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41650 Publications

Data: Temperature Driven Transformation of the Flexible Metal-Organic Framework DUT-8(Ni)

Ehrling, S.; Senkovska, I.; Efimova, A.; Bon, V.; Abylgazina, L.; Petkov, P.; Evans, J. D.; Elsherif, A. G. A.; Thomas Wharmby, M.; Roslova, M.; Huang, Z.; Tanaka, H.; Wagner, A.; Schmidt, P.; Kaskel, S.

Abstract

These are the raw data of "Temperature Driven Transformation of the Flexible Metal-Organic Framework DUT-8(Ni)"  

DUT-8(Ni) metal-organic framework belongs to the family of flexible pillared layer materials. The desolvated framework can be obtained in the open pore form (op) or in the closed pore form (cp), depending on the crystal size regime. In the present work, we report on the behaviour of desolvated DUT-8(Ni) at elevated temperatures.
For both, op and cp variants, heating causes a structural transition, leading to an new, crystalline compound, containing two
interpenetrated networks. The state of the framework before transition (op vs. cp) influences the transition temperature: the small particles of the op phase transform at significantly lower temperature in comparison to the macroparticles of the cp phase, transforming close to the decomposition temperature. The new compound, confined closed pore phase (ccp), was characterized by powder X-ray diffraction and spectroscopic techniques, such as IR, EXAFS, and positron annihilation lifetime spectroscopy (PALS). Thermal effects of structural cp to ccp transitions were studied using differential scanning calorimetry (DSC), showing an overall exothermic effect of the process, involving bond breaking and reformation. Theoretical calculations reveal the energetics, driving the observed temperature induced phase transition.

Keywords: thermal response • interpenetrated MOF • thermal effect • phase transition • bond rearrangement

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Permalink: https://www.hzdr.de/publications/Publ-34595


The nature of π-hole interaction between iodide anion and quinoid ring in the crystalline state

Milašinović, V.; Vedran Vuković, V.; Krawczuk, A.; Krešimir Molčanov, K.; Hennig, C.; Bodensteiner, M.

Abstract

Abstract The investigated co-crystal of 3-chloro-N-methylpyridinium iodide with tetrabromoquinone (3−Cl−N−MePy∙I∙Br4Q) reveals a π-hole interaction between an iodide anion and a quinoid ring involving a n→π* charge transfer. The quinoid ring has a partial negative charge (estimated to be in the range of 0.08 to 0.11 e) and a partial radical character, which is related to black colour of the crystals (the crystals of neutral tetrabromoquinone are yellow). A detailed X-ray charge density study revealed two symmetry-independent bonding critical points between the iodide and carbon atoms of the ring. Their maximum electron density of 0.065 e Å−3 was reproduced by quantum chemical modelling. Energy of the interaction is estimated to be −11.16 kcal mol−1, which is comparable to the strength of moderate hydrogen bonding (about −10 kcal mol−1); it is dominantly of electrostatic nature, with a considerable dispersion component.

Keywords: π-hole interactions; charge transfer; quinone; charge density; atoms-in-molecule

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Permalink: https://www.hzdr.de/publications/Publ-34594


Real-time Image Stream Algorithms - RISA

Windisch, D.; Bieberle, A.

Abstract

Real-time image stream algorithms (RISA) is a high-throughput, low-latency image stream processing command-line application. Based on a configuration file, it will construct a processing pipeline of distinct processing steps and process a given image stream. Implementations of such processing steps are loaded from RISA-compatible shared libraries.

Keywords: Real-time; Image processing; Data processing; CUDA; C++

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  • Software in external data repository
    Publication year 2022
    Programming language: C++, CUDA
    System requirements: Linux-based operating system, CUDA-capable GPU
    License: Apache-2.0 (Link to license text)
    Hosted on https://gitlab.hzdr.de/risa/RISA: Link to location

Permalink: https://www.hzdr.de/publications/Publ-34593


Data: Fully encapsulated and stable black phosphorus field-effect transistors

Arora, H.; Fekri, Z.; Vekariya, Y. N.; Chava, P.; Watanabe, K.; Taniguchi, T.; Helm, M.; Erbe, A.

Abstract

Fabricated devices went through electrical characterization with 4200-SCS parameter analyzer located in greyroom and Agilent 4156C Parameter Analyzer equipped with a cool-down setup located in 613. The measured data was processed with origin software.

Keywords: two-dimensional semiconductors; black phosphorus; field-effect transistors; hexagonal boron nitride; encapsulation

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Permalink: https://www.hzdr.de/publications/Publ-34592


Expanding the Range: AuCu Metal Aerogels from H2O and EtOH

Georgi, M.; Kresse, J.; Hiekel, K.; Hübner, R.; Eychmüller, A.

Abstract

Due to their self-supporting and nanoparticulate structure, metal aerogels have emerged as excellent electrocatalysts, especially in the light of the shift to renewable energy cycles. While a large number of synthesis parameters have already been studied in depth, only superficial attention has been paid to the solvent. In order to investigate the influence of this parameter with respect to the gelation time, crystallinity, morphology, or porosity of metal gels, AuxCuy aerogels were prepared in water and ethanol. It was shown that although gelation in water leads to highly porous gels (60 m2g-1), a CuO phase forms during this process. The undesired oxide could be selectively removed using a post-washing step with formic acid. In contrast, the solvent change to EtOH led to a halving of the gelation time and the suppression of Cu oxidation. Thus, pure Cu aerogels were synthesized in addition to various bimetallic Au3X (X = Ni, Fe, Co) gels. The faster gelation, caused by the lower permittivity of EtOH, led to the formation of thicker gel strands, which resulted in a lower porosity of the AuxCuy aerogels. The advantage given by the solvent choice simplifies the preparation of metal aerogels and provides deeper knowledge about their gelation.

Keywords: metal; aerogel; gold; copper; ethanol; water; solvent; bimetallic; porous; one-step

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Permalink: https://www.hzdr.de/publications/Publ-34591


Bioleaching of metal(loid)s from sulfidic mine tailings and waste rock from the Neves Corvo mine, Portugal, by an acidophilic consortium

Opara, C. B.; Blannin, R.; Ebert, D.; Frenzel, M.; Pollmann, K.; Kutschke, S.

Abstract

Sulfidic mine waste usually contains elevated amounts of valuable and hazardous metal(loid)s, which may pose environmental risks but can also provide opportunities for resource recovery. Reprocessing of mine waste can offer both economic and environmental benefits by supplying some of the ever-growing global demand for valuable metals, as well as reducing environmental risks. The present study aimed to simultaneously recover both valuable and hazardous metal(loid)s from two sulfidic mine waste samples (waste rock (NC_01) and tailings (NC_02)) from the Neves Corvo mine, Portugal, using a novel acidophilic consortium dominated by iron-oxidizing Leptospirillum genus and Acidiphilium sp. Bioleaching results showed that over 70% of the total Zn, Co, In, As, and Cd contents of NC_01 and NC_02 were leached within 21 days, while 55% – 62% Mn was leached. Copper behaved in a refractory manner, as only 33% and 21% Cu were leached from NC_01 and NC_02, respectively. X-ray diffraction (XRD) and Scanning electron microscope-based automated image analyses (SEM/MLA-GXMAP) of the bioleached residues revealed an almost complete absence of residual pyrite in NC_01 and a reduction of pyrite in NC-02, as well as the formation of secondary minerals, especially jarosite. In most cases, the biogenic jarosite co-precipitated some of the leached elements again, e.g., Cu and Pb. In conclusion, a synchronized method for bioleaching valuable and hazardous metal(loid)s was developed using a novel acidophilic consortium, thereby demonstrating the potential for the generation of economic value and environmental risk reduction for sulfidic mine waste samples.

Keywords: Bioleaching; Acidophiles; Metal(loid)s; Minerals; Sulfidic tailings; Sulfidic waste rock; SEM/MLA-GXMAP; XRD

Permalink: https://www.hzdr.de/publications/Publ-34590


Identification of geochemical and biological processes controlling naturally occurring radionuclides (NOR) mobility to derive more robust solid/liquid distribution coefficients (Kd)

Arnold, T.; Bok, F.; Cazala, C.; Coppin, F.; Fevrier, L.; Katz, A.; Krawczyk-Bärsch, E.; Landesman, C.; Mangeret, A.; Marsal, F.; Merroun, M. L.; Montavon, G.; Nivesse, A.-L.; Pelkonen, M.; Pérez-Sánchez, D.; Rigol, A.; Sachs, S.; Skipperud, L.; Urso, L.; Veilly, E.; Vidal, M.

Abstract

Geochemical and biological processes controlling NOR mobility are studied within the RadoNorm project to derive more robust distribution coefficients Kd. To achieve this (i) the effect of microorganisms on NOR mobility in uranium (U) mine waters is studied, (ii) new datasets of NOR sorption and desorption parameters are acquired, (iii) a methodology for the determination of site-specific Kd values is evolved and (iv) models able to predict Kd (NOR) in relevant scenarios are developed.
The impact of microbes on the speciation of U in U mine waters is characterized by a multidisciplinary approach providing insights into the microbe/U interaction mechanisms needed to predict the effect of microbial processes on the mobility of this radionuclide.
Laboratory studies are performed to identify the soil properties that govern NOR interactions in soils. Sorption and desorption Kds for representative soils are determined, also considering soil aging effects. Chemical analogy between NOR and stable elements (e.g., Ba vs. Ra) is also examined, with new data and additional values gathered from literature.
Considering the dynamics of sorption-desorption reactions, studies are carried out at the Zatu site (France) to develop a method to determine site-specific Kds. Experiments with soil core samples are performed to determine the amount of desorbed U, Ra and Pb and to derive apparent Kd values. The validity of this approach will be confirmed combining these results with in situ studies (Zatu site).
Two approaches are followed to derive models for Kd (NOR) prediction. The first one is the “smart Kd” model, which is based on a realistic description of chemical reactions of NOR in liquid and solid phases. The second one is constructing simple, multivariate Kd prediction models based on soil properties governing NOR interaction. Water transport models with different levels of complexity are applied to describe the transport of NOR at the Zatu site in consistency with site-specific Kds.

Keywords: Naturally occurring radionuclides; NORM; Uranium; Radium; Sorption; Transport; Distribution coefficients; Modeling; Geochemical processes; Biological processes

  • Lecture (Conference)
    European Radiation Protection Week 2022, 09.-14.10.2022, Estoril, Portugal

Permalink: https://www.hzdr.de/publications/Publ-34589


(Data set) 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.

Abstract

The folder contains the data set that the publication with the same name is based on. 

Origin file: 

  1. Reflectivity
  2. Optical conductivity
  3. Band resolved DFT calculation (band structure + optical conductivity)
  4. Comparison of DFT and experiment (interband transitions) above and below CDW transition
  5. Further data sets are available upon request

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Permalink: https://www.hzdr.de/publications/Publ-34588


Scaling Laser-Plasma Electron Accelerators to 100GeV-scale Energies using TWEAC and Multi-Petawatt Lasers

Debus, A.; Steiniger, K.; Schramm, U.

Abstract

The quest for advanced acceleration techniques for providing more compact accelerators is a grand challenge of particle accelerator physics. Addressing this challenge will allow to further scale up energies for high-energy physics, as well as enable accelerator technology to be more commonly available.
Despite tremendous advances in Laser-Plasma accelerators (LPAs) with respect to beam energy, quality, charge and stability, sustaining scalability of compact LPAs to even higher electron energies and more brilliant secondary radiation sources is one of the yet to be solved key challenges of the field.
These limitations can be overcome by TWEAC (Traveling-Wave Electron ACceleration), a novel laser-plasma interaction geometry relying on spatio-temporally shaped ultrashort, high-power laser pulses using existing laser technology. These laser pulses provide "flying" focal regions propagating at tuneable velocities close to the speed of light without the need for external guiding.
Multi-petawatt laser facilities together with TWEAC pave the way towards scalable LPAs on the 100GeV scale without the need for multiple laser-accelerator stages.

Permalink: https://www.hzdr.de/publications/Publ-34587


Petawatt Class Lasers for Realizing Optical Free-Electron Lasers with Traveling-Wave Thomson-Scattering

Steiniger, K.; Debus, A.; Schramm, U.

Abstract

Traveling-Wave Thomson-Scattering (TWTS) is a scheme for the realization of optical free-electron lasers (OFELs) from the interaction of ultra-short, high-power laser pulses with relativistic electrons.
The laser pulse thereby provides the undulator field which typically needs to include a few 100 to several 1000 undulator periods for OFEL operation.
Such long optical undulators are realized in TWTS by the combination of a side-scattering geometry where electron and laser pulse propagation directions enclose the interaction angle $\phi$ and a laser pulse-front tilt $\alpha_\A{tilt} = \phi/2$ of half the interaction angle.
This combination of side-scattering and pulse-front tilt ensures continuous overlap of electrons and laser pulse during the passage of the electrons through the laser pulse.
Interaction durations between laser pulse, electrons, and their emitted radiation can be long enough to initiate microbunching of the electron pulse and subsequent coherent amplification of radiation provided electron and laser pulse are of sufficient quality.
Requirements on electron and laser pulse quality can be met for VUV TWTS OFELs with existing technology already today and higher power laser pulses enable TWTS OFELs at shorter wavelength, e.\,g.\ EUV TWTS OFELs.

Permalink: https://www.hzdr.de/publications/Publ-34586


Atomically Dispersed Pentacoordinated-Zirconium Catalyst with Axial Oxygen Ligand for Oxygen Reduction Reaction

Wang, X.; An, Y.; Liu, L.; Fang, L.; Liu, Y.; Zhang, J.; Qi, H.; Li, T.; Heine, T.; Kuc, A. B.; Yu, M.; Feng, X.

Abstract

Single-atom catalysts (SACs), affording extraordinary catalytic activity per site, represent promising alternatives to the commercial platinum-based electrocatalysts towards oxygen reduction reaction (ORR). Yet, the common in-plane coordination configuration limits platinum-competitive SACs to few transition metal elements with low metal loading (< 5 wt%). Here, we report the discovery of an ORR-efficient Zr-based SAC (denoted O-Zr-N-C), which consists of unique pentacoordinated Zr sites with nontrivial axial O ligands. The axial O ligand with the desirable electron-withdrawing effect downshifts the d-band center of Zr and confers single-atom Zr sites with stable local structure and proper adsorption capability for O-containing intermediates. Consequently, the ORR performance of O-Zr-N-C electrocatalyst in alkaline condition prominently surpasses that of commercial Pt/C, achieving a half-wave potential of 0.91 V vs. reversible hydrogen electrode, a kinetic current density of 76.0 mA cm–2, and outstanding durability (92% current retention after 130-hour operation). Moreover, the pentacoordinated Zr site shows good resistance towards aggregation, enabling the synthesis of O-Zr-N-C with high single atom Zr loading (9.1 wt%). With the high loading catalyst, the assembled zinc-air battery (ZAB) delivers a record-high power density of 324 mW cm−2 among those of SAC-based ZABs. This work not only provides a new member of ORR-active SACs, but also sheds light on the atomic-level design of advanced electrocatalysts.

Permalink: https://www.hzdr.de/publications/Publ-34585


Interlayer excitons in MoSe2/2D perovskite hybrid heterostructures – the interplay between charge and energy transfer

Karpińska, M.; Jasiński, J.; Kempt, R.; Ziegler, J. D.; Sansom, H.; Snaith, H. J.; Taniguchi, T.; Watanabe, K.; Surrente, A.; Dyksik, M.; Maude, D. K.; Kłopotowski, Ł.; Chernikov, A.; Kuc, A. B.; Baranowski, M.; Plochocka, P.

Abstract

Van der Waals crystals have opened a new and exciting chapter in heterostructure research, removing lattice matching constraints characteristic of epitaxial semiconductors. They provide unprecedented flexibility for heterostructure design. Combining 2D perovskites with other 2D materials, in particular transition metal dichalcogenides (TMDs) has recently emerged as an intriguing way to design hybrid opto- electronic devices. However, the excitation transfer mechanism between the layers (charge or energy transfer) remains to be elucidated. Here we investigate PEA2PbI4/MoSe2 and (BA)2PbI4/MoSe2 heterostructures by combining optical spectroscopy and density functional theory (DFT) calculations. We show that the band alignment facilitates charge transfer. Namely, holes are transferred from the TMD to the 2D perovskite, while the electron transfer is blocked, resulting in the formation of inter-layer excitons. Moreover, we show that the energy transfer mechanism can be turned on by an appropriate alignment of the excitonic states, providing a rule of thumb for the deterministic control of the excitation transfer mechanism in TMD/2D-perovskite heterostructures.

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Permalink: https://www.hzdr.de/publications/Publ-34584


On the prospects of magnetic-field-assisted electrodeposition of nano-structured ferromagnetic layers

Huang, M.; Skibinska, K.; Zabinski, P.; Wojnicki, M.; Wloch, G.; Eckert, K.; Mutschke, G.

Abstract

Micro- and nano-structured ferromagnetic layers are attractive for super-hydrophobic and electrocatalytic applications and can be effectively synthesized using electrodeposition. Beside the use of capping agents, magnetic fields have recently been proven to promote the growth of mm-sized conical structures by alternatively generating a supportive local flow. Here we explore the prospects of using magnetic fields to support the growth of smaller, micro-/nano-sized conical structures. We first elaborate by numerical simulations how the local electrolyte flow and the related inhomogeneous mass transfer change with shrinking cone size. Related scaling laws are derived, and stronger viscous friction along with smaller concentration changes inside the diffusion layer are found to limit the support of the magnetic field. To enhance the structuring effect, pulsed electrodeposition and use of superconducting magnets are discussed. Second, systematic experiments on the template-free electrodeposition of nickel layers in magnetic fields of different orientations and intensities are performed. Regardless of the direction, strong fields are found to promote blunt-ended, shell-like structures. These results are finally discussed by the help of numerical simulations which additionally consider the global cell flow forced by the magnetic fields. Importantly, global flow is found to dominate compared to local flow. We therefore propose improved electrode geometries for future research to clarify the prospects of stronger magnetic fields.

Keywords: ferromagnetic metal electrodeposition; magnetic field; nano-structured catalyst; numerical simulation; micro MHD effect

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Permalink: https://www.hzdr.de/publications/Publ-34582


Radiopharmazie des vergangenen Jahrzehnts

Steinbach, J.; Kopka, K.

Abstract

Die Radiochemiker/Radiopharmazeuten des deutschsprachigen Raums sind im Verbund der AGRR – der „Arbeitsgemeinschaft Radiochemie und Radiopharmazie“ – innerhalb der Deutschen Gesellschaft für Nuklearmedizin organisiert. Die AGRR setzt sich vorrangig aus Kolleginnen und Kollegen der D-A-CH-Länder zusammen, sodass auf radiopharmazeutischer Seite eine Anbindung an die OGNMB und SGNM besteht. Sie pflegen dort – auch mit zahlreichen Mitgliedern aus der Industrie – während der jährlichen Arbeitstagungen einen intensiven Austausch, der über die Grenzen klassischer Vortragsveranstaltungen hinausgeht und so zu einer engen Vernetzung beiträgt. Neben klassisch-fachlichen Fragen bietet die AGRR eine Plattform zur Behandlung der vielen regulatorischen Probleme, die sowohl die pharmazeutischen als auch die Strahlenschutz-bezogenen Herausforderungen zur sicheren Versorgung der Nuklearmedizin mit anwendungsfertigen Radiopharmaka mit sich bringen.

