Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41684 Publications

P–Ru-Complexes with a Chelate-Bridge-Switch: A Comparison of 2-Picolyl and 2-Pyridyloxy Moieties as Bridging Ligands

Ehrlich, L.; Gericke, R.; Brendler, E.; Wagler, J.

Abstract

Starting from [Ru(pyO)₂(nbd)] 1 and a N,P,N-tridentate ligand (2a: PhP(pic)₂, 2b: PhP(pyO)₂) (nbd = 2,5-norbornadiene, pic = 2-picolyl = 2-pyridylmethyl, pyO = 2-pyridyloxy = pyridine-2-olate), the compounds [PhP(μ-pic)₂(μ-pyO)Ru(κ²-pyO)] (3a) and [PhP(μ-pyO)₃Ru(κ²-pyO)] (3b), respectively, were prepared. Reaction of compounds 3 with CO and CNtBu afforded the opening of the Ru(κ²-pyO) chelate motif with the formation of compounds [PhP(μ-pic)₂(μ-pyO)Ru(κ-O-pyO)(CO)] (4a), [PhP(μ-pic)₂(μ-pyO)₂Ru(CNtBu)] (5a), [PhP(μ-pyO)₄Ru(CO)] (4b) and [PhP(μ-pyO)₄Ru(CNtBu)] (5b). In dichloromethane solution, 4a underwent a reaction with the solvent, i.e., substitution of the dangling pyO ligand by chloride with the formation of [PhP(μ-pic)₂(μ-pyO)Ru(Cl)(CO)] (6a). The new complexes 3a, 4a, 5a, 5b and 6a were characterized by single-crystal X-ray diffraction analyses and multi-nuclear (¹H, ¹³C, ³¹P) NMR spectroscopy. The different coordination behaviors of related pairs of molecules (i.e., pairs of 3, 4 and 5), which depend on the nature of the P–Ru-bridging ligand moieties (μ-pic vs. μ-pyO), were also studied via computational analyses using QTAIM (quantum theory of atoms in molecules) and NBO (natural bond orbital) approaches, as well as the NCI (non-covalent interactions descriptor) for weak intramolecular interactions.

Keywords: atoms-in-molecules; hemilabile; phosphane; ruthenium

Permalink: https://www.hzdr.de/publications/Publ-34635


NOVO - Neutron and Prompt Gamma-Ray Range Verification in Particle Therapy

Kögler, T.; Alagoz, E.; Ytre-Hauge, K. S.; Hysing, L. B.; Lathouwers, D.; Lionheart, W.; Obhodas, J.; Pausch, G.; Pettersen, H. E. S.; Ratliff, H. N.; Rovituso, M.; Schellhammer, S.; Setterdahl, L. M.; Skjerdal, K.; Sudac, D.; Turko, J. A. B.; Meric, I.

Abstract

Due to its high sensitivity to anatomical changes, particle therapy will only unfold its full potential together with a functioning online range verification. We present a detector concept making use of a large fraction of the secondary particles available by hybrid prompt gamma-ray and fast neutron imaging. The system is expected to exhibit a high detection sensitivity to these particles, a high time, energy and position resolution, excellent pulse shape discrimination, and a small footprint. It comprises a quasi-monolithic organic detector array consisting of novel organic scintillators with dual-ended silicon photomultiplier light read-out and fast digitizers. The reconstruction of the proton range from the events registered by the detector is based on gamma/neutron scatter kinematics, cone back-projection and maximum likelihood expectation maximization. Multiple studies are currently ongoing investigating the feasibility of this concept on an experimental and simulation level. A first Monte Carlo simulation study involving realistic patient data and an idealized detector has revealed that a range-shift sensitivity of 1 mm per spot is attainable for clinical spot weights. These results demonstrate the potential of particle treatment verification by fast neutrons and prompt gamma-rays and strengthen the potential of this hybrid system for clinical application.

Keywords: particle therapy; range verification; fast neutrons; prompt gamma rays; imaging

Involved research facilities

Related publications

  • Lecture (Conference) (Online presentation)
    IEEE Medical Imaging Conference 2022, 05.-12.11.2022, Milano, Italy

Permalink: https://www.hzdr.de/publications/Publ-34632


Development of a proton bunch monitor for treatment verification in particle therapy

Kögler, T.; Franke, A.; Makarevich, K.; Römer, K.; Tiebel, J.; Turko, J. A. B.; Wagner, A.; Weinberger, D.; Werner, R.-D.; Schellhammer, S.

Abstract

Treatment verification is a key element in future online-adaptive particle therapy. As a light-weight, collimator-free technique, Prompt γ-Ray Timing is a promising candidate for this purpose. The development of such a system for clinical application is challenging due to instabilities in the accelerator phase relation.
We present two proton bunch monitors which are capable of measuring and ultimately correct for these instabilities. Firstly, a diamond detector to be placed at the beam energy degrader was investigated. It was found to exhibit an excellent time resolution 82(6) ps and to be able to monitor the phase instability with sufficient precision in a realistic geometry. Secondly, a phase pick-up installed in the low level radio frequency module of the accelerator was used. The data acquired with this monitor showed a very good agreement with the diamond detector with smaller statistical fluctuations. In conclusion, both proton bunch monitors were shown to resolve phase instabilities in Prompt γ-Ray Timing and are expected to strengthen the potential of this system for clinical application.

Keywords: particle therapy; range verification; prompt gamma ray timing; proton bunch monitoring; diamond detector

Involved research facilities

Related publications

  • Lecture (Conference) (Online presentation)
    IEEE Medical Imaging Conference 2022, 05.-12.11.2022, Milano, Italy

Permalink: https://www.hzdr.de/publications/Publ-34631


Data publication: Calorimeter with Bayesian unfolding of spectra of high-flux broadband X-rays

Laso García, A.; Hannasch, A.; Molodtsova, M.; Ferrari, A.; Couperus Cabadağ, J. P.; Downer, M. C.; Irman, A.; Kraft, S.; Metzkes-Ng, J.; Naumann, L.; Prencipe, I.; Schramm, U.; Zeil, K.; Zgadzaj, R.; Ziegler, T.; Cowan, T.

