Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

"Online First" included
Without submitted and only approved publications
Only approved publications

35836 Publications

Sub-threshold strangeness production measured with HADES

Kornakov, G.; Adamczewski-Musch, J.; Arnold, O.; Arnoldi-Meadows, B.; Belounnas, A.; Belyaev, A.; Biernat, J.; Blanco, A.; Blume, C.; Boehmer, M.; Bordalo, P.; Chlad, L.; Chudoba, P.; Ciepal, I.; Deveaux, C.; Dittert, D.; Dreyer, J.; Fabbietti, L.; Fateev, O.; Fonte, P.; Franco, C.; Friese, J.; Froehlich, I.; Galatyuk, T.; Garzon, J. A.; Gernhaeuser, R.; Gillitzer, A.; Golosov, O.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hoehne, C.; Holzmann, R.; Ierusalimov, A.; Ivanov, V.; Ivashkin, A.; Kaempfer, B.; Kajetanowicz, M.; Kampert, K.-H.; Kardan, B.; Khomyakov, V.; Koenig, I.; Koenig, W.; Korcyl, G.; Kornas, F.; Kotte, R.; Kozela, A.; Kubos, J.; Kugler, A.; Kunz, T.; Kurilkin, P.; Kushpil, V.; Ladygin, V.; Lalik, R.; Lebedev, A.; Linev, S.; Lopes, L.; Lorenz, M.; Lykasov, G.; Mahmoud, T.; Malakhov, A.; Markert, J.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Mikhaylov, V.; Morozov, S.; Muentz, C.; Naumann, L.; Nowakowski, K.; Parpottas, Y.; Patel, V.; Pauly, C.; Pechenov, V.; Pechenova, O.; Pereira, A.; Petousis, V.; Petukhov, O.; Pfeifer, D.; Pietraszko, J.; Prozorov, A. P.; Przygoda, W.; Pysz, K.; Ramos, S.; Ramstein, B.; Reshetin, A.; Ritman, L.; Rodriguez-Ramos, P.; Rost, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Silva, L.; Smyrski, J.; Sobiella, M.; Spataro, S.; Spies, S.; Strikhanov, M.; Stroebele, H.; Stroth, J.; Strzempek, P.; Svoboda, O.; Szala, M.; Taranenko, A.; Tlusty, P.; Traxler, M.; Troyan, A.; Tsertos, H.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wintz, P.; Wirth, J.; Wloch, B.; Zhilin, A.; Zinchenko, A.; Zumbruch, P.

At energies below sqrt(sNN) approximate to 2.55 GeV, strange quarks cannot be produced in binary nucleon-nucleon collisions because of the higher production threshold of the lightest hadrons carrying strangeness. Hence, the investigation of sub-threshold strangeness production in heavy-ion collisions is one of the most promising probes, to access the properties of the created system, as the missing energy must be provided by the latter one. For the first time, a nearly complete set of strange particles has been reconstructed in the 40% most central Au+Au collisions at sqrt(sNN) = 2.42 GeV. The data sample includes multi-differential representations of charged and neutral particles containing strangeness (K+,-,Ks 0, φ, Λ). To achieve a better understanding of strangeness production the properties of the short-lived resonances have to be investigated. The first steps in this direction are presented here, including the reconstruction of baryon resonances using a new iterative technique, comparison to microscopic transport model calculations and interpretation of the pion transverse momentum distribution.


Publ.-Id: 29153

Ferromagnetic (In,Ga,Mn)As films prepared by ion implantation and pulsed laser melting

Xu, C.; Wang, M.; Zhang, X.; Yuan, Y.; Zhou, S.

In the present work, we show the preparation of (In,Ga,Mn)As films with different Ga concentration by Mn ion implantation and pulsed laser melting. All films are confirmed to be well recrystallized by Rutherford backscattering spectrometry/channeling and to be ferromagnetic by magnetometry measurements, respectively. Their Curie temperatures depend on the Ga concentration. Our results show the perspective of ion implantation in the preparation of different III-Mn-V quaternary alloys as new members of diluted ferromagnetic semiconductors.

Keywords: Thin film; Ion implantation; Pulsed laser melting; III-V compounds


Publ.-Id: 29152

Coupled dissolution-precipitation reactive transport modeling at the pore scale

Karimzadeh, L.; Fischer, C.

Coupled dissolution-precipitation processes are of critical importance for the evolution of porosity and permeability in materials and for multiple applications, such as waste management, reservoir rocks, and corrosion. Here, we study the impact of saturation and fluid flow velocity with high spatial resolution, i.e., in the micrometer to submicrometer scale. Utilizing a time series of datasets of corroded crystal surfaces, collected using interferometry techniques, we analyze the impact of local fluid flow heterogeneity and resulting saturation variability. Systematically, the series of surface data is used (i) to constrain the initial topography for reactive transport modeling, and (ii) to compare the model vs. experimental results.
In this work, a reactive transport model is presented which simulates the complex chemical reaction of mineral dissolution/precipitation and subsequent pore-geometry evolution at a single pore scale [1]. We used the finite element package COMSOL Multiphysics® 5.4 for the simulation, utilizing the arbitary-Lagrangian Eulerian (ALE) method for the free-moving domain boundary.
Experimental and modeling studies have shown both the spatial [2] and temporal [3] heterogeneity of reaction rates and their impact on topography evolution at the pore scale. We expect an improved predictability of reactive transport modeling by using an approach combining the heterogeneities of surface reactivity and flow velocity at the pore scale.

[1] Karimzadeh, L., et al., 2018. Benchmark 3D reactive transport modelling of leaching of fractured calcareous sulfide ores, in: Lottermoser, B.G. (Ed.), Aachen International Mining Symposia (AIMS 2018), Aachen, Germany, p. 88 pp.
[2] Fischer, C., and Luttge, A., 2018, Pulsating dissolution of crystalline matter. PNAS 115.
[3] Fischer, C., Kurganskaya, I., and Luttge, A., 2018, Inherited control of crystal surface reactivity. Applied Geochemistry 91, 140.

  • Poster
    EGU General Assembly 2019, 08.-12.04.2019, Wien, Österreich

Publ.-Id: 29151

Improving fracture-flow models by experimental evidence from process tomography

Kulenkampff, J.; Karimzadeh, L.; Jankovsky, F.; Zuna, M.; Havlova, V.; Fischer, C.

Advective fluid flow transport controls the migration of radionuclides in fractured crystalline rocks. Thus, the
safety assessment of deep geological repositories in crystalline rocks relies critically on fracture flow properties
and the reliability of transport modelling approaches. Here, we focus on heterogeneity and complexity of transport
processes, typically of limited predictability. In order to tackle this issue, we suggest experimental observations by
using tomographic methods, as well as feedback with and improvement of existing transport modelling approaches.
As an example, tracer propagation through fractured crystalline rock cores from the Czech Republic (Bukov URL,
depth of 500 m below the surface), was studied in collaboration between HZDR (Germany) and UJV (Czech
Republic). Spatiotemporal data of the tracer concentration during conservative transport are based on positron
emission tomography (PET), and the underlying fracture structure was characterized by microCT-imaging. The latter
yields a structural model for reactive transport modelling. The PET data sequences provide (i) the validation of
existing simulation approaches, and (ii) serve as input or the parameterization of advanced simulation concepts.
First results underscore the outlined approach. In particular, the PET measurements clearly show preferential and
localized pathways, a feature of the process that significantly reduces the effect of interactions at the fracture
surface (and thus retention by adsorption); although repeat experiments are suggesting that the identified pathways
are not constant over the experimental periods.
As a consequence of the combined experimental and simulation approach, we expect (i) advanced model concepts
based on experimental insights and (ii) an improved understanding of reactive transport processes with a focus on
temporal heterogeneity of preferential pathways.

  • Poster
    EGU General Assembly 2019, 08.-12.04.2019, Wien, Österreich

Publ.-Id: 29150

Photoconductive germanium antenna emitting broadband THz pulses

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

The spectral range between 5 and 10 THz is hardly accessible for time-resolved THz spectroscopy due to strong phonon absorption in many polar materials utilized for the generation of THz transients. We demonstrate that non-polar germanium is a promising semiconductor for a realization of a photoconductive THz emitter with a continuous spectrum spanning well above 10 THz.

  • Invited lecture (Conferences)
    AES 2019, the 7th Advanced Electromagnetics Symposium, 24.-26.07.2019, Lisbon, Portugal

Publ.-Id: 29149

A correlation study of layer growth rate, thickness uniformity, stoichiometry, and hydrogen impurity level of ALD grown HfO2 thin films

Blaschke, D.; Munnik, F.; Grenzer, J.; Rebohle, L.; Zahn, P.; Schmidt, H.; Gemming, S.

Hafnium oxide was deposited from tetrakis(dimethylamino)hafnium (TDMAHf) and water by atomic layer deposition (ALD) on heated 400 Si wafers covered with native oxide in the temperature range from 100 C to 350 C. Optimized self-limiting ALD reaction and smallest hydrogen impurity level have been realized for a substrate temperature of 300 C. The stoichiometry of deposited films and hydrogen impurity level were measured by elastic recoil detection analysis. The hafnium to oxygen ratio showed the expected 1:2 value. Besides hydrogen, no other impurities could be detected.
Furthermore, a strong correlation between the growth rate per cycle (GPC), film uniformity and level of hydrogen impurities was observed. Based on this result, the easily accessible GPC can be used as a first indication for the hydrogen impurity level in ALD grown thin films.
Furthermore, the characterization of the crystal structure showed the appearance of some crystallites in an amorphous matrix already for a growth temperature of 250 C and a pure crystalline layer at a growth temperature of 350 C. The increased crystallinity with increasing growth temperature was attributed to a higher seed concentration and a constant crystal size.

Keywords: ALD; TDMAHf; HfO₂; growth rate per cycle; thickness uniformity; ERDA; H impurity level; GIXRD; AFM


Publ.-Id: 29148

Simulación numérica en pilas de combustible PEMFC tipo Air-Breathing

Weber, N.; Chaparro, A.; Ferreira Aparicio, P.

Der Vortrag gibt eine Übersicht über die Simulation von Luft atmenden Brennstoffzellen.

  • Lecture (others)
    Institutsseminar am CIEMAT, 24.04.2019, Madrid, Spanien

Publ.-Id: 29147

Maximizing magnetic field generation in high power laser–solid interactions

Huang, L.; Takabe, H.; Cowan, T.

In order to understand the transport of fast electrons within solid density targets driven by an optical high power laser, wehave numerically investigated the dynamics and structure of strong self-generated magnetic fields in such experiments.Here we present a systematic study of the bulk magnetic field generation due to the ponderomotive current, Weibel-likeinstability and resistivity gradient between two solid layers. Using particle-in-cell simulations, we observe the effect ofvarying the laser and target parameters, including laser intensity, focal size, incident angle, preplasma scale length, targetthickness and material and experimental geometry. The simulation results suggest that the strongest magnetic field isgenerated with laser incident angles and preplasma scale lengths that maximize laser absorption efficiency. The recentcommissioning of experimental platforms equipped with both optical high power laser and X-ray free electron laser(XFEL), such as European XFEL-HED, LCLS-MEC and SACLA beamlines, provides unprecedented opportunities toprobe the self-generated bulk magnetic field by X-ray polarimetry via Faraday rotation with simultaneous high spatialand temporal resolution. We expect that this systematic numerical investigation will pave the way to design and optimizenear future experimental setups to probe the magnetic fields in such experimental platforms

Keywords: laser–plasmas interaction; high energy density physics; X-ray free electron laser probi

  • Open Access Logo High Power Laser Science and Engineering 7(2019)e22
    Online First (2019) DOI: 10.1017/hpl.2019.9


Publ.-Id: 29146

Kinetic Simulations of Target Heating, Ionization and Micro-Explosion with High Intensity XFEL Beams

Huang, L.; Hartley, N.; Hau-Riege, S.; Inubushi, Y.; Kamimura, N.; Katagiri, K.; Kodama, R.; Kon, A.; Makita, M.; Matsuoka, T.; Nakajima, S.; Pikuz, T.; Rode, A.; Rohatsch, K.; Sagae, D.; Schuster, A.; Tono, K.; Lu, W.; Yabuuchi, T.; Ozaki, N.; Kraus, D.; Cowan, T.

High intensity X-ray Free Electron Lasers (XFEL) are an ideal tool to heat materials directly and isochorically, which can cause them to be modified and damaged irreversibly. During XFEL-matter interactions, the energy of an XFEL beam will be mainly absorbed by photoionization, creating numerous high-energy photo- and Auger electrons. Modelling this process is quite complex since both atomic physics and plasma physics are involved. Atomic collisional-radiative (CR) codes such as FLYCHK are widely used to simulate such processes. However, the CR codes typically assume local thermodynamic equilibrium (LTE) and are limited to zero dimension.
In order to understand the sample damaging mechanisms, we performed two-dimensional kinetic particle-in-cell simulations with radiation transport (PIC-RT) to retrieve the temporal processes of XFEL-matter interactions. The dynamics of XFEL-Matter interactions can roughly divide into three different time scales: 1) electron heating and photoionization by XFEL in ~ 10 fs ; 2) collisional heating and ionization by high-energy photo- and Auger electrons with several keV energy in tens of fs to sub-ps; and 3) collective hydrodynamic explosion driven by ~ TPa thermal pressure from ~100 fs to nanoseconds.
The simulation results are compared to our recent experiment that a variety of samples were irradiated by Japanese XFEL SACLA with intensities on the order of 10^20 W/cm^2. The post-analysis of the irradiated samples showed that large holes with radius sizes more than one order of magnitude higher than the XFEL spot were created for metallic samples. The hole size is also much larger than the stopping range of high energy electrons. According to our PIC-RT simulations, we attribute the generation of such large holes to the micro-explosion process. Kinect simulation of the hole generation with multiple time scales is also useful and complementary to understand the change of X-Ray diffraction pattern in the experiment that infers significant material structural change on femtosecond timescales.

Keywords: XFEL; Pump-Probe Experiment; Kinect Simulations; Radiation Transport

  • Lecture (Conference)
    SPIE Optics + Optoelectronics, 01.-04.04.2019, Prague, Czech Republic
    DOI: 10.1117/12.2520565

Publ.-Id: 29145

Uncertainty limits of range verification in proton therapy by means of prompt gamma-ray timing (PGT)

Werner, T.; Kögler, T.; Permatasari, F. F.; Petzoldt, J.; Römer, K.; Wagner, A.; Enghardt, W.; Pausch, G.

Range verification during clinical treatments is a key for further improving the precision and for reducing the normal-tissue toxicity of radiotherapy with proton beams. In spite of the breakthrough achieved with IBA’s knife-edge slit camera, capable of imaging single beam spots in pencil-beam scanning (PBS) treatment fractions delivered to cancer patients, there are ongoing activities aiming at systems distinguished by lower expense, lower weight, easier integration in the therapy facility, and potentially higher precision. In this context, OncoRay’s Prompt Gamma-Ray Timing (PGT) technology has been further explored with the focus on quantifying uncertainty contributions in potential clinical applications. Experimental data acquired in the treatment room of the University Proton Therapy Dresden (UPTD) during single pencil beam delivery to a polymethyl methacrylate (PMMA) target with arbitrary air cavities have been carefully analyzed. Besides the limited number of events the instable phase relation between proton-beam bunches and accelerating RF turned out to be the weakest point at the given facility. Technical means for monitoring this phase relation at a time scale of split seconds without touching the medical beamline are being developed and will be discussed in the paper. Altogether PGT could provide range verification with 3 mm accuracy at PBS spot level, if (at least) eight PGT detection units are deployed. Technically even a larger number of detectors could be arranged around the nozzle, which would further reduce the uncertainty.

Keywords: proton therapy; treatment verification; range verification; prompt gamma ray; prompt gamma-ray imaging; PGI; prompt gamma-ray timing; PGT

  • Lecture (Conference)
    2019 IEEE Nuclear Science Symposium and Medical Imaging Conference, 26.10.-02.11.2019, Manchester, Great Britain

Publ.-Id: 29144

Fast 2D laser-induced fluorescence spectroscopy mapping of rare earth elements in rock samples

Seidel, P.; Lorenz, S.; Heinig, T.; Zimmermann, R.; Booysen, R.; Beyer, J.; Heitmann, J.; Gloaguen, R.

Due to the rapidly increasing use of energy-efficient technologies, the need for complex materials containing rare earth elements (REEs) is steadily growing. The high demand for REEs requires the exploration of new mineral deposits of these valuable elements, as recovery by recycling is still very low. Easy-to-deploy sensors technologies featuring high sensitivity to REE are required to overcome limitations by traditional techniques such as X-ray fluorescence. We demonstrate the ability of laser-induced fluorescence (LIF) to detect REEs rapidly in relevant geological samples. We introduce two-dimensional LIF mapping to scan rock samples from two Namibian REE deposits and cross-validate the obtained results by employing mineral liberation analysis (MLA) and hyperspectral imaging (HSI). Technique-specific parameters, such as acquisition speed, spatial resolution, and detection limits, are discussed and compared to established analysis methods. We also focus on the attribution of REEs occurrences to mineralogical features, which may helpful for the further geological interpretation of the deposit. This study sets the basis for the development of a combined mapping sensor for HSI and 2D LIF measurements, which could be used for drill-core logging in REE exploration as well as in recovery plants.

Keywords: laser-induced fluorescence; rare earth elements; imaging sensor; reflectance spectroscopy; optical spectroscopy

Publ.-Id: 29143

Successful immunotherapy and irradiation in a HIV-positive patient with metastatic Merkel cell carcinoma

Linge, A.; Rauschenberg, R.; Blum, S.; Spornraft-Ragaller, P.; Meier, F.; Troost, E. G. C.

This case report presents a HIV-positive 60-year old male with Merkel cell carcinoma of his right forearm and pulmonary sarcoidosis, who, after excisions and irradiations of the primary tumour site and subsequent lymph node metastases developed distant metastases. He received radiotherapy to symptomatic mediastinal lymph node metastases followed by Doxorubicin and, after two cycles, by the PD-1 Inhibitor Pembrolizumab due to mixed response. Re-staging showed a para-mediastinal, radiotherapy-induced pneumonitis, which was treated by prednisolone due to clinical symptoms. In September 2017, the patient developed a solitary lymph node metastasis next to the right atrium, for which he received stereotactic radiotherapy. The systemic treatment with Pembrolizumab was replaced by the PD-L1 inhibitor Avelumab and is being continued since. The patient has been in complete remission for one year now and the HIV-infection is well-controlled.

