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39109 Publications

Technetium retention by green rust chloride

Mayordomo, N.; Rodriguez Hernandez, D. M.; Schild, D.; Roßberg, A.; Scheinost, A.; Brendler, V.; Müller, K.

Techntium-99 (99Tc) is one of the most concerning fission products due to its long half-life (2.14∙10⁵ years) and the mobility of the anion pertechnetate (TcO₄⁻). [1] However, Tc migration decreases when Tc(VII) is reduced to Tc(IV). This scavenging step is favored by reductive material, among which Fe(II) minerals have been widely studied due to their versatility, low cost and ubiquity. [2]
Green rust is a Fe(II)-Fe(III) mixed hydroxide that possesses adsorption, anion exchange and reduction capabilities. Its presence is expected in the near- and far-field of a nuclear waste repository because it is an iron corrosion product, and it is also formed in the environment when Fe²⁺ interacts with Fe(III) minerals. [3]
Batch contact studies have been performed under a wide range of conditions, i.e. pH (3-11), Tc concentration (nM-mM), and ionic strength (0-0.1 M). X-ray diffraction, Raman microscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) provided information on Tc oxidation state and speciation as well as on secondary redox products related to the Tc interaction with green rust. In addition, re-oxidation experiments have been performed during six months.
The results show that green rust removes Tc from solution with efficiencies between 80% (Kd = 8.0∙103 mL/g) and ≈100% (Kd = 9.9∙10⁵ mL/g) for pH > 6.0, regardless on the ionic strength and the Tc concentration. In contrast, Tc removal for pH < 6.0 drops with decreasing pH, and ranges from 80% to 50% (Kd = 2.0∙10³ mL/g), reaching a minimum at pH 3.5. XPS analysis reveals the predominance of Tc(IV) at all evaluated pH values (3.5 to 11.5), supporting that Tc reductive immobilization is the main retention mechanism. Re-oxidation experiments show that Tc is slowly solubilized when time increases.
We thank the German Federal Ministry of Economic Affairs and Energy (BMWi) for funding the VESPA II project (02E11607B).
[1] Meena, A.H.; Arai, Y. Env. Chem Lett (2017), 15, 241–263.
[2] Pearce, C.I. et al. Sci. Total Environ. (2020), 716, 132849.
[3] Usman, M. et al. Chem. Rev. (2018), 118, 3251–3304.

Keywords: Technetium; Reductive immobilization; Sorption; Fe(II)-minerals

Related publications

  • Lecture (Conference) (Online presentation)
    Goldschmidt 2021, 04.-09.07.2021, Online, Online

Publ.-Id: 32650

Interfacial flow of a surfactant-laden interface under asymmetric shear flow

Eftekhari, M.; Schwarzenberger, K.; Heitkam, S.; Eckert, K.

The shear stress of the axisymmetric flow field triggers a nonuniform distribution of the surfactants at the surface of a rising bubble, known as stagnant cap. The formation of the stagnant cap gives rise to Marangoni stresses that reduce the mobility of the interface, which in return reduces the rising velocity. However, the conditions in technological processes usually deviate from the linear rise of a single bubble in a quiescent unbounded liquid. Asymmetric shear can act on the bubble surface e.g. due to the vorticity in the surrounding flow, bubble-bubble interactions, or influence of the reactor wall. A different surfactant distribution at the interface is expected under asymmetric shear, which can change the hydrodynamic behavior of the interface drastically.
Here we conduct model experiments with a bubble or a drop at the tip of a capillary placed in a defined flow field. Thereby we investigate the influence of asymmetric shear forces on the interface in the presence of surfactants. Microscopic particle tracking velocimetry is employed to measure the velocity of the surfactant-laden interface for different degrees of asymmetry in the surrounding liquid flow.
We show a direct experimental observation of the circulating flow at the interface under asymmetric shear, which prevents the formation of the typical stagnant cap. Additionally, we reveal that the interface remains mobile regardless of the surfactant concentration. Our results confirm that increasing the degree of asymmetry increases the shear forces and thus the interfacial velocity.

Keywords: Rising bubble; Stagnant cap; Surfactant distribution; Marangoni effect; Particle image velocimetry; Interfacial flow


Publ.-Id: 32649

Investigation of Np(V) sorption onto the zircaloy corrosion product ZrO₂

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

In a safety assessment of a high-level radioactive waste repository, interactions of radionuclides (e.g. neptunium(V)) with corroded phases in the near field of the repository have to be taken into account. The corrosion product of the zircaloy cladding material of spent nuclear fuel rods, namely zirconia (ZrO₂), potentially represents a first migration barrier towards mobilized radionuclide ions.
The interactions of Np(V) with monoclinic zirconia were studied at room temperature on a macroscopic and molecular scale. To gain comprehensive characteristics on the macroscopic level, batch sorption experiments were conducted to investigate the influence of different parameters (time, pH, Np(V) concentration and ionic strength). Np(V) showed increasing sorption to ZrO₂, starting from pH 3 and with a maximum uptake reached at pH ≥ 7. The Np(V) sorption is independent of ionic strength in the studied range (0.01 ‒ 0.1 M), indicating the formation of Np(V) inner-sphere sorption complexes on the ZrO₂ surface. Electrophoretic measurements further support this result by shifting the isoelectric point of ZrO₂ towards higher pH values in the presence of Np(V) compared to neat zirconia material.
Spectroscopic studies enable a deeper understanding of Np(V) sorption on a molecular scale. In situ Attenuated Total Reflection Fourier-transform Infrared spectroscopy potentially provides information on the number of sorption species, their denticity and the reversibility of the sorption process. From Extended X-ray Absorption Fine Structure spectroscopy access is given to the interatomic Np-Zr distances and the coordination numbers. Information gained on the macroscopic and molecular level will subsequently be used for surface complexation modelling (SCM) to parametrize a comprehensive description of the Np(V)-ZrO₂ system. This will contribute to a more reliable prediction of the environmental fate of neptunium(V).

Keywords: neptunium(V); sorption; zirconia; spectroscopy

Related publications

  • Lecture (Conference) (Online presentation)
    45th Scientific Basis for Nuclear Waste Management (SBNWM), 24.-29.10.2021, Cologne, Germany

Publ.-Id: 32648

Scaling of Lift Reversal of Deformed Bubbles in Air-Water Systems

Hayashi, K.; Heßenkemper, H.; Lucas, D.; Legendre, D.; Tomiyama, A.

Scaling of the lift reversal for a deformed bubble in the surface tension-inertial force dominant regime was discussed. Lift data of bubbles in water recently reported in literature were used. The negative lift component was well correlated in terms of the drag coefficient, which, in turn, implies that the vorticity produced at the bubble surface plays a key role in both drag and lift forces as is the case with the viscous force dominant regime. The scaling was confirmed to give good evaluations of the lift coefficients.

Keywords: Lift force; Lift reversal; Negative lift; Shape deformation


Publ.-Id: 32647

Interfacial mobility of surfactant and nanoparticle -laden interfaces under asymmetric shear flow

Eftekhari, M.; Schwarzenberger, K.; Heitkam, S.; Javadi, A.; Eckert, K.

The shear stress of an axisymmetric flow field triggers a nonuniform distribution of the surfactants at the surface of a rising bubble, known as stagnant cap. This nonuniform surfactant distribution creates a surface tension gradient that counteracts the viscous shear stress of the flow and thus reduces the mobility of the interface. However, in technological processes the flow field often is asymmetric e.g. due to the vorticity in the flow. Under such conditions, the interface experiences an unbalanced shear stress that is not curl-free. Thus, it cannot be compensated by the redistribution of the surfactants at the interface [1].
Here, we conduct model experiments with a bubble at the tip of a capillary placed in a defined asymmetric flow field. Thereby, we investigate the mobility of the interface in the presence of surfactants and nanoparticles using microscopic particle tracking velocimetry. Compared to surfactants, nanoparticles have substantially higher desorption energy, leading to irreversible adsorption. Thus, a different interaction between the bulk flow and the interface is expected for different types of adsorbed materials.
In this study, we show a direct experimental observation of the circulating flow at the interface under asymmetric shear stress. The results indicate that the interface remains mobile regardless of the surfactant concentration [2]. Additionally, we show that the nanoparticle-laden interface adopts a solid-like state and resists the interfacial flow upon surface compression. Our results imply that the immobilization of the interface can be described by the ratio of the interfacial elasticity to the bulk viscous forces.

Keywords: Rising bubble; asymmetric shear flow; surfactant distribution; nanoparticles; interfacial immobility

Related publications

  • Lecture (Conference)
    European Colloid & Interface Society, 05.-10.09.2021, Athens, Greece

Publ.-Id: 32645

Llama, a low level abstraction library for memory access

Gruber, B. M.

This talk presents the current state of LLAMA, the library for Low Level Abstraction of Memory Access.

  • Open Access Logo Lecture (Conference) (Online presentation)
    Compute Accelerator Forum, 12.05.2021, virtual, Switzerland


Publ.-Id: 32643

Stable isotope fractionation of thallium as novel evidence for its geochemical transfer during lead‑zinc smelting activities

Zhou, Y.; He, H.; Wang, J.; Liu, J.; Lippold, H.; Bao, Z.; Wang, L.; Lin, Y.; Fang, F.; Huang, Y.; Jiang, Y.; Xiao, T.; Yuan, W.; Wei, X.; Tsang, D. C. W.

Thallium(Tl) is a highly toxic trace metal. Lead(Pb)-zinc(Zn) smelting, which is a pillar industry in various countries, is regarded as one of the dominant anthropogenic sources of Tl contamination in the environment. In this study, thallium isotope data have been evaluated for raw material and a set of industrial wastes produced at different stages of Pb-Zn smelting in a representative large facility located by the North River, South China, in order to capture Tl isotope signatures of such typical anthropogenic origin for laying the foundation of tracking Tl pollution. Large variations in Tl isotopic compositions of raw Pb-Zn ores and solid smelting wastes produced along the process chain were observed. The ε205Tl value of raw Pb-Zn ores and return fines are −0.87 ± 0.26 and −1.0 ± 0.17, respectively, contrasted by increasingly more negative values for electrostatic precipitator dust (ε205Tl = −2.03 ± 0.14), lime neutralizing slag (ε205Tl = −2.36 ± 0.18), and acid sludge (ε205Tl = −4.62 ± 0.76). The heaviest ε205Tl (1.12 ± 0.51) was found in clinker. These results show that isotopic fractionation occurs during the smelting processes. Obviously, the lighter Tl isotope is enriched in the vapor phase (−3.75 ε205Tl units). Further XPS and STEM-EDS analyses show that Tl isotope fractionation conforms to the Rayleigh fractionation model, and adsorption of 205Tl onto hematite (Fe2O3) may play an important role in the enrichment of the heavier Tl isotope. The findings demonstrate that Tl isotope analysis is a robust tool to aid our understanding of Tl behavior in smelting processes and to provide a basis for source apportionment of Tl contaminations.

Keywords: Tl contamination; Tl isotope; Pb-Zn smelting; Rayleigh fractionation

Publ.-Id: 32642

Low Carbon Footprint Recycling of Post-Consumer PET Plastic with a Metagenomic Polyester Hydrolase

Sonnendecker, C.; Oeser, J.; Richter, P. K.; Hille, P.; Zhao, Z.; Fischer, C.; Lippold, H.; Blázquez-Sánchez, P.; Engelberger, F.; Ramírez-Sarmiento, C. A.; Oeser, T.; Lihanova, Y.; Frank, R.; Jahnke, H.-G.; Billig, S.; Abel, B.; Sträter, N.; Matysik, J.; Zimmermann, W.

Our planet is flooded with plastics and the need for sustainable recycling strategies of polymers has become increasingly urgent. Enzyme-based hydrolysis of post-consumer plastic is an emerging strategy for closed-loop recycling of polyethylene terephthalate (PET). The polyester hydrolase PHL7 isolated from a compost metagenome completely hydrolyzed amorphous PET films, releasing 91 mg of terephthalic acid per hour and mg of enzyme. Degradation rates of the PET film of 6.8 µm h-1 were monitored by vertical scanning interferometry. Structural analysis indicated the importance of leucine at position 210 for the extraordinarily high PET-hydrolyzing activity of PHL7. Within 24 h, 0.6 mgenzyme gPET -1 completely degraded post-consumer thermoform PET packaging in an aqueous buffer at 70°C without any energy-intensive pretreatments. Terephthalic acid recovered from the enzymatic hydrolysate was used to synthesize virgin PET, demonstrating the potential of polyester hydrolases as catalysts in sustainable PET recycling processes with a low carbon footprint.

Publ.-Id: 32641

Optimization of multi-group energy structures for diffusion analyses of sodium-cooled fast reactors assisted by simulated annealing – Part II: methodology application

Di Nora, V. A.; Fridman, E.; Nikitin, E.; Bilodid, Y.; Mikityuk, K.

Part I of this study introduced a novel methodology for the optimization of energy group structures to be used in diffusion calculations of Sodium Fast Reactors (SFRs). Such a methodology is assisted by either direct or simulated annealing search techniques. The capabilities of the method were preliminarily demonstrated on a single core state of the Superphénix reactor by using the DYN3D nodal diffusion code.
The scope of Part II is the further demonstration of the methodology efficiency through its application to more challenging “real-life” cases. In this respect, a static Superphénix neutronic benchmark comprising 13 different core states and a transient test initiated by an increase of the core inlet temperature at the Phénix reactor are considered.
For both Superphénix and Phénix reactor cores, 2- to 12-group optimal condensed energy group structures are identified using the 24-group structure as a starting point. The obtained optimal structures are thus employed in DYN3D and compared to the reference 24-group DYN3D solutions.
The outcomes show that also for a broader range of core configurations and under transient conditions the optimal energy group structures allow for significant acceleration of the DYN3D performance with practically negligible degradation of the solution accuracy.

Keywords: Serpent; SFR; energy structure optimization; simulated annealing

Publ.-Id: 32640

High brightness ion sources for laser-induced ionization of metal and metalloid ions

Machalett, F.; Ying, B.; Wustelt, P.; Huth, V.; Bischoff, L.; Klingner, N.; Kübel, M.; Sayler, A. M.; Stöhlker, T.; Paulus, G. G.

Gold and silicon ions emitted from high brightness liquid metal ion sources (LMIS) are used as ionic targets for strong field laser interaction with femtosecond laser beams. Field ionization processes in the field emission source at electrostatic fields of some 10 V/nm allow the generation of various metallic and metalloid ion beams with charge states such as Au2+ and Si2+. Studying the ionization in strong femtosecond laser fields with intensities of up to 1016 W/cm2, we observed for these elements charge states of up to Au11+ and Si4+.

Related publications

  • Open Access Logo Contribution to external collection
    in: Jahresbericht 2020 des Helmholtz-Instituts Jena, Jena: Helmholtz-Institut Jena, 2021


Publ.-Id: 32639

Inductive System for Magnesium Level Detection in a Titanium Reduction Reactor

Krauter, N.; Eckert, S.; Gundrum, T.; Stefani, F.; Wondrak, T.; Khalilov, R.; Dimov, I.; Frick, P.

The determination of the magnesium level in a titanium reduction retort by inductive methods
is often hampered by the formation of titanium sponge rings which disturb the propagation of
electromagnetic signals between excitation and receiver coils. We present a new method for the
reliable identification of the magnesium level which explicitly takes into account the presence of sponge rings with unknown geometry and conductivity. The resulting inverse problem is solved by a look-up-table method, based on the solution of the inductive forward problems for several tens thousands of parameter combinations. The feasibility of that method is demonstrated by performing numerical simulations and measurements on a model experiment. This method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.

Keywords: Kroll Process; Numerical Simulation; Inductive Measurements; Titanium; Level Detection

  • Contribution to proceedings
    Electromagnetic Processing of Materials 2021, 13.-17.06.2021, Riga, Lettland
    Proceedings of the 10th international conference on Electromagnetic Processing of Materials
  • Lecture (Conference) (Online presentation)
    Electromagnetic Processing of Materials 2021, 13.-17.06.2021, Riga, Lettland
  • Lecture (Conference) (Online presentation)
    4th Russian Conference on Magnetohydrodynamics, 20.-22.09.2021, Perm, Russland

Publ.-Id: 32638

Eddy Current Flow Meter Flow Rate Measurements in Liquid Sodium at the Superfennec Loop

Krauter, N.; Paumel, K.; Girard, M.; Eckert, S.; Gerbeth, G.

The Eddy Current Flow Meter is an inductive flow rate sensor which can be used in many liquid metal applications and is well suited for operation in liquid metal cooled fast reactors. There it can be used as part of the safety instrumentation in order to detect a loss of flow in the reactor core. To further qualify the Eddy Current Flow Meter for use in liquid metal cooled reactors, measurements with a high temperature prototype of the sensor have been performed at the sodium loop SUPERFENNEC for sodium temperatures between 200 °C and 300 °C and flow velocities of up to 2.5 m/s. By measuring the magnitude or phase shift of the output voltage of the sensor, the flow rate or velocity of the liquid sodium in a certain volume around the sensor can be determined. Depending on the frequency of the excitation current, the sensitivity of the sensor is changing. Therefore, measurement results for different frequencies and temperatures are presented as well as the results of a frequency sweep for determining the optimal excitation frequency of the sensor.

Keywords: Flow Measurements; Eddy Current Flow Meter; Liquid Sodium; Inductive Measurements

  • Poster (Online presentation)
    International Conference on Fast Reactors and Related Fuel Cycles FR22: Sustainable Clean Energy for the Future (CN-291), 19.-22.04.2022, Wien, Österreich

Publ.-Id: 32637

Coolant Flow Monitoring With an Eddy Current Flow Meter at a Mock-Up of a Liquid Metal Cooled Fast Reactor

Krauter, N.; Stefani, F.; Wondrak, T.; Eckert, S.; Gerbeth, G.

