Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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34122 Publications

On non drag interfacial force and thermal phase change modelling of reactingEulerFoam

Peltola, J.; Pättikangas, T.; Bainbridge, W.; Lehnigk, R.; Schlegel, F.

The reactingEulerFoam framework included in OpenFOAM releases since 3.0.0 provides a highly flexible platform for the modelling of multiphase flows. Extensive selection of interfacial force models is provided along with alternate turbulence models. The thermal phase change capability [1,2] was first introduced in OpenFOAM 3.0.1 [3] and has since been extended and refined in subsequent releases.
The current OpenFOAM 7 release features include support for non-equilibrium wall boiling, n-phase thermal phase change and for bubble diameter modelling algebraic, IATE and inhomogeneous class method models are supported.The present simulations have been carried out with the OpenFOAM Foundation development release [4]. The goal is to aid those that intend to use the publicly available reactingEulerFoam by providing a summary of the models and demonstrations of a few modelling details by expanding upon tutorials recently added to the OpenFOAM Foundation development line.
DEDALE experiments [5] are used as a reference for the non-drag interfacial force modelling.
Subcooled nucleate boiling simulation results with different models combinations are compared to the DEBORA experiments [6,7]. Finally, a more complex direct contact condensation simulation of SEF-POOL test facility [8] is presented and results are compared to the experiment.

References

[1] Peltola, J., & Pättikangas, T.J.H. Development and validation of a boiling model for OpenFOAM multiphase solver. CFD4NRS-4 Conference Proceedings, Daejeon, Korea, paper 59, (2012).
[2] Peltola, J., Pättikangas, T., Bainbridge, W., Lehnigk, R., Schlegel, F., On development and validation of subcooled nucleate boiling models for OpenFOAM Foundation release. NURETH-18 Conference Proceedings, Portland, Oregon, United States (2019).
[3] OpenFOAM Foundation, “OpenFOAM 3.0.1,” http://openfoam.org/version/3.0.1/ (2015).
[4] OpenFOAM Foundation, “OpenFOAM-dev,” https://openfoam.org/version/dev/ (2014-2019).
[5] Grossetete, C., Experimental investigation and numerical simulations of void profile development in a vertical cylindrical pipe (No. EDF--96-NB-00120). Electricite de France (EDF), (1995).
[6] E. Manon, Contribution à l’anayse et à la modélisation locale des écoulements boillants sous-saturésdans les conditions des Réacteurs à Eau sous Pression, PhD thesis, Ecole Centrale Paris (2000).
[7] J. Garnier, E. Manon, G. Cubizolles, “Local measurements on flow boiling of refrigerant 12 in avertical tube”, Multiphase Science and Technology, pp. 1-111 (2001).
[8] M. Puustinen, J. Laine, A. Räsänen, E. Kotro, and K. Tielinen, “Characterizing tests in SEF-POOLfacility,” Technical Report, Lappeenranta University of Technology, Nuclear Engineering, INSTAB3/2017 (2017).

  • Lecture (Conference)
    17th Multiphase Flow Conference and Short Course, 11.-15.11.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30011
Publ.-Id: 30011


Flexible development framework for the Euler Euler approach

Schlegel, F.; Greenshields, C.

The presentation gives a detailed insight into the OpenFOAM Developments for Euler-Euler simulations at HZDR, i.p. the multi-field two-fluid model approach, LES simulations, stratified flow simulations, entrainment modelling and more. Furthermore, the successfull development strategy and co-working with the OpenFOAM Foundation is explained.

Keywords: Euler-Euler; OpenFOAM; Numerical Simulation; Entrainment; Gentop; Stratified Flow

  • Invited lecture (Conferences)
    17th Multiphase Flow Conference and Short Course, 11.-15.11.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-30010
Publ.-Id: 30010


X2 benchmark specification dataset

Bilodid, Y.

The X2 VVER-1000 benchmark specification dataset.

Keywords: VVER-1000; X2 benchmark

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-11-27
    DOI: 10.14278/rodare.199
    License: CC-BY-4.0

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Permalink: https://www.hzdr.de/publications/Publ-30009
Publ.-Id: 30009


AER working group D meeting on VVER safety analysis - report of the 2019 meeting

Kliem, S.

The AER Working Group D on VVER reactor safety analysis held its 28th meeting in Garching, Germany, during the period 26-27 June, 2019. The meeting was hosted by GRS Garching and was held in conjunction with the second workshop on multi-physics MPMV-2 and the first workshop on the ROSTOV-2 benchmark. Altogether 20 participants from eleven AER member organizations and seven guests attended the meeting of the working group D. The co-ordinator of the working group, Mr. S. Kliem, served as the chairperson of the meeting.

The meeting started with a general information exchange about the recent activities in the participating organizations.

The given 12 presentations and the discussions can be attributed to the following topics:

• Safety analyses methods and results
• Code development and benchmarking
• Future activities

A list of the participants and a list of the handouts distributed at the meeting are attached to the report. The corresponding PDF-files of the handouts can be obtained from the chairperson.

  • Contribution to proceedings
    29th Symposium of AER on VVER Reactor Physics and Reactor Safety, 14.-18.10.2019, Mochovce, Slovakia
    Proceedings of the 29th Symposium of AER on VVER Reactor Physics and Reactor Safety, Budapest: Kiadja az EK, 9789637351327, 325-330

Permalink: https://www.hzdr.de/publications/Publ-30008
Publ.-Id: 30008


Microstructural evolution and thermal stability of AlCr(Si)N hard coatings revealed by in-situ high-temperature high-energy grazing incidence transmission X-ray diffraction

Jäger, N.; Meindlhumer, M.; Spor, S.; Hruby, H.; Julin, J.; Stark, A.; Nahif, F.; Keckes, J.; Mitterer, C.; Daniel, R.

An extensive understanding about the microstructural evolution and thermal stability of the metastable AlCr(Si)N coating system is of considerable importance for applications facing high temperatures, but it is also a challenging task since several superimposed processes simultaneously occur at elevated temperatures. In this work, three AlCr(Si)N coatings with 0 at.%, 2.5 at.% and 5 at.% Si were investigated by in-situ high-temperature high-energy grazing incidence transmission X-ray diffraction (HT-HE-GIT-XRD) and complementary differential scanning calorimetry and thermogravimetric analysis measurements combined with conventional ex-situ X-ray diffraction. The results revealed (i) a change in the microstructure from columnar to a fine-grained nano-composite, (ii) a reduced decomposition rate of CrN to Cr₂N, also shifted to higher onset temperatures from ∼ 1000 ℃ to above 1100 ℃ and (iii) an increase of lattice defects and micro strains resulting in a significant increase of compressive residual strain with increasing Si content. While the Si-containing coatings in the as-deposited state show a lower hardness of 28 GPa compared to AlCrN with 32 GPa, vacuum annealing at 1100℃ led to an increase in hardness to 29 GPa for the coatings containing Si and a decrease in hardness to 26 GPa for AlCrN. Furthermore, the in-situ HT-HE-GIT-XRD method allowed for simultaneously accessing temperature-dependent variations of the coating microstructure (defect density, grain size), residual strain state and phase stability up to 1100℃. Finally, the results established a deeper understanding about the relationships between the elemental composition of the materials, the resulting microstructure including crystallographic phases and residual strain state, and the coating properties from room temperature up to 1100℃.

Keywords: AlCrSiN; nano-composite; cathodic arc; thermal stability

Permalink: https://www.hzdr.de/publications/Publ-30007
Publ.-Id: 30007


Analysis of studies and research projects regarding the detection of nanomaterials in different environmental compartments and deduction of need for action regarding method development

Hildebrand, H.; Schymura, S.; Franke, K.; Fischer, C.

The aim of the present report was to obtain an overview of current strategies and methods for the detection of (manufactured) nanomaterials (NMs) in the environmental compartments surface water, soil, sediment, air, biota and sewage sludge. Based on this several recommendations for future needs of action in the short to long term are derived in order to establish a standardized detection of NMs in the environment that is necessary in order to check the pollution in the environment, to check whether or not potential risk management measures take the intended effect and to validate NM release models with real data.
A literature review was performed using predominantly “Web of Science” and screening for literature, such as review articles summarising the state of the art of NM detection techniques for environmental samples. More than 160 scientific publications were evaluated concerning NM detection methods. Results of the literature survey clearly show that a combination of detection techniques is necessary in order to detect and identify NMs, and to differentiate between natural NMs and manufactured NMs. The crucial step is accurate sample preparation for the selected detection method which means in most cases complete removal of the (disturbing) matrix and transfer of the NM in appropriate media for measurement. So far field studies in terms of detection of unknown amounts of unspecific engineered NMs in natural samples are rare and only existing for a few compartments, mainly surface waters.
Hence, it is concluded that the need of action is focused on the development, standardization and validation of existing methods in a combinatory approach.

Keywords: technische Nanomaterialien; manufactured nanomaterials Detektion; detection; Umwelt; Environment

  • Open Access Logo Other report
    Desssau-Roßlau: Umweltbundesamt, 2019
    63 Seiten

Permalink: https://www.hzdr.de/publications/Publ-30005
Publ.-Id: 30005


Soft hydrothermal synthesis of hafnon, HfSiO4

Estevenon, P.; Kaczmarek, T.; Rafiuddin, M. R.; Welcomme, E.; Szenknect, S.; Mesbah, A.; Moisy, P.; Poinssot, C.; Dacheux, N.

Despite being a member of the zircon type silicate family, the conditions allowing the hydrothermal synthesis of HfSiO4 were not well constrained. A multiparametric study was performed in order to follow the synthesis of this phase under soft hydro-thermal conditions and thus to determine the most efficient conditions to form single phase samples. Among the experi-mental parameters investigated, concentration of reactants, pH of the reactive media, temperature and duration of the hydrothermal treatment impacted significantly the formation rate of hafnon and its crystallization state. Pure HfSiO4 was obtained in acid reactive media with an acidity ranging from CHCl = 1.5 M to pH = 1.0 and for CSi ≈ CHf ≥ 0.21 mol·L 1. The silicate phase was prepared after a 24-hours treatment at temperatures ranging from 150°C to 250°C. However, rise of tem-perature and extension of the duration of the hydrothermal treatment favored the crystallization state of the final HfSiO4 samples.

Keywords: hafnium silicate; hafnon; wet chemistry route; hydrothermal synthesis; zircon structure type

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Permalink: https://www.hzdr.de/publications/Publ-30004
Publ.-Id: 30004


Thermal and flow performance of tilted oval tubes with novel fin designs

Unger, S.; Beyer, M.; Szalinski, L.; Hampel, U.

These are the raw data and the processed data of the journal paper "Thermal and flow performance of tilted oval tubes with novel fin designs".

The raw data contains the measured values on the experimental setup and the processed data contains the data of the data used in the corresponding journal publication.

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-11-26
    DOI: 10.14278/rodare.205
    License: CC-BY-4.0

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-30003
Publ.-Id: 30003


Solutal buoyancy and electrovortex flow in liquid metal batteries

Herreman, W.; Benard, S.; Nore, C.; Personnettaz, P.; Cappanera, L.; Guermond, J.-L.

Solutal buoyancy has a large impact on the flow of the alloy phase composing the positive electrode in liquid metal batteries. During discharge solutal buoyancy creates a stabilizing stratification, during charge it creates a vigorous solutal convection. In this article we provide new physical understandings of the role of solutal buoyancy during both charge and discharge. In particular we find that during discharge the electrovortex mechanism is in general not strong enough to counter the stabilizing effect of solutal buoyancy, and therefore this mechanism cannot be used to mix the alloy as is sometimes suggested in the literature. We show that the mixing capability of a generic flow in the alloy phase can be estimated by comparing the typical flow magnitude U to two velocity scales: Up and Um. Below Up the flow cannot mix the alloy, and above Um the flow significantly opposes solutal buoyancy. Although we focus on Li||Pb-based batteries, these simple mixing criteria can be used during the discharging phase in other types of liquid batteries. We also present new, fully three-dimensional simulations of solutal convection during the charging cycle. These simulations suggest scaling laws for the magnitude of the convective flow, the time for the onset of solutal convection, and the typical inhomogeneity level in the alloy during charge. We propose physical arguments to explain these scaling laws.

Keywords: mass transport; electro-vortex flow; liquid metal batteries; liquid metal electrode

Permalink: https://www.hzdr.de/publications/Publ-30001
Publ.-Id: 30001


Firm spin and parity assignment for high-lying low-spin levels in stable Si isotopes

Sinclair, J.; Scheck, M.; Finch, S. W.; Krishichayan, F.; Gayer, U.; Tornow, W.; Battaglio, G.; Beck, T.; Chapman, R.; Chishti, M. M. R.; Fransen, C.; Gonzales, R.; Hoemann, E.; Isaak, J.; Janssens, R. V. F.; Jaroszynski, D. A.; Johnson, S.; Jones, M. D.; Keatings, J. M.; Kelly, N.; Kleemann, J.; Little, D.; Löher, B.; Mashtakov, K. R.; Müscher, M.; O'Donnell, D.; Papst, O.; Peters, E. E.; Savran, D.; Schilling, P.; Schwengner, R.; Spagnoletti, P.; Spieker, M.; Werner, V.; Wilhemy, J.; Wieland, O.; Yates, S. W.; Zilges, A.

A natural silicon target was investigated in a natSi(gamma,gamma' ) photon-scattering experiment using fully polarised, quasi-monochromatic gamma rays in the entrance channel. The mean photon energies used were = 9.33, 9.77, 10.17, 10.55, 10.93, and 11.37 MeV, while the relative energy spread (Full Width Half Maximum) of the incident beam amounts to dE / E ~ 3.5 - 4 %. The observed angular distribution in the ground-state decay channel allows to propose a firm spin and parity assignment for several levels of the stable even-even silicon isotopes.

Keywords: Photon scattering; nuclear resonance fluorescence; quasimonoenergetic gamma beam; angular distribution; polarization

  • European Physical Journal A 56(2020), 105

Permalink: https://www.hzdr.de/publications/Publ-29999
Publ.-Id: 29999


PET Imaging of the Adenosine A2A Receptor in the Rotenone-Based Mouse Model of Parkinson’s Disease with [18F]FESCH Synthesized by a Simplified Two-Step One-Pot Radiolabeling Strategy

Schröder, S.; Lai, T. H.; Toussaint, M.; Kranz, M.; Chovsepian, A.; Shang, Q.; Dukic-Stefanovic, S.; Deuther-Conrad, W.; Teodoro, R.; Wenzel, B.; Moldovan, R.-P.; Pan-Montojo, F.; Brust, P.

The adenosine A2A receptor (A2AR) is regarded as a particularly appropriate target for non-dopaminergic treatment of Parkinson’s disease (PD). An increased A2AR availability has been found in the human striatum at early stages of PD and in patients with PD and dyskinesias. The aim of this small animal positron emission tomography/magnetic resonance (PET/MR) imaging study was to investigate whether rotenone-treated mice reflect the aspect of striatal A2AR upregulation in PD. For that purpose, we selected the known A2AR-specific radiotracer [18F]FESCH and developed a simplified two-step one-pot radiosynthesis. PET images showed a high uptake of [18F]FESCH in the mouse striatum. Concomitantly, metabolism studies with [18F]FESCH revealed the presence of a brain-penetrant radiometabolite. In rotenone-treated mice, a slightly higher striatal A2AR binding of [18F]FESCH was found. Nonetheless, the correlation between the increased A2AR levels within the proposed PD animal model remains to be further investigated.

Keywords: Adenosine A2A receptor; Parkinson’s disease; rotenone-based mouse model; PET imaging; [18F]FESCH; two-step one-pot radiosynthesis

Permalink: https://www.hzdr.de/publications/Publ-29998
Publ.-Id: 29998


The extracellular, cellular and nuclear stiffness, a trinity in the cancer resistome – A review

Deville, S. S.; Cordes, N.

Alterations in mechano-physiological properties of a tissue instigate cancer burdens in parallel to common genetic and epigenetic alterations. The chronological and mechanistic interrelation between the various extra- and intracellular aspects remains largely elusive. Mechano-physiologically, integrins and other cell adhesion molecules present the main mediators for transferring and distributing forces between extracellular matrix (ECM), via focal adhesomes to cytoskeleton and nucleus and vice versa of the single cell thereby affecting the pathophysiology of multicellular cancer tissues. In combina-tion with simultaneous activation of diverse downstream signaling pathways, the phenotypes of can-cer cells are created and driven characterized by deregulated transcriptional and biochemical cues that elicit the hallmarks of cancer. It, however, remains unclear how elastostatic modifications, i.e. stiffness, in the extracellular, intracellular and nuclear compartment contribute and control the re-sistance of cancer cells to therapy. In this review, we discuss how stiffness of unique tumor compo-nents dictates therapy response and what is known about the underlying molecular mechanisms.

Keywords: Stiffness; extracellular matrix, cancer resistome; radio(chemo)resistance; cell–extracellular matrix interaction; focal adhesions; solid stress

Permalink: https://www.hzdr.de/publications/Publ-29997
Publ.-Id: 29997


Discriminant Analysis for Compositional Data Incorporating Cell-wise Uncertainties

Pospiech, S.; Tolosana Delgado, R.; van den Boogaart, K. G.

In the geosciences it is still uncommon to include measurement uncertainties into numerical analysis such as discriminant analysis. The implementation of uncertainties is not trivial because data sets in geosciences often present a compositional nature, e.g. they are given as concentrations, proportions, percentages or any other form of information about the relative abundance of a set of components forming a whole. For these data the respective uncertainties are nearly never considering their compositional nature. The uncertainties can be incorporated in discriminant analysis either by each measured variable, by each observation or by using the individual, cell-wise uncertainties (each observation has for each variable an individual uncertainty). Most DA methods incorporating uncertainties use the uncertainties as weights for the variables or observations of the data set. In contrast, the here proposed method uses uncertainties to calculate a better estimation of the group variances and group means, which then influence the decision rules of quadratic respectively linear discriminant algorithm. This methodological framework does not only allow to incorporate cell-wise uncertainties, but also would largely be valid if the information about the co-dependency between uncertainties within each observation is reported.

Keywords: discriminant analysis; compositional data; cell-wise uncertainty; weighted discriminant analysis; geochemical data

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Permalink: https://www.hzdr.de/publications/Publ-29996
Publ.-Id: 29996


Tracking in magnetic fields

Müller, S.

Tracking in magnetic fields with the FLUKA radiation transport and reaction code

Keywords: FLUKA; radiation transport

  • Lecture (others)
    5th Advanced FLUKA course, 18.-22.11.2019, Paris, France

Permalink: https://www.hzdr.de/publications/Publ-29995
Publ.-Id: 29995


FLAIR:Geometries

Müller, S.

Usage of the FLAIR Geometry-Editor
(Lecture given at the 5th Advanced FLUKA Course at NEA, Paris)

Keywords: FLUKA; FLAIR

  • Lecture (others)
    5th FLUKA Advanced Course, 18.-22.11.2019, Paris, France

Permalink: https://www.hzdr.de/publications/Publ-29994
Publ.-Id: 29994


Non-quenching photoluminescence emission up to at least 865 K upon near-UV excitation in a single crystal of orange-red emitting SmPO4

Sharma, S.; Beyer, J.; Gloaguen, R.; Heitmann, J.

The adjustment of photoluminescence emission spectrum and an enhancement in the thermal stability of red/orange-red emitting phosphors is an important issue for the whole lighting industry. Herein, we present our results on the luminescence spectroscopy of a single crystal sample of SmPO4 exhibiting a prominent orange-red emission at 597 nm, along with a charge-transfer absorption (O2− → Sm3+) around 200 nm. We study the temperature dependence of emission spectra in SmPO4 for excitations at 365 and 455 nm, to mimic experimental conditions for phosphor converted light emitting diodes, to show that the sample has a non-quenching photoluminescence emission up to at least 865 K for an excitation at 365 nm, and ∼865 K for an excitation at wavelength, 455 nm. The thermal stability of SmPO4 was found to be much higher than its structural analogue, EuPO4, which is also an orange-red emission phosphor, but possesses a thermal quenching temperature of 710 K (exc. 365 nm), and 735 K (exc. 455 nm). The extraordinary thermal stability of SmPO4 is a result of the energy transfer from deep defects to the Sm3+ ions at high temperatures. The color purity of SmPO4 (65%) was found to be slightly lower than the EuPO4 sample (70%), at room temperature. The results suggests that the rare earth orthophosphate, SmPO4, has a large potential for near-UV excited phosphor converted solid state lighting devices.

Keywords: SmPO4; photoluminescence; thermal quenching; lighting

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Permalink: https://www.hzdr.de/publications/Publ-29993
Publ.-Id: 29993


X2 VVER-1000 benchmark revision: fresh HZP core state and the reference Monte Carlo solution

Bilodid, Y.; Fridman, E.; Lötsch, T.