Keywords: Merkel cell carcinoma; Avelumab; Immunotherapy; Pembrolizumab; Immune checkpoint Inhibition; Radiotherapy; HIV; Sarcoidosis

Publ.-Id: 29142

Implementierung von CT-basierten Schwächungskarten am PET/MRT für die Bestrahlungsplanung von Prostatakrebspatienten

Taeubert, L.; Pfaffenberger, A.; Berker, Y.; Beuthien-Baumann, B.; Hoffmann, A. L.; Troost, E. G. C.; Koerber, S. A.; Kachelrieß, M.; Gillmann, C.

Das Ziel der Einbindung von PSMA-PET/MRT-Daten in die Bestrahlungsplanung (RT) von Prostatakrebspatienten ist es, die Tumorabgrenzung zu verbessern und eventuell die
Dosisverschreibung zu individualisieren. Da diese Scans in Behandlungsposition aufgenommen werden müssen, ist eine Schwächungskorrektur für die RT-Positionierungshilfsmittel erforderlich. Die hier vorgestellte Methode implementiert CT-basierte Schwächungskarten von RT-Positionierungshilfsmitteln in die Rekonstruktion von PET/MRT-Bildern und wird anschließend hinsichtlich der Genauigkeit ihrer Schwächungskorrektur analysiert.

Material & Methode:
Eine RT-Tischplattenauflage (hausinterne Herstellung) wurde an einem CT (SOMATOM Definition Flash, Siemens) mit einer Röhrenspannung von 120 kV und einem effektiven Röhrenstrom von 320 mAs gescannt. Basierend auf den CT-Bildern wurde eine Schwächungskarte der RT-Tischplattenauflage berechnet. Anschließend wurde die RT-Tischplattenauflage auf den Patiententisch des PET/MRTs (Biograph mMR, Siemens) montiert. PET-Messungen mit (RT-Scan) und ohne (Referenzscan) RT-Tischplattenauflage wurden mithilfe eines aktiven, homogen gefüllten 68Ge-Phantoms (32 MBq, 10 Minuten Scanzeit) aufgenommen. Beide Scans wurden mit identischen Rekonstruktionsparametern rekonstruiert. Die Rekonstruktion des RT-Scans wurde mit (korrigiert) und ohne (unkorrigiert) Implementierung der Schwächungskarte der RT-Tischplattenauflage durchgeführt. Die PET-Aktivitäten der RT- und Referenzscans wurden verglichen, indem die Mittelwerte der ROIs im Abstand von 10 Schichten entlang des Phantoms in Längsrichtung ausgewertet wurden.

Tabelle 1 zeigt den Vergleich der gemessenen PET-Aktivitäten des unkorrigiertem und des korrigiertem RT-Scans mit dem Referenzscan. Der mittlere prozentuale Unterschied zwischen dem unkorrigierten RT- und dem Referenzscan beträgt 4,8%. Zwischen dem korrigierten RT- und dem Referenzscan wurde eine mittlere prozentuale Differenz von 0,5% ermittelt.

Die PET-Signalschwächung durch die RT-Tischplattenauflage ist mit durchschnittlich 5% klinisch relevant und kann mithilfe von CT-basierten Schwächungskarten erfolgreich korrigiert werden. Dieser Schritt ist Voraussetzung für die Integration von PET/MRT-Daten in die Bestrahlungsplanung.

  • Lecture (Conference)
    50. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik (DGMP) e. V., 18.-21.09.2019, Stuttgart, Deutschland

Publ.-Id: 29141

Midostaurin abrogates CD33-directed UniCAR and CD33-CD3 bispecific antibody therapy in acute myeloid leukemia

Fasslrinner, F.; Arndt, C.; Koristka, S.; Feldmann, A.; Altmann, H.; von Bonin, M.; Schmitz, M.; Bornhäuser, M.; Bachmann, M.

Combinatory therapeutic approaches of different targeted therapies in acute myeloid leukemia (AML) are currently under preclinical and early clinical investigation. To enhance anti-tumor effects, we combined tyrosine kinase inhibitor (TKI) Midostaurin and T cell-mediated immunotherapy directed against CD33. We show that clinically relevant concentrations of Midostaurin abrogate T cell-mediated cytotoxicity both after activation with bispecific antibodies (bsAbs) and chimeric antigen receptor (CAR) T cells. This information is of relevance for clinicians exploring T cell-mediated immunotherapy in early clinical trials. Given the profound inhibition of T cell functionality and anti-tumor activity, we recommend favoring specific fms-like tyrosine kinase 3 (FLT3) TKIs for further clinical testing of combinatory approaches with T cell-based immunotherapy.

Publ.-Id: 29140

T Cell Based Immunotherapy of Acute Myeloid Leukemia is Abrogated by the Tyrosine Kinase Inhibitor Midostaurin

Fasslrinner, F.; Arndt, C.; Koristka, S.; Feldmann, A.; Altmann, H.; von Bonin, M.; Schmitz, M.; Bornhäuser, M.; Bachmann, M.

Induction chemotherapy is currently the standard of care for treatment of acute myeloid leukemia (AML) with 5-year disease-free survival of 33%. Given the large proportion of non-responders and relapsed patients, novel adjuvant drugs are urgently needed. Especially, targeted therapies including small molecules and T cell based immunotherapies are under intensive preclinical and clinical investigation. The tyrosine kinase inhibitor Midostaurin recently received approval for treatment of FLT3-positive AML. In addition to chemotherapy, it significantly deepens remission rates and improves overall survival of patients. In light of future combinatorial approaches, simultaneous application of different targeted therapies should theoretically augment anti-tumor effects.

Therefore, we questioned whether Midostaurin could strengthen cytotoxic effector mechanisms of redirected switchable UniCAR T cells or bispecific antibody-redirected T cells against primary AML cells.

By performing in vitro co-cultivation assays with patient-derived AML cells, it was shown that Midostaurin concentrations ≥ 1 µM significantly impair the activation, proliferation, cytokine production and cytotoxicity of autologous and allogeneic T cells after engagement via bsAb or the UniCAR system. Data could be also verified in a solid tumor model.

At concentrations ranging between 0.1 and 10 M, it was shown that Midostaurin and its metabolites are indeed able to inhibit several components of the TCR signaling pathway including LcK, Zeta-chain-associated protein kinase 70 (ZAP-70), mitogen-activated protein kinase (MAPK) and Protein kinase C (PKC) in vitro. Therefore, we argue that the observed T cell inhibition by Midostaurin in our studies is caused by the inhibition of several of these kinases. This hypothesis is supported by the work of two individual research groups that were able to show synergistic effects by combining FLT3 selective TKIs with different T cell-based immunotherapies. Because Midostaurin through concentrations above ≥ 1 µM have been observed in earlier performed dose finding studies, we speculate that current standard Midostaurin therapy will inhibit T cell function in vivo.
In summary, our data underline that combination of Midostaurin and T cell-based immunotherapies in FLT3-positive AML patients is not recommended due to the suppressive effect of Midostaurin on T cells. Therefore, more selective TKI or other small molecules should be chosen to avoid impairment of T cell functions.

  • Poster
    1st European CAR T Cell Meeting, 14.-16.02.2019, Paris, France

Publ.-Id: 29139

Integriertes Management und Publikation von wissenschaftlichen Artikeln, Software und Forschungsdaten am Helmholtz-Zentrum Dresden-Rossendorf (HZDR)

Reschke, E.; Konrad, U.

Mit dem Ziel, das Publizieren von Artikeln, Forschungsdaten und wissenschaftlicher Software gemäß den FAIR-Prinzipien zu unterstützen, wurde am HZDR ein integriertes Publikationsmanagement aufgebaut. Insbesondere Daten- und Softwarepublikationen erfordern die Entwicklung bedarfsgerechter organisatorischer und technischer Strukturen ergänzend zu bereits sehr gut funktionierenden Services im Publikationsmanagement. In der Zusammenarbeit mit Wissenschaftlern des HZDR und internationalen Partnern in ausgewählten Projekten wurde der Bedarf an Unterstützung im Forschungsdatenmanagement analysiert. Darauf aufbauend wurde schrittweise ein integriertes System von Infrastrukturen und Services entwickelt und bereitgestellt. In einer seit Mai 2018 gültigen Data Policy wurden die Rahmenbedingungen und Regelungen sowohl für wissenschaftliche Mitarbeiter als auch für externe Messgäste definiert.
Zusammenfassend werden unsere Erfahrungen im integrierten Publikationsmanagement für Artikel, Forschungsdaten und Forschungssoftware vorgestellt. Es wird ein Ausblick auf die nächsten Schritte und Aufgaben gegeben und Aspekte der Integration im Kontext der europäischen und nationalen Forschungsorganisationen herausgearbeitet.

Keywords: Publikationsmanagement; Forschungsdaten; Forschungssoftware; publication management; research data; research software; FAIR; Open Access

  • Open Access Logo Contribution to proceedings
    WissKom2019: Forschungsdaten - Sammeln, sichern, strukturieren, 04.-06.06.2019, Jülich, Deutschland
    WissKom2019: Forschungsdaten - Sammeln, sichern, strukturieren. 8. Konferenz der Zentralbibliothek, Forschungszentrum Jülich, Jülich: Forschungszentrum Jülich, 978-3-95806-405-8, 167-177
  • Open Access Logo Invited lecture (Conferences)
    WissKom2019 – Forschungsdaten: Sammeln, sichern, strukturieren. 8. Konferenz der Zentralbibliothek, Forschungszentrum Jülich, 04.-06.06.2019, Jülich, Deutschland
    DOI: 10.13140/RG.2.2.14789.19683


Publ.-Id: 29138

X-ray radioscopic visualization of bubbly flows injected through a top submerged lance into a liquid metal

Akashi, M.; Keplinger, O.; Anders, S.; Shevchenko, N.; Reuter, M.; Eckert, S.

We present an experimental study on the formation and behaviour of a liquid metal bubbly flow arising from a downward gas injection through a top submerged lance (TSL). A visualization of the bubble dynamics was achieved by the X-ray radiography combined with high-speed imaging. The experiments were carried out in a parallelepiped container (144×144×12 mm3) using GaInSn, a ternary alloy that is liquid at room temperature. The gas flow rate Qgas was adjusted in a range between 0.033 and 0.1 l/s. Three different injection positions were considered with respect to the submergence depth L. X-ray images allow for a characterization of the flow regimes and provide the properties of the individual bubbles such as size, shape and trajectory. Formation and entrainment of smaller gas bubbles are observed at the free surface. These small bubbles can be trapped in the fluid for a long time by recirculation vortices. Bubbles size distributions are determined for different Qgas. The bubble detachment frequency is measured as a function of Qgas and L. The results are compared with previously published data for water. The X-ray radiography offers an effective method for determining the local void fraction and allows for an estimation of the bubble volume.

Keywords: Two phase flow; X-ray radiography; Top submerged lance


Publ.-Id: 29137

An oligo-His-tag of a targeting module does not influence its biodistribution and the retargeting capabilities of UniCAR T cells

Jureczek, J.; Bergmann, R.; Berndt, N.; Koristka, S.; Kegler, A.; Puentes-Cala, E.; Soto, J. A.; Arndt, C.; Bachmann, M.; Feldmann, A.

Recently, we established the controllable modular UniCAR platform technology to advance the efficacy and safety of CAR T cell therapy. The UniCAR system is composed of (i) target modules (TMs) and (ii) UniCAR armed T cells. TMs are bispecific molecules that are able to bind to the tumor cell surface and simultaneously to UniCAR T cells. For interaction with UniCAR T cells, TMs contain a peptide epitope sequence which is recognised by UniCAR T cells. So far, a series of TMs against a variety of tumor targets including against the prostate stem cell antigen (PSCA) were constructed and functionally characterised. In order to facilitate their purification all these TMs are expressed as recombinant proteins equipped with an oligo-His-tag. The aim of the here presented manuscript was to learn whether or not the oligo-His-tag of the TM influences the UniCAR system. For this purpose, we constructed TMs against PSCA equipped with or lacking an oligo-His-tag. Both TMs were compared side by side including for functionality and biodistribution. According to our data, an oligo-His-tag of a UniCAR TM has only little if any effect on its binding affinity, in vitro and in vivo killing capability and in vivo biodistribution.

Publ.-Id: 29136

Eulerian/Lagrangian formulation for the elasto-capillary deformation of a flexible fibre

Lecrivain, G.; Grein, T. B. P.; Yamamoto, R.; Hampel, U.; Taniguchi, T.

The capillary-induced bending of flexible fibres, a process also known as elasto-capillary deformation, is central to a variety of industrial and non-industrial applications, among which stand out textile flotation, stabilization of emulsions, micro-folding of elastic structures, and clogging of feather fibres by oil droplets. A consistent formulation for the direct numerical simulation of a flexible fibre interacting with a fluidic interface is presently suggested. The fibre is geometrically decomposed into a chain of spherical beads, which undergo stretching, bending, and twisting. interactions. The capillary force, acting at the three-phase contact line, is calculated using a ternary diffuse-interface model. In a first stage, the fibre deformation model and the ternary diffuse-interface model are validated against theoretical solutions. In a second stage, the two- and three-dimensional elasto-capillary bending of a fibre by an immersed droplet are numerically investigated. Partial wrapping and complete encapsulation could be simulated. The results show that the fibre curvature increases linearly with the square of the elasto-capillary length, for both low and large structural deformation.

Keywords: Elasto-capillary deformation; fibre at fluidic interface; ternary diffuse interface model; direct numerical simulation; droplet encapsulation


Publ.-Id: 29135

Fluid Flow and Transport Phenomena in Liquid Metal Batteries

Weier, T.; Horstmann, G. M.; Landgraf, S.; Nimtz, M.; Personnettaz, P.; Stefani, F.; Weber, N.

Fluid flows in liquid metal batteries can be generated by a number of effects. We start with a short overview of different driving mechanisms and then address questions specific to the metal pad role instabilities in three-layer systems. Besides introducing a term accounting for the interfacial tension that should be considered for smaller cells, we focus on the role of the conductivity distribution in the cell.

Keywords: Liquid metal batteries; metal pad roll; sloshing

  • Contribution to proceedings
    11th PAMIR International Conference Fundamental and Applied MHD, 01.-05.07.2019, Reims, Frankreich, 188-192
  • Lecture (Conference)
    11th PAMIR International Conference Fundamental and Applied MHD, 01.-05.07.2019, Reims, Frankreich

Publ.-Id: 29134

Mass Transport in the Positive Electrode of a Liquid Metal Battery

Personnettaz, P.; Landgraf, S.; Nimtz, M.; Weber, N.; Weier, T.

Liquid metal electrodes are one of the key components of different electrical energy storage technologies. The understanding of transport phenomena behind liquid electrodes is mandatory in order to ensure efficient operation, however it would certainly gain by further investigations. In the present study we focus our attention on the positive electrode of a Li||Bi liquid metal battery. Starting from a real experimental setup, we investigate mass transport with numerical simulations. During the charge of the cell, compositional convection becomes apparent. The time evolution of the fluid flow and the flow structure are studied. First results on compositional convection are presented, highlighting its capability to affect the flow in the positive electrode.

Keywords: electrorefining; liquid electrode; liquid metal batteries; mass transport; solutal convection

  • Contribution to proceedings
    11th PAMIR International Conference Fundamental and Applied MHD, 01.-05.07.2019, Reims, France
    Mass Transport in the Positive Electrode of a Liquid Metal Battery
  • Poster
    11th PAMIR International Conference Fundamental and Applied MHD, 01.-05.07.2019, Reims, France

Publ.-Id: 29133

Oscillating hydrogen bubbles at Pt microelectrodes

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

The dynamics of hydrogen bubbles produced via electrolysis in acidic electrolytes is studied in a combination of experiments and numerical simulations.
A transition from monotonous to oscillatory bubble growth is observed after 2/3 of the bubble lifetime, if the electric potential exceeds -3V. This work analyzes characteristic features of the oscillations in terms of bubble geometry, the thickness of the microbubble carpet and the oscillation frequency. An explanation of the oscillation mechanisms is provided by the competition between buoyancy and electric force, the magnitude of which depends on the carpet thickness. Both the critical carpet thickness at detachment and the oscillation frequencies of the bubble as predicted by the model agree well with the experiment.

Keywords: electrolysis; hydrogen bubble; oscillations; charged bubble; electric force

Publ.-Id: 29132

Integral multi-scenario robustness evaluation of anatomical robust optimization in head and neck

Cubillos Mesías, M.; Troost, E. G. C.; Lohaus, F.; Agolli, L.; Rehm, M.; Richter, C.; Stützer, K.

Classical robust optimization considers uncertainties in patient setup and particle range. Usually plan robustness is evaluated from calculation of perturbed dose distributions based on the planning CT, without considering potential anatomical changes that may occur during the treatment course. Our aim was to compare the overall plan robustness of classical robust optimization (cRO) with the recently proposed anatomical robust optimization (aRO) based on an integral multi-scenario evaluation, considering all types of uncertainties including anatomical variations.

Datasets for 20 head and neck cancer patients, including a planning CT and weekly control CTs, were analyzed. Two intensity-modulated proton therapy (IMPT) plans were calculated: cRO, using solely the planning CT, and aRO, including additionally the first two control CTs in the plan optimization. For the robustness analysis, perturbed dose distributions with random setup uncertainties and fixed range uncertainty values of -3.5%, 0% and +3.5% were generated, drawing for each fraction n a random number from a Gaussian distribution around 0 mm with a standard deviation of 2.5 mm for the isocenter shift in each cardinal direction (xn, yn, zn). Moreover, in each fraction n the correspondent weekly control CT was used to consider the anatomical changes during therapy. 33 single-fraction perturbed doses were calculated and summed to generate a perturbed whole-treatment dose distribution. The procedure was repeated 10 times for each of the three range uncertainty values, resulting in 30 perturbed dose distributions per plan (Figure 1).

Both nominal plans fulfilled the clinical objective for target coverage (D98% ≥ 95% of the prescribed dose). The median values calculated from the 30 perturbed dose distributions for each patient showed a reduction in the target coverage for the cRO plan, with mean (minimum) values of 94.9% (88.1%) and 95.4% (89.3%) for the low- and high-risk CTV, respectively, in comparison with 96.6% (92.0%) and 96.8% (93.6%), respectively, for aRO (Figure 2a). The variation in CTV coverage between the 30 scenarios, i.e. the width of the perturbed dose distributions, was found to be larger for cRO plans, with median (maximum) values of 1.9 (8.3) and 1.4 (5.6) for low- and high-risk CTV, respectively, in comparison with 1.4 (3.4) and 0.9 (5.2) for aRO plans, respectively. Moreover, the cRO case showed reduced robustness in comparison with aRO for some patients, where certain scenarios violate the clinical objective, as shown in Figure 2b.

