Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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35175 Publications

The pyrazolo[3,4-d]pyrimidine-based kinase inhibitor NVP-BHG712: Effects of regioisomers on tumor growth, perfusion, and hypoxia in EphB4-positive A375 melanoma xenografts

Neuber, C.; Tröster, A.; Löser, R.; Belter, B.; Schwalbe, H.; Pietzsch, J.

In a previous study, EphB4 was demonstrated to be a positive regulator of A375 melanoma growth but a negative regulator of tumor vascularization and perfusion. To distinguish between EphB4 forward and ephrinB2 reverse signaling, we used the commercially available EphB4 kinase inhibitor NVP BHG712 (NVP), which was later identified as its regioisomer NVPiso. Since there have been reported significant differences between the inhibition profiles of NVP and NVPiso, we compared the influence of NVP and NVPiso on tumor characteristics under the same experimental conditions. Despite of different inhibitory profiles of NVP and NVPiso, the comparative study conducted here showed the same EphB4-induced effects in vivo as in the previous investigation. This confirmed the conclusion that EphB4-ephrinB2 reverse signaling is responsible for increased tumor growth as well as decreased tumor vascularization and perfusion. These results are further substantiated by microarrays showing differences between mock-transfected and EphB4-transfected (A375-EphB4) cells with respect to at least 9 angiogenesis-related proteins. Decreased expression of VEGF, Ang-1, and Akt/PKB, together with the increased expression of TIMP-1 and TGF-2, is consistent with the impaired vascularization of A375-EphB4 xenografts. Functional overexpression of EphB4 in A375-EphB4 cells was confirmed by activation of a variety of signaling pathways including JAK/STAT, Ras/Raf/MEK, and NFkB.

Keywords: Eph receptor tyrosin kinase family; ephrins; tyrosine kinase inhibitors; regioisomers; tumor angiogenesis; tumor hypoxia; tumor perfusion

Permalink: https://www.hzdr.de/publications/Publ-31524
Publ.-Id: 31524


Experimental investigation of the return flow instability in magnetic spherical Couette flow

Ogbonna, J. E.; Garcia Gonzalez, F.; Gundrum, T.; Seilmayer, M.; Stefani, F.

We conduct magnetic spherical Couette (MSC) flow experiments in the return flow instability regime with GaInSn as the working fluid, and the ratio of the inner to the outer sphere radii rᵢ/rₒ= 0.5, the Reynolds number Re = 1000, and the Hartmann number Ha ∈ [27.5, 40]. Rotating waves with different azimuthal wavenumbers m ∈ {2, 3, 4} manifest in certain ranges of Ha in the experiments, depending on whether the values of Ha were fixed or varied from different initial values. These observations demonstrate the multistability of rotating waves, which we attribute to the dynamical system representing the state of the MSC flow tending to move along the same solution branch of the bifurcation diagram when Ha is varied. In experiments with both fixed and varying Ha, the rotation frequencies of the rotating waves are consistent with the results of nonlinear stability analysis. A brief numerical investigation shows that differences in the azimuthal wavenumbers of the rotating waves that develop in the flow also depend on the azimuthal modes that are initially excited.

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31523
Publ.-Id: 31523


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.

Permalink: https://www.hzdr.de/publications/Publ-31518
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

Permalink: https://www.hzdr.de/publications/Publ-31517
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

Permalink: https://www.hzdr.de/publications/Publ-31516
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

Permalink: https://www.hzdr.de/publications/Publ-31515
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

Permalink: https://www.hzdr.de/publications/Publ-31514
Publ.-Id: 31514


Stress distribution at the AlN/SiC heterointerface probed by Raman spectroscopy

Breev, I. D.; Likhachev, K. V.; Yakovleva, V. V.; Hübner, R.; Astakhov, G.; Mokhov, E. N.; Baranov, P. G.; Anisimov, A. N.

We investigate AlN grown on 4H- and 6H-SiC substrates using Raman spectroscopy. We obtain the Raman peak shifts in 4H- and 6H-SiC substrates across the heterointerface and along the entire depth of the SiC layer. Using the earlier experimental prediction for the phonon deformation potential constants, we determine the stress tensor components in the 4H-SiC layer as a function of the distance from the AlN/SiC heterointerface and estimate the stress tensor value along the entire depth of the 6H-SiC layer. The maximum compressing stress values lie in the range of -1.7 GPa for the 4H-SiC/AlN heterostructure and in the range of -1.5 GPa for the 6H-SiC/AlN heterostructure.

Keywords: SiC; AlN; Raman spectroscopy; Stress

Permalink: https://www.hzdr.de/publications/Publ-31513
Publ.-Id: 31513


4f 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.

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Permalink: https://www.hzdr.de/publications/Publ-31512
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

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Permalink: https://www.hzdr.de/publications/Publ-31511
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

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Permalink: https://www.hzdr.de/publications/Publ-31510
Publ.-Id: 31510


Analysis of aerosol particles collected in Ljubljana, Slovenia, using Particle Induced X-ray Emission with a focused proton beam and a Helium Ion Microscope

Podlipec, R.; Munnik, F.; Klingner, N.; Rigler, M.; Heller, R.

The correlative approach of real-time aerosol measurements with offline filter analysis and ParticleInduced X-ray Emission (PIXE) can significantly enhance the scope of aerosol studies. Aerosol particles have diverse physical and chemical properties, thus having a direct impact on air quality, cloud nucleation the planetary radiation balance, public health, etc. Essential information on the chemical composition of aerosol particles can be deduced from the elemental concentrations measured simultaneously for many elements by non-destructive and undemanding PIXE (Lucarelli, 2018). Furthermore, PIXE measurements can be performed with a focused beam allowing the analysis of individual particles (Biancato, 2006). Determining elemental concentrations is also important input information for aerosol source apportionment models and consequently abatement measures in order to improve air quality (Artaxo, 1999). Complementary information of aerosol particles structure down to nm scale, can be obtained with a Helium Ion Microscope (HIM), which, to our knowledge, has never been used before for aerosol characterization. The detection of secondary electrons and backscattered ions enables sub nm lateral resolution and large depth-of-field, also on insulating samples. In addition, a concurrent secondary ion mass spectrometry (ToF-SIMS) integrated in the HIM can provide insights of the composition of elements and molecules with imaging capabilities of sub 8 nm (Klingner, 2019).
In this study we coupled real-time measurements of optical properties of aerosols with an Aethalometer (Drinovec, 2015) and their carbon content with a Total Carbon Analyzer (Rigler, 2019) with PIXE and HIM analysis. Ambient aerosols were collected on quartz filters and quartz filters with Teflon coating during different pollution events (traffic or biomass burning dominated, Saharan dust dominated, etc.) at an urban background sampling site in Ljubljana, Slovenia (46o04’17’’N, 14o30’06’’E). The PM2.5 inlet was used for sampling carbonaceous aerosol while a virtual impactor was used for concentrating coarse particles during Saharan dust events.
PIXE measurements have been performed on these collected samples and compared to optical properties and source apportionment obtained by the online instruments. The PIXE measurements were performed across several hundred-micrometer regions and on individual points and results are presented including a description of the procedures for quantification. Complementary high-resolution imaging and sputtered ion analysis on single black carbon and Saharian dust aerosol particles was done on the HIM to study their structure and coating composition. The combination of all methods yields a comprehensive view of the aerosol particles.

  • Poster
    European Aerosol Conference (EAC), 31.08.-04.09.2020, Virtual Event, Virtual Event

Permalink: https://www.hzdr.de/publications/Publ-31509
Publ.-Id: 31509


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

Permalink: https://www.hzdr.de/publications/Publ-31508
Publ.-Id: 31508


Application of Next Generation Sequencing (NGS) in Phage Displayed Peptide Selection to Support the Identification of Arsenic-Binding Motifs

Braun, R.; Schönberger, N.; Vinke, S.; Lederer, F.; Kalinowski, J.; Pollmann, K.

Next generation sequencing (NGS) in combination with phage surface display (PSD) are powerful tools in the newly equipped molecular biology toolbox for the identification of specific target binding biomolecules. Application of PSD led to the discovery of manifold ligands in clinical and material research. However, limitations of traditional phage display hinder the identification process. Growth-based library biases and target-unrelated peptides often result in the dominance of parasitic sequences and the collapse of library diversity. This study describes the effective enrichment of specific peptide motifs potentially binding to arsenic as proof-of-concept using the combination of PSD and NGS. Arsenic is an environmental toxin, which is applied in various semiconductors as gallium arsenide and selective recovery of this element is crucial for recycling and remediation. The development of biomolecules as specific arsenic-binding sorbents is a new approach for its recovery. Usage of NGS for all biopanning fractions allowed for evaluation of motif enrichment, in-depth insight into the selection process and the discrimination of biopanning artefacts, e.g., the amplification-induced library-wide reduction in hydrophobic amino acid proportion. Application of bioinformatics tools led to the identification of an SxHS and a carboxy-terminal QxQ motif, which are potentially involved in the binding of arsenic. To the best of our knowledge, this is the first report of PSD combined with NGS of all relevant biopanning fractions.