The X2 VVER-1000 benchmark provides a unique set of VVER-1000 plant data: the detailed core definition, operational history of the first four fuel cycles and various measurement results. This paper presents the second revision of the benchmark specification with significant improvements such as detailed reflector definition, corrected material compositions, clear illustrations etc. The reference solution for the hot zero power experiments conducted during the fresh core start-up was obtained with the Serpent-2 Monte Carlo code. The calculated and measured values of a critical boron concentration, temperature reactivity effect, and control rod worth are in a very good agreement while the deviations lay within the measurement uncertainties. Further extension of the benchmark definition is foreseen for a future work.

Keywords: X2 benchmark; VVER-1000; Serpent

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  • Secondary publication expected from 07.05.2021

Permalink: https://www.hzdr.de/publications/Publ-29992
Publ.-Id: 29992


Ab initio dielectric response function of diamond and other relevant high pressure phases of carbon

Ramakrishna, K.; Vorberger, J.

The electronic structure and dielectric properties of the diamond, body centered cubic diamond (bc8), and hexagonal diamond (lonsdaleite) phases of carbon are computed using density functional theory and many-body perturbation theory with the emphasis on the excitonic picture of the solid phases relevant in the regimes of high-pressure physics and warm dense matter. We also discuss the capabilities of reproducing the inelastic x-ray scattering spectra in comparison with the existing models in light of recent x-ray scattering experiments on carbon and carbon bearing materials in the Megabar range.

Keywords: high pressure effects; dielectric functions; warm dense matter

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  • Secondary publication expected from 22.11.2020

Permalink: https://www.hzdr.de/publications/Publ-29991
Publ.-Id: 29991


Batch reactor vs. flow column – mechanistic investigation and modeling of Au(III) ions adsorption from aqueous solutions containing Ni2+, Na+, Cl¯ and ClO4¯ as impurities.

Marek, W.; Pierrick, N.; Magdalena, L.-B.; Robert, S.; Yang, X.; Zbigniew, P.

In this paper, a mechanistic analysis of the adsorption and reduction of gold(III) chloride complex ions on the activated carbon surface were described. All experiments were performed in the presence of nickel ions. Obtained results confirm that there is no influence of light and heavy cations on the adsorption process. From the Arrhenius equation, activation parameters such as activation energy (17.53±0.98 kJ/mol) and pre-exponential (28.7±8.91 min-1 ) factor were determined. SEM and XRD, as well as XPS analysis, have confirmed the presence of metallic gold on the surface of activated carbon. The concentration distribution of gold inside activated carbon after adsorption process both for continuous stirred tank reactor and continuous flow reactor was determined. New estimator for interfacial area of mass transfer was defined.

Keywords: Au(III) ions adsorption; chemical reduction; active carbon; kinetic studies; continuous synthesis; mathematical model CSTR vs. CFR

Permalink: https://www.hzdr.de/publications/Publ-29990
Publ.-Id: 29990


Controlled inline fluid separation based on smart process tomography sensors

Sahovic, B.; Atmani, H.; Sattar, M. A.; Garcia, M. M.; Schleicher, E.; Legendre, D.; Climent, E.; Zamanski, R.; Pedrono, A.; Babout, L.; Banasiak, R.; Portela, L.; Hampel, U.

Today’s mechanical fluid separators in industry are mostly operated without any control to maintain efficient separation for varying inlet conditions. Controlling inline fluid separators, on the other hand, is challenging for two reasons: the process is very fast and measurements in the multiphase stream are difficult as conventional sensors typically fail here. With recent improvement of process tomography sensors alongside with an increase in processing power of smart computers, such sensors can now be potentially used in inline fluid separation. Within the European Innovative Training Network TOMOCON we develop concepts for tomography-controlled inline fluid separation. It comprises of electrical tomography and wire-mesh sensors, a fast and massive data processing and an appropriate control strategy to control the process via valve action or alternative actuation principles. Solutions and ideas presented in this paper base on process models derived from theoretical investigation, numerical simulations and analysis of experimental data.

Keywords: Inline fluid separation; CFD simulation; Wire-mesh sensor; Electrical tomography; Control systems

Permalink: https://www.hzdr.de/publications/Publ-29989
Publ.-Id: 29989


Uranium(VI) complexation with aqueous silicates in the acidic to alkaline pH-range

Lösch, H.; Tits, J.; Marques-Fernandes, M.; Baeyens, B.; Krüger, S.; Chiorescu, I.; Stumpf, T.; Huittinen, N. M.

An important parameter for the safety assessment of radioactive waste repositories is the prediction and modelling of aqueous complex formation reactions between actinides (An) and common dissolved inorganic or organic ligands.Alteration processes at the contact zone between the backfill material, bentonite, or the clay host rock and the cementitious materials of the geotechnical barrier will lead to high silicate concentrations in the groundwater, which may strongly influence the aqueous speciation of actinides[1]. A detailed knowledge of the An–silicate complex formation is therefore very important. In the present study, we have investigated the U(VI)-complexation in with aqueous silicates using two approaches: 1) Time-resolved laser-induced luminescence spectroscopy(TRLFS) in the acidic pH-range (pH 3.5)was used to determine the in-situU(VI) speciation in dependency of temperature(1-25°C)and silicon concentration, 2) the Schubert method was used to acquire the U(VI)-silicate complexation constant and stoichiometryin the alkaline pH-range where no literature data for U(VI)-silicates currently exists. For the TRLFS studythe uranium concentration was fixed at 5×10-6Mwith an ionic strength of 0.2 M (NaClO4),while the silicon concentration was varied between 3×10-4and1.5×10-3M. In the absence of silicate the 1:1 U-hydroxo complex was found to play a significant role in the U-speciationin the acidic pH-range. With increasing silicon concentration an increase of the luminescence intensity and a bathochromic shift of the emission spectra couldbe observed. Based on the peak deconvolution the free component spectra of U-hydroxo and U-silicate complexeswere extracted. The following slope analysis resulted in aslope close to 1 for all temperatures, confirming the formation of the UO2OSi(OH)3+complex at pH 3.5. The temperature dependent measurements enabledthe determination of the thermodynamicparameters ΔrH0=46.3kJ∙mol-1and ΔrS0=154.1J∙K-1∙mol-1. For the Schubert method, the U(VI) sorption distribution coefficient Rdon ZrO2was determined by LSC-measurements as a function of the ligand concentration and the pH in the alkaline pH range. By plotting the Rd-values as a function of the ligand concentration, information about the number of involved ligands in the U(VI)-silicate complex could be obtained. When further plotting the fitting constant (obtained from the Rd-plot) as a function of log[H+], the number of protons involved in the complexation reaction and the conditional complexation constant could be determined. With the obtained stoichiometry, two possible complexes could be proposed in the alkaline pH-range.DFT-calculations supportedthe formation of the UO2(OH)2OSi(OH)3complex.References:[1]D. Savage, Mineral. Mag., 2011, 75

  • Lecture (Conference)
    Gesellschaft Deutscher Chemiker, Jahrestagung der Fachgruppe Nuklearchemie 2019, 25.-27.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29988
Publ.-Id: 29988


Uranium(VI) complexation with aqueous silicates in the acidic to alkaline pH-range

Lösch, H.; Tits, J.; Marques-Fernandes, M.; Baeyens, B.; Chiorescu, I.; Krüger, S.; Stumpf, T.; Huittinen, N. M.

An important parameter for the safety assessment of radioactive waste repositories is the prediction and modelling of aqueous complex formation reactions between actinides (An) and common dissolved inorganic or organic ligands. Alteration processes at the contact zone between the backfill material, bentonite, or the clay host rock and the cementitious materials of the geotechnical barrier will lead to high silicate concentrations in the groundwater, which may strongly influence the aqueous speciation of actinides such as uranium, which is stable in the hexavalent oxidation state under oxidizing conditions. [1]. A detailed knowledge of the U(VI) –silicate complex formation is therefore very important.
Depending on the used host rock and backfill material, the pH of the groundwater will be in the neutral to alkaline range. However, in this pH-range, reliable thermodynamic data for aqueous An(VI) - silicate complexes are scarce. In the acidic pH-range, only the 1:1 An(VI)-Si complex, i.e. An(VI)O2OSiOH3+, has been determined for U(VI), Np(VI), and Pu(VI), and the complex formation constants differ by almost two orders of magnitude (Table 1) [2].
Table 1: Complex formation constants for An(VI)-Si complexes [2].
An logK0
U(VI) -1,86
Np(VI) -2,61
Pu(VI) -3,65

In the alkaline pH-range (pH ~8), Yusov et al. [3] postulated the formation of either a ternary Pu-OH-Si complex: (PuO2(H2O)3(OH)OSi(OH)3) with the H3SiO4- ligand or a binary Pu-Si complex (PuO2(H2O)3O2Si(OH)2) with H2SiO42-. For other hexavalent actinides, no complexes in the alkaline pH-range have been reported, however, in analogy with Pu(VI), comparable complexes should also exist for U(VI) and Np(VI).
This contribution reports on a study of the U(VI) complexation with silicate in the pH range between 3.4 and 11.5. Two approaches were used: 1) Time-resolved laser-induced luminescence spectroscopy (TRLS) was applied to determine the in situ U(VI) speciation in U(VI) solutions with various silicate concentrations and various pH. 2) U(VI)-silicate complexation constants and complex stoichiometries were determined using Schubert’s method. For the TRLFS measurements, a U(VI) concentration of 5×10-6 M (pH = 3.5) or 1×10-7 M (pH = 9) was used, while the silicon concentration was varied between 3×10-4 and 1.5×10-3 M. To determine the thermodynamic parameters ΔrH0 and ΔrS0, temperature dependent measurements were performed in the range from 1°C to 25°C. The ionic strength was fixed with NaClO4 at 0.2 M. The Schubert method allows determination of complex stoichiometry and complexation constant by measuring the solid/liquid distribution ratio (Rd value) for the U(VI) sorption on a solid phase in absence and in the presence of increasing concentrations of silicate. Here, monoclinic ZrO2 was used as a solid phase. The U(VI) concentration in the experiments was 1×10-7 M and silicate concentrations were varied between 5×10-5 and 5×10-3 M, at pH values ranging from 6.0 to 11.5 at an ionic strength of 0.1 M NaCl. LSC measurements of the 233U activity were used to determine the U(VI) concentration in solution.
In the absence of aqueous silicates, the 1:1 uranium hydrolysis species UO2OH+ plays a significant role in the speciation starting from a pH of 3.5. Therefore, this species has to be taken into account in the speciation. Figure 1 shows the luminescence spectra with increasing Si-concentration at different temperatures. The obtained spectra show a bathochromic shift and an increase in the luminescence intensity with increasing silicate concentration. Based on peak deconvolution, the pure component spectra of the UO2OSi(OH)3+ and UO2OH+ complex were extracted. The species distributions were calculated by a least-square fit method. The following slope analysis resulted in a slope close to 1 for all temperatures, confirming the formation of a UO2OSi(OH)3+ complex at pH 3.5. The obtained complexation constants were corrected to standard conditions using the Davies equation. The obtained stability constant at 25°C is significantly higher than the literature values due to the consideration of the hydroxo complex and the solubility limit of the aqueous silicates [2]. A van’t Hoff plot was used to extract the reaction enthalpy and entropy, which were found to be ΔrH0 = 46.3 kJ∙mol-1 and ΔrS0 = 154.1 J∙K-1∙mol-1.

Figure 1: Emission spectra of the U-Si complexation at pH 3.5 with varying [Si] between 3×10-4 and 1.5×10-3 M, [U] = 5×10-6 M, fixed [NaClO4] = 0.2 M, in the temperature range between 1°C to 25°C.
For the Schubert method, the U(VI) sorption distribution coefficient Rd on ZrO2 was determined by LSC-measurements as a function of the ligand concentration and the pH in the alkaline pH range. By plotting the Rd-values as a function of the ligand concentration, information about the number of involved ligands in the U(VI)-silicate complex could be obtained. When further plotting the fitting constant (obtained from the Rd-plot) as a function of corrected pH, the number of protons involved in the complexation reaction and the conditional complexation constant could be determined. With the obtained stoichiometry, two possible complexes could be proposed in the alkaline pH-range, (i) UO2(OH)O2Si(OH)2- or (ii) UO2(OH)2OSi(OH)3-. DFT-calculations support the formation of the second complex with a corrected stability constant of logK0 = -16.30.


[1] D. Savage, Mineral. Mag.,2011, 75, 2401-2418.
[2] R. Guillaumont et al., Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium, 2003, NEA-TBD.
[3] A. B. Yusov, A. M. Fedoseev, Russ. J. Coord. Chem., 2003, 29, 625-634.

  • Lecture (Conference)
    17th International Conference on the Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere, 15.-20.09.2019, Kyoto, Japan

Permalink: https://www.hzdr.de/publications/Publ-29987
Publ.-Id: 29987


PET for the imaging of cerebral α7 acetylcholine receptors: from tracer development to clinical application

Teodoro, R.; Deuther-Conrad, W.; Scheunemann, M.; Wenzel, B.; Peters, D.; Barthel, H.; Patt, M.; Sabri, O.; Brust, P.

Background: Changes in the expression of homomeric α7 nicotinic acetylcholine receptors (α7 nAChR) in the human brain are widely assumed to be associated with neuropsychiatric and neurooncologial processes. Indeed, thoroughly performed studies have shown the ability of α7 nAChR modulators to minimise the extent of cell death as well as to promote synaptic plasticity in different diseases including depression, schizophrenia, stroke and Alzheimer´s disease. Nonetheless, up to date, the clinical meaningful findings obtained with these agents were not always supported by a complete understanding of the downstream effects initiated by α7 nAChR modulators.
Methods: To help understanding these processes an extensive work has been done by our and other groups on the development of positron emission tomography (PET) α7 nAChR agents labeled with the radioisotopes fluorine-18 (18F) and carbon-11 (11C). So far two main classes of α7 nAChR PET tracers have advanced to clinical trials: scaffolds composed of a three-side binding mode to the receptor (e.g., hydrogen bond acceptor, hydrophobic element and a rigid basic amine as the cationic centre), and the scaffolds containing fused functionalities belonging to the interferon inducer tilorone class of derivatives.
Results and Discussion: Structure-activity relationship studies on these two classes have been the subject of continuous research aiming at the development of highly affine and selective α7 nAChR PET tracers with suitable pharmacokinetic properties for an accurate receptor occupancy quantification and distribution of α7 nAChR in the brain. As a result, [18F]NS10743, [18F]NS14490, [11C]NS14992, [18F]DBT10 and its ortho isomer [18F]ASEM emerged as the most promising α7 nAChR PET tracers developed so far. Studies in piglets were done for [18F]NS10743 and [11C]NS14992. Ongoing clinical trials have been reported using [18F]ASEM. Efforts to translate [18F]DBT10 into the clinics have been initiated with its transfer onto an automated synthesis in compliance to clinical production. The results of a successful pre-clinical imaging study, including dosimetry in piglets and evaluation in monkeys suggests the suitability of [18F]DBT10 for imaging α7 nAChR. Very recently a pilot study in a large animal model of ischemic stroke in sheep revealed a high inflammation-related specific uptake of [18F]DBT10 in the stroke border 14 days after permanent middle cerebral artery occlusion.
Conclusion: Among the receptor-specific α7 nAChR PET tracers developed so far, the dibenzothiophene isomers [18F]DBT10 and [18F]ASEM are under continuous investigation due to their suitable pharmacokinetics and high target-specific signal. More proof-of-concept studies are required to support the usefulness of these tracers for sensitive and specific α7 nAChR PET imaging.

Keywords: nicotinic acetylcholine receptors; alpha 7; PET

  • Lecture (Conference)
    International Symposium on Trends in Radiopharmaceuticals (ISTR 2019), 28.10.-01.11.2019, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-29986
Publ.-Id: 29986


The capability of Ansys CFX to predict the mixing phenomena in ROCOM test facility

Boumaza, M.; Höhne, T.; Mohammedi, B.; Dizene, R.

This work consists of a Computational Fluid Dynamics (CFD) modeling of a reference experiment on boron dilution in the Rossendorf coolant mixing Model (ROCOM) as part of a coordinated research project of the International Atomic Energy Agency, namely, “Application of numerical codes of fluid dynamics to the design of nuclear power plants”. This coordinated project aims to address the application of CFD codes to the process of optimizing the design of nuclear power plants related to pressurized water reactors and to evaluate the performance and predictive capabilities of these codes and to contribute to their validation. In this context, a three-dimensional numerical simulation study was carried out using CFD code ANSYS CFX v14.5, to study the boron mixing phenomenon at the core inlet and the downcomer of the ROCOM test facility. The phenomenon of experimental mixing occurs by the injection of a tracer (sodium chloride) into one of the loops of the ROCOM installation mainly containing demineralized water in its primary circuit. The concentration field of the tracer is measured and simulated at the entrance of the heart and in the lowering. The SST-kω turbulence model used in this study could reasonably predict the distribution of the injected tracer in measurement locations within the test facility. The results of this numerical simulation were compared to the Benchmark data provided by the ROCOM experimental facility of the Helmholtz-Zentrum Dresden-Rossendorf Institute.

Keywords: Boron dilution CFD codes Mixing

Permalink: https://www.hzdr.de/publications/Publ-29984
Publ.-Id: 29984


Inhibition of ATP hydrolysis restores airway surface liquid production in cystic fibrosis airway epithelia

van Heusden, C.; Button, B.; Anderson, W. H.; Ceppe, A.; Morton, L. C.; O'Neal, W. K.; Dang, H.; Neil, E. A.; Donaldson, S.; Stephan, H.; Boucher, R. C.; Lazarowski, E. R.

Airway surface dehydration is a pathological feature of cystic fibrosis (CF) lung disease. 20 CF is caused by mutations in the CF transmembrane conductance regulator (CFTR), a cyclic 21 AMP-regulated Cl- channel controlled in part by the adenosine A2B receptor. An alternative, 22 CFTR-independent mechanism of fluid secretion is regulated by ATP, via the P2Y2 receptor 23 (P2Y2R) that activates Ca2+-regulated Cl- channels (CaCC/TMEM16) and inhibits Na+ 24 absorption. However, due to rapid ATP hydrolysis, steady-state ATP levels in CF airway surface 25 liquid (ASL) are inadequate to maintain P2Y2R-mediated fluid secretion. Therefore, inhibiting 26 airway epithelial ecto-ATPases to increase ASL ATP levels constitutes a strategy to restore 27 airway surface hydration in CF. Using [γ32P]ATP as radiotracer, we assessed the effect of a 28 series of ATPase inhibitory compounds on the stability of physiologically occurring ATP 29 concentrations. We identified the polyoxometalate [Co4(H2O)2(PW9O34)2]10- (POM-5) as the 30 most potent and effective ecto-ATPase inhibitor in CF airway epithelial cells. POM-5 caused 31 long-lasting inhibition of ATP hydrolysis in airway epithelia, which was reversible upon removal 32 of the inhibitor. Importantly, POM-5 markedly enhanced steady-state levels of released ATP, 33 promoting increased ASL volume in CF cell surfaces. These results provide proof-of-concept for 34 ecto-ATPase inhibitors as therapeutic agents to restore hydration of CF airway surfaces. As a test 35 of this notion, cell-free sputum supernatants from CF subjects were studied and found to have 36 abnormally elevated ATPase activity, which was markedly inhibited by POM-5.

Keywords: Extracellular ATP; ecto-ATPases; purinergic receptors; cystic fibrosis; polyoxometalates

Permalink: https://www.hzdr.de/publications/Publ-29983
Publ.-Id: 29983


Towards Optimal Bubble Generation for Biological Wastewater Treatment

Mohseni, E.; Reinecke, S. F.; Hampel, U.

