Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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41396 Publications

MHT-X: Offline Multiple Hypothesis Tracking with Algorithm X

Zvejnieks, P.; Birjukovs, M.; Klevs, M.; Akashi, M.; Eckert, S.; Jakovics, A.

An efficient and versatile implementation of offline multiple hypothesis tracking with Algorithm X for optimal association search was developed using Python. The code is intended for scientific applications that do not require online processing. Directed graph framework is used and multiple scans with progressively increasing time window width are used for edge construction for maximum likelihood trajectories. The current version of the code was developed for applications in multi-phase hydrodynamics, e.g. bubble and particle
tracking, and is capable of resolving object motion, merges and splits. Feasible object associations and trajectory graph edge likelihoods are determined using weak mass and momentum conservation laws translated to statistical functions for object properties. The code is compatible with n-dimensional motion with arbitrarily many tracked object properties. This framework is easily extendable beyond the present application by replacing the currently used heuristics with ones more appropriate for the problem at hand. The code is open-source and will be continuously developed further.

Keywords: Algorithm X; two-phase flow; bubble dynamics; liquid metal; X-ray radiography; neutron imaging; image processing

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Permalink: https://www.hzdr.de/publications/Publ-32494
Publ.-Id: 32494


Ion beam joining of ceramic and carbon-based nanostructures

Das, P.; Möller, W.; Elliman, R. G.; Chatterjee, S.

Ion beam assisted joining of nanostructured materials is a relatively new field. In particular, ion beam technique
has been proven to be worthwhile for joining ceramic nanostructures. However, a large scope is still remaining to
study heterojunctions between two dissimilar materials as the process of formation of bonds between two dis
similar
materials is still to be understood. In this work we pick up a ceramic oxide and carbon based material to
study ion beam joining. Specifically, we for the first time show heterojunction formation between hydrogen
titanate nanowire (HTNW) and carbon nanotube (CNT) by the low energy ion beam. In order to understand the
mechanism, we have invoked density functional theory and three-dimensional ion–solid interaction simulations.
Experimental results are supported by predictions of simulations and suggest that the joining is established
through ion beam mixing, surface defects and sputter redeposition at the junction points. The current study
enlightens how the defects and sputtered out atoms are involved in the joining process. The chemical bonds
between HTNW and CNT are formed only when C vacancy and simultaneously non-lattice O and C were pro
duced
during irradiation. The effect of joining on electrical conductivity and surface wetting has also been
studied experimentally in this work, which is supported by simulations.

Keywords: Ion irradiation; Heterojunction; TRI3DYN; Density functional theory; Transport property; Wetting

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Permalink: https://www.hzdr.de/publications/Publ-32493
Publ.-Id: 32493


Data for: High-bias-field operation of GaAs photoconductive terahertz emitters

Welsch, M.; Singh, A.; Winnerl, S.; Pashkin, O.; Xu, M.; Li, M.; Helm, M.; Schneider, H.

Data file names start with the corresponding figure in the manuscript. For example- file "F1cd_velocity vs E_hs_Jan8.opju" means this data set is used to plot Fig. 1c and 1d (So, name start with F1cd_). 

Keywords: Terahertz emitter; Photoconductive; Terahertz

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Permalink: https://www.hzdr.de/publications/Publ-32492
Publ.-Id: 32492


Data for: Influence of Muscovite (001) Surface Nanotopography on Radionuclide Adsorption studied by kinetic Monte Carlo Simulations

Schabernack, J.; Kurganskaya, I.; Fischer, C.; Luttge, A.

Raw Data for the Publication: Influence of Muscovite (001) Surface Nanotopography on Europium Adsorption studied by kinetic Monte Carlo Simulations

Kinetic Monte Carlo (KMC) simulations were performed on the (001) muscovite face.
KMC simulations were divided in two parts: (1) surface dissolution (2) europium (Eu3+) adsorption to resulting surface

Simulation Settings:
    - Surface Size [unit cells]: 700 in a, 300 in b, 8 in c
    - Dissolved Atoms: 2,000,000
    - Adsorbed Atoms: 300,000

KMC Simulations:
    - Case(I)  [1PitDepth6]  : One single etch pit with a depth of 6 unit cells or ~12 nm / 10 Simulation Runs
    - Case(II) [6PitsDepth1] : Six inital etch pits with depths of 1 uni cell or ~2 nm / 10 Simulation Runs
    - Study of etch pit depth vs. number of octahedral surface atoms [OctahedralSitesDepth]: Six simulations with pit depths from 1 to 6 unit cells / 1 Simulation Run each

Produced Output Data from KMC Simulations. Each Run contains:
    - Number of Adsorbed Atoms and Time (Ad_Num.txt)
    - Number of Adsorbed Atoms by Position and Time (Ad_Site_Stat.txt)
    - Number of Dissolved Atoms and Time (diss_num_1.txt)
    - Number of Dissolved Atoms by Position and Time (site_stats_1.txt)
    - Four Files for Adsorption Visualization (Ad_mov_01 to _04.pdb)
    - Four Files for Dissolution Visualization (m_mov_001_1 to _4.pdb)

    .pdb files can be opened and viewed by using the Visual Molecular Dynamics (VMD) viewer (https://www.ks.uiuc.edu/Research/vmd/)
        Humphrey, W., Dalke, A. and Schulten, K., "VMD - Visual Molecular Dynamics", J. Molec. Graphics, 1996, vol. 14, pp. 33-38.

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Permalink: https://www.hzdr.de/publications/Publ-32491
Publ.-Id: 32491


Heterogeneous sorption of radionuclides predicted by crystal surface nanoroughness

Yuan, T.; Schymura, S.; Bollermann, T.; Molodtsov, K.; Chekhonin, P.; Schmidt, M.; Stumpf, T.; Fischer, C.

Reactive transport modeling (RTM) is an essential tool for the prediction of contaminants’ behavior in the bio- and geosphere. However, RTM of sorption reactions is constrained by the reactive surface site assessment. The reactive site density variability of the crystal surface nanotopography provides an “energetic landscape”, responsible for heterogeneous sorption efficiency, not covered in current RTM approaches. Here, we study the spatially heterogeneous sorption behavior of Eu(III), as an analogue to trivalent actinides, on a polycrystalline nanotopographic calcite surface and quantify the sorption efficiency as a function of surface nanoroughness. Based on experimental data from micro-focus time-resolved laser-induced luminescence spectroscopy (μTRLFS), vertical scanning interferometry, and electron back-scattering diffraction (EBSD), we parameterize a surface complexation model (SCM) using surface nanotopography data. The validation of the quantitatively predicted spatial sorption heterogeneity suggests that retention reactions can be considerably influenced by nanotopographic surface features. Our study presents a way to implement heterogeneous surface reactivity into a SCM for enhanced prediction of radionuclide retention.

Keywords: Sorption reactions; Crystal surface reactivity; µTRLFS; Surface complexation modeling; Radionuclide migration

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Permalink: https://www.hzdr.de/publications/Publ-32490
Publ.-Id: 32490


Effective diffusivity prediction of radionuclides in clay formations using an integrated upscaling workflow

Yuan, T.; Fischer, C.

The effective diffusivity is a key parameter in the diffusive transport calculations, thus decisive for predicting the radionuclide migration in low-permeable clay-rich formations. Potential host rocks such as the Opalinus clay exhibit pore network heterogeneities, critically modified due to compositional variability in the sandy facies and owing to diagenetic minerals. Meaningful estimation of the effective diffusivity requires an understanding of transport mechanisms at the nanometer-scale as a starting point and a combination with upscaling strategies for considering compositional heterogeneities at the micrometer-scale.
In this study, we propose an upscaling workflow that integrates transport simulations at both the nanometer-scale and the micrometer-scale to predict the effective diffusivities of radionuclides in the sandy facies of the Opalinus clay. The respective synthetic digital rocks provide conceptually two types of materials at the pore scale, in which the pore space and pore network in the clay matrix at the nanometer scale and mineral complexity in shales at the micrometer scale are considered. The numerical approach using the introduced digital rocks is validated with published experimental data that confirm the general applicability of the models. Sensitivity studies reveal the increase of effective diffusivity of shales as a function of increased pore space, reduced tortuosity, and an increased sheet silicate concentration compared to other rock components. Thus, such spatial variabilities at the pore scale of more complex sedimentary rocks are now addressed in the proposed approach and available for studying heterogeneous diffusion patterns compared to commonly assumed homogeneous behavior. Finally, and as a starting point for further upscaling strategies, we investigate anisotropic diffusion by studying the effect of lamination of the shales towards enhanced predictability of radionuclide migration.

Keywords: Radionuclide migration; Diffusive transport modeling and Upscaling; Digital rock; Opalinus Clay; Nuclear waste disposal; Clay rock formations

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Permalink: https://www.hzdr.de/publications/Publ-32489
Publ.-Id: 32489


A combined experimental and theoretical study of 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene adsorption on Au(111)

Lokamani, M.; Kelling, J.; Ohmann, R.; Meyer, J.; Kühne, T.; Cuniberti, G.; Wolf, J.; Huhn, T.; Zahn, P.; Moresco, F.; Gemming, S.

The electronic and geometrical structure of 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene
(PEEB) molecules adsorbed on a Au(111) surface is investigated by low temperature scanning tun-
neling microscopy (STM) and scanning tunneling spectroscopy (STS) in conjunction with density-
functional-based tight-binding (DFTB) simulations of the density of states and the interaction with
the substrate. Our density functional theory calculations indicate that the PEEB molecule is ph-
ysisorbed on the Au(111) substrate, with negligible distortion of the molecular geometry and charge
transfer between molecule and substrate.

Keywords: 1,4-bis(phenylethynyl)-2,5-bis(ethoxy)benzene; DFT; STM; Au(111)

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Permalink: https://www.hzdr.de/publications/Publ-32488
Publ.-Id: 32488


Data for: Entrance effects in a radial Hele-Shaw cell: numerical and experimental study

Stergiou, G.; Eckert, K.; Schwarzenberger, K.

Hele-Shaw cells are a frequently used tool in various fields of chemical technology, and in environmental and biomedical engineering. The flow conditions near the inlet of a radial Hele-Shaw cell significantly affect the outcome of its technological applications. The present work combines Computational Fluid Dynamics (CFD) and micro-Particle Image Velocimetry (μPIV) to explain the entrance phenomena, i.e. flow detachment and vortex generation, in radial Hele-Shaw cells. The experiments show that the flow detachment is determined by the inlet flow Reynolds number, Re. Two-dimensional numerical simulations were employed to further investigate the role of the gap width, w to inlet diameter, D aspect ratio, w/D. The resulting flow regime map is divided by a transitional Re number, Ret, that depends on the aspect ratio. A further parametric study examining how Re and the aspect ratio affect the reattachment length yields an empirical correlation in power-law form. Finally, the impact of the inlet's geometrical features is briefly examined. The current work can be used as a design guide for future radial HS engineering applications.

Keywords: Hele-Shaw cell; flow separation; laminar flow; reattachment length; CFD; μPIV

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Permalink: https://www.hzdr.de/publications/Publ-32487
Publ.-Id: 32487


Linear, spatio-temporally resolved ultrasound measurement of the liquid fraction distribution in froth

Emmerich, H.; Schaller, L.; Nauber, R.; Knüpfer, L.; Heitkam, S.; Czarske, J.; Büttner, L.

Froth flotation is an important process for separating metal particles from gangue. A single flotation circuit for copper uses approx. 44 billion litres water a year. In situ process monitoring of the foam’s parameters and closed-loop control can reduce the resource use. However, no measurement technique is broadly employed that yields the liquid fraction distribution in the froth. Optical measurement are prevented by the bulk foam’s opacity. Though, ultrasound in the low frequency range is able to penetrate froth. In this paper we investigate the application of ultrasound to measure the local liquid content of aqueous foam in the axis of the ultrasound beam. Assuming a dependency of the reflection coefficient 𝑟 on the foam’s liquid fraction 𝜑, we developed a model to calculate 𝑟 from the reflected signal. Local reflection coefficients 𝑟_𝑛 can be determined for timegated windows and show a monotonic dependency on the foam’s liquid fraction 𝜑 (for 𝜑< 0.8 %). The uncertainty of the liquid fraction determined by means of a electrical reference measurement is 𝜎_𝜑= 0.079%. We demonstrated the capability of spatio-temporally resolved measurements with a frame rate of 3 s and an axial resolution of 0.79 mm in an experiment with a time-varying, inhomogeneous liquid fraction. This research work is contributing to a determination of in situ information of the foam’s parameter in a flotation process.

Keywords: foam; ultrasound

Permalink: https://www.hzdr.de/publications/Publ-32486
Publ.-Id: 32486


Design, radiosynthesis and preliminary biological evaluation in mice of a brain-penetrant 18F-labelled σ2 receptor ligand

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

The σ2 receptor (transmembrane protein 97), which is involved in cholesterol homeostasis, is of high relevance for neoplastic processes. The upregulated expression of σ2 receptors in cancer cells and tissue in combination with the antiproliferative potency of σ2 receptor ligands motivates the research in the field of 2 receptors for the diagnosis and therapy of different types of cancer. Starting from the well described 2-(4-(1H-indol-1-yl)butyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline class of compounds, we synthesized a novel series of fluorinated derivatives, bearing the F-atom at the aromatic indole/azaindole subunit. RM273 (2-[4-(6-fluoro-1H-pyrrolo[2,3-b]pyridin-1-yl)butyl]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline) was selected for labelling with 18F and evaluation regarding detection of σ2 receptors in the brain by positron emission tomography. Initial metabolism and biodistribution studies of [18F]RM273 in healthy mice revealed promising penetration of the radioligand into the brain. Preliminary in vitro autoradiography on brain cryosections of an orthotopic rat glioblastoma model proved the potential of the radioligand to detect the upregulation of σ2 receptor in glioblastoma cells compared to healthy brain. The results indicate that the herein developed σ2 receptor ligand [18F]RM273 has potential to assess by non-invasive molecular imaging the correlation between the availability of σ2 receptors with properties of brain tumors such as tumor proliferation or resistance towards particular therapies

Keywords: σ2 receptor; transmembrane protein 97; azaindoles; binding affinity; radiochemistry; fluorine-18 labeling; positron emission tomography (PET); brain-penetration; glioblastoma; orthotopic

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Permalink: https://www.hzdr.de/publications/Publ-32485
Publ.-Id: 32485


Status of LISEL@DREAMS

Forstner, O.; Weber, T.; Wendt, K.; Gadelshin, V.; Merchel, S.; Rugel, G.