Keywords: phage display; peptide; biopanning; target-unrelated peptide; arsenic; motif; NGS; Illumina; interaction; oxyanion

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Permalink: https://www.hzdr.de/publications/Publ-31507
Publ.-Id: 31507


Scanning transmission imaging in the helium ion microscope using a microchannel plate with a delay line detector

Serralta Hurtado De Menezes, E.; Klingner, N.; de Castro, O.; Mousley, M.; Eswara, S.; Duarte Pinto, S.; Wirtz, T.; Hlawacek, G.

A detection system based on a microchannel plate with a delay line readout structure has been developed to perform scanning transmission ion microscopy (STIM) in the helium ion microscope (HIM). This system is an improvement over other existing approaches since it combines the information of the scanning beam position on the sample with the position (scattering angle) and time of the transmission events. Various imaging modes such as bright and dark field or the direct image of the transmitted signal can be created by post-processing the collected STIM data. Furthermore, the detector has high spatial and time resolution, is sensitive to both ions and neutral particles over a wide energy range, and shows robustness against ion beam-induced damage. A special in-vacuum movable support gives the possibility of moving the detector vertically, placing the detector closer to the sample for the detection of high-angle scattering events, or moving it down to increase the angular resolution and distance for time-of-flight measurements. With this new system, we show composition-dependent contrast for amorphous materials and the contrast difference between small and high angle scattering signals. We also detect channeling related contrast on polycrystalline silicon, thallium chloride nanocrystals, and single crystalline silicon by comparing the signal transmitted at different directions for the same data set

Keywords: helium ion microscopy; Scanning transmission ion microscopy; delay line detector; channeling; bright field; dark field

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31506
Publ.-Id: 31506


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

Podlipec, R.
WorkPackageLeader: Rok Podlipec; ContactPerson: Gregor Hlawacek; ContactPerson: Nico Klingner

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.

Related publications

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

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Permalink: https://www.hzdr.de/publications/Publ-31505
Publ.-Id: 31505


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

Kokot, H.; Kokot, B.; Sebastijanović, A.; Voss, C.; Podlipec, R.; Zawilska, P.; Berthing, T.; Ballester López, C.; Høgh Danielsen, P.; Contini, C.; Ivanov, M.; Krišelj, A.; Čotar, P.; Zhou, Q.; Ponti, J.; Zhernovkov, V.; Schneemilch, M.; Doumandji, Z.; Pušnik, M.; Umek, P.; Pajk, S.; Joubert, O.; Schmid, O.; Urbančič, I.; Irmler, M.; Beckers, J.; Lobaskin, V.; Halappanavar, S.; Quirke, N.; Lyubartsev, A. P.; Vogel, U.; Koklič, T.; Stoeger, T.; Štrancar, J.

We are daily exposed to a multitude of health hazardous airborne particulate matter with notable deposition in the fragile alveolar region of our lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modelling, we have here determined that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows us to predict the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modelling potentially relating outcomes to material properties for large number of materials thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, our work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.

Keywords: material safety and health hazards; adverse outcome pathway; mode of action; disease prediction; advanced microscopies

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Permalink: https://www.hzdr.de/publications/Publ-31504
Publ.-Id: 31504


Experimental validation of an inductive system for magnesium level detection in a titanium reduction reactor

Krauter, N.; Eckert, S.; Gundrum, T.; Stefani, F.; Wondrak, T.; Khalilov, R.; Dimov, R.; Frick, P.

In order to determine the magnesium level in a titanium reduction retort by inductive methods, many interfering influences have to be considered to achieve precise measurement results. By using a look-up-table method, the magnesium level can be identified while taking into account the interfering effects of titanium sponge rings that are forming at the walls of the retort during the reduction process with their unknown geometrical and electrical parameters. This new method uses a combination of numerical simulations and measurements, whereby the simulation model is calibrated so that it represents the experimental setup as closely as possible. Previously we have presented purely theoretical studies on this method. Here, we demonstrate the practical feasibility of that method by performing measurements on a model experiment. This method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.

Keywords: Kroll process; numerical simulation; inductive measurements; Titanium; level detection

Permalink: https://www.hzdr.de/publications/Publ-31503
Publ.-Id: 31503


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

Jüstel, P.; Röhrborn, S.; Galindo, V.; Schindler, F.
Project Member: Frick, Peter; Project Member: Gundrum, Thomas; Project Leader: Stefani, Frank; Project Member: Stepanov, Rodion; Project Member: Vogt, Tobias

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

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Permalink: https://www.hzdr.de/publications/Publ-31502
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

Permalink: https://www.hzdr.de/publications/Publ-31499
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
  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Azeotrope Chemistry Seminar at National Institute of Technology (NIT) Rourkela, 25.11.2020, Rourkela, India

Permalink: https://www.hzdr.de/publications/Publ-31498
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.

Permalink: https://www.hzdr.de/publications/Publ-31497
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

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Permalink: https://www.hzdr.de/publications/Publ-31496
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

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Permalink: https://www.hzdr.de/publications/Publ-31495
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

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Permalink: https://www.hzdr.de/publications/Publ-31494
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

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Permalink: https://www.hzdr.de/publications/Publ-31493
Publ.-Id: 31493


T-Staging and Target Volume Definition by Imaging in Head and Neck Tumors

Platzek, I.; Agolli, L.; Beuthien-Baumann, B.; Troost, E. G. C.

Anatomical and functional imaging by means of computed tomography, magnetic resonance imaging, and positron emission tomography are, besides a thorough physical examination, of utmost importance for accurate staging of primary tumors in the head and neck region. This chapter deals with the particular advan-tages and disadvantages of those imaging techniques and gives practical guidance on how to employ these in radiation treatment planning.

Keywords: CT,; Head and neck squamous cell carcinoma; Multiparametric MRIPETT-staging; Tumor characterization

  • Book chapter
    Regina G.H. Beets-TanWim J. G. OyenVincenzo Valentini: Imaging and Interventional Radiology for Radiation Oncology, Switzerland: Springer, 2020, 978-3-030-38260-5, 169-181
    DOI: 10.1007/978-3-030-38261-2_12

Permalink: https://www.hzdr.de/publications/Publ-31492
Publ.-Id: 31492


A new approach for estimating the effective froth height on column trays

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

The present work proposes a new approach for measuring the effective froth height on column trays. This approach is applied on the two-phase dispersion data gathered by a novel multi-probe sensor installed inside a large-scale tray column mockup. A physical explanation of the proposed approach describes how to distinguish between the liquid-continuous and gas-continuous regions in the froth. Accordingly, the effective froth height distributions are reported for selected tray loadings.

Keywords: Effective froth height; Column tray; Two-phase dispersion; Conductivity probes

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  • Secondary publication expected from 13.11.2021

Permalink: https://www.hzdr.de/publications/Publ-31491
Publ.-Id: 31491


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

Permalink: https://www.hzdr.de/publications/Publ-31490
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

Permalink: https://www.hzdr.de/publications/Publ-31489
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

Permalink: https://www.hzdr.de/publications/Publ-31488
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

Permalink: https://www.hzdr.de/publications/Publ-31487
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.

Permalink: https://www.hzdr.de/publications/Publ-31486
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.

Permalink: https://www.hzdr.de/publications/Publ-31485
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.

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Permalink: https://www.hzdr.de/publications/Publ-31484
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.

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Permalink: https://www.hzdr.de/publications/Publ-31483
Publ.-Id: 31483


Efficient Modulation of Photonic Bandgap and Defect Modes in All-Dielectric Photonic Crystals by Energetic Ion Beams

Du, G.; Zhou, X.; Pang, C.; Zhang, K.; Zhao, Y.; Lu, G.; Liu, F.; Wu, A.; Akhmadaliev, S.; Zhou, S.; Chen, F.

The photonic bandgap and localization in photonic crystals can be effectively modulated by energetic ion beams owing to the induced modification of the thickness and refractive indices of the materials. In this work, the modulation of photonic bandgap and defect modes in 1D all-dielectric photonic crystals is investigated theoretically and experimentally by using carbon (C5+) ion irradiation. It is found that the photonic bandgap and defect mode have a remarkable hypsochromic shift under the C5+ ion irradiation. The degree of the blueshift mainly depends on the reduction of the material thickness that is nearly proportional to the fluences of C5+ ions. The blueshift of the band edges and defect modes shows a step-like behavior from transparency to opacification (near-zero transmittance or high reflectance) or a converse trend. The work paves a new way to tailor the photonic crystals toward the development of novel devices with tunable specific wavelengths and wavebands.