Permalink: https://www.hzdr.de/publications/Publ-34581


Speciation and spatial distribution of Eu(III) in fungal mycelium

Günther, A.; Wollenberg, A.; Vogel, M.; Drobot, B.; Steudtner, R.; Freitag, L.; Hübner, R.; Stumpf, T.; Raff, J.

Abstract

Europium, as an easy-to-study analog of the trivalent actinides, is of particular importance for studying the behavior of lanthanides and actinides in the environment. Since different soil organisms can influence the migration behavior of these elements, a detailed knowledge of these interaction mechanisms is important. The aim of this study was to investigate the interaction of mycelia of selected wood-inhabiting (S. commune, P. ostreatus, L. tigrinus) and soil-inhabiting fungi (L. naucinus) with Eu(III). In addition to determining the Eu(III) complexes in the sorption solution, the formed Eu(III) fungal species were characterized using scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, chemical microscopy in combination with the time-resolved laser-induced fluorescence spectroscopy. Our data show that S. commune exhibited significantly higher Eu(III) binding capacity in comparison to the other fungi. Depending on fungal strain, the metal was immobilized on the cell surface, in the cell membranes, and within the membranes of various organelles, or in the cytoplasm in some cases. During the bioassociation process two different Eu(III) fungal species were formed in all investigated fungal strain. The phosphate groups of organic ligands were identified as being important functional groups to bind Eu(III) and thus immobilize the metal in the fungal matrix. The information obtained contributes to a better understanding of the role of fungi in migration, removal or retention mechanisms of rare earth elements and trivalent actinides in the environment.

Keywords: Fungi; Europium; Speciation; Scanning transmission electron microscopy (STEM); Chemical microscopy; Time-resolved laser-induced fluorescence spectroscopy (TRLFS)

Permalink: https://www.hzdr.de/publications/Publ-34580


Coupling between ferromagnetic and ferroelastic transitions and ordering in Heusler alloys produces new multifunctionality

Oleg, H.; Hanuš, S.; Fähler, S.

Abstract

The ability of Heusler alloys to accommodate broad variations of composition, doping
and ordering provides multiple options for tailoring their ferromagnetic and ferroelastic
properties. Moreover, existing coupling between these ferroic properties ranging from
coupled ferroic transitions to a coupling of their ferromagnetic and ferroelastic
microstructure allows for manifold multifunctionalities. Here we focus on ferromagnetic,
metamagnetic and reentrant shape memory alloys explaining the principles and sketch
effects’ rich susceptibility to temperature, magnetic field and stress. We illustrate how
these can provide a path to a multitude of emerging applications for actuation, sensing,
and energy use. As an outlook, we discuss time dependency, fatigue, and finite size
effects, which are not yet fully explored.

Keywords: Heusler Alloys; Functional magnetic materials; Magnetic shape memory alloys

Permalink: https://www.hzdr.de/publications/Publ-34579


New concepts for recovery of metals from wastes using biological means

Pollmann, K.; Lederer, F.; Schönberger, N.; Jain, R.; Chakankar, M. V.; Kutschke, S.

Abstract

The development of new technologies, especially in the field of renewable energies, has led to an increase in the demand for essential metals in recent years. At the same time, the extraction of these metals is not always environmentally friendly. Toxic metals can pollute waters and enter the environment both during extraction and processing or through disposal. Therefore, new environmentally friendly technologies are needed that prevent their entry into the environment or efficiently contribute to the recovery and recycling of the elements. Biotechnology can contribute to this.
Such technologies exploit the natural ability of organisms, bio-components, and biomolecules to interact with metals. Furthermore, modern methods of molecular biology and synthetic biology enable the development of tailored biomolecules that interact with metal ions or surfaces. In this talk, some of these modern biotechnological concepts for metal extraction such as bioleaching, bioflotation, biosorption from various primary and secondary raw materials as well as for treatment of metal contaminated waste waters will be presented.

  • Lecture (Conference) (Online presentation)
    ACS Spring 2022, 20.-24.03.2022, San Diego, CA, USA

Permalink: https://www.hzdr.de/publications/Publ-34578


Temperature Driven Transformation of the Flexible Metal-Organic Framework DUT-8(Ni)

Ehrling, S.; Senkovska, I.; Efimova, A.; Bon, V.; Abylgazina, L.; Petkov, P.; Evans, J. D.; Attallah, A. G.; Thomas Wharmby, M.; Roslova, M.; Huang, Z.; Tanaka, H.; Wagner, A.; Schmidt, P.; Kaskel, S.

Abstract

DUT-8(Ni) belongs to the flexible pillared layer MOFs, which solvent free variant can exist in the open pore (op, rigid) form or in the closed pore (cp, flexible) form depending on the crystal size regime. In present work, we report on response of desolvated DUT-8(Ni) against elevated temperature. For both variants, heating leads to structural transition, involving interpenetration of the framework and resulting in a new crystalline contracted closed pore phase (DUT-8(Ni)_ccp). The new compound was characterized by powder X-ray diffraction and spectroscopic techniques, such as IR, Raman spectroscopy, EXAFS and positron annihilation lifetime spectroscopy (PALS). State of the framework before transition (op vs. cp) influences the transition temperature: the small particles of the op phase transform at significantly lower temperature in comparison to the macroparticles of the cp phase, transforming just before decomposition. Thermal effects of structural cp to ccp transitions were studied using differential scanning calorimetry (DSC), showing an overall exothermic effect of the process, necessarily involving bond breaking and reformation. The theoretical calculations reveal the energetics driving the observed temperature induced phase transition.

Keywords: bond rearrangement; nterpenetrated MOF; hase transitio; thermal response; hermally-induced phase transformation

Involved research facilities

  • P-ELBE

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Permalink: https://www.hzdr.de/publications/Publ-34575


Atherosclerotic risk is associated with cerebral perfusion – a cross-sectional study using arterial spin labelling MRI

Hafdi, M.; Mutsaerts, H. J.; Petr, J.; Richard, E.; van Dalen, J. W.

Abstract

Non-invasive measurement of cerebral perfusion is promising for identifying individuals at high risk of cerebrovascular disease for prevention strategies. We tested whether the new and easily calculated arterial spin labelling (ASL) MRI parameter for vascular and tissue signal distribution - ‘spatial coefficient of variation’ (ASL-sCoV) - correlates better as a radiological marker with atherosclerotic risk than the more courant markers white matter hyperintensity volume (WMHV) and cerebral blood flow (CBF).
Methods
195 participants of the preDIVA trial, aged 72-80 years with systolic hypertension (>140 mmHg) were invited for 2 MRI-scans 2-3 years apart. WMHV was derived from 3D FLAIR; grey matter CBF and ASL-sCoV from ASL. The ASL-sCoV was defined as the standard deviation of CBF divided by the mean CBF in the entire region of interest. Atherosclerotic risk was operationalized as 10-year cardiovascular risk by the Systematic COronary Risk Evaluation Older Persons (SCORE O.P.) and calculated at baseline and follow-up. Data were analysed using linear regression.
Results
CBF was associated with atherosclerotic risk scores at baseline (standardized-beta=-0.26, 95%CI=-0.40,-0.13, p<0.001) but not on follow-up (standardized-beta=-0.14, 95%CI=-0.33,0.04, p=0.12). ASL-sCoV was associated with atherosclerotic risk scores at both time points (baseline standardized-beta=0.23, 95%CI=0.10,0.36, p<0.0001, follow-up standardized beta= 0.20, 95%CI=0.03,0.36, p=0.02). WMHV was not significantly associated with atherosclerotic risk scores at either time-points (p>0.25). There were no longitudinal associations between changes in MRI parameters and baseline atherosclerotic risk scores. Imputation of missing values, exclusion of outliers, and repeating analyses using the Framingham- and ASCVD risk scores instead of the SCORE O.P. gave similar results.
Conclusions
Our findings suggest that ASL-sCoV correlates better with atherosclerotic risk than the more conventional markers CBF and WMHV. Our data reaffirm that non-invasive imaging with MRI is highly informative and could provide additional information about the (cerebro)vascular status, especially in participants in whom early prevention of atherosclerosis and cardiovascular disease might still be attainable.

Involved research facilities

  • PET-Center

Permalink: https://www.hzdr.de/publications/Publ-34573


Mitigating pseudoreplication and bias in resource selection functions with autocorrelation-informed weighting

Alston, J.; Fleming, C.; Kays, R.; Streicher, J.; Downs, C.; Ramesh, T.; Reineking, B.; Calabrese, J.

Abstract

Resource selection functions are among the most commonly used statistical tools in both basic and applied animal ecology. They are typically parameterized using animal tracking data, and advances in animal tracking technology have led to increasing levels of autocorrelation between locations in such data sets. Because resource selection functions assume that data are independent and identically distributed, such autocorrelation can cause misleadingly narrow confidence intervals and biased parameter estimates. Data thinning, generalized estimating equations, and step selection functions have been suggested as techniques for mitigating the statistical problems posed by autocorrelation, but these approaches have notable limitations that include statistical inefficiency, unclear or arbitrary targets for adequate levels of statistical independence, constraints in input data, and (in the case of step selection functions) scale-dependent inference. To remedy these problems, we introduce a method for likelihood weighting of animal locations to mitigate the negative consequences of autocorrelation on resource selection functions. This method weights each observed location in an animal's movement track according to its level of autocorrelation, expanding confidence intervals to match an objective target (i.e., the effective sample size for Autocorrelated Gaussian Density Estimation) and accounting for bias that can arise when there are gaps in the movement track. In this study, we describe the mathematical principles underlying our method, demonstrate its practical advantages versus conventional approaches using simulations and empirical data on a water mongoose (\textit{Atilax paludinosus}), a caracal (\textit{Caracal caracal}), and a serval (\textit{Leptailurus serval}), and discuss pathways for further development of our method. We also provide a complete, annotated analytical workflow to help new users apply our method to their own animal tracking data using the \texttt{ctmm R} package.

Keywords: continuous-time movement models; habitat selection; home range; Ornstein-Uhlenbeck process; space use; spatial point process; utilization distribution

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Permalink: https://www.hzdr.de/publications/Publ-34572


alpaka-group/alpaka: alpaka 0.9.0: The SYCL Complex

Bastrakov, S.; Bocci, A.; Di Pilato, A.; Ehrig, S.; Gruber, B. M.; Hübl, A.; Kelling, J.; Pantaleo, F.; Stephan, J.; Vyskocil, J.; Widera, R.; Worpitz, B.

Abstract

The alpaka library is a header-only C++17 abstraction library for accelerator development. Its aim is to provide performance portability across accelerators through the abstraction (not hiding!) of the underlying levels of parallelism.

Keywords: CUDA; HPC; alpaka; OpenMP; HIP; C++; GPU; heterogeneous computing; performance portability; FPGA; SYCL

  • Software in external data repository
    Publication year 2022
    Programming language: C++
    System requirements: OS: Linux, Windows, or macOS Software requirements: C++17 compiler, Boost 1.74.0+, CMake 3.18+
    License: MPL-2.0 (Link to license text)
    Hosted on GitHub: Link to location
    DOI: 10.5281/zenodo.6475608

Permalink: https://www.hzdr.de/publications/Publ-34571


Quantifying the impact of cross-border flux on disease dynamics

Senapati, A.; Calabrese, J.

Abstract

Countries all over the world have implemented various cross-border policies such as mandatory testing, quarantining upon arrival, and travel restrictions to minimize the risk of infection. The strength of these measures has varied over time. The aim of this study is twofold. First, we develop a spatially explicit SIR-type mechanistic model to assess the epidemiological consequences of allowing cross-border mobility between two countries under different epidemic conditions. We show that the time to achieve the peak of infection is significantly changed if cross-border mobility is allowed during disease outbreak. Moreover, if we compare between the scenarios with and without cross-border flux, the difference in peak timings in two countries is reduced in the latter case. Next, based on stochastic simulation, we present a method for estimating cross-border mobility flux between two regions from the difference in peak-timing in infection under some reasonable assumptions. As a case study, we apply the method to data from the Germany-Poland border region and quantify heterogeneity in cross-border fluxes along the border during the COVID-19 pandemic.

Keywords: COVID-19; Infectious disease; Mathematical Modelling; Cross-border mobility; Compartmental modelling

  • Open Access Logo Lecture (Conference)
    Models in Population Dynamics, Ecology and Evolution (MPDEE 2022), 13.-17.06.2022, Torino, Italy

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Permalink: https://www.hzdr.de/publications/Publ-34569


Differences in the critical dynamics underlying the human and fruit-fly connectome

Ódor, G.; Deco, G.; Kelling, J.

Abstract

Previous simulation studies on human connectomes suggested that critical dynamics emerge subcritically in the so-called Griffiths phases. Now we investigate this on the largest available brain network, the 21662 node fruit-fly connectome, using the Kuramoto synchronization model. As this graph is less heterogeneous, lacking modular structure and exhibiting high topological dimension, we expect a difference from the previous results. Indeed, the synchronization transition is mean-field-like, and the width of the transition region is larger than in random graphs, but much smaller than as for the KKI-18 human connectome. This demonstrates the effect of modular structure and dimension on the dynamics, providing a basis for better understanding the complex critical dynamics of humans.

Keywords: Critical phenomena; Dynamical phase transitions; Neuronal dynamics; Neuronal network activity; Nonequilibrium statistical mechanics; Synchronization transition

Permalink: https://www.hzdr.de/publications/Publ-34568


Top-down nanofabrication of silicon nanopillars hosting telecom photon emitters

Jagtap, N. S.; Hollenbach, M.; Fowley, C.; Baratech, J.; Guardia-Arce, V.; Kentsch, U.; Eichler-Volf, A.; Abrosimov, N. V.; Erbe, A.; Shin, C.; Kim, H.; Helm, M.; Lee, W.; Astakhov, G. V.; Berencén, Y.

Abstract

Silicon, a ubiquitous material in modern computing, is an emerging platform for realizing a source of indistinguishable single-photons on demand. The integration of recently discovered single-photon emitters in silicon into photonic structures is advantageous to exploit their full potential for integrated photonic quantum technologies. Here, we show the integration of an ensemble of telecom photon emitters in a two-dimensional array of silicon nanopillars. We developed a top-down nanofabrication method, enabling the production of thousands of individual nanopillars per square millimeter with state-of-the-art photonic-circuit pitch, all the while being free of fabrication-related radiation damage defects. We found a waveguiding effect of the 1278 nm G-center emission along individual pillars accompanied by improved brightness, compared to that of bulk silicon. These results open pathways to monolithically integrating single-photon emitters into a photonic platform.

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  • Poster
    DPG-Tagung 2022, 04.-09.09.2022, Regensburg, Germany

Permalink: https://www.hzdr.de/publications/Publ-34567


A photonic platform hosting telecom photon emitters in silicon

Jagtap, N. S.; Hollenbach, M.; Fowley, C.; Baratech, J.; Guardia-Arce, V.; Kentsch, U.; Eichler-Volf, A.; Abrosimov, N. V.; Erbe, A.; Shin, C.; Kim, H.; Helm, M.; Lee, W.; Astakhov, G. V.; Berencén, Y.

Abstract

Silicon, a ubiquitous material in modern computing, is an emerging platform for realizing a source of indistinguishable single-photons on demand. The integration of recently discovered single-photon emitters in silicon into photonic structures is advantageous to exploit their full potential for integrated photonic quantum technologies [1] [2]. Here, we show the integration of telecom photon emitters in a photonic platform consisting of silicon nanopillars. We developed a CMOS-compatible nanofabrication method, enabling the production of thousands of individual nanopillars per square millimetre with state-of-the-art photonic-circuit pitch, all the while being free of fabrication-related radiation damage defects. We found a waveguiding effect of the 1278 nm G-center emission along individual pillars accompanied by improved brightness, photoluminescence signal-to-noise ratio and photon extraction efficiency compared to that of bulk silicon. These results unlock clear pathways to monolithically integrating single-photon emitters into a photonic platform at a scale that matches the required pitch of quantum photonic circuits.

Keywords: G centers; MACEtch

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  • Open Access Logo Poster
    LEAPS meets Quantum Technology, 15.-20.05.2022, Elba Island, Italy

Permalink: https://www.hzdr.de/publications/Publ-34566


Introducing micro physiological systems to evaluate new radiopharmaceuticals: First attempts with radiolabeled cetuximab

Sihver, W.; Nitt-Weber, A.-K.; Behrens, S.; Ullrich, M.; Pietzsch, H.-J.; Namazian Jam, N.; Schmieder, F.; Sonntag, F.

Abstract

Radiopharmaceuticals can be used for targetspecific functional diagnostics, such as PET or SPECT imaging, or radionuclide therapy of diseased tissue, depending on the incorporated radionuclide. Following initial in vitro testing, radiopharmaceutical candidates are usually further characterized in small animals. Since reduction of animal testing is a central precept in preclinical research it would be beneficial to replace at least some of these tests by alternative methods. Using micro-physiological system (MPS) technology, various organ-on-chip models can be created with human cell systems/organoids, which are operated in a circulatory system under defined physiological conditions.
Here we present first attempts to introduce MPS for evaluating radiopharmaceuticals using the radiolabeled anti-EGFR antibody cetuximab (C225) as reference compound.
In an MPS equipped with six 96-well plate-like microwells in a flow chamber, binding of 64Cu and 68Ga-labeled C225 to cells and spheroids grown from A431 (EGFR-positive) and MDA-MB435S (EGFR-negative) cells was measured and compared to conventional microplates. Specific saturation binding of radiolabeled C225 at increasing concentrations was analyzed using a phosphor imaging system.
The affinity of radiolabeled C225 towards A431 spheroids measured in the MPS was in the same range as that of the spheroids in conventional microplates. Within the MPS assays, the results showed a trend towards increased affinity for A431 monolayers compared to the spheroids. The values of binding capacity for radiolabeled C225 on 2D and 3D A431 cell culture models were in the same order of magnitude when measured in MPS or in microplates.

Keywords: radiopharmaceuticals; micro-physiological systems; radiopharmacological parameters; preclinical trials; reduction experimental animals

Permalink: https://www.hzdr.de/publications/Publ-34565


Research data: Terahertz-wave decoding of femtosecond extreme-ultraviolet light pulses

Ilyakov, I.; Agarwal, N.; Deinert, J.-C.; Liu, J.; Yaroslavtsev, A.; Foglia, L.; Kurdi, G.; Mincigrucci, R.; Principi, E.; Jakob, G.; Kläui, M.; Seifert, T.; Kampfrath, T.; Kovalev, S.; Carley, R.; Scherz, A.; Gensch, M.

Abstract

This repository entry contains the research data used for generating the publication "Terahertz-wave decoding of femtosecond extreme-ultraviolet light pulses".

Keywords: Terahertz; Extreme Ultraviolet; Pulse-resolved; ultrafast; terahertz tomography; electron bunch diagnostics

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Permalink: https://www.hzdr.de/publications/Publ-34564


Differential evolution optimization of Rutherford back-scattering spectra

Heller, R.; Klingner, N.; Claessens, N.; Merckling, C.; Meersschaut, J.

Abstract

We investigate differential evolution optimization to fit Rutherford back-scattering data. The algorithm helps to find, with very high precision, the sample composition profile that best fits the experimental spectra. The capabilities of the algorithm are first demonstrated with the analysis of synthetic Rutherford back-scattering spectra. The use of synthetic spectra highlights the achievable precision, through which it becomes possible to differentiate between the counting statistical uncertainty of the spectra and the fitting error. Finally, the capability of the algorithm to analyze large sets of experimental spectra is demonstrated with the analysis of the position-dependent composition of a SrxTiyOz layer on a 200 mm silicon wafer. It is shown that the counting statistical uncertainty as well as the fitting error can be determined, and the reported total analysis uncertainty must cover both.