Anatomical robust optimization showed superior plan robustness in comparison with the classical approach in a comprehensive multi-scenario evaluation. Anatomical variations play an important role in the overall plan robustness together with setup and range uncertainties, therefore their effect should not be underestimated or neglected.

  • Lecture (Conference)
    ESTRO 38, 26.-30.04.2019, Mailand, Italien
  • Open Access Logo Abstract in refereed journal
    Radiotherapy and Oncology 133(2019)Sup 1, S488-S489
    DOI: 10.1016/S0167-8140(19)31335-0

Publ.-Id: 29131

Quantification of plan robustness against different uncertainty sources for classical and anatomical robust optimized treatment plans in head and neck cancer proton therapy

Cubillos-Mesías, M.; Troost, E. G. C.; Lohaus, F.; Agolli, L.; Rehm, M.; Richter, C.; Stützer, K.

Objective: Classical robust optimization (cRO) in intensity-modulated proton therapy (IMPT) considers isocenter position and particle range uncertainties; anatomical robust optimization (aRO) aims to consider additional non-rigid positioning variations. This work compares the influence of different uncertainty sources on the robustness of cRO and aRO IMPT plans for head and neck squamous cell carcinoma (HNSCC).
Methods: Two IMPT plans were optimized for twenty HNSCC patients who received weekly control CTs (cCT): cRO, using solely the planning CT, and aRO, including two additional cCTs. The robustness of the plans in terms of clinical target volume (CTV) coverage and organ at risk (OAR) sparing was analyzed considering stepwise the influence of (1) non-rigid anatomical variations given by the weekly cCT, (2) with fraction-wise added rigid random setup errors and (3) additional systematic proton range uncertainties.
Results: cRO plans presented significantly higher nominal CTV coverage but are outperformed by aRO plans when considering non-rigid anatomical variations only, as cRO and aRO plans presented a median target coverage (D98%) decrease for the low-risk/high-risk CTV of 1.8/1.1 percentage points (pp) and -0.2pp/-0.3pp, respectively. Setup and range uncertainties had larger influence on cRO CTV coverage, but led to similar OAR dose changes in both plans. Considering all error sources, 10/2 cRO/aRO patients missed the CTV coverage and a limited number exceeded some OAR constraints in both plans.
Conclusions: Non-rigid anatomical variations are mainly responsible for critical target coverage loss of cRO plans, whereas the aRO approach was robust against such variations. Both plans provide similar robustness of OAR parameters.
Advances in knowledge: The influence of different uncertainty sources was quantified for robust IMPT HNSCC plans.

Keywords: Robust optimization; robustness analysis; head and neck cancer; proton therapy


Publ.-Id: 29130

Bestimmung der Gas-Flüssigkeits-Grenzfläche in Anstaupackungen mittels ultraschneller Röntgentomographie

Sohr, J.; Bieberle, M.; Schubert, M.; Flechsig, S.; Kenig, E. Y.; Hampel, U.

Durch die alternierend angeordneten Packungslagen mit unterschiedlichen geometrischen Oberflächen bilden sich in Anstaupackungen abhängig von den Betriebsbedingungen Filmströmung und Sprudelschicht gleichzeitig aus. Der intensive Kontakt zwischen der Gas- und Flüssigkeitsphase in den sprudelnden Bereichen der Anstaupackung führt zu einer Trenneffizienzsteigerung von bis zu 30 % im Vergleich zu konventionell gepackten Kolonnen [1]. Zur Abschätzung der Beiträge der jeweiligen Bereiche mit unterschiedlichen Strömungsregimen zur Gesamttrennleistung ist die Kenntnis der Gas-Flüssigkeits-Grenzfläche erforderlich. Die Grenzfläche kann mittels ultraschneller Röntgentomographie bestimmt werden, welche die dynamischen Strömungsstrukturen mit einer Bildrate von 1000 Bildern pro Sekunde erfasst. Mithilfe eines modifizierten Level-set-Algorithmus wird die Phasengrenze zwischen Gas einerseits und Flüssigkeit sowie Metallpackung andererseits in den Querschnittsbildern detektiert (Abb.1).
In diesem Beitrag werden sowohl die Methodik zur Bestimmung der Phasengrenzfläche als auch Ergebnisse für unterschiedliche Gas- und Flüssigkeitsbelastungen bei verschiedenen Packungskombinationen präsentiert.
Wir danken der DFG für die finanzielle Unterstützung des Kooperationsprojekts "Experimentelle und theoretische Untersuchung der Fluiddynamik und des Stofftrennverhaltens von Anstaupackungen" (KE 837/26-1, HA 3088/10-1).
[1] M. Jödecke, T. Friese, G. Schuch, B. Kaibel, H. Jansen, Institution of Chemical Engineers Symposium Series, Institution of Chemical Engineers, 2006, Vol.152, pp. 786–789.

  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Membrantechnik, 27.-29.03.2019, Potsdam, Deutschland

Publ.-Id: 29129

Partieller Einsatz von teilweise gefluteten Packungen

Flechsig, S.; Utchenko, Y.; Sohr, J.; Schubert, M.; Hampel, U.; Kenig, E. Y.

Ein Weg zur Reduzierung des hohen Energiebedarfs thermischer Trennverfahren ist die Prozessintegration. Ein Beispiel dafür ist die Integration verschiedener Strömungsformen in einem Trennapparat durch den Einsatz von Anstaupackungen, wodurch eine Erhöhung der Trennleistung im Vergleich zu Strukturpackungen erzielt wird. Anstaupackungen bestehen aus zwei alternierend angeordneten Lagen von industriell verfügbaren Standardpackungen mit unterschiedlichen spezifischen Oberflächen. Die untere Anstaulage weist eine geringere Lastgrenze als die darüber angeordnete Abscheidelage auf, wodurch im Betrieb zwischen den Flutpunkten
beider Lagen ein heterogenes Strömungsmuster entsteht. Dabei bildet sich in der gezielt gefluteten Anstaulage eine bis in die Abscheidelage hineinreichende Sprudelschicht, die durch eine intensive Phasenvermischung und große
Phasengrenzflächen geprägt ist.
Um die Leistungscharakteristik von Anstaupackungen mit der von anderen Einbauten vergleichen zu können, wurde in einer vorherigen Arbeit [1] ein rate-based-Modell entwickelt, welches die Auswirkungen der belastungsabhängig auftretenden Regime in Anstaupackungen berücksichtigt. Basierend auf experimentellen Daten zur CO2-Absorption mit wässrigen Aminlösungen im Technikumsmaßstab sowie tomographischen Untersuchungen wurden Abhängigkeiten der modellspezifischen Parameter identifiziert und anschließend regimespezifisch ins Modell implementiert. Mittels Prozesssimulationen der CO2-Absorption aus Abgasen gasbefeuerter Kraftwerke im industriellen Maßstab werden im Rahmen dieser Arbeit Anstaupackungen und Strukturpackungen hinsichtlich der benötigten Kolonnenabmessungen und des zu überwindenden Druckverlustes verglichen. Um eine abschließende Bewertung durchzuführen, wurden mithilfe von Aspen Process Economic AnalyzerTM die Anlagen- und Betriebskosten für die CO2-Abscheidung bestimmt. Zusätzlich wurde zur Ermittlung eines optimalen Designs der Einfluss der wesentlichen Geometrieparameter von Anstaupackungen auf die Kosten untersucht.
[1] S. Flechsig, J. Sohr, M. Schubert, U. Hampel, E.Y. Kenig, Chem. Eng. Trans., 2018, 69, 169-174, DOI: 10.3303/CET1869029.

  • Lecture (Conference)
    Jahrestreffen der ProcessNet-Fachgruppen Fluidverfahrenstechnik und Membrantechnik, 27.-29.03.2019, Potsdam, Deutschland

Publ.-Id: 29128

Mass transfer and electrolyte flow during electrodeposition on a conically shaped electrode under the influence of a magnetic field

Huang, M.; Marinaro, G.; Yang, X.; Fritzsche, B.; Lei, Z.; Uhlemann, M.; Eckert, K.; Mutschke, G.

The electrodeposition of copper on a conically shaped diamagnetic electrode was studied under the influence of a vertical magnetic field. Numerical simulations combined with measurements of the velocity and the concentration field were conducted to provide understanding of the influence of the Lorentz force on the deposition process. The secondary flow caused by the magnetic field is directed downward along the cone surface and thus supporting conical growth. Since the cathode is placed at the bottom of the electrochemical cell, natural convection is counteracting the influence of the Lorentz force. However, the different time scales of both forces involved allow to utilize the beneficial influence of the Lorentz force, e.g. in pulsed deposition regimes.

Keywords: copper electrodeposition; magnetic field; surface-structured electrode; Mach-Zehnder interferometry; shadowgraphy; numerical simulation


Publ.-Id: 29127

Degradation of natural uranium containing micro-mineral phases: Implications to contaminats transport at abandoned mining sites

Pidchenko, I.; Bauterns, S.; Amidani, L.; Kvashnina, K.

In this work a combination of multiple synchrotron and laboratory based micro-techniques is utilized to unveil the speciation, heterogeneities and degradation of uranium (U) micro-mineral phases accumulated on rock outcrop from natural U deposit area. The investigated system is sampled from the abandoned Krunkelbach U mine in Southern Germany with 2-3 km surrounding area which represents a natural analogue site with an unique accumulation of U minerals suitable for investigations of potential mobilization-immobilization processes expected in a real spent nuclear fuel repository. A specific feature of the site is the occurrence of more than forty secondary U minerals, from uraninite, mixed U oxy-hydroxides to uranyl silicates, representing a wide scale of U ore weathering events. Available data on the age of the secondary U mineralization indicates that oxidizing processes at the site started some 340,000 years ago and continues up to date. Several phases close to Cu(UO2)2(PO4)2-x(AsO4)x·8H2O are identified on 1×2 mm2 area with presumably older, more evenly distributed uranyl silicate and uranyl tungstate mineralization. Based on a multi-technique investigation 10-200 μm Cu(UO2)2(PO4)2-x(AsO4)x·8H2O particles with widely varying arsenic-phosphorus (As-P) content are analyzed. The evidences of a degradation on some zones of selected crystals are found which are associated with higher As content. This observation can be apparently attributed to different degradation properties of the mixed As-P phases depending on As-P ratio and originate from drastically different solubility properties of Cu(UO2)2(PO4)2·8H2O and Cu(UO2)2(AsO4)2·8H2O species. The conditions for preferential formation of As rich Cu(UO2)2(XO4)2·8H2O [X=As, P] phases and its possible role on U transport in environment under oxidizing conditions are discussed.

  • Lecture (Conference)
    21st Mendeleev Congress on General and Applied Chemistry, 09.-13.09.2019, Saint Petersburg, Russia

Publ.-Id: 29126

Multidimensional fluid mixing study during an asymmetric injection of cold water in the primary side of a generic PWR KONVOI with ATHLET 3.1A

Diaz Pescador, E.; Schäfer, F.; Kliem, S.

The presented paper gathers the insights obtained during the study of the multidimensional fluid mixing in the reactor pressure vessel (RPV) during an asymmetric injection of cold or overcooled water in the primary side of a generic German PWR KONVOI reactor by means of the thermal-hydraulic system code ATHLET 3.1A. With this aim, the paper provides first an overview on the selection procedure of the accident scenarios to be studied together with the plant model development, with special emphasis on the pseudo multidimensional RPV configuration. Later on the fluid mixing study in the RPV is performed during an overcooling transient by means of two different developed vessel configurations and the obtained results are assessed against experimental data from analogous tests carried out at the ROCOM test facility, showing good agreement to each other.

  • Contribution to proceedings
    50th Annual Meeting on Nuclear Technology (AMNT) 2019, 07.05.2019, Berlin, Germany
  • Lecture (Conference)
    50th Annual meeting on Nuclear Technology (AMNT) 2019, 07.-08.05.2019, Berlin, Germany

Publ.-Id: 29125

Accelerated time-of-flight scatter correction for whole-body PET

Nikulin, P.; Maus, J.; Hofheinz, F.; van den Hoff, J.

Utilization of Time-Of-Flight (TOF) information allows to improve image quality and convergence rate in PET image reconstruction. In order to obtain quantitatively correct images accurate scatter correction (SC) is required that accounts for the study-specific scatter time distribution.
The currently accepted TOF-SC gold standard - the TOF extension of the single scatter simulation approach (TOF-SSS), see [1] - is computationally demanding and can substantially slow down the reconstruction which becomes a substantial problem in whole-body investigations. On the other hand, the accuracy of existing simplified TOF-SC algorithms is limited in many cases. We have developed a new TOF-SC algorithm in order to improve this situation.

Our TOF-SC method is based on a separate estimation of scatter spatial distribution (via SSS) and scatter time distribution via a dedicated fast algorithm. The key idea of the algorithm is the use of an immediate scatter approximation (ISA) for scatter time distributions calculation. The underlying assumption is that for this calculation a distinction between the emission point from which the annihilation event originates and actual scatter point is not crucial.
The proposed approach was evaluated in phantom measurements providing challenging high activity contrast conditions as well as in representative clinical patient data sets.

The reconstructed images are in excellent quantitative agreement with those obtained with TOF-SSS while scatter estimation time was reduced by a factor of four and overall reconstruction time by a factor of two in whole-body studies, even when using a listmode reconstruction not optimized for speed.

Our results show that ISA is a viable alternative to TOF-SSS offering a factor of four TOF scatter estimation acceleration without compromising the image quality.

[1] C. C. Watson, Extension of Single Scatter Simulation to Scatter Correction of Time-of-Flight PET, IEEE Transations Nucl. Sci., vol. 54(5), pp. 1679–1686, 2007


  • Lecture (Conference)
    57. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 03.-06.04.2019, Bremen, Deutschland

Publ.-Id: 29121

Predictive Geometallurgy- State of the Art

Birtel, S.; Büttner, P.; Frenzel, M.; Bachmann, K.; Tolosana Delgado, R.; Gutzmer, J.

The 45 minutes talk gives a brief overview of the approach of the Helmholtz Institute Freiberg for Resource Technology, followed by an introduction into Geometallurgy, Predictive Geometallurgy respectively. From the analytical perspective there will be a focus on SEM based automated image analysis. This data is the basis for further data processing, statistical assesment and interpretations. Depending on data availability, operational stage (exploration extraction) different levels of geometallurgical models can be created. This will be illustrated in case studies, showing the work flow and result for the development of 1) 3D resource potential model of a historic tailings dam to recover Sn, 2) Methodology for mineralogical deportment prediction of In as a by- product from complex ore types, 3) 3D first order geomet model of a primary deposit to recover PGE as by product

Keywords: Geometallurgy; predictive geometallurgical model; SEM based automated mineralogy; data analysis

  • Invited lecture (Conferences)
    InRec Stakeholder Meeting (Geometallurgy applied to industrial Mineral operations), 24.-25.04.2019, Trondheim, Norway

Publ.-Id: 29120

Geostatistical Compositional Analysis of Regional Geochemical Stream Sediments of West Java, Indonesia

Selia, S. R. R.; Rus, A. M. M.; Tolosana Delgado, R.; Sendjaja, P.; van den Boogaart, K. G.; Schaeben, H.

As analytical tools evolve, more geochemical data are obtained so that effective and robust tools are demanded for capturing detailed information of underlying geological processes such as alteration, mineralization and weathering. The data are formed by a number of elements, whose concentrations are interdependent due to the fact that their total sum is bounded to a constant (e.g. 100%). Classical statistical analysis of this type of data may provide misleading results because it does not consider the closure effects: for instance, one of the correlation coefficients will always be negative regardless of whether the two elements with negative correlation are incompatible or not. Consequently, methods employing variance cannot be used on the raw dataset. To manage this problem, one can adopt Compositional Data Analysis (CoDa) which acknowledges the compositional nature of the data.

In the last decade, CoDa has been widely applied to geochemical data. Thus, combined with geological information, we apply CoDa to the regional geochemical stream sediment data of West Java to address our understanding of the underlying geological processes of the area. The first process carried out is a log-ratio transformation to eliminate both constant-sum constraints and non-negativity problems. Then to distinguish features in the data a Principal Component Analysis (PCA) can be performed. Here we can get linear components that have a large effect on variations in the data. The final stage is the spatial estimation of important PCA components through experimental variogram calculation, variogram modeling, and geostatistical estimation. The interpolated maps can be back-transformed to obtain maps of the original components. In this way, the results will not violate the compositional nature of the data, while spatially representing the captured processes.

Keywords: Geochemical exploration; Geology of Java; Mining

  • Lecture (Conference)
    HAGI-IAGI-IAFMI-IATMI Joint Convention 2019, 25.-28.11.2019, Yogyakarta, Indonesia

Publ.-Id: 29119

Mid-Treatment Gd-EOB-DTPA-Enhanced MRI and Interleukin 6 Cytokine as Biomarkers of Radiation-induced Liver Toxicity in Metastatic Liver Patients

Ajdari, A.; Xie, Y.; Richter, C.; Hong, T.; Bortfeld, T.

Purpose: In the era of precision medicine and personalized radiation treatment (RT), there is an ever-growing need to find predictive biomarkers of treatment response in patients. Here we investigate the potentials of using mid-treatment MR images and inflammatory cytokines as biomarkers of liver toxicity.

Method and Materials: Eleven intrahepatic metastatic patients who had proton stereotactic body radiotherapy (SBRT) to the liver lesion were retrospectively analyzed. Two Gd-EOB-DTPA (a hepatobiliary-directed contrast agent)-enhanced MR scans as well as three inflammatory cytokines (interleukin 6 [IL-6], IL-8, and tumor necrosis factor α [TNF- α]) were acquired during the RT course. Deformable image registrations were done among mid-treatment (fx4 and 5) MR images and the planning CT. MR signal changes and delivered dose were then calculated for each voxel. Mid-treatment changes in the expression of the cytokines were calculated with respect to the pre-treatment baseline. Liver toxicity was assessed at 3 months post-RT, using Child-Pugh (CP) and ALBI score. Patients were subsequently classified into high-risk (HR) and low-risk (LR) groups. Statistical analysis was performed to compare the changes in the MR signals and cytokine expressions between these groups.