Permalink: https://www.hzdr.de/publications/Publ-31481
Publ.-Id: 31481


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.

Permalink: https://www.hzdr.de/publications/Publ-31479
Publ.-Id: 31479


Electron dose rate and oxygen depletion protect zebrafish embryo from radiation damage

Beyreuther, E.; Brand, M.; Hans, S.; Karsch, L.; Leßmann, E.; Löck, S.; Schürer, M.; Pawelke, J.

The combination of the beneficial effects of high dose-rate Flash-RT and proton depth dose distribution promise the differential sparing of normal tissue under similar tumour treating efficacy. However, of the two published attempts [1,2] made at clinical proton facilities, one in vivo study on zebrafish embryo was not able to measure a Flash effect [2]. In the discussion of this experiment, the zebrafish model, a non-ideal pulse-time-regime and an uncertain oxygen level during irradiation were identified as potential explanations for the missing Flash effect. In order to investigate these parameters in detail an experiment was scheduled at the research electron accelerator ELBE at HZDR, because an electron Flash effect was already demonstrated for zebrafish embryo [3]. The highly variable pulse structure of ELBE enables to deliver the dose either in therapy like quasi-continuous (cw) beams or as electron Flash irradiation.
Zebrafish embryo were irradiated with 40 Gy with pulse dose rates of 109 Gy/s and mean dose rates of 106 Gy/s in comparison to 0.1 Gy/s with cw irradiation. In addition to this, the Oxylite system was applied to measure and control oxygen depletion kinetics in sealed embryo samples. A protective Flash effect was seen for most endpoints ranging from 4 % less reduction in embryo length to about 20 – 25 % less embryo with spinal curvature and pericardial oedema, relative to cw-irradiation. The reduction of partial oxygen pressure below atmospheric levels results in higher protection, the more the lower the oxygen level.
In conclusion, the Flash experiment at ELBE show that the zebrafish embryo model is appropriate for the study of the radiobiological response of high dose rate irradiation. A sufficiently pulse dose seems to be more important than pulse dose rate and the partial oxygen pressure during irradiation plays a pivotal role.
[1] Diffenderfer et al.: https://doi.org/10.1016/j.ijrobp.2019.10.049
[2] Beyreuther et al.: https://doi.org/10.1016/j.radonc.2019.06.024
[3] Vozenin et al.: https://doi.org/10.1016/j.clon.2019.04.001

  • Invited lecture (Conferences) (Online presentation)
    European Radiation Research Meeting, 13.-17.09.2020, Lund, Sweden
  • Invited lecture (Conferences) (Online presentation)
    VHEE/FLASH meeting - virtual, 05.-07.10.2020, CERN, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-31478
Publ.-Id: 31478


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.

Permalink: https://www.hzdr.de/publications/Publ-31477
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.

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Permalink: https://www.hzdr.de/publications/Publ-31476
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, M.; 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.

Permalink: https://www.hzdr.de/publications/Publ-31475
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.

Permalink: https://www.hzdr.de/publications/Publ-31474
Publ.-Id: 31474


Precision modeling of the IBA Universal Nozzle double scattering mode at the University Proton Therapy Dresden

Lutz, B.; Eulitz, J.; Haneke-Swanson, R.; Enghardt, W.; Lühr, A.

Monte Carlo (MC) simulations are indispensable for many research and advanced clinical questions in proton therapy (PT). However, the necessary site-specifc modeling of a double scattering (DS) PT system is extensive and challenging and requires a clear strategy. This work describes a comprehensive method for precise and accurate modeling of a DS nozzle that minimizes additional measurement effort. A detailed model of the IBA universal nozzle is created within the TOPAS simulation framework. This model is subsequently fine-tuned using a step by step procedure to match the same dose profiles used for the commissioning of the treatment planning system. In the proposed bottom-up approach, the geometry of beam-shaping elements is first adjusted to measured quantities and then the beam and model properties are optimized using iterative methods. The resulting dose distributions are validated with a set of independent measurement data to estimate the achieved quality. The resulting simulated dose distributions agree well with the data and show residual range diifferences typically better than 0.5 mm. The shape of the SOBP plateau regions is accurately reproduced with a spread of the residuals below 1% (i.e., near to the statistical limit) over a large part of the machine settings. The simulated lateral dose profiles, although not directly included in the optimization, match the shape of the validation data better than 0.14 mm. The minimal measurement effort and high-precision proton field modeling make this method attractive, in particular, for retrospective beam modeling needed in clinical outcome studies after DS treatment.

Keywords: radiation therapy; protons; Monte Carlo simulation; SOBP fields; nozzles; double scattering

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  • Secondary publication expected from 25.03.2022

Permalink: https://www.hzdr.de/publications/Publ-31473
Publ.-Id: 31473


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

Permalink: https://www.hzdr.de/publications/Publ-31472
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, 201-239
    DOI: 10.1142/11352

Permalink: https://www.hzdr.de/publications/Publ-31471
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

Permalink: https://www.hzdr.de/publications/Publ-31470
Publ.-Id: 31470


Late side effects in normal mouse brain tissue after proton irradiation

Suckert, T.; Beyreuther, E.; Müller, J.; Azadegan, B.; Meinhardt, M.; Raschke, F.; Bodenstein, E.; von Neubeck, C.; Lühr, A.; Krause, M.; Dietrich, A.

Radiation induced late side effects such as cognitive decline and normal tissue complications can severely affect quality of life and outcome in long-term survivors of brain tumors. Proton therapy offers a favorable depth-dose deposition with the potential to spare tumor-surrounding normal tissue, thus potentially reducing such side effects. In this study, we describe a preclinical model to reveal underlying biological mechanisms caused by precise high-dose proton irradiation of a brain subvolume.
We studied the dose- and time-dependent radiation response of mouse brain tissue, using a high-precision image-guided proton irradiation setup for small animals established at the University Proton Therapy Dresden. The right hippocampal area of ten C57BL/6 and ten C3H/He mice was irradiated. Both strains consisted of four groups treated with increasing doses (0 – 85 Gy and 0 – 80 Gy, respectively). Follow-ups were performed up to six months, including longitudinal monitoring of general health status and regular contrast-enhanced magnetic resonance imaging (MRI) of mouse brains. These findings were related to comprehensive final histological analysis.
In mice of the highest dose group, first symptoms of blood-brain barrier (BBB) damage appeared one week after irradiation, while a dose-dependent delay in onset was observed for lower doses. MRI contrast agent leakage occurred in the irradiated brain areas and was progressive in the higher dose groups. Mouse health status and survival corresponded to the extent of contrast agent leakage. Histological analysis revealed tissue changes such as vessel abnormalities, gliosis, and granule cell dispersion, which also partly affected the non-irradiated contralateral hippocampus.
All observed effects depended strongly on the prescribed radiation doses and the outcome, i.e. survival, image changes and tissue alterations, within an experimental dose cohort was very consistent. A derived dose-response model will determine doses in future experiments and may support the formulation of clinical hypotheses on brain toxicity after proton therapy.

Keywords: Proton therapy; brain irradiation; preclinical mouse model; magnetic resonance imaging (MRI); late side effects; blood-brain barrier; brain tissue toxicity; radiation dose modelling

Related publications

Permalink: https://www.hzdr.de/publications/Publ-31469
Publ.-Id: 31469


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.

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  • Secondary publication expected from 21.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31468
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

Downloads:

  • Secondary publication expected from 27.08.2021

Permalink: https://www.hzdr.de/publications/Publ-31467
Publ.-Id: 31467


Atomic Physics in Particle in Cell Algorithms(PIC)

Marre, B. E.; Garten, M.; Bussmann, M.; Kluge, T.

Simulations allow us to get a detailed understanding of processes inside plasmas not directly accessible to experiments. They are therefore a very important tool for theoretical and experimental research and are continually being improved.
One improvement in development is the direct inclusion of atomic physics in Particle in Cell(PIC) simulations, a specific simulation technic used for non fluid-like plasmas.
In this talk I will describe possible approaches to realise atomic physics in PIC and give a short introduction to PIC algorithms and atomic physics in plasmas.

Keywords: atomic physics; particel in cell; Atomphysik in Plasmen; plasma; PIConGPU

  • Lecture (others)
    Numerics Seminar, 06.08.2020, Görlitz, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-31466
Publ.-Id: 31466


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
-O-(CH)ₚ-C(O)-NH-S(O)₂-R¹
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

Permalink: https://www.hzdr.de/publications/Publ-31465
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

Permalink: https://www.hzdr.de/publications/Publ-31464
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

Permalink: https://www.hzdr.de/publications/Publ-31463
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

Permalink: https://www.hzdr.de/publications/Publ-31462
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

Permalink: https://www.hzdr.de/publications/Publ-31461
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
entsteht.