Gas bubble dispersion determines the efficiency of the aeration process in biological wastewater treatment plants (WWTP). The purpose of aeration is to provide an aerobic environment for microbial degradation of organic matters. This is an expensive procedure, which is responsible for the largest share of energy bill in the whole WWTP in the range from 45% to 75% [1]. The state of the art of aerators, which are currently in use at the activated sludge facilities, is the rubber membrane diffusers. These diffusers offer relatively low standard oxygen transfer efficiency (SOTE) in the range of 40% to 60% [2]. Several factors affect the SOTE, e.g. the gas holdup, bubble size, bubble residence time, and the apparent viscosity [3]. Among these parameters, the bubble size is of a great importance, since it directly influences the gas holdup and the bubble residence time. Moreover, the bubble size determines the surface area to volume ratio, which affects the volumetric oxygen transfer coefficient k_L a and the oxygen transfer rate OTR. To specify the oxygen transfer, one needs to know the mass transfer coefficient from a gas bubble as a function of its diameter and accurate information on the terminal bubble rising velocity. Accordingly, Motarjemi and Jameson have measured the initial bubble size required to achieve 95% transfer of available oxygen from an air bubble as a function of the depth of the basin [3].
To achieve the optimal bubble size, it is important to know the relation between the initial bubble volume and other influential parameters, e.g. the gas flow rate, orifice diameter, gas reservoir volume, and physical properties of both phases. Since 1960, many authors have tried to calculate the initial bubble volume. The majority of these models divide the bubble formation into two stages, namely the growing stage and the elongation stage through a neck. Each stage can be solved either by its corresponding force balance, or by empirical assumptions related to the moment of bubble detachment. Although these models are quite reliable in low flow rates, by increasing the gas flow rate, they diverge. Latter is due to the fact that, the assumptions, which are used to close the equations in each stage, do not take into account the variation in the detachment condition at different bubbling regimes.By increasing the gas flow rate, the bubble surface moves more dynamic and the influence of the gas momentum force is more pronounced. In this case, the final bubble is a product of multiple coalescence of smaller bubbles right above the orifice. Moreover, the three-phase contact of the gas phase, the liquid phase, and the solid phase during the bubble formation is generally a dynamic procedure. However, in most of the models this measure is assumed to be a constant value.

In the current study, we investigate the bubble formation from a submerged orifice at different bubbling regimes. To track the three-contact phase point inside and above the orifice, we use an optical setup with a matched refractive index of the solid and the liquid phase. Consequently, we are able to follow the three-phase contact point even inside of the orifice. To mimic the bubble formation in water, we keep the dimensionless Reynolds number constant. The bubble formation is recorded with a high-speed camera with a maximum spatial resolution of 2 μm and a temporal resolution of up to 25 μs.
The gas flow rate is set via a mass flow controller. We cover the full range of bubbling regimes, from the quasi-static to the chaotic regime. Similar to Badam et al., the change in the map of the bubbling regime is reported according to the dimensionless Froude and Bond number [4]. By increasing the gas flow rate, we track the progressive bubble volume and the trajectory of the bubble’s center of mass using an in-house bubble tracking algorithm. Latter enables us to report the change in the distance of the bubble’s center of mass to the orifice surface, until one instant before the bubble pinch-off, and correlate it to its corresponding bubbling regime. By implementing these detachment conditions, we develop a model to estimate the final bubble volume. Finally, using this model we are able to estimate the appropriate operating parameters, e.g. the gas flow rate, and the orifice diameter, in order to achieve the optimal bubble size for enhanced aeration efficiency.


References
1. Zimmerman, W.B., V. Tesař, and H.H. Bandulasena, Towards energy efficient nanobubble generation with fluidic oscillation. Current Opinion in Colloid & Interface Science, 2011. 16(4): p. 350-356.
2. Wang, L.K., N.K. Shammas, and Y.-T. Hung, Advanced biological treatment processes. Vol. 9. 2010: Springer Science & Business Media.
3. Motarjemi, M. and G. Jameson, Mass transfer from very small bubbles—the optimum bubble size for aeration. Chemical Engineering Science, 1978. 33(11): p. 1415-1423.
4. Badam, V., V. Buwa, and F. Durst, Experimental investigations of regimes of bubble formation on submerged orifices under constant flow condition. The Canadian Journal of Chemical Engineering, 2007. 85(3): p. 257-267.

Keywords: Bubble Formation; Aeration; Activated Sludge; Oxygen Mass Transfer; Bubbling Regime

  • Contribution to proceedings
    14th International Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering (GLS-14), 30.05.-03.06.2019, Guilin, China

Permalink: https://www.hzdr.de/publications/Publ-29982
Publ.-Id: 29982


Hemodynamic impairments within individual watershed areas in asymptomatic carotid artery stenosis by multimodal MRI

Kaczmarz, S.; Goettler, J.; Petr, J.; Hansen, M. B.; Mouridsen, K.; Zimmer, C.; Hyder, F.; Preibisch, C.

Improved understanding of complex hemodynamic impairments in asymptomatic internal carotid artery stenosis (ICAS) is crucial to better assess stroke risks. Multimodal MRI is ideal to measure brain hemodynamics and has the potential to improve diagnostics and treatment selection. We applied MRI-based perfusion and oxygenation sensitive imaging in ICAS, hypothesizing that sensitivity to hemodynamic impairments will improve within individual watershed areas (iWSA).We studied cerebral blood flow (CBF), cerebrovascular reactivity (CVR), relative cerebral blood volume (rCBV), relative oxygen extraction fraction (rOEF), oxygen extraction capacity (OEC) and capillary transit time heterogeneity (CTH) in 29 patients with asymptomatic, unilateral ICAS (age 70.3±7.0y) and 30 age-matched healthy controls (HCs). In ICAS, we found significant impairments of CBF, CVR, rCBV, OEC, and CTH (strongest lateralization ∆CVR=-24%) – but not of rOEF. Even though spatial overlap of compromised hemodynamic parameters within each patient varied in a complex manner, most pronounced changes of CBF, CVR and rCBV were detected within iWSAs (strongest effect ∆rCBV=+96%). At the same time, CTH impairments were iWSA independent, indicating widespread dysfunction of capillary-level oxygen diffusivity. In summary, complementary MRI-based perfusion and oxygenation parameters offer deeper perspectives on complex microvascular impairments in individual patients. Furthermore, knowledge about iWSAs improves sensitivity to hemodynamic impairments.

Permalink: https://www.hzdr.de/publications/Publ-29981
Publ.-Id: 29981


ExploreASL: an image processing pipeline for multi-center ASL perfusion MRI studies

Mutsaerts, H. J.; Petr, J.; Groot, P. F.; Vandemaele, P.; Ingala, S.; Robertson, A. D.; Vaclavu, L.; Groote, I.; Kuijf, H.; Zelaya, F.; O'Daly, O.; Hilal, S.; Wink, A. M.; Kant, I.; Caan, M.; Morgan, C.; de Bresser, J.; Lysvik, E.; Schrantee, A.; Bjornebekk, A.; Clement, P.; Shirzadi, Z.; Kuijer, J.; Anazodo, U.; Pajkrt, D.; Richard, E.; Bokkers, R.; Reneman, L.; Masellis, M.; Guenther, M.; Macintosh, B.; Achten, E.; Chappell, M.; van Osch, M.; Golay, X.; Thomas, D.; de Vita, E.; Bjornerud, A.; Nederveen, A.; Hendrikse, J.; Asllani, I.; Barkhof, F.

Arterial spin labeling (ASL) has undergone significant development since its inception, with a focus on improving standardization and reproducibility of its acquisition and quantification. In a community-wide effort towards robust and reproducible clinical ASL image processing, we developed the software package ExploreASL, allowing standardized analyses across centers and scanners. The procedures used in ExploreASL capitalize on published image processing advancements and address the challenges of multi-center datasets with scanner-specific processing and artifact reduction to limit patient exclusion. ExploreASL is self-contained, written in MATLAB and based on Statistical Parameter Mapping (SPM) and runs on multiple operating systems. The toolbox adheres to previously defined international standards for data structure, provenance, and best analysis practice. ExploreASL was iteratively refined and tested in the analysis of >10,000 ASL scans using different pulse-sequences in a variety of clinical populations, resulting in four processing modules: Import, Structural, ASL, and Population that perform tasks, respectively, for data curation, structural and ASL image processing and quality control, and finally preparing the results for statistical analyses on both single-subject and group level. We illustrate ExploreASL processing results from three cohorts: perinatally HIV-infected children, healthy adults, and elderly at risk for neurodegenerative disease. We show the reproducibility for each cohort when processed at different centers with different operating systems and MATLAB versions, and its effects on the quantification of gray matter cerebral blood flow. ExploreASL facilitates the standardization of image processing and quality control, allowing the pooling of cohorts to increase statistical power and discover between-group perfusion differences. Ultimately, this workflow may advance ASL for wider adoption in clinical studies, trials, and practice.

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Publ.-Id: 29980


ASL-BIDS, the brain imaging data structure extension for arterial spin labeling

Clement, P.; Castellaro, M.; Okell, T.; Thomas, D.; Gorgolewski, C.; Appelhoff, S.; Petr, J.; Chappell, M.; Mutsaerts, H.-J.

Purpose/Introduction: The Brain Imaging Data Structure (BIDS) is a recently developed data storage standard, that meets the need for a structured manner to organize imaging data in the age of big datasets and data sharing (https://bids.neuroimaging.io). 1 This abstract presents a BIDS extension for ASL, which only supports ASL approaches as recommended in the ASL acquisition consensus paper, and several M0 calibration approaches. 2

Subjects and Methods: A group of ASL experts initiated this extension by defining several concepts and preparing a first draft. This draft was shared online from May 2017 until March 2019 with the international ASL community, and several teleconference and face-to-face meetings were organised. Per BIDS convention, existing BIDS fields were reused for the ASL-BIDS extension if possible. The BIDS fields names were based on the NEMA ASL DICOM fields, where possible. Additionally, three example datasets were collected 3
and efforts were initiated to adapt existing ASL analysis tools and the BIDS validator for ASL-BIDS compatibility.

Results: Six concepts were defined to allow a uniform yet flexible ASL-BIDS specification. First, it was decided to focus solely on the implementation of the ASL approaches discussed in the ASL consensus paper: single- and multi-delay, pulsed, continuous, and pseudo-continuous ASL. 5 Second, the BIDS-structure consists of two mandatory files and several optional files (Fig. 1). Third, it is obligatory to keep the ASL time series in the original acquisition order in a 4D NIfTI file, including any M0, if it was part of the original ASL
time series. If an M0 image was acquired separately, it should be stored as a separate NIfTI file. The ASL-context BIDS field explains the content of each volume in the ASL time series. Fourth, the derivative images DeltaM and CBF are considered to be raw images if the ASL-sequence or vendor only provided derivative images, lacking raw data. This principle follows the prioritization shown in Fig. 2. Fifth, all ASL data need to be stored in at least 32 bit floating point, without any scale slopes. Some vendor implementations store scaled ASL data to increase the precision of the stored data within the traditional 12 bit DICOM files. It is the responsibility of the DICOM to BIDS conversion to apply any existing scale slopes. Sixth, it is recommended to specify as much information as labeling as possible: the exact location of the labeling plane and the labeling efficiency.

Discussion/Conclusion: The current ASL-BIDS extension is restricted to the ASL approaches recommended by the consensus paper. 1 With the current development of more advanced ASL approaches, such as time-encoded and velocity-selective ASL, the ASL-BIDS may be extended for these technique. Also, a derivatives extension for ASL is anticipated.

  • Poster
    ESMRMB 2019, 36th Annual Scientific Meeting, 05.10.2019, Rotterdam, Netherlands
  • Abstract in refereed journal
    Magnetic Resonance Materials in Physics, Biology and Medicine 32(2019)Suppl 1, S147-S148
    DOI: 10.1007/s10334-019-00754-2

Permalink: https://www.hzdr.de/publications/Publ-29979
Publ.-Id: 29979


Multi-modal evaluation of haemodynamic impairments within individual watershed areas reveals increased sensitivity in unilateral carotid artery stenosis

Kaczmarz, S.; Göttler, J.; Petr, J.; Hansen, M. B.; Kufer, J.; Zimmer, C.; Mouridsen, K.; Hyder, F.; Preibisch, C.

Purpose/Introduction: Internal carotid-artery stenosis (ICAS) is a major public health issue and causes complex haemodynamic impairments. 1–3 However, influences of microvascular effects remain poorly understood. Furthermore, increased sensitivity for regional pathophysiological changes is required to detect early disease stages.
The aim of our study was therefore to establish a multi-modal MRI protocol allowing deeper insights into the pathology. Furthermore, we hypothesize to be most sensitive to ICAS-impairments within individual watershed areas (iWSAs), which were proposed to be most vulnerable to haemodynamic compromise. 4

Subjects and Methods: Fifty-nine participants (29 unilateral ICAS-patients, age = 70.1 ± 4.8y and 30 age-matched healthy controls [HC]) underwent MRI on a Philips 3T Ingenia. The imaging protocol yielded oxygenation, perfusion and microvascular biomarkers which are summarized in Fig. 1. Additionally, iWSA’s were defined for each participant. 4 Mean haemodynamic parameter values were compared within each hemisphere of ICAS-patients vs. HC and inside vs. outside iWSAs (Fig. 2A, B) in GM and WM.

Results: Exemplary data of an ICAS-patient is shown in Fig. 2. On group-level, significant lateralisation of CBF, CVR, rCBV, CTH and OEC were found in ICAS, while rOEF was not lateralized (Fig. 3). Lateralisation was significantly enhanced inside iWSAs compared to outside of iWSAs for CBF and CVR, with a strong trend for rCBV—and strongest in WM of iWSAs (t test, p \ 0.05). OEC and CTH were indeed lateralized, but not different inside vs. outside iWSAs (Fig. 3). All HC parameters were symmetrical (data not shown).
Discussion/Conclusion: We successfully applied the proposed multimodal MRI-protocol and demonstrated its sensitivity to haemodynamic impairments in ICAS. Specificity was affirmed by symmetrical HC results. Individual parameter lateralisation in ICAS excellently agrees with the literature. Decreased CVR along with increased rCBV indicates chronic vasodilation. 1 Pronounced effects in WM-iWSA fit with the different blood supply in GM/WM. Ipsi-laterally decreased CBF, symmetrical rOEF 2 and increased CTH also coincide with recent studies 3 . The DCBF vs. DrOEF mismatch could relate to variable oxygen diffusivity 8 —potentially moderated by CTH 3, 9 . Interestingly, CTH and OEC lateralisation were iWSA-location independent, which matches previous findings. 10 These complimentary information of TTP and CTH about macrovascular effects, respectively microvascular flow 3 are highly promising to gain deeper insights into the pathology. And as initially hypothesized, evaluation within iWSA significantly increased the sensitivity to
CBF, CVR and rCBV impairments and allows to detect even subtle changes.

  • Lecture (Conference)
    ESMRMB 2019, 36th Annual Scientific Meeting, 05.10.2019, Rotterdam, Netherlands
  • Abstract in refereed journal
    Magnetic Resonance Materials in Physics, Biology and Medicine 32(2019)Suppl 1, S352-S353
    DOI: 10.1007/s10334-019-00755-1

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-29978
Publ.-Id: 29978


Multi-modality perfusion imaging in gliomas: quantitative and visual comparison between ASL, DSC, and [15O]H20 PET

Petr, J.; Verburg, N.; Koopman, T.; Kuijer, J. P.; Barkhof, F.; van den Hoff, J.; Boellaard, R.; de Witt Hamer, P. C.; Mutsaerts, H. J.

Purpose/Introduction
Glioma vascularization and perfusion are important factors for tumor diagnostics. Dynamic Susceptibility Contrast (DSC) provides a proxy of perfusion by measuring mean transit time and blood volume and is sensitive to blood-brain-barrier breakdown. Arterial spin labeling (ASL) measures true tissue perfusion and can thus provide complementary information to DSC that may aid in tumor grading and in imaging the treatment response to, e.g., antiangiogenic drugs. Agreement of ASL and PET was shown in volunteers 1 .
However, ASL can also partly show intravascular signal making ASL imaging of tumors challenging especially in the presence of vascular shunting. We compared ASL and DSC to the gold-standard for perfusion, [ 15 O]H 2 0 PET, to understand their limits as a surrogate of true regional perfusion.

Subjects and Methods
As part of the FRONTIER study, 8 glioma patients underwent multiple biopsies before scanning using Philips 3T Achieva MR and Gemini PET-CT 2 . PET (10min, 370 MBq of [ 15 O]H 2 0, simultaneous arterial blood sampling), ASL (pCASL 2D EPI, post-labeling delay and labeling duration 1800ms, 3x3x5 mm 3 ), DSC (TR 1.9s, TE 30ms, 1.7x2.4x3.6mm 3 , preloaded contrast) images were acquired. Cerebral blood flow (CBF) was quantified for ASL with ExploreASL, for DSC with Olea Sphere 3.0 with AIF obtained manually from MCA 3 . CBF images were aligned to PET and downsampled 6x6x6mm 3 resolution. Mean and voxel-wise CBF was compared between modalities in tumors and in contralateral-hemisphere gray matter (GM). Absolute and relative CBF (divided by subject’s mean whole-hemisphere contralateral GM CBF) were assessed.

Results
Mean hemispheric and voxelwise GM CBF values in the contralateral hemisphere were compared before and after normalization to global GM mean. For relative CBF, we observed a linear relationship between modalities in the tumor maximum values. Voxelwise analysis shows good agreement of PET and ASL for CBF ratio<1.5. For higher values ASL overestimated CBF, however, the relation was monotonic. DSC and ASL differed due to ASL overestimation in shunting vessels or low DSC signal in non-enhancing
gliomas.

Discussion/Conclusion
CBF normalization to contralateral GM improves the agreement of ASL and PET in tumors, after which a linear relationship in tumor-maximum was observed between all three modalities. The voxel-wise analysis, however, showed that ASL overestimates CBF in the presence of vascular shunting offering a different type of contrast than perfusion. We also observed increased CBF in both PET and ASL in non-enhancing tumors where CBF was underestimated by DSC. ASL presents a viable alternative to DSC with a monotonic relation to PET CBF, can present complementary information to DSC and thus warrants further research in its utility for glioma assessment.

  • Lecture (Conference)
    ESMRMB 2019, 36th Annual Scientific Meeting, 05.10.2019, Rotterdam, Netherlands

Permalink: https://www.hzdr.de/publications/Publ-29977
Publ.-Id: 29977


Glioma MR Imaging 2.0: a new European Cooperation in Science & Technology (COST) Action

Clement, P.; Hirschler, L.; Jančálek, R.; Keil, V.; Maumet, C.; Petr, J.; Smits, M.; Zhao, M.; Warnert, E. A. H.

Purpose/Introduction
In Europe, 50,000 new cases of primary glioma occur each year, and this number is expected to rise with the aging population 1 . Established international consortia are putting tremendous research efforts into a better understanding of glioma pathology and improved treatment strategies. Magnetic resonance imaging (MRI) only has a minor role in these research efforts, despite being a widely available medical imaging modality and whilst advanced MRI techniques are emerging with great potential for improved characterisation of
glioma. To exploit advanced MRI to the fullest, two issues need to be solved: (1) The scattered research landscape in which advanced MRI is being developed for glioma imaging. (2) The limited presence of advanced MRI research in established consortia for clinical work and research in glioma. To solve these issues, we have recently formed Glioma MR Imaging 2.0 (GliMR), an international consortium funded by the European Cooperation in Science & Technology (COST) 2 . In the coming 4 years, GliMR will establish an
international network of experts in glioma research, patient organisations, and data and MR imaging scientists that aims to progress development and application of MRI for improved decision making in diagnosis, patient monitoring, and assessment of treatment response in clinical trials and practice.

Subjects and Methods
GliMR starts as a network of 37 proposers spread across 22 countries world-wide (Figure 1). There are 5 working groups (WGs) (Figure 2) that will ensure we will reach the Research Coordination and Capacity Building Objectives of the network (Table 1) via the organisation of meetings, workshops, and training schools. Additionally, individual researchers and clinicians can apply for funds to go on Short Term Scientific Missions (STSMs) and gain experience by working in a different hospital/lab abroad. The network will be open to new members and participation for all those interested is highly encouraged.

Results
GliMR will lead to an international network operating at the forefront of glioma imaging diagnostics. It will result into recommendations and open-access software tools for advanced MRI assessment of glioma, the creation of multi-site, cross-border data sets on glioma imaging, and strengthened connections between all stakeholders in glioma diagnostics. GliMR will facilitate further understanding of glioma pathophysiology, scientific breakthroughs in novel therapies and improve personalised patient management, ultimately
increasing the quality of life of patients diagnosed with glioma.

Discussion/Conclusion
We would like to thank all proposers and our advisors for their input to the proposal. Special thanks go to the EORTC, GLASS, INCF, PanCare Society, Gold Standard Phantoms, Medical Software Solutions, Mediri, and Quantib for endorsing GliMR.

  • Lecture (Conference)
    ESMRMB 2019, 36th Annual Scientific Meeting, 05.10.2019, Rotterdam, Netherlands

Permalink: https://www.hzdr.de/publications/Publ-29976
Publ.-Id: 29976


Molekulare Bildgebung des Adenosin-A2A-Rezeptors: Synthese und Evaluierung des hochaffinen 18F-markierten Radiotracers [18F]FLUDA

Lai, T. H.; Teodoro, R.; Toussaint, M.; Gündel, D.; Dukic-Stefanovic, S.; Deuther-Conrad, W.; Schröder, S.; Moldovan, R.-P.; Brust, P.

