Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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34188 Publications

Raw data: CoFeB beamtime overview

Awari, N.; Deinert, J.-C.

Collection of raw data and evaluated data for the CoFeB experiments carried out in collaboration with Stefano Bonetti et al.

Keywords: Spin dynamics; nutation; CoFeB; Terahertz

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-19
    DOI: 10.14278/rodare.551


Publ.-Id: 31612

Parametric optimization in rougher flotation performance of a sulfidized mixed copper ore

Hassanzadehmahaleh, A.; Azizi, A. A.; Masdarian, M. A.; Bahri, Z. C.; Niedoba, T. D.; Surowiak, A. D.

The dominant challenge of current copper beneficiation plants is the low recoverability of oxide copper-bearing minerals associated with sulfide type ones. Furthermore, applying commonly used conventional methodologies does not allow the interactional effects of critical parameters in the flotation processes to be investigated, which is mostly overlooked in the literature. To tackle this issue, the present paper aimed at characterizing the behavior of five key effective factors and their interactions in a sulfidized copper ore. In this context, dosage of collector (sodium di-ethydithiophosphate, 60–100 g/t), depressant (sodium silicate, 80–120 g/t) and frother (methyl isobutyl carbinol (MIBC), 6–10 g/t), pulp pH (7–11) and agitation rate (900–1300 rpm) were examined and statistically analyzed using response surface methodology. Flotation experiments were conducted in a Denver type agitated flotation cell at the rougher stage. The experimental results showed that increasing the pH (from 8 to 10) at low agitation rate (1000 rpm) enhanced the recovery from 80.36% to 85.22%, while at high agitation rate (1200 rpm), a slight declination occurred in the recovery. Meanwhile, increasing the collector dosage at a lower frother value (7 g/t), caused a reduction of about 4.44% in copper recovery owing to the interactions between factors, whereas at a higher frother level (9 g/t), the recovery was almost unchanged. The optimization process was also performed using the goal function approach, and maximum copper recovery of 92.75% was obtained using ~70 g/t collector, 110 g/t depressant, 7 g/t frother, pulp pH of 10 and 1000 rpm agitation rate.

Keywords: sulfidized copper ore; flotation; recovery; optimization; interaction effects

Publ.-Id: 31611

Code, data and supplementary material for: An improved contact method for quantifying the mixing of a binary granular mixture

Papapetrou, T. N.; Lecrivain, G.; Bieberle, M.; Boudouvis, A.; Hampel, U.

This material is related to the publication "An improved contact method for quantifying the mixing of a binary granular mixture", submitted on 13.05.2020 to Granular Matter. The original camera video, an intermediate masked video and the final preprocessed video used in the calculations, made from frames 4-1004 of the masked one, are included. The code used for all calculations in the paper and supplementary material, including the implementation of the mixing index evaluation methods, as well as the static artificial images and the generated data, are also included. All images used in the calculations are stored in the required data form. The figures of the paper are also included, as well as two supplementary materials: a version of Figure 12 with the points of the original contact method, and a discussion on the calculation of the minimum modified contact length.

Keywords: binary particle mixing; rotating drum; image analysis; mixing index; contact method; variance method

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-13
    DOI: 10.14278/rodare.548


Publ.-Id: 31602

The effect of Pd(II) chloride complexes anchoring on the formation and properties of Pd/MgAlOx catalysts

Belskaya, O. B.; Zaikovskii, V. I.; Gulyaeva, T. I.; Talsi, V. P.; Trubina, S. V.; Kvashnina, K.; Nizovskii, A. I.; Kalinkin, A. V.; Bukhtiyarov, V. I.; A. Likholobov, V.

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


  • Secondary publication expected from 08.10.2021

Publ.-Id: 31600

Development of New 14 Cr ODS Steels by Using New Oxides Formers and B as an Inhibitor of the Grain Growth

Meza, A.; Macía, E.; García-Junceda, A.; Antonio Díaz, L.; Chekhonin, P.; Altstadt, E.; Serrano, M.; Eugenia Rabanal, M.; Campos, M.

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

Publ.-Id: 31597

Automated mineralogy particle dataset: apatite flotation

Hoang, D. H.; Pereira, L.; Kupka, N.; Tolosana Delgado, R.; Frenzel, M.; Rudolph, M.; Gutzmer, J.

This particle dataset was used for demonstrating the particle-tracking method presented in the paper "Computing single-particle flotation kinetics using automated mineralogy data and machine learning", submitted to Minerals Engineering in 08/10/2020, by Lucas Pereira, Max Frenzel, Duong Huu Hoang, Raimon Tolosana-Delgado, Martin Rudolph, Jens Gutzmer from the Helmholtz Institute Freiberg for Resource Technology.

This data belongs to the flotation tests performed by Duong Huu Hoang, and presented in:

Hoang, D.H., Kupka, N., Peuker, U.A., Rudolph, M., 2018. Flotation study of fine grained carbonaceous sedimentary apatite ore – Challenges in process mineralogy and impact of hydrodynamics. Miner. Eng. 121, 196–204.

For this study, phosphate rock samples from the Lao Cai province, Vietnam, were provided by the Vietnam Apatite Limited Company. The objective of the flotation experiments was to determine the best way to efficiently separate fluorapatite from dolomite, calcite and silicates. After grinding for 8 minutes in a laboratory ball mill to assure a d90 of 67 µm, batch flotation tests were performed in a flotation cell built at the TU Bergakademie Freiberg. Corn starch ((C6H10O5)n) gelatinized with sodium hydroxide (NaOH) was used in combination with sodium silicate (Na2SiO3) to depress gangue minerals. The latter also acts as a fine particle dispersant. Solution pH was kept at 10 using the modifier sodium carbonate (Na2CO3), which can also be regarded as a depressant. Berol 2015 was used as the collector. Four concentrate fractions were collected after 0.75 min (CA), 1.50 min (CB), 3.00 min (CC), and 6.00 min (CD). In addition, a final tailings sample was collected (TD). Five replicates of the test were done to ensure reproducibility and produce enough sample mass for detailed characterization. All samples, including the feed, were wet sieved into four size fractions (-20 µm, +20 to -32 µm, +32 to -50 µm, and +50 µm) before characterization by MLA at the Helmholtz Institute Freiberg for Resource Technology. Samples were analyzed on a FEI Quanta 650F scanning electron microscope equipped with two Bruker Quantax X-Flash 5030 EDX detectors. The SEM was operated at 25 kV overall electron beam accelerating voltage and Extended BSE Liberation Analysis measurement mode. MLA results were validated with ICP-OES chemical assays. Particles from the flotation product samples (concentrate and tailings) are in the Traindata.csv file, while particles from the feed sample are in the FeedData.csv file. The weight distribution of each sample is given below:

Sample | wt.%

CA -20µm | 6.7

CA 20-32µm | 5.8

CA 32-50µm | 4.6

CA +50µm | 2.2

CB -20µm | 6.4

CB 20-32µm | 5.4

CB 32-50µm | 3.9

CB +50µm | 2.8

CC -20µm | 5.8

CC 20-32µm | 4.3

CC 32-50µm | 3.5

CC +50µm | 2.0

CD -20µm | 4.7

CD 20-32µm | 2.8

CD 32-50µm | 2.3

CD +50µm | 1.1

TD -20µm | 11.3

TD 20-32µm | 7.0

TD 32-50µm | 6.7

TD +50µm | 10.7

Feed -20µm | 36.60

Feed 20-32µm | 23.88

Feed 32-50µm | 21.75

Feed +50µm | 17.78

Variable names:

  • Mineral composition: Actinolite, Albite, Almandine, Apatite, Barite, Biotite, Calcite, Chalcopyrite, Clinochlore, Diopside, Dolomite, Fluorite, Hematite, Muscovite, Orthoclase, Plagioclase, Phlogopite, Pyrite, Pyrrhotite, Quartz, Rutile, Sanidine, Sphalerite_Fe, Titanite, Zircon.
  • Surface composition:,,,,,,,,,,,,,,,,,,,,,,,,
  • Size and shape: AspectRatio, Solidity, ECD
  • Sample identifier: Class - In this case, particles identified with "CA20", for example, are the particles from the <20µm size fraction of the first concentrate sample, while "TD50" are the particles from the >50µm size fraction of the final tailings sample.

Keywords: Apatite; Froth flotation; Automated mineralogy; Geometallurgy; Particle-tracking

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-08
    DOI: 10.14278/rodare.542
    License: CC-BY-4.0


Publ.-Id: 31592

Raw data: Magnetic field-induced even-order harmonic generation in the three-dimensional Dirac semimetal Cd3As2

Deinert, J.-C.

Raw files from the TELBE beamtime August 2020 for exchange.

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-06
    DOI: 10.14278/rodare.533


Publ.-Id: 31589

Interactive results viewer: Computing single-particle flotation kinetics using automated mineralogy data and machine learning

Pereira, L.; Frenzel, M.; Hoang, D. H.; Tolosana Delgado, R.; Rudolph, M.; Gutzmer, J.

This plotting application allows the reader to interact with all results obtained in the case study presented in the publication

"Computing single-particle flotation kinetics using automated mineralogy data and machine learning", submitted on 07/10/2020 to Minerals Engineering and currently under review.

The interactive plot displays the flotation kinetics modelling outcome (k, Rmax, km) for single-particles. The user is able to filter particles according to their intrinsic properties (modal composition, surface composition, size, and shape), thus allowing the user to understand the influence of every particle property in their process (i.e. flotation) behavior.

The platform contains a help function to guide the user.

It can be accessed here: Pereira et al. 2021 Flotation kinetics platform.

Keywords: Geometallurgy; Particle-tracking; Froth flotation; Automated mineralogy

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-06
    DOI: 10.14278/rodare.535
    License: CC-BY-4.0


Publ.-Id: 31588

BGM MLA data from grinding kinetics experiments

Belo Fernandes, I.

Datasource from two sets of grinding experiments:

- from top size fraction -1600µm+1250µm

- from top size fraction -425µm+315µm

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-05
    DOI: 10.14278/rodare.531


Publ.-Id: 31586

Long-range magnetic order in the S = 1/2 triangular lattice antiferromagnet KCeS2

Bastien, G.; Rubrecht, B.; Haeussler, E.; Schlender, P.; Zangeneh, Z.; Avdoshenko, S.; Sarkar, R.; Alfonso, A.; Luther, S.; Onykiienko, Y. A.; Walker, H. C.; Kühne, H.; Grinenko, V.; Guguchia, Z.; Kataev, V.; Klauss, H.-H.; Hozoi, L.; van den Brink, J.; Inosov, D. S.; Büchner, B.; Wolter, A. U. B.; Doert, T.

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

Publ.-Id: 31585

2D MOFs: A New Platform for Optics?

Arora, H.; Park, S.; Dong, R.; Erbe, A.

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

Keywords: Metal-organic frameworks; Two-dimensional semiconductors; Photonics; optical applications; photodetectors; high-mobility materials; sensors

Publ.-Id: 31584

New reaction rates for the destruction of 7Be during big bang nucleosynthesis measured at CERN/n_TOF and their implications on the cosmological lithium problem

Mengoni, A.; Damone, L. A.; Barbagallo, M.; Aberle, O.; Alcayne, V.; Amaducci, S.; Andrzejewski, J.; Audouin, L.; Babiano-Suarez, V.; Bacak, M.; Bennett, S.; Berthoumieux, E.; Bosnar, D.; Brown, A. S.; Busso, M.; Caamaño, M.; Caballero, L.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Casanovas, A.; Cerutti, F.; Chiaveri, E.; Colonna, N.; Cortés, G. P.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Davies, P. J.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dressler, R.; Ducasse, Q.; Dupont, E.; Durán, I.; Eleme, Z.; Fernández-Domíngez, B.; Ferrari, A.; Ferro-Gonçalves, I.; Finocchiaro, P.; Furman, V.; Garg, R.; Gawlik, A.; Gilardoni, S.; Göbel, K.; González-Romero, E.; Guerrero, C.; Gunsing, F.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Jiri, U.; Junghans, A.; Kadi, Y.; Käppeler, F.; Kimura, A.; Knapová, I.; Kokkoris, M.; Kopatch, Y.; Krtička, M.; Kurtulgil, D.; Ladarescu, I.; Lederer-Woods, C.; Lerendegui-Marco, J.; Lonsdale, S.-J.; Macina, D.; Manna, A.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Maugeri, E.; Mazzone, A.; Mendoza, E.; Michalopoulou, V.; Milazzo, P. M.; Millán-Callado, M. A.; Mingrone, F.; Moreno-Soto, J.; Musumarra, A.; Negret, A.; Ogállar, F.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Petrone, C.; Piersanti, L.; Pirovano, E.; Porras, I.; Praena, J.; Quesada, J. M.; Ramos Doval, D.; Reifarth, R.; Rochman, D.; Rubbia, C.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schumann, D.; Sekhar, A.; Smith, A. G.; Sosnin, N.; Sprung, P.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A. E.; Tassan-Got, L.; Thomas, B.; Torres-Sánchez, P.; Tsinganis, A.; Urlass, S.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T. J.; Žugec, P.