The Eddy Current Flow Meter is an inductive velocity sensor which can be used in liquid metal applications, such as liquid metal cooled fast reactors. There it can be used as part of the safety instrumentation in order to monitor the coolant flow through subassemblies under normal operating conditions or to detect and locate blockages in case of a local freezing of the coolant. Typically the Eddy Current Flow Meter is used in pipe flows where the flow is mostly parallel to the sensor axis, whereas the flow angle may change significantly above subassemblies in a liquid metal cooled reactor. In the first part, the paper therefore deals with investigating the influence of varying flow angles on the performance of the Eddy Current Flow Meter. By performing measurements in a model experiment, the effect of different flow angles on the measured velocities will be demonstrated. In the second part of the paper, multiple Eddy Current Flow Meters in an array are used to detect and locate blockages in an array of seven subassemblies in the same model experiment. All experiments are carried out at room temperature with a liquid alloy of gallium, indium and tin.

Keywords: Flow Measurements; Eddy Current Flow Meter; Reactor Safety; Liquid Metals

  • Lecture (Conference) (Online presentation)
    International Conference on Fast Reactors and Related Fuel Cycles FR22: Sustainable Clean Energy for the Future (CN-291), 19.-22.04.2022, Wien, Österreich

Publ.-Id: 32636

H2pyhox - Octadentate Bis(pyridyloxine)

Southcott, L.; Wang, X.; Choudhary, N.; Wharton, L.; Patrick, B.; Yang, H.; Zarschler, K.; Kubeil, M.; Stephan, H.; Jaraquemada-Pelaez, M. D. G.; Orvig, C.

A new versatile chelating ligand for intermediate size and softness radiometals [64Cu]Cu2+ and [111In]In3+, H2pyhox, was synthesized by introducing
pyridine as a new donor moiety to complement 8-hydroxyquinoline on an ethylenediamine backbone. The combination of pyridine
and oxine as donor sets was explored through structural analysis, and crystals of the three metal complexes with Cu2+, La3+ and In3+ demonstrate how the ligand adapts to accommodate metal ions of different sizes and charge. Exhaustive in-batch UV solution studies characterized the protonation constants of the free ligand as well as the formation constants of the metal complexes with Cu2+, In3+ and La3+. Preliminary concentration dependent radiolabeling studies with [111In]In3+ and [64Cu]Cu2+ show the robustness of H2pyhox to successfully coordinate both radiometals under mild conditions (< 15 min, room temperature, pH 6). H2pyhox is the first oxinate ligand to successfully radiolabel [225Ac]Ac3+, albeit only at high concentrations (0.1 – 1 mM) with gentle heating to 37℃. Whole serum, protein and ligand challenge assays further demonstrate the kinetic inertness of the radiometal-ligand complexes, confirming H2pyhox to be a promising versatile radiopharmaceutical chelator.

Publ.-Id: 32635

Jump rope vortex flow in liquid metal Rayleigh-Bénard convection in a cuboid container of aspect ratio five

Akashi, M.; Yanagisawa, T.; Sakuraba, A.; Schindler, F.; Horn, S.; Vogt, T.; Eckert, S.

We study the topology and the temporal dynamics of turbulent Rayleigh-B´enard convection in a liquid metal with a Prandtl number of 0.03 located inside a box with a square base area and an aspect ratio of Γ = 5. Experiments and numerical simulations are focused on the Rayleigh number range, 6.7 × 10⁴ < Ra 3.5 × 10⁵
, where a new cellular flow regime has been reported by a previous study (Akashi et al., Phys. Rev. Fluids, vol.4, 2019, 033501). This flow structure shows symmetries with respect to the vertical mid-planes of the fluid container. The dynamic behaviour is dominated by strong three-dimensional oscillations with a periodic time that corresponds to the turnover time. Our analysis reveals that the flow structure in the Γ = 5 box corresponds in key features to the jump rope vortex structure, which has recently been discovered in a Γ = 2 cylinder (Vogt et al., Proc. Natl Acad. Sci. USA, vol.115, 2018, 12674-12679). While in the Γ = 2 cylinder a single jump rope vortex occurs, the coexistence of four recirculating swirls is detected here. Their cycling movement is restrained by the limited height of the fluid layer in the Γ = 5 box. Their approach to the lid or the bottom causes a temporal deceleration of both the horizontal velocity at the respective plate and the vertical velocity, which in
turn is reflected in Nusselt number oscillations. The cellular flow regime shows remarkable similarities to properties commonly attributed to turbulent superstructures.

Keywords: Rayleigh-B´enard convection; thermal turbulence; heat transport; large-scale circulation; liquid metal; low Prandtl number

Publ.-Id: 32634

Oct4 confers stemness and radioresistance to head and neck squamous cell carcinoma by regulating the homologous recombination factors PSMC3IP and RAD54L

Nathansen, J.; Lukiyanchuk, V.; Hein, L.; Stolte, M.-I.; Borgmann, K.; Löck, S.; Kurth, I.; Baumann, M.; Krause, M.; Linge, A.; Dubrovska, A.

Head and neck squamous cell carcinoma (HNSCC) is often being diagnosed at an advanced stage, conferring a poor prognosis. The probability of local control after radiotherapy depends on the eradication of cancer stem cells (CSCs) with activated DNA repair. This study provides evidence that the CSC-related transcription factor Oct4 contributes to HNSCC radioresistance by regulating DNA damage response and the CSC phenotype. Knockdown of Oct4 A isoform reduced self-renewal capacity in HNSCC and led to partial tumor cell radiosensitization caused by transcriptional downregulation of the cell cycle checkpoint kinases CHK1 and WEE1 and homologous recombination (HR) repair genes PSMC3IP and RAD54L. Besides, PARP inhibition with Olaparib selectively radiosensitized Oct4 A knockout, but not wild type HNSCC cells. This finding links Oct4 A to the HR-mediated DNA repair mechanisms. In turn, knockdown of PSMC3IP and RAD54L reduced the HNSCC self-renewal capacity and clonogenic cell survival after irradiation, suggesting the interplay between DNA repair and the CSC phenotype. Similar to the effect of Oct4 knockdown, overexpression of Oct4 also resulted in significant HNSCC radiosensitization and increased DNA damage, suggesting that Oct4-dependent regulation of DNA repair depends on its fine-tuned expression. In line with this observation, HNSCC patients with high and low nuclear Oct4 expression at the invasive tumor front exhibited poor loco-regional tumor control after postoperative radio(chemo)therapy compared to the intermediate expression subgroup. Thus, we found that the Oct4-driven transcriptional program plays a critical role in regulating HNSCC radioresistance, and a combination of radiotherapy with PARP inhibitors may induce synthetic lethality in Oct4-deregulated tumors.

Keywords: radioresistance; head and neck squamous cell carcinoma; homologous recombination; biomarker

Publ.-Id: 32633

Evolution of the magnetic hyperfine field profiles in ion-irradiated Fe60Al40 film measured by nuclear resonant reflectivity

Andreeva, M.; Smekhova, A.; Baulin, R.; Repchenko, Y.; Bali, R.; Schmitz-Antoniak, C.; Wende, H.; Sergueev, I.; Schlage, K.; Wille, H. C.

Nuclear resonant reflectivity (NRR) from an Fe60Al40 film was measured using synchrotron radiation at several grazing angles near the critical angle of the total external reflection. By laterally resolved measurements after 20 keV Ne+ ion irradiation with gradually varied fluences of 0 - 3.0 x 10^14 ions/cm2, the progressive creation of the ferromagnetic A2 phase with increasing ion fluence was confirmed. The observed depth-selectivity of the method has been explained by application of the standing wave approach. From the time spectra of the nuclear resonant scattering in forward or diffraction directions the depth-profiles for different hyperfine fields were extracted. The results evidence that the highest magnetic hyperfine fields (~ 18 % 23 T) are initially created at the center part of the film and partially at the bottom interface with SiO2 substrate. The evolution of the ferromagnetic onset, commencing at a fixed depth within the film and propagating towards the interfaces has been directly observed. At higher fluence (3.01014 ions/cm2) the depth distribution of the ferromagnetic fractions became more homogeneous across the film depth in accordance with previous results.

Keywords: Magnetic patterning; ion irradiation; x-ray reflectivity; hyperfine interactions; nuclear resonant scattering; magnetic depth-profiles; Mössbauer spectroscopy

Related publications


Publ.-Id: 32632

HELIPORT: A Portable Platform for FAIR {Workflow | Metadata | Scientific Project Lifecycle} Management and Everything

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

Modern scientific collaborations and projects (MSCPs) employ various processing stages, starting with the proposal submission, continuing with data acquisition and concluding with final publications. The realization of such MSCPs poses a huge challenge due to (1) the complexity and diversity of the tools, (2) the heterogeneity of various involved computing and experimental platforms, (3) flexibility of analysis targets towards data acquisition and (4) data throughput. Another challenge for MSCPs is to provide additional metadata according to the FAIR principles for all processing stages for internal and external use. Consequently, the demand for a system, that assists the scientist in all project stages and archives all processes on the basis of metadata standards like DataCite to make really everything transparent, understandable and citable, has risen considerably. The aim of this project is the development of the HELmholtz ScIentific Project WORkflow PlaTform (HELIPORT), which ensures data provenance by accommodating the complete life cycle of a scientific project and linking all employed programs and systems. The modular structure of HELIPORT enables the deployment of the core applications to different Helmholtz centers (HZs) and can be adapted to center-specific needs simply by adding or replacing individual components. HELIPORT is based on modern web technologies and can be used on different platforms.

Keywords: Data Management; Metadata; Scientific Project; FAIR; Data provenance; Related Identifier; Datasets; Digital Objects

  • Open Access Logo Contribution to proceedings
    4th International Workshop on Practical Reproducible Evaluation of Computer Systems (P-RECS ’21), 21.-25.06.2021, Stockholm, Sweden
    Proceedings of the 4th International Workshop on Practical Reproducible Evaluation of Computer Systems (P-RECS ’21), New York, NY, USA: ACM, 978-1-4503-8395-0/21/06, 9-14
    DOI: 10.1145/3456287.3465477

Publ.-Id: 32631

GPU-based computation of coalescence and breakup models for polydisperse bubbly flows

Petelin, G.; Kelling, J.; Lehnigk, R.; Papa, G.; Schlegel, F.

Polydisperse bubbly flows appear in many industrial applications and are particularly relevant for nuclear and process engineering. A popular approach for their simulation is the two-fluid model, which requires information about the bubble size. An associated challenge is to incorporate the effects of coalescence and breakup on the size distribution, which can be tracked by a population balance equation. It can be solved by the method of classes, which splits the bubble population into a finite number of size groups. However, this technique is expensive because the source term assembly involves the computation of coalescence and breakup frequencies between all bubble size pairs. This work focuses on improving the performance of the class method implementation within the OpenFOAM Foundation release (, an open source computational fluid dynamics software that allows for domain decomposition and parallel execution on multiple central processing units. Here, the parallel computation of the coalescence and breakup frequencies is shifted to graphics processing units using the Nvidia CUDA framework. Calculations are done asynchronously with overlapping data transfers, treating size pairs as independent units of work that are computed in parallel. The coalescence and breakup frequency computation on graphics processing units leads to a significant speedup compared to the pre-existing implementation. The improvement is demonstrated for a co-current two-phase flow in a vertical pipe. Both the source code and the case setup are made publicly available.

  • Lecture (Conference)
    30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slovenien
  • Contribution to proceedings
    30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slovenien
    Proceedings of the 30th International Conference Nuclear Energy for New Europe

Publ.-Id: 32629

Microscopic characterization of un-irradiated and irradiated steel shielding material of a nuclear power plant

Yassin, G.; Barkleit, A.; Brendler, V.

Nuclear power plants (NPPs) have been considered an important energy source in Europe over a long time. However, in Germany the government decided that NPPs must terminate their operation end of 2022 at the latest, due to their possible threats on humans and the environment. The question arises, how much the long term irradiation of an NPP poses safety risks, in particular, in the reactor pressure vessel (RPV), which is the main shielding barrier of the radioactive fuel. For this purpose, the microstructural features, the composition, and the radioactive inventory of the steel shielding material in the RPV are investigated.

  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-113 Mai 2020, 77-78
    ISSN: 2191-8708, eISSN: 2191-8716

Publ.-Id: 32628

Coexistence of fluorescent Escherichia coli strains in millifluidic droplet reactors

Zhao, X.; Illing, R.; Ruelens, P.; Bachmann, M.; Cuniberti, G.; de Visser, J. A. G. M.; Baraban, L.

Understanding competition and cooperation within microbiota is of high fundamental and clinical importance, helping to comprehend species' evolution and biodiversity. We co-encapsulated and cultured two isogenic Escherichia coli strains expressing blue (BFP) and yellow (YFP) fluorescent proteins into numerous emulsion droplets and quantified their growth by employing fluorescence measurements. To characterize and compare the bacterial growth kinetics and behavior in mono and co-culture, we compared the experimental observations with predictions from a simple growth model. Varying the initial ratio (R0) of both cell types injected, we observed a broad landscape from competition to cooperation between both strains in their confined microenvironments depending on start frequency: from a nearly symmetric situation at R0 = 1, up to the domination of one subpopulation when R0 ≫ 1 (or R0 ≪ 1). Due to competition between the strains, their doubling times and final biomass ratios (R1) continuously deviate from the monoculture behavior. The correlation map of the two strains' doubling times reveals that the R0 is one of the critical parameters affecting the competitive interaction between isogenic bacterial strains. Thanks to this strategy, different species of bacteria can be monitored simultaneously in real-time. Further advantages include high statistical output, unaffected bacteria growth, and long-time measurements in a well-mixed environment. We expect that the millifluidic droplet-based reactor can be utilized for practical clinical applications, such as bacterial antibiotic resistance and enzyme reaction kinetics studies.

Keywords: droplets; microbiology; bacterial coexistance

Publ.-Id: 32626

A neural network model for the microlayer evaporation in wall boiling flows

Evdokimov, I.; Hänsch, S.

Microlayers, the thin layers of liquid forming at the underside of a steam bubble growing at a heated wall, have shown to contribute significantly to the bubble growth under certain wall boiling conditions.
The measurement of their shape and thickness remains an experimental and the simulation of their formation via CFD a computational challenge.
Thus, it is difficult to develop microlayer evaporation models covering a wide enough parameter space, which would allow their inclusion into advanced Euler-Euler wall boiling models.
In this work we present a feed-forward neural network (NN), which was trained by a small set of direct numerical simulation (DNS) data with the aim to predict microlayer profiles and volumes under different wall boiling conditions. Various configurations of such machine learning (ML) models were studied and introduced into the OpenFOAM open source CFD solver.
The training data consists of interface-tracking simulation results of the early bubble growth stages. Using the level-set and phase-change capabilities of PHASTA the transient evolution of evaporating microlayer profiles was computed for three different superheats for water at atmospheric pressure.
Data mining was then applied to pre-process and feed these results to a neural network in order for it to learn how to predict the microlayer volume depending on different wall superheats and bubble departure sizes.
The computed microlayer-to-bubble volume ratio allowed the trained NN model to be embedded into the RPI wall boiling model of OpenFOAM, which was extended in order to account for an additional microlayer evaporation term. Whilst the overall evaporation component remains unchanged in magnitude, the proposed model does distinguish between the evaporation contributions from the upper curved bubble surface and from the microlayer region.
The NN extended RPI wall boiling model is applied to two demonstration cases: the DEBORA wall boiling case [1], for which no microlayer contribution is expected, and the experimental case of Lee et al. [2] for water under atmospheric pressure, for which the microlayer evaporation is expected to be significant. The NN extended RPI wall boiling model is shown to predict reasonable contributions of the different evaporation mechanisms.
The application of ML techniques, where experimental and computational limits hinder sufficient data collection, seems a promising alternative to the conventional development of Euler-Euler models. In the future the NN model presented here can be fed with additional DNS data as well as experimental data for more refined results under various boiling conditions and for different working fluids. The particular implementation of the ML models in the RPI wall boiling model needs to be further researched and discussed with the broad scientific community.

[1] J. Garnier, E. Manon, G. Cubizolles, Local measurments on flow boiling of refrigerant r12 in a vertical tube, Multiphase Science and Technology 13 (2001) 1–111.
[2] T. Lee, G. Park, D. Lee, Local flow characteristics of subcooled flow boil-ing flow of water in a vertical concentric annulus, International Journal of Multiphase Flow 28 (2002) 1351–1368.

Keywords: machine learning; feed-forward neural network; wall boiling; microlayer; interface-tracking

  • Contribution to proceedings
    NENE 2021 - 30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slovenia
  • Poster
    NENE 2021 - 30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slovenia

Publ.-Id: 32625

Sensitivity of PS/CoPd Janus particles to an external magnetic field

Eichler-Volf, A.; Alsaadawi, Y.; Vazquez Luna, F.; Khan, Q. A.; Stierle, S.; Xu, C.; Heigl, M.; Fekri, Z.; Zhou, S.; Zahn, P.; Albrecht, M.; Steinhart, M.; Erbe, A.

The dual nature of Janus particles confers fascinating properties such as a response to multiple stimuli. In this communication, we systematically study the sensitivity to a uniform external magnetic field of isolated Janus rod-shaped and spherical particles in water confined to two dimensions. The Janus asymmetry of the particles is given by magnetic [Co(0.28 nm)/Pd(0.90 nm)]8 multilayer films deposited onto monodisperse polystyrene (PS) nanorods and microspheres, respectively. It is shown that the particles dispersed in water respond to weak magnetic field applied in in-plane direction. Here we demonstrate that a precise control of the in-plane particle orientation can be obtained for magnetic field strengths higher than 0.1 mT for microspheres and 0.4 mT for nanorods.

Publ.-Id: 32624

Magnetically Induced Aggregation of Iron Oxide Nanoparticles for Carrier Flotation Strategies

Schwaminger, S. P.; Schwarzenberger, K.; Gatzemeier, J.; Lei, Z.; Eckert, K.