  • Patent
    DE102018125822 - Erteilung 02.01.2020

Permalink: https://www.hzdr.de/publications/Publ-31460
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

Related publications

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

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31459
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.

Permalink: https://www.hzdr.de/publications/Publ-31457
Publ.-Id: 31457


Non-linear Breit-Wheeler process with linearly polarized beams

Titov, A.; Kämpfer, B.

We study the non-linear Breit-Wheeler process γ⃗ ′+L⃗ →e++e− in the interaction of linearly polarized probe photons (γ⃗ ′) with a linearly polarized laser beam (L⃗ ). In particular, we consider the asymmetry of the total cross section and the azimuthal electron distributions when the polarizations of the photon and laser beams in the initial state are mutually perpendicular or parallel. Considering intense laser beams and the strong field asymptotic we explore essentially the multi-photon dynamics. The asymmetry exhibits some non-monotonic behavior depending on initial kinematic conditions; it depends sensitively on the laser pulse duration. Our results provide additional knowledge for studying non-linear multi-photon effects in quantum electrodynamics and may be used in planning experiments in upcoming laser facilities.

Permalink: https://www.hzdr.de/publications/Publ-31455
Publ.-Id: 31455


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.

Permalink: https://www.hzdr.de/publications/Publ-31454
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

Permalink: https://www.hzdr.de/publications/Publ-31453
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, P.; 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 mg.kg−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

Permalink: https://www.hzdr.de/publications/Publ-31452
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

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  • Secondary publication expected from 15.09.2021

Permalink: https://www.hzdr.de/publications/Publ-31451
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.

Related publications

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-31450
Publ.-Id: 31450


Fate of contaminants from repositories for radioactive waste based in clay-rock?

Marques Fernandes, M.; Baeyens, B.; Daehn, R.; Scheinost, A. C.; Churakov, S. V.

Safe disposal of radioactive waste is one of the big challenges of modern society. The concept of final storage in deep geological formations has become internationally accepted as a means of safe waste management waste in order to isolate it from the Biosphere for hundreds of thousands of years. The safety case has hence to prove that migration from the disposal site into the Biosphere can be effectively prevented across this time span. The potential migration is primarily controlled by sorption/desorption processes onto mineral surfaces along the migration path. Clay minerals are major constituents in both the engineered barriers and in the argillaceous host rock formations being considered for the deep high-level radioactive waste (HLW) repository in Switzerland. Therefore it is critically important to develop an understanding of the uptake processes of radionuclides on clay minerals and other minerals under a wide range of relevant geochemical conditions, to quantify and characterize them with the aim of strengthening the confidence in the safety case. An overview of the work performed at the Laboratory for Waste Management on the retention of radionuclides on clay rich materials will be presented.

Keywords: nuclear waste; clay rock; XAFS; ROBL

  • Invited lecture (Conferences) (Online presentation)
    18th Swiss Geoscience Meeting, 06.-07.11.2020, Zurich, Switzerland

Permalink: https://www.hzdr.de/publications/Publ-31448
Publ.-Id: 31448


Crystal structure, phase transition and properties of indium (III) sulfide

Wyżga, P.; Carrillo-Cabrera, W.; Akselrud, L.; Veremchuk, I.; Wagler, J.; Hennig, C.; Tsirlin, A.; Leithe-Jasper, A.; Kroke, E.; Gumeniuk, R.

Poly- and single-crystalline samples of In0.670.33In2S4 thiospinel were obtained by various powder metallurgical and chemical vapor transport methods, respectively. All synthesized samples contained β-In0.670.33In2S4 modification only, independent from synthesis procedure. High-resolution powder X-ray diffraction (PXRD) experiment at 80 K enabled observation of split tetragonal reflections (completely overlapped at room temperature), which proves the correctness of crystal structure model accepted for β-polymorph. Combined single-crystal XRD, transmission electron microscopy and selected-area electron diffraction confirmed the presence of three twin domains in as-grown crystals. High temperature PXRD study revealed both abrupt (in full width at half maximum) and gradual (in intensity of satellites, c/a ratio and unit-cell volume) changes in the vicinity of the α-β phase transition. On the other hand, clear thermal effect in heat capacity, magnitude of enthalpy/entropy change and temperature dependence of electrical resistivity, associated with hysteresis, hinted towards the 1st order type of the transition. Two scenarios, based on Rietveld refinement analysis, were proposed for the description of crystal structure evolution from β- to α-modification. Seebeck coefficient, electrical resistivity and thermal conductivity were shown to be influenced not only by phase transition, but also by annealing conditions (S-poor or S-rich atmosphere). Theoretical density functional calculations predicted n-type semiconducting behavior of In0.670.33In2S4, as well as instability of fictitious InIn2S4 thiospinel.

Keywords: In2S3; synchrotron diffraction; single-crystal diffraction; twinning; DFT calculations

Permalink: https://www.hzdr.de/publications/Publ-31446
Publ.-Id: 31446


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

Permalink: https://www.hzdr.de/publications/Publ-31445
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

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Permalink: https://www.hzdr.de/publications/Publ-31444
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

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Permalink: https://www.hzdr.de/publications/Publ-31443
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

Permalink: https://www.hzdr.de/publications/Publ-31442
Publ.-Id: 31442


X-ray and neutron radiographic experiments on particle-laden molten metal flows

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

In metallurgical processing, non-metallic inclusions in metallic materials are one highly relevant challenge. Bubble injection into molten metals boosts the inclusion control and removal, thus enhancing metal homogenisation and purification. Although this principle of bubble flotation has been used for a long time, the effects of bubble-inclusion interactions in molten metals are not yet well researched. Imaging measurements of multiphase metal flows are challenging for two main reasons: the metals’ high melting temperatures, and their opaqueness for visible light. This work focuses on X-ray and neutron radiographic experiments employing low-melting gallium alloys laden with model particles smaller than 1 mm in diameter. Both, bubbles and particles, are visualised simultaneously with high spatial and temporal resolution to analyse their motions by tracking algorithms. We demonstrate the capability of time-resolved X-ray and neutron radiography to image multiphase flows in particle-laden optically opaque liquid metal, thus contributing to pave the way for systematic investigations on bubble-inclusion interactions in molten metals.

Keywords: X-ray radiography; neutron radiography; bubble flotation; non-metallic inclusions; liquid metal

  • Lecture (Conference) (Online presentation)
    TMS2021 Virtual, 15.-18.03.2021, Orlando, Florida, USA
  • Book chapter
    Lee J., Wagstaff S., Anderson A., Tesfaye F., Lambotte G., Allanore A.: Materials Processing Fundamentals 2021, Cham: Springer, 2021, 978-3-030-65253-1, 13-29
    DOI: 10.1007/978-3-030-65253-1_2

Permalink: https://www.hzdr.de/publications/Publ-31441
Publ.-Id: 31441


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

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  • Secondary publication expected from 22.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31440
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

Permalink: https://www.hzdr.de/publications/Publ-31439
Publ.-Id: 31439


The dipole response of 87Rb and its impact on the 86Rb(n,γ)87Rb cross section

Wilhelmy, J.; Müscher, M.; Rusev, G.; Schwengner, R.; Beyer, R.; Bhike, M.; Erbacher, P.; Fiedler, F.; Friman-Gayer, U.; Glorius, J.; Greifenhagen, R.; Hammer, S.; Hensel, T.; Isaak, J.; Junghans, A. R.; Krishichayan, F.; Löher, B.; Müller, S. E.; Pietralla, N.; Reinicke, S.; Savran, D.; Scholz, P.; Sonnabend, K.; Szücs, T.; Tamkas, M.; Tornow, W.; Turkat, S.; Wagner, A.; Zilges, A.