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

Publ.-Id: 31579

Status and perspectives of the neutron time-of-flight facility n_TOF at CERN

Chiaveri, E.; Aberle, O.; Alcayne, V.; Amaducci, S.; Andrzejewski, J.; Audouin, L.; Babiano-Suarez, V.; Bacak, M.; Barbagallo, M.; Bennett, S.; Berthoumieux, E.; Bosnar, D.; Brown, A. S.; Busso, M.; Caamaño, M.; Caballero, L.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Casanovas, A.; Cerutti, F.; Colonna, N.; Cortés, G. P.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Damone, L. A.; Davies, P. J.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dressler, R.; Ducasse, Q.; Dupont, E.; Durán, I.; Eleme, Z.; Fernández-Domíngez, B.; Ferrari, A.; Ferro-Gonçalves, I.; Finocchiaro, P.; Furman, V.; Garg, R.; Gawlik, A.; Gilardoni, S.; Göbel, K.; González-Romero, E.; Guerrero, C.; Gunsing, F.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Jiri, U.; Junghans, A.; Kadi, Y.; Käppeler, F.; Kimura, A.; Knapová, I.; Kokkoris, M.; Kopatch, Y.; Krtička, M.; Kurtulgil, D.; Ladarescu, I.; Lederer-Woods, C.; Lerendegui-Marco, J.; Lonsdale, S.-J.; Macina, D.; Manna, A.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Maugeri, E.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Michalopoulou, V.; Milazzo, P. M.; Millán-Callado, M. A.; Mingrone, F.; Moreno-Soto, J.; Musumarra, A.; Negret, A.; Ogállar, F.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Petrone, C.; Piersanti, L.; Pirovano, E.; Porras, I.; Praena, J.; Quesada, J. M.; Ramos Doval, D.; Reifarth, R.; Rochman, D.; Rubbia, C.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schumann, D.; Sekhar, A.; Smith, A. G.; Sosnin, N.; Sprung, P.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A. E.; Tassan-Got, L.; Thomas, B.; Torres-Sánchez, P.; Tsinganis, A.; Urlass, S.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T. J.; Žugec, P.

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

Publ.-Id: 31578

Measurement of the energy-differential cross-section of the 12C(n,p)12B and 12C(n,d)11B reactions at the n_TOF facility at CERN

Barbagallo, M.; Aberle, O.; Alcayne, V.; Amaducci, S.; Andrzejewski, J.; Audouin, L.; Babiano-Suarez, V.; Bacak, M.; Bennett, S.; Berthoumieux, E.; Bosnar, D.; Brown, A. S.; Busso, M.; Caamaño, M.; Caballero, L.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Casanovas, A.; Cerutti, F.; Chiaveri, E.; Colonna, N.; Cortés, G. P.; Cortés-Giraldo, M. A.; Cosentino, L.; Cristallo, S.; Damone, L. A.; Davies, P. J.; Diakaki, M.; Dietz, M.; Domingo-Pardo, C.; Dressler, R.; Ducasse, Q.; Dupont, E.; Durán, I.; Eleme, Z.; Fernández-Domíngez, B.; Ferrari, A.; Ferro-Gonçalves, I.; Finocchiaro, P.; Furman, V.; Garg, R.; Gawlik, A.; Gilardoni, S.; Göbel, K.; González-Romero, E.; Guerrero, C.; Gunsing, F.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Jiri, U.; Junghans, A.; Kadi, Y.; Käppeler, F.; Kimura, A.; Knapová, I.; Kokkoris, M.; Kopatch, Y.; Krtička, M.; Kurtulgil, D.; Ladarescu, I.; Lederer-Woods, C.; Lerendegui-Marco, J.; Lonsdale, S.-J.; Macina, D.; Manna, A.; Martínez, T.; Masi, A.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Maugeri, E.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Michalopoulou, V.; Milazzo, P. M.; Millán-Callado, M. A.; Mingrone, F.; Moreno-Soto, J.; Musumarra, A.; Negret, A.; Ogállar, F.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Petrone, C.; Piersanti, L.; Pirovano, E.; Porras, I.; Praena, J.; Quesada, J. M.; Ramos Doval, D.; Reifarth, R.; Rochman, D.; Rubbia, C.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schumann, D.; Sekhar, A.; Smith, A. G.; Sosnin, N.; Sprung, P.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A. E.; Tassan-Got, L.; Thomas, B.; Torres-Sánchez, P.; Tsinganis, A.; Urlass, S.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Woods, P. J.; Wright, T. J.; Žugec, P.

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

Publ.-Id: 31577

Measurement of the 242Pu(n, γ) cross section from thermal to 500 keV at the Budapest research reactor and CERN n_TOF-EAR1 facilities

Lerendegui-Marco, J.; Guerrero, C.; Mendoza, E.; Quesada, J. M.; Eberhardt, K.; Junghans, A.; Krtiička, M.; Belgya, T.; Maróti, B.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Balibrea, J.; Barbagallo, M.; Barros, S.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Furman, V.; Göbel, K.; García, A. R.; Gawlik, A.; Glodariu, T.; Gonçalves, I. F.; González-Romero, E.; Goverdovski, A.; Griesmayer, E.; Gunsing, F.; Harada, H.; Heftrich, T.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Knapova, I.; Kokkoris, M.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, J. I.; Praena, J.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vescovi, D.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Weiss, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.; The N_TOF Collaboration

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

Publ.-Id: 31576

Co(NO3)2 as an inverted umbrella-type chiral noncoplanar ferrimagnet

Danilovich, I. L.; Deeva, E. B.; Bukhteev, K. Y.; Vorobyova, A. A.; Morozov, I. V.; Volkova, O. S.; Zvereva, E. A.; Maximova, O. V.; Solovyev, I. V.; Nikolaev, S. A.; Phuyal, D.; Abdel-Hafiez, M.; Wang, Y. C.; Lin, J.-Y.; Chen, J. M.; Gorbunov, D.; Puzniak, K.; Lake, B.; Vasiliev, A. N.

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

Publ.-Id: 31575

Dataset for: Morphology of flashing feeds at critical fluid properties in larger pipes

Döß, A.; Schubert, M.; Hampel, U.

This data set contains cross-sectional averaged vapor fraction data obtained for flashing refrigerant in the horizontal feed section (inner pipe diameter of 200 mm) of the TERESA facility. The data was obtained with the Wire-mesh Sensor Framework GUI (Version 1.3.0). The archive 'void' contains .epst-files which are organized as a two column table (ASCII). The first column denotes the time step (in seconds), the second column is the cross-sectional averaged vapor fraction in percent.

Allocation of the files to the operational conditions is included separate .csv-file (overview.csv), which contains 12 columns for each measurement. Here the averaged values of the .epst-files are included as well.

In this study, two wire-mesh sensors were operated simultaneously. WMS1 (*_X_Sensor_1.epst) was located in an axial distance of L = 2.5 D from the flash nozzle and WMS2 (*_Y_Sensor_2.epst) was located L = 17.5 D away from the flash nozzle.  

Keywords: TERESA; Flashing feed; Wire-mesh sensor

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-10-01
    DOI: 10.14278/rodare.418
    License: CC-BY-4.0


Publ.-Id: 31573

Reducing entrainment in ultrafine particle flotation by selective flocculation of gangue material

Sygusch, J.; Rudolph, M.

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

Keywords: Ultrafine Particles; Flotation; Selective flocculation; Entrainment

  • Poster (Online presentation)
    10. ProcessNet-Jahrestagung und 34. DECHEMA-Jahrestagung der Biotechnologen 2020, 21.-24.09.2020, Online, Deutschland

Publ.-Id: 31571

Formation and crystallographic orientation of NiSi2-Si interfaces

Fuchs, F.; Khan, B.; Deb, D.; Pohl, D.; Schuster, J.; Weber, W. M.; Mühle, U.; Löffler, M.; Georgiev, Y. M.; Erbe, A.; Gemming, S.

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


  • Secondary publication expected

Publ.-Id: 31568

Monitoring laser-induced magnetization in FeRh by transient terahertz emission spectroscopy

Awari, N.; Semisalova, A.; Deinert, J.-C.; Lenz, K.; Lindner, J.; Fullerton, E.; Uhlir, V.; Li, J.; Clemens, B.; Carley, R.; Scherz, A.; Kovalev, S.; Gensch, M.

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

Keywords: Magnetization dynamics; terahertz; ultrafast; FeRh

Publ.-Id: 31565

Experimental data of the ROCOME2.3 experiment

Kliem, S.

The experiment ROCOM E2.3 represents a boron dilution event in a KONVOI-type pressurized lightwater reactor. It was conducted at room temperature with de-mineralized water without boric acid. Underborated water slugs were modelled by adding Ethanol in order to adjust a density difference of 1.22% with respect to the regular coolant inventory. At the beginning of the experiment, the slugs are enclosed between two valves in the cold legs of loops 1 and 2. The volume of the two water slugs accounts for 0.0576 m 3 (57.6 l) each and the slug fronts are located at 1.8 m upstream of the pressure vessel inlet nozzles. The experiment is started by opening the loop valves and running up the circulation pumps. The time dependency of the volumetric flow rates in all four coolant loops can be found in During the experiment, the mixing process was recorded by wire-mesh conductivity sensors at various positions within the coolant loops and the pressure vessel.  The nomenclature of the data files as well as the format of the tables are described in the accompanying document DataDescription_ROCOME23.pdf.

Keywords: boron dilution; coolant mixing; pressurized water reactor

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-25
    DOI: 10.14278/rodare.527
    License: CC-BY-4.0


Publ.-Id: 31562

Zur Untersuchung schwerer Erdalkalimetalle für die radiopharmazeutische Anwendung

Bauer, D.

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

Keywords: Radium-223; Barium-131; Makrozyklen; targetd Alpha-Therrapy

  • Doctoral thesis
    TU Dresden, 2020
    Mentor: PD Dr. habil. Constantin Mamat
    162 Seiten

Publ.-Id: 31560

Tailoring the Electronic and Magnetic Properties of Hematene by Surface Passivation: Insights from First-principles Calculations

Wei, Y.; Ghorbani Asl, M.; Krasheninnikov, A.

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

Keywords: Two-dimensional materials; Hematene; Surface Passivation; First-principles Calculations


  • Secondary publication expected from 24.09.2021

Publ.-Id: 31557

Anisotropy of the magnetocaloric effect: Example of Mn5Ge3

Maraytta, N.; Voigt, J.; Salazar Mejia, C.; Friese, K.; Scurschii, I.; Perßon, J.; Salman, S. M.; Brückel, T.

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

Publ.-Id: 31553

Pulsed laser deposition of Fe-oxypnictides: Co- and F-substitution

Haindl, S.; Sato, M.; Wurmehl, S.; Büchner, B.; Kampert, W. A. G.

The majority of thin film studies that were devoted to Fe-oxyarsenides has focused so far on F-substituted (i.e. indirectly electron doped) LnOFeAs (Ln = La, Nd, Sm). Here we turn our attention towards Co-substituted (i.e. directly electron doped) LaOFeAs and SmOFeAs in order to investigate its growth on different substrate materials by using pulsed laser deposition (PLD). We detected dominant LnOFeAs phase formation and discuss the occurrence of minor impurity phases in the different films on different substrates. The lack of a superconducting transition in LnOFe0.85Co0.15As films on MgO(100) could be due to strain, since we observe an onset of superconductivity in SmOFe1−xCoxAs (x = 0.07, 0.15) films on other oxide substrates. In addition, Co-substitution (i.e. within the Fe2As2 layers) and F-substitution (i.e. within the Ln2O2 layers) leading to direct and indirect electron doping respectively, appears for films deposited on CaF2 substrates. In contrast to the F-substituted but Co-free Fe-oxyarsenides, the co-doped SmO1−xFxFe0.85Co0.15As film has experimentally accessible upper critical fields down to the lowest temperatures and may serve as an ideal test bed for further theoretical modeling of Fe-oxyarsenides.

Publ.-Id: 31552

Preparation of γ-Al₂O₃/α-Al₂O₃ ceramic foams as catalyst carriers via the replica technique

Shumilov, V.; Kirilin, A.; Tokarev, A.; Boden, S.; Schubert, M.; Hampel, U.; Hupa, L.; Salmi, T.; Murzin, D. Y.

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

Keywords: γ-Al₂O₃/α-Al₂O₃; catalytic foams; macroporous ceramics; hydrogenation of ethylbenzoylformate

Publ.-Id: 31551

Single-Shot Measurement of Post-Pulse-GeneratedPre-Pulse in High-Power Laser Systems

Kon, A.; Nishiuchi, M.; Kiriyama, H.; Kando, M.; Bock, S.; Ziegler, T.; Püschel, T.; Zeil, K.; Schramm, U.; Kondo, K.

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

Keywords: laser pulse contrast; high-intensity lasers; B-integral

Publ.-Id: 31549

Supplementary simulations for laser foil experiments on TOD variation

Göthel, I.

Simulations made with PIConGPU in 2d geometry with a longitudinally modified gaussian laser on a foil.
The laser has been modified to reproduce the main features of the pulse shape seen in the experiments as a result of modifying TOD and GVD.
The three main features, which were enabled with varying strength in the simulations:
 - an exponential ramp on the timescale of 300fs before the gaussian main pulse
 - a postpulse with around 100fs delay and around 0.2 of the total pulse energy
 - a skewness of the gaussian - modelled by two gaussian halves for the rising and falling part

From the spectra of the accelerated protons the cutoff energy is measured. The main result is, that the variations of the spectra are much smaller than those observed in the experiments, suggesting more complex mechanisms than those modelled here.

Keywords: laser particle acceleration

  • Software in the HZDR data repository RODARE
    Publication date: 2020-09-22
    DOI: 10.14278/rodare.521
    License: CC-BY-4.0


Publ.-Id: 31548

Single-shot diagnostics development for high power laser driven relativistic plasma experiments at the Helmholtz-Zentrum Dresden-Rossendorf

Bock, S.; Püschel, T.; Helbig, U.; Gebhardt, R.; Oksenhendler, T.; Bernert, C.; Couperus Cabadağ, J. P.; Ziegler, T.; Schöbel, S.; Zeil, K.; Irman, A.; Toncian, T.; Cowan, T.; Schramm, U.

