Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41421 Publications

Helmholtz Open Science Forum “Research Evaluation, Reputation Systems, and Openness”

Genderjahn, S.; Bertelmann, R.; Ferguson, L. M.; Graf Zu Castell-Rüdenhausen, W.; Dransch, D.; Juckeland, G.; Kiesselbach, M.; Köhler, M.; Rank, S.; Rohmann, J. L.; Upmeier, A.; Wiesenfeldt, S.

On May 9, 2023, the Helmholtz Open Science Office organized the Forum "Research Evaluation, Reputation Systems, and Openness". On this occasion, experts from Helmholtz and the scientific community presented current developments in the field of research evaluation and reflected on the connection between reputation systems and openness. The event focused on three main topics: 1) Development of Helmholtz quality indicators for data and software products, 2) 10 years Declaration on Research Assessment (DORA) and 3) Coalition for Advancing Research Assessment (CoARA). A central subject in the discussion and presentations was the issue of the use and definitions of indicators which foster Open Science. The discussion centered on what appropriate incentives look like in order to make research evaluation fair and appreciative. Furthermore, the relevance of these questions from the perspective of early-career scientists was highlighted.

Permalink: https://www.hzdr.de/publications/Publ-37450
Publ.-Id: 37450


Hydrodynamics in a Bubble Column – Part 1: Two-Phase Flow

Sommer, A.-E.; Draw, M.; Wang, L.; Schmidtpeter, J.; Hessenkemper, H.; Gatter, J.; Nam, H.; Eckert, K.; Rzehak, R.

Multiphase computational fluid dynamics (CFD) simulation is a useful tool to study the hydrodynamics in a bubble column if
appropriate closure models are known. Systematic assessment of different models is an ongoing venture that benefits from
improved validation data. The present study accumulates a database on two-phase flow experiments in a bubble column.
This is achieved by using a combination of particle image velocimetry and shadowgraphy to measure the liquid velocity field
and gas dispersion properties simultaneously. This methodology is applied for different needle diameters and gas flow rates.
The experimental data are compared with CFD simulations which show good predictions. A systematic investigation of the
three-phase flow in the bubble column will appear as a sequel.

Keywords: Closure relations; Euler-Euler two-fluid model; Particle image velocimetry; Shadowgraphy; Two-phase bubble column

Permalink: https://www.hzdr.de/publications/Publ-37448
Publ.-Id: 37448


Data publication: Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights Into Unforeseen Pharmacokinetics

Krutzek, F.; Donat, C.; Stadlbauer, S.

Bei diesem Datensatz handelt es sich um die chemische Charakterisierung der Verbindungen, die in-vitro- und in-vivo-Daten.

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Permalink: https://www.hzdr.de/publications/Publ-37447
Publ.-Id: 37447


Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights Into Unforeseen Pharmacokinetics

Krutzek, F.; Donat, C.; Stadlbauer, S.

Immune checkpoint inhibitor therapy targeting the PD-1/PD-L1 axis in cancer patients holds promise as an oncological treatment. However, the number of non-responders remains high. Consequently, clinicians need a diagnostic tool to predict treatment outcomes. PET imaging can play an important role in supporting therapy decisions by offering whole-body scan while quantitatively assessing PD-L1 expression. In multi-step organic synthesis, four PD-L1 radiolig-ands containing a linker-chelator system for radiometallation, along with three hydrophilizing units – one sulfonic acid and two phosphonic acids – were synthesized. After labeling with 64Cu, log D7.4 values of below –3.03 were determined and proteolytic stability studies were conducted confirming stabilities over 94% after 48 hours. Binding affinities studies were conducted using two different binding assays revealing high affinities up 13 nM. µPET/CT imaging was performed in tumor-bearing mice to investigate PD-L1 specific tumor uptake and the pharmacokinetic profile. The µPET images revealed an unexpected in vivo behavior, including low tumor uptake in PD-L1 positive tumors, high liver uptake, and accumulation in bone/bone marrow/joints. These effects were attributed to Ca2+-affinity and/or binding to macrophages. Despite phosphonic acids offering a high degree of water-solubility, their incorporation must be carefully considered to avoid ex-acerbating the radioligands’ pharmacokinetic behaviors.

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Permalink: https://www.hzdr.de/publications/Publ-37446
Publ.-Id: 37446


Reduction of the electron beam divergence of laser wakefield-accelerators by integrated plamsa lens

Chang, Y.-Y.; Couperus Cabadağ, J. P.; Debus, A.; Ghaith, A.; La Berge, M.; Pausch, R.; Schöbel, S.; Ufer, P.; Schramm, U.; Irman, A.

We report on electron beam collimation using a passive plasma lens, integrated directly and conveniently into a laser wakefield accelerator stage operating in the high charge regime. The lens is created by reshaping the gas density profile of a super-sonic jet at the beam's exit side through an obstacle mounted above the jet. It reduces the beam's divergence by a factor of two to below 1 mrad (root-mean-square), while preserving the total charge of 170 pC and maintaining the energy spread. The resulting spectral-charge density, here defined as the charge per energy bandwidth and emission angle, of up to 7 pC/(MeV·mrad) played a key role in the recent experimental demonstration of free-electron lasing. The presented simple and robust gas shaping technique holds the potential to generate specific density profiles, essential for the application of adiabatic focusing or staging of accelerators.

Keywords: LWFA; Plasma Lens; PIConGPU

Permalink: https://www.hzdr.de/publications/Publ-37445
Publ.-Id: 37445


Bound state breaking and the importance of thermal exchange-correlation effects in warm dense hydrogen

Moldabekov, Z.; Schwalbe, S.; Böhme, M.; Vorberger, J.; Shao, X.; Pavanello, M.; Graziani, F.; Dornheim, T.

Hydrogen at extreme temperatures and pressures is ubiquitous throughout our universe and naturally occurs in a variety of astrophysical objects. In addition, it is of key relevance for cutting-edge technological applications, with inertial confinement fusion research being a prime example. In the present work, we present exact \emph{ab initio} path integral Monte Carlo (PIMC) results for the electronic density of warm dense hydrogen along a line of constant degeneracy across a broad range of densities. Using the well-known concept of reduced density gradients, we develop a new framework to identify the breaking of bound states due to pressure ionization in bulk hydrogen. Moreover, we use our PIMC results as a reference to rigorously assess the accuracy of a variety of exchange--correlation (XC) functionals in density functional theory calculations for different density regions. Here a key finding is the importance of thermal XC effects for the accurate description of density gradients in high-energy density systems. Our exact PIMC test set is freely available online and can be used to guide the development of new methodologies for the simulation of warm dense matter and beyond.

Permalink: https://www.hzdr.de/publications/Publ-37444
Publ.-Id: 37444


Novel Liquid Distributor Concept for Rotating Packed Beds

Pyka, T.; Bieberle, A.; Loll, R.; Held, C.; Schubert, M.; Schembecker, G.

Although it is known that a loss in separation performance is caused by liquid maldistribution, there is only marginal knowledge about liquid distribution in rotating packed beds (RPBs). As a result, the exact influence of liquid distribution on separation performance in RPBs is not fully understood. Therefore, this study focuses on the influence of different liquid distributors on the liquid distribution of a rotating metal foam packing inside RPBs. Liquid hold-ups were measured non-invasively using gamma-ray computed tomography (CT), and water/air was the system under investigation, operated at atmospheric pressure, temperature of 20°C, liquid flow rate of 60 l h^-1, F-factor of 2.3 Pa^0.5 and at rotational speeds up to 900 rpm. For the first time, the liquid distribution in axial direction of a rotating metal foam of an RPB could be accessed, which allowed the identification and quantification of occurring wall flows. Furthermore, the path of the liquid phase through the entire opaque packing could be visualized for different operating conditions by synchronizing the CT scans with the rotational speed of the rotor. The use of a single-point full-jet nozzle was more prone to cause wall flow than the use of a rotating baffle distributor with 36 baffles. For comparison, circumferential liquid maldistribution was also observed using a rotating baffle distributor with 12 baffles.

Keywords: rotating packed bed; rotating baffle distributer; gamma-ray computed tomography

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-37443
Publ.-Id: 37443


SPEChpc 2021 Benchmark Suites for Modern HPC Systems

Li, J.; Bobyr, A.; Boehm, S.; Brantley, W.; Brunst, H.; Cavelan, A.; Chandrasekaran, S.; Cheng, J.; Ciorba, F. M.; Colgrove, M.; Curtis, T.; Daley, C.; Ferrato, M.; Gimenes De Souza, M.; Hagerty, N.; Henschel, R.; Juckeland, G.; Kelling, J.; Li, K.; Lieberman, R.; McMahon, K.; Melnichenko, E.; Ayoub Neggaz, M.; Ono, H.; Ponder, C.; Raddatz, D.; Schueller, S.; Searles, R.; Vasilev, F.; Melesse Vergara, V.; Wang, B.; Wesarg, B.; Wienke, S.; Zavala, M.

The SPEChpc™ 2021 suites are application-based benchmarks de-
signed to measure performance of modern HPC systems. The bench-
marks support MPI, MPI+OpenMP, MPI+OpenMP target offload,
MPI+OpenACC and are portable across all major HPC platforms.

Keywords: HPC; Benchmark; Performance Evaluation; MPI; OpenMP; OpenACC

Permalink: https://www.hzdr.de/publications/Publ-37442
Publ.-Id: 37442


Responsive Magnetic Nanocomposites for Intelligent Shape-Morphing Microrobots

Liu, Y.; Lin, G.; Medina-Sánchez, M.; Guix, M.; Makarov, D.; Jin, D.

With the development of advanced biomedical theragnosis and bioengineering tools, smart and soft responsive microstructures and nanostructures have emerged. These structures can transform their body shape on demand and convert external power into mechanical actions. Here, we survey the key advances in the design of responsive polymer−particle nanocomposites that led to the development of smart shapemorphing microscale robotic devices. We overview the technological roadmap of the field and highlight the emerging opportunities in programming magnetically responsive nanomaterials in polymeric matrixes, as magnetic materials offer a rich spectrum of properties that can be encoded with various magnetization information. The use
of magnetic fields as a tether-free control can easily penetrate biological tissues. With the advances in nanotechnology and manufacturing techniques, microrobotic devices can be realized with the desired magnetic reconfigurability. We emphasize that future fabrication techniques will be the key to bridging the gaps between integrating sophisticated functionalities of
nanoscale materials and reducing the complexity and footprints of microscale intelligent robots.

Keywords: Magnetic nanocomposites; shape-morphing; Microrobots; Magnetic reconfigurability; Stimuli-responsive materials; Scalable manufacturing approaches; Biomedical and bioengineering applications

Permalink: https://www.hzdr.de/publications/Publ-37441
Publ.-Id: 37441


Optical properties of selenium-hyperdoped Si layers: Effects of laser and thermal treatment

Komarov, F. F.; Vlasukova, L. A.; Milchanin, O. V.; Parkhomenko, I. N.; Berencen, Y.; Alzhanova, A. E.; Wang, T.; Zuk, J.

Silicon layers with a selenium impurity concentration up to 1021 cm–3, which exceeds the equilibrium solubility limit of this
impurity in silicon by four orders of magnitude, were obtained by high-dose ion implantation followed by pulsed laser
annealing at pulse energy densities from 0.5 to 2.5 J/cm2. Rutherford backscattering of He+ ions showed that up to 70% of
the implemented impurity atoms were localized at silicon crystal-lattice sites after laser annealing. The Se-hyperdoped Si
layers were characterized by increased (up to 45–55%) absorption in the spectral range 1100–2400 nm. Thermal treatment
(550°C for 30 min followed by 850°C for 5 min) did not increase the IR absorption as compared with the initial Si, which was
explained by Se losses resulting from diffusional redistribution. Recrystallization of Si layers amorphized by Se ions and
redistribution of the dopant with equilibrium thermal treatment were theoretically evaluated.

Keywords: IR-light absorption; laser annealing; selenium implantation; silicon; thermal treatment

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  • Secondary publication expected from 17.05.2024

Permalink: https://www.hzdr.de/publications/Publ-37440
Publ.-Id: 37440


Novel Mixed-Dimensional hBN-Passivated Silicon Nanowire Reconfigurable Field Effect Transistors: Fabrication and Characterization

Ghosh, S.; Bilal Khan, M.; Chava, P.; Watanabe, K.; Taniguchi, T.; Prucnal, S.; Hübner, R.; Mikolajick, T.; Erbe, A.; Georgiev, Y.

This work demonstrates the novel concept of a mixed-dimensional reconfigurable field effect transistor (RFET) by combining a one-dimensional (1D) channel material such as a silicon (Si) nanowire with a two-dimensional (2D) material as a gate dielectric. An RFET is an innovative device that can be dynamically programmed to perform as either an n- or p-FET by applying appropriate gate potentials. In this work, an insulating 2D material, hexagonal boron nitride (hBN), is introduced as a gate dielectric and encapsulation layer around the nanowire in place of a thermally grown or atomic-layer-deposited oxide. hBN flake was mechanically exfoliated and transferred onto a silicon nanowire-based RFET device using the dry viscoelastic stamping transfer technique. The thickness of the hBN flakes was investigated by atomic force microscopy and transmission electron microscopy. The ambipolar transfer characteristics of the Si-hBN RFETs with different gating architectures showed a significant improvement in the device’s electrical parameters due to the encapsulation and passivation of the nanowire with the hBN flake. Both n- and p-type characteristics measured through the top gate exhibited a reduction of hysteresis by 10–20 V and an increase in the on–off ratio (ION/IOFF) by 1 order of magnitude (up to 108) compared to the values measured for unpassivated nanowire. Specifically, the hBN encapsulation provided improved electrostatic top gate coupling, which is reflected in the enhanced subthreshold swing values of the devices. For a single nanowire, an improvement up to 0.97 and 0.5 V/dec in the n- and p-conduction, respectively, is observed. Due to their dynamic switching and polarity control, RFETs boast great potential in reducing the device count, lowering power consumption, and playing a crucial role in advanced electronic circuitry. The concept of mixed-dimensional RFET could further strengthen its functionality, opening up new pathways for future electronics.

Keywords: mixed-dimensional reconfigurable FET; ambipolar; nickel silicide; flash lamp annealing; hBN encapsulation; subthreshold swing

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  • Open Access Logo ACS Applied Materials and Interfaces 15(2023)34, 40709-40718
    Online First (2023) DOI: 10.1021/acsami.3c04808

Permalink: https://www.hzdr.de/publications/Publ-37438
Publ.-Id: 37438


On the optimal presence strategies for workplace during pandemics: A COVID-19 inspired probabilistic model

Davoodi Monfared, M.; Senapati, A.; Mertel, A.; Schlechte-Welnicz, W.; Calabrese, J.

During pandemics like COVID-19, both the quality and quantity of services offered by businesses and organizations have been severely impacted. They often have applied a hybrid home office setup to overcome this problem, although in some situations, working from home lowers employee productivity. So, increasing the rate of presence in the office is frequently desired from the manager's standpoint. On the other hand, as the virus spreads through interpersonal contact, the risk of infection increases when workplace occupancy rises.
Motivated by this trade-off, in this paper, we model this problem as a bi-objective optimization problem and propose a practical approach to find the trade-off solutions. We present a new probabilistic framework to compute the expected number of infected employees for a setting of the influential parameters, such as the incidence level in the neighborhood of the company, transmission rate of the virus, number of employees, rate of vaccination, testing frequency, and rate of contacts among the employees. The results show a wide range of trade-offs between the expected number of infections and productivity, for example, from 1 to 6 weekly infections in 100 employees and a productivity level of 65\% to 85\%. This depends on the configuration of influential parameters and the occupancy level.
We implement the model and the algorithm and perform several experiments with different settings of the parameters. Moreover, we developed an online application based on the result in this paper which can be used as a recommender for the optimal rate of occupancy in companies/workplaces.

Keywords: COVID-19; Optimization; Productivity

Permalink: https://www.hzdr.de/publications/Publ-37437
Publ.-Id: 37437


Impact of the Fuel Rod Modeling on the X2 Control Rod Cluster Ejection Results

Bilodid, Y.; Zilly, M.; Fischer, M.; Henry, R.; Kliem, S.; Alexander, A.; Kilger, R.

The new benchmark for VVER-1000 control rod ejection transient was published recently. One of the assumptions proposed in the benchmark is given fixed values for fuel-cladding gas gap thermal conductivity and thermo-physical properties of fuel and cladding materials. In this paper, authors investigate an impact of this assumption on simulation results.

Keywords: X2; VVER-1000; Control Rod Ejection; fuel-cladding gas gap thermal conductivity; thermo-physical properties of fuel and cladding

  • Contribution to proceedings
    International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023), 13.-17.08.2023, Niagara Falls, Canada
    Proceedings of M&C 2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, 978-1-926773-50-6
  • Lecture (Conference)
    International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2023), 13.-17.08.2023, Niagara Falls, Canada

Permalink: https://www.hzdr.de/publications/Publ-37436
Publ.-Id: 37436


Sulfide S-Zn-Cd isotopes and origin of the Liangyan Zn-Pb deposit in the Sichuan-Yunnan-Guizhou metallogenic province, SW China

Wu, T.; He, Y.-F.; He, Z.-W.; Huang, Z.-L.; Ye, L.; Wei, C.; Fan, H.-F.; Hu, Y.-S.; Du, L.; Gun, M.-S.

Unraveling the metal sources of Zn-Pb deposits is vital to understand the genetic types and ore-forming processes. The Sichuan-Yunnan-Guizhou metallogenic province (SYGMP) hosts abundant Zn-Pb deposits that are variably rich in critical metals such as Ga, Ge, Cd and Tl. However, sources of these critical metals and main metal Zn are still unclear. The Liangyan Cd-rich Zn-Pb deposit as a representative in the SYGMP is hosted in a carbonate sedimentary sequence and controlled by the regional Yadu-Wogong anticline and Yadu-Mangdong thrust fault. SZn-Cd isotopes of sulfide minerals from this deposit are obtained in order to understand the sources of metals and origin of the deposit. Sulfur isotopic results of pyrite and sphalerite reveal that sulfur was produced by thermochemical sulfate reduction (TSR) of sulfates from the Carboniferous dolostone and mudstone and the Ediacaran-Devonian carbonates. Sphalerite grains have δ66ZnJMC values that are negatively correlated with the δ114Cd spex values, implying different sources for both Zn and Cd. The variation trend of δ66ZnJMC and Cd/Zn
suggests that Zn was mainly sourced from the Neoproterozoic basement with minor from the Carboniferous wallrocks. Besides, sphalerite grains show a negative correlation between δ114Cdspex and Zn/Cd, and these values fall in the field close to the Carboniferous carbonates, but away from the Permian Emeishan basalts, indicating that Cd was derived mainly from the Carboniferous wallrocks with minor from the Emeishan basalts. Together with geological evidence, the multi-isotope data suggest that the Liangyan deposit belongs to a thrust-controlled MVT Zn-Pb deposit.