Der Adenosin-A2A-Rezeptor (A2AR) ist ein vielversprechendes Target für die molekulare Bildgebung sowohl von neurodegenerativen Erkrankungen als auch von Tumoren mittels PET. Bis zum jetzigen Zeitpunkt ist [18F]MNI 444 [Ki(hA2AR) = 2,8 nM] der einzige 18F-markierte Radiotracer, welcher in einer klinischen Studie an gesunden Probanden untersucht wurde (1). Ausgehend von dem literaturbekannten [18F]FESCH [Ki(hA2AR) = 0,6 nM] sollte durch chemische Modifikation ein deuteriertes Analogon mit einer erhöhter metabolischer Stabilität entwickelt werden (2,3).

Die Synthese von FLUDA basiert auf der Einführung einer deuterierten Fluoroethoxy-Gruppe. Für die Radiosynthese von [18F]FLUDA wurde eine zweistufige Eintopfmethode ausgehend von einem Phenol- und [2H4]Ethylenditosylat-Präkursor entwickelt. Die In vitro- und In-vivo-Evaluierung erfolgte mittels Autoradiographie-, Metaboliten- und PET-Studien in CD-1 Mäusen.

Es wurde eine Radiosynthese von [18F]FLUDA [Ki(hA2AR) = 0,6 nM] mit einer radiochemischen Ausbeute von 19±3% (n = 9) etabliert. Im Vergleich zu [18F]FESCH zeigt das deuterierte [18F]FLUDA eine deutlich gesteigerte In-vivo-Stabilität (15 min p.i., Gehirn: 91% intaktes [18F]FLUDA). Die In-vitro-Autoradiographie von [18F]FLUDA weist eine spezifische Aktivitätsanreicherung im Striatum nach, die durch die Rezeptorparameter KD = 4,3±0,7 nM und Bmax = 556±143 fmol/mg charakterisiert ist. In den PET-Studien wurde ein SUV-Verhältnis (SUVR) Striatum/Cerebellum von >8 (15-30 min) nachgewiesen. Selektive A2AR-Blockadestudien mit 2,5 mg/kg Tozadenant führten zu einem signifikanten Rückgang dieses SUVR um 35%.

Die Radiosynthese des neuen Radiotracers [18F]FLUDA wurde erfolgreich etabliert. Aufgrund der vielversprechenden präklinischen Ergebnisse wird derzeit die Translation von [18F]FLUDA in die Klinik vorbereitet.

(1) Barret et al., J Nucl Med 2015, 56, 586-91
(2) Bhattacharjee et al., Nucl Med Biol 2011, 38, 897-906
(3) Khanapur et al., J Med Chem 2014, 57, 6765-80

Keywords: Adenosine-A2A-Rezeptor; PET; Radiotracer; Fluor-18

  • Lecture (Conference) (Online presentation)
    Nuklearmedizin 2020 - DIGITAL, 07.-09.07.2020, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29975
Publ.-Id: 29975


Anforderungen an Materialien zur definierten Immobilisierung von Biomolekülen und Zellen

Raff, J.

In dem Vortag wird der aktuelle Stand der Forschungen zur Funktionalisierung von Oberflächen am HZDR vorgestellt und daraus entsprechende Anforderungen an Materialien zur definierten Immobilisierung von Molekülen und Zellen abgeleitet.

Keywords: Immobilisierung; Funktionalisierung; Mikroskopie

  • Invited lecture (Conferences)
    PolCarr-Innovationsforum, 28.-29.03.2019, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29974
Publ.-Id: 29974


Spatially-resolved speciation of Eu(III) and Cm(III) on granite surfaces

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

The search for a suitable site for a nuclear waste repository in Germany requires linking molecular scale information with the large scale of the repository. Here, we present a novel approach to bridge the gap from the molecular to the millimeter scale.
We complement well-known surface investigation techniques such as Raman microscopy, interferometry and autoradiography with μTRLFS. This newly developed technique allows the investigation of luminescent radionuclides, such as Cm(III) and its chemical homologue Eu(III), on the surface of crystalline rocks with complex mineral composition. The combination of multiple surface investigation techniques allows to draw a correlation between surface mineralogy, topography, radionuclide speciation and the resulting retention behavior.
In an initial μTRLFS study using natural granite from Eibenstock, Germany, it was found that uptake strength, capacity, and homogeneity vary from mineral to mineral. For example, Eu(III) on feldspars adsorbed relatively weakly but in large amounts, whereas only minor sorption was observed on quartz, but with a high sorption strength. In addition, distinct sorption behavior was found on some mineral grain boundaries.[1]
To obtain a more comprehensive picture, granitic drill core samples were obtained from across Europe, from which thin section samples were prepared for μTRLFS experiments. The sorption of Eu(III) and Cm(III) onto these samples was conducted using solutions with defined ionic strength, metal concentration and pH.
We will discuss the speciation differences between varying mineral phases one each rock, as well as differences between the characteristic crystalline rocks from diverse locations and the potential impact of the radionuclide speciation on their migration properties in the geosphere. Additionally the results will be compared to single phase studies from literature to evaluate the validity of an additive component mixing approach.

Keywords: sorption; granite; europium; curium; spatial; resolution

  • Lecture (Conference)
    Goldschmidt Barcelona 2019, 18.-23.08.2019, Barcelona, Spanien
  • Lecture (Conference)
    GDCh Jahrestagung der Fachgruppe Nuklearchemie 2019, 25.-27.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29973
Publ.-Id: 29973


Hemodynamic impairments in asymptomatic unilateral carotid artery stenosis are most pronounced within individual watershed areas

Kaczmarz, S.; Petr, J.; Hansen, M. B.; Hock, A.; Kufer, J.; Mouridsen, K.; Zimmer, C.; Hyder, F.; Preibisch, C.; Göttler, J.

Background: Watershed areas are most susceptible for ischemia in patients with high-grade internal carotid artery stenosis (ICAS) [1]. Thorough investigation of the currently not well understood hemodynamic impairments is important to improve treatment guidelines. [2] Here, we propose a multimodal-MRI protocol to better characterise hemodynamic impairments in asymptomatic ICAS with increased sensitivity within individual watershed areas (iWSA).
Methods: Twenty-nine asymptomatic, unilateral ICAS patients (age = 70.1 ± 4.8y), and 30 age-matched healthy controls (age = 70.3 ± 7.3y) underwent 3T-MRI. Imaging yielded maps of cerebrovascular reactivity (CVR) [3], cerebral blood flow (CBF) [4], relative oxygen extraction fraction (rOEF), [5] relative cerebral blood volume (rCBV), capillary transit-time heterogeneity (CTH), and oxygen extraction capacity (OEC) [6] (Fig. 1). Based on DSC-derived time-to-peak (TTP) maps, iWSAs were defined for each participant (Fig. 2a) [7]. Mean hemodynamic parameter values within each hemisphere were compared between ICAS-patients vs. HC and inside vs. outside iWSAs (Fig. 2a, b) within GM and WM.
Result: We found significant lateralisation of CBF, CVR, rCBV, CTH, and OEC for ICAS-patients (all p < 0.05), whereas no significant rOEF lateralisation was found (Fig. 2). Inside iWSAs, lateralisation was enhanced for CBF and CVR (p < 0.05), with a strong trend for rCBV.
Overall, lateralisation was stronger within WM than GM (Fig. 2I).
Contrary, OEC and CTH were indeed lateralised, but comparable inside vs. outside iWSAs (Fig. 2I). For HC, all parameters were symmetrical between hemispheres (data not shown).
Discussion: Observed impairments of CBF, CVR, and CBV are in line with recent studies [8]. As proposed, CBF and CVR impairments are specifically pronounced within iWSAs (Fig. 2I). Interestingly, CTH and OEC were lateralized, however not specifically changed within iWSAs, indicating an independently impaired hemodynamic mechanism.
Conclusion: CBF and CVR reductions may be indicative of the severity of hemodynamic changes within iWSAs, and thus future stroke risk. CTH and OEC impairments are independent of iWSA locations.

  • Lecture (Conference)
    54. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., 09.10.2019, Frankfurt, Germany
  • Open Access Logo Abstract in refereed journal
    Clinical Neuroradiology 29(2019)Suppl. 1, 288
    DOI: 10.1007/s00062-019-00826-9

Permalink: https://www.hzdr.de/publications/Publ-29972
Publ.-Id: 29972


Recovery of cerebrovascular reactivity after treatment of asymptomatic carotid artery stenosis is assessable by non-invasive breath-hold fMRI within global watershed areas

Kaczmarz, S.; Petr, J.; Sollmann, N.; Hock, A.; Zimmer, C.; Hyder, F.; Preibisch, C.; Göttler, J.

Background: Treatment of asymptomatic internal carotid artery stenosis (ICAS) patients remains still controversial [1]. Hemodynamic biomarkers such as the cerebrovascular reactivity (CVR) are promising to identify patients who benefit from revascularization precedures [2–4]. However, commonly employed methods are invasive acetazolamide or complicated gas applications [2–6]. The aim of our study was therefore to measure CVR recovery in ICAS-patients after treatment by easily-applicable breath-hold fMRI (BH-fMRI) with increased sensitivity by evaluation within global watershed areas (gWSAs) [7].
Methods: Thirty-three participants (16 asymptomatic, unilateral ICAS-patients, age = 71.4 ± 5.8y, and 17 healthy controls [HC], age = 70.8 ± 5.3y, see Fig. 1) underwent MRI on a 3T Philips Ingenia.
All participants were scanned twice, patients before and at least three months after treatment, HC at similar follow-up delays. BH-fMRI comprised five breath-holds à 15s each; CVR-maps were calculated by data-driven analysis [8] (Fig. 2a, b). Lateralization of CVR was calculated in GM of gWSAs between hemispheres for each participant (Fig. 2c).
Result: Exemplary ICAS-patient’s data shows impaired CVR before treatment, which recovered after treatment (Fig. 1A,B). On group level, CVR was significantly impaired ipsilateral to the stenosis before treatment (Fig. 3a, t-test, p = 0.0038). After treatment, CVR significantly recovered (2-sample t-test, p = 0.0495) resulting in symmetrical CVR between hemispheres (t-test, p = 0.25). HC data was symmetrical between hemispheres (Fig. 3b, p > 0.60).
Discussion: BH-fMRI based evaluation within gWSAs was sensitive to CVR impairments in asymptomatic ICAS, indicating chronic vasodilation [5]. Specificity was affirmed by symmetrical HC results. Consistent with current literature, CVR recovered after ICAS-treatment [4–7], demonstrating improved hemodynamic status.
Conclusion: We successfully analyzed CVR recovery after ICAS treatment by easily applicable, tolerable and non-invasive BH-fMRI within clinically feasible scan times. This technique could potentially improve future treatment decisions.

  • Lecture (Conference)
    54. Jahrestagung der Deutschen Gesellschaft für Neuroradiologie e.V., 09.10.2019, Frankfurt, Germany
  • Open Access Logo Abstract in refereed journal
    Clinical Neuroradiology 29(2019)Suppl. 1, 290
    DOI: 10.1007/s00062-019-00826-9

Permalink: https://www.hzdr.de/publications/Publ-29971
Publ.-Id: 29971


Tuning the metal-insulator transition in epitaxial SrVO3 films by uniaxial strain

Wang, C.; Zhang, H.; Deepak, K.; Chen, C.; Fouchet, A.; Duan, J.; Hilliard, D.; Kentsch, U.; Chen, D.; Zeng, M.; Gao, X.; Zeng, Y.-J.; Helm, M.; Prellier, W.; Zhou, S.

Understanding of the metal-insulator transition (MIT) in correlated transition-metal oxides is a fascinating topic in condensed matter physics and a precise control of such transitions plays a key role in developing novel electronic devices. Here we report an effective tuning of the MIT in epitaxial SrVO3 (SVO) films by expanding the out-of-plane lattice constant without changing in-plane lattice parameters, through helium ion irradiation. Upon increase of the ion fluence, we observe a MIT with a crossover from metallic to insulating state in SVO films. A combination of transport and magnetoresistance measurements in SVO at low temperatures reveals that the observed MIT is mainly ascribed to electron-electron interactions rather than disorder-induced localization. Moreover, these results are well supported by the combination of density functional theory and dynamical mean field theory (DFT+DMFT) calculations, further confirming the decrease of the bandwidth and the enhanced electron-electron interactions resulting from the expansion of out-of-plane lattice constant. These findings provide insights into the understanding of MIT in correlated oxides and perspectives for the design of unexpected functional devices based on strongly correlated electrons.

Keywords: Oxide thin film; Strain engineering; Metal-insulator transition; Lattice distortion; Correlated electrons

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Permalink: https://www.hzdr.de/publications/Publ-29969
Publ.-Id: 29969


Confirmation of the prognostic value of pretherapeutic tumor SUR and MTV in patients with esophageal squamous cell carcinoma

Hofheinz, F.; Li, Y.; Steffen, I.; Lin, Q.; Lili, C.; Hua, W.; van den Hoff, J.; Zschaeck, S.

Purpose

The prognosis for patients with inoperable esophageal carcinoma is still poor and the reliability of individual therapy outcome prediction based on clinical parameters is not convincing. In a recent publication, we were able to show that PET can provide independent prognostic information in such a patient group and that the tumor-to-blood standard uptake ratio (SUR) can improve the prognostic value of tracer uptake values. The present investigation addresses the question of whether the distinctly improved prognostic value of SUR can be confirmed in a similar patient group that was examined and treated at a different site.
Methods

18F-FDG PET/CT was performed in 147 consecutive patients (115 male, 32 female, mean age: 62 years) with newly diagnosed esophageal squamous cell carcinoma prior to definitive radiochemotherapy. In the PET images, the metabolic active volume (MTV) of the primary tumor was delineated with an adaptive threshold method. For the resulting ROIs, SUVmax and total lesion glycolysis (TLG = MTV × SUVmean) were computed. The blood SUV was determined by manually delineating the aorta in the low-dose CT. SUR values were computed as ratio of tumor SUV and blood SUV. Univariate Cox regression and Kaplan–Meier analysis with respect to overall survival (OS), distant-metastases-free survival (DM), and locoregional control (LRC) was performed. Additionally, a multivariate Cox regression including clinically relevant parameters was performed.
Results

Univariate Cox regression revealed MTV, TLG, and SURmax as significant prognostic factors for OS. MTV as well as TLG were significant prognostic factors for LRC while SURmax showed only a trend for significance. None of the PET parameters was prognostic for DM. In univariate analysis, SUVmax was not prognostic for any of the investigated clinical endpoints. In multivariate analysis (T-stage, N-stage, MTV, and SURmax), MTV was an independent prognostic factor for OS and showed a trend for significance for LRC. SURmax was not an independent predictor for OS or LRC. When including the PET parameters separately in multivariate analysis, MTV as well as SURmax were prognostic factors for OS indicating that SURmax is independent from the clinical parameters but not from MTV. In addition, MTV was an independent prognostic factor for LRC in this separate analysis.
Conclusions

Our study revealed a clearly improved prognostic value of tumor SUR compared to tumor SUV and confirms our previously published findings regarding OS. Furthermore, SUR delivers prognostic information beyond that provided by the clinical parameters alone, but does not add prognostic information beyond that provided by MTV in this patient group. Therefore, our results suggest that pretherapeutic MTV is the parameter of choice for PET-based risk stratification in the considered setting but further investigations are necessary to demonstrate that this suggestion is correct.

Keywords: PET Esophageal cancer Definitive radiochemotherapy SUV SUR

Permalink: https://www.hzdr.de/publications/Publ-29968
Publ.-Id: 29968


HZDR Data Management Strategy — Meeting at Leibniz Institute of Polymer Research Dresden (IPF)

Knodel, O.; Gruber, T.; Müller, S.

Top-Level Architecture of the proposed HZDR Data Management Strategy with an example experiment

Keywords: data management

  • Open Access Logo Invited lecture (Conferences)
    Meeting at Leibniz Institute of Polymer Research Dresden (IPF), 15.11.2019, Dresden, Germany

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Permalink: https://www.hzdr.de/publications/Publ-29967
Publ.-Id: 29967


Validation of an independent prognostic value of the asphericity of F18-fluorodeoxyglucose (FDG) uptake in non-small cell lung cancer (NSCLC) patients undergoing treatment in curative intent

Rogasch, J.; Furth, C.; Chibolela, C.; Hofheinz, F.; Ochsenreither, S.; Rückert, J.; Neudecker, J.; Böhmer, D.; Laffert, M.; Amthauer, H.; Frost, N.

Background

In patients with non-small cell lung cancer (NSCLC), asphericity (ASP) of the primary tumor’s metabolic tumor volume (MTV) has shown prognostic significance. This study aimed at validation in an independent, sufficiently large cohort.
Patients and Methods

Retrospective study in 311 NSCLC patients undergoing FDG-PET/CT before curatively intended treatment (always including surgery). 140 patients had UICC stage I, 78 stage II, and 93 stage III (adenocarcinoma [ADC]:153; squamous cell carcinoma [SCC]:141). Primary tumor MTV was delineated with semiautomated background-adapted threshold relative to SUVmax. Cox regression (PFS/OS) for PET (MTV, ASP, SUVmax), clinical (T/N descriptor, UICC stages), histological and treatment variables (Rx/1 vs. R0 resection, chemotherapy/radiotherapy yes/no).
Results

Events (progression/relapse) occurred in 167/311 patients, 137 died (median survivor follow-up, 37 months). In multivariable Cox regression for OS, ASP>33.3% (HR, 1.58 [1.04-2.39]), male sex (1.84), age (1.04 per year), EGOG≥2 vs. 0/1 (2.68), stage II vs. I (1.96), and Rx/1 vs. R0 resection (2.1) were significant. Among separate UICC stages, ASP only predicted OS in stage II (optimal, >19.5%; median OS, 33 vs. 59 months). Regarding PFS, ASP>21.2%, male sex, EGOG≥2, stage II vs. I, and Rx/1 resection were prognostic. ASP remained prognostic in stage II (optimal, >19.5%; PFS, 12 vs. 47 months). Log-rank test for ASP was significant at any cut-off ≥18% (OS) or from 9-59% (PFS).
Conclusion

ASP was validated as prognostic factor for PFS and OS in patients with NSCLC and curative treatment intent, especially stage II. High ASP in stage II could imply intensified treatment or intensified follow-up.

Keywords: Prognosis; survival; FDG-PET; metabolic tumor volume; quantification

Permalink: https://www.hzdr.de/publications/Publ-29966
Publ.-Id: 29966


Introduction of the New Center for Radiopharmaceutical Cancer Research at Helmholtz-Zentrum Dresden-Rossendorf

Kreller, M.; Pietzsch, H.-J.; Walther, M.; Tietze, H.; Kaever, P.; Knieß, T.; Füchtner, F.; Steinbach, J.; Preusche, S.

A new Center for Radiopharmaceutical Cancer Research was established at the Helmholtz-Zentrum Dresden-Rossendorf in order to centralize radionuclide production, radiopharmaceutical production and the chemical and biochemical research facilities. The newly installed cyclotron is equipped with two beamlines, two target selectors and several liquid, gas and solid target systems. The cyclotron including the target systems and first results of beam characterization measurements as well as results of the radionuclide production are presented. The produced radionuclides are automatically distributed from the targets to the destination hot cells. This process is supervised and controlled by an in-house developed system.

Keywords: cyclotrons; radionuclide production; solid, liquid and gas targets

Permalink: https://www.hzdr.de/publications/Publ-29965
Publ.-Id: 29965


Microstructural characterization of inhomogeneity in 9Cr ODS EUROFER steel

Das, A.; Chekhonin, P.; Altstadt, E.; Bergner, F.; Heintze, C.; Lindau, R.

Ferritic-martensitic ODS steels are one of the candidate materials for Gen-IV nuclear fission and fusion reactors. Residual ferrite was often found in the microstructure of 9Cr ODS steels. This constituent was reported to be responsible for the superior creep and high-temperature strength. Using optical microscopy of an air-cooled batch of ODS EUROFER, inhomogeneous regions in the microstructure have been found with similar appearance to previously reported residual ferrite. Detailed microstructural investigations have been carried out on the inhomogeneous regions using site-specific nanoindentation, scanning electron microscopy including electron backscatter diffraction, and transmission electron microscopy. It is demonstrated that the inhomogeneous regions are formed due to imperfect mechanical alloying leading to the absence of oxide nanoparticles and consequently lower hardness. It is concluded that optical microscopy is insufficient to distinguish beneficial residual ferrite from undesired particle-free regions. The weakness of the inhomogeneous regions is attributed to the absence of nanoparticles and a lower dislocation density. Our findings are underpinned by the consistency between the calculated theoretical yield strength, the yield strength converted from the indentation hardness and the yield strength obtained from tensile testing.

