were comparable for alpha-emitters and both high- and low-energy electron emitters. The radioprotection by DMSO was not influenced by hypoxia. Overall, the results indicate the contribution of mainly indirect radiation effects for 99mTc, 188Re and 223Ra. 99mTc-pyrene caused direct DNA damages. The direct participation of oxygen in cell-free plasmid DNA damage induction was not proven.

Keywords: hypoxia; plasmid DNA; α-emitter; Auger-electrons; DMSO

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  • Secondary publication expected from 18.01.2021

Permalink: https://www.hzdr.de/publications/Publ-29791
Publ.-Id: 29791


Engineering Self-Supported Noble Metal Foams Toward Electrocatalysis and Beyond

Du, R.; Jin, X.; Hübner, R.; Fan, X.; Hu, Y.; Eychmüller, A.

Noble metals, despite their expensiveness, display irreplaceable roles in widespread fields. To acquire novel physicochemical properties and boost the performance-to-price ratio for practical applications, one core direction is to engineer noble metals into nanostructured porous networks. Noble metal foams (NMFs), featuring self-supported, 3D interconnected networks structured from noble-metal-based building blocks, have drawn tremendous attention in the last two decades. Inheriting structural traits of foams and physicochemical properties of noble metals, NMFs showcase a variety of interesting properties and impressive prospect in diverse fields, including electrocatalysis, heterogeneous catalysis, surface-enhanced Raman scattering, sensing and actuation, etc. A number of NMFs have been created and versatile synthetic approaches have been developed. However, because of the innate limitation of specific methods and the insufficient understanding of formation mechanisms, flexible manipulation of compositions, structures, and corresponding properties of NMFs are still challenging. Thus, the correlations between composition/structure and properties are seldom established, retarding material design/optimization for specific applications. This review is devoted to a comprehensive introduction of NMFs ranging from synthesis to applications, with an emphasis on electrocatalysis. Challenges and opportunities are also included to guide possible research directions in this field and promote the interest of interdisciplinary scientists.

Permalink: https://www.hzdr.de/publications/Publ-29789
Publ.-Id: 29789


Identical pion intensity interferometry at sqrt(s_NN)=2.4 GeV

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.; Garzón, 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.; 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.; 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.; Wójcik, D.; Zanevsky, Y.; Zumbruch, P.

High-statistics π−π− and π+π+ femtoscopy data are presented for Au+Au collisions at sqrt(s_NN)=2.4 GeV, measured with HADES at SIS18/GSI. The experimental correlation functions allow the determination of the space-time extent of the corresponding emission sources via a comparison to models. The emission source, parametrized as three-dimensional Gaussian distribution, is studied in dependence on pair transverse momentum, azimuthal emission angle with respect to the reaction plane, collision centrality and beam energy. For all centralities and transverse momenta, a geometrical distribution of ellipsoidal shape is found in the plane perpendicular to the beam direction with the larger extension perpendicular to the reaction plane. For large transverse momenta, the corresponding eccentricity approaches the initial eccentricity. The eccentricity is smallest for most central collisions, where the shape is almost circular. The magnitude of the tilt angle of the emission ellipsoid in the reaction plane decreases with increasing centrality and increasing transverse momentum. All source radii increase with centrality, largely exhibiting a linear rise with the number of participants, irrespective of transverse momentum. A substantial charge-sign difference of the source radii is found, appearing most pronounced at low transverse momentum. The extracted source parameters are consistent with the extrapolation of their energy dependence down from higher energies.

Permalink: https://www.hzdr.de/publications/Publ-29788
Publ.-Id: 29788


Versatile Bispidine-based Bifunctional Chelators for 64CuII-Labelling of Biomolecules

Singh, G.; Zarschler, K.; Hunoldt, S.; Santana Martinez, I. I.; Rühl, C.; Matterna, M.; Bergmann, R.; Mathe, D.; Hegedüs, N.; Bachmann, M.; Comba, P.; Stephan, H.

Bifunctional chelators as parts of modular metal-based radiopharmaceuticals are responsible for stable complexation of the radiometal ion and for covalent linkage between the complex and the targeting vector. To avoid loss of complex stability, the bioconjugation strategy should not interfere with the radiometal chelation by occupying coordinating groups. The C9 position of the very stable CuII chelator 3,7-diazabicyclo[3.3.1]nonane (bispidine) is virtually predestined to introduce functional groups for facile bioconjugation as this functionalisation does not disturb the metal binding centre. We describe the preparation and characterisation of a set of novel bispidine derivatives equipped with suitable functional groups for diverse bioconjugation reactions, including common amine coupling strategies (bispidine-isothiocyanate) and the Cu-free strain promoted alkyne-azide cycloaddition. We demonstrate their functionality and versatility in an exemplary way by conjugation to an antibody-based biomolecule and validate the obtained conjugate in vitro and in vivo.