On the nanoscale, iron oxides can be used for multiple applications ranging from medical treatment to biotechnology. We aimed to utilize the specific properties of these nanoparticles for new process concepts in flotation. Magnetic nanoparticles were synthesized by alkaline coprecipitation, leading to a primary particle size of 9 nm, and coated with oleate. The nanomaterial was characterized for its superparamagnetism and its colloidal stability at different ionic strengths, with and without an external magnetic field. The nanomaterial was used for model experiments on magnetic carrier flotation of microplastic particles, based on magnetically induced heteroagglomeration. We were able to demonstrate the magnetically induced aggregation of the nanoparticles which allows for new flotation strategies. Since the nanomaterial has zero remanent magnetization, the agglomeration is reversible which facilitates the process control. Magnetic carrier flotation based on iron oxide nanoparticles can pave the way to promising new recycling processes for microplastic wastes.


Publ.-Id: 32623

Pyrrol-Based Ligands as Salen Relatives: Complex Synthesis, Characterization and Comparison

Köhler, L.; Patzschke, M.; März, J.; Schmidt, M.; Stumpf, T.

Schiff bases like the mixed N, O donor ligands of the salen (Bis(salicyliden)ethylendiamin) family are frequently chosen systems for complexation studies. Advantageous is their ability to stabilize a large number of metals including actinides, as well as their tuneable electronical and sterical properties.1–4 Pyrrol-based ligands are salen’s structural relatives, but only exhibit N-donor functionalities. This provides the possibility to investigate and compare the binding situation between early actinides and N atoms in different environments.
In this study a complex series from Th to Pu with the pyrrol-based ligands 1,2-ethylenediamine-N,N’-bis(1H-pyrrol-2-yl)methylene (pyrenH2) L¹ H₂ and 1,2-benzenediamine-N,N’-bis(1H-pyrrol-2-yl)methylene (pyrophenH2) L² H₂ was synthesized. Characterization in solution (NMR) and solid state (SC-XRD) in combination with quantum chemical calculations reveal the different binding situations to the different N donors at the electronic level, which leads to unique paramagnetic behavior in solution.

1 B. E. Klamm et al., Chem. Commun., 2018, 54, 8634–8636.
2 A. N. Dame et al., Eur. J. Inorg. Chem., 2015, 2015, 2996–3005.
3 B. E. Klamm et al., Inorg. Chem., 2018, 57, 15389–15398.
4 T. Radoske et al., Chem. – Eur. J., 2020, 26, 16853–16859.

Keywords: actinides; N donor ligands; SC-XRD

  • Lecture (Conference) (Online presentation)
    ACS-Spring Meeting, 12.04.2021, USA, USA

Publ.-Id: 32622

Photoluminescence Lineshapes for Defect Centers in Silicon Carbide from First-Principles Calculations

Hashemi, A.; LinderäLv, C.; Krasheninnikov, A.; Ala-Nissilä, T.; Erhart, P.; Komsa, H.-P.

Silicon carbide with optically and magnetically active point defects offers unique opportunities for quantum technology applications. Since interaction with these defects commonly happens through optical excitation and deexcitation, a complete understanding of their light-matter interaction in general and optical signatures in particular is crucial. Here, we employ quantum mechanical density functional theory calculations to investigate the photoluminescence line shapes of selected, experimentally observed color centers (including single vacan- cies, double vacancies, and vacancy-impurity pairs) in 4H-SiC. The analysis of zero-phonon lines as well as Huang-Rhys and Debye-Waller factors is accompanied by a detailed study of the underlying lattice vibrations. We show that the defect line shapes are governed by strong coupling to bulk phonons at lower energies and localized vibrational modes at higher energies. Generally, good agreement with the available experimental data is obtained, and thus we expect our theoretical work to be beneficial for the identification of defect signatures in the photoluminescence spectra and thereby advance the research in quantum photonics and quantum information processing.

Keywords: SiC; photoluminecsence; color centers; defects

Related publications


Publ.-Id: 32621

Effect of temperature and strain rate on the deformation behavior of Ti5321 during hot-compression

Gu, B.; Chekhonin, P.; Xin, S. W.; Liu, G. Q.; Ma, C. L.; Zhou, L.; Skrotzki, W.

The effect of deformation temperature and strain rate (collectively described by the Zener-Hollomon parameter Z) on the deformation mechanism and texture formation of the metastable β-titanium alloy Ti5321 across the β-transus temperature during hot-compression was investigated by electron backscatter diffraction. In the β-phase field, it is found that the deformation behavior and texture formation varies depending on Z. With decreasing Z dynamic recovery and dynamic recrystallization become more and more important. The activation energy for steady state deformation is 240 kJ/mol and 370 kJ/mol in the β- and (α + β)-phase field, respectively. The texture developed is a <100> <111> double-fiber with < 100 > dominating at all deformation conditions. The <111> fiber gets more prominent with increasing Z suggesting that it is mainly related to deformation. Flow softening behavior of Ti5321 is associated with dynamic globularization of the α-phase and promotion of β-grain formation by continuous dynamic recrystallization.

Keywords: Metastable β-titanium alloy; EBSD; Microstructure; Texture; Dynamic recrystallization; Deformation mechanism


Publ.-Id: 32620

HELIPORT: A Potential Platform for Running Digital Twins FAIRly

Knodel, O.

This presentation introduces the HELIPORT project, which aims at developing a platform which accommodates the complete life cycle of a scientific project and links all corresponding programs, systems and workflows to create a more FAIR and comprehensible project description. Heliport is linked with our local Handle-Server and generates uniform PIDs from and for various systems and services. With the integration of the Handle system Heliport can support digital twins.

Keywords: Data management; Digital twins; Handles

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    LEAPS Integrated Platform Workshop, Digital Twinning Session, 11.-12.05.2021, Villigen, Schweiz


Publ.-Id: 32619

Multistate current-induced magnetization switching in Au/Fe/MgO(001) epitaxial heterostructures

Gospodarič, P.; Młyńczak, E.; Soldatov, I.; Kakay, A.; Bürgler, D. E.; Plucinski, L.; Schäfer, R.; Faßbender, J.; Schneider, C. M.

Magnetization switching using in-plane charge current recently has been widely investigated in heavy metal/ferromagnet bilayers with the switching mechanism usually attributed to the action of the spin-orbit coupling. Here we study in-plane current induced magnetization switching in model epitaxial bilayers that consist of Au(001) and Fe(001) grown on MgO(001). We use the planar Hall effect combined with magnetooptical Kerr effect (MOKE) microscopy to investigate magnetic properties of the bilayers and current-induced switching. We show that a current density beyond 1.4×10^7 A/cm can be employed for reproducible electrical switching of the magnetization between multiple stable states that correspond to different arrangements of magnetic domains with magnetization direction along one of the in-plane easy magnetization axes of the Fe(001) film. Lower current densities result in stable intermediate transversal resistances which are interpreted based on MOKE-microscopy investigations as resulting from the current-induced magnetic domain structure that is formed in the area of the Hall cross. We find that the physical mechanism of the current-induced magnetization switching of the Au/Fe/MgO(001) system at room temperature can be fully explained by the Oersted field, which is generated by the charge current flowing mostly through the Au layer.

Publ.-Id: 32616

AMS measurements of ⁵⁵Fe in steel - an example of a simple analysis with a big machine

Lachner, J.; Merchel, S.; Rugel, G.; Wallner, A.; Walther, D.; Ziegenrücker, R.

1 Introduction

The characterization of steel regarding its content of the short-lived 55Fe (T_1/2 = 2.756 years [1]) is considered important in processes of nuclear decommissioning. In steel, 55Fe is mainly produced in a neutron capture reaction on 54Fe. We present a pilot study using Accelerator Mass Spectrometry (AMS) at the DREAMS (DREsden AMS) facility showing that 55Fe determination in steel samples with a weight of some mg is possible without any radiochemical separation [2]. The minimalist requirements in sample preparation together with reduced measurement times allow for very short turnaround times and low costs.

2 Experimental Methods & Results

We used a few mg of fine to coarse grained steel chips from a nuclear reactor vessel without any chemical processing, which were directly pressed in the AMS sample holder. For validation the same material was chemically processed and prepared for liquid scintillation counting (LSC) and AMS, respectively. AMS uses negative ions of Fe created in a Cs sputter ion source. The use of negative ions is an advantage: There is no isobaric background from the stable 55Mn as this element does not form negative atomic ions. The counting of 55Fe events is performed relative to the measurement of ion currents of the stable isotopes 54Fe or 56Fe.
Three instances of quality control were carried out: (1) AMS measurements in three aliquots of the steel chips without further pretreatment, (2) an AMS-internal comparison of the steel chips and chemically treated AMS samples, and (3) a comparison of AMS data and LSC measurements. For these different comparisons results overlap within 3% to 20% on levels of 10² Bq/g Fe to 10⁴ Bq/g Fe. At those levels, the actual AMS measurement of a single sample can be carried out within a few minutes. In this pilot study, the sensitivity of the AMS determination reached 3 Bq/g Fe and was mainly limited by the short measurement time.

3 Outlook

Collaboration and further development of 55Fe and other radionuclide (e.g. 36Cl, 41Ca [4]) measurements within trans-national access are supported by the Horizon 2020 program RADIATE [3]. A dedicated AMS facility is planned at HZDR, for which allocation of beam times can be handled more flexibly than at the larger multi-user facility DREAMS, leading to further reduction of turnaround times. Additionally, an isobar suppression technique using the interaction of lasers with the ion beam is presently developed and may open options for AMS analysis of 59Ni, 93Zr and other isotopes also of interest for nuclear decommissioning.


[1] Pommé, S., Stroh, H., Van Ammel, R.: The 55Fe half-life measured with a pressurised proportional counter. Appl Rad Isot (2019) 148:27-34.
[2] Merchel, S., Rugel, G., Lachner, J., Wallner, A., Walther, D., Ziegenrücker, R.: Evaluation of a sensitive, cheap, and fast detection method for 55Fe in steel. J Radioanal Nucl Chem (2021) submitted.
[4] Hampe, D. Gleisberg, B., Akhmadaliev, S., Rugel, G., Merchel, S.: Determination of 41Ca with LSC and AMS: method development, modifications and applications. J Radioanal Nucl Chem (2013) 296:617-624.

Related publications

  • Lecture (Conference)
    RCA-Workshop 2021, 08.-09.06.2021, Dresden / virtual, Deutschland

Publ.-Id: 32615

High-field THz pulses from GaAs photoconductive emitter for non-linear THz studies

Singh, A.; Li, J.; Pashkin, O.; Rana, R.; Winnerl, S.; Helm, M.; Schneider, H.

We report the emission of high-field terahertz pulses from a GaAs large-area photoconductive emitter pumped with a Ti:Sapphire amplifier laser system at 800 nm wavelength and 1 kHz repetition rate. The maximum estimated terahertz electric field at the focus is ≳ 230 kV/cm. We also demonstrate the capability of the terahertz field to cause a non-linear effect, which usually requires high-field terahertz pulses generated through optical rectification or an air plasma. A significant drop in the optical conductivity of optically pumped GaAs due to Γ-L inter-valley scattering of free electrons caused by the strong THz field is found.

Keywords: Terahertz sources; Nonlinear THz; Photoconductive emitter

Related publications

Publ.-Id: 32614

Advanced Git Usage

Erxleben, F.

A talk and demo session on various topics of advanced usage regarding the version control system Git.

Keywords: Git; Talk

  • Open Access Logo Lecture (others) (Online presentation)
    PCD Data Science Basics, 11.05.2021, Hamburg, Deutschland


Publ.-Id: 32613

Fundamental investigations of actinide immobilization by incorporation into solid phases relevant for final disposal

Huittinen, N. M.; Hennig, C.; Murphy, G. L.; Peters, L.; Tonnesen, T.; Winkler, B.

This contribution provides an overview of a current research network funded by the German Federal Ministry of Education and Research (BMBF), entitled “Fundamental investigations of actinide immobilization by incorporation into solid phases relevant for final disposal” – AcE. The AcE project aims at understanding the incorporation and immobilization of actinides (An) in crystalline, repository-relevant solid phases, such as zirconia (ZrO2) and UO2, but also in zircon (ZrSiO4), pyrochlores (Ln2Zr2O7) and orthophosphates of the monazite type (LnPO4), which may find use as host matrices for the immobilization and safe disposal of high-level waste streams.
The main objectives of the AcE project are (i) the development of synthesis strategies for An(IV)-doped solid phases, (ii) understanding their associated structural and physical properties using combined modelling and experimental approaches and (iii) determining their performance after irradiation with particular regard to an assessment of their long-term stability, dissolution behavior, and suitability for An matrix incorporation.
Recent results obtained for ZrO2, the main corrosion product of the Zircaloy cladding material surrounding nuclear fuel rods, in terms or actinide immobilization and radiation tolerance, will also be discussed.
ZrO2 is monoclinic phase (P21/c) at ambient conditions, and transforms into tetragonal (P42/nmc) and cubic phases (Fm3 ̅m) at high temperatures of around 1200 °C and 2370 °C, respectively. However, particle size effects, the incorporation of foreign ions such as the actinides, as well as high radiation fields are known to also influence the stability fields of the polymorphs. A short overview of experimental studies conducted by the AcE partners, addressing both the ZrO2 bulk structure, irradiation-induced

Related publications

  • Lecture (Conference) (Online presentation)
    MRS 2021 – 45th Scientific Basis for Nuclear Waste Management (SBNWM), 24.-29.10.2021, Köln, Deutschland

Publ.-Id: 32612

Stratigraphy, depositional setting, and Shrimp U-Pb geochronology of the banded iron formation–bearing Bailadila group in the Bacheli iron ore mining district, Bastar Craton, India

Mukhopadhyay, J.; Armstrong, R. A.; Gutzmer, J.; de Kock, M.; Beukes, N. J.

The Bailadila Group of the Bastar Craton, India, is host to a 200-m-thick banded iron formation (BIF). We document the lithostratigraphic context for the BIF, informally referred to as the Bose iron formation, and provide radiometric constraints for its depositional age. Field evidence illustrates that the BIF was deposited on an inner-shelf succession with a quartz arenite that grades upward into the BIF through storm-dominated offshore shelf deposits. The quartz arenite to BIF transition records a relative sea level rise from transgressive to highstand systems tract when the BIFs were deposited in a starved outer continental shelf. U-Pb SHRIMP analyses of zircons from the basement of the Bailadila Group yielded mostly highly discordant U-Pb SHRIMP ages. However, the ages fall on well-defined discordia lines from which concordia intercept ages could be determined. These ages, in combination with the ages of a few zircons that are less than 6% discordant, indicate that the granitoid basement crystallized at 3500–3550 Ma. The maximum depositional age of the Bailadila Group is constrained from the weighted mean207 Pb/206 Pb SHRIMP age of 2725 5 57 Ma from detrital zircons from the basal arenites. A well-constrained weighted mean207 Pb/206 Pb SHRIMP age of 2733 5 53 Ma for zircons from a unit that unconformably overlies the Bailadila Group is within error of that age. Stratigraphic relationships suggest that the Bailadila succession is unconformably overlain by the ~2.5 Ga Kotri and Dongargarh Supergroups. The depositional age of the Bailadila Group is well constrained between ~2.7 and 2.5 Ga. In contrast to most other Archean Algoma-type iron formations of peninsular India, which are closely related to volcanic rocks in greenstone belts, the Bose iron formation is associated with siliciclastic shelf succession. It thus is considered a Superior-type iron formation that represents the oldest known one of its kind in India.

Keywords: banded iron formation; Bastar Cartoon; stratigraphy; age

Publ.-Id: 32611

Towards standalone attitude estimation for instrumented flow followers

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

A concept for 3D-motion tracking of instrumented flow-following sensor particles, equipped with a gyroscope, accelerometer, magnetometer and pressure sensor, has been developed. Consisting of an error state Kalman filter (ESKF) the algorithm can track the attitude of the sensor particle in relation to a reference coordinate system. In this short paper we investigated if the estimated attitude returns to the reference trajectory after experiencing motion similar to a motion that is expected to be found in the multidisperse fluid flows of a biogas fermenter or a waste water treatment basin. Results show the feasibility of the proposed method. However, the strategy of the measurement update in the ESKF needs improvement.

Keywords: error state kalman filter; motion tracking; fluid dynamics; sensor particle; soft sensor

  • Open Access Logo Contribution to proceedings
    Sensor and Measurement Science International 2021, 03.-06.05.2021, Online, Deutschland
    SMSI 2021 - Sensors and Instrumentation, Wunstorf: AMA Service GmbH, 978-3-9819376-4-0, 141-142
    DOI: 10.5162/SMSI2021/B6.3


Publ.-Id: 32610

Sustainable Development Goal Conflicts in Re-Mining activities

Büttner, P.; Gutzmer, J.; Engelhardt, J.; Martin, M.

The Davidschacht tailings storage facility (TSF), operated from 1944 to 1964, represents one of the largest tailings dams in the historic Freiberg mining district. It contains a volume of 760,000 m³ of sulfidic flotation tailings, residues of former base metal and silver ore beneficiation. The tailings material still contains elevated concentrations of valuable elements such as zinc (0.4 wt.% on average), lead (0.2 wt.%) and copper (0.05 wt.%) as well as indium (10 ppm). The material has thus become the focus of efforts to enable eventual re-mining and recovery of valuable metals. However, such efforts have to take into account a number of important interests of the public. The first of these is the fact that the unrehabilitated tailings pose a significant risk to the environment. Cd (44 ppm on average) and As (0.6 wt.%) concentrations are particularly high – and have a marked influence on the adjacent water bodies, such as the Freiberg Mulde river. Curbing this influence has been the subject of multiple remediation studies, but pressure to act has risen recently due to increasing regulatory demands on the quality of surface water (EU Water Framework Directive of 2000). This is, in principle, very much in favour of re-mining the tailings in an effort to remove also hazardous components. Counteracting this reclamation scenario is the fact that the TSF is part of the UNESCO World Heritage Site “Erzgebirge / Krusne Hory” that was awarded in 2019. Another restriction pertains to the highly protected status of individual species (esp. sand lizard) settling on the TSF surface. This constellation obviously provides ample space for discussion as to how to deal with the tailings material contained in the Davidschacht TSF in future. Different sustainable development goals (SDG) have to be weighed against each other in order to find a holistic and sustainable. Airlift reactor-based bioleaching has been considered as an opportunity to maximize the sustainability of re-mining activities on the Davidschacht TSF. This innovative approach – and its circumstantial limitations – are documented in this contribution.