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

  • Invited lecture (Conferences) (Online presentation)
    CLEO 2020, 11.-15.05.2020, San Jose, California, USA

Publ.-Id: 31547

Control of magneto-optical properties of cobalt-layers by adsorption of α-helical polyalanine self-assembled monolayers

Sharma, A.; Matthes, P.; Soldatov, I.; Arekapudi, S. S. P. K.; Böhm, B.; Lindner, M.; Selyshchev, O.; Thi, N. H. N.; Mehring, M.; Tegenkamp, C.; Schulz, S. E.; Zahn, D. R. T.; Paltiel, Y.; Hellwig, O.; Salvan, G.

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

Publ.-Id: 31546

Fluid Mechanics of Liquid Metal Batteries

Weier, T.; Horstmann, G. M.; Landgraf, S.; Nimtz, M.; Personnettaz, P.; Weber, N.

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

Keywords: liquid metal batteries; electro-vortex flows; mass transfer; solutal convection

  • Invited lecture (Conferences) (Online presentation)
    Department Seminar Mechanical Engineering Department, 16.10.2020, Dearborn, MI, USA

Publ.-Id: 31544

Investigation of Mild Steel Corrosion in the Cement Production Associated with the Usage of Secondary Fuels

Thieme, M.; Bergmann, U.; Kiesewetter, A.; Wehry, T.; Potzger, K.; Zarzycki, A.; Marszalek, M.; Worch, H.

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

Keywords: Mössbauer spectroscopy; corrosion

Publ.-Id: 31541

CT-based attenuation correction of whole-body radiotherapy treatment positioning devices in PET/MRI hybrid imaging

Taeubert, L.; Berker, Y.; Beuthien-Baumann, B.; Hoffmann, A. L.; Troost, E. G. C.; Kachelrieß, M.; Gillmann, C.

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

Publ.-Id: 31536

Wafer-scale 4H-silicon carbide-on-insulator (4H–SiCOI) platform for nonlinear integrated optical devices

Yi, A.; Zheng, Y.; Huang, H.; Lin, J.; Yan, Y.; You, T.; Huang, K.; Zhang, S.; Shen, C.; Zhou, M.; Huang, W.; Zhang, J.; Zhou, S.; Ou, H.; Ou, X.

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

Publ.-Id: 31534

High carrier mobility epitaxially aligned PtSe2 films grown by one-zone selenization

Sojkova, M.; Dobročka, E.; Hutár, P.; Tašková, V.; Pribusová-Slušná, L.; Stoklas, R.; Píš, I.; Bondino, F.; Munnik, F.; Hulman, M.

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

Keywords: PtSe2; epitaxial films; Laue oscillations; Raman spectroscopy

Publ.-Id: 31532

The absence of metamictisation in natural monazite

Nasdala, L.; Akhmadaliev, S.; Burakov, B. E.; Chanmuang N, C.; Škoda, R.

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

Publ.-Id: 31530

Experimental gas phase hydrodynamic data of lab scale bubble column

Kipping, R.; Hampel, U.

For the investigation of bubble column hydrodynamics an experimental study using ultrafast electron beam X-ray tomography (UFXCT) has been carried out. Local hydrodynamic parameters were measured in a DN100 bubble column using two types of capillary gas sparger, which are named as 'Type A' and 'Type B' . Nitrogen is used as gas phase and deionized water as liquid phase. For Type B sparger additionally, experiments with sodium hydroxide of different concentrations are given. Experiments were carried out at two different measurement heights, which are located at 10 (L/D = 1) and 70 cm (L/D = 7) above the gas sparger

An additional readme.txt file provides all required information and is necessary for the interpretation of the experimental data.

Keywords: Bubble column hydrodynamics; Uniform bubbly flow; Ultrafast X-ray computed tomography; SPP1740

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-04-02
    DOI: 10.14278/rodare.282


Publ.-Id: 31529

Analytical Approach to Phonon Calculations in the SCC-DFTB Framework

Bacic, V.; Heine, T.; Kuc, A. B.

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


  • Secondary publication expected

Publ.-Id: 31528

Structural and chemical evolution of Au-silica core-shell nanoparticles during 20 keV helium ion irradiation: a comparison between experiment and simulation

Mousley, M.; Möller, W.; Philipp, P.; Hlawacek, G.; Wirtz, T.; Eswara, S.

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

Keywords: nanoparticles, ion irradiation, He-Ne microscope, computer simulation, TRI3DYN

Publ.-Id: 31526

Band structure of a HgTe-based three-dimensional topological insulator

Gospodaric, J.; Dziom, V.; Shuvaev, A.; Dobretsova, A. A.; Mikhailov, N. N.; Kvon, Z. D.; Novik, E. G.; Pimenov, A.

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

Publ.-Id: 31518

STRUctural MATerials research for safe Long Term Operation of LWR NPPs (STRUMAT-LTO) Work Package 3: Synergetic effects of Ni, Mn and Si on RPV embrittlement at high fluences

Ulbricht, A.

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

  • Lecture (Conference) (Online presentation)
    STRUMAT-LTO Kick-off Meeting, 07.-08.09.2020, online, online

Publ.-Id: 31517

Nanoindentation testing and TEM observations of irradiated F/M alloys

Bergner, F.

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

Keywords: Nanoindentation; TEM; Ferritic/martensitic steels; Ion irradiation; Irradiation hardening; Dislocation loops

  • Lecture (others) (Online presentation)
    ONLINE M4F Plenary Project Meeting, 16.-17.06.2020, Online, Online

Publ.-Id: 31516

ENTENTE WP3 Task 3.2: Task 3.2: Microstructural Examinations in RPV Steels and Model Alloys

Chekhonin, P.

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

Keywords: ENTENTE project

  • Lecture (Conference) (Online presentation)
    ENTENTE Kickoff Meeting, 09.-10.09.2020, Dresden, Germany

Publ.-Id: 31515

ENTENTE WP2 Task 2.4: Data Collection

Chekhonin, P.

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

Keywords: ENTENTE project

  • Lecture (Conference) (Online presentation)
    ENTENTE Kickoff Meeting, 09.-10.09.2020, Dresden, Germany

Publ.-Id: 31514

4 f spin driven ferroelectric-ferromagnetic multiferroicity in PrMn2O5 under a magnetic field

Chattopadhyay, S.; Balédent, V.; Panda, S. K.; Yamamoto, S.; Duc, F.; Herrmannsdörfer, T.; Uhlarz, M.; Gottschall, T.; Mathon, O.; Wang, Z.

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


Publ.-Id: 31512

Videos for: Characterization of blood coagulation dynamics and oxygenation in ex‐vivo retinal vessels by fluorescence hyperspectral imaging

Podlipec, R.

Videos are showing experimental results of the blood coagulation dynamics study in ex‐vivo retinal vessels.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-08
    DOI: 10.14278/rodare.511
    License: CC-BY-4.0


Publ.-Id: 31511

Images for: Characterization of blood coagulation dynamics and oxygenation in ex-vivo retinal vessels by fluorescence hyperspectral imaging

Podlipec, R.

Images for the manuscript/paper titled Characterization of blood coagulation dynamics and oxygenation in ex-vivo retinal vessels by fluorescence hyperspectral imaging

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-08
    DOI: 10.14278/rodare.509
    License: CC-BY-4.0


Publ.-Id: 31510

HIFIS - Platform, Training and Support for a Sustainable Software Development

Huste, T.

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

Keywords: HIFIS; Software Engineering; Cloud; Consulting; Education; Training

  • Invited lecture (Conferences) (Online presentation)
    Wissensaustausch-Workshop Software Engineering (WAW SE VII), 09.09.2020, Online, Deutschland

Publ.-Id: 31508

Chronic Inflammation Prediction for Inhaled Particles, the Impact of Material Cycling and Quarantining in the Lung Epithelium

Podlipec, R.

Correlative optical (STED) and ion (HIM) high-resolution images of lung epithelial cells interacting with metal oxide nanoparticles where the mechanism of material cycling and quarantining is studied.

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-08
    DOI: 10.14278/rodare.513
    License: CC-BY-4.0


Publ.-Id: 31505

Generating a tide-like flow in a cylindrical vessel by electromagnetic forcing - datasets and software

Jüstel, P.; Röhrborn, S.; Galindo, V.; Schindler, F.

The two 7z Archives contain experimental data and the corresponding evaluation software, as well as the code and setup of the numerical part of the paper "Generating a tide-like flow in a cylindrical vessel by electromagnetic forcing".

Keywords: Ultrasound-Doppler-Velocimetry (UDV); Python; openFOAM

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-08
    DOI: 10.14278/rodare.507
    License: CC-BY-4.0


Publ.-Id: 31502

Effect of nanoscale surface topography on the adsorption of globular proteins

Yang, Y.; Yu, M.; Böke, F.; Qin, Q.; Hübner, R.; Knust, S.; Schwiderek, S.; Grundmeier, G.; Fischer, H.; Keller, A.

Protein adsorption is the initial step in the response of biological systems to artificial surfaces and thus a ubiquitous phenomenon in biomedicine and tissue engineering. Here, we investigate the adsorption of the three globular proteins myoglobin (MGB), thyroglobulin (TGL), and bovine serum albumin (BSA) at flat and nanorippled SiOx/Si and TiOx/Ti surfaces. Despite having lateral and vertical dimensions of only about 30 nm and less than 2 nm, respectively, these nanoripples influence protein adsorption and adsorption-induced protein denaturation in a highly protein- and material-specific way. Adsorption of small, positively charged MGB results in preferential protein alignment along the nanoripples on both oxide surfaces. The larger and strongly negatively charged TGL forms layers of similar thickness on all four surfaces except the nanorippled TiOx/Ti surface. Here, a smaller layer thickness is attributed to different denaturation states of the adsorbed proteins. Similarly, the smaller and less negatively charged BSA shows different degrees of denaturation on the flat and rippled SiOx/Si surfaces. Our results thus demonstrate that topographic surface features with vertical dimensions well below 10 nm may have a surprisingly strong effect on protein adsorption and thus need to be considered in the interaction of biological systems even with apparently flat surfaces.

Keywords: Protein adsorption; Biomaterials; Biointerfaces; Nanopatterning; Surface topography

Publ.-Id: 31499

Interfacial redox reactions, X-ray absorption spectroscopy, and how they can contribute to the safety of radioactive-waste repositories

Scheinost, A. C.

The safe enclosure of nuclear waste in deep-geological repositories is not only a challenge for engineers to build it, but also for geoscientist to predict that the eventually forming leaks do not lead to a contamination of the biosphere – and this for a period of up to one million years, as dictated by the slow decay of long-lived radionuclides. A precise, molecular-scale understanding of the retention processes at water/mineral interfaces is one of the fundamental requirements to improve the prediction of radionuclide migration by (reactive) transport models. These processes include physical and chemical sorption, and structural incorporation by existing or neoforming mineral phases. Interfacial redox reactions with structural or sorbed Fe(II) play a pivotal role during these processes, since Fe(II) is the most ubiquitous redox agent in the deep anoxic underground, and is released from steel canisters corroding under radiolytic H2 production. Synchrotron-based X-ray absorption spectroscopy is ideally suited to elucidate such processes, since it provides information on oxidation state, bonding and short-range structure of an element at the same time, and this in situ due to the high penetration depth and element-specifity of the used synchrotron radiation. I will show selected examples for a range of metals occurring in radwaste (Tc, U, Np, Pu, Am), while the observed processes are transferable to many other metals and metalloids of general geochemical interest.

Keywords: nuclear waste; XAFS; Redox

  • Invited lecture (Conferences) (Online presentation)
    GFZ Talk, 17.09.2020, Postdam, Germany

Publ.-Id: 31498

Electrochemical detection of ascorbic acid in artificial sweat using a flexible alginate/CuO-modified electrode

Ibarlucea, B.; Pérez, R. A.; Belyaev, D.; Baraban, L.; Cuniberti, G.

A flexible sensor is presented for electrochemical detection of ascorbic acid in sweat based on single-step modified gold microelectrodes. The modification consists of electrodeposition of alginate membrane with trapped CuO nanoparticles. The electrodes are fabricated at a thin polyimide support and the soft nature of the membrane can withstand mechanical stress beyond requirements for skin monitoring. After characterization of the membrane via optical and scanning electron microscopy and cyclic voltammetry, the oxidative properties of CuO are exploited toward ascorbic acid for amperometric measurement at micromolar levels in neutral buffer and acidic artificial sweat, at ultralow applied potential (− 5 mV vs. Au pseudo-reference electrode). Alternatively, measurement of the horizontal shift of redox peaks by cyclic voltammetry is also possible. Obtaining a limit of detection of 1.97 μM, sensitivity of 0.103 V log (μM)−1 of peak shift, and linear range of 10–150 μM, the effect of possible interfering species present in sweat is minimized, with no observable cross-reaction, thus maintaining a high degree of selectivity despite the absence of enzymes in the fabrication scheme. With a lateral flow approach for sample delivery, repeated measurements show recovery in few seconds, with relative standard deviation of about 20%, which can serve to detect increased loss or absence of vitamin, and yet be improved in future by optimized device designs. This sensor is envisioned as a promising component of wearable devices for e.g. non-invasive monitoring of micronutrient loss through sweat, comprising features of light weight, low cost, and easy fabrication needed for such application.

Publ.-Id: 31497

Intracavity third-harmonic generation in Si:B pumped by intense terahertz pulses

Meng, F.; Thomson, M. D.; Ul-Islam, Q.; Klug, B.; Pashkin, O.; Schneider, H.; Roskos, H. G.