Background: Detailed information on the low-lying dipole response in atomic nuclei along isotonic or isotopic chains is well suited to systematically investigate the structure and evolution of the Pygmy Dipole Resonance (PDR). Moreover, the dipole strength below and around the neutron separation energy Sn has impact on statistical model calculations for nucleosynthesis processes. Purpose: The photon strength function (PSF) of 87 Rb, which is directly connected to the photoabsorption cross section, is a crucial input for statistical model calculations constraining the Maxwellian-averaged cross section (MACS) of the neutron capture of the unstable s-process branching-point nucleus 86 Rb. Within this work, the photoabsorption cross section is investigated.
Methods: The photoabsorption cross section of the N = 50 nucleus 87 Rb was determined from photon-scattering experiments via the Nuclear Resonance Fluorescence (NRF) technique. Bremsstrahlung beams at the γELBE facility in conjunction with monoenergetic photon beams at the HIGS facility were used to determine the integrated cross sections Is of isolated states as well as the averaged cross section as function of the excitation energy. Decays to the ground state were disentangled from decays to first low-lying excited states. Statistical and experimental approaches for the γ-decay properties at various excitation energies were applied. The linearly polarized photon beams at HIGS provide information on the ratio of electric and magnetic type of radiation.
Results: Within this work, more than 200 ground-state decays and associated levels in 87Rb were identified. Moreover, transitions below the sensitivity limit of the state-by-state analysis were taken into account via a statistical approach from the bremsstrahlung data as well as model-independently from the HIGS data. The photoabsorption cross sections at various excitation energies were determined. The dipole response between 6 and 10 MeV of 87 Rb is in agreement with assuming contributions of electric multipolarity, only.
Conclusions: The photoabsorption cross section of 87Rb does not contradict with the trend of decreasing E1 strength with increasing proton number along the N = 50 isotonic chain but might also be associated with a constant trend. The experimental γ decay at various excitation energies of the HIGS data supports the statistical approach but does not provide a stringent proof due to the limited sensitivity in the decay channels. The additional E1 strength observed in the present experiments significantly enhances the MACSs compared to recent microscopic D1M HFB+QRPA calculations only. Moreover, theoretical estimations provided by the KADoN iS project could be significantly improved.

Permalink: https://www.hzdr.de/publications/Publ-31438
Publ.-Id: 31438


Uranium(VI) bioassociation by different fungi – a comparative study into molecular processes

Wollenberg, A.; Drobot, B.; Hübner, R.; Kretzschmar, J.; Freitag, L.; Lehmann, F.; Günther, A.; Stumpf, T.; Raff, J.

After the Chernobyl and Fukushima incidents it has become clear that fungi can take up and accumulate large quantities of radionuclides and heavy metals, but the underlying processes are not well understood yet. For this study, the molecular interactions of uranium(VI) with the white-rot fungi, Schizophyllum commune and Pleurotus ostreatus, and the soil-living fungus, Leucoagaricus naucinus, were investigated. First, the uranium concentration in the biomass was determined by time-dependent bioassociation experiments. To characterize the molecular interactions, uranium was localized in the biomass by transmission electron microscopy analysis. Second, the formed uranyl complexes in both biomass and supernatant were determined by fluorescence spectroscopy. Additionally, possible bioligands in the supernatant were identified. The results show that the discernible interactions between metals and fungi are similar, namely biosorption, accumulation, and subsequent crystallization. But at the same time, the underlying biochemical mechanisms are different and specific to the fungal species. In addition, Schizophyllum commune was found to be the only fungus that, under the chosen experimental conditions, released tryptophan and other indole derivatives in the presence of uranium(VI) as determined by nuclear magnetic resonance spectroscopy. These released substances most likely act as messenger molecules rather than serving the direct detoxification of uranium(VI).

Keywords: radionuclides; mycelium; microscopy; spectroscopy; metabolite; quorum sensing

Permalink: https://www.hzdr.de/publications/Publ-31437
Publ.-Id: 31437


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)

Permalink: https://www.hzdr.de/publications/Publ-31436
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.

Purpose

[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.
Methods

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.
Results

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).
Conclusions

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.

Permalink: https://www.hzdr.de/publications/Publ-31435
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

Permalink: https://www.hzdr.de/publications/Publ-31434
Publ.-Id: 31434


Applying tissue slice culture in cancer research—insights from preclinical proton radiotherapy

Suckert, T.; Rassamegevanon, T.; Müller, J.; Dietrich, A.; Graja, A.; Reiche, M.; Löck, S.; Krause, M.; Beyreuther, E.; von Neubeck, C.

A challenge in cancer research is the definition of reproducible, reliable, and practical models, which reflect the effects of complex treatment modalities and the heterogeneous response of patients. Proton beam radiotherapy (PBRT), relative to conventional photon-based radiotherapy, offers the potential for iso-effective tumor control, while protecting the normal tissue surrounding the tumor. However, the effects of PBRT on the tumor microenvironment and the interplay with newly developed chemo-and immunotherapeutic approaches are still open for investigation. This work evaluated thin-cut tumor slice cultures (TSC) of head and neck cancer and organotypic brain slice cultures (OBSC) of adult mice brain, regarding their relevance for translational radiooncology research. TSC and OBSC were treated with PBRT and investigated for cell survival with a lactate dehydrogenase (LDH) assay, DNA repair via the DNA double strand break marker γH2AX, as well as histology with regards to morphology. Adult OBSC failed to be an appropriate model for radiobiological research questions. However, histological analysis of TSC showed DNA damage and tumor morphological results, comparable to known in vivo and in vitro data, making them a promising model to study novel treatment approaches in patient-derived xenografts or primary tumor material.

Keywords: tumor biology; DNA damage; organotypic brain slice culture; head and neck cancer; proton beam radiotherapy; thin-cut tissue slices

Permalink: https://www.hzdr.de/publications/Publ-31432
Publ.-Id: 31432


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

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Permalink: https://www.hzdr.de/publications/Publ-31431
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

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  • Secondary publication expected from 28.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31430
Publ.-Id: 31430


A supervised technique for drillcore mineral mapping using Hyperspectral data

Contreras Acosta, I. C.; Khodadadzadeh, M.; Tusa, L.; Gloaguen, R.

D rilling is a key task in exploration campaigns to characterize mineral deposits at depth. Drillcores are first logged in the field by a geologist and with regards to, e.g., mineral assemblages, alteration patterns, and structural features. The core-logging information is then used to locate and target the important ore accumulations and select representative samples that are further analyzed by laboratory measurements (e.g., Scanning Electron Microscopy (SEM), Xray diffraction (XRD), X-ray Fluorescence (XRF)). However, core-logging is a laborious task and subject to the expertise of the geologist. Hyperspectral imaging is a non invasive and non-destructive technique that is increasingly being used to support the geologist in the analysis of drill-core samples. Nonetheless, the benefit and impact of using hyperspectral data depend on the applied methods. With this in mind, machine learning techniques, which have been applied in different research fields, provide useful tools for an advance and more automatic analysis of the data. Lately, machine learning frameworks are also being implemented for mapping minerals in drill-core hyperspectral data. In this context, this work follows an approach to map minerals on drill-core hyperspectral data using supervised machine learning techniques, in which SEM data, integrated with the mineral liberation analysis (MLA) software, are used in training a classifier. More specifically, the high-resolution mineralogical data obtained by SEM-MLA analysis is resampled and co-registered to the hyperspectral data to generate a training set. Due to the large difference in spatial resolution between the SEM-MLA and hyperspectral images, a pre-labeling strategy is required to link these two images at the hyperspectral data spatial resolution. In this study, we use the SEM-MLA image to compute the abundances of minerals for each hyperspectral pixel in the corresponding SEM-MLA region. We then use the abundances as features in a clustering procedure to generate the training labels. In the final step, the generated training set is fed into a supervised classification technique for the mineral mapping over a large area of a drill-core. The experiments are carried out on a visible to near-infrared (VNIR) and shortwave infrared (SWIR) hyperspectral data set and based on preliminary tests the mineral mapping task improves significantly.

  • Open Access Logo Poster (Online presentation)
    European Geosciences Union (EGU) General Assembly, 04.-08.05.2020, Vienna, Austria

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Permalink: https://www.hzdr.de/publications/Publ-31429
Publ.-Id: 31429


Fusion of VNIR-SWIR and LWIR for Mineral Mapping in a Machine Learning Framework

Contreras Acosta, I. C.; Khodadadzadeh, M.; Tusa, L.; Gloaguen, R.

Mineral mapping is an important task in exploration campaigns where it is required to obtain a preliminary idea about the composition of ore deposits. Hyperspectral imaging is becoming a trending technology within the mining community to map minerals during exploration campaigns. This is because minerals have unique spectral responses in specific parts of the electromagnetic spectrum. These responses depend on the bonds between the atoms and electron orbitals of the minerals. In other words, based on the molecular vibrations and composition of the minerals the light reflects differently from the minerals and therefore, the spectral responses vary. In general, alteration minerals (e.g., phyllosilicates) can be mapped using the visible to near-infrared (VNIR) and short-wave infrared (SWIR) parts of the electromagnetic spectrum, whereas rock-forming minerals, (e.g., feldspars and quartz) are better distinguishable using the long-wave infrared (LWIR). Therefore, fusing the VNIR-SWIR and LWIR parts of the electromagnetic spectrum provides a complete range of data for the mineral mapping task. The benefit of using hyperspectral data from both regions of the electromagnetic spectrum to map minerals is clear and it has been previously implemented in an independent manner. However, in this work, we focus on different machine learning strategies to fuse VNIR-SWIR and LWIR hyperspectral data for an accurate mineral mapping. We test two fusion scenarios: feature level fusion and decision-level fusion. For the feature-level fusion, we adopt a state-of-the-art multiple feature learning technique to adequately exploit the information containing in both data types. Hence, we take advantage of the complementary information using only one classifier. For the decision-level fusion, we integrate the independent classification results obtained using the VNIR-SWIR and LWIR data. In this way, higher robustness is expected from the combination of the classification results. The experiments are carried out on real hyperspectral datasets of drill core samples. With this contribution, we introduce a novel approach for the mining community to map minerals using a full range of hyperspectral data where not only alteration minerals but rock-forming minerals can be jointly mapped. Moreover, our proposed approach can accurately map minerals with weak spectral responses in both wavelength ranges. Based on preliminary attempts, the fusion of the VNIRSWIR and LWIR at both decision and feature levels performed better than considering both datasets independently.