Keywords: Re-Mining; recomine; Tailing; Davidschacht; HIF; Resource Technology; Freiberg; Sustainable Development Goals; SDG; Bioleaching

Publ.-Id: 32609

Pathophysiological Changes in the Enteric Nervous System of Rotenone-Exposed Mice as Early Radiological Markers for Parkinson's Disease

Schaffernicht, G.; Shang, Q.; Stievenard, A.; Bötzel, K.; Dening, Y.; Kempe, R.; Toussaint, M.; Gündel, D.; Kranz, M.; Reichmann, H.; Vanbesien-Mailliot, C.; Brust, P.; Dieterich, M.; Funk, R. H. W.; Ravens, U.; Pan-Montojo, F.

Parkinson's disease (PD) is known to involve the peripheral nervous system (PNS) and the enteric nervous system (ENS). Functional changes in PNS and ENS appear early in the course of the disease and are responsible for some of the non-motor symptoms observed in PD patients like constipation, that can precede the appearance of motor symptoms by years. Here we analyzed the effect of the pesticide rotenone, a mitochondrial Complex I inhibitor, on the function and neuronal composition of the ENS by measuring intestinal contractility in a tissue bath and by analyzing related protein expression. Our results show that rotenone changes the normal physiological response of the intestine to carbachol, dopamine and electric field stimulation (EFS). Changes in the reaction to EFS seem to be related to the reduction in the cholinergic input but also related to the noradrenergic input, as suggested by the non-adrenergic non-cholinergic (NANC) reaction to the EFS in rotenone-exposed mice. The magnitude and direction of these alterations varies between intestinal regions and exposure times and is associated with an early up-regulation of dopaminergic, cholinergic and adrenergic receptors and an irregular reduction in the amount of enteric neurons in rotenone-exposed mice. The early appearance of these alterations, that start occurring before the substantia nigra is affected in this mouse model, suggests that these alterations could be also observed in patients before the onset of motor symptoms and makes them ideal potential candidates to be used as radiological markers for the detection of Parkinson's disease in its early stages.

Keywords: Parkinson's disease; enteric nervous system; non-motor symptoms; pathophysiology; radiological marker


Publ.-Id: 32608

Half-Auxeticity and Anisotropic Transport in Pd Decorated Two-Dimensional Boron Sheets

Ma, F.; Jiao, Y.; Wu, W.; Liu, Y.; Yang, S. A.; Heine, T.

Upon strain, most materials shrink normal to the direction of applied strain. Similarly, if a material is compressed, it will expand in the direction orthogonal to the pressure. Few materials, those of negative Poisson ratio, show the opposite behavior. Here, we show an unprecedented feature, a material that expands normal to the direction of stress, regardless if it is strained or compressed. Such behavior, namely, half-auxeticity, is demonstrated for a borophene sheet stabilized by decorating Pd atoms. We explore Pd-decorated borophene, identify three stable phases of which one has this peculiar property of half auxeticity. After carefully analyzing stability and mechanical and electronic properties we explore the origin of this very uncommon behavior and identify it as a structural feature that may also be employed to design further 2D nanomaterials.

Keywords: two-dimensional materials; auxetic materials; borophene; buckling structure; first-principle calculation


Publ.-Id: 32607

Curvature-driven homogeneous Dzyaloshinskii-Moriya interaction and emergent weak ferromagnetism in anisotropic antiferromagnetic spin chains

Pylypovskyi, O.; Borysenko, Y. A.; Faßbender, J.; Sheka, D.; Makarov, D.

Chiral antiferromagnets are currently considered for a broad range of applications in spintronics, spin-orbitronics, and magnonics. In contrast to the established approach relying on materials screening, the anisotropic and chiral responses of low-dimensional antiferromagnets can be tailored relying on the geometrical curvature. Here, we consider an achiral, anisotropic antiferromagnetic spin chain and demonstrate that these systems possess geometry-driven effects stemming not only from the exchange interaction but also from the anisotropy. Peculiarly, the anisotropy-driven effects are complementary to the curvature effects stemming from the exchange interaction and rather strong as they are linear in curvature. These effects are responsible for the tilt of the equilibrium direction of vector order parameters and the appearance of the homogeneous Dzyaloshinskii–Moriya interaction. The latter is a source of the geometry-driven weak ferromagnetism emerging in curvilinear antiferromagnetic spin chains. Our findings provide a deeper fundamental insight into the physics of curvilinear antiferromagnets beyond the σ-model and offer an additional degree of freedom in the design of spintronic and magnonic devices.

Keywords: antiferromagnetism; curvilinear magnetism; Dzyaloshinskii-Moriya interaction; anisotropy

Publ.-Id: 32606

Diffusion of In Atoms in SiO2 Films Implanted with As+ Ions

Tyschenko, I. E.; Voelskow, M.; Si, Z.; Popov, V. P.

The diffusion of indium atoms in silicon-dioxide films previously implanted with arsenic ions with different energies is studied in relation to the temperature of postimplantation annealing. It is established that the diffusion properties of indium depend on the presence of arsenic atoms in the film and their energy. An increase in the As content in the region of the average projective range of In+ ions prevents the diffusion of In towards the SiO2 film surface at high annealing temperatures and stimulates the diffusion of In deep into the film in the form of a monovalent interstitial site. The experimentally observed effects are interpreted on the assumption of the formation of In–As pairs in neighboring substitutional positions in the SiO2 matrix.

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Publ.-Id: 32605

Spin polarization and magnetotransport properties of systematically disordered Fe60Al40 thin films

Borisov, K.; Ehrler, J.; Fowley, C.; Eggert, B.; Wende, H.; Cornelius, S.; Potzger, K.; Lindner, J.; Faßbender, J.; Bali, R.; Stamenov, P.

We investigate the evolution of spin polarization, spontaneous Hall angle (SHA), saturation magnetization and Curie temperature of B2-ordered Fe60Al40 thin films under varying antisite disorder, induced by Ne+-ion irradiation. The spin polarization increases monotonically as a function of ion fluence. A relatively high polarization of 46 % and the SHA of 3.1 % are achieved on 40 nm thick films irradiated with 2 ⋅ 1016 ions/cm2 at 30 keV. An interesting divergence in the trends of the magnetization and SHA is observed for low disorder concentrations. The high spin polarization and its broad tunability range make ion-irradiated Fe60Al40 a promising material for application in spin electronic devices.

Keywords: Spin polarization; Iron-Aluminium; Spintronics; Anomalous Hall Effect; Topological Hall effect; Irradiation effects; Thin films; Magnetometry; Andreev reflection

Related publications


Publ.-Id: 32604

Statistical position reconstruction for RPC-based thermal neutron detectors

Morozov, A.; Margato, L. M. S.; Solovov, V.; Blanco, A.; Saraiva, J.; Wilpert, T.; Zeitelhack, K.; Roemer, K.; Hall-Wilton, R.

Multilayer position-sensitive 10B-RPC thermal neutron detectors offer an attractive combination of
sub-millimeter spatial resolution and high (>50%) detection efficiency. Here we describe a new
position reconstruction method based on statistical approach. Using experimental data, we compare
performance of this method with that of the centroid reconstruction. Both methods results in a
similar image quality and spatial resolution. However, the statistical method allows to improve the
image quality at the detector periphery, offers more flexible (and more easily configurable) event
filtering and allows to develop automatic quality monitoring procedures for early detection of
situations when a change in the detector operation conditions starts to affect reconstruction quality.

Keywords: RPC; spatial resolution; neutron detection


Publ.-Id: 32602

Software: Method for real-time controlled tissue theranostics using a single adaptable laser source

Podlipec, R.

Software support for real-time quantification of the treatment effect on the targeted tissue induced by a pulsed laser. Model functions used to quantify laser treatment effect are based on the calculated descriptor values from FLIM (Fluorescence lifetime imaging microscopy) and AF (autofluorescence) diagnostics images done on human retinal tissue using SPC Image software (B&H).

Related publications


Publ.-Id: 32601

ExPaNDS periodic progress report, September 2019 to February 2021

Servan, S.; Konrad, U.

This document presents the progress of the ExPaNDS (European Open Science Cloud Photon and Neutron Services) project after i ts first 18 months of activities, spanning from September 2019 to February 2021. It reproduces the explanation of the work carried out by the ExPaNDS partners as provided to the European Commission in the first periodic report of the project.

Keywords: EOSC; European Open Science Cloud; Photon Science; Neutron Science; Big Data; Information Technology; Forschungsdaten; Reasearch Data

Related publications

Publ.-Id: 32600

Dataset: Method for real-time controlled tissue theranostics using a single adaptable laser source

Podlipec, R.

Raw data of theranostics laser parameters and calculated descriptor values from FLIM (Fluorescence lifetime imaging microscopy) and AF (autofluorescence) retinal diagnostics for real-time quantification of the treatment effect.

Related publications


Publ.-Id: 32599

IV-data for Complex Metal Nanostructures with Programmable Shapes from Simple DNA Building Blocks

Jain, A.; Bayrak, T.; Erbe, A.

IV-curves measured on self-organized Au nanogaps. HSQ-wires are 10 nm gaps without DNA molecules, to characterise the insulating properties of HSQ resist. Au_nanowire are measurements of continuous Au nanowires. The temperature dependent measurements characterize self-organised Au contacts to DNA ensembles with 10 nm length

Keywords: Nanoelectronics; Self-Organisation; DNA Origami

Related publications


Publ.-Id: 32598

Method for controlled tissue theranostics using a single tunable laser source

Podlipec, R.; Mur, J.; Petelin, J.; Štrancar, J.; Petkovšek, R.

Tissue diseases and related disorders need to be first recognized using diagnostic methods and then later treated by therapeutic methods–a joint procedure called theranostics. One of the main challenges in the field of retinal therapies remains in the success of the treatment, typically improving the local metabolism, by sparing the surrounding tissue and with the immediate information of the laser effect. In our study, we present a concept for real-time controlled tissue theranostics on a proof-of-concept study capable of using a single tunable ps
laser source (in terms of irradiance, fluence, and repetition rate), done on ex-vivo human retinal pigment epithelium. We have found autofluorescence intensity and lifetime imaging diagnostics very promising for the recognition and quantification of laser effects ranging from selective non-destructive molecular tissue modification to complete tissue ablation. The main novelty of our work presents the developed algorithm for optimized theranostics based on the model function used to quantify laser-induced tissue changes through the diagnostics
descriptors, fluorescence lifetime and fluorescence intensity parameters. This approach, together with the operation of the single adaptable laser source, can serve as a new theranostics method in personalized medicine in the future not only limited to treat retinal diseases.

Publ.-Id: 32597

A novel approach for the geospatial modelling and resource assessment of tailings storage facilities

Blannin, R.; Frenzel, M.; Gutzmer, J.

Tailings are the fine-grained residues of ore processing operations, typically stored in dedicated tailings storage facilities (TSFs). Despite being viewed as ‘waste’ materials, tailings can contain significant amounts of valuable metals which were not recovered by original processing techniques or were previously not of economic interest. Re-processing of tailings deposits for the recovery of remaining metals has the additional benefits of mitigation of environmental hazards posed by the TSFs, such as Acid Mine Drainage (AMD). The estimation of mineral resources requires the construction of accurate and reproducible geospatial models. However, the sedimentary-style deposition and subsequent weathering of tailings results in a complex internal structure which is challenging to model, with a laterally and vertically heterogeneous distribution of the minerals comprising the residues. The present study investigates a novel approach for the geospatial modelling of a TSF case study. The surface of the tailings deposit was densely sampled in order to assess the intrinsic horizontal variability. Drill core samples were taken from a depth of 1-3 m, on a 30 m grid and nested grids of 15 m and 7.5 m, with additional random and twin holes. The entire depth of the TSF was sampled in 2 m intervals with a total of 10 drill holes to assess vertical variability. All drill core samples were analysed with x-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. The compositional data was log-ratio-transformed and variography and subsequent ordinary kriging and co-kriging were performed on the surface samples. The variogram models obtained for the surface samples were then applied for kriging of the deeper layers. Historical photographs of the surface of the TSF were used to improve estimates with co-kriging for the corresponding layers. The entire data set will be used to determine the most efficient sampling approach for the resource estimation of TSFs.

  • Open Access Logo Contribution to proceedings
    European Geosciences Union General Assembly 2021, 26.-30.04.2021, Vienna, Austria
    DOI: 10.5194/egusphere-egu21-2992

Publ.-Id: 32595

[¹⁸F]JHU94620-d₈ – A new radiotracer for the noninvasive in vivo assessment of the CB₂ receptor in brain and peripheral tissues by PET

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

An upregulation of cannabinoid receptors type 2 (₂) has been reported in association with inflammation processes, traumatic brain injury, neurodegeneration and cancer.[1] The activation of ₂ leads to an anti-inflammatory action. Therefore, the non-invasive assessment of the ₂ availability with PET can support decisions for ₂-directed therapies. Recently, we have reported on the development of the PET radiotracer [¹⁸F]JHU94620. This radioligand suffers from low metabolic stability in vivo.[2] Here, we describe the deuterated analogue [¹⁸F]JHU94620-d₈ and its biological evaluation.
The precursor for radiofluorination was obtained by coupling 4,5-dimethylthiazol-ylidene-2,2,3,3-tetramethylcyclopropane-1-carboxamide with 1,4-butandiol-1,1,2,2,3,3,4,4-d₈ bis(4-methylbenzenesulfonate) and radiofluorinated in the presence of the Kryptand K2.2.2. and K2CO3. The fraction of radiometabolites after injection of 27 to 50 MBq i.v. (AM ≈ 150 GBq/µmol) was quantified in mice plasma and brain 30 min p.i. The ₂ binding affinity (KD) and specificity (Ki) of [¹⁸F]JHU94620-d₈ was determined in vitro. Additionally, PET studies (injection of 23 ± 5 MBq i.v.) were performed to evaluate the [¹⁸F]JHU94620-d₈ uptake into the spleen of adult healthy Wistar rats and in rats overexpressing the functional inactive h₂(D𔕐N) in the right striatum[3] (h₂-rs).
[¹⁸F]JHU94620-d₈ was obtained in 10% radiochemical yield and >99% radiochemical purity, showing an improved metabolic stability of the deuterated analogue (80% vs. 36% for [¹⁸F]JHU94620, determined in the brain 30 min p.i.). It revealed a KD on rat ₂ of 0.36 nM and on human ₂ of 2.72 nM, as well as a Ki(hCB1) > 1 µM and Ki(h₂) of 0.9 nM. PET studies revealed a ₂-specific uptake of [¹⁸F]JHU94620-d₈ into the rat spleen (AUC0-30min = 33 vs. 17 SUV × min after blocking with GW405833). In the h₂-rs rats we could show a reversible and target-specific uptake of [¹⁸F]JHU94620-d₈ with an SUVmean of 6.7 ± 0.3 from 6 to 60 min p.i. and an SUVr (right striatum-to-cerebellum) of 43 ± 7 at 60 min p.i.
[¹⁸F]JHU94620-d₈ is a new PET tracer with improved metabolic stability as compared with the non-deuterated version, thus indicating an excellent ability to image the ₂ receptors in vivo.
This research was funded by Deutsche Forschungsgemeinschaft (DFG), grant number MO2677/4-1
A German patent application was filed Nr. 10 2020118 255.4
[1] Stasiulewicz, A., Znajdek, K., et al. 2020, ‘A Guide to Targeting the Endocannabinoid System in Drug Design’, IJMS, 2020, 21, 2778; doi:10.3390/ijms21082778
[2] Moldovan, R.-P., Deuther-Conrad, W., et al., 2015, ‘¹⁸F-JHU94620, a high affinity PET radioligand for imaging of cannabinoid subtype 2 receptors (₂R)’, J. Nucl. Med., 56, 1048
[3] Attili, B., Celen, S., et al., 2019, ‘Preclinical evaluation of [¹⁸F]MA3: a ₂ receptor agonist radiotracer for PET’, Br. J. Pharmacol., 176, 1481-1491

Keywords: PET; cannabinoid receptor 2; CB2

  • Poster
    EMIM2021, 24.-27.08.2021, Göttingen, Deutschland

Publ.-Id: 32588

Investigation of the radioactive inventory in the reactor pressure vessel of a nuclear power plant - a key for efficient nuclear waste disposal

Yassin, G.; Barkleit, A.; Brendler, V.

One of the most important activities after the decommissioning process of the nuclear power plant NPP is the determination of the neutron activated radionuclides RNs in the construction material of the reactor. Our work is mainly focused on the dismantled units of reactor pressure vessel RPV of Greifswald NPP. For this aim, both nondestructive and destructive methods were employed. Firstly, surface analysis methods based on scanning electron microscopy / energy dispersive X-ray spectroscopy SEM / EDX were performed, in order to understand the impact of the neutron fluencies on the RPV steel shielding material during the long-term operation. Furthermore, gamma spectrometry measurements were done for the analysis of the activity of the gamma emitting RN of Co-60 in the decommissioned RPV units. On the other hand, the determination of the long lived beta emitting RNs such as C-14 was determined by employing a commercial sample oxidizer, followed by liquid scintillation counting LSC measurements. Radiochemical procedure including precipitation, anion exchange chromatography and extraction steps was developed for the separation and purification of Ni-63 and Fe-55 prior to their activity determination.

  • Open Access Logo Contribution to proceedings
    9. RCA Workshop, 08.-09.06.2021, Dresden, Deutschland
    Proceedings of the 9. RCA Workshop
  • Poster
    9. RCA Workshop, 08.-09.06.2021, online, Germany


Publ.-Id: 32587

Grobstruktursimulation blasenbehafteter Strömungen mittels eines hybriden Mehrphasenmodells

Meller, R.