Abstract

Data for the publication: Calorimeter with Bayesian unfolding of spectra of high-flux broadband X-rays Containing: - Raw datasets - Source code for extracting calibrated energy information from datasets - Source code for simulations - Source code for unfolding of spectra

Keywords: Technique and instrumentation; Relativistic laser plasmas; X-rays; Bremsstrahlung

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Permalink: https://www.hzdr.de/publications/Publ-34630


A proposal for calibration with locally varying references

van den Boogaart, K. G.; Tolosana Delgado, R.; Renno, A.

Abstract

Local Analysis aims at quantifying the local material composition at small measurement location, in larger heterogeneous specimen. In many cases it is technically impossible to produce homogeneous samples of that material classes to provide homogeneous standards or reference materials. The corresponding reasons are manifold, for example not reaching thermodynamic equilibrium, kinetic delays in crystallization, exsolution in solid solutions or immiscibility in glass-forming melts.

We therefore propose a class of methods to be coined “local calibration”, which would allow to establish traceability of local chemical measurements based on references consisting of heterogeneous reference specimen along with a new kind of description/certification for local analytical methods. Such a certification would not only define a single reference value, minimum sample size and accuracy, but describe in more detail, how the material can be used as reference, Such a description could for instance provide a measurement mask or rule ensuring that only certain minerals are used in reference measurements, or it could include a description of the local concentrations in a specimen with locally varying concentrations. The kinds of descriptions would depend on the type of heterogeneity of the reference specimen, the characteristics of the local measurement procedure it is certified for (like e.g. the interaction volume, or whether the method is destructive) and on technologies available for the description process. The methodology includes a validation procedure ensuring traceability.

The methodology is based on a simple observation: Local analysis only depends on a local material portion, and will deliver measurement values dependent of the local composition irrespective of a larger scale heterogeneity or homogeneity of the larger specimen. It is thus sufficient to provide an accurate and traceable value for the measurements which will be actually done during the use of the reference specimen. Depending on the type of heterogeneity this is however possible through various statistical and analytical strategies, such as, e.g. establishing a local map using a calibrated reference technique if such a technique is available, providing a geostatistical interpolation in case of slowly varying local concentration gradients, or by physical modeling the source of concentration differences (e.g. in case of a growth gradient). In each case all aspects of such a description can be checked statistically, based on control measurements.

Keywords: calibration; tracebility; heterogenious material

  • Lecture (Conference)
    Geoanalysis 2022, 06.-12.08.2022, Freiberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34628


Local control after locally ablative, image-guided radiotherapy of oligometastases identified by Gallium-68-PSMA-Positron Emission Tomography in castration-sensitive prostate cancer patients (OLI-P)

Hölscher, T.; Baumann, M.; Kotzerke, J.; Zöphel, K.; Paulsen, F.; Müller, A.; Zips, D.; Thomas, C.; Wirth, M.; Troost, E. G. C.; Krause, M.; Löck, S.; Lohaus, F.

Abstract

Progression of prostate-specific antigen (PSA) values after curative treatment of prostate
cancer patients is common. Prostate-specific membrane antigen (PSMA-) PET imaging can identify
patients with metachronous oligometastatic disease even at low PSA levels. Metastases-directed
local ablative radiotherapy (aRT) has been shown to be a safe treatment option. In this prospective
clinical trial, we evaluated local control and the pattern of tumor progression. Between 2014 and 2018,
63 patients received aRT of 89 metastases (MET) (68 lymph node (LN-)MET and 21 bony (OSS-)MET)
with one of two radiation treatment schedules: 50 Gy in 2 Gy fractions in 34 MET or 30 Gy in 10 Gy
fractions in 55 MET. The mean gross tumor volume and planning target volume were 2.2 and 14.9 mL,
respectively. The median follow-up time was 40.7 months. Local progression occurred in seven MET,
resulting in a local control rate of 93.5% after three years. Neither treatment schedule, target volume,
nor type of lesion was associated with local progression. Regional progression in the proximity to the
LN-MET was observed in 19 of 47 patients with at least one LN-MET (actuarial 59.3% free of regional
progression after 3 years). In 33 patients (52%), a distant progression was reported. The median time
to first tumor-related clinical event was 16.6 months, and 22.2% of patients had no tumor-related
clinical event after three years. A total of 14 patients (22%) had another aRT. In conclusion, local
ablative radiotherapy in patients with PSMA-PET staged oligometastatic prostate cancer may achieve
local control, but regional or distant progression is common. Further studies are warranted, e.g., to
define the optimal target volume coverage in LN-MET and OSS-MET.

Keywords: prostatic neoplasms; prospective studies; radiotherapy; image-guided; radiosurgery; positron emission tomography; prostate-specific antigen; neoplasm metastasis; local control

Permalink: https://www.hzdr.de/publications/Publ-34626


Hybrid in-vivo treatment verification for particle therapy: Multivariate modelling of fast neutron and gamma-ray detection

Pettersen, H. E. S.; Schellhammer, S.; Löck, S.; Kögler, T.; Meric, I.

Abstract

Given its sensitivity to anatomical variations, par-
ticle therapy is expected to benefit strongly from reliable on-
line treatment verification. Making use of a large fraction of
the secondary particles available, hybrid prompt gamma-ray and
fast neutron imaging is a promising approach for this purpose.
We present a simulation study introducing a novel method
for range reconstruction by means of these particles. To this
end, the passage of a proton beam through a patient and the
detection of secondary particles in a dedicated detector array
were simulated by Monte Carlo particle transport calculations.
Anatomical variations were mimicked by adding or removing
tissue to the patient. The secondary particle production vertices
were reconstructed from the events registered by the detector
based on scatter kinematics and maximum likelihood expectation
maximisation. The vertices were projected onto the beam axis
and the most predictive features of the resulting distributions
were identified from a standardised feature set by forward
feature selection and the Least Absolute Shrinkage and Selection
Operator (LASSO). A range-shift sensitivity of 1 mm or less
was reached at intensities of 1.2×10 7 protons per spot with
fast neutrons, and at 2.6×10 7 protons per spot with prompt
gamma-rays. These results demonstrate the potential of particle
treatment verification by fast neutrons and prompt gamma-rays
and strengthen the potential of this hybrid system for clinical
application.