Keywords: ODS steel; ferritic-martensitic steel; inhomogeneity; nanoindentation; residual ferrite

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  • Secondary publication expected from 01.05.2021

Permalink: https://www.hzdr.de/publications/Publ-29964
Publ.-Id: 29964


Time reversal and quantum Loschmidt echo in optical lattices

Schützhold, R.; Szpak, N.

A quantum Loschmidt echo (also referred to as quantum time mirror) corresponds to an effective time inversion after which the quantum wave function reverses its previous time evolution and eventually reaches its initial distribution again. We propose a comparably simple protocol for such an effective time reversal for ultra-cold atoms in optical lattices which should be easier to realize experimentally than previous proposals.

Keywords: Quantum Physics; Quantum Gases

Permalink: https://www.hzdr.de/publications/Publ-29961
Publ.-Id: 29961


Reply to comment on "Interaction of a BEC with a gravitational wave"

Schützhold, R.

This reply contains a brief response to the comment by R. Howl, D. Rätzel, and I. Fuentes [arXiv:1811.10306]

Keywords: Quantum Physics; General Relativity and Quantum Cosmology

Permalink: https://www.hzdr.de/publications/Publ-29960
Publ.-Id: 29960


Quantum simulation of spontaneous pair creation in 2D optical lattices

Schützhold, R.; Klar, L.; Szpak, N.

One of the fundamental predictions of Quantum Electrodynamics (QED) is the spontaneous creation of particle--antiparticle pairs from vacuum in presence of a very strong electric field. Under these extreme conditions a strongly bound state can fetch an otherwise unobservable electron from the Dirac sea, leaving behind a hole representing a positron. Although generally known for many decades, the effect has not yet been demonstrated experimentally. We propose an analogue model of the quantum Dirac field, realized by ultra--cold fermionic atoms in an optical lattice, aiming at an experimental simulation of this intriguing non--perturbative phenomenon. Numerical simulations demonstrate the effect of spontaneous pair creation in the optical analogue system, in qualitative agreement with QED: in the adiabatic regime the vacuum can be destabilized only by supercritical fields exceeding a critical threshold.

Keywords: Quantum Physics; Quantum Gases

Permalink: https://www.hzdr.de/publications/Publ-29959
Publ.-Id: 29959


Phonon Pair Creation by Inflating Quantum Fluctuations in an Ion Trap

Schützhold, R.; Wittemer, M.; Hakelberg, F.; Kiefer, P.; Schröder, J.-P.; Warring, U.; Schaetz, T.; Fey, C.

Quantum theory predicts intriguing dynamics during drastic changes of external conditions. We switch the trapping field of two ions sufficiently fast to tear apart quantum fluctuations, i.e., create pairs of phonons and, thereby, squeeze the ions’ motional state. This process can be interpreted as an experimental analog to cosmological particle creation and is accompanied by the formation of spatial entanglement. Hence, our platform allows one to study the causal connections of squeezing, pair creation, and entanglement and might permit one to cross-fertilize between concepts in cosmology and applications of quantum information processing.

Keywords: Inflation; Quantum Information with trapped Ions; Quantum simulation

Permalink: https://www.hzdr.de/publications/Publ-29958
Publ.-Id: 29958


Relaxation dynamics in a Hubbard dimer coupled to fermionic baths: phenomenological description and its microscopic foundation

Schützhold, R.; Kleinherbers, E.; Szpak, N.; König, J.

We study relaxation dynamics in a strongly-interacting two-site Fermi-Hubbard model that is induced by fermionic baths. To derive the proper form of the Lindblad operators that enter an effective description of the system-bath coupling in different temperature regimes, we employ a diagrammatic real-time technique for the reduced density matrix. An improvement on the commonly-used secular approximation, referred to as coherent approximation, is presented. We analyze the spectrum of relaxation rates and identify different time scales that are involved in the equilibration of the Hubbard dimer after a quantum quench.

Permalink: https://www.hzdr.de/publications/Publ-29957
Publ.-Id: 29957


Hydrodynamic data of an advanced inclined rotating fixed-bed reactor

Timaeus, R.; Schleicher, E.; Bieberle, A.; Hampel, U.; Schubert, M.

This publication contains the hydrodynamic data of an advanced inclined rotating fixed-bed reactor with inner tube. The phase distribution in the cross-section of the reactor and the normalized liquid filling level (normalized to the reactor diameter) were obtained with a capacitance wire-mesh sensor. Besides, the specific pressure drops for the investigated operating points are given. Furthermore, the porostiy profile of different configurations (different particle and inner tube diameter) are stored, which were obtained by gamm-ray computed tomography.

Keywords: Capacitance wire-mesh sensor; gamma-ray tomography; inclined rotating fixed-bed reactor

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-11-18
    DOI: 10.14278/rodare.203

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-29956
Publ.-Id: 29956


Technetium retention by gamma alumina nanoparticles and the effect of sorbed Fe²⁺

Mayordomo Herranz, N.; Rodriguez Hernandez, D. M.; Schild, D.; Molodtsov, K.; Johnstone, E. V.; Hübner, R.; Shams Aldin Azzam, S.; Brendler, V.; Müller, K.

Technetium (Tc) retention on gamma alumina nanoparticles (gamma-Al₂O₃ NPs) has been studied in the absence (binary system) and presence (ternary system) of previously sorbed Fe²⁺ as a reducing agent. In the binary system, gamma-Al₂O₃ NPs sorb up to 6.5% of Tc from solution as Tc(VII). In the ternary system, the presence of previously sorbed Fe²⁺ on gamma-Al₂O₃ NPs significantly enhances the uptake of Tc from pH 4 to pH 11. Under these conditions, the reaction rate of Tc increases with pH, resulting in a complete uptake for pHs > 6.5. Redox potential (Eh) and X-ray photoelectron spectroscopy (XPS) measurements evince heterogeneous reduction of Tc(VII) to Tc(IV). Here, the formation of Fe containing solids was observed; Raman and scanning electron microscopy showed the presence of Fe(OH)₂, Fe(II)-Al(III)-Cl layered double hydroxide (LDH), and other Fe(II) and Fe(III) mineral phases, e.g. Fe₃O₄, FeOOH, Fe₂O₃. These results indicate that Tc scavenging is predominantly governed by the presence of sorbed Fe²⁺ species on gamma-Al₂O₃ NPs, where the reduction of Tc(VII) to Tc(IV) and overall Tc retention is highly improved, even under acidic conditions. Likewise, the formation of additional Fe solid phases in the ternary system promotes the Tc uptake via adsorption, co-precipitation, and incorporation mechanisms.

Keywords: Technetium; Al₂O₃; reduction; sorption; immobilization

Permalink: https://www.hzdr.de/publications/Publ-29955
Publ.-Id: 29955


High-Speed Data Acquisition System and Real-time Data Processing using FPGA Architecture

Bawatna, M.; Kovalev, S.; Deinert, J.-C.

The super radiant THz sources at TELBE facility is based on the new class of accelerator-driven terahertz (THz) radiation sources that provide high repetition rates up to 13 MHz, and flexibility of tuning the THz pulse form. The THz pulses are used for the excitation of materials of interest, about two orders of magnitude higher than state-of-the-art tabletop sources. Time-resolved experiments can be performed with a time resolution down to 30 femtoseconds (fs) using the novel pulse-resolved Data Acquisition (DAQ) system. However, the increasing demands in improving the flexibility, data throughput, and speed of the DAQ systems motivate the integration of reconfigurable processing units close to the new detectors to accelerate the processing of tens of GigaBytes of data per second. In this poster, we introduce our online ultra fast DAQ system that uses an FPGA architecture for real-time image processing, as well as interfacing the image sensors and provide a continuous data transfer.

Keywords: Ultra fast DAQ system; Pulse-resolved Data Acquisition (DAQ) system; Field Programmable Gate Array (FPGA)

  • Open Access Logo Poster
    MT ARD ST3 Annual meeting, 16.-18.10.2019, Darmstadt, Germany

Permalink: https://www.hzdr.de/publications/Publ-29954
Publ.-Id: 29954


High speed data acquisition with online analysis

Bawatna, M.; Green, B. W.; Kovalev, S.; Deinert, J.-C.

TELBE THz facility is performing ultra-fast pump-probe experiments by providing a unique combination of high pulse energies and high repetition rates. In this type of experiment, the electric or magnetic field in the THz pump pulse acts as the excitation of dynamics in the matter. This dynamic in turn is then probed by ultra-short (light) pulses, typically with the sub THz cycle resolution. A pulse resolved DAQ system has been developed at TELBE user facility to allow the performance of time-resolved THz spectroscopy measurements with sub 30 fs Full-Width Half Maximum (FHWM) time resolution with excellent dynamic range up to 120 dB.

  • Open Access Logo Poster
    The 6th Accelerator Research & Development (ARD) Workshop, 26.-28.09.2018, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-29953
Publ.-Id: 29953


High-Speed Data Acquisition and Online Analysis System at MHz Repetition Rate

Bawatna, M.; Green, B. W.; Deinert, J.-C.; Kovalev, S.

A unique high-rep-rate pulse-resolved detection scheme has been developed at TELBE that provides timing down to 12 fs by post-mortem arrival time jitter correction. This allows experiments to take full advantage of the superior properties of the light source without sacrificing the ability to perform high-resolution, high dynamic range, time-resolved experiments previously only available with tabletop sources.
One major asset is the fact that meanwhile real-time data analysis can be provided at TELBE making use of multi-thread technology.

Keywords: Real-time data analysis; Terahertz; pulse-resolve arrival time monitor

  • Open Access Logo Poster
    FELBE/TELBE User Workshop 2019, 13.-15.05.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-29952
Publ.-Id: 29952


Towards the Development of FPGA-Based High-Speed Data Acquisition and Online Analysis System at MHz Repetition Rate: Proposals and Major Tradeoffs

Bawatna, M.; Green, B. W.; Kovalev, S.; Deinert, J.-C.

Pulse-resolved data acquisition and online analysis is a key ingredient in modern accelerator-based light sources because of the ever-increasing demands in data quality (e.g. signal-to-noise ratios, time resolution). Accelerator-based light sources, in particular those based on linear accelerators, are intrinsically less stable than lasers or other more conventional light sources because of their large scale. In order to achieve optimal data quality the properties of each light pulse need to be detected and implemented into the analysis of each respective experiment. Such schemes are of particular advantage in 4th generation light sources based on super-conducting radiofrequency (SRF) technology, since here the combination of pulse-resolved detection schemes with high-repetition-rates is particularly fruitful. In this case pulse-to-pulse instabilities can be utilized to perform studies of multi-dimensional parameter dependencies on very short timescales making particularly the operation of user facilities much more efficient. A unique high-rep-rate pulse-resolved arrival time monitor has been developed at the high-field high-repetition-rate THz user facility TELBE as a demonstrator for the European XFEL and routinely operates up to a repetition rate of 100 kHz in user experiments providing, among other things, a timing precision of few 10 femtoseconds. In this contribution we will outline how this existing scheme shall be upgraded based on FPGA technology so that it allows operation at MHz repetition rates and sub femtosecond timing precision. An architecture based on Field Programmable Gate Array (FPGA) technology will allow online analysis of the measured data at MHz repetition rate and will decrease the amount of data throughput and the required disk capacity for storing the data by orders of magnitude. Implementation of several novel purpose-built CMOS line array detector will enable to perform arrivaltime measurements at MHz repetition rates.

Keywords: Pulse-resolved arrival time monitor; MHz repetition rates; Terahertz; sub femtosecond timing precision

  • Open Access Logo Lecture (Conference)
    The 9th Workshop on Longitudinal Electron Bunch Diagnostics, 20.-23.02.2019, TU Dortmund, Germany

Permalink: https://www.hzdr.de/publications/Publ-29951
Publ.-Id: 29951


Pulse-resolved Data Acquisition System for THz Pump Laser Probe Experiments at TELBE using Super-radiant Terahertz Sources

Bawatna, M.; Green, B. W.; Deinert, J.-C.; Kovalev, S.; Knodel, O.; Spallek, R.; Cowan, T.

The terahertz (THz) frequency range lies between the frequency range of radio and infrared. The development of suitable detectors, detection techniques, and sources for this frequency range has much interest over the past decade. THz pulses of sufficient strength that act as an excitation of dynamics in the matter have only been available, due to the development in 4th generation light sources based on superconducting radiofrequency (SRF) technology. In the THz pump laser probe experiments the electric or magnetic field in the THz pump pulse acts as the excitation of dynamics in the matter. Ultra-short laser pulses then probe this dynamic in turn. In this contribution, we will outline the pulse-resolved data acquisition scheme of the TELBE user facility based on the characterization of a new class of accelerator-based light sources, which provide a unique combination of high pulse energies and high repetition rates.

Keywords: Ultra fast Science; High-speed Data Acqusition (DAQ) System; Terahertz; High repetition rates

  • Open Access Logo Contribution to proceedings
    2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), 16.-18.07.2019, Bochum, Germany
    2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), IEEE: IEEE Xplore, 978-1-7281-0936-7/19, 142-144
    DOI: 10.1109/IMWS-AMP.2019.8880116

Permalink: https://www.hzdr.de/publications/Publ-29950
Publ.-Id: 29950


Design and Development of High-Speed Data Acquisition System and Online Data Processing with a Heterogeneous FPGA/GPU Architecture

Bawatna, M.; Deinert, J.-C.; Knodel, O.; Kovalev, S.; Spallek, R.

The superradiant THz sources at TELBE facility is based on the new class of accelerator-driven terahertz (THz) radiation sources that provide high repetition rates up to 13 MHz, and flexibility of tuning the THz pulse form. The THz pulses are used for the excitation of materials of interest, about two orders of magnitude higher than state-of-the-art tabletop sources. Time-resolved experiments can be performed with a time resolution down to 30 femtoseconds (fs) using the novel pulse-resolved Data Acquisition (DAQ) system. However, the increasing demands in improving the flexibility, data throughput, and speed of the DAQ systems motivate the integration of reconfigurable processing units close to the new detectors to accelerate the processing of tens of GigaBytes of data per second. In this paper, we introduce our online ultrafast DAQ system that uses a GPU platform for real-time image processing, and a custom high-performance FPGA board for interfacing the image sensors and provide a continuous data transfer.

Keywords: Online Data Acquisition System; MHz Repetition Rates; Ultrafast; bunch diagnostics; Field Programmable Gate Array

  • Open Access Logo Contribution to proceedings
    The 39th International Free Electron Laser Conference (FEL2019), 18.08.-25.11.2019, Hamburg, Germany
    Proceedings of the 39th International Free Electron Laser Conference (FEL2019), JACoW: JACoW, 978-3-95450-210-3, 510-512
    DOI: 10.18429/JACoW-FEL2019-WEP081

Permalink: https://www.hzdr.de/publications/Publ-29949
Publ.-Id: 29949


On the Use of Statistical Entropy Analysis as Assessment Parameter for the Comparison of Lithium-Ion Battery Recycling Processes

Velázquez-Martinez, O.; van den Boogaart, K. G.; Lundström, M.; Santasalo-Aarnio, A.; Reuter, M.; Serna-Guerrero, R.

The principle of the circular economy is to reintroduce end-of-life materials back into the economic cycle. While reintroduction processes, for example, recycling or refurbishing, undoubtedly support this objective, they inevitably present material losses or generation of undesired by-products. Balancing losses and recoveries into a single and logical assessment has now become a major concern. The present work broadens the use of relative statistical entropy and material flow analysis to assess the recycling processes of two lithium-ion batteries previously published in the literature. Process simulation software, that is, HSC Sim®, was employed to evaluate with a high level of accuracy the performance of such recycling processes. Hereby, this methodology introduces an entropic association between the quality of final recoveries and the pre-processing stages, that is, shredding, grinding, and separation, by a parameter based on information theory. The results demonstrate that the pre-processing stages have a significant impact on the entropy value obtained at the final stages, reflecting the losses of materials into waste and side streams. In this manner, it is demonstrated how a pre-processing system capable of separating a wider number of components is advantageous, even when the final quality of refined products in two different processes is comparable. Additionally, it is possible to observe where the process becomes redundant, that is, where processing of material does not result in a significant concentration in order to take corrective actions on the process. The present work demonstrates how material flow analysis combined with statistical entropy can be used as a parameter upon which the performance of multiple recycling processes can be objectively compared from a material-centric perspective.

Keywords: material flow analysis; relative statistical entropy; circular economy; lithium-ion batteries; LIB recycling; process simulation

Permalink: https://www.hzdr.de/publications/Publ-29948
Publ.-Id: 29948


The energy needed to concentrate minerals from common rocks: the case of copper ore

Palacios, J.-L.; Abadias Llamas, A.; Valero, A.; Valero, A.; Reuter, M.

A way to assess today's mineral patrimony is to evaluate how much mining energy is saved today because of having concentrated mines instead of finding the minerals dispersed throughout the crust. This can be assessed through the so-called exergy replacement costs (ERC), which are a measure of the exergy required to extract and concentrate minerals from barerock. Previous studies evaluated such exergy using a theoretical approach. In this paper, from a mineral processing point-of-view through a model developed with HSC Chemistry 9.4.1, we calculated the energy needed to concentrate copper from common rocks at average crustal concentrations. In the model, current state-of-the-art technologies for copper concentration were considered. The results were then compared to the theoretical value obtained before for the ERC of copper and helped to update it. The updated ERC value is of one order of magnitude greater than the original one. This difference in magnitude enhances, even more, the issue of ore grade decline in terms of the associated spiraling energy required for mining. It also reveals the importance of valuing properly the mineral heritage of nations and the effort that should be placed for increasing secondary metal production.

Keywords: Copper; Mining energy; Ore grade decline Thanatia; Exergy replacement cost

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-29947
Publ.-Id: 29947


Producing metals from common rock: the case of gold

Palacios, J.-L.; Abadias Llamas, A.; Valero, A.; Valero, A.; Reuter, M.

The depletion of the mineral capital is a topic of concern because the worldwide demand for minerals is rapidly increasing. Moreover, since the energy consumption increases as ore grades decline, there is growing stress on energy resources and the environment associated with mining activities. The energy costs associated with the exhaustion of mineral deposits is ruled by the entropy law through a negative logarithmic pattern, in which as the ore grade tends to zero, the energy tends to infinity. This study analyzes through a model developed in HSC Chemistry software, the energy that would be required to produce gold from common bare rock. In this way, we evaluate the maximum energy consumption with current technologies, to obtain gold at the final ore grade, i.e., when all mineral deposits were completely exhausted until reaching crustal concentration. The final theoretical concentration of gold is assumed to be that of the model of Thanatia, which is a resource exhausted Earth with the most abundant minerals found at crustal concentrations. The results are then compared to theoretical values obtained in previous studies for gold and serve to update with a more accurate methodology, the so-called thermodynamic rarity of minerals, as a way to assess the avoided mining energy for having minerals con- centrated in mines and not dispersed throughout the crust. This then serves to assess the mineral capital and its degradation velocity from a thermodynamic point of view.

Keywords: Mineral processing Gold; Crust; Thanatia; Exergy replacement cost Thermodynamic rarity

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  • Secondary publication expected

Permalink: https://www.hzdr.de/publications/Publ-29946
Publ.-Id: 29946


Linking NRP2 with EMT and chemoradioresistance in bladder cancer

Schulz, A.; Gorodetska, I.; Behrendt, R.; Fuessel, S.; Erdmann, K.; Foerster, S.; Datta, K.; Mayr, T.; Muders, M.; Dubrovska, A.

Neuropilin-2 (NRP2) is a prognostic indicator for reduced survival in bladder cancer (BCa) patients. Together with its major ligand, vascular endothelial growth factor (VEGF)-C, NRP2 expression is a predictive factor for treatment outcome in response to radiochemotherapy in BCa patients who underwent transurethral resection. Therefore, we investigated the benefit of combining cisplatin-based chemotherapy with irradiation treatment in the BCa cell line RT112 exhibiting or lacking endogenous NRP2 expression in order to evaluate NRP2 as potential therapeutic target. We have identified a high correlation of NRP2 and the Glioma-associated oncogene family zinc finger 2 (GLI2) transcripts in the cancer genome atlas (TCGA) cohort of BCa patients and a panel of 15 human BCa cell lines. Furthermore, we used in vitro BCa models to show the transforming growth factor-beta 1 (TGFb1)-dependent regulation of NRP2 and GLI2 expression levels. Since NRP2 was shown to bind TGFb1, associate with TGFb receptors and enhance TGFb1 signaling, we evaluated downstream signaling pathways using an epithelial to mesenchymal (EMT)-assay in combination with a PCR profiling array containing 84 genes related to EMT. Subsequent target validation in NRP2 knockout and knockdown models revealed secreted phosphoprotein 1 (SPP1/OPN/Osteopontin) as a downstream target positively regulated by NRP2.