Keywords: bispidines; bifunctional chelator; site-specific labelling; imaging; EGFR

Permalink: https://www.hzdr.de/publications/Publ-29787
Publ.-Id: 29787


Ultrasmall silicon nanoparticles as a promising platform for multimodal imaging

Singh, G.; Ddungu, J. L. Z.; Licciardello, N.; Bergmann, R.; de Cola, L.; Stephan, H.

Bimodal systems for nuclear and optical imaging are currently being intensively investigated due to their comparable detection sensitivity and complementary information they provide. In this perspective, we have implemented both modalities on biocompatible ultrasmall silicon nanoparticles (Si NPs). Such nanoparticles are particularly interesting since highly biocompatible, covalent surface functionalization and demonstrated a very fast body clearance. We prepared monodisperse citrate-stabilized Si NPs (2.4 ± 0.5 nm) with more than 40 accessible terminal amino groups per particle and, for the first time, simultaneously a near-infrared dye (IR800-CW) and a radiolabel (64Cu-NOTA = 1,4,7-triazacyclononane-1,4,7-triacetic acid) have been covalently linked to the surface of such Si NPs. The obtained nanomaterials have been fully characterized them by HR-TEM, XPS, UV-Vis and FT-IR spectroscopy. These dual-labelled particles do not exhibit any cytotoxicity in vitro. In vivo studies employing both positron emission tomography (PET) and optical imaging (OI) techniques revealed a rapid renal clearance of dual-labelled Si NPs from mice.

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  • Secondary publication expected from 11.10.2020

Permalink: https://www.hzdr.de/publications/Publ-29786
Publ.-Id: 29786


Updates on the FLUKA geometry for the MU2E experiment

Müller, S.; Ferrari, A.; Rachamin, R.

Presentation at Mu2e Collaboration Meeting 16.10.2019

Keywords: Mu2e; FLUKA; Monte Carlo; CLFV

  • Lecture (Conference)
    Mu2e Collaboration Meeting, 16.-19.10.2019, Fermilab, Batavia, USA

Permalink: https://www.hzdr.de/publications/Publ-29784
Publ.-Id: 29784


Synthesis and cyclooxygenase inhibition of sulfonamide-substituted (dihydro)pyrrolo[3,2,1-hi]indoles and their potential prodrugs

Laube, M.; Gassner, C.; Knieß, T.; Pietzsch, J.

Non-invasive imaging of cyclooxygenase-2 (COX-2) by radiolabeled ligands is attractive for the diagnosis of cancer and novel highly affine leads with optimized pharmacokinetic profile are of high interest for future developments. Recent findings have shown that methylsulfonyl-substituted (dihydro)pyrrolo[3,2,1-hi]indoles represent highly potent and selective COX-2 inhibitors but possess unsuitable pharmacokinetic properties for radiotracer applications. Based on these results, we herein present the development and evaluation of a second series of sulfonamide-substituted (dihydro)pyrrolo[3,2,1-hi]indoles and their conversion into the respective more hydrophilic N-propionamide-substituted analogs. In comparison to the methylsulfonyl-substituted leads, COX inhibition potency and selectivity was retained in the sulfonamide-substituted compounds; however, the high lipophilicity might hinder their future use. The N-propionamide-substituted analogs showed a significantly decreased lipophilicity and, as expected, lower or no COX-inhibition potency. Hence, the N-(sulfonyl)propionamides can be regarded as potential prodrugs, which represents a potential approach for more sophisticated radiotracer developments.

Keywords: Cancer; Imaging; Inflammation; Lipophilicity; McMurry cyclization; Structure-Activity-Relationship

Permalink: https://www.hzdr.de/publications/Publ-29783
Publ.-Id: 29783


Characterization of Tissue Transglutaminase as a Potential Biomarker for Tissue Response toward Biomaterials

Hauser, S.; Wodtke, R.; Tondera, C.; Wodtke, J.; Neffe, A. T.; Hampe, J.; Lendlein, A.; Löser, R.; Pietzsch, J.