Keywords: Treatment verification; fast neutron; prompt gamma-rays; feature selection; particle therapy

  • Lecture (Conference)
    2022 IEEE Nuclear Science Symposium (NSS), Medical Imaging Conference (MIC) and Room Temperature Semiconductor Detector (RTSD) Conference, 05.-12.11.2022, Milano, Italia

Permalink: https://www.hzdr.de/publications/Publ-34625


Test of the detector system for the Stopping Target Monitor of the Mu2e experiment in the presence of a high flux gamma background

Price, J.; Müller, S.; Ferrari, A.; Knodel, O.; Voigt, M.; Keshavarzi, A.; Motuk, E.; Judson, D.; Koltick, D.; Miller, J.; Plesniak, P.; Edmonds, A.; Ufer, R.; Huang, S.; Chen, J.; Chislett, R.; Lancaster, M.; Rachamin, R.; Tickle, S.; Alvarez, C.; Ginther, G.; Harkness-Brennan, L.

Abstract

These data were taken to characterize the performance and test the data acquisition system of two detectors to be used to monitor the stopping target for the forth-coming Mu2e experiment at Fermilab; the High Purity Germanium (HPGe) and Lanthanum Bromide (LaBr) Detectors, in the presence of the pulsed gamma beam at ELBE. This measurement is crucial for the normalisation of the Mu2e experiment. The corresponding beamtime was carried out at the gELBE bremsstrahlung beamline of HZDR's ELBE radiation facility from April 21 to April 25, 2022 (GATE ID: 21202619-ST). The data sets represent the data taken with the LaBr detector by means of an ORTEC DSPEC 50 and a Lecroy/Teledyne HDO4104 oscilloscope.

Keywords: dataset; detector; HPGe; LaBr3; Stopping target Monitor (STM); Mu2e; gELBE; Data Mangement; DAQ; muon conversion

Involved research facilities

Related publications

  • DOI: 10.58065/24020 is cited by this (Id 34624) publication
  • DOI: 10.17815/jlsrf-2-58 is cited by this (Id 34624) publication
  • HANDLE: 20.500.12865/HZDR.Projects.2022.FWCC.Project.74 documents this (Id 34624) publication

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Permalink: https://www.hzdr.de/publications/Publ-34624


Horizont 2020 Projekt: „Sodium-Zinc molten salt batteries for low-cost stationary storage“

Weber, N.

Abstract

Der Vortrag gibt einen Überblick über die Erfahrungen bei der Antragstellung des Horizon 2020-Projekts SOLSTICE.

  • Invited lecture (Conferences) (Online presentation)
    Aktuelle Förderinstrumente der EU im Bereich Energie - Details, Hinweise und Erfahrungsberichte, 11.05.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34622


Natrium-Zink Salzschmelzenbatterien als stationäre Energiespeicher

Weber, N.

Abstract

Der Vortrag gibt einen Überblick über das Forschungsvorhaben SOLSTICE sowie die ersten Ergebnisse.

  • Invited lecture (Conferences)
    5. Vernetzungsveranstaltung im Bereich Energieinnovation - Chancen für sächsische und ostdeutsche Akteure, 13.05.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34621


Prospects for precise predictions of $a_\mu$ in the Standard Model

Colangelo, G.; Davier, M.; El-Khadra, A. X.; Hoferichter, M.; Lehner, C.; Lellouch, L.; Mibe, T.; Roberts, B. L.; Teubner, T.; Wittig, H.; Ananthanarayan, B.; Bashir, A.; Bijnens, J.; Blum, T.; Boyle, P.; Bray-Ali, N.; Caprini, I.; Carloni Calame, C. M.; Catà, O.; Cè, M.; Charles, J.; Christ, N. H.; Curciarello, F.; Danilkin, I.; Das, D.; Deineka, O.; Della Morte, M.; Denig, A.; Detar, C. E.; Dominguez, C. A.; Eichmann, G.; Fischer, C. S.; Gérardin, A.; Giusti, D.; Golterman, M.; Gottlieb, S.; Gülpers, V.; Hagelstein, F.; Hayakawa, M.; Hermansson-Truedsson, N.; Hoid, B.-L.; Holz, S.; Izubuchi, T.; Jüttner, A.; Keshavarzi, A.; Knecht, M.; Kronfeld, A. S.; Kubis, B.; Kupść, A.; Lahert, S.; Liu, K. F.; Lüdtke, J.; Lynch, M.; Malaescu, B.; Maltman, K.; Marciano, W.; Marinković, M. K.; Masjuan, P.; Meyer, H. B.; Müller, S.; Neil, E. T.; Passera, M.; Pepe, M.; Peris, S.; Petrov, A. A.; Procura, M.; Raya, K.; Rebhan, A.; Risch, A.; Rodríguez-Sánchez, A.; Roig, P.; Sánchez-Puertas, P.; Simula, S.; Stoffer, P.; Stokes, F. M.; Sugar, R.; Tsang, J. T.; van de Water, R. S.; Vaquero Avilés-Casco, A.; Venanzoni, G.; von Hippel, G. M.; Zhang, Z.

Abstract

We discuss the prospects for improving the precision on the hadronic corrections to
the anomalous magnetic moment of the muon, and the plans of the Muon g − 2 Theory
Initiative to update the Standard Model prediction.

Keywords: muon anomalous magnetic moment; g-2; a_mu

Permalink: https://www.hzdr.de/publications/Publ-34620


Krebsforschung mit laserbeschleunigten Protonen

Kroll, F.; Zeil, K.; Brack, F.-E.; Beyreuther, E.

Abstract

Durch Hochleistungslaser getriebene Protonenquellen stellen eine interessante Ergänzung zu konventionellen Protonenbeschleunigern dar, insbesondere für die radiobiologische Forschung. Unserem interdisziplinären Forschungsteam ist es erstmals gelungen, eine radiobiologische Kleintierstudie mit laserbeschleunigten Protonen durchzuführen.

Keywords: Laserbeschleunigung; Radiobiologie; Protonentherapie

Permalink: https://www.hzdr.de/publications/Publ-34619


The Training Catalogue for Photon and Neutron Data Services

Knodel, O.; Konrad, U.; Valcarcel-Orti, A.; Padovani, A.

