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41396 Publications

Software for Bubble identification from images with machine learning methods

Heßenkemper, H.; Starke, S.; Atassi, Y.; Ziegenhein, T.; Lucas, D.

This package contains the software and the trained models described in the publication "Bubble identification from images with machine learning methods". Please refer to the README.md for installation instructions and to the Prediction_demo.ipynb for usage demonstration.

Update

The Prediction_demo.ipynb includes now an example how to prepare the predictions for the tracking algorithm of "Fate of bubble clusters rising in a quiescent liquid". The tracking code can be found here.

Update

Now only tensorflow models are used, so no MXNet installation required.

Keywords: Bubbly flows; Deep Learning; Computer Vision; CNN; Semantic segmentation

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Permalink: https://www.hzdr.de/publications/Publ-34349
Publ.-Id: 34349


Superradiance of Spin Defects in Silicon Carbide for Maser Applications

Gottscholl, A.; Wagenhöfer, M.; Klimmer, M.; Scherbel, S.; Kasper, C.; Baianov, V.; Astakhov, G.; Dyakonov, V.; Sperlich, A.

Masers as telecommunication amplifiers have been known for decades, yet their application is strongly limited due to extreme operating conditions requiring vacuum techniques and cryogenic temperatures. Recently, a new generation of masers has been invented based on optically pumped spin states in pentacene and diamond. In this study, we pave the way for masers based on spin S = 3/2 silicon vacancy (VSi) defects in silicon carbide (SiC) to overcome the microwave generation threshold and discuss the advantages of this highly developed spin hosting material. To achieve population inversion, we optically pump the VSi into their mS = ±1/2 spin sub-states and additionally tune the Zeeman energy splitting by applying an external magnetic field. In this way, the prerequisites for stimulated emission by means of resonant microwaves in the 10 GHz range are fulfilled. On the way to realising a maser, we were able to systematically solve a series of subtasks that improved the underlying relevant physical parameters of the SiC samples. Among others, we investigated the pump efficiency as a function of the optical excitation wavelength and the angle between the magnetic field and the defect symmetry axis in order to boost the population inversion factor, a key figure of merit for the targeted microwave oscillator. Furthermore, we developed a high-Q sapphire microwave resonator (Q 10^4 – 10^5) with which we find indications of superradiant stimulated microwave emission. In summary, SiC with optimized spin defect density and thus spin relaxation rates is well on its way of becoming a suitable maser gain material with wide-ranging applications.

Keywords: Quantum technology; Stimulated emission; Population inversion; Spin centers; Silicon carbide

Permalink: https://www.hzdr.de/publications/Publ-34347
Publ.-Id: 34347


Data publication: Laboratory investigation of tomography-controlled continuous steel casting

Glavinic, I.; Muttakin, I.; Abouelazayem, S.; Blishchik, A.; Stefani, F.; Eckert, S.; Soleimani, M.; Saidani, I.; Hlava, J.; Kenjeres, S.; Wondrak, T.

Dataset containing the raw and post-processed data used for in the associated publication. Scripts for evaluating the data are attached.

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Permalink: https://www.hzdr.de/publications/Publ-34346
Publ.-Id: 34346


Positrons in Material Sciences: Intense Beams for Defect Studies and Applications

Wagner, A.; Butterling, M.; Elsherif, A. G. A.; Hirschmann, E.; Liedke, M. O.; Krause-Rehberg, R.

The Helmholtz-Center Dresden-Rossendorf operates several user beamlines for materials research using positron annihilation energy and lifetime spectroscopy. The superconducting electron LINAC ELBE [2] drives a hard X-ray source, which generates positrons through pair production. The high-intensity Mono-energetic Positron Source MePS utilizes moderated positrons with adjustable kinetic energies ranging from 500 eV to 16 keV for depth profiling of defects in thin films. A magnetic beam transport system consisting of a beam chopper, a beam buncher, and a post-accelerator guides the positron beam towards the sample under investigation. Fully digital data processing of positron annihilation lifetime events generates high-quality spectra with timing resolutions down to about 210 ps and count rates in excess of 120 kcps.
The MePS facility is currently complemented by an additional beamline named Apparatus for In-situ Defect Analysis, AIDA-II, where in-situ defect studies are to be performed in a wide temperature range during thin film growth and under ion irradiation. A complimentary but functionally similar setup, AIDA-I, is operated at a 22Na-based mono-energetic continuous positron beam used for in-situ (coincidence) Doppler-broadening positron annihilation spectroscopy experiments. Recent developments figuring the formation and time dynamics of hydrogen-induced vacancies in nickel and niobium and the role of defects in magneto-ionics and ZnO semiconductor films will be presented.
The MePS facility has partly been funded by the Federal Ministry of Education and Research (BMBF) with the grant PosiAnalyse (05K2013). The initial AIDA system was funded by the Impulse- und Networking fund of the Helmholtz-Association (FKZ VH-VI-442 Memriox). The AIDA facility was funded through the Helmholtz Energy Materials Characterization Platform.

Keywords: positron annihilation spectroscopy; positron annihilation lifetime spectroscopy; MePS

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  • Invited lecture (Conferences) (Online presentation)
    Nuclear Probes for Materials, Medicine and Industry (NPMMI-2022), 04.-05.03.2022, Mumbai, India

Permalink: https://www.hzdr.de/publications/Publ-34345
Publ.-Id: 34345


Salting-Out of DNA Origami Nanostructures by Ammonium Sulfate

Hanke, M.; Hansen, N.; Ruiping, C.; Grundmeier, G.; Fahmy, K.; Keller, A.

DNA origami technology enables the folding of DNA strands into complex nanoscale shapes whose properties and interactions with molecular species often deviate significantly from that of genomic DNA. Here, we investigate the salting-out of different DNA origami shapes by the kosmotropic salt ammonium sulfate that is routinely employed in protein precipitation. We find that centrifugation in the presence of 3 M ammonium sulfate results in notable precipitation of DNA origami nanostructures but not of double-stranded genomic DNA. The precipitated DNA origami nanostructures can be resuspended in ammonium sulfate-free buffer without apparent formation of aggregates or loss of structural integrity. Even though quasi-1D six-helix bundle DNA origami are slightly less susceptible toward salting-out than more compact DNA origami triangles and 24-helix bundles, precipitation and recovery yields appear to be mostly independent of DNA origami shape and superstructure. Exploiting the specificity of ammonium sulfate salting-out for DNA origami nanostructures, we further apply this method to separate DNA origami triangles from genomic DNA fragments in a complex mixture. Our results thus demonstrate the possibility of concentrating and purifying DNA origami nanostructures by ammonium sulfate-induced salting-out.

Keywords: DNA origami; DNA nanotechnology; ammonium sulfate; precipitation; salting-out

Permalink: https://www.hzdr.de/publications/Publ-34343
Publ.-Id: 34343


Data for case studies about estimating measurement uncertainties

Pospiech, S.

These data are supplementary material for the publication "Uncertainty Estimation for Measurement Data - A Practical Guide for Earth Scientists" in the journal Geostandards and Geoanalytical Research.

Data have uncertainties. Including a good estimate of the uncertainties for data analysis might significantly change the data interpretation. Therefore, high data quality is characterized by good accuracy of measurement results, but equally important by a good estimation of data uncertainty, which includes all relevant sources of dispersion of a measurement procedure. These data are example data sets for two case studies using uncertainty models based on replicated measurements. The case studies demonstrate how the models can be parameterized by using measurement data. The case studies are accompanied by code examples for the statistical programming language R.

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Permalink: https://www.hzdr.de/publications/Publ-34342
Publ.-Id: 34342


Stacking polymorphism in PtSe2 drastically affects its electromechanical properties

Kempt, R.; Lukas, S.; Hartwig, O.; Prechtl, M.; Kuc, A. B.; Brumme, T.; Li, S.; Neumaier, D.; Lemme, M. C.; Duesberg, G. S.; Heine, T.

PtSe2 is one of the most promising materials for the next generation of piezoresistive sensors. However, the large-scale synthesis of homogeneous thin films with reproducible electromechanical properties is challenging due to polycrystallinity. We show that stacking phases other than the 1T phase become thermodynamically available at elevated temperatures that are common during synthesis. We show that these phases can make up a significant fraction in a polycrystalline thin film and discuss methods to characterize them, including their Seebeck coefficients. Lastly, we estimate their gauge factors, which vary strongly and heavily impact the performance of a nanoelectromechanical device.

Permalink: https://www.hzdr.de/publications/Publ-34341
Publ.-Id: 34341


Stochastic Modelling of Mineral Exploration Targets

Talebi, H.; Mueller, U.; Peeters, L. J. M.; Otto, A.; de Caritat, P.; Tolosana Delgado, R.; van den Boogaart, K. G.

Mineral deposits are metal enrichment anomalies, occurring as local manifestations of the interplay between various geological processes that operate at a wide range of temporal and spatial scales. Mineral prospectivity maps are generated by integrating several proxy maps that represent critical geological processes in a mineral system conceptual model. The derivation of mineral prospectivity maps is subject to several types of uncertainty, including systematic (inadequate knowledge of mineralisation processes), stochastic (incomplete geoscience data), and model uncertainty (multiple choices for predictive models and their parameters). Traditional approaches to mineral prospectivity mapping often fail to fully appreciate different sources of uncertainty and spatiotemporal interdependencies between proxy maps associated with the mineral system components. Therefore, these traditional approaches are biased and understate the overall uncertainty. For instance, spatial proxies are mapped using univariate deterministic approaches that ignore stochastic uncertainty and spatial dependencies (i.e., auto- and cross-correlations). This study presents a multivariate stochastic model for prediction and uncertainty quantification of mineral exploration targets by combining multivariate geostatistical simulations and spatial machine learning algorithms. The spatial machine learning algorithm used in the stochastic model is a spatially aware random forests algorithm based on higher-order spatial statistics. It is demonstrated that the proposed approach can detect intrinsic heterogeneity, spatial interdependencies, and complex spatial patterns in proxy maps that are related to the mineralisation type of interest. The approach is illustrated using a synthetic case study with multiple geochemical, geophysical, and lithological attributes.

Keywords: Geostatistical learning; Machine learning; Mineral prospectivity mapping; Spatial data; Spatial predictive model; Uncertainty quantification

Permalink: https://www.hzdr.de/publications/Publ-34340
Publ.-Id: 34340


Reaction cross sections 54Fe(n,γ)55Fe and 35Cl(n,γ)36Cl at keV neutron energies investigated by Accelerator Mass Spectrometry

Slavkovska, Z.; Wallner, A.; Reifarth, R.; Bott, L.; Brückner, B.; Erbacher, P.; Fifield, K.; Froehlich, M.; Göbel, K.; Al-Khasawneh, K.; Koll, D.; Lachner, J.; Merchel, S.; Pavetich, S.; Reich, M.; Rugel, G.; Thomas, B.; Tims, S. G.; Volknandt, M.; Weigand, M.

Typical neutron energies for the astrophysical s-process follow the Maxwell-Boltzmann distribution in the keV energy range. Neutron capture cross sections highly relevant for modelling the s-process can be experimentally determined by using the Time-of-Flight (ToF) method [1] or by the activation technique. If the reaction product is a long-lived radionuclide (t1/2 ~ yr -100 Myr), the cross section can be determined by activation with a quasi-stellar neutron distribution (typically kT = 25 keV) and a subsequent accelerator mass spectrometry (AMS) measurement of the reaction product [2]. Comparison of a number of such neutron capture cross sections shows a systematic bias, i.e. AMS data being lower than the ToF data [3, 4].

To investigate this discrepancy, we repeated experiments for two reactions that allow for highly precise AMS data: Maxwellian-averaged cross sections for the reactions 54Fe(n,γ)55Fe and 35Cl(n,γ)36Cl were investigated with dedicated activations at the Frankfurt Neutron Source (FRANZ) in Germany [5] and AMS measurements at two independent facilities. Analogously to previous activations, a quasi-stellar neutron spectrum of kT = 25 keV was produced via the 7Li(p,n) reaction, but at a different neutron-producing facility. Furthermore, to complement existing ToF and AMS data, an additional neutron activation of 54Fe and 35Cl at a proton energy of 2 MeV was performed, yielding data in the not-yet explored kT = 90 keV region.

The irradiated metallic Fe foil and NaCl pellet (both of natural isotopic composition) were chemically processed and converted to AMS targets (Fe2O3 and AgCl) together with non-irradiated blanks. The subsequent AMS measurements of both radionuclides, 36Cl and 55Fe, were performed at two complementary AMS facilities, the Heavy Ion Accelerator Facility (HIAF) at the Australian National University [6] and at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Germany [7]. AMS allows a direct measurement of the 55Fe/54Fe and 36Cl/35Cl conversion ratios that result from the irradiation. The cross section is then deduced from the isotope ratio and the neutron fluence, which is determined using Au monitor foils.

The new experiment was designed to produce highly accurate data and, owing to the two independent AMS measurements, it minimizes unrecognized sources of uncertainties in the AMS technique. The new preliminary data obtained in this work seem to confirm the previous AMS results. Consequently, the systematic discrepancy between AMS and ToF data remains unresolved.

[1] Guber, K.H., et al., Phys. Rev. C 65, 058801 (2002).
[2] Györky, Gy., et al., Eur. Phys. J. A 55, 41 (2019).
[3] Capote, R., et al., Nucl. Data Sheets 163 (2020): 191.
[4] Slavkovská, Z., et al., EPJ Web Conf. Vol. 232, p.02005, EDP Sciences, 2020.
[5] Reifarth, R., et al., Publ. Astron. Soc. Aust. 26.3 (2009): 255.
[6] Fifield, L.K., et al. Nucl. Instr. Meth. B: 268 (2010): 858.
[7] Rugel, G., et al., Nucl. Instr. and Meth. in Phys. Res. B 370 (2016) 94.

Keywords: AMS

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Permalink: https://www.hzdr.de/publications/Publ-34339
Publ.-Id: 34339


Data publication: First-principles derivation and properties of density-functional average-atom models

Callow, T. J.; Hansen, S. B.; Kraisler, E.; Cangi, A.

Data for the pre-print "First-principles derivation and properties of density-functional average-atom models", https://arxiv.org/abs/2103.09928.

Each data folder is named according to the corresponding figure in the paper. For any questions, please contact the authors.

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Permalink: https://www.hzdr.de/publications/Publ-34337
Publ.-Id: 34337


Metadatamanagement - How to make your data FAIR

Schaller, T.; Steinmeier, L.; Rau, F.

The necessity of exhaustive documentation of research data arises from an increasing depth of scientific understanding and investigations of unknown phenomena with research teams of different areas and fields. Different methods and definitions and insufficient documentation of field work, experimental and numerical examinations lead to information loss, especially over time. To counteract this problem the scientific community aims to make research data Findable, Accessible, Interoperable and Reusable (FAIR). Unfortunately infrastructure, tools, personnel and acceptability for these additional steps are often missing and result in the mentioned paucity of information and data. Within the Helmholtz Association the Helmholtz Metadata Collaboration (HMC) has taken on the task of building this infrastructure to support high quality data documentation and publication throughout the entire lifecycle of research data and to raise the awareness for necessary structural changes in the wider scientific community.
One goal of HMC is the mapping of existing data management structures and demands in the different research fields of the Helmholtz Community. These fields are especially addressed with Hubs, being the connection between HMC and the specific needs of the research fields. Based on the collected information HMC will implement tools to assist scientists, data managers and IT administrators in making their research data FAIR. Furthermore members of HMC will connect with other (meta-)data initiatives to work towards necessary structural changes in the world of scientific research by e.g. defining standards.
In this poster we will discuss the FAIR principles and introduce the Helmholtz Metadata Collaboration and their tasks. Also, we will show concrete examples from the geoscientific part of Hub Energy. The Hub in which we are active.

Keywords: FAIR; Metadata; Helmholtz Metadata Collaboration; Deutsche Geophysikalische Gesellschaft

  • Poster (Online presentation)
    Jahrestagung der Deutschen Geophysikalischen Gesellschaft, 07.-10.03.2022, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34336
Publ.-Id: 34336


Complexation studies of Eu(III) with NTA at high ionic strengths

Sieber, C.; Kretzschmar, J.; Schmeide, K.; Stumpf, T.

Radionuclide speciation inside long-term radioactive waste repositories needs to be understood in order to ensure effective containment of the waste. Organic ligands originating from the degradation of organic components inside such a repository can possibly affect the mobility of radionuclides in solution. The present study focuses on nitrilotriacetic acid, NTA, as a model molecule and europium, Eu(III), as a nonradioactive analog with outstanding luminescence and magnetic properties.
The complexation of NTA with Eu(III) (in ratios of 1:2 and 1:1 Eu:NTA) as a function of pH was studied using nuclear magnetic resonance (NMR) spectroscopy in 1 M NaCl D2O solution. The 1H and 13C NMR spectra of the NTA solutions with Eu(III) show clearly distinguishable signals for the free NTA and two Eu-NTA complexes, which is indicative of a 1:1 and a 1:2 Eu-NTA complex. The interaction of Eu(III) with NTA is relatively strong and favors the 1:2 Eu-NTA complex even in solution containing 1:1 Eu-NTA ratio, unless in very acidic solutions.
As a repository relevant cationic groundwater components, the influence of Ca(II) and Al(III) on Eu(III) complexation is studied in detail.
A combination of NMR spectroscopy and time-resolved laser-induced fluorescence spectroscopy yields qualitative and quantitative information on the coordination environment from the ligand’s and the metal ion’s perspective, respectively. In subsequent studies focusing on ternary systems comprising repository relevant solid phases, radionuclides and organic ligands this will allow the identification of radionuclide speciation in solution and their sorption to solid phases.
Acknowledgement: The German Federal Ministry for Economic Affairs and Energy (BMWi) is thanked for financial support within the GRaZ II project, no. 02E11860B.

Keywords: europium; nitrilotriacetic acid; nuclear magnetic resonance

  • Poster
    19th Radiochemical Conference (RadChem), 15.-20.05.2022, Mariánské Lázně, Tschechische Republik

Permalink: https://www.hzdr.de/publications/Publ-34333
Publ.-Id: 34333


What is the speed limit of martensitic transformations?

Schwabe, S.; Lünser, K.; Schmidt, D.; Nielsch, K.; Gaal, P.; Fähler, S.