Results: On average, high-risk patients had lower high-dose/low-dose mid-treatment signal changes (i.e., decreased/increased signal in high-dose/low-dose). In CP classification, there was a significant difference in MR signal change between two group means (0.61 and 1.04 for HR and LR groups; p-value=0.005). The ALBI classification showed more pronounced difference (0.61 vs. 1.11, p-value = 0.002). High-risk patients also showed larger IL-6 changes during their treatment (86% vs. 0.33%, p-value=0.01).

Conclusion: Using mid-treatment MR scans and interleukin 6 as biomarkers, it is possible to predict the risk of acute liver toxicity, already during the RT course. This biomarker information can be potentially used for adaptive planning and RT plan personalization.

Keywords: Liver metastasis; MR; mid-treatment; adaptations; biomarker; cytokine

  • Lecture (Conference)
    2019 AAPM Annual Meeting, 14.-18.07.2019, San Antonio, USA
  • Abstract in refereed journal
    Medical Physics 46(2019)6, E499-E499
    DOI: 10.1002/mp.13589

Publ.-Id: 29118

Late life brain perfusion after prenatal famine exposure

de Rooij, S. R.; Mutsaerts, H. M.; Petr, J.; Asllani, I.; Caan, M. W.; Groot, P.; Nederveen, A.; Schwab, M.; Roseboom, T. J.

Early nutritional deprivation may cause irreversible damage to the brain and seems to affect cognitive function in older age. We investigated whether prenatal undernutrition was associated with brain perfusion differences in older age. We acquired Arterial spin labelling scans in 118 Dutch famine birth cohort members. Cerebral blood flow (CBF) was compared between exposed and unexposed groups in grey and white matter, perfusion territories, neurodegeneration-related regions anterior and posterior cingulate cortex and precuneus. Furthermore, we compared the GM/WM-ratio and the spatial coefficient of variation (CoV) as a proxy of overall cerebrovascular health. The WM ASL signal and the GM/WM-ratio were significantly lower and higher respectively among exposed participants. Exposed men had lower CBF in anterior and posterior cingulate cortices and higher spatial CoV. The latter seemed largely mediated by higher 2h-glucose levels at age 50. Our findings suggest that overall brain perfusion was worse in exposed participants, especially men exposed to undernutrition in early gestation. These results provide further evidence for life-long effects of undernutrition during early brain development.

Keywords: brain perfusion; prenatal famine; fetal programming


Publ.-Id: 29117

Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air

Unger, S.; Krepper, E.; Beyer, M.; Hampel, U.

The passive cooling of nuclear spent fuel pools is a promising alternative to active cooling. Since such systems work even in safety-critical situations, e.g. station blackout, the reliability of nuclear power plants would be enhanced. As in such systems heat needs to be transfer to the environment, the heat exchanger to air has a crucial influence on the system performance. This paper describes investigations of the Nusselt number, the achievable efficiency and the volumetric heat flux density of the tube bundle heat exchangers for a passive cooling system located at the bottom of a chimney. The effect of tube bundle configuration, tube shape, longitudinal tube pitch, transversal tube pitch and tube row number on natural convection heat transfer was numerical studied. These parameters were varied to optimize the heat transfer performance of the heat exchanger. It was found, that the staggered configuration performs better than the inline arrangement, since the flow mixing is higher. Furthermore circular tube shape and an oval tube shape with the aspect ratio of 1:2.1 were optimum for the inline and staggered configuration respectively. The longitudinal and transversal tube pitches of 63 mm and 65 mm performed best, since higher values reduced heat transfer. A tube row number greater than 5 did not improve the heat transfer and therefore a tube row number of 5 is recommended. The Nusselt number and volumetric heat flux density of the optimized tube bundle arrangement enhanced by 15.4 % and 47.8 % respectively at a temperature difference of 40 K compared to the initial design.

Keywords: passive cooling; spent fuel pool; natural convection; tube bundle heat exchanger; air cooling; design optimization

Related publications

Publ.-Id: 29116

Quantifying the value of geometallurgical information and optimization

van den Boogaart, K. G.

Predictive Geometallurgy can use thorough quantitative characterisation of the ores microstructure and mineralogy to predict and adaptively optimize the processing and blending of the ore. Adaptive processing allows to exploit this variation to achieve higher overall recovery at lower costs, e.g. by adapting milling to mineral grain sizes or grades.

The geometallurgical properties of the ore are however typically only known with some geostatistical uncertainty. The talk demonstrates in model calculation, that naive optimization of processing parameters based on expected ore properties might lead to performance losses relative to non-adaptive processing, while overestimating its own expected performance. The contribution shows how to outperform non-adpative processsing decissions substantially based on a stochastic optimization approach and how to quantify the value of geometallurgical information in a certain setting.

Indeed in the context of predictive geometallurgy the value of a blend is no longer defined only by its acutally physical properties, but also by the information we have about it at the time of processing. This makes geometallurgical exploration activity a relevant part of the mine plan, which can actually change and on average increase the value of blocks.

Keywords: Geometallurgy; Mine Scheduling; Stochastic Optimization; Geostatistics

  • Lecture (Conference)
    2019 COSMO Technical Day, 27.-28.06.2019, Montreal, Canada

Publ.-Id: 29115

Nuclear Data Sensitivity and Uncertainty Analysis of Critical VENUS-F Cores with the Serpent Monte Carlo Code

Fridman, E.; Valtavirta, V.; Aufiero, M.

In the framework of the FP7 Euratom project FREYA, the Serpent Monte Code was used to characterize a number of critical VENUS-F core configurations. Several neutronic parameters calculated by Serpent were compared to the available experimental data and reported in a previous study. Although a generally reasonable agreement between the calculated and experimental values was obtained, the study also revealed some important issues related to the numerical results such as a systematic overestimation of reactivity and a systematic underestimation of U238 to U235 fission rate ratio (designated as F28/F25 spectral index).
The objective of the current follow-up study is to quantify the effect of nuclear data uncertainties on the Monte Carlo estimates of reactivity and spectral indices. The analysis is carried out for two critical VENUS-F cores using a recently upgraded version of Serpent which is capable to perform sensitivity analysis based on the collision history method and to propagate and quantify nuclear data uncertainties using multi-group covariance libraries in an automated way. The criticality calculations were performed using the ENDV/B-VII.1 based cross sections while the uncertainties due to nuclear data were obtained using 56-group neutron cross section covariance library from the SCALE-6.2 package.
The estimated uncertainties due to nuclear data are of the order of 2200 pcm and 8% on k-eff and F28/F25 spectral index respectively. It was found that the major contributor to the k-eff uncertainty is capture cross section of U235. In the F28/F25 case, the total uncertainty is dominated by inelastic cross section of U238, fission spectrum of U235, and capture cross section of U235.

Keywords: Serpent; Monte Carlo; uncertainty quantification; FREYA; VENUS-F; critical experiments


  • Secondary publication expected

Publ.-Id: 29114

Simulating air-breathing fuel cells using openFuelCell

Weber, N.; Chaparro, A. M.; Ferreira-Aparicio, P.; Zhang, S.; Reimer, U.; Beale, S.

The talk will be dedicated to modelling polymer electrolyte fuel cells. In the first part, the theory of the fuel cell model is presented. Details on its implementation in the open source library openFuelCell will be given. Secondly, numerical results on modelling an air-breathing fuel cell operated at CIEMAT will be shown and discussed.

  • Lecture (Conference)
    OpenFOAM Workshop, 23.07.2019, Duisburg, Germany

Publ.-Id: 29113

Modelling electric potential distributions in batteries and fuel cells: an overview

Weber, N.; Personnettaz, P.; Weier, T.; Sadoway, D.

The talk will give an overview on simulating electric potential and current distributions in the frame of the finite volume method. Special attention will be paid to modelling internal discontinuities of the electric potential, as they appear at the electrode-electrolyte interface in fuel cells, electrolysers and batteries. The theoretical background will be explained and illustrated with simple examples.

  • Lecture (Conference)
    OpenFOAM Workshop, 23.07.2019, Duisburg, Deutschland

Publ.-Id: 29112

Detection of the pulp-froth interface using the ultrasound transit time technique

Richter, T.; Heitkam, S.; Odenbach, S.; Eckert, K.

The vertical position of the pulp-froth interface in a flotation cell is an important parameter in froth flotation processes which needs to be controlled in situ. For this purpose, we introduce the ultrasound transit time technique (UTTT), a non-invasive technique for detecting and measuring the position of this interface. Based on lab-scale experiments, the method is evaluated for a pulp-air and a pulp-froth interface. The technique was found to be well applicable in pulp with up to 21% particle mass fraction. In a container with 80 mm height the accuracy is found to equal 1mm.

Keywords: lab-scale flotation; level height detection; pulp-froth interface; ultrasound transit time technique


  • Secondary publication expected from 26.10.2021

Publ.-Id: 29111

Interaction of uranium with halophilic microorganisms

Bader, M.; Hilpmann, S.; Swanson, J. S.; Steudtner, R.; Drobot, B.; Schmidt, M.; Roßberg, A.; Ikeda-Ohno, A.; Stumpf, T.; Cherkouk, A.

Rock salts are considered as potential host rocks for the long-term storage of highly radioactive waste in a deep geological repository. In addition to bacteria and fungi, extremely halophilic archaea, e.g. Halobacterium species, are predominantly present in this habitat. For long-term risk assessment it is of high interest to study how these microorganisms can potentially interact with radionuclides if the radionuclides are released from the waste repository. Given this fact, the interactions of extremely halophilic archaea from the genus Halobacterium and the moderately halophilic bacterium Brachybacterium sp. G1 with uranium, one of the major radionuclides of concern in the geological repository of radioactive wastes, were investigated in detail in batch experiments. The archaea and the bacterium showed different association mechanisms with uranium. Brachybacterium sp. G1 cells sorbed uranium within a short time, whereas a much longer and a multi-stage bioassociation process, dependent on the uranium concentration, occurred with the archaea. Furthermore, a multi-spectroscopic (time-resolved laser-induced fluorescence spectroscopy and X-ray absorption spectroscopy) and -microscopic (scanning electron microscopy coupled with energy-dispersive X-ray analysis for elemental mapping) approach was used to elucidate the U(VI) bioassociation behavior. By using these spectroscopic and microscopic tools, the formation of a U(VI) phosphate mineral, such as meta-autunite, by the Halobacterium species was demonstrated. These findings offer new insights into the microbe-actinide interactions at highly saline conditions relevant to the disposal of nuclear waste.

  • Lecture (Conference)
    Halophiles 2019, 24.-28.06.2019, Cluj-Napoca, Romania

Publ.-Id: 29110

Prediction of Bubble Departure in Forced Convection Boiling with a Mechanistic Model that Considers Dynamic Contact Angle and Base Expansion

Setoodeh, H.; Ding, W.; Lucas, D.; Hampel, U.

A mechanistic model for bubble dynamics in flow boiling that is based on a force balance approach for a growing bubble is introduced. It considers evaporation of the microlayer underneath the bubble, thermal diffusion and condensation around the bubble cap as well as dynamic inclination and contact angles between the bubble and the heating wall. It requires no recalibration of parameters to predict the bubble growth. Validation against different experimental flow boiling data was carried out with no case-dependent recalibration and yielded good agreement. The simulations confirmed the dependency of bubble departure and lift-off diameters on different parameters, such as heat flux, liquid properties, subcooling temperature, system pressure, inclination angle of channel, channel geometry and mass flow rate.

Keywords: flow boiling; bubble growth; bubble departure; force balance

Publ.-Id: 29109

Mechanical compliancy for magnetic field sensors

Makarov, D.

Augmented reality gadgets are becoming common for our information intensive society assisting us to acquire and process the data. Although impressive in the realization and demonstrations, the obvious drawback of the state-of-the-art augmented and virtual reality devices relying on optical detection systems is their bulkiness, energy inefficiency and the stringent requirement for an operator to be at the line of sight of the device.
We envision that prospective augmented reality systems will strongly benefit from the recent developments in compliant on-skin electronics [1-3]. The fabrication of highly conformable gadgets requires the realization of the electronic replica of the exteroceptive sensory system of humans as well as calls for the acquiring new perception skills beyond those prescribed by the evolution. The representative example of the missing exteroceptive sense of humans is the magnetoception, which allows some of the mammals but not humans perceiving the location in space or directions based on the detection of magnetic fields. The first crucial step towards the realization of this vision was accomplished with the development of interactive magnetosensitive skins [4-6]. The key enabler for this technology is the shapeable magnetoelectronics [7] –namely, flexible [5,6], stretchable [8,9] and imperceptible [4,10-12]– magnetic field sensorics.
Here, we present the first on-skin gadgets, which replicate our natural proprioceptive sensory ability of detecting the motion [4,10-12]. The technology is put forth to realize distributed arrays of magnetic field sensors on ultra-thin polymeric foils. Relying on this magnetically enabled electronic proprioception, we visualize the bodily motion and demonstrate the touchless manipulation of virtual objects for augmented reality systems.
Those highly conformable interactive devices possess great potential to extend the portfolio of tasks, which can be performed in virtual or augmented reality. The integration of gadgets in imperceptible electronic skins will open not only exciting possibilities for business or gaming industry but is also beneficial for safety and security applications, where the somatic manipulation of objects, e.g. turning regulation knobs located in a restricted environment is undesirable or even prohibited.

1. J. A. Rogers et al., Nature 477, 45 (2011).
2. S. Bauer et al., Adv. Mater. 26, 149 (2014).
3. M. Kaltenbrunner et al., Nature 499, 458 (2013).
4. M. Melzer et al., Nature Commun. 6, 6080 (2015).
5. M. Melzer et al., Adv. Mater. 27, 1274 (2015).
6. N. Münzenrieder et al., Adv. Electron. Mater. 2, 1600188 (2016).
7. D. Makarov et al., Appl. Phys. Rev. 3, 011101 (2016).
8. M. Melzer et al., Nano Lett. 11, 2522 (2011).
9. M. Melzer et al., Adv. Mater. 27, 1333 (2015).
10. G. S. Canon Bermudez et al., Science Advances 4, eaao2623 (2018).
11. G. S. Canon Bermudez et al., Nature Electronics 1, 589 (2018).
12. P. Granell et al., npj Flexible Electronics 3, 3 (2019).

Keywords: flexible electronics; flexible magnetic field sensors

  • Invited lecture (Conferences)
    Magnetic Frontiers 2019: Magnetic Sensors, 24.-27.06.2019, Lisbon, Portugal

Publ.-Id: 29108

Curvilinear magnetism

Makarov, D.

There is one aspect, which is in common to the majority of fundamentally appealing and technologically relevant novel magnetic materials, namely their non-collinear magnetic textures like spin spirals, chiral domain walls or skyrmions [1]. These textures are typically driven by the Dzyaloshinskii-Moriya interaction (DMI). Recently, curvature effects emerged as a novel mean to design chiral magnetic properties by relying on extrinsic parameters, e.g. geometry of thin films [2]. In particular, novel effects occur when the magnetization is modulated by curvature leading to new magnetization configurations and is implications on the spin dynamics due to topological constraints. Advances in this novel field solely rely on the understanding of the fundamentals behind the modifications of magnetic responses of 3D-curved magnetic thin films [3,4] and nanowires [5]. The lack of an inversion symmetry and the emergence of a curvature induced effective anisotropy and DMI are characteristic of curved surfaces, leading to curvature-driven magnetochiral effects and topologically induced magnetization patterning [6,7]. The application potential of 3D-shaped objects is currently being explored as mechanically reshapeable magnetic field sensorics [8] for flexible interactive electronics [9,10], spin-wave filters and high-speed racetrack memory devices [11]. The fundamentals as well as application relevant aspects of curvilinear nanomagnets will be covered in this presentation.
[1] “The 2017 Magnetism Roadmap”, D. Sander et al., J. Phys. D 50, 363001 (2017).
[2] “Magnetism in curved geometries”, R. Streubel, et al., J. Phys. D 49, 363001 (2016).
[3] “Curvature Effects in Thin Magnetic Shells”, Y. Gaididei et al., Phys. Rev. Lett. 112, 257203 (2014).
[4] “Multiplet of Skyrmion States on a Curvilinear Defect: Reconfigurable Skyrmion Lattices”, V. Kravchuk et al., Phys. Rev. Lett. 120, 067201 (2018).
[5] “Mesoscale Dzyaloshinskii-Moriya interaction: geometrical tailoring of the magnetochirality”, O. M. Volkov et al., Scientific Reports 8, 866 (2018).
[6] “Coupling of Chiralities in Spin and Physical Spaces: The Möbius Ring as a Case Study”, O. V. Pylypovskyi et al., Phys. Rev. Lett. 114, 197204 (2015).
[7] “Curvature-Induced Asymmetric Spin-Wave Dispersion”, J. A. Otalora et al., Phys. Rev. Lett. 117, 227203 (2016).
[8] “Shapeable magnetoelectronics”, D.Makarov et al., Appl. Phys. Rev. 3, 011101 (2016).
[9] “Magnetosensitive e-skins with directional perception for augmented reality”, S. Canon Bermudez et al., Science Advances 4, eaao2623 (2018).
[10] “Electronic-skin compasses for geomagnetic field driven artificial magnetoreception and interactive electronics”, S. Canon Bermudez et al., Nature Electronics 1, 589 (2018).
[11] “Beating the Walker Limit with Massless Domain Walls in Cylindrical Nanowires”, M. Yan et al., Phys. Rev. Lett. 104, 057201 (2010).

Keywords: curvature effects in magnetism; curved magnetic thin films

  • Invited lecture (Conferences)
    6th International Conference from Nanoparticles and Nanomaterials to Nanodevices and Nanosystems, 30.06.-03.07.2019, Corfu, Greece

Publ.-Id: 29107

Revealing the Formation Dynamics of the Electric Double Layer by means of in-situ Rutherford Backscattering Spectrometry

Baghban Khojasteh Mohammadi, N.; Apelt, S.; Bergmann, U.; Facsko, S.; Heller, R.

We report on a new versatile experimental setup for in-situ Rutherford backscattering spectrometry at solid- liquid interfaces that enables investigations of electric double layers directly, in-situ and in a quantitative manner. A liquid cell equipped with a three electrode arrangement is mounted in front of the beam line and a thin Si3N4 window down to a thickness of 150 nm separates the vacuum of the detector chamber from the electrolyte in the cell. Since the contribution of the window to the measured spectra is minimized, a large variety of elements at the solid-liquid interface with sensitivities far below one mono layer can be monitored. The attachment of Ba onto the Si3N4 surface as a function of contact time and pH value of the electrolyte solution was chosen as example system. From our measurement we can not only read the evolution of the double layer but also derive limits for the point of zero charge for the Si3N4 surface. Our findings of 5.7 ≤ pH_PZC ≤ 6.2 are in good accordance with values found in the literature obtained by other techniques. Despite the measurements shown in this work, the presented setup allows for a large variety of in-situ investigations at solid-liquid interfaces such as tracing electro-chemical reactions, monitoring segregation, adsorption and dissolution and corrosion processes.