Keywords: Zn and Cd isotopes; Metal source; Ore genesis; Mixing of isotopically distinct sources; MVT deposit

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  • Secondary publication expected from 27.07.2024

Permalink: https://www.hzdr.de/publications/Publ-37434
Publ.-Id: 37434


ESFR-SIMPLE: new HORIZON-EURATOM project on SFR safety

Sciora, P.; Mikityuk, K.; Bonzom, P. V.; Fridman, E.; Bubelis, E.; Rineiski, A.; Hamy, J. M.; Gaus-Liu, X.; Gerbeth, Gunter; Eckert, Sven; Dupont, V.; Shwageraus, E.

Following several previous European projects (EFR, CP-ESFR and ESFR-SMART), a new project ESFR-SIMPLE has been proposed in response to the HORIZON-EURATOM call on “Safety of advanced and innovative nuclear designs and fuels”. The new project aims at challenging the Generation IV ESFR (European Sodium Fast Reactor) designed in the ESFR-SMART project, to improve its safety and economics thanks to innovative technologies. The project high-level objectives and actions are: 1) Challenge the ESFR design to simplify the reactor, through reducing its size, which could allow taking advantage of SMRs (Small Modular Reactors) in terms of transportability, modularization, standardization, flexible operation and machine learning, all ultimately leading to improved economics. 2) Propose, develop and assess advanced methods of monitoring and processing operational data using Artificial Intelligence, e.g., to optimize fault detection in the steam generators at an early stage. 3) Produce new experimental data in order to support calibration and validation of the computational tools such as properties measurements of irradiated and non-irradiated MOX fuel including fuel with optimized micro-structures, and to assist in qualification of innovative components, such as expansion bellows, thermo-electric pumps and accident tolerant core-catcher. 4) Assess alternative technologies, such as the use of metallic fuel and compact secondary system design, for the large-size ESFR to improve the economics and safety. 5) Ensure that the knowledge generated in the project will be shared not only among the project partner institutions, but also among as wide a range of stakeholders as possible in Europe and internationally. The project relies on a consortium of 16 partners and will benefit from different skills and experiments available in Europe and in the US. It started in October 2022 and will end in September 2026. In addition to the technical details, this paper also briefly outlines the organization of the project.

  • Contribution to proceedings
    International Congress on Advances in Nuclear Power Plants (ICAPP 2023), 23.-27.04.2023, Gyeongju, South Korea

Permalink: https://www.hzdr.de/publications/Publ-37433
Publ.-Id: 37433


First Direct Measurement Constraining the 34Ar(α,p)37K Reaction Cross Section for Mixed Hydrogen and Helium Burning in Accreting Neutron Stars

Browne, J.; Chipps, K. A.; Schmidt, K.; Schatz, H.; Ahn, S.; Pain, S. D.; Montes, F.; Ong, W.-J.; Greife, U.; Allen, J.; Bardayan, D. W.; Blackmon, J. C.; Blankstein, D.; Cha, S.; Chae, K. Y.; Febbraro, M.; Hall, M. R.; Jones, K. L.; Kontos, A.; Meisel, Z.; O’Malley, P. D.; Schmitt, K. T.; Smith, K.; Smith, M. S.; Thompson, P.; Toomey, R.; Vostinar, M.; Walter, D.

The rate of the final step in the astrophysical αp process, the 34Ar(α,p)37K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. We present the first direct measurement constraining the 34Ar(α,p)37K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the 34Ar,Cl(α,p)37K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The 34Ar(α,2p)36Ar cross section, which can be exclusively attributed to the 34Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.

Keywords: experimental nuclear astrophysics; JENSA gas jet target; x-ray burst; accreting neutron star; nuclear reaction study; TALYS; light curve; nuclear ashes

Permalink: https://www.hzdr.de/publications/Publ-37432
Publ.-Id: 37432


Providing AI expertise as an infrastructure in academia

Piraud, M.; Camero, A.; Götz, M.; Kesselheim, S.; Steinbach, P.; Weigel, T.

Artificial intelligence (AI) is proliferating and developing faster than any domain scientist can adapt. To support the scientific enterprise in the Helmholtz association, a network of AI specialists has been set up to disseminate AI expertise as an infrastructure among domain scientists. As this effort exposes an evolutionary step in science organization in Germany, this article aspires to describe our setup, goals, and motivations. We comment on past experiences, current developments, and future ideas as we bring our expertise as an infrastructure closer to scientists across our organization. We hope that this offers a brief yet insightful view of our activities as well as inspiration for other science organizations.

Keywords: machine learning; artificial intelligence; consulting; consultants; expertise; infrastructure; service; science

Permalink: https://www.hzdr.de/publications/Publ-37431
Publ.-Id: 37431


Increased cerebral blood flow is associated with higher baseline amyloid burden in a cognitively unimpaired population

Padrela, B. E.; Lorenzini, L.; Collij, L. E.; Tomassen, J.; Bader, I.; Shekari, M.; van Berckel, B. N. M.; Visser, P. J.; Barkhof, F.; Petr, J.; Mutsaerts, H.-J.

Background:

Decreased cerebral blood flow (CBF) and deterioration of blood-brain barrier (BBB) are suggested to be precursor conditions of cognitive impairment. Using a novel multi-echo-time arterial spin labelling (ASL) protocol, we examined the time of exchange (Tex) of water across the BBB as a measurement of BBB permeability. We further examined the association of cardiovascular risk factors with Tex in an ongoing cohort study.
Method:
Data (n=29, mean age: 55.9±6.1years, 69% women) were drawn from Neurological biomarkers of Blood, MRI and Cognition (NEURO-BMC) study performed at National University of Singapore. NEURO-BMC is an ongoing prospective cohort study (age: 45-65 years) on brain changes in a subclinical phase of cognitive impairment. A multi-echo, Hadamard-encoded multi-post-labelling-delay pseudo-continuous ASL (PCASL) protocol was used on a 3T scanner. ExploreASL was used with a modified version of FSL FABBER(4) to quantify cerebral blood flow (CBF), arterial transit time (ATT), and Tex. ASL-extracted parameters were compared with cardiovascular risk parameters such as blood pressure (BP), BMI and smoking status.
Result:
High systolic and diastolic BP were associated with significantly reduced Tex (Fig 1). Additionally, higher systolic and diastolic BP showed a trend of increased ATT and reduced CBF, though the associations were not statistically significant (Table 1). High BMI had a significant association with increased ATT and reduced CBF. However, no trend was observed between BMI and Tex. Participants who ever smoked were observed to have a reduced Tex and CBF and increased ATT, but statistical significance was only found for CBF (Fig 1).
Conclusion:
In this pilot study, we showed that BBB-ASL-derived parameters - ATT, CBF, and Tex - were associated with BP, BMI, and smoking status. While the sample size for this preliminary analysis was too small to make a definitive conclusion as not all associations were statistically significant, all studied cardiovascular risk factors showed their potential in increasing the risk of BBB deterioration. Further investigation with a larger sample size and other health risk factors to assess these observations is warranted.

  • Open Access Logo Contribution to proceedings
    Alzheimer's Association International Conference, 16.07.2023, Amsterdam, Amsterdam
    DOI: 10.1002/alz.065779
  • Poster
    Alzheimer's Association International Conference, 16.07.2023, Amsterdam, The Netherlands

Permalink: https://www.hzdr.de/publications/Publ-37430
Publ.-Id: 37430


Coherent x-ray diffraction of a semiregular Pt nanodot array

Keller, T. F.; Shayduk, R.; Kim, C.; Mukharamova, N.; Dangwal Pandey, A.; Abuin, M.; Vonk, V.; Fernandez-Cuesta, I.; Barthelmess, M.; Frömter, R.; Zozulya, A.; Erbe, A.; Stierle, A.

Structural insight into nano-objects down to the atomic scale is one of the most important prerequisites in understanding functional materials properties and will ultimately permit to relate the size and shape of nanoparticles to their catalytic activity. We elucidate the potential of extracting structural information about a small ensemble of nanoparticles semi-regularly arranged on a periodic array from coherent X-ray Bragg diffraction. The observed superstructure in the Pt(111) Bragg peak obviously originates from the mutual interference of the Bragg scattered wave field from individual nanoparticles in the nano-array. Despite the absence of a symmetry center in the Bragg peak of the nano-array, we identify the most prominent in-plane spatial frequencies of the latter by applying a Patterson map analysis to the Bragg peak superstructure. Integration along the out-of-plane reciprocal space direction over the relevant in-plane regions of interest results in Laue oscillations that arise from nanoparticle sets of similar heights in real space. A one-to-one comparison with real-space microscopic information obtained from SEM and AFM suggests potential nanoparticle subsets as origin for the X-ray intensity in these regions of interest by the good agreement in their height and direction-dependent in-plane interparticle distances, as also further supported by simulations. Nanoparticle arrays with well-defined tunable sizes and lateral distances may serve in the future to track structural changes of smallest catalysis-relevant nanoparticles during operando heterogeneous catalysis experiments in the 10 nm size regime.

Keywords: Coherent X-ray Bragg diffraction; platinum nanodot-array; strontium titanate; electron beam lithography

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Permalink: https://www.hzdr.de/publications/Publ-37429
Publ.-Id: 37429


On the application of advanced modeling tools to the SLB analysis in NuScale. Part I: TRACE/PARCS, TRACE/PANTHER and ATHLET/DYN3D

Sanchez-Torrijos, J.; Redondo-Valero, E.; Queral, C.; Cabellos, O.; Meca, R.; Petrásek, O.; Diaz Pescador, E.; Kliem, S.; Palmans, N.; Sanchez-Espinoza, V.

Nowadays, there is a growing interest in the Small Modular Reactors (SMRs) technology due to their enhanced safety level and reasonably reduced manufacturing and construction costs. However, modeling tools should be able to deal with the special features inherent to their design such as the modeling of the helical Steam Generators. In this work, a Steam Line Break sequence in the NuScale reactor has been simulated using several modeling tools based on a full-plant thermohydraulic model for a system code coupled with a 3D nodal diffusion code for describing the core physics. To do so, four different models have been developed by four different organization for the coupled codes TRACE/PARCS, TRACE/PANTHER and ATHLET/DYN3D. In that sense, a very reasonable agreement is reached among the steady-state parameters of the plant computed by each participant and the ones presented in the Design Standard Application Report of NuScale. Regarding the simulation of the SLB transient, it should be noted that after 100 seconds of simulation, it can be said that remarkable differences are to be seen among the results for the time behavior of the core temperatures. Those differences are attributable to differences in the heat transfer within the helically coiled steam generators. Important differences have been also found in the decay heat removal system performance, so it is concluded that further investigation and model development is needed for the phenomena occurring in the steam generators and the decay heat removal heat system.

Keywords: NuScale; McSAFER; Steam Line Break; Coupled codes

  • Contribution to proceedings
    2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 13.-17.08.2023, Niagara Falls, Canada
    Proceedings of the 2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 978-1-926773-50-6
  • Lecture (Conference)
    2023 International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering, M&C 2023, 13.-17.08.2023, Niagara Falls, Canada

Permalink: https://www.hzdr.de/publications/Publ-37428
Publ.-Id: 37428


Review and recommendations on deformable image registration uncertainties for radiotherapy applications

Nenoff, L.; Amstutz, F.; Murr, M.; Archibald-Heeren, B.; Fusella, M.; Hussein, M.; Lechner, W.; Zhang, Y.; Sharp, G.; Vasquez Osorio, E.

Deformable image registration (DIR) is a versatile tool used in many applications in radiotherapy (RT). DIR algorithms have been implemented in many commercial treatment planning systems providing accessible and easy-to-use solutions. However, the geometric uncertainty of DIR can be large and difficult to quantify, resulting in barriers to clinical practice. Currently, there is no agreement in the RT community on how to quantify these uncertainties and determine thresholds that distinguish a good DIR result from a poor one. This review summarises the current literature on sources of DIR uncertainties and their impact on RT applications. Recommendations are provided on how to handle these uncertainties for patient-specific use, commissioning, and research. Recommendations are also provided for developers and vendors to help users to understand DIR uncertainties and make the application of DIR in RT safer and more reliable.

Keywords: deformable image registration; DIR uncertainty; radiotherapy; structure propagation; dose accumulation; mapping; image deformation

Permalink: https://www.hzdr.de/publications/Publ-37427
Publ.-Id: 37427


CEFR control rod drop transient simulation using RAST-F code system

Tran, T. Q.; Huo, X.; Fridman, E.; Lee, D.

This study aimed to verify and validate the transient simulation capability of the hybrid code system RAST-F for fast reactor analysis. For this purpose, control rod (CR) drop experiments of eight CRs and six control groups in the China Experimental Fast Reactor (CEFR) start-up tests were utilized to simulate the CR drop transient. The RAST-F numerical solution, including the neutron population, time-dependent reactivity, and CR worth, was compared against the measurement values obtained from two out-of-core detectors. Moreover, the time-dependent reactivity and CR worth from RAST-F were verified against the results obtained by the Monte Carlo code Serpent using continuous energy nuclear data. A code-to-code comparison between Serpent and RAST-F showed good agreement in terms of time-dependent reactivity and CR worth. The discrepancy was less than 160 pcm for reactivity and less than 110 pcm for CR worth. RAST-F solution was almost identical to the measurement data in terms of neutron population and reactivity. All the calculated CR worth results agreed with experimental results within two standard deviations of experimental uncertainty for all CRs and control groups. This work demonstrates that the RAST-F code system can be a potential tool for analyzing time-dependent phenomena in fast reactors.

Keywords: CEFR; RAST-F; Transient; Nodal diffusion code; Serpent

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Permalink: https://www.hzdr.de/publications/Publ-37426
Publ.-Id: 37426


Prompt gamma-ray spectroscopy in conjunction with the Monte Carlo Library Least Squares approach: applications to range verification in proton therapy

Skjerdal, K.; Kögler, T.; Lionheart, W.; Smeland Ytre-Hauge, K.; Meric, I.

Prompt Gamma-ray Spectroscopy (PGS) in conjunction with the Monte Carlo Library Least Squares (MCLLS) approach was investigated for the purposes of range monitoring in proton therapy through Monte Carlo simulations. Prompt gamma-rays are produced during treatment and can be correlated to the range of the proton beam in the tissue. In contrast to established approaches, MCLLS does not rely on the identification of specific photopeaks. Instead it treats each individual constituent as a library spectrum and calculates coefficients for each spectrum, and therefore takes both the photopeaks and the Compton continuum into account. It can thus be applied to organic scintillators traditionally not used for energy spectroscopy due to their low Z number and density. Preliminary results demonstrate that the proposed approach returns a strong linear correlation between the range of the primary proton beam and the calculated library coefficients, depending on the composition of libraries. This can be exploited for range monitoring.

Keywords: proton therapy; spectroscopy; Monte Carlo simulations; range verification

Related publications

  • Open Access Logo Contribution to proceedings
    ANIMMA 2023 – Advancements in Nuclear Instrumentation Measurement Methods and their Applications, 12.-16.06.2023, Real Collegio, Italy
    ANIMMA 2023 Conference Proceedings: EPJ Web of Conferences
    DOI: 10.1051/epjconf/202328809003

Permalink: https://www.hzdr.de/publications/Publ-37424
Publ.-Id: 37424


Morphology and orientation change of layer-by-layer deposited one- and two-dimensional coordination polymer nanocrystals containing rhodium paddle-wheel units

Steinbach, D.; Neubert, R.; Gersdorf, S.; Schimpf, C.; Erb, D.; Rafaja, D.; Plamper, F. A.; Mertens, F.

Surface-directed and preferentially oriented assemblies of nanomaterials can enable enhanced applications in e.g. catalysis or sensing. Coordination polymers, which can be even conducting, could be suitable materials for this purpose because of their facile surface anchoring. Hence, we coassembled rhodium paddle-wheel building blocks with bi- or trifunctional linkers in dip coatings that were produced by layer-by-layer approach on silicon wafers functionalized by thin nanocrystalline gold surfaces. These gold surfaces were decorated with a self-assembled monolayer (SAM) for coordination and binding to the Rh-units. As linkers, pyrazine, triazine and melamine were used, leading to rectangularly-shaped, hexagonally-shaped or needle-like crystals, respectively. The coordination polymers were produced by repeated dipping into the linker and paddle-wheel solution, each followed by a cleaning step. The crystals growth was followed by atomic force microscopy (AFM) grazing incidence small-angle X-ray scattering (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS). AFM and GISAXS revealed the shape and size of the crystals. GIWAXS disclosed their preferred orientation. It turned out that the automated dipping procedure does not lead to a strong alignment of crystallites along the dipping direction for the pyrazine-based deposits. However, these crystals are preferentially oriented with respect to the substrate normal direction. The crystallographic direction and the degree of the alignment depend on the number of deposition cycles. In the early phases of the deposition process, predominantly “lying” crystals were detected. With increasing number of the deposition cycles, the fraction of “standing” crystals became dominant. These crystals are oriented with their {010} directions perpendicular to the surface of the substrate. Still, “lying” and some tilted crystals were detected additionally. The study gives a deeper structural understanding of crystallite assemblies and suggests an evolvement of more anisotropic orientations of the crystallites with increasing deposition cycles (leading to the prevalence of crystals having the preferred {010} orientation with respect to the surface normal direction).

Permalink: https://www.hzdr.de/publications/Publ-37423
Publ.-Id: 37423


Overcoming stereological Bias: A workflow for 3D mineral characterization of particles using X-ray micro-computed tomography

Siddique, A.; Da Assuncao Godinho, J. R.; Sittner, J.; Pereira, L.

Mineral separation processes operate on properties of individual particle, which can currently be quantified with 2D
characterization techniques, namely 2D automated mineralogy. While 2D automated mineralogy data have driven significant
developments in particle-based separation models, this data inherently correspond to 2D slices of 3D objects, which leads to
stereological bias in the quantification of geometric particle properties. X-ray micro-computed tomography (μCT) is a 3D
imaging technique that can quantify particle geometry. However, μCT only collects limited information regarding material
composition, making mineral identification quantification a challenge. To overcome this challenge, we present a workflow
that utilizes individual particle histograms and corrects image artefacts caused by μCT measurements, such as partial
volume effect. We demonstrate the application of the workflow to perform 3D mineral characterisation of a sulfidic gold ore,
where mineral phases that are commonly mistaken with μCT could be distinguished: pyrite and chalcopyrite, gold, and
galena. Results were verified by comparison with inductively coupled plasma mass spectrometry and 2D automated
mineralogy. As a result, the workflow provides the user with a detailed 3D particle dataset containing the modal mineralogy
and surface compositions, size, and geometrical properties of each particle in a sample – essential data for modelling
mineral separation processes.