Abstract

Education is becoming an increasingly important topic to help scientists work on photon and neutron sources. Other relevant areas such as advanced quantum technologies will also play a key role in the future.

One of the goals of ExPaNDS (European Open Science Cloud (EOSC) Photon and Neutron Data Service) is to train research scientists in order to better understand the issues, methods and available computational RI infrastructures to address critical research questions.

Our PaN-training catalogue provides a one-stop shop for trainers and trainees to discover online information and content:

* For trainers the catalogue offers an environment for sharing materials and event information.
* For trainees, it offers a convenient gateway via which to identify relevant training events and resources, and to perform specific, guided analysis tasks via training workflows to provide FAIR research.

Keywords: training; photon science; neutron science; e-learning; catalogue; data management

Related publications

  • Open Access Logo Poster
    LEAPS meets Quantum Technology Conference, 15.-21.05.2022, La Biodola Bay, Elba Island, Italy
    DOI: 10.5281/zenodo.6491949
  • Open Access Logo Poster
    Annual EGI conference 2022, 20.-22.09.2022, Prague, Czech Republic
    DOI: 10.5281/zenodo.6491948
  • Open Access Logo Lecture (Conference)
    EOSC Symposium 2022, 14.-17.11.2022, Prag, Tschechische Republik
  • Open Access Logo Invited lecture (Conferences)
    ExPaNDS closing event, 23.-24.01.2023, Hamburg, Germany

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Permalink: https://www.hzdr.de/publications/Publ-34618


Process characterization in industrial vessels by flow-following sensor particles

Reinecke, S.; Buntkiel, L.; Kipping, R.; Hampel, U.

Abstract

Instrumented flow-following sensor particles have been developed for investigation of hydrodynamic and biochemical processes in chemical reactors and bioreactors, where standard measurement techniques are not applicable. The sensor particles allow autonomous long-term measurement of spatially distributed process parameters in the chemically and mechanically harsh environments of e.g. agitated industrial vessels. Each sensor particle comprises of an on-board measurement electronics that logs the signals of the embedded sensors. A buoyancy control unit enables automated taring to achieve neutral buoyancy of the sensor particles. Moreover, controlled floating of the sensor particles is possible to expose them for recovery from the liquid surface. Macro-flow tracking of the sensor particles is validated with circulation time reference measurements by means of salt tracer experiments in a stirred model reactor and CFD simulations. Moreover, process characterization with sensor particles is demonstrated in three further applications, namely a biogas pilot digester, an air-water column and a biological wastewater treatment basin. Acquired data were used to fit mixing model parameters, namely effective circulation time, circulation number, degree of suspension and Péclet number.

Keywords: sensor particle; flow follower; flow tracking; mixing model; bioreactor

Involved research facilities

  • TOPFLOW Facility

Permalink: https://www.hzdr.de/publications/Publ-34617


Magnetometric exploration of the phase diagrams of Yb-based delafossites

Luther, S.

Abstract

The Yb-based delafossites NaYbCh2 (Ch = O, S, Se) are planar triangular-lattice spin systems with a trigonal crystal structure (space group R-3m). In these compounds, a strong spin-orbit coupling, combined with crystalline-electric-field effects, leads to a pronounced magnetic anisotropy and a pseudospin-1/2 spin-liquid ground state at low temperatures. The chalcogen series provides the possibility for tuning the interlayer distance and the associated exchange couplings by changing the chemical composition. The absence of magnetic long-range order at zero field down to lowest temperatures is strongly suggestive of a quantum spin-liquid ground state. Relaxation measurements by means of µSR and NMR have shown persistent strong fluctuations down to 100 mK at low magnetic fields. Based on specific-heat and magnetization experiments, we have observed magnetic order for out-of-plane fields exceeding 2 T for all three compounds. For in-plane fields of several tesla, a plateau-like feature in the magnetization indicates an up-up-down spin arrangement [1-3]. Furthermore, our measurements up to fields of 30 T allow to probe the saturation fields and polarized moments and, thus, the determination of the anisotropic exchange couplings [4]. Our 23Na NMR measurements of NaYbSe2 aim to probe the microscopic details of the field-induced magnetic structure in this compound. Measurements of the field-dependent transition temperature to long-range order via the 1/𝑇1-relaxation rate are in agreement with the specific-heat results. The in-plane up-up-down spin arrangement is leading to an asymmetric broadening of the NMR spectra. At elevated out-of-plane fields, an umbrella-type configuration of the magnetic moments is predicted and in agreement with a symmetric broadening of the 23Na NMR spectra. Low-field measurements reveal a monotonic low-temperature increase of the 1/𝑇1-relaxation rate and spectral broadening, without any signature of long-range order down to 0.3 K.

[1] M. Baenitz et al., Phys. Rev. B 98, 220409(R) (2018)
[2] K. M. Ranjith et al., Phys. Rev. B 99, 180401(R) (2019)
[3] K. M. Ranjith et al., Phys. Rev. B 100, 224417 (2019)
[4] B. Schmidt et al., Phys. Rev. B 103, 214445 (2021)

Involved research facilities

  • High Magnetic Field Laboratory (HLD)
  • Lecture (others)
    IFPM Seminar, 17.05.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34616


A quasi-bivariate approach to tracking secondary particle properties within the class method framework

Lehnigk, R.; Lucas, D.; Niemi, T.; Peltola, J.; Schlegel, F.

Abstract

In many polydisperse multiphase flows, the fluid or solid particles are not only distributed over size, but also with respect to other variables such as their velocity, shape, temperature or chemical composition, in which case the corresponding population balance is referred to as bi- or multivariate, respectively as two- or multidimensional. While industrial Computational Fluid Dynamics (CFD) simulations of disperse multiphase flows increasingly include approximate solutions of univariate population balance equations, e.g. for tracking the particle size distribution by means of class or quadrature-based moment methods, bivariate solution approaches are still a subject of research. This contribution highlights an aspect of recently published work (Lehnigk et al. 2022) [1], wherein a quasi-bivariate approach to tracking secondary particle properties in the class method framework is presented and demonstrated for the simulation of a bubbly flow in a vertical pipe as well as the synthesis of titania powder in a furnace reactor. In the former case, the velocity is selected as secondary property, since shear in the liquid phase can result in a pronounced radial separation of bubbles depending on their size. For the latter case, the surface area to volume ratio of the particle aggregates is used to describe the fractal-like shape of the aggregates, which influences the collision frequency and by extension also the aggregate size distribution.