  • Open Access Logo Lecture (Conference)
    European Geosciences Union (EGU) General Assembly, 07.-12.04.2019, Vienna, Austria

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Permalink: https://www.hzdr.de/publications/Publ-31428
Publ.-Id: 31428


Multi-label Classification for Drill-core Hyperspectral Mineral Mapping

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

A multi-label classification concept is introduced for the mineral mapping task in drill-core hyperspectral data analysis. As opposed to traditional classification methods, this approach has the advantage of considering the different mineral mixtures present in each pixel. For the multi-label classification, the well-known Classifier Chain method (CC) is implemented using the Random Forest (RF) algorithm as the base classifier. High resolution mineralogical data obtained from Scanning Electron Microscopy (SEM) instrument equipped with the Mineral Liberation Analysis (MLA) software are used for generating the training data set. The drillcore hyperspectral data used in this paper cover the visible-near infrared (VNIR) and the short-wave infrared (SWIR) range of the electromagnetic spectrum. The quantitative and qualitative analysis of the obtained results shows that the multi-label classification approach provides meaningful and descriptive mineral maps and outperforms the single-label RF classification for the mineral
mapping task.

Keywords: Mineral mapping; drill-core hyperspectral data; mineral liberation analysis; classifier chains; random forest; multi-label classification; machine learning

Permalink: https://www.hzdr.de/publications/Publ-31427
Publ.-Id: 31427


Geochemical and Hyperspectral Data Fusion for Drill-core Mineral Mapping

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

Hyperspectral imaging is increasingly being used in the mining industry for the investigation of drill-core samples. It provides the means to analyze a large amount of cores considerably faster than traditional methods and in a non-invasive and non-destructive manner. Traditional approaches used to analyse drill-core hyperspectral data are mainly based on visual observations and need significant human interactions. Thus, they are time-consuming and subjective. In this paper, we explore the use of supervised machine learning techniques for mineral mapping in drill-core hyperspectral data. For this purpose, we suggest to use geochemical data for generating a training set. The main contribution of this work is to fuse geochemical and hyperspectral data within a machine learning framework. Moreover, for a more complete mineral mapping task, we integrate visible near-infrared (VNIR), short-wave infrared (SWIR) and long-wave infrared (LWIR) hyperspectral data. For the extraction of input features, the traditional Principal Component Analysis (PCA) is implemented. For classification, we propose to use Random Forest (RF) because of its significant performance in hyperspectral data classification when there are few training samples available. Experimental results show that the proposed method provides comprehensive mineral maps in which the distribution and patterns of different minerals are well characterised.

Keywords: Data fusion; mineral mapping; hyperspectral data; geochemical data; machine learning

  • Contribution to proceedings
    2019 10th Workshop on Hyperspectral Imaging and Signal Processing: Evolution in Remote Sensing (WHISPERS), 24.-26.09.2019, Amsterdam, The Netherlands
    2019 10th Workshop on Hyperspectral Imaging and Signal Processing: Evolution in Remote Sensing (WHISPERS): IEEE
    DOI: 10.1109/WHISPERS.2019.8921163

Permalink: https://www.hzdr.de/publications/Publ-31426
Publ.-Id: 31426


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
    DOI: 10.1109/JSTARS.2020.3011221

Permalink: https://www.hzdr.de/publications/Publ-31425
Publ.-Id: 31425


Mass Spectrum of Pseudo-Scalar Glueballs from a Bethe–Salpeter Approach with the Rainbow–Ladder Truncation

Kaptari, L. P.; Kämpfer, B.

We suggest a framework based on the rainbow approximation to the Dyson–Schwinger and Bethe–Salpeter equations with effective parameters adjusted to lattice QCD data to calculate the masses of the ground and excited states of pseudo-scalar glueballs. The structure of the truncated Bethe–Salpeter equation with the gluon and ghost propagators as solutions of the truncated Dyson–Schwinger equations is analyzed in Landau gauge. Both, the Bethe–Salpeter and Dyson–Schwinger equations, are solved numerically within the same rainbow–ladder truncation with the same effective parameters which ensure consistency of the approach. We found that with a set of parameters, which provides a good description of the lattice data within the Dyson–Schwinger approach, the solutions of the Bethe–Salpeter equation for the pseudo-scalar glueballs exhibit a rich mass spectrum which also includes the ground and excited states predicted by lattice calculations. The obtained mass spectrum contains also several intermediate excitations beyond the lattice approaches. The partial Bethe–Salpeter amplitudes of the pseudo-scalar glueballs are presented as well.

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  • Secondary publication expected from 28.07.2021

Permalink: https://www.hzdr.de/publications/Publ-31424
Publ.-Id: 31424


Ab initio results for the plasmon dispersion and damping of the warm dense electron gas

Hamann, P.; Vorberger, J.; Dornheim, T.; Moldabekov, Z.; Bonitz, M.

Warm dense matter (WDM) is an exotic state on the border between condensed matter and dense plasmas. Important occurrences of WDM include dense astrophysical objects, matter in the core of our Earth, as well as matter produced in strong compression experiments. As of late, x-ray Thomson scattering has become an advanced tool to diagnose WDM. The interpretation of the data requires model input for the dynamic structure factor S(q,ω) and the plasmon dispersion ω(q). Recently the first \textit{ab initio} results for S(q,ω) of the homogeneous warm dense electron gas were obtained from path integral Monte Carlo simulations, [Dornheim et al., Phys. Rev. Lett. 121, 255001 (2018)]. Here, we analyse the effects of correlations and finite temperature on the dynamic dielectric function and the plasmon dispersion. Our results for the plasmon dispersion and damping differ significantly from the random phase approximation and from earlier models of the correlated electron gas. Moreover, we show when commonly used weak damping approximations break down and how the method of complex zeros of the dielectric function can solve this problem for WDM conditions.

Keywords: warm dense matter; electron gas; correlation; exchange; plasmon dispersion; plasmon width; collective effects; dynamic structure factor

Permalink: https://www.hzdr.de/publications/Publ-31423
Publ.-Id: 31423


Highly ordered silicide ripple patterns induced by medium-energy ion irradiation

Redondo-Cubero, A.; Palomares, F. J.; Hübner, R.; Gago, R.; Vázquez, L.

We study the nanopatterning of silicon surfaces under near-normal 40-keV Ar+ sputtering with simultaneous Fe oblique codeposition. The ion-beam incidence was kept at 15°, for which no pattern is produced in the absence of metal incorporation. Morphological and compositional analyses were performed by atomic force microscopy, in its morphological and electrical modes, Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, scanning Auger, as well as transmission and scanning electron microscopy. Initially, nanodot structures randomly emerge, which, with increasing ion fluence, become progressively aligned along the perpendicular direction to the Fe flux. With increasing fluence, they coalesce, leading to a ripple pattern. The pattern dynamics and characteristics are faster and enhanced, respectively, as the distance to the metal source decreases (i.e., as the metal content increases). For the highest metal flux, the ripples can become rather large (up to 18 μm) and straighter, with few defects, and a pattern wavelength close to 500 nm, while keeping the surface roughness close to 15 nm. Furthermore, for a fixed ion fluence, the pattern order is improved for higher metal flux. In contrast, the pattern order enhancement rate with ion fluence does not depend on the metal flux. Our experimental observations agree with the predictions and assumptions of the model by Bradley [R. M. Bradley, Phys. Rev. B 87, 205408 (2013)] Several compositional and morphological studies reveal that the ripple pattern is also a compositional one, in which the ripple peaks have a higher iron silicide content, in agreement with the model. Likewise, the ripple structures develop along the perpendicular direction to the Fe flux, and the pattern wavelength increases as the metal flux decreases with a behavior qualitatively consistent with the model predictions.