Keywords: 2D automated mineralogy; 3D mineral characterization; Individual particle histograms; Mineral separation processes; X-ray micro-computed tomography

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  • Secondary publication expected from 28.04.2024

Permalink: https://www.hzdr.de/publications/Publ-37422
Publ.-Id: 37422


Highly Enhanced Defects Driven Room Temperature Ferromagnetism in Mixed-phase MoS2-MoOx Films

Singh, P.; Ghosh, S.; Jain, M.; Singh, A.; Singh, R.; Balal, M.; Roy Barman, S.; Kentsch, U.; Zhou, S.; Bhattacharya, S.; Srivastava, P.

Room temperature ferromagnetism has been reported in chemical vapor deposition-grown mixed-phase MoS2-MoOx thin films after Xe ion irradiation. Magnetic moment has significantly been enhanced after ion irradiation. Deterioration in crystallinity after ion irradiation has been shown by X-ray diffraction and Raman spectroscopy measurements. The variation in the surface morphology and/or formation of edge states can be observed by secondary electron microscopy images. The reduction in the oxygen vacancy concentration, probed by analysis of the O 1s core level X-ray photoelectron spectrum for the film with the maximum magnetic moment, rules out the possibility of ferromagnetism due to oxygen vacancy. Enhancement in the Mo content in 5+ and 6+ oxidation states due to the occupation of sulfur vacancy sites by oxygen after ion irradiation, calculated from X-ray photoelectron spectroscopy core level of Mo 3d and S 2p and valence band spectra, has been observed. Density functional theory (DFT) calculations also show the one-to-one correspondence of saturation magnetic moment with Mo6+ content. So, the enhancement in the ferromagnetism in mixed-phase of MoS2-MoOx thin films is due to the increase of Mo in 6+ oxidation state and exchange interaction between the different oxidation states of Mo via p-orbital of anion and formation of edged states.

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Permalink: https://www.hzdr.de/publications/Publ-37421
Publ.-Id: 37421


Ion irradiation of monolayer graphene-Nd:YAG hybrid waveguides: fabrication and laser

Ma, L.; Li, S.; Wang, H.; Zhou, S.; Yang, T.

Hybrid waveguides consisting of two-dimensional layered materials pad on the surface of optical waveguides suffer from a nonuniform and loose contact between the two-dimensional material and the waveguide, which can reduce the efficiency of the pulsed laser. Here, we present high-performance passively Q-switched pulsed lasers in three distinct structures of monolayer graphene-Nd:YAG hybrid waveguides irradiated by energetic ions. The ion irradiation enables the monolayer graphene a tight contact and strong coupling with the waveguide. As a result, Q-switched pulsed lasers with narrow pulse width and high repetition rate are obtained in three designed hybrid waveguides. The narrowest pulse width is 43.6 ns, provided by the ion-irradiated Y-branch hybrid waveguide. This study paves the way toward developing on-chip laser sources based on hybrid waveguides by using ion irradiation.

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Permalink: https://www.hzdr.de/publications/Publ-37420
Publ.-Id: 37420


Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions

Long, F.; Ghorbani Asl, M.; Mosina, K.; Li, Y.; Lin, K.; Ganss, F.; Hübner, R.; Sofer, Z.; Dirnberger, F.; Kamra, A.; Krasheninnikov, A.; Prucnal, S.; Helm, M.; Zhou, S.

Layered magnetic materials are becoming a major platform for future spin-based applications. Particularly the air-stable van der Waals compound CrSBr is attracting considerable interest due to its prominent magneto-transport and magneto-optical properties. In this work, we observe a transition from antiferromagnetic to ferromagnetic behavior in CrSBr crystals exposed to high-energy, non-magnetic ions. Already at moderate fluences, ion irradiation induces a remanent magnetization with hysteresis adapting to the easy-axis anisotropy of the pristine magnetic order up to a critical temperature of 110 K. Structure analysis of the irradiated crystals in conjunction with density functional theory calculations suggest that the displacement of constituent atoms due to collisions with ions and the formation of interstitials favors ferromagnetic order between the layers.

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Permalink: https://www.hzdr.de/publications/Publ-37419
Publ.-Id: 37419


[18F]RM273 – A PET probe for the imaging of the sigma2 receptor in brain cancer

Gündel, D.; Toussaint, M.; Moldovan, R.-P.; Teodoro, R.; Schepmann, D.; Wünsch, B.; Ludwig, F.-A.; Fischer, S.; Brust, P.; Deuther-Conrad, W.

The sigma2 receptor (TMEM97) expression correlates well with the Ki67 expression in tumours [1, 2] and therefore represents an attractive marker for the proliferative status. We developed the 18F-labelled radioligand [18F]RM273 for sigma2 receptor imaging in brain tumours.
[18F]RM273 (2-[4-(6-[18F]fluoro-1H-pyrrolo[2,3-b]pyridin-1-yl)butyl]-6,7-dimethoxy-1,2,3,4-tetra-hydroisoquinoline) has been obtained by automated synthesis by Cu-mediated oxidative radiofluorination of the aryl boronic acid pinacol ester precursor. Radiometabolite analysis was performed in mouse plasma samples 30 min p.i. The target specificity was investigated by in vitro autoradiographic studies with or without the sigma2 receptor antagonist ISO-1 in rat brain cryosections with a stereotactically implanted F98 glioma [3]. The biodistribution of [18F]RM273 in healthy mice (female, CD1; n = 4; 7.2 ± 1.1 MBq) and the tumour uptake into the F98 glioma (male, Fischer rats; n = 2; 21 and 25 MBq) were investigated by dynamic PET imaging for 60 min (nanoScan®PET-1T MRI, Mediso).
Polar radiometabolites of [18F]RM273 (AM 69 – 233 GBq/μmol, RCY 8%) were detectable in plasma, but not in brain extracts. We determined a 3-times higher density of binding sites in tumour compared to healthy brain in vitro [3]. PET studies revealed a TAC peak value of 1.3 at 2.25 min p.i. followed by a wash out in the brain of healthy mice [3]. In the F98 glioma brain region a two times higher uptake (SUVmean of 0.8–1.3 at 30–60 min p.i.) compared to contralateral was observable. Therefore, [18F]RM273 could potentially be used to determine the proliferative status of brain tumours.
Acknowledgements: This work was supported by the Deutsche Forschungsgemeinschaft (DFG: BR 1360/13-1).
References: [1] Shoghi et al. Plos One 2013, 8: e74188; [2] Yang et al. Molecules 2020, 25 (22): 5439 [3] Moldovan et al. Int. J. Mol. Sci. 2021, 22: 5447

Keywords: Sigma 2 recceptor; glioma; PET; [18F]RM273

  • Poster
    PET iS Wonderful, 23.-24.10.2023, Edinburgh, Scotland
  • Lecture (Conference)
    PET Is Wonderful, 23.-24.10.2023, Edinburgh, Scotland

Permalink: https://www.hzdr.de/publications/Publ-37418
Publ.-Id: 37418


Development of a Highly Specific 18F-labeled Radioligand for Imaging of Sigma-2 Receptor in Brain Tumor

Wang, T.; Wang, J.; Chen, L.; Zhang, X.; Mou, T.; An, X.; Zhang, J.; Zhang, X.; Deuther-Conrad, W.; Huang, Y.; Jia, H.

Series of novel ligands with the 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline or 5,6-dimethoxyisoindoline pharmacophore were designed and synthesized for evaluation of their structure-activity relationship to the sigma-2 (2) receptor and development as suitable PET radioligands. Compound 1 was found to possess nanomolar affinity (6.97 nM) for the 2 receptor, high subtype selectivity (58-fold) and high selectivity over 40 other receptors and transporters. Radioligand [18F]1 was prepared with radiochemical yield of 37–54%, > 99% radiochemical purity, molar activity of 107–189 GBq/μmol. Biodistribution and blocking studies in mice and micro-PET/CT imaging of [18F]1 in rats indicated excellent binding specificity of [18F]1 to the 2 receptors in vivo. Micro-PET/CT imaging of [18F]1 in the U87MG glioma xenograft model demonstrated clear tumor visualization with high tumor uptake and tumor-to-background ratio. Co-injection with CM398 (5 mol/kg) led to remarkable reduction of tumor uptake (80%, 60–70 min), indicating high specific binding of [18F]1 in U87MG glioma xenografts.

Keywords: 2 receptor; benzimidazolone derivative; brain tumor; positron emission tomography; fluorine-18

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  • Secondary publication expected from 13.09.2024

Permalink: https://www.hzdr.de/publications/Publ-37417
Publ.-Id: 37417


Acoustically induced spin resonances of silicon-vacancy centers in 4H-SiC

Vasselon, T.; Hernandez-Mınguez, A.; Hollenbach, M.; Astakhov, G.; Santos, P. V.

The long-lived and optically addressable spin states of silicon vacancies (VSi) in 4H-SiC make them promising qubits for quantum communication and sensing. These color centers can be created in both the hexagonal (V1) and in the cubic (V2) local crystallographic environments of the 4H-SiC host. While the spin of the V2 center can be efficiently manipulated by optically detected magnetic resonance at room temperature, spin control of the V1 centers above cryogenic temperatures has been elusive. Here, we show that the dynamic strain of surface acoustic waves can overcome this limitation and efficiently excite magnetic resonances of V1 centers up to room temperature. Based on the width and temperature dependence of the acoustically induced spin resonances, we attribute them to transitions between spin sublevels in the excited state. The acoustic spin control of both V1 and V2 centers in their excited states opens new ways for applications in quantum technologies based on spin-optomechanics.

Keywords: Quantum technologies; Acoustic; Spintronics; Defects; Silicon carbide

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Permalink: https://www.hzdr.de/publications/Publ-37416
Publ.-Id: 37416


Dataset on European Project ENTENTE Deliverable D4.5 "Hybrid hardening models from SANS and nanoindentation experiments

Bergner, F.; Altstadt, E.; Brandenburg, J.-E.; Chekhonin, P.; Ulbricht, A.

This dataset covers experimental data obtained for neutron-irradiated reactor pressure vessel (RPV) steels, in detail type and composition of steels, initial microstructure, initial properties, irradiation conditions, irradiation-induced microstructure changes and irradiation-induced property changes. The metadata sections of the data compilation include references to published journal articles and reports, where the data were originally published. A special feature of the data compilation is the availability of the characteristics of irradiation-induced nm-sized solute atom clusters derived from small-angle neutron scattering (SANS) experiments for each of the RPV materials and irradiation conditions considered. These characteristics, including cluster volume fraction and size, are statistically reliable and macroscopically representative. Moreover, results of Vickers hardness tests obtained using the same samples and also probing macroscopic volumes are provided. The data compilation is organized in the format of an Excel workbook called SANS-RPV. There are numerous potential applications of the data compilation such as the comparison of cluster characteristics derived from SANS and APT experiments, the correlation between cluster volume fraction and irradiation-induced hardness increase or brittle-ductile transition temperature shift, microstructure-informed predictions of the initial yield stress or irradiation-induced yield stress increase or the assessment of embrittlement trend curce (ETC) models, to mention a few. As an illustration, selected applications are saved in a separate Excel file called SANS_RPV_Analyses, which is included in the dataset. The background and usage of the data compilation as well as applications and implications are part of a study performed within the European Project ENTENTE. A copy of the project report draft (Deliverable D4.5) is included in the dataset.

Keywords: Reactor pressure vessel steels; Neutron irradiation; Microstructure; Mechanical properties; Hardening; Embrittlement; Small-angle neutron scattering

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Permalink: https://www.hzdr.de/publications/Publ-37415
Publ.-Id: 37415


Numerical Simulation of Particles in Rising Gas Bubbles

Mathew, A. T.; Maestri, R.; Lecrivain, G.

Numerical Simulation of Particles in Rising Gas Bubbles

Keywords: Taylor bubble; Simulation; Computational Fluid Dynamics

  • Study thesis
    TUBAF, 2023
    Mentor: Maestri, Rhandrey; Lecrivain, Gregory

Permalink: https://www.hzdr.de/publications/Publ-37414
Publ.-Id: 37414


Curvilinear and 3D micromagnetism: geometrically curved ferro- and antiferromagnets

Makarov, D.

Curvilinear magnetism is a framework, which helps understanding the impact of geometrical curvature on complex magnetic responses of curved 1D wires and 2D shells [1-3]. The lack of inversion symmetry and emergence of curvature induced anisotropy and Dzyaloshinskii-Moriya interaction (DMI) stemming from the exchange interaction [4,5] are characteristic of curved surfaces. Recently, a non-local chiral symmetry breaking was discovered [6], which is responsible for the coexistence and coupling of multiple magnetochiral properties within the same magnetic object [7].
Regarding antiferromagnets, it is demonstrated that intrinsically achiral one-dimensional curvilinear antiferromagnets behave as a chiral helimagnet with geometrically tunable DMI, orientation of the Neel vector and the helimagnetic phase transition [8-10]. This positions curvilinear antiferromagnets as a platform for geometrically tunable antiferromagnetic spinorbitronics.

[1] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[2] D. Makarov et al., Adv. Mat. 34, 2101758 (2022).
[3] D. Sheka et al., Small 18, 2105219 (2022).
[4] Y. Gaididei et al., PRL 112, 257203 (2014).
[5] O. Volkov et al., PRL 123, 077201 (2019).
[6] D. Sheka et al., Commun. Phys. 3, 128 (2020).
[7] O. Volkov et al., Nature Com. 14, 1491 (2023).
[8] O. Pylypovskyi et al., Nano Lett. 20, 8157 (2020).
[9] O. Pylypovskyi et al., APL 118, 182405 (2021).
[10] Y. Borysenko et al., PRB 106, 174426 (2022).

Keywords: curvilinear magnetism; 3D nanostructures

Related publications

  • Invited lecture (Conferences)
    68th Annual Conference on Magnetism and Magnetic Materials, 30.10.-03.11.2023, Dallas, USA

Permalink: https://www.hzdr.de/publications/Publ-37413
Publ.-Id: 37413


Curvilinear and 3D low-dimensional magnetic architectures in research and technology

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review current application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions [4] and enables fundamentally new non-local chiral symmetry breaking effect [5,6]. Application potential of geometrically curved magnetic architectures is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices, magnetic soft robotics [7] as well as on-skin interactive electronics relying on thin films [8,9,10] as well as printed magnetic composites [11,12,13].

[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
[5] D. D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020).
[6] O. M. Volkov et al., Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nature Communications 14, 1491 (2023).
[7] M. Ha et al., Reconfigurable Magnetic Origami Actuators with On-Board Sensing for Guided Assembly. Advanced Materials 33, 2008751 (2021).
[8] G. S. Canon Bermudez et al., Magnetosensitive e-skins for interactive devices. Advanced Functional Materials (Review) 31, 2007788 (2021).
[9] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[10] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[11] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[12] E. S. Oliveros Mata et al., Dispenser printed bismuth-based magnetic field sensors with non-saturating large magnetoresistance for touchless interactive surfaces. Adv. Mater. Technol. 7, 2200227 (2022).
[13] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: curvilinear magnetism; magnetic solitons; printed magnetoelectronics; shapeable magnetic field sensors

Related publications

  • Invited lecture (Conferences)
    XII-Latin American Workshop on Magnetism, Magnetic Materials & their Applications, 16.-20.10.2023, Puerto Varas, Chile

Permalink: https://www.hzdr.de/publications/Publ-37412
Publ.-Id: 37412


From curvilinear magnetism to shapeable magnetoelectronics

Makarov, D.

Extending 2D structures into 3D space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics, superconductivity and magnetism [1,2]. This approach provides means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape of magnetic thin films and nanowires [2,3]. In this talk, we will address fundamentals of curvature-induced effects in magnetism and review current application scenarios. In particular, we will demonstrate that curvature allows tailoring fundamental anisotropic and chiral magnetic interactions [4] and enables fundamentally new non-local chiral symmetry breaking effect [5,6]. Application potential of geometrically curved magnetic architectures is currently being explored as mechanically reshapeable magnetic field sensors for automotive applications, memory, spin-wave filters, high-speed racetrack memory devices as well as on-skin interactive electronics relying on thin films [7,8] as well as printed magnetic composites [9] with appealing self-healing performance [10].

Reference list
[1] P. Gentile et al., Electronic materials with nanoscale curved geometries. Nature Electronics (Review) 5, 551 (2022).
[2] D. Makarov et al., New Dimension in Magnetism and Superconductivity: 3D and Curvilinear Nanoarchitectures. Advanced Materials (Review) 34, 2101758 (2022).
[3] D. Makarov et al., Curvilinear micromagnetism: from fundamentals to applications (Springer, Zurich, 2022).
[4] O. Volkov et al., Experimental observation of exchange-driven chiral effects in curvilinear magnetism. Physical Review Letters 123, 077201 (2019).
[5] D. D. Sheka et al., Nonlocal chiral symmetry breaking in curvilinear magnetic shells. Communications Physics 3, 128 (2020).
[6] O. M. Volkov et al., Chirality coupling in topological magnetic textures with multiple magnetochiral parameters. Nature Communications 14, 1491 (2023).
[7] J. Ge et al., A bimodal soft electronic skin for tactile and touchless interaction in real time. Nature Communications 10, 4405 (2019).
[8] G. S. Canon Bermudez et al., Electronic-skin compasses for geomagnetic field driven artificial magnetoception and interactive electronics. Nature Electronics 1, 589 (2018).
[9] M. Ha et al., Printable and Stretchable Giant Magnetoresistive Sensors for Highly Compliant and Skin-Conformal Electronics. Advanced Materials 33, 2005521 (2021).
[10] R. Xu et al., Self-healable printed magnetic field sensors using alternating magnetic fields. Nature Communications 13, 6587 (2022).

Keywords: curvilinear magnetism; shapeable magnetoelectronics; printed magnetoelectronics; soft magnetic composites

Related publications

  • Invited lecture (Conferences) (Online presentation)
    NATO advanced research workshop "Functional Spintronic Nanomaterials 
for Radiation Detection and Energy Harvesting", 25.-27.09.2023, Kyiv, Ukraine

Permalink: https://www.hzdr.de/publications/Publ-37411
Publ.-Id: 37411


Development of Zinc Targetry: Production of diagnostic 67Ga and theranostic 67Cu

Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.