[1] R. Lehnigk, W. Bainbridge, Y. Liao, D. Lucas, T. Niemi, J. Peltola, F. Schlegel, An open-source population balance modeling framework for the simulation of polydisperse multiphase flows, AIChe J. 68[3] (2022) e17539. https://doi.org/10.1002/aic.17539.

  • Poster
    7th International Conference on Population Balance Modelling (PBM 2022), 09.-11.05.2022, Lyon, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-34615


Hybrid Classical-Quantum Machine Learning Algorithms for Large Scale Applications

Konar, D.

Abstract

In this talk, I will be discussing primarily on quantum machine learning, quantum optimization, hybrid classical-quantum neural networks with a direct application on computer vision, material science etc. Hybrid classical-quantum spiking and Random neural networks are highly promising candidate for quantum advantage. We propose a novel framework to demonstrate the feasibility of Hybrid Classical-Quantum Neural Networks (HCQNN) employing Variational Quantum Circuit (VQC) in the dressed quantum layer. The HCQNN relies on a hybrid classical-quantum circuit with gate parameters optimized during training. The dressed quantum layer in the suggested DSQ-Net model as a VQC are capable of being trained with thousands of parameters employed in the architecture. The HCQNN model has been experimented on various computer vision datasets using the Penny Lane quantum simulator.
Moreover, we are also working on Hybrid Parameterized Quantum Supervised Learning Classifiers. To obviate the data reduction before feeding to the circuit, dense parameterized quantum circuits (VQC) with lesser number trainable parameters have been proposed without compromising the classification accuracy. Recently, we have developed Quantum Kernel Integrated Ridge Regression for the direct applications to material science which will be also the part of our discussion. Finally, I will shed some light in to the future of quantum machine learning and the feasibility of quantum deep learning for large-scale applications.

Keywords: Quantum computing; Quantum Machine Learning; Computer Vision; Quantum Neural Networks

  • Invited lecture (Conferences) (Online presentation)
    11th IEEE International Conference on Communication Systems and Network Technologies (CSNT 2022), 23.-24.04.2022, Indore, India

Permalink: https://www.hzdr.de/publications/Publ-34614


The Influence Of Surface Cover And Bedrock Geology On The Snow Geochemistry – An Example From Northern Finland

Taivalkoski, A.; Pospiech, S.; Middleton, M.; Lahaye, Y.; Kinnunen, J.

Abstract

The idea of using snow in mineral exploration is due to the needs of environmentally friendly sampling methods for the ecologically sensitive northern areas. Not only the environmental issues, but the low costs of sampling and relieving permission issues encourage researchers to find new methods for mineral exploration. Surface geochemical methods, including sampling plants, topsoil horizons and snow can be considered in the areas where machinery is not allowed. Moreover, surface geochemical methods can provide the information of metal ions derived from the deep-seated mineralization below. The advantages of snow sampling are low volume of sample material, (comparably) light sample material and sampling equipment and therefore the option for low impact sampling campaign by skies or snowshoes.
In the New Exploration Technologies (NEXT) project*, 165 snow samples together with 13 field duplicate snow samples for quality control, were collected in March-April winter 2019. The aim was to estimate with statistical methods the usage of snow as a sampling material for mineral exploration. The samples were collected on the Rajapalot Au-Co prospect in northern Finland, 60 km west from Rovaniemi, operated by Mawson Oy. Stratified random sampling method was used to calculate sampling locations with balanced number of points per soil type and geophysical parameter, but randomly distributedwithin the strata over the test area. The samples were analysed in the Research Laboratory of the Geological Survey of Finland using a Nu AttoM single collector inductively coupled plasma mass spectrometry (SC-ICPMS) and returned analytical results for 52 elements at ppt level.
Of the analysed elements Ba, Ca, Li, Mg, Mo, Rb, Sr and V passed the strict quality control and were used for the final data analysis. Prior to statistical methods, the geochemical data was transformed to log-ratio scores in order to ensure that results are independent of the selection of elements and to avoid spurious correlations (compositional data approach). The results indicate strong dependency of the snow element composition to the soil type, meaning that there is systematic shift of element pattern if the snow sample was taken above mineral soil or organic soil. Thus, the soil type should be included in models to predict (geological) features below the surface or interpretation of snow data should be performed separately for different soil types. The impact of subsurface features on the snow geochemistry could only be tested indirectly by using geophysical data as proxy for characteristics of the basement rock. Based on linear models, it seems that snow geochemistry could be used as a mapping tool for delineating the areas of major geological units. Given the selection of analytical available elements, snow sampling could serve as a proxy where to continue exploration with different methods rather than directly pointing out the mineralized zones.

Keywords: snow; exploration; geochemistry; statistics; compositional data

  • Lecture (Conference)
    Nordic Geological Winter Meeting, Reykjavik, 11.-13.05.2022, Reykjavik, Iceland

Permalink: https://www.hzdr.de/publications/Publ-34613


A Scalable 5,6-Qubit Grover's Quantum Search Algorithm

Vemula, D. R.; Konar, D.; Satheesan, S.; Cangi, A.

Abstract

Recent studies have been spurred on by the promise of advanced quantum computing technology, which has led to the development of quantum computer simulations on classical hardware. Grover's quantum search algorithm is one of the well-known applications of quantum computing, enabling quantum computers to perform a database search (unsorted array) and quadratically outperform their classical counterparts in terms of time. Given the restricted access to database search for an oracle model (black-box), researchers have demonstrated various implementations of Grover's circuit for two to four qubits on various platforms. However, larger search spaces have not yet been explored. In this paper, a scalable Quantum Grover Search algorithm is introduced and implemented using 5-qubit and 6-qubit quantum circuits, along with a design pattern for ease of building an Oracle for a higher order of qubits. For our implementation, the probability of finding the correct entity is in the high nineties. The accuracy of the proposed 5-qubit and 6-qubit circuits is benchmarked against the state-of-the-art implementations for 3-qubit and 4-qubit. Furthermore, the reusability of the proposed quantum circuits using subroutines is also illustrated by the opportunity for large-scale implementation of quantum algorithms in the future.