Structural martensitic transformations enable various applications, which range from high stroke actuation and sensing to energy efficient magnetocaloric refrigeration and thermomagnetic energy harvesting. All these emerging applications benefit from a fast transformation, but up to now the speed limit of martensitic transformations has not been explored. Here, we demonstrate that a martensite to austenite transformation can be completed in under ten nanoseconds. We heat an epitaxial Ni-Mn-Ga film with a laser pulse and use synchrotron diffraction to probe the influence of initial sample temperature and overheating on transformation rate and ratio. We demonstrate that an increase of thermal energy drives this transformation faster. Though the observed speed limit of 2.5 x 10^27 (Js)^-1 per unit cell leaves plenty of room for a further acceleration of applications, our analysis reveals that the practical limit will be the energy required for switching. Our experiments unveil that martensitic transformations obey similar speed limits as in microelectronics, which are expressed by the Margolus–Levitin theorem.

Keywords: Martensitic Transformations; Time dependency; Syncrotron Diffraction

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Permalink: https://www.hzdr.de/publications/Publ-34330
Publ.-Id: 34330


One-step synthesis of the hydrophobic conical Co-Fe structures – the comparison of their active areas and electrocatalytic properties

Skibińska, K.; Kornaus, K.; Yang, X.; Kutyła, D.; Wojnicki, M.; Żabiński, P.

Enhancement of the surface of the catalyst is desirable in the interest of mass transport maximizing. However, without a well-defined method of determination of its active surface, catalyst deposited with different conditions cannot be accurately compared. In this work, Co-Fe alloy cones were synthesized from the electrolyte containing ammonium chloride as a crystal modifier. It controls the direction of the deposit growth, and consequently, develops the active surface area. Moreover, the influence of the direction of the applied magnetic field on the ferromagnetic Co-Fe alloy was investigated. It affected noticeably the morphology and composition of layers and therefore, the catalytic activity of the samples in the Hydrogen Evolution Reaction (HER). Linear Sweep Voltammetry (LSV) measurements were used to test the catalytic activity in 1 M NaOH electrolyte. The expected development of the real active surface area was determined using two different methods: Brunauer-Emmett-Teller (BET) and Helmholtz Double-Layer Capacitance (DLC). Results show that no specific value of the sample surface multiplication can be found based on these methods. All conical structures were hydrophobic.

Keywords: Co-Fe cones; crystal modifier; magnetic field; hydrogen evolution reaction; active surface area

Permalink: https://www.hzdr.de/publications/Publ-34329
Publ.-Id: 34329


From License Consultation to Software Spotlights

Konrad, U.; Meeßen, C.; Hammitzsch, M.; Huste, T.; Jandt, U.

Presentation to the session: "Reproducible Science - Research Data and Research Software in Interaction" - "Reproduzierbare Wissenschaft – Forschungsdaten und Research Software im Zusammenspiel".
Reproducibility is a prerequisite for open science, but results must also be reusable in accordance with FAIR principles, and this applies in particular to research software! But how can research software, even if it is developed in open source projects, be made known to a broad user community? And how can better visibility and recognition be achieved for the developers of successful software solutions?
A new approach is currently being implemented in the Helmholtz Association. First of all, the necessary database is being created by building up a software directory as automatically as possible on the basis of standardised metadata. By evaluating these entries, successful solutions will be marked and prepared for a broad community. Finally, the best software products will be published in a "Software Flagship Store" and offered to a broad community.

Keywords: Research Software Engineering; Software License; HIFIS; Cloud Services; Software Development; Software Entwicklung; Forschungssoftware; Lizenzen; Helmholtz Federated IT Services

  • Open Access Logo Lecture (Conference) (Online presentation)
    RDA Deutschland Tagung 2022, 21.-25.02.2022, virtuell, Deutschland
    DOI: 10.5281/zenodo.6248895

Permalink: https://www.hzdr.de/publications/Publ-34327
Publ.-Id: 34327


Estimating individual uncertainties – making use of all your replicate analysis

Pospiech, S.; van den Boogaart, K. G.; Renno, A.; Möckel, R.; Fahlbusch, W.

High data quality is characterized by good accuracy of measurement results but equally important by a good estimation of data uncertainty (JCGM 100:2008). Using a good estimate of the uncertainty for data analysis might significantly change the data interpretation: Ignoring or underestimating uncertainties projects too high confidence into the measurand values, while overestimation of uncertainties could blur relevant information in the data. The information carried by the data can be exploited best, if the measurement result would be reported as original (not rounded) number accompanied by the values of the measurement uncertainty (Eggen, et al. 2019). This requires methods to calculate or estimate uncertainties for each analytical datum. Including uncertainties as separate values into the data interpretation is especially important if the data set has individual uncertainties, i.e., every data point has a its ‘own’ uncertainty.

Earth scientists need a method of estimating individual uncertainties based on a few multiple measurements. This method should consider the sample materials' characteristics for which the uncertainty should be assessed, e.g. range of potential measurand values, variability in sample material and heterogeneities. It should also allow to model several sources of uncertainties to account for the multi-step measurement procedure. And last but not least, the method should remain affordable and practical, e.g. the method should also be applicable if samples are send to external laboratories.

In this contribution, we present a method to quantify individual uncertainties with respect to the analyte level (Ellison and Williams 2012)[Annex E.5], including uncertainty model component which allows to model Poisson type error, e.g. due to heterogeneities which are typical for samples in the geosciences. Case studies and examples in data science languages are presented to facilitate the implementation.

Keywords: uncertainty; uncertainty estimation; analytics; measurement data; R-package

  • Open Access Logo Lecture (Conference)
    Geoanalysis 2022, 06.-12.08.2022, Freiberg, Germany

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Permalink: https://www.hzdr.de/publications/Publ-34323
Publ.-Id: 34323


A comprehensive study on the interaction of Eu(III) and U(VI) with plant cells (Daucus carota) in suspension

Jessat, J.; Moll, H.; John, W.; Bilke, M.-L.; Hübner, R.; Kretzschmar, J.; Steudtner, R.; Drobot, B.; Stumpf, T.; Sachs, S.

Daucus carota suspension cells showed a high affinity towards Eu(III) and U(VI) based on a single-step bioassociation process with an equilibrium after 48 to 72 h. Cells responded with an increased metabolic activity towards heavy metal stress. Luminescence spectroscopy pointed to multiple species for both heavy metals in the culture media, providing initial hints of their interaction with cells and released metabolites. Using nuclear magnetic resonance spectroscopy, we could prove that malate, as an released metabolite in the culture medium, was found to complex with U. Luminescence spectroscopy also showed that Eu(III)-EDTA species are interacting with the cells. Furthermore, Eu(III) and U(VI) coordination is dominated by phosphate groups provided by the cells. We found that Ca ion channels of D. carota cells were involved in the uptake of U(VI), which led to a bioprecipitation of U(VI) in the vacuole of the cells, most probably as uranyl(VI) phosphates along with an intracellular sorption of U(VI) on biomembranes by lipid structures. Eu(III) could be found locally concentrated in the cell wall and in the cytoplasm with a co-localization with phosphorous and oxygen.

Keywords: actinides; lanthanides; luminescence spectroscopy; malate; mobilization

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-34322
Publ.-Id: 34322


Charge-density reduction promotes ribozyme activity in RNA–peptide coacervates via RNA fluidization and magnesium partitioning

Iglesias-Artola, J. M.; Drobot, B.; Kar, M.; Fritsch, A. W.; Mutschler, H.; Dora Tang, T.-Y.; Kreysing, M.

It has long been proposed that phase-separated compartments can provide a basis for the formation of cellular precursors in prebiotic environments. However, we know very little about the properties of coacervates formed from simple peptides, their compatibility with ribozymes or their functional significance. Here we assess the conditions under which functional ribozymes form coacervates with simple peptides. We find coacervation to be most robust when transitioning from long homopeptides to shorter, more pre-biologically plausible heteropeptides. We mechanistically show that these RNA–peptide coacervates display peptide-dependent material properties and cofactor concentrations. We find that the interspacing of cationic and neutral amino acids increases RNA mobility, and we use isothermal calorimetry to reveal sequence-dependent Mg2+ partitioning, two critical factors that together enable ribozyme activity. Our results establish how peptides of limited length, homogeneity and charge density facilitate the compartmentalization of active ribozymes into non-gelating, magnesium-rich coacervates, a scenario that could be applicable to cellular precursors with peptide-dependent functional phenotypes.

Keywords: Ribozyme; Coacervates; Origin of llife

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Permalink: https://www.hzdr.de/publications/Publ-34321
Publ.-Id: 34321


Cosmogenic nuclide rates and (U,Th)-He dates of denudation in the eastern Great Escarpment, South Africa

Makhubela, T. V.; Kramers, J. D.; Konyana, S. M.; van Niekerk, H. S.; Winkler, S.

In Southern Africa, cosmogenic nuclides have been used during the past two decades in determining the denudation rates, exposure dates, and burial dates of surfaces, soils, and deposits. That work has focused on the Great Escarpment in the semi-arid to arid western segment in Namibia and the humid south and southeast segments in South Africa (Makhubela et al., 2021a). We present the first cosmogenic beryllium-10 (10Be) denudation rates and uranium-thorium-helium ((U,Th)-He) dates in the very humid eastern segment of the Great escarpment in South Africa (Makhubela et al., 2021b). The 10Be denudation rates were obtained from river sediments and bedrock outcrops (2.7 – 14.1 m/Ma and 1.8 – 24 m/Ma, respectively), and they are similar in range to the values determined from the other segments of the Great Escarpment. These denudation rates are positively correlated with mean annual precipitation above 800 mm/yr, but the similarity of the denudation rates across the segments of the escarpment with different climates suggests that topography is the main driver of denudation. The (U,Th)-He dates were determined on pedogenic goethite concretions in oxisols at Graskop near the escarpment edge, using a new approach that incorporates helium data into U/Th disequilibrium dating. The ages range from 0.85 Ma to 1.05 Ma, documenting a long soil residence time. They coincide with the Mid-Pleistocene Transition and appear to indicate the last period of intensive chemical weathering on the eastern escarpment, when the climate of the region changed from wet to dry conditions whichthat lasted for ca. 600 kyr before the present humidification (Caley et al., 2018). Our results demonstrate that the combination of cosmogenic nuclides and U-series offer a novel way of dating and quantifying Earth surface processes in the context of past climate changes.
Caley, T., et al., 2018. Nature, 560, 76-79.
Makhubela, T. V., et al., 2021a. South African Geographical Journal, 103(1), 99-118.
Makhubela, T. V., et al., 2021b. Chemical Geology, 580, 120368.

  • Poster
    Goldschmidt 2022 Conference, 10.-15.07.2022, Honolulu, Hawaiʻi, USA

Permalink: https://www.hzdr.de/publications/Publ-34320
Publ.-Id: 34320


Uranium(VI) retention by calcium aluminosilicate hydrates (C-A-S-H) – Impact of temperature, ionic strength, and organic ligands

Schmeide, K.; Huittinen, N. M.; Shams Aldin Azzam, S.; Brendler, E.; Kretzschmar, J.

Concepts for the safe disposal of high-level radioactive waste in deep geological formations to ensure isolation from the biosphere are based on a multi-barrier system. Cementitious materials are one component of the geotechnical barrier, used as backfill material, for borehole sealing and to enforce the mechanical stability of tunnels. Calcium silicate hydrate (C-S-H), the principal binding phase of conventional concrete, is known to provide a high sorption capacity for trivalent to hexavalent actinides [1-3]. In modern concretes, Al-containing compounds such as blast furnace slag or fly ash are added, leading to formation of calcium aluminosilicate hydrate (C-A-S-H). To systematically study the influence of Al on both the structure of C-A-S-H phases and their U(VI) retention properties in comparison to C-S-H phases, three series of samples were synthesized in the absence and presence of U(VI). They comprise samples with Ca/Si molar ratios of 0.8, 1.2 and 1.6, representing different alteration stages of concrete, and increasing Al/Si molar ratios of 0, 0.06 and 0.18 within each series. Furthermore, the impact of temperature (25°C, 100°C, 200°C) on the structure of C-A-S-H phases and on the U(VI) retention mechanism was studied. Structural characteristics of the cementitious phases were obtained from powder X-ray diffraction as well as 27Al and 29Si solid-state magic angle spinning nuclear magnetic resonance spectroscopy. Al tetrahedra were identified to occupy bridging positions of the Si chain and cross-linking positions. Enhanced temperatures were found to increase the crystallinity of the material with the appearance of neoformed crystalline phases. U(VI) luminescence spectroscopy was applied to characterize the U(VI) binding. Several U(VI) species (surface-sorbed or C-A-S-H interlayer absorbed) are forming in different amounts, depending on the composition of the C-A-S-H phases.
Finally, to study the stability (or reversibility) of the U(VI) retention by the C-A-S-H phases in the presence of (i) high ionic strength pore waters and (ii) organics originally present as admixtures in cement-based materials, leaching experiments were conducted. In these experiments, simulated pore waters of complex solution composition and solutions containing gluconate as a representative of organic ligands that may be present under repository conditions, respectively, were used. The leaching experiments were conducted over extended timescales of up to 6 months. The results showed a high retention of U(VI) in the C-A-S-H phases under both abovementioned solution conditions. In conclusion, the immobilization of U(VI) by cementitious material via sorption and/or incorporation processes has important positive implications for limiting uranium migration during geological disposal of radioactive waste.

Keywords: C-S-H; C-A-S-H; cement; actinide; uranium; sorption; NMR; TRLFS; XRD; leaching

  • Lecture (Conference)
    RadChem 2022 / 19th Radiochemical Conference, 15.-20.05.2022, Mariánské Lázně, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-34317
Publ.-Id: 34317


Enhanced survival of high-risk medulloblastoma-bearing mice after multimodal treatment with radiotherapy, decitabine, and abacavir

Gringmuth, M.; Walther, J.; Greiser, S.; Toussaint, M.; Schwalm, B.; Kool, M.; Kortmann, R.-D.; Glasow, A.; Patties, I.

Children with high-risk SHH/TP53-mut and Group 3 medulloblastoma (MB) have a 5-year overall survival of only 40 %. Innovative approaches to enhance survival while preventing adverse effects are urgently needed. We investigated an innovative therapy approach combining irradiation (RT), decitabine (DEC), and abacavir (ABC) in a patient-derived orthotopic SHH/TP53-mut and Group 3 MB mouse model. MB-bearing mice were treated with DEC, ABC and RT. Mouse survival, tumor growth (BLI, MRT) tumor histology (H/E), proliferation (Ki-67), and endothelial (CD31) staining were analyzed. Gene expression was examined by microarray and RT-PCR (Ki-67, VEGF, CD31, CD15, CD133, nestin, CD68, IBA). The RT/DEC/ABC therapy inhibited tumor growth and enhanced mouse survival. Ki-67 decreased in SHH/TP53-mut MBs after RT, DEC, RT/ABC, and RT/DEC/ABC therapy. CD31 was higher in
SHH/TP53-mut compared to Group 3 MBs and decreased after RT/DEC/ABC. Microarray analyses showed a therapy-induced downregulation of cell cycle genes. By RT-PCR, no therapy-induced effect on stem cell fraction or immune cell invasion/activation could be shown. We showed for the first time that RT/DEC/ABC therapy improves survival of ortothopic SHH/TP53-mut and Group 3 MB-bearing mice without inducing adverse effects suggesting the potential for an adjuvant application of this multimodal therapy approach in the human clinic.

Keywords: medulloblastoma; radiation; decitabine; abacavir; in vivo study; magnetic resonance imaging; T2 mapping; bioluminescence imaging; gene expression microarray

Permalink: https://www.hzdr.de/publications/Publ-34316
Publ.-Id: 34316


Complexation of Eu(III) in artificial digestive media by aminopolycarboxylic acid EGTA

Friedrich, S.; Holtmann, L.; Kretzschmar, J.; Barkleit, A.; Stumpf, T.

Radionuclides released from nuclear accidents can be widely distributed and even enter the human food chain. If ingested, they interact with the fluids from the digestive system and can cause necrosis or carcinogenesis of human cells. To remove these radionuclides, decorporation agents are used. Clinical approved decorporation agents like ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) that are used against heavy metal poisoning show low oral activity.[1] Therefore, the focus of this work is set on EDTA and DTPA related compound ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA). Europium(III) is used as a non-radioactive analogue for trivalent actinides like americium and curium. The overall goal of the study is to expand the knowledge of processes underlying the interactions of radionuclides in the human digestive system in the presence of decorporation agents on a molecular level. To derive thermodynamic parameters, the Eu-EGTA-system is investigated at different physiological relevant pH values and molar ratios, using time-resolved laser-induced fluorescence spectroscopy (TRLFS), NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and isothermal titration calorimetry (ITC). Between pH 3 and 9 a very stable complex with a Eu(III)-EGTA-ratio of 1:1 is observed and comprehensively characterised from the ligands and metals perspective. Our knowledge on the speciation of Eu(III) in artificial biofluids of the human digestive system is now extended by the impact of EGTA on the speciation to measure the suitability of EGTA as possible decorporation agent for usage in radiation protection.[2] This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant number 02NUK057A and part of the joint project RADEKOR.

[1] P. W. Durbin, Health Phys. 2008, 95, 465.
[2] C. Wilke, A. Barkleit, T. Stumpf, A. Ikeda-Ohno, J. Inorg. Biochem. 2017, 175, 248.

  • Open Access Logo Lecture (Conference)
    19th Radiochemical Conference, 15.-20.05.2022, Marienbad, Tschechien

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Permalink: https://www.hzdr.de/publications/Publ-34315
Publ.-Id: 34315


A scalable pipeline for effective forecast of COVID-19 in Germany, Czechia, and Poland

Abdussalam, W.

We develop a software system for the spatial, temporal, and strategic optimization of the use of tests for SARS-COV-2. We have built an operational data store (ODS) using PostgreSQL to continuously consolidate datasets from multiple data sources, perform collaborative work, facilitate high performance data analysis, and trace changes. The ODS has been built to store the COVID-19 data from Germany, Czechia, and other areas. We have built the schema of metadata which is capable of orderly storing the data from those regions, and is scalable to the entire world. Next, the ODS is populated using batch Extract, Transfer, and Load (ETL) jobs and SQL queries are created which reduce the need for pre-processing data. The data can then support forecasting using a version-controlled Arima and Holt Winter model and other analyses to support decision making. The jobs run at a weekly interval and plan to upgrade to a daily interval. The results are finally displayed as a web app at https://www.where2test.de.