Keywords: Electric Double Layer; in-situ RBS; solid-liquid interface


Publ.-Id: 29106

Indium thiospinel In1-xxIn2S4 – structural characterization and thermoelectric properties

Wyżga, P.; Veremchuk, I.; Himcinshi, C.; Burkhardt, U.; Carrillo-Cabrera, W.; Bobnar, M.; Hennig, C.; Leithe-Jasper, A.; Kortus, J.; Gumeniuk, R.

A detailed study of polycrystalline indium-based In1-xxIn2S4 (x = 0.16, 0.22, 0.28, 0.33) thiospinel is presented. The comprehensive description of synthesis conditions, phase composition and thermoelectric properties is performed applying various diffraction, microscopic and spectroscopic methods. Single-phase α- and β-In1-xxIn2S4 were found in the samples with 0.16  x  0.22 and x = 0.33 (In2S3), respectively, while In0.720.28In2S4 is proven to contain both α- and β-polymorphic modifications. Consequently, thermoelectric characterization of well-defined α-and β-In1-xxIn2S4 is conducted for the first time. α-In1-xxIn2S4 (x = 0.16, 0.22 and 0.28) revealed n-type semiconducting behavior, large Seebeck coefficient (< - 200 μV∙K-1) and moderate charge carrier mobility on the level of ~ 20 cm2V-1s-1 at room temperature (RT). The evident decrease of charge carrier concentration (increase of electrical resistivity) and thermal conductivity (even below 0.6 W∙m-1K-1 at 760 K) for larger In-content is observed. Although β-In0.670.33In2S4 (β-In2S3) is a distinct polymorphic modification, it followed the above-mentioned trend in thermal conductivity and displayed significantly higher charge carrier mobility (~ 104 cm2V-1s-1 at RT). These findings indicate that structural disorder in α-modification affects both electronic and thermal properties in this thiospinel. The reduction of thermal conductivity counterbalances lowered power factor and thus, thermoelectric figure of merit ZTmax = 0.2 at 760 K is nearly the same for both α- and β-In1-xxIn2S4.

Keywords: In2S3; thermoelectric properties; thiospinel; Raman spectroscopy; transmission electron microscopy

Publ.-Id: 29105

Structural stability and thermoelectric performance of high quality synthetic and natural pyrites (FeS2)

Zuñiga-Puelles, E.; Cardoso-Gil, R.; Bobnar, M.; Veremchuk, I.; Himcinschi, C.; Hennig, C.; Kortus, J.; Heide, G.; Gumeniuk, R.

Synthetic bulk and natural pyrite from the hydrothermal mine in Schönbrunn (Saxony, Germany) are confirmed to be stoichiometric compounds with the composition FeS2 and to be stable up to ~600 K by combined chemical, spectroscopic and X-ray diffraction analyses. Natural pyrite with negligibly small amount (< 0.6 wt.%) of well-defined transition metal carbonates impurities revealed characteristics of a nondegenerate semiconductor and is considered as a model system for investigation of thermoelectric performance. In the temperature range 50-600 K both natural and synthetic high quality bulk FeS2 samples show electrical resistivity varying within (220)-(5×10-3) Ω m and Seebeck coefficients of (4)-(-450) μV K-1. The thermal conductivity is large (~40 W m-1 K-1 at 300 K) and exclusively due to phononic contribution. It reveals a well pronounced maximum centered at ~75 K for natural pyrite (grain size ≤ 5 mm), which becomes almost completely suppressed in the sintered bulk samples due to increase of the point defects concentration and additional scattering on the grain boundaries (grain size ≤ 100 μm). The thermoelectric efficiency of a pure pyrite with ZT ~ 10-6 at 600 K is indeed by a factor of ~1000 worse than those reported earlier for some minerals and synthetic samples.

Keywords: crystal structure; thermoelectric; natural mineral; pyrite

Publ.-Id: 29104

CeMo2B5: a new type of arrangement of puckered boron hexagonal rings

Flipo, S.; Kohut, M.; Roth, F.; Weigel, T.; Schnelle, W.; Bobnar, M.; Ormeci, A.; Burkhardt, U.; Hennig, C.; Leisegang, T.; Meyer, D.-C.; Leithe-Jasper, A.; Gumeniuk, R.

REMo2B5 (RE = Ce, Pr, Nd) and CeW2B5 have been synthesized by arc melting with further annealing at 1300 °C.
CeMo2B5 crystallizes in a new structure type with space group REMo2B5 (RE = Ce, Pr, Nd) and CeW2B5 have synthesized by arc melting with further annealing at 1300 °C. CeMo2B5 crystallizes in a new structure type with space group Pnma, a = 11.0298(2) Å, b = 3.12080(5) Å, c = 9.9594(2) Å, Z = 4. Its structural arrangement reveals puckered [B6]-hexagonal rings, trigonal-prismatic- and empty pyramidal-tetrahedralslabs.The structure can be related to the derivatives of AlB2 and CrB prototypes. The boron atoms form a two-dimensional network of corrugated ribbons, each composed of four edgelinked [B6] rings infinitely extending along the b-axis. CeMo2B5 is a Pauli paramagnet. Electrical transport measurements together with the calculated density of states at the Fermi level of 3.81 states eV–1 f.u.–1 indicate CeMo2B5 to be a typical metallic system. Electronic structure calculations reveal significant hybridization of Ce 4f5d states with Mo 4d states. The chemical bonding scenario is dominated by chains of [Ce2Mo2] clusters with multi-center bonds. These clusters are connected via metallic Mo–Mo bonds. This metal-framework, in turn, is stabilized by bonding interactions with the boron ribbons to which it donates electrons.

Keywords: intermetallic borides; crystal structure; X-ray diffraction; magnetism

Publ.-Id: 29103

High-Quality LWFA-Based Electron Sources

Couperus Cabadağ, J. P.

  • Invited lecture (Conferences)
    ALEGRO workshop 2019, 27.03.2019, Genève, Confédération suisse

Publ.-Id: 29102

Reduced diffusion in normal appearing white matter of glioma patients following radio(chemo)therapy

Raschke, F.; Wesemann, T.; Wahl, H.; Appold, S.; Krause, M.; Linn, J.; Troost, E. G. C.

Background and purpose:
Standard treatment of high grade gliomas includes gross tumour resection followed by radio(chemo)therapy. Radiotherapy inevitably leads to irradiation of normal brain tissue. The goal of this prospective, longitudinal study was to use MRI to quantify normal appearing white and grey matter changes following radiation treatment as a function of dose and time after radiotherapy.
Materials and methods:
Pre-radiotherapy MRI (proton or photon therapy) and follow-up MRIs collected in 3 monthly intervals thereafter were analysed for 22 glioma patients and included diffusion tensor imaging, quantitative T1, T2* and proton density mapping. Abnormal tissue was excluded from analysis. MR signal changes were quantified within different dose bin regions for grey and white matter and subsequently for whole brain white matter.
We found significant reductions of mean diffusivity, radial diffusivity, axial diffusivity and T2* in normal appearing white matter regions receiving a radiation dose as low as 10-20 Gy within the observational period of up to 18 months. The magnitude of these changes increased with the received radiation dose and progressed with time after radiotherapy. Whole brain white matter also showed a significant reduction in radial diffusivity as a function of radiation dose and time after radiotherapy. No significant changes were observed in grey matter.
Diffusion tensor imaging and T2* imaging revealed normal appearing white matter changes following radiation treatment. The changes were dose dependant and progressed over time. Further work is needed to understand the underlying tissue changes and to correlate the observed diffusion changes with late brain malfunctions.

Keywords: White Matter; Grey Matter; Diffusion Tensor Imaging; Radiotherapy; quantitative MRI; Proton Therapy; Photon Therapy; glioma; normal tissue


Publ.-Id: 29101

Calcium binding to a disordered domain of a type III-secreted protein from a coral pathogen promotes secondary structure formation and catalytic activity

Hoyer, E.; Knöppel, J.; Liebmann, M.; Steppert, M.; Raiwa, M.; Herczynski, O.; Hanspach, E.; Zehner, S.; Göttfert, M.; Tsushima, S.; Fahmy, K.; Oertel, J.

Strains of the Gram-negative bacterium Vibrio coralliilyticus cause the bleaching of corals due to decomposition of symbiotic microalgae. The V. coralliilyticus strain ATCC BAA-450 (Vc450) encodes a type III secretion system (T3SS). The gene cluster also encodes a protein (locus tag VIC_001052) with sequence homology to the T3SS-secreted nodulation proteins NopE1 and NopE2 of Bradyrhizobium japonicum (USDA110). VIC_001052 has been shown to undergo auto-cleavage in the presence of Ca2+ similar to the NopE proteins. We have studied the hitherto unknown secondary structure, Ca2+-binding affinity and stoichiometry of the “metal ion-inducible autocleavage” (MIIA) domain of VIC_001052 which does not possess a classical Ca2+-binding motif. CD and fluorescence spectroscopy revealed that the MIIA domain is intrinsically largely disordered. Binding of Ca2+ and other di- and trivalent cations induced secondary structure and hydrophobic packing after partial neutralization of the highly negatively charged MIIA domain. Mass spectrometry and isothermal titration calorimetry showed two Ca2+-binding sites which promote structure formation with a total binding enthalpy of -110 kJ mol-1 at a low micromolar Kd. Putative binding motifs were identified by sequence similarity to EF-hand domains and their structure analyzed by molecular dynamics calculations. The stoichiometric Ca2+-dependent induction of structure correlated with catalytic activity and may provide a “host-sensing” mechanism that is shared among pathogens that use a T3SS for efficient secretion of disordered proteins.

Keywords: metal protein interactions; protein folding; rhizobium; intrinsically disordered protein

Publ.-Id: 29100

Frontiers of applications of Petawatt lasers, Plasma accelerator development in Dresden

Schramm, U.

Discussion on progress of PW laser applications and advanced accelerators of protons and electrons

Keywords: Petawatt laser; laser particle acceleration; LWFA; secondary sources

  • Invited lecture (Conferences)
    SPIE Optics + Optoelectronics, 02.-04.04.2019, Prag, Czech Republic
  • Invited lecture (Conferences)
    JuSPARC Kick-off Workshop, 27.-29.03.2019, Vaals, Niederlande

Publ.-Id: 29099

Laser plasma proton accelerators for therapy ?

Schramm, U.

Workshop discussion on advanced accelerators for therapy.

Keywords: particle cancer therapy; laser acceleration

  • Invited lecture (Conferences)
    2nd ARIES Annual Meeting, 10.-11.04.2019, Budapest, Ungarn

Publ.-Id: 29098

Phonon Magnetochiral Effect

Nomura, T.; Zhang, X.-X.; Zherlitsyn, S.; Wosnitza, J.; Tokura, Y.; Nagaosa, N.; Seki, S.

The magnetochiral effect (MCE) of phonons, a nonreciprocal acoustic propagation arising due to symmetry principles, is demonstrated in the chiral-lattice ferrimagnet Cu2OSeO3. Our high-resolution ultrasound experiments reveal that the sound velocity differs for parallel and antiparallel propagation with respect to the external magnetic field. The sign of the nonreciprocity depends on the chirality of the crystal in accordance with the selection rule of the MCE. The nonreciprocity is enhanced below the magnetic ordering temperature and at higher ultrasound frequencies, which is quantitatively explained by a proposed magnon-phonon hybridization mechanism.


Publ.-Id: 29097

Quantification of the metabolic uptake rate in whole body F-18 FDG PET: a comparison between dynamic and static imaging

van den Hoff, J.; Hofheinz, F.; Weise, R.; Maus, J.; Preuß, R.; Burchert, W.

Dynamic whole body (DWB) FDG PET has become available with the recent introduction of the "flow motion" package by Siemens which offers fully automated generation of parametric images of the metabolic uptake rate K[m]. While this approach is superior to SUV-based quantification, it requires substantially more scan time and reduces patient throughput. On the other hand, the tumor to blood standard uptake ratio (SUR) has outperformed SUV in several clinical studies, which is attributed to a very high correlation between SUR and K[m]. However, direct evidence for this correlation is scarce. Our study compares K[sur], the SUR-derived "static" estimate of K[m], with the Patlak-derived K[m].

Altogether, 12 oncological patients are enclosed and scheduled for DWB PET. Parametric images of K[m] and K[sur] are computed using the vendor provided Patlak procedure and in-house software, respectively. Evaluation of the voxel intensity correlation between both parametric images as well as ROI-based analysis is performed.

So far, 4 patients have been evaluated. K[m] and K[sur] are highly correlated (R^2=0.97) in areas with nonnegligible irreversible uptake (so far we investigated the range K[m]=[0.01,0.07]). K[m] and K[sur] images have very similar image contrast between such areas. Minor contrast differences exist in healthy soft tissue and regions where the Patlak approach is invalid (notably the liver). The relative scale factor between both parametric images is 0.86.

Our results suggest that SUR and K[sur] are proportional surrogates of true K[m]. The unquestionable potential of DWB PET might thus be more relevant for applications beyond oncological FDG PET. To test this conjecture, comprehensive studies in homogeneous patient groups are required in order to compare the prognostic value of K[m] and SUR/K[sur] in the context of survival analysis

  • Lecture (Conference)
    Jahrestagung der DGN, 03.-06.04.2019, Bremen, Deutschland

Publ.-Id: 29096

Quantifizierung von pulmonalen 18F-FDG-PET/CT-Untersuchungen: Vergleich von Standard Uptake Ratio (SUR) und Patlak (Ki)

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

Dynamische PET/CT Scans gefolgt von Patlak Modellierung der 18F-FDG-Aufnahmerate (Ki) ist eine etablierte Methode zur Quantifizierung der Lungenentzündung im tierexp. Modell des akuten Lungenversagens (ARDS), erfordert aber zeitintensive Aufnahmen und erlaubt nur ein begrenztes cranio-caudales FoV. Dyn. PET/CT Scans von Patienten mit Lebermetastasen zeigten gute Korrelationen zwischen Ki und Standard Uptake Ratio (SUR = ROI-SUV / Blut-SUV) [1]. Wir analysierten in einem tierexp. ARDS-Modell, ob stat. PET/CT Messungen und SUR-Analysen alternativ zu dyn. PET/CT und Ki für die Quantifizierung der pulmonalen Inflammation genutzt werden können.

In 14 Schweinen erfolgten nach Induktion eines schweren ARDS sowie nach 24h Beatmung dyn. 18F-FDG-PET/CT Scans und Patlak Ki-Analysen. Anschließende stat. PET/CT Scans (77-81min p.i.) wurden für die Bestimmung von mittleren, zeitkorrigierten SUR-Werte genutzt. SUR- und Ki-Werte wurden für 5 ventro-dorsale ROIs mittels linearer Regression verglichen (Variationskoeffizient, r2). Anhand von Blutproben wurde die Variabilität der arteriellen Inputfunktion (AIF) zwischen Tieren und Messzeitpunkten verglichen.

SUR- und Ki-Werte korrelierten vor und nach 24h Beatmung (r2=0.84 bzw. 0.97). Der zeitliche Verlauf der AIF war zwischen Tieren und Aufnahmezeitpunkten vergleichbar und konnte mittels einer inversen Potenzfunktion beschrieben werden (r2 = 0.99). Die Patlak-Zeit war Zeit-, aber nicht AIF-abhängig, und wies eine geringe Variabilität auf (t=70min: 153.6 ± 13.3min).

Für die Quantifizierung der pulmonalen Inflammation in exp. Studien der Anästhesie können stat. PET/CT Scans und SUR-Analysen alternativ zu dyn. 18F-FDG-PET/CT und Patlak genutzt werden. Dies ermöglicht eine schnellere Datenakquisition, die Erfassung der gesamten Lunge und eine Reduktion der erforderlichen Blutproben. Grundlage der guten Ki-SUR Korrelation bildete die geringe Variabilität des AIF.

  • Lecture (Conference)
    Jahrestagung der DGN, 03.-06.04.2019, Bremen, Deutschland

Publ.-Id: 29095

Validation of an independent prognostic value of the asphericity of FDG uptake in non-small cell cancer patients undergoing treatment in curative intent

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

In patients with non-small cell lung cancer (NSCLC) undergoing treatment with curative intent, the asphericity (ASP) of the primary tumor’s metabolic tumor volume (MTV) has been demonstrated as a prognostic factor. This study aimed at validation in an independent cohort with sufficient sample size.

Retrospective study in 313 NSCLC patients (203 men; median age, 67 [41-87] a) undergoing FDG-PET/CT with the same scanner prior to treatment in curative intent (always including resection of the primary tumor). 137 patients had UICC stage I, 79 patients stage II and 97 patients stage III disease (adenocarcinoma [ADC], 153; squamous cell carcinoma [SCC], 143, other, 17). Delineation of primary tumor MTV with semiautomated background-adapted threshold relative to its SUVmax. Univariable Cox regression for progression-free (PFS) and overall survival (OS) for PET parameters (MTV, ASP, SUVmax, SUVmean), clinical (UICC stage I vs. II vs. III), histological (SCC vs. ADC) and treatment variables (Rx/1 vs. R0 resection, chemotherapy yes/no, radiotherapy yes/no). Multivariable Cox of parameters significant in univariate Cox.

Events (progression, relapse, death) occurred in 169/313 patients, 139 patients died (median follow-up in survivors, 37 months). In multivariable Cox for OS, ASP >33.3% (hazard ratio [HR], 1.53 [95%-confidence interval, 1.02-2.3]), Rx/1 vs. R0 resection (HR, 2.47 [1.5-4.2]) and SCC vs. ADC (HR, 1.53 [1.1-2.2]) were significant. Log-rank test for ASP was significant at any cut-off from 18% upwards. Among separate UICC stages, ASP was only prognostic for OS in stage II (optimal, >19.5%; median OS, 33 vs. 59 months; p<0.01). In multivariable Cox for PFS, ASP >21.2% (HR, 1.75 [1.2-2.5]) and Rx/1 vs. R0 (HR, 2.48 [1.5-4.1]) were significant. Log-rank test for ASP was significant at any cut-off from 10-60%.

ASP was validated as an independent predictor of PFS and OS in NSCLC patients with curative treatment intent. Subdividing UICC stages, ASP remained prognostic in stage II.