Raw experimental data: emission interferograms, FEL spectra and FEL spots

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-03
    DOI: 10.14278/rodare.502


Publ.-Id: 31496

Data for: Lattice dynamics and ultrafast energy flow between electrons, spins, and phonons in a 3d ferromagnet

Zahn, D.; Jakobs, F.; William Windsor, Y.; Seiler, H.; Vasileiadis, T.; Butcher, T. A.; Qi, Y.; Engel, D.; Atxitia, U.; Vorberger, J.; Ernstorfer, R.

The ultrafast dynamics of magnetic order in a ferromagnet are governed by the interplay between electronic, magnetic and lattice degrees of freedom. In order to obtain a microscopic understanding of ultrafast demagnetization, information on the response of all three subsystems is required. A consistent description of demagnetization and microscopic energy flow, however, is still missing. Here, we combine a femtosecond electron diffraction study of the ultrafast lattice response of nickel to laser excitation with ab initio calculations of the electron-phonon interaction and energy conserving atomistic spin dynamics simulations. Our model is in agreement with the observed lattice dynamics and previously reported electron and magnetization dynamics. Our approach reveals that the spin system is the dominating heat sink in the initial few hundreds of femtoseconds and implies a transient non-thermal state of the spins. Our results provide a clear picture of the microscopic energy flow between electronic, magnetic and lattice degrees of freedom on ultrafast timescales and constitute a foundation for theoretical descriptions of demagnetization that are consistent with the dynamics of all three subsystems.

Keywords: magnetization; relaxation; laser; phonon; spin; DFT; electron beam; femtosecond

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-09-03
    DOI: 10.14278/rodare.500
    License: CC-BY-4.0


Publ.-Id: 31495

Water-Window X-Ray Pulses from a Laser-Plasma Driven Undulator

Maier, A. R.; Kajumba, N.; Guggenmos, A.; Werle, C.; Wenz, J.; Delbos, N.; Zeitler, B.; Dornmair, I.; Schmidt, J.; Gullikson, E. M.; Krausz, F.; Schramm, U.; Kleineberg, U.; Karsch, S.; Gruner, F.

Femtosecond (fs) x-ray pulses are a key tool to study the structure and dynamics of matter on its natural length and time scale. To complement radio-frequency accelerator-based large-scale facilities, novel laser-based mechanisms hold promise for compact laboratory-scale x-ray sources. Laser-plasma driven undulator radiation in particular offers high peak-brightness, optically synchronized few-fs pulses reaching into the few-nanometer (nm) regime. To date, however, few experiments have successfully demonstrated plasma-driven undulator radiation. Those that have, typically operated at single and comparably long wavelengths. Here we demonstrate plasma-driven undulator radiation with octave-spanning tuneability at discrete wavelengths reaching from 13 nm to 4 nm. Studying spontaneous undulator radiation is an important step towards a plasma-driven free-electron laser. Our specific setup creates a photon pulse, which closely resembles the plasma electron bunch length and charge profile and thus might enable novel methods to characterize the longitudinal electron phase space.

Keywords: LWFA


Publ.-Id: 31494

Worldline master formulas for the dressed electron propagator, part 1: Off-shell amplitudes

Ahmadiniaz, N.; Guzman, V. M. B.; Bastianelli, F.; Corradini, O.; Edwards, J. P.; Schubert, C.

In the firrst-quantised worldline approach to quantum field theory, a long-standing problem has been to extend this formalism to amplitudes involving open fermion lines while maintaining the efficiency of the well-tested closed-loop case. In the present series of papers, we develop a suitable formalism for the case of quantum electrodynamics (QED) in vacuum (part one and two) and in a constant external electromagnetic field (part three), based on second-order fermions and the symbol map. We derive this formalism from standard field theory, but also give an alternative derivation intrinsic to the worldline theory. In this first part, we use it to obtain a Bern-Kosower type master formula for the fermion propagator, dressed with N photons in configuration as well as in momentum space.

Keywords: Worlline formalism; QED; Scattering Amplitudes; Gauge Symmetry


Publ.-Id: 31493

Small-scale diagenetic facies heterogeneity controls porosity and permeability pattern in reservoir sandstones

Heidsiek, M.; Butscher, C.; Blum, P.; Fischer, C.

The fluvial-aeolian Upper Rotliegend sandstones from the Bebertal outcrop (Flechtingen High, Germany) are the famous reservoir analog for the deeply-buried Upper Rotliegend gas reservoirs of the Southern Permian Basin (SPB). While most diagenetic and reservoir quality investigations are conducted on a meter scale, there is an emerging consensus that significant reservoir heterogeneity is inherited from diagenetic complexity at smaller scales. In this study, we utilize information about diagenetic products and processes at the pore-and plug-scale and analyze their impact on the heterogeneity of porosity, permeability, and cement patterns. Eodiagenetic poikilitic calcite cements, illite/iron oxide grain coatings, and the amount of infiltrated clay are responsible for mm-to cm-scale reservoir heterogeneities in the Parchim formation of the Upper Rotliegend sandstones. Using the Petrel E&P software platform, spatial fluctuations and spatial variations of permeability, porosity, and calcite cements are modeled and compared, offering opportunities for predicting small-scale reservoir rock properties based on diagenetic constraints.

Keywords: Sandstone diagenesis, calcite cement, reservoir quality, high-resolution diagenetic modeling, Upper Rotliegend sandstone

Publ.-Id: 31490

70 THz bandwidth from a Au-implanted Ge photoconductive emitter pumped by a modelocked Er:fibre laser

Singh, A.; Winnerl, A. P. S.; Welsch, M.; Beckh, C.; Sulzer, P.; Leitenstorfer, A.; Helm, M.; Schneider, H.

Germanium is a nonpolar semiconductor with missing one-phonon absorption. The absence of a Reststrahlen band enables the generation of a gapless THz spectrum spreading up to 13 THz [1], limited only by the duration of the excitation and detection laser pulses. However, in spite of other promising properties including low bandgap and small effective mass, the long, µs-scale recombination time arising from the indirect bandgap of intrinsic germanium has been prohibitive for practical application as photoconductive THz emitters. Although not essential for broadband THz emission, shorter recombination times are necessary to ensure complete carrier recombination between subsequent laser pulses and to make these emitters compatible with standard modelocked laser systems operating at pulse repetition rates up to hundreds of MHz.
By introducing deep traps into germanium via gold implantation, we have reduced the carrier lifetime to sub-nanosecond values. Fabricated on this Au-implanted Ge material, we have demonstrated a photoconductive THz antenna which is compatible with modelocked fibre lasers operating at wavelengths of 1.1 and 1.55 m and with pulse repetition rates of 78 MHz [2] and potentially up to several hundreds of MHz. Reaching up to 70 THz bandwidth, which is almost one order of magnitude higher than that of existing state-of–the-art photoconductive THz emitters fabricated on GaAs or InGaAs, our approach points towards the possibility of compact, high-bandwidth THz photonic devices compatible with Si CMOS technology.
[1] A. Singh et al., ACS Photonics 5, 2718 (2018).
[2] A. Singh et al., Light Science & Applications 9, 30 (2020).

  • Invited lecture (Conferences) (Online presentation)
    SPIE Optics + Photonics Digital Forum, 24.-28.08.2020, San Diego, USA

Publ.-Id: 31489

THz nonlinear electronic response in GaAs/InGaAs semiconductor nanowires

Schneider, H.

This presentation reviews some recent experiments using free-electron-laser-based narrow-band as well as tabletop-laser-based single-cycle terahertz (THz) fields for exploring electronic properties in semiconducting GaAs/InGaAs core/shell nanowires (NW) [1]. In undoped NW, charge carriers are optically excited by near-infrared pulses and probed by strong single-cycle THz fields up to 0.6 MV/cm. The photoexcited charge carriers exhibit a pronounced plasmon resonance, which undergoes a systematic redshift and a suppression of its spectral weight, which indicates a drop of the electron mobility at the highest fields to about half of the original value [2]. In n-type NWs, intense narrowband THz excitation causes a nonlinear plasmonic response, which manifests itself by a similar pronounced red shift of the plasma resonance. This nonlinearity is investigated by scattering-type scanning near-field infrared microscopy on individual NWs. For NW doped with Si to a concentration of 9x10^18 cm^-3, a spectrally sharp plasma resonance, located at a photon energy of 125 meV for weak excitation, undergoes a power-dependent redshift to about 95 meV [3]. In these experiments, the observed behavior is attributed to a pronounced increase of the average electron effective mass caused by transient carrier heating and electron intervalley transfer. The results quantify the nonlinear transport regime in GaAs-based nanowires and show their high potential for development of nanodevices operating at THz frequencies.
[1] L. Balaghi et al., Widely tunable GaAs band gap via strain engineering in core/shell nanowires, Nature Comm. 10, 2793 (2019)
[2] R. Rana et al., Nonlinear terahertz field-induced charge transport and transferred-electron effect in InGaAs nanowires, Nano Lett. 20, 3225 (2020)
[3] D. Lang et al., Nonlinear plasmonic response of doped nanowires observed by infrared nanospectroscopy, Nanotechnol. 30, 084003 (2019)

  • Invited lecture (Conferences) (Online presentation)
    Synchrotron and Free electron laser Radiation: generation and application (SFR-2020), 13.-16.07.2020, Novosibirsk, Russische Föderation

Publ.-Id: 31488

Ion-implanted Ge photoconductive antennae for terahertz emission

Schneider, H.

This talk does not have an abstract.

  • Invited lecture (Conferences)
    Radiation Effects of Materials and Devices (REMD-2020), 12.-15.01.2020, Harbin, China

Publ.-Id: 31487

Non-monotonic pressure dependence of high-field nematicity and magnetism in CeRhIn5

Helm, T.; Grockowiak, A. D.; Balakirev, F. F.; Singleton, J.; Betts, J. B.; Shirer, K. R.; König, M.; Förster, T.; Bauer, E. D.; Ronning, F.

CeRhIn5 provides a textbook example of quantum criticality in a heavy fermion system: Pressure suppresses local-moment antiferromagnetic (AFM) order and induces superconductivity in a dome around the associated quantum critical point (QCP) near pc ≈ 23 kbar. Strong magnetic fields also suppress the AFM order at a field-induced QCP at Bc ≈ 50 T. In its vicinity, a nematic phase at B* ≈ 28 T characterized by a large in-plane resistivity anisotropy emerges. Here, we directly investigate the interrelation between these phenomena via magnetoresistivity measurements under high pressure. As pressure increases, the nematic transition shifts to higher fields, until it vanishes just below p. While pressure suppresses magnetic order in zero field as pc is approached, we find magnetism to strengthen under strong magnetic fields due to suppression of the Kondo effect. We reveal a strongly nonmean-field-like phase diagram, much richer than the common local-moment description of CeRhIn would suggest.

Publ.-Id: 31486

Determination of the crystal field parameters in SmFe11Ti

Diop, L. V. B.; Kuz'Min, M. D.; Scurschii, I.; Skokov, K. P.; Radulov, I. A.; Gutfleisch, O.

The magnetization of SmFe11Ti single crystals has been measured along the principal crystallographic directions in steady (14 T) and pulsed (43 T) magnetic fields. The fourfold symmetry axis [001] is an easy magnetization direction. The magnetization curves measured in directions perpendicular to [001] are remarkable in two ways: (i) They do not depend on orientation of H within the basal plane; (ii) at low temperature they are S shaped, with an inflection point at about 0.6 times saturation magnetization. These two facts enable us to conclude that three out of five crystal field parameters of SmFe11Ti are negligibly small; only A0 2 and A0 6 are essentially nonzero. A comparison with an isomorphous compound DyFe11Ti reveals a dramatic disparity of their crystal fields, especially as regards A4 4, nearly zero in SmFe11Ti but outstandingly large in DyFe11Ti.

Publ.-Id: 31485

Extremely well isolated two-dimensional spin-1/2 antiferromagnetic Heisenberg layers with a small exchange coupling in the molecular-based magnet CuPOF

Opherden, D.; Nizar, N.; Richardson, K.; Monroe, J. C.; Turnbull, M. M.; Polson, M.; Vela, S.; Blackmore, W. J. A.; Goddard, P. A.; Singleton, J.; Choi, E. S.; Xiao, F.; Williams, R. C.; Lancaster, T.; Pratt, F. L.; Blundell, S. J.; Scurschii, I.; Uhlarz, M.; Ponomaryov, O.; Zvyagin, S.; Wosnitza, J.; Baenitz, M.; Heinmaa, I.; Stern, R.; Kühne, H.; Landee, C. P.

We report on a comprehensive characterization of the newly synthesized Cu2+-based molecular magnet [Cu(pz)2 (2-HOpy)2](PF6)2 (CuPOF), where pz = C4H4N2 and 2-HOpy = C5H4NHO. From a comparison of theoretical modeling to results of bulk magnetometry, specific heat, μ+SR, ESR, and NMR spectroscopy, this material is determined as an excellent realization of the two dimensional square-lattice S = 1/2 antiferromagnetic Heisenberg model with a moderate intraplane nearest-neighbor exchange coupling of J/kB = 6.80(5) K, and an extremely small interlayer interaction of about 1 mK. At zero field, the bulk magnetometry reveals a temperature-driven crossover of spin correlations from isotropic to XY type, caused by the presence of a weak intrinsic easy-plane anisotropy. A transition to long-range order, driven by the low-temperature XY anisotropy under the influence of the interlayer coupling, occurs at TN = 1.38(2) K, as revealed by μ+SR. In applied magnetic fields, our 1H-NMR data reveal a strong increase of the magnetic anisotropy, manifested by a pronounced enhancement of the transition temperature to commensurate long-range order at TN = 2.8 K and 7 T.