Permalink: https://www.hzdr.de/publications/Publ-31422
Publ.-Id: 31422


Towards Bacteria Counting in DI Water of Several Microliters or Growing Suspension Using Impedance Biochips

Kiani, M.; Tannert, A.; Du, N.; Hübner, U.; Skorupa, I.; Bürger, D.; Zhao, X.; Blaschke, D.; Rebohle, L.; Cherkouk, C.; Neugebauer, U.; Schmidt, O. G.; Schmidt, H.

We counted bacterial cells of E. coli strain K12 in several-microliter DI water or in several-microliter PBS in the low optical density (OD) range (OD = 0.05-1.08) in contact with the surface of Si-based impedance biochips with ring electrodes by impedance measurements. The multiparameter fit of the impedance data allowed calibration of the impedance data with the concentration cb of the E. coli cells in the range of cb = 0.06 to 1.26 × 109 cells/mL. The results showed that for E. coli in DI water and in PBS, the modelled impedance parameters depend linearly on the concentration of cells in the range of cb = 0.06 to 1.26 × 109 cells/mL, whereas the OD, which was independently measured with a spectrophotometer, was only linearly dependent on the concentration of the E. coli cells in the range of cb = 0.06 to 0.50 × 109 cells/mL.

Permalink: https://www.hzdr.de/publications/Publ-31421
Publ.-Id: 31421


Sorption of trivalent actinides (Cm, Am) and their rare earth analogues (Lu, Y, Eu, Nd, La) onto orthoclase: Batch experiments, Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) and Surface Complexation Modeling (SCM)

Brinkmann, H.; Neumann, J.; Britz, S.; Brendler, V.; Stumpf, T.; Schmidt, M.

Sorption is one of the main processes, which determine the retention of radionuclides (RN) in a repository for nuclear waste. In a multi-barrier system, the host rock poses the ultimate barrier retarding the release of RN into the environment. Feldspars (e.g. orthoclase) are one of the main constituents of crystalline rock (e.g. granite), which is considered one potential host rock type in many countries (e.g. Finland, Sweden, Germany). In this study, the sorption of trivalent actinides (Cm, Am) and their rare earth analogues (Lu, Y, Eu, Nd, La) onto orthoclase (K feldspar) is investigated. For reliable predictions concerning the migration of RN, a process understanding on the molecular level of such processes is necessary. To achieve this, batch sorption experiments are combined with TRLFS and SCM.
Batch experiments were performed covering a broad range of experimental conditions (pH 4-11, oxic and anoxic conditions, [M3+] = 10-6-10-4 M, 3-50 g/L orthoclase (grain size: < 21 and 63-200 µm; SSA: 4.2 and 0.2 m2g-1)). Weak retardation below pH 5, followed by a strong increase between pH 5 and 7 and complete removal from solution at pH ≥ 8 was observed for all investigated metals. Cm- and Eu-TRLFS-measurements suggested the formation of an outer-sphere surface complex at lower (pH<5) and two different inner-sphere surface complexes at higher pH values (pH > 5 and pH > 7.5, respectively). Surface precipitation was observed for higher metal concentrations (10-4 M). As the investigated metals revealed a similar behavior over a broad range of conditions, a generic approach was used for the SCM to describe the system as a whole. Experimental data of different series with different metals were simultaneously fitted by coupling PHREEQC with UCODE using the same underlying speciation model. Resulting generic stability constants for the involved surface complexes will be presented.
The identification of comparable processes and their unified description with one suitable model is important to map the complexity of natural systems onto simplified geochemical models. This step is crucial for large-scale reactive transport calculations needed for a reliable safety assessment of potential repository sites, as they require enormous computing efforts.

Keywords: Actinides; Sorption; Orthoclase; Spectroscopy; Modeling

Permalink: https://www.hzdr.de/publications/Publ-31420
Publ.-Id: 31420


Analysis of technetium immobilization and its molecular retention mechanisms by Fe(II)-Al(III)-Cl layered double hydroxide.

Mayordomo, N.; Rodriguez Hernandez, D. M.; Roßberg, A.; Foerstendorf, H.; Heim, K.; Brendler, V.; Müller, K.

Layered double hydroxides (LDH) play a decisive role in regulating the mobility of contaminants in natural and engineered environments. In this work, the retention of an Fe(II)-Al(III)-Cl LDH towards pertechnetate (TcO₄⁻ ), which is the most stable and highly mobile form of Tc under aerobic conditions, is investigated comprehensively as a function of pH, Tc concentration and ionic strength. For a technetium initial concentration of 5 µM, its retention yield is higher than 80% from pH 3.5 to pH 10.5, especially at NaCl concentration below 0.1 M. A combination of vibrational and X-ray absorption spectroscopy provides structural information on the retention mechanism on a molecular scale. X-ray absorption near edge spectroscopy (XANES) confirms that most of the Tc uptake is due to Tc(VII) reduction to Tc(IV). The analysis of the extended X-ray absorption fine structure (EXAFS) reveals two different mechanisms of Tc(IV) interaction with hematite (sub-product of the LDH oxidation and confirmed by Raman microscopy). At low pH, sorption of Tc(IV) dimers via inner-sphere monodentate complexation on hematite dominates. In contrast, under alkaline conditions, Tc(IV) is incorporated into the structure of hematite. Additionally, in situ attenuated total reflection Fourier-transform infrared spectroscopy (ATR FT-IR) evidences a small contribution of the total uptake corresponding to Tc(VII) anion exchange.
The derived molecular structures increase confidence in predictive modelling of Tc migration patterns in subsurface environments, e.g. in the vicinity of a radioactive waste repository and treatment sites or in polluted areas due to other anthropogenic Tc sources.

Keywords: LDH; hematite; reduction; retardation; XAS; ATR FT-IR

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  • Secondary publication expected from 15.03.2022

Permalink: https://www.hzdr.de/publications/Publ-31419
Publ.-Id: 31419


Mapping the stray fields of a micromagnet using spin centers in SiC

Bejarano, M.; Trindade Goncalves, F. J.; Hollenbach, M.; Hache, T.; Hula, T.; Berencen, Y.; Faßbender, J.; Helm, M.; Astakhov, G.; Schultheiß, H.

We report the use of optically addressable spin qubits in SiC to probe the static magnetic stray fields generated by a ferromagnetic microstructure lithographically patterned on the surface of a SiC crystal. The stray fields cause shifts in the resonance frequency of the spin centers. The spin resonance is driven by a micrometer-sized microwave antenna patterned adjacent to the magnetic element. The patterning of the antenna is done to ensure that the driving microwave fields are delivered locally and more efficiently compared to conventional, millimeter-sized circuits. A clear difference in the resonance frequency of the spin centers in SiC is observed at various distances to the magnetic element, for two different magnetic states. Our results offer a wafer-scale platform to develop hybrid magnon-quantum applications by deploying local microwave fields and the stray field landscape at the micrometer lengthscale.

Keywords: Quantum sensing; Magnonics; Spin qubits in SiC; Microwave circuits; electron beam lithography

Related publications

  • Poster (Online presentation)
    Magnetism and Magnetic Materials Conference 2020 (MMM2020), 02.-06.11.2020, Online, United States

Permalink: https://www.hzdr.de/publications/Publ-31418
Publ.-Id: 31418


Studies of Big Data Processing at Linear Accelerator Sources Using Machine Learning

Bawatna, M.; Green, B. W.

In linear accelerator sources such as the electron beam of the super-conducting linear accelerator at the radiation source Electron Linear accelerator for beams with high Brilliance and low Emittance (ELBE), different kinds of secondary radiation can be produced for various research purposes from materials science up to medicine. A variety of different beam detectors generate a huge amount of data, which take a great deal of computing power to capture and analyse. In this contribution, we will discuss the possibilities of using Machine Learning method to solve the big data challenges. Moreover, we will present a technique that employ the machine learning strategy for the diagnostics of high-field terahertz pulses generated at the ELBE accelerator with extremely flexible parameters such as repetition rate, pulse form and polarization.

Keywords: Cloud computing; Machine learning; Big data; Deep neural networks

  • Contribution to proceedings
    Computer Science On-line Conference, CSOC 2020: Artificial Intelligence and Bioinspired Computational Methods, 20.-24.05.2020, Berlin, Germany
    Advances in Intelligent Systems and Computing, Volume 1225 AISC, 2020, Pages 450-460: Springer, 978-3-030-51970-4
    DOI: 10.1007/978-3-030-51971-1_37

Permalink: https://www.hzdr.de/publications/Publ-31417
Publ.-Id: 31417


Real-Time Data Compression System for Data-Intensive Scientific Applications Using FPGA Architecture

Bawatna, M.; Knodel, O.; Spallek, R.