  • Lecture (Conference)
    Jahrestagung der DGN, 03.-06.04.2019, Bremen, Deutschland

Publ.-Id: 29094

Interobserver variability of image–derived arterial blood SUV in FDG–PET

Hofheinz, F.; Maus, J.; Zschaeck, S.; Rogasch, J.; Schramm, G.; Oehme, L.; Apostolova, I.; Kotzerke, J.; van den Hoff, J.

The standardized uptake value (SUV) is essentially the only means for quantitative evaluation of static FDG PET. However, the SUV approach has well-known shortcomings which adversely affect the reliability of the SUV as a surrogate of the metabolic rate of glucose consumption. The standard uptake ratio (SUR), i.e. the uptake time corrected ratio of tumor SUV to image-derived arterial blood SUV, has been shown to overcome most of these shortcomings and to increase the prognostic value in comparison to SUV. However, it is unclear, to what extent the SUR approach is vulnerable to observer variability of the required blood SUV (BSUV) determination. The goal of the present work was the investigation of the interobserver variability of image-derived BSUV.

FDG PET/CT scans from 83 patients were included. BSUV was determined by 8 individuals, each applying a dedicated delineation tool for the BSUV determination in the aorta. Altogether 5 different delineation tools were used. With each used tool, delineation was performed for the whole patient group, resulting in 12 distinct observations per patient. Interobserver variability of BSUV determination was assessed using the fractional deviations of the individual observers from the observer-average for the considered patient.

Interobserver variability in the pooled data amounts to SD=2.8% and is much smaller than the intersubject variability of BSUV (SD=16%). Averaged over the whole patient group, deviations of individual observers from the observer average are very small and fall in the range [-0.96,1.05]%. However, interobserver variability partly differs distinctly for different patients (range: [0.7,7.4]%).

The present investigation proofs unambiguously that the image-based manual determination of BSUV in the aorta provides sufficient accuracy and reproducibility for the purposes of the SUR approach. This finding is in line with the already demonstrated superiority of SUR in comparison to SUV in first clinical studies.

  • Lecture (Conference)
    Jahrestagung der DGN, 03.-06.04.2019, Bremen, Deutschland

Publ.-Id: 29093

Die Asphärizität neuroendokriner Tumore in der prätherapeutischen Somatostatinrezeptor-Bildgebung: Ein innovativer Prädiktor für das progressionsfreie Überleben unter Everolimus?

Wetz, C.; Genseke, P.; Pape, U.; Jann, H.; Furth, C.; Kreißl, M.; Hofheinz, F.; Venrito, M.; Stüven, A.; Amthauer, H.

Bei Patienten mit pulmonalen oder gastrointestinalen neuroendokrinen Tumoren (NET) kann der teils nebenwirkungsreiche mTOR-Inhibitor Everolimus das progressionsfreie Überleben (PFS) verlängern. Ziel dieser Studie war die Evaluation der läsionalen Asphärizität (ASP) in der prätherapeutischen Somatostatinrezeptor (SSR)-Bildgebung hinsichtlich einer weiteren Spezifizierung von Patientensubgruppen die von der Therapie im Besonderen profitieren.

Retrospektive, bizentrische Analyse von 30 Patienten (m=17; w=13; medianes Alter, 59 [38-75] Jahre) mit einer prätherapeutischen [111In-DTPA0]octreotid Szintigraphie. Die funktionellen Volumina von bis zu 3 führenden Läsionen je Patient (n=74) wurden mittels halbautomatischer, hintergrundadaptierter Segmentierung erhoben (ROVER, Version 2.1.20) und jeweils die sphärische Heterogenität des SSR-Besatzes - die ASP - berechnet. Für die maximal gemessene ASP je Patient erfolgten Kaplan-Meier-Analysen inklusive log-rank-Tests sowie eine univariate Cox Regression bzgl. des PFS.

Alle 30 Patienten waren unter Everolimus progredient oder entwickelten ein Rezidiv. In der univariaten Analyse erwies sich die ASP [Median, 12,7%; Spannweite, 1,1–43,5] als Prädiktor des PFS (p=0,033; Hazard Ratio [HR], 2,391 je eine Einheit). Patienten mit einer hohen ASP (>14%) zeigten ein medianes PFS von 6,7 Monaten (95%-Konfidenzintervall [CI], 2,1-11,4 Monate) gegenüber 14,4 Monaten (95%-CI, 12,5-16,3 Monate; p=0,028) für eine ASP ≤14%.

Mittels ASP kann im untersuchten Patientenkollektiv eine Prädiktion des PFS erreicht werden. In Bezug auf eine Nutzen-/Risiko-Abwägung zur Indikationsstellung der Everolimusgabe erscheint der Einsatz der prätherapeutischen ASP bzgl. einer optimalen Patientenauswahl bedeutsam; Patienten mit einer ASP >14% hatten ein signifikant kürzeres PFS.

  • Lecture (Conference)
    Jahrestagung der DGN, 03.-06.04.2019, Bremen, Deutschland

Publ.-Id: 29092

Application of Fourier Analysis of Cerebral Glucose Metabolism in Color Induced Long-term Potentiation: A Novel Functional PET Spectroscopy (fPETS) Study in Mice

Njemanze, P. C.; Kranz, M.; Brust, P.

Fourier time series analysis could be used to segregate changes in the ventral and dorsal streams of the visual system in male and female mice. Color memory processes of long-term potentiation and long-term depression could be identified through spectral analysis. We used small animal positron emission tomography and magnetic resonance imaging (PET/MRI) to measure the accumulation of [18F]fluorodeoxyglucose ([18F]FDG) in the mouse brain during light stimulation with blue and yellow filters compared to darkness condition. The mean standardized uptake values (SUV) of [18F]FDG for each stimulus condition was analyzed using standard Fourier analysis software to derive spectral density estimates for each condition. Spectral peaks were identified as originating from the subcortical region (S-peak) by subcortical long-term potentiation (SLTP) or depression (SLTD), and originating from the cortical region (C-peak) by cortical long-term potentiation (CLTP) or depression (CLTD). Luminance opponency occurred at S-peak by SLTP in the dorsal stream in the left visual cortex in male mice. On the other hand, chromatic opponency occurred by wavelength-differencing at C-peak by CLTP in the cortico-subcortical pathways in the ventral stream of the left visual cortex in male mice. In contrast in female mice, during luminance processing, there was resonance phenomenon at C-peak in the ventral stream in the right visual cortex. Chromatic opponency occurred at S-peak by SLTP in the dorsal stream in the right visual cortex in female mice. Application of Fourier analysis improved spatial and temporal resolutions of conventional fPET/MRI methods. Computation of colour processing as a conscious experience has wide range applications in neuroscience and artificial intelligence.

Keywords: Chromatic Opponency; Brain; Light Stimulation; Sex; Asymmetry; Spectroscopy; Memory

  • Open Access Logo Book chapter
    Dr. Goran S. Nikolić, Dr. Dragana Marković-Nikolić: Application of Fourier Analysis of Cerebral Glucose Metabolism in Color Induced Long-term Potentiation: A Novel Functional PET Spectroscopy (fPETS) Study in Mice / Fourier Transforms - Century of Digitalization and Increasing Expectations, London: IntechOpen, 2019, 1-23-1
    DOI: 10.5772/intechopen.85641

Publ.-Id: 29091

Nanomagnetism of Magnetoelectric Granular Thin-Film Antiferromagnets

Appel, P.; Shields, B. J.; Kosub, T.; Hedrich, N.; Hübner, R.; Fassbender, J.; Makarov, D.; Maletinsky, P.

Antiferromagnets have recently emerged as attractive platforms for spintronics applications, offering fundamentally new functionalities compared with their ferromagnetic counterparts. Whereas nanoscale thin-film materials are key to the development of future antiferromagnetic spintronic technologies, existing experimental tools tend to suffer from low resolution or expensive and complex equipment requirements. We offer a simple, high-resolution alternative by addressing the ubiquitous surface magnetization of magnetoelectric antiferromagnets in a granular thin-film sample on the nanoscale using single-spin magnetometry in combination with spin-sensitive transport experiments. Specifically, we quantitatively image the evolution of individual nanoscale antiferromagnetic domains in 200 nm thin films of Cr2O3 in real space and across the paramagnet-to-antiferromagnet phase transition, finding an average domain size of 230 nm, several times larger than the average grain size in the film. These experiments allow us to discern key properties of the Cr2O3 thin film, including the boundary magnetic moment density, the variation of critical temperature throughout the film, the mechanism of domain formation, and the strength of exchange coupling between individual grains comprising the film. Our work offers novel insights into the magnetic ordering mechanism of Cr2O3 and firmly establishes single-spin magnetometry as a versatile and widely applicable tool for addressing antiferromagnetic thin films on the nanoscale.


Publ.-Id: 29090

Modelling high resolution XANES for nuclear materials

Amidani, L.; Pidchenko, I.; Kvashnina, K.

X-ray Absorption Spectroscopy (XAS) is an invaluable tool in nuclear material research, allowing to probe the oxidation state and the local coordination of a selected atomic species. The first part of the spectrum, the X-ray Near Edge Structure (XANES), is less exploited than the Extended X-ray Absorption Fine Structure (EXAFS). However XANES conceals a wealth of information on the electronic structure and the local geometry around the absorber. Nowadays important progresses in the interpretation of XANES have been made thanks to i) the development of dedicated ab-initio codes using powerful computational resources and ii) the use of high resolution XANES, which is especially advantageous for actinides.
We present here an example of how to extracted valuable information from XANES. We performed a systematic study of U L₃ edge XANES for U⁵⁺ and U⁶⁺ in different local coordination. It is well known that the presence uranyl bonds gives a characteristic feature in the post-edge of U L₃ XANES and it has been observed experimentally that this feature shifts to lower energy when going from the uranyl to the uranate coordination. We found that in U⁶⁺ and U⁵⁺ mixed systems the U⁵⁺ in octahedral coordination gives a characteristic shoulder just before the uranyl feature due to the splitting of the 6d DOS from the octahedral crystal field. We think that the shift of the uranyl feature going to uranate configuration indeed points to the presence of U⁵⁺.

  • Lecture (Conference)
    E-MRS spring meeting, 27.-31.05.2019, Nice, France

Publ.-Id: 29089

Modeling XANES of U⁵⁺ and U⁶⁺ in different local coordination geometries

Amidani, L.; Pidchenko, I.; Kvashnina, K.

X-ray Absorption Spectroscopy (XAS) is an invaluable tool in nuclear material research, allowing to probe the oxidation state and the local coordination of selected atomic species. The first part of the spectrum, the X-ray Near Edge Structure (XANES), is less exploited than the Extended X-ray Absorption Fine Structure (EXAFS). However XANES conceals a wealth of information on the electronic structure and on the local geometry around the absorber. What prevents XANES to become a more common technique is the complexity of its analysis, which still gives more qualitative than quantitative information. Nowadays important progresses in the interpretation of XANES have been made thanks to i) the development of dedicated ab-initio codes using powerful computational resources and ii) the use of High Energy Fluorescence Detected (HERFD) XANES, which boosted spectral resolution especially in the case of actinides. These recent developments make the systematic studies based on XANES simulations an invaluable tool to strengthen our understanding of XANES.
In this regards we present a detailed investigation on how the local coordination of U⁵⁺ and U⁶⁺ affects the U L₃ edge HERFD XANES. By simulating a large number of structures containing U⁵⁺ and/or U⁶⁺ in different local coordination geometries we found systematic trends, especially correlated with the presence of longer or shorter U – O bonds. It is well established that the presence of the short uranyl bond shows up in U L₃ edge XANES by the presence of a characteristic post-edge feature [1]. Interestingly, some experimental investigations reported that the uranyl post-edge feature shifts to lower energy when going from the uranyl to the uranate coordination, i.e. identical U – O distances [2,3]. Our systematic investigation confirms that this behavior correlates with the presence of U coordinated with 6 oxygen atoms in a regular octahedron and it is a consequence of the splitting of U 6d Density of States (DOS) induced by the crystal field. The possibility to detect the presence of U⁵⁺ in systems with both U⁵⁺ and U⁶⁺ by HERFD XANES will be discussed on the bases of our systematic investigation.

  • Lecture (Conference)
    49èmes Journées des Actinides, 14.-18.04.2019, Erice, Italy

Publ.-Id: 29088

Plant cell (Brassica napus) response to europium(III) and uranium(VI) exposure

Moll, H.; Sachs, S.; Geipel, G.

Experiments conducted over a period of 6 weeks using Brassica napus callus cells grown in vitro under Eu(III) or U(VI) stress showed that B. napus cells were able to bioassociate both potentially toxic metals (PTM), 762 nmol Eu/gfresh cells and 995 nmol U/gfresh cells. Most of the Eu(III) and U(VI) was found to be enriched in the cell wall fraction. Under high metal stress (200 µM), cells responded with reduced cell viability and growth. Subsequent speciation analyses using both metals as luminescence probes confirmed that B. napus callus cells provided multiple-binding environments for Eu(III) and U(VI). Moreover, two different inner-sphere Eu3+ species could be distinguished. For U(VI), a dominant binding by organic and/or inorganic phosphate groups of the plant biomass can be concluded.

Keywords: uranium; europium; plant cells; luminescence spectroscopy; viability

Publ.-Id: 29087

Numerical investigation on the effects of vortex generators on sub-channel flow in a rod bundle

Tas, S.; Krepper, E.; Unger, S.; Hampel, U.

Spacer grids of fuel assemblies are equipped with vanes, which promote mixing and turbulence within and across the sub-channels and thereby enhance the heat transfer. In this study, we investigated the impact of vortex generating vanes on the downstream flow evolution and heat transfer from the fuel rods by numerical analyses. Simulations were performed with ANSYS CFX. We investigated the turbulence change along the channel in the presence of the vanes depending on vorticity. The use of vanes results in a vortex, in which the vorticity enhances with increasing vane angle. These change induce turbulence kinetic energy variations. Physical conditions for optimum heat transfer along the sub-channel were determined in terms of Nusselt number. The Nusselt numbers of the present simulation were compared with experimental results from literature and a slight over prediction of the simulation compare to the experiment was found.

Keywords: Turbulent flow; Heat transfer; Numerical analysis

  • Lecture (Conference)
    50th Annual Meeting on Nuclear Technology, 07.-08.05.2019, Berlin, Deutschland

Publ.-Id: 29086

Magnetic interactions and spin dynamics in the bond-disordered pyrochlore fluoride NaCaCo2F7

Zeisner, J.; Bräuninger, S. A.; Opherden, L.; Sarkar, R.; Gorbunov, D. I.; Krizan, J. W.; Herrmannsdörfer, T.; Cava, R. J.; Wosnitza, J.; Büchner, B.; Klauss, H. H.; Kataev, V.

We report high-frequency/high-field electron spin resonance (ESR) and high-field magnetization studies on single crystals of the bond-disordered pyrochlore NaCaCo2F7. Frequency- and temperature-dependent ESR investigations above the freezing temperature Tf ∼ 2.4 K reveal the coexistence of two distinct magnetic phases. A cooperative paramagnetic phase, evidenced by a gapless excitation mode, is found along with a spin-glass phase developing below 20 K which is associated with a gapped low-energy excitation. Effective g factors close to 2 are obtained for both modes, in line with pulsed high-field magnetization measurements which show an unsaturated isotropic behavior up to 58 T at 2 K. In order to describe the field-dependent magnetization in high magnetic fields, we propose an empirical model accounting for highly anisotropic ionic g tensors expected for this material and taking into account the strongly competing interactions between the spins which lead to a frustrated ground state. As a detailed quantitative relation between effective g factors as determined from ESR and the local g tensors obtained by neutron scattering [Ross et al., Phys. Rev. B 93, 014433 (2016)] is still sought after, our work motivates further theoretical investigations of the low-energy excitations in bond-disordered pyrochlores.

Publ.-Id: 29085

Reference Database for Photon Strength Functions

Goriely, S.; Dimitriou, P.; Wiedeking, M.; Belgya, T.; Firestone, R.; Kopecky, J.; Krticka, M.; Plujko, V.; Schwengner, R.; Siem, S.; Utsunomiya, H.; Hilaire, S.; Peru, S.; Cho, Y. S.; Filipescu, S. M.; Iwamoto, N.; Kawano, T.; Oblozinsky, P.; Tao, X.; Varlamov, V.; Xu, R.

Photon strength functions describing the average response of the nucleus to an electromagnetic probe are key input information in the theoretical modelling of nuclear reactions and consequently they are highly relevant to a wide range of fields in basic sciences and applications such as nuclear structure, nuclear astrophysics, medical isotope production, fission and fusion reactor technologies, activation analyses and safeguards. They are also sources of information for widely used databases such as the IAEA Reference Input Parameter Library, the evaluated data files, such as ENSDF, EGAF, and the astrophysical reaction databases (e.g. BRUSLIB, STARLIB, REACLIB). In the past two decades, there has been considerable growth in the amount of reaction gamma-ray data measured to determine photon strength functions. Quite often the different experimental techniques lead to discrepant results and users are faced with the dilemma of deciding which (if any) amongst the divergent data they should adopt.

Keywords: Photon strength functions; gamma-ray strength; data base

Publ.-Id: 29084

Flexible magnetoelectronics

Makarov, D.

I will review our activities on shapeable magnetoelectronics. Fabrication and application potential of flexible magnetic field sensors will be in the focus of the talk.

Keywords: flexible electronics; magnetoelectronics

  • Invited lecture (Conferences)
    Nanoforum 2019, 17.05.2019, Linz, Austria

Publ.-Id: 29083

Current status of the PEnELOPE laser system

Albach, D.; Emmanuello, C.; Löser, M.; Siebold, M.; Schramm, U.

We present an update on the development of the PENELOPE laser system currently under construction at the Helmholtz-Zentrum Dresden-Rossendorf, Germany. Pulses from an oscillator are stretched to the nanosecond scale before several amplification stages will boost the energy up to the 150 J level on target. About 150 fs are foreseen at repetition rates of up to 1 Hz, ultimately yielding a peak power of 1 PW.
Our primary objective lies currently on the compression of the amplified pulses on the Joule scale. First tests used a direct compression of the stretched oscillator output (hence a small beam size), while the amplified compression will be performed with the full sized beam. Compressibility of the full scale beam is therefore of major interest. The second target is the improvement of the average power capacity of especially the second to the last amplifiers section. Room temperature operation is the main aim for the close future with lower temperature operation envisioned.