Keywords: Quantum Computing; Grover’s search algorithm; IBM quantum computer; qubit

Permalink: https://www.hzdr.de/publications/Publ-34612


Properties of Cr2AlC thin films disordered by ion-irradiation

Salgado Cabaco, J.; Kentsch, U.; Lindner, J.; Faßbender, J.; Leyens, C.; Bali, R.; Boucher, R.

Abstract

MAX phases are nano-lamellar composite materials of the form Mn+1AXn, where n is 1, 2 or 3; M an early transition metal; A is an A-group element and X is carbon or nitrogen [1,2]. An interesting combination of metallic and ceramic properties as well as potential applications in spintronics [1,3] led to significant research interest in MAX phases. Literature on the effect of systematic disordering of the nano-laminar structure on the magnetic and transport properties is still limited. In particular, MAX phase systems doped with magnetic ions via ion-irradiation may result in large variations of the magneto-transport properties. Here we observe the magneto-transport properties and attempt to separate the contributions of structural changes due to the irradiation and magnetic effects due to the doping on the magneto-transport. A prototype material is Cr2AlC, formed from a unit cell of Cr2C sandwiched between atomic planes of Al. In this work, we study 50 nm and 500 nm thick thin films of Cr2AlC grown on Si (111) by sputtering and subsequent annealing. Structural characterization using X-ray Diffraction in Bragg-Brentano geometry shows a pronounced MAX phase, confirmed by the occurrence of the 002 superlattice reflection. The films were irradiated with Co+ at 450 (50) keV for the 500 (50) nm thick films. The Co+ fluence varied between 1×10^12 - 1×10^15 ions.cm^-2, in full order steps. The Co+ irradiation led to a gradual suppression of the 0002 superstructure reflection, while preserving the fundamental peaks, implying the intermixing of the nano-laminar MAX phase structure. The magnetic properties are characterized using vibrating sample magnetometry at low temperatures, showing an increasing paramagnetic behavior as the Co+-fluence increases. In comparison, magneto-resistance measurements show that for the 500 nm film thickness, the magnetoresistance reaches up to 3 % (10 T) for 100 K, at an optimized Co+-fluence of 5×10^13 ions.cm^-2. The above results suggest that in the low-fluence regime, the irradiation-induced disorder remains sufficiently low to obtain pronounced magneto-resistance values. Understanding the defect state in the optimized MAX phase films will shed light on the magneto-transport mechanisms in these nano-laminated materials.

Keywords: Ion Irradiation; X-ray diffraction; Disorder; MAX phases

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  • Poster
    22nd International Conference on Ion Beam Modification of Materials, 10.-15.07.2022, Lisbon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-34611


Combining a SIMS with AMS: Super-SIMS at DREAMS - Status of this challenging initiative

Rugel, G.

Abstract

At the DREAMS (DREsden AMS) facility [1,2] we are implementing a so-called Super-SIMS (SIMS =
Secondary Ion Mass Spectrometry) device [3] for specialized applications. The system combines the spatial
resolution capability of a commercial SIMS (CAMECA IMS 7f-auto) with AMS capability, which should
suppress molecular isobars in the ion beam allowing for the quantification of elemental abundances down to
~ E-9 - E-12. This would be more than an order of magnitude improvement over traditional dynamic SIMS
(e.g. [4,5]). We aim to use this for the highly sensitive analysis of geological samples in the context of
resource technology.
In the present setup, high efficiency transmission in the low-energy ion optics segment remains a challenge,
as the beam needs to traverse two existing magnet chambers without deflection, where no steering or lens
elements are available over a flight distance of 4 m. We have now improved the low-energy injection just
after the ion beam exits the 7f-auto, upgrading the steerers directly after the SIMS and by adding a beam
intensity attenuator. This provides both more stable conditions for instrument tuning and simplifies transition
between measurements of the beam intensity in Faraday cups and the gas ionization chamber. Regarding the
measurement of C, N and O in silicon, we found that a simple Wien-filter using permanent magnets for the
primary Cs-sputter beam significantly reduces the background at the detector, as the 7f-auto uses a Cs₂ CO₃
source – rather than metallic Cs – for the generation of the primary positive Cs beam.
Once the remaining issues associated with ion beam-path are fully addressed, we will still need to tackle the
issue of establishing suitable, well characterized reference materials needed for our first suite of resource and
geoscience applications (e.g., halides in naturally occurring sulphide minerals). We present ongoing
developments and results, as well as plans for extending to other matrices and isotope systems.
[1] S. Akhmadaliev et al., NIMB 294 (2013) 5. [2] G. Rugel et al. NIMB 370 (2016) 94. [3] J. M. Anthony,
D. J. Donahue, A. J. T. Jull, MRS Proceedings 69 (1986) 311-316. [4] C. Maden, PhD thesis, ETH Zurich
2003. [5] S. Matteson, Mass Spectrom. Rev., 27 (2008) 470.

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  • Invited lecture (Conferences) (Online presentation)
    National Workshop on "Chronological systematics and their applications in Earth Sciences", 19.-21.04.2022, New Delhi, India

Permalink: https://www.hzdr.de/publications/Publ-34610


Data Publication: Protein Enrichment by Foam Fractionation: Experiment and Modeling

Keshavarzi, B.; Krause, T.; Sikandar, S.; Schwarzenberger, K.; Eckert, K.; Ansorge-Schumacher, M.; Heitkam, S.

Abstract

This work investigates the enrichment of bovine serum albumin (BSA) protein through foam fractionation. Here, we performed experiments using BSA and measured the recovery and grade of the extract. Additionally, an unsteady-state simulation of the protein foam fractionation process was carried out by numerically solving the liquid drainage equation in the foam. Thereby, the extracted liquid volume and protein concentration were calculated. Required quantities such as foam stability, interface coverage or bubble size distribution were measured in corresponding experiments and were fed into the model. The experiments showed that the foam coalescence accelerates the liquid drainage leading to dryer extract and higher protein enrichment. The modeling also reproduced the liquid recovery and extract concentration of the foam fractionation tests within a reasonable error range. The modeling solely relies on experimental inputs and does not require any tuning parameters. It can be further used for optimization or up-scaling of protein foam fractionation.