Tissue transglutaminase (TGase 2) is proposed to be important for biomaterial−tissue interactions due to its
presence and versatile functions in the extracellular environment. TGase 2 catalyzes the cross-linking of proteins through its Ca2+-dependent acyltransferase activity. Moreover, it enhances the interactions between fibronectin and integrins, which in turn mediates the adhesion, migration, and motility of the cells. TGase 2 is also a key player in the pathogenesis of fibrosis. In this study, we investigated whether TGase 2 is present at the biomaterial−tissue interface and might serve as an informative biomarker for the visualization of tissue response toward gelatin-based biomaterials. Two differently cross-linked hydrogels were used, which were obtained by the reaction of gelatin with lysine diisocyanate ethyl ester. The overall expression of TGase 2 by endothelial cells, macrophages, and granulocytes was partly influenced by contact to the hydrogels or their degradation products, although no clear correlation was evidenced. In contrast, the secretion of TGase 2 differed remarkably between the different cells, indicating that it might be involved in the cellular reaction toward gelatin-based hydrogels. The hydrogels were implanted subcutaneously in immunocompetent, hairless SKH1-Elite mice. Ex vivo immunohistochemical analysis of tissue sections over 112 days revealed enhanced expression of TGase 2 around the hydrogels, in particular at days 14 and 21 post-implantation. The incorporation of fluorescently labeled cadaverine derivatives for the detection of active TGase 2 was in accordance with the results of the expression analysis. The presence of an irreversible inhibitor of TGase 2 led to attenuated incorporation of the cadaverines, which verified the catalytic action of TGase 2. Our in vitro and ex vivo results verified TGase 2 as a potential biomarker for tissue response toward gelatin-based hydrogels. In vivo, no TGase 2 activity was detectable, which is mainly attributed to the unfavorable physicochemical properties of the cadaverine probe used.

Keywords: extracellular matrix modifying enzymes; gelatin-based hydrogels; biomaterial−tissue interface; polyamines; optical imaging

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  • Secondary publication expected from 07.10.2020

Permalink: https://www.hzdr.de/publications/Publ-29782
Publ.-Id: 29782


Accuracy and robustness of 4D logfile-based dose reconstruction

Spautz, S.; Peters, N.; Meijers, A.; Jakobi, A.; Knopf, A.; Troost, E. G. C.; Richter, C.; Stützer, K.

Introduction: We plan to use 4D logfile-based dose reconstruction for daily monitoring and potential intervention in PBS treatments of non-small cell lung cancer patients, restricted to limited motion (≤5mm). Here, we assessed the validity of reconstructed doses and their sensitivity to selected disturbed input parameters by dedicated phantom experiments.
Material/Methods: Quasi-monoenergetic proton fields were delivered to a dynamic thorax phantom (G.C. Technology, Germany) equipped with a 3cm soft-tissue target intersected by a radiochromic film. The surrogate signal (AZ733-V, ANZAI Medical Co.,Ltd, Japan) of the motion patterns (cos/cos4, period: 5s, peak-to-peak amplitude: 5mm and 30mm) was recorded in synchronization with the machine logfiles. 4D reconstructions with 1mm/3mm dose grid resolution were performed using 4DCTs of 12 amplitude-sorted phases and either ground truth or automatically generated deformation vector fields. Characteristic 1D profiles of the reconstructed and measured doses were compared by gamma index analyses (2mm, 2%). Maximum dose deviations due to simulated offsets between motion and machine logfiles (±1/±5/±25/±250ms) were assessed for quasi-monoenergetic and 4D optimized plans.
Results: Characteristic dose patterns were well reproduced (Fig.1). Gamma pass rates were >98% under static conditions. For 5mm motion, the pass rate of 94.2% for an ideal reconstruction with 1mm³ dose voxels dropped to 93.0% with clinically used voxel sizes (3×3×3mm³), 83.6% when using automated DIR and 78.2% for the combination of both, respectively. For the 30mm motion, the CT artifacts and residual motion were predominant and lead for 3mm dose grids to gamma pass rates of approximately 84%, irrespective of chosen DIR. Fig.2 depicts the effect of simulated logfile asynchrony.
Conclusions: The implemented method is robust against disturbed input parameters for the small, clinically aimed motion amplitudes. Reconstruction accuracy decreases with deformation-related inaccuracies and increasing 4DCT artifacts for large motion. Consistent breathing and regular control CTs are compulsory for meaningful 4D logfile-based dose reconstructions.