Accelerator Mass Spectrometry (AMS) is a highly versatile tool to detect radionuclides on the ultra-trace level. LISEL@DREAMS aims for improving the AMS method by reducing the amount of stable isobars limiting its applicability especially in the mass region 50

Keywords: Accelerator Mass Spectrometry; Low-energy Isobar SEparation by Lasers; LISEL; AMS; radionuclide

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  • Poster (Online presentation)
    Ion beam workshop 2021 - virtual meeting, 24.-25.03.2021, Online, World-wide

Permalink: https://www.hzdr.de/publications/Publ-32484
Publ.-Id: 32484


Influence of Muscovite (001) Surface Nanotopography on Radionuclide Adsorption Studied by Kinetic Monte Carlo Simulations

Schabernack, J.; Kurganskaya, I.; Fischer, C.; Luttge, A.

Mechanistic understanding and prediction of solute adsorption from fluids onto mineral surfaces is relevant for many natural and technical processes. Mineral surfaces in natural systems are often exposed to fluids at non-equilibrium conditions resulting in surface dissolution reactions. Such reactions cause the formation of surface nanotopography and, consequently, the exposure of different types of surface atoms. The quantitative effect of nanotopography on the efficiency of adsorption reactions at crystal surfaces is not known. Using kinetic Monte Carlo simulations, we combine a model of muscovite (001) face dissolution with a consequent model of europium adsorption on the rough mineral surface. The model considers three different adsorption sites based on the muscovite surface cations: silicon, tetrahedral and octahedral aluminum. Two different surface nanotopography configurations are investigated, both showing similar adsorption behavior. Octahedral aluminum surface atoms defined by having the highest reactivity towards adsorption are exposed solely on steps and pits on the muscovite (001) face. Thus, their availability directly depends on the surface nanotopography. The model results show the need for a more precise parameterization of surface site-specific adsorption, taking into account the coordination of the involved surface cation such as kink, step or terrace sites.

Keywords: kinetic Monte Carlo simulation; adsorption; dissolution; radionuclides; muscovite

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Permalink: https://www.hzdr.de/publications/Publ-32483
Publ.-Id: 32483


MHD driven localized short circuits in liquid metal batteries

Benard, S.; Landgraf, S.; Weber, N.; Weier, T.

Liquid metal batteries (LMBs) are electrochemical devices, which operate as simple concentration cells at elevated temperature. Abundant raw materials and the totally liquid interior promise a very long life time, extreme current densities and a very competitive price of these storage devices. For this reason, LMBs are discussed as an ideal candidate for grid-scale energy storage.
The cathode of the cells (e.g. molten Bi, at the bottom) is typically contained in a metal vessel, while the anode (e.g. molten Li, at the top) is soaked into a FeNi-foam. Both electrodes are separated by a molten salt electrolyte. When discharging the cell, Li is oxidised, crosses the electrolyte layer and alloys into Bi; upon charge, the process is reversed. Due to corrosion or electrochemical reactions of the molten salt layer with the FeNi-foam, the Li-wetting of the foam might decrease during operation. In case of insufficient wetting of this current collector, it might happen that the Li does not penetrate the foam any more, when the cell is charged. Consequently, small Li-droplets will appear below of the foam, and will grow into the electrolyte layer, when charging the battery. As the conductivity of the electrolyte is four orders of magnitude smaller than that of the metals, the current will take the shortest way through the electrolyte, i.e. a large current will flow through the Li-droplets. This current might pinch the droplet locally, possibly deforming, or even cutting it off. Hence, small Li-spheres might be transferred into the electrolyte. This might lead to unwanted self-discharge, if Li reaches the Bi-layer.
In the presentation, the appearance and significance of such localised droplet-transfer and short-circuits will be discussed first. Then, some experimental evidence of similar effects will be presented. Finally, numerical simulations of the transfer of a single droplet will be shown. Moreover, the relevance of the results for practical applications and real cells will be explained.

  • Lecture (Conference)
    Fourth Russian Conference on Magnetohydrodynamics, 20.09.2021, Perm, Russland

Permalink: https://www.hzdr.de/publications/Publ-32482
Publ.-Id: 32482


Teaching Machine Learning in 2020

Steinbach, P.; Seibold, H.; Guhr, O.

Faced by the abundant use of machine learning in industry and academia, the effective and efficient teaching of core concepts in this field becomes of high importance. For this, we organized a workshop on teaching methods in the field of machine learning. In this document, we summarize the current standing of the community as by our workshop and their methods. We touch on existing working concepts in machine learning didactics, what methods present initiatives use and cover open teaching resources available to date. With this, we hope to provide a starting point for future collaborations on this central topic given the expanding use of machine learning in science, industry and our daily lives.

Keywords: Machine Learning; Deep Learning; Data Science; Teaching; Didactics

  • Open Access Logo Contribution to proceedings
    Proceedings of the first Teaching Machine Learning and Artificial Intelligence Workshop at ECML-PKDD 2020, 14.09.2020, virtuell, virtuell
    Volume 141: European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases, http://proceedings.mlr.press/v141/

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Permalink: https://www.hzdr.de/publications/Publ-32481
Publ.-Id: 32481


Investigating the interplay of heat and mass transport in a three-layer liquid metal battery model

Klopper, T. S.

Thermal and solutal convection effects have been proven to have a significant impact in liquid metal batteries (LMBs) with potentially beneficial but eventually detrimental effects on their operation. LMBs are likely to be good candidates for solving the 21st century challenge of storing electrical energy on a large scale in order to ensure the stability of electrical grids in the future, which will consist of an increasing amount of renewable energies. With their fully liquid interior, they feature numerous phenomena of fluid dynamics, which are studied in order to adjust the battery’s design. Among them are convective phenomena, which play a role when density gradients form due to heating or compositional variations. The typical LMB consists of three segregated layers featuring different characteristics. Thermal convection typically occurs in the negative electrode and the electrolyte, while solutal convection is unique in the positive electrode, where it occurs during charge of the battery. Previous numerical studies observed that thermal convection is dominant either in the negative electrode or in the electrolyte, which depends strongly on the layers’ thicknesses. Coupling between the interfaces has been observed, but was not yet studied in-depth. Effects of solutal convection have been studied on the isolated positive electrode only and could be associated with substantial flow.
We performed numerical studies to examine the interfacial coupling of the two types of convection in a three-layer model. Therefore we made use of an OpenFOAM solver specifically developed for this problem. The solver was first validated by performing a grid independence study and comparing the results to previous solutions. A configuration was then studied, where significant flow evolves due to both thermal and solutal convection in all three regions. We observed chaotic flow patterns, which were strongly affected by the interfacial coupling. As a result, the flow phenomena in the electrolyte are highly irregular, as it is affected from the other layers both at its top and bottom interfaces. We suspect the behaviour to be highly dependent on the exact configuration of the battery and therefore suggest that these phenomena are studied more extensively in the future.

  • Master thesis
    Carl von Ossietzky Universität Oldenburg, 2021

Permalink: https://www.hzdr.de/publications/Publ-32480
Publ.-Id: 32480


Entrance effects in a radial Hele-Shaw cell: numerical and experimental study

Stergiou, G.; Eckert, K.; Schwarzenberger, K.

Hele-Shaw cells are a frequently used tool in various fields of chemical technology, and in environmental and biomedical engineering. The flow conditions near the inlet of a radial Hele-Shaw cell significantly affect the outcome of its technological applications. The present work combines Computational Fluid Dynamics (CFD) and micro-Particle Image Velocimetry (μPIV) to explain the entrance phenomena, i.e. flow detachment and vortex generation, in radial Hele-Shaw cells. The experiments show that the flow detachment is determined by the inlet flow Reynolds number, Re. Two-dimensional numerical simulations were employed to further investigate the role of the gap width, w to inlet diameter, D aspect ratio, w/D. The resulting flow regime map is divided by a transitional Re number, Ret, that depends on the aspect ratio. A further parametric study examining how Re and the aspect ratio affect the reattachment length yields an empirical correlation in power-law form. Finally, the impact of the inlet's geometrical features is briefly examined. The current work can be used as a design guide for future radial HS engineering applications.

Keywords: Hele-Shaw cell; flow separation; laminar flow; reattachment length; CFD; μPIV

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Permalink: https://www.hzdr.de/publications/Publ-32479
Publ.-Id: 32479


Post-implantation defects in heavy ion implanted monocrystalline ZnO

Werner, Z.; Barlak, M.; Ratajczak, R.; Akhmadaliev, S.; Heller, R.; Staszkiewicz, B.; Zagórski, J.

Monocrystalline ZnO samples were implanted with Co (transition metal) and with Ar and Kr noble gas ions, with energies and doses leading to comparable damage in the host lattice as regards its extension and magnitude. Structural properties of the implantedZnOwere investigated by channeled Rutherford Backscattering Spectrometry (cRBS), aided with calculations using McChasy code. It was shown that the damage produced by implantation does not reach an amorphization level in all cases and is produced deeper in the crystal in comparison with theoretical predictions. The range and magnitude of damaged region are comparable in all cases of ion implantation.

Keywords: ZnO; heavy ion implantation; cRBS measurements; damage simulation

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Permalink: https://www.hzdr.de/publications/Publ-32478
Publ.-Id: 32478


Oscillatory Copper Deposition on Conical Iron Electrodes in a Nonuniform Magnetic Field

Marinaro, G.; Huang, M.; Mutschke, G.; Yang, X.; Eckert, K.

We report the effect of a magnetic field on the deposition of copper ions on a conically shaped iron probe. In our setup, the magnetic forces and buoyancy are the key factors influencing the electrolyte flow and the mass transfer. Without external current, a spontaneous reduction of copper on the iron cone occurs, known as electroless deposition. Mach–Zehnder and differential interferometry indicate a variation in the concentration of copper ions near the cone. After an initial transient of about 60 s, temporal oscillations in the copper concentration are found under the effect of a magnetic field. In galvanostatic conditions, a similar oscillatory behavior of the concentration of the electrolyte is observed. Numerical simulations show that the oscillations are caused by the magnetic gradient, Lorentz force, and buoyancy force counteracting one an-other, and the oscillation frequency is estimated analytically based on this mechanism. Fur-thermore, we present a study on the oscillation frequency for both electroless and galvanostatic conditions with different current densities. The results of this study may stimulate future re-search aimed at the local control of the deposition rate and the realization of miniaturized, reg-ularly structured deposits using magnetic fields.

Keywords: Electrodeposition; magnetic field; mass transport; variation of ion concentration; Mach-Zehnder Interferometry

Permalink: https://www.hzdr.de/publications/Publ-32477
Publ.-Id: 32477


Numerical and experimental data set obtained from paraffin phantom measurements based on the capacitance wire-mesh sensor.

de Assis Dias, F.; Wiedemann, P.; Da Silva, M. J.; Schleicher, E.; Hampel, U.

This data set contains experimental and numerical data from a 12x12 wire-mesh sensor. A 12x12 WMS was used to measure paraffin phantoms created to mimic three flow patterns: slug, annular and bubble flow. The sensor was assembled with flanges and filled with tap water. Two models based on finite element model were used to generate the synthetic data. The first one is a basic FEM model, which was designed based on other models reported in the literature (i.e. the output signal is obtained by integrating the current density over the surface of a receiver wire). In the second model (FEM+EC), the electric potential is solved as the basic one, however, external circuits (macromodels) were coupled to the 3D geometry of the sensor to emulate the excitation and amplification systems of a real WMS.A mapping containing the coordinates and electrical properties of the paraffin phantoms was created through image processing and imported into the software COMSOL v.5.6. Thus, both basic FEM and FEM+EC models were used to generate synthetic data that can be direct compared to the experimental data.

Keywords: capacitance wire-mesh sensor; data set; phantom measurement; multiphase flow; finite element method

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Permalink: https://www.hzdr.de/publications/Publ-32476
Publ.-Id: 32476


Correlative light and Helium Ion Microscopy to identify lung response to metal oxide and carbon nanomaterials done on model lung epithelium

Podlipec, R.; Kriselj, A.; Vogel Mikus, K.; Klingner, N.; Hlawacek, G.; Strancar, J.

Comprehensive understanding of molecular events governing lung epithelium response to inhaled nanoparticles is still lacking. These repeating events in lungs could eventually lead to persistent inflammation and further cardiovascular diseases [1,2]. To better understand how it all start on a molecular, nanoscale level one urgently needs an appropriate model system and an advanced imaging technique(s) capable of unravelling key information on a nanoscale. Many studies addressing such complex biological problems have been lately tackled by correlative microscopy (CM) approach using an optimal combination of complementary and advanced techniques [3].
Our approach was thus to apply live cell epithelium model imaging using an advanced high-resolution fluorescence microscopy followed by helium ion microscopy (HIM) to visualize structures and morphology further down at nano-scale. One of the HIM advantages to other high-resolution, high-vacuum imaging techniques is large depth of focus, sub-nm resolution, nm surface sensitivity, and especially no need for sample coating that changes the nanostructure morphology on the surface. To gather any further structure-function information of the investigated biological system using such diametrical techniques, an appropriate sample preparation needed to be developed. Once done, we could study sub-micron to nanometer changes that govern model lung epithelium interaction with various nanoparticles. Exposure of metal oxide (TiO2) nanotubes has revealed active passivation of nanomaterial-biological matter composites on the cell surface with lipo-proteins present, identified both with optical and ion beam technique (Figure, below). Findings of CM studies have contributed to better understand chronic inflammation prediction in lung diseases [4]. On the other hand, exposed carbon nanoparticles have shown completely different cell response and will be discussed.