Keywords: Protein; foam fractionation; flotation; modeling; dynamic adsorption; surface equation of state; flow-on-bubble

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Permalink: https://www.hzdr.de/publications/Publ-34609


Protein Enrichment by Foam Fractionation: Experiment and Modeling

Keshavarzi, B.; Krause, T.; Sikandar, S.; Schwarzenberger, K.; Eckert, K.; Ansorge-Schumacher, M.; Heitkam, S.

Abstract

This work investigates the enrichment of bovine serum albumin (BSA) protein through foam fractionation. Here, we performed experiments using BSA and measured the recovery and grade of the extract. Additionally, an unsteady-state simulation of the protein foam fractionation process was carried out by numerically solving the liquid drainage equation in the foam. Thereby, the extracted liquid volume and protein concentration were calculated. Required quantities such as foam stability, interface coverage or bubble size distribution were measured in corresponding experiments and were fed into the model. The experiments showed that the foam coalescence accelerates the liquid drainage leading to dryer extract and higher protein enrichment. The modeling also reproduced the liquid recovery and extract concentration of the foam fractionation tests within a reasonable error range. The modeling solely relies on experimental inputs and does not require any tuning parameters. It can be further used for optimization or up-scaling of protein foam fractionation.

Keywords: Protein; foam fractionation; flotation; modeling; dynamic adsorption; surface equation of state; flow-on-bubble

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Permalink: https://www.hzdr.de/publications/Publ-34606


Generic Library for Asynchronous Data Operations and Streaming - GLADOS

Windisch, D.; Bieberle, A.

Abstract

Generic Library for Asynchronous Data Operations and Streaming (GLADOS) provides a framework for data stream processing in a pipeline scheme. GLADOS provides a managed memory pool for device memory and host memory which allows high-throughput processing of streams without runtime memory allocations. GLADOS supports the fork-join paradigm to allow for parallel processing branches and the subject-observer pattern for asychnronous control of the process. Implementations of the processing steps use C++ templates and can therefore be adapted very flexibly.

Keywords: Pipeline; Data processing; C++; CUDA

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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/GLADOS: Link to location

Permalink: https://www.hzdr.de/publications/Publ-34605


Real-time Image Stream Algorithms: Core Library - libRISA_Core

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.

The libRISA_Core library includes basic image processing algorithms, e.g., for filtering, masking, transforming (FFT) and displaying data.

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

Related publications

  • 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/librisa_core: Link to location

Permalink: https://www.hzdr.de/publications/Publ-34604


Targeting CD10 on B-Cell Leukemia Using the Universal CAR T-Cell Platform (UniCAR)

Mitwasi, N.; Arndt, C.; Loureiro, L. R.; Kegler, A.; Fasslrinner, F.; Berndt, N.; Bergmann, R.; HoˇRejší, V.; Rössig, C.; Bachmann, M.; Feldmann, A.

Abstract

Chimeric antigen receptor (CAR)-expressing T-cells are without a doubt a breakthrough therapy for hematological malignancies. Despite their success, clinical experience has revealed several challenges, which include relapse after targeting single antigens such as CD19 in the case of B-cell acute lymphoblastic leukemia (B-ALL), and the occurrence of side effects that could be severe in some cases. Therefore, it became clear that improved safety approaches, and targeting multiple antigens, should be considered to further improve CAR T-cell therapy for B-ALL. In this paper, we address both issues by investigating the use of CD10 as a therapeutic target for B-ALL with our switchable UniCAR system. The UniCAR platform is a modular platform that depends on the presence of two elements to function. These include UniCAR T-cells and the target modules (TMs), which cross-link the T-cells to their respective targets on tumor cells. The TMs function as keys that control the switchability of UniCAR T-cells. Here, we demonstrate that UniCAR T-cells, armed with anti-CD10 TM, can efficiently kill B-ALL cell lines, as well as patient-derived B-ALL blasts, thereby highlighting the exciting possibility for using CD10 as an emerging therapeutic target for B-cell malignancies.

Keywords: CD10; immunotherapy; CAR T-cells

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Permalink: https://www.hzdr.de/publications/Publ-34603


Teaching Workshop: Software Carpentry Workshop, Unix shell, Git, and Programming with Python

Zongru Doris Shao, R. H.

Abstract

Teaching Software Carpentry Workshop

Keywords: Python; Git; Shell

  • Open Access Logo Lecture (others) (Online presentation)
    Software Carpentry Workshop, 16.-19.05.2022, University of Twente, online, Netherlands

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Permalink: https://www.hzdr.de/publications/Publ-34602


Personnel staffing and scheduling during COVID-19 pandemic: A contact network-based analysis

Batista German, A. C.; Senapati, A.; Davoodi Monfared, M.; Calabrese, J.

Abstract

The COVID-19 pandemic has disrupted global operations, compromising people's health and safety. Several organizations, in particular, have been forced to shift their operations to a hybrid system (working from home) to prevent the spread of the virus and ensure employee safety. Although working from home is effective for some organizations, others need to find a balance between workplace occupancy and risk of infection to keep their operations functioning efficiently. We address this issue through contact network analysis by investigating the impact of employee interactions on virus spread in closed environments. We develop a staffing model for the scheduling of employees, considering contact networks. The goal is to maximize occupancy while minimizing the risk of infection. We aim to find the optimal composition of staff differing by priority to be allocated over a specified discrete-time horizon. We propose a Mixed Integer Non-Linear Programming (MINLP) model considering a Microscopic Markov Chain Approach (MMCA) to determine the probability of infection in a contact network based on the employee’s interactions. We assess the effectiveness of the approach through simulation, considering several contact network structures and interventions such as testing, vaccination, and personal protection. Through extensive computational analysis, we show that workplace occupancy can be efficiently balanced while keeping safety in the workplace.