  • Poster
    4D Treatment Workshop for Particle Therapy 2019, 22.-23.11.2019, Kraków, Polska

Permalink: https://www.hzdr.de/publications/Publ-29781
Publ.-Id: 29781


Search for beta-delayed proton emission from ¹¹Be

Riisager, K.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Forstner, O.; Fraile, L. M.; Fynbo, H. O. U.; Garzon Camacho, A.; Johansen, J. G.; Jonson, B.; Lund, M. V.; Lachner, J.; Madurga, M.; Merchel, S.; Nacher, E.; Nilsson, T.; Steier, P.; Tengblad, O.; Vedia, V.

We report on an attempt to reproduce the observation of beta-minus-delayed proton emission from ¹¹Be through detection of the final state nucleus ¹⁰Be with accelerator mass spectrometry. Twelve samples were collected at the ISOLDE facility at CERN at different separator settings, allowing tests of different sources of contamination to be carried out. The observed amounts of ¹⁰Be per collected ¹¹Be rule out several contamination sources, but do not agree internally. Formation of BeH molecular ions in the ion source may explain our data, in which case an upper limit of the beta p branching ratio of 2.2 x10-6 can be derived.

Keywords: beta-decay; AMS

Permalink: https://www.hzdr.de/publications/Publ-29780
Publ.-Id: 29780


A Simulation-Based Study on Reprocessing of Phosphate Tailings for Recovering Pyrochlore and Monazite

Vicino Pacheco De Aquino, T.; Pereira, L.; Hassanzadehmahaleh, A.; Belo Fernandes, I.; Rudolph, M.; Mischo, H.; Barakos, G.

The present study aims to investigate possibilities for improving the recovery of pyrochlore ((Na, Ca)₂Nb₂O₆) and monazite ((Ce, La, Th, Sm)PO4) as by-products from a phosphate mine with current niobium (Nb) production from geometallurgical perspectives. With this purpose, process mineralogy of Nb- and REE-bearing minerals together with operating properties of the concentration plant are examined using respectively mineral liberation analyzer (MLA) and the HSC® Chemistry 9 simulation module. A plant-site sampling campaign was performed and key operating parameters such as throughputs and pulp densities for individual streams were measured. The results obtained by MLA analyses as the base of mineral mass balances were compared and validated by commonly used chemical characterization techniques i.e. X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma–optical emission spectroscopy (ICP-OES). Simulation results showed that the combination of Nb flotation rougher and scavenger cells into one single rougher bank plus the addition of a new scavenger bank (4x1.4 m³ cells) can increase pyrochlore recovery in the silica/niobium flotation circuit from approximately 31% to 44%. This cell configuration improves the ultimate pyrochlore’s plant recovery from 27% to 38% leading to a substantial enhancement in final concentrate throughput from 540 to 740 kg/h. Future studies on this topic include the use of wet high intensity magnetic separation (WHIMS) and froth flotation respectively for the pre-concentration and concentration of monazite.

Keywords: Pyrochlore; phosphate deposit; rare earth elements (REE); HSC Sim®; process simulation

  • Contribution to proceedings
    International Mineral Processing Conference Eurasia (IMPC 2019), 31.10.-02.11.2019, Antalya, Turkey
    Proceedings of IMPC 2019

Permalink: https://www.hzdr.de/publications/Publ-29779
Publ.-Id: 29779


⁹⁹Tc immobilization by aluminum solids containing Fe(II) moieties

Mayordomo Herranz, N.; Rodriguez Hernandez, D. M.; Molodtsov, K.; Johnstone, Erik V.; Roßberg, A.; Heim, K.; Foerstendorf, H.; Schild, Dieter; Brendler, V.; Müller, K.

The immobilization of ⁹⁹Tc is predominantly mediated by the reduction of Tc(VII) to Tc(IV), primarily due to the fact that [Tc(VII)O₄] ⁻ interactions with solid interfaces are limited, whereas Tc(IV)O₂ is a hardly soluble solid [1]. Tc reduction is facilitated by Fe²⁺, particularly when it is present as a sorbed species or a constituent mineral phase [2].
The present work analyzes the ⁹⁹Tc aqueous removal by two aluminum solids containing Fe(II) moieties: γ-Al₂O₃ with sorbed Fe²⁺ and Fe(II)-Al(III) layered double hydroxide (LDH). Batch contact experiments demonstrate that both solids are effective Tc scavengers, yielding a complete removal for pH > 6.5 and from pH 3.5 to 10.5, respectively. Characterization via XPS, XAS, and in situ ATR FT-IR spectroscopy provided information of the Tc speciation and uptake mechanism. Secondary Fe-minerals (hematite, magnetite, ferrihydrite) formed in the reduction were also identified by Raman microscopy.