1. Li, X., Jin, L. & Kan, H. Air pollution: a global problem needs local fixes. Nature 570, 437–439 (2019).
2. Underwood, E. The polluted brain. Science 355, 342–345 (2017).
3. Ando, T. The 2018 correlative microscopy techniques roadmap, J. Phys. D: Appl. Phys. 51, (2018).
4. Kokot, H., et. al, Prediction of Chronic Inflammation for Inhaled Particles: the Impact of Material Cycling and Quarantining in the Lung Epithelium, Advanced Materials 32, 2003913 (2020)

Related publications

  • Lecture (Conference)
    Focus on Microscopy, 2021, 28.-31.03.2021, Virtual, Virtual

Permalink: https://www.hzdr.de/publications/Publ-32475
Publ.-Id: 32475


Aktuelle radiopharmazeutische Entwicklungen für die theranostische Anwendung

Neels, O.; Kratochwil, C.; Patt, M.

Im vorliegenden CME-Beitrag sollen die Grundlagen des Theranostik-Prinzips beginnend bei den Eigenschaften der Radionuklide sowie deren Verfügbarkeit erläutert werden. Anhand von medizinischen und chemischen Beispielen aus den prominentesten Anwendungsgebieten der Theranostik (Prostatakarzinom/PSMA, neuroendokrine Tumoren und Fibroblasten-Aktivierungsprotein Inhibitoren) werden die unterschiedlichen Arten von theranostischen Radionuklid- und Radioliganden-Paaren beschrieben. Abgerundet wird der Artikel durch Ausführungen zu den regulatorischen Randbedingungen wie Verfügbarkeit und Verkehrsfähigkeit von Radionuklidvorstufen und radioaktiven Arzneimitteln sowie zu deren Eigenherstellung.

Keywords: Theranostik; Radiopharmazie; PET; SPECT; Gesetzgebung; AMG; erlaubnisfreie Herstellung; AMRadV

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Permalink: https://www.hzdr.de/publications/Publ-32474
Publ.-Id: 32474


Predicting the Risk of Metastases by PSMA-PET/CT—Evaluation of 335 Men with Treatment-Naïve Prostate Carcinoma.

Koerber, S.; Boesch, J.; Kratochwil, C.; Schlampp, I.; Ristau, J.; Winter, E.; Zschaebitz, S.; Hofer, L.; Herfarth, K.; Kopka, K.; Holland-Letz, T.; Jaeger, D.; Hohenfellner, M.; Haberkorn, U.; Debus, J.; Giesel, F.

Men diagnosed with aggressive prostate cancer are at high risk of local relapse or systemic
progression after definitive treatment. Treatment intensification is highly needed for that patient
cohort; however, no relevant stratification tool has been implemented into the clinical work routine
so far. Therefore, the aim of the current study was to analyze the role of initial PSMA-PET/CT as a prediction tool for metastases. In total, 335 men with biopsy-proven prostate carcinoma and PSMA-PET/CT for primary staging were enrolled in the present, retrospective study. The number
and site of metastases were analyzed and correlated with the maximum standardized uptake value (SUVmax) of the intraprostatic, malignant lesion. Receiver operating characteristic (ROC) curves were used to determine sensitivity and specificity and a model was created using multiple logistic regression. PSMA-PET/CT detected 171 metastases with PSMA-uptake in 82 patients. A statistically significant higher SUVmax was found for men with metastatic disease than for the cohort without distant metastases (median 16.1 vs. 11.2; p < 0.001). The area under the curve (AUC) in regard to predicting the presence of any metastases was 0.65. Choosing a cut-off value of 11.9 for SUVmax, a sensitivity and specificity (factor 1:1) of 76.0% and 58.4% was obtained. The current study confirms, that initial PSMA-PET/CT is able to detect a relatively high number of treatment-naïve men with metastatic prostate carcinoma. Intraprostatic SUVmax seems to be a promising parameter for the prediction of distant disease and could be used for treatment stratification—aspects which should be verified within prospective trials.

Keywords: prostate cancer; PSMA; PET; metastases; intraprostatic SUV

Permalink: https://www.hzdr.de/publications/Publ-32473
Publ.-Id: 32473


Chlorine doping of MoSe2 flakes by ion implantation

Prucnal, S.; Hashemi, A.; Ghorbani Asl, M.; Hübner, R.; Duan, J.; Wei, Y.; Sharma, D.; Zahn, D. R. T.; Ziegenrücker, R.; Kentsch, U.; Krasheninnikov, A.; Helm, M.; Zhou, S.

The efficient integration of transition metal dichalcogenides (TMDs) into the current electronic device technology requires mastering the techniques of effective tuning of their optoelectronic properties. Specifically, controllable doping is essential. For conventional bulk semiconductors, ion implantation is the most developed method offering stable and tunable doping. In this work, we demonstrate n-type doping in MoSe2 flakes realized by low-energy ion implantation of Cl+ ions followed by millisecond-range flash lamp annealing (FLA). We further show that FLA for 3 ms with a peak temperature of about 1000 °C is enough to recrystallize implanted MoSe2. The Cl distribution in few-layer-thick MoSe2 is measured by secondary ion mass spectrometry. An increase in the electron concentration with increasing Cl fluence is determined from the softening and red shift of the Raman-active A1g phonon mode due to the Fano effect. The electrical measurements confirm the n-type doping of Cl-implanted MoSe2. A comparison of the results of our density functional theory calculations and experimental temperature-dependent micro-Raman spectroscopy data indicates that Cl atoms are incorporated into the atomic network of MoSe2 as substitutional donor impurities.

Keywords: MoSe2; ion implantation; Flash Lamp Annealing; doping; 2D materials; DFT; Raman

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Permalink: https://www.hzdr.de/publications/Publ-32472
Publ.-Id: 32472


Flow morphologies in straight and bent horizontal pipes

Döß, A.; Schubert, M.; Wiedemann, P.; Junge, P.; Hampel, U.; Schleicher, E.; Mehringer, C.; Geipel, C.

Two-phase flows in pipes develop characteristic patterns or flow morphologies. Their transport between process units and plant components often involves short pipes, large pipe diameters as well as bends and curvatures. The prediction of the predominantly undeveloped flow morphologies in such systems is challenging and subject to high uncertainties due to lacking experimental data and universal engineering models. In this work comprehensive experimental studies were conducted in horizontal straight and bent pipes of 50 mm and 200 mm diameter. Wire-mesh sensors were applied at characteristic positions to obtain the gas-liquid distributions with high spatiotemporal resolution. Subsequently, a fuzzy classification method is applied to assign a flow pattern to characterize the flow conditions. As this assignment is fuzzy, we introduce an advanced concept of a color-coded flow map visualization for further analyses. As a result, we analyze the effect of pipe curvatures on the flow morphology and its downstream recovery.

Keywords: Developing two-phase flow; horizontal pipe flow; wire-mesh sensor; fuzzy flow pattern identification; flow morphology

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Permalink: https://www.hzdr.de/publications/Publ-32471
Publ.-Id: 32471


Combined Finite Element and Electronic Circuit Model of a Wire-Mesh Sensor

de Assis Dias, F.; Wiedemann, P.; Da Silva, M. J.; Schleicher, E.; Hampel, U.

A new wire-mesh sensor model based on electric field and circuit simulations is presented. In our approach, the excitation and amplification stages of the capacitance WMS are created as macromodels and coupled to the electrodes of a 3D geometry of the sensor. Thus, the effects caused by nonideal characteristics of the amplifiers are considered (e.g. finite open-loop gain and bandwidth). In order to evaluate the performance of the model, a static validation based on phantom measurement was performed. The phantoms were created with paraffin to emulate typical flow regimes, i.e. annular, slug and bubble flow. A mapping containing the position and the electrical properties of the patterns was obtained by image processing and incorporated to the field simulation. Hence the numerical simulations could be directly compared to the experimental data. The results show that coupling the external circuits to the capacitance WMS model is crucial to provide reliable synthetic data.

Keywords: complex impedance; multiphase flow; flow visualization; finite-element method; wire-mesh sensor

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Permalink: https://www.hzdr.de/publications/Publ-32470
Publ.-Id: 32470


Conductive hydrogels with dynamic reversible networks for biomedical applications

Xu, Y.; Patino Gaillez, M.; Rothe, R.; Hauser, S.; Voigt, D.; Pietzsch, J.; Zhang, Y.

Conductive hydrogels (CHs) are emerging as a promising and well-utilized platform for three-dimensional (3D) cell culture and tissue engineering to incorporate electron signals as biorelevant physical cues. In conventional covalently crosslinked conductive hydrogels, the network dynamics (e.g., stress relaxation, shear shining, and self-healing) required for complex cellular functions and many biomedical utilities (e.g., injection) cannot be easily realized. In contrast, dynamic conductive hydrogels (DCHs) are fabricated by dynamic and reversible crosslinks. By allowing for the breaking and reforming of the reversible linkages, DCHs can provide dynamic environments for cellular functions while maintaining matrix integrity. These dynamic materials can mimic some properties of native tissues, making them well suited for several biotechnological and medical applications. An overview of the design, synthesis, and engineering of DCHs is presented in this review, focusing on the different dynamic crosslinking mechanisms of DCHs and their biomedical applications.

Permalink: https://www.hzdr.de/publications/Publ-32469
Publ.-Id: 32469


High Bias Field Operation of GaAs Photoconductive Terahertz Emitter

Welsch, M.; Singh, A.; Winnerl, S.; Pashkin, O.; Xu, M.; Li, M.; Helm, M.; Schneider, H.

We demonstrate experimentally the increase of optical-to-terahertz conversion efficiency for GaAs-based photoconductive terahertz emitters. This increase is achieved by preventing device breakdown through series resistors, which act as a current limiter. Pulsed photoexcitation and potential current fluctuations result in heat dissipation leading to local heating, which further increases the current and may lead to device breakdown. We manage to increase the maximum bias field before device breakdown by a factor of 3 under illuminated conditions. For a laser system with 250 kHz repetition rate, the terahertz emission amplitude increases linearly with applied bias field up to 120 kV/cm bias field, which results in 3 times higher signal as compared to the standard device. Furthermore, we have also achieved this expanded breakdown prevention at 78 MHz repetition rate, where an integrated on-chip resistance leads to an enhancement of the terahertz field amplitude by 70%. This simple technique can increase the performance of almost all photoconductive terahertz emitters by using appropriate resistances according to the emitter capacitance and laser repetition rate.

Keywords: Terahertz emitter; Terahertz; Photoconductive emitter

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Permalink: https://www.hzdr.de/publications/Publ-32468
Publ.-Id: 32468


Two Be or Not Two Be: The Nuclear Autoantigen La/SS-B Is able to form Dimers and Oligomers in a Redox Dependent Manner

Berndt, N.; Bippes, C. C.; Michalk, I.; Bachmann, D.; Bachmann, J.; Puentes-Cala, E.; Bartsch, T.; Loureiro, L. R.; Kegler, A.; Bergmann, R.; Gross, J. K.; Gross, T.; Kurien, B. T.; Scofield, R. H.; Farris, A. D.; James, J. A.; Schmitz, M.; Fahmy, K.; Feldmann, A.; Arndt, C.; Bachmann, M.

According to the literature, the autoantigen La is involved in Cap-independent translation. It was proposed that one prerequisite for this function is the formation of a protein dimer. However, structural analyses argue against La protein dimers. Noteworthy to mention, these structural analyses were performed under reducing conditions. Here we describe that La protein can undergo redox-dependent structural changes. The oxidized form of La protein can form dimers, oligomers and even polymers stabilized by disulfide bridges. The primary sequence of La protein contains three cysteine residues. Only after mutation of all three cysteine residues to alanine La protein becomes insensitive to oxidation, indicating that all three cysteines are involved in redox-dependent structural changes. Biophysical analyses of the secondary structure of La protein support the redox-dependent conformational changes. Moreover, we identified monoclonal anti-La antibodies (anti-La mAbs) that react with either the reduced or oxidized form of La protein. Differential reactivities to the reduced and oxidized form of La protein were also found in anti-La sera of autoimmune patients.

Keywords: anti-La/SS-B antibodies; autoimmunity; La/SS-B autoantigen; systemic lupus erythematosus; primary Sjögren’s syndrome

Permalink: https://www.hzdr.de/publications/Publ-32466
Publ.-Id: 32466


LWFA PIConGPU setup for minimizing transverse phase space effects paper

Pausch, R.; Köhler, A.; Bastrakov, S.; Bussmann, M.; Couperus Cabadağ, J. P.; Irman, A.; Steiniger, K.; Widera, R.; Debus, A.

This repository contains the PIConGPU source code and setup files used for the "Minimizing transverse phase space effects on beam-loaded laser-wakefield accelerated electron beams" paper.

Keywords: PIConGPU; HPC; LWFA

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Permalink: https://www.hzdr.de/publications/Publ-32465
Publ.-Id: 32465


Overestimation of grey matter atrophy in glioblastoma patients following radio(chemo)therapy

Gommlich, A.; Raschke, F.; Petr, J.; Seidlitz, A.; Jentsch, C.; Platzek, I.; van den Hoff, J.; Kotzerke, J.; Beuthien-Baumann, B.; Baumann, M.; Krause, M.; Troost, E. G. C.