  • Open Access Logo Lecture (Conference) (Online presentation)
    Software Engineering 2022, 21.-25.02.2022, Potsdam Online, Germany

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Permalink: https://www.hzdr.de/publications/Publ-34314
Publ.-Id: 34314


From data to model: microstructure aware models for uncertainty estimation of reactive transport in granitoide rocks

Pospiech, S.; Tolosana Delgado, R.; Brendler, V.; Bachmann, K.; Krause, J.; van den Boogaart, K. G.

Safety of nuclear waste repositories in crystalline host rocks depends on realistic predictions of radionuclide migration in undisturbed geologies beyond the geotechnical barrier. There, the fluid migration paths will be - in absence of large scale connectivities like fissures, fault systems and joints - along weakzones like microcracks, alterations and grain boundaries. The retention potential of crystalline rocks is thus not only controlled by its modal mineralogy but also by the (heterogeneous) distribution of mineral grains, e.g. by contact area of different mineral surfaces to migration paths. Until now, reactive transport models assume homogeneous and isotropic distribution of minerals in the host rock. Including the spatial correlation of transport and mineralogy, especially the modal mineralogy along fluid migration paths, would significantly improve the estimation of radionuclide retention potential.
Modelling the microstructures is subject to uncertainties. Such uncertainties can be derived by estimating this spatial co-occurances from measured microstructures. The workflow requires spatially distributed data from analytical methods, which a) provide information about mineral composition including voids and b) allow to detect migrations paths and the mineral surface types with related areas. Here, information from gneissic samples is used to train a structure simulation model. The resulting variability of "accessible" mineral surfaces then allows to derive (by geochemical speciation codes) the variability of contaminant distribution coefficients based on sorption data and pore water composition. Finally, the spatial geological predictions are applied in reactive transport models to calculate the uncertainty of the radionuclide retention within a representative rock volume. In this contribution, we present a workflow from (real) samples to microstructure aware retention models, and discuss challenges of input data uncertainties, how they affect the total uncertainty of the model, and whether these models can be used for upscaling.

Keywords: nuclear waste repository; microstructure modelling; crystalline rock; geostatistics; radionuclide migration; radionuclide retention

  • Open Access Logo Lecture (Conference)
    21st Annual Conference of the International Association for Mathematical Geosciences, 29.08.-03.09.2022, Nancy, France

Permalink: https://www.hzdr.de/publications/Publ-34313
Publ.-Id: 34313


Energetic Au ion beam implantation of ZnO nanopillars for optical response modulation

Macková, A.; Malinský, P.; Jagerová, A.; Mikšová, R.; Lalik, O.; Nekvindová, P.; Mistrík, J.; Marvan, P.; Sofer, Z.; Holý, V.; Schutter, J. D.; Kentsch, U.; Azarov, A.; Galeckas, A.

Nanopillars of ZnO were implanted with Au-400 keV ions at various ion fluences from 1 × 10¹⁵ cm⁻² to 1 × 10¹⁶ cm⁻² and subsequently annealed at 750 °C for 15 min in order to reduce the implantation damage and to support Au nanoparticle (NP) aggregation. It was found that implantation-induced effects and thermal effects influence the Au NP coalescence as well as the quality of the ZnO nanopillars. Rutherford Back-Scattering spectrometry (RBS) showed the broader Au-depth profiles than it was theoretically predicted, but the Au-concentration maximum agrees well with prediction taking into account the effective ZnO layer density. The implantation at the higher fluences induced the morphology modification of the nanopillar layer evidenced by RBS and scanning electron microscopy (SEM). An indirect evidence of this effect was given by optical ellipsometry due to gradual refractive index changes in the ZnO nanopillars with the increased Au-ion fluence. Optical characterization of the Au-implanted and annealed nanopillars performed by means of photoluminescence (PL) and diffuse-reflectance spectroscopy (DRS) evidenced the surface plasmon resonance (SPR) activity of the embedded Au NPs. The SPR-enhanced scattering and PL emission observed in the spectral range 500–650 nm are ascribed to Au NPs or more complex Au-clusters. In addition, the ellipsometry measurements of extinction coefficient are found to corroborate well results from DRS, both indicating increase of SPR effect with the increase of Au-ion fluence and after the post-annealing.

Keywords: ZnO nanopillars; Au nanoparticles; ion implantation; SPR; doped ZnO nanostructures

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Permalink: https://www.hzdr.de/publications/Publ-34312
Publ.-Id: 34312


Spectroscopic investigation of the speciation of uranium(VI) in the biofluids of the human digestive system

Butscher, D.; Barkleit, A.; Stumpf, T.

In case radionuclides (RN) enter the food chain and are incorporated by humans, they pose a possible health risk due to their radio- and chemotoxicity. Therefore, it is necessary to know the biokinetic processes as well as the speciation of the RN after ingestion in order to develop and improve specific methods for their decorporation. When RN are ingested orally, they first come into contact and interact with the biofluids of the digestive tract. However, for most actinides, little is known to date about their speciation and biochemical behavior in the gastrointestinal tract. Therefore, the aim of this study was to investigate the interactions of hexavalent uranium in the digestive steps and respective biofluids in the stomach (saliva and gastric juice) and small intestine (pancreatic juice and bile fluid). The combination of these two segments was also considered. Biofluids and digestive steps were artificially simulated based on human physiology. The chemical speciation of uranium was investigated using cryogenic time-resolved laser-induced fluorescence spectroscopy (cryo-TRLFS) at 153 K. The results were compared with thermodynamic modeling.
The TRLFS experiments show that uranium is predominantly complexed with inorganic ligands, mainly carbonate and to a smaller extent phosphate, as confirmed by thermodynamic modeling. For the organic ligands, only some proteins, e.g. prancreatin, are involved in the speciation to a small extent. Based on this knowledge, specific decorporation agents can be developed and their influence on uranium speciation can be observed using cryo-TRLFS.

  • Lecture (Conference)
    RadChem 2022 / 19th Radiochemical Conference, 15.-20.05.2022, Marianske Lazne, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-34311
Publ.-Id: 34311


Data publication: Non-invasive assessment of locally overexpressed human adenosine 2A receptors in the heart of transgenic mice

Gündel, D.; Lai, T. H.; Dukic-Stefanovic, S.; Teodoro, R.; Deuther-Conrad, W.; Toussaint, M.; Moldovan, R.-P.; Kopka, K.; Boknik, P.; Hofmann, B.; Gergs, U.; Neumann, J.; Brust, P.

PET data, mice; i.v. administration of [18F]FLUDA with and without pre-administration of istradefylline

Keywords: [18F]FLUDA; A2A adenosine receptor; PET; myocardium

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Permalink: https://www.hzdr.de/publications/Publ-34310
Publ.-Id: 34310


Compositional Data Analysis of Organizational Culture and Business-IT Alignment

Sieber, M. R.; van den Boogaart, K. G.

This research project examines the relationship between organizational culture and business-
IT alignment. With the Fourth Industrial Revolution and digitalization, this relationship is
changing. IT and its management tend to evolve from a service provider to a value creator. The
research question is about typical management culture characteristics and their contributions to
the strategic alignment to the business of the IT departments, teams, and solution providers.
For answering the research question, this study juxtaposes two four-quadrants models. First,
it applies Cameron and Quinn’s (2011) Competing Values Framework for examining organiza-
tional culture. This model attributes culture to the four types of clan culture, adhocracy culture,
market culture, and hierarchy culture with the dimensions of flexibility vs. stability and an in-
ternal vs. external focus. Similarly, Henderson and Venkatraman’s (1993) Strategic Alignment
Model differs four perspectives for business-IT alignment with the dimensions of functional inte-
gration into IT or business and the strategic fit, i.e., the internal vs. external orientation. These
strategic alignment perspectives and their performance criteria equal a cost center, an investment
center, a profit center, and a service center.
In a survey, respondents had to divide 100 points between four options. For example, the
dominant IT management culture type: is it a clan, adhocracy, market, or hierarchy? The
corresponding ipsative scales originate from the Competing Values Framework and result in
compositional data. After eliminating missing values and imputing zeroes, the analysis calculated
a linear model with the ilr-transformed variables in R with the package compositions. Converting
ilr coefficients into the clr space revealed a variance-/covariance-matrix with the weights of IT
management culture and its alignment as the mapping of clan culture to cost center at 0.05,
adhocracy culture to investment center at 0.13, market culture to profit center at 0.17 and
hierarchy culture to service center at 0.19.

Keywords: Organizational culture; business-IT alignment; Competing Values Framework; Strategic Alignment Model; Compositional Data

  • Poster
    CoDaWork2022, 28.06.-01.07.2022, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-34308
Publ.-Id: 34308


Kinetic Aspects of the Electrochemical Reduction of Uranyl in HCl Solutions

Munoz, A.; Weiß, S.

The interfacial mechanism of uranyl electroreduction at Au-electrodes in HCl solutions was discussed on the light of systematic studies of cyclovoltammetry, normal pulse voltammetry, UV-vis spectroscopy and published electroanalytical research. Voltammetric waves were numerically deconvoluted on the basis of a reaction model consisting of a first masscontrolled, quasi-reversible first electron transfer and a subsequent reduction of interfacial U(V) intermediate species with adsorption of generated U(IV) products. The dependence of the kinetic parameters on [HCl] indicates an electron transfer following an inner-sphere type mechanism assisted by electrosorption of chloride ligands. The interfacial accumulation of chloride exerts a strong electrostatic repulsion of complexed uranyl and a consequent edged drop of electron transfer rates at [HCl] ∼ 0.5 mol l-1. The electron transfer steps are followed by a chemical desorption reaction of the unstable tetravalent uranyl in U(H2O)94+ species. It is shown that the numerical reproduction of voltammetric waves suits as a method for calculating kinetic parameters in multi-steps electrochemical reactions.

Keywords: Cell proliferation; Cyclic voltammetry; Electron transitions; Gold compounds; Reaction intermediates; Interfacial mechanism

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Permalink: https://www.hzdr.de/publications/Publ-34307
Publ.-Id: 34307


A critical review of the solution chemistry, solubility, and thermodynamics of Eu(III)

Jordan, N.; Thoenen, T.; Starke, S.; Spahiu, K.; Brendler, V.

New materials showing specific magnetic and/or electrooptic properties incorporate critical raw materials such as Rare Earth Elements (REE). Due to their very specific technological application, it is necessary to separate the REE from each other and enrich them. The optimization of physico-chemical conditions for the design of effective extraction and recycling processes of REE relies on accurate and reliable thermodynamic data. However, no consolidated and internationally recognized Thermodynamic Database (TDB) is currently available for REE.

Several reviews and reports [1-5] on the aqueous chemistry/geochemistry of europium were published, but had several drawbacks, for example:

→ insufficient transparency about the selection procedure,
→ lack of systematic screening to gather primary literature sources,
→ too high reliance on the analogy with trivalent actinides,
→ for weak complexes such as chloride and nitrate, changes in the activity coefficients due to the replacement of up to 100 % of the background electrolyte anion by Cl− or NO3− was either completely overlooked or, if recognized, not handled properly,
→ too high reliance on the charge analogy for the estimation of missing ion interaction coefficients when the Specific ion Interaction theory (SIT) was applied.

This study aims at significantly improving the situation by carefully addressing all aforementioned issues in order to provide a reliable, robust, and internally consistent TDB for europium. All available primary literature sources for Eu(III) complexation constants and solubility products for the OH−, Cl−, NO3−, PO43−, SO42−, and CO32− inorganic ligands were thoroughly evaluated. This allowed deriving a recommended set of thermodynamic data at infinite dilution and 25 °C using the SIT. Results concerning the chloride, sulfate, and phosphate ligands will be presented [6].

[1] P.L. Brown, C. Ekberg, Hydrolysis of Metal Ions. Vol. 1, Wiley-VCH, Weinheim, 2016.
[2] W. Hummel, et al., Nagra/PSI Chemical Thermodynamic Data Base 01/01, Technical Report 02-16, 2002.
[3] J.A. Rard, Chemical Reviews, 85(6) (1985) 555-582.
[4] K. Spahiu, J. Bruno, A selected thermodynamic database for REE to be used in HLNW performance assessment exercises, SKB Technical Report, 1995.
[5] S.A. Wood, Chemical Geology, 82(1-2) (1990) 159-186.
[6] N. Jordan et al., Coordination Chemistry Review (2022) (under revision).

Keywords: Europium; Thermodynamic database; complexation; solubility; SIT

  • Contribution to proceedings
    Goldschmidt 2022, 10.-15.07.2022, Hawaiʻi, USA
  • Lecture (Conference) (Online presentation)
    Goldschmidt 2022, 10.-15.07.2022, Hawaiʻi, USA

Permalink: https://www.hzdr.de/publications/Publ-34305
Publ.-Id: 34305


Growth factor receptor and β1 integrin signaling differentially regulate basal clonogenicity and radiation survival of fibroblasts via a modulation of cell cycling

Vehlow, A.; Cordes, N.

Cell adhesion to extracellular matrix proteins mediates resistance to radio- and chemotherapy by activating integrin signal-
ing. In addition, mutual and cooperative interactions between integrin and growth factor receptor signaling contribute to
the cellular radiation response. Here, we investigate to which extend the crosstalk between β1 integrins and growth factor
receptor signaling determines the cellular radiation response of fibroblasts by assessing clonogenic survival and cell cycling.
By utilizing growth factor signaling competent and either β1 integrin wildtype GD25β1A fibroblasts or β1 integrin mutant,
signaling incompetent GD25β1B fibroblasts, we show basal clonogenic survival to depend on growth factor receptor but not
integrin signaling. Our data further suggest the cooperation between β1 integrins and growth factor receptors to be critical
for enhancing the radiation-induced G2/M cell cycle block leading to improved clonogenic radiation survival. By pharmaco-
logical inhibition of EGFR and PI3K, we additionally show that the essential contribution of EGFR signaling to radiogenic
G2/M cell cycle arrest depends on the co-activation of the β1 integrin signaling axis, but occurs independent of PI3K. Taken
together, elucidation of the signaling circuitry underlying the EGFR/β1 integrin crosstalk may support the development of
advanced molecular targeted therapies for radiation oncology.

Keywords: beta1 integrin; Growth factor receptor; Cell cycle; Ionizing radiation

Permalink: https://www.hzdr.de/publications/Publ-34303
Publ.-Id: 34303


Nuclear Magnetic Resonance of Actinides

Kaden, P.

This book chapter covers all aspects of nuclear magnetic resonance spectroscopy observing actinides and nuclei in actinide-containing compounds with this spectroscopic technique.

Keywords: NMR; actinides

  • Book chapter
    Stephen T Liddle, David P Mills, Louise S Natrajan: The Lanthanides and Actinides Synthesis, Reactivity, Properties and Applications, London / UK: World Scientific Europe, 2022, 978-1-80061-015-6, 617-631
    DOI: 10.1142/9781800610163_0016

Permalink: https://www.hzdr.de/publications/Publ-34302
Publ.-Id: 34302


Radiation studies for MU2E-II

Müller, S.

Presentation at MU2E-II Workshop (virtual), February 22, 2022

Keywords: MU2E; FLUKA; Simulation

  • Open Access Logo Lecture (others) (Online presentation)
    Mu2e-II Snowmass22 Workshop (xi), 22.02.2022, virtuell, USA

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Permalink: https://www.hzdr.de/publications/Publ-34301
Publ.-Id: 34301


Future Knowledge in Geometallurgical Mining Optimization

van den Boogaart, K. G.

Mining and processing involves a lot of decision making, on capacity
building, mine scheduling, blending, process parameters, and
contracted sales. Traditionally stochastic mine planning and
predictive Geometallurgy use stochastic knowledge provided e.g. by
conditional geostatistical simulations of the conditional
distributions of ore properties to infere optimal decisions through
stochastic optimization. Stochastic knowledge is however no fixed
fact, but can rather increase by later aquisition of information,
automatically as a direct consequence of the operation itself, and
optionally through additional exploration.

The contribution shows with simple and easy to comprehend sand box
examples how and why such future knowledge and even the option to
obtain future knowledge already changes, what is an optimal decision
even before this knowledge is obtained. In case of optional knowledge,
the decision to obtain it and when, becomes an integral part of the
decision problem. This radically changes what algorithms can be
feasibly used to compute optimal decissions. Straight forward
stochastic optimization is not yet computationally feasible, for
situations with increasing knowledge. The state of the art for models
using increasing information is to use reinforcement learning based
heuristics.

This contribution explores the idea of making a stochastic
optimizating possible by exploiting certain structures of the mining
related increasing knowledge optimization problem. Possible speedup
are based on 1) inequality relations in stochastic optimization
allowing for advanced branch and bound techniques, 2) exploiting the
fact that certain values are equivalent in different branches which
simplifies comparisions and precomputation, and 3) explicit
computation of conditional expectations in a partial separation of the
processing optimization and the scheduling optimization.

Keywords: geometallurgical optimization; branch and bound; inequalities; mining geostatistics

  • Lecture (Conference)
    IAMG 2022, 29.08.-02.09.2022, Nancy, France

Permalink: https://www.hzdr.de/publications/Publ-34300
Publ.-Id: 34300


Np(V) uptake by the cladding corrosion product zirconia: a combined batch, spectroscopic, and modeling approach

Jessat, I.; Roßberg, A.; Scheinost, A.; Lützenkirchen, J.; Foerstendorf, H.; Jordan, N.