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Permalink: https://www.hzdr.de/publications/Publ-34563


Anion-specific structure and stability of guanidinium-bound DNA origami

Hanke, M.; Dornbusch, D.; Hadlich, C.; Roßberg, A.; Hansen, N.; Grundmeier, G.; Tsushima, S.; Keller, A.; Fahmy, K.

Abstract

While the folding of DNA into rationally designed DNA origami nanostructures has been studied extensively with the aim of increasing structural diversity and introducing functionality, the fundamental physical and chemical properties of these nanostructures remain largely elusive. Here, we investigate the correlation between atomistic, molecular, nanoscopic, and thermodynamic properties of DNA origami triangles. Using guanidinium (Gdm) as a DNA-stabilizing but potentially also denaturing cation, we explore the dependence of DNA origami stability on the identity of the accompanying anions. The statistical analyses of atomic force microscopy (AFM) images and circular dichroism (CD) spectra reveals that sulfate and chloride exert stabilizing and destabilizing effects, respectively, already below the global melting temperature of the DNA origami triangles. We identify structural transitions during thermal denaturation and show that heat capacity changes ΔCp determine the temperature sensitivity of structural damage. The different hydration shells of the anions and their potential to form Gdm+ ion pairs in concentrated salt solutions modulate ΔCp by altered wetting properties of hydrophobic DNA surface regions as shown by molecular dynamics simulations. The underlying structural changes on the molecular scale become amplified by the large number of structurally coupled DNA segments and thereby find a nanoscopic correlation in AFM images.

Keywords: DNA origami; atomic force microscopy; denaturation; circular dichroism; counter ions; heat capacity

Permalink: https://www.hzdr.de/publications/Publ-34562


A self-consistent planetary synchronization model of short, medium, and long term cycles of the solar dynamo

Stefani, F.; Horstmann, G. M.; Klevs, M.; Stepanov, R.; Weier, T.

Abstract

In a series of recent papers we have developed a self-consistent explanation of short, medium and long term solar cycles in terms of synchronization by planetary motions. According to this model, the surprisingly phase-stable 22.14-year Hale cycle results from parametric resonance of a conventional α−Ω dynamo with an oscillatory part of the helical turbulence parameter α that is thought to be synchronized by the 11.07-year spring-tide periodicity of the three tidally dominant planets Venus, Earth and Jupiter. The medium term Suess-de Vries cycle (specified to 193 years in our model) emerges as a beat period between the basic 22.14-year Hale cycle and some (yet not well
understood) spin–orbit coupling connected with the motion of the Sun around the barycenter of the solar system that is governed by the 19.86-year synodic period of Jupiter and Saturn. Closely related to this, Gleissberg-type cycles appear as nonlinear beat effects and/or from perturbations of the Sun’s orbital motion due to other synodic periods of the Jovian planets. Finally, the long-term variations on the millennial time-scale (Bond events) arise as chaotic transitions between regular and irregular episodes of the solar dynamo, in close analogy with the super-modulation concept introduced by Weiss and Tobias.

Keywords: solar dynamo; synchronization

  • Lecture (Conference)
    The 12th pamir International Conference on Fundamental and Applied MHD, 04.-08.07.2022, Krakow, Poland

Permalink: https://www.hzdr.de/publications/Publ-34561


Development of a Copper-free Click-Radiolabeling for 99mTc-Tricarbonyl Complexes

Schlesinger, M.

Abstract

Click chemistry, and in particular copper-free click reactions, have gained growing interest in the field of radiopharmaceutical sciences. The 99mTc-tricarbonyl moiety is an excellent precursor for radiolabelling of biomolecules. This master thesis aims at synthesizing two new chelators containing the 2,2’-dipicolylamine (DPA) moiety for 99mTc and investigating the copper-free strain-promoted cycloaddition for the Tc(CO)3-core. The first chelator was based on a tetrafluorophenyl ester and was successfully radiolabeled with [99mTc][Tc(CO)3(H2O)3]+ at 40°C with a a radiochemical conversion (RCC) of 89% after 20 min. The chelator was afforded in a radiochemical purity over 99% after separation using a cartridge. The subsequent conjugation of an amine-functionalized PSMA (prostate-specific membrane antigen) targeting motif was investigated, and the PSMA targeting 99mTc-complex was afforded with an RCC of 23% at 100°C after 150 min. Two other unknown side products were observed. Further in-depth studies are required to optimize the radiolabeling and to identify the formed side-products. For the SPAAC reaction, a 4,8-diazacyclononyne containing the DPA moiety was prepared via the Nicholas reaction. Radiolabeling at 100°C afforded the radiolabeled complex with an RCC of 89% after 30 min. The ensuing SPAAC reaction with an azide-functionalized PSMA motif was studied at three different temperatures. The PSMA targeting 99mTc-complex was afforded selectively at 100°C after 4 hours with an RCC of 89%. No side products were observed. Nonradioactive Re(CO)3-complexes were synthesized and characterized to confirm the 99mTc-complexes. Further modifications of the 4,8-diazacyclononyne could prospectively enable to carry out the radiolabeling under physiological conditions. Continuing in vitro and in vivo experiments are planned.

Keywords: technetium-99m; click reaction; strainpromoted; tricarbonyl complex

  • Master thesis
    Universität Leipzig, 2022
    Mentor: PD Dr. habil. Constantin Mamat
    122 Seiten

Permalink: https://www.hzdr.de/publications/Publ-34560


Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting

Steuer, O.; Schwarz, D.; Oehme, M.; Schulze, J.; Mączko, H.; Kudrawiec, R.; Fischer, I. A.; Heller, R.; Hübner, R.; Khan, M. M.; Georgiev, Y.; Zhou, S.; Helm, M.; Prucnal, S.

Abstract

Alloying Ge with Sn enables effective band-gap engineering and improves significantly the charge carrier mobility. The pseudomorphic growth of Ge1-xSnx on Ge causes in-plane compressive strain, which degrades the superior properties of the Ge1-xSnx alloys. Therefore, efficient strain engineering is required. In this article, we present strain and band-gap engineering in GeSn alloys grown on Ge a virtual substrate using post-growth nanosecond pulsed laser melting (PLM). Micro-Raman and X-ray diffraction show that the initial in-plane compressive strain is removed. Moreover, for PLM energy densities higher than 0.5 J cm-2, the Ge0.89Sn0.11 layer becomes tensile strained. Simultaneously, as revealed by Rutherford Backscattering spectrometry, cross-sectional transmission electron microscopy investigations and X-ray diffraction the crystalline quality and Sn-distribution in PLM-treated Ge0.89Sn0.11 layers are only slightly affected. Additionally, the change of the band structure after PLM is also confirmed by low-temperature photoreflectance measurements. The presented results prove that post-growth ns-range PLM is an effective way for band-gap and strain engineering in highly-mismatched alloys.

Keywords: Germanium Tin; band-gap engineering; GeSn; pseudomorphic growth; pulsed laser melting; GeSn alloys; molecular-beam epitaxy; Ge1-xSnx

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  • Open Access Logo Journal of Physics: Condensed Matter 35(2023)5, 055302
    Online First (2022) DOI: 10.1088/1361-648X/aca3ea
    Cited 4 times in Scopus
  • Lecture (Conference)
    Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting, 05.-09.09.2022, Regensburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34559


High-field magnetization studies and their analysis in RFe11Ti and RFe11TiH1 rare-earth intermetallics (an example: HoFe11TiHx, x = 0 and 1)

Kostyuchenko, N. V.; Tereshina, I. S.; Tereshina-Chitrova, E. A.; Skoursky, J.; Doerr, M.; Zvezdin, A. K.; Drulis, H.

Abstract

We present experimental high-field magnetization studies for the single-crystalline ferrimagnetic RFeTi compounds at example of holmium-based hydride in order to evaluate, compare and analyze the crystal-field and exchange parameters. We predict theoretically the magnetization behavior of HoFe11Ti up to 80 T magnetic field for the first time. The results are compared with data for the parent compound HoFe11TiH1 and those with erbium and thulium (x = 0 and 1).

Involved research facilities

  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-34558


Fermi surface of a system with strong valence fluctuations: Evidence for a noninteger count of valence electrons in EuIr2Si2

Götze, K.; Bergk, B.; Ignatchik, O.; Polyakov, A.; Kraft, I.; Lorenz, V.; Rosner, H.; Förster, T.; Seiro, S.; Sheikin, I.; Wosnitza, J.; Geibel, C.

Abstract

We present de Haas-van Alphen (dHvA) measurements on an Eu-based valence-fluctuating system. EuIr2Si2 exhibits a temperature-dependent, noninteger europium valence with Eu2.8+ at low temperatures. The comparison of experimental results from our magnetic-torque experiments in fields up to 32 T and density functional theory band-structure calculations with localized 4f electrons shows that the best agreement is reached for a Fermi surface based on a valence of Eu2.8+. The calculated quantum-oscillation frequencies for Eu3+ instead cannot explain all the experimentally observed frequencies. The effective masses, derived from the temperature dependence of the dHvA oscillation amplitudes, show not only a significant enhancement with masses up to 11 me (me being the free electron mass), but also a magnetic-field dependence of the heaviest mass. We attribute the formation of these heavy masses to strong correlation effects resulting from valence fluctuations of 4f electrons being strongly hybridized with conduction electrons. The increase of the heavy masses with magnetic field likely results from the onset of the expected field-induced valence crossover that enhances these valence fluctuations but does not alter the Fermi-surface topology in the field range studied.

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  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-34557


Collinear order in the spin-5/2 triangular-lattice antiferromagnet Na3Fe(PO4)2

Sebastian, S. J.; Islam, S. S.; Jain, A.; Yusuf, S. M.; Uhlarz, M.; Nath, R.

Abstract

We set forth the structural and magnetic properties of the frustrated spin-5/2 triangle lattice antiferromagnet Na3Fe(PO4)2 examined via x-ray diffraction, magnetization, heat capacity, and neutron diffraction measurements on the polycrystalline sample. No structural distortion was detected from the temperature-dependent x-ray diffraction down to 12.5 K, except a systematic lattice contraction. The magnetic susceptibility at high temperatures agrees well with the high-temperature series expansion for a spin-5/2 isotropic triangular lattice antiferromagnet with an average exchange coupling of J/kB ≃ 1.8 K rather than a one-dimensional spin-5/2 chain model. This value of the exchange coupling is consistently reproduced by the saturation field of the pulse field magnetization data. It undergoes a magnetic long-range order at TN ≃ 10.4 K. Neutron diffraction experiments elucidate a collinear antiferromagnetic ordering below TN with the propagation vector k = (1, 0, 0). An intermediate value of frustration ratio ( f ≃ 3.6) reflects moderate frustration in the compound which is corroborated by a reduced ordered magnetic moment of ∼1.52μB at 1.6 K, compared to its classical value (5μB). Magnetic isotherms exhibit a change of slope envisaging a field induced spin-flop transition at HSF ≃ 3.2 T. The magnetic field vs temperature phase diagram clearly unfold three distinct phase regimes, reminiscent of a frustrated magnet with in-plane (XY-type) anisotropy.

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  • High Magnetic Field Laboratory (HLD)

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Permalink: https://www.hzdr.de/publications/Publ-34556


Tunneling transport in WSe2-MoS2 heterojunction transistor enabled by a two-dimensional device architecture

Chava, P.; Watanabe, K.; Taniguchi, T.; Mikolajick, T.; Helm, M.; Erbe, A.

Abstract

Heterojunctions made of two-dimensional (2D) semiconducting materials provide promising properties for the realization of tunnel field effect transistors (TFETs). The absence of dangling bonds allows the formation of sharp hetero-interfaces, which enables the reduction of parasitic components arising due to interface traps. In this work, we demonstrate band-to-band tunneling (BTBT) between layers of WSe2 and MoS2 that are contacted with few-layered graphene (FLG) on both sides of the junction and completely encapsulated with hexagonal boron nitride (h-BN). Additionally, we also use the FLG as a gate electrode, which allows us to realize devices made entirely of different 2D materials. We observe negative differential resistance (NDR) confirming the tunneling transport in our devices showing the potential in terms of further optimization.

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Permalink: https://www.hzdr.de/publications/Publ-34555


A combined extended x–ray absorption fine structure spectroscopy and density functional theory study of americium vs. yttrium adsorption on corundum (α–Al2O3)

Huittinen, N. M.; Virtanen, S.; Roßberg, A.; Eibl, M.; Lönnrot, S.; Polly, R.

Abstract

Adsorption reactions on mineral surfaces are influenced by the overall concentration of the adsorbing metal cation. Different site types (strong vs. weak ones) are often included to describe the complexation reactions in the various concentration regimes. More specifically, strong sites are presumed to retain metal ions at low sorbate concentrations, while weak sites contribute to metal ion retention when the sorbate concentration increases. The involvement of different sites in the sorption reaction may, thereby, also be influenced by competing cations, which increase the overall metal ion concentration in the system. To date, very little is known about the complex structures and metal ion speciation in these hypothetical strong- and weak-site regimes, especially in competing scenarios. In the present study, we have investigated the uptake of the actinide americium on corundum (α–Al2O3) in the absence and presence of yttrium as competing metal by combining extended X-ray absorption fine structure spectroscopy (EXAFS) with density functional theory (DFT) calculations. Isotherm studies using the radioactive 152Eu tracer were used to identify the sorption regimes where strong sites and weak sites contribute to the sorption reaction. The overall americium concentration, as well as the presence of yttrium could be seen to influence both the amount of americium uptake by corundum, but also the speciation at the surface. More specifically, increasing the Am3+ or Y3+ concentrations from the strong site to the weak site concentration regimes in the mineral suspensions resulted in a decrease in the overall Am–O coordination number from nine to eight, with a subsequent shortening of the average Am–O bond length. DFT calculations suggest a reduction of the surface coordination with increasing metal–ion loading, postulating the formation of tetradentate and tridentate Am3+ complexes at low and high surface coverages, respectively.

Keywords: EXAFS; DFT; sorption competition; Am3+; Y3+; speciation; strong sites; weak sites

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Permalink: https://www.hzdr.de/publications/Publ-34553


Influence of Albumin Binders on Tumor Uptake of 225Ac-mcp-PSMA-Radioconjugates

Mamat, C.; Reissig, F.; Zarschler, K.; Novy, Z.; Petrik, M.; Bendova, K.; Kurfurstova, D.; Bouchal, J.; Pietzsch, H.-J.; Kopka, K.

Abstract

The prostate-specific membrane antigen (PSMA) is expressed in approx. 80% of prostate cancer at considerably higher levels in tumor cells compared to healthy tissues. Its upregulation occurs in all stages of the disease. Therefore, PSMA has emerged as an attractive target for molecular imaging and especially targeted radionuclide therapy (endoradiotherapy) of metastatic castration-resistant prostate cancer (mCRPC).
Due to its favorable nuclear physical properties, actinium-225 belongs to the clinically applied alpha emitters for therapeutic applications. More than ten clinical trials are displayed for actinium-225-DOTA-based conjugates. A trial using [225Ac]Ac-PSMA-617 as the IMP in men with PSMA-positive prostate cancer is projected to start. Actinium-225 can be chelated with the standard DOTA chelator, but requires rather harsh labeling conditions such as high temperatures (80–95°C) or microwave assistance. Alternatively, with the complexing agent macropa mild labeling conditions, low reaction temperature and high in vivo stability can be realized owing to its perfect characteristics for Ac3+ chelation.
Moreover, to further improve the tumor uptake for future targeted alpha therapy, albumin binding units based on 4-iodophenylbutyrate were introduced to increase the tumor uptake. Two 225Ac-radioconjugates with albumin binders were prepared, either containing one or two PSMA-binding units (based on PSMA-617), the second one to raise the binding affinity to the PSMA receptor. The synthetic approach consisted of the functionalization of one or two picolinic side arms with a clickable reactive site for the connection of the vector molecules. The azide-functionalized PSMA derivative, which also contains the albumin binder, was prepared using standard peptide coupling conditions. Cell culture-based studies regarding radioligand affinity and clonogenicity were performed using PSMA-positive LNCaP cells and the biodistribution of the radioconjugates was evaluated using LNCaP tumor-bearing mice.
Radiolabeling of both PSMA ligands with [225Ac]Ac3+ was performed at up to 5 MBq/nmol with >99% radiochemical purity. Cell binding and survival studies revealed a higher cell binding affinity and an improved cell killing efficiency for the radioconjugate with two PSMA-binding entities compared to the derivative with only one targeting motif. A considerable binding of both radioligands to mouse, rat and human serum proteins was confirmed. Biodistribution studies revealed enhanced blood circulation times of both albumin-binding PSMA ligands compared to their counterparts without the albumin binders. A substantially higher accumulation in LNCaP tumors up to 50 %ID/g (one PSMA-binding moiety) and 120 %ID/g (two PSMA-binding moieties) after 120 h p.i., respectively, was also observed. Additionally, a considerable DNA damage and a massive decrease in cell proliferation was observed by immunohistochemical examination of LNCaP tumors, whereas necrosis in the kidneys of the animals was not observed.

  • Open Access Logo Lecture (Conference)
    TERACHEM 2022, 14.-17.09.2022, Bressanone, Italien

Permalink: https://www.hzdr.de/publications/Publ-34552


Temporal contrast-dependent modeling of laser-driven solids - studying femtosecond-nanometer interactions and probing

Garten, M.

Abstract

Establishing precise control over the unique beam parameters of laser-accelerated ions from relativistic ultra-short pulse laser-solid interactions has been a major goal for the past 20 years. While the spatio-temporal coupling of laser-pulse and target parameters create transient phenomena at femtosecond-nanometer scales that are decisive for the acceleration performance, these scales have also largely been inaccessible to experimental observation. Computer simulations of laser-driven plasmas provide valuable insight into the physics at play. Nevertheless, predictive capabilities are still lacking due to the massive computational cost to perform these in 3D at high resolution for extended simulation times. This thesis investigates the optimal acceleration of protons from ultra-thin foils following the interaction with an ultra-short ultra-high intensity laser pulse, including realistic contrast conditions up to a picosecond before the main pulse. Advanced ionization methods implemented into the highly scalable, open-source particle-in-cell code PIConGPU enabled this study. Supporting two experimental campaigns, the new methods led to a deeper understanding of the physics of Laser-Wakefield acceleration and Colloidal Crystal melting, respectively, for they now allowed to explain experimental observations with simulated ionization- and plasma dynamics. Subsequently, explorative 3D3V simulations of enhanced laser-ion acceleration were performed on the Swiss supercomputer Piz Daint. There, the inclusion of realistic laser contrast conditions altered the intra-pulse dynamics of the acceleration process significantly. Contrary to a perfect Gaussian pulse, a better spatio-temporal overlap of the protons with the electron sheath origin allowed for full exploitation of the accelerating potential, leading to higher maximum energies. Adapting well-known analytic models allowed to match the results qualitatively and, in chosen cases, quantitatively. However, despite complex 3D plasma dynamics not being reflected within the 1D models, the upper limit of ion acceleration performance within the TNSA scenario can be predicted remarkably well. Radiation signatures obtained from synthetic diagnostics of electrons, protons, and bremsstrahlung photons show that the target state at maximum laser intensity is encoded, previewing how experiments may gain insight into this previously unobservable time frame.
Furthermore, as X-ray Free Electron Laser facilities have only recently begun to allow observations at femtosecond-nanometer scales, benchmarking the physics models for solid-density plasma simulations is now in reach. Finally, this thesis presents the first start-to-end simulations of optical-pump, X-ray-probe laser-solid interactions with the photon scattering code ParaTAXIS. The associated PIC simulations guided the planning and execution of an LCLS experiment, demonstrating the first observation of solid-density plasma distribution driven by near-relativistic short-pulse laser pulses at femtosecond-nanometer resolution.