Objective
Brain atrophy has the potential to become a biomarker for severity of radiation-induced side-effects. Particularly brain tumour patients can show great MRI signal changes over time caused by e.g. oedema, tumour progress or necrosis. The goal of this study was to investigate if such changes affect the segmentation accuracy of normal appearing brain and thus influence longitudinal volumetric measurements.
Materials and Methods
T1-weighted MR images of 52 glioblastoma patients with unilateral tumours acquired before and three months after the end of radio(chemo)therapy were analysed. GM and WM volumes in the contralateral hemisphere were compared between segmenting the whole brain (full) and the contralateral hemisphere only (cl) with SPM and FSL. Relative GM and WM volumes were compared using paired t-tests and correlated with the corresponding mean dose in GM and WM, respectively.
Results
Mean GM atrophy was significantly higher for full segmentation compared to cl segmentation when using SPM (mean ± std: ΔVGM,full = -3.1% ± 3.7%, ΔVGM,cl = -1.6% ± 2.7%; p < 0.001 , d = 0.62). GM atrophy was significantly correlated with the mean GM dose with the SPM cl segmentation (r = -0.4, p = 0.004), FSL full segmentation (r = -0.4, p = 0.004) and FSL cl segmentation (r = -0.35, p = 0.012) but not with the SPM full segmentation (r = -0.23, p = 0.1).
Conclusions
For accurate normal tissue volume measurements in brain tumour patients using SPM, abnormal tissue needs to be masked prior to segmentation, however, this is not necessary when using FSL.

Keywords: radiotherapy; tissue segmentation; SPM; atrophy; glioblastoma; proton

Permalink: https://www.hzdr.de/publications/Publ-32464
Publ.-Id: 32464


Efficient and low-voltage vertical organic permeable base light-emitting transistors

Wu, Z.; Liu, Y.; Guo, E.; Darbandy, G.; Wang, S.-J.; Hübner, R.; Kloes, A.; Kleemann, H.; Leo, K.

Organic light-emitting transistors, three-terminal devices combining a thin-film transistor with a light-emitting diode, have generated increasing interest in organic electronics. However, increasing their efficiency while keeping the operating voltage low still remains a key challenge. Here, we demonstrate organic permeable base light-emitting transistors; these three-terminal vertical optoelectronic devices operate at driving voltages below 5.0 V; emit in the red, green and blue ranges; and reach, respectively, peak external quantum efficiencies of 19.6%, 24.6% and 11.8%, current efficiencies of 20.6 cd A–1, 90.1 cd A–1 and 27.1 cd A–1 and maximum luminance values of 9,833 cd m–2, 12,513 cd m–2 and 4,753 cd m–2. Our simulations demonstrate that the nano-pore permeable base electrode located at the centre of the device, which forms a distinctive optical microcavity and regulates charge carrier injection and transport, is the key to the good performance obtained. Our work paves the way towards efficient and low-voltage organic light-emitting transistors, useful for power-efficient active matrix displays and solid-state lighting.

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Permalink: https://www.hzdr.de/publications/Publ-32463
Publ.-Id: 32463


Reconfigurable magnetic origami actuators with on-board sensing for guided assembly

Ha, M.; Canon Bermudez, G. S.; Liu, J. A.-C.; Oliveros Mata, E. S.; Evans, B. A.; Tracy, J. B.; Makarov, D.

Origami utilizes orchestrated transformation of soft two-dimensional structures into complex three-dimensional architectures, mimicking shapes and functions found in nature. In contrast to origami in nature, synthetic origami lacks the ability to monitor the environment and correspondingly adjust its behavior. Here, we design, fabricate, and demonstrate magnetic origami actuators with capabilities to sense their orientation and displacement and detect their own magnetization state and readiness for supervised folding. These origami actuators integrate photothermal heating and magnetic actuation by using composite thin films (~60 µm thick) of shape-memory polymers with embedded magnetic NdFeB microparticles. Mechanically compliant magnetic field sensors, known as magnetosensitive electronic skins, are laminated on the surface of the soft actuators. These ultrathin actuators accomplish sequential folding and recovery, with hinge locations programmed on the fly. Endowing mechanically active smart materials with cognition is an important step toward realizing intelligent, stimuli-responsive structures.

Keywords: magnetic; origami; reconfigurable; actuation; sensor

Permalink: https://www.hzdr.de/publications/Publ-32462
Publ.-Id: 32462


Complexation and longer-term dynamics of the coordination of Cm(III) and Eu(III) in Human serum Transferrin

Taylor, C. J.

Conference presentation, International Workshop on Theory Frontiers in Actinide Sciences: Chemistry and Materials, 2nd-5th of Feb, Hilton Santa Fe, Santa Fe, New Mexico, USA

  • Lecture (Conference)
    International Workshop on Theory Frontiers in Actinide Sciences: Chemistry and Materials, 02.-05.02.2020, Santa Fe, NM, USA

Permalink: https://www.hzdr.de/publications/Publ-32461
Publ.-Id: 32461


Porosity characterisation of intact concrete specimens.

Roode-Gutzmer, Q. I.; Kulenkampff, J.; Barkleit, A.; Stumpf, T.

The chemical durability of concrete is largely dependent on the chemical reactivity of the silicate aggregates to alkaline pore water. Concrete irradiated at sufficient neutron fluences results in the breakdown of the Si-tetrahedron connected to 4 Si-atoms (Q⁴) to produce Q³ species, which is significantly more soluble in aqueous media. This leads to the alkali silica reaction (ASR), which is the most important degradation process in radiation-damaged concrete. For biological shielding concrete the occurrence of ASR has two ramifications: loss of mechanical strength (which shortens service life), and changes to the pore structure and reactive surface that play a role in the sorption characteristics and transport of radionuclides (neutron activated species or fission products from leaked reactor cooling water). Most investigations on the porosity of materials are conducted on pulverized specimens. We employ intact specimens. In order to achieve the highest possible resolution via μ-computed tomography (μ-CT), small cylindrical cores (0.15±0.01 g) were examined. The connected porosity of these specimens is examined using mercury intrusion porosimetry.

Keywords: concrete; intact specimens; porosity; mercury intrusion porosimetry; micro computed tomography

  • Open Access Logo Poster (Online presentation)
    3rd ICCCM International Conference on the Chemistry of Construction Materials, 15.-17.03.2021, Karlsruhe / Online, Germany

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Permalink: https://www.hzdr.de/publications/Publ-32460
Publ.-Id: 32460


Sub-diffractional cavity modes of terahertz hyperbolic phonon polaritons in tin oxide

Feres, F. H.; Mayer, R. A.; Wehmeier, L.; Maia, F. C. B.; Viana, E. R.; Malachias, A.; Bechtel, H. A.; Klopf, J. M.; Eng, L. M.; Kehr, S. C.; González, J. C.; Freitas, R. O.; Barcelos, I. D.

Hyperbolic phonon polaritons have recently attracted considerable attention in nanophotonics mostly due to their intrinsic strong electromagnetic field confinement, ultraslow polariton group velocities, and long lifetimes. Here we introduce tin oxide (SnO2) nanobelts as a photonic platform for the transport of surface and volume phonon polaritons in the mid- to far-infrared frequency range. This report brings a comprehensive description of the polaritonic properties of SnO2 as a nanometer-sized dielectric and also as an engineered material in the form of a waveguide. By combining accelerator-based IR-THz sources (synchrotron and free-electron laser) with s-SNOM, we employed nanoscale far-infrared hyperspectral-imaging to uncover a Fabry–Perot cavity mechanism in SnO2 nanobelts via direct detection of phonon-polariton standing waves. Our experimental findings are accurately supported by notable convergence between theory and numerical simulations. Thus, the SnO2 is confirmed as a natural hyperbolic material with unique photonic properties essential for future applications involving subdiffractional light traffic and detection in the farinfrared range.

Keywords: s-SNOM; near-field; THz; phonon polariton

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Permalink: https://www.hzdr.de/publications/Publ-32459
Publ.-Id: 32459


Enhanced thermoelectric performance in Mg3+xSb1.5Bi0.49Te0.01 via engineering microstructure through melt-centrifugation

Ozen, M.; Yahyaoglu, M.; Candolfi, C.; Veremchuk, I.; Kaiser, F.; Burkhardt, U.; Snyder, G. J.; Grin, Y.; Aydemir, U.

N-type Zintl phases with earth-abundant and non-toxic constituent elements have attracted intense research interest thanks to their high thermoelectric efficiencies in the mid-temperature range, exemplified by the recently discovered Mg3Sb2 material. In this study, the liquid phase is expelled from the microstructure of the optimized n-type phase Mg3+xSb1.5Bi0.49Te0.01 by applying a melt-centrifugation technique leading to the formation of lattice dislocations, grain boundary dislocations and increasing porosity. Additional phonon scattering mechanisms were introduced in the microstructure through this manufacturing method, resulting in a significant 50% reduction in the total thermal conductivity from ∼1 W m−1 K−1 to ∼0.5 W m−1 K−1 at 723 K. Combined with high power factors, this reduced heat transport leads to a dimensionless thermoelectric figure of merit, zT, value of ∼1.64 at 723 K, 43% higher than the value obtained in untreated Mg3+xSb1.5Bi0.49Te0.01 (zT ∼ 1.14 at 723 K). This peak zT value yields a predicted device ZT of 0.95, and a promising theoretical thermoelectric efficiency of about 12%. These results further underline the great potential of the lightweight Mg3Sb2 material for mid-temperature energy harvesting via thermoelectric effects.

Permalink: https://www.hzdr.de/publications/Publ-32458
Publ.-Id: 32458


FIT4NANO---Focused Ion Technology for functional nanomaterials

Hlawacek, G.; Popovic, M.; Wirtz, T.; Hobler, G.; Höflich, K.; Rius, G.; Gandy, A.

FIT4NANO[1] is a European COST[2] network of researchers with the aim to further
develop focused ion beam (FIB) technology for the fabrication and characterization of
functional nanomaterials. This will help to further strengthen Europe’s leading role in
the evolution of this enabling technology. FIBs are enabling research in numerous
fields including semiconductor technology, quantum sensing and communication,
development of devices based on 2D materials, photonic and phononic crystals,
health and biology as well as raw materials, structural materials and space
applications.
The Action comprises three groups of academic and industrial researchers. First,
there is the group of developers of new focused ion beam sources, optics, detectors
and spectrometers as well as add-ons for in-situ and in-operando experiments. The
second and biggest group is applying FIBs to materials science, health and other
research challenges, utilizing bleeding edge developments provided by group one.
Both groups are supported by the third group that provides the software tools to
understand and predict ion solid interaction effects at the nanoscale.
The instruments and methods developed by the Action are shared with stakeholders
around the globe and a new FIB road-map will showcase current and future develop-
ments of this enabling technology for materials characterization and fabrication.
[1] https://www.fit4nano.eu.
[2] https:/www.cost.eu/actions/CA19140

Keywords: Focused ion beam; nanomaterials; functional nanomaterials

Related publications

  • Poster (Online presentation)
    Euro Nano Forum 2021, 05.-06.05.2021, Braga, Portugal

Permalink: https://www.hzdr.de/publications/Publ-32457
Publ.-Id: 32457


Effect of silver ion implantation on antibacterial ability of polyethylene food packing films

Lu, N.; Chen, Z.; Zhang, W.; Yang, G.; Liu, Q.; Böttger, R.; Zhou, S.; Liu, Y.

Bacterial adhesion on medical instruments’ and food packages’ surfaces causes implanted infections, food spoilage and human disease, therefore attracts a lot of attention in the field of medical and food applications. Containing the initial adhesion of bacteria on the surface of the material plays an important role in reducing potential safety hazards. In this work, we investigate the influence of silver ion implantation with different doses on the antibacterial performance of the polyethylene (PE) films. It is found out that silver ion implantation will not color the PE films but can improve their surface hydrophilicity. The silver-implanted PE films show the ability to inhibit bacterial adhesion and have the bactericidal effect, both of which can be improved with increasing silver implantation dose. This method also proves relatively safe, because the silver ions are relatively stable. The results will introduce potential applications for ion implantation in the food packing and food accessible materials.

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Permalink: https://www.hzdr.de/publications/Publ-32456
Publ.-Id: 32456


An Internet of Things Approach for Water Efficiency: A Case Study of the Beverage Factory

Jagtap, S.; Skouteris, G.; Choudhari, V.; Rahimifard, S.; Nguyen Khanh Duong, L.

There is a lack of knowledge among food manufacturers about adopting the Internet of Things (IoT)-based water monitoring system and its ability to support water minimisation activities. It is therefore necessary to investigate the applicability of IoT-based real-time water monitoring systems in a real food manufacturing environment to pursue water-saving opportunities accordingly. This article aims to propose an architecture of an IoT-based water-monitoring system needed for real-time monitoring of water usage, and address any water inefficiencies within food manufacturing. This article looks at a study conducted in a food beverage factory where an IoT-based real-time water monitoring system is implemented to analyse the complete water usage in order to devise solutions and address water overconsumption/wastage during the manufacturing process. The successful implementation of an IoT-based real-time water monitoring system offered the beverage factory a detailed analysis of the water consumption and insights into the water hotspots that needed attention. This action initiated several water-saving project opportunities, which contributed to the improvement of water sustainability and led to an 11% reduction in the beverage factory’s daily water usage.

Keywords: Internet of Things; Water Monitoring System; Food Beverage Industry; Water Sustainability

Permalink: https://www.hzdr.de/publications/Publ-32455
Publ.-Id: 32455


Reductive immobilization of 99Tc(VII) by FeS2: the effect of marcasite

Rodriguez Hernandez, D. M.; Mayordomo, N.; Schild, D.; Shams Aldin Azzam, S.; Brendler, V.; Müller, K.; Stumpf, T.

Reductive immobilization of 99Tc by a synthetic FeS2 mixture, i.e. marcasite-pyrite 60:40, was studied by a combined approach of batch experiments and powder X-ray diffraction, X-ray photoelectron spectroscopy as well as Raman microscopy. It was found that the FeS2 mixture removes 100% of Tc from the suspension after 7 days in contact at 6.0 < pH ≤ 9.0. The retention outside that pH range was slower and incomplete. Spectroscopic analysis showed that the redox active species at pH 6.0 is Fe2+ as expected from previous works with pyrite. However, at pH 10.0 the surprising oxidation of S2- to SO42- was found responsible for Tc immobilization. This was explained by the high reactivity of marcasite that is easily oxidized to produce H2SO4. Our work provides new molecular insights into the reductive mobilization of Tc(VII) by oxidative formation of sulfate. The assigned molecular reactions may also be relevant for the assessment of other redox reactive contaminants. Technetium re-oxidation essays showed that the fast oxidation of marcasite is associated to the reduction of the remaining Tc(VII) in solution, which gives marcasite the potential of Tc natural remediation since it delays the re-oxidation of Tc(IV).