Publ.-Id: 31484

Changes in elastic moduli as evidence for quadrupolar ordering in the rare-earth frustrated magnet Tb2Ti2O7

Gritsenko, Y.; Mombetsu, S.; Cong, P. T.; Stöter, T.; Green, E. L.; Salazar Mejia, C.; Wosnitza, J.; Ruminy, M.; Fennell, T.; Zvyagin, A. A.; Zherlitsyn, S.; Kenzelmann, M.

Numerous materials feature unexplained phases with invisible or hidden order of electronic origin. A particularly mysterious case is that of Tb2Ti2O7, which avoids magnetic order to the lowest temperatures, but nevertheless has an unexplained second-order phase transition near T = 0.5 K. Our ultrasound measurements of Tb2Ti2O7 provide direct evidence of a huge softening followed by strong hardening of the structural lattice below T = 0.5 K. In the absence of magnetic order at this temperature, our results provide conclusive evidence for the proposed quadrupolar order and emphasize the importance of higher-order multipolar interactions in rare-earth frustrated magnets.


Publ.-Id: 31483

How public health services pay for radiotherapy in Europe: an ESTRO-HERO analysis of reimbursement

Lievens, Y.; Defourny, N.; Corral, J.; Gasparotto, C.; Grau, C.; Borras, J.; Chauvet, B.; Coffey, M.; Coza, O.; Daisne, J.; Hadjieva, T.; Jarusevicius, L.; Karadjinovic, V.; Kouloulias, V.; Kozma, E.; Kristensen, B.; Lopez, A.; Mohammed, N.; Petera, J.; Rolles, M.; Roques, T.; Russi, E.; Sedlmayer, F.; Slobina, E.; Smichkoska, S.; Takácsi-Nagy, Z.; Trigo, L.; Troost, E. G. C.; Untereiner, M.; Valgma, M.; van Loon, J.

Reimbursement is a key factor in defining which resources are made available to ensure quality, efficiency, availability,
and access to specific health-care interventions. This Policy Review assesses publicly funded radiotherapy
reimbursement systems in Europe. We did a survey of the national societies of radiation oncology in Europe, focusing
on the general features and global structure of the reimbursement system, the coverage scope, and level for typical
indications. The annual expenditure covering radiotherapy in each country was also collected. Most countries have a
predominantly budgetary-based system. Variability was the major finding, both in the components of the treatment
considered for reimbursement, and in the fees paid for specific treatment techniques, fractionations, and indications.
Annual expenses for radiotherapy, including capital investment, available in 12 countries, represented between 4·3%
and 12·3% (average 7·8%) of the cancer care budget. Although an essential pillar in multidisciplinary oncology,
radiotherapy is an inexpensive modality with a modest contribution to total cancer care costs. Scientific societies and
policy makers across Europe need to discuss new strategies for reimbursement, combining flexibility with incentives
to improve productivity and quality, allowing radiation oncology services to follow evolving evidence.

Publ.-Id: 31479

Room-Temperature Infrared Photoresponse from Ion Beam–Hyperdoped Silicon

Wang, M.; Berencen, Y.

Room-temperature broadband infrared photoresponse in Si is of great interest for the development of on-chip complementary metal-oxide-semiconductor (CMOS)-compatible photonic platforms. One effective approach to extend the room-temperature photoresponse of Si to the mid-infrared range is the so-called hyperdoping. This consists of introducing deep-level impurities into Si to form an intermediate band within its bandgap enabling a strong intermediate band-mediated infrared photoresponse.Typically, impurity concentrations in excess of the equilibrium solubility limit can be introduced into the Si host either by pulsed laser melting of Si with a gas-phase impurity precursor, by pulsed laser mixing of a thin-film layer of impurities atop the Si surface or by ion implantation followed by a sub-second annealing step. In this review, a conspectus of the current status of room-temperature infrared photoresponse in hyperdoped Si by ion implantation followed by nanosecond-pulsed laser annealing is provided. The possibilities of achieving room-temperature broadband infrared photoresponse in ion beam-hyperdoped Si with different deep-level impurities are discussed in terms of material fabrication and device performance. The thermal stability of hyperdoped Si with deep-level impurities is addressed with special emphasis on the structural and the opto-electronic material properties. The future perspectives of achieving room-temperature Si-based broadband infrared photodetectors are outlined.

Publ.-Id: 31477

Critical behavior of the insulator-to-metal transition in Te-hyperdoped Si

Wang, M.; Debernardi, A.; Zhang, W.; Xu, C.; Yuan, Y.; Xie, Y.; Berencén, Y.; Prucnal, S.; Helm, M.; Zhou, S.

Hyperdoping Si with chalcogens is a topic of great interest due to the strong sub-band-gap absorption exhibited by the resulting material, which can be exploited to develop broadband room-temperature infrared photodetectors using fully Si-compatible technology. Here, we report on the critical behavior of the impurity-driven insulator-tometal transition in Te-hyperdoped Si layers fabricated via ion implantation followed by nanosecond pulsed-laser melting. Electrical transport measurements reveal an insulator-to-metal transition, which is also confirmed and understood by density functional theory calculations. We demonstrate that the metallic phase is governed by a power-law dependence of the conductivity at temperatures below 25 K, whereas the conductivity in the insulating phase is well described by a variable-range hopping mechanism with a Coulomb gap at temperatures in the range of 2–50 K. These results show that the electron wave function in the vicinity of the transition is strongly affected by the disorder and the electron-electron interaction.


Publ.-Id: 31476

Phthalocyanine-Based 2D Conjugated Metal-Organic Framework Nanosheets for High-Performance Micro-Supercapacitors

Wang, M.; Shi, H.; Zhang, P.; Liao, Z.; Wang, Mao; Zhong, H.; Schwotzer, F.; Shaygan Nia, A.; Zschech, E.; Zhou, S.; Kaskel, S.; Dong, R.; Feng, X.

2D conjugated metal-organic frameworks (2D c-MOFs) are emerging as a novel class of conductive redox-active materials for electrochemical energy storage. However, developing 2D c-MOFs as flexible thin-flm electrodes have been largely limited, due to the lack of capability of solution-processing and integration into nanodevices arising from the rigid powder samples by solvothermal synthesis. Here, the synthesis of phthalocyanine-based 2D c-MOF (Ni2[CuPc(NH)8]) nanosheets through ball milling mechanical exfoliation method are reported. The nanosheets feature with average lateral size of ≈160 nm and mean thickness of ≈7 nm (≈10 layers), and exhibit high crystallinity and chemical stability as well as a p-type semiconducting behavior with mobility of ≈1.5 cm2 V−1 s−1 at room temperature. Benefting from the ultrathin feature, the nanosheets allow high utilization of active sites and facile solution-processability. Thus, micro-supercapacitor (MSC) devices are fabricated mixing Ni2[CuPc(NH)8] nanosheets with exfoliated graphene, which display outstanding cycling stability and a high areal capacitance up to 18.9 mF cm−2; the performance surpasses most of the reported conducting polymers-based and 2D materials-based MSCs.

Publ.-Id: 31475

Ultrathin two-dimensional conjugated metal–organic framework single-crystalline nanosheets enabled by surfactant-assisted synthesis

Wang, Z.; Wang, G.; Qi, H.; Wang, M.; Wang, M.; Park, S.; Wang, H.; Yu, M.; Kaiser, U.; Fery, A.; Zhou, S.; Dong, R.; Feng, X.

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) have recently emerged for potential applications in (opto-)electronics, chemiresistive sensing, and energy storage and conversion, due to their excellent electrical conductivity, abundant active sites, and intrinsic porous structures. However, developing ultrathin 2D c-MOF nanosheets (NSs) for facile solution processing and integration into devices remains a great challenge, mostly due to unscalable synthesis, low yield, limited lateral size and low crystallinity.
Here, we report a surfactant-assisted solution synthesis toward ultrathin 2D c-MOF NSs, including HHBCu (HHB ¼ hexahydroxybenzene), HHB-Ni and HHTP-Cu (HHTP ¼ 2,3,6,7,10,11-hexahydroxytriphenylene). For the first time, we achieve single-crystalline HHB-Cu(Ni) NSs featured with a thickness of 4–5 nm (~8–10 layers) and a lateral size of 0.25–0.65 mm2, as well as single-crystalline HHTP-Cu NSs with a thickness of ~5.1 + 2.6 nm (~10 layers) and a lateral size of 0.002–0.02 mm2.Benefiting from the ultrathin feature, the synthetic NSs allow fast ion diffusion and high utilization of active sites. As a proof of concept, when serving as a cathode material for Li-ion storage, HHB-Cu NSs
deliver a remarkable rate capability (charge within 3 min) and long-term cycling stability (90% capacity retention after 1000 cycles), superior to the corresponding bulk materials and other reported MOF cathodes.

Publ.-Id: 31474

How robust are landslide susceptibility estimates?

Ozturk, U.; Pittore, M.; Behling, R.; Roessner, S.; Andreani, L.; Korup, O.

Much of contemporary landslide research is concerned with predicting and mapping susceptibility to slope failure. Many studies rely on generalised linear models with environmental predictors that are trained with data collected from within and outside of the margins of mapped landslides. Whether and how the performance of these models depends on sample size, location, or time remains largely untested. We address this question by exploring the sensitivity of a multivariate logistic regression—one of the most widely used susceptibility models—to data sampled from different portions of landslides in two independent inventories (i.e. a historic and a multi-temporal) covering parts of the eastern rim of the Fergana Basin, Kyrgyzstan. We find that considering only areas on lower parts of landslides, and hence most likely their deposits, can improve the model performance by >10% over the reference case that uses the entire landslide areas, especially for landslides of intermediate size. Hence, using landslide toe areas may suffice for this particular model and come in useful where landslide scars are vague or hidden in this part of Central Asia. The model performance marginally varied after progressively updating and adding more landslides data through time. We conclude that landslide susceptibility estimates for the study area remain largely insensitive to changes in data over about a decade. Spatial or temporal stratified sampling contributes only minor variations to model performance. Our findings call for more extensive testing of the concept of dynamic susceptibility and its interpretation in data-driven models, especially within the broader framework of landslide risk assessment under environmental and land-use change.

Keywords: landslide susceptibility; logistic regression; Southern Kyrgyzstan; Landslide inventory; Remote sensing

Publ.-Id: 31472

Ferromagnetism in B2-Ordered Alloys Induced via Lattice Defects

Bali, R.

This chapter considers the case of B2-ordered alloys that are initially non-ferromagnetic and where the introduction of lattice defects can cause the onset of ferromagnetism. This disorder-induced ferromagnetism is confined to the regions where the defects are concentrated. In general, the lattice can be thermally re-ordered, removing the defects and erasing the magnetized regions. Using B2 Fe60Al40 thin films as a prototype, the use of ion irradiation as well as pulsed laser irradiation for inducing antisite defects in the crystalline lattice is demonstrated. Ion beams can be applied as broad beams in combination with shadow masks for printing magnetic patterns over large areas, or focused down to approximately nanometer diameters for stylus-like writing of nanomagnets of desired geometries. The patterning resolution is limited by the lateral scattering of ions and can be estimated by semi-empirical modelling, described in this chapter. In the case of laser pulsing, disordering can be induced at thin film surfaces for pulse fluences above the melting threshold. Pulsing below the threshold can lead to surface re-ordering, erasing the magnetic regions and achieving all-laser re-writeable patterning. Localized disordering of B2 ordered systems thus enables a versatile path to embedding highly resolved non-volatile magnets at room temperature, with potential in magnetic device applications.

  • Book chapter
    Francis Chi-Chung Ling, Shengqiang Zhou, Andrej Kuznetsov: Defects in Functional Materials, Hong Kong: World Scientific Publishing Co Pte Ltd, 2020, 978-981-120-316-9
    DOI: 10.1142/11352

Publ.-Id: 31471

Normal tissue reaction following proton irradiation of the mouse brain

Beyreuther, E.; Suckert, T.; Müller, J.; Azadegan, B.; Bodenstein, E.; Haase, R.; Schürer, M.; Krause, M.; Lühr, A.; von Neubeck, C.; Dietrich, A.

Background: Due to the beneficial inverse physical depth-dose profile, proton radiotherapy (PT) offers the potential to reduce normal tissue toxicity by depositing the maximum dose within the tumor volume while sparing the surrounding tissue. However, range uncertainties and necessary clinical safety margins in combination with varying relative biological effectiveness may result in a critical dose in the normal tissue. Dedicated preclinical studies are needed to assess and better understand potential adverse effects of PT and to develop potential biomarkers and countermeasures for backtranslation into clinics.
For this purpose, a high-precision image-guided proton irradiation setup for small animals was established at the University Proton Therapy Dresden that mimics the clinical workflow, including pre-treatment imaging, treatment planning and image-guided brain irradiation.
The right hippocampus of C57BL/6 and C3H/HeN mice was irradiated to study the dose- and time-dependent radiation response of mouse brain tissue after short or long-term follow-up analysis. A Monte Carlo model of the proton beam was designed in the simulation toolkit TOPAS to calculate the dose distributions in vivo and to correlate the outcome with proton dose and LET.
The geometric accuracy of proton irradiation, detailed dose simulations on mouse CT and cell-based assessment enable a biologically and spatially resolved analysis of short-term radiation response and RBE. In addition, the long-term follow up over six month provides first insights into the formation of normal tissue damage in mouse brain after PT.