Keywords: laser ion acceleration; TNSA; particle-in-cell; PIConGPU; Smilei; temporal laser contrast; SAXS; ParaTAXIS; HPC

  • Doctoral thesis
    TU Dresden, 2022
    Mentor: Thomas Kluge
    193 Seiten
  • Open Access Logo Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-124 2023
    ISSN: 2191-8708, eISSN: 2191-8716

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Permalink: https://www.hzdr.de/publications/Publ-34551


Membrane-free alkali metal - iodide battery with a molten salt

Lee, J.; Monrrabal Marquez, G.; Sarma, M.; Lappan, T.; Hofstettet, Y. J.; Trtik, P.; Landgraf, S.; Ding, W.; Kumar, S.; Vaynzof, Y.; Weber, N.; Weier, T.

Abstract

Batteries with liquid metal electrodes are attractive candidates for sustainable
energy storage applications due to low manufacturing cost as well as high recyclability. For
broad applications, these batteries should be developed for lower operating temperature,
higher cell voltage, and membrane-free cell configuration. Here, we demonstrate a new type
of membrane-free electrochemical energy storage system relying on liquid alkali metals and
iodide. As a proof-of-concept study, membrane-free alkali metal-iodide (A-AI) batteries were
constructed by a facile cell assembly introducing current collectors, LiI-LiCl-KI-CsI salt mixture,
and an insulator without relying on solid-state mediums for separating electrolytes. For the
initial assembly, no active electrode materials were required since they can be naturally
formed during battery operation. Despite the unoptimized cell construction, the membrane-
free A-AI batteries showed promising electrochemical performance such as voltage efficiency
of ca. 40 % at 500 mA/cm2, maximum specific energy of 34.2 Wh/kg with an energy efficiency
of 59 % for a charging/discharging period of 5.8 h and reliable stability for 250 cycles. Even
without ion-selective membranes, we observed a relatively low self-discharge rate of
3.56 mA/cm2, which implies the possibility of an iodine-concentrated layer at the bottom of
the cell. This was further supported by post-mortem analyses using neutron radiography.
Additionally, X-ray photoemission spectroscopy was performed to identify the changes in the
iodine concentration in the cell.

Keywords: liquid metal batteries; alkali metal-iodide batteries; liquid metal electrodes; low-temperature molten salt; membrane-free energy storage; neutron radiography

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Top-down fabrication of silicon photonic structures for hosting single-photon emitters

Jagtap, N.; Hollenbach, M.; Fowley, C.; Berencen, Y.; Lee, W.; Astakhov, G.; Erbe, A.; Helm, M.

Abstract

Silicon, the ubiquitous material for computer chips, has recently been shown to be instrumental for hosting sources of single-photons emitting in the strategic optical telecommunication O-band (1260-1360 nm)[1], the so-called G center. To increase the brightness and the photon extraction efficiency of single G center, the coupling of these centers into photonic structures is strong. This work presents a top-down approach avoiding the use of ion beam-based etching methods for fabricating high-quality defect-free photonic structures such as silicon nanopillars, which can host singlephoton emitters. This method builds upon a wet-chemical process known as metal-assisted chemical etching. We report the successful fabrication of two-dimensional arrays of vertically-directed waveguiding silicon nanopillars. We also show the etch chemistry dependence on the Si wafer resistivity along with its effect on the etch rate and the sidewall roughness of pillars for a variety of pillar diameters.
References:[1] M. Hollenbach, et al. Opt. Express 28,26111-26121

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    virtual DPG-Frühjahrstagungen (DPG Spring Meetings) 2021, 27.-30.09.2021, Online, Germany

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Top down Fabrication of Silicon Photonic Structures by Metal Assisted Chemical Etching

Jagtap, N.

Abstract

Silicon, the ubiquitous material for computer chips, has recently been shown to be instrumental for hosting sources of single-photons emitting in the strategic optical telecommunication O-band (1260-1360 nm)[1], the so-called G center. To increase the brightness and the photon extraction efficiency of single G center, the coupling of these centers into photonic structures is strong.
This work presents a top-down approach avoiding the use of ion beam-based etching methods for fabricating high-quality defect-free photonic structures such as silicon nanopillars, which can host single photon emitters. This method builds upon a wet-chemical process known as MACEtch. We report the successful fabrication of two-dimensional arrays of vertically directed wave guiding silicon nanopillars. The confocal microscopy after carbon ion implantation shows presence of ensembles of G centers.

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  • Open Access Logo Lecture (Conference)
    NANONET Annual Workshop 2021, 21.-23.09.2021, Klingenberg, Germany

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Copper-free Click Labeling with the 99mTc-Tricarbonyl-Core Using DACN Derivatives

Schlesinger, M.; Jentschel, C.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.

Abstract

Diazacyclononyne (DACN) derivatives belong to the class of diazamacrocycles containing a strained alkyne bond. Therefore, DACNs are predestinated starting materials to be applied in copper-free strain-promoted click labeling with azide-functionalized bio(macro)molecules. The diazamacrocyclic scaffold is easy to prepare via a double Nicholas reaction. The following functionalization is convenient by the use of functionalized sulfonamides or by the alkylation of the secondary amines provided by the molecule.
To make the DACN derivatives suitable for radiolabeling with technetium-99m, two dipicolylamine (DPA) derivatives were prepared allowing the use of the 99mTc-tricarbonyl core. The first DPA-ligand is functionalized with an activated ester to allow convenient labeling of, e.g., amines. The second is based on the DACN macrocycle, allowing the copper-free click labeling. Two PSMA-binding derivatives based on PSMA-617 were chosen for final radiolabeling, one with a terminal amine function the other with an azide function.
For the conventional radiolabeling with e.g. primary amines, the DPA chelator was functionalized with a benzoate moiety which was further transferred into the corresponding activated TFP ester using tetrafluorophenol in three steps and an overall yield of 64%. For the click labeling procedure, the functionalized DACN macrocycle was prepared from a sulfonyl-modified diamide (4 steps) which was reacted with butyne-1,3-diol under Nicholas conditions. Finally, the DPA moiety was connected to the DACN via the propylsulfonyl linker. Both derivatives were reacted with (Et4N)2[ReBr3(CO)3] in methanol to obtain both reference complexes (natRe-DPA-TFP ester: 91% yield, natRe-DPA-DACN: 76% yield).
[99mTc][Tc(CO)3]+ was prepared according to an established protocol using 99mTc-pertechnetate and K2[H3BCO2] (in-house-produced tricarbonyl kit). Prior to its use, the solution was brought to pH 5.5 using MES buffer. The radiolabeling of the DPA-TFP derivative was accomplished with [99mTc][Tc(CO)3]+ at 40°C for 30 min in MES buffer (pH 5.5) obtaining the 99mTc-DPA-TFP ester with a radiochemical yield of 89%. The DPA-DACN derivative was labeled under the same conditions yielding 99mTc-DPA-DACN with 83% RCY. The connection of the 99mTc-labeled TFP ester to the primary amine of the PSMA targeting derivative was realized with 23% RCY at 100°C after 2.5 hours. Two additional by-products were observed by radio-HPLC indicating hydrolysis of the 99mTc-DPA-TFP ester. In contrast, by-products were not found using the click reaction of the 99mTc-labelled DPA-DACN-derivative for the conjugation with the azide-functionalized PSMA derivative. The labeling was performed using the same conditions, leading to 79% RCY after 4 hours. Both 99mTc-radiolabeled DPA-building blocks and both 99mTc-PSMA targeting derivatives were evidenced by comparison of the retention times of their respective natRe-derivatives.

Keywords: technetium-99m; click; tricarbonyl

  • Open Access Logo Poster
    TERACHEM 2022, 14.-17.09.2022, Bressanone, Italien

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Biohydrometallurgy in e-waste recycling

Lederer, F.

Abstract

E-waste recycling starts to focus more on biological methods that are developed in only a few institutes. The Biotechnology devision at Helmholtz Institute Freiberg for Resource Technology focusses on three main research approaches called bioflotation, biosorption and bioleaching. All these techniques and examples out of litereature and the lab are shown in this lecture.

Keywords: biomolecules; bacteria; e-waste; siderophores; peptides

  • Invited lecture (Conferences) (Online presentation)
    Urban mining lectures, 25.3.2022, Vancouver, Canada

Permalink: https://www.hzdr.de/publications/Publ-34546


Syntetic Spectra Data used in publication "Differential evolution optimization of Rutherford back-scattering spectra"

Heller, R.; Meersschaut, J.; Claessens, N.; Merckling, C.; Klingner, N.

Abstract

The zip-file contains all synthetic spectra as used for and  described in the publication "Differential evolution optimization of Rutherford back-scattering spectra" and all simulation input files for the code RUTHELDE presented therein. Naming according to the text in the paper. All files are in human readable ASCII format. The simulation input files can be best viewed with any kind of JSON file editor.

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Enhanced blood retention and tumor uptake of PSMA-targeting, 225Ac-labeled radioconjugates

Reissig, F.; Zarschler, K.; Ludik, M.-C.; Novy, Z.; Petrik, M.; Bendova, K.; Kurfürstova, D.; Bouchal, J.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.

Abstract

Objectives
The prostate-specific membrane antigen (PSMA) is expressed in most cases of prostate cancer at considerably higher levels in tumor cells compared to healthy tissues [1-3] and its upregulation occurs in all stage of the disease [4, 5]. Therefore, PSMA has emerged as an attractive target for molecular imaging and especially targeted radionuclide therapy (endoradiotherapy) of metastatic castration-resistant prostate cancer (mCRPC), given the example of [177Lu]Lu-PSMA-617. We recently described the synthesis and in-depth characterization of PSMA radioligands for targeted alpha therapy with actinium-225 [6]. Our present study aimed at the design, synthesis and preclinical evaluation of albumin-binding PSMA ligands in order to optimize their tissue distribution profile and to improve their pharmacokinetic properties.

Methods
Two novel compounds were prepared by combining a macropa chelator with one or two lysine-ureido-glutamate–based PSMA-binding entities equipped with 4-(p-iodophenyl)butyrate residues. The albumin-binding properties of the 225Ac-labeled conjugates were investigated in vitro using mouse, rat and human serum. The specific interaction of both compounds with human serum albumin was confirmed by microscale thermophoresis. Cell culture-based studies regarding radioligand affinity and clonogenicity were performed on PSMA-positive LNCaP cells. The biodistribution of the radioconjugates was analyzed in LNCaP tumor-bearing mice with ensuing investigation of tissue toxicity by histological examinations.

Results
Radiolabeling of both PSMA ligands with 225Ac was achieved at up to 5 MBq/nmol with >99% radiochemical purity. In vitro assays confirmed considerable binding of the radioligands to mouse, rat and human serum proteins. Cell binding and survival studies revealed a higher cell binding affinity and an improved cell killing efficiency for the radioconjugate with two PSMA-binding entities compared to the derivative with only one targeting motif. Biodistribution studies revealed enhanced blood circulation times of the new albumin-binding PSMA ligands compared to their counterparts lacking the 4-(p-iodophenyl)butyrate residues as well as substantially higher accumulation in LNCaP tumors up to 50 %ID/g (one PSMA-binding moiety) and 150 %ID/g (two PSMA-binding moieties), respectively, after 120 h p.i. Considerable DNA damage and a massive decrease in cell proliferation was observed by histological examination of LNCaP tumors, whereas necrosis in the kidneys of the animals was not detected.

Conclusions
In this study, we demonstrate the development and evaluation of two new PSMA-targeting radioligands comprising 4-(p-iodophenyl)butyrate residues as albumin binder. The prolonged blood circulation of the novel radioligands resulted in greatly enhanced tumor uptake and retention over time. These radioconjugates have the potential to improve the efficacy of targeted alpha therapy and are promising candidates for the treatment of mCRPC.

Keywords: targeted alpha therapy; actinium-225; albumin binder

  • Lecture (Conference)
    24th International Symposium on Radiopharmaceutical Sciences, 29.05.-02.06.2022, Nantes, Frankreich
  • Abstract in refereed journal
    Nuclear Medicine and Biology 108-109(2022), S30-S31
    DOI: 10.1016/S0969-8051(22)00103-2

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Multi-Center Magnon Excitations Open the Entire Brillouin Zone to Terahertz Magnetometry of Quantum Magnets

Biesner, T.; Roh, S.; Razpopov, A.; Willwater, J.; Süllow, S.; Li, Y.; Zoch, K. M.; Medarde, M.; Nuss, J.; Gorbunov, D.; Scurschii, I.; Pustogow, A.; Brown, S. E.; Krellner, C.; Valenti, R.; Puphal, P.; Dressel, M.

Abstract

Due to the small photon momentum, optical spectroscopy commonly probes magnetic excitations only at the center of the Brillouin zone; however, there are ways to override this restriction. In case of the distorted kagome quantum magnet Y-kapellasite, Y3Cu9(OH)19Cl8, under scrutiny here, the spin (magnon) density of states (SDOS) can be accessed over the entire Brillouin zone through three-center magnon excitations. This mechanism is aided by the three different magnetic sublattices and strong short-range correlations in the distorted kagome lattice. The results of THz time-domain experiments agree remarkably well with linear spin-wave theory (LSWT). Relaxing the conventional zone-center constraint of photons gives a new aspect to probe magnetism in matter.

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  • High Magnetic Field Laboratory (HLD)

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Commensurate helicoidal order in the triangular layered magnet Na2MnTeO6

Kurbakov, A. I.; Susloparova, A. E.; Pomjakushin, V. Y.; Skourski, Y.; Vavilova, E. L.; Vasilchikova, T. M.; Raganyan, G. V.; Vasiliev, A. N.

Abstract

The trigonal layered quaternary tellurate Na2MnTeO6 has been studied by means of various techniques to clarify its magnetic properties. The crystal structure of this compound is based on the triangular arrangement of all cations in the parallel layers with the space group P31c. By using symmetry analysis of the magnetic neutron scattering data, we have found that the solution for the magnetic structure corresponds to the magnetic Shubnikov group R3´c´ (No. 167.4.1337). Mn4+ ions in an octahedral environment form a triangular network where all spins are directed from the center of each triangle. Overall magnetic structure in Na2MnTeO6 is commensurate 120° spin helix with propagation vector k = (1/3, 1/3, 1/3) in variance with planar spin structure in structurally equivalent Li2MnTeO6 with magnetic propagation vector k = (1/3, 1/3, 0). The magnetization measurements show that Na2MnTeO6 experiences an antiferromagnetic order at TN = 5.5 K. NMR, electron spin resonance, and thermodynamics experiments demonstrate the extended temperature region of 2D short-range correlations well above the ordering temperature.

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  • High Magnetic Field Laboratory (HLD)

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Alteration of Mitochondrial Integrity as Upstream Event in the Pathophysiology of SOD1-ALS

Günther, R.; Pal, A.; Williams, C.; Zimyanin, V. L.; Liehr, M.; von Neubeck, C.; Krause, M.; Parab, M. G.; Petri, S.; Kalmbach, N.; Marklund, S. L.; Sterneckert, J.; Munch Andersen, P.; Wegner, F.; Gilthorpe, J. D.; Hermann, A.

Abstract

Little is known about the early pathogenic events by which mutant superoxide dismutase 1 (SOD1) causes amyotrophic lateral sclerosis (ALS). This lack of mechanistic understanding is a major barrier to the development and evaluation of efficient therapies. Although protein aggregation is known to be involved, it is not understood how mutant SOD1 causes degeneration of motoneurons (MNs). Previous research has relied heavily on the overexpression of mutant SOD1, but the clinical relevance of SOD1 overexpression models remains questionable. We used a human induced pluripotent stem cell (iPSC) model of spinal MNs and three different endogenous ALS-associated SOD1 mutations (D90Ahom, R115Ghet or A4Vhet) to investigate early cellular disturbances in MNs. Although enhanced misfolding and aggregation of SOD1 was induced by proteasome inhibition, Cells 2022, it was not affected by activation of the stress granule pathway. Interestingly, we identified loss of mitochondrial, but not lysosomal, integrity as the earliest common pathological phenotype, which preceded elevated levels of insoluble, aggregated SOD1. A super-elongated mitochondrial morphology with impaired inner mitochondrial membrane potential was a unifying feature in mutant SOD1 iPSC-derived MNs. Impaired mitochondrial integrity was most prominent in mutant D90Ahom MNs, whereas both soluble disordered and detergent-resistant misfolded SOD1 was more prominent in R115Ghet and A4Vhet mutant lines. Taking advantage of patient-specific models of SOD1-ALS in vitro, our data suggest that mitochondrial dysfunction is one of the first crucial steps in the pathogenic cascade that leads to SOD1-ALS and also highlights the need for individualized medical approaches for SOD1-ALS.

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  • High Magnetic Field Laboratory (HLD)

Permalink: https://www.hzdr.de/publications/Publ-34541


Hot Hydride Superconductivity Above 550 K

Grockowiak, A. D.; Ahart, M.; Helm, T.; Coniglio, W. A.; Kumar, R.; Glazyrin, K.; Garbarino, G.; Meng, Y.; Oliff, M.; Williams, V.; Ashcroft, N. W.; Hemley, R. J.; Somayazulu, M.; Tozer, S. W.

Abstract

The search for room temperature superconductivity has accelerated in the last few years driven by experimentally accessible theoretical predictions that indicated alloying dense hydrogen with other elements could produce conventional superconductivity at high temperatures and pressures. These predictions helped inform the synthesis of simple binary hydrides that culminated in the discovery of the superhydride LaH10 with a superconducting transition temperature Tc of 260 K at 180 GPa. We have now successfully synthesized a metallic La-based superhydride with an initial Tc of 294 K. When subjected to subsequent thermal excursions that promoted a chemical reaction to a higher order system, the Tc onset was driven irreversibly to 556 K. X-ray characterization confirmed the formation of a distorted LaH10 based backbone that suggests the formation of ternary or quaternary compounds with substitution at the La and/or H sites. The results provide evidence for hot superconductivity, aligning with recent predictions for higher order hydrides under pressure.

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  • High Magnetic Field Laboratory (HLD)

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Data to "Application of a fluorescence anisotropy-based assay to quantify transglutaminase 2 activity in cell lysates"

Hauser, S.; Sommerfeld, P.; Wodtke, J.; Hauser, C.; Schlitterlau, P.; Pietzsch, J.; Löser, R.; Pietsch, M.; Wodtke, R.

Abstract

Primärdaten zum FA-Assay, activity-based ELISA und ELISA

Keywords: activity-based protein profiling; cancer; ELISA; enzyme assay; transamidase activity

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Permalink: https://www.hzdr.de/publications/Publ-34539


Data Publication: Tuning of Curie temperature in Mn5Ge3 films

Xie, Y.; Birowska, M.; Funk, S. H.; Fischer, A. I.; Schwarz, D.; Schulze, J.; Zeng, Y.-J.; Helm, M.; Zhou, S.; Prucnal, S.

Abstract

This contains a set of data that were used to generate the figures and results in the manuscripts: Tuning of Curie temperature in Mn5Ge3 films (DOI: 10.1063/5.0066717).

The compressed folders “Curie temperature in Mn5Ge3 films ” contain below data:

  • RBS data
  • MH data
  • ZFC/FC data
  • XRD data

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Localization and chemical speciation of europium(III) in Brassica napus plants

Jessat, J.; John, W.; Moll, H.; Vogel, M.; Steudtner, R.; Drobot, B.; Hübner, R.; Stumpf, T.; Sachs, S.