When assessing the safety of a nuclear waste repository, the interactions of dissolved long-lived radionuclides, such as the actinide neptunium, with corrosion products in the near-field of the repository are crucial processes that have to be taken into account. Zirconia (ZrO₂), the main corrosion product of the zircaloy cladding material of nuclear fuel rods, constitutes a first barrier against the release of radionuclides into the environment.
A multimethod approach was pursued to gain a thorough understanding of the Np(V) sorption processes on the water−zirconia interface. For the macroscopic description of the Np(V)−ZrO₂ system, pH-dependent batch sorption experiments (varying ionic strength, Np(V) concentration, and the solid-to-liquid ratio) as well as a sorption isotherm experiment at pH 6 were conducted. The uptake of Np(V) was pH-dependent, with an increased sorption starting from pH 3 and being at a maximum at pH 6 and above. The Np(V) sorption was independent of ionic strength, hinting to the presence of Np(V) inner-sphere complexes on the zirconia surface. This was supported by zeta potential measurements in the presence of neptunium, where a shift to higher pH values of the isoelectric point of the neat ZrO₂ was observed. The Np(V) sorption edge was shifted towards lower pH values with increasing solid-to-liquid ratio, indicating the presence of different kinds of sorption sites, which was also deduced from the shape of the sorption isotherm.
Molecular information of the surface species were obtained by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) and in situ Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) revealing the predominant formation of inner-sphere Np(V) surface complexes. A short Np−Zr distance derived from EXAFS spectra suggested the presence of Np(V) bidentate complexes at the zirconia surface.
Reliable information about the number and denticity of surface species obtained by macroscopic and molecular spectroscopic investigations potentially facilitate modeling approaches such as surface complexation modeling (SCM) that in turn will contribute to a more profound prediction of the environmental behavior of neptunium.

Keywords: neptunium(V); zirconia; ZrO₂; sorption; spectroscopy; EXAFS; IR

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  • Lecture (Conference) (Online presentation)
    Goldschmidt Conference, 10.-15.07.2022, Honolulu, Hawaiʻi, USA

Permalink: https://www.hzdr.de/publications/Publ-34299
Publ.-Id: 34299


Neutron-irradiated concrete: Structural characterisation and gamma dosimetry.

Roode-Gutzmer, Q. I.; Barkleit, A.; Rachamin, R.; Hennig, C.; Weiß, S.; Paasch, S.; Konheiser, J.; Stumpf, T.

Increased reactivity of radiation-damaged quartz in the alkaline pore water of concrete and its role in radionuclide transport is a subject that is becoming increasingly important as nuclear power plants (NPPs) around the world reach end-of-life. Quartz contributes more than half the weight of most concretes and up to 40 % of the total radioactive waste volume associated with the dismantling of an NPP.

The gamma-emitting radionuclides are the major contributors to the radiation dose rate in the concrete biological shield in the intermediate term after NPP shut-down. The appreciable activity and associated half-lives of these radionuclides pose a problem not only during the safe dismantling of NPPs, but also in terms of processing the concrete to reduce the active waste volume for final disposal in a repository.

While thermal neutrons are captured by atomic nuclei according to their thermal neutron cross-sections, fast neutrons undergo collision cascades, which cause defects in the structure of materials. The concentration of defects accumulates as a function of neutron energy and fluence. The high covalency and the density of Si-O bonds in tectosilicates, primarily quartz, followed by feldspars, makes these minerals very susceptible to radiation damage.

In this study, two inactive concrete powder samples were placed inside an instrumentation channel passing through the first biological shielding of an operating German NPP, respectively for a half- and a full fuel cycle. Using a plant-specific 3D-reactor model in conjunction with Monte Carlo neutron transport calculations, neutron fluences at the sample positions and the resulting gamma activities are calculated. We compare the measured and calculated activities of the gamma-emitting radionuclides

Synchrotron X-ray powder diffractometry was used to examine structural changes on sub-nanoscale. The local structure of the silicate aggregate minerals was investigated by solid-state magic angle spinning nuclear magnetic resonance (NMR) Spectroscopy using 27Al and 29Si as probes.

With this work we wish to gain insights into the potential for alkali-silica reaction (ASR) in radiation-damaged concrete and the role this plays in the transport or sorption of radionuclides either present in situ via neutron activation or ex situ due to transport of leaked reactor cooling water.

Keywords: concrete biological shield; neutron activation; gamma dosimetry; Monte Carlo neutron transport calculations; radionuclides; radiation damage; quartz; alkali silica reaction

Related publications

  • Lecture (Conference)
    RadChem 2022 / 19th Radiochemical Conference, 15.-20.05.2022, Marianske Lazne, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-34298
Publ.-Id: 34298


Die Rolle von Mikroorganismen bei der Lagerung von hoch-radioaktiven Abfällen - Mikrobiologie am HZDR - (2022)

Matschiavelli, N.

Der Vortrag gibt einen Überblick über mikrobielle Prozesse in einem Endlager für hoch-radioaktiven Müll

  • Lecture (others) (Online presentation)
    Girl´s & Boy´s day 2022, 28.04.2022, HZDR, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34297
Publ.-Id: 34297


Microbial influence on cast iron corrosion under repository-relevant conditions

Matschiavelli, N.

Darstellung und Presentation von Daten innerhalb des UMB-II Projektes

  • Lecture (others)
    UMB-II 3rd workshop, 09.-10.03.2022, Greifswald, Dresden
  • Lecture (others)
    UMB-II 4th projectmeeting, 26.10.2022, Braunschweig, Deutschland
  • Lecture (others)
    UMB-II 5th project meeting, 03.-04.05.2023, Garching, Deutschland
  • Open Access Logo Lecture (others)
    UMB-II 6th project meeting, 05.-06.12.2023, Hannover, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34296
Publ.-Id: 34296


Beam pulse structure and dose rate as determinants for the Flash effect observed in zebrafish embryo

Karsch, L.; Pawelke, J.; Brand, M.; Hans, S.; Hideghety, K.; Jansen, J.; Leßmann, E.; Löck, S.; Schürer, M.; Schurig, R.; Seco, J.; Szabo, E. R.; Beyreuther, E.

Background and purpose
Continuing recent experiments at the research electron accelerator ELBE at the Helmholtz-Zentrum Dresden-Rossendorf the influence of beam pulse time structure on the Flash effect should be investigated in a zebrafish embryo model.
Materials and methods
The pulse structures of an isochronous and a synchrocyclotron were mimicked at ELBE with mean dose rates of 287 Gy/s and 177 Gy/s and pulse dose rates of 106 Gy/s and 109 Gy/s, respectively; and a macro pulsing for the latter. For comparison, a maximum (mean dose rate 2.5 x 105 Gy/s, pulse dose rate ~109 Gy/s) and a reference (mean dose rate of ~8 Gy/min) regime were applied. Radiation induced changes were assessed in zebrafish embryos over four days post irradiation.
Results
A significant protecting Flash effect with a clear dependence on mean dose rate was revealed for almost all endpoints and all electron pulse regimes relative to the reference. The macro pulse dependent prolongation of treatment time of the synchrotron-like regime reduce the protecting effect compared to the maximum regime delivered at same pulse but higher mean dose rate. The protecting Flash effect of the cyclotron-like regime was confirmed at a clinical isochronous proton cyclotron comparing the effects induced by 300 Gy/s relative to conventional proton beam delivery.
Conclusion
The mean dose rate or treatment time are more important than pulse dose rate for the extent of the normal tissue protecting Flash effect.

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Publ.-Id: 34295


Spin-aware quantum-accurate interatomic potentials for heavy elements

Lokamani, M.; Ramakrishna, K.; Nikolov, S.; Tranchida, J.; Juckeland, G.; Wood, M.; Cangi, A.

Studying matter under extreme conditions using density functional theory (DFT) is computationally expensive, since the degrees of freedom and consequently the configurational space grows rapidly with increasing temperature and pressure. Therefore, the use of DFT for such simulations is limited to fairly small simulation cells and time scales. Machine learning-based interatomic potentials (ML-IAP) provide access to much larger spatial and temporal domains, thus enabling the discovery of new and exotic magnetic materials. A majority of existing descriptors required to construct ML-IAPs neglect the spin degrees of freedom. Here, we present our preliminary ideas/workflows to construct "spin-aware" ML-IAP using the SNAP[1] descriptors and the coupled spin-molecular dynamics framework implemented in LAMMPS [2]. This modeling capability will complement upcoming experiments to magneto-structural properties in shock- compressed or laser-driven samples at elevated temperatures and pressures exposed to strong, pulsed magnetic fields, which are planned at photon sources such as within the HIBEF consortium at the European XFEL.

Keywords: matter under extreme conditions; Machine learning-based interatomic potentials; coupled spin-molecular dynamics; High-throughput; Advanced data science; Hyperparameter optimization

  • Open Access Logo Poster
    DFT Methods for Matter under Extreme Conditions, 21.-22.02.2022, Görlitz, Saxony, Germany

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Publ.-Id: 34294


Fe+ ion irradiation effects in Fe-10at%Cr films irradiated at 300 °C

Pantousa, S.; Mergia, K.; Ionescu, A.; Manios, E.; Dellis, S.; Kinane, C.; Langridge, S.; Caruana, A.; Kentsch, U.; Messoloras, S.

Fe-Cr alloys constitute the model systems for the investigation of radiation damage effects in ferritic-martensitic steels which are candidate structural materials for fusion reactors. In the current study Fe-10at%Cr alloy films of 70 nm thickness were irradiated by 490 keV Fe+ ions at 300 °C at doses ranging from 0.5 up to 20 displacements per atom (dpa). The Fe+ ion energy chosen corresponds to the energy of primary Fe(Cr) knock-on atoms from 14 MeV neutrons. The irradiation effects were investigated employing X-ray diffraction and X-ray and polarized neutron reflectivity. The irradiation produced dose dependent: a) lattice constant increase, b) grain size growth and c) Cr depletion in the matrix. These changes occur largely up to 4 dpa and afterwards the system attains a dynamic equilibrium.

Keywords: Fe-Cr alloys; ion irradiation; lattice damage; Cr depletion; polarized neutron reflectivity; magnetization

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Permalink: https://www.hzdr.de/publications/Publ-34293
Publ.-Id: 34293


The role of crustal thickness on magma composition in arcs: An example from the pre-Andean, South American Cordillera

Alasino, P. H.; Paterson, S. R.; Kirsch, M.; Larrovere, M. A.

We explore the temporal evolution of pre-Andean Cordilleran arcs in central and northwestern Argentina and northern Chile (27°-34°S) with a focus on the geochemical characteristics of the episodic magmatism and the relationship with crustal thickness. A compilation of ca. 5000 U-Pb bedrock and detrital zircon ages, with ages from 600 to 130 Ma, reveals seven temporal magmatic accretions with main peaks at ~526 Ma (Pampean); ~471 Ma (Famatinian); ~340 and ~305 Ma (Early Gondwanan); ~253 and ~221 Ma (Gondwanan); and ~ 160 Ma (Early Andean). We show that most of the magmatic episodes were developed in 30-50 km thick crust. Magmatism experienced fractional crystallization (r = 0) combined with variable degrees of assimilation (r > 0) that mostly did not exceed 30% crust. We conclude that increasing crustal thickness not only promotes more extensive differentiation by fractionation but also establishes conditions near host rock solidi at shallow crustal levels promoting further contamination in magmas.

Keywords: Cordilleran arc; Crust; Magmatic tempos; Mantle procceses

Permalink: https://www.hzdr.de/publications/Publ-34292
Publ.-Id: 34292


Roadmap on Spin-Wave Computing

Chumak, A. V.; Kabos, P.; Wu, M.; et al.; Schultheiß, H.; Schultheiß, K.

Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors that covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with Boolean digital data, unconventional approaches like neuromorphic computing, and the progress towards magnon-based quantum computing. The article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction.

Keywords: Spin wave; Magnon; Magnonics; Computing; Data processing

Permalink: https://www.hzdr.de/publications/Publ-34291
Publ.-Id: 34291


Data publication: Multisite Dopamine Sensing with Femtomolar Resolution Using a CMOS Enabled Aptasensor Chip

Baraban, L.; Seichepine, F.; Sessi, V.; Ibarlucea, B.; Klinghammer, S.; Ibrahim, I.; Heinzig, A.; Szabo, N.; Mikolajick, T.; Reinhold Hierlemann, A.; Frey, U.; Weber, W.; Cuniberti, G.

Data describe the graphs summarized into the figures with a possibility of opening the figures and direct data access.

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Permalink: https://www.hzdr.de/publications/Publ-34290
Publ.-Id: 34290


Lab Scale Experimental Studies For Modeling Possible Zinc Removal Efforts in LOCA Situations

Harm, U.; Kryk, H.; Hampel, U.; Seeliger, A.; Alt, S.; Kästner, W.

During the sump recirculation phase after a postulated LOCA in PWR, the coolant in the reactor sump is recirculated to the reactor core by residual-heat removal pumps as part of the emergency core cooling system. Long-term contact of the boric acid containing coolant with hot-dip galvanized containment internals (e.g. grating treads) is assumed to cause corrosion of corresponding materials with the consequence of rising concentrations of dissolved zinc in coolant. As it was shown in previous research projects, subsequently formed zinc borates may precipitate within hot spots of the reactor core in the late phase of the LOCA causing thermal hydraulic effects. In PWR, ion exchange columns are installed as part of the coolant cleaning system, having potential to be used to remove dissolved zinc ions.
For evaluation of such approach, lab scale investigations with ion exchange resins to remove dissolved zinc ions from the coolant are carried out under typical conditions of the post LOCA phase (sump recirculation). The usability of the coolant cleaning system for this purpose was proven successfully. The further aim is to model the zinc removal process by the coolant cleaning system by means of data of the ion exchange capacity of different ion exchange resins and kinetic data for the zinc removal under LOCA conditions.

The investigations are carried out as joint research project of Helmholtz-Zentrum Dresden - Rossendorf, TU Dresden, and Hochschule Zittau/Goerlitz. The goal is to build up a database for extensions of thermo-hydraulic simulation tools by the project partner GRS.

Keywords: PWR; LOCA; coolant cleaning system; zinc; modeling

  • Contribution to proceedings
    The 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19), 06.-11.03.2022, Brussels, Belgium
    Proceedings of NURETH-19
  • Lecture (Conference) (Online presentation)
    The 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19), 06.-11.03.2022, Brussels, Belgium

Permalink: https://www.hzdr.de/publications/Publ-34289
Publ.-Id: 34289


Understanding the M4 edge HERFD XANES of U6+

Amidani, L.; Volkova, A.; Retegan, M.; Popa, K.; Martin, P.; Kvashnina, K.

Hexavalent uranium is of considerable importance in the actinide field, and its characterization, consequently, of fundamental concern. The application of High-Energy-Resolution Fluorescence-Detected X-ray Absorption Near-Edge Structure (HERFD XANES) spectroscopy at the M4 edge of actinides probes the 5f electronic structure with augmented resolution compared to conventional XANES and is gaining great popularity. If, from one side, the extreme sensitivity of M4 HERFD XANES to actinides’ oxidation state is well-established [1], its sensitivity to the local environment has been less extensively explored [2,3]. The partially filled 5f subshell makes intra-atomic electron interactions the primary force shaping the spectrum, and simulations treating multi-electronic effects can only approximately account for the local environment.
In these regards, U6+, with its empty 5f shell, is a fortunate exceptional case. Simulation approaches based on the one-electron approximation can then be applied, and the dependence on the local environment be carefully investigated. We recently reported a detailed investigation where experimental and simulated M4 HERFD XANES are obtained on a set of U6+ compounds with different local environments [4]. The coordination of U6+ represented by the set of samples comprises an almost perfect UO6 octahedral bipyramid (Sr3UO6), two UO6 featuring the uranyl ion (Cs2UO2Cl4 and SrUO4), and a UO8 distorted hexagonal bipyramid (CaUO4).
Experimental M4 HERFD are shown in Figure 1. The spectral shape has a similar structure, made of three or four peaks of decreasing intensity. At the same time, it presents significant differences indicating the substantial impact on the spectral shape of the local environment. We simulated the set of U6+ compounds with the DFT-based code FDMNES [5]. The good agreement between theory and experiment, see Fig. 1, makes it reasonable to have a closer look at the underlying f-density of states and to assign spectral features to specific f-orbitals.
Simulations allow to rationalize how the local coordination of U6+ affects the M4 HERFD XANES and demonstrate its high sensitivity to the local environment. Simulations based on crystal field theory were also performed. Their comparison to FDMNES results will be discussed.

  • Lecture (Conference)
    JdA 51 - Journées des Actinides, 10.-14.04.2022, Santa Margherita, Italia

Permalink: https://www.hzdr.de/publications/Publ-34288
Publ.-Id: 34288


State-resolved ultrafast charge and spin dynamics in [Co/Pd] multilayers

Le Guyader, L.; Higley, D. J.; Pancaldi, M.; Liu, T.; Chen, Z.; Chase, T.; Granitzka, P. W.; Coslovich, G.; Lutman, A. A.; Dakovski, G. L.; Schlotter, W. F.; Shafer, P.; Arenholz, E.; Hellwig, O.; Lalieu, M. L. M.; Koopmans, B.; Reid, A. H.; Bonetti, S.; Stöhr, J.; Dürr, H. A.

We use transient absorption spectroscopy with circularly polarized x-rays to detect laser-
excited hole states below the Fermi level and compare their dynamics with that of unoc-
cupied states above the Fermi level in ferromagnetic [Co/Pd] multilayers. While below
the Fermi level an instantaneous and significantly stronger demagnetization is observed,
above the Fermi level the demagnetization is delayed by 35 ± 10 fs. This provides a direct
visualization of how ultrafast demagnetization proceeds via initial spin-flip scattering of
laser-excited holes to the subsequent formation of spin waves

Permalink: https://www.hzdr.de/publications/Publ-34287
Publ.-Id: 34287


Multisite Dopamine Sensing with Femtomolar Resolution Using a CMOS Enabled Aptasensor Chip

Baraban, L.; Seichepine, F.; Sessi, V.; Ibarlucea, B.; Klinghammer, S.; Ibrahim, I.; Heinzig, A.; Szabo, N.; Mikolajick, T.; Reinhold Hierlemann, A.; Frey, U.; Weber, W.; Cuniberti, G.