Keywords: Technetium removal; iron sulfide; iron sulfate; pyrite; remediation

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Permalink: https://www.hzdr.de/publications/Publ-32454
Publ.-Id: 32454


Ekman boundary layers in a fluid filled precessing cylinder

Pizzi, F.; Giesecke, A.; Stefani, F.

The fluid flow in a precessing cylinder is investigated numerically with focus on the Ekman boundary layers in the strongly forced regime. Not surprisingly, in that regime, we find deviations from the linear theory due to significant modifications of the base flow in terms of an axisymmetric geostrophic mode whose rotation is opposite to that of the container. The transition of the bulk flow from a three-dimensional non-axisymmetric base flow to a geostrophic axisymmetric pattern is reflected in the scaling of both the sidewall boundary layers and the Ekman boundary layers on top and bottom of the cylinder. In our simulations, the Ekman layers surpass the threshold of the first instability (class A) and show an increase in the thickness together with a marked vertical flow advection inside the boundary layer in a limited range of the forcing magnitude. However, due to numerical restrictions in our simulations, which limit the range of achievable Ekman numbers, no developed boundary layer turbulence is found. An estimation by extrapolation shows that, for this purpose, Ekman numbers smaller by a factor of two have to be achieved.

Permalink: https://www.hzdr.de/publications/Publ-32453
Publ.-Id: 32453


Overview of the Rossendorf Data Repository (RODARE) at HZDR

Knodel, O.; Fiedler, M.; Gruber, T.

The lecture gives a short introduction of the Rossendorf Data Repository RODARE. Features are highlighted, the typical usage is demonstrated and best practices are provided.

Keywords: Rodare; Data Management

  • Invited lecture (Conferences) (Online presentation)
    RADIATE Data Management and Standards Workshop, 17.03.2021, Lisboa, Portugal

Permalink: https://www.hzdr.de/publications/Publ-32452
Publ.-Id: 32452


Stress-induced modification of gyration dynamics in stacked double-vortex structures studied by micromagnetic simulations

Iurchuk, V.; Kakay, A.; Deac, A. M.

In this paper, using micromagnetic simulations, we investigate the stress-induced frequency tunability of double-vortex nano-oscillators comprising magnetostrictive and non-magnetostrictive ferromagnetic layers separated vertically by a non-magnetic spacer. We show that the the relative orientations of the vortex core polarities p₁ and p₂ have a strong impact on the eigen-frequencies of the dynamic modes. When the two vortices with antiparallel polarities have different eigen-frequencies and the magnetostatic coupling between them is sufficiently strong, the stress-induced magnetoelastic anisotropy can lead to the single-frequency gyration mode of the two vortex cores. Additionally, for the case of parallel polarities, we demonstrate that for sufficiently strong magnetostatic coupling, the magnetoelastic anisotropy leads to the coupled vortex gyration in the stochastic regime and to the lateral separation of the vortex core trajectories. These findings offer a fine control over gyration frequencies and trajectories in vortex-based oscillators via adjustable elastic stress, which can be easily generated and tuned electrically, mechanically or optically.

Keywords: Magnetic vortex; Magnetization dynamics; Magnetoelastic anisotropy; Micromagnetic modelling

Permalink: https://www.hzdr.de/publications/Publ-32451
Publ.-Id: 32451


An Approach to Self-Supervised Object Localisation through Deep Learning Based Classification

Politov, A.

Deep learning has become ubiquitous in science and industry for classifying images or identifying patterns in data. The most widely used approach to training convolutional neural networks is supervised learning, which requires a large set of annotated data. To elude the high cost of collecting and annotating datasets, self-supervised learning methods represent a promising way to learn the common functions of images and videos from large-scale unlabeled data without using human-annotated labels. This thesis provides the results of using self-supervised learning and explainable AI to localise objects in images from electron microscopes. The work used a synthetic geometric dataset and a synthetic pollen dataset. The classifica-tion was used as a pretext task. Different methods of explainable AI were applied: Grad-CAM and backpropagation-based approaches showed the lack of prospects; at the same time, the Extremal Perturbation function has shown efficiency. As a result of the downstream localisation task, the objects of interest were detected with competitive accuracy for one-class images. The advantages and limitations of the approach have been analysed. Directions for further work are proposed.

Keywords: deep learning; self-supervised learning; diamonds; scanning electron microscope; localisation

  • Open Access Logo Master thesis
    TU Dresden, 2021
    Mentor: Peter Steinbach
    76 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-32450
Publ.-Id: 32450


Determination of the froth height as a prerequisite of a model-based flotation control

Rau, F.; Buchmann, M.; Hoang, D. H.; Rudolph, M.; van den Boogaart, K. G.

Flotation represents one of the most important separation processes in the mineral processing industry. By exploiting differences of the surface properties, it enables an effective way for the separation of valuable from gangue material. Through the addition of air to the material pulp it is possible to selectively attach hydrophobic particles to air bubbles and to transport them to the upper end of a flotation cell. The froth phase on top of the pulp is crucial for the generation of a high quality concentrate, as it serves as a cleaning region to remove unselectively entrained particles from the product stream. Therefore, the detailed monitoring and control of this froth phase is a crucial requirement for an efficient and stable process. Flotation represents a complex process, where multiple input variables influence several sub-processes and output parameters. Such a multi-input multi-output problem cannot be efficiently controlled by conventional PIDs.
A model-based predictive controller (MPC) is required to reproduce the complex relations between the various in- and outputs to calculate an optimum set of parameters. For the successful implementation of MPCs the calculation time represents a critical factor. The required complexity of the model and therefore the calculation time can be reduced by measuring relevant process parameters. Such characteristic variables are the density of the pulp, the froth and the pulp height. Nevertheless these information need to be available at all time and as accurate as possible, so the complexity of the MPC is reduced permanently since no further failsafe methods are required.
This contribution focuses on a combination of a radar level meter and a hydrostatic pressure sensor to form a measurement system, being capable of measuring the three mentioned values at once. It is implemented into a pilot flotation plant to investigate its applicability for the concept of a “reduced” MPC. One scope of the investigations is the response of the radar signal to the typical flotation fluid, forming a three-phase systems (solid, liquid, gaseous), and consequently the robustness to disturbances and the reasonable sample rate of the sensor system. Additionally, the pilot plant is equipped with optical sensors to assess the accuracy.

Keywords: Flotation; control; sensor; froth height

  • Lecture (Conference) (Online presentation)
    13th European Congress of Chemical Engineering, 20.-23.09.2021, Frankfurt am Main, Germany

Permalink: https://www.hzdr.de/publications/Publ-32449
Publ.-Id: 32449


Agility of spin Hall nano-oscillators

Trindade Goncalves, F. J.; Hache, T.; Bejarano, M.; Hula, T.; Hellwig, O.; Faßbender, J.; Schultheiß, H.

We investigate the temporal response of constriction-based spin Hall nano-oscillators driven by pulsed stimuli using time-resolved Brillouin light scattering microscopy. The growth rate of the magnetization auto-oscillations, enabled by spin Hall effect and spin orbit torque, is found to vary with the amplitude of the input voltage pulses, as well as the synchronization frequency set by an external microwave input. The combination of voltage and microwave pulses allows to generate auto-oscillation signals with multi-level amplitude and frequency in the time-domain. Our findings suggest that the lead time of processes such as synchronization and logic using spin Hall nano-oscillators can be reduced to the nanosecond time-scale.

Keywords: Spintronics; Magnons; Spin waves; Brillouin scattering & spectroscopy; Microwave techniques

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Permalink: https://www.hzdr.de/publications/Publ-32448
Publ.-Id: 32448


FFTF startup tests - joint publication raw data

Nikitin, E.

Models and results with DYN3D and Serpent (HZDR), and results of PARCS (PSI) and GenFoam (EPFL).

Keywords: SFR; DYN3D; PARCS; GeN-Foam; diffusion solver

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Permalink: https://www.hzdr.de/publications/Publ-32446
Publ.-Id: 32446


Neutronic Modelling of the FFTF Control Rod Worth Measurements with Diffusion Codes

Nikitin, E.; Fridman, E.; Mikityuk, K.; Radman, S.; Fiorina, C.

This paper presents an assessment of three deterministic core simulators with the focus on the neutronic performance in steady-state calculations of small Sodium cooled Fast Reactor cores. The selected codes are DYN3D, PARCS and the novel multi-physics solver GeN-Foam. By using these codes, the multi-group diffusion solutions are obtained for the selected twenty control rod worth measurements performed during the isothermal physics tests of the Fast Flux Test Facility (FFTF). The identical set of homogenized few-group cross sections applied in the calculations is generated with the Serpent Monte Carlo code. The numerical results are compared with each other as well as with the measured values. The obtained numerical results, such as the multiplication factors and control rod worth values, are in good agreement as compared to the experimental data. Furthermore, a comparison of the radial power distributions is presented between DYN3D, PARCS and GeN-Foam. Ultimately, the power distributions are compared to the full core Serpent solution, demonstrating an adequate performance of the selected deterministic tools. In overall, this study presents a verification and validation of the neutronic solvers applied by DYN3D, PARCS and GeN-Foam to steady-state calculations of SFR cores.

Keywords: SFR; DYN3D; PARCS; GeN-Foam; diffusion solver

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Permalink: https://www.hzdr.de/publications/Publ-32445
Publ.-Id: 32445


Identification and characterization of gallium-binding peptides

Schönberger, N.

The present work demonstrates how a peptide-based material can be obtained for the biosorptive recovery of metals from contaminated industrial wastewater. Starting with Phage surface display for the initial identification and optimization of gallium-binding peptides, all the following application-focussed experiments are based on chemically synthesized peptides.
Two chromatography-based biopanning methods for the identification of gallium-binding peptides from a commercial phage display library were developed. Five gallium-binding peptide sequences were identified and evaluated to show good gallium-binding properties.
Furthermore, the biosorption of free gallium and arsenic by gallium-binding bacteriophage clones was investigated. A large influence of the pH-value on the respective interactions was demonstrated.
Mutagenesis experiments were also carried out for a bacteriophage clone expressed peptide, in which a cysteine pair systematically replaced amino acids. Biosorption experiments with the resulting seven different bacteriophage mutants suggested a relationship between the rigidity of the peptide structure and the gallium-binding properties.
In isothermal titration experiments, the thermodynamics of the interaction between gallium and the peptides as chemically synthesized derivatives were characterized, independent of the bacteriophage. The peptides differed strongly in their interaction with gallium, and in some cases, the complex formation with gallium depended strongly on the surrounding buffer conditions.
The peptide with the amino acid sequence NYLPHQSSSPSR has particularly promising gallium-binding properties. Computer modeling suggests the probable structure of the peptide in aqueous solution and postulates a possible binding site for gallium.
The side-selective and covalent immobilization of the peptides on a polystyrene matrix led to the creation of a biocomposite for the biosorptive recovery of gallium. The sorption performance and desorbability of the peptide-based biosorption materials were determined in studies with model solutions and real waters from the semiconductor industry.

Keywords: Phage Surface Display; Gallium; Wastewater treatment; Peptides

  • Doctoral thesis
    TUBAF, 2021
    Mentor: Dr. Katrin Pollmann
    0112 Seiten

Permalink: https://www.hzdr.de/publications/Publ-32444
Publ.-Id: 32444


DNA-Mediated Stack Formation of Nanodiscs

Subramanian, M.; Kielar, C.; Tsushima, S.; Fahmy, K.; Oertel, J.

Membrane-scaffolding proteins (MSPs) derived from apolipoprotein A-1 have become a versatile tool in generating nano-sized discoidal membrane mimetics (nanodiscs) for membrane protein research. Recent efforts have aimed at exploiting their controlled lipid protein ratio and size distribution to arrange membrane proteins in regular supramolecular structures for diffraction studies. Thereby, direct membrane protein crystallization, which has remained the limiting factor in structure determination of membrane proteins, would be circumvented. We describe here the formation of multimers of membrane-scaffolding protein MSP1D1-bounded nanodiscs using the thiol reactivity of engineered cysteines. The mutated positions N42 and K163 in MSP1D1 were chosen to support chemical modification as evidenced by fluorescent labeling with pyrene. Minimal interference with the nanodisc formation and structure was demonstrated by circular dichroism spectroscopy, differential light scattering and size exclusion chromatography. The direct disulphide bond formation of nanodiscs formed by the MSP1D1_N42C variant led to dimers and trimers with low yield. In contrast, transmission electron microscopy revealed that the attachment of oligonucleotides to the engineered cysteines of MSP1D1 allowed the growth of submicron-sized tracts of stacked nanodiscs through the hybridization of nanodisc populations carrying complementary strands and a flexible spacer.

Keywords: membrane-scaffolding protein; nanodisc; membrane protein; lipid bilayer; lipid protein interaction; multimerization; self-assembly; bionanotechnology

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Permalink: https://www.hzdr.de/publications/Publ-32443
Publ.-Id: 32443


Influence of interstitial and substitutional atoms on magnetocaloric effects in RNi compounds

Chzhan, V. B.; Kurganskaya, A. A.; Tereshina, I. S.; Karpenkov, A. Y.; Ovchenkova, I. A.; Tereshina-Chitrova, E. A.; Andreev, A. V.; Gorbunov, D.; Lushnikov, S. A.; Verbetsky, V. N.