Abstract

For the reliable safety assessment of repositories of highly radioactive waste, further development of the modelling of radionuclide migration and transfer in the environment is necessary, which requires a deeper process understanding at the molecular level. Eu(III) is a non-radioactive analogue for trivalent actinides, which contribute heavily to radiotoxicity in a repository. For in-depth study of the interaction of plants with trivalent f elements, we investigated the uptake, speciation, and localization of Eu(III) in Brassica napus plants at two concentrations, 30 and 200 µM, as a function of the incubation time up to 72 h. Eu(III) was used as luminescence probe for combined microscopy and chemical speciation analyses of it in Brassica napus plants. The localization of bioassociated Eu(III) in plant parts was explored by spatially resolved chemical microscopy. Three Eu(III) species were identified in the root tissue. Moreover, different luminescence spectroscopic techniques were applied for an improved Eu(III) species determination in solution. In addition, transmission electron microscopy combined with energy-dispersive X-ray spectroscopy was used to localize Eu(III) in the plant tissue, showing Eu-containing aggregates. By using this multi-method setup, a profound knowledge on the behavior of Eu(III) within plants and changes in its speciation could be obtained, showing that different Eu(III) species occur simultaneously within the root tissue and in solution.

Keywords: lanthanides; plants; laser spectroscopy; speciation; chemical microscopy; localization

Permalink: https://www.hzdr.de/publications/Publ-34537


10Be at iThemba LABS using a silicon nitride membrane stack as absorber for isobar suppression

Winkler, S.; Mbele, V.; Khosa, R.; Corbett, L.; Bierman, P.; Hidy, A.; Brown, T.; Makhubela, T.; Kramers, J.; Tooth, S.

Abstract

10Be is an important isotope for accelerator mass spectrometry (AMS) because of the demand for cosmogenic radionuclide dating methods in the earth science and paleo-sciences community. At the iThemba Laboratory for Accelerator Based Science (iThemba LABS) we implemented full suppression of the interfering isobar 10B using a silicon nitride foil-stack, utilizing the 2+ charge state for high efficiency. We demonstrate the performance of this newly established AMS system using standards and test samples. We further present the results of an inter-comparison between iThemba LABS and the Center for Accelerator Mass Spectrometry/Lawrence Livermore National Laboratory, on AMS samples prepared from purified quartz at the University of Vermont. The results for 10Be from the laboratories are in close agreement, fully consistent with cross-calibration between them. AMS results for 26Al are in similarly good agreement, demonstrating the performance and accuracy of iThemba LABS for the most commonly measured in situ produced cosmogenic nuclides.

Permalink: https://www.hzdr.de/publications/Publ-34536


Towards perfectly linearly polarized x-rays

Schulze, K. S.; Grabiger, B.; Loetzsch, R.; Marx-Glowna, B.; Schmitt, A. T.; Laso García, A.; Hippler, W.; Huang, L.; Karbstein, F.; Konôpková, Z.; Schlenvoigt, H.-P.; Schwinkendorf, J.-P.; Strohm, C.; Toncian, T.; Uschmann, I.; Wille, H.-C.; Zastrau, U.; Röhlsberger, R.; Stöhlker, T.; Cowan, T.; Paulus, G. G.

Abstract

In recent years, high-precision x-ray polarimeters have become a key method for the investigation of fundamental physical questions from solid-state physics to quantum optics. Here, we report on the verification of a polarization purity of better than 8×10−11 at an x-ray free-electron laser, which implies a suppression of the incoming photons to the noise level in the crossed polarizer setting. This purity provides exceptional sensitivity to tiny polarization changes and offers intriguing perspectives for fundamental tests of quantum electrodynamics.

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  • HIBEF

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Peptidoglycan as major binding motif for Uranium bioassociation on Magnetospirillum magneticum AMB-1 in contaminated waters

Krawczyk-Bärsch, E.; Ramtke, J.; Drobot, B.; Müller, K.; Steudtner, R.; Kluge, S.; Hübner, R.; Raff, J.

Abstract

The mining and industrial use of heavy metals lead to locally high heavy metal contamination with serious consequences for the environment and local population. The high potential of biological remediation processes, in particular, the use of magnetotactic bacteria of heavy metal and radionuclide-contaminated waters has recently been discussed. Yet, the molecular reactions involved in the uptake of radionuclides, especially U, by these bacteria are unknown. The present work is a multidisciplinary approach combining wet chemistry, microscopy, and spectroscopy methods. Our findings suggest that the cell wall plays a prominent role in the bioassociation of U(VI). In time-dependent bioassociation studies, up to 95 % of the initial U(VI) was removed from the suspension within the first hours by Magnetospirillum magneticum AMB-1. PARAFAC analysis of TRLFS data highlights that peptidoglycan is the most important ligand involved, showing a stable immobilization of U(VI) over a wide pH range with the formation of three characteristic species. In addition, in-situ ATR FT-IR reveals the predominant binding to carboxylic functionalities, at higher pH polynuclear species seem to play an important role. This comprehensive molecular study may initiate in future new remediation strategies on effective immobilization of U in combination with the bacteria´s magnetic properties.

Keywords: Magnetotactic bacteria; Uranium; Spectroscopy; Microscopy; Bioremediation

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Convolutional neural networks predict the linear energy transfer for proton-beam radiotherapy of patients with brain tumours

Starke, S.; Eulitz, J.; Zwanenburg, A.; Troost, E. G. C.; Krause, M.; Lühr, A.; Löck, S.

Abstract

Proton therapy is a promising option for cancer treatment, even though its radiobiological properties are not yet fully considered in clinical practice. In this context, the relative biological effectiveness (RBE) of protons is the most important quantity, which is strongly related to their linear energy transfer (LET). LET distributions can be provided by commercial treatment-planning systems based on Monte Carlo simulations. However, such systems require a considerable amount of computational resources, are not yet available in every proton-therapy centre and may not be applicable to assess retrospective patient data. Here, we provide proof-of-concept for inferring LET distributions using convolutional neural networks (CNN) based on proton therapy radiation dose distributions and treatment-planning computed tomography (CT). We further evaluate established models for estimating treatment-related side effects after proton therapy of brain tumours and observe good agreement between CNN and MC based outputs.

Keywords: proton therapy; linear energy transfer; relative biological effectiveness; convolutional neural networks

  • Open Access Logo Lecture (Conference)
    MIDL 2022 - Medical Imaging with Deep Learning, 06.-08.07.2022, Zürich, Schweiz

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Permalink: https://www.hzdr.de/publications/Publ-34533


The European Particle Therapy Network (EPTN) consensus on the follow-up of adult patients with brain and skull base tumours treated with photon or proton irradiation

de Roeck, L.; van der Weide, H.; Eekers, D.; Kramer, M.; Alapetite, C.; Bromstrand, M.; Burnet, N.; Calugaru, V.; Coremans, I.; Di Perri, D.; Harrabi, S.; Innalfi, A.; Klaver, Y.; Langendijk, J.; Méndez Romero, A.; Paulsen, F.; Roelofs, E.; de Ruysscher, D.; Timmermann, B.; Vitek, P.; Weber, D.; Whitfield, G.; Witt Nyström, P.; Zindler, J.; Troost, E. G. C.; Lambrecht, M.

Abstract

Purpose: Treatment-related toxicity after irradiation of brain tumours has been underreported in the lit-
erature. Furthermore, there is considerable heterogeneity on how and when toxicity is evaluated. The aim
of this European Particle Network (EPTN) collaborative project is to develop recommendations for uni-
form follow-up and toxicity scoring of adult brain tumour patients treated with radiotherapy.
Methods: A Delphi method-based consensus was reached among 24 international radiation-oncology
experts in the field of neuro-oncology concerning the toxicity endpoints, evaluation methods and time
points.
Results: In this paper, we present a basic framework for consistent toxicity scoring and follow-up, using
multiple levels of recommendation. Level I includes all recommendations that are considered minimum
of care, whereas level II and III are optional evaluations in the advanced clinical or research setting,
respectively. Per outcome domain, the clinical endpoints and evaluation methods per level are listed.
Where relevant, the organ at risk threshold doses for recommended referral to specific organ specialists
are defined.

Keywords: European Particle Therapy Network; Particle therapy; Follow-up; Toxicity; Brain tumour; Skull base tumour; Central nervous system

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Permalink: https://www.hzdr.de/publications/Publ-34532


Subjective memory impairment in glioma patients with curative radiotherapy

Donix, M.; Seidlitz, A.; Buthut, M.; Löck, S.; Meissner, G.; Matthes, C.; Troost, E. G. C.; Baumann, M.; Raschke, F.; Linn, J.; Krause, M.

Abstract

Background: Radiotherapy in patients with primary brain tumors may affect hippocampal structure and
cause dyscognitive side-effects.
Patients and methods: Using structural MRI and comprehensive neurocognitive evaluation, we investi-
gated associations between hippocampal structure and memory deficits in 15 patients with WHO grade
3 and grade 4 gliomas receiving standard radio(chemo)therapy.
Results: We did not find changes in hippocampal thickness or cognitive abilities three months after com-
pleting radiotherapy. However, subjective memory impairment was associated with symptoms of
depression, but not with objective memory performance, cortical thickness of the hippocampus or radi-
ation dose.
Conclusions: Irrespective of whether there is a bidirectional relationship between affective changes and
subjective cognitive dysfunction in these patients, depressive symptoms remain a target for intervention
to improve their quality of life. The results of our pilot study highlight that future assessment of side
effects of radiotherapy concerning memory should include assessments of depressive symptoms.

Keywords: radiotherapy; hippocampus; MRI; neurocognitive evaluation; subjective memory impairment

Permalink: https://www.hzdr.de/publications/Publ-34531


Development and functional characterization of a versatile radio-/immunotheranostic tool for prostate cancer management

Arndt, C.; Bergmann, R.; Striese, F.; Merkel, K.; Máthé, D.; Loureiro, L. R.; Mitwasi, N.; Kegler, A.; Fasslrinner, F.; González Soto, K. E.; Neuber, C.; Berndt, N.; Kovács, N.; Szöllősi, D.; Hegedűs, N.; Tóth, G.; Emmermann, J.-P.; Harikumar, K. B.; Kovacs, T.; Bachmann, M.; Feldmann, A.

Abstract

Due to its overexpression on the surface of prostate cancer (PCa) cells, the prostate stem cell antigen (PSCA) is a potential target for PCa diagnosis and therapy. Here we describe the development and functional characterization of a novel IgG4-based anti-PSCA antibody (Ab) derivative (anti-PSCA IgG4-TM) that is conjugated with the chelator DOTAGA. The anti-PSCA IgG4-TM represents a multimodal immunotheranostic compound that can be used (i) as target module (TM) for UniCAR T cell-based immunotherapy, (ii) for diagnostic PET imaging, and (iii) targeted alpha therapy. Cross-linkage of UniCAR T cells and PSCA-positive tumor cells via the anti-PSCA IgG4-TM results in efficient tumor cell lysis both in vitro and in vivo. After radiolabeling with 64Cu2+ the anti-PSCA IgG4-TM was successfully applied for high contrast PET imaging. In a PCa mouse model, it showed specific accumulation in PSCA-expressing tumors, while no uptake in other organs was observed. Additionally, the DOTAGA-conjugated anti-PSCA IgG4-TM was radiolabeled with 225Ac3+ and applied for targeted alpha therapy. A single injection of the 225Ac-labeled anti-PSCA IgG4-TM was able to significantly control tumor growth in experimental mice. Overall, the novel anti-PSCA IgG4-TM represents an attractive first member of a novel group of radio-/immunotheranostics that allows diagnostic imaging, endoradiotherapy, and CAR T cell immunotherapy.

Keywords: prostate cancer; PSCA; PSMA; IgG4; CAR T cell; theranostics; Ac-225; Cu-64; (18)F-JK-PSMA-7

Permalink: https://www.hzdr.de/publications/Publ-34530


Mu2e-II: Muon to electron conversion with PIP-II Contributed paper for Snowmass

Byrum, K.; Corrodi, S.; Oksuzian, Y.; Winter, P.; Xia, L.; Edmonds, A. W. J.; Miller, J. P.; Mott, J.; Marciano, W. J.; Szafron, R.; Bonventre, R.; Brown, D. N.; Kolomensky, Y. G.; Ning, O.; Singh, V.; Prebys, E.; Borrel, L.; Echenard, B.; Hitlin, D. G.; Hu, C.; Lin, D. X.; Middleton, S.; Porter, F. C.; Zhang, L.; Zhu, R.-Y.; Ambrose, D.; Badgley, K.; Bernstein, R. H.; Boi, S.; Casey, B. C. K.; Culbertson, R.; Gaponenko, A.; Glass, H. D.; Glenzinski, D.; Goodenough, L.; Hocker, A.; Kargiantoulakis, M.; Kashikhin, V.; Kiburg, B.; Kutschke, R. K.; Murat, P. A.; Neuffer, D.; Pronskikh, V. S.; Pushka, D.; Rakness, G.; Strauss, T.; Yucel, M.; Bloise, C.; Diociaiuti, E.; Giovannella, S.; Happacher, F.; Miscetti, S.; Sarra, I.; Martini, M.; Ferrari, A.; Müller, S.; Rachamin, R.; Barlas-Yucel, E.; Artikov, A.; Atanov, N.; Davydov, Y. I.; Glagolev, V.; Vasilyev, I. I.; Brown, D. N.; Uesaka, Y.; Denisov, S. P.; Evdokimov, V.; Kozelov, A. V.; Popov, A. V.; Vasilyev, I. A.; Tassielli, G.; Teubner, T.; Chislett, R. T.; Hesketh, G. G.; Lancaster, M.; Campbell, M.; Ciampa, K.; Heller, K.; Messerly, B.; Cummings, M. A. C.; Calibbi, L.; Blazey, G. C.; Syphers, M. J.; Zutshi, V.; Kampa, C.; Mackenzie, M.; Di Falco, S.; Donati, S.; Gioiosa, A.; Giusti, V.; Morescalchi, L.; Pasciuto, D.; Pedreschi, E.; Spinella, F.; Hedges, M. T.; Jones, M.; You, Z. Y.; Zanetti, A. M.; Valetov, E. V.; Dukes, E. C.; Ehrlich, R.; Group, R. C.; Heeck, J.; Hung, P. Q.; Demers, S. M.; Pezzullo, G.; Lynch, K. R.; Popp, J. L.

Abstract

An observation of Charged Lepton Flavor Violation (CLFV) would be unambiguous evidence for
physics beyond the Standard Model. The Mu2e and COMET experiments, under construction, are
designed to push the sensitivity to CLFV in the μ → e conversion process to unprecedented levels.
Whether conversion is observed or not, there is a strong case to be made for further improving
sensitivity, or for examining the process on additional target materials. Mu2e-II is a proposed
upgrade to Mu2e, with at least an additional order of magnitude in sensitivity to the conversion
rate over Mu2e. The approach and challenges for this proposal are summarized. Mu2e-II may be
regarded as the next logical step in a continued high-intensity muon program at FNAL

Keywords: CLFV; MU2E; FNAL; Snowmass

Permalink: https://www.hzdr.de/publications/Publ-34527


Data publication: Epitaxial lateral overgrowth of tin spheres driven and directly observed by helium ion microscopy

Klingner, N.; Heinig, K.-H.; Tucholski, D.; Möller, W.; Hübner, R.; Bischoff, L.; Hlawacek, G.; Facsko, S.

Abstract

Raw data for the publication: "Epitaxial lateral overgrowth of tin spheres driven and directly observed by helium ion microscopy". It contains helium ion microscopy, transmission electron microscopy, scanning electron microscopy as well as gallium focused ion microscopy images and XPS data. It shows how the irradiation of tin spheres with keV He ions causes epitaxial lateral overgrowth.

Keywords: helium ion microscope; tin whisker growth; defect kinetics

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Permalink: https://www.hzdr.de/publications/Publ-34526


Epitaxial lateral overgrowth of tin spheres driven and directly observed by helium ion microscopy

Klingner, N.; Heinig, K.-H.; Tucholski, D.; Möller, W.; Hübner, R.; Bischoff, L.; Hlawacek, G.; Facsko, S.

Abstract

Enhanced interstitial diffusion in tin is a phenomenon often observed during ion-beam irradiation and in lead-free solders. For the latter, this
not very well understood, strain-driven mechanism results in the growth of whiskers, which can lead to unwanted shorts in electronic designs. In ion-beam physics, this phenomenon is often observed as a result of the enhanced formation of Frenkel pairs in the energetic collision cascade. Here, we show how epitaxial growth of tin extrusions on tin-oxide-covered tin spheres can be induced and simultaneously observed by implanting helium using a helium ion microscope. Calculations of collision cascades based on the binary collision approximation and 3D-lattice-kinetic Monte Carlo simulations show that the implanted helium will occupy vacancy sites, leading to a tin interstitial excess. Sputtering and phase separation of the tin oxide skin, which is impermeable for tin atoms, create holes and will allow the epitaxial overgrowth to start. Simultaneously, helium accumulates inside the irradiated spheres. Fitting the simulations to the experimentally observed morphology allows us to estimate the tin to tin-oxide interface energy to be 1.98 J m−2 . Our approach allows the targeted initiation and in situ observation of interstitial diffusion-driven effects to improve the understanding of the tin-whisker growth mechanism observed in lead-free solders.

Keywords: helium ion microscope; tin whisker growth; defect kinetics

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Permalink: https://www.hzdr.de/publications/Publ-34525


Development of Mechanistic Neural Mass (mNM) Models that Link Physiology to Mean-Field Dynamics

Tripathi, R.; Gluckman, B. J.

Abstract

Brain rhythms emerge from the mean-field activity of networks of neurons. There have been many efforts to build mathematical and computational embodiments in the form of discrete cell group activities termed neural masses to understand particular the origins of evoked potentials, intrinsic patterns of activities such as theta, regulation of sleep, Parkinson's disease related dynamics, and instabilities such as seizure dynamics. As originally utilized, standard neural masses convert input through a sigmoidal function to a firing rate, and firing rate through a synaptic alpha function to other masses. Here we define a process to build almost from first principles (i.e. Hodgkin Huxley type models) mean field models of different neuron types that duplicate the stability, firing rate, and associated bifurcations as function of relevant slow variables - such as extracellular potassium - and synaptic current; and whose output is both firing rate and impact on the slow variables - such as transmembrane potassium flux. Small networks composed of just excitatory and inhibitory masses demonstrate expected dynamical states including stable firing, runaway excitation and depolarization block, and these transitions change in biologically observed ways with changes in extracellular potassium and excitatory-inhibitory balance.

Keywords: Excitation-Inhibition imbalance; Depolarization Block; Neural Mass Model; Brain Networks; Pathophysiology

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Permalink: https://www.hzdr.de/publications/Publ-34523


Biogeographic Regionalization: Freshwater

Dias, M. S.; Oikonomou, A.; Su, G.

Abstract

Defining the number and geographical borders of regions containing similar organisms and high levels of endemism can shed light on the evolution and distribution of life on Earth. We provide an historical overview of studies delineating the global biogeographical regions of freshwater organisms, mainly focusing on fish, to understand whether aquatic and terrestrial organisms share similar distribution patterns. Then, we provide a geographical and biological description giving special attention to major biogeographical fish patterns and taxa present in each of the considered regions.

Permalink: https://www.hzdr.de/publications/Publ-34522


Modelling Cross-border Mobility During Disease Outbreak

Senapati, A.; Calabrese, J.