In einer Vielzahl industrieller Prozesse spielen Strömungen mit verschiedenen gasförmigen und flüssigen Phasen eine wichtige Rolle. Die Phasengrenzflächen bilden sehr große Strukturen aus, wie z. B. eine freie Wasseroberfläche. Gleichzeitig können kleine, s. g. disperse Strukturen wie Gasbläschen auftreten. Um auch komplexe Prozesse zu simulieren ohne die Art der Strömung im Vorhinein zu kennen, werden unterschiedliche Methoden zur numerischen Beschreibung der verschiedenen Strömungstypen miteinander kombiniert. In der vorliegenden Arbeit wird die Euler-Euler-Methode für disperse Strukturen mit der algebraischen Volume-Of-Fluid-Methode für großskalige Phasengrenzflächen kombiniert. Das auf diese Weise formulierte hybride Mehrphasenmodell wird im Mehr-Fluid-Modell für eine beliebige Anzahl von Phasen formuliert, d. h. für jede vorhandene Phase gelten individuelle Erhaltungsgleichungen für Masse und Impuls. Für disperse Strömungen werden Formulierungen aus der Literatur für den Strömungswiderstand und die virtuelle Masse von Gasblasen genutzt, um den Impulsaustausch zwischen den verschiedenen Phasen zu beschreiben. Für großskalige Phasengrenzflächen wird das Widerstandsmodell von Štrubelj und Tiselj (2011) verwendet, mit dessen Hilfe die Impulserhaltungsgleichungen der individuellen Phasen stark aneinander gekoppelt werden. Zur Beschreibung des Platzens von Gasbläschen an einer freien Oberfläche wird eine neue Formulierung des Phasentransfers eingeführt, womit disperses in kontinuierliches Gas überführt wird.
Für die numerische Lösung des resultierenden Gleichungssystems wird die kompakte Impulsinterpolation von Cubero et al. (2014) genutzt. Die starke Kopplung der phasen-spezifischen Gleichungen für den Impulserhalt erfordert besondere numerische Maßnahmen, um das gesamte Gleichungssystem effizient zu lösen. Dazu wird die Methode der partiellen Eliminierung von Spalding (1981) durch eine Summenformulierung zur näherungsweise Auflösung dieser Kopplung auf das Mehr-Fluid-Modell erweitert. Anhand von zwei- und dreidimensionalen Fällen von aufsteigenden einzelnen Gasblasen wird nachgewiesen, dass das hybride Modell das Verhalten des Ein-Fluid-Modells zur Beschreibung großskaliger Phasengrenzflächen beschreiben kann. Darüber hinaus wird die Funktionsweise der Methode demonstriert, die Interaktion zwischen kleinen Gasbläschen und großskaliger Phasengrenzflächen zu beschreiben. Dies schließt den Phasentransfer von dispersem zu kontinuierlichem Gas ein.
In der Realität sind viele Strömungen turbulent und analog zu den Phasengrenzflächen sind die turbulenten Wirbel typischerweise von sehr verschiedenen Längenskalen. Ein möglicher Weg, solche Probleme numerisch zu beschreiben, ist die Grobstruktursimulation (engl. large-eddy simulation). Dazu werden die Erhaltungsgleichungen räumlich tiefpass-gefiltert. Dadurch entstehen im hiesigen Mehr-Fluid-Modell fünf ungeschlossene Feinstrukturterme, zu denen die Terme der konvektiven Feinstrukturspannungen und der Feinstruktur-Oberflächenspannung gehören. Für die Abschätzung dieser beiden Terme werden unterschiedliche Modelle genutzt. Bei manchen dieser Modelle wird die Struktur der Phasengrenzfläche direkt berücksichtigt. Der Einfluss dieser Modelle auf die Interaktion zwischen der Turbulenz und der Phasengrenzfläche wird anhand von Testfällen einzelner aufsteigender Gasblasen a posteriori untersucht.


Flows of gaseous and liquid phases play an important role in numerous industrial processes. The interface, which is the contact surface between different immiscible phases, may form large structures, e.g., a free water surface. At the same time small, so-called disperse structures such as micro gas bubbles may appear.In order to numerically describe such complex processes without knowing the type of flow in advance, different methods for the numerical description of different kinds of flows are combined with each other. In the present work the Euler-Euler method is applied for disperse structures and the algebraic volume-of-fluid method is used to describe large scale interfaces. The resulting hybrid multiphase model is formulated in the context of the multi-fluid model for an arbitrary number of phases, i.e., for each phase present individual conservation equations are considered for mass and momentum. This requires the definition of model forces to express the momentum transfer between different phases. For disperse flows appropriate formulations for drag and virtual mass of gas bubbles from the literature are employed. For large scale interfaces the drag model of Štrubelj and Tiselj (2011) is used, which strongly couples the momentum equations of the individual phases together. In order to describe the process of gas bubbles bursting at a free surface a new phase transfer formulation is introduced, such that disperse gas can be turned into continuous one.
The compact momentum interpolation according to Cubero et al. (2014) is utilized for the numerical solution of the resulting system of equations. The strong coupling of phase specific momentum conservation equations requires special treatment to allow the system of equations to be numerically solved in an efficient way. Therefore, the partial elimination algorithm of Spalding (1981) is expanded to the multi-field model via a sum formulation with the goal of an approximate resolution of phase coupling. The functionality of the hybrid method to reproduce the behaviour of the one-fluid model for the description of large scale interfaces is proven with several two- and three-dimensional test cases considering individual rising gas bubbles. Furthermore, the method's ability to predict interactions of small gas bubbles and large scale interfaces is demonstrated, which includes the phase transfer from disperse to continuous gas.
In reality many flows are turbulent and the according eddies are typically of widely varying length scales, just as it is the case for interfacial structures. Large-eddy simulation is a common approach to describe such problems numerically. Therefore, the conservation equations are spatially low-pass filtered, which leads to five unclosed sub-grid scale terms in the case of the presented multi-fluid model. Two of them are the convective sub-grid stress and the sub-grid surface tension term, which are modelled via several individual formulations taking the interface into account. The model influence on the interaction between turbulence and interface is assessed a posteriori considering single rising gas bubbles.

  • Doctoral thesis
    Universität der Bundeswehr München, 2021
    Mentor: Prof. Dr.-Ing. habil. Markus Klein
    183 Seiten

Publ.-Id: 32586

Classification and resolution adaptive drag modelling of gas-liquid interfaces with a multifield two-fluid model

Meller, R.; Tekavcic, M.; Krull, B.; Schlegel, F.

Reliable techniques for the numerical simulation of gas-liquid flows at industrial scales are of great interest for safety analysis and efficiency optimisation, e.g. in nuclear power or metal processing industries. This type of simulation is hard to carry out due to the immense range of scales, which is spanned by interfacial and turbulent structures. For this purpose, hybrid morphology-adaptive numerical frameworks are being developed in the recent years, combining different well established numerical methods for individual flow regimes. The present work follows the approach of Meller et al. (Int J Numer Meth Fluids. 2021; 93: 748-773), who utilise the Euler-Euler approach to statistically describe multiphase structures in dispersed flow regimes, such as bubbly flows, as a basis. At the same time, regimes with resolved gas-liquid interfaces, such as large rising gas bubbles or horizontal interfaces in stratified flows, are captured by means of a Volume-of-Fluid-like method (Tekavčič et al., Nucl Eng Des. 2021; 379: 111223). A fully morphology-adaptive numerical framework needs to comprise transitions between the aforementioned regimes. Hence, the limits of both underlying basic numerical approaches need to be pushed towards and beyond an overlapping region of grid resolution with adequate predictive power, such that the whole spectrum of length scales is covered, forming the basis of morphology transitions.
For this purpose, the present work focuses on the extension of the Volume-of-Fluid methodology towards reliable resolved simulations of gas-liquid interfaces with very coarse grid resolutions. By means of the underlying two-fluid model, an interfacial slip velocity in the interface region becomes generally possible and can be chosen physically motivated. The flow in the vicinity of the interface needs to be classified. For this purpose, the latter is categorised to be of shear type, stagnant type or in between the two. Furthermore, a dimensionless grid spacing is evaluated based on the shear stress across the interface, similarly to the y+ value for the cell thickness of wall-bounded flows. Besides that, interface curvature is considered in relation to grid spacing. From these information, a degree of under-resolution of the interface is determined, which subsequently serves as a criterion for the drag modelling framework. On this basis, interfacial drag coupling is manipulated, such that interfacial slip can take place in the direction tangential to the interface, whenever required. While the interfacial drag formulation of Štrubelj and Tiselj (Int J Numer Methods Engng. 2011; 85: 575-590) is used in case of proper resolution, the closure formulations of Porombka and Höhne (Chem Eng Sci. 2015; 134: 348-459) or Marschall (Technical University of Munich, PhD Thesis, 2011) are considered for portions of the computational domain, where interfaces are classified to be under-resolved. The functionality of the described procedure is validated in cases of 2D and 3D rising gas bubbles, considering their shape and rising velocity. Moreover, gas and liquid velocity profiles of a stratified flow serve as a validation in an additional flow regime.
In this way, the numerical prediction of the gas-liquid interface is improved, pushing the limit of spatial resolutions with adequately reliable predictions towards extremely coarse computational grids, which is the prerequisite for efficient numerical simulations in large-scale applications.

  • Lecture (Conference)
    30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slowenien
  • Contribution to proceedings
    30th International Conference Nuclear Energy for New Europe, 06.-09.09.2021, Bled, Slovenija
    NENE 2021 conference proceedings, Ljubljana: Nuclear Society of Slovenia, 978-961-6207-51-5, 601.1-601.9

Publ.-Id: 32585

Revealing inflammatory indications induced by titanium alloy wear debris in periprosthetic tissue by label-free correlative high-resolution ion, electron and optical micro-spectroscopy

Podlipec, R.; Punzón-Quijorna, E.; Pirker, L.; Kelemen, M.; Vavpetič, P.; Kavalar, R.; Hlawacek, G.; Štrancar, J.; Pelicon, P.; Fokter, S. K.

The metallic-associated adverse local tissue reactions (ALTR) and events accompanying worn-broken implant materials are still poorly understood on the subcellular and molecular lev-el. Current immunohistochemical techniques lack spatial resolution and chemical sensitivity to investigate causal relations between material and biological response on submicron or even na-noscale. In our study, new insights of titanium alloy debris-tissue interaction were revealed by the implementation of label-free high-resolution correlative microscopy approaches. Wear debris chemical and biological impact on the surrounding periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis was suc-cessfully characterized by applying a combination of photon, electron and ion beam mi-cro-spectroscopy techniques, that includes hybrid optical fluorescence and reflectance mi-cro-spectroscopy, scanning electron microscopy (SEM), Energy-dispersive X-ray Spectroscopy (EDS), helium ion microscopy (HIM) and micro-particle-induced X-ray emission (micro-PIXE). Micron-sized wear debris was found as the main cause of the tissue oxidative stress exhibited through lipopigments accumulation in the nearby lysosomes. Furthermore, insights on extensive fretting and corrosion of the debris on nm scale and a quantitative measure of significant Al and V release into the tissue together with hydroxyapatite-like layer formation particularly bound to the regions with the highest Al content were revealed. The functional and structural information obtained at the molecular and subcellular level contributes to a better understanding of the mac-roscopic inflammatory processes observed on the tissue level. The established label-free correla-tive microscopy approach can efficiently be adopted to study any other clinical cases related to ALTR.

Keywords: Adverse Local Tissue Reactions (ALTR); periprosthetic tissue; Titanium alloy wear debris; correlative microscopy; confocal fluorescence and reflectance microscopy; FLIM; SEM-EDS; HIM; micro-PIXE; fHSI

Related publications

Publ.-Id: 32584

An efficient route to obtain (radio)fluorinated or (radio)iodinated 1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid (TIC(OH)) analogues as potential radiotracers for imaging of solid tumours

Maisonial-Besset, A.; Noelia Chao, M.; Debiton, E.; Canitrot, D.; Witkowski, T.; Degoul, F.; Tarrit, S.; Wenzel, B.; Miot-Noirault, E.; Serre, A.; Chezal, J.-M.


The use of radiolabelled amino acids (AAs) can provide high contrast SPECT/PET imaging of solid tumours. Among them, radiohalogenated tyrosine analogues ([123I]IMT, [18F]FDOPA, [123I]8-iodo-L-TIC(OH), etc) were developed mainly for imaging of neuroendocrine, prostatic and brain tumours. While radioiodinated derivatives are easily available via electrophilic aromatic substitutions with radioactive I+, radiofluorinated tyrosine analogues are difficult to obtain. Indeed, direct radiofluorination of electron-rich aromatic structures from [18F]F- remains a challenge as evidenced by the number of emerging methods recently published. The progresses reported for the radiosynthesis of the [18F]FDOPA illustrate the new opportunities to produce radiofluorinated arenes that could not be routinely accessed even a few years ago. Surprisingly, the [123I]8-iodo-L-TIC(OH), a promising radiotracer for SPECT imaging of prostatic tumours, did not benefit from these methodological advances and no corresponding radiofluorinated derivatives, which could allow the use of the TIC(OH) scaffold to PET imaging, were reported so far.

Materials and Methods:

A convergent synthetic route was developed to produce radioiodinated [125I]iodo-L-TIC(OH), and radiofluorinated [18F]fluoro-L-TIC(OH) tracers from common organotin intermediates, synthesized from iodinated analogues via palladium catalyzed I/SnMe3 exchange. The [125I]iodo-L-TIC(OH) radiotracers were obtained by electrophilic radioiododestannylation with [125I]I+, while the radiofluorinated analogues [18F]fluoro-L-TIC(OH) were produced from the organotin precursors by a copper-mediated aromatic radiofluorination using nucleophilic [18F]F-. For control of the purity, molar activity and enantiomeric excess, corresponding non-radiolabelled iodinated and fluorinated derivatives from the L and D series were synthesized.


Organotin compounds were radiolabelled using no-carrier-added [125I]NaI in the presence of Chloramine-T as mild oxidative agent at room temperature for 5 minutes with excellent labelling efficiencies (> 95%). After a two-step deprotection sequence and semipreparative RP-HPLC purification, [125I]iodo-L-TIC(OH) compounds were isolated with good radiochemical yields (RCY, 51-78%), high radiochemical purities (RCP, > 98%), molar activities (> 1.5-2.9 GBq/µmol) and enantiomeric excess (e.e., > 99%). [18F]fluoro-L-TIC(OH) derivatives were obtained by radiofluorination of organotin compounds in presence of tetrakis(pyridine)copper(II) triflate catalyst and nucleophilic [18F]F- at 110 °C for 10 minutes with high labelling efficiencies (54-92%). After purification by C18 solid phase extraction, deprotection under acidic conditions and semipreparative RP-HPLC purification, [18F]fluoro-L-TIC(OH) radiotracers were produced with good RCY (23-37% d.c.), high RCP (> 99%), molar activities (20-107 GBq/µmol) and e.e. (> 99%).


A short and efficient synthetic pathway was developed to easily produce [125I]iodo-L-TIC(OH) and [18F]fluoro-L-TIC(OH) compounds from common organotin intermediates. In vitro studies on human cancer cell lines are ongoing to evaluate the potential of these radioligands to target AAs transporters.

  • Lecture (Conference) (Online presentation)
    34th Annual EANM Congress, 20.10.2021, virtuell, virtuell

Publ.-Id: 32583

SEM-EDS datasets of titanium alloy wear debris in periprosthetic tissue

Podlipec, R.; Pirker, L.

SEM-EDS images and datasets of titanium alloy wear debris found in periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis.

Related publications


Publ.-Id: 32582

Pump-probe data for "A Two‐Dimensional Polyimide‐Graphene Heterostructure with Ultra‐fast Interlayer Charge Transfer"

Li, J.; Pashkin, O.; Schneider, H.; Helm, M.

Pump-probe traces of transient absorption change for graphene, protonated 2DPI and protonated 2DPI on graphene

Related publications


Publ.-Id: 32581

Dynamics of Single Hydrogen Bubbles at Pt Microelectrodes in Microgravity

Bashkatov, A.; Yang, X.; Mutschke, G.; Fritzsche, B.; Hossain, S. S.; Eckert, K.

The dynamics of single hydrogen bubbles electrogenerated in acidic electrolytes at a Pt microelectrode under potentiostatic conditions is investigated in microgravity during parabolic flights. Three bubble evolution scenarios have been identified depending on the electric potential applied and the acid concentration. The dominant scenario, characterized by lateral detachment of the grown bubble, is studied in detail. For that purpose, the evolution of the bubble radius, electric current and bubble trajectories, as well as the bubble lifetime are comprehensively addressed for different potentials and electrolyte concentrations. We focus particularly on analyzing bubble-bubble coalescence events which are responsible for reversals of the direction of bubble motion. Finally, as parabolic flights also permit hypergravity conditions, a detailed comparison of the characteristic bubble phenomena at various levels of gravity is drawn.

Keywords: hydrogen; bubble; bubble dynamics; electrolysis; microgravity; microelectrode; force balance; parabolic flight; energy


Publ.-Id: 32580

Solutions for the Ages – a Short Crash Course on Sustainable Software Development

Huste, T.

As part of the International Virtual Covid Challenge this talk gives an introduction on sustainable software development. Basing on the HIFIS course "Let's Make Your Script Ready for Publication" it details the steps necessary to build a sustainable software application that can easily be cited in a scientific publication.

Keywords: Software; Sustainability; Licensing; Open Source

  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    International Virtual Covid Data Challenge 2021, 29.04.2021, Online, Deutschland
  • Open Access Logo Invited lecture (Conferences) (Online presentation)
    HIDA Annual Conference 2021, 30.11.2021, Berlin, Deutschland


Publ.-Id: 32579

Data for: Sensitivity of PS/CoPd Janus particles to an external magnetic field

Eichler-Volf, A.; Alsaadawi, Y.; Vazquez Luna, F.; Khan, Q. A.; Stierle, S.; Xu, C.; Heigl, M.; Fekri, Z.; Zhou, S.; Zahn, P.; Albrecht, M.; Steinhart, M.; Erbe, A.