The effects of substitutional and interstitial atoms on the magnetic and magnetocaloric properties are investigated for RNi (R is rare earth) compounds attractive for magnetic solid-state cooling at cryogenic temperatures. We focused on combining weakly and highly anisotropic rare earth compounds and obtained GdxDy1-xNi (x = 0.1 and 0.9) compounds and their GdxDy1-xNiH3 hydrides. We observed a considerable decrease in Curie temperatures (TC) in the hydrides GdxDy1-xNiH3 compared to their parent alloys. The magnetocaloric effect (MCE) values of GdxDy1-xNiHy (y = 0 and 3) in the vicinity of TC were obtained and compared with literature data for the final GdNi and DyNi compounds. The maximum specific isothermal entropy changes –ΔsT at μ0ΔH = 5 T were 14.5, 17, and 17.5 J kg−1K−1 for GdNi, Gd0.9Dy0.1Ni, and Gd0.9Dy0.1NiH3, respectively. For DyNi, Gd0.1Dy0.9Ni, and Gd0.1Dy0.9NiH3, they were –ΔsT = 18, 15.5, and 12.5 J kg−1K−1 at μ0ΔH = 5 T, respectively. –ΔsT(H) in Gd0.9Dy0.1NiH3 at T = TC linearly increased in fields up to 7 T, while Gd0.1Dy0.9NiH3 at T ≥ TC showed a plateau-like magnetocaloric effect at μ0ΔH = 5 and 7 T. The observed effects were explained based on altered exchange and magnetocrystalline interactions in the modified compounds.

Permalink: https://www.hzdr.de/publications/Publ-32442
Publ.-Id: 32442


Compensating for artifacts in scanning near-field optical microscopy due to electrostatics

Nörenberg, T.; Wehmeier, L.; Lang, D.; Kehr, S. C.; Eng, L. M.

Nanotechnology and modern materials science demand reliable local probing techniques on the nanoscopic length scale. Most commonly, scanning probe microscopy methods are applied in numerous variants and shades, for probing the different sample properties. Scattering scanning near-field optical microscopy (s-SNOM), in particular, is sensitive to the local optical response of a sample, by scattering light off an atomic force microscopy (AFM) tip, yielding a wavelength-independent lateral resolution in the order of ∼10 nm. However, local electric potential variations on the sample surface may severely affect the probe-sample interaction, thereby introducing artifacts into both the optical near-field signal and the AFM topography. On the other hand, Kelvin-probe force microscopy (KPFM) is capable of both probing and compensating such local electric potentials by applying a combination of ac and dc-voltages to the AFM tip. Here, we propose to combine s-SNOM with KPFM in order to compensate for undesirable electrostatic interaction, enabling the in situ probing of local electric potentials along with pristine optical responses and topography of sample surfaces. We demonstrate the suitability of this method for different types of materials, namely, metals (Au), semiconductors (Si), dielectrics (SiO2), and ferroelectrics (BaTiO3), by exploring the influence of charges in the systems as well as the capability of KPFM to compensate for the resulting electric force interactions.

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Permalink: https://www.hzdr.de/publications/Publ-32441
Publ.-Id: 32441


Experimental assessment of inter-centre variation in stopping-power and range prediction in particle therapy

Peters, N.; Wohlfahrt, P.; Dahlgren, C. V.; de Marzi, L.; Ellerbrock, M.; Fracchiolla, F.; Free, J.; Goma, C.; Gora, J.; Jensen, M. F.; Kajdrowicz, T.; Mackay, R.; Molinelli, S.; Rinaldi, I.; Rompokos, V.; Siewert, D.; van der Tol, P.; Vermeren, X.; Nyström, H.; Lomax, T.; Richter, C.

Purpose: Experimental assessment of inter-centre variation and absolute accuracy of stopping-power ratio (SPR) prediction within 17 particle therapy centres of the European Particle Therapy Network.
Material and Methods: A head and body phantom with seventeen tissue-equivalent materials were scanned consecutively at the participating centres using their individual clinical CT scan protocol and translated into SPR with their in-house CT-number-to-SPR conversion. Inter-centre variation and absolute accuracy in SPR prediction were quantified for three tissue groups: lung, soft tissues and bones. The integral effect on range prediction for typical clinical beams traversing different tissues was determined for representative beam paths for the treatment of primary brain tumours as well as lung and prostate cancer.
Results: An inter-centre variation in SPR prediction (2σ) of 8.7%, 6.3% and 1.5% relative to water was determined for bone, lung and soft-tissue surrogates in the head setup, respectively. Slightly smaller variations were observed in the body phantom (6.2%, 3.1%, 1.3%). This translated into inter-centre variation of integral range prediction (2σ) of 2.9%, 2.6% and 1.3% for typical beam paths of prostate-, lung- and primary brain-tumour treatments, respectively. The absolute error in range exceeded 2% in every fourth participating centre. The consideration of beam hardening and the execution of an independent HLUT validation had a positive effect, on average.
Conclusion: The large inter-centre variations in SPR and range prediction justify the currently clinically used margins accounting for range uncertainty, which are of the same magnitude as the inter-centre variation. This study underlines the necessity of higher standardisation in CT-number-to-SPR conversion.

Permalink: https://www.hzdr.de/publications/Publ-32440
Publ.-Id: 32440


Broadband frequency filters with quantum dot chains

Ehrlich, T.; Schaller, G.

Two-terminal electronic transport systems with a rectangular transmission can violate standard thermodynamic uncertainty relations. This is possible beyond the linear response regime and for parameters that are not accessible with rate equations obeying detailed-balance. Looser bounds originating from fluctuation theorem symmetries alone remain respected. We demonstrate that optimal finite-sized quantum dot chains can implement rectangular transmission functions with high accuracy and discuss the resulting violations of standard thermodynamic uncertainty relations as well as heat engine performance.

Keywords: fluctuation theorems; thermodynamic uncertainty relation; Levitov-Lesovik formula; transmission; reaction-coordinate mapping

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Permalink: https://www.hzdr.de/publications/Publ-32439
Publ.-Id: 32439


Imaging and milling resolution of light ion beams in modern FIBs

Mazarov, P.; Pilz, W.; Meyer, F.; Richter, T.; Klingner, N.; Bischoff, L.; Hlawacek, G.

Light ions are of increasing interest by application of focused ion beam (FIB) techniques due to the available high beam resolution in the nanometer range and their special chemical and physical behavior in the substrate [1, 2]. We compare helium and neon ion beams from a helium ion microscope with ion beams such as lithium, boron, and silicon, obtained from a mass-separated FIB using a liquid metal alloy ion source (LMAIS) with respect to the imaging and milling resolution, as well as the current stability [3]. While He+ offers, experimentally and in simulations, the smallest minimum trench width, light ion species such as Li+ from a LMAIS [4] offer higher milling rates and ion currents while outperforming the milling resolution of Ne+ from a gas field ion source. The comparison allows one to select the best possible ion species for the specific demands in terms of resolution, beam current, and volume and time for milling.

References
[1] L. Bischoff et al., Appl. Phys. Rev. 3 021101 (2016).
[2] P. Mazarov et al., Phys. Usp. 63 1219–1255 (2020).
[3] N. Klingner et al., Beilstein J. Nanotechnol. 11 1742–1749 (2020).
[4] W. Pilz et al., JVSTB 37 021802 (2019).

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  • Lecture (Conference) (Online presentation)
    Virtual 13th Annual FIB SEM Meeting, 29.04.2021, Online, Online

Permalink: https://www.hzdr.de/publications/Publ-32438
Publ.-Id: 32438


The Mu2e experiment at Fermilab

Müller, S.; Ferrari, A.; Knodel, O.; Rachamin, R.

Presentation in parallel session "Detector Systems (T19.1)" at 2021 spring meeting of German Physical Society (DPG), section "Particle Physics"

Keywords: Mu2e; DPG; Charged Lepton Flavor Violation

  • Lecture (Conference) (Online presentation)
    2021 spring meeting of German Physical Society (DPG), section "Particle Physics", 15.-19.03.2021, Dortmund (virtual), Germany

Permalink: https://www.hzdr.de/publications/Publ-32437
Publ.-Id: 32437


Demonstration of a laser-driven, narrow spectral bandwidth x-ray source for collective x-ray scattering experiments

Macdonald, M. J.; Saunders, A. M.; Bachmann, B.; Bethkenhagen, M.; Divol, L.; Doyle, M. D.; Fletcher, L. B.; Glenzer, S. H.; Kraus, D.; Landen, O. L.; Lefevre, H. J.; Klein, S. R.; Neumayer, P.; Redmer, R.; Schörner, M.; Whiting, N.; Falcone, R. W.; Döppner, T.

X-ray Thomson scattering (XRTS) is a powerful diagnostic technique that involves an x-ray source interacting with a dense plasma sample,
resulting in a spectrum of elastically and inelastically scattered x-rays. Depending on the plasma conditions, one can measure a range of
parameters from the resulting spectrum, including plasma temperature, electron density, and ionization state. To achieve sensitivity to collective
electron oscillations, XRTS measurements require limited momentum transfer where the spectral separation of elastic and inelastic scattering
is small. Such measurements require an x-ray probe source with a narrow bandwidth in order to reduce the spectral overlap between
scattering contributions, allowing for the different features to be more precisely deconvolved. In this investigation, we discuss the theory
behind how the bandwidth for a common XRTS probe, Zn He-a emission at 9 keV, can be reduced using a Cu K-edge filter. Proof-of-principle
experiments conducted at the OMEGA laser facility confirm that this is an effective method for attenuating the higher energy He-a peak in
the Zn emission spectrum. Calibration measurements at the National Ignition Facility show a reduction in spectral bandwidth from 87 eV to
48 eV when using the Cu filter, which will be important to improve the spectral resolution of future XRTS measurements that will probe plasmon
oscillations in strongly compressed plasmas of low-Z materials at densities of tens of g/cm3.

Permalink: https://www.hzdr.de/publications/Publ-32436
Publ.-Id: 32436


DFT/DFT-MD IPD Publication Data

Böhme, M.
Supervisor: Vorberger, Jan; Supervisor: Militzer, Burkhard; Researcher: Massacrier, Gerard; Researcher: Soubiran, Francois

Average atom (AA) models allow one to efficiently compute electronic and optical properties of materials over a wide range of conditions and are often employed to interpret experimental data. However, at high pressure, predictions from AA models have been shown to disagree with results from ab initio computer simulations. We represent a new innovative AA model, AvIon, that computes the electronic eigenstates with novel boundary conditions within the ion sphere. Bound and free states are derived consistently. We drop the common AA assumption that the free-particle spectrum starts at the potential threshold, which we found to be incompatible with ab initio calculations. We perform ab initio simulations of crystalline and liquid carbon and aluminum over a wide range of densities and show that the computed band structure is in very good agreement with predictions from AvIon.

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Permalink: https://www.hzdr.de/publications/Publ-32435
Publ.-Id: 32435


Implicit reduced Vlasov–Fokker–Planck–Maxwell model based on high-order mixed elements

Nikl, J.; Göthel, I.; Kuchařík, M.; Weber, S.; Bussmann, M.

etailed description of the transport processes in plasma is crucial for many disciplines. When the mean-free-path of the electrons is comparable or exceeds a characteristic length scale of the plasma profile, non-local behavior can be observed. Predictions of the diffusion theory are not valid and non-local electric and magnetic fields are generated. Kinetic modeling of these phenomena on time scales several orders of magnitude longer than the electron–electron collision time has proven to be cumbersome due to prohibitive requirements on the time step and violation of the conservation laws in the classical explicit Vlasov–Fokker–Planck methods. Therefore, a multi-dimensional conservative implicit Vlasov–Fokker–Planck–Maxwell method is proposed, where the distribution function is approximated by a truncated Cartesian tensor expansion. The electric and magnetic fields are modeled self-consistently, describing the generation process and emergence of non-locality in detail. Mixed finite elements are employed in space and the velocity dimension is discretized by staggered finite differences. Conservation properties are proved theoretically and the overall features are benchmarked on a series of physically representative problems. The second order convergence in velocity and the spatial order proportional to the polynomial order of the finite elements is shown. Further possible extensions of the method are discussed.

Keywords: plasma; simulation; vlasov; focker-planck; numerical methods; implicit; collisions

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-32434
Publ.-Id: 32434


SPX Benchmark Part I: Results of Static neutronics -- HZDR results

Nikitin, E.; Fridman, E.

DYN3D and Serpent calculations (inputs and results) of the SPX Benchmark Part I: Results of Static neutronics.

Keywords: DYN3D; Serpent; Superphénix; Neutronics

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Permalink: https://www.hzdr.de/publications/Publ-32433
Publ.-Id: 32433


ESFR-SMART WP1.2.2 dataset - DecayHeat

Fridman, E.

I/O for ESFR-SMART WP1.2.2  (DecayHeat)

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Permalink: https://www.hzdr.de/publications/Publ-32432
Publ.-Id: 32432


Static Density Response of the Warm Dense Electron Gas beyond Linear Response Theory: Excitation of Harmonics

Böhme, M.; Dornheim, T.; Moldabekov, Z.; Vorberger, J.; Bonitz, M.

Experimental diagnostics as well as theoretical modeling of warm
dense matter (WDM) heavily rely on linear response theory.
However, Dornheim et. al. [Phys. Rev. Lett.125, 085001 (2020)]
showed that assuming the linear regime may not always be
justified in experiments studying WDM. In addition, the
intentional driving of non-linear effects should make new insight
into many-particle effects possible. We use ab initio Path-Integral
Monte-Carlo (PIMC) to obtain exact results for a harmonically
perturbed homogeneous electron gas. A thorough analysis for
different perturbation amplitudes is carried out. The
corresponding density response reveals resonances at the higher
harmonics of the perturbation wave vector. Analyzing the induced
density response as a function of the perturbation amplitude
shows the importance of the cubic response at the first harmonic
and of the quadratic response at the second harmonic.