Many biomarkers including neurotransmitters are found in external body fluids, such as sweat or saliva, but at lower titration levels than they are present in blood. Efficient detection of such biomarkers thus requires, on the one hand, to use techniques offering high sensitivity, and, on the other hand, to use a miniaturized format to carry out diagnostics in a minimally invasive way. Here, we present the hybrid integration of bottom-up silicon-nanowire Schottky-junction FETs (SiNW SJ-FETs) with complementary-metal–oxide–semiconductor (CMOS) readout and amplification electronics to establish a robust biosensing platform with 32 x 32 aptasensor measurement sites at a 100 µm pitch. The applied hetero-junctions yield a selective biomolecular detection down to femtomolar concentrations. Selective and multi-site detection of dopamine is demonstrated at an outstanding sensitivity of ~ 1 V/fM. The integrated platform offers great potential for detecting biomarkers at high dilution levels and could be applied, for example, to diagnosing neurodegenerative diseases or monitoring therapy progress based on patient samples, such as tear liquid, saliva, or eccrine sweat.

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Permalink: https://www.hzdr.de/publications/Publ-34286
Publ.-Id: 34286


Design and production of tungsten-carbide rich coating layers

Racz, A. S.; Fogarassy, Z.; Kentsch, U.; Panjan, P.; Menyhard, M.

Ion beam induced mixing (IBM) can be used for making protecting coating layers at room temperature. We have studied the production of tungsten-carbide, having high strength and low friction, by IBM since this material is also a candidate for protective coatings. WC rich layers have been produced by irradiating C/W multilayer of various structures (with individual layer thicknesses from 10 to 20 nm) by noble gases using medium energy projectiles. The resulting alterations of the samples have been measured by Auger electron spectroscopy (AES) depth-profiling. TRIDYN simulations, with some parametrization, were applied to determine the elemental in-depth distribution after IBM; the compound formation was calculated by a simple model. The calculated and measured depth profiles were compared and excellent agreement has been found for a rich dataset differing in layer structures, projectiles, ion fluences and energies. The good agreement in a wide parameter range validates our procedure and allows the design of the WC-rich layers and also enables the significant decrease of the experimental work.

Keywords: Tungsten-carbide; WC; Coating; Simulation; Ion irradiation; TRIDYN

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Permalink: https://www.hzdr.de/publications/Publ-34285
Publ.-Id: 34285


A perfect match between borophene and aluminium in the AlB3heterostructure with covalent Al-B bonds, multiple Dirac points and a high Fermi velocity

Jiao, Y.; Ma, F.; Zhang, X.; Heine, T.

By performing a swarm-intelligent global structure search combined with first-principles calculations, a stable twodimensional (2D) AlB3 heterostructure with directed, covalent Al-B bonds forms due to a nearly perfect lattice match between 2D borophene and the Al(111) surface. The AlB3 heterosheet with the P6mm space group is composed of a planar Al(111) layer and a corrugated borophene layer, where the in-plane coordinates of Al covalently link with the corrugated B atoms. The resulting structure shows a similar interlayer interaction energy to that of the Al(111) surface layer to the bulk and high mechanical and thermal stability, possesses multiple Dirac points in the Brillouin zone with a remarkably high Fermi velocity of 1.09 × 106 m s-1, which is comparable to that of graphene. Detailed analysis of the electronic structure employing the electron localisation function and topological analysis of the electron density confirm the covalent Al-B bond with high electron localisation between the Al and B centres and with only little interatomic charge transfer. The combination of
borophene with metal monolayers in 2D heterostructures opens the door to a rich chemistry with potentially unprecedented properties.

Keywords: Calculations; Charge transfer; Electronic structure; Graphene; Topology; Dirac point

Permalink: https://www.hzdr.de/publications/Publ-34284
Publ.-Id: 34284


Quantifying the Dzyaloshinkii-Moriya Interaction Induced by the Bulk Magnetic Asymmetry

Zhang, Q.; Liang, J.; Bi, K.; Zhao, L.; Bai, H.; Cui, Q.; Zhou, H.-A.; Bai, H.; Feng, H.; Song, W.; Chai, G.; Gladii, O.; Schultheiß, H.; Zhu, T.; Zhang, J.; Peng, Y.; Yang, H.; Jiang, W.

A broken interfacial inversion symmetry in ultrathin ferromagnet/heavy metal (FM/HM) bilayers is generally believed to be a prerequisite for accommodating Dzyaloshinskii-Moriya interaction (DMI) and for stabilizing chiral spin textures. By contrast, we present an approach for engineering both the sign and amplitude of DMI in relatively thick films without involving interfacial asymmetry, which is achieved through incorporating the composition gradient-induced bulk magnetic asymmetry (BMA) combined with strong spin-orbit coupling (SOC). The pivotal roles of BMA and SOC are theoretically examined based on the three-site Fert-Lévy model and the first principles calculations. Experimentally, both the sign and amplitude of DMI in films with controllable composition gradients along the growth direction, in the presence/absence of SOC are studied by using a Brillouin light scattering spectroscopy. Our results suggest that the appreciable value of DMI (±0.15 mJ/m2) could be established through combining BMA and SOC into relatively thick films. It is expected that our findings may help to further understand chiral magnetism and to design novel non-collinear spin textures.

Keywords: Dzyaloshinskii-Moriya interaction; Brillouin light scattering; spin-wave non-reciprocity; bulk magnetic asymmetry; spin-orbit coupling

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Publ.-Id: 34283


Electron-ion temperature relaxation in warm dense hydrogen observed with picosecond resolved X-ray scattering

Fletcher, L. B.; Vorberger, J.; Schumaker, W.; Ruyer, C.; Goede, S.; Galtier, E.; Zastrau, U.; Alves, E. P.; Baalrud, S. D.; Baggott, R. A.; Barbrel, B.; Chen, Z.; Döppner, T.; Gauthier, M.; Granados, E.; Kim, J. B.; Kraus, D.; Lee, H. J.; Macdonald, M. J.; Mishra, R.; Pelka, A.; Ravasio, A.; Roedel, C.; Fry, A. R.; Redmer, R.; Fiuza, F.; Gericke, D. O.; Glenzer, S. H.

Angularly resolved X-ray scattering measurements from fs-laser heated hydrogen have been
used to determine the equilibration of electron and ion temperatures in the warm dense matter
regime. The relaxation of rapidly heated cryogenic hydrogen is visualized using 5.5 keV X-ray
pulses from the Linac Coherent Light (LCLS) source in a 1 Hz repetition rate pump-probe setting.
We demonstrate that the electron-ion energy transfer is faster than quasi-classical Landau-Spitzer
models that use ad hoc cutoffs in the Coulomb logarithm.

Keywords: warm dense matter; x-ray scattering; relaxation; femtosecond; hydrogen jet

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Permalink: https://www.hzdr.de/publications/Publ-34282
Publ.-Id: 34282


Quantitative assessment of radionuclide production yields in in-beam1 and offline PET measurements at different proton irradiation facilities

Bauer, J.; Hildebrandt, M.; Baumgartl, M.; Fiedler, F.; Robert, C.; Buvat, I.; Enghardt, W.; Parodi, K.

Objective: Reliable radionuclide production-yield data are a prerequisite for positron-emission-1
tomography (PET) based in-vivo proton treatment verification. In this context, activation data acquired2
at two different treatment facilities with different imaging systems were analyzed to provide3
experimentally determined radionuclide yields in thick targets and were compared with each other to4
investigate the impact of the respective imaging technique.5
Approach: Homogeneous thick targets (PMMA, gelatine, and graphite) were irradiated with mono-6
energetic proton pencil-beams at two distinct energies. Material activation was measured (i) in-beam7
during and after beam delivery with a double-head prototype PET camera and (ii) offline shortly after8
beam delivery with a commercial full-ring PET/CT scanner. Integral as well as depth-resolved +-9
emitter yields were determined for the dominant positron-emitting radionuclides 11C, 15O, 13N and (in-10
beam only) 10C. In-beam data were used to investigate the qualitative impact of different monitoring11
time schemes on activity depth profiles and their quantitative impact on count rates and total activity.12
Main results: Production yields measured with the in-beam camera were comparable to or higher13
compared to respective offline results. Depth profiles of radionuclide-specific yields obtained from the14
double-head camera showed qualitative differences to data acquired with the full-ring camera with a15
more convex profile shape. Considerable impact of the imaging timing scheme on the activity profile16
was observed for gelatine only with a range variation of up to 3.5 mm. Evaluation of the coincidence17
rate and the total number of observed events in the considered workflows confirmed a strongly18
decreasing rate in targets with a large oxygen fraction.19
Significance: The observed quantitative and qualitative differences between the datasets underline20
the importance of a thorough system commissioning. Due to the lack of reliable cross-section data, in-21
house phantom measurements are still considered a gold standard for careful characterization of the22
system response and to ensure a reliable beam range verification

Keywords: offline PET; positron emitter production yield; in-beam PET; particle therapy; in-vivo range verification

Permalink: https://www.hzdr.de/publications/Publ-34281
Publ.-Id: 34281


Scale dependent anisotropy & intermittency in bubble laden turbulent flows

Ma, T.; Hessenkemper, H.; Lucas, D.; Ott, B.; Fröhlich, J.; Bragg, A.

-- Anisotropy
DNS data of disperse bubbly flows in a vertical channel are used to study scale-dependent anisotropy for flows dominated by bubble-induced turbulence. We developed a new method, based on an extension of the barycentric map approach, that allows to quantify and visualize the anisotropy and componentiality of the flow at any scale. Using this we found that the bubbles significantly enhance anisotropy in the flow at all scales compared with the unladen case, and that for some bubble cases, very strong anisotropy persists down to the smallest scales of the flow. The strongest anisotropy observed was for the cases involving small bubbles.

-- intermittency
We experimentally explore the properties of bubble-laden turbulent flow at different scales, considering how the bubbles effect the extreme events of the flow. To this end, high-resolution Particle Shadow Velocimetry measurements are carried out in a bubble column in which the flow generated by a homogeneous distributed bubble swarm rising in water for two different bubble diameters (2.7 mm & 3.9 mm) and moderate gas volume fractions (0.26% - 1.31%). We considered the intermittency quantified by the normalized probability density functions of the longitudinal velocity increments. The results reveal that extreme values in the velocity increments become more probable with decreasing Reynolds number, the opposite of the behavior in single-phase turbulence. We visualize those extreme events and find that regions of intense small-scale velocity increments occur near the turbulent/non-turbulent interface at the boundary of the bubble wake.

Keywords: Bubbly flow; Turbulence

  • Invited lecture (Conferences)
    Special Seminar at Johns Hopkins University Center for Environmental & Applied Fluid Mechanics, 23.02.2022, Baltimore, USA

Permalink: https://www.hzdr.de/publications/Publ-34280
Publ.-Id: 34280


Experimental activation determination in and on components of nuclear power plants and comparison with activity calculations

Barkleit, A.; Rachamin, R.; Yassin, G.; Pönitz, E.; Konheiser, J.

Due to the “German Energiewende”, all nuclear power plants (NPPs) in Germany will have been shut down by the end of 2022. Consequently, a safe, economical, and efficient dismantling of the NPPs will be an important challenge for the next decades. This includes to progress with methods for optimal planning and implementation of decommissioning.
Several studies have been conducted to develop a standardized method for evaluating the specific and temporal progression of the activation in the reactor components, near-reactor concrete, and construction elements based on the reactor's power history. This will serve as an early non-destructive tool for the radiological characterization of the NPP's components. Such essential knowledge can significantly minimize the radioactive waste and the radiation exposure of the operating personnel during the NPP's decommissioning.
The studies considered two strategies. In the first one, the radionuclide inventory in the material of an NPP already under dismantling was investigated. Among others, Co-60 and C-14 in steel samples from the reactor pressure vessel and Eu-152 and Ba-133 in concrete drill cores from biological shielding were determined. In the second strategy, the neutron flux in NPPs still under operation was determined with activation monitors (small metal foils, e.g., In, Sn, Zn). The experimental data from both strategies were compared with results from Monte-Carlo simulations.
This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant numbers 15S9412 (WERREBA) and 15S9409A (EMPRADO) and is carried out in cooperation with PreussenElektra GmbH and EWN Greifswald GmbH.

  • Contribution to proceedings
    19th Radiochemical Conference RadChem, 15.-20.05.2022, Marianske Lazne, Czech Republic
  • Lecture (Conference)
    19th Radiochemical Conference RadChem, 15.-20.05.2022, Marianske Lazne, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-34279
Publ.-Id: 34279


Speciation and transfer of radionuclides in the human organism especially taking into account decorporation agents (RADEKOR) – a joint project

Barkleit, A.; Heller, A.; Walther, C.; Walther, D.; Raskob, W.

In case radionuclides (RN) enter the food chain and are incorporated by humans, they pose a possible health risk due to their radio- and chemotoxicity. To precisely assess the health risk after oral incorporation of RN with food and beverages and to apply effective decontamination methods, it is mandatory to understand the processes of RN biokinetics on both cellular and molecular scale. Within the joint research project “Speciation and transfer of radionuclides in the human organism especially taking into account decorporation agents (RADEKOR)”, quantitative excretion analysis and biokinetic modeling of orally incorporated RN are performed. Additionally, these macroscopic investigations are combined with molecular speciation studies of RN in artificial fluids of the alimentary tract of humans and cytotoxicity studies with respective human and rat cell lines both in the absence and presence of decorporation agents. Aim of the project is to expand the knowledge of processes underlying RN interactions within the human alimentary tract on a cellular and molecular scale to establish a precise biokinetic model as well as to contribute to the development and improvement of nuclide specific decontamination methods.
This joint project is funded by the German Federal Ministry of Education and Research (grant number 02NUK057). The funding period is from July 2020 to December 2023 and cooperation partners are: Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Technische Universität Dresden (TUD), Leibniz-Universität Hannover (LUH), VKTA - Radiation Protection, Analytics & Disposal (VKTA), and Karlsruhe Institute of Technology (KIT).

  • Contribution to proceedings
    19th Radiochemical Conference RadChem, 15.-20.05.2022, Marianske Lazne, Czech Republic
  • Poster
    19th Radiochemical Conference RadChem, 15.-20.05.2022, Marianske Lazne, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-34278
Publ.-Id: 34278


Strained Ammonium Precursors for Radiofluorinations

Reissig, F.; Mamat, C.

The increasing application of positron emission tomography (PET) in nuclear medicine has stimulated the extensive development of a multitude of novel and versatile techniques to introduce fluorine-18 especially for the radiolabelling of biologically or pharmacology active molecules. Taking into consideration that the introduction of fluorine-18 (t1/2 = 109.8 min) mostly proceeds under harsh conditions, radiolabelling of such molecules represents a challenge and is of enormous interest. Ideally, it should proceed in a regioselective manner under mild physiological conditions, in an acceptable time span, with high yields and high specific activities. Special attention has been drawn to 2-fluoroethyl and 3-fluoropropyl groups, respectively, which are often the active site of radiofluorinated compounds. Precursors containing an ammonium leaving group which consists of a strained azetidinium or aziridinium moiety can help to overcome these obstacles leading to a mild introduction of [18F]fluoride with high radiochemical yields.

Keywords: strained rings; ring opening; aziridines; azetidinium; fluorination

Permalink: https://www.hzdr.de/publications/Publ-34277
Publ.-Id: 34277


CeO2-azacrown conjugate as a nanoplatform for combined radiopharmaceuticals

Khabirova, S. Y.; Aleshin, G. Y.; Plakhova, T. V.; Zubenko, A. D.; Shchukina, A. A.; Fedorova, O. A.; Averin, A. A.; Belova, E. V.; Bazarkina, E. F.; Kvashnina, K. O.; Kalmykov, S. N.

This communication is one of the first attempts to assess CeO2 nanoparticles as a nanoplatform for radiopharmaceuticals with radionuclides. The process of functionalization using a bifunctional azacrown ligand is described, and the resulting conjugates are characterized by IR and Raman spectroscopy. Their complexes with 207Bi show a high stability in medically relevant media, thus encouraging the further study of these conjugates in vivo as potential combined radiopharmaceuticals

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Permalink: https://www.hzdr.de/publications/Publ-34276
Publ.-Id: 34276


Data publication: Effects of gravity modulation on the dynamics of a radial A + B → C reaction front

Stergiou, Y.; Hauser, M. J. B.; Comolli, A.; Brau, F.; de Wit, A.; Schuszter, G.; Papp, P.; Horvath, D.; Roux, C.; Pimienta, V.; Eckert, K.; Schwarzenberger, K.

Raw image data of the reaction-diffusion-advection front experiments in radial Hele-Shaw cells. Including experiments in ground 1-g conditions and parabolic flight experiments.

Keywords: Reaction-diffusion-advection; reaction front; microgravity; convection; radial Hele-Shaw; parabolic flight

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Permalink: https://www.hzdr.de/publications/Publ-34275
Publ.-Id: 34275


Cr2+ solid solution in UO2 evidenced by advanced spectroscopy

Smith, H.; Townsend, L. T.; Mohun, R.; Cordara, T.; Stennett, M.; Mosselmans, F.; Kvashnina, K.; Hyatt, N.; Corkhill, C.

Advanced Cr-doped UO2 fuels are essential for driving safe and efficient generation of nuclear energy. Although widely deployed, little is known about their fundamental chemistry, which is a critical gap for development of new fuel materials and radioactive waste management strategies. Utilising an original approach, we directly evidence the chemistry of Cr(3+)2O3–doped U(4+)O2. Advanced high-flux, high-spectral purity X-ray absorption spectroscopy (XAS), corroborated by diffraction, Raman spectroscopy and high energy resolved fluorescence detection-XAS, is used to establish that Cr2+ directly substitutes for U4+, accompanied by U5+ and oxygen vacancy charge compensation. Extension of the analysis to heat-treated simulant nuclear fuel reveals a mixed Cr2+/3+ oxidation state, with Cr in more than one physical form, explaining the substantial discrepancies that exist in the literature. Successful demonstration of this analytical advance, and the scientific underpinning it provides, opens opportunities for an expansion in the range of dopants utilised in advanced UO2 fuels.

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Permalink: https://www.hzdr.de/publications/Publ-34274
Publ.-Id: 34274


High surface area “3D Graphene Oxide” for enhanced sorption of radionuclides

Boulanger, N.; Kuzenkova, A. S.; Iakunkov, A.; Nordenström, A.; Romanchuk, A. Y.; Trigub, A. L.; Zasimov, P. V.; Podana, M.; Enachescu, M.; Bauters, S.; Amidani, L.; Kvashnina, K. O.; Kalmykov, S. N.; Talyzin, A. V.