Movies show the 90-degrees rotation of PS/CoPd Janus particles in weak and strong magnetic fields

EDX/SEM/XRD data were used  to characterize the the CoPd particles

Related publications


Publ.-Id: 32578

HELIPORT (HELmholtz ScIentific Project WORkflow PlaTform)

Voigt, M.; Ufer, R.; Schacht, W.; Knodel, O.; Pape, D.; Lokamani, M.; Müller, S.

The guidance system HELIPORT aims to make the entire life cycle of a project at the HZDR searchable, accessible, complete and reusable according to the FAIR principles, mentioned below. In particular, our data management solution deals with the areas from the generation of the data to the publication of primary research data, the workflows carried out and the actual research results. For this purpose, a concept was developed which shows the various essential components and their connections. Descriptions of the individual components can be found in our RODARE publication: 10.14278/rodare.193

Keywords: metadata; HELIPORT; project lifecycle; FAIR; data managment


Publ.-Id: 32577

Update on Radiation Studies for MU2E-II (and MU2E)

Müller, S.

Presentation at "Mu2e-II Snowmass22 Workshop", 28.04.2021

Keywords: FLUKA; MU2E

  • Lecture (Conference) (Online presentation)
    Mu2e-II Snowmass22 Workshop, 28.04.2021, FERMILAB (virtual), USA

Publ.-Id: 32576

Data for: Comparison of Elemental Analysis Techniques for the Characterization of Commercial Alloys

Seidel, P.

The uploaded XRF, OES, and LIBS data served as base for the publication by Seidel et al. 2021 in the journal Metals.

Keywords: Metals; Element analysis; XRF

Related publications


Publ.-Id: 32575

Demonstration of a compact plasma accelerator powered by laser-accelerated electron beams

Kurz, T.; Heinemann, T.; Gilljohann, M. F.; Chang, Y.-Y.; Couperus Cabadağ, J. P.; Debus, A.; Kononenko, O.; Pausch, R.; Schöbel, S.; Assmann, R. W.; Bussmann, M.; Ding, H.; Götzfried, J.; Köhler, A.; Raj, G.; Schindler, S.; Steiniger, K.; Zarini, O.; Corde, S.; Döpp, A.; Hidding, B.; Karsch, S.; Schramm, U.; Martinez De La Ossa, A.; Irman, A.

Plasma wakefield accelerators are capable of sustaining gigavolt-per-centimeter accelerating
fields, surpassing the electric breakdown threshold in state-of-the-art accelerator modules by
3-4 orders of magnitude. Beam-driven wakefields offer particularly attractive conditions for
the generation and acceleration of high-quality beams. However, this scheme relies on
kilometer-scale accelerators. Here, we report on the demonstration of a millimeter-scale
plasma accelerator powered by laser-accelerated electron beams. We showcase the acceleration
of electron beams to 128 MeV, consistent with simulations exhibiting accelerating
gradients exceeding 100 GVm⁻¹. This miniaturized accelerator is further explored by
employing a controlled pair of drive and witness electron bunches, where a fraction of the
driver energy is transferred to the accelerated witness through the plasma. Such a hybrid
approach allows fundamental studies of beam-driven plasma accelerator concepts at widely
accessible high-power laser facilities. It is anticipated to provide compact sources of energetic
high-brightness electron beams for quality-demanding applications such as free-electron

Keywords: Laser; Plasma; High energy electrons; X-Rays; Hybrid; High brightness

Related publications

Publ.-Id: 32574

Discovery and development of brain-penetrant 18F-labeled radioligands for neuroimaging of the sigma-2 receptors

Zhang, Y.; Wang, T.; Zhang, X.; Deuther-Conrad, W.; Fu, H.; Cui, M.; Zhang, J.; Brust, P.; Huang, Y.; Jia, H.

Six indole-based derivatives with a methoxy group at the indole ring were synthesized and evaluated as σ2 receptor ligands with nanomolar affinity (Ki (σ2) = 4.40-9.46 nM) and moderate subtype selectivity (Ki(σ2)/Ki(σ1) = 7-102). Radioligands 1-(4-(5,6-dimethoxyisoindolin-2-yl)butyl)-4-(2-[18F]fluoroethoxy)-1H-indole ([18F]3) and 1-(4-(5,6-dimethoxyisoindolin-2-yl)butyl)-5-(2-[18F]fluoroethoxy)-1H-indole ([18F]4) with high σ2 receptor affinity and subtype selectivity were synthesized through a direct SN2 displacement reaction, with radiochemical yields of 36-50% and 20-29%, radiochemical purity of >99%, and molar activities of 29-151 GBq/μmol and 55-72 GBq/μmol, respectively. Radioligand [18F]3 displayed high brain uptake, high brain-to-blood ratio and slow washout from the brain in male ICR mice. Administration of compound CM398 5 min prior to the radiotracer injection led to a significantly dose-dependent reduction of the brain accumulation (29-54%) and the brain-to-blood ratio (60-88%) at 30 min, indicating high specific binding of [18F]3 to the σ2 receptors in the brain. Ex vivo autoradiography in male ICR mice showed widely and heterogeneous distribution of [18F]3 in the brain. Small animal positron emission tomography imaging in rats confirmed different distribution and high specific binding of [18F]3 to σ2 receptors in rat brain. These findings warrant [18F]3 as a potential probe used for neuroimaging of the σ2 receptors in the brain.

Keywords: indole-based derivatives; σ2 receptor; fluorine-18; positron emission tomography; neuroimaging

Publ.-Id: 32573

Large eddy simulation of the fluid–structure interaction in an abstracted aquatic canopy consisting of flexible blades

Tschisgale, S.; Löhrer, B.; Meller, R.; Fröhlich, J.

The paper addresses the fluid–structure interaction of submerged aquatic canopies, with particular focus on the complex interplay between coherent flow structures and the motion of vegetation elements. New insights into the underlying mechanisms are gained from a large eddy simulation of a submerged model canopy flow. The model canopy is made up of 800 highly flexible blades, each individually resolved by an immersed boundary method. The obtained high-resolution flow data reveal well-known coherent turbulent structures, including velocity streaks, Kelvin–Helmholtz (KH) vortices in the mixing layer as well as hairpin (HP) vortices in the outer flow region. The present results show that the interaction of these prototypical structures plays a key role creating unique turbulent features such as composite KH/HP vortices located between a high-speed and low-speed streak. Under the influence of these pronounced eddies, groups of blades respond by a strong local reconfiguration. Due to the convection of the coherent structures by the mean flow this causes an apparent wave-like motion of the canopy in streamwise direction, known as monami. A frequency analysis of this phenomenon shows that the vegetation responds almost passively, merely reflecting local flow conditions.

Keywords: flow–structure interactions; turbulent boundary layers

Publ.-Id: 32572

An experimental investigation of light emission produced in the process of positronium formation in matter

Pietrow, M.; Zaleski, R.; Wagner, A.; Słomski, P.; Hirschmann, E.; Krause-Rehberg, R.; Liedke, M. O.; Butterling, M.; Weinberger, D.

The excess energy emitted during the positronium (Ps) formation in condensed matter may be released as light. Spectroscopic analysis of this light can be a new method of studying the electronic properties of materials. We report the first experimental attempt, according to our knowledge, to verify the existence of this emission process. As a result, the possibility of the emission of photons during Ps formation is within the experimental uncertainty in two different solids: an n-alkane and porous silica. However, it seems that the Ps formation on the alkane surface is not accompanied by the emission of photons with energy in the detection range of 1.6 – 3.8 eV. Various processes that can influence the energy of the photon emitted during the Ps formation are discussed to elucidate this issue. To aid future experiments, equations were developed to estimate the expected ratio of light emission events to annihilation events with the presence or absence of a photon during the Ps formation.

Keywords: positron annihilation lifetime spectroscopy; ELBE; MePS; EPOS; porosity; positronium

Related publications

  • Open Access Logo Physical Chemistry Chemical Physics 23(2021)19, 11264-11271
    Online First (2021) DOI: 10.1039/d1cp00755f


Publ.-Id: 32571

A combination of advanced ion beam techniques reveals detailed physico-chemical properties of collected Saharan dust particles

Podlipec, R.; Munnik, F.; Klingner, N.; Hlawacek, G.; Rigler, M.; Heller, R.

The diverse physical and chemical properties of aerosols can cause a diverse impact on air quality, cloud nucleation, planetary radiation balance, public health, etc. Besides carbon particles from incomplete combustion, mineral particles from Saharan dust also present a significant contribution to the changes. It is estimated that 400 to 700 million tons of dust is transported from Sahara every year and with the particular wind directions it is carried to the Mediterranean or even to the north of Europe (Prospero, 1996). It has recently been shown that these particles induce serious problems for asthmatics (Gutierrez et al., 2020).
To understand the origin of pollution, necessary input information presents knowing the source apportionment of aerosols. Techniques such as non-destructive particle induced X-ray emission (PIXE) (Lucarelli et al., 2018) and energy dispersive x-ray spectroscopy (SEM-EDS) (Longoria-Rodríguez et al., 2021) have been successfully applied for chemical microanalysis of individual particles. However, knowing both the physical and chemical properties of particles towards nm scales, which would cover all aerosol sizes, is still a challenging task.
In our study, we have thus implemented the correlative approach using advanced ion beam techniques to study both physical and chemical properties of mineral particles from Saharan dust collected on quartz fiber filters on Cyprus Atmospheric Observatory (35.04oN,33.06 Eo; 535 m a.s.l.) using a combination of the virtual impactor and Aethalometer AE33 (Aerosol d.o.o.). We have implemented Helium Ion Microscopy (HIM), capable of sub-nm resolution imaging with high depth-of-field contrast, followed by micro-PIXE elemental analysis done on the same filter region. Information from backscattered high-energy ions was found particularly suitable for the registration and overlap of complementary images (Figure 1).
The study has revealed the size, shape, architecture, and surface topography of individual mineral particles on nm scale, while micro-PIXE their chemical composition. Additionally, HIM resolution and surface sensitivity enabled the detection and identification of individual black carbon (BC) soot attached to the surface of mineral particles. This information can have a significant impact on our understanding of the optical properties of mineral dust and its relevance to climate changes and health effects. This finding urges for further investigations where additional focused ion beam techniques and instrumentation have been implemented and will be discussed.

Keywords: HIM; micro-PIXE; Saharan dust; BC soot; correlative microscopy

Related publications

  • Lecture (Conference)
    European Aerosol Conference (EAC 2021), 30.08.-03.09.2021, Virtual, Virtual

Publ.-Id: 32570

Examining out-of-plane expansion of aggregate minerals in ion-irradiated concrete.

Roode-Gutzmer, Q. I.; Schymura, S.; Barkleit, A.; Stumpf, T.

1 Introduction

Concrete consists primarily of the mineral quartz as coarse and fine aggregates to a weight of 50-60 %. After quartz, feldspar is generally contained in a weight quantity of 15-20 %. Quartz in its pristine state is the least soluble of the silicates, thereby providing concrete the highest possible chemical durability. Biological shielding concrete that surrounds nuclear reactor pressure vessels are exposed to neutron radiation over decades during the course of nuclear power plant (NPP) operation. Minerals that are subjected to radiation, whether it be neutrons, electrons, or ions, of sufficient fluence and energy, accumulate defects in their crystal lattices. Once the threshold concentration of defects has been reached, structural relaxation occurs, which is a volume expansive amorphization process. Of all the minerals examined for neutron radiation-induced volume expansion, quartz exhibits the highest, followed by feldspar with volume expansion maxima respectively being 17.8 and 7.7 % [1]. Irradiated quartz accumulates E’-center defects [2], which are essentially unpaired sp³ dangling bonds and chemically reactive in aqueous solution, particularly at the higher pH values typically prevailing in pore water in concrete. It is the objective of this research to investigate the increased dissolution rates of irradiated silicate minerals, particularly in the context of the alkali-silica reaction (ASR), which is the most significant degradation reaction known to occur in concrete.

2 Experimental

Polished sections of concrete partially masked with aluminium foil were subjected to Si-ion irradiation with a fluence of 5·1014 ions/cm2 at 300 keV under vacuum without cooling. Changes in the vertical profiles of the irradiated samples were examined by Vertical Scanning Interferometry (VSI) and Confocal Microscopy.

3 Results

The minerals making up the aggregate were identified by µ Raman spectroscopy to be α-quartz and potassium feldspar (microcline: KAlSi₃O₈), the latter always intergrown with quartz. Quartz (grain A) exhibited an out-of-plane expansion of ~ 80 nm. No observable difference in average height between radiated and non-radiated areas on the aggregate containing feldspar (grain B) could be ascertained. This is mainly attributable to the surface roughness of feldspar (> 1 µm), which is essentially out of range for interferometric techniques. Furthermore, the penetration depths estimated in the Kinchin-Pease calculation by SRIM [3] for Si-ion irradiation at 300 keV are 429 and 604 nm, respectively for α-quartz and microcline. As the damage to the structure occurs initially at the point where the ion stops, structural relaxation in the feldspar begins much further away from the surface than it does for quartz. In our case, it is likely that the expansion in the feldspar has not detectably reached the surface.


[1] Le Pape, Y., Alsaid, F., Alain, B. and Giorla, B.: J. Adv. Conc. Technol. (2018) 16, 191-209.
[2] Douillard, L. and Duraud, J. P.: Nucl. Instrum. Methods Phys. Res. (1996) B16, 191-209.
[3] Ziegler, J. F., Ziegler, M. D. and Biersack, J. P.: Nucl. Instrum. Methods Phys. Res. (2010) B268, 1818-1823. (

Related publications

  • Lecture (Conference) (Online presentation)
    9. Radiochemischer Analytik Workshop, 08.-09.06.2021, Rossendorf, Germany

Publ.-Id: 32569

An updated status and trends in actinide metal-organic frameworks (An-MOFs): from synthesis to application

Lyu, K.; Fichter, S.; Gu, M.; März, J.; Schmidt, M.

Actinide metal-organic frameworks (An-MOFs) consisting of actinide nodes and organic linkers represent an underexplored category of coordination polymers due to challenges in their synthetic and characterization. The unparalleled coordination chemistry of actinide elements confers a huge opportunity to explore the rational design, chemical reactivity, and versatile properties of An-MOFs as one of the most intriguing class of metal-organic frameworks (MOFs). Significant advances in this “juvenile” MOF research field have been witnessed in recent years and progress in the An-MOFs area since 2003 has been reviewed from the aspects of the synthesis, structure, and applications. The preparative handling and synthetic strategies implemented in constructing An-MOFs are illustrated. Their structure motifs are then classified and expounded by actinide building blocks and organic linkers. The modularity, topology, and porosity of An-MOFs are specified to highlight a great potential to tune their electronic structures and ensuing properties. Ultimately, applications of An-MOFs as
selective adsorbents, heterogenous catalysts, luminescent sensors, conducting, and semiconducting materials, and nuclear targets are underlined. This updated review is envisaged to guide in-depth investigation of largely elusive transuranium MOFs and the development of thorium or uranium-based MOFs towards practical applications.

Keywords: Actinide coordination chemistry; Metal-Organic Frameworks; Actinide MOF; Transuranium elements; Uranium and Thorium; Properties and Applications


Publ.-Id: 32568

Modulation of γ-secretase activity by a carborane-based flurbiprofen analogue

Saretz, S.; Basset, G.; Useini, L.; Laube, M.; Pietzsch, J.; Draca, D.; Maksimović-Ivanić, D.; Trambauer, J.; Steiner, H.; Hey-Hawkins, E.

All over the world, societies are facing rapidly aging populations combined with a growing num-ber of patients suffering from Alzheimer’s disease (AD). One focus in pharmaceutical research to address this issue is on the reduction of the longer amyloid-β (Aβ) fragments in brain by modula-tion of γ-secretase, a membrane-bound protease. R-Flurbiprofen (tarenflurbil) was studied in this regard, but failed to show significant improvement in AD patients in a phase 3 clinical trial. This was mainly attributed to its low ability to cross the blood-brain barrier (BBB). We here present the synthesis and in vitro evaluation of a racemic meta-carborane analogue of flurbiprofen. By intro-ducing the carborane moiety, the hydrophobicity could be shifted into a more favourable range for the penetration of the blood-brain barrier, evident by a logD7.4 value of 2.0. Furthermore, our analogue retained γ-secretase modulator activity in comparison to racemic flurbiprofen in a cell-based assay. These findings demonstrate the potential of carboranes as phenyl mimetics also in AD research.

Keywords: Alzheimer; Carborane; Flurbiprofen; γ-Secretase modulator (GSM); Small molecule; Amyloid-β (Aβ) peptide; Phenyl mimetic

Publ.-Id: 32567

A Fluorometric Investigation of a Peptide-assisted Interaction between Composite Magnetic Beads and Phosphors for the Recycling of Rare Earth Elements

Hinman, N. R.

The recovery of rare earth elements through recycling of end-of-life electronics has become a goal of increasing importance as this helps create a more sustainable economy. Nevertheless, the recycling rates are still low. Rare earth elements could potentially be recovered from phosphors in end-of-life compact fluorescent lamps. In this thesis, LAP-specific peptides were immobilized on composite magnetic beads and these were brought in contact with LAP to see how much LAP interacts with the magnetic beads. LAP is an inorganic phosphor particle that emits green light when exposed to ultraviolet radiation. To be able to interpret the binding experiments, the fluorescent spectra of five different phosphors were measured and a simple quantification method was developed. In addition to this, the ratio of elements present in five different phosphors was investigated. This thesis has provided several insights into the fluorometric properties of suspended phosphors, single or in mixture, and into the effect of media on binding experiments. These insights can help in future work e.g. to be able to adapt the binding experiments for a mixture of phosphors. Furthermore, the proof-of-concept for binding experiments developed in this thesis could easily be applied for the investigation of other peptides phosphors as well.