Abstract

Due to the COVID-19 pandemic various cross-border policies such as mandatory testing, quarantining upon arrival, travel restrictions have been implemented by the countries to minimize the risk of disease import. The strictness of these measures has varied over time. The aim of this study is twofold. First, we develop a spatially explicit SIR-type compartmental model to evaluate the impact of cross-border mobility between two countries on the disease dynamics under different epidemic conditions. We see a significant change in the time to reach the peak of infection if the cross-border mobility is permitted during disease outbreak. Moreover, our study shows that allowing cross-border mobility shortens the difference in peak timings in two countries in comparison to the scenario with no cross-border flux. Next, we present a method using stochastic simulation for estimating cross-border mobility flux between two regions from the difference in peak-timing in infection under some reasonable assumptions.

Keywords: Mathematical modelling; Infectious disease; COVID-19; Cross-border mobility; Compartmental modelling

  • Poster
    12th European Conference on Mathematical and Theoretical Biology, 19.-23.09.2022, Heidelberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-34521


Molten salt electrolyte in Na-ZnCl2 solid-electrolyte battery for electricity storage

Kumar, S.; Ding, W.; Bonk, A.; Heinz, M. V. F.; Weber, N.; Bauer, T.

Abstract

Increasing share of intermittent renewable energy resources such as PV and wind energy in the grid has led to increasing demand in grid-scale stationary storage batteries. The commercial ZEBRA (Na-NiCl2) batteries are one kind of low-cost stationary storage batteries, which have been developed in the past decades to increase their efficiency, safety and performance.

Replacing Ni with abundant and low-cost Zn (i.e., Na-ZnCl2 batteries) could make these batteries more cost-effective (cut down around 46 and 20% of the cell material and overall battery costs). Fig. 1 shows the material cost breakdown of Na–NiCl2 and Na-ZnCl2 batteries. Compared to ZEBRA battery (Ni: 63%), the Zn electrode in the Na-ZnCl2 battery has a much lower material cost share (Zn: 23%). Several studies have been done on these novel Na-ZnCl2 batteries, but there is still a lack of understanding for the electrolyte system (AlCl3-NaCl-ZnCl2) of the Na-ZnCl2 batteries in terms of melting temperature, phase changes and salt vapor pressures at various temperatures. These properties of the salt electrolyte are vital for the battery design and optimization.

In this work (as part of the SOLSTICE EU H2020 project for development of Na-ZnCl2 batteries), the simulation-assisted in-depth analysis on the AlCl3-NaCl-ZnCl2 salt electrolyte for the Na-ZnCl2 solid electrolyte batteries was performed via the thermodynamic software FactSage and thermo-analytical techniques like Differential Scanning Calorimetry (DSC) and OptiMeltTM. Moreover, an estimation model for the unit storage salt material cost (i.e., salt cost/storage capacity, $/kWh) was developed and used for the pre-optimization of this salt electrolyte.
The simulation and experimental results show that increasing the concentration of AlCl3 in the AlCl3-(NaCl)2-ZnCl2 salt mixture decreases the melting point significantly, which could enlarge the charge/discharge range of the battery. However, when containing more than 40 mol% AlCl3, the vapor pressure of the salt mixture could be above 1 atm at 300 °C. Thus, this factor is suggested to be considered in the electrolyte selection and battery operation for the battery safety. Moreover, the estimation results of the unit storage salt material cost in Fig. 2 indicate that as AlCl3 has a much higher cost than NaCl, increasing the concentration of AlCl3 in the AlCl3-(NaCl)2-ZnCl2 salt electrolyte from 5 to 50 mol% could increase the unit storage salt material cost from 0.2 to 2.8 $/kWh, when the salt electrolyte in the full discharged state and Zn metal are used as the starting cathode in the battery. However, when the salt contains a low concentration of AlCl3 (e.g., 5 mol%), the possibly low conductivity of the salt electrolyte due to its high melting temperature (small ratio of the liquid salt phase) could limit the battery performance. While the results of this study, such as the AlCl3-(NaCl)2-ZnCl2 phase diagramme, its vapour pressure and price will be very beneficial for preselecting possible salt compositions, the final selection will need to be made based on real battery tests and accounting for further issues, such as corrosion, as well. These experiments are currently under way.

  • Lecture (Conference)
    International Renewable Energy Storage Conference, 20.09.2022, Düsseldorf, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34520


Influence of surface roughness on the sorption of Cm(III) on crystalline-water interfaces

Demnitz, M.; Schymura, S.; Neumann, J.; Müller, K.; Schmidt, M.

Abstract

Many countries plan to use deep geological repositories to dispose of their highly radioactive nuclear waste. Internationally, crystalline rock is a potential host rock because of its strong geotechnical stability, low permeability and low solubility. After a potential water ingress into a nuclear waste repository, radionuclides might be mobilized in aqueous solution. The topographical surface features affect the speciation and therefore retention potential of radionuclides on the host rock. Therefore, there is a need for using sophisticated techniques that allow to characterize the nanostructure of such crystalline rock with spatial resolution and the molecular speciation of the actinides thereon. As a representative for trivalent actinides, such as Am(III), Np(III), and Pu(III), we have chosen the actinide Cm(III). It possesses excellent luminescence properties, allowing us to determine Cm(III) sorption uptake and molecular speciation.

Our investigations focused on cleaved orthoclase (K-feldspar) single crystals and thin slices of different crystalline rocks stemming from the Grimsel test site (GTS) in Switzerland. Cleaved pieces of orthoclase or thin sections of the crystalline rocks were immersed in a sorption solution containing Cm(III). The experiments were undertaken at selected pH values (5.5, 6.9 and 7.3) and different inherent mineralogical complexity of the systems. Subsequently, we applied correlated spectroscopy to analyze the samples. Thus, we were able to correlate mineralogy, topography, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters. [1, 2].

We observed that Cm(III) sorption uptake and speciation on orthoclase single crystals depends not exclusively on the mineral phase and the solution conditions, such as the pH, but also on the surface roughness. At pH 5.5 the sorption uptake differed between low and high surface roughness areas, while the speciation on both areas remained largely similar. Increasing the pH to 6.9 not only increased the overall sorption uptake, also the speciation between smoother and rougher surfaces differed. Using luminescence peak and lifetime analysis we could determine that the speciation is highly dependent on the availability on strong sorption sites. Based on our results we proposed a simple model for Cm(III) sorption on an orthoclase surface.

Further we compared the Cm(III) speciation on orthoclase singe crystals with orthoclase mineral grains on a thin section prepared from Grimsel specimen rock. The sorption was now influenced additionally by the presence of a heterogeneous surface, affecting the strength and form of surface sorbed Cm(III) species.

We conclude that in addition to mineral composition, surface roughness needs to be considered adequately by reactive transport models to describe interfacial speciation of contaminants and respective retention patterns for the safety assessments of nuclear waste repositories.

Acknowledgements:

This work has been developed in the frame of the iCross project. We gratefully acknowledge funding provided by the German Federal Ministry of Education and Research (BMBF, Grant 02NUK053) and the Helmholtz Association (Grant SO-093).

[1] Molodtsov et al. (2019): Sorption of Eu(III) on Eibenstock granite studied by µTRLFS: A novel spatially-resolved luminescence-spectroscopic technique – In: Scientific Reports, 9, Article Number 6287.

[2] Demnitz et al. (2021): Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock– In: Journal of Hazardous Materials, Volume 423, Part A , 127006.

Keywords: luminescence; speciation; Cm; crystal; interface; crystalline; roughness; topography; microscopy; spatial

  • Open Access Logo Lecture (Conference) (Online presentation)
    28. Tagung der Fachsektion Hydrogeologie e. V. in der DGGV e.V., 23.-25.03.2022, Jena, Germany

Permalink: https://www.hzdr.de/publications/Publ-34518


Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

Demnitz, M.; Molodtsov, K.; Schymura, S.; Schierz, A.; Müller, K.; Schmidt, M.

Abstract

Many countries will use deep geological repositories to dispose of highly active nuclear waste. Crystalline rock is a potential host rock because of its strong geotechnical stability, low permeability and low solubility; however, its inherent mineralogy is heterogeneous, consisting of a wide set of minerals in varying amounts. Therefore, there is a need for using sophisticated techniques that allow spatial resolution to characterize the nanostructure of such crystalline rock surfaces and the speciation of the actinides therein. As a representative for trivalent actinides, such as Am(III), Np(III), and Pu(III), which are expected to be present due to the reducing conditions encountered in a deep geological repository, we have chosen the actinide Cm(III). Cm(III) possesses excellent luminescence properties, which allows us to not only examine the sorption uptake but also the speciation of Cm(III) on the surface.

We combined spatially resolved investigation techniques, such as vertical scanning interferometry, calibrated autoradiography, and Raman microscopy coupled to micro-focus time-resolved laser-induced luminescence spectroscopy (µTRLFS) (Molodtsov et al., 2019). Thus, we were able to correlate mineralogy, surface roughness, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters.

Investigations focused on granite from Eibenstock (Germany) and migmatised gneiss from Bukov (Czech Republic). Cm(III) sorption on the rock's constituting minerals – primarily feldspar, mica and quartz – was analyzed quantitatively and qualitatively. We observed that Cm(III) sorption uptake and speciation depends not only on the mineral phase but also the surface roughness (Demnitz et al., 2021). An increasing surface roughness leads to higher sorption uptake and a stronger coordination of the sorbed Cm(III). On the same mineral grains sorption differed significantly depending if an area exhibits a low or high surface roughness. In the case that one mineral phase dominates the sorption process, sorption of Cm(III) on other mineral phases will only occur at strong binding sites, typically where surface roughness is high. Areas of feldspar and quartz with high surface roughness additionally showed the formation of sorption species with particularly high sorption strength that could either be interpreted as Cm(III) incorporation species or ternary complexes on the mineral surface (Demnitz et al., 2021).

We conclude that in addition to mineral composition, surface roughness needs to be adequately considered to describe interfacial speciation of contaminants and respective retention patterns for the safety assessments of nuclear waste repositories.

Demnitz, M., Molodtsov, K., Schymura, S., Schierz, A., Müller, K., Jankovsky, F., Havlova, V., Stumpf, T., and Schmidt, M.: Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock, J. Hazard. Mater. Pt. A, 423, 127006, https://doi.org/10.1016/j.jhazmat.2021.127006, 2021.  

Molodtsov, K., Schymura, S., Rothe, J., Dardenne, K., and Schmidt, M.: Sorption of Eu(III) on Eibenstock granite studied by µTRLFS: A novel spatially-resolved luminescence-spectroscopic technique, Sci. Rep.-UK, 9, 6287, https://doi.org/10.1038/s41598-019-42664-2, 2019. 

Keywords: luminescence; speciation; Cm; host rock; interface; crystalline; roughness; topography; microscopy; spatial

  • Open Access Logo Lecture (Conference)
    Interdisciplinary research symposium On the safety of nuclear disposal practices 2021, 10.-12.11.2021, Berlin, Germany
    DOI: 10.5194/sand-1-145-2021

Permalink: https://www.hzdr.de/publications/Publ-34517


Influence of surface roughness on the sorption of Cm(III)

Demnitz, M.; Schymura, S.; Neumann, J.; Müller, K.; Schmidt, M.

Abstract

INTRODUCTION

Many countries will use deep geological repositories to dispose of their highly radioactive nuclear waste. With an international perspective, crystalline rock is a potential host rock because of its strong geotechnical stability, low permeability and low solubility. However, its inherent mineralogy is heterogeneous, consisting of a wide set of minerals in varying amounts. Therefore, there is a need for using sophisticated techniques that allow to characterize the nanostructure of such crystalline rock surfaces with spatial resolution and the molecular speciation of the actinides thereon. As a representative for trivalent actinides, such as Am(III), Np(III), and Pu(III), which are expected to be present due to the reducing conditions encountered in a deep geological repository, we have chosen the actinide Cm(III). It possesses excellent luminescence properties, allowing us to determine sorption uptake and molecular speciation of Cm(III) on the surface.

DESCRIPTION OF THE WORK

Investigations focused on cleaved orthoclase (K-feldspar) single crystals as well as different crystalline rocks stemming from various regions in Europe. Cleaved pieces of orthoclase or thin sections of the crystalline rocks were immersed in a sorption solution containing [Cm(III)] = 5∙10-7 – 10-5 M. The experiments were undertaken at selected pH values (5.0 and 6.9) and different inherent mineralogical complexity of the systems. Subsequently, we applied correlated spectroscopy to analyze the samples. We combined vertical scanning interferometry, calibrated autoradiography, and Raman microscopy coupled to µTRLFS. Thus, we were able to correlate mineralogy, topography, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters. For experimental details, see [1].

RESULTS AND DISCUSSION

We observed that Cm(III) sorption uptake and speciation depends not only on the mineral phase, but also the surface roughness. Already on single crystal orthoclase an increasing surface roughness leads to higher sorption uptake (see Fig. 1) and to a stronger coordination of the sorbed Cm(III).
Increasing the mineral complexity of the system further, we used thin sections of various crystalline rocks, consisting mainly of feldspar, quartz, and mica. We observed significant differences in sorption uptake on individual mineral phases as well as the resulting speciation. In case that one mineral phase dominates the sorption process, e.g. amphibole, sorption of Cm(III) on other mineral phases will only occur at strong binding sites, typically where surface roughness is high. Areas of feldspar and quartz with high surface roughness additionally showed the formation of sorption species with particularly high sorption strength that could either be interpreted as Cm(III) incorporation species or adsorbed ternary complexes on the mineral surface.[2]
At pH values of around 6.8 Cm(III) generally sorbs more weakly to the surface, while preferentially targeting mineral phases such as mica instead of feldspar or quartz. At a higher pH of 8.0 the sorption uptake on other mineral phases increases, with a general trend towards more strongly bound Cm(III) surface species.
We conclude that in addition to mineral composition, surface roughness needs to be considered adequately by reactive transport models to describe interfacial speciation of contaminants and respective retention patterns for the safety assessments of nuclear waste repositories.

Acknowledgements:

This work has been developed in the frame of the iCross project. We gratefully acknowledge funding provided by the German Federal Ministry of Education and Research (BMBF, Grant 02NUK053) and the Helmholtz Association (Grant SO-093).

REFERENCES

1. Molodtsov et al., “Sorption of Eu(III) on Eibenstock granite studied by µTRLFS: A novel spatially-resolved luminescence-spectroscopic technique” Scientific Reports, 9, Article Number 6287 (2019), https://doi.org/10.1038/s41598-019-42664-2.

2. Demnitz et al., “Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock” Journal of Hazardous Materials, (2021), https://doi.org/10.1016/j.jhazmat.2021.127006.

Keywords: luminescence; speciation; Cm; crystal; interface; crystalline; roughness; topography; microscopy; spatial

  • Poster (Online presentation)
    TransRet2020 - Workshop on Processes Influencing Radionuclide Transport and Retention, 12.04.-13.10.2021, Karlsruhe, Germany

Permalink: https://www.hzdr.de/publications/Publ-34516


Electronic pair alignment and roton feature in the warm dense electron gas

Dornheim, T.

Abstract

The study of matter under extreme densities and temperatures as they occur e.g. in astrophysical objects and nuclear fusion applications has emerged as one of the most active frontiers in physics, material science, and related disciplines. In this context, a key quantity is given by the dynamic structure factor S(q,ω), which is probed in scattering experiments -- the most widely used method of diagnostics at these extreme conditions. In addition to its crucial importance for the study of warm dense matter, the modeling of such dynamic properties of correlated quantum many-body systems constitutes one of the most fundamental theoretical challenges of our time. Here we report a hitherto unexplained roton feature in S(q,ω) of the warm dense electron gas [1], and introduce a microscopic explanation in terms of a new electronic pair alignment model [2]. This new paradigm will be highly important for the understanding of warm dense matter, and has a direct impact on the interpretation of scattering experiments. Moreover, we expect our results to give unprecedented insights into the dynamics of a number of correlated quantum many-body systems such as ultracold helium, dipolar supersolids, and bilayer heterostructures.

  • Lecture (others)
    Theorie-Seminar am Insitut für Theoretische Physik und Astrophysik der Christian-Albrechts Universität zu Kiel., 12.04.2022, Kiel, Germany

Permalink: https://www.hzdr.de/publications/Publ-34515


Update of the Bunch Arrival Time Monitor at ELBE

Kuntzsch, M.; Maalberg, A.; Schwarz, A.; Zenker, K.; Czwalinna, M. K.; Kral, J.

Abstract

The bunch arrival time monitor (BAM) at the radiation source ELBE has been upgraded twofold. In order to achieve a higher precision a new frontend has been designed, based on a development by DESY, that uses state of the art 50 GHz electro-optical modulators (EOMs). The frontend allows for thermal control of critical components and monitoring of system parameters. The modulated EOM signals and monitoring data are distributed to a new readout electronic. The new MicroTCA-based receiveris based on a dedicated FMC card developed at DESY that is installed on an FMC25 carrier board. The arrival time is calculated on a FPGA with low latency and can be used for machine diagnostic. The code has been adapted to enable the processing of a data stream of the continuous train of electron bunches, allowing for the implementation of a cw beam based feedback in a next step. The contribution will describe the BAM setup as well as the performance measured at the ELBE accelerator.

Keywords: BAM; ELBE; arrival time; synchronization

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  • Poster
    International Particle Accelerator Conference IPAC 2022, 12.-17.06.2022, Bangkok, Thailand

Permalink: https://www.hzdr.de/publications/Publ-34514


Identification of color pigments in wall paintings of Oscar Schlemmer

Hennig, C.

Abstract

Residuals of wall paintings from Bauhaus artist Oscar Schlemmer have been re-discovered recently. The restauration strategy of these precious objects requires a phase identification of the color pigments. The study includes the identification of potential decomposition mechanisms, as the wall paintings were in contact with chemicals of the glue from overlaying wall paper. Some coloring minerals were identified by combining high-resolution powder diffraction (PXRD) and x-ray fluorescence spectroscopy (XRF) using the new diffractometers at the Rossendorf Beamline (ROBL).

The Bauhaus revolutionized creative and artistic thinking and work worldwide. Walter Gropius employed a series of acclaimed artists as professors, among them Oskar Schlemmer, Wassili Kandinsky, Lyonel Feininger and Paul Klee. Adolf Meier, head of the architectural office of Walter Gropius, commissioned Oskar Schlemmer with wall paintings in his apartment for the first Bauhaus exhibition in 1923. Oskar Schlemmer, who was 1922-1925 the head of the Bauhaus studio for wall paintings, performed the work with Werner Gilles. During the Nazi regime, Schlemmer’s work was classified as degenerate art. Many of his wall paintings were overpainted. The wall paintings in Meier’s former apartment fell into oblivion. It was in the 1990s that Bauhaus research became aware of the existence of these wall paintings, which are only documented by two black and white photos from the time they were created.

In 2018, the apartment became subject of restoration studies. For this purpose, a network of institutions was created to identify the color scheme of the wall paintings and to generate a detailed 3D model of the room. The identification of the original color substances of the paintings remains a demanding issue as there are only residuals available. Schlemmer used partly new organic color material which was identified by spectroscopic techniques. A part of the paints is based on natural or synthetic mineral phase. These substances appear usually in a crystalline form and were identified with XRD. Heavy metals were identified with XRF spectroscopy. The small size of the color fragments, which were released from the walls, have microscopic dimensions of 10-30µm. This makes it impossible to perform phase identi¬fication with conventional laboratory equipment. The results of the synchrotron based XRD and XRF measurements from ROBL will be presented.