Keywords: Warm Dense Matter; Path-Intergral Monte-Carlo

  • Poster (Online presentation)
    APS March Meeting, 15.-19.03.2021, Washington DC, USA
  • Open Access Logo Lecture (Conference)
    Division of Plasma Physics Meeting 2021, 08.-12.11.2021, Pittsburgh, PA, USA
  • Open Access Logo Poster (Online presentation)
    MML - "From Matter to Materials and Life", 22.-24.11.2021, Online, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-32431
Publ.-Id: 32431


SPX-StartUp-ATHLET-StandAlone

Di Nora, V. A.

SPX StartUp tests: ATHLET-StandAlone models

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Permalink: https://www.hzdr.de/publications/Publ-32430
Publ.-Id: 32430


Evaluation of the ESFR End of Equilibrium Cycle State: Spatial Distributions of Reactivity Coefficients

Baker, U.; Margulis, M.; Shwageraus, E.; Fridman, E.; Jiménez-Carrascosa, A.; García-Herranz, N.; Cabellos, O.; Gregg, R.; Krepel, J.

The Horizon 2020 ESFR-SMART project investigates the behaviour of the commercial-size European Sodium-cooled Fast Reactor (ESFR) throughout its lifetime. This paper reports work focused on the End of Equilibrium Cycle (EOEC) loading of the ESFR, including neutronic analysis, core- and zone-wise reactivity coefficients, and more detailed local mapping of important safety-relevant parameters. Sensitivity and uncertainty analysis on these parameters have also been performed and a detailed investigation into decay heat mapping carried out.
Due to the scope of this work the results have been split into three papers. The nominal operating conditions and both zone-wise and local mapping of reactivity coefficients are considered in this paper; the sensitivity and uncertainty analysis are detailed in Margulis et al. and the decay heat mapping calculations are reported in Jimenez-Carrascosa et al. The work was performed across four institutions using both continuous-energy Monte Carlo and deterministic reactor physics codes. A good agreement is observed between the methods, verifying
the suitability of these codes for simulation of large, complicated reactor configurations; and giving confidence in the results for the most limiting ESFR EOEC core state for safety analysis. The results from this work will inform the transient calculations planned for the next stage of work on the ESFR, allowing for more in-depth studies to be performed on the multiphysics behaviour of the reactor.

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Permalink: https://www.hzdr.de/publications/Publ-32429
Publ.-Id: 32429


Superphénix Benchmark Part II: Transient Results

Ponomarev, A.; Mikityuk, K.; Fridman, E.; Di Nora, V. A.; Bubelis, E.; Schikorr, M.

The paper presents a transient simulation phase of the new benchmark on a large sodium fast reactor core. This phase of the benchmark was devoted to the modelling of selected operational transients performed during start-up tests of French SFR Superphénix in order to evaluate its reactivity characteristics and core response to certain perturbations. Six operational transients were selected for the analysis. The specification of a simplified thermal hydraulic model equipped with point kinetics reactivity data and boundary conditions for the selected transients are given in the paper and the results of simulations with several system codes are reported. The study uses the results of the reference Serpent 2 Monte Carlo solution obtained during the first phase of the benchmark related to static neutronic characterization of the core. The developed model contains necessary thermal hydraulic description of primary system components and assumptions to account for thermal expansion reactivity feedbacks from in-reactor structures, neutron kinetics parameters, power distribution and reactivity coefficients. Thus the transient benchmark appears as an effective tool for validation and cross comparisons of system codes including approbation and comparison of different modelling features for thermal expansion of the in-reactor structures, giving a reference core behaviour with use of relatively simple models. The results of the modelling demonstrate a reasonable agreement between all solutions and with the experimentally measured evolution of the core parameters. Particular discrepancies with experimental data could not be resolved using the simplified benchmark model and available experimental data reconstructed from the published analysis of start-up tests. Because of that, the future steps for achieving the improved agreement between the simulated results and the experimental data were proposed.

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Permalink: https://www.hzdr.de/publications/Publ-32428
Publ.-Id: 32428


Decay heat characterization for the European Sodium Fast Reactor

Jiménez-Carrascosa, A.; García-Herranz, N.; Krepel, J.; Margulis, M.; Davies, U.; Shwageraus, E.; Fridman, E.; Gregg, R.

In this work a detailed assessment of the decay heat power for the commercial-size European Sodium-cooled Fast Reactor (ESFR) at the end of its equilibrium cycle has been performed. The summation method has been used to compute very accurate spatial- and time-dependent decay heat by employing state-of-the-art coupled transport-depletion computational codes and nuclear data. This detailed map provides basic information for subsequent transient calculations of the ESFR. A comprehensive analysis of the decay heat has been carried out and interdependencies among decay heat and different parameters characterizing the core state prior to shutdown, such as discharge burnup or type of fuel material, have been identified. That analysis has served as a basis to develop analytic functions to reconstruct the spatial-dependent decay heat power for the ESFR for cooling times within the first day after shutdown.

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Permalink: https://www.hzdr.de/publications/Publ-32427
Publ.-Id: 32427


Superphénix Benchmark Part I: Results of Static neutronics

Ponomarev, A.; Mikityuk, K.; Zhang, L.; Nikitin, E.; Fridman, E.; Álvarez-Velarde, F.; Romojaro-Otero, P.; Jiménez-Carrascosa, A.; García-Herranz, N.; Lindley, B.; Davies, U.; Seubert, A.; Henry, R.

n the paper, the specification of a new neutronics benchmark for a large Sodium cooled Fast Reactor
(SFR) core and results of modelling by different participants are presented. The neutronics benchmark describes
the core of the French sodium cooled reactor Superphénix at its startup configuration, which in particular was
used for experimental measurement of reactivity characteristics. The benchmark consists of the detailed
heterogeneous core specification for neutronic analysis and results of the reference solution. Different core
geometries and thermal conditions from cold “as fabricated” up to full power were considered. The reference
Monte Carlo solution of Serpent 2 includes data on multiplication factor, power distribution, axial and radial
reaction rates distribution, reactivity coefficients and safety characteristics, control rods worth, kinetic data.
The results of modelling with seven other solutions using deterministic and Monte Carlo methods are also
presented and compared to the reference solution. The comparisons results demonstrate appropriate
agreement of evaluated characteristics. The neutronics results will be used in the second phase of the
benchmark for evaluation of transient behaviour of the core.

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Permalink: https://www.hzdr.de/publications/Publ-32426
Publ.-Id: 32426


Unser Rohstoffbedarf – Forschung für eine nachhaltige Rohstoffsuche in Europa im Spannungsfeld von Umwelt und Wirtschaft

Pospiech, S.

Vortrag für Schüler des Heidelberger Life-Science Labs (HLSL) am Deutschen Krebsforschungszentrum (DKFZ) im Rahmen der Freitagsvorträge, einer öffentlichen Vortragsreihe

Keywords: Schüler; Rohstoffe; Critical raw materials; Exploration; EU-Projekt

  • Lecture (others) (Online presentation)
    Freitagsvorträge des Heidelberger Life-Science Labs, 12.03.2021, Heidelberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-32425
Publ.-Id: 32425


Dissolution-based uptake of CeO2 nanoparticles by fresh water shrimp – A dual-radiolabelling study of the fate of anthropogenic cerium in water organisms

Schymura, S.; Rybkin, I.; Uygan, S. S. S.; Drev, S.; Podlipec, R.; Rijavec, T.; Mansel, A.; Lapanje, A.; Franke, K.; Strok, M.

Manufactured nanoparticles, such as CeO2, give rise to novel risks when released into the environment. To assess these risks it is important to quantify the nanoparticle mass flows, as well as their speciation and the mechanisms of their transformation. We developed an innovative dual-radiolabelling strategy for CeO2 nanoparticles using neutron activation and in-diffusion labelling to radiolabel CeO2 nanoparticles with both Ce-141 and Ce-139. The different distribution of the radiolabels in the particles does not only allow easy dose determination in uptake studies but also enables us to track the uptake pathways of the anthropogenic cerium. By measuring the activity as well as the isotope ratio we tracked the uptake, transformation and excretion of CeO2 nanoparticles in freshwater shrimp. We found that 99.99 % of the uptaken particles are excreted, leaving the gut with excrement. The remaining 0.01 % was internalized via a dissolution based pathway and accumulated in the hepatopancreas of the shrimp at a dose range of pg CeO2 per shrimp. Most importantly, our results show that dissolution is not only coincidental but instrumental in the uptake of the cerium into the internal organs of the shrimp.

Keywords: CeO2 nanoparticles; radiolabelling; Uptake; Dissoltution

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Permalink: https://www.hzdr.de/publications/Publ-32424
Publ.-Id: 32424


Particle resuspension from monolayered deposits: evidence of collision-induced phenomenon

Lecrivain, G.; Banari, A.; Henry, C.; Hampel, U.

We present here new experimental and numerical results for the resuspension of microscopic glass particles from a monolayer bed into a turbulent gas flow. With an intermediate surface coverage, here about 10 % of the field of
view, we report two distinct detachment mechanisms: collision-induced resuspension at low flow velocities and individual particle resuspension at higher fluid velocities.

Keywords: Particle resuspension

  • Invited lecture (Conferences)
    Institute Seminar at Institut National de Recherche en Sciences et Technologies du Numérique (INRIA), 11.03.2021, Sophia Antipolis - Méditerranée, France

Permalink: https://www.hzdr.de/publications/Publ-32423
Publ.-Id: 32423


Data-Driven Shadowgraph Simulation of a 3D Object

Willmann, A.; Stiller, P.; Debus, A.; Irman, A.; Pausch, R.; Chang, Y.-Y.; Bussmann, M.; Hoffmann, N.

In this work we propose a deep neural network based surrogate model for a plasma shadowgraph - a technique for visualization of perturbations in a transparent medium. We are substituting the numerical code by a computationally cheaper projection based surrogate model that is able to approximate the electric fields at a given time without computing all preceding electric fields as required by numerical methods. This means that the projection based surrogate model allows to recover the solution of the governing 3D partial differential equation, 3D wave equation, at any point of a given compute domain and configuration without the need to run a full simulation. This model has shown a good quality of reconstruction in a problem of interpolation of data within a narrow range of simulation parameters and can be used for input data of large size.

  • Contribution to proceedings
    ICLR 2021 - Ninth International Conference on Learning Representations, 03.-07.05.2021, Vienna, Austria

Permalink: https://www.hzdr.de/publications/Publ-32422
Publ.-Id: 32422


Robust Magnetoelectric Effect in Decorated Graphene/In2Se3 Heterostructure

Shang, J.; Tang, X.; Gu, Y.; Krasheninnikov, A.; Picozzi, S.; Chen, C.; Kou, L.

The magnetoelectric effect is a fundamental physical phenomenon that synergizes electric and magnetic degrees of freedom to generate distinct material responses like electrically tuned magnetism, which serves as a key foundation of the emerging field of spintronics. Here, we show by first-principles studies that ferroelectric (FE) polarization of an In2Se3 monolayer can modulate the magnetism of an adjacent transition-metal (TM)-decorated graphene layer via a ferroelectrically induced electronic transition. The TM nonbonding d-orbital shifts downward and hybridizes with carbon-p states near the Fermi level, suppressing the magnetic moment, under one FE polarization, but on reversed FE polarization this TM d-orbital moves upward, restoring the original magnetic moment. This finding of robust magnetoelectric effect in the TM-decorated graphene/In2Se3 heterostructure offers powerful insights and a promising avenue for experimental exploration of ferroelectrically controlled magnetism in two-dimensional (2D) materials.

Keywords: 2D materials; First-principles calculations

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Permalink: https://www.hzdr.de/publications/Publ-32421
Publ.-Id: 32421


Formation of Highly Doped Nanostripes in 2D Transition Metal Dichalcogenides via a Dislocation Climb Mechanism

Lin, Y.; Karthikeyan, J.; Chang, Y.; Li, S.; Kretschmer, S.; Komsa, H.; Chiu, P.; Krasheninnikov, A.; Suenaga, K.

Doping of materials beyond the dopant solubility limit remains a challenge, especially when spatially nonuniform doping is required. In 2D materials with a high surface‐to‐volume ratio, such as transition metal dichalcogenides, various post‐synthesis approaches to doping have been demonstrated, but full control over spatial distribution of dopants remains a challenge. A post‐growth doping of single layers of WSe2 is performed by adding transition metal (TM) atoms in a two‐step process, which includes annealing followed by deposition of dopants together with Se or S. The Ti, V, Cr, and Fe impurities at W sites are identified by using transmission electron microscopy and electron energy loss spectroscopy. Remarkably, an extremely high density (6.4–15%) of various types of impurity atoms is achieved. The dopants are revealed to be largely confined within nanostripes embedded in the otherwise pristine WSe2. Density functional theory calculations show that the dislocations assist the incorporation of the dopant during their climb and give rise to stripes of TM dopant atoms. This work demonstrates a possible spatially controllable doping strategy to achieve the desired local electronic, magnetic, and optical properties in 2D materials.

Keywords: 2D materials; doping; first-principles simulations

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Permalink: https://www.hzdr.de/publications/Publ-32420
Publ.-Id: 32420


Atomistic Simulations of Defect Production in Monolayer and Bulk Hexagonal Boron Nitride under Low- and High-Fluence Ion Irradiation

Ghaderzadeh, S.; Kretschmer, S.; Ghorbani Asl, M.; Hlawacek, G.; Krasheninnikov, A.

Controlled production of defects in hexagonal boron nitride (h-BN) through ion irradiation has recently been demonstrated to be an effective tool for adding new functionalitites to this material such as single photon generation and for developing optical quantum applications. Using analytical potential molecular dynamics, we study the mechanisms of vacancy creation in single- and multi-layer h-BN under low- and high-fluence ion irradiation. Our results quantify the densities of defects produced by noble gas ions in a wide range of ion energies and elucidate the types and distribution of defects in the target. The simulation data can directly be used to guide the experiment aimed at the creation of defects of particular types in h-BN targets for single-photon emission, spin-selective optical transitions and other applications by using beams of energetic ions.