Keywords: Phosphor; Compact Fluorescent Lamps; Lamp Powder; Fluorescence; Rare Earth Element

  • Bachelor thesis
    Hochschule Bonn-Rhein-Sieg, 2021
    Mentor: Dr. Ulf Ritgen
    68 Seiten

Publ.-Id: 32566

Spin-wave frequency combs

Hula, T.; Schultheiß, K.; Trindade Goncalves, F. J.; Körber, L.; Bejarano, M.; Copus, M.; Flacke, L.; Liensberger, L.; Buzdakov, A.; Kakay, A.; Weiler, M.; Camley, R.; Faßbender, J.; Schultheiß, H.

We experimentally demonstrate the generation of spin-wave frequency combs based on the non-
linear interaction of propagating spin waves in a microstructured waveguide. By means of time- and space-resolved Brillouin light scattering spectroscopy, we show that the simultaneous excita- tion of spin waves with different frequencies leads to a cascade of four-magnon scattering events which ultimately results in well-defined frequency combs. Their spectral weight can be tuned by the choice of amplitude and frequency of the input signals. Furthermore, we introduce a model for stimulated four-magnon scattering which describes the formation of spin-wave frequency combs in the frequency and time domain.

Keywords: magnetism; magnetization dynamics; spin waves; magnons; spin dynamics; micromagnetic modeling; Brillouin light scattering; spectroscopy


Publ.-Id: 32565

A novel and open-source illumination correction for hyperspectral digital outcrop models

T. Thiele, S.; Lorenz, S.; Kirsch, M.; Gloaguen, R.

The widespread application of drones and associated miniaturization of imaging sensors has led to an explosion of remote sensing applications with very high spatial and spectral resolutions. Three dimensional (3-D) ultra-high resolution digital outcrop models created using drones and oblique imagery from ground-based sensors are now commonly used in the academic and industrial sectors. While the generation of spatially accurate models has been greatly facilitated by the development of com- puter vision tools such as Structure from Motion, correction of spectral attributes to achieve material reflectance measurements remains challenging. Following the development of a topograph- ical correction toolbox (mephysto), we now propose a series of new tools that can leverage the detailed geometry captured by digital outcrop models to correct for illumination effects caused by oblique viewing angles and the interaction of light with complex 3-D surfaces. This open source code is integrated into hylite, a python toolbox for the full 3-D processing and fusion of digital outcrop models with hyperspectral imaging data. We validate the performance of our novel method using a case study at an open pit mine in Tharsis, Spain, and demonstrate the importance of accurate illumination corrections for quantitative spectral analyses. Significantly, we show that commonly applied spectral analysis techniques can yield erroneous results for data corrected using current state of the art approaches. Our proposed method ameliorates many of the issues with these established approaches.

Keywords: Digital outcrop models; Geology; Illumination correction; Hyperspectral imaging

Publ.-Id: 32564

Reactivation of magma pathways: Insights from field observations, geochronology, geomechanical tests and numerical models

Thiele, S. T.; Cruden, A. R.; Zhang, X.; Micklethwaite, S.; Matchan, E. L.

Field observations and unmanned aerial vehicle surveys from Caldera Taburiente (La Palma, Canary Islands, Spain) show that pre-existing dykes can capture and re-direct younger ones to form multiple dyke composites. Chill margins suggest that the older dykes were solidified and cooled when this occurred. In one multiple dyke example, an 40Ar/39Ar age difference of 200 kyr was determined between co-located dykes. Petrography and geomechanical measurements (ultrasonic pulse and Brazilian disc tests) show that a microscopic preferred alignment of plagioclase laths and sheet-like structures formed by non-randomly distributed vesicles give the solidified dykes anisotropic elastic moduli and fracture toughness. We hypothesise that this anisotropy led to the development of margin-parallel joints within the dykes, during subsequent volcanic loading. Finite element models also suggest that the elastic contrast between solidified dykes and their host rock elevated and re-oriented the stresses that governed subsequent dyke propagation. Thus, the margin-parallel joints, combined with local concentration and rotation of stresses, favoured the deflection of subsequent magma-filled fractures by up to 60° to form the multiple dykes. At the edifice scale, the capture and deflection of active intrusions by older ones could change the organisation of volcanic magma plumbing systems and cause unexpected propagation paths relative to the regional stress. We suggest that reactivation of older dykes by this mechanism gives the volcanic edifice a structural memory of past stress states, potentially encouraging the re-use of older vents and deflecting intrusions along volcanic rift zones or towards shallow magma reservoirs.

Keywords: multiple dyke; elastic anisotropy; fracture deflection; mechanical discontinuity; reactivation; Quaternary; basalt Ar-Ar dating; Canary Islands

Publ.-Id: 32563

Data: Finite-element dynamic-matrix approach for spin-wave dispersions in magnonic waveguides with arbitrary cross section

Körber, L.; Quasebarth, G.; Otto, A.; Kakay, A.

This repository contains data generated to showcase our developed micromagnetic method described in our paper "Finite-element dynamic-matrix approach for spin-wave dispersions in magnonic waveguides with arbitrary cross section". For each example in Section V, we provide

  • .clc and .spc files containing important material and experimental parameters
  • .geo files containing the sample geometry (gmsh files)
  • .csv files containing the dispersions calculated using our eigensolver 

  • only for example A: linescans of the mode profiles along the width of the waveguide
  • only for example B: .dat file of the obtained mumax dispersion

Related publications


Publ.-Id: 32562

Finite-element dynamic-matrix approach for spin-wave dispersions in magnonic waveguides with arbitrary cross section

Körber, L.; Quasebarth, G.; Otto, A.; Kakay, A.

We present a numerical approach to efficiently calculate spin-wave dispersions and spatial mode profiles in magnetic waveguides of arbitrarily shaped cross section with any non-collinear equilibrium magnetization which is translationally invariant along the waveguide. Our method is based on the propagating-wave dynamic-matrix approach by Henry et al. and extends it to arbitrary cross sections using a finite-element method. We solve the linearized equation of motion of the magnetization only in a single waveguide cross section which drastically reduces computational effort compared to common three-dimensional micromagnetic simulations. In order to numerically obtain the dipolar potential of individual spin-wave modes, we present a plane-wave version of the hybrid finite-element/boundary-element method by Frekdin and Koehler which, for the first time, we extend to a modified version of the Poisson equation. Our method is applied to several important examples of magnonic waveguides including systems with surface curvature, such as magnetic nanotubes, where the curvature leads to an asymmetric spin-wave dispersion. In all cases, the validity of our approach is confirmed by other methods. Our method is of particular interest for the study of curvature-induced or magnetochiral effects on spin-wave transport but also serves as an efficient tool to investigate standard magnonic problems.

Keywords: spin wave; eigensolver; micromagnetic simulation; dispersion; finite-element method; FEM

Publ.-Id: 32561

Magneto-ionics in single-layer transition metal nitrides

de Rojas, J.; Salguero, J.; Ibrahim, F.; Chshiev, M.; Quintana, A.; Lopeandia, A.; Liedke, M. O.; Butterling, M.; Hirschmann, E.; Wagner, A.; Abad, L.; Costa-Krämer, J. L.; Menéndez, E.; Sort, J.

Magneto-ionics allows for tunable control of magnetism by voltage-driven transport of ions, traditionally oxygen or lithium, and, more recently, hydrogen, fluorine or nitrogen. Here, magneto-ionic effects in single-layer iron nitride films are demonstrated, and their performance is evaluated at room temperature and compared with previously studied cobalt nitrides. Iron nitrides require an increased activation energy and, under high bias, exhibit more modest rates of magneto-ionic motion than cobalt nitrides. Ab initio calculations reveal that, based on the atomic bonding strength, the critical field required to induce nitrogen-ion motion is higher in iron nitrides (≈ 6.6 V nm-1) than in cobalt nitrides (≈ 5.3 V nm-1). Nonetheless, under large bias (i.e., well above the magneto-ionic onset and, thus, when magneto-ionics is fully activated), iron nitride films exhibit enhanced coercivity and larger generated saturation magnetization, surpassing many of the features of cobalt nitrides. The microstructural effects responsible for these enhanced magneto-ionic effects are discussed. These results open up the potential integration of magneto-ionics in existing nitride semiconductor materials in view of new memory system architectures.

Keywords: FeN; magneto-ionics; positron annihilation spectroscopy


Publ.-Id: 32560

Origin of the 30 T transition in CeRhIn5 in tilted magnetic fields

Mishra, S.; Gorbunov, D.; Campbell, D. J.; Leboeuf, D.; Hornung, J.; Klotz, J.; Zherlitsyn, S.; Harima, H.; Wosnitza, J.; Aoki, D.; McCollam, A.; Sheikin, I.

We present a comprehensive ultrasound study of the prototypical heavy-fermion material CeRhIn5, examining the origin of the enigmatic 30 T transition. For a field applied at 2° from the c axis, we observed two sharp anomalies in the sound velocity, at Bm ≈ 20 T and B ≈ 30 T, in all the symmetry-breaking ultrasound modes at low temperatures. The lower-field anomaly corresponds to the well-known first-order metamagnetic incommensurate-to-commensurate transition. The higher-field anomaly takes place at 30 T, where an electronic-nematic transition was previously suggested to occur. Both anomalies, observed only within the antiferromagnetic state, are of similar shape, but the corresponding changes of the ultrasound velocity have opposite signs. Based on our experimental results, we suggest that a field-induced magnetic transition from a commensurate to another incommensurate antiferromagnetic state occurs at B. With further increasing the field angle from the c axis, the anomaly at B slowly shifts to higher fields, broadens, and becomes smaller in magnitude. Traced up to 30° from the c axis, it is no longer observed at 40° below 36 T.


Publ.-Id: 32559

Accelerator Programming Using Directives 7th International Workshop, WACCPD 2020, Virtual Event, November 20, 2020, Proceedings

Bhalachandra, S.; Wienke, S.; Chandrasekaran, S.; Juckeland, G.

This book constitutes the proceedings of the 7th International Workshop on Accelerator Programming Using Directives, WACCPD 2020, which took place on November 20, 2021. The workshop was initially planned to take place in Atlanta, GA, USA, and changed to an online format due to the COVID-19 pandemic.
WACCPD is one of the major forums for bringing together users, developers, and the software and tools community to share knowledge and experiences when programming emerging complex parallel computing systems. The 5 papers presented in this volume were carefully reviewed and selected from 7 submissions. They were organized in topical sections named: OpenMP; OpenACC; and Domain-specific Solvers.

Keywords: Compilers; computer networks; CUDA; distributed computer systems; embedded systems; Graphics Processing Unit (GPU); Hardware accelerators; Heterogeneous (hybrid) systems; Massively parallel algorithms; Massively parallel and high-performance simulations

Publ.-Id: 32558

Development of [18F]LU14 for PET Imaging of Cannabinoid Receptor Type 2 in the Brain

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

Cannabinoid receptors represent an attractive therapeutic target for neurodegenerative diseases and cancer. Aiming at a positron emission tomography (PET) radiotracer to monitor neuronal changes of receptor density and/or occupancy during the CB2R-tailored therapy, we developed here cis-[18F]1-(4-fluorobutyl-N-((1s,4s)-4-methylcyclohexyl)-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamide ([18F]LU14) starting from the corresponding mesylate precursor. First biological evalua-tion revealed that [18F]LU14 is a highly affine CB2R radioligand with optimal metabolic stability (>80% intact tracer in brain at 30 min p.i.). Its further evaluation in a well-established rat model of CB2R overexpression by PET demonstrated its ability to selectively image the CB2R in the brain and its potential as tracer to further investigate diseased related CB2R alterations.

Keywords: Cannabinoid receptor type 2; naphtyrid-2-one; binding affinity; radiochemistry; fluorine-18 labeling; brain; positron emission tomography (PET)

Publ.-Id: 32557

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

Matschiavelli, N.

Durch den Ausstieg Deutschlands aus der Kernkraft tritt immer mehr die dauerhafte und sichere Lagerung der noch hoch-radioaktiven Brennelemente in den Fokus. Aber wie beeinflussen Mikroorganismen die Metalle und Gesteine, aus denen ein Endlager aufgebaut ist? Als Mikrobiologen/innen in der Abteilung für Biogeochemie zeigen wir dir, wie mit modernen biologischen Methoden diese Fragen beantwortet werden.

  • Lecture (others) (Online presentation)
    Gils`& Boys`day am HZDR, 22.04.2021, Dresden, Deutschland

Publ.-Id: 32556

Evaluation of a sensitive, reasonable, and fast detection method for ⁵⁵Fe in steel

Merchel, S.; Rugel, G.; Lachner, J.; Wallner, A.; Walther, D.; Ziegenrücker, R.

A pilot study to quantify ⁵⁵Fe in steel from a reactor vessel of a nuclear power plant by accelerator mass spectrometry (AMS) without any chemical sample preparation was validated by liquid scintillation counting (LSC) and AMS after radiochemical separation. AMS reaches an uncertainty <10% at the 1 kBq gFe -1 level within less than 10 min measuring time. The background was <3 Bq gFe -1, presently limited by the short measurement time. The new instrumental AMS method for analysing ⁵⁵Fe from neutron capture production is reasonable and fast compared to other analytical methods.

Keywords: Accelerator mass spectrometry; nuclear decommissioning; nuclear waste; ⁵⁵Fe; radiochemical separation

Related publications

Publ.-Id: 32555

Proton beam quality enhancement by spectral phase control of a PW-class laser system

Ziegler, T.; Albach, D.; Bernert, C.; Bock, S.; Brack, F.-E.; Cowan, T. E.; Dover, N. P.; Garten, M.; Gaus, L.; Gebhardt, R.; Goethel, I.; Helbig, U.; Irman, A.; Kiriyama, H.; Kluge, T.; Kon, A.; Kraft, S.; Kroll, F.; Loeser, M.; Metzkes-Ng, J.; Obst-Huebl, L.; Püschel, T.; Rehwald, M.; Schlenvoigt, H.-P.; Schramm, U.; Zeil, K.

This repository contains the experimental raw data, the analyzed data and corresponding scripts as well as figures for the "Proton beam quality enhancement by spectral phase control of a PW-class laser system" publication.

Related publications


Publ.-Id: 32554

ExPaNDS Training Catalogue Demo

Knodel, O.

This entry contains a demo video introducing the ExPaNDS/PaNOSC training catalogue used as  PaN Training Portal developed by HZDR. The video is also part of the ExPaNDS WP5 Deliverable 5.4.

One of the goals of ExPaNDS (European Open Science Cloud (EOSC) Photon and Neutron Data Service) is to train research scientists to better use available computational RI infrastructures to address critical research questions. This requires access both to face-to-face training opportunities and to disparate training materials and resources, currently dispersed across Europe.

The ambitious ExPaNDS project itself is a collaboration between 10 national Photon and Neutron Research Infrastructures (PaN RIs) as well as EGI. The project aims to deliver standardised, interoperable, and integrated data sources and data analysis services for Photon and Neutron facilities. ExPaNDS collaborates with PaNOSC (Photon and Neutron Open Science Cloud). 

ExPaNDS WP5: Training activities through EOSC platforms will organise workshops and deliver training materials through the e-learning platforms made available on the EOSC.

Keywords: data management; training; ExPaNDS

Related publications


Publ.-Id: 32553

Thermocapillary Effects at Gas Bubbles Growing on Electrodes

Mutschke, G.; Hossain, S. S.; Bashkatov, A.; Yang, X.; Eckert, K.

The contribution summarizes recent progress obtained in our group when studying the dynamics of
hydrogen gas bubbles growing during electrolysis in an aqueous electrolyte. We find that thermocapillary
effects are important to be considered, which lead to characteristic vortical electrolyte flow close to the
bubble [1,2]. We further discuss the resulting force on the bubble and conclude on how the bubble
departure is affected at electrodes of different sizes [3]. This knowledge might contribute to advancing
the efficiency of electrolyzers.


[1] X. Yang et al., Marangoni convection at electrogenerated hydrogen bubbles, Phys. Chem. Chem.
Phys. 20 (2018) 11542.
[2] J. Massing et al., Thermocapillary convection during hydrogen evolution at microelectrodes,
Electrochim. Acta 297 (2019) 929-940.
[3] S.S. Hossain et al., On the thermocapillary effect on gas bubbles growing on electrodes of different
sizes, Electrochim. Acta 353 (2020) 136461.

Keywords: electrolysis; water splitting; gas evolution; thermocapillary effect

  • Lecture (Conference) (Online presentation)
    29th Topical Meeting of the International Society of Electrochemistry, 19.-21.04.2021, Mikulov, Tschechische Republik
  • Poster
    International Congress of Theoretical and Applied Mechanics (ICTAM 2020+1), 26.08.2021, Milano, Italien, 22.-27.08.2021, Milano, Italien
  • Lecture (Conference) (Online presentation)
    72nd Annual Meeting of the International Society of Electrochemistry, 29.08.-03.09.2021, Jeju, Südkorea

Publ.-Id: 32552

Macro to generate muon (g-2) summary plot

Müller, S.

This macro gives the status of the muon (g-2) just after the FERMILAB seminar on April 7, 2021.

The theoretical values use the different contributions as given in the

[White Paper]( of the

[Theory Initiative]( Since the leading

order hadronic contribution is dominating the uncertainty of the

theoretical values, several values for a$_\mu$ are plotted which use the

different evaluations for the leading order hadronic contribution given in

Table 4 of the White Paper as well as the White Paper average.

Keywords: ROOT; (g-2); Macro


Publ.-Id: 32551

A Two‐Dimensional Polyimide‐Graphene Heterostructure with Ultra‐fast Interlayer Charge Transfer

Liu, K.; Li, J.; Qi, H.; Hambsch, M.; Rawle, J.; Romaní Vázquez, A.; Shaygan Nia, A.; Pashkin, O.; Schneider, H.; Polozij, M.; Heine, T.; Helm, M.; Mannsfeld, S. C. B.; Kaiser, U.; Dong, R.; Feng, X.