Keywords: Keywords: bladder cancer; Neuropilin-2 (NRP2); Glioma-Associated Oncogene Family Zinc Finger 2 (GLI2); Secreted Phosphoprotein 1 (SPP1); Osteopontin (OPN); Epithelial to Mesenchymal Transition (EMT); RT112; J82

Permalink: https://www.hzdr.de/publications/Publ-29945
Publ.-Id: 29945


The importance of viscous and interfacial forces in the hydrodynamics of the Top-Submerged-Lance furnace

Obiso, D.; Kriebitzsch, S.; Reuter, M.; Meyer, B.

The purpose of this work is to focus on the hydrodynamics of a Top-Submerged-Lance (TSL) smelting furnace, understanding how liquid properties and operational parameters act on key factors of a TSL process, such as splashing, mixing, mass transfer area, and bubble development. A deep knowledge of all those aspects is needed since they all influence the smelting reaction rates; hence the efficiency of the reactor. The characterization and scaling of the TSL gas injection are commonly based on the modified Froude number, the ratio of dynamic and gravitational forces. Detailed literature research reveals a potential weakness of this approach, since it does not consider the effects of viscosity and surface tension. To investigate this question an extensive parametric study was performed applying computational fluid dynamics to cold and non-reactive flows, which provided a broad overview of the physics of the flow. The analysis was performed on fluid dynamic properties (liquid density, liquid viscosity, surface tension) and operational variables (gas volume flow, lance immersion depth). The coupled Level Set—Volume of Fluid model, available in the commercial solver ANSYS FluentÒ, was used to resolve the gas–liquid interface in the multiphase flow. The results of the work underscore the significance of the viscous and interfacial forces for gas injection in smelting slags, confirming the incompleteness of applying only the Froude number to describe such flows.

Permalink: https://www.hzdr.de/publications/Publ-29942
Publ.-Id: 29942


A Critical Review of Lithium-Ion Battery Recycling Processes from a Circular Economy Perspective

Velázquez-Martínez, J. V.; Santasalo-Aarnio, A.; Reuter, M.; Serna-Guerrero, R.

Lithium-ion batteries (LIBs) are currently one of the most important electrochemical energy storage devices, powering electronic mobile devices and electric vehicles alike. However, there is a remarkable difference between their rate of production and rate of recycling. At the end of their lifecycle, only a limited number of LIBs undergo any recycling treatment, with the majority go to landfills or being hoarded in households. Further losses of LIB components occur because the the state-of-the-art LIB recycling processes are limited to components with high economic value, e.g., Co, Cu, Fe, and Al. With the increasing popularity of concepts such as “circular economy” (CE), new LIB recycling systems have been proposed that target a wider spectrum of compounds, thus reducing the environmental impact associated with LIB production. This review work presents a discussion of the current practices and some of the most promising emerging technologies for recycling LIBs. While other authoritative reviews have focused on the description of recycling processes, the aim of the present was is to offer an analysis of recycling technologies from a CE perspective. Consequently, the discussion is based on the ability of each technology to recover every component in LIBs. The gathered data depicted a direct relationship between process complexity and the variety and usability of the recovered fractions. Indeed, only processes employing a combination of mechanical processing, and hydro- and pyrometallurgical steps seemed able to obtain materials suitable for LIB (re)manufacture. On the other hand, processes relying on pyrometallurgical steps are robust, but only capable of recovering metallic components.

Keywords: circular economy; recycling processes; lithium-ion battery

Permalink: https://www.hzdr.de/publications/Publ-29941
Publ.-Id: 29941


The simulation-based analysis of the resource efficiency of the circular economy – the enabling role of metallurgical infrastructure

Bartie, N. J.; Abadias Llamas, A.; Heibeck, M.; Fröhling, M.; Reuter, M.

Process metallurgy is a key enabler and the heart of the Circular Economy (CE). This paper shows the state-of-the-art approach to understanding the resource efficiency of very large-scale CE systems. Process simulation permits system-wide exergy analysis also linked to environmental footprinting. It is shown that digital twins of large CE systems can be created and their resource efficiencies quantified. This approach provides the basis for detailed estimation of financial expenditures as well as high-impact CE system innovation. The cadmium telluride (CdTe) photovoltaic technology life cycle, which brings several metal infrastructures into play, is studied. The results show that considerable work remains to optimise the CdTe system. Low exergy efficiencies resulting specifically from energy-intensive processes highlight areas with the greatest renewables-based improvement potential. This detail sheds light on the true performance of the CE and the inconvenient truth that it cannot be fully realised but only driven to its thermodynamic limits.

Keywords: Circular economy; exergy; life cycle assessment; metallurgy; photovoltaics; resource efficiency; sustainability; digital twin

Permalink: https://www.hzdr.de/publications/Publ-29940
Publ.-Id: 29940


Simulation-based exergy analysis of large circular economy systems: Zinc production coupled to CdTe photovoltaic module life cycle

Abadias Llamas, A.; Bartie, N. J.; Heibeck, M.; Stelter, M.; Reuter, M.

The second law of thermodynamics (2LT) helps to quantify the limits as well as the resource efficiency of the circular economy (CE) in its transformation of resources, which include materials, energy or water, into products and residues, some of which will be irreversibly lost. Furthermore, material and energy losses will also occur, as well as the residues and emissions that are generated have an environmental impact. Identifying the limits of circularity of large-scale CE systems, i.e. flowsheets, is necessary to understand the viability of the CE. With this deeper understanding, the full social, environmental and economic sustainability can be explored. Exergy dissipation, a measure of resource consumption, material recoveries and environmental impact indicators together provide a quantitative basis for designing a resource efficient CE system. Unique and very large simulation models, linking up to 223 detailed modelled unit operations, over 860 flows and 30 elements and all associated compounds apply this thermoeconomic (exergy-based) methodology showing (i) the resource efficiency limits, in terms of material losses and exergy dissipation of the CdTe photovoltaic (PV) module CE system (i.e. from ore to metal production, PV module production, and end- of-life recycling the original metal into the system again), and (ii) the analysis of the zinc processing subsystem of the CdTe PV system, for which the material recovery, resource consumption and environmental impacts of the different processing routes were evaluated and the most resource-efficient alternative to minimize the residue production during zinc production was selected. The paper also quantifies the key role that metallurgy plays in enabling sustainability. Therefore, it highlights the criticality of the metallurgical infrastructure to the CE, above and beyond simply focusing on the criticality of the elements.

Keywords: Exergy; Thermoeconomics; Circular economy; Geometallurgy, Process simulation; Digital twin; Sustainability; Jarosite; CdTe photovoltaic (PV) modules

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  • Secondary publication expected from 01.03.2021

Permalink: https://www.hzdr.de/publications/Publ-29939
Publ.-Id: 29939


Towards Real-time Data Processing using FPGA Technology for High-speed Data Acquisition System at MHz Repetition Rates

Bawatna, M.; Arnold, A.; Green, B. W.; Deinert, J.-C.; Kovalev, S.

Accelerator-based light sources, in particular, those based on linear accelerators, are intrinsically less stable than lasers or other more conventional light sources be-cause of their large scale. In order to achieve optimal data quality, the properties of each light pulse need to be de-tected and implemented into the analysis of each experi-ment. Such schemes are of particular advantage in 4th gen-eration light sources based on superconducting radiofre-quency (SRF) technology, since here the combination of pulse -resolved detection schemes with high -repetition-rate is particularly fruitful. Implementation of several different pur pose -built CMOS linear array detector will enable to perform arrival-time measurements at MHz repetition rates. An architecture based on FPGA technology will al-low an online analysis of the measured data at MHz repe-tition rate and will decrease the amount of data throughput and disk capacity for storing the data by orders of magni-tude. In this contribution, we will outline how the pulse-resolved data acquisition scheme of the TELBE user facil-ity shall be upgraded to allow operation at MHz repetition rates and sub-femtosecond timing precision.

Keywords: Real-Time Data Processing; High-speed Data Acquisition System; High Repetition Rates

  • Open Access Logo Contribution to proceedings
    The 19th International Conference on RF Superconductivity (SRF2019), 23.-30.06.2019, Dresden, Germany
    Proceedings of SRF 2019, JACoW: JACoW, 978-3-95450-211-0, 907-912
    DOI: 10.18429/JACoW-SRF2019-THP029

Permalink: https://www.hzdr.de/publications/Publ-29938
Publ.-Id: 29938


Modelling ASTRID-Like Sodium-Cooled Fast Reactor with Serpent DYN3D Code Sequence

Rydlewicz, W.; Fridman, Emil; Shwageraus, E.

This study explores the feasibility of applying the Serpent-DYN3D sequence to the analysis of Sodium-cooled Fast Reactors (SFRs) with complex core geometries, such as the ASTRID-like design. The core is characterised by a highly heterogeneous configuration and was likely to challenge the accuracy of the Serpent-DYN3D sequence. It includes axially heterogeneous fuel assemblies, non-uniform fuel assembly heights and large sodium plena. Consequently, the influence of generation and correction methods of various homogenised, few-group cross-sections (XS) on the accuracy of the full-core nodal diffusion DYN3D calculations is presented. An attempt to compare the approximate time effort spent on models preparation against the accuracy of the result is made. Results are compared to reference full-core Serpent MC (Monte Carlo) solutions. Initially, XS data was generated in Serpent using traditional methods (2D single assemblies and 2D super-cells). Full core calculations and MC simulations offered a moderate agreement. Therefore, XS generation with 2D fuel-reflector models and 3D single assembly models was verified. Super-homogenisation (SPH) factors for XS correction were applied. In conclusion, the performed work suggests that Serpent-DYN3D sequence could be used for the analysis of highly heterogeneous SFR designs similar to the studied ASTRID-like, with an only small penalty on the accuracy of the core reactivity and radial power distribution prediction. However, the XS generation route would need to include the correction with SPH factors and generation of XS with various MC models, for different core regions. At a certain point, there are diminishing returns to using more complex XS generation methods, as the accuracy of full-core deterministic calculations improves only slightly, while the time effort required increases significantly.

Keywords: Group constant generation; Serpent; DYN3D; Monte Carlo; ASTRID

  • Contribution to proceedings
    Physics of Reactors PHYSOR 2020, 29.03.-02.04.2020, Cambridge, United Kingdom, 978-1-5272-6447-2

Permalink: https://www.hzdr.de/publications/Publ-29937
Publ.-Id: 29937


Case study of bilayered spin-1/2 square lattice compound VO(HCOO)2 · (H2O)

Guchhait, S.; Arjun, U.; Anjana, P. K.; Sahoo, M.; Thirumurugan, A.; Medhi, A.; Scurschii, I.; Koo, B.; Sichelschmidt, J.; Schmidt, B.; Baenitz, M.; Nath, R.

We present the synthesis and a detailed investigation of structural and magnetic properties of polycrystalline VO(HCOO)2 · (H2O) by means of x-ray diffraction, magnetic susceptibility, high-field magnetization, heat capacity, and electron-spin-resonance measurements. The compound crystallizes in an orthorhombic structure with space group Pcca. The crystal lattice features distorted VO6 octahedra connected via HCOO linkers (formate anions), forming a two-dimensional square lattice network with a bilayered structure. Analysis of magnetic susceptibility, high-field magnetization, and heat capacity data in terms of the frustrated square lattice model unambiguously establish the quasi-two-dimensional nature of the compound with nearest-neighbor interaction J1/kB ≃ 11.7 K and next-nearest-neighbor interaction J2/k ≃ 0.02 K. A Néel antiferromagnetic ordering sets in at TN ≃ 1.1 K. The ratio θCW/TN ≃ 10.9 reflects excellent two-dimensionality of the spin-lattice in the compound. A strong in-plane anisotropy is inferred from the linear increase of TN with magnetic field, consistent with the structural data.

Permalink: https://www.hzdr.de/publications/Publ-29936
Publ.-Id: 29936


Evaluation of the ESFR End of Cycle State and Detailed Spatial Distributions of Reactivity Coefficients

Davies, U.; Margulis, M.; Shwageraus, E.; Fridman, E.; Garcia-Herranz, N.; Jimenez-Carrascosa, A.; Cabellos, O.; Gregg, R.

The ESFR-SMART project is the latest iteration of research into the behaviour of a commercial-size SFR core throughout its lifetime. As part of this project the ESFR core has been modelled by a range of different reactor physics simulation codes at its end of cycle state, and the important safety relevant parameters evaluated. These parameters are found to agree well between the different codes, giving good confidence in the results.
A detailed mapping of the local sodium void worth is also performed due to the problems associated with the positive void coefficient seen in large SFR designs. The local void worth maps show that the use of zone-wise coefficients replicates the important reactivity feedbacks, with a trend towards conservatism.

Keywords: ESFR; sodium-cooled fast reactor; spatial reactivity coefficients; sodium void worth

  • Contribution to proceedings
    Physics of Reactors PHYSOR 2020, 29.03.-02.04.2020, Cambridge, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-29935
Publ.-Id: 29935


One- and three-dimensional quantum phase transitions and anisotropy in Rb2CuMo3O12

Hayashida, S.; Blosser, D.; Povarov, K. Y.; Yan, Z.; Gvasaliya, S.; Ponomaryov, O.; Zvyagin, S.; Zheludev, A.

Single crystal samples of the frustrated quasi-one-dimensional quantum magnet Rb2Cu2Mo3O12 are investigated by magnetic, thermodynamic, and electron spin resonance (ESR) measurements. Quantum Phase transitions between the gapped, magnetically ordered, and fully saturated phases are observed. Surprisingly, the former has a distinctive three-dimensional character, while the latter is dominated by one-dimensional Quantum spin fluctuations. The entire H-T phase diagram is mapped out and found to be substantially anisotropic. In particular, the lower critical fields differ by over 50% depending on the direction of applied field, while the upper ones are almost isotropic, as is the magnetization above saturation. The ESR spectra are strongly dependent on field orientation and point to a helical structure with a rigidly defined spin rotation plane.

Permalink: https://www.hzdr.de/publications/Publ-29933
Publ.-Id: 29933


Bioflotation of sulfides in sea water: Sailing towards up-scaling the process

Luque Consuegra, G.

Halophilic bacteria were tested in microflotation experiments with minerals pyrite and chalcopyrite and in 1 litre batch flotation experiments with mafic complex sulphide mineral from El teniente mine. Results in microflotation experiments show that Halomonas sp. depresses pyrite from 80% floated pyrite to 10% floated pyrite in single mineral microflotation experiments and slightly improves the flotation of chalcopyrite in single mineral microflotation experiments. It is notable to mention that in these experiments, no lime or pH modifier was used to alter the pH of artificial sea water (ASW), leading to milder flotation conditions which could be potentially beneficial in large scale flotation processes. Due to these results, flotation experiments in 1L were performed on a core sample from El Teniente mine with halophilic bacteria as pyrite biodepressant instead of lime. Results from the XRD and MLA from the batch flotation experiments will be displayed in the presentation at the IBS 2019 in Fukuoka, Japan.

Keywords: Bioflotation; Biodepression; Pyrite; Halophilic Bacteria

  • Lecture (Conference)
    International Biohydrometallurgy Symposium Fukuoka, 20.-23.10.2019, Fukuoka, Japan

Permalink: https://www.hzdr.de/publications/Publ-29932
Publ.-Id: 29932


Halophilic bacteria as potential pyrite bio-depressants in Cu-Mo bioflotation

Luque Consuegra, G.; Kutschke, S.; Rudolph, M.; Pollmann, K.

Five halophilic bacteria have been studied as potential pyrite biodepressants. Microflotation experiments, as well as hydrophobicity and adhesion experiments were performed in order to assess the potential of these bacteria in the sulfide flotation process. It was shown that bacteria with hydrophobic properties in the Microbial Adhesion To Hydrocarbons (MATH) test adhere to pyrite and that Halomonas boliviensis and Halomonas sp. adhere to chalcopyrite in artificial sea water medium. Selective pyrite biodepression was greatly enhanced in the presence of Halobacillus sp. and Halomonas sp., and Halomonas boliviensis whilst chalcopyrite flotation was unaffected and in fact, enhanced by Halobacillus sp., Marinobacter spp. and Marinococcus sp. showing that the potential of this family of bacteria is yet to be untapped and could be an interesting development in sulfide bioflotation/biodepression processes.

Keywords: Halophilic bacteria; bioflotation; biodepression; pyrite; chalcopyrite; biobeneficiation

Permalink: https://www.hzdr.de/publications/Publ-29931
Publ.-Id: 29931


Effect of background electrolyte composition on the formation of Th(IV) nanoparticles on mica (001)

Neumann, J.; Qiu, C.; Hellebrandt, S.; Eng, P.; Skanthakumar, S.; Steppert, M.; Soderholm, L.; Stumpf, T.; Schmidt, M.

Actinides are known to form nanoparticles (NP), which may enhance[1] or decrease radionuclide mobility in the environment. Understanding these processes on the molecular level is therefore of particular interest for a reliable safety assessment for nuclear waste repositories. Previous results showed a strong and unusual influence of the background electrolyte composition on Th sorption on the mica (001) basal plane based on surface x-ray diffraction (SXD) data. Uptake was shown to be significantly lower (~0.04 Th/AUC; AUC = 46.72 Ų, the area of the mica (001) unit cell) for NaClO4 solution compared to NaCl (0.4 Th/AUC). An exceptional high coverage was detected for LiClO4 (4.9 Th/AUC) and surprisingly intermediate sorption occurs for KClO4 (~0.1 Th/AUC) under otherwise identical solution conditions.[2,3] The measured Th coverage from LiClO4 medium far exceeds the amount needed for surface charge compensation (0.25 Th/AUC), which suggests the formation of Th NP.[3] The mechanism of the reaction remains unclear, for instance whether the reaction occurs at the interface or in solution and if anion and cation effect occur independently. We applied SXD as well as electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) and in situ atomic force microscopy (AFM) to address these questions. ESI-TOF-MS measurements show no NP formation or other electrolyte influence in solution over a broad concentration range of Th in all media, which proofs the processes happen on the mica surface. From Cl- media higher coverages are found for LiCl (8.8 Th/AUC) and KCl (3.6 Th/AUC) compared to Na (0.4 Th/AUC), confirming the trend observed with perchlorates. All samples with Cl- electrolytes show higher coverages than the corresponding ClO4- samples, which confirms two independent effects for the electrolyte cation and anion. In situ AFM images show the Th-NP to have a variable lateral size and a height of a few nanometers. For higher Th(IV) concentrations the formation of Th-nanochains is observed. In the suggested mechanism the formation of Th NP occurs on the mica surface in a first step and the particles move along the surface in a second step to form band like structures of up to several hundred nanometer length. Formation of Thnanochains occurs at lower Th concentrations in the presence of LiCl (0.5 mM) compared to NaCl (1 mM). The findings suggest that the electrolyte cation influences oligomerization at the mineral-water-interface.
References:
[1] A. Kersting, Nature, 1999, 397, 56-59.
[2] M. Schmidt, Geochim. Et Cosmochim. Acta. 2015, 165, 280-293.
[3] M. Schmidt, Geochim. Et Cosmochim. Acta. 2012, 88, 66-76.

Keywords: Sorption; Thorium; Nanoparticles; Surface X-ray Diffraction; Background Electrolyte

  • Poster
    GDCh Fachgruppentagung Nuklearchemie, 25.-27.09.2019, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29930
Publ.-Id: 29930


Radionuclide sorption in heterogeneous systems: Form model mineral oxides to complex rock

Schierz, A.; Stockmann, M.; Jordan, N.; Foerstendorf, H.; Steudtner, R.; Bok, F.; Brendler, V.

The fate of radionuclides in natural rocks is governed by their sorption reactions onto heterogeneous systems. Fundamental process understanding of the retardation mechanisms is crucial in the long-term safety assessment of nuclear waste repositories.
The “Component Additivity” (CA) approach is widely used to model radionuclide sorption onto rocks or soils in a realistic manner. This bottom up approach is based on the principle that the sorption in a complex material is determined by competitive sorption effects from the individual minerals. In the context of repository safety assessment the CA approach is used in the smart Kd concept, which is developed for complex geochemical transport models to describe the radionuclide migration in the far-field of a repository more realistically [1].
In this work, batch sorption experiments of radionuclides, e.g. Np(V) and U(VI) onto mixtures of different mineral oxides, such as iron oxides, silicium dioxide, manganese oxides were performed varying the ratio of mineral oxides, solid-liquid-ratios and geochemical conditions. Vibrational (IR) and luminescence spectroscopy (TRLFS) were performed to identify sorbed species and to gain mechanistic understanding of the radionuclide sorption processes. Surface complexation parameters (such as surface protolysis and complex formation constants) of single minerals and mixtures thereof were derived, namely from titration and batch sorption experiments.
Finally, the experimental results were compared with results obtained from sorption predictions to verify the robustness and applicability of the CA approach. Based on the results obtained, estimations on the applicability of the CA approach for radionuclide sorption processes are presented.