Keywords: scheduling; optimization; disease modeling; Markov Chain

  • Open Access Logo Lecture (Conference)
    48th Annual Meeting of the Euro Working Group on Operational Research Applied to Health Services, 17.-22.07.2022, Bergamo, Italy

Permalink: https://www.hzdr.de/publications/Publ-34601


Therapeutic potential of repetitive AC-magnetic treatments on iPSC-derived motoneurons from ALS patients to improve axonal regeneration

Kandhavivorn, W.

Abstract

lecture seminar for Ph.D. candidates at Center for Radiopharmaceutical Tumor Research (ZRT), HZDR
es hat keine Inhaltsangabe dafür vorgelegen

Involved research facilities

  • High Magnetic Field Laboratory (HLD)
  • Lecture (others) (Online presentation)
    Lecture Seminar for Ph.D. candidates at Center for Radiopharmaceutical Tumor Research (ZRT), HZDR, 25.04.2022, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-34600


The application of AC-magnetic stimulations on iPSC-derived motoneurons from ALS patients to improve axonal regeneration for therapeutic potential in neurodegeneration

Kandhavivorn, W.

Abstract

lecture in EGBE 693 Research Seminar for Biomedical Engineering II for graduate students at the Department of Biomedical Engineering, Faculty of Engineering, Mahidol University Thailand
es hat keine Inhaltsangabe dafür vorgelegen

Involved research facilities

  • High Magnetic Field Laboratory (HLD)
  • Lecture (Conference) (Online presentation)
    EGBE 693 Research Seminar for Biomedical Engineering II for graduate students, 18.01.2022, Nakhon Pathom, Thailand

Permalink: https://www.hzdr.de/publications/Publ-34599


Radiomics-based differentiation of lung disease models generated by polluted air based on X-ray computed tomography data

Szigeti, K.; Szabó, T.; Korom, C.; Ilona, C.; Horváth, I.; Veres, D. S.; Gyöngyi, Z.; Karlinger, K.; Bergmann, R.; Pócsik, M.; Budán, F.; Máthé, D.

Abstract

Background: Lung diseases (resulting from air pollution) require a widely accessible method for risk estimation and arly diagnosis to ensure proper and responsive treatment. Radiomics-based fractal dimension analysis of X-ray computed tomography attenuation patterns in chest voxels of mice exposed to different air polluting agents was performed to model early stages of disease and establish differential diagnosis.
Methods: To model different types of air pollution, BALBc/ByJ mouse groups were exposed to cigarette smoke combined with ozone, sulphur dioxide gas and a control group was established. Two weeks after exposure, the frequency distributions of image voxel attenuation data were evaluated. Specific cut-off ranges were defined to group voxels by attenuation. Cut-off ranges were binarized and their spatial pattern was associated with calculated fractal dimension, then abstracted by the fractal dimension – cut-off range mathematical function. Nonparametric
Kruskal-Wallis (KW) and Mann–Whitney post hoc (MWph) tests were used.
Results: Each cut-off range versus fractal dimension function plot was found to contain two distinctive Gaussian curves. The ratios of the Gaussian curve parameters are considerably significant and are statistically distinguishable within the three exposure groups.
Conclusions: A new radiomics evaluation method was established based on analysis of the fractal dimension of chest X-ray computed tomography data segments. The specific attenuation patterns calculated utilizing our method may diagnose and monitor certain lung diseases, such as chronic obstructive pulmonary disease (COPD), asthma, tuberculosis or lung carcinomas.

Keywords: Fractal dimension; Radiomics; In vivo micro-CT; Air pollution; Lung disease

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  • PET-Center

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Permalink: https://www.hzdr.de/publications/Publ-34597


Euler-Euler / RANS Modeling of Solid-liquid Flow in Stirred Tanks: a Comprehensive Model Validation

Shi, P.; Sommer, A.-E.; Rox, H.; Eckert, K.; Rzehak, R.

Abstract

Simulations of solid-liquid flow on industrial scales are feasible within the Euler-Euler / RANS approach. The reliability of this approach depends largely on the closure models applied to describe the unresolved phenomena at the particle scale, in particular the interfacial forces. In this work, a set of closure models assembled previously for this kind of application (Shi and Rzehak 2020) is further validated by comparing the predictions to a recent experiment on stirred-tank flows (Sommer et al. 2021), which focuses on dilute suspensions. The dataset used for validation comprises 14 different experimental cases, covering a wide range of particle slip Reynolds number, impeller Reynolds number, and particle Stokes number. For each case, simulation results on the solid velocity and volume fraction as well as liquid velocity and turbulence are compared with the experimental data. It turns out that by and large the experimental data are reasonably well reproduced. However, the measurements show a small but clear effect of modulation of the liquid phase turbulence by the particles. Therefore, several particle-induced turbulence (PIT) models based on the available literature are assessed as well. Our results indicate a reduction in the predicted fluctuations by all PIT models, which improves the results in cases with turbulence suppression but deteriorates those with turbulence augmentation.

Keywords: stirred tanks; solid-liquid flow; Euler-Euler two-fluid model; Reynolds-stress turbulence model; particle-induced turbulence

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Permalink: https://www.hzdr.de/publications/Publ-34596


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++

Related publications

  • 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

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  • 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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Permalink: https://www.hzdr.de/publications/Publ-34550


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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  • Open Access Logo Poster (Online presentation)
    virtual DPG-Frühjahrstagungen (DPG Spring Meetings) 2021, 27.-30.09.2021, Online, Germany

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Permalink: https://www.hzdr.de/publications/Publ-34549


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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Permalink: https://www.hzdr.de/publications/Publ-34548


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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Permalink: https://www.hzdr.de/publications/Publ-34545


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

Permalink: https://www.hzdr.de/publications/Publ-34544


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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Permalink: https://www.hzdr.de/publications/Publ-34543


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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Permalink: https://www.hzdr.de/publications/Publ-34542


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.

Involved research facilities

  • 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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Permalink: https://www.hzdr.de/publications/Publ-34540


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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Permalink: https://www.hzdr.de/publications/Publ-34538


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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Permalink: https://www.hzdr.de/publications/Publ-34535


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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Permalink: https://www.hzdr.de/publications/Publ-34534


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


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