Earlier studies demonstrated that graphene oxide (GO)
with large number of defects is favorable for the sorption of
radionuclides. Here we report oxidation treatment which converts high
surface area activated reduced graphene oxide (arGO) into a 3D
analogue of defect-rich GO (dGO). Oxidation of arGO using
ammonium persulfate results in oxidation corresponding to carbon to
oxygen ratio C/O=3.3, similar to the oxidation state of graphene oxide
while preserving high BET surface area of about 880 m2/g. Analysis
of surface oxidized arGO shows high abundance of oxygen functional
groups very similar to dGO and hydrophilic properties. The “3D
graphene oxide” showed high sorption capacity for U(VI) removal in
an extraordinary broad interval of pH. Notably, the surface oxidized
carbon material has a rigid 3D structure with micropores accessible
for penetration of radionuclide ions. Therefore, the bulk “3D GO” can
be used as a sorbent directly without dispersing, the step required for
GO to make its surface area accessible for pollutants

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Permalink: https://www.hzdr.de/publications/Publ-34273
Publ.-Id: 34273


Data publication: MOFs with 12-coordinate 5f-block metal centers

Lv, K.; Urbank, C.; Patzschke, M.; März, J.; Kaden, P.; Weiß, S.; Schmidt, M.

Autoluminescence CO2 BET Elemental analysis Leaching test results Powder XRD TGA-DSC UV/vis

Keywords: Actinides; Metal-Organic Frameworks; Autoluminescence; Semiconductor

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Permalink: https://www.hzdr.de/publications/Publ-34272
Publ.-Id: 34272


A study on the wettability of metal oxides as cathode active materials to improve lithium-ion battery recycling

Sandbrink, J.; Vanderbruggen, A.; Rudolph, M.

One of the main tasks for today’s researchers in order to ensure the supply of critical raw materials is the efficient recovery and recycling of secondary resources. Lithium-ion batteries (LIB) are the key technology to electrify transport, which is one of the multiple measures proposed to prevent global warming. Therefore, the recycling of spent LIBs is of great interest and unvoidable. A major challenge in spent LIBs recycling, is the beneficiation of fine powder resulting from the battery crushing, so-called “black mass”, which contains the valuable lithium metal oxides (from the cathode) and the critical graphite (from the anode). One promising way to separate the graphitic material from the lithium metal oxides is through froth flotation, which separates the particles according to their differences in wettability.
In order to improve the separation process, one must first have a proper understanding of the particle properties. In particular, the lithium metal oxides are rather declared as hydrophilic and should therefore be easily separated from the hydrophobic graphite. Nevertheless, many studies report on their recovery into the froth product, along with the graphite, thus lowering its grade, which is most probably due to the residual hydrophobic binder that causes a change in their wettability.
In this study, different battery materials, including fresh lithium metal oxides and graphite, as well as real spent materials from LIBs were used. The particles were analysed for their wettability and wetting ability using optical contour analysis, inverse gas chromatography, particle attachment to bubbles, analytical particle solvent extraction as well as the Washburn method. These results are set into context with flotation tests and shed light on the particle wettability and its effect on the flotation separation efficiency, as well as the difficulties that arise when it comes to the recycling of spent LIBs.

Keywords: Flotation; lithium-ion batteries; wettability; recycling

  • Lecture (Conference) (Online presentation)
    Jahrestreffen der ProcessNet-Fachgruppen Grenzflächenbestimmte Systeme und Prozesse, Partikelmesstechnik sowie Aerosoltechnik, 16.-17.02.2022, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-34271
Publ.-Id: 34271


Sustainable Bioengineering of Gold Structured Wide-Area Supported Catalysts for Hand-Recyclable Ultra-Efficient Heterogeneous Catalysis

Bhatt, C. S.; Parimi, D. S.; Bollu, T. K.; Madhura, H. U.; Jacob, N.; Korivi, R.; Ponugoti, S. S.; Mannathan, S.; Ojha, S.; Klingner, N.; Motapothula, M.; Suresh, A. K.

Metal nanoparticles grafted within inert and porous wide-area supports are emerging as recyclable, sustainable catalysts for modern industry applications. Here, we develop gold nanoparticle-anchored supported catalysts by utilizing the natural metal binding and reductive potential of natural eggshell. Variable hand-recyclable wide-area catalysts between ~(80±7) and (0.5±0.1) cm2 are generated by varying the support dimensions. The catalyst possesses high-porosity (17.1 Å) and stability against high-temperatures (300°C), polar and non-polar solvents, electrolytes, acids and bases, facilitating compatible ultra-efficient catalysis. As validated by large-volume (2.8 liters) sewage-dye detoxification, gram-scale hydrogenation of nitroarenes and synthesis of propargylamine. Moreover, persistent-recyclability, monitoring of reaction kinetics and product intermediates are possible due to retrievability and interchangeability of the catalyst. Finally, the bio-nature of support permits ~76.9% recovery of noble gold simply by immersing in royal solution. Our naturally-created, low-cost, scalable, hand-recyclable and resilient supported mega-catalyst dwarfs most challenges for large-scale metal-based heterogeneous catalysis.

Keywords: supported-catalyst; sustainable; hand-recyclable; gram-scale; large-volume; dye-detoxification; sewa

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Permalink: https://www.hzdr.de/publications/Publ-34270
Publ.-Id: 34270


Perspective paper about the joint EANM/SNMMI/ESTRO practice recommendations for the use of 2-[18F]FDG-PET/CT external beam radiation treatment planning in lung cancer

Vaz, S.; Adam, J.; Bolton Delgado, R.; Vera, P.; van Elmpt, W.; Herrmann, K.; Hicks, R.; Lievens, Y.; Santos, A.; Schöder, H.; Dubray, B.; Visvikis, D.; Troost, E. G. C.; de Geus-Oei, L.

In ‘‘Joint EANM/SNMMI/ESTRO Practice Recommendations for the Use of 2-[18F]FDG-PET/CT External Beam Radiation Treatment Planning in Lung Cancer V1.0” clinical indications for PET-CT in (non-)small cell lung cancer are highlighted and selective nodal irradiation is discussed. Additionally, concepts about target definition, target delineation and treatment evaluation are reviewed.

Permalink: https://www.hzdr.de/publications/Publ-34269
Publ.-Id: 34269


Spinning Particles in Quantum Mechanics and Quantum Field Theory

Corradini, O.; Schubert, C.; Edwards, J. P.; Ahmadiniaz, N.

These are notes of lectures on spinning particles and the worldline formalism originally given by Olindo Corradini and Christian Schubert at the School on spinning Particles in Quantum Field Theory: Worldline Formalism, HigherSpins, and Conformal Geometry, held at Morelia, Mexico, from November 19 through November 23, 2012. The lectures were addressed to graduate-level students with a background in relativistic quantum mechanics and at least a rudimentary knowledge of field theory. They have since been up-dated to include a further set of lecture notes on tree level processes from a worldline perspective based on a mini-course by James P. Edwards at the Instituto de Fisica y Matematicas in Morelia, Mexico given to graduatesand visiting professors during July 2017 and in various later classes, com-plemented by a series of three lectures titled New techniques for amplitude calculation in QED given by Naser Ahmadiniaz at the Center for Relativistic Laser Science (CoReLS), Institute for Basic Science (IBS), November 2015, Gwangju, South Korea and as an invited lecturer at the Helmholtz International Summer School (HISS) - Dubna International Advanced School of Theoretical Physics (DIAS-TH): “Quantum Field Theory at the Limits: from strong Fields to Heavy Quarks”, July-August 2019, Dubna, Russia. These additional notes complete the picture of first quantised techniques and bring the worldline description up to date.

Keywords: Worldline formalism; loop-level processes; Tree-level processes

  • Open Access Logo Invited lecture (Conferences)
    Quantum Field Theory at the Limits: from Strong Fields to Heavy Quarks, 22.07.-02.08.2019, Dubna, Russia

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Permalink: https://www.hzdr.de/publications/Publ-34268
Publ.-Id: 34268


Breakup with benefits - hydrothermal mineral systems related to the disintegration of a supercontinent

Burisch, M.; Markl, G.; Gutzmer, J.

Mesozoic hydrothermal systems host the majority of Europe's fluorspar and barite resources as well as significant amounts
of metals such as Ag, Co, Zn, Pb, Ni and Cu. Their genetic link to extensional tectonics in conjunction with the opening of
the North Atlantic has long been suspected, but their spatial and temporal relation to the tectonic evolution of Europe has
remained enigmatic. A thorough evaluation of available geochronological data for fluorite-barite-Pb-Zn, native-metalarsenide-
carbonate and MVT-type mineralization in Continental Europe and North Africa reveals a distinct, as yet
unrecognized, time-space relationship between the distribution of hydrothermal mineral systems and the tectonic evolution
of the Tethys-Atlantic-Caribbean rift system. The observed time-space relationship and ore-forming mechanisms are
evaluated to constrain the underlying driving force for hydrothermal mineralization in the context of the geodynamic evolution
of the European lithosphere. Based on this assessment we propose the first continental-scale model for the genesis of
Mesozoic hydrothermal ore deposits associated to the breakup of the supercontinent Pangea.

Keywords: continental rifting; critical raw materials; hydrothermal ore deposits; North Atlantic; Pangea supercontinent

Permalink: https://www.hzdr.de/publications/Publ-34267
Publ.-Id: 34267


Linking Diffraction Techniques with XRF and XAS Spectroscopy at the German CRG Beamline ROBL / ESRF

Hennig, C.; Svitlyk, V.

The recent upgrade of the Rossendorf Beamline at ESRF allows simultaneous collection of diffraction and spectroscopy (XRF and XANES). A 6-circle Huber diffractometer (XRD-1) with Eulerian cradle geometry is used for high-resolution powder diffraction and surface diffraction. The powder diffraction module uses an Eiger CdTe 500k detector, the surface diffraction module is equipped with a Pilatus Si 100k detector. PXRD data suitable for Rietveld refinement can be collected between 10 and 31 keV in an 2θ angular range of 0-65°. The Bragg reflexes in PXRD are extracted by radial integration using a modified pyFAI code. Diffraction measurements can be combined with XRF and XAS spectroscopy using a single-element Si drift detector (Vortex X90 CUBE, 1mm SDD, 25 mm Be window) with a FalconX1 processor.

The second diffractometer (XRD-2) consists of a heavy optical bench with an exchangeable goniometer and a Pilatus3 X 2M detector. It is used for single crystal diffraction and in situ or operando powder diffraction. Devices for non-ambient sample conditions are a hot-air blower (RT-1100K), a heating chamber (RT-1470K), and a LN2 cryostream (90-400K). This diffractometer is controlled with the Pylatus software. The single crystal data extraction is performed with CrysAlisPro. The Si drift detector can be placed in different positions to combine diffraction with XRF and XAS measurements.

Keywords: single-crystal diffraction ScXRD; high resolution powder diffraction HR-PXRD; in situ and perando applications

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  • Lecture (Conference) (Online presentation)
    30th Annual Meeting of the German Crystallographic Society, 14.-17.03.2022, Munich, Germany

Permalink: https://www.hzdr.de/publications/Publ-34265
Publ.-Id: 34265


“X-ray diffraction spectroscopy” – Refinement of dispersion correction parameters for XRD measurements of Mo(CO)6 at the Mo K-edge

Meurer, F.; Dolomanov, O. V.; Hennig, C.; Peyerimhoff, N.; Kleemiss, F.; Puschmann, H.; Bodensteiner, M.

Correcting for anomalous dispersion is part of any refinement of an X-ray
diffraction crystal structure determination. The procedure takes the inelastic
scattering in the diffraction experiment into account. This X-ray absorption effect
is specific to each chemical compound and is particularly sensitive to radiation
energies in the region of the absorption edges of the elements in the compound.
Therefore, the widely used tabulated values for these corrections can only be
approximations as they are based on calculations for isolated atoms. Features of
the unique spatial and electronic environment that are directly related to the
anomalous dispersion are ignored, although these can be observed spectroscopically.
This significantly affects the fit between the crystallographic model and
the measured intensities when the excitation wavelength in an X-ray diffraction
experiment is close to an element’s absorption edge. Herein, we report on
synchrotron multi-wavelength single-crystal X-ray diffraction, as well as X-ray
absorption spectroscopy experiments which we performed on the molecular
compound Mo(CO)6 at energies around the molybdenum K edge. The dispersive
(f 0) and absorptive (f 00) terms of the anomalous dispersion can be refined as
independent parameters in the full-matrix least-squares refinement. This procedure
has been implemented as a new feature in the well-established OLEX2 software
suite. These refined parameters are in good agreement with the independently
recorded X-ray absorption spectrum. The resulting crystallographic models show
significant improvement compared to those employing tabulated values.

Keywords: X-ray diffraction; anomalous dispersion; crystal structure determination

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Permalink: https://www.hzdr.de/publications/Publ-34263
Publ.-Id: 34263


Improved ⁴¹Ca AMS measurements at DREAMS

Vivo Vilches, C.; Rugel, G.; Lachner, J.; Wallner, A.; Koll, D.; Stübner, K.; Fichter, S.; Winkler, S.

Sensitivity of ⁴¹Ca measurements at the 6 MV AMS system at HZDR, DREAMS, using calcium fluoride (CaF₂) targets, is mainly limited by 2 factors: the total efficiency of the measurements; and the fraction of ions of its isobar ⁴¹K which mimic the signal of ⁴¹Ca in the gas ionization chamber detector.
The addition of lead fluoride (PbF₂) to the target mixture has been proven to boost the production of different (MFₙ)- ions. At DREAMS, changing the previously used mixture of CaF₂+Ag (1:4 w/w) by CaF₂+Ag+PbF₂ (1:4:4 w/w), ionization efficiency is increased from ∼0.15% to ∼0.45%.
The ⁴¹K suppression by the detector can also be improved, even without changes in the instrumentation itself. With an optimized analysis of the 4-dimensional signals from the gas ionization chamber detector, the suppression factor can be increased, at least, a factor 2: from 2 × 10⁴ to 4 × 10⁴.
The reported changes improve the total efficiency of ⁴¹Ca detection as well as the suppression of the ⁴¹K isobar and lead to a ⁴¹Ca/⁴⁰Ca sensitivity of 2-3 × 10⁻¹⁵ with an overall efficiency of ∼0.03%.

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  • Lecture (Conference) (Online presentation)
    85th Annual Conference of the DPG and DPG Spring Meeting, 14.-18.03.2022, Erlagen, Germany

Permalink: https://www.hzdr.de/publications/Publ-34262
Publ.-Id: 34262


Evaluation of [18F]LU14 and [18F]LU13 in a rat model with a local overexpression of the human cannabinoid receptor 2 in the brain with PET

Gündel, D.; Deuther-Conrad, W.; Ueberham, L.; Teodoro, R.; Bormans, G.; Toussaint, M.; Kopka, K.; Bachmann, M.; Brust, P.; Moldovan, R.-P.

Objectives: An upregulation of cannabinoid receptors type 2 (CB2) has been reported in association with inflammation processes, traumatic brain injury, neurodegeneration and cancer.[1] The activation of CB2 leads to an anti-inflammatory action. Therefore, the non-invasive assessment of the CB2 availability with PET could improve the decision-making for CB2-directed therapies. We developed a series of fluorinated naphthyridine-2-one-carboxamides as CB2 ligands, of which [18F]LU14[2] and [18F]LU13 were radiosynthesized and biologically evaluated.
Methods: The two radioligands [18F]LU14[2] and [18F]LU13 were developed starting from appropriate precursor compounds.The fraction of radiometabolites was quantified in isolated plasma and brain samples at 30 min p.i. The CB2 binding affinities selectivities (expressed and determined from KD and Ki values of both radioligands were determined in vitro. PET studies were performed to evaluate the radioligand uptake into the brains of rats overexpressing the hCB2(D80N) in the right striatum[3].
Results: Favourable properties where achieved for [18F]LU14, which could be further improved for [18F]LU13 (AM, affinity, selectivity and metabolic stability). In rats bearing the local overexpression of the hCB2 a target-specific and reversible uptake for both radioligands was demonstrated. [18F]LU14 reached a TAC peak SUV of 3.3 ± 0.6 at 7.4 ± 2.8 min p.i., and the SUVr (target region–to–cerebellum) was stable between 6.6 and 7.0 after 30 min p.i. For [18F]LU13 a stable SUV of 3.6 ± 0.9 after 26 min p.i. was reached and a close to linearly increasing SUVr (target region–to–cerebellum) up to 8.8 ± 4.3 at 60 min p.i. was determined (slope = 0.15 SUV/min; R² =.0.8).
Conclusion: [18F]LU14 and [18F]LU13 showed an excellent ability to image the CB2 receptors in vivo. Additionally, [18F]LU14 revealed a faster washout from the non-target regions in the brain, compared to [18F]LU13.
References: [1] Stasiulewicz et al. IJMS, 2020, 21, 2778; [2] Teodoro et al. IJMS, 2021, 22, 15; [3] Attili et al. BJP, 2019, 176, 1481

Keywords: cannabinoid receptor 2; PET; brain; [18F]LU13; [18F]LU14[2]; CB2

  • Lecture (Conference)
    Turku PET Symposium 2022, 03.-06.06.2022, Turku, Finland

Permalink: https://www.hzdr.de/publications/Publ-34261
Publ.-Id: 34261


Effects of gravity modulation on the dynamics of a radial A + B → C reaction front

Stergiou, Y.; Hauser, M. J. B.; Comolli, A.; Brau, F.; de Wit, A.; Schuszter, G.; Papp, P.; Horvath, D.; Roux, C.; Pimienta, V.; Eckert, K.; Schwarzenberger, K.

The dynamics of radial A + B → C reaction fronts can be affected by buoyancy-driven convection. Motivated by recent advances in reaction-diffusion-advection (RDA) systems theory, we investigated experimentally a radial A + B → C RDA system under modulated gravity, using a Hele-Shaw cell setup onboard a parabolic flight. We evaluated characteristic properties of the RDA models, such as the temporal evolution of the total amount of product C, the width and position of the reaction front and compared them with theoretical predictions. During increased gravity, we observed an increase in the total amount of product C, formed and the front width, compared to the corresponding normal-gravity experiments, caused by the stronger buoyancy-driven convection in the former case. Finally, we report on experiments performed entirely in absence of gravity, eliminating buoyancy-driven convection. Despite the short observation time, comparison with ground experiments showed the effect of buoyant convection on radial RDA fronts, enhancing mixing and increasing product generation.