  • Lecture (Conference) (Online presentation)
    digital-ERRs, 13.-17.09.2020, Lund, Sweden

Publ.-Id: 31470

Damages induced by synchrotron radiation-based X-ray microanalysis in chrome yellow paints and related Cr-compounds: assessment, quantification and mitigation strategies

Monico, L.; Cotte, M.; Vanmeert, F.; Amidani, L.; Janssens, K.; Nuyts, G.; Garrevoet, J.; Falkenberg, G.; Glatzel, P.; Romani, A.; Miliani, C.

Synchrotron radiation (SR)-based X-ray methods are powerful analytical tools for several purposes and we widely use them for probing the degradation mechanisms of inorganic artists’ pigments in paintings, including chrome yellows (PbCr1-xSxO4; 0 ≤x≤0.8), a class of compounds often found in Van Gogh masterpieces. However, the high intensity and brightness of SR beams raise important issues regarding potential damages of the analyzed samples. A thorough knowledge of the SR X-ray sensitivity of each class of pigment in the painting matrix is therefore required to find analytical strategies that contribute to minimize the damage for preserving the integrity of the analyzed sample and to avoid misinterpretation of the data. Here, we employ a combination of Cr K-edge X-ray absorption near edge structure (XANES) spectroscopy, Cr-Kβ X-ray emission spectroscopy (XES) and X-ray diffraction (XRD) to monitor and quantify the effects of SR X-rays on the stability of chrome yellows and related Cr-compounds and to define strategies for mitigating their damage. We found that the SR X-ray beam exposure induces changes in the oxidation state and local coordination environment of Cr-ions and leads to a loss of the compound’s crystalline structure. The extent of X-ray damage depends on some intrinsic properties of the samples (chemical composition of the pigment as well as the presence/absence and nature of the binder) and it can be minimized by optimizing the overall fluence/dose released to the samples and by working in vacuum and cryogenic conditions.


  • Secondary publication expected from 21.09.2021

Publ.-Id: 31468

Development of PSMA-1007 - Related Series of 18F-Labeled Glu-ureido type PSMA inhibitors.

Cardinale, J.; Roscher, M.; Schaefer, M.; Geerlings, M.; Benešová, M.; Bauder-Wüst, U.; Remde, Y.; Eder, M.; Novakova, Z.; Motlová, L.; Bařinka, C.; Giesel, F.; Kopka, K.

In recent years, a number of drugs targeting the prostate specific-membrane antigen (PSMA) have become important tools in the diagnosis and treatment of prostate cancer. In the present work, we report on the synthesis and preclinical evaluation of a series of 18F-labeled PSMA ligands for diagnostic application based on the theragnostic ligand PSMA-617. By applying modifications to the linker-structure, insight into the structure-activity relationship could be gained highlighting the importance of hydrophilicity and stereoselectivity on interaction with PSMA and hence the biodistribution. Selected compounds were co-crystallized with the PSMA-protein and analyzed by X-ray with mixed results. Amongst these, PSMA-1007 (compound 5) showed the best interaction with the PSMA protein. The respective radiotracer [18F]PSMA-1007 was translated into the clinic and is in the meantime subject of advanced clinical trials.

Keywords: PET Tracer; PSMA ligands; prostate cancer; PSMA-1007; PSMA inhibitors

Publ.-Id: 31467

P1826 - Calix[n]aren-Derivate zur Komplexierung von Erdalkalimetallkationen

Mamat, C.; Bauer, D.; Reissig, F.; Pietzsch, H.-J.; Steinbach, J.

Die Erfindung betrifft eine Verbindung, die

  • eine Calixaren-Einheit, die n Phenoleinheiten aufweist, wobei n 4, 5, 6 oder 8 ist;
  • eine Ethereinheit, die unter Ausbildung eines Kronenethers an die Calixaren-Einheit gebunden ist; und
  • zumindest eine Sulfonsäureamid-Einheit der Formel
aufweist, wobei
die zumindest eine Sulfonsäureamid-Einheiten jeweils an die Calixaren-Einheit gebunden ist und R¹ jeweils aus der Gruppe ausgewählt ist, die aus einer perfluorierten verzweigten oder unverzweigten C₂-C₈-Alkylgruppe, einer perfluorierten Arylgruppe, und einer Gruppe Ar besteht, p eine Ganzzahl von 1 bis 4 ist und Ar eine Phenylgruppe ist, die mit einer oder mehreren perfluorierten verzweigten oder unverzweigten C₁-C₈-Alkylgruppen substituiert ist.
  • Patent
    DE102018132293 - Offenlegung 18.06.2020; Nachanmeldungen: WO

Publ.-Id: 31465

P1825 - Tomographievorrichtung und Tomographieverfahren

Iskander, K.; Bieberle, A.; Schleicher, E.

Die Erfindung betrifft eine Tomographievorrichtung und ein Tomographieverfahren zum Abbilden der inneren Struktur eines Untersuchungsobjekts, wobei aufeinanderfolgend in einer ersten, einer zweiten und einer dritten Scanebene Strahlung zum tomographischen Untersuchen des Untersuchungsobjekts erzeugt wird und die Strahlung mittels einer Detektorvorrichtung mit mehreren Detektorsegmenten erfasst wird, wobei jedes Detektorsegment einen in der ersten Scanebene angeordneten ersten Strahlungsdetektor, einen in der zweiten Scanebene angeordneten zweiten Strahlungsdetektor und einen in der dritten Scanebene angeordneten dritten Strahlungsdetektor zum Erfassen der Strahlung unter Erzeugung von Detektorsignalen aufweist, und wobei die Detektorsignale des ersten und des dritten Strahlungsdetektors mittels eines ersten Verstärkers verstärkt werden und die Detektorsignale des zweiten Strahlungsdetektors mittels eines zweiten Verstärkers verstärkt werden.

  • Patent
    DE102018131497 - Offenlegung 10.06.2020

Publ.-Id: 31464

P1824 - Rippenrohrwärmeübertrager mit konvexen Aussparungen der Rippenflächen und integrierten Materialaufdickungen

Unger, S.; Hampel, U.

Die Erfindung betrifft einen Wärmeübertrager mit wenigstens einer Trennwand und wenigstens von einer Seite der Trennwand abstehenden und die Oberfläche der Trennwand vergrößernden Oberflächenelementen, die von einem Fluid umströmbar sind. Dabei weisen die Oberflächenelemente Verstärkungswülste und zwischen den Verstärkungswülsten befindliche Flächenbereiche auf, wobei sich die Verstärkungswülste von der Trennwand ausgehend erstrecken und eine kreisrunde oder ovale Querschnittform haben. Die Verstärkungswülste erstrecken sich ausgehend von der Trennwand über mindestens einen Teil der Höhe des Oberflächenelementes und verjüngen sich von der Trennwand aus entlang der Höhe der Oberflächenelemente. Die Oberflächenelemente weisen eine Vielzahl konvexer Aussparungen auf, wobei jede der konvexen Aussparungen in einem der Flächenbereiche zwischen zwei Verstärkungswülsten angeordnet ist und sich von einer Außenkante des Oberflächenelementes erstreckt. Der Scheitelpunkt der konvexen Aussparung liegt bei einer Höhe größer als oder gleich 30% und kleiner als oder gleich 70% der gesamten Höhe des Oberflächenelementes, wobei die Höhe ausgehend von der Trennwand gemessen ist.

  • Patent
    DE102018129788 - Erteilung 24.10.2019; Nachanmeldungen: WO

Publ.-Id: 31463

P1823 - Pyrrolopyridin-Derivate und deren Verwendung

Moldovan, R.-P.; Fischer, S.; Ludwig, F.-A.; Deuther-Conrad, W.; Brust, P.

Die Erfindung betrifft eine Verbindung der allgemeinen Formel I worin Ar ein Pyridin-Ring ist; R¹ Wasserstoff oder Fluor ist; R² aus der Gruppe ausgewählt ist, die aus Wasserstoff, Hydroxy, Halogen, -CN, -NO₂, -N(R³R⁴), -(CR⁹R¹⁰)ₚ-C(O)-N(R⁵R⁶), -(CR⁹R¹⁰)q-CHO, -(CR⁹R¹⁰)r-C(O)-(CR⁹R¹⁰)s-R⁷, -(CR⁹R¹⁰)t-O-(CR⁹R¹⁰)v-R⁸ oder einer verzweigten oder unverzweigten, substituierten oder unsubstituierten C₁-C₁₂-Alkylgruppe besteht; R³, R⁴, R⁵, R⁶ und R⁷ unabhängig voneinander jeweils Wasserstoff oder eine verzweigte oder unverzweigte, substituierte oder unsubstituierte C₁-C₁₂-Alkylgruppe sind; R⁸ eine verzweigte oder unverzweigte, substituierte oder unsubstituierte C₁-C₁₂-Alkylgruppe ist; R⁹ und R¹⁰ unabhängig voneinander bei jedem Vorkommen Wasserstoff, Halogen, verzweigtes oder unverzweigtes, unsubstituiertes oder substituiertes C₁-C₁₂-Alkyl oder unsubstituiertes oder substituiertes C₂-C₆-Alkenyl sind; 1 1, 2, 3 oder 4 ist m 0, 1 oder 2 ist, mit der Maßgabe, dass 1 + m nicht größer als 4 ist; n 1, 2 oder 3 ist; und p, q, r, s, t und v unabhängig voneinander 0 oder eine Ganzzahl von 1 bis 6 sind. Außerdem ist eine Präkursor-Verbindung zur Herstellung einer Verbindung der Formel I vorgesehen, die anstelle einer Gruppe R¹ eine Abgangsgruppe aufweist.

  • Patent
    DE102018129693 - Offenlegung 28.05.2020; Nachanmeldungen: WO

Publ.-Id: 31462

P1821 - Markierungsvorläufer mit Quadratsäure-Kopplung

Bergmann, R.; Johannes-Gutenberg-Universität Mainz

Ein Markierungsvorläufer umfasst einen Chelator oder eine Fluorierungsgruppe für die Radiomarkierung mit ⁴⁴Sc, ⁴⁷Sc, ⁵⁵Co, ⁶²Cu, ⁶⁴Cu, ⁶⁷Cu, ⁶⁶Ga, ⁶⁷Ga, ⁶⁸Ga, ⁸⁹Zr, ⁸⁶Y, ⁹⁰Y, ⁹⁰Nb, ⁹⁹ᵐTc, ¹¹¹In, ¹³⁵Sm, ¹⁴⁰Pr, ¹⁵⁹Gd, ¹⁴⁹Tb, ¹⁶⁰Tb, ¹⁶¹Tb, ¹⁶⁵Er, ¹⁶⁶Dy, ¹⁶⁶Ho, ¹⁷⁵Yb, ¹⁷⁷Lu, ¹⁸⁶Re, ¹⁸⁸Re, ¹¹³Bi und ¹¹⁵Ac beziehungsweise mit ¹⁸F, ¹³¹I oder ¹¹¹At und einen oder zwei biologische Targetingvektoren, die über eine oder mehrere Quadratsäuregruppen mit dem Chelator oder der Fluorierungsgruppe gekoppelt sind.

  • Patent
    DE102018126558 - Offenlegung 30.04.2020; Nachanmeldungen: WO

Publ.-Id: 31461

P1820 - Tomographievorrichtung und Tomographieverfahren

Barthel, F.

Die Erfindung betrifft eine Tomographievorrichtung und ein Tomographieverfahren zum Abbilden der inneren Struktur eines Untersuchungsobjekts, wobei ein Elektronenstrahl derart über ein erstes Target mit mehreren Durchtrittsöffnungen geführt wird, dass der Elektronenstrahl nacheinander mehrere der Durchtrittsöffnungen überstreicht, wobei an dem ersten Target erste Röntgenstrahlung zum Durchstrahlen des Untersuchungsobjekts entsteht, wenn der Elektronenstrahl abseits der Durchtrittsöffungen auf das erste Target trifft, und wobei der Elektronenstrahl durch das erste Target hindurchtritt und mittels einer zwischen das erste Target und ein zweites Target angelegten elektrischen Spannung auf das zweite Target beschleunigt wird, wenn der Elektronenstrahl auf eine der Durchtrittsöffnungen gerichtet ist, wobei an dem zweiten Target zweite Röntgenstrahlung zum Durchstrahlen des Untersuchungsobjekts

  • Patent
    DE102018125822 - Erteilung 02.01.2020

Publ.-Id: 31460

Data for: Enantiomerically pure Tetravalent Neptunium Amidinates: Synthesis and Characterization

Fichter, S.; Kaufmann, S.; Kaden, P.; Brunner, T. S.; Stumpf, T.; Roesky, P. W.; März, J.

The synthesis of a tetravalent neptunium amidinate [NpCl((S)‐PEBA)3] (1) ((S)‐PEBA=(S,S)‐N,N′‐bis‐(1‐phenylethyl)‐benzamidinate) is reported. This complex represents the first structurally characterized enantiopure transuranic compound. Reactivity studies with halide/pseudohalides yielding [NpX((S)‐PEBA)3] (X=F (2), Br (3), N3 (4)) have shown that the chirality‐at‐metal is preserved for all compounds in the solid state. Furthermore, they represent an unprecedented example of a structurally characterized metal–organic Np complex featuring a Np−Br (3) bond. In addition, 4 is the only reported tetravalent transuranic azide. All compounds were additionally characterized in solution using para‐magnetic NMR spectroscopy showing an expected C3‐symmetry at low temperatures.

Keywords: transuranium chemistry; actinides; neptunium; coordination chemistry; amidinates

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  • Reseach data in the HZDR data repository RODARE
    Publication date: 2020-08-27
    DOI: 10.14278/rodare.465
    License: CC-BY-4.0


Publ.-Id: 31459

How does iron storage protein ferritin interact with plutonium (and thorium) ?