Keywords: Two-dimensional materials; ion irradiation; atomistic simulations; defects

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Permalink: https://www.hzdr.de/publications/Publ-32419
Publ.-Id: 32419


Supporting data to the publication: Impact of surface charge on the motion of light-activated Janus micromotors

Baraban, L.

These video set (Video 1-5) summarizes the all experimental results. these videos were analyzed to get the dynamics of the Janus particle in the article further reflected in the figures.

Keywords: Janus particles; particle tracking

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Permalink: https://www.hzdr.de/publications/Publ-32418
Publ.-Id: 32418


Data (15/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

- Simulationsdaten für den ROFEX 1 zum Vergleich unterschiedlicher Detektorgrößen mit dem USRBIN-Kommando

Keywords: Electron beam; Beam position; FLUKA; ROFEX

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Permalink: https://www.hzdr.de/publications/Publ-32417
Publ.-Id: 32417


Data (14/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

- Simulationsdaten für den ROFEX 1 zum Vergleich unterschiedlicher Detektorgrößen mit dem USRBIN-Kommando

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32416
Publ.-Id: 32416


Data (13/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

- Simulationsdaten für den ROFEX 1 mit dem FLUKA-USRBDX-Kommando (Ro1_Pos_*)
- Simulationsdaten für den ROFEX 1 mit dem USRBIN-Kommando zum Vergleich unterschiedlicher Detektorgrößen

Keywords: ROFEX; Electron beam; FLUKA; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32415
Publ.-Id: 32415


Data (12/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

- Simulationsdaten für den ROFEX 1 mit dem USRBDX-FLUKA-Kommando

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32414
Publ.-Id: 32414


Data (11/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

- Pos_* Simulationsdaten für den ROFEX 3 für verschiedene USRBINs mit EMFCUT=10keV
- Ro1_* Simulationsdaten für den ROFEX 1 mit EMFCUT = 100keV

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32413
Publ.-Id: 32413


Data (10/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschiedener USRBDX-Strukturen auf den Elektronenfluss.

Keywords: FLUKA; ROFEX; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32412
Publ.-Id: 32412


Data (9/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandtd, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschiedener USRBDX-Strukturen auf den Elektronenfluss.

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32411
Publ.-Id: 32411


Data (8/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschiedener USRBDX-Strukturen auf den Elektronenfluss.

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32410
Publ.-Id: 32410


Data (7/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschiedener USRBDX-Strukturen auf den Elektronenfluss.

Keywords: ROFEX; FLUKA; Electron Beam

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Permalink: https://www.hzdr.de/publications/Publ-32409
Publ.-Id: 32409


Data (6/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschiedener USRBDX-Strukturen auf den Elektronenfluss.

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32408
Publ.-Id: 32408


Data (5/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschiedener USRBDX-Strukturen auf den Elektronenfluss.

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32407
Publ.-Id: 32407


Data for (4/15): Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Untersuchung des Einflusses verschieder USRBDX-Strukturen auf den Elektronenfluss.

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32406
Publ.-Id: 32406


Data (3/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Pos_17* enthält die Elektronenflusssimulationen für den ROFEX 3 mit EMFCUT=10keV

Keywords: ROFEX; Electron beam; FLUKA; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32405
Publ.-Id: 32405


Data (2/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

FLUKA-Daten für den ROFEX 3:
- Pos_18_* wurden zur Erstellung des Gleichungssystems Elektronenfluss(r, phi) verwendet.

Messdaten für den ROFEX 1:
-DC_4_2kHz* aufgenommen mit dem Präzisionsmessgerät LTT24

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32404
Publ.-Id: 32404


Data (1/15) for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Simulationsdaten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Daten für den ROFEX 3:
- Pos_17 bzw. Pos_19 wurden zur Bestimmung des Gleichungssystems Elektronenfluss(r, phi) verwendet
- groessenvgl diente dem Vergleich verschiedener USRBIN-Größen bei den ROFEX-3-Simulationen
- USRBIN70_Ro3 zeigte den Elektronenfluss an einer weiteren Detektorposition
- 66_21_Ro3 untersuchte einen leicht verschobenen USRBIN 66.

Daten für den ROFEX 1:
-Ro1_USRBIN_gekippt wurde für den Vergleich von USRBINs mit unterschiedlichen Winkeln verwendet

Keywords: ROFEX; FLUKA; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32403
Publ.-Id: 32403


Scripts for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Skripte und FLUKA-Eingangsdateien ohne Strahlposition für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Keywords: FLUKA; ROFEX; Electron beam; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32402
Publ.-Id: 32402


Results for: Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, M.
Supervisor: Barthel, Frank

Auswertungen der Daten für die Masterarbeit Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Keywords: Electron beam; ROFEX; Beam position

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Permalink: https://www.hzdr.de/publications/Publ-32401
Publ.-Id: 32401


Analysen zur Anwendbarkeit verschiedener Strahlbahn-Monitoring-Konzepte für die ultraschnelle Röntgencomputertomografie

Brandt, Mira

Deutsch:

Die vorliegende Arbeit beschäftigt sich mit der Suche nach einem für die ultraschnelle Röntgencomputertomografie geeigneten Strahlbahn-Monitoring-Konzept. Mehrere Sekundäreffekte, die durch den Primärelektronenstrahl ausgelöst werden, wurden analysiert und aus ihnen die Rückstreuelektronenverteilung als Parameter für das Monitoring ausgewählt. Auf Grundlage von für verschiedene Strahlpositionen durchgeführten Simulationen des Elektronenflusses mit dem Monte-Carlo-Simulationspaket FLUKA wurden geeignet positionierte Kupferelektroden als Elektronendetektoren verwendet. Mit diesen Elektroden wurden Testmessungen durchgeführt. Die aufgenommenen Spannungskurven wurden mit den simulierten Elektronenflusskurven verglichen, wobei die Kurvenformen ähnlich waren. Das Spannungssignal wurde dagegen von den Simulationen unterschätzt. Da es während der ersten Messungen zu Spannungsüberschlägen kam, wurde ein zweites, verbessertes System entwickelt, das diese vermeiden soll.

English:

This thesis shows the search for a beam path monitoring concept suitable for ultrafast X-ray computed tomography. Several secondary effects triggered by the primary electron beam were analysed and from them the backscattered electron distribution was selected as a parameter to monitor the beam position. Based on simulations of the electron fluence, carried out for different beam positions with the Monte Carlo simulation package FLUKA, well positioned copper electrodes were used as electron detectors. Test measurements were done with these electrodes. The recorded voltage curves were compared with the simulated electron fluence curves which showed that the curve shapes are similar. However, the voltage signal was underestimated by the simulations. Because voltage flashovers occurred during the first measurements, a second improved system was developed to avoid them.

Keywords: Electron beam; Computed tomography; Beam position; Beam monitoring; ROFEX

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  • Master thesis
    TU Dresden, 2021
    Mentor: Dr.-Ing. Frank Barthel
    151 Seiten

Permalink: https://www.hzdr.de/publications/Publ-32400
Publ.-Id: 32400


Towards high-rate RPC-based thermal neutron detectors using low-resistivity electrodes

Margato, L. M. S.; Morozov, A.; Blanco, A.; Fonte, P.; Lopes, L.; Saraiva, J.; Zeitelhack, K.; Hall-Wilton, R.; Höglund, C.; Lai, C.-C.; Robinson, L.; Svensson, P.; Naumann, L.; Römer, K.; Stach, D.; Wilpert, T.

We present experimental results on the counting rate measurements for several single-gap ¹⁰B‑RPCs with anodes made from standard float glass, low-resistivity glass and ceramic. The measurements were performed at the V17 monochromatic neutron beamline (3.35 Å) at the Helmholtz-Zentrum Berlin. For the ¹⁰B-RPCs with 0.28 mm thick float glass a maximum counting rate density of about 8×10³ Hz/cm² was obtained. In the case of low resistivity glass and ceramic, the counting rate density did not deviate from linear dependence on the neutron flux up to the maximum flux available at this beamline and exceeded a value of 3×10⁴ Hz/cm².

Keywords: RPC; neutron detection

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Permalink: https://www.hzdr.de/publications/Publ-32399
Publ.-Id: 32399


Research data "Fluorination of graphene leads to susceptibility for nanopore formation by highly charged ion impact"

Creutzburg, S.; Hübner, R.; Facsko, S.

The depository contains STEM images, experimental data from charge exchange measurements and data from charge exchange simulations.

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Permalink: https://www.hzdr.de/publications/Publ-32397
Publ.-Id: 32397


Fluorination of graphene leads to susceptibility for nanopore formation by highly charged ion impact

Creutzburg, S.; Mergl, M.; Hübner, R.; Jirka, I.; Erb, D.; Heller, R.; Niggas, A.; Grande, P. L.; Aumayr, F.; Wilhelm, R. A.; Kalbac, M.; Facsko, S.

The formation of nanopores by highly charged ion impacts on freestanding fluorine-functionalized graphene is demonstrated. The process is driven by potential sputtering, which becomes active by changing the semi-metallic properties of graphene into a strongly insulating state by fluorination. The interaction of fluorographene with highly charged ions is also studied in terms of charge exchange and kinetic energy loss. A higher number of captured electrons and a larger kinetic energy loss than in pristine graphene are observed, which can be well explained by an increase in the ion's neutralization length and in the atomic areal density of the target, respectively. Using a computer code based on a time-dependent scattering potential model, a connection between the efficiency of charge exchange and the fluorine coverage is revealed. Our results suggest a competition of two distinct nanostructure formation processes leading either to pore formation or fluorine desorption.

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Permalink: https://www.hzdr.de/publications/Publ-32396
Publ.-Id: 32396


Flexible magnetoreceptor with tunable intrinsic logic for on-skin touchless human-machine interfaces

Makushko, P.; Oliveros Mata, E. S.; Canon Bermudez, G. S.; Hassan, M.; Laureti, S.; Rinaldi, C.; Fagiani, F.; Barucca, G.; Schmidt, N.; Zabila, Y.; Kosub, T.; Illing, R.; Volkov, O.; Vladymyrskyi, I.; Faßbender, J.; Albrecht, M.; Varvaro, G.; Makarov, D.

Artificial magnetoception is a new and yet to be explored path for humans to interact with our surroundings. This technology is enabled by thin film magnetic field sensors embedded in a soft and flexible format to constitute magnetosensitive electronic skins (e-skins). Being limited by the sensitivity to in-plane magnetic fields, magnetosensitive e-skins are restricted to basic proximity and angle sensing and are not used as switches or logic elements of interactive wearable electronics. Here, we demonstrate a novel magnetoreceptive platform for on-skin touchless interactive electronics based on flexible spin valve switches with the sensitivity to out-of-plane magnetic fields. The technology relies on all-metal Co/Pd-based spin valves with a synthetic antiferromagnet possessing perpendicular magnetic anisotropy. The flexible magnetoreceptors act as logic elements, namely momentary and permanent (latching) switches. The switches maintain their performance even upon severe bending to a radius of less than 5 mm and withstand repetitive bending for hundreds of cycles. We integrated flexible switches in on-skin interactive electronics and demonstrated their performance as touchless human-machine interfaces, which are intuitive to use, energy efficient, and insensitive to external magnetic disturbances. This technology offers qualitatively new functionalities for electronic skins and paves the way towards full-fledged on-skin touchless interactive electronics.

Keywords: flexible electronics; magnetic field sensors; flexible spin valve; skin-conformal; sensor

Permalink: https://www.hzdr.de/publications/Publ-32395
Publ.-Id: 32395


Slice2Volume: Fusion of multimodal medical imaging and light microscopy data of irradiation-injured brain tissue in 3D

Soltwedel, J.; Suckert, T.; Beyreuther, E.; Schneider, M.; Boucsein, M.; Bodenstein, E.; Stolz-Kieslich, L.; Krause, M.; Neubeck, C. V.; Haase, R.; Lühr, A.; Dietrich, A.

Comprehending cellular changes of radiation-induced brain injury is crucial to prevent and treat the pathology. We provide a unique open dataset of proton-irradiated mouse brains consisting of medical imaging, radiation dose simulations, and large-scale microscopy images, all registered into a common coordinate system. This allows dose-dependent analyses on single-cell level.

Keywords: Multimodal Imaging; Normal tissue toxicity; Open Data; Preclinical mouse brain irradiation; Proton therapy; Radiationinduced brain injury

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Permalink: https://www.hzdr.de/publications/Publ-32394
Publ.-Id: 32394


Impact of surface charge on the motion of light-activated Janus micromotors

Huang, T.; Ibarlucea, B.; Caspari, A.; Synytska, A.; Cuniberti, G.; de Graaf, J.; Baraban, L.

Control over the motion of micromotors is of high relevance for lab-on-a-chip and biomedical engineering, wherein such particles encounter complex microenvironments. Here, we introduce an efficient way to influence the direction of motion and speed of Janus micromotors by modifying their surface properties and those of their immediate surroundings. We fabricated light-responsive Janus micromotors with positive and negative surface charge, both driven by ionic self-diffusiophoresis. These were used to observe direction-of-motion reversal in proximity to glass substrates for which we varied the surface charge. Quantitative analysis allowed us to extract the dependence of the particle velocity on the surface charge density at the substrate. This constitutes the first quantitative demonstration of the substrate’s surface charge on the motility of the light-activited diffusiophoretic motors in water. We provide qualitative understanding of these observations in terms of osmotic flow along the substrate generated through the ions released by the propulsion mechanism. Our results constitute a crucial step in moving toward practical application of self-phoretic artificial micromotors.

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Permalink: https://www.hzdr.de/publications/Publ-32393
Publ.-Id: 32393


PIConGPU setup: LPWFA downramp injection

Pausch, R.; Couperus Cabadag, J. P.; Bastrakov, S.; Bussmann, M.; Irman, A.; Kurz, T.; Schöbel, S.; Schramm, U.; Steiniger, K.; Ufer, P.; Widera, R.; Debus, A.

PIConGPU source code and setup files used for the LPWFA downramp injection simulation study

Keywords: PIConGPU; LWFA; PWFA; LPWFA; hybrid

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