Keywords: Reaction-diffusion-advection; reaction front; microgravity; convection; radial Hele-Shaw; parabolic flight

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Permalink: https://www.hzdr.de/publications/Publ-34260
Publ.-Id: 34260


Beyond Active Colloids: From Functional Materials to Microscale Robotics

Simmchen, J.; Baraban, L.; Wang, W.

Guest editors Juliane Simmchen, Larysa Baraban, and Wei Wang introduce the topics covered in this special collection covering the synthesis, applications, and dynamics of active colloids.

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Permalink: https://www.hzdr.de/publications/Publ-34259
Publ.-Id: 34259


Development of explanatory movies for the delineation of new organs at risk in neuro-oncology

Di Perri, D.; Hofstede, D.; Postma, A.; Zegers, C.; In’T Ven, L.; Hoebers, F.; van Elmpt, W.; Verheesen, L.; Beurskens, H.; Troost, E. G. C.; Compter, I.; Eekers, D.

Ten new organs at risk (OARs) were recently introduced in the updated European Particle Therapy Network neurological contouring atlas. Despite the use of the illustrated atlas and descriptive text, interindividual contouring variations may persist. To further facilitate the contouring of these OARs, educational films were developed and published on www.cancerdata.org.

Keywords: atlas for neuro-oncology; brain; organs at risk; film; particle therapy; radiotherapy

Permalink: https://www.hzdr.de/publications/Publ-34258
Publ.-Id: 34258


A systematic review of clinical studies on proton Relative Biological Effectiveness (RBE)

Underwood, T.; McNamara, A.; Appelt, A.; Haviland, J.; Sørensen, B.; Troost, E. G. C.

Recently, a number of clinical studies have explored links between possible Relative Biological Effectiveness (RBE) elevations and patient toxicities and/or image changes following proton therapy. Our objective was to perform a systematic review of such studies. We applied a "Problem [RBE], Intervention [Protons], Population [Patients], Outcome [Side effect]” search strategy to the PubMed database. From our search, we retrieved studies which: (a) performed novel voxel-wise analyses of patient effects versus dose and LET (n= 13), and (b) compared image changes between proton and photon cohorts with regard to proton RBE (n=9). For each retrieved study, we extracted data regarding: primary tumour type; size of patient cohort; type of image change studied; image-registration method (deformable or rigid); LET calculation method, and statistical methodology. We compared and contrasted their methods in order to discuss the weight of clinical evidence for variable proton RBE. We concluded that clinical evidence for variable proton RBE remains statistically weak at present. Our principal recommendation is that proton centres and clinical trial teams collaborate to standardize follow-up protocols and statistical analysis methods, so that larger patient cohorts can ultimately be considered for RBE analyses.

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Permalink: https://www.hzdr.de/publications/Publ-34256
Publ.-Id: 34256


Optical study of RbV₃Sb₅: Multiple density-wave gaps and phonon anomalies

Wenzel, M.; Ortiz, B. R.; Wilson, S. D.; Dressel, M.; Tsirlin, A. A.; Uykur, E.

Temperature-dependent reflectivity studies on the non-magnetic kagome metal RbV₃Sb₅ in a broad energy range (50 cm$^{-1}$ - 20000 cm$^{-1}$, equivalent to 6 meV - 2.5 eV) down to 10 K are reported. Below T_CDW=102 K, the optical spectra demonstrate a prominent spectral-weight transfer from low to higher energies as the fingerprint of the charge-density wave (CDW) formation with the opening of a partial gap. A detailed analysis reveals two energy scales of, respectively, ~800 cm$^{-1}$ (100 meV) and 360 cm$^{-1}$ (45 meV), the latter appearing below 50 K only. Additionally, two modes at, respectively, 160 cm$^{-1}$ (20 meV) and 430 cm$^{-1}$ (53 meV) can be traced both above and below T_CDW. They show strong anomalies already above T_CDW with a further renormalization across the transition, suggesting the importance of the electron-phonon coupling in RbV₃Sb₅ in both normal and CDW states. While the 160 cm$^{-1}$mode can be attributed to the E_1u phonon, the 430 cm$^{-1}$ mode could not be reproduced in our phonon calculations. The antiresonance nature of this mode suggests a nontrivial electron-phonon coupling in RbV₃Sb₅. A distinct localization peak observed at all temperatures signals damped electron dynamics, whereas the reduced Drude spectral weight manifests moderate deviations from the band picture in RbV₃Sb₅.

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Permalink: https://www.hzdr.de/publications/Publ-34255
Publ.-Id: 34255


Amphiphilic Anionic Oligomer-Stabilized Calcium Phosphate Nanoparticles with Prospects in siRNA Delivery via Convection-Enhanced Delivery

Mitrach, F.; Schmid, M.; Toussaint, M.; Dukic-Stefanovic, S.; Deuther-Conrad, W.; Franke, H.; Ewe, A.; Aigner, A.; Wölk, C.; Brust, P.; Hacker, M. C.; Schulz-Siegmund, M.

Convection-enhanced delivery (CED) has been introduced as a concept in cancer treatment to generate high local concentrations of anticancer therapeutics and overcome the limited diffusional distribution, e.g., in the brain. RNA interference provides interesting therapeutic options to fight cancer cells but requires nanoparticulate (NP) carriers with a size below 100 nm as well as a low zeta potential for CED application. In this study, we investigated calcium phosphate NPs (CaP-NPs) as siRNA carriers for CED application. Since CaP-NPs tend to aggregate, we introduced a new terpolymer (o14PEGMA(1:1:2.5) NH3) for stabilization of CaP-NPs intended for delivery of siRNA to brain cancer cells. This small terpolymer provides PEG chains for steric stabilization, and a fat alcohol to improve interfacial activity, as well as maleic anhydrides that allow for both labeling and high affinity to Ca(II) in the hydrolyzed state. In a systematic approach, we varied the Ca/P ratio as well as the terpolymer concentration and successfully stabilized NPs with the desired properties. Labeling
of the terpolymer with the fluorescent dye Cy5 revealed the terpolymer’s high affinity to CaP. Importantly, we also determined a high efficiency of siRNA binding to the NPs that caused very effective survivin siRNA silencing in F98 rat brain cancer cells. Cytotoxicity investigations with a standard cell line resulted in minor and transient effects; no adverse effects were observed in organotypic brain slice cultures. However, more specific cytotoxicity investigations are required. This study provides a systematic and mechanistic analysis characterizing the effects of the first oligomer of a new class of stabilizers for siRNA-loaded CaP-NPs.

Keywords: Calcium phosphate nanoparticles; Cell transfection; Particle characterization; PEGylated terpolymer

Permalink: https://www.hzdr.de/publications/Publ-34254
Publ.-Id: 34254


Platinum-group elements in Late Quaternary high-Mg basalts of eastern Kamchatka: Evidence for minor cryptic sulfide fractionation in primitive arc magmas

Nekrylov, N.; Kamenetsky, V. S.; Savelyev, D. P.; Gorbach, N. V.; Kontonikas-Charos, A.; Palesskii, S. V.; Shcherbakov, V. D.; Kutyrev, A. V.; Savelyeva, O. L.; Korneeva, A. A.; Kozmenko, O. A.; Zelenski, M. E.

The geochemical variations of magmas across and along supra-subduction zones (SSZ) have been commonly attributed to profound changes in the phase and chemical compositions of the mantle source and subduction-derived melt and fluid fluxes, as well as the physical parameters (e.g. depth, temperature, oxygen fugacity etc) of slab dehydration, mineral breakdown and melting. Here we test the variability of the Late Quaternary primitive magmas in the southern and northern parts of the meridionally oriented Eastern Volcanic Belt (EVB) of Kamchatka, with a slab depth varying from 60 to 160 km. Eight high-Mg (Mg# > 60 mol%) basalts were characterized for major, trace and platinum-group element (PGE) abundances, as well as the compositions of olivine phenocrysts and olivine-hosted spinel inclusions. The basalts in our study are geochemically typical of SSZ magmas and contain similar liquidus assemblages of forsteritic olivine (Mg# 78–92 mol%), low-Ti Cr-spinel and clinopyroxene. Although the absolute abundances of major and trace elements, and their ratios, in the basalts fluctuate to some extent, the observed variability cannot be correlated with any of considered parameters in the geometry of the Kamchatka SSZ and conditions of melting. This unexpected result led to the evaluation of the platinumgroup element (PGE) systematics against the lithophile and chalcophile trace element geochemistry and the compositions of phenocrysts. Total whole-rock PGE content varies from 2.3 to 11.7 ppb, whereas the normalized PGE concentration patterns are typical for supra-subduction zones magmas and broadly similar in all studied samples. They are enriched in Rh, Pd and Pt relative to mid-ocean ridge basalts (MORB) and have nearly identical concentrations of Ir-group PGE. The only parameter that correlates well with PGE contents is the average Mg# of olivine phenocrysts from 84 to 90.3 mol%. This is interpreted to result from minor cryptic fractionation of sulfide melt, together with primitive olivine, in low-to-mid crustal conditions. Negative Ru anomalies on chondrite-normalized diagrams correspond to the Fe2+/Fe3+ ratios in spinel (a proxy for magma redox conditions), which reflects a replacement of monosulfide solid solution by laurite in the mantle wedge during oxidation.

Keywords: Kamchatka; Olivine; Laurite; PGE; Sulfide

Permalink: https://www.hzdr.de/publications/Publ-34252
Publ.-Id: 34252


Analysis of MRI and CT-based radiomics features for personalized treatment in locally advanced rectal cancer and external validation of published radiomics models

Shahzadi, I.; Zwanenburg, A.; Lattermann, A.; Linge, A.; Baldus, C.; Peeken, J.; Combs, S.; Diefenhardt, M.; Rödel, C.; Kirste, S.; Grosu, A.-L.; Baumann, M.; Krause, M.; Troost, E. G. C.; Löck, S.

Radiomics analyses commonly apply imaging features of different complexity for the prediction of the endpoint of interest. However, the prognostic value of each feature class is generally unclear. Furthermore, many radiomics models lack independent external validation that is decisive for their clinical application. Therefore, in this manuscript we present two complementary studies. In our modelling study, we developed and validated different radiomics signatures for outcome prediction after neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer (LARC) based on computed tomography (CT) and T2-weighted (T2w) magnetic resonance (MR) imaging datasets of 4 independent institutions (training: 122, validation 68 patients). We compared different feature classes extracted from the gross tumour volume for the prognosis of tumour response and freedom from distant metastases (FFDM): morphological and first order (MFO) features, second order texture (SOT) features, and Laplacian of Gaussian (LoG) transformed intensity features. Analyses were performed for CT and MRI separately and combined. Model performance was assessed by the area under the curve (AUC) and the concordance index (CI) for tumour response and FFDM, respectively. Overall, intensity features of LoG transformed CT and MR imaging combined with clinical T stage (cT) showed the best performance for tumour response prediction, while SOT features showed good performance for FFDM in independent validation (AUC = 0.70, CI = 0.69). In our external validation study, we aimed to validate previously published radiomics signatures on our multicentre cohort. We identified relevant publications on comparable patient datasets through a literature search and applied the reported radiomics models to our dataset. Only one of the identified studies could be validated, indicating an overall lack of reproducibility and the need of further standardization of radiomics before clinical application.

Permalink: https://www.hzdr.de/publications/Publ-34251
Publ.-Id: 34251


Uptake of Np(V) by zirconia: a combined batch, spectroscopic, and surface complexation modeling study

Jessat, I.; Roßberg, A.; Scheinost, A.; Lützenkirchen, J.; Foerstendorf, H.; Jordan, N.

The interactions of long-lived actinides, such as the transuranium element neptunium, with corrosion products in the near-field of a repository are important processes that have to be considered when assessing the safety of a nuclear waste repository. As a main corrosion product of the zircaloy cladding material of spent nuclear fuel rods, zirconia (ZrO₂) constitutes a first possible barrier against the release of radionuclides.
To gain a detailed understanding of the surface processes in the Np(V)−zirconia system, a comprehensive, multi-method approach was applied. The Np(V)−ZrO₂ system has been studied on the macroscopic level by conducting pH-dependent batch sorption experiments under varying conditions (ionic strength, Np(V) concentration, and solid-to-liquid ratio (m/V)). In addition, a Np(V) sorption isotherm at pH 6 was collected. The results revealed that Np(V) sorption onto ZrO₂ was affected by pH, Np(V) concentration, and solid-to-liquid ratio. Uptake of Np(V) increased with pH, starting around pH 3 with maximum sorption reached from pH 6. The shift of the sorption edge towards lower pH with increase of the m/V ratio points to the presence of different kinds of sorption sites. This is supported by the Np(V) sorption isotherm results, where the shape suggests strong and weak binding sites. Furthermore, Np(V) uptake was found to be independent of ionic strength and zeta potential measurements revealed a shift towards higher pH values of the isoelectric point of the neat ZrO₂ in the presence of Np(V). Hence, the formation of Np(V) inner-sphere surface complexes is indicated.
Molecular information about the surface species were obtained by Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) and in situ Infrared (IR) Spectroscopy, revealing the predominant formation of inner-sphere Np(V) surface complexes. A short Np−Zr distance derived from EXAFS suggests the presence of Np(V) bidentate inner-sphere complexes on the ZrO₂ surface.
These information obtained on a macroscopic and a molecular level can be used to restrict the number of surface species as well as their denticity in a surface complexation model. The thermodynamic surface complexation parameters of the Np(V)−zirconia system derived in this study will help to make more reliable predictions about the fate of Np(V) in the environment.

Keywords: neptunium(V); zirconia; ZrO₂; sorption; spectroscopy; EXAFS; IR

Related publications

  • Lecture (Conference)
    19th Radiochemical Conference (RadChem), 15.-20.05.2022, Mariánské Lázně (Marienbad), Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-34249
Publ.-Id: 34249


Crystal field effects in the zig-zag chain compound SrTm2O4

Kademane, A. B.; Quintero-Castro, D. L.; Siemensmeyer, K.; Salazar Mejia, C.; Gorbunov, D.; Stewart, J. R.; Luetkens, H.; Baines, C.; Li, H.

The single ion properties of the zig-zag chain compound SrTm2O4 have been investigated using heat capacity, magnetic susceptibility, magnetization, inelastic neutron scattering, and polarized muon spectroscopy. Two crystal field models are employed to estimate the single ion properties; a Density Function Theory based model and an effective charge model based on the Hutchings point charge model. The latter describes our experimental results well. This model estimates an easy-axis anisotropy for one of the Tm3+ sites and an easyplane anisotropy for the second site. It also predicts a mixed ground state with dominating 𝐽 = 0 characteristics for both sites. Additionally, muon spin rotation/relaxation (𝜇+SR) spectra reveal oscillations, typically a sign of long-range magnetic order. However, the temperature dependence of the precession frequency and the relaxation rates indicate that the system is in an extended critical regime and the observed relaxation is actually dynamic.

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Permalink: https://www.hzdr.de/publications/Publ-34248
Publ.-Id: 34248


Numerical Simulation of the Two-Phase Flow at a Single Trapezoid Fixed Valve Using a Hybrid CFD Approach

Wiedemann, P.; Kota, S. P.; Weckesser, S.; Schleicher, E.; Schubert, M.; Hampel, U.

In the present contribution, we demonstrate the application of a hybrid CFD approach, which allows for simulating dispersed phases as well as resolved interfaces within an Eulerian framework, for the flow on distillation trays for the first time. The morphology adaptive multi-field two-fluid model is exemplified for a generic tray setup with a single trapezoid fixed valve. Instead of fully resolving its geometry in the computational grid, we emulate the gas inlets by implementing local mass and momentum sources. Different source term implementations are tested and compared: continuous gas vs. dispersed gas sources and steady vs. dynamic sources. The simulation results are verified with experimental data from a lab-scale test rig with air-water flow. Local phase fractions were measured using a conductivity sensor array. The comparison of simulated and experimental results reveals that the relevant time-averaged and transient flow characteristics can be predicted satisfactorily when choosing proper source term implementations.

Keywords: fixed valve; morphology adaptive multi-field two-fluid model; local source terms; CFD

  • Contribution to proceedings
    12th international conference on Distillation & Absorption 2022, 18.-21.09.2022, Toulouse, France
  • Lecture (Conference)
    12th international conference on Distillation & Absorption 2022, 20.09.2022, Toulouse, France

Permalink: https://www.hzdr.de/publications/Publ-34247
Publ.-Id: 34247


On the agglomeration and breakage of particles in turbulent flows through pipe bends using CFD-PBE

Bilde, K. G.; Hærvig, J.; Lehnigk, R.; Schlegel, F.; Sørensen, K.

Particle agglomeration and breakage through pipe bends in turbulent flows are important for a wide range of industries and applications. A computational fluid dynamics (CFD) model is presented where the population balance equation (PBE) is applied to track the particle size distribution for a periodic turbulent pipe flow with 180◦ bends with a fluid Reynolds number in the range 15, 000 < Ref < 35, 000 and for three different pipe bend radii of rB = 1dh, rB = 1.5dh and rB = 2.5dh. The critical parameters in the Eulerian framework are analysed and suitable parameters are chosen to describe the agglomeration of soot-like particles suspended in water based on an experimentally obtained particle size distribution. The experimental particle size distribution of flocculated
soot particles was measured using a Malvern Mastersizer 3000 at the outlet of a static flocculator with a bend radius of rb = 1.5D. It is concluded that for the particle properties applied, the particle Sauter mean diameter converges to a constant value independent of the pipe bend radius when the fluid Reynolds number exceeds Ref = 30, 000. The agglomeration and breakage kernels for solid particles in a turbulent fluid flow are implemented in the open-source CFD library by the OpenFOAM Foundation.

Keywords: Multiphase flows; Population balance equation; Particle agglomeration; Particle breakage; Turbulence

Permalink: https://www.hzdr.de/publications/Publ-34246
Publ.-Id: 34246


Laboratory Investigation of Tomography-Controlled Continuous Steel Casting

Glavinic, I.; Muttakin, I.; Abouelazayem, S.; Blishchik, A.; Stefani, F.; Eckert, S.; Soleimani, M.; Saidani, I.; Hlava, J.; Kenjereš, S.; Wondrak, T.