Objectives: Radionuclide availability plays a key role for development of new radiopharmaceuticals. Moreover, theranostic matched pairs of radionuclides have aroused interest in the last couple of years. On the one hand, 68Ga has been used as a diagnostic counterpart to the therapeutic β--emitter 177Lu, however, due to its short half-life (68 min), further alternatives have to be considered. In particular 67Ga (half-life: 3.26 d) as the longest-lived of the radiogallium isotopes has γ-lines that can be used for SPECT imaging (93.3 keV, 184 keV). On the other hand, 67Cu is referred as a theranostic radionuclide due to its β--emission and γ-emission suitable for SPECT, forming a perfect matched pair with the PET radionuclides 61/64Cu. At HZDR the zinc targetry and target chemistry developed for 67Cu production [1] has been applied to produce 67Ga.

Methods: 67Cu production consisted of proton irradiation (16.8 MeV, 60 µA, up to 20 h, 30° solid target configuration) of 70Zn targets (100-140 mg/cm2) electrodeposited onto silver via the 70Zn(p,α)67Cu nuclear reaction. Target work-up comprise a two- or three-step chromatographic column separation [1]. Gamma spectroscopy was used to quantify the radionuclidic purity (RNP), ICP-MS for the molar activity (Am) and test radiolabeling with the macrocyclic complexing agent TETA for apparent molar activity (AMA) quantification. Additionally, 67Ga was produced by proton irradiation (19 MeV, 35 µA, 2 h, 30° solid target configuration) of enriched 68Zn targets (60-70 mg/cm2) electrodeposited onto gold via the 68Zn(p,2n)67Ga nuclear reaction. After “cooling down” of the target (12-16 h, decay of co-produced 68Ga), the radiochemical separation consisted of a two-step chromatographic column separation; first a 1 mL TK400 cartridge followed by a 0.3 mL DGA branched cartridge. RNP was quantified by gamma spectroscopy.

Results: Activity yields of > 1.0 GBq 67Cu at EOB were reached, leading to over 800 MBq [67Cu]CuCl2 at EOP in 1.5 mL of 0.05 M HCl with RNP g.t. 99.5 % (at EOP) and AMA up to 300 GBq/µmol (EOB corrected). Furthermore, activities of up to 1.8 GBq 67Ga at EOB, and ca. 1.0 GBq [67Ga]GaCl3 at EOP in 0.5 mL of 0.05 M HCl were produced. First 67Ga gamma spectroscopy results showed a RNP of over 99 % at EOP. In both cases, the activity reached represented about 60 % to 70 % of the calculated yield.

Conclusions: Production of the radionuclides 67Cu and 67Ga from proton irradiation of zinc targets is being performed at HZDR. Both radionuclide product solutions proved sufficient quality regarding RNP and radiolabeling properties. further optimization of the 67Ga production is planned. Although 67Cu activities produced are not enough for clinical demand, the obtained yields are adequate for first in vitro and in vivo studies while other production routes are being explored.

References:

[1] Brühlmann SA, Walther M, Kreller M, Reissig F, Pietzsch H-J, Knieß T and Kopka K. Pharmaceuticals 2023, 16, 314.

  • Contribution to proceedings
    29. Jahrestagung der AGRR, 28.-30.09.2023, Bad Salzuflen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37410
Publ.-Id: 37410


Production of Lanthanum-133 via the134Ba(p,2n)133La Nuclear Reaction with High Radionuclide Purity for Theranostic Purposes

Brühlmann, S. A.; Kreller, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.; Walther, M.; Reissig, F.

Aim/Introduction: Actinium-225 has gained great importance in Targeted Alpha Therapy (TAT) due to its suitable physical and chemical properties. In past years, studies using 225Ac-PSMA-617 have shown promising results [1], however, the macropa chelator has proven more beneficial properties regarding labelling and stability in vivo as compared with DOTA. While 68Ga has been used for DOTA-based radioconjugates, the macropa chelator lacks an imaging radionuclide counterpart. For this purpose, the β+-emitter 133La is an attractive candidate due to its physical properties and similar to 225Ac coordination chemistry. Following our recent publication [2], further optimization of the production of 133La with high radionuclidic purity (RNP) for theranostic purposes is presented. Materials and Methods: Lanthanum-133 was produced via the 134Ba(p,2n)133La nuclear reaction. Proton irradiation (19 MeV, 35 µA, 30 min) was performed using the HZDR TR-FLEX (ACSI) cyclotron on silver discs filled with 25 mg of [134Ba]BaCO3 capped with a 25 µm aluminum foil. The solid target was opened and the powder dissolved in 2 mL of 1 M HNO3. A one-step separation was carried out with a branched DGA resin cartridge after testing other resins. The 134Ba-containing fractions were collected and recycled through [134Ba]BaCO3 precipitation. Test radiolabelling of macropa-derived PSMA conjugates previously published by our group was performed in the MBq/nmol range [3]. Results: Lanthanum-133 yields of ca. 1.8 GBq for the described targets were reached at end of bombardment (EOB), accounting for about 65 % of the theoretical yield. After radiochemical separation, 1.2 GBq 133La were collected in 1 mL of 0.05 M HCl ready to label, with a RNP over 99.5 %. Further studies showed no detriment of the RNP by 21 MeV proton irradiation, thus being feasible irradiation of larger targets (prior thermal studies). Furthermore, quantitative radiolabeling was achieved with ligand concentrations down to 300 MBq/nmol. Conclusion: Lanthanum-133 of high RNP was produced for the first time. Considering future medical demands, the scale up to radioactivity amounts that are needed for clinical application purposes could be achieved by increasing the irradiation time. Alternatively, irradiation with higher currents or of thicker targets could also lead to higher activities. Based on these results, our group will attempt to establish a diagnostic platform for 225Ac-TAT based on 133La-macropa radioconjugates instead of the conventional 68Ga-DOTA application. References: [1] Kratochwil et al., J. Nucl. Med. 2016, 57, 1941-1944 [2] Brühlmann et al., Pharmaceuticals 2022, 15, 1167. [3] Reissig et al., Cancers 2021, 13, 1974.

  • Open Access Logo Contribution to proceedings
    EANM'23, 09.-13.09.2023, Wien, Austria

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Publ.-Id: 37409


Data publication: Multitask learning with convolutional neural networks and vision transformers can improve outcome prediction for head and neck cancer patients

Starke, S.; Zwanenburg, A.; Leger, K.; Lohaus, F.; Linge, A.; Schreiber, A.; Kalinauskaite, G.; Tinhofer, I.; Guberina, N.; Guberina, M.; Balermpas, P.; von der Grün, J.; Ganswindt, U.; Belka, C.; Peeken, J. C.; Combs, S. E.; Böke, S.; Zips, D.; Richter, C.; Troost, E. G. C.; Krause, M.; Baumann, M.; Löck, S.

This dataset contains the model checkpoints, predictions and performance metrics for the multitask neural networks presented in the corresponding manuscript.

Keywords: survival analysis; vision transformer; convolutional neural network; multitask learning; tumor segmentation; head and neck cancer; Cox proportional hazards; loco-regional control; progression-free survival; discrete-time survival models

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Permalink: https://www.hzdr.de/publications/Publ-37408
Publ.-Id: 37408


Cyclotron-based production of the theranostic radionuclide 67Cu

Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.

Objectives
Copper-67 (half-life 61.83 h, β--emission [mean energy 140 keV], γ-emission [184.6 keV, 48.7 % intensity]), is a promising radiometal due to its theranostic potential. Moreover, it forms a perfect matched pair with the
β+-emitters 61Cu and 64Cu. However, broad application of this radionuclide is limited due to its low availability. In this work, we investigate the no-carrier-added 67Cu production via the 70Zn(p,α)67Cu reaction [1].

  • Contribution to proceedings
    10. Radiochemischer Workshop, 12.-14.06.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37407
Publ.-Id: 37407


Understanding electronic correlations in warm dense quantum plasmas

Dornheim, T.

Warm dense matter (WDM)---an extreme state that is characterized by extreme densities and temperatures---has emerged as one of the most active frontiers in plasma physics and material science. In nature, WDM occurs in astrophysical objects such as giant planet interiors and brown dwarfs. In addition, WDM is highly important for cutting-edge technological applications such as inertial confinement fusion and the discovery of novel materials. In the laboratory, WDM is studied experimentally in large facilities around the globe, and new techniques have facilitated unprecedented insights. Yet, the interpretation of these experiments requires a reliable diagnostics based on accurate theoretical modeling, which is a notoriously difficult task [1].

In this work, I will give an overview of how we can use exact ab-initio path integral Monte Carlo (PIMC) simulations [2] together with thermal density functional theory (DFT) calculations to get new insights into the behavior of WDM. This includes recent results for various density response properties [3] such as the exchange—correlation (XC) kernel [2,4], and the utility of PIMC reference data to assess the accuracy of different XC functionals [5].

Finally, I will show how switching to the imaginary-time representation allows us to significantly improve the interpretation of X-ray Thomson scattering (XRTS) experiments, which are a key diagnostic for WDM [3]. Specifically, I will present a model-free temperature diagnostic [6] based on the well-known principle of detailed balance, but available for all wave numbers, and a new idea to directly extract the electron—electron static structure factor from an XRTS measurement [7]. As an outlook, I will show how new PIMC capabilities [8] will allow to give us novel insights into electronic correlations in warm dense quantum plasmas, leading to unprecedented agreement between experiments [9] and theory.

[1] M. Bonitz et al., Physics of Plasmas 27, 042710 (2020)
[2] M. Böhme et al., Physical Review Letters 129, 066402 (2022)
[3] T. Dornheim et al., Physics of Plasmas 30, 032705 (2023)
[4] Zh. Moldabekov et al., Journal of Chemical Theory and Computation 19, 1286-1299 (2023)
[5] Zh. Moldabekov et al., arXiv:2308.07916 (submitted)
[6] T. Dornheim et al., Nature Communications 13, 7911 (2022)
[7] T. Dornheim et al., arXiv:2305.15305 (submitted)
[8] T. Dornheim et al., arXiv:2308.06071 (submitted)
[9] T. Döppner et al., Nature 618, 270-275 (2023)

  • Invited lecture (Conferences)
    CECAM Flagship Workshop: Accelerating Improvements in Density Functional Theory, 21.-25.08.2023, Lausanne, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-37406
Publ.-Id: 37406


Cyclotron-based Production of Lanthanum-133 with High Radionuclide Purity for Theranostic Purposes

Brühlmann, S. A.; Kreller, M.; Pietzsch, H.-J.; Kopka, K.; Mamat, C.; Walther, M.; Reissig, F.

Objectives:

Targeted Alpha Therapy (TAT) is a research field of highest interest in specialized molecular radionuclide therapy. In particular, the radionuclide actinium-225 provides all necessary physical and chemical properties for a successful clinical application. Although the macropa chelator has shown beneficial properties regarding labelling and stability in vivo as compared with DOTA, the former lacks an imaging radionuclide counterpart to 225Ac. In this connection, lanthanum is an appropriate surrogate for actinium due to its comparable coordination chemistry. Furthermore, the imaging properties of the β+-emitter lanthanum-133 makes it an attractive candidate as a theranostic matched pair to 225Ac. Following our recent publication [1], 133La of high radionuclide purity for theranostic purposes was produced through the 134Ba(p,2n)133La reaction.

  • Open Access Logo Contribution to proceedings
    25th International Symposium in Radiopharmaceutical Sciences, 22.-26.05.2023, Honolulu, USA

Permalink: https://www.hzdr.de/publications/Publ-37405
Publ.-Id: 37405


Cyclotron Production of Copper-67: Exploring the limits

Brühlmann, S. A.; Walther, M.; Kreller, M.; Reissig, F.; Pietzsch, H.-J.; Knieß, T.; Kopka, K.

Objectives.
Copper-67 (67Cu, half-life 61.83 h, β--emission [mean energy 140 keV], γ-emission [184.6 keV with 48.7 % intensity, i.a.]), is a promising radiometal due to its theranostic potential. While 61Cu and 64Cu are suitable for PET, matched pair 67Cu brings a therapeutic counterpart to the table. However, broad application of this radionuclide is limited due to its low availability. No-carrier-added 67Cu can be produced through the 70Zn(p,α)67Cu reaction, while featuring a low yield and the need of expensive 70Zn target material. Nevertheless, co-production of other copper nuclides (from other zinc isotopes low-content) as well as contamination with stable copper can be minimized but not completely eliminated.

  • Open Access Logo Contribution to proceedings
    25th International Symposium in Radiopharmaceutical Sciences, 22.-26.05.2023, Honolulu, USA

Permalink: https://www.hzdr.de/publications/Publ-37404
Publ.-Id: 37404


Guidance for measuring the axial gas dispersion coefficient in bubble columns via gas flow modulation

Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.

The gas flow modulation technique (GFM) is a novel non-invasive approach for measuring the axial gas dispersion coefficient in bubble columns. The approach overcomes the limitations of traditional tracer-based techniques, qualifying it as a promising candidate for measurements in an industrial setting. The current work elaborates systematic guidelines for selecting the experimental parameters for the GFM. These guidelines are crucial for its successful application. In addition, a novel approach is proposed for confidently extracting the values and the uncertainty limits of the axial gas dispersion coefficient. Afterwards, we show the application of these guidelines in the frame of a case study that serves the purpose to illustrate their application and to demonstrate their usefulness.

Keywords: gas flow modulation; axial dispersion coefficient; bubble columns; gas flow modulation workflow

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Permalink: https://www.hzdr.de/publications/Publ-37403
Publ.-Id: 37403


Unravelling the nonlinear ideal density response of many-body systems

Tolias, P.; Dornheim, T.; Moldabekov, Z.; Vorberger, J.

Nonlinear density response theory is revisited focusing on the harmonically perturbed finite temperature uniform electron gas. Within the non-interacting limit, brute force quantum kinetic theory calculations for the quadratic, cubic, quartic and quintic responses reveal a deep connection with the linear response. Careful analysis of the static long wavelength limit led us to conjecture a canonical non-interacting form that expresses arbitrary order nonlinear responses as the weighted sum of the linear responses evaluated at all multiple harmonics. This harmonic expansion is successfully validated against ab initio path integral Monte Carlo simulations.

Permalink: https://www.hzdr.de/publications/Publ-37402
Publ.-Id: 37402


Schätze im Müll

Matys, S.

Anhand des Beispiels Mobiltelefon wird erklärt, wie viele wertvolle Rohstoffe in elektronischen Geräten stecken und wie die Forschenden am HIF mit der Etablierung neuer (bio)technologischer Methoden dazu beitragen, dem Ziel einer geschlossenen Kreislaufwirtschaft näher zu kommen.

Keywords: Biotechnologie; Kreislaufwirtschaft; Wertstoffe; Metalle

  • Lecture (others)
    Abschlussveranstaltung Mathematikolympiade 2023 Landkreis Bautzen, 26.02.2023, Radeberg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37401
Publ.-Id: 37401


Asphericity derived from [18F]FDG PET as a new prognostic parameter in cervical cancer patients

Cegla, P.; Hofheinz, F.; Burchardt, E.; Czepczyński, R.; Kubiak, A.; van den Hoff, J.; Nikulin, P.; Bos-Liedke, A.; Roszak, A.; Cholewinski, W.

The objective of this study was to assess the prognostic value of asphericity (ASP) and standardized uptake ratio (SUR) in cervical cancer patients. Retrospective analysis was performed on a group of 508 (aged 55 ± 12 years) previously untreated cervical cancer patients. All patients underwent a pretreatment [18F]FDG PET/CT study to assess the severity of the disease. The metabolic tumor volume (MTV) of the cervical cancer was delineated with an adaptive threshold method. For the resulting ROIs the maximum standardized uptake value (SUVmax) was measured. In addition, ASP and SUR were determined as previously described. Univariate Cox regression and Kaplan–Meier analysis with respect to event free survival (EFS), overall survival (OS), freedom from distant metastasis (FFDM) and locoregional control (LRC) was performed. Additionally, a multivariate Cox regression including clinically relevant parameters was performed. In the survival analysis, MTV and ASP were shown to be prognostic factors for all investigated endpoints. Tumor metabolism quantified with the SUVmax was not prognostic for any of the endpoints (p > 0.2). The SUR did not reach statistical significance either (p = 0.1, 0.25, 0.066, 0.053, respectively). In the multivariate analysis, the ASP remained a significant factor for EFS and LRC, while MTV was a significant factor for FFDM, indicating their independent prognostic value for the respective endpoints. The alternative parameter ASP has the potential to improve the prognostic value of [18F]FDG PET/CT for event-free survival and locoregional control in radically treated cervical cancer patients.

Keywords: NA

Permalink: https://www.hzdr.de/publications/Publ-37400
Publ.-Id: 37400


Multi-sensor spectral database of WEEE polymers

de Lima Ribeiro, A.; Fuchs, M.; Lorenz, S.; Röder, C.; Heitmann, J.; Gloaguen, R.
DataCollector: Madriz, Yuleika; DataCollector: Herrmann, Erik

Polymers represent around 25% of total waste from electronic and electric equipment. Any successful recycling process must ensure that polymer-specific functionalities are preserved, to avoid downcycling. This requires a precise characterization of particle compounds moving at high speeds on conveyor belts in processing plants. We present a multi-sensor database including spectra acquired from imaging and point measurement sensors on 23 polymers including ABS, PS, PC, PE-types, PP, PVC, PET-types, PMMA, and PTFE. The techniques applied include hyperspectral imaging sensors (HSI) to map reflectance in the visible to near infrared (VNIR, (350–1000) nm ), short-wave (SWIR, (1000–2500) nm) and mid-wave infrared (MWIR, (2500–5000) nm) as well as point Raman, FTIR and portable spectral spectroradiometer (PSR) instruments.

Keywords: plastics; e-waste; hyperspectral; Raman

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Permalink: https://www.hzdr.de/publications/Publ-37399
Publ.-Id: 37399


Coupled 3D neutronics/thermal-hydraulics analysis of Superphénix start-up tests with DYN3D/ATHLET code system

Ponomarev, A.; Nikitin, E.; Fridman, E.

The capabilities of the DYN3D/ATHLET coupled code system were recently extended to allow for 3D neutron kinetics/thermal hydraulics analyses of Sodium cooled Fast Reactors at reactor system level. In this paper, the DYN3D/ATHLET coupled code system was applied to analyze the Superphenix reactor transient benchmark. The benchmark comprises six operational transients initiated during the SPX reactor start-up tests, covering a wide range of reactor operating states. The peculiarity of these transients is the necessity to consider thermal expansions of major structural elements of the primary system, which significantly influence the transient position of control rods in the core. The paper includes a brief summary of the benchmark specifications, description of the neutron kinetics and thermal hydraulics models, an analysis of the simulation results, and a comparison to the experimental data.