Keywords: laser; diode pumping; ytterbium; CaF2

  • Lecture (others)
    The 11th International Workshop of High Energy Class Diode Pumped Solid State Lasers (HEC-DPSSL), 13.-16.01.2019, Daejeon, Süd-Korea

Publ.-Id: 29082

Microscopic Nature of the First-Order Field-Induced Phase Transition in the Strongly Anisotropic Ferrimagnet HoFe5Al7

Gorbunov, D. I.; Strohm, C.; Henriques, M. S.; van der Linden, P.; Pedersen, B.; Mushnikov, N. V.; Rosenfeld, E. V.; Petricek, V.; Mathon, O.; Wosnitza, J.

We report on x-ray magnetic circular dichroism experiments in pulsed fields up to 30 T to follow the rotations of individual magnetic moments through the field-induced phase transition in the ferrimagnet HoFe5Al7. Near the ground state, we observe simultaneous stepwise rotations of the Ho and Fe moments and explain them using a two-sublattice model for an anisotropic ferrimagnet with weak intersublattice exchange interactions. Near the compensation point, we find two phase transitions. The additional magnetization jump reflects the fact that the Ho moment is no longer rigid as the applied field acts against the intersublattice exchange field.


Publ.-Id: 29081

Inductive Heating Using a High-Magnetic-Field Pulse to Initiate Chemical Reactions to Generate Composite Materials

Zimmerer, C.; Salazar Mejia, C.; Utech, T.; Arnhold, K.; Janke, A.; Wosnitza, J.

Induction heating is efficient, precise, cost-effective, and clean. The heating process is coupled to an electrically conducting material, usually a metal. As most polymers are dielectric and non-conducting, induction heating is not applicable. In order to transfer energy from an electromagnetic field into polymer induction structures, conducting materials or materials that absorb the radiation are required. This report gives a brief overview of induction heating processes used in polymer technology. In contrast to metals, most polymer materials are not affected by electromagnetic fields. However, an unwanted temperature rise of the polymer can occur when a radio frequency field is applied. The now available high-field magnetic sources provide a new platform for induction heating at very low frequencies, avoiding unwanted thermal effects within the material. Using polycarbonate and octadecylamine as an example, it is demonstrated that induction heating performed by a magnetic-field pulse with a maximum flux density of 59 T can be used to initiate chemical reactions. A 50 nm thick Ag loop, with a mean diameter of 7 mm, placed in the polymer-polymer interface acts as susceptor and a resistive heating element. The formation of urethane as a linker compound was examined by infrared spectroscopic imaging and differential scanning calorimetry.

Publ.-Id: 29080

Upgrade of the ERDA setup at the HZDR 6 MV tandem accelerator

Julin, J.; Aniol, R.; Munnik, F.; Heller, R.

During 2019 the elastic recoil detection (ERD) beamline attached to the 6 MV tandem accelerator at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has been modernized completely. Since many of the vacuum and electrical components of the previous setup had been showing signs of aging or failing, the decision was made to replace these and rebuild the setup. Additionally, during 2018 the construction of a new time-of-flight spectrometer for ERD was also completed, and it was seen that the ERD setup as a whole would benefit from a combination of a new chamber, mechanical supports and a control system.

The new setup incorporates the previously used Z-separating Bragg ionization chamber (BIC), which is typically used with 43 MeV 35Cl beam. It is connected to a port on the chamber giving 30 degree scattering angle. The time-of-flight branch is attached to the other side of the chamber at a 40 degree scattering angle. Various beams up to an energy of 20 MeV for 35Cl or 30 MeV for 63Cu can be used, or even higher if hydrogen depth profiling is not necessary. The detector branches can be operated independently of each other, minimizing downtime due to breakdowns of detectors or maintenance. This is exceedingly important since the ion beam center (IBC) is a user facility and the beam time for the 6 MV accelerator is allocated based on proposals and scheduled long in advance to the actual measurement.

This presentation will give an overview of the new ERD setup, including specifics on the design of the new chamber, control and vacuum systems, detectors and data acquisition as well as some experimental data, performance figures and experiences gained during the construction of the setup.

Keywords: IBA; ERDA

  • Poster
    ECAART13 - 13th European Conference on Accelerators in Applied Research and Technology, 05.-10.05.2019, Split, Croatia

Publ.-Id: 29078

The influence of orifice types on the flow structure of a bubble-driven liquid-metal flow in a horizontal magnetic field

Richter, T.; Wondrak, T.; Eckert, K.; Eckert, S.; Odenbach, S.

Bubble plumes play an important role in metallurgical applications in order to stir and refine melts. Static electromagnetic fields allow a contactless control of those bubble plumes. However, for a tailored control the effects of the magnetic field to the bubble motion are important.
It is well known, that a bubble plume rising in a bulk of liquid metal has an axially symmetric shape. But the motion becomes asymmetric, when a static magnetic field (B) is applied in horizontal direction to the liquid metal. The direction of the flow parallel to B is upward, while the direction of the flow perpendicular to B is downward close to the plume.
Measurements of Zhang et al. of a bubble plume in the liquid metal GaInSn, emerging from a single orifice in a cylindrical vessel by the usage of the ultrasound Doppler velocimetry (UDV), confirmed this asymmetric motion. They observed traveling vortex structures in the direction perpendicular to B for moderate Hartmann numbers (Ha). This vortex structure became frozen, when high Ha were reached.
The focal point of this paper is the measurement of the bubble features in a similar container instead of measuring the flow of the liquid metal. The ultrasound transit time technique (UTTT) is employed, which was previously utilized to detect and analyze the motion of single bubbles rising in GaInSn. In comparison to the previous setup, a square vessel instead of round one is used and a sharp injection needle instead of a polished one was placed at the bottom of the vessel. During these new measurements, almost contradictory results are obtained: for small Ha numbers static vortex structures, which were deduced from the bubble motion, were observed, while traveling vortices were measured, when higher Ha were reached. The cause of this discrepancy is presumably the sharp orifice in the new setup, because the different cross section of the tank would rarely influence the motion.
We want to analyze the influence of the orifice type, by the comparison of two different shaped orifices, on the flow behavior in a new measurement campaign, where the bubble motion and the flow structure are detected by UTTT and UDV.

Keywords: ultrasound transit time technique; liquid metal; bubble plume

  • Lecture (Conference)
    11th PAMIR international conference fundamental and applied MHD, 01.-05.07.2019, Reims, France
  • Contribution to proceedings
    11th PAMIR International Conference Fundamental and Applied MHD, 01.-05.07.2019, Reims, France
    The influence of orifice types on the flow structure of a bubble-driven liquid-metal flow in a horizontal magnetic field

Publ.-Id: 29077

Radiopharmakologische Charakterisierung eines neuen Chelators konjugiert an das PSMA-Bindungsmotiv Glutamat-Urea-Lysin

Sihver, W.; Böhme, J.; Wodtke, R.; Walther, M.; Steinbach, J.; Pietzsch, J.; Pietzsch, H.-J.

Molekulare Bildgebung mittels PET bzw. SPECT ist in der Krebsforschung ein unverzichtbares Werkzeug geworden, da diese genaue Informationen zu molekularen Eigenschaften von Tumoren liefern kann. Auf der Suche nach vielseitig einsetzbaren Chelatoren wurde für die Radionuklidmarkierung zielgerichteter PET/SPECT-Liganden ein Cyclohexandiamin-Triazol-Chelator entwickelt und an das Bindungsmotiv des prostata-spezifischen Antigens (PSMA) Glutamat-Urea-Lysin gekoppelt (Ligand in Abb. 1 = L). Dieses Motiv ist bekannt für seine gute Affinität an PSMA [1], welches bei verschiedenen Tumorentitäten stark exprimiert wird [2–4].
Ziel der Untersuchung war es, das radiopharmakologische Potential von L nach Radiomarkierung mit 68Ga, 111In und 18F bezüglich der Bindungseigenschaften und Zell-Internalisierung abzuschätzen und mit dem ‚Gold-Standard‘ PSMA-617 (177Lu- oder 64Cu-markiert) zu vergleichen.
Für den nichtmarkierten Liganden L wurde in Kompetitionsassays versus [177Lu]Lu-PSMA-617 eine etwas geringere Affinität als für PSMA-617 ermittelt. Sättigungsanalysen von [68Ga]Ga-L, [111In]In-L und [18F]F-L an LNCaP-Zellhomogenaten ergaben ähnliche Affinitäten (Kd 18–30 nM), die wiederum etwas niedriger waren als die von [177Lu]Lu-PSMA-617 (11 nM). Die Ergebnisse der Internalisierungsversuche zeigten eine stärkere Aufnahme von [64Cu]Cu-PSMA-617 in LNCaP-Zellen als vom verschieden radiomarkierten L.
Mit dem Konjugat L konnten nach erfolgreicher Radiomarkierung mit 68Ga, 111In und 18F vielversprechende Bindungseigenschaften gegenüber PSMA bestimmt werden. Die Vielseitigkeit dieses Chelators bietet die Möglichkeit mit entsprechendem Radionuklid sowohl für PET (68Ga, 18F) als auch für SPECT (111In) einsetzbar zu sein.


[1] K. Kopka, J. Nucl. Med. 2017, 58,17S. [2] H.R. Kulkarni, Br. J. Radiol. 2018, 91,20180308. [3] Y. Tolkach, Breast Cancer Res.Treat. 2018, 169,447. [4] M.C. Haffner, Hum.Pathol. 2009, 40,1754.

  • Lecture (Conference)
    Radiopharmakologische Charakterisierung eines neuen Chelators konjugiert an das PSMA-Bindungsmotiv Glutamat-Urea-Lysin /GDCh Nuklearchemie, 25.-27.09.2019, Dresden, Deutschland

Publ.-Id: 29076

Nature and Surface Interactions of Sulfur-Containing Deposits on V2O5-WO3/TiO2- Catalysts for SCR-DeNOx

Rammelt, T.; Kuc, A.; Böhm, J.; Heine, T.; Gläser, R.

Sulfur-containing deposits form on a monolithic V2O5-WO3/TiO2 (VWT) catalyst during SCR-DeNOx with NH3 at 473 and 523 K and pressures up to 500 kPa in the presence of SO2 with sulfate contents of 1.7 to 13.0 wt.-%. Using TGA and DRIFTS, these deposits are determined to be mainly NH4HSO4 for SCR temperatures > 523 K. At lower temperatures, (NH4)2SO4 is formed. The thermal stability of NH4HSO4 supported on different transition metal oxides including V2O5, WO3, TiO2, MoO3 and Al2O3 varies with decomposition temperatures from 620 to 820 K. Using DFT calculations, it is show that the thermal stability of supported NH4HSO4 is mainly determined by hydrogen bonding of the HSO4- anions with the metal oxide surface. Increasing electronegativity of the metal atoms of the support oxide leads to weakening of the S-O bonds in the HSO4- anions and to lower decomposition temperatures of the supported NH4HSO4.


Publ.-Id: 29075

Selective CO2 Electroreduction to Ethylene and Multicarbon Alcohols via Electrolyte-Driven Nanostructuring

Gao, D.; Sinev, I.; Scholten, F.; Arán-Ais, R. M.; Divins, N. J.; Kvashnina, K.; Timoshenko, J.; Roldan Cuenya, B.

The production of multicarbon products (C2+) from CO2 electroreduction reaction (CO2RR) is highly desirable for storing renewable energy and reducing carbon emission. Here we report the electrochemical synthesis of CO2RR catalysts that are highly selective for C2+ products via electrolyte-driven nanostructuring. Nanostructured Cu catalysts synthesized in the presence of specific anions can selectively convert CO2 to ethylene and multicarbon alcohols in aqueous 0.1 M KHCO3 solution, with the iodine-modified catalyst displaying the highest Faradaic efficiency of ~80% and partial current density of ~34 mA cm−2 for C2+ products at −0.9 V vs RHE. Operando X-ray absorption spectroscopy and quasi in situ X-ray photoelectron spectroscopy measurements revealed that the high C2+ selectivity of these nanostructured Cu catalysts can be mainly attributed to their nanoporous structure, presence of subsurface oxygen and Cu+ species, and the adsorbed halides. This work provides new insight into the parameters that should be tuned in order to rationally design C2+-selective CO2RR catalysts.

Publ.-Id: 29074

Predicting late magnetic resonance image changes in glioma patients after proton therapy

Eulitz, J.; Troost, E. G. C.; Raschk, F.; Schulz, E.; Lutz, B.; Dutz, A.; Löck, S.; Wohlfahrt, P.; Enghardt, W.; Karpowitz, C.; Krause, M.; Lühr, A.


Proton radiation therapy is an effective treatment for glioma patients. To exploit its full potential, a better description of regional differences in radiation response within the brain is required. In this study, we present a model for predicting magnetic resonance (MR) image changes in glioma patients that considers the variability in proton relative biological effectiveness (RBE) as well as the regional susceptibility of brain tissue to radiation damage.

Material and methods:

Six glioma patients treated with adjuvant proton radio(chemo)therapy showed contrast enhancement on follow-up T1-weighted MR imaging corresponding to treatment-related changes. Physical dose and linear energy transfer (LET) were obtained from high-precision Monte-Carlo simulations. The periventricular region (PVR) was contoured as a 4 mm expansion around the ventricles. Correlations between the image changes and dose, LET, and the PVR were evaluated voxel-wise in univariable and multivariable logistic regression analyses. Model performance was assessed by the area under the curve (AUC) using leave-one-out cross validation. The tolerance dose TD50, at which 50% of the tissue voxels show toxicity was interpolated from the model and used for RBE estimation.


The spatial distribution of MR image changes in the brain was highly non-uniform and correlated poorly with the considered predictors in univariable analysis. Multivariable modelling with either only dose and LET or PVR as third predictor revealed AUC values of 0.89 and 0.92, respectively. TD50 decreased with increasing LET and the modelled RBE was found to vary between 0.9 and 2.3. No relevant difference in model performance was found for track- or dose-averaged LET.


The strong correlation of MR image changes with dose, LET, and the PVR demonstrates the relevance of non-uniform dose response models. A larger patient cohort including patients without image changes will be used to validate the clinically observed indication of a variable proton RBE.

Keywords: Proton Therapy; Glioma; Variable RBE; MR image changes

Publ.-Id: 29073

Performance Analysis for Large Scale GPU Applications and DL Frameworks

Juckeland, G.; Henschel, R.

Get your hands on the latest versions of Score-P and Vampir to profile the execution behavior of your large-scale GPU-Accelerated applications. See how these HPC community tools pick up as other tools (such as NVVP) drop off when your application spans multiple compute nodes. Regardless of whether your application uses CUDA, OpenACC, OpenMP or OpenCL for acceleration, or whether it is written in C, C++, Fortran or Python, you will receive a high-resolution timeline view of all program activity alongside the standard profiles to identify hot spots and avenues for optimization. The novel Python support now also enables performance studies for optimizing the inner workings of deep learning frameworks.

  • Lecture (Conference)
    GPU Technology Conference 2019, 17.-21.03.2019, San Jose, CA, USA

Publ.-Id: 29070

The dominating mechanisms for the formation of solute-rich clusters in steels under irradiation

Castin, N.; Bonny, G.; Bakaev, A.; Bergner, F.; Domain, C.; Hyde, J. M.; Messina, L.; Radiguet, B.; Riddle, N.; Malerba, L.

The formation of nano-sized, coherent, solute-rich clusters (NSRC) is known to be an important factor causing the degradation of the macroscopic properties of steels under irradiation. The mechanisms driving their formation are still debated. This work focuses on low-Cu reactor pressure vessel (RPV) steels, where solute species are generally not expected to precipitate. We rationalize the processes that take place at the nanometer scale under irradiation, relying on the latest theoretical and experimental evidence on atomic-level diffusion and transport processes. These are compiled in a new model, based on the object kinetic Monte Carlo (OKMC) technique. We evaluate the relevance of the underlying physical assumptions by applying the model to a large variety of irradiation experiments. Our model predictions are compared with new experimental data obtained with atom probe tomography and small angle neutron scattering, complemented with information from the literature. The results of this study reveal that the role of immobilized self-interstitial atoms (SIA) loops dominates the nucleation process of NSRC.

Keywords: Hardening; Embrittlement; Steel; Modelling

Publ.-Id: 29069

Inter-observer variability in target delineation increases during adaptive treatment of head-and-neck and lung cancer

Apolle, R.; Appold, S.; Bijl, H. P.; Blanchard, P.; Bussink, J.; Faivre-Finn, C.; Khalifa, J.; Laprie, A.; Lievens, Y.; Madani, I.; Ruffier, A.; de Ruysscher, D.; van Elmpt, W.; Troost, E. G. C.

Inter-observer variability (IOV) in target volume delineation is a well-documented source of geometric uncertainty in radiotherapy. Such variability has not yet been explored in the context of adaptive re-delineation based on imaging data acquired during treatment. We compared IOV in the pre- and mid-treatment setting using expert primary gross tumour volume (GTV) and clinical target volume (CTV) delineations in locoregionally advanced head-and-neck squamous cell carcinoma (HNSCC) and (non-)small cell lung cancer [(N)SCLC].

Materials and Methods
Five and six observers participated in the HNSCC and (N)SCLC arm, respectively, and provided delineations for five cases each. Imaging data consisted of CT studies partly complemented by FDG-PET and was provided in two separate phases for pre- and mid-treatment. Global delineation compatibility was assessed with a volume overlap metric (the Generalised Conformity Index), while local extremes of IOV were identified through the standard deviation of surface distances from observer delineations to a median consensus delineation. Details of delineation procedures, in particular GTV to CTV expansion and adaptation strategies, were collected through a questionnaire.

Volume overlap analysis revealed a worsening of IOV in all but one case per disease site, which failed to reach significance in this small sample (p-value range 0.063- 0.125). Changes in agreement were propagated from GTV to CTV delineations, but correlation could not be formally demonstrated. Surface distance based analysis identified longitudinal target extent as a pervasive source of disagreement for HNSCC. High variability in (N)SCLC was often associated with tumours abutting consolidated lung tissue or potentially invading the mediastinum. Adaptation practices were variable between observers with fewer than half stating that they consistently adapted pre-treatment delineations during treatment.

IOV in target volume delineation increases during treatment, where a disparity in institutional adaptation practices adds to the conventional causes of IOV. Consensus guidelines are urgently needed.

Keywords: Target volume delineation; Inter-observer variability; Adaptive radiotherapy; Head-and-neck squamous cell carcinoma; (Non-)small cell lung cancer


Publ.-Id: 29068

Einfluss von Protonen-Reichweiteunsicherheiten auf LET-Verteilungen am Beispiel von Hirntumor-Patienten

Hahn, C.; Peters, N.; Wohlfahrt, P.; Richter, C.; Eulitz, J.; Enghardt, W.; Lühr, A.