Bibliography
[1] Meena, A. H.; Arai, Y. Env. Chem Lett 2017, 15, 241–263.
[2] Cui, D.; Eriksen, T. E. Environ. Sci. Technol. 1996, 30 (7), 2259–2262.

  • Lecture (Conference)
    The 43th symposium on scientific basis for nuclear waste management, 21.-24.10.2019, Viena, Austria

Permalink: https://www.hzdr.de/publications/Publ-29778
Publ.-Id: 29778


Some microbial issues regarding the storage of high-level radioactive waste

Matschiavelli, N.; Kluge, S.; Dressler, M.; Cherkouk, A.

The talk summerizes bio-geochemical results regarding the potential geo-technical barrier bentonite in a repositors of high-level radioactive waste.

  • Lecture (others)
    18th bilateral meeting HZDR/IRE - PSI/LES, 28.-29.10.2019, HZDR, IRE, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29777
Publ.-Id: 29777


Nonstoichiometric Phases of Two-Dimensional Transition-Metal Dichalcogenides: From Chalcogen Vacancies to Pure Metal Membranes

Joseph, T.; Ghorbani Asl, M.; Kvashnin, A. G.; Larionov, K. V.; Popov, Z. I.; Sorokin, P. B.; Krasheninnikov, A.

Two-dimensional (2D) membranes consisting of a single layer of Mo atoms were recently manufactured [ Adv. Mater. 2018, 30, 1707281] from MoSe2 sheets by sputtering Se atoms using an electron beam in a transmission electron microscope. This is an unexpected result as formation of Mo clusters should energetically be more favorable. To get microscopic insights into the energetics of realistic Mo membranes and nonstoichiometric phases of transition-metal dichalcogenides (TMDs) MaXb, where M = Mo and W and X = S, Se, and Te, we carry out first-principles calculations and demonstrate that the membranes, which can be referred to as metallic quantum dots embedded into a semiconducting matrix, can be stabilized by charge transfer. We also show that an ideal neutral 2D Mo or W sheet is not flat but a corrugated structure, with a square lattice being the lowest-energy configuration. We further demonstrate that several intermediate nonstoichiometric phases of TMDs are possible as they have lower formation energies than pure metal membranes. Among them, the orthorhombic metallic 2D M4X4 phase is particularly stable. Finally, we study the properties of this phase in detail and discuss how it can be manufactured by the top-down approaches.

Keywords: 2D; non-stoichiometric phases; Transition-Metal Dichalcogenides; DFT; metal membrane

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  • Secondary publication expected from 07.10.2020

Permalink: https://www.hzdr.de/publications/Publ-29776
Publ.-Id: 29776


Thickness of polyelectrolyte layers of separately confined bacteria alters key physiological parameters on a single cell level

Rybkin, I.; Gorin, D.; Sukhorukov, G.; Lapanje, A.

Confinement of bacterial cells in matrix or capsules is an integral part of many biotechnological applications. Here, it is adopted the well-known layer-by-layer method of deposition of a few nanometer thick polyelectrolyte layers to confine separated bacterial cells in permeable and physically durable shells. Due to the physical properties of such a confinement, here it is found that this method enables investigation of effects of physical barrier against the mass gain and cell division. Using the method of time-lapse confocal microscopy, it is observed a prolonged lag phase, dependent on the number of polyelectrolyte layers. In the confinement, both the GFP fluorescent signal from the leaking T7 promoter and cell size, were increased by more than five and two times, respectively. This creates paradigm shift that enables using mechanical entrapment for control of bacterial cell physiology which opens possibilities of controlling the division rate as well as gene expression. These effects can be attributed to the perturbation of the sensing of the cell size, which results in disproportional synthesis of cell envelope against the intracellular material and compels cells to grow rapidly. In addition, the charged surface of cells enabled longer intercellular physical interaction resulting in spherically shaped microcolonies.

Keywords: time-lapse confocal microscopy; polyelectrolytes; layer-by-layer encapsulation; electrostatic interactions; cell surface modification

Permalink: https://www.hzdr.de/publications/Publ-29775
Publ.-Id: 29775


M4F - Materials Modelling For Fusion and Fission Materials - Domain 1

Heintze, C.; Olsson, P.; Konstantinovic, M.; Caturla, M.-J.

The talk provides on overview on the objectives, activities and first results of Domain 1 of the H2020/EU project M4F. It aims at providing a broader scientific motivation and background for the benefit of the PhD students and post-docs participating in the project.