Zurita, C.; Tsushima, S.; Bresson, C.; Garcia-Cortes, M.; Solari, P. L.; Jeanson, A.; Creff, G.; Den Auwer, C.

The impact of the contamination of living organisms by actinide elements has been a constant subject of attention since the 1950s. But to date still little is understood. Ferritin is the major storage and regulation protein of iron in many organisms, it consists of a protein ring and a ferrihydric core at the center. This work sheds light on the interactions of early actinides (Th, Pu) at oxidation state +IV with ferritin and its ability to store those elements at physiological pH compared to Fe. The Ferritin ‐ thorium load curve suggests that Th(IV) saturates the protein (2840 Th atoms per ferritin) in a similar way that Fe does on the protein ring. Complementary spectroscopic techniques (Spectrophotometry, Infrared Spectroscopy and X‐ray Absorption Spectroscopy) were combined with Molecular Dynamics to provide a structural model of the interaction of Th(IV) and Pu(IV) with ferritin. Comparison of spectroscopic data together with MD calculations suggests that Th(IV) and Pu(IV) are complexed mainly on the protein ring and not on the ferrihydric core. Indeed from XAS data, there is no evidence of Fe neighbors in the Th and Pu environments. On the other hand, carboxylates from amino acids of the protein ring and a possible additional carbonate anion are shaping the cation coordination spheres. This thorough description from a molecular view point of Th(IV) and Pu(IV) interaction with ferritin, an essential iron storage protein, is a cornerstone in comprehensive nuclear toxicology.

Publ.-Id: 31457

Quarkonia formation in a holographic gravity-dilaton background describing QCD thermodynamics

Zöllner, R.; Kämpfer, B.

A holographic model of probe quarkonia is presented, where the dynamical gravity-dilaton background is adjusted to the thermodynamics of 2 +1 flavor QCD with physical quark masses. The quarkonia action is modified to account for a systematic study of the heavy-quark mass dependence. We focus on the J/ψ and Υ spectral functions and relate our model to heavy quarkonia formation as a special aspect of hadron phenomenology in heavy-ion collisions at LHC.

Publ.-Id: 31454

Brittle-ductile transition temperature of recrystallized tungsten following exposure to fusion relevant cyclic high heat load

Shah, V.; van Dommelen, J. A. W.; Altstadt, E.; Das, A.; Geers, M. G. D.

The lifetime of tungsten (W) monoblocks under fusion conditions is ambivalent. In this work, the microstructure dependent mechanical behaviour of pulsed high heat flux (HHF) exposed W monoblock is investigated. Two different microstructural states, i.e. initial (deformed) and recrystallized, both machined from HHF exposed monoblocks are tested using tensile and small punch tests. The initial microstructural state reveals a higher fraction of low angle boundaries along with a preferred orientation of crystals. Following HHF exposure, the recrystallized state exhibits weakening of initial texture along with a higher fraction of high angle boundaries. Irrespective of the testing methodology, both the microstructural states display brittle failure for temperatures lower than 400∘C. For higher temperatures (>400∘C), the recrystallized microstructure exhibits more ductile behaviour as compared to the initial state. The observed microstructural state-dependent mechanical behaviour is further discussed in terms of different microstructural features. The estimated brittle-to-ductile transition temperature (BDTT) range is noticed to be lower for the recrystallized state as compared to the initial state. The lower BDTT in the recrystallized state is attributed to the high purity of the W in combination with its low defect density, thereby preventing segregation of impurities at the recrystallized boundaries and the related premature failure. Based on this observation, it is concluded that the common opinion of the aggravation of BDTT in W due to recrystallization is not unerring, and as a matter of fact, recrystallization in W could be instrumental for preventing the self-castellation of the monoblocks.

Keywords: Tungsten; High heat flux exposure; Tensile test; Small punch test; Recrystallization and embrittlement; Brittle-to-ductile transition temperature

Publ.-Id: 31453

An integrated approach combining soil profile, records and tree ring analysis to identify the origin of environmental contamination in a former uranium mine (Rophin, France)

Martin, A.; Hassan-Loni, Y.; Fichtner, A.; Péron, O.; David, K.; Chardon, C.; Larrue, S.; Gourgiotis, A.; Sachs, S.; Arnold, T.; Grambow, B.; Stumpf, T.; Montavon, G.

Uranium mining and milling activities raise environmental concerns due to the release of radioactive and other toxic elements. Their long-term management thus requires a knowledge of past events coupled with a good understanding of the geochemical mechanisms regulating the mobility of residual radionuclides. This article presents the results on the traces of anthropic activity linked to previous uranium (U) mining activities in the vicinity of the Rophin tailings storage site (Puy de Dôme, France). Several complementary approaches were developed based on a study of the site's history and records, as well as on a radiological and chemical characterization of soil cores and a dendrochronology. Gamma survey measurements of the wetland downstream of the Rophin site revealed a level of 1050 nSv.h−1. Soil cores extracted in the wetland showed U concentrations of up to 1855−1, which appears to be associated with the presence of a whitish silt loam (WSL) soil layer located below an organic topsoil layer. Records, corroborated by prior aerial photographs and analyses of 137Cs and 14C activities, suggest the discharge of U mineral particles while the site was being operated. Moreover, lead isotope ratios indicate that contamination in the WSL layer can be discriminated by a larger contribution of radiogenic lead to total lead. The dendroanalysis correlate U emissions from Rophin with the site's history. Oak tree rings located downstream of the site contain uranium concentrations ten times higher than values measured on unaffected trees. Moreover, the highest U concentrations were recorded not only for the operating period, but more surprisingly for the recent site renovations as well. This integrated approach corroborates that U mineral particles were initially transported as mineral particles in Rophin's watershed and that amajority of the deposited uranium appears to have been trapped in the topsoil layer, with high organic matter content.

Keywords: Uranium mining; Wetland; Records; Dendroanalysis; Radiochronology; U decay chain

Publ.-Id: 31452

Photoluminescence and Raman Spectroscopy Study on Color Centers of Helium Ion-Implanted 4H–SiC

Song, Y.; Xu, Z.; Li, R.; Wang, H.; Fan, Y.; Rommel, M.; Liu, J.; Astakhov, G.; Hlawacek, G.; Li, B.; Xu, J.; Fang, F.

Color centers in silicon carbide (SiC) are promising candidates for quantum technologies. However, the richness of the poly-type and defect coniguration of SiC makes the accurate control of the types and position of defects in SiC still challenging. In this study, helium ion-implanted 4H–SiC was characterized by atomic force microscopy (AFM), confocal photoluminescence (PL), and Raman spectroscopy at room temperature. PL signals of silicon vacancy were found and analyzed using 638-nm and 785-nm laser excitation by means of depth proiling and SWIFT mapping. Lattice defects (C–C bond) were detected by continuous laser excitation at 532 nm and 638 nm, respectively. PL/Raman depth proiling is helpful in revealing the three-dimensional distribution of produced defects. Diferences in the depth proiling results and SRIM simulation results were explained by considering the depth resolution of the confocal measurement setup, helium bubbles, as well as swelling.

Keywords: Helium ion implantation; Silicon Carbid (SiC); Color Center; Point defect; Silicon vacancy; Confocal photoluminescence spectroscopy; Raman spectroscopy; Atomic force Microscopy (AFM); Helium Ion Microscopy


  • Secondary publication expected from 15.09.2021

Publ.-Id: 31451

Intracavity third-harmonic generation in Si:B pumped by intense terahertz pulses

Meng, F.; Thomson, M. D.; Ul-Islam, Q.; Klug, B.; Pashkin, O.; Schneider, H.; Roskos, H. G.

We observe third-harmonic generation (THG) in boron-doped silicon (Si:B) upon pumping with picosecond 1.56 THz pulses from a free-electon laser with a peak electric field strength of up to 12 kV/cm. The measurements are performed at cryogenic temperatures where the majority of holes are bound to the acceptor dopants. The dependence of the THG on the pump intensity exhibits a threshold-free power-law behavior with an exponent close to 4. The observations can be explained by THz emission by free holes accelerated in the non-parabolic valence band, under the assumption that the density of free holes increases with the pump intensity. A quantitative treatment supports that these carriers are generated by impact ionization, initiated by the population of thermally ionized carriers , as opposed to direct tunneling ionization. In addition, we also observe intracavity THG by embedding the Si:B in a one-dimensional photonic crystal cavity. The THG efficiency is increased by a factor of eight due to the field enhancement in the cavity, with the potential to reach a factor of more than 100 for pump pulses with a spectrum narrower than the linewidth of the cavity resonance.

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Publ.-Id: 31450

Anisotropic spin-acoustic resonance in silicon carbide at room temperature

Hernandez-Minguez, A.; Poshakinskiy, A. V.; Hollenbach, M.; Santos, P. V.; Astakhov, G.

We report on acoustically driven spin resonances in atomic-scale centers in silicon carbide at room temperature. Specifically, we use a surface acoustic wave cavity to selectively address spin transitions with magnetic quantum number differences of 1 and 2 in the absence of external microwave electromagnetic fields. These spin-acoustic resonances reveal a nontrivial dependence on the static magnetic field orientation, which is attributed to the intrinsic symmetry of the acoustic fields combined with the peculiar properties of a half-integer spin system. We develop a microscopic model of the spin-acoustic interaction, which describes our experimental data without fitting parameters. Furthermore, we predict that traveling surface waves lead to a chiral spin-acoustic resonance that changes upon magnetic field inversion. These results establish silicon carbide as a highly promising hybrid platform for on-chip spin-optomechanical quantum control enabling engineered interactions at room temperature.

Keywords: Spin qubits; surface acoustic waves; quantum technology; SiC

Publ.-Id: 31445

Experimental and numerical analysis of the complex permittivity of open-cell ceramic foams

Hernandez, J. N. C.; Link, G.; Soldatov, S.; Füssel, A.; Schubert, M.; Hampel, U.

Open-cell ceramic foams are promising materials in the field of microwave heating. They can be manufactured from susceptor materials and can, therefore, be used as selective heating elements. In this study, the complex permittivities of ceramic foam materials, including silicon-infiltrated silicon carbide (SiSiC), pressureless sintered silicon carbide (SSiC), silicate bonded silicon carbide (SBSiC), and cordierite were determined. The dielectric properties of the foams were determined by the cavity perturbation technique using a TE104 WR340 waveguide resonator at 2.45 GHz. Samples were preheated in a tubular furnace, enabling temperature-dependent permittivity measurements up to 200 °C. The effective dielectric constant and effective loss factor were found to depend on the porosity and material composition of the foam. The SiSiC material had a higher effective dielectric constant than the SSiC and SBSiC ceramics. The effective dielectric constant of the foams showed a trend of gradual increase with increasing temperature. Some selected dielectric mixing relations were then applied to describe the effective permittivity of the foams and compare them with predictions from finite element simulations performed using the CST Studio Suite. The foam morphologies and simple block inclusions were used in the simulations.

Keywords: microwave processing; dielectric properties; silicon carbide; cordierite


Publ.-Id: 31444

Dimensional crossover in spin Hall oscillators

Smith, A.; Sobotkiewich, K.; Khan, A.; Montoya, E. A.; Yang, L.; Duan, Z.; Schneider, T.; Lenz, K.; Lindner, J.; An, K.; Li, X.; Krivorotov, I. N.

Auto-oscillations of magnetization driven by direct spin current have been previously observed in multiple quasi-zero-dimensional (0D) ferromagnetic systems such as nanomagnets and nanocontacts. Recently, it was shown that pure spin Hall current can excite coherent auto-oscillatory dynamics in quasi-one-dimensional (1D) ferromagnetic nanowires but not in quasi-two-dimensional (2D) ferromagnetic films. Here we study the 1D to 2D dimensional crossover of current-driven magnetization dynamics in wire-based Pt/Ni80Fe20 bilayer spin Hall oscillators via varying the wire width.We find that increasing the wire width results in an increase of the number of excited auto-oscillatory modes accompanied by a decrease of the amplitude and coherence of each mode. We also observe a crossover from a hard to a soft onset of the auto-oscillations with increasing wire width. The amplitude of auto-oscillations rapidly decreases with increasing temperature suggesting that interactions of the phase-coherent auto-oscillatory modes with incoherent thermal magnons play an important role in suppression of the auto-oscillatory dynamics. Our measurements set the upper limit on the dimensions of an individual spin Hall oscillator and elucidate the mechanisms leading to suppression of coherent auto-oscillations with increasing oscillator size.

Keywords: Spin hall oscillators, ferromagnetism, spin currents, magnetization dynamics, spin waves


Publ.-Id: 31443

Liquid Metal Alloy Ion Sources for magnetic nano-structures

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

Focused Ion Beam (FIB) is a modern tool for µm and sub-µm structure fabrication and analysis. Commercial systems work mostly with a Gallium - Liquid Metal Ion Source (LMIS) and can achieve a resolution lower than 10 nm and current densities more than 10 Acm-2. The use of alloy LMIS, mainly developed at HZDR, opens a broad field of new applications. In combination with modern FIB systems, like the VELION (Raith) the application field can be extended due to a broad spectrum of available ion species in high resolution ion beams and the stage properties. All these aspects will be concentrated to the ZIM project GRANT No.-ZF4330902 DF7 dealing with the prospective modern topic of nano-magnetic structures from basic research up to new applications. Main topics are: i) the local modification of magnetic single nano-structures using a FIB with Co, Ni, Fe, … ions and ii) the fabrication and investigation of magnonic crystals, made by writing FIB implantation with rare earth ions (Nd, Dy, Ho, Er, …).