  • Poster
    GDCh, Jahrestagung der Fachgruppe Nuklearchemie 2019, 25.-27.09.2019, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-29929
Publ.-Id: 29929


Radionuclide sorption in heterogeneous systems: From model mineral oxides to complex rocks

Schierz, A.; Stockmann, M.; Jordan, N.; Foerstendorf, H.; Steudtner, R.; Bok, F.; Brendler, V.

The fate of radionuclides in natural rocks is governed by their sorption reactions onto heterogeneous systems. Fundamental process understanding of the retardation mechanisms is crucial in the long-term safety assessment of nuclear waste repositories.
The “Component Additivity” (CA) approach is widely used to model radionuclide sorption onto rocks or soils in a realistic manner. This bottom-up approach is based on the principle that the sorption in a complex material is determined by competitive sorption effects from the individual minerals. In the context of repository safety assessment the CA approach is used in the smart Kd-concept, which is developed for complex geochemical transport models to describe the radionuclide migration in the far-field of a repository more realistically [1].
In this work, batch sorption experiments of radionuclides, e.g. Np(V) and U(VI) onto mixtures of different mineral oxides, such as iron oxides, silicium dioxide, manganese oxides were performed varying the ratio of mineral oxides, solid-liquid-ratios and geochemical conditions. Vibrational (IR) and luminescence spectroscopy (TRLFS) were performed to identify sorbed species and to gain mechanistic understanding of the radionuclide sorption processes. Surface complexation parameters (such as surface protolysis and complex formation constants) of single minerals and mixtures thereof were derived, namely from titration and batch sorption experiments.
Finally, the experimental results were compared with results obtained from sorption predictions to verify the robustness and applicability of the CA approach. Based on the results obtained, a first estimation on the applicability of the CA approach for radionuclide sorption processes is presented.
[1] Stockmann et al. (2017), Chemosphere 187, 277-285.

Keywords: Sorption

  • Poster
    Goldschmidt2019, 18.-23.08.2019, Barcelona, Spain

Permalink: https://www.hzdr.de/publications/Publ-29928
Publ.-Id: 29928


Effect of Background Electrolyte Composition on the Interfacial Formation of Th(IV) Nanoparticles

Neumann, J.; Qiu, C.; Hellebrandt, S.; Eng, P.; Skanthakumar, S.; Steppert, M.; Soderholm, L.; Stumpf, T.; Schmidt, M.

Understanding actinide nanoparticle (NP) formation and its influence on their mobility in ecosystems is essential for the reliable safety assessment of nuclear waste repositories. Previous surface x-ray diffraction (SXD) results showed a strong and unusual influence of the background electrolyte composition on Th sorption on the mica (001) basal plane.
Uptake was shown to be significantly lower (0.04 Th/AUC; AUC = 46.72 Å2, area of mica (001) unit cell) for NaClO4 solution compared to NaCl (0.4 Th/AUC). An exceptionally high coverage was detected for LiClO4 (4.9 Th/AUC), which far exceeds the amount needed for surface charge compensation (0.25 Th/AUC), suggesting the formation of Th-NP. However, it remained unclear, if the reaction occurs at the interface or in solution and if anion and cation effect occur independently. We applied SXD as well as electrospray-ionization time-offlight mass spectrometry (ESI-TOF-MS) and in situ AFM to address these questions. ESI-TOF-MS measurements show no influence on solution speciation, indicating the processes happen on the mica surface. In all media, only monomers are observed. From Cl- media higher coverages are found for LiCl (8.8 Th/AUC) and KCl (3.6 Th/AUC) compared to NaCl (0.4 Th/AUC), confirming the trend observed with perchlorates and the occurrence of two independent effects for the electrolyte cation and anion. In situ AFM images show the Th-NP to have variable lateral size and a height of a few nanometers. For higher Th(IV) concentrations the formation of Th nanochains is observed. In the suggested mechanism the formation of Th-NP occurs on the mica surface. In a first step, Th is adsorbed on the surface, where large local concentrations lead to the formation of Th-NP in some media. These particles move along the surface in a second step to form band-like structures of up to several hundred nanometer length.

Keywords: Sorption; Thorium; Nanoparticles; Surface X-ray Diffraction; Background electrolyte

  • Lecture (Conference)
    Goldschmidt Konferenz 2019, 18.-23.08.2019, Barcelona, Spanien

Permalink: https://www.hzdr.de/publications/Publ-29927
Publ.-Id: 29927


New insights into 99Tc(VII) removal by pyrite: A spectroscopic approach

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

99Tc(VII) uptake by synthetic pure pyrite was studied in a wide pH range from 3.5 to 10.5 using batch experiments at 21°C combined with scanning electron microscopy (SEM), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and Raman microscopy. We found that pyrite removes Tc quantitatively from solution (log Kd = 5.0 ± 0.1) within one day at pH ≥ 5.5. At pH < 5.5 the uptake process is slower, leading to 98% Tc removal (log Kd = 4.5 ± 0.1) after 35 days. The slower Tc uptake was explained by higher pyrite solubility under acidic conditions. After two months in contact with oxygen at pH 6 and 10, Tc was neither re-oxidized nor re-dissolved. XAS showed that the uptake mechanism involves the reduction from Tc(VII) to Tc(IV) and subsequent inner-sphere complexation of Tc(IV)-Tc(IV) dimers onto a Fe oxide like hematite at pH 6, and Tc(IV) incorporation into magnetite via Fe(III) substitution at pH 10. Calculations of Fe speciation under the experimental conditions predict the formation of hematite at pH < 7.5 and magnetite at pH > 7.5, explaining the formation of the two different Tc species depending on the pH. XPS spectra showed the formation of TcSx at pH 10, being a small fraction of a surface complex, potentially a transient phase in the total redox process.

Permalink: https://www.hzdr.de/publications/Publ-29925
Publ.-Id: 29925


Freestanding and positionable microwave-antenna device for magneto-optical spectroscopy experiments

Hache, T.; Vaňatka, M.; Flajšman, L.; Weinhold, T.; Hula, T.; Ciubotariu, O.; Albrecht, M.; Arkook, B.; Barsukov, I.; Fallarino, L.; Hellwig, O.; Faßbender, J.; Urbánek, M.; Schultheiß, H.

Modern spectroscopic techniques for the investigation of magnetization dynamics in micro- and nano- structures or thin films use mostly microwave antennas which are directly fabricated on the sample by means of electron-beam-lithography (EBL). Following this approach, every magnetic structure on the sample needs its own antenna, resulting in additional EBL steps and layer deposition processes. We demonstrate a new device for magnetization excitation that is suitable for optical and non-optical spectroscopic techniques. By patterning the antenna on a separated flexible glass cantilever and insulating it electrically, we solved the be- fore mentioned issues. Since we use flexible transparent glass as a substrate, optical spectroscopic techniques like Brillouin-light-scattering microscopy (μBLS), time resolved magneto-optical Kerr effect measurements (TRMOKE) or optical detected magnetic resonance (ODMR) measurements can be performed at visible laser wavelengths. As the antenna is detached from the sample it can be freely positioned in all three dimensions to get access to all desired magnetic sample structures, while being brought in close contact with the sample for an effective excitation. We show the functionality of these antennas using μBLS. We compare with thermally excited magnons to show the enhancement of the signal by a factor of about 400 demonstrating the high impact of the magnetization excitation by the antenna. Moreover, we show the possibility to characterize yttrium iron garnet thin films by doing optical ferromagnetic resonance (FMR) experiments allowing for the characterization of magnetic properties spatially resolved. Additionally, we show the spatial excitation profile of the antenna by measuring the magnetization dynamics in two dimensions. Furthermore, injection-locking of spin Hall nano-oscillators could be shown.

Keywords: magnetism; magnetization dynamics; spin Hall; spin waves; microwave; antenna; yttrium iron garnet; CoFeB; spin Hall nano-oscillators; optical FMR; antenna device; radio frequency; solid state physics; physics; experimental physics; injection locking; phase locking

  • Poster
    DPG-Frühjahrstagung der Sektion Kondensierte Materie, 31.03.-05.04.2019, Universität Regensburg, Deutschland
  • Physical Review Applied 13(2020)5, 054009
    DOI: 10.1103/PhysRevApplied.13.054009

Permalink: https://www.hzdr.de/publications/Publ-29920
Publ.-Id: 29920


Determination of electron effective mass in InN by cyclotron resonance spectroscopy

Fang, X.; Zheng, F.; Drachenko, O.; Zhou, S.; Zheng, X.; Chen, Z.; Wang, P.; Ge, W.; Shen, B.; Feng, J.; Wang, X.

We report the determination of electron effective mass in InN by using cyclotron resonance (CR) spectroscopy. To avoid the influence of sapphire substrate on CR measurements, InN epilayer with low residual electron concentration of 5 × 1017 cm−3 was grown on silicon substrate. Together with analyzing the effect of non-parabolic band structure, we derive that the isotropy c-plane electron effective mass of InN epilayer is 0.050±0.002 m0 and 0.058±0.002 m0 at temperatures of 4.2 and 50 K, respectively, which is in good agreement with our theoretical predication of the effective mass near the Γ point.

Keywords: Cyclotron resonance spectroscopy; Effective mass; InN

Permalink: https://www.hzdr.de/publications/Publ-29918
Publ.-Id: 29918


Two types of axisymmetric helical magnetorotational instability in rotating flows with positive shear

Mamatsashvili, G.; Stefani, F.; Hollerbach, R.; Rüdiger, G.

We reveal and investigate a type of linear axisymmetric helical magnetorotational instability which is capable of destabilizing viscous and resistive rotational flows with radially increasing angular velocity, or positive shear. This instability is double-diffusive by nature and is different from the more familiar helical magnetorotational instability, operating at positive shear above the Liu limit, in that it works instead for a wide range of the positive shear when (i) a combination of axial and azimuthal magnetic fields is applied and (ii) the magnetic Prandtl number is not too close to unity. We study this instability first with radially local Wentzel-Kramers-Brillouin (WKB) analysis, deriving the scaling properties of its growth rate with respect to Hartmann, Reynolds, and magnetic Prandtl numbers. Then we confirm its existence using a global stability analysis of the magnetized flow confined between two rotating coaxial cylinders with purely conducting or insulating boundaries and compare the results with those of the local analysis. From an experimental point of view, we also demonstrate the presence of this instability in a magnetized viscous and resistive Taylor-Couette flow with positive shear for such values of the flow parameters, which can be realized in upcoming experiments at the DRESDYN facility. Finally, this instability might have implications for the dynamics of the equatorial parts of the solar tachocline and dynamo action there, since the above two necessary conditions for the instability to take place are satisfied in this region. Our global stability calculations for the tachocline-like configuration, representing a thin rotating cylindrical layer with the appropriate boundary conditions—conducting inner and insulating outer cylinders—and the values of the flow parameters, indicate that it can indeed arise in this case with a characteristic growth time comparable to the solar cycle period.

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Permalink: https://www.hzdr.de/publications/Publ-29917
Publ.-Id: 29917


Hierarchy of double-time correlations

Queißer, F.; Schützhold, R.

The hierarchy of correlations is an analytical approximation method which allows us to study non-equilibrium phenomena in strongly interacting quantum many-body systems on lattices in higher dimensions. So far, this method was restricted to equal-time correlators ⟨A ^ μ (t)B ^ ν (t)⟩ . In this work, we generalize this method to double-time correlators ⟨A ^ μ (t)B ^ ν (t ′ )⟩ , which allows us to study effective light cones and Green functions and to incorporate finite initial temperatures.

Permalink: https://www.hzdr.de/publications/Publ-29916
Publ.-Id: 29916


Boltzmann relaxation dynamics of strongly interacting spinless fermions on a lattice

Queißer, F.; Schützhold, R.; Schreiber, S.; Kratzer, P.

Motivated by the recent interest in non-equilibrium phenomena in quantum many-body systems, we study strongly interacting fermions on a lattice by deriving and numerically solving quantum Boltzmann equations that describe their relaxation to thermodynamic equilibrium.The derivation is carried out by inspecting the hierarchy of correlations within the framework of the 1/Z-expansion. Applying the Markov approximation, we obtain the dynamic equations for the distribution functions. Interestingly, we find that in the strong-coupling limit, collisions between particles and holes dominate over particle-particle and hole-hole collisions -- in stark contrast to weakly interacting systems. As a consequence, our numerical simulations show that the relaxation time scales strongly depend on the type of excitations (particles or holes or both) that are initially present.

Permalink: https://www.hzdr.de/publications/Publ-29915
Publ.-Id: 29915


Doublon bottleneck in the ultrafast relaxation dynamics of hot electrons in 1T-TaS_2

Queißer, F.; Schützhold, R.; Avigo, I.; Zhou, P.; Ligges, M.; Rossnagel, K.; Bovensiepen, U.

Employing time-resolved photoelectron spectroscopy we analyze the relaxation dynamics of hot electrons in the charge density wave / Mott material 1T-TaS_2. At 1.2 eV above the Fermi level we observe a hot electron lifetime of 12 +- 5 fs in the metallic state and of 60 +- 10 fs in the broken symmetry ground state - a direct consequence of the reduced phase space for electron-electron scattering determined by the Mott gap. Boltzmann equation calculations which account for the interaction of hot electrons in a Bloch band with a doublon-holon excitation in the Mott state provide insight into the unoccupied electronic structure in the correlated state.

Permalink: https://www.hzdr.de/publications/Publ-29914
Publ.-Id: 29914


Stability of a Flow Under Electromagnetic Forcing in a Cylindrical Vessel

Jüstel, P.; Röhrborn, S.; Schindler, F.; Stefani, F.

We investigate the flow excited by electromagnetic forcing in a unit aspect ratio Rayleigh-Bénard cylinder. Flow structure and velocities dependent on AC frequency and coil current amplitude have been analysed. The unstable impinging jet flow bears interesting features, and a possible stochastic resonance is still under investigation.

Keywords: electromagnetic; forcing; flow stability; impinging jet; stochastic resonance

  • Poster
    N2 Event 2019, 13.11.2019, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-29913
Publ.-Id: 29913


Environment induced pre-thermalization in the Mott-Hubbard model

Queißer, F.; Schützhold, R.

Via the hierarchy of correlations, we study the strongly interacting Fermi-Hubbard model in the Mott insulator state and couple it to a Markovian environment which constantly monitors the particle numbers \hat n_\mu^\uparrow and \hat n_\mu^\downarrow for each lattice site \mu. As expected, the environment induces an imaginary part \gamma (i.e., decay rate) of the quasi-particle frequencies \omega_{\mathbf{k}}\to\omega_{\mathbf{k}}-i\gamma and tends to diminish the correlations between lattice sites. Surprisingly, the environment does also steer the state of the system on intermediate time scales \mathcal{O}(1/\gamma) to a pre-thermalized state very similar to a quantum quench (i.e., suddenly switching on the hopping rate J). Full thermalization occurs via local on-site heating and takes much longer.

Permalink: https://www.hzdr.de/publications/Publ-29912
Publ.-Id: 29912


Low-energy electron irradiation induced synthesis of molecular nanosheets: An influence of the electron beam energy

Neumann, C.; Wilhelm, R. A.; Küllmer, M.; Turchanin, A.

Aromatic self-assembled monolayers (SAMs) can be cross-linked into molecular nanosheets  carbon nanomembranes (CNMs)  via low-energy electron irradiation. Due to their favorable mechanical stability and tunable functional properties, they possess a high potential for various applications including nanosensors, separation membrane for osmosis or energy conversion devices. Despite this potential, the mechanistic details of the electron irradiation induced cross-linking process still need to be understood in more detail. Here we studied the cross-linking of 4'-nitro-1,1 ́-biphenyl-4-thiol SAM on gold. The SAM samples were irradiated with different electron energies ranging from 2.5 to 100 eV in ultra-high vacuum and subsequently analysed by complementary techniques. We present results obtained via spectroscopy and microscopy characterization by high-resolution X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction with micrometre sized electron beams (LEED) and low-energy electron microscopy (LEEM). To demostrate the formation of CNMs, the formed two-dimensional molecular materials were transferred onto grids and oxidized wafer and analyzed by optical, scanning electron (SEM) and atomic force microscopy (AFM). We found a strong energy dependence for the cross section for the cross-linking process, which rates decrease exponentially towards lower electron energies by about four orders of magnitude. We conduct a comparative analysis of the cross sections for the C-H bond scission via electron impact ionization and dissociative electron attachment and find out that these different ionization mechnisms are responsible for the variation of the cross-linking cross section with electron energy.

Permalink: https://www.hzdr.de/publications/Publ-29910
Publ.-Id: 29910


Dynamically assisted nuclear fusion

Queißer, F.; Schützhold, R.

We consider deuterium-tritium fusion as a generic example for general fusion reactions. For initial kinetic energies in the keV regime, the reaction rate is exponentially suppressed due to the Coulomb barrier between the nuclei, which is overcome by tunneling. Here, we study whether the tunneling probability could be enhanced by an additional electromagnetic field, such as an x-ray free electron laser (XFEL). We find that the XFEL frequencies and field strengths required for this dynamical assistance mechanism should come within reach of present-day or near-future technology.

Permalink: https://www.hzdr.de/publications/Publ-29909
Publ.-Id: 29909


Charge calibration of DRZ scintillation phosphor screens

Schwinkendorf, J.-P.; Bohlena, S.; Couperus Cabadağ, J. P.; Ding, H.; Irman, A.; Karsch, S.; Köhler, A.; Krämer, J. M.; Kurz, T.; Kuschel, S.; Osterhoff, J.; Schaper, L. F.; Schinkel, D.; Schramm, U.; Zarini, O.; D'Arcy, R.

As a basic diagnostic tool, scintillation screens are employed in particle accelerators to detect charged particles. In extension to the recent revision on the calibration of scintillation screens commonly applied in the context of plasma acceleration [T. Kurz et al., Rev. Sci. Instrum. 89 (2018) 093303], here we present the charge calibration of three DRZ screens (Std, Plus, High), which promise to offer similar spatial resolution to other screen types whilst reaching higher conversion efficiencies. The calibration was performed at the Electron Linac for beams with high Brilliance and low Emittance (ELBE) at the Helmholtz-Zentrum Dresden-Rossendorf, which delivers picosecond-long beams of up to 40 MeV energy. Compared to the most sensitive screen, Kodak BioMAX MS, of the aforementioned recent investigation by Kurz et al., the sample with highest yield in this campaign, DRZ High, revealed a 30% increase in light yield. The detection threshold with these screens was found to be below 10 pC/mm². For higher charge-densities (several nC/mm²) saturation effects were observed. In contrast to the recent reported work, the DRZ screens were more robust, demonstrating higher durability under the same high level of charge deposition.

Keywords: Beam-line instrumentation (beam position and profile monitors; beam-intensity moni-tors; bunch length monitors); Detector alignment and calibration methods (lasers, sources, particle-beams); Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators); Wake-field acceleration (laser-driven, electron-driven)

Permalink: https://www.hzdr.de/publications/Publ-29908
Publ.-Id: 29908


Antibacterial activity of selenium nanoparticles studied by calorimetry, flow cytometry and electron microscopy

Schäfer, S.; Fahmy, K.; Merroun, M. L.

Nanoparticles (NPs) are of growing interest for various applications due to their unique properties, such as elevated surface-to-volume-ratio and variability of composition surface features and charge. Moreover, certain metal NPs possess antimicrobial activity and are therefore considered as an alternative to common antibiotics to overcome the recently emerging issue of bacterial resistance against common antibiotics [1].
Silver (Ag) NPs are well-studied concerning their antimicrobial activity and already applied in medicine and household products. However, cellular interaction mechanisms and consequent toxicity are not entirely elucidated. It is proposed, that NPs either interact with the cell membrane via intermolecular interactions, such as charge-charge interactions or intracellular accumulation. Once interacting with the cell extra- or intracellularly, NPs release reactive oxygen species and metal ions, which subsequently damage the cell membrane and affect enzymatic activity, ultimately leading to cell death. [1]
Besides AgNPs, selenium (Se) NPs exhibit prominent antimicrobial activity, without being studied into more detail [2,3]. In our approach, gram-positive and gram-negative bacterial strains are chosen their putatively differing response to the metal NPs based on differing cell wall compositions. Calorimetric studies of differentially-coated Se NPs exhibited a decrease in growth rate of the bacterial model strains, indicating their antimicrobial activity. To further investigate the cytotoxicity, the influence on reactive oxygen species and enzymatic activity, fluorescence-based flow cytometry is being performed. Furthermore, electron microscopy is exploited to localize the NPs and to elucidate putative metal ion release.