  • Lecture (others)
    M4F PhD and post-doc event, 23.-25.06.2019, Miraflores de la Sierra, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-29774
Publ.-Id: 29774


Behaviour of C, Ni, Si, P under ion irradiation at different doses in model FeCr(Ni, Si, P) alloys

Gueye, P.-M.; Gomez-Ferrer, B.; Heintze, C.; Pareige, C.

Ferritic-martensitic steels with high chromium content are considered as promising candidates as structural materials in Gen-IV reactors because of their low swelling value for operating conditions and low ductile-brittle transition temperature (DBTT) shift under irradiation. Nevertheless, they tend to harden and embrittle under irradiation at low temperatures (350°C). Impurities as Ni, Si and P are known to increase hardening in these steels by creating solute-rich clusters (SRCs) [1-4].
In order to understand the role of each impurity on the formation of SRCs under irradiation, FeCr (NiSiP) alloys with different concentrations in Ni, Si and P have been ion irradiated with 5 MeV Fe2+ ions up to 0.1, 0.5 and 2.5 dpa at 300°C. The evolution of the solute distribution has been investigated by atom probe tomography (APT).
The results reveal the tendency to cluster of Ni, Si and P under irradiation from 0.1 dpa. Moreover, differences on the solutes distributions between materials containing one low-alloying element (Ni, Si or P) and the alloy containing Ni, Si and P, suggest a synergetic effect between these species. Results show the major role of P on the formation of the SRCs. The influence of C on the formation of SRCs will also be discussed.

References
[1] F. Garner, M. Toloczko, B. Sencer, J. Nucl. Mater. 276 (2000) 123.
[2] R. L. Klueh, A. T. Nelson, J. Nucl. Mater. 371 (2007) 37-52.
[3] A. Kohyama, A. Hishinuma, D. S. Gelles, R. L. Klueh, W. Dietz, K. Ehrlich, J. Nucl. Mater. 233-237 (1996) 138-147.
[4] B. Gomez-Ferrer, C. Heintze, C. Pareige, J. Nucl. Mater. 515 (2019) 35-44.

  • Lecture (others)
    M4F PhD and post-doc event, 23.-25.06.2019, Miraflores de la Sierra, Madrid, Spain

Permalink: https://www.hzdr.de/publications/Publ-29773
Publ.-Id: 29773


On the role of Ni, Si and P on the nanostructural evolution of FeCr alloys under irradiation – link with hardening

Pareige, C.; Gómez-Ferrer, B.; Heintze, C.; Oñorbe, E.; Hernandez-Mayoral, M.; Desgardin, P.; Malerba, L.

High-chromium ferritic-martensitic (F-M) steels are promising candidates for structural components in Gen-IV reactors because of their excellent swelling resistance and good thermal properties. However, the operating window of these steels is constrained by irradiation hardening at low temperature (<350°C). This issues has been addressed within the FP7/MatISSE project.
After neutron irradiation of Fe-Cr alloys of low purity (model alloys of F-M steels), impurities as P, Ni and Si have been shown to create solute clusters which significantly contribute to hardening and might be associated with small invisible dislocation loops1. In order to understand the role of each impurity on the formation of the nano-features formed under irradiation and the eventual synergies between the different species, FeCr(SiNiP) alloys of different composition has been ion irradiated and characterized using transmission electron microscopy, atom probe tomography, positron annihilation and nano-indentation. Combination of these techniques enabled to study the influence of these impurities on the concentration of vacancy defects, formation of solute clusters and dislocation loops and to make the link with irradiation hardening.

  • Lecture (Conference)
    SMINS 5 - NEA International Workshop on Structural Materials for Innovative Nuclear Systems, 08.-11.07.2019, Kyoto, Japan

Permalink: https://www.hzdr.de/publications/Publ-29772
Publ.-Id: 29772


Influence of impurities in microstructural evolution of FeCr alloys under ion irradiation – link with hardening

Pareige, C.; Gómez-Ferrer, B.; Heintze, C.; Onorbe, E.; Hernándet Mayoral, M.; Gueye, P.-M.; Malerba, L.

After neutron irradiation of Fe-Cr alloys of low purity (model alloys of F-M steels), impurities as P, Ni and Si have been shown to create solute clusters which significantly contribute to hardening and might be associated with small dislocation loops. In order to understand the role of each impurity on the formation of the nano-features formed under irradiation and the eventual synergies between the different species, FeCr(SiNiP) alloys of different composition have been ion irradiated and characterized using transmission electron microscopy, atom probe tomography and nano-indentation. Combination of these techniques enabled to study the influence of these impurities on the formation of solute clusters and dislocation loops and to make the link with irradiation hardening. Influence of C atoms on the nanostructure evolution will also be discussed.