Keywords: Focused Ion Beam; ion sources; magnetic nanostructures; magnonic crystals

  • Lecture (others)
    Kick-off meeting, ZIM Project No.-ZF4494801 DF7, 14.-16.09.2020, Dortmund, Germany

Publ.-Id: 31442

Simulation of hard x-rays source produced by a picosecond laser irradiated solid target for Compton radiography

Meng-Ting, L.; Guang-Yue, H.; Huang, L.; Jian, Z.

A bremsstrahlung radiation hard x-ray source, produced by a picosecond intense laser irradiated solid target, was used to diagnose an implosion capsule at stagnation phase via Compton radiography in experiments. By performing Monte Carlo and particle-in-cell simulation, we investigated the influence of target materials and laser intensity on the >70 keV bremsstrahlung hard x-ray emission. We found that the brightness of the hard x-rays is proportional to the atomic number multiplied by area density (ZρL), which indicates that the higher Z and higher density gold or uranium material will produce the brightest hard x-rays source at the same thickness. In relativistic laser solid interactions, hot electron recirculation plays an important role in hard x-ray emission. Without recirculation, hard x-ray conversion efficiency decays when increasing the laser intensity. While the hard x-ray emission comes to the maximal saturated conversion efficiency at relativistic laser intensity if considering the electron recirculation.
These results provide valuable insights into the experimental design of Compton radiography

Keywords: Inertial confined fusion; Compton radiography; Numerical modeling


  • Secondary publication expected from 22.07.2021

Publ.-Id: 31440

Three-dimensional cell culture systems in radiopharmaceutical cancer research

Doctor, A.; Seifert, V.; Ullrich, M.; Hauser, S.; Pietzsch, J.

In preclinical cancer research, three-dimensional (3D) cell culture systems such as multicellular spheroids and organoids are becoming increasingly important. They provide valuable information before studies on animal models begin and, in some cases, are even suitable for reducing or replacing animal experiments. Furthermore, they recapitulate microtumors, metastases and the tumor microenvironment much better than monolayer culture systems could. 3D models show higher structural complexity and diverse cell interactions, while reflecting (patho)physiological phenomena such as oxygen and nutrient gradients in the course of their growth or development. These interactions and properties are of great importance for understanding the pathophysiological importance of stromal cells and the extracellular matrix for tumor progression, treatment response or resistance mechanisms of solid tumors. Special emphasis is placed on co-cultivation with tumor-associated cells, which further increases the predictive value of 3D models, e.g. for drug development. The aim of this overview is to shed light on selected 3D models and their advantages and disadvantages, especially from the radiopharmacist´s point of view with focus on the suitability of 3D models for the radiopharmacological characterization of novel radiotracers and radiotherapeutics. Special attention is paid to pancreatic ductal adenocarcinoma (PDAC), as predestined target for the development of new radionuclide-based theranostics.

Keywords: Co-culture; organoids; pancreatic cancer; radiotherapeutics; radiotracer; spheroids; stromal cells; 3D model; tumor microenvironment

Publ.-Id: 31439

Trapped-ion toolkit for studies of quantum harmonic oscillators under extreme conditions

Wittemer, M.; Schröder, J.-P.; Hakelberg, F.; Kiefer, P.; Fey, C.; Schützhold, R.; Warring, U.; Schaetz, T.

Many phenomena described in relativistic quantum field theory are inaccessible to direct observations, but analogue processes studied under well-defined laboratory conditions can present an alternative perspective. Recently, we demonstrated an analogy of particle creation using an intrinsically robust motional mode of two trapped atomic ions. Here, we substantially extend our classical control techniques by implementing machine-learning strategies in our platform and, consequently, increase the accessible parameter regime. As a proof of methodology, we present experimental results of multiple quenches and parametric modulation of an unprotected motional mode of a single ion, demonstrating the increased level of real-time control. In combination with previous results, we enable future experiments that may yield entanglement generation using a process in analogy to Hawking radiation. This article is part of a discussion meeting issue 'The next generation of analogue gravity experiments'.

Keywords: Trapped Ions; Qubits; Ion Traps (Instrumentation)

Publ.-Id: 31436

Prognostic value of baseline [18F]-fluorodeoxyglucose positron emission tomography parameters MTV, TLG and asphericity in an international multicenter cohort of nasopharyngeal carcinoma patients

Zschaeck, S.; Li, Y.; Lin, Q.; Beck, M.; Amthauer, H.; Bauersachs, L.; Hajiyianni, M.; Rogasch, J.; Ehrhardt, V. H.; Kalinauskaite, G.; Weingärtner, J.; Hartmann, V.; van den Hoff, J.; Budach, V.; Stromberger, C.; Hofheinz, F.


[18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) parameters have shown prognostic value in nasopharyngeal carcinomas (NPC), mostly in monocenter studies. The aim of this study was to assess the prognostic impact of standard and novel PET parameters in a multicenter cohort of patients.

The established PET parameters metabolic tumor volume (MTV), total lesion glycolysis (TLG) and maximal standardized uptake value (SUVmax) as well as the novel parameter tumor asphericity (ASP) were evaluated in a retrospective multicenter cohort of 114 NPC patients with FDG-PET staging, treated with (chemo)radiation at 8 international institutions. Uni- and multivariable Cox regression and Kaplan-Meier analysis with respect to overall survival (OS), event-free survival (EFS), distant metastases-free survival (FFDM), and locoregional control (LRC) was performed for clinical and PET parameters.

When analyzing metric PET parameters, ASP showed a significant association with EFS (p = 0.035) and a trend for OS (p = 0.058). MTV was significantly associated with EFS (p = 0.026), OS (p = 0.008) and LRC (p = 0.012) and TLG with LRC (p = 0.019). TLG and MTV showed a very high correlation (Spearman’s rho = 0.95), therefore TLG was subesequently not further analysed. Optimal cutoff values for defining high and low risk groups were determined by maximization of the p-value in univariate Cox regression considering all possible cutoff values. Generation of stable cutoff values was feasible for MTV (p<0.001), ASP (p = 0.023) and combination of both (MTV+ASP = occurrence of one or both risk factors, p<0.001) for OS and for MTV regarding the endpoints OS (p<0.001) and LRC (p<0.001). In multivariable Cox (age >55 years + one binarized PET parameter), MTV >11.1ml (hazard ratio (HR): 3.57, p<0.001) and ASP > 14.4% (HR: 3.2, p = 0.031) remained prognostic for OS. MTV additionally remained prognostic for LRC (HR: 4.86 p<0.001) and EFS (HR: 2.51 p = 0.004). Bootstrapping analyses showed that a combination of high MTV and ASP improved prognostic value for OS compared to each single variable significantly (p = 0.005 and p = 0.04, respectively). When using the cohort from China (n = 57 patients) for establishment of prognostic parameters and all other patients for validation (n = 57 patients), MTV could be successfully validated as prognostic parameter regarding OS, EFS and LRC (all p-values <0.05 for both cohorts).

In this analysis, PET parameters were associated with outcome of NPC patients. MTV showed a robust association with OS, EFS and LRC. Our data suggest that combination of MTV and ASP may potentially further improve the risk stratification of NPC patients.

Publ.-Id: 31435

Unusual scandium enrichments of the Tørdal pegmatites, south Norway. Part I: Garnet as Sc exploration pathfinder

Steffenssen, G.; Müller, A.; Munnik, F.; Friis, H.; Erambert, M.; Kristoffersen, M.; Rosing-Schow, N.

The granitic pegmatites of the Tørdal area in southern Norway have been known for their Sc enrichment for about 100 years. Scandium is a compatible element in garnet. In this study, 32 garnet samples from 16 pegmatite localities across the Tørdal pegmatite field were investigated to determine the Sc distribution within garnets (crystal scale), within pegmatite bodies (pegmatite scale) and across the Tørdal pegmatite field (regional scale). In the Tørdal pegmatites, Sc content in garnet is representative for the Sc bulk composition of pegmatites, defining garnet as a reliable pathfinder mineral for the exploration of Sc mineralization in pegmatite fields. Garnets with highest Sc concentrations of up to 2197 µg/g have a spessartine component ranging from 50 to 60 mol.%. Since most garnets crystallized during the early stage of pegmatite formation (wall zone stage) Sc decreases in the remaining pegmatite melt, as documented by generally decreasing Sc from core to rim of crystals and by the occurrence of late-stage garnets (albite zone stage) with low Sc. Thus, with progressing crystallization Sc decreases in the melt. The regional Sc distribution in the Tørdal pegmatite field revealed that the Skardsfjell-Heftetjern-Høydalen pegmatites have highest Sc enrichments to sub-economic levels, with an average bulk Sc content of 53 µg/g and an average Sc content in garnet of about 1900 µg/g in the Heftetjern 2 pegmatite.
The assumed resources of the Skardsfjell-Heftetjern-Høydalen area are about 125,000 t ore grading c. 50 µg/g Sc resulting in a total of 625 t Sc, which is too small to have economic potential. However, the strong Sc enrichment of the Tørdal pegmatites is unusual for granitic pegmatites, making them a specific Sc deposit type. The amphibolitic host rocks of the Tørdal pegmatites are identified as the source rocks of Sc. The host rocks, which are part of the Nissedal Outlier supracrustals, are enriched in Sc (mean 34 µg/g) compared to average crustal compositions (mean 14 µg/g). Scandium of amphiboles was preferentially released at the onset of partial melting of the amphibolites. Thus, the Sc content in the pegmatite is strongly dependent on the degree of partial melting.

Keywords: scandium; pegmatite; garnet; Sveconorwegian orogeny; Tørdal

Publ.-Id: 31434

Coherent Optical Signatures of Electron Microbunching in Laser-Driven Plasma Accelerators

Lumpkin, A. H.; Laberge, M.; Rule, D. W.; Zgadzaj, R.; Hannasch, A.; Zarini, O.; Bowers, B.; Irman, A.; Couperus Cabadağ, J. P.; Debus, A.; Köhler, A.; Schramm, U.; Downer, M. C.

We report observations of coherent optical transition radiation interferometry (COTRI) patterns generated by microbunched∼200-MeV electrons as they emerge from a laser-driven plasma accelerator. The divergence of the microbunched portion of electrons, deduced by comparison to a COTRI model, is ∼9× smaller than the ∼3 mrad ensemble beam divergence, while the radius of the microbunched beam, obtained from COTR images on the same shot, is <3 μm. The combined results show that the microbunched distribution has estimated transverse normalized emittance∼0.4mm mrad.

Keywords: Beam diagnostics; LWFA; COTRI; CTR; transition radiation


Publ.-Id: 31431

Freestanding and Supported MoS2 Monolayers under Cluster Irradiation: Insights from Molecular Dynamics Simulation

Ghaderzadeh, S.; Ladygin, V.; Ghorbani Asl, M.; Hlawacek, G.; Schleberger, M.; Krasheninnikov, A.

Two-dimensional (2D) materials with nanometer-size holes are promising systems for DNA sequencing, water purification, and molecule selection/separation. However, controllable creation of holes with uniform sizes and shapes is still a challenge, especially when the 2D material consists of several atomic layers as, e.g., MoS2, the archetypical transition metal dichalcogenide.We use analytical potential molecular dynamics simulations to study the response of 2D MoS2tocluster irradiation. We model both freestanding and supported sheets and assess the amount of damage created in MoS2by the impacts of noble gas clusters in a wide range of cluster energies and incident angles. We show that cluster irradiation can be used to produce uniform holes in 2DMoS2with the diameter being dependent on cluster size and energy. Energetic clusters can also beused to displace sulfur atoms preferentially from either top or bottom layers of S atoms in MoS2and also clean the surface of MoS2sheets from adsorbents. Our results for MoS2, which should be relevant to other 2D transition metal dichalcogenides, suggest new routes toward cluster beam engineering of devices based on 2Dinorganic materials.

Keywords: two-dimensional materials; MoS2; cluster irradiation; pore formation; sputtering yield; atomistic simulation


  • Secondary publication expected from 28.07.2021

Publ.-Id: 31430

Drill-Core Hyperspectral and Geochemical Data Integration in a Superpixel-Based Machine Learning Framework

Contreras Acosta, I. C.; Khodadadzadeh, M.; Tolosana Delgado, R.; Gloaguen, R.

The analysis of drill-core samples is one of the most important steps in the mining industry for the exploration and discovery of mineral resources. Geochemical assays are a common approach to represent the abundance of different chemical elements and aid at quantifying the concentrations of the important ore accumulations. However, their acquisition is time-consuming and usually averages of long core portions. Hyperspectral data are increasingly being used in the mining industry to complement the analysis of drill-cores due to their efficiency and fast turn-around time. Moreover, hyperspectral imaging is a technique able to provide data with high spatial resolution. In this article, we propose to integrate the complementary information derived from hyperspectral and geochemical data via a superpixel-based machine learning framework. This framework considers the difference in spatial resolution through segmentation. We extract labels from the geochemical assays and select, from the hyperspectral data, representative samples for each measurement. A supervised machine learning classification (composite kernel support vector machine) is then used to extrapolate the elements relative abundance to the entire core length. We propose an innovative integration of hyperspectral data covering different regions of the electromagnetic spectrum in a kernel-based framework to facilitate the identification of a larger amount of elements. A qualitative and quantitative evaluation of the results demonstrates the capabilities of the proposed method, which provides approximately 20% more accurate results than the pixel-based approach. Results also imply that the method could be beneficial for the reduction of geochemical assays needed for the detailed analysis of the cores.

Keywords: Data integration; drill-cores; geochemical data; hyperspectral data; machine learning; superpixel segmentation

  • Open Access Logo IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 13(2020), 4214-4228
    Online First (2020) DOI: 10.1109/JSTARS.2020.3011221

Publ.-Id: 31425

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