Keywords: ATHLET; DYN3D; Monte Carlo; Serpent; SFR; Superphenix; Thermal hydraulics analysis; Control rods

Permalink: https://www.hzdr.de/publications/Publ-37397
Publ.-Id: 37397


Strömungstechnischer Funktionsnachweis für Verschlussbauwerke und flüssigkeitsgestützte Abdichtung des Kontaktbereiches Phase III (Vertiefung Kenntnisstand Kontaktbereich & Injektionsmittel, in situ-Versuche) (STROEFUN III) Schlussbericht (Hauptband)

Bauermeister, J.; Langefeld, O.; Schieweg, A.; Raebiger, L.; Abel, P.; Viertel, T.; Flemming, J.; Noorhan, W.; Ley, S.; Glaubach, U.; Wilsnack, T.; Müller-Hoeppe, N.; Hussein, A.; Fischer, T.; Lack, D.; Schicht, T.; Brüning, M.; Kulenkampff, J.

In dem Forschungsvorhaben STROEFUN III wurde ein Konzept für die strömungstechnische Testung von Streckenverschlussbauwerken entwickelt, installiert und in einem Streckenver-schlussbauwerk in der Grube Teutschenthal erfolgreich getestet. Das Testkonzept für Bauwerke oder Bauwerksabschnitte aus hydraulisch abbindenden Dichtbaustoffen basiert auf der Druckbeaufschlagung von mindestens 3 an der Streckenkontur installierten Ringkammern. Diese können individuell mit Gas und/oder Flüssigkeit im stationären oder instationären Druck-regime beaufschlagt werden. Das Konzept konzentriert sich auf die Testung des Kontaktbereiches Baustoff/ Gebirge als bestimmenden Strömungsraum für die Dichtwirkung von Stre-ckenverschlussbauwerken. Im Ergebnis der modellbasierten Auswertung der im Test ermittelten Druckganglinien sind Aussagen über die Permeabilität des Bauwerkes im Kontakt Bau-stoff/ Gebirge und, daraus abgeleitet, für die integrale Permeabilität des Bauwerkes möglich. Das Testkonzept ist ein zusätzlicher Baustein für den gegenständlichen, strömungstechni-schen Funktionstest von Streckenverschlussbauwerken im Rahmen der Nachweisführung. Im Ergebnis des Forschungsvorhabens liegen umfangreiche Kenntnisse zum Standort und zum Bauwerk aus MgO-Baustoff (angelehnt an die A1-Basisrezeptur) vor. Dieser umfangreiche Kenntnisstand, die Zugänglichkeit und die Standortbedingungen bieten die Chance in der nahen Zukunft eine Vielzahl an Untersuchungen zur nachträglichen Vergütung des Bauwerkes mit Beurteilung der strömungstechnischen Wirkung der Vergütung sowie zum zeitabhängigen Baustoffverhalten im Kontakt zur Atmosphäre und im Kontakt zur Salzlösung durchzuführen.

In the research project STROEFUN III a concept for the fluidic testing of closuring structures was developed, installed and successfully tested on a closuring structure at the Teutschenthal mine. The test concept for structures or sections of structures made of hydraulically settling sealing materials is based on the pressurization of at least 3 ring chambers installed on the drift contour. These can be individually pressurized with gas and/or liquid in a steady-state or transient pressure regime. The concept concentrates on testing the contact area between material and rock mass as the determining flow space for the sealing effect of drift closure structures. As a result of the modelbased evaluation of the pressure hydrographs determined in the test, statements can be made about the permeability of the structure in the contact between the building material and the rock mass and, derived from this, about the integral permeability of the structure. The test concept is an additional option for the fluidic functional test of drifts closure structures within the scope of verification of sealing effect. As a result of the research project, extensive knowledge is available on the location and the structure made of MgO-building material. This extensive knowledge, the accessibility and the site conditions offer the opportunity in the near future to carry out a large number of investigations on the subsequent improvement of the structure with assessment of the fluidic effect of the improvement as well as on the time-dependent behavior of the building material in contact with the atmosphere and in contact with the salt solution.

Keywords: underground repository; underground dam sealing; MgO concrete; closure structure; µCT

Permalink: https://www.hzdr.de/publications/Publ-37396
Publ.-Id: 37396


Timing and origin of skarn-, greisen-, and vein-hosted tin mineralization at Geyer, Erzgebirge (Germany)

Meyer, N.; Markl, G.; Gerdes, A.; Gutzmer, J.; Burisch, M.

This contribution presents new insights into the origin and age relationships of the Geyer tin deposit in the Erzgebirge, Germany. Tin mineralization occurs in skarns, greisen, and in cassiterite-bearing fluorite-quartz veins. Skarn alteration replaces marble layers of the Cambrian Jáchymov Group and occurs in two clearly distinct stages. The first skarn stage forms skarnoid textured assemblages of clinopyroxene, garnet, and wollastonite with no tin phases recognized. Garnet U-Pb ages of this skarn stage (~322 Ma) relate the earlier skarn stage to the emplacement of the Ehrenfriedersdorf granite (~324 to 317 Ma). The second stage of skarn alteration is marked by the occurrence of malayaite and cassiterite associated with garnet recording ages of 307 to 301 Ma. Greisen- and skarn-hosted cassiterite-bearing veins provide U-Pb ages in the range of 308 to 305 Ma, relating greisenization and vein formation to the same magmatic-hydrothermal event as the second skarn stage. This suggests that tin mineralization at Geyer is related to a distinctly younger magmatic-hydrothermal event, clearly postdating the Ehrenfriedersdorf granite, which was previously assumed as the source of the tin-rich fluids. Fluid inclusions show salinities in the range of 1.0 to 31.5 % eq. w(NaCl±CaCl2) and homogenization temperatures between 255 and 340 °C. Cassiterite-associated fluid inclusions show indications for heterogeneous entrapment and dilution of hydrothermal with meteoric fluids. Dilution of high-salinity fluids with low-salinity fluids and cooling of the system was probably a decisive process in the precipitation of cassiterite in the Geyer Sn system.

Keywords: Erzgebirge; skarn; greisen; tin

Permalink: https://www.hzdr.de/publications/Publ-37395
Publ.-Id: 37395


Ion-induced telecom single-photon emitters in silicon

Astakhov, G.; Hollenbach, M.; Klingner, N.; Jagtap, N.; Bischoff, L.; Fowley, C.; Kentsch, U.; Hlawacek, G.; Erbe, A.; Abrosimov, N. V.; Helm, M.; Berencen, Y.

Single-photon emitters (SPEs) are one of the elementary building blocks for photonic quantum information and optical quantum computing. One of the upcoming challenges is the monolithic photonic integration and coupling of single-photon emission, reconfigurable photonic elements, and single-photon detection on a silicon chip in a controllable manner. Particularly, fully integrated SPEs on-demand are required for enabling a smart integration of advanced functionalities in on-chip quantum photonic circuits. The major challenge in realizing a fully monolithic, photonic integrated circuitry lies in the development of a quantum light source in silicon since the indirect nature of the small energy bandgap does not allow for efficient PL emission. Nevertheless, below-bandgap light emission can be used for good advantage by exploiting extrinsic and intrinsic point defects acting as SPEs. Indeed, the isolation of SPEs, such as G-, W-, and T-centers, in the optical telecommunication O-band has been recently realized in silicon.. In all these cases, however, SPEs were created uncontrollably in random locations, preventing their scalability.
We present mask-free nanofabrication involving a quasi-deterministic creation of single G- and W-centers in silicon wafers using focused-ion beam (FIB) writing. We also implement a scalable, broad-beam implantation protocol compatible with the complementary-metal-oxide-semiconductor (CMOS) technology to fabricate telecom SPEs at desired positions on the nanoscale.

Keywords: Quantum technologies; Single photon emitters; Silicon; Defects

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  • Invited lecture (Conferences)
    25th International Conference on the Electronic Properties of Two-Dimensional Systems (EP2DS-25) and 21st International Conference on Modulated Semiconductor Structures (MSS-21), 10.-14.07.2023, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-37394
Publ.-Id: 37394


Hybrid quantum technologies with spin qubits in SiC

Astakhov, G.

An overview of quantum technologies based on spin defects in SiC is presented. It includes microwave assisted spectroscopy, inverted excited-state structure for spin-photon entanglement protocols and acoustic control of spin qubits.

Keywords: Quantum technologies; Spin qubits; Silicon carbide; Defects

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  • Invited lecture (Conferences)
    Seminar at the Institute of Applied Quantum Technologies, 09.02.2023, Erlangen, Germany

Permalink: https://www.hzdr.de/publications/Publ-37393
Publ.-Id: 37393


18F-FDG PET/CT-derived total lesion glycolysis predicts abscess formation in patients with surgically confirmed infective endocarditis: Results of a retrospective study at a tertiary center

Maria Sag, S. J.; Menhart, K.; Hitzenbichler, F.; Schmid, C.; Hofheinz, F.; van den Hoff, J.; Maier, L. S.; Hellwig, D.; Grosse, J.; Sag, C. M.

Background
Abnormal activity of 18F-FDG PET/CT is a major Duke criterion in the diagnostic work-up of infective prosthetic valve endocarditis (IE). We hypothesized that quantitative lesion assessment by 18F-FDG PET/CT-derived standard maximum uptake ratio (SURmax), metabolic volume (MV), and total lesion glycolysis (TLG) might be useful in distinct subgroups of IE patients (e.g. IE-related abscess formation).

Methods
All patients (n = 27) hospitalized in our tertiary IE referral medical center from January 2014 to October 2018 with preoperatively performed 18F-FDG PET/CT and surgically confirmed IE were included into this retrospective analysis.

Results
Patients with surgically confirmed abscess formation (n = 10) had significantly increased MV (by ~ fivefold) and TLG (by ~ sevenfold) as compared to patients without abscess (n = 17). Receiver operation characteristics (ROC) analyses demonstrated that TLG (calculated as MV × SURmean, i.e. TLG (SUR)) had the most favorable area under the ROC curve (0.841 [CI 0.659 to 1.000]) in predicting IE-related abscess formation. This resulted in a sensitivity of 80% and a specificity of 88% at a cut-off value of 14.14 mL for TLG (SUR).

Conclusion
We suggest that 18F-FDG PET/CT-derived quantitative assessment of TLG (SUR) may provide a novel diagnostic tool in predicting endocarditis-associated abscess formation.

Keywords: 18F-FDG PET/CT; infective endocarditis; total lesion glycolysis; valve abscess

Permalink: https://www.hzdr.de/publications/Publ-37392
Publ.-Id: 37392


Numerical Simulations of the Pore-Scale Flow in Ceramic Open-Cell Foams

Hernandez, J. N. C.; Schubert, M.; Hampel, U.

Porous materials are abundant in nature and in industrial applications. Their ability to allow fluids passing through them is of major importance and plays a very important role in various operations, such as hydrocarbon extraction of reservoirs in oil production [1]; or by dictating the amount of heat that can be dissipated from an electronic component using force convection (e.g. heat sinks) [2]. The key indicator of how easily fluids pass through porous materials is the “permeability”, which allows describing pressure loss and flow velocity in porous materials. However, the impact of droplet impingement inside open-cell foams and the retention time of a solid or liquid disperse phase cannot be described solely by the permeability. To study these phenomena current computing resources permit pore-scale CFD simulations, which relate structure and transport properties of porous materials. Instead of using equivalent geometrical models based on simple geometries just as spheres or cylinders, the genuine geometry representation of the porous structure is required, especially since porous media usually involve significant pore structure defects and feature multiple length scales, which produce different mechanisms of interaction within the pores.
The present work investigates the performance of pore-scale numerical simulations over genuine 3D geometrical representations of ceramic foams reconstructed from X-ray micro-computed tomography (μCT) scans of silicon-infiltrated silicon carbide” (SiSiC) open-cell foams with different nominal pore sizes using marching cubes algorithm [3]. To disclose the airflow velocity profile inside the foam simulations of single-phase air flow were conducted using finite volume method (FVM) for a wide range of Reynolds numbers including Reynolds-averaged Navier-Stokes (RANS) turbulence models. Good agreement was achieved especially between the computed pressure gradient and the experimental pressure measurements, even outperforming other conventional numerical models based on average pore properties such as porosity and surface area. Further simulations were carried out using a Lagrangian approach to analyze particular effects such as rebounding of a low mass fraction of the disperse phase on the ceramic structure and deposition thresholds.
The work already done pursues to improve upon the current state-of-the-art of pore-scale simulations, providing evidence of the feasibility to perform flow simulations on reconstructed representations of ceramic porous media that considerably are able to predict experimental flow properties.

  • Poster
    4th World Congress on Momentum, Heat and Mass Transfer (MHMT'19), 10.-12.04.2019, Rome, Italy
    DOI: 10.11159/icmfht19.124

Permalink: https://www.hzdr.de/publications/Publ-37391
Publ.-Id: 37391


Microwave Dielectric Properties of Open-Cell Solid Foams Based on Silicon Carbide Ceramics

Hernandez, J. N. C.; Sodatov, S.; Link, G.; Füssel, A.; Hampel, U.

Open-cell porous materials are abundant in industrial applications and are used for example as heat exchangers, thermal insulators, reaction catalysts, flow stabilizers, mass transfer enhancers, solar radiation absorbers and electrical heaters, etc. [1]. In recent years, the interest in solid foams based on silicon carbide “SiC” has regained popularity. Nevertheless, when applied to microwave applications there is a lack of reported properties. The key indicator of how a material interacts and is heated with microwaves is the “permittivity”, which is best described in a complex form. The aim of this work is to improve the database of complex permittivity of open-cell solid foams based on silicon carbide, which was determined using the cavity perturbation method [2]. Temperature dependent measurements of permittivity were performed in the range of 30 °C to 190 °C for three different foam materials, i.e. silicon infiltrated silicon carbide (SiSiC), pressureless sintered silicon carbide (SSiC) and silicate-bounded silicon carbide (SBSiC), with porosities in the range of 86.9 % to 96.5 % and pore size of 30 ppi (pore per inch), 45 ppi and 60 ppi. As a result, a model based on mixture rules was developed that well predicts the permittivity as a function of porosity.

Keywords: microwaves; complex permittivity; SiC; open-cell solid foams

  • Lecture (Conference)
    17th International Conference on Microwave and High Frequency Heating AMPERE 2019, 09.-12.6.2019, Valencia, Spain

Permalink: https://www.hzdr.de/publications/Publ-37390
Publ.-Id: 37390


Extending the coherence of spin defects in hBN enables advanced qubit control and quantum sensing

Rizzato, R.; Schalk, M.; Mohr, S.; Hermann, J. C.; Leibold, J. P.; Bruckmaier, F.; Salvitti, G.; Ji, P.; Astakhov, G.; Kentsch, U.; Helm, M.; Stier, A. V.; Finley, J. J.; Bucher, D. B.

Negatively-charged boron vacancy centers hexagonal Boron Nitride (hBN) are attracting increasing interest since they represent optically-addressable qubits in a van der Waals material. In particular, these spin defects have shown promise as sensors of temperature, pressure, and static magnetic fields. However, their short spin coherence time limits their scope for quantum technology. Here, we apply dynamical decoupling techniques to suppress magnetic noise and extend the spin coherence time by two orders of magnitude, approaching the fundamental T1 relaxation limit. Based on this improvement, we demonstrate advanced spin control and a set of quantum sensing protocols to detect electromagnetic signals in the MHz range with sub-Hz resolution. This work lays the foundation for nanoscale sensing using spin defects in an exfoliable material and opens a promising path to quantum sensors and quantum networks integrated into ultra-thin structures.

Keywords: Quantum technologies; 2D materials; Spintronics; Defects

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37389
Publ.-Id: 37389


Multitask Learning with Convolutional Neural Networks and Vision Transformers Can Improve Outcome Prediction for Head and Neck Cancer Patients

Starke, S.; Zwanenburg, A.; Leger, K.; Lohaus, F.; Linge, A.; Schreiber, A.; Kalinauskaite, G.; Tinhofer, I.; Guberina, N.; Guberina, M.; Balermpas, P.; von der Grün, J.; Ganswindt, U.; Belka, C.; Peeken, J. C.; Combs, S. E.; Böke, S.; Zips, D.; Richter, C.; Troost, E. G. C.; Krause, M.; Baumann, M.; Löck, S.

Neural-network-based outcome predictions may enable further treatment personalization of patients
with head and neck cancer. The development of neural networks can prove challenging when a limited number of cases is available. Therefore, we investigated whether multitask learning strategies, implemented through the simultaneous optimization of two distinct outcome objectives (multi-outcome) and combined with a tumor segmentation task, can lead to improved performance of convolutional neural networks (CNN) and vision transformers (ViT). Model training was conducted on two distinct multicenter datasets for the endpoints loco-regional control (LRC) and progression-free survival (PFS), respectively. The first dataset consisted of pre-treatment computed tomography (CT) imaging for 290 patients and the second dataset contained combined positron emission tomography (PET)/CT for 224 patients. Discriminative performance was assessed by the concordance index (C-index). Risk stratification was evaluated using log-rank tests. Across both datasets, CNN and ViT model ensembles achieved similar results. Multitask approaches showed favorable performance in most investigations. Multi-outcome CNN models trained with segmentation loss were identified as the optimal strategy across cohorts. On the PET/CT dataset, an ensemble of multi-outcome CNNs trained with segmentation loss achieved the best discrimination (C-index: 0.29, 95% confidence interval (CI): 0.22-0.36) and successfully stratified patients into groups with low and high risk of disease progression (p=0.003). On the CT dataset, ensembles of multi-outcome CNNs and of single-outcome ViTs trained with segmentation loss performed best (C-index: 0.26 and 0.26, CI: 0.18-0.34 and 0.18-0.35, respectively), both with significant risk stratification for LRC in independent validation (p=0.002 and p=0.011). Further validation of the developed multitask-learning models is planned based on a prospective validation study, which is currently ongoing.

Keywords: survival analysis; vision transformer; convolutional neural network; multitask learning; tumor segmentation; head and neck cancer; Cox proportional hazards; loco-regional control; progression-free survival; discrete-time survival models

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Permalink: https://www.hzdr.de/publications/Publ-37388
Publ.-Id: 37388


Plasmas, fluids and lasers

Nikl, J.

Plasma is the most abundant form of matter in our universe. Fluid dynamics then presents one of the most successful models of modern physics and lasers are the most versatile tools of the 21st century. All these topics are introduced and their joint applications at HZDR and elsewhere are presented.