Two‐dimensional polymers (2DPs) are a class of atomically/molecularly thin crystalline organic 2D materials. They are intriguing candidates for the development of unprecedented organic‐inorganic 2D van der Waals heterostructures (vdWHs) with exotic physicochemical properties. In this work, we demonstrate the on‐water surface synthesis of large‐area (cm 2 ), monolayer 2D polyimide (2DPI) with 3.1‐nm lattice. Such 2DPI comprises metal‐free porphyrin and perylene units linked by imide bonds. We further achieve a scalable synthesis of 2DPI‐graphene (2DPI‐G) vdWHs via a face‐to‐face co‐assembly of graphene and 2DPI on the water surface. Remarkably, femtosecond transient absorption spectroscopy reveals an ultra‐fast interlayer charge transfer (~60 fs) in the resultant 2DPI‐G vdWH upon protonation by acid, which is equivalent to that of the fastest reports among inorganic 2D vdWHs. Such large interlayer electronic coupling is ascribed to the interlayer cation‐π interaction between 2DP and graphene. Our work opens opportunities to develop 2DP‐based vdWHs via the on‐water surface synthesis strategy and highlights the unique interface‐induced optoelectronic properties.

Keywords: 2D polymer; graphene; van der Waals heterostructure; transient absorption spectroscopy

Publ.-Id: 32550

A tunable autocorrelator for pulse measurements at IR FEL-oscillator facilities

Cicek, E.; Seidel, W.; Ketenoglu, B.

Radiation characteristics of a Free-Electron Laser (FEL) such as pulse length, timestructure, intensity, bandwidth, wavelength, power, frequency, etc., which were measured on adiagnostics table, are thoroughly discussed. In this respect, pulse length measurements of an InfraredFEL (IR-FEL) beam are evaluated through an intensity autocorrelator, designed and installed as adiagnostics tool at the “Helmholtz-Zentrum Dresden-Rossendorf (HZDR)-Radiation Source ELBE”of Germany. In addition, the autocorrelator was designed as a unique, cost-effective, and in-housesetup. It operates within the wavelength range of 3–35 microns, using Cadmium-Telluride (CdTe)crystals in the Second Harmonic Generation (SHG) medium. The intensity autocorrelation curveswere obtained for the FEL beam with the wavelength of 26.2 microns, indicating an FWHM pulseduration ranging between 3.29–8.03 ps with different optical cavity detuning values. Furthermore,the pulse duration of Ti: sapphire laser beam is measured between 1–3 ps through the designedautocorrelator at the ELBE light source. On the other hand, the setup may pave the way for pulselength measurements of the Turkish infrared FEL-oscillator facility (TARLA) as well, which iscurrently under the hardware installation phase. Finally, it is elaborated in section 3 that the uniqueautocorrelator design fully meets all requirements for pulse length measurements of an infraredFEL source.Radiation characteristics of a Free-Electron Laser (FEL) such as pulse length, timestructure, intensity, bandwidth, wavelength, power, frequency, etc., which were measured on adiagnostics table, are thoroughly discussed. In this respect, pulse length measurements of an InfraredFEL (IR-FEL) beam are evaluated through an intensity autocorrelator, designed and installed as adiagnostics tool at the “Helmholtz-Zentrum Dresden-Rossendorf (HZDR)-Radiation Source ELBE”of Germany. In addition, the autocorrelator was designed as a unique, cost-effective, and in-housesetup. It operates within the wavelength range of 3–35 microns, using Cadmium-Telluride (CdTe)crystals in the Second Harmonic Generation (SHG) medium. The intensity autocorrelation curveswere obtained for the FEL beam with the wavelength of 26.2 microns, indicating an FWHM pulseduration ranging between 3.29–8.03 ps with different optical cavity detuning values. Furthermore,the pulse duration of Ti: sapphire laser beam is measured between 1–3 ps through the designedautocorrelator at the ELBE light source. On the other hand, the setup may pave the way for pulselength measurements of the Turkish infrared FEL-oscillator facility (TARLA) as well, which iscurrently under the hardware installation phase. Finally, it is elaborated in section 3 that the uniqueautocorrelator design fully meets all requirements for pulse length measurements of an infraredFEL source.

Keywords: Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch lengt

Related publications

Publ.-Id: 32549

Ion Microprobe analysis of wear processes in tribological ta-C coatings.

Munnik, F.; Habenicht, C.; Lorenz, L.; Krause, M.

Solid lubricants are an active research topic due to many factors, an important one being the elimination of current liquid lubrication because of its environmental impact. The tribological behaviour of different solid lubricants depends on the gas en¬vironment while testing. The most often-used solid lubricant coating is MoS2. A newer one still under research is ta-C (hydrogen-free, tetra-edic, amorphous carbon) that behaves like a polar opposite to MoS2. ta-C relies on free hydrogen and hydroxide ions to passivate free bonds resulting from the wear testing.
In a first test, a ta-C coating has been subjected to tribological tests with counter bodies made of various materials. The aim is to study tribological surface changes like material loss of the coating or material transfer from the counter body, processes which aren’t fully understood yet. Both the wear tracks on the ta-C coating and the counter bodies have been subjected to Ion Beam Analysis using a high energy ion microprobe. Both PIXE (Particle Induced X-ray Emission) and RBS (Rutherford Backscattering Spectrometry) measurements have been performed using a 2 MeV He ion beam and a 3 MeV H ion beam. Results for the wear tracks obtained with a brass and a Al2O3 counter body are presented as well as results on the counter bodies themselves. The advantages and drawbacks of the results obtained with different ions and different methods are presented. These results show that it is important to combine the measurements in order to obtain a complete picture of the damage caused by the wear tests.

Keywords: Tribilogy; Ion beam analysis

Related publications

  • Lecture (Conference) (Online presentation)
    Ion beam workshop 2021 - virtual meeting, 24.-25.03.2021, online, Deutschland

Publ.-Id: 32548

Terahertz-wave decoding of femtosecond extreme-ultraviolet light pulses

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

In recent years, femtosecond extreme-ultraviolet (XUV) and X-ray pulses from free-electron lasers have developed into important probes to monitor processes and dynamics in matter on femtosecond-time and Angstroem-length-scales. With the rapid progress of versatile ultra-fast X-ray spectroscopy techniques and more sophisticated data-analysis tools, accurate single-pulse information on the arrival time, duration and shape of the probing X-ray and XUV pulses becomes essential. Here, we demonstrate for the first time that XUV pulses can be converted into terahertz electromagnetic pulses. We observe that the duration, arrival time and energy of each individual XUV pulse is encoded in the waveform of the associated terahertz pulses and can, thus, be readily deduced from single-shot terahertz time-domain detection.

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

Publ.-Id: 32547

Modelling on the very large-scale connectome

Ódor, G.; Gastner, M.; Kelling, J.; Deco, G.

In this review we discuss critical dynamics of simple nonequilibrium models on large connectomes, obtained by diffusion MRI, representing the white matter of the human brain. In the first chapter we overview graph theoretical and topological analysis of these networks, pointing out certain universality, which allows to select a representative one, the KKI-18, which has been used for dynamical simulation subsequently. The critical and sub-critical behavior of simple, two or three state threshold models is discussed with special emphasis of rare-region effects leading to robust Griffiths Phases (GP). Numerical results of synchronization phenomena, studied by the Kuramoto model, are also shown, leading to a continuous analog of GP, termed frustrated synchronization in Chimera states. The models presented here exhibit avalanche scaling behavior with exponents in agreement with brain experimental data if local homeostasis is provided.

Publ.-Id: 32546

The Helmholtz cloud services as well suited platform for sustainable OpenFOAM_RCS development

Schlegel, F.; Greenshields, C.; Huste, T.; Lehnigk, R.; Lucas, D.; Peltola, J.

The presentation gives a comprehensive overview about sustainable software development strategies for OpenFOAM_RCS and how this will be supported by the Helmholtz cloud services in the frame of HIFIS.

Keywords: OpenFOAM; HIFIS; Computational Fluid Dynamics; software development

  • Lecture (Conference) (Online presentation)
    32nd Meeting of German CFD Network of Competence, 16.-17.03.2021, München, Deutschland

Publ.-Id: 32544

Experimental electronic stopping cross section of tungsten for light ions in a large energy interval

Moro, M. V.; Wolf, P. M.; Bruckner, B.; Munnik, F.; Heller, R.; Bauer, P.; Primetzhofer, D.

Electronic stopping cross section of tungsten for light ions was experimentally measured in a wide energy interval (20 to 6000 keV for protons and 50 to 9000 keV for helium) in backscattering and transmission geometries. The measurements were carried out in three laboratories (Austria, Germany and Sweden) using five different set-ups, the stopping data deduced from different data sets showed excellent agreement amongst each other, with total uncertainty varying within 1.5–3.8% for protons and 2.2–5.5% for helium, averaged over the respective energy range of each data set. The final data is compared to available data and to widely adopted semi-empirical and theoretical approaches, and found to be in good agreement with most adopted models at energies around and above the stopping maximum. Most importantly, our results extend the energy regime towards lower energies, and are thus of high technological relevance, e.g., in fusion research. At these low energies, our findings also revealed that tungsten – featured with fully and partially occupied f- and d-subshells, respectively – can be modeled as an electron gas for the energy loss process.

Keywords: Stopping power; Tungsten; Free electron gas; Bragg peak; Protons; Helium; Fusion

Related publications

Publ.-Id: 32543

Data/Software for: Dynamics of mono- and poly-disperse two-dimensional foams flowing in an obstructed channel

Lecrivain, G.

This archive contains selected raw data and the original code described in the manuscript "Dynamics of mono- and poly-disperse two-dimensional foams flowing in an obstructed channel", submitted in 2020 to Journal of Fluid Mechanics by Thales Carl Lavoratti, Sascha Heitkam, Uwe Hampel, and Gregory Lecrivain. The archive contains the following data:

- C++ code used to simulate the foam dynamics and create the raw data (petsc.tar.gz)

- selected raw data in petsc format. The mono-disperse scenarios V125.tar.gz, V200.tar.gz, V250.tar.gz, V350.tar.gz correspond to the gas fractions \varepsilon = 0.44, 0.68, 0.83, and 0.99, respectively. The poly-disperse scenarios V125r.tar.gz, V200r.tar.gz, V250r.tar.gz, V350r.tar.gz correspond to the gas fractions 0.44, 0.69, 0.84, and 0.99, respectively

- bash and python scripts used to create bubble contours from the petsc raw data (scripts.tar.gz)

- extracted bubble contours (contours.tar.gz)

- python codes used to make figures and animations (figures.tar.gz)

- Mathematica notebook testing the wall potential f(\phi_w) = 0 (potential.nb)

- manuscript data (manuscript.tar.gz)

For further questions, feel free to contact me (

Keywords: Flowing foam; Phase-field simulation; Obstructed channel

Related publications


Publ.-Id: 32542

X-ray and neutron radiography of optically opaque fluid flows: experiments with particle-laden liquid metals and liquid foams

Lappan, T.

Multi-phase flows of small solid particles and gas bubbles in optically opaque fluids play a key role in both mineral and metallurgical processing, which use the principle of froth flotation and bubble flotation, respectively. To gain visual insight into such particle-laden multi-phase flows, this dissertation investigates the application of radiographic techniques, employing both X-rays and neutron radiation. Lab-scale experiments are performed with model particles in liquid foams and liquid metals, focussing on the time-resolved measurement of the particles’ motion in the multi-phase flows, aiming for a sufficient contrast-to-noise ratio in the X-ray or neutron image sequences.

The model experiments in this dissertation demonstrate the capabilities of X-ray and neutron radiography to image multi-phase flow in particle-laden and optically opaque fluids, especially to measure the motions of small particles with high spatial and temporal resolution. X-ray radiography enables to track custom-tailored tracer particles acting as tools for experimental investigations of flow phenomena in three-dimensional liquid foams. Both radiographic techniques supplement each other for imaging measurements of multi-phase flows with gas bubbles and solid particles in liquid metals. However, to visualise smallest model particles in liquid metal flows, neutron radiography proves to be the more promising technique compared to X-ray radiography. All in all, this dissertation contributes to paving the way for systematic radiographic measurements and further studies of particle-laden flows in optically opaque fluids.

Keywords: X-ray radiography; neutron radiography; liquid metal; liquid foam; flotation

  • Doctoral thesis
    TU Dresden, 2021
    Mentor: Dr. Sven Eckert, Dr. Sascha Heitkam, Prof. Kerstin Eckert


Publ.-Id: 32539

Speciation of Pd in minerals from Norilsk ores by X-ray absorption spectroscopy

Brovchenko, V. D.; Merkulova, M.; Sittner, J.; Renno, A. D.

Определены спектры рентгеновского поглощения (XANES) для Pd в пентландите, Pd в металлической форме (Pd фольга) и Pd в минералах платиновой группы, показывающие большие различия в форме всех спектров. Доказано, что палладий в пентландите не имеет ни металлической формы, ни микропримесей минералов платиновой группы, но входит в кристаллическую решетку пентландита. Энергетическое положение белой линии (3173.8 eV) спектра Pd в пентландите аналогично положению белой линии спектров Pd в минералах платиновой группы. Это свидетельствует о том, что палладий в пентландите имеет номинальное состояние окисления +2. Поэтому можно предположить, что палладий замещает атомы железа или никеля в кристаллической структуре пентландита.
X-ray absorption spectra (XANES) for Pd in pentlandite, Pd in metallic form (Pd foil) and Pd in platinum-group minerals were determined showing large differences in the shape of all spectra. It was proved that palladium in pentlandite is neither in its metal form nor in microinclusions of platinum-group minerals, but is included in the crystal lattice of pentlandite. Energy position of white line (3173.8 eV) of Pd spectrum in pentlandite is similar to the position of white line of Pd spectra in platinum group minerals. This indicates that palladium in pentlandite has a nominal oxidation state of +2. Therefore, we can assume that palladium replaces iron or nickel atoms in the crystal structure of pentlandite.

Keywords: Norilsk; X-Ray Absorption Spectroscopy; Palladium; Pentlandite

  • Open Access Logo Lecture (Conference)
    Металлогения древних и современных океанов – 2021. Сингенез, эпигенез, гипергенез Metallogeny of ancient and modern oceans - 2021. Syngenesis, epigenesis, hypergenesis, 26.-30.04.2021, Миасс - Miass, Russland


Publ.-Id: 32538

Example Project Plan generated by HELIPORT

Voigt, M.; Knodel, O.

This dataset contains the metadata for an example project generated using the project export button in our prototype scientific project lifecycle and workflow management system HELIPORT (HELmholtz ScIentific Project WORkflow PlaTform). The metadata schema is still under development and this entry will be updated to reflect further developments.

Keywords: metadata; HELIPORT; project livecycle; FAIR


Publ.-Id: 32537

Variable relative biological effectiveness (RBE) in proton therapy of benign brain tumors

Klünder, L.; Lühr, A.; Troost, E. G. C.; Liheng, T.; Krause, M.; Löck, S.; Eulitz, J.

Currently, there is an intense debate on the need to consider a variable clinical relative biological effectiveness (RBE) in proton therapy. Here, a variable clinically derived RBE-model was applied in-silico to predict the risk for late radiation-induced brain injuries (RIBI) in benign brain tumor patients having undergone proton therapy.

Materials & Methods
In total, 23 patients with benign brain tumors of WHO grade I-II, who received (adjuvant) proton radio(chemo)therapy between 2015 and 2017, were analyzed. Dose and linear energy transfer distributions were retrospectively simulated and used to calculate variable RBE-weighted dose in brain tissue. The variable RBE-model was previously derived for RIBI observed after proton therapy in grade II-IV gliomas. RBE-weighted dose, dose-volume parameters and normal tissue complication probabilities (NTCP) were calculated in brain tissue within and outside the clinical target volume (CTV) using the variable RBE-model and the clinically applied RBE of 1.1, excluding brainstem, gross tumor volume and surgical cavity from analysis.

The average difference in maximum RBE-weighted dose between the variable and constant RBE-model was 12 Gy(RBE) [range: 7.9-15 Gy(RBE)] and 14.8 Gy(RBE) [8.9-19.2 Gy(RBE)] within and outside the CTV. In the same regions, values of 9.2 Gy(RBE) [5.8-12.6 Gy(RBE)] and 1.0 Gy(RBE) [0.2-3.2 Gy(RBE)] were obtained for the difference of the mean dose. Using the variable RBE-model the cohort average D4ml (minimum dose to the hottest 4 ml) and NTCP increased by 10.8 Gy(RBE) [7.4-16.0 Gy(RBE)] and 25.4% [0.6-53.4%], respectively (figure 1).

A substantial increase in high dose and predicted RIBI risk was found in normal and normal-appearing brain tissue using the assumption of a variable RBE-model instead of a generic RBE of 1.1. After correlation of predicted with occurring RIBI on follow-up MRI scans, our results may help to verify and extend clinical RBE-models established for proton therapy of gliomas.

Keywords: Variable proton RBE; Radiation-induced brain injury; Benign brain tumors

  • Lecture (Conference) (Online presentation)
    Dreiländertagung der Medizinischen Physik, 19.-22.09.2021, Wien, Österreich

Publ.-Id: 32536

Agility of spin Hall nano-oscillators

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

Data repository for manuscript submitted to Physical Review Applied: Agility of spin Hall nano-oscillators.

DATA fingerprint for resubmitted: md5:a9bbd503a5370963b835d3c40cdf8ba8
Ignore the older onesmd5:36e53eb278f8c3073a51de6c709f72c8   (Ignore md5:3e2ddf76473149ad1d58cf100f90321f , I am unable to remove it, it is just an incomplete submission)

Data organised on a figure by figure basis. The provided file- How to navigate the data- links all the data sets and data handling scripts utilised on each figure. Ipython notebook was used in the data handling and Omnigraffle was used to assemble the sub-figures and label the plots produced in via the Ipython notebooks. Data shown in the corresponding plots can be found in the .txt files with same labelling as figures.


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

Related publications


Publ.-Id: 32535

3D CT image

Da Assuncao Godinho, J. R.

3D image, experiment 2

Related publications


Publ.-Id: 32534

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