References:
[1] Brandelli et al. (2017) Springer Int Publ 337-363.
[2] Piacenza et al. (2017) Microb Biotechnol 10, 804-818.
[3] Srivastava & Mukhopadhyay (2015) Bioprocess Biosyst Eng 38, 1723-1730.

  • Open Access Logo Lecture (Conference)
    Goldschmidt Conference, 18.-23.08.2019, Barcelona, Spain

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Permalink: https://www.hzdr.de/publications/Publ-29907
Publ.-Id: 29907


Antibacterial activity of selenium nanoparticles studied by calorimetry, flow cytometry and electron microscopy

Schäfer, S.; Fahmy, K.; Merroun, M. L.

Nanoparticles are of growing interest for various applications due to their unique properties, such as elevated surface-to-volume-ratio and variability of material, surface features, and charge. Therefore, they are applied in industry as catalysts and are investigated concerning their feasibility in drug delivery [1]. Moreover, certain metal nanoparticles possess antimicrobial activity and are therefore considered as an alternative to common antibiotics [2]. Especially due to increasing bacterial resistance against common antibiotics and the lack of the development of novel ones, metal nanoparticles attracted interest in biomedical research.
Silver nanoparticles are well-studied concerning their antimicrobial activity and already applied in medicine and household products. However, cellular interaction mechanisms and consequent toxicity are not entirely elucidated. It is proposed, that nanoparticles either interact with the cell membrane via intermolecular interactions, such as charge-charge interactions or penetrate it. Thus, the size and charge of the nanoparticles are the main properties to influence interaction and antimicrobial activity. Once interacting with the cell extra- or intracellularly, nanoparticles release reactive oxygen species and metal ions, which subsequently damage the cell membrane and affect enzymatic activity, consequently leading to cell death. [2]
Besides silver nanoparticles, selenium nanoparticles exhibit prominent antimicrobial activity, without being studied into more detail [3,4]. In our approach, gram-positive (Lysinibacillus sphaericus) and gram-negative (Stenotrophomonas bentonitica) bacterial strains are chosen due to their different cell wall composition and their putatively differing response to the metal nanoparticles. Calorimetric studies of BSA- and Chitosan-coated selenium nanoparticles exhibited a decrease in growth rate of the bacterial model strains, indicating their antimicrobial activity. To further investigate the cytotoxicity, influence of reactive oxygen species and enzymatic activity, the bacterial model strains are incubated with selenium nanoparticles with different surface coatings and charges and studied via fluorescence-based flow cytometry. Furthermore, electron microscopy is performed to characterize interaction mechanisms, to localize the nanoparticles and to elucidate putative metal ion release.

References:
[1] Faraji, A. H. & Wipf, P. Nanoparticles in cellular drug delivery. Bioorganic Med. Chem. 17, 2950–2962 (2009).
[2] Brandelli, A., Ritter, A. C. & Veras, F. F. in Metal Nanoparticles in Pharma 337–363 (Springer International Publishing, 2017). doi:10.1007/978-3-319-63790-7_1
[3] Piacenza, E. et al. Antimicrobial activity of biogenically produced spherical Se-nanomaterials embedded in organic material against Pseudomonas aeruginosa and Staphylococcus aureus strains on hydroxyapatite-coated surfaces. Microb. Biotechnol. 10, 804–818 (2017).
[4] Srivastava, N. & Mukhopadhyay, M. Green synthesis and structural characterization of selenium nanoparticles and assessment of their antimicrobial property. Bioprocess Biosyst. Eng. 38, 1723–1730 (2015).

  • Open Access Logo Lecture (Conference)
    Congreso Nacional de Microbiología, 01.-05.07.2019, Málaga, Spain

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Permalink: https://www.hzdr.de/publications/Publ-29906
Publ.-Id: 29906


Fractionation of geochemical twins (Zr/Hf, Nb/Ta and Y/Ho) and HREE-enrichment during magmatic and metamorphic processes in peralkaline nepheline syenites from Norra Kärr (Sweden).

Atanasova, P.; Marks, M. A. W.; Frenzel, M.; Gutzmer, J.; Krause, J.; Markl, G.

The Norra Kärr complex (Sweden) consists of deformed and metamorphosed peralkaline nepheline syenites that contain eudialyte-group minerals as the major host of high field strength elements and rare earth elements. Petrographic studies have revealed the presence of paragenetically distinct generations of eudialyte-group minerals and clinopyroxene of magmatic and metamorphic origin. In this study, we present the trace element characteristics of these different generations of rock-forming minerals in the three major lithological subunits of the Norra Kärr complex.
The trace element chemistry of eudialyte-group minerals mimic whole-rock compositions and display well-developed negative Eu-anomalies and strong Sr- and Ba-depletions in chondrite-normalized diagrams. They imply that the Norra Kärr rocks developed by intense fractional crystallization from an alkali basaltic parental magma. Our data also illustrate that eudialyte-group minerals do not significantly fractionate the geochemical twins Zr/Hf, Y/Ho and Nb/Ta during magmatic processes. In contrast, magmatic clinopyroxene shows a clear preference for Hf over Zr.
The transition from magmatic to metamorphic crystallization is clearly marked in the trace element chemistry of clinopyroxene by decreasing Zr/Hf and Y/Ho ratios. This accompanies the change in major element composition from aegirine sensu strictu to Al-aegirine. The transition from a magmatic to a metamorphic environment is also recorded by an increase of the rare earth element content of eudialyte-group minerals, especially the heavy rare earth elements. The exceptional enrichment of heavy rare earth elements in late metamorphic eudialyte may result from residual enrichment, whereby light rare earth elements were preferentially mobilized to form local secondary light rare earth-rich rinkite-group mineral assemblages.

Keywords: fractionation; geochemical twins; rare earth elements; clinopyroxene; eudialyte-group minerals; nepheline syenite

Permalink: https://www.hzdr.de/publications/Publ-29905
Publ.-Id: 29905


Comparison of Static and Dynamic 18F-FDG PET/CT for Quantification of Pulmonary Inflammation in Acute Lung Injury

Braune, A.; Hofheinz, F.; Bluth, T.; Kiss, T.; Wittenstein, J.; Scharffenberg, M.; Kotzerke, J.; Gama De Abreu, M.

PET imaging with 18F-FDG followed by mathematic modeling of the pulmonary uptake rate (Ki) is the gold standard for assessment of pulmonary inflammation in experimental studies of acute respiratory distress syndrome (ARDS). However, dynamic PET requires long imaging and allows the assessment of only 1 cranio-caudal field of view (∼15 cm). We investigated whether static 18F-FDG PET/CT and analysis of SUV or standardized uptake ratios (SURstat, uptake time-corrected ratio of 18F-FDG concentration in lung tissue and blood plasma) might be an alternative to dynamic 18F-FDG PET/CT and Patlak analysis for quantification of pulmonary inflammation in experimental ARDS.

Methods: ARDS was induced by saline lung lavage followed by injurious mechanical ventilation in 14 anesthetized pigs (29.5-40.0 kg). PET/CT imaging sequences were acquired before and after 24 h of mechanical ventilation. Ki and the apparent volume of distribution were calculated from dynamic 18F-FDG PET/CT scans using the Patlak analysis. Static 18F-FDG PET/CT scans were obtained immediately after dynamic PET/CT and used for calculations of SUV and SURstat Mean Ki values of the whole imaged field of view and of 5 ventro-dorsal lung regions were compared with corresponding SUV and SURstat values, respectively, by means of linear regression and concordance analysis. The variability of the 18F-FDG concentration in blood plasma (arterial input function) was analyzed.

Results: Both for the whole imaged field of view and ventro-dorsal subregions, Ki was linearly correlated with SURstat (r2 ≥ 0.84), whereas Ki-SUV correlations were worse (r2 ≤ 0.75). The arterial input function exhibited an essentially invariant shape across all animals and time points and can be described by an inverse power law. Compared with Ki, SURstat and SUV tracked the same direction of change in regional lung inflammation in 98.6% and 84.3% of measurements, respectively.


Conclusion: The Ki-SURstat correlations were considerably stronger than the Ki-SUV correlations. The good Ki-SURstat correlations suggest that static 18F-FDG PET/CT and SURstat analysis provides an alternative to dynamic 18F-FDG PET/CT and Patlak analysis, allowing the assessment of inflammation of whole lungs, repeated measurements within the period of 18F-FDG decay, and faster data acquisition. © 2019 by the Society of Nuclear Medicine and Molecular Imaging.

Keywords: Animal Imaging Image Processing PET/CT Radiotracer Tissue Kinetics Respiratory 18-F-FDG positron emission tomography pulmonary inflammation standard uptake value tumor-to-blood standard uptake ratio (SUR)

Permalink: https://www.hzdr.de/publications/Publ-29904
Publ.-Id: 29904


Metal deportment and ore variability of the Bolcana porphyry Au–Cu system (Apuseni Mts, Romania) – Implications for ore processing

Blannin, R.; Tusa, L.; Birtel, S.; Gutzmer, J.; Gilbricht, S.; Ivascanu, P.

The maiden resource estimate for the Bolcana gold-copper porphyry defines 381 Mt at 0.53 g/t gold and 0.18% copper. The early stage of exploration provides the perfect opportunity for the application of geometallurgical studies, to enable optimisation of future mine and plant operations. Quantitative mineralogy and microfabric characterisation of crushed material and thin sections from seven 40 m drill core intervals were accomplished by Scanning Electron Microscopy based Mineral Liberation Analysis, complemented by X-ray Powder Diffraction. The mineralogy of the studied samples is highly variable, depending on lithology, mineralisation and alteration. The main Cu-bearing mineral is chalcopyrite, predominantly occurring in B and C veins. At shallow depths, secondary bornite and covellite form rims around chalcopyrite. Primary bornite occurs at greater depths in the system. Native gold grains are typically <10 μm and hosted by chalcopyrite or, to a lesser extent, pyrite. Electron Probe Microanalysis on four samples determined that gold concentrations in solid solution in selected sulphide minerals are <100 ppm. Copper and associated gold should be recoverable by flotation of chalcopyrite. The recovery of free gold and gold associated with pyrite may require additional processing steps.

  • Open Access Logo Lecture (Conference)
    15th Biennial Meeting of the Society for Geology Applied to Mineral Deposits, 27.08.2019, Glasgow, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-29903
Publ.-Id: 29903


Metal deportment and ore variability of the Bolcana porphyry Au–Cu system (Apuseni Mts, Romania) – Implications for ore processing

Blannin, R.; Tusa, L.; Birtel, S.; Gutzmer, J.; Gilbricht, S.; Ivascanu, P.

The maiden resource estimate for the Bolcana gold-copper porphyry defines 381 Mt at 0.53 g/t gold and 0.18% copper. The early stage of exploration provides the perfect opportunity for the application of geometallurgical studies, to enable optimisation of future mine and plant operations. Quantitative mineralogy and microfabric characterisation of crushed material and thin sections from seven 40 m drill core intervals were accomplished by Scanning Electron Microscopy based Mineral Liberation Analysis, complemented by X-ray Powder Diffraction. The mineralogy of the studied samples is highly variable, depending on lithology, mineralisation and alteration. The main Cu-bearing mineral is chalcopyrite, predominantly occurring in B and C veins. At shallow depths, secondary bornite and covellite form rims around chalcopyrite. Primary bornite occurs at greater depths in the system. Native gold grains are typically <10 μm and hosted by chalcopyrite or, to a lesser extent, pyrite. Electron Probe Microanalysis on four samples determined that gold concentrations in solid solution in selected sulphide minerals are <100 ppm. Copper and associated gold should be recoverable by flotation of chalcopyrite. The recovery of free gold and gold associated with pyrite may require additional processing steps.

  • Open Access Logo Contribution to proceedings
    15th Biennial Meeting of the Society for Geology Applied to Mineral Deposits, 27.-30.08.2019, Glasgow, United Kingdom

Permalink: https://www.hzdr.de/publications/Publ-29902
Publ.-Id: 29902


Antiferromagnetic domain wall control via surface spin flop in fully tunable synthetic antiferromagnets with perpendicular magnetic anisotropy

Böhm, B.; Fallarino, L.; Pohl, D.; Rellinghaus, B.; Nielsch, K.; Kiselev, N. S.; Hellwig, O.

Antiferromagnetic (AF) domain walls have recently attracted revived attention, not only in the emerging field of AF spintronics, but also more specifically for offering fast domain wall velocities and dynamic excitations up to the terahertz frequency regime. Here, we introduce an approach to nucleate and stabilize an AF domain wall in a synthetic antiferromagnet (SAF). We present experimental and micromagnetic studies of the magnetization reversal in [(Co/Pt)X-1/Co/Ir]N-1(Co/Pt)X SAFs, where interface-induced perpendicular magnetic anisotropy (PMA) and AF interlayer exchange coupling (IEC) are completely controlled via the individual layer thicknesses within the multilayer stack. By combining strong PMA with even stronger AF-IEC, the SAF reveals a collective response to an external magnetic field applied normal to the surface, and we stabilize the characteristic surface spin-flop (SSF) state for an even number N of AF-coupled (Co/Pt)X-1/Co multilayer blocks. In the SSF state our system provides a well-controlled and fully tunable vertical AF domain wall, easy to integrate as no single-crystal substrates are required and with uniform two-dimensional magnetization in the film plane for further functionalization options, such as lateral patterning via lithography.

Permalink: https://www.hzdr.de/publications/Publ-29901
Publ.-Id: 29901


Unveiling Electronic Properties in Metal−Phthalocyanine-Based Pyrazine-Linked Conjugated Two-Dimensional Covalent Organic Frameworks

Mingchao, W.; Marco, B.; Wang, M.; Hung-Hsuan, L.; Bishnu, P. B.; Xiaocang, H.; Silvia, P.; Eike, B.; Pan, L.; Mingwei, C.; Mischa, B.; Heine, T.; Zhou, S.; Enrique, C.; Renhao, D.; Xinliang, F.

π-Conjugated two-dimensional covalent organic frameworks (2D COFs) are emerging as a novel class of electroactive materials for (opto)electronic and chemiresistive sensing applications. However, understanding the intricate interplay between chemistry, structure, and conductivity in π-conjugated 2D COFs remains elusive. Here, we report a detailed characterization for the electronic properties of two novel samples consisting of Zn− and Cu−phthalocyaninebased pyrazine-linked 2D COFs. These 2D COFs are synthesized by condensation of metal−phthalocyanine (M =Zn and Cu) and pyrene derivatives. The obtained polycrystalline-layered COFs are p-type semiconductors both with a band gap of ∼1.2 eV. A record device-relevant mobility up to ∼5 cm2/(V s) is resolved in the dc limit, which represents a lower threshold induced by charge carrier localization at crystalline grain boundaries. Hall effect measurements (dc limit) and terahertz (THz) spectroscopy (ac limit) in combination with density functional theory (DFT) calculations demonstrate that varying metal center from Cu to Zn in the phthalocyanine moiety has a negligible effect in the conductivity (∼5 × 10−7 S/cm), charge carrier density (∼1012 cm−3), charge carrier scattering rate (∼3 × 1013 s−1), and effective mass (∼2.3m0) of majority carriers (holes). Notably, charge carrier transport is found to be anisotropic, with hole mobilities being practically null in-plane and finite out-of-plane for these 2D COFs.

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Permalink: https://www.hzdr.de/publications/Publ-29900
Publ.-Id: 29900


Nonsaturating extreme magnetoresistance and large electronic magnetostriction in LuAs

Juraszek, J.; Bochenek, L.; Rudenko, A.; Hosen, M. M.; Daszkiewicz, M.; Wang, Z.; Wosnitza, J.; Henkie, Z.; Samsel-Czekala, M.; Neupane, M.

In the known topological semimetals, conventional charge carriers exist in addition to relativistic quasiparticles, and thus a disentangling of their conduction properties remains challenging. Here, we address an unsaturated extreme magnetoresistance (XMR) with a marked deviation from the semiclassical B2 behavior that is commonly credited to the presence of topologically protected electronic states. For the topologically trivial semimetal LuAs, we observe a nonsaturating XMR with a nonquadratic magnetic-field dependence gained up to nearly 60 T. Remarkably, this diamagnetic material exhibits a very large magnetostriction that provides solid evidence for a field-dependent variation of electron and hole concentrations. We show that an underlying strain-induced change in the charge-carrier densities can give rise to an unsaturated XMR even in a moderately imbalanced semimetal. Our finding is of importance as well for topological semimetals in which the number of conventional charge carriers can be continuously altered with increasing field, and hence some of their high-field properties may not necessarily reflect the presence of massless quasiparticles.

Permalink: https://www.hzdr.de/publications/Publ-29899
Publ.-Id: 29899


Bose-Einstein condensation of triplons close to the quantum critical point in the quasi-one-dimensional spin-1/2 antiferromagnet NaVOPO4

Mukharjee, P. K.; Ranjith, K. M.; Koo, B.; Sichelschmidt, J.; Baenitz, M.; Scurschii, I.; Inagaki, Y.; Furukawa, Y.; Tsirlin, A. A.; Nath, R.

Structural and magnetic properties of a quasi-one-dimensional spin-½ compound NaVOPO4 are explored by x-ray diffraction, magnetic susceptibility, high-field magnetization, specific heat, electron spin resonance, and 31P nuclear magnetic resonance measurements, as well as complementary ab initio calculations. Whereas magnetic susceptibility of NaVOPO4 may be compatible with the gapless uniform spin chain model, detailed examination of the crystal structure reveals a weak alternation of the exchange couplings with the alternation ratio α 󠆪≃ 0.98 and the ensuing zero-field spin gap Δ0/kB ≃ 2.4 K directly probed by field-dependent magnetization measurements. No long-range order is observed down to 50 mK in zero field. However, applied fields above the critical field Hc1 ≃ 1.6 T give rise to a magnetic ordering transition with the phase boundary TN ∝ (H – Hc1) 1/φ, where φ ≃ 1.8 is close to the value expected for Bose-Einstein condensation of triplons.With its weak alternation of the exchange couplings and small spin gap, NaVOPO4 lies close to the quantum critical point.

Permalink: https://www.hzdr.de/publications/Publ-29898
Publ.-Id: 29898


High Energy Lasers – embedded intelligence

Bock, S.; Püschel, T.; Gebhardt, R.; Helbig, U.; Schramm, U.

Workshop presentation on requirements for assistance on running high power lasers

  • Lecture (Conference)
    High Energy Lasers - Ideas & Future (HELIF), 05.05.2019, Split, Croatia

Permalink: https://www.hzdr.de/publications/Publ-29897
Publ.-Id: 29897


Characterization of measurement devices for temporal laser pulse contrast with high dynamic range

Püschel, T.; Herrmann, F. M.; Lötfering, J. J.; Gebhardt, R.; Helbig, U.; Toncian, T.; Schramm, U.; Bock, S.

We demonstrate a protocol for the absolute calibration of third-order autocorrelator (TO-AC) response to the temporal profile of a high contrast high power laser pulse based on either artificially generated coherent pre- and post-pulses or incoherent background. The dynamic range provided by the protocol exceeds more than eight orders of magnitude. For cross-calibration, the technique of self-referenced spectral interferometry with extended time excursion (SRSI-ETE) is used.

Keywords: Ultra-short high peak power lasers; contrast; SRSI-ETE; third-order autocorrelator

  • Poster
    Ultrafast Optics XII, 06.-11.10.2019, Bol, Brac, Croatia

Permalink: https://www.hzdr.de/publications/Publ-29896
Publ.-Id: 29896


Model Experiments for Flow Phenomena in Crystal Growth

Dadzis, K.; Pätzold, O.; Gerbeth, G.

The concept of a physical model experiment is introduced and discussed in the context of melt and gas flows in bulk crystal growth processes. Such experiments allow one to "extract" selected physical phenomena from the full complexity of a real crystal growth process and “transfer” them to material systems with an easier access for experimental measurements. Model experiments for the main techniques of melt growth are summarized in a literature review, and the applicability of the results to real crystal growth systems is analyzed. Recent examples of model experiments for melt and gas flows in Czochralski growth of silicon are used to demonstrate the state of the art and show the potential of such experiments to improve the understanding of complex multi-physical multi-scale phenomena occurring in every crystal growth process.

Keywords: crystal growth; melt flows; model experiments; numerical simulation

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Permalink: https://www.hzdr.de/publications/Publ-29894
Publ.-Id: 29894


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