  • Lecture (others)
    HZDR summer school, 31.07.-31.08.2023, HZDR Campus, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37387
Publ.-Id: 37387


Orientation resolved measurements of accelerations with sensor particles in bioreactors

Buntkiel, L.; Ma, Y.; Reinecke, S.; Hampel, U.

The measurement of the spatially distributed
flow field in large industrial vessels, e.g. biogas fermenters,
is not possible with commercially available measurement
equipment. Therefore the concept of flow following sensor
particles has been developed. They act as data loggers
within the vessel. The sensor particles are equipped with
a pressure sensor and an inertial measurement unit to
measure their motion. The measurements are taken in
the coordinate frame of the sensor particle and need to
be transformed into the vessel’s coordinate frame to ana-
lyze the flow field. This is done by an error-state Kalman
filter which estimates the orientation of the sensor par-
ticle with respect to the vessel based on the direction
of the gravitational acceleration and the local magnetic
field. Since no other aiding sensors are available or usable
within an industrial vessel particular emphasis was given
to the stochastic modeling of the inertial sensors and the
calibration of the accelerometer. Based on the orienta-
tion estimation, the measured acceleration is transformed
into the vessel frame. We performed two experiments in
a 1.4 m³ lab reactor to qualify this approach. The results
show, that the transformed acceleration is in good quali-
tative agreement with the known flow field inside the lab
reactor

Keywords: Sensor particle; Flow follower; Flow measurement; Kalman filter; Inertial measurements

Downloads

  • Secondary publication expected from 16.11.2024

Permalink: https://www.hzdr.de/publications/Publ-37386
Publ.-Id: 37386


Ultra-high dose rate radiobiology with protons at the DRACO and PENELOPE high power laser facilities

Metzkes-Ng, J.

Ultra-high dose rate radiobiology with protons at the DRACO and PENELOPE high power laser facilities

  • Invited lecture (Conferences)
    Very High Energy Electron Radiotherapy Conference 2023, 10.-13.07.2023, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37385
Publ.-Id: 37385


Fermionic physics from ab initio path integral Monte Carlo simulations of fictitious identical particles

Dornheim, T.; Tolias, P.; Groth, S.; Moldabekov, Z.; Vorberger, J.; Hirshberg, B.

The \emph{ab initio} path integral Monte Carlo (PIMC) method is one of the most successful methods in statistical physics, quantum chemistry and related fields, but its application to quantum degenerate Fermi systems is severely hampered by an exponential computational bottleneck: the notorious fermion sign problem. Very recently, Xiong and Xiong [J. Chem. Phys. 157, 094112 (2022)] have suggested to partially circumvent the sign problem by carrying out PIMC simulations of fictitious systems which contain an interpolating continuous variable ξ∈[−1,1] in their partition function, with the physical Fermi- and Bose-statistics corresponding to the endpoint limits ξ=−1 and ξ=1. It has been proposed that thermodynamic information about the fermionic limit might be obtained by path integral calculations within the bosonic sector ξ>0 combined with a quadratic ξ extrapolation throughout the fermionic sector ξ<0, essentially bypassing the sign problem. In this work, we show how the inclusion of the artificial parameter ξ can be interpreted as an effective penalty on the formation of permutation cycles in the PIMC simulation. We empirically demonstrate that the proposed extrapolation method breaks down for moderate to high quantum degeneracy. Instead, the method constitutes a valuable tool for the description of large Fermi-systems of weak quantum degeneracy. This is demonstrated for electrons in a 2D harmonic trap and for the archetypal uniform electron gas (UEG), where we find excellent agreement (∼0.5%) with exact configuration PIMC results in the high-density regime while attaining a speed-up exceeding eleven orders of magnitude. Finally, we extend the idea beyond the energy and analyze the radial density distribution (2D trap), as well as the static structure factor and imaginary-time density-density correlation function (UEG).

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37382
Publ.-Id: 37382


Simultaneous inhibition of discoidin domain receptor 1 and integrin αVβ3 radiosensitizes human glioblastoma cells

Elser, M.; Vehlow, A.; Juratli, T.; Cordes, N.

Glioblastomas (GBM) are the most common primary brain tumors in adults and associated with poor clinical outcomes due to therapy resistances and destructive growth. Interactions of cancer cells with the extracellular matrix (ECM) play a pivotal role in therapy resistances and tumor progression. In this study, we investigate the functional dependencies between the discoidin domain receptor 1 (DDR1) and the integrin family of cell adhesion molecules for the radioresponse of human glioblastoma cells. By means of an RNA interference screen on DDR1 and all known integrin subunits, we identified co-targeting of DDR1/integrin β3 to most efficiently reduce clonogenicity, enhance cellular radiosensitivity and diminish repair of DNA double strand breaks (DSB). Simultaneous pharmacological inhibition of DDR1 with DDR1-IN-1 and of integrins αVβ3/αVβ5 with cilengitide resulted in confirmatory data in a panel of 2D grown glioblastoma cultures and 3D gliospheres. Mechanistically, we found that key DNA repair proteins ATM and DNA-PK are altered upon DDR1/ integrin αVβ3 /integrin αVβ5 inhibition, suggesting a link to DNA repair mechanisms. In sum, the radioresistance of human glioblastoma cells can effectively be declined by co-deactivation of DDR1, integrin αVβ3 and integrin αVβ5.

Keywords: GBM; Integrins; Radiotherapy; DDR1

  • Open Access Logo American Journal of Cancer Research 13(2023)10, 4597-4612

Permalink: https://www.hzdr.de/publications/Publ-37381
Publ.-Id: 37381


Strong magnetoelastic coupling in MnCoSi compounds studied in pulsed magnetic fields

Zhang, F.; Bykov, E.; Gottschall, T.; van Dijk, N.; Brück, E.

The orthorhombic MnCoSi compounds have been found to present a large magnetoelastic coupling, which is regarded as the source for the magnetocaloric effect (MCE) and the magnetostrictive effect. As a result, these compounds are potential materials for caloric applications such as solid-state refrigeration. In the presentstudy, we offer fundamental insights in the magnetoelastic coupling in these compounds based on their structural, metamagnetic, and MCE behavior. The directly measured adiabatic temperature change (ΔTad) in different initial temperatures (down to 18 K) and pulsed magnetic fields (up to 40 T) presents a moderate MCE performance (the maximum ΔTad = –3.1 K for a field change of 13 T), which results from the metamagnetic behavior of these compounds. Furthermore, the magnetization measurements in pulsed (and static) magnetic fields indicate that the magnetoelastic coupling is significantly enhanced for increasing fields resulting in an improved saturation magnetization. The metamagnetic transition is continuously pushed to lower temperatures in higher fields. The phase diagram constructed from the experimental transition temperatures Tt and the critical magnetic fields μ0Hcr indicate that the transition is terminated below 18 K and that ferromagnetism is stabilized for fields above 22.3 T. Our results provide unique insights into the strong magnetoelastic coupling under high pulsed magnetic fields, providing guidelines for the design of giant magnetocaloric materials for future caloric applications.

Permalink: https://www.hzdr.de/publications/Publ-37380
Publ.-Id: 37380


Controlling the Propagation Asymmetry of Hyperbolic Shear Polaritons in Beta-Gallium Oxide

Matson, J.; Wasserroth, S.; Ni, X.; Obst, M.; Diaz-Granados, K.; Carini, G.; Maria Renzi, E.; Galiffi, E.; Folland, T. G.; Eng, L. M.; Klopf, J. M.; Mastel, S.; Armster, S.; Gambin, V.; Wolf, M.; Kehr, S. C.; Alu, A.; Paarmann, A.; Caldwell, J. D.

Structural anisotropy in crystals is crucial for controlling light propagation, particularly in the infrared spectral regime where optical frequencies overlap with crystalline lattice resonances, enabling light-matter coupled quasiparticles called phonon polaritons (PhPs). Exploring PhPs in anisotropic materials like hBN and MoO3 has led to advancements in light confinement and manipulation. In a recent study, PhPs in the monoclinic crystal β-Ga2O3 (bGO) were shown to exhibit strongly asymmetric propagation with a frequency dispersive optical axis. Here, using scanning near-field optical microscopy (s-SNOM), we directly image the symmetry-broken propagation of hyperbolic shear polaritons in bGO. Further, we demonstrate the control and enhancement of shear-induced propagation asymmetry by varying the incident laser orientation and polariton momentum using different sizes of nano-antennas. Finally, we observe significant rotation of the hyperbola axis by changing the frequency of incident light. Our findings lay the groundwork for the widespread utilization and implementation of polaritons in low-symmetry crystals.

Keywords: FEL; FELBE; s-SNOM; 2D Materials; THz; phonon polaritons; near-field; nanoscale

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Permalink: https://www.hzdr.de/publications/Publ-37379
Publ.-Id: 37379


Data publication: Validation experiments for gamma-ray densitometry uncertainty prediction algorithm in gas flow modulation

Marchini, S.; Bieberle, A.; Schubert, M.; Hampel, U.

The gas flow modulation technique is a recently proposed approach for measuring the axial gas dispersion coefficient in bubble columns. The approach uses a marginal sinusoidal distrubance on the gas inlet flow and relates the propagation of such disturbance in the column's axial direction to the axial gas dispersion coefficient. The approach requires to measure sinusoidally changing gas holdup in time with high accuracy. The presented data set was used to experimentally validate a newly developed simualtion algorithm for predicting the effect of various uncertainty sources on the measured holdup wave. The algorithm is able to predict the uncertianty related to the applycation of gamma-ray densitometry and of the data ensable-averaging approach. Experiments were preformed using an elliptical rotating disc able to mimik a controlled "material holdup wave", similar to the gas holdup wave measured in gas flow modulation.

Keywords: Gas flow modulation technique; axial dispersion coefficient; gamma-ray densitometry; uncertainty analysis

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Permalink: https://www.hzdr.de/publications/Publ-37377
Publ.-Id: 37377


Efficient ultrafast field-driven spin current generation for spintronic terahertz frequency conversion

Ilyakov, I.; Brataas, A.; de Oliveira, T.; Ponomaryov, O.; Deinert, J.-C.; Hellwig, O.; Faßbender, J.; Lindner, J.; Salikhov, R.; Kovalev, S.

Efficient generation and control of spin currents launched by terahertz (THz) radiation with subsequent ultrafast spin-to-charge conversion is the current challenge for the next-generation of high-speed communication and data processing units. Here, we demonstrate that THz light can efficiently drive coherent angular momentum transfer in nanometer-thick ferromagnet/heavy-metal heterostructures. This process is non-resonant and does neither require external magnetic fields nor cryogenics. The efficiency of this process is more than one order of magnitude higher as compared to the recently observed THz induced spin-pumping in MnF2 antiferromagnet. The coherently driven spin currents originate from the ultrafast spin Seebeck effect, caused by a THz-induced temperature imbalance in electronic and magnonic temperatures and fast relaxation of the electron-phonon system. Owing to the fact that the electron-phonon relaxation time is comparable with the period of a THz wave, the induced spin current results in THz second harmonic generation and THz optical rectification, providing a spintronic basis for THz frequency mixing and rectifying components.

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Permalink: https://www.hzdr.de/publications/Publ-37375
Publ.-Id: 37375


Double magnetic transitions and exotic field-induced phase in the triangular lattice antiferromagnets Sr3Co(Nb,Ta)2O9

Lal, S.; Sebastian, S. J.; Islam, S. S.; Saravanan, M. P.; Uhlarz, M.; Skourski, Y.; Nath, R.

Two triangular lattice antiferromagnets Sr3Co(Nb, Ta)2O9 with an effective jeff = 1/2 ofCo2+ are synthesized and their magnetic properties are investigated via magnetization and heat capacity measurements. The leading in-plane antiferromagnetic exchange coupling is estimated to be J/kB ≃ 4.7 and 5.8 K, respectively. Both compounds feature two-step magnetic transitions at low temperatures [(TN1 ≃ 1.47 K and TN2 ≃ 1.22 K) and (TN1 ≃ 0.88 K and TN2 ≃ 0.67 K), respectively], driven by weak easy-axis anisotropy. Under magnetic field, Sr3CoNb2O9 evinces a plateau at 1/3 magnetization. Interestingly, the high-field magnetization of Sr3CoTa2O9 reveals an exotic regime (between HS1 and HS2) below the fully polarized state in which the heat capacity at low temperatures is governed by a power law (Cp ∝ Tα) with a reduced exponent α ≃ 2. These results demonstrate an unusual field-induced state with gapless excitations in the strongly frustrated magnet Sr3CoTa2O9. The complete T -H phase diagram is discussed for both compounds.

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Permalink: https://www.hzdr.de/publications/Publ-37374
Publ.-Id: 37374


A universal route to efficient non-linear response via Thomson scattering in linear solids

Wen, Y.; Giorgianni, F.; Ilyakov, I.; Quan, B.; Kovalev, S.; Wang, C.; Vicario, C.; Deinert, J.-C.; Xiong, X.; Bailey, J.; Chen, M.; Ponomaryov, O.; Awari, N.; Rovere, A.; Sun, J.; Morandotti, R.; Razzari, L. F.; Aeppli, G.; Li, J.; Zhou, J.

Non-linear materials are cornerstones of modern optics and electronics. Strong dependence on the intrinsic properties of
particular materials, however, inhibits the at-will extension of demanding non-linear effects, especially those second-order
ones, to widely adopted centrosymmetric materials (for example, silicon) and technologically important burgeoning spectral
domains (for example, terahertz frequencies). Here we introduce a universal route to efficient non-linear responses enabled
by exciting non-linear Thomson scattering, a fundamental process in electrodynamics that was known to occur only in
relativistic electrons in metamaterial composed of linear materials. Such a mechanism modulates the trajectory of charges,
either intrinsically or extrinsically provided in solids, at twice the driving frequency, allowing second-harmonic generation at
terahertz frequencies on crystalline silicon with extremely large non-linear susceptibility in our proof-of-concept experiments.
By offering a substantially material-and frequency-independent platform, our approach opens new possibilities in the fields of
on-demand non-linear optics, terahertz sources, strong field light-solid interactions and integrated photonic circuits

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Permalink: https://www.hzdr.de/publications/Publ-37373
Publ.-Id: 37373


Optical Properties of MoSe2 Monolayer Implanted with Ultra-Low-Energy Cr Ions

Bui, M. N.; Rost, S.; Auge, M.; Zhou, L.; Friedrich, C.; Blügel, S.; Kretschmer, S.; Krasheninnikov, A.; Watanabe, K.; Taniguchi, T.; Hofsäss, H. C.; Grützmacher, D.; Kardynał, B. E.

This paper explores the optical properties of an exfoliated MoSe2 monolayer implanted with Cr + ions, accelerated to 25 eV. Photoluminescence of the implanted MoSe 2 reveals an emission line from Cr-related defects that is present only under weak electron doping. Unlike band-to-band transition, the Cr-introduced emission is characterized by nonzero activation energy, long lifetimes, and weak response to the magnetic field. To rationalize the experimental results and get insights into the atomic structure of the defects, we modeled the Cr-ion irradiation process using ab initio molecular dynamics simulations followed by the electronic structure calculations of the system with defects. The experimental and theoretical results suggest that the recombination of electrons on the acceptors, which could be introduced by the Cr implantation-induced defects, with the valence band holes is the most likely origin of the low-energy emission. Our results demonstrate the potential of low-energy ion implantation as a tool to tailor the properties of two-dimensional (2D) materials by doping.

Keywords: transition-metal dichalcogenide monolayer; ultra-low-energy ion implantation; MoSe2; van der Waals heterostructure; photoluminescence; molecular dynamics; density functional theory

Permalink: https://www.hzdr.de/publications/Publ-37372
Publ.-Id: 37372


Data publication: Design, Synthesis, and Biological Evaluation of Small Molecule Based Radioligands with Improved Pharmacokinetic Properties for Imaging of Programmed Death Ligand 1

Krutzek, F.; Donat, C.; Ullrich, M.; Stadlbauer, S.

Bei diesem Datensatz handelt es sich um die chemische Charakterisierung der Verbindungen, die in-vitro-, in-vivo- und ex-vivo-Daten.

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Permalink: https://www.hzdr.de/publications/Publ-37371
Publ.-Id: 37371


Radiomics predictive modeling from dual-time-point FDG PET Ki parametric maps: application to chemotherapy response in lymphoma

Samimi, R.; Shiri, I.; Ahmadyar, Y.; van den Hoff, J.; Kamali-Asl, A.; Rezaee, A.; Yousefirizi, F.; Geramifar, P.; Rahmim, A.

Background: To investigate the use of dynamic radiomics features derived from dual-time-point (DTP-feature) [18F]FDG PET metabolic uptake rate Ki parametric maps to develop a predictive model for response to chemotherapy in lymphoma patients. Methods: We analyzed 126 lesions from 45 lymphoma patients (responding n = 75 and non-responding n = 51) treated with chemotherapy from two different centers. Static and DTP radiomics features were extracted from baseline static PET images and DTP Ki parametric maps. Spearman’s rank correlations were calculated between static and DTP features to identify features with potential additional information. We first employed univariate analysis to determine correlations between individual features, and subsequently utilized multivariate analysis to derive predictive models utilizing DTP and static radiomics features before and after ComBat harmonization. For multivariate modeling, we utilized both the minimum redundancy maximum relevance feature selection technique and the XGBoost classifier. To evaluate our model, we partitioned the patient datasets into training/validation and testing sets using an 80/20% split. Different metrics for classification including area under the curve (AUC), sensitivity (SEN), specificity (SPE), and accuracy (ACC) were reported in test sets. Results: Via Spearman’s rank correlations, there was negligible to moderate correlation between 32 out of 65 DTP features and some static features (ρ < 0.7); all the other 33 features showed high correlations (ρ ≥ 0.7). In univariate modeling, no significant difference between AUC of DTP and static features was observed. GLRLM_RLNU from static features demonstrated a strong correlation (AUC = 0.75, p value = 0.0001, q value = 0.0007) with therapy response. The most predictive DTP features were GLCM_Energy, GLCM_Entropy, and Uniformity, each with AUC = 0.73, p value = 0.0001, and q value < 0.0005. In multivariate analysis, the mean ranges of AUCs increased following harmonization. Use of harmonization plus combining DTP and static features was shown to provide significantly improved predictions (AUC = 0.97 ± 0.02, accuracy = 0.89 ± 0.05, sensitivity = 0.92 ± 0.09, and specificity = 0.88 ± 0.05). All models depicted significant performance in terms of AUC, ACC, SEN, and SPE (p < 0.05, Mann–Whitney test). Conclusions: Our results demonstrate significant value in harmonization of radiomics features as well as combining DTP and static radiomics models for predicting response to chemotherapy in lymphoma patients. © 2023, The Author(s).