More than 96% of steel in the world is produced via the method of continuous casting. The flow condition in the mould, where the initial solidification occurs, has a significant impact on the quality of steel products. It is important to have timely, and perhaps automated, control of the flow during casting. This work presents a new concept of using contactless inductive flow tomography (CIFT) as a sensor for a novel controller, which alters the strength of an electromagnetic brake (EMBr) of ruler type based on the reconstructed flow structure in the mould. The method was developed for the small-scale Liquid Metal Model for Continuous Casting (mini-LIMMCAST) facility available at the Helmholtz-Zentrum Dresden-Rossendorf. As an example of an undesired flow condition, clogging of the submerged entry nozzle (SEN) was modelled by partly closing one of the side ports of the SEN; in combination with an active EMBr, the jet penetrates deeper into the mould than when the EMBr is switched off. Corresponding flow patterns are detected by extracting the impingement position of the jets at the narrow faces of the mould from the CIFT reconstruction. The controller is designed to detect to undesired flow condition and switch off the EMBr. The temporal resolution of CIFT is 0.5 s.

Keywords: Contactless Inductive Flow Tomography; Continuous casting; Clogging; Flow control; EMBr; Inductive measurements; Mini-LIMMCAST

Related publications

Permalink: https://www.hzdr.de/publications/Publ-34245
Publ.-Id: 34245


Kaon and pion parton distributions

Cui, Z.-F.; Ding, M.; Gao, F.; Raya, K.; Binosi, D.; Chang, L.; Roberts, C. D.; Rodriguez-Quintero, J.; Schmidt, S. M.

Beginning with results for the leading-twist two-particle distribution amplitudes of π- and K-mesons, each of which exhibits dilation driven by the mechanism responsible for the emergence of hadronic mass, we develop parameter-free predictions for the pointwise behaviour of all π and K distribution functions (DFs), including glue and sea. The large-x behaviour of each DF meets expectations based on quantum chromodynamics; the valence-quark distributions match extractions from available data, including the pion case when threshold resummation effects are included; and at ζ5=5.2GeV, the scale of existing measurements, the light-front momentum of these hadrons is shared as follows: ⟨xvalence⟩π=0.41(4), ⟨xglue⟩π=0.45(2), ⟨xsea⟩π=0.14(2); and ⟨xvalence⟩K=0.42(3), ⟨xglue⟩K=0.44(2), ⟨xsea⟩K=0.14(2). The kaon’s glue and sea distributions are similar to those in the pion, although the inclusion of mass-dependent splitting functions introduces some differences on the valence-quark domain. This study should stimulate improved analyses of existing data and motivate new experiments sensitive to all π and K DFs. With little known empirically about the structure of the Standard Model’s (pseudo-) Nambu-Goldstone modes and analyses of existing, limited data being controversial, it is likely that new generation experiments at upgraded and anticipated facilities will provide the information needed to resolve the puzzles and complete the picture of these complex bound states.

Keywords: parton; Kaon

Permalink: https://www.hzdr.de/publications/Publ-34244
Publ.-Id: 34244


Towards attosecond imaging at the nanoscale using broadband holography-assisted coherent imaging in the extreme ultraviolet

Eschen, W.; Wang, S.; Liu, C.; Klas, R.; Steinert, M.; Yulin, S.; Meißner, H.; Bussmann, M.; Pertsch, T.; Limpert, J.; Rothhardt, J.

Nanoscale coherent imaging has emerged as an indispensable modality, allowing to surpass the resolution limit given by classical imaging optics. At the same time, attosecond science has experienced enormous progress and has revealed the ultrafast dynamics in complex materials. Combining attosecond temporal resolution of pump-probe experiments with nanometer spatial resolution would allow studying ultrafast dynamics on the smallest spatio-temporal scales but has not been demonstrated yet. To date, the large bandwidth of attosecond pulses poses a major challenge to high-resolution coherent imaging. Here, we present broadband holography-enhanced coherent imaging, which enables the combination of high-resolution coherent imaging with a large spectral bandwidth. By implementing our method at a high harmonic source, we demonstrate a spatial resolution of 34 nm in combination with a spectral bandwidth of 5.5 eV at a central photon energy of 92 eV. The method is single-shot capable and retrieves the spectrum from the measured diffraction pattern.

Permalink: https://www.hzdr.de/publications/Publ-34243
Publ.-Id: 34243


Reflections upon the Emergence of Hadronic Mass

Roberts, C. D.; Schmidt, S. M.

With discovery of the Higgs boson, science has located the source for ≲2% of the mass of visible matter. The focus of attention can now shift to the search for the origin of the remaining ≳98%. The instruments at work here must be capable of simultaneously generating the 1 GeV mass-scale associated with the nucleon and ensuring that this mass-scale is completely hidden in the chiral-limit pion. This hunt for an understanding of the emergence of hadronic mass (EHM) has actually been underway for many years. What is changing are the impacts of QCD-related theory, through the elucidation of clear signals for EHM in hadron observables, and the ability of modern and planned experimental facilities to access these observables. These developments are exemplified in a discussion of the evolving understanding of pion and kaon parton distributions.

Keywords: hadronic; Phenomenology; physics

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Permalink: https://www.hzdr.de/publications/Publ-34242
Publ.-Id: 34242


Nucleon elastic form factors at accessible large spacelike momenta

Schmidt, S. M.; Cui, Z.-F.; Roberts, C. D.; Chen, C.; Binosi, D.; de Soto, F.; Rodríguez-Quintero, J.; Segovia, J.

A Poincaré-covariant quark+diquark Faddeev equation is used to compute nucleon elastic form factors on 0≤Q2≤18m2N (mN is the nucleon mass) and elucidate their role as probes of emergent hadronic mass in the Standard Model. The calculations expose features of the form factors that can be tested in new generation experiments at existing facilities, e.g. a zero in GpE/GpM; a maximum in GnE/GnM; and a zero in the proton's d-quark Dirac form factor, Fd1. Additionally, examination of the associated light-front-transverse number and anomalous magnetisation densities reveals, inter alia: a marked excess of valence u-quarks in the neighbourhood of the proton's centre of transverse momentum; and that the valence d-quark is markedly more active magnetically than either of the valence u-quarks. The calculations and analysis also reveal other aspects of nucleon structure that could be tested with a high-luminosity accelerator capable of delivering higher beam energies than are currently available.

Keywords: nucleon; quark

Permalink: https://www.hzdr.de/publications/Publ-34241
Publ.-Id: 34241


Valence quark ratio in the proton

Cui, Z.-F.; Gao, F.; Binosi, D.; Chang, L.; Roberts, C. D.; Schmidt, S. M.

Beginning with precise data on the ratio of structure functions in deep inelastic scattering (DIS) from 3He and 3H, collected on the domain 0.19≤xB≤0.83, where xB is the Bjorken scaling variable, we employ a robust method for extrapolating such data to arrive at a model-independent result for the xB=1 value of the ratio of neutron and proton structure functions. Combining this with information obtained in analyses of DIS from nuclei, corrected for target-structure dependence, we arrive at a prediction for the proton's valence-quark ratio: dv/uv|xB→1=0.230(57). Requiring consistency with this result presents a challenge to many descriptions of proton structure.

Keywords: quark; proton; valence; ratio

Permalink: https://www.hzdr.de/publications/Publ-34240
Publ.-Id: 34240


Pauli Radius of the Proton

Cui, Z.-F.; Binosi, D.; Roberts, C. D.; Schmidt, S. M.

Using a procedure based on interpolation via continued fractions supplemented by statistical sampling, we analyze proton magnetic form factor data obtained via electron+proton scattering on Q2∈[0.027,0.55] GeV2 with the goal of determining the proton magnetic radius. The approach avoids assumptions about the function form used for data interpolation and ensuing extrapolation onto Q2≃0 for extraction of the form factor slope. In this way, we find Tm=0.817(27) fm. Regarding the difference between proton electric and magnetic radii calculated in this way, extant data are seen to be compatible with the possibility that the slopes of the proton Dirac and Pauli form factors, F1,2(Q2), are not truly independent observables; to wit, the difference F′1(0)−F′2(0)/κp=[1+κp]/[4m2p], viz., the proton Foldy term.

Keywords: pauli; radius; proton

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Permalink: https://www.hzdr.de/publications/Publ-34239
Publ.-Id: 34239


Pion charge radius from pion and electron elastic scattering data

Schmidt, S. M.; Cui, Z.-F.; Binosi, D.; Roberts, C. D.

With the aim of extracting the pion charge radius, we analyse extant precise pion+electron elastic scattering data on Q2∈[0.015,0.144]GeV2 using a method based on interpolation via continued fractions augmented by statistical sampling. The scheme avoids any assumptions on the form of function used for the representation of data and subsequent extrapolation onto Q2≃0. Combining results obtained from the two available data sets, we obtain rπ=0.640(7)fm, a value 2.4σ below today's commonly quoted average. The tension may be relieved by collection and similar analysis of new precise data that densely cover a domain which reaches well below Q2=0.015GeV2. Considering available kaon+electron elastic scattering data sets, our analysis reveals that they contain insufficient information to extract an objective result for the charged-kaon radius, rK. New data with much improved precision, low-Q2 reach and coverage are necessary before a sound result for rK can be recorded.

Keywords: pion; electron; scattering

Permalink: https://www.hzdr.de/publications/Publ-34238
Publ.-Id: 34238


Fresh Extraction of the Proton Charge Radius from Electron Scattering

Schmidt, S. M.; Cui, Z.-F.; Roberts, C. D.; Binosi, D.

We present a novel method for extracting the proton radius from elastic electron-proton (ep) scattering data. The approach is based on interpolation via continued fractions augmented by statistical sampling and avoids any assumptions on the form of function used for the representation of data and subsequent
extrapolation onto Q2 ≃ 0. Applying the method to extant modern ep datasets, we find that all results are mutually consistent and, combining them, we arrive at rp = 0.847(8) fm. This result compares favorably with values obtained from contemporary measurements of the Lamb shift in muonic hydrogen, transitions
in electronic hydrogen, and muonic deuterium spectroscopy.

Keywords: electron; scattering; proton

Permalink: https://www.hzdr.de/publications/Publ-34237
Publ.-Id: 34237


Prolificacy Assessment of Spermatozoan via State-of-the-Art Deep Learning Frameworks

Chandra, S.; Gourisaria, M. K.; Konar, D.; Gao, X.; Wang, T.; Min, X.; Gm, H.

Childlessness or infertility among couples has become a global health concern. Due to the rise in infertility, couples are looking for medical supports to attain reproduction. This paper deals with diagnosing infertility among men and the major factor in diagnosing infertility among men is the Sperm Morphology Analysis (SMA). In this manuscript, we explore establishing deep learning frameworks to automate the classification problem in the fertilization of sperm cells. We investigate the performance of multiple state-of-the-art deep neural networks on the MHSMA dataset. The experimental results demonstrate that the deep learning-based framework outperforms human experts on sperm classification in terms of accuracy, throughput and reliability. We further analyse the sperm cell data by visualizing the feature activations of the deep learning models, providing a new perspective to understand the data. Finally, a comprehensive analysis is also demonstrated on the experimental results obtained and attributing them to pertinent reasons.

Keywords: Sperm abnormality; deep learning; transfer learning

Permalink: https://www.hzdr.de/publications/Publ-34236
Publ.-Id: 34236


A correspondence between the free and interacting field theories

Gao, F.; Ding, M.; Liu, Y.; Schmidt, S. M.

We discover a correspondence between the free field and the interacting states. This correspondence is firstly given from the fact that the free propagator can be converted into a tower of propagators for massive states, when expanded with the Hermite function basis. The equivalence of propagators reveals that in this particular case the duality can naturally be regarded as the equivalence of one theory on the plane wave basis to the other on the Hermite function basis. More generally, the Hermite function basis provides an alternative quantization process with the creation/annihilation operators that correspond directly to the interacting fields. Moreover, the Hermite function basis defines an exact way of dimensional reduction. As an illustration, we apply this basis on 3+1 dimensional Yang-Mills theory with three dimensional space being reduced through the Hermite function basis, and if with only the lowest order Hermite function, the equivalent action becomes the Banks-Fischler-Shenker-Susskind (BFSS) matrix model.

Permalink: https://www.hzdr.de/publications/Publ-34235
Publ.-Id: 34235


Strahlenschutz im HZDR und im Institut für Radiopharmazeutische Krebsforschung

Wendler, M.

Vorstellung des Strahlenschutzes und der Strahlenschutzstruktur am HZDR. Es wird die Strahlenschutzpraxis im Institut für radiopharmazeutische Krebsforschung erläutert und aktuelle Projekte wie die Beantragung von Freigabewerten und das Alpha-Projekt aus Strahlenschutzsicht erläutert.

Keywords: Institut für radiopharmazeutische Krebsforschung; Radiation Protection; Betrieblicher Strahlenschutz

  • Lecture (others) (Online presentation)
    Sitzung des Arbeitskreis Praktischer Strahlenschutz im Fachverband Strahlenschutz, 17.03.2022, Deutsch, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34234
Publ.-Id: 34234


Quantum Zeno Manipulation of Quantum Dots

Ahmadiniaz, N.; Paul Geller, M.; König, J.; Kratzer, P.; Lorke, A.; Schaller, G.; Schützhold, R.

We investigate whether and how the quantum Zeno effect, i.e., the inhibition of quantum evolution by frequent measurements, can be employed to isolate a quantum dot from its surrounding electron reservoir. In contrast to the often studied case of tunneling between discrete levels, we consider the tunnelling of an electron from a continuum reservoir to a discrete level in the dot. Realizing the quantum Zeno effect in this scenario can be much harder because the measurements should be repeated before the wave packet of the hole left behind in the reservoir moves away from the vicinity of the dot. Thus, the required repetition rate could be lowered by having a flat band (with a slow group velocity) in resonance with the dot or a sufficiently small Fermi velocity or a strong external magnetic field.

Keywords: Quantum Zeno effect; quantum dots; wave packet decay; measurement problem; perturbation theory

Permalink: https://www.hzdr.de/publications/Publ-34233
Publ.-Id: 34233


Decay of quantum sensitivity due to three-body loss in Bose-Einstein condensates

Schützhold, R.; Rätzel, D.

In view of the coherent properties of a large number of atoms, Bose-Einstein condensates (BECs) have a high potential for sensing applications. Several proposals have been put forward to use collective excitations such as phonons in BECs for quantum-enhanced sensing in quantum metrology. However, the associated highly nonclassical states tend to be very vulnerable to decoherence. In this article, we investigate the effect of decoherence due to the omnipresent process of three-body loss in BECs.We find strong restrictions for a wide range of parameters, and we discuss possibilities to limit these restrictions.

Keywords: quantum; Bose-Einstein

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Permalink: https://www.hzdr.de/publications/Publ-34231
Publ.-Id: 34231


Technische Umsetzung von RDM Services: RODARE - InvenioRDM am HZDR

Knodel, O.; Fiedler, M.

The presentation highlights the research data repository of the HZDR RODARE.
In the first part Maik Fiedler gives an overview of the current use of the repository, shows features and statistics on the development and embeds the system in the publication economy of the HZDR.
In the second part the update upgrade from Rodare to an InvenioRDM-based RODARE-RDM is introduced with the technical background and conditions by Oliver Knodel. Furthermore, the concept for the integration of Rodare into the HELIPORT data management system HELIPORT is presented.

Keywords: Helmholtz Open Science Office; Research data; Research software; Data Management

  • Invited lecture (Conferences) (Online presentation)
    Praxisforum Forschungsdatenmanagement, 03.02.2022, Online, Deutschland
    DOI: 10.48440/os.helmholtz.044

Permalink: https://www.hzdr.de/publications/Publ-34230
Publ.-Id: 34230


Radiocarbon-dated evidence for Late Pleistocene and Holocene coastal change at Yzerfontein, Western Cape, South Africa

Woodborne, S.; Miller, D.; Evans, M.; Winkler, S.

We report radiocarbon dates obtained from on-shore marine and near-shore terrestrial deposits near Yzerfontein, on the West Coast of South Africa. These include Late Pleistocene shell concretions from the southern end of 16 Mile Beach and a marine shell deposit inland of the coastal Rooipan; mid-Holocene coastal pan deposits exposed by modern storm erosion of the sandy 16 Mile Beach; and four Holocene storm beach deposits on a rocky shore to the south. We interpret the results in terms of local geomorphology constraints on sea-level fluctuations. The eastern margin of Rooipan is a >40 ka elevated beach deposit in a dune cordon that separates it from the adjacent Yzerfonteinpan. Both pans have gypsum deposits up to 2 m thick formed by repeated marine overwash. Saline pan deposits that are exposed intermittently on the beach are mid-Holocene and indicate a former westward extension of Rooipan. This is in contrast to storm beaches dating 9 000–3 000 cal BP at higher elevations on a rocky platform further south. This suggests that a dune barrier existed seaward of the present shoreline near Rooipan at this time. The coastal changes described here show that deposition and erosion can be affected significantly by the local palaeo-geomorphology and cannot be ascribed solely to sea-level change.

Permalink: https://www.hzdr.de/publications/Publ-34229
Publ.-Id: 34229


Highlight selection of radiochemistry and radiopharmacy developments by editorial board

Bernardes, E.; Caravan, P.; van Dam, M.; Deuther-Conrad, W.; Ellis, B.; Furumoto, S.; Guillet, B.; Huang, Y.-Y.; Jia, H.; Laverman, P.; Li, Z.; Liu, Z.; Lodi, F.; Miao, Y.; Perk, L.; Schirrmacher, R.; Vercoullie, J.; Yang, H.; Yang, M.; Yang, X.; Zhang, J.; Zhang, M.-R.; Zhu, H.

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to update the readership on trends in the field of radiopharmaceutical development.
Results: This commentary of highlights has resulted in 23 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals and also a contribution in relation to MRI-agents is included.
Conclusion: Trends in (radio)chemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry.

Keywords: Radiopharmacy; Radiochemistry; Radiopharmaceuticals

Permalink: https://www.hzdr.de/publications/Publ-34228
Publ.-Id: 34228


Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.]