  • Lecture (Conference)
    MINES - Materials in Nuclear Energy Systems, 06.-10.10.2019, Baltimore, Maryland, USA

Permalink: https://www.hzdr.de/publications/Publ-29771
Publ.-Id: 29771


Neutron irradiated microstructure of FeCr alloys investigated by TEM

Hernández Mayoral, M.; Onorbe, E.; Gómez-Ferrer, B.; Heintze, C.; Malerba, L.; Gueye, P.-M.; Pareige, C.

Different parameters have been observed to influence the nature and evolution of the neutron radiation induced features, which are responsible of the mechanical behavior of FeCr-based alloys. In this work, the experimental conditions were selected so as to focus on the effect of both, composition and irradiation temperature. The study has been performed in the framework of collaborative European funded projects, where a combination of advanced characterization techniques was applied to a set of alloys of varying composition and initial microstructure, which were irradiated together under different conditions of temperature, dose and also dose-rate. The characterization of dislocation loops has been performed on the basis of Transmission Electron Microscopy (TEM), while the solute redistribution has been studied by Atom Probe Tomography (APT). The results, that show how the involved variables affect the neutron irradiated microstructure, will be presented and discussed.

  • Lecture (Conference)
    MINES - Materials in Nuclear Energy Systems, 06.-10.10.2019, Baltimore, Maryland, USA

Permalink: https://www.hzdr.de/publications/Publ-29770
Publ.-Id: 29770


Hyperspectral outcrop models for palaeoseismic studies

Kirsch, M.; Lorenz, S.; Zimmermann, R.; Andreani, L.; Tusa, L.; Pospiech, S.; Jackisch, R.; Unger, G.; Khodadadzadeh, M.; Ghamisi, P.; Middleton, M.; Ojala, A.; Mattila, J.; Nordbäck, N.; Palmu, J.-P.; Ruskeeniemi, T.; Sutinen, R.; Tiljander, M.; Heikkilä, P.; Gloaguen, R.

The traditional study of palaeoseismic trenches, involving logging, stratigraphic and structural interpretation, can be time consuming and affected by biases and inaccuracies. To overcome these limitations, a new workflow is presented that integrates infrared hyperspectral and photogrammetric data to support field-based palaeoseismic observations. As a case study, this method is applied on two palaeoseismic trenches excavated across a post-glacial fault scarp in northern Finnish Lapland. The hyperspectral imagery (HSI) is geometrically and radiometrically corrected, processed using established image processing algorithms and machine learning approaches, and co-registered to a structure-from-motion point cloud. HSI-enhanced virtual outcrop models are a useful complement to palaeoseismic field studies as they not only provide an intuitive visualisation of the outcrop and a versatile data archive, but also enable an unbiased assessment of the mineralogical composition of lithologic units and a semi-automatic delineation of contacts and deformational structures in a 3D virtual environment.

Keywords: palaeoseismology; SfM photogrammetry; hyperspectral imaging; geology; remote sensing; outcrop models

Permalink: https://www.hzdr.de/publications/Publ-29768
Publ.-Id: 29768


Direct Synthesis of Large-Scale Multilayer TaSe2 on SiO2/Si Using Ion Beam Technology

Tsai, H.-S.; Liu, F.-W.; Liou, J.-W.; Chi, C.-C.; Tang, S.-Y.; Wang, C.; Ouyang, H.; Chueh, Y.-L.; Liu, C.; Zhou, S.; Woon, W.-Y.

The multilayer 1T-TaSe2 is successfully synthesized by annealing a Se-implanted Ta thin film on the SiO2/Si substrate. Material analyses confirm the 1T (octahedral) structure and the quasi-2D nature of the prepared TaSe2. Temperaturedependent resistivity reveals that the multilayer 1T-TaSe2 obtained by our method undergoes a commensurate charge-density wave (CCDW) transition at around 500 K. This synthesis process has been applied to synthesize MoSe2 and HfSe2 and expanded for synthesis of one more transition-metal dichalcogenide (TMD) material. In addition, the main issue of the process, that is, the excess metal capping on the TMD layers, is solved by the reduction of thickness of the as-deposited metal thin film in this work.

Keywords: TaSe2; charge-density wave; ion beam; synthesis

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Permalink: https://www.hzdr.de/publications/Publ-29766
Publ.-Id: 29766


Production of the amphiphilic siderophore Marinobactin for the application as froth flotation reagent. 