Keywords: Artificial intelligence; Dynamic PET; Engineered radiomics; Lymphoma; Predictive model; Radiomics

Permalink: https://www.hzdr.de/publications/Publ-37370
Publ.-Id: 37370


Data publication: Pulsating dissolution of crystalline matter: A transport- or surface-controlled process?

Schabernack, J.; Fischer, C.

KIMERA (Open Source KMC software):

  • Input file: kimera.input
  • Crystal structure: StructurePaperInna_noO.xyz
  • Output files: Calcite.box, Calcite.clayer, Calcite.data, Calcite.meandiscoord, Calcite.surface
  • KMC data evaluation file: KMC-KinkSites.xlsx

COMSOL:

  • COMSOL program files for two simulations: .mph files
     

Keywords: Surface reactivity; Pulsating dissolution; Kinetic Monte Carlo; Reactive transport; Calcite

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Permalink: https://www.hzdr.de/publications/Publ-37369
Publ.-Id: 37369


Data publication: STENCIL-NET for equation-free forecasting from data

Maddu, S.; Sturm, D.; Cheeseman, B. L.; Müller, C. L.; Sbalzarini, I. F.

Git repository for "STENCIL-NET for equation-free forecasting from data"

Keywords: data-driven modeling; stencil; neural network; forecasting; scientific computing

Related publications

  • Reseach data in external data repository
    Publication year 2023
    License: -
    Hosted on https://github.com/mosaic-group/STENCIL-NET: Link to location

Permalink: https://www.hzdr.de/publications/Publ-37367
Publ.-Id: 37367


STENCIL-NET for equation-free forecasting from data

Maddu, S.; Sturm, D.; Cheeseman, B. L.; Müller, C. L.; Sbalzarini, I. F.

We present an artificial neural network architecture, termed STENCIL-NET, for equation-free forecasting of spatiotemporal dynamics from data. STENCIL-NET works by learning a discrete propagator that is able to reproduce the spatiotemporal dynamics of the training data. This data-driven propagator can then be used to forecast or extrapolate dynamics without needing to know a governing equation. STENCIL-NET does not learn a governing equation, nor an approximation to the data themselves. It instead learns a discrete propagator that reproduces the data. It therefore generalizes well to different dynamics and different grid resolutions. By analogy with classic numerical methods, we show that the discrete forecasting operators learned by STENCIL-NET are numerically stable and accurate for data represented on regular Cartesian grids. A once-trained STENCIL-NET model can be used for equation-free forecasting on larger spatial domains and for longer times than it was trained for, as an autonomous predictor of chaotic dynamics, as a coarse-graining method, and as a data-adaptive de-noising method, as we illustrate in numerical experiments. In all tests, STENCIL-NET generalizes better and is computationally more efficient, both in training and inference, than neural network architectures based on local (CNN) or global (FNO) nonlinear convolutions.

Keywords: data-driven modeling; stencil; neural network; forecasting; scientific computing

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Permalink: https://www.hzdr.de/publications/Publ-37366
Publ.-Id: 37366


Design, Synthesis, and Biological Evaluation of Small Molecule Based Radioligands with Improved Pharmacokinetic Properties for Imaging of Programmed Death Ligand 1

Krutzek, F.; Donat, C.; Ullrich, M.; Stadlbauer, S.

Small molecules offer some advantages for developing PET tracers and are therefore a promising approach for imaging and therapy monitoring of PD-L1 positive tumors. Here, we report six biphenyl PD-L1 radioligands, using the NODA-GA-chelator for efficient copper-64 complexation. These radioligands contain varying numbers of sulfonic and/or phosphon-ic acid groups, serving as hydrophilizing units to lower the log D7.4 value down to –4.28. Binding affinities of compounds were evaluated using saturation binding and a real-time binding assay, with lowest binding affinity of 21 nM. Small ani-mal PET imaging revealed vastly different pharmacokinetic profiles, depending on the quantity and type of hydrophiliz-ing units. Of the investigated radioligands, [64Cu]Cu-3 showed the most favorable kinetics in vitro. This was also found in vivo, with a predominantly renal clearance and a specific uptake in the PD-L1-positive tumor. With further modifications, this compound could be a promising candidate for imaging of PD-L1 in the clinical setting.

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Permalink: https://www.hzdr.de/publications/Publ-37365
Publ.-Id: 37365


Raw data related to publication "Influence of engineered roughness microstructures on adhesion and turbulent resuspension of microparticles" by Banari et al. (2023)

Lecrivain, G.
ContactPerson: Lecrivain, Gregory

#Folder "Adhesion": Contains all raw data related to the adhesion force measurement. To plot the figure, run python3. plot.py

#Folder "SEM": each subfolder S1, S2 and S3 contains further high-resolution pictures taken with the SEM

#Folder "WindChannel": Contains all raw data related to the resuspensiob experiment performed in the winf channel. More Info in Windchannel/Readme.txt

Keywords: Particle resuspension; Turbulent gas flow; Aerosol transport

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Permalink: https://www.hzdr.de/publications/Publ-37363
Publ.-Id: 37363


Knowledge Graph Development as a Collaborative Process

Steinmeier, L.; van den Boogaart, K. G.; Schaller, T.

Establishing semantic data and knowledge graphs in scientific working groups is no easy feat. In most cases there is neither a user friendly tool chain nor experience with ontologies for the respective research field. But without a start, said experience can never be gained. The same is true for individuals that want to start into the field.

We thus see knowledge graph development not as a task of expert individuals that already know everything, but as a collaborative (learning) process of working groups and organisations. At the start of this process the right ontologies are not known and the individuals do not yet have experience with expressing information in knowledge graphs. Thus, a tool chain must provide basic knowledge to help newcomers to get started. It must also support the learning process and the selection of terms and ontologies, while users are already working with their own data and metadata. Additionally, the tool chain must support cooperation and lateral transfer of knowledge within organisations and working groups as well as between working groups world wide.

We therefore propose to establish a data infrastructure in every research organisation consisting of the following elements: An organisational knowledge graph, integration of (global) ID services, links to FAIR ontologies, policies, and a graph editing tool. This editing tool must support simultaneously the input of graph data, the extension of ontologies, the development of data structures, and finding and reusing existing ontologies and data structures not only from other persons inside the organisation but also from globally emerging metadata standards. While searching for a fitting term from a predefined set of ontologies, the tool would also allow for the creation of an internal term, when no fitting one is found. While trying to create a new term, fitting ones are automatically searched and proposed. The here proposed graph editing tool would provide the possibility to refactor existing data to newly selected ontologies, e.g. through replacing terms or whole structures, while keeping the original history in a git+GitLab like structure. This would also allow for access control and cooperation within the organisation and beyond. Such refactoring translations would also be described in terms of graph data and be published, so that others considering the same transition could use them without much effort.

We think that in the presented infrastructure users could establish processes that would foster harmonization and convergence of ontologies and data structures, while not impeding the collection of data and learning processes of individuals before harmonization is achieved.

Keywords: knowledge graph; collaborative data development; metadata harmonization; research data interoperability

  • Lecture (Conference) (Online presentation)
    HMC Conference 2023, 10.-12.10.2023, online, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37362
Publ.-Id: 37362


Hydrogen Transport Between Layers of Transition Metal-Dichalcogenides

Eren, I.; Yun, A.; Kuc, A. B.

Hydrogen is a crucial source of green energy and has been extensively studied for its potential usage in fuel cells. The advent of two-dimensional crystals (2DCs) has taken hydrogen research to new heights, enabling it to tunnel through layers of 2DCs or be transported within voids between the layers, as demonstrated in recent experiments by Geim’s group. In this study, we investigate how the composition and stacking of transition-metal dichalcogenide (TMDC) layers influence the transport and self-diffusion coefficients (D) of hydrogen atoms using well-tempered metadynamics simulations. Our findings show that modifying either the transition metal or the chalcogen atoms significantly affects the free energy barriers (ΔF) and, consequently, the self-diffusion of hydrogen atoms between the 2DC layers. In the Hhh polytype (2H stacking), MoSe2 exhibits the lowest ΔF, while WS2 has the highest, resulting in the largest D for the former system. Additionally, hydrogen atoms inside the RMh (or 3R) polytype encounter more than twice lower energy barriers and, thus, much higher diffusivity compared to those within the most stable Hhh stacking. These findings are particularly significant when investigating twisted layers or homo- or heterostructures, as different stacking areas may dominate over others, potentially leading to directional transport and interesting materials for ion or atom sieving.

Keywords: hydrogen transport; two-dimensional materials; transition-metal dichalcogenides; well-tempered metadynamics simulations; self-diffusion coefficients

Permalink: https://www.hzdr.de/publications/Publ-37361
Publ.-Id: 37361


supplementary material for bubble trajectories

Shi, P.; Tholan, V.; Sommer, A.-E.; Heitkam, S.; Eckert, K.; Kevin, G.; Rzehak, R.

supplementary material for bubble trajectories

Keywords: spherical bubble; inclined channel; drag force; lift force; wake bending

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Permalink: https://www.hzdr.de/publications/Publ-37360
Publ.-Id: 37360


Forces on a nearly spherical bubble rising in an inclined channel flow

Shi, P.; Tholan, V.; Sommer, A.-E.; Heitkam, S.; Eckert, K.; Kevin, G.; Rzehak, R.

The dynamics of a sub-millimeter air bubble rising at a bubble Reynolds number of about 100 in water in an inclined, laminar channel flow is investigated experimentally. In this configuration which is relevant in modern separation technologies for valuable particles, the bubble is undergoing a cross-stream motion, as the buoyancy force is not aligned with the undisturbed liquid flow. From measurements of bubble velocities and trajectories we estimate the drag and lift forces on the bubble at two different channel Reynolds numbers. The results are compared with their streamwise counterparts, i.e. in the configuration where the bubble rises largely along a streamline of the undisturbed liquid flow. For the lower channel Reynolds number, the cross-stream effects are only small. For the larger channel Reynolds number however, the drag coefficient is found to be notably larger than its streamwise counterpart. The lift coefficient may be either larger or smaller than its streamwise counterpart depending on the detailed local flow conditions. In particular, its value is non-zero when the bubble crosses the channel centerline where the shear rate is zero. These deviations are found to be closely connected with the bending of the bubble wake as well as the finite value of the angle formed between the bubble slip velocity and the velocity of the liquid flow.

Keywords: spherical bubble; inclined channel; drag force; lift force; wake bending

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  • Secondary publication expected from 23.09.2024

Permalink: https://www.hzdr.de/publications/Publ-37359
Publ.-Id: 37359


Data publication: All-electrical operation of a Curie switch at room temperature

Iurchuk, V.; Kozlov, O.; Sorokin, S.; Zhou, S.; Lindner, J.; Reshetniak, S.; Kravets, A.; Polishchuk, D.; Korenivski, V.

This dataset contains the experimental and analytical data used and discussed in the publication "All-Electrical Operation of a Curie Switch at Room Temperature" (Phys. Rev. Applied 20, 024009 – Published 3 August 2023).

Keywords: Magnetoresistance; Magnetic hysteresis; Vibrating sample magnetometry; Spin valve; Thermomagnetic effects; RKKY interaction

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Permalink: https://www.hzdr.de/publications/Publ-37358
Publ.-Id: 37358


Overarching Data Management Ecosystem at HZDR

Knodel, O.; Gruber, T.; Kelling, J.; Lokamani, M.; Müller, S.; Pape, D.; Voigt, M.; Juckeland, G.

When dealing with research data management, researchers at Helmholtz-
Zentrum Dresden – Rossendorf (HZDR) face a variety of systems and tools. These
range from the project planning phase (proposal management, data management plans
and policies), over documentation during the experiment or simulation campaign, to the
publication (collaborative authoring tools, metadata catalogs, publication systems, data
repositories). In addition, modern research projects usually are required to interact with
a variety of software stacks and workflow management systems to allow comprehensi-
ble and FAIR science on the underlying IT infrastructure (HPC, data storage, network
file systems, archival). This article first demonstrates the data management systems
and services provided at HZDR, followed by an overview of a self-developed guidance
system. It is concluded by a real-world example.

Keywords: research data management; data life cycle; workflows; metadata; FAIR; data provenance; HELIPORT

  • Open Access Logo Contribution to proceedings
    1st Conference on Research Data Infrastructure, 12.-14.09.2023, Karlsruhe, Deutschland
    Proceedings of the 1st Conference on Research Data Infrastructure, Hannover: TIB Open Publishing
    DOI: 10.52825/CoRDI.v1i.277
    ISSN: 2941-296X

Permalink: https://www.hzdr.de/publications/Publ-37357
Publ.-Id: 37357


Two-Step Approach in Metadata Management for Data Publications at Research Centres

Gruber, T.; Schlenvoigt, H.-P.; Knodel, O.; Tippey, K. E.; Juckeland, G.

Data repositories like Zenodo have a limited list of metadata to search for. Metadata catalogues are designed to provide a community-specific parameters search, but their deployment has just started. These catalogues require metadata standards for interoperability, which in turn are often in development for many communities. To support publications with a metadata standard in the future, a two-step concept is presented in this article. It discusses how the electronic documentation should be constructed, in order to convert this later into a standardised schema for publication. We will present examples from the laser-plasma community for both steps, firstly how we deal with the complex challenges of metadata management and secondly for methods for developing metadata schemas.

Keywords: Data Management; Workflows; Metadata; Data Provenance

  • Open Access Logo Contribution to proceedings
    1st Conference on Research Data Infrastructure, 12.-14.09.2023, Karlsruhe, Deutschland
    Proceedings of the Conference on Research Data Infrastructure, Hannover: TIB Open Publishing
    DOI: 10.52825/cordi.v1i.377

Permalink: https://www.hzdr.de/publications/Publ-37356
Publ.-Id: 37356


Data-Driven Research for the Discovery of Novel Two-Dimensional and Ionic Materials

Friedrich, R.

While two-dimensional (2D) materials are traditionally derived from bulk layered
compounds bonded by weak van der Waals (vdW) forces, the recent surprising
experimental realization of non-vdW 2D compounds obtained from non-layered
crystals [1] foreshadows a new direction in 2D systems research.
Here, several dozens of candidates of this novel materials class are presented derived
from filtering the AFLOW materials database (see Fig. 1) in conjunction with
autonomous ab initio calculations [2,3]. The oxidation state of the surface cations of
the 2D sheets is an enabling descriptor regarding the manufacturing of these systems
as it determines their exfoliation energy: small oxidation states promote easy peel off
[2]. When extending the set from oxides to sulfides and chlorides, the exfoliation
energy becomes ultra low due to strong surface relaxations [3]. The candidates exhibit
a wide range of appealing electronic, optical and magnetic properties making these
systems an attractive platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[3] T. Barnowsky et al., Adv. El. Mats., in press (2023).

Related publications

  • Invited lecture (Conferences)
    Invited talk at BTU Cottbus-Senftenberg, 20.01.2023, Cottbus, BRD

Permalink: https://www.hzdr.de/publications/Publ-37355
Publ.-Id: 37355


Discovering Two-Dimensional Non-van der Waals Materials by Data-driven Research

Friedrich, R.

While two-dimensional (2D) materials are traditionally associated with bulk layered
compounds bonded by weak van der Waals (vdW) interactions, the recent surprising
experimental realization of non-vdW 2D systems obtained from non-layered crystals [1,2]
opens up a new direction. These materials show several distinct differences to traditional
2D sheets as their surface was revealed to be terminated by cations rather than anions.
Here, we outline several dozens of candidates of this novel materials class derived from
employing data-driven research principles in conjunction with autonomous ab initio
calculations [3,4] (Figure 1). The oxidation state of the surface cations of the 2D sheets
turns out to be an enabling descriptor regarding the manufacturing of these systems as
it determines their exfoliation energy: small oxidation states promote easy peel off [3].
When extending the set from oxides to sulfides and chlorides, the exfoliation energy
becomes ultra low due to strong surface relaxations [4]. The candidates exhibit a wide
range of appealing electronic, optical and in particular magnetic properties making these
systems an attractive platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] A. Puthirath Balan et al., Chem. Mater. 30, 5923 (2018).
[3] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[4] T. Barnowsky et al., Adv. Electron. Mater. 9, 2201112 (2023).

Related publications

  • Invited lecture (Conferences)
    2nd China-Germany bilateral meeting on topological devices, 2D materials and the future of spintronics, 03.-04.08.2023, Mainz, BRD

Permalink: https://www.hzdr.de/publications/Publ-37354
Publ.-Id: 37354


Data-Driven Research for the Discovery of Novel Two-Dimensional and Ionic Material

Friedrich, R.

Data-Driven Research for the Discovery of Novel Two-Dimensional and Ionic Material

Related publications

  • Invited lecture (Conferences)
    Retreat of the Felser Department of the Max Planck Institute for the Chemical Physics of Solids, 11.-13.01.2023, Bad Schandau, BRD

Permalink: https://www.hzdr.de/publications/Publ-37353
Publ.-Id: 37353


Two-Dimensional Non-van der Waals Materials from Data-Driven Research

Friedrich, R.; Barnowsky, T.; Ghorbani-Asl, M.; Curtarolo, S.; Krasheninnikov, A. V.

While two-dimensional (2D) materials are traditionally derived from
bulk layered compounds bonded by weak van der Waals (vdW) forces,
the recent surprising experimental realization of non-vdW 2D compounds
obtained from non-layered crystals [1] foreshadows a new direction
in 2D systems research.
Here, we present several dozens of candidates of this novel materials
class derived from applying data-driven research methodologies
in conjunction with autonomous ab initio calculations [2,3]. We find
that the oxidation state of the surface cations of the 2D sheets is an
enabling descriptor regarding the manufacturing of these systems as
it determines their exfoliation energy: small oxidation states promote
easy peel off [2]. When extending the set from oxides to sulfides and
chlorides, the exfoliation energy becomes ultra low due to strong surface
relaxations [3]. The candidates exhibit a wide range of appealing
electronic, optical and magnetic properties making these systems an
attractive platform for fundamental and applied nanoscience.
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13, 602 (2018).
[2] R. Friedrich et al., Nano Lett. 22, 989 (2022).
[3] T. Barnowsky et al., submitted (2022).

Related publications

  • Lecture (Conference)
    DPG Spring Meeting of the Condensed Matter Section (SKM) 2023, 26.-31.03.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37352
Publ.-Id: 37352


Efficient workflow for treating thermal and zero-point contributions to formation enthalpies

Friedrich, R.; Esters, M.; Oses, C.; Ki, S.; Brenner, M. J.; Hicks, D.; Mehl, M. J.; Toher, C.; Curtarolo, S.