Particle accelerators are continually advancing and offer insights into the world of molecules, atoms, and particles on the ever shorter length and timescales. A variety of detectors, which are connected to different front-end electronics are installed in various kinds of Data Acquisition (DAQ) systems, to collect a huge amount of raw data. This goes along with a rapid and highly accurate transformation of analog quantities into discrete values for electronic storage and processing with exponentially increasing amounts of data. Therefore, data reduction or compression is an important feature for the DAQ systems to reduce the size of the data transmission path between the detectors and the computing units or storage devices. The flexibility of the Field Programmable Gate Arrays (FPGAs) allows the implementation of real-time data compression algorithms inside these DAQ systems. In this contribution, we will present our developed real-time data compression technique for continuous data recorded by high-speed imaging detectors at the terahertz source facility at ELBE particle accelerator. The hardware implementation of the algorithm proved its real-time suitability by compressing one hundred thousand consecutive input signals without introducing dead time.

Keywords: Lossless data compression; FPGA; Real-time; Data-intensive

  • Contribution to proceedings
    Computer Science On-line Conference, Applied Informatics and Cybernetics in Intelligent Systems, 20.-24.05.2020, Berlin, Germany
    CSOC 2020: Applied Informatics and Cybernetics in Intelligent Systems: Springer, 978-3-030-51974-2, 304-313
    DOI: 10.1007/978-3-030-51974-2_29

Permalink: https://www.hzdr.de/publications/Publ-31416
Publ.-Id: 31416


Possibilities and Challenges for Reconfigurable Hardware and Cloud Architectures in Data-Intensive Scientific Applications

Bawatna, M.; Knodel, O.; Spallek, R.

Advances in process technology and new design tools have expanded the scope of embedded systems. This ranges from the implementation in several chips on board to module groups in integrated circuits. Reconfigurable hardware and, in particular, FPGAs are used more frequently in scientific applications, where they enable the development of complex and intelligent field devices. Furthermore, this increased the use of a platform-based design approach that facilitates the development and verification of complex FPGAs through the full reuse of hardware and software modules. Especially in the area of heterogeneous accelerators, which can improve the exploitation of modern data centers. Another critical aspect in the evolution of embedded systems is the trend towards networking embedded nodes using specialized computational and networking technologies called cloud computing. In this paper, we will present our data-intensive experiments at the terahertz source at ELBE accelerator-based light source, and its integration into a reproducible data management workflow at the heterogeneous cluster in our data centre

Keywords: Reconfigurable computing; cloud; data-intensive scientific applications

  • Contribution to proceedings
    Seventh International Conference on Software Defined Systems (SDS), 20.-23.04.2020, Paris, France
    Proceedings of Seventh International Conference on Software Defined Systems: IEEE, 978-1-7281-7218-7
    DOI: 10.1109/SDS49854.2020.9143904

Permalink: https://www.hzdr.de/publications/Publ-31415
Publ.-Id: 31415


In silico finding of key interaction mediated α3β4 and α7 nicotinic acetylcholine receptor ligand selectivity of quinuclidine-triazole chemotype

Arunrungvichian, K.; Chongruchiroj, S.; Sarasamkan, J.; Schüürmann, G.; Brust, P.; Vajragupta, O.

The selective binding of six (S)-quinuclidine-triazole and their (R)-enantiomers to nicotinic acetylcholine receptor (nAChR) subtypes α3β4 and α7, respectively, was analyzed by in silico docking to provide the insight into the molecular basis for the observed stereospecific subtype discrimination. Homology modeling follwed by molecular docking and molecular dynamics (MD) simulations revealed that unique amino acid residues in the complementary subunits of the nAChR subtypes are involved in subtype-specific selectivity profiles. In the complementary β4-subunit of the α3β4 nAChR binding pocket, non-conserved AspB173 through a salt bridge was found to be the key determinant for the α3β4 selectivity of the quinuclidine-triazole chemotype, explaining the 47-327-fold affinity of the (S)-enantiomers as compared to their (R)-enantiomer counterparts. Regarding the α7 nAChR subtype, the aminio acids promoting a however significantly lower preference for the (R)-enantiomers were the conserved TyrA93, TrpA149 and TrpB55 residues. The non-conserved amino acid residue in the complementary subunit of nAChR subtypes appeard to play a significant role for the nAChR subtype-selective binding, particularly at the heteropentameric subtype, wheras the conserved amino acid residues in both principal and complementary subunits are essential for ligand potency and efficacy.

Keywords: stereoselectivity; anti-1,2,3-triazole; α7 nAChR; α3β4 nAChR; quinuclidine

Permalink: https://www.hzdr.de/publications/Publ-31414
Publ.-Id: 31414


Effects of Acquisition Parameter Modifications and Field Strength on the Reproducibility of Brain Perfusion Measurements Using Arterial Spin-Labeling

Baas, K.; Petr, J.; Kuijer, J.; Nederveen, A.; Mutsaerts, H.-J.; van de Ven, K.

Background and Purpose: To encourage clinical adoption of ASL-based perfusion MRI, we investigated the reproducibility of CBF measurements and the effects of protocol variations at clinical field strengths in adult participants with a broad age range. This study increases the knowledge on the tolerance to variations in scan parameters compared to the recommended ASL implementation.
Materials and Methods: Thirty-four volunteers (mean age 57.8±17.0y, range 22-80y) underwent two separate scan sessions on clinical field strengths (1.5T and 3T, single vendor), using a fifteen channel head coil. Both sessions contained repeated 3D and 2D pseudo-continuous ASL (pCASL) vendor-recommended protocols, followed by three 3D pCASL scans; two with post-labeling delays (PLD) of 1600ms and 2000ms and one with increased spatial resolution. All pCASL scans were acquired with a single PLD. The effect of scan parameter variations on CBF and spatial coefficient of variation (CoV) was examined, as well as the reproducibility of the recommended protocols, both intrasession (two identical protocols scanned 5 min apart) and intersession (first 2D and 3D protocol of the first and second session).
Results: Intrasession CBF reproducibility was similar across image readouts and field strengths ( coefficient of variation (CV) ranging from 4.0% to 6.9%) and did not show a statistically significant correlation with age. Intersession wsCV ranged from 6.8% to 14.8%, scanning twice at 3T versus mixed 3T-1.5T respectively. At 3T, there is sufficient SNR to increase the spatial resolution of the 3D protocol, causing less mixing of gray matter (GM) and white matter signal, therewith decreasing the bias in GM CBF between 2D and 3D protocols (ΔCBF = 2.49 (p<0.001) ml/100g/min. Changes in PLD resulted in a modest bias (ΔCBF ranging from -3.78 (p<0.001) to 2.83 (p<0.001) ml/100g/min).
Conclusion: Our data shows that ASL imaging is reproducible at both field strengths and does not show a statistically significant correlation with age. Furthermore, 3T offers more tolerance for scan parameter variations and allows for protocol optimizations such that 3D and 2D protocols can be compared.

Permalink: https://www.hzdr.de/publications/Publ-31413
Publ.-Id: 31413


GliMR: Cross-border collaborations to promote advanced MRI biomarkers in glioma

Clement, P.; Borovecki, F.; Emblem, K. E.; Figueiredo, P.; Hirschler, L.; Jancalek, R.; Keil, V. C.; Maumet, C.; Ozsunar, Y.; Pernet, C.; Petr, J.; Pinto, J.; Smits, M.; Warnert, E. A. H.

Every year, 50.000 new glioma cases occur in Europe. The optimal treatment strategy is highly personalised, depending on tumour type, grade, spatial localization, and tissue infiltration level. In research settings, advanced magnetic resonance imaging (MRI) has shown great promise to inform personalised treatment decisions. However, the use of advanced MRI in clinical practice is still scarce, due to a scattered imaging research landscape, a limited representation of MRI in established consortia for glioma, and the lack of tools and expertise for advanced MRI, available in standard clinical settings. These shortcomings delay the translation of scientific breakthroughs into novel treatment strategy developments, and limit the progression of personalised medicine.
Therefore, in this work, the network Glioma MR Imaging 2.0 (GliMR) is presented. GliMR aims to build a pan-European and multidisciplinary network of experts and progress beyond the state-of-the-art in glioma imaging, by accelerating the use of advanced MRI in glioma. The Action ‘Glioma MR Imaging 2.0 (GliMR)’ was granted funding by the European Cooperation in Science and Technology (COST) in June 2019.
GliMR’s first grant period ran from September 2019 to April 2020, during which several networking meetings were held and projects were initiated by the different working groups, such as reviewing of the current knowledge on advanced MRI, developing a GDPR-compliant consent form, initiating relationships with European scientific organisations, and setting up several dissemination channels, including the website www.glimr.eu. The action is funded until September 2023 and is accepting new members during its entire duration.

Permalink: https://www.hzdr.de/publications/Publ-31412
Publ.-Id: 31412


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