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  • Invited lecture (Conferences)
    Das Raumkunstwerk Wohnraum Adolf Meyer in Weimar im Kontext der Entwicklung des Bauhauses, 20.04.2022, Weimar, Germany

Permalink: https://www.hzdr.de/publications/Publ-34513


Machine Learning Collaboration-as-a-service at Helmholtz

Steinbach, P.; Hoffmann, H.; Tanveer, M.; Schmerler, S.; Starke, S.

Abstract

Machine Learning (ML) based methods are proliferating in industry, society, science and physics in particular in the last years. Not only do ML tools allow inferences from experimental data, but also have shown to be an inroads to previously unreachable theoretical or experimental domains. In this presentation, I'll introduce Helmholtz AI as a funded networking activity within Helmholtz to support matter research in using ML for science. I'll dive into how and why the program is split into research and collaboration-as-a-service staff. If time allows, I'll discuss how we approach ML projects with scientists from a consulting point of view.

Keywords: machine learning; consulting; academia; science; services; Helmholtz AI

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    Seminar des ORIGINS Data Science Laboratory Munich, Einladung durch Lukas Heinrich, 08.04.2022, virtuell, Germany
    DOI: 10.6084/m9.figshare.19550815.v1

Permalink: https://www.hzdr.de/publications/Publ-34512


Effects of electrically conductive walls on turbulent magnetohydrodynamic flow in a continuous casting mold

Blishchik, A.; Glavinic, I.; Wondrak, T.; van Odyck, D.; Kenjereš, S.

Abstract

In the present study, we have performed a series of numerical simulations of the turbulent liquid metal flow in a laboratory-scale setup of the continuous casting. The liquid metal flow was subjected to an external non-uniform magnetic field reproducing a realistic electromagnetic brake (EMBr) effect. The focus of this research was on the effects of the finite electrical conductivity of Hartmann walls on the flow and turbulence in the mold. To be able to simulate distributions of the electric potential and current in both the fluid and solid wall domains, we applied our recently developed and validated in-house conjugate MHD solver based on the open-source code OpenFOAM. The dynamic Large Eddy Simulation (LES) method was used to simulate the turbulent flow. The results obtained for the neutral (non-MHD) and MHD cases over a range of the imposed EMBr strengths – all for the perfectly electrically insulated walls – were compared with the available Ultrasound Doppler Velocimetry (UDV) measurements. A good agreement between simulations and experiments was obtained for all simulated cases. Next, we completed a series of simulations including a wide range of the finite electric conductivities (ranging from a weakly to perfectly conducting wall conditions) of the Hartmann walls for a fixed value of the imposed EMBr. The obtained results demonstrated a significant influence of the electric wall conductivities on the flow and turbulence reorganization. It is expected that here provided insights can be applicable for the new generation of the laboratory- and real-scale continuous casting setups.

Keywords: MHD; Magnetic field; Lorentz force; OpenFOAM; Electrically conducting walls; Dynamic LES; Continuous casting

Permalink: https://www.hzdr.de/publications/Publ-34511


Depth-Adjustable Magnetostructural Phase Transition in Fe₆₀V₄₀ Thin Films

Anwar, M. S.; Cansever, H.; Boehm, B.; Gallardo, R.; Hübner, R.; Zhou, S.; Kentsch, U.; Rauls, S.; Eggert, B.; Wende, H.; Potzger, K.; Faßbender, J.; Lenz, K.; Lindner, J.; Hellwig, O.; Bali, R.

Abstract

Phase transitions occurring within spatially confined regions can be useful for generating nanoscale material property modulations. Here we describe a magneto-structural phase transition in a binary alloy, where a structural transition from short range order (SRO) to body centered cubic (bcc) results in the formation of depth-adjustable ferromagnetic layers, which reveal application-relevant magnetic properties of high saturation magnetitzation (Ms) and low Gilbert damping (α). Here we use Fe₆₀V₄₀ binary alloy films which transform from initially Ms = 17 kA/m (SRO structure) to 747 kA/m (bcc structure) driven by atomic displacements caused by penetrating ions. Simulations show that estimated ~1 displacement per atom triggers a structural transition, forming homogeneous ferromagnetic layers. The thickness of ferromagnetic layer increases as a step-like function of the ion-fluence. Microwave excitations of the ferromagnetic/non-ferromagnetic layered system reveals an α = 0.0027 ± 0.0001. The combination of nanoscale spatial confinement, low α and high Ms provide a pathway for the rapid patterning of magnetic and microwave device elements.

Keywords: Magneto-structural correlations; Phase transitions; Magnetic thin films; Ion-irradiation; Short-range order

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Permalink: https://www.hzdr.de/publications/Publ-34510


Spatially-resolved sorption of Cm(III)/Eu(III) on heterogeneous crystalline rocks

Molodtsov, K.; Schymura, S.; Schierz, A.; Müller, K.; Stumpf, T.; Schmidt, M.

Abstract

Many countries will use deep geological repositories (DGR) to store their heat generating high-level radioactive waste. Crystalline rock is one of the potential host rocks, but possesses high inherent mineralogical heterogeneity. Since the molecular retardation reactions of radionuclides at water-mineral interfaces depend mainly on the availability of reactive sites, heterogeneity is expected to play a major role for contaminant transport in a DGR. The fundamental understanding and transferrability of this heterogeneity into modeling different transport scenarios is of urgent need for a reliable safety assessment of a repository. Through correlation of spectroscopic information with spatial resolution we characterized the nanostructure of crystalline rock surfaces and the surface speciation of selected radionuclides, namely Eu(III) and Cm(III) thereon. We utilized vertical scanning interferometry, autoradiography, and Raman microscopy in combination with µTRLFS – microfocus time-resolved laser-induced fluorescence spectrsocopy.[1] Using these novel techniques the surface speciation of Eu(III) and Cm(III) can be qualified and quantified. Moreover, we were able to correlate mineralogy, topography, and grain boundary effects with radionuclide speciation, allowing us to draw conclusions about radionuclide retention mechanisms on mineral surfaces.
Our work focussed on granite from Eibenstock (Germany) and migmatised gneiss from the Bukov URL (Czech Republic). We characterized the sorption of Cm(III) and Eu(III) on feldspar, mica, quartz and accessory mineral areas on both rocks. [1-3] Using autoradiography and µTRLFS we linked the sorption uptake on the heterogeneous surface with the mineralogy and the surface roughness, showing that surface roughness within the same mineral phase has an impact not only on the amount of sorption uptake, but also the radionuclide surface speciation and thus bond strengths and reversibility.
Using µTRLFS we identified how the speciation correlates to mineral phases and surface roughness. A higher surface roughness induces more binding sites available to Eu(III) and Cm(III) resulting in strongly bound trivalent radionuclide surface complexes and a higher sorption uptake. On quartz and feldspar high surface roughness leads to ternary Cm(III) complex formation on the surface presumably with silicate and carbonate ions avaliable in solution.
In comparison to Eibenstock granite, Bukov gneiss inherently contained a greater number of accessory minerals. We observed that some of them seem to dominate the sorption process, lowering the sorption of Eu(III) on the major components feldspar and quartz in comparison to Eibenstock granite.[2] The leftover Cm(III)/Eu(III) sorb on stronger and preferential sorption sites, which are located in regions exhibiting a high surface roughness.[3] This could be clearly proven for Cm(III)/Eu(III) surface complexes being stronger on feldspar. With this work we demonstrated a successful upscaling approach to derive molecular understanding of radionuclide retention processes from the nm to the cm sacle.

References
[1] Molodtsov, Sorption of Eu(III) on Eibenstock granite studied by µTRLFS: A novel spatially-resolved luminescence-spectroscopic technique, Scientific Reports, 9, 6287 (2019).
[2] Molodtsov, A µTRLFS investigation on the sorption of Eu3+ on Bukov migmatised gneiss on the molecular level, Environmental Science & Technology, submitted.
[3] Demnitz, A spatially-resolved study on the sorption of Cm(III) on different crystalline rocks using surface investigation techniques, in preparation.

Keywords: luminescence; trlfs; surface; mineralogy; topography; interface; curium; europium; correlative; spectroscopy

  • Open Access Logo Lecture (Conference) (Online presentation)
    2. Tage der Standortauswahl, 11.-12.02.2021, Freiberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-34509


Contemporary environment and historical legacy explain functional diversity of freshwater fishes in the world rivers

Su, G.; Tedesco, P. A.; Toussaint, A.; Villéger, S.; Brosse, S.

Abstract

Aim
Regional taxonomic diversity (species richness) is strongly influenced by a joint effect of the current processes (habitat and energy availability) and historical legacies (past climate and geography), but it is still unclear how those historical and current environmental drivers have shaped the functional diversity of species assemblages.

Major taxa studied
Freshwater fish.

Location
Global.

Time period
1960s–2000s.

Methods
We combined the spatial occurrences over 2,400 river basins world-wide and the functional traits measured on 10,682 freshwater fish species to quantify the relative role of the habitat, climate and historical processes on the current global fish functional diversity. To avoid any correlation between taxonomic diversity and functional diversity, we controlled for differences in the number of species (species richness) between rivers. Functional diversity was considered through three complementary facets: functional richness, functional dispersion and functional identity.

Results
The habitat-related variables explained most of the gradient in functional richness, verifying the habitat size–diversity hypothesis. In contrast, the historical climate–geography legacies markedly imprinted the functional dispersion and functional identity patterns, leading to a balanced influence of the current and historical processes. Indeed, the distribution of morphological traits related to fish dispersal was explained largely by the glaciation events during the Quaternary, leading to strong latitudinal gradients.

Main conclusions
This study provides new insights into the role of historical and current environmental determinants on the functional structure of fish assemblages and strengthens the proposal that the independence of facets of functional diversity from the species richness makes them essential biodiversity variables to understand the structure of communities and their responses to global changes.

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Permalink: https://www.hzdr.de/publications/Publ-34508


FISHMORPH: A global database on morphological traits of freshwater fishes

Brosse, S.; Charpin, N.; Su, G.; Toussaint, A.; Herrera-R, G. A.; Tedesco, P. A.; Villéger, S.

Abstract

Motivation
Global freshwater fish biodiversity and the responses of fishes to global changes have been explored intensively using taxonomic data, whereas functional aspects remain understudied owing to the lack of knowledge for most species. To fill this gap, we compiled morphological traits related to locomotion and feeding for the world freshwater fish fauna based on pictures and scientific drawings available from the literature.

Main types of variables contained
The database includes 10 morphological traits measured on 8,342 freshwater fish species, covering 48.69% of the world freshwater fish fauna.

Spatial location and grain
Global.

Major taxa and level of measurement
The database considers ray-finned fishes (class Actinopterygii). Measurements were made at the species level.

Software format
.csv.

Main conclusion
The FISHMORPH database provides the most comprehensive database on fish morphological traits to date. It represents an essential source of information for ecologists and environmental managers seeking to consider morphological patterns of fish faunas throughout the globe, and for those interested in current and future impacts of human activities on the morphological structure of fish assemblages. Given the high threat status of freshwater environments and the biodiversity they host, we believe this database will be of great interest for future studies on freshwater ecology research and conservation.

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Permalink: https://www.hzdr.de/publications/Publ-34507


Spatially resolved sorption of Cm(III) on crystalline rock: influence of surface roughness and mineralogy

Demnitz, M.; Molodtsov, K.; Schymura, S.; Schierz, A.; Müller, K.; Schmidt, M.

Abstract

Many countries will use deep geological repositories to dispose of their highly active nuclear waste. Crystalline rock is a potential host rock because of its high stability, heat resistance and low solubility. However, it possesses a high inherent mineralogical heterogeneity. Using sophisticated techniques that allow spatial resolution we characterized the nanostructure of such crystalline rock surfaces and the speciation of the actinide Cm(III) thereon.

Namely, we combined vertical scanning interferometry, calibrated autoradiography, and Raman microscopy coupled to µTRLFS (micro-focus time-resolved laser-induced spectroscopy).[1] Thus we were able to correlate mineralogy, topography, and grain boundary effects with radionuclide speciation, allowing us to identify important radionuclide retention processes and parameters.

Investigations focussed on granite from Eibenstock (Germany) and migmatised gneiss from Bukov (Czech Republic). Cm(III) sorption on the rock’s constituing minerals - primarily feldspar, mica and quartz - was analyzed quantitatively and qualitatively. We observed that Cm(III) sorption uptake and speciation depends not only on the mineral phase, but also the surface roughness. An increasing surface roughness leads to higher sorption uptake and a stronger coordination of the sorbed Cm(III). On the same mineral grains sorption differed significantly depending if an area exhibits a low or high surface roughness. In case that one mineral phase dominates the sorption process, sorption of Cm(III) on other mineral phases will only occur at strong binding sites, typically where surface roughness is high. Areas of feldspar and quartz with high surface roughness additionally showed the formation of sorption species with particularly high sorption strength that could either be interpreted as Cm(III) incorporation species or ternary complexes on the mineral surface.

We conclude that in addition to mineral composition, surface roughness needs to be considered adequately to describe interfacial speciation of contaminants and respective retention patterns for the safety assessments of nuclear waste repositories.

[1] Molodtsov, Schymura, Rothe, Dardenne & Schmidt (2019), Scientific Reports 9, 6287.

  • Open Access Logo Lecture (Conference) (Online presentation)
    Goldschmidt Virtual 2021, 08.07.2021, Lyon, France
    DOI: 10.7185/gold2021.3156

Permalink: https://www.hzdr.de/publications/Publ-34506


Mechanistic understanding of Curium(III) sorption on natural K feldspar surfaces

Demnitz, M.; Schymura, S.; Neumann, J.; Schmidt, M.; Schäfer, T.; Stumpf, T.; Müller, K.

Abstract

To assess a reliable safety case for future deep underground repositories for highly active nuclear waste the retention of radionuclides by the surrounding host rock must be understood comprehensively. Retention is influenced by several parameters such as mineral heterogeneity and surface roughness, as well as pore water chemistry (e.g., pH). However, the interplay between those parameters is not yet well understood. Therefore, we present a correlative spectromicroscopic approach to investigate sorption of the actinide Cm(III) on: 1) bulk K-feldspar crystals to determine the effect of surface roughness and pH (5.5 and 6.9) and 2) a large feldspar grain as part of a complex crystalline rock system to observe how sorption is influenced by the surrounding heterogeneous mineralogy. Our findings show that rougher K-feldspar surfaces exhibit increased Cm(III) uptake and stronger complexation. Similarly, increasing pH leads to higher surface loading and stronger Cm(III) binding to the surface. Within a heterogeneous mineralogical system sorption is further affected by neighboring mineral dissolution and competitive sorption between mineral phases such as mica and feldspar. The obtained results express a need for investigating relevant processes on multiple scales of dimension and complexity to better understand trivalent radionuclide retention by a potential repository host rock.

Keywords: luminescence; speciation; Cm; host rock; interface; crystalline; roughness; topography; microscopy; spatial

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Permalink: https://www.hzdr.de/publications/Publ-34505


BIM - Biomedical Image analysis Models survey

Li, R.; Sharma, V.; Thangamani, S.; Yakimovich, A.

Abstract

This is meta-analysis repository for the program code and meta-data collected on open-source biomedical image analysis models. This repository is maintained as a continuous survey of published open-source models. Code is aimed at obtaining statistical summary of the meta-data.

Keywords: open source; machine learning; bioimage analysis; deep learning

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  • Software in external data repository
    Publication year 2022
    Programming language: Python
    System requirements: Python 3.9.7 seaborn 0.11.2 pandas 1.3.4 matplotlib 3.5.0
    License: MIT (Link to license text)
    Hosted on GitHub: Link to location

Permalink: https://www.hzdr.de/publications/Publ-34504


GUI Flow data

Döß, A.; Schubert, M.

Abstract

- english version below -

Diese grafische Nutzeroberfläche in Form einer installirbaren standalone-Anwendung dient zur Visualisierung aus der Literatur bekannter experimenteller Datensätze und Strömungskarten für horizontal strömende Luft/Wasser-Systeme. Weiterhin sind Modelle und Strömungskarten aus der Literatur integriert, die für beliebige Stoffsysteme eine Vorhersage über die zu erwartenden Strömungsformen treffen. Zusätzlich erlauben Schnitstellen in Form von .txt-Dateien das Importieren eigener Datensätze, bzw. das Exportieren der visualisierten Inhalte.

Für die Richtigkeit der dargestellten Inhalte wird keine Haftung übernommen. Das Urheberrecht für die zugrundeliegenden Datensätze und Berechnungen liegt bei den Autoren der referenzierten Primärliteratur.

This graphical user interface in the form of an installable standalone application is used to visualize experimental data sets and flow maps known from the literature for horizontally flowing air/water systems. Furthermore, models and flow maps from the literature are integrated to predict the flow patterns for any fluid system. Additionally, data interfaces in the form of .txt files allow the import of own data sets, respectively the export of the visualized contents.

No liability is assumed for the correctness of the displayed contents. The copyright for the underlying data sets and calculations is held by the authors of the referenced primary literature.

Keywords: GUI; Interface; Flow data; flow regime maps; Strömungsdaten; Strömungskarten

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  • TOPFLOW Facility

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Permalink: https://www.hzdr.de/publications/Publ-34503


Fully encapsulated and stable black phosphorus field-effect transistors

Arora, H.; Fekri, Z.; Vekariya, Y. N.; Chava, P.; Watanabe, K.; Taniguchi, T.; Helm, M.; Erbe, A.

Abstract

Black phosphorus (BP) has quickly gained popularity in the scientific community owing to its interesting semiconducting properties, such as direct bandgap, high mobility, and intrinsic ambipolar behavior. However, its sensitivity to oxygen, moisture, and other air species has restricted its integration into active devices. Here, we employ lithography-free via-encapsulation scheme to fabricate fully-encapsulated BP-based field-effect transistors (FETs). The full encapsulation is achieved by sandwiching the BP layers between top and bottom hexagonal boron nitride (hBN) layers; top hBN passivating the BP layer from the environment and bottom hBN acting as a spacer and suppressing charge transfer to the BP layer from the SiO2 substrate. The embedded via-metal-electrodes allow us to perform reliable electrical measurements of the BP FETs. Based on our results, we find that the electronic properties of the via-encapsulated BP FETs are significantly improved compared to unencapsulated devices and a clear metal–insulator transition is observed which remained missing in the latter. We further establish that the via-contacting scheme leads to superior results compared to graphene-hBN heterostructures and bare hBN layers combined with evaporated metal contacts (both use top and bottom hBN to encapsulate BP) by revealing a higher mobility, lower hysteresis, and long-term ambient-stability in BP FETs.

Keywords: two-dimensional semiconductors; black phosphorus; field-effect transistors; hexagonal boron nitride; encapsulation

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Permalink: https://www.hzdr.de/publications/Publ-34502


Open-Source Biomedical Image Analysis Models: a Meta-analysis and Continuous Survey

Li, R.; Sharma, V.; Thangamani, S.; Yakimovich, A.

Abstract

Open-source research software has proven indispensable in modern biomedical image analysis. A multitude of open-source platforms drive image analysis pipelines and help disseminate novel analytical approaches and algorithms. Recent advances in machine learning allow for unprecedented improvement in these approaches. However, these novel algorithms come with new requirements in order to remain open source. To understand how these requirements are met, we have collected 50 biomedical image analysis models and performed meta-analysis of their respective paper, source code, dataset and trained model parameters. We concluded that while there are many positive trends in openness, only a fraction of all publications makes all necessary elements available to the research community.