The formation enthalpy, quantifying the enthalpy of a compound with
respect to its elemental references, is a key parameter for predicting the
thermodynamic stability of materials thus enabling data-driven materials
design. Although for instance zero-point vibrational and thermal
contributions to the formation enthalpy can be quite substantial reaching
absolute values of up to ∼ 50 meV/atom for ionic systems such as
oxides, they are often neglected in ab initio workflows.
Here, we first calculate the thermal and zero-point contributions accurately
from a quasi-harmonic Debye model. At room temperature,
they largely cancel each other due to the different bond stiffness of
compound and references reducing the total vibrational contribution
to maximally ∼ 20 meV/atom [1]. Moreover, the vibrational contributions
can be parametrized within the coordination corrected enthalpies
(CCE) method completely eliminating the need to compute
these terms explicitly. On this basis, using only 0 K ab initio data
as input, a workflow can be designed providing access to formation
enthalpies at different temperatures from the AFLOW-CCE tool [2].
[1] R. Friedrich et al., npj Comput. Mater. 5, 59 (2019).
[2] R. Friedrich et al., Phys. Rev. Mater. 5, 043803 (2021).

Related publications

  • Lecture (Conference)
    DPG Spring Meeting of the Condensed Matter Section (SKM) 2023, 26.-31.03.2023, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-37351
Publ.-Id: 37351


Discovering Two-Dimensional Non-van der Waals Materials

Friedrich, R.; Barnowsky, T.; Ghorbani-Asl, M.; Curtarolo, S.; Krasheninnikov, A. V.

While two-dimensional (2D) materials are traditionally associated with bulk layered compounds
bonded by weak van der Waals (vdW) interactions, the recent surprising experimental realization of
non-vdW 2D compounds obtained from non-layered crystals [1,2] opens up a new direction in 2D
systems research. These materials show several distinct differences to traditional 2D sheets as their
surface was revealed to be terminated by cations rather than anions. Here, we outline several
dozens of candidates of this novel materials class derived from employing data-driven research
principles in conjunction with autonomous ab initio calculations [3,4] (Figure 1). The oxidation state
of the surface cations of the 2D sheets turns out to be an enabling descriptor regarding the
manufacturing of these systems as it determines their exfoliation energy: small oxidation states
promote easy peel off [3]. When extending the set from oxides to sulfides and chlorides, the
exfoliation energy becomes ultra low due to strong surface relaxations [4]. The materials also pass
several tests validating their vibrational and dynamic stability. The candidates exhibit a wide range of
appealing electronic, optical and in particular magnetic properties making these systems an
attractive platform for fundamental and applied nanoscience.
References
[1] A. Puthirath Balan et al., Nat. Nanotechnol. 13 (2018) 602.
[2] A. Puthirath Balan et al., Chem. Mater. 30 (2018) 5923.
[3] R. Friedrich et al., Nano Lett. 22 (2022) 989.
[4] T. Barnowsky et al., Adv. Electron. Mater. (2023) 2201112.

Related publications

  • Lecture (Conference)
    chem2Dmat, 15.-18.05.2023, Bologna, Italien

Permalink: https://www.hzdr.de/publications/Publ-37350
Publ.-Id: 37350


Phenotype-preserving metric design for high-content image reconstruction by generative inpainting

Sharma, V.; Yakimovich, A.

In the past decades, automated high-content microscopy demonstrated its ability to deliver large quantities of image-based data powering the versatility of phenotypic drug screening and systems biology applications. However, as the sizes of image-based datasets grew, it became infeasible for humans to control, avoid and overcome the presence of imaging and sample preparation artefacts in the images. While novel techniques like machine learning and deep learning may address these shortcomings through generative image inpainting, when applied to sensitive research data this may come at the cost of undesired image manipulation. Undesired manipulation may be caused by phenomena such as neural hallucinations, to which some artificial neural networks are prone. To address this, here we evaluate the state-of-the-art inpainting methods for image restoration in a high-content fluorescence microscopy dataset of cultured cells with labelled nuclei. We show that architectures like DeepFill V2 and Edge Connect can faithfully restore microscopy images upon fine-tuning with relatively little data. Our results demonstrate that the area of the region to be restored is of higher importance than shape. Furthermore, to control for the quality of restoration, we propose a novel phenotype-preserving metric design strategy. In this strategy, the size and count of the restored biological phenotypes like cell nuclei are quantified to penalise undesirable manipulation. We argue that the design principles of our approach may also generalise to other applications.

Keywords: Deep Learning; Generative Inpainting; Computer Vision; Fluorescence Microscopy; Sample Preparation Artefacts; Image Reconstruction; Metric

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Permalink: https://www.hzdr.de/publications/Publ-37349
Publ.-Id: 37349


Data publication: A weak-labelling and deep learning approach for in-focus object segmentation in 3D widefield microscopy

Li, R.; Kudryashev, M.; Yakimovich, A.

D. rerio 3D microscopy and in-focus pixel segmentation.

Keywords: weak-labeling; deep neural network; widefield microscopy; surrogate model

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Permalink: https://www.hzdr.de/publications/Publ-37348
Publ.-Id: 37348


Analysis of loss of flow without scram test in the FFTF reactor – Part II: System thermal hydraulics with point neutron kinetics

Ponomarev, A.; Nikitin, E.; Fridman, E.

This study presents a benchmark analysis of an unprotected loss of flow transient in a sodium-cooled fast reactor at the Fast Flux Test Facility (FFTF), carried out as part of an IAEA coordinated research project. Three codes, namely Serpent (Monte Carlo), DYN3D (3D nodal diffusion) and ATHLET (system thermal hydraulics), were employed in the benchmark exercise. Two distinct modeling approaches were utilized: 1) stand-alone ATHLET with point kinetics (PK) and system thermal hydraulics (TH); and 2) coupled DYN3D/ATHLET with spatial kinetics (SK) and system TH. Neutronics data essential for both approaches were generated using Serpent. The study is organized into three parts.

Part I presented a summary of the preparation of neutronics data for PK or coupled SK/TH simulations and included the outcomes of the static neutronics stage of the benchmark. The main focus lay on verifying the cross-section generation method for DYN3D by comparing its results against the reference Monte Carlo solutions obtained with Serpent.

Part II provides a detailed description of the ATHLET TH model of the system. This model is thoroughly evaluated by comparing the results with the ANL benchmark solution and experimental data for the transient. Furthermore, a sensitivity analysis is conducted to explore various modeling options and assess their impact on the simulation results.

Part III will showcase the transient calculation results using the two modeling approaches. Additionally, an adaptive decay heat model for nodal codes will be introduced. The performance of both modeling approaches will be assessed by comparing their results to the available experimental data.

Keywords: ATHLET; FFTF; Gas Expansion Module; loss of flow; point kinetics; SFR; unprotected transient

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Permalink: https://www.hzdr.de/publications/Publ-37346
Publ.-Id: 37346


Analysis of loss of flow without scram test in the FFTF reactor – Part I: preparation of neutronics data

Nikitin, E.; Fridman, E.; Ponomarev, A.

This study presents a benchmark analysis of an unprotected loss of flow transient in a sodium-cooled fast reactor at the Fast Flux Test Facility (FFTF), carried out as part of an IAEA coordinate research project. Three codes, namely Serpent (Monte Carlo), DYN3D (3D nodal diffusion) and ATHLET (system thermal hydraulics), were employed in the benchmark exercise. Two distinct modeling approaches were utilized: 1) stand-alone ATHLET with point kinetics (PK) and system thermal hydraulics (TH); and 2) coupled DYN3D/ATHLET with spatial kinetics (SK) and system TH. Neutronics data essential for both approaches were generated using Serpent. The study is organized into three parts.

Part I presents a summary of the preparation of neutronics data for PK or coupled SK/TH simulations and includes the outcomes of the static neutronics stage of the benchmark. The main focus lies on verifying the cross-section generation method for DYN3D by comparing its results against the reference Monte Carlo solutions obtained with Serpent.

Part II will provide a detailed description of the ATHLET TH model of the system. This model will be thoroughly evaluated by comparing the results with the ANL benchmark solution and experimental data for the transient. Furthermore, a sensitivity analysis will be conducted to explore various modeling options and assess their impact on the simulation results.

Part III will showcase the transient calculation results using the two modeling approaches. Additionally, an adaptive decay heat model for nodal codes will be introduced. The performance of both modeling approaches will be assessed by comparing their results to the available experimental data.

Keywords: SFR; Serpent; DYN3D; neutronics benchmark; homogenized cross section

Related publications

Permalink: https://www.hzdr.de/publications/Publ-37345
Publ.-Id: 37345


Variational Formulations for Solving PDEs with Non-Smooth Solutions using Non-Linear Surrogates

Suarez Cardona, J. E.

This talk intends to address the challenge of solving Partial Differential Equations (PDEs) with smooth
or non-smooth solutions by formulating variational PDE formulations resulting in a soft-constrained
optimization problem. The flexibility of the variational formulation enables us to use hybrid non-linear
surrogates to approximate discontinuous shocks while solving forward or inverse PDE problems. We
first explore general concepts and tools necessary for solving PDEs under a variational formulation with
general non-linear surrogates and boundary conditions. We then compare the numerical performance of
Physics Informed Neural Networks (PINNs) as surrogates against Polynomial Surrogate Models (PSMs).
Our goal is to open up the discussion regarding the class of problems that genuinely require the use of
Neural Networks. Our findings indicate that PSMs outperform PINNs by several orders of magnitude in
both accuracy and runtime. Furthermore, we introduce a new method for approximating discontinuous
functions using modified global spectral methods. We extend this method to solve PDEs with nonsmooth
solutions, providing an innovative solution to a highly challenging problem.

  • Open Access Logo Poster
    NoLineal 2023, 26.06.2023, Barcelona, Spain

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Permalink: https://www.hzdr.de/publications/Publ-37344
Publ.-Id: 37344


High-field EPR of copper(II)–nitroxide compound exhibiting three-step phase transition: structural insights from the field-induced sample orientation

Tumanov, S. V.; Ponomaryov, O.; Maryunina, K. Y.; Bogomyakov, A. S.; Ovcharenko, V. I.; Zvyagin, S.; Fedin, M. V.; Veber, S. L.

Copper(II)–nitroxide based Cu(hfac)2LR compounds exhibit unusual magnetic behavior that can be induced by various stimuli. In many aspects, the magnetic phenomena observed in Cu(hfac)2LR are similar to classical spin-crossover behavior. However, these phenomena originate from polynuclear exchangecoupled spin clusters Cu2+–O–N< or >N–O–Cu2+–O–N<. Such peculiarities may result in additional multifunctionality of Cu(hfac)2LR compounds, making them promising materials for spintronic applications. Herein, we investigate the Cu(hfac)2LMeMe material, which demonstrates a three-step temperature-induced magnetostructural transition between high-temperature, low-temperature, and intermediate states, as revealed by magnetometry. Two main steps were resolved using variable-temperature Fourier-transform infrared and Q-band electron paramagnetic resonance (EPR) spectroscopies. The intermediate-temperature states (∼40–90 K) are characterized by the coexistence of two types of copper(II)–nitroxide clusters, corresponding to the low-temperature and high-temperature phases. High-field EPR experiments revealed the effect of partial alignment of Cu(hfac)2LMeMe microcrystals in a strong (>20 T) magnetic field. This effect was used to unveil the structural features of the low-temperature phase of Cu(hfac)2LMeMe, which were inaccessible using single-crystal X-ray diffraction (XRD) technique. In particular, high-field EPR allowed us to determine the relative direction of the Jahn–Teller axes in CuO6 and CuO4N2 units.

Permalink: https://www.hzdr.de/publications/Publ-37342
Publ.-Id: 37342


Non-axisymmetric standard magnetorotational instability in the upcoming DRESDYN-MRI experiments -- linear and nonlinear dynamics

Mishra, A.; Mamatsashvili, G.; Stefani, F.

Magnetorotational instability (MRI) is the most likely mechanism for efficient transport of angular momentum in accretion disks. However, despite numerous efforts, the quest for an unambiguous realization of MRI in experiments is still ongoing. To conclusively identify MRI in the laboratory, a large Taylor-Couette experiment with liquid sodium is under construction at the Helmholtz-Zentrum Dresden-Rossendorf within the DRESDYN project. Recently, we have determined the optimal range of parameters for the onset of an axisymmetric mode of the standard MRI (SMRI) with a purely axial background magnetic field and analyzed its nonlinear evolution, saturation and scaling properties in the context of the DRESDYN-MRI experiment. In this sequel paper, we continue SMRI studies and investigate the linear and nonlinear dynamics of non-axisymmetric modes of the instability in a similar magnetized Taylor-Couette setup. For the linear stability analysis, we use $Pm=\nu/\eta \sim 10^{-5}$ typical of liquid sodium used in the experiment. We show that the achievable magnetic Reynolds $Rm\sim 40$ and Lundquist $Lu\sim10$ numbers in this experiment are large enough for the growth of non-axisymmetric $|m|=1$ SMRI modes. For fixed $\mu$, the critical $Rm_c$ for the onset of non-axisymmetric SMRI is about 2-3 time higher than that of axisymmetric SMRI. We follow the evolution of these modes from their exponential growth in the linear regime all over to nonlinear saturation. The structure of the saturated state and its scaling properties with respect to Reynolds number $Re$ are analyzed, which is relevant and important for the DRESDYN-MRI experiment having very high Reynolds numbers ($\sim 10^6$). We show that for $Re \lesssim 10^4$, the magnetic energy of non-axisymmetric SMRI modes does not saturate and eventually decays due to the modification of the radial shear profile of the mean azimuthal velocity by the nonlinear axisymmetric SMRI, that is, the modified shear profile appears to be stable against non-axisymmetric modes. By contrast, for large $Re \gtrsim 10^4$, a sudden rapid growth and saturation of the magnetic energy of non-axisymmetric modes occur, which are radially localized in the turbulent boundary layer near the inner cylinder wall. The saturation amplitude of the non-axisymmetric modes is always a few orders smaller than that of the axisymmetric SMRI mode. We further show that the scaling relations for magnetic energy and torque in the saturated state of SMRI derived for axisymmetric modes in our previous study well carry over to $|m|\geq 1$ non-axisymmetric ones.

Keywords: Taylor-Couette system; Astrophysical fluid dynamics; Flow instability; Magnetohydrodynamic turbulence; Magnetohydrodynamics; Nonlinear dynamics in fluids; Shear flows; Turbulence

Permalink: https://www.hzdr.de/publications/Publ-37341
Publ.-Id: 37341


Synthesis of Single Crystals of ε-Iron and Direct Measurements of Its Elastic Constants

Dewaele, A.; Amadon, B.; Bosak, A.; Svitlyk, V.; Occelli, F.

Seismology finds that Earth’s solid inner core behaves anisotropically. Interpretation of this requires a knowledge of crystalline elastic anisotropy of its constituents—the major phase being most likely ε-Fe, stable only under high pressure. Here, single crystals of this phase are synthesized, and its full elasticity tensor is measured between 15 and 33 GPa at 300 K. It is calculated under the same conditions, using the combination of density functional theory and dynamical mean field theory, which describes explicitly electronic correlation effects. The predictive power of this scheme is checked by comparison with measurements; it is then used to evaluate the crystalline anisotropy in ε-Fe under higher density. This anisotropy remains of the same amplitude up to densities typical of Earth’s inner core.

Permalink: https://www.hzdr.de/publications/Publ-37340
Publ.-Id: 37340


A comprehensive review of numerical and experimental research on the thermal-hydraulics of two-phase flows in vertical rod bundles

Tas-Köhler, S.

Thermal-hydraulic analysis of two-phase flow plays a crucial role in the optimal design of nuclear fuel assemblies and in nuclear safety. This paper presents the state of the art in two-phase flow hydrodynamics and heat transfer in nuclear fuel assemblies. A comprehensive review of experimental and CFD methods used in the last 30 years to analyse the thermal-hydraulic characteristics of sub-channels in rod bundle geometries under different flow conditions (adiabatic and boiling two-phase flow) is presented. The effects of design parameters, e.g. rod-pitch length, mixing vane angle, and flow parameters, e.g. pressure, mass flux and heat flux, on flow hydrodynamics and heat transfer performance are summarized. In addition, the capabilities of CFD modelling of two-phase in rod bundles are discussed. Moreover, based on the existing studies, some recommendations for future studies are given.

Keywords: Rod bundle; CFD; Experimental study; Two-phase flow; Flow hydrodynamics; Heat transfer

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Permalink: https://www.hzdr.de/publications/Publ-37339
Publ.-Id: 37339


Ultra-short pulse laser acceleration of protons to 80 MeV from cryogenic hydrogen jets tailored to near-critical density

Rehwald, M.; Assenbaum, S.; Bernert, C.; Brack, F.-E.; Bussmann, M.; Cowan, T.; Curry, C. B.; Fiuza, F.; Garten, M.; Gaus, L.; Gauthier, M.; Göde, S.; Göthel, I.; Glenzer, S. H.; Huang, L.; Huebl, A.; Kim, J. B.; Kluge, T.; Kraft, S.; Kroll, F.; Metzkes-Ng, J.; Miethlinger, T.; Löser, M.; Obst-Huebl, L.; Reimold, M.; Schlenvoigt, H.-P.; Schoenwaelder, C.; Schramm, U.; Siebold, M.; Treffert, F.; Yang, L.; Ziegler, T.; Zeil, K.

Laser plasma-based particle accelerators attract great interest in fields where conventional accelerators reach limits based on size, cost or beam parameters. Despite the fact that particle in cell simulations have predicted several advantageous ion acceleration schemes, laser accelerators have not yet reached their full potential in producing simultaneous high-radiation doses at high particle energies. The most stringent limitation is the lack of a suitable high-repetition rate target that also provides a high degree of control of the plasma conditions required to access these advanced regimes. Here, we demonstrate that the interaction of petawatt-class laser pulses with a pre-formed micrometer-sized cryogenic hydrogen jet plasma overcomes these limitations enabling tailored density scans from the solid to the underdense regime. Our proof-of-concept experiment demonstrates that the near-critical plasma density profile produces proton energies of up to 80 MeV. Based on hydrodynamic and three-dimensional particle in cell simulations, transition between different acceleration schemes are shown, suggesting enhanced proton acceleration at the relativistic transparency front for the optimal case.

Keywords: Laser-produced plasmas; Plasma-based accelerators; Laser proton acceleration

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Permalink: https://www.hzdr.de/publications/Publ-37338
Publ.-Id: 37338


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