Schrader, S.; Kutschke, S.; Rudolph, M.; Pollmann, K.

The consumption of metallic raw materials increased in the last years. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, some new ways have to be gone, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in the classic froth flotation process. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate groups, is responsible for the binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same functional groups, also work well as collectors. The fatty acid tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work presents interaction studies and flotation experiments of different scales, including “Bubble pick up test”, Halimond tube tests and one-liter flotation experiments of iron, copper and PGM containing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.

Keywords: Marinobactin; Marinobacter; amphiphilic; Siderophores froth flotation

  • Lecture (Conference)
    23. International Biohydrometallurgy Symposium, 20.10.2019, Fukuoka, Japan

Permalink: https://www.hzdr.de/publications/Publ-29765
Publ.-Id: 29765


Amphiphilic Siderophores – A group of complexing surfactant bioreagents for the application in froth flotation separation

Schrader, S.; Kutschke, S.; Hartmann, S.; Pollmann, K.; Rudolph, M.

The consumption of metallic raw materials is constantly increasing. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, new approaches will have to be developed, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in conventional froth flotation processes. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to selectively form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate functional groups, is responsible for the selective binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same and even more selective functional groups are highly potential as ecofriendly collector molecules for flotation and should generally be interesting for the surfactant industry. The molecule’s tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work includes also interaction studies and flotation experiments of different scales, including bubble pick-up tests, Halimond tube microflotation and batch lab flotation experiments of iron and copper bearing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.

Keywords: Marinobactin; Marinobacter; amphiphilic; Siderophores froth flotation

  • Poster
    Jahrestreffen der ProcessNet-Fachgruppen Zerkleinern und Klassieren, Kristallisation und Grenzflächenbestimmte Systeme und Prozesse, 12.-13.03.2019, Bamberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29764
Publ.-Id: 29764


Integriertes Management und Publikation von wissenschaftlichen Artikeln, Software und Forschungsdaten am Helmholtz-Zentrum Dresden-Rossendorf (HZDR)

Reschke, E.; Konrad, U.

Mit dem Ziel, das Publizieren von Artikeln, Forschungsdaten und wissenschaftlicher Software gemäß den FAIR-Prinzipien (https://www.go-fair.org/fair-principles/) zu unterstützen, wurde am HZDR ein integriertes Publikationsmanagement aufgebaut. Insbesondere Daten- und Softwarepublikationen erfordern die Entwicklung bedarfsgerechter organisatorischer und technischer Strukturen ergänzend zu bereits sehr gut funktionierenden Services im Publikationsmanagement. In der Zusammenarbeit mit Wissenschaftlern des HZDR und internationalen Partnern in ausgewählten Projekten wurde der Bedarf an Unterstützung im Forschungsdatenmanagement analysiert. Darauf aufbauend wurde schrittweise ein integriertes System von Infrastrukturen und Services entwickelt und bereitgestellt. In einer seit Mai 2018 gültigen Data Policy wurden die Rahmenbedingungen und Regelungen sowohl für wissenschaftliche Mitarbeiter als auch für externe Messgäste definiert. Im Vortrag wird auf die Erfahrungen im integrierten Publikationsmanagement für Artikel, Forschungsdaten und Forschungssoftware eingegangen und daraus resultierend werden die nächsten Aufgaben und Ziele entwickelt.

Keywords: Open Access; Research Data; Rodare; Robis; Research Infrastructure

  • Open Access Logo Invited lecture (Conferences)
    „Forschungsdaten in Sachsen: Planen – Organisieren – Nachnutzen“ – 1. sächsische FDM-Tagung, 19.09.2019, Dresden, Deutschland

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29763
Publ.-Id: 29763


Production of the amphiphilic siderophore marinobactin and the application as froth flotation reagent

Schrader, S.; Kutschke, S.; Rudolph, M.; Pollmann, K.

The consumption of metallic raw materials increased in the last years. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, some new ways have to be gone, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in the classic froth flotation process. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate groups, is responsible for the binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same functional groups, also work well as collectors. The fatty acid tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work presents interaction studies and flotation experiments of different scales, including “Bubble pick up test”, Halimond tube tests and one-liter flotation experiments of iron, copper and PGM containing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.

Keywords: Marinobactin; Marinobacter; amphiphilic; Siderophores froth flotation

  • Poster
    4th Green & Sustainable Chemistry Conference, 05.-08.05.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29762
Publ.-Id: 29762


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