Keywords: deep learning; machine learning; bioimage analysis; open source

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Permalink: https://www.hzdr.de/publications/Publ-34501


Sequencing meets machine learning to fight emerging pathogens: A preview

Yakimovich, A.

Abstract

In searching for SARS-CoV variants-of-concern, pathogen sequencing is generating an impressive amount of data. However, beyond epidemiological use, these data contain cues fundamental to our understanding of pathogen evolution in the human population. Yet, to harness them, further development of computational methodology, such as machine learning, may be required. This preview discusses updates in machine learning to understand emerging pathogens.

Keywords: SARS-CoV2; machine learning; sequencing

Permalink: https://www.hzdr.de/publications/Publ-34497


A tandem segmentation-classification approach for the localization of morphological predictors of C. elegans lifespan and motility

Galimov, E.; Yakimovich, A.

Abstract

C. elegans is an established model organism for studying genetic and drug effects on aging, many of which are conserved in humans. It is also an important model for basic research, and C. elegans pathologies is a new emerging field. Here we develop a proof-of-principal convolutional neural network-based platform to segment C. elegans and extract features that might be useful for lifespan prediction. We use a dataset of 734 worms tracked throughout their lifespan and classify worms into long-lived and short-lived. We designed WormNet - a convolutional neural network (CNN) to predict the worm lifespan class based on young adult images (day 1 – day 3 old adults) and showed that WormNet, as well as, InceptionV3 CNN can successfully classify lifespan. Based on U-Net architecture we develop HydraNet CNNs which allow segmenting worms accurately into anterior, mid-body and posterior parts. We combine HydraNet segmentation, WormNet prediction and the class activation map approach to determine the segments most important for lifespan classification. Such a tandem segmentation-classification approach shows the posterior part of the worm might be more important for classifying long-lived worms. Our approach can be useful for the acceleration of anti-aging drug discovery and for studying C. elegans pathologies.

Keywords: aging; deep learning; Caenorhabditis elegans; interpretable machine learning; convolutional neural networks

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Permalink: https://www.hzdr.de/publications/Publ-34496


PaN Training Catalogue

Knodel, O.; Padovani, A.

Abstract

The source code of the training catalogue for the PaN community developed in the ExPaNDS and PaNOSC projects. The initial code was developed for the training portal TeSS developed in the ELIXIR project.

Keywords: data management; photon and neutron community; training catalogue

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  • Open Access Logo Software in external data repository
    Publication year 2022
    Programming language: Ruby on Rails
    System requirements: ruby-2.7.4
    License: BSD 3-Clause License (Link to license text)
    Hosted on https://github.com/pan-training/training-catalogue: Link to location

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Permalink: https://www.hzdr.de/publications/Publ-34495


Model-independent determination of the dipole response of 66Zn using quasimonoenergetic and linearly polarized photon beams

Savran, D.; Isaak, J.; Schwengner, R.; Massarczyk, R.; Scheck, M.; Tornow, W.; Battaglia, G.; Beck, T.; Finch, S. W.; Fransen, C.; Friman-Gayer, U.; Gonzalez, R.; Hoemann, E.; Janssens, R. V. F.; Johnson, S.; Jones, M. D.; Kelly, N.; Kleemann, J.; Krishichayan, D. R. L.; O'Donnell, D.; Papst, O.; Sinclair, J.; Werner, V.; Wieland, O.; Wilhelmy, J.

Abstract

Photon strength functions are an important ingredient in calculations relevant for the nuclear synthesis of heavy elements. The relation to the photo-absorption cross section allows to experimentally constrain photon strength functions by investigating the photo-response of atomic nuclei.
We determine the photoresponse of 66Zn in the energy region of 5.6 MeV to 9.9 MeV and analyze the contribution of the decay channel back to the ground state. In addition, for the elastic channel electric and magnetic dipole transitions can be separated.
Nuclear resonance fluorescence experiments were performed using a linearly-polarized quasimonoenergetic photon beam at the High Intensity Gamma-ray Source. Photon beam energies in the energy range from 5.6 MeV to 9.9 MeV with an energy spread of about 3 % were selected in steps of 200 - 300 keV.
Two High-Purity Germanium detectors were used for the subsequent gamma-ray spectroscopy.
Full photo absorption cross sections are extracted from the data making use of the mono-energetic character of the photon beam. For the ground-state decay channel the average contribution of electric and magnetic dipole strength is disentangled. The average branching ratio back to the ground state is determined as well.
The new results show lower cross sections compared to the values extracted from experiments using bremsstrahlung. In the latter the average branching ratio to the ground state needs to be estimated from statistical model calculations in order to analyze the data. The calculations underestimate this branching ratio
compared to the values extracted within the present analysis, which would partly explain the high cross sections determined from the bremsstrahlung data.

Keywords: Nuclear structure; electromagnetic transitions; photon scattering; nuclear resonance fluorescence; polarized photon beams

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Permalink: https://www.hzdr.de/publications/Publ-34493


Evaluation of raw data from THz source.

Gruber, T.

Abstract

The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) at the Helmholtz Centre Dresden Rossendorf (HZDR) can produce several kinds of secondary radiations. THz radiation is one of them and can be used with a typical pulse frequency of 100 kHz as a stimulation source for elementary low-energy degrees of freedom in matter. It was used in the "Phase-resolved Higgs response in superconducting cuprates" publication (DOI: 10.1038/s41467-020-15613-1). The raw data for this publication can be accessed on RODARE (DOI: 10.14278/rodare.277) and will be used to reproduce the figures from the publication. This Jupyter notebook enables the user to handle the raw data from an TELBE THz experiment. To sample the whole THz wave the laser path length is modified by moving specific mirrors. The raw data contains for each mirror position a binary file storing the signal spectra and a folder with gray scaled tiff files storing the jitter timing. Parts of the code are parallelized and can run on multiple cores. The execution time on a single core is roughly 15 min after downloading and extracting a 20 GB zip file.

Keywords: Jupyter Notebook; Thz2

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Permalink: https://www.hzdr.de/publications/Publ-34492


Data publication: Caenorhabditis elegans microscopy dataset with lifespan, movement and segmentation annotations.

Galimov, E.; Pincus, Z.; Yakimovich, A.

Abstract

The nematode Caenorhabditis elegans (C. elegans) is an established model for studying various interventions into the ageing process, which allowed to find numerous genes and drugs interfering with agein. This dataset of widefield time-lapse (days 1 to 3) micrographs of C. elegans was initially obtained in the Pincus lab (Pincus et al. 2011, Zhang et al. 2016). Here, the dataset was annotated for lifespan, movement and segmentation of C. elegans, and was employed for developing a machine learning framework (Yakimovich et al. 2021). All files are in 8-bit PNG format. Movement and lifespan annotations are provided using folder structure. Segmentation annotation is provided by the accompanying masks.

Keywords: C. elegans; Caenorhabditis elegans; lifespan; movement; segmentation; microscopy

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Permalink: https://www.hzdr.de/publications/Publ-34491


Review on zigzag air classifier

Kaas, A.; Mütze, T.; Peuker, U. A.

Abstract

The zigzag (ZZ) classifier is a sorting and classification device with a wide range of applications (e.g. recycling, food industry [1, 2]). Due to the possible variation of geometry and process settings, the apparatus is used for various windows of operation regarding the specifications of the separation (e.g. cut sizes from 100 μm to several decimetres, compact and fluffy materials as well as foils). Since the ZZ-classifier gains more and more interest in recycling applications, it is discussed in this paper, regarding its design, mode of operation, influencing parameters and the research to date. Research on the ZZ-classifier has been going on for more than 50 years and can be divided into mainly experimental studies and modelling approaches.

Keywords: zigzag; classifier; separation; modelling; design

Permalink: https://www.hzdr.de/publications/Publ-34489


Development of Proton Bunch Monitors for Prompt Gamma-Ray Timing Based Treatment Verification

Makarevich, K.; Franke, A.; Pausch, G.; Permatasari, F.; Römer, K.; Schellhammer, S.; Stach, D.; Tiebel, J.; Wagner, A.; Weinberger, D.; Werner, R.-D.; Kögler, T.

Abstract

Introduction
Particle therapy emerged as a principal innovative technology for tumor treatment. However, it requires verification to exploit its full potential. Various approaches based on prompt gamma radiation were developed for range verification. Prompt gamma-ray timing (PGT), which determines the range of the therapeutic particles from time distributions of produced secondary gamma-rays, is a promising candidate for this as it is collimator-free and can be easily integrated into existing clinical beam deliveries [1]. However, phase instabilities between the accelerating radio frequency (RF) and the actual proton arrival time make phase monitoring indispensable [2]. In recent years, different concepts for proton bunch monitors (PBM) were developed [3,4]. The two most promising candidates are presented here.

Materials and Methods
A diamond detector with high radiation hardness and excellent time resolution was positioned close to the beam degrader. Protons scattered there were used to determine the phase correlation between RF and proton arrival time under realistic clinical conditions. The second monitor is a direct phasing tap on the low-level RF module of the IBA Proteus®C230 isochronous cyclotron. The correlation of both PBMs to the actual phase was checked in a scattering setup where protons from a pencil beam scattered in a thin polythene foil and then were coincidentally detected by CeBr₃-scintillators. The kinematics of this reaction makes the determination of the proton arrival time independent of the beam's bunch time spread.

Results
Both PBMs strongly correlate with the phase shift between the arrival time of the proton bunch and the RF. A model based on an over-damped, harmonic oscillator was able to describe the time-dependent change in the phase position and its correction by a control circuit with sufficient accuracy. Thus, the phase instabilities in the PGT data could be successfully corrected, enabling the improved measurement accuracy.

Summary
The phase instability of the proton bunch is the source of the greatest uncertainty of the PGT method [2]. Two PBMs were studied to correct these instabilities. PBM(s) complement the measurement setup, which should increase the sensitivity of the method and facilitate the translation of the PGT approach into clinical application.

Literature
[1] C. Golnik et al.: Range assessment in particle therapy based on prompt γ-ray timing measurements, Phys. Med. Biol. 59 (2014) 5399.
[2] T. Werner et al.: Processing of prompt gamma-ray timing data for proton range measurements at a clinical beam delivery, Phys. Med. Biol. 64 (2019) 105023.
[3] F. Permatasari: Development of a Clinically Applicable Technique for Range Verification in Proton Therapy Based on the PGT Method, PhD thesis, TU Dresden, in preparation.
[4] R.-D. Werner: Charakterisierung eines schnellen Diamantdetektors als PBM für die Reichweiteverifikation in der Protonentherapie, Masterarbeit, Universität Halle-Wittenberg, 2021.

Keywords: proton range verification; prompt gamma timing; proton bunch monitor; particle range verification; prompt gamma-ray timing; range verification; proton therapy; PGT

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  • Lecture (Conference)
    53. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik, 21.-24.09.2022, Aachen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34488


2-Phosphonobutane-1,2,4,-Tricarboxylic Acid (PBTC): pH-Dependent Behavior Studied by Means of Multinuclear NMR Spectroscopy

Kretzschmar, J.; Wollenberg, A.; Tsushima, S.; Schmeide, K.; Acker, M.

Abstract

Although 2-phosphonobutane-1,2,4,-tricarboxylic acid, PBTC, has manifold industrial applications, relevant and reliable data on the protonation of PBTC are poor. However, these data are critical parameters for ascertaining PBTC speciation, especially with regard to a sound structural and thermodynamic characterization of its metal ion complexes. A rigorous evaluation of pH-dependent 1H, 13C, and 31P chemical shifts along with accessible scalar spin–spin coupling constants (J) was performed in order to determine the pKa values of PBTC in 0.5 molal NaCl aqueous solution by means of nuclear magnetic resonance (NMR) spectroscopy. The phosphonate group revealed pKa values of 0.90 ± 0.02 and 9.79 ± 0.02, and the pKa values associated with the carboxylic groups are 3.92 ± 0.02, 4.76 ± 0.03, and 6.13 ± 0.03. Supported by DFT-calculated structures revealing strong intramolecular hydrogen bonding, the sequence of deprotonation could be unambiguously determined.

Keywords: PBTC; NMR; DFT; speciation; Thermodynamic constant; protolysis

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Permalink: https://www.hzdr.de/publications/Publ-34485


The RODARE Data Repository (InvenioRDM) and why we need a separate Metadata Catalogue

Knodel, O.

Abstract

Presentations from the Workshop on Metadata Catalogues, which took place virtually via Zoom on the 4th April 2022. Rodare was presented to introduce a data publication repository in contrast to the metadata catalogues SciCAT and ICAT. A recording of the event can be found on the ExPaNDS website: https://expands.eu/presentations/

Keywords: Data Management; Metadata Catalogue; ExPaNDS

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    ExPaNDS Workshop on Metadata Catalogues, 04.04.2022, online, online

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Permalink: https://www.hzdr.de/publications/Publ-34484


Novel Mixing Relations for Determining the Effective Thermal Conductivity of Open-Cell Foams

Nain Camacho Hernandez, J.; Link, G.; Schubert, M.; Hampel, U.

Abstract

This paper proposes a new approach to relate the effective thermal conductivity of open-cell solid foams to their porosity. It is based on a recently published approach for estimating the dielectric permittivity of isotropic porous media. A comprehensive assessment was performed comparing the proposed mixing relation with published experimental data for thermal conductivity and with numerical data from state-of-the-art relations. The mixing relation for the estimation of thermal conductivities based on dodecahedrons as building blocks shows good agreement with experimental data over a wide range of porosity.

Keywords: open-cell foams; effective permittivity; thermal conductivity; platonic solids

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  • TOPFLOW Facility

Permalink: https://www.hzdr.de/publications/Publ-34483


Analysis of Low-Temperature Magnetotransport Properties of NbN Thin Films Grown by Atomic Layer Deposition

Vegesna, S. V.; Lanka, S. V.; Bürger, D.; Li, Z.; Linzen, S.; Schmidt, H.

Abstract

Superconducting niobium nitride (NbN) films with nominal thicknesses of 4 nm, 5 nm, 7 nm, and 9 nm were grown on
sapphire substrates using atomic layer deposition (ALD). We observed probed Hall resistance (HR) (Rxy) in external out-ofplane magnetic fields up to 6 T and magnetore-sistance (MR) (Rxx) in external in-plane and out-of-plane magnetic fields up
to 6 T on NbN thin films in Van der Pauw geometry. We also observed that positive MR dominated. Our study focused on the
analysis of interaction and localisation effects on electronic disorder in NbN in the normal state in temperatures that ranged
from 50 K down to the superconducting transition temperature. By modelling the temperature and magnetic field
dependence of the MR data, we extracted the temperature-dependent Coulomb interaction constants, spin–orbit scattering
lengths, localisation lengths, and valley degeneracy factors. The MR model allowed us to distinguish between interaction
effects (positive MR) and localisation effects (negative MR) for in-plane and out-of-plane magnetic fields. We showed that
anisotropic dephasing scattering due to lattice non-idealities in NbN could be neglected in the ALD-grown NbN thin films.

Keywords: Atomic layer deposition; Coulomb interaction constant; Magnetoresistance; NbN thin films; Supercondutor; Valley degeneracy

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Permalink: https://www.hzdr.de/publications/Publ-34481


Liquid Metal Alloy Ion Sources for FIB Applications in Nano – Technology

Bischoff, L.; Klingner, N.; Hlawacek, G.; Pablo Navarro, J.; Lenz, K.; Lindner, J.; Mazarov, P.; Pilz, W.; Meyer, F.

Abstract

Focused Ion Beam (FIB) processing has been established as a well-suited and promising technique in R&D in nearly all fields of nanotechnology for patterning and prototyping on the μm-scale and below. Liquid Metal Alloy Ion Sources (LMAIS) represent an alternative to expand the FIB application fields beside all other source concepts. Here we present in the frame of two industrial related projects (ZIM) the development of different special LMAIS for FIB applications in nano–technology. So among others the alloys CoNd, CoNdB, AuGeB, AuGeBNi, AuSiCr, GaBiLi, CoDy, CuDy and AuSiDy are investigated and tested with regard to their use in modern mass separated FIB systems due to mass resolution, ion beam current of the certain ion species and the available spot size. The light ions like B, Li or Si dedicated for ion beam lithography systems. The transition metal elements Co, Fe and Ni are important for the modification and the adjustment of magnetic properties of nanomagnetic structures, presented in detail with a Co – FIB on a permalloy nanowire. Rare earth elements, especially Dy can tune the magnetic damping in nanometric dimensions. The latter is shown on magnonic stripe pattern of one mm² in size on a thin permalloy film made by a VELION FIB.

Keywords: Focused Ion Beam; Liquid Metal Alloy Ion Sources; nanomagnetic structures; magnetic damping

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  • Lecture (Conference)
    Ion Beam Workshop 2022, 31.03.-01.04.2022, Jena, Germany

Permalink: https://www.hzdr.de/publications/Publ-34480


Technological assessments on recent developments in fine and coarse particle flotation systems

Ahmad, H.; Mehdi, S.; Hoang, D. H.; Hamid, K.; Boris, A.; Przemyslaw, B. K.

Abstract

After more than a century applying flotation to the mining industry, two completely different strategies have been introduced for processing purposes. One is the classical approach viz. grinding ores to a certain extent (fine particles) and floating them via conventional mechanical and pneumatic cells i.e., Jameson, Imhoflot™ and Reflux™. This strategy continues because mines face declining cut-off grades, complex and poly-mineralized ores, and they are required to achieve an acceptable degree of mineral liberation. The other school of thought deals with coarse particle processes mainly owing to the low energy requirements, that includes SkimAir® flash, fluidized bed and HydroFloat™ cells. There is no study in the literature to comparatively present the recent developments of flotation apparatuses versus the conventional mechanical cells. To cover this knowledge gap in the literature, the present paper endeavors to critically evaluate these concepts from several points of view, including existing technological advancements, water and energy usage, kinetics, and circuit design. A brief introduction of advanced technologies, along with their applications is presented. The data from literature and case studies showed that the Jameson, Imhoflot™ and recently developed Reflux™ flotation cells can be very effective for recovering fine particles owing to their specific hydrodynamic designs, intensive energy dissipation rate and generation of micron-sized bubbles (100–700 μm). Very low (less than a few minutes) mean particle residence time, high gas-hold up (ca. 50–70 %), no agitation and high efficiency of particle-bubble collision were identified as their main advantages compared to traditional mechanical flotation cells. In addition to their common applications in cleaner stage, these cells were used in pre-flotation and scalping (producing final concentrate from the rougher feed) duties. Their main challenges were recognized as relatively unclear procedure on their scale up/down, optimization and simulation. The HydroFloat™ cell was indicated as a promising technology for recovering coarse particle fraction sizes by taking advantage of the fluidized-bed concept with plug-flow dispersion regime, high particle residence time, and limited cell turbulence. We finally concluded that fine particle flotation may remain as the main focus of re-processing tailings dams, while coarse particle treatment should be the focus of this century to reduce total energy consumptions.

Keywords: Pneumatic flotation cells; Slurry retention time; Technological development; Flotation kinetics; Micron-sized bubbles

Permalink: https://www.hzdr.de/publications/Publ-34479


Teaching on Software Carpentry (Virtual) (2022-03-28-upr-online)

Shao, Z.

Abstract

Teaching "Programming with Python" for the workshop.
Workshop recordings are available on .

Keywords: Python

  • Software in external data repository
    Publication year 2022
    Programming language: Python
    System requirements: Python, jupyter
    License: Creative Commons Attribution license (Link to license text)
    Hosted on https://github.com/zdshaoteach/2022-03-28-upr-online: Link to location

Permalink: https://www.hzdr.de/publications/Publ-34478


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