Erste klinische Evidenz zeigt, dass die relative biologische Wirksamkeit (RBW) von Protonen auch vom linearen Energietransfer (LET) bestimmt wird. Die patientenspezifische LET-Verteilung folgt aus der Eindringtiefe der Protonenstrahlen und wird daher unmittelbar von Reichweiteunsicherheiten beeinflusst. Diese Studie quantifiziert den Einfluss von Reichweiteunsicherheiten auf LET-Verteilungen im klinischen Zielvolumen (CTV) und angrenzenden Risikoorganen am Beispiel von Hirntumor-Patienten.

Material & Methoden
Für jeden Patienten wurden zwei nominelle, robust-optimierte Bestrahlungspläne mit Pencil-Beam-Scanning unter Verwendung von Single-Field-Uniform-Dose und Multi-Field-Optimization erstellt. Dabei wurde jeweils ein Simultan-Integrierter-Boost mit zwei Einstrahlrichtungen geplant. Das Protonenbremsvermögen jedes Voxels folgte direkt aus dem Dual-Energy-CT-Scan für die Therapieplanung. Systematische Reichweiteunterschiede wurden durch Skalierung des Bremsvermögens erzeugt. Die Bestrahlungspläne wurden mittels Monte-Carlo-Methode für drei Reichweiteszenarien (nominell, ±3.5%) simuliert und der dosisgemittelte LET voxelweise bestimmt (RayStation, Forschungsversion 5.99.50). Die Auswertungen der LET-Differenzen erfolgte voxelweise, organspezifisch und auf einem Signifikanzniveau von 5% (zweiseitiger t-Test).

Der mittlere LET im Zielvolumen änderte sich weder signifikant durch die simulierten Reichweiteunsicherheiten noch durch die verwendete Planungsstrategie. Gemittelt über Patienten, Planungsstrategie und Reichweiteszenarien betrug der mittlere LET (±Standardabweichung) im CTV 2.78 (±0.07) keV/µm. Im Vergleich zum CTV war der mittlere LET in Risikoorganen signifikant erhöht. Reichweiteunsicherheiten führten innerhalb einer Planungsstrategie patientenspezifisch zu einer Veränderung des mittleren LET um bis zu 0.70 keV/µm (rechter Sehnerv) bzw. 0.38 keV/µm (Hirnstamm). Die Reichweiteunsicherheiten führten zu relevanten Änderungen der LET-Varianz in angrenzenden Risikoorganen mit LET-Maxima bei einzelnen Patienten, z.B. im Hirnstamm (maximale Dosis von 51.8 Gy(RBW)) oder im rechten Sehnerv (53.6 Gy(RBW)).

Die Reichweiteunsicherheit der Protonentherapie bei Hirn-Tumor-Patienten beeinflusste die LET-Verteilungen in Risikoorganen, aber nicht im Zielvolumen. Beobachtete hohe, lokale LET-Varianzen sowie LET-Maxima in Risikoorganen könnten zu einer erhöhten biologischen Wirksamkeit führen und bei Dosen nahe dem Grenzwert unerwartete Normalgewebskomplikationen hervorrufen.

  • Lecture (Conference)
    50. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik, 18.-21.09.2019, Stuttgart, Deutschland

Publ.-Id: 29067

Degradation of Cu-bearing uranyl As-P micromineral phases from Krunkelbach uranium deposit, Southern Germany

Pidchenko, I.; Bauterns, S.; Amidani, L.; Kvashnina, K. O.

The abandoned Krunkelbach uranium (U) mine, Southern Germany, with 2-3 km surrounding area represents a unique natural analogue site with accumulation of U minerals suitable for investigations of potential mobilization-immobilization processes expected in a real spent nuclear fuel repository. A specific feature of the site is the occurrence of more than forty secondary U minerals, from mixed redox U oxy-hydroxides to alkaline metal uranyl silicates, thus representing a wide scale of U ore weathering events. In this work the combination of synchrotron and laboratory techniques is used to unveil U speciation and micro heterogeneities in U phases accumulated on granitic rock outcrop from U deposit area. Available data on the age of the secondary U mineralization indicates that oxidizing processes at the site started some 340,000 years ago and continues up to date. Several phases close to Cu(UO2)2(PO4)2-x(AsO4)x·8H2O are identified on 1×2 mm2 area with presumably older, more evenly distributed Cu(UO2)2(SiO3OH)2·6H2O and (Fe, Ba, Pb)(UO2)2(WO4) (OH)4·12H2O, mineralization. Based on a multi-technique investigation 10-200 µm Cu(UO2)2(PO4)2-x(AsO4)x·8H2O particles with widely varying As-P content are analyzed. The evidences of a degradation occurred on some zones on the selected crystals are found associated with higher As and decreased P content. This observation can be apparently attributed to different degradation properties of the mixed As-P phases depending on As-P ratio and originate from different solubility properties of Cu(UO2)2(PO4)2·8H2O and Cu(UO2)2(AsO4)2·8H2O species. The conditions for preferential formation of As rich Cu(UO2)2(XO4)2·8H2O [X=As, P] phases and its possible role on U transport in environment under oxidizing conditions are discussed.

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

Publ.-Id: 29066

Kuramoto Model on KKI18 connectome

Ódor, G.; Kelling, J.

Results of fourth-order Runge--Kutta integration of the first-order Kuramoto model in brain connectome graph.

  • Awr.dat.gz : connectome graph
  • Awri.dat.gz : connectome graph with 5% inhibitory links
  • ccdata.tgz , sredata.tgz : simulations data for different configurations
    (averages at top-level, single runs in folders)
    • eERll*.dat: cube graph with random long-range links
    • o.ocp-kur_{lambda}_*.dat: connectome with coupling lambda
    • o.ocp-kur_{lambda}I_*.dat: connectome with inhibitory links, coupling lambda
    • elo-Thr: smoothed probability distributions of avalance times
  • awr.tgz : simulation data for connectome graphs sorted by parameters
    • structure: [connectome]/norm_[norm]/dt_[dt]/lam_[lam]/
    • connectomes:
      • Awr: see above
      • AwrC: AwrC.dat.gz (Awr withough disconnected components)
      • Awri10: Awri10.dat.gz (10% inhbibitory)
      • Awri20: Awri20.dat.gz
      • Awri5: see Awri above
      • AwriL5_s23: AwriL5_s23.dat.gz (Awri5 with different random sites flipped)
      • AwriN5_s23_max2000: AwriN5_s23_max2000.dat.gz (Awri5 with different random sites flipped, only site with <=2000 connections flipped)

Keywords: Kuramoto Model; Graph; Synchronization

Related publications

  • Reseach data in the HZDR data repository RODARE
    Publication date: 2019-03-14
    DOI: 10.14278/rodare.120
    License: CC-BY-SA-4.0


Publ.-Id: 29065

Liquid Metal Model Experiments for Continuous Casting of Steel Under the Influence of Magnetic Fields

Schurmann, D.; Glavinić, I.; Timmel, K.; Willers, B.; Eckert, S.

Magnetic fields are widely applied in the continuous casting process to modify the flow pattern in the mold and thereby improve the quality of the semi-finished product. While the use of Electromagnetic Brakes (EMBr) is common in slab casting, Electromagnetic Stirring (EMS) is mainly applied in bloom and billet casting and recently also in slab casting. Due to the harsh conditions in the real casting process, model experiments in cold liquid metals enable accurate measurements of velocity fields, surface oscillations, gas bubble characteristics, etc. These models improve understanding the effects of electromagnetic actuators and provide data to validate numerical models.

We present experimental results obtained in a model of a continuous caster, the Mini-LIMMCAST facility, where the velocity field is measured by Ultrasound Doppler Velocimetry (UDV). Results of experiments conducted with EMS in a round bloom geometry as well as experiments with EMBr in slab geometries are presented.

Keywords: Model Experiments; Ultrasound Doppler Velocimetry; Continuous Casting; Electromagnetic Brake; Electromagnetic Stirring

  • Contribution to proceedings
    8th International Conference on Modeling and Simulation of Metallurgical Processes in Steelmaking (STEELSIM2019), 13.-15.08.2019, Toronto, Ontario, Canada, 620-627
    DOI: 10.33313/503/065
  • Lecture (Conference)
    8th International Conference on Modeling and Simulation of Metallurgical Processes in Steelmaking (STEELSIM2019), 13.-15.08.2019, Toronto, Ontario, Kanada

Publ.-Id: 29064

A spectroscopic investigation of Eu3+ incorporation in LnPO4 (Ln = Tb, Gd1–xLux, x = 0.3, 0.5, 0.7, 1) ceramics

Huittinen, N.; Lösch, H.; Hirsch, A.; Holthausen, J.; Peters, L.; Xiao, B.; Neumeier, S.; Schmidt, M.

In recent years, rare-earth orthophosphates LnPO4 have attracted attention as potential hosts for the immobilization of specific radioactive waste streams.
In the present work, the incorporation of Eu3+ in LnPO4 host materials predominantly having the xenotime structure has been investigated on the molecular level. As host cations we used Tb and Lu as well as a solid solution series of Gd1–xLuxPO4 (x = 0.3, 0.5, 0.7). The site selective laser luminescence spectroscopy (TRLFS) technique was applied to study the distribution of Eu3+ in the synthetic xenotime phases, while PXRD and Raman spectroscopy were used for bulk structural investigations direct after synthesis and after one year of storage at ambient conditions.
The PXRD patterns of the solid solution series show the formation of a single xenotime phase up to a substitution of x = 0.5 both before and after aging. The TRLFS emission spectra also show that Eu3+ is substituted for the host cation site in the xenotime hosts. After one year, the emission spectra show a broad dominant signal between the transitions regions of the 7F1‒ and 7F2‒bands, and the luminescence signal no longer corresponds to Eu3+‒incorporation in a xenotime environment, only. These changes indicate a time-dependent change in the local structure of the europium dopant. Based on these observations we suggest an exclusion of Eu3+ from the crystal structure and subsequent migration of the cation to the grain boundaries during aging. The migration of Eu3+ in void spaces through the crystal structure could be responsible for the additional signals in the emission spectra, while the narrow void space forces an overlap between Eu3+ and oxygen atomic orbitals, resulting in the broad signal between the 7F1‒ and 7F2‒bands.
The segregation of Eu3+ to grain boundaries after a relatively short aging in the xenotime materials, indicates that xenotime ceramics will not serve as a suitable waste form for trivalent actinides from high–level nuclear waste.

  • Lecture (Conference)
    27th Annual Meeting of the German Crystallographic Society (DGK), 25.-28.03.2019, Leipzig, Germany

Publ.-Id: 29063

Protonentherapie von Lungentumoren: Logfile-basierte Dosisrekonstruktion zur klinischen Implementierung des Pencil-Beam-Scanning-Verfahrens

Spautz, S.; Meijers, A.; Jakobi, A.; Thiele, J.; Knopf, A.; Troost, E. G. C.; Richter, C.; Stützer, K.

Bei der Protonentherapie von Lungentumoren mittels Pencil-Beam-Scanning (PBS) kann der Interplay-Effekt aus Protonenstrahl- und Zielvolumenbewegung zu Dosisabweichungen führen. Ob klinisch relevante Dosisparameter eingehalten werden, ist nicht vorhersehbar, weshalb PBS für Lungentumore in unserem Institut noch nicht klinische angewendet wird. Mit dieser Arbeit kann im Rahmen der Qualitätssicherung die tatsächlich applizierte Dosis nach jeder Fraktion rekonstruiert werden. Dies soll zunächst für die PBS-Bestrahlung von Patienten in freier Atmung, ohne Bewegungskompensation und mit Tumorbewegungen unter 5mm angewendet werden, da der Interplay-Effekt-Einfluss bei diesen Amplituden gering ist.
Material und Methoden
Die Dosisrekonstruktion erfolgt skript-basiert im Planungssystem Raystation (RaySearch Laboratories AB, Schweden). Durch Kombination der Maschinen-Logfiles der Protonen-Bestrahlungsanlage (IBA, Belgien), welche die Spotpositionen und applizierten Monitoreinheiten während der Bestrahlung mit einer zeitlichen Auflösung von 250 μs enthalten, der simultan gemessenen Atemkurve des Patienten (ANZAI, Japan) und den wöchentlichen 4D-CTs (Siemens Somatom Definition AS, Deutschland) werden alle Spots zeitlich den entsprechenden 4D-CT Atemphasen zugeordnet. Die daraus errechneten Dosisverteilungen pro Atemphase werden auf ein Referenz-CT deformiert, auf welchem die akkumulierte Dosis nach jeder Fraktion bewertet werden kann. (Abb.1)
Das Verfahren wurde an der Universitätsprotonentherapie Dresden (UPTD) implementiert und an klinischen Datensätzen eines ausgewählten Patienten getestet. Die Phasenaufteilung der Atemkurve erfolgt, konform zum Algorithmus des 4D-CTs, amplitudenbasiert (Abb.2). Pro Fraktion benötigt die Dosisnachberechnung etwa 10 min und ist somit praktikabel im klinischen Arbeitsablauf einsetzbar.
Derzeit wird die Methode experimentell an einem dynamischen Thorax-Phantom (CIRS, USA) validiert und die zeitliche Synchronisierung von Maschinen-Logfiles und Atemkurve überprüft. Die Behandlung erster Patienten mit diesem Verfahren ist für die zweite Hälfte dieses Jahres geplant.
Mit der vorgestellten Methode ist es möglich, die applizierte Dosis nach jeder Fraktion zu rekonstruieren und die akkumulierte Dosis über die gesamte Behandlungsdauer zu kontrollieren. Somit können durch anatomische Änderungen und den Interplay-Effekt bedingte Dosisabweichungen erkannt und benötigte Schritte wie Planadaptionen eingeleitet werden.

  • Lecture (Conference)
    50. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik, 18.-21.09.2019, Stuttgart, Deutschland

Publ.-Id: 29062

Exploration of Proton Bunch Monitoring for In-vivo Range Verification in Proton Therapy

Permatasari, F.; Römer, K.; Werner, T.; Wagner, A.; Pausch, G.; Kögler, T.

The accuracy of proton therapy is basically delimited by range uncertainties. In order to fully exploit the benefit of proton therapy, real-time range verification is needed. Prompt gamma rays, produced during the deceleration of protons in tissue, allow assessing the proton range indirectly. Prompt gamma-ray timing (PGT) utilizes measured time distributions of prompt gamma rays for estimating the beam range [1-4]. At the given therapy facility, however, the accuracy of range determination is affected by drifts of the proton bunch timing (or phase) with respect to the cyclotron radiofrequency, and by the proton bunch width. To counter this limitation, a proton bunch monitor (PBM) has to be introduced.

Materials & Methods
The coincident detection of protons elastically scattered out of a thin target allows measuring phase and width of the proton micro-bunches [3]. Two CeBr3 scintillation detectors coupled with PGT electronics [4] were employed for these measurements. Alternatively, scintillating fibers placed in the beam halo have also been studied.

The applicability of standard PGT detectors and electronics [4] for accurate bunch phase and width measurements has been demonstrated. The detection of beam-halo protons with scintillating fibers seems to be a feasible alternative for bunch phase monitoring at higher sampling rates. Quantitative analysis are still ongoing.

Alternative proton bunch monitoring approaches have been investigated to assess beam parameters necessary for range verification by means of the PGT method. An appropriate PBM would complete the current PGT detection system.

This work has been supported by StrahlenSchutzSeminar in Thüringen e.V.

[1] C. Golnik et al., Phys. Med. Biol. 59 (2014) 5399
[2] F. Hueso-González et al., Phys. Med. Biol. 60 (2015) 6247
[3] J. Petzoldt et al., Phys. Med. Biol. 61 (2016) 2432
[4] T. Werner et al., Phys. Med. Biol. accepted (2019)

Keywords: proton therapy; range verification; prompt gamma-ray; PGT

  • Lecture (Conference)
    50. Jahrestagung der DGMP, 19.-21.09.2019, Stuttgart, Deutschland

Publ.-Id: 29061

First-in-man validation of CT-based stopping-power prediction using prompt-gamma-based range verification

Berthold, J.; Khamfongkhruea, C.; Petzoldt, J.; Thiele, J.; Hölscher, T.; Wohlfahrt, P.; Pausch, G.; Janssens, G.; Smeets, J.; Richter, C.

Currently, the uncertainty in CT-based range prediction is substantially impairing the accuracy of particle therapy. Improvements like a determination of stopping-power ratio (SPR) from dual-energy CT (DECT) have been proposed. However, a validation of range prediction in patients has not been achieved by any means. Here, we present the first verification of proton range prediction in patients, using Prompt-Gamma-Imaging (PGI).

Materials & Methods
A PGI-slit-camera system was modified to enhance its positioning accuracy using a floor-based docking station. Its accuracy and positioning reproducibility were determined with x-ray and PGI measurements. The PGI system was clinically applied to monitor absolute proton ranges for a 1.5Gy field during eight fractions of hypo-fractionated treatment of two prostate-cancer patients using pencil beam scanning (Fig.1). For all monitored fractions, in-room control-CT scans were acquired in treatment position enabling PGI-based spot-by-spot range analysis for the actual patient anatomy. The PG measurements were compared to simulations of the expected PGI signal using either a standard CT-number-to-SPR conversion (HLUT) or a HLUT optimized with patient-specific DECT-derived SPR information (DECT-HLUT), respectively.

The accuracy and precision for global range verification (averaging over multiple spots) was determined to be 0.6mm and 1.3mm (both 2σ-level), respectively. The precision is limited by remaining uncertainties in image registration and positioning reproducibility (1mm,2σ). To verify range prediction in patients, the histogram of range shifts was analyzed concerning its Gaussian mean (Fig. 2) as surrogate for the accuracy of the respective range prediction method, independent from random uncertainty contributions (e.g. positioning, statistical uncertainty in shift determination). The mean deviation for the DECT-HLUT and standard HLUT were -0.6mm and 1.3mm, respectively.

The accuracy of PGI-based range verification was improved to enable the verification of CT-based stopping-power prediction in patients for the first time. First data evaluation suggests a slight superiority of DECT-based range prediction.

  • Lecture (Conference)
    50. Jahrestagung DGMP, 18.-21.09.2019, Stuttgart, Deutschland

Publ.-Id: 29060

Combined measurement of velocity and temperature in liquid metal convection

Zürner, T.; Schindler, F.; Vogt, T.; Eckert, S.; Schumacher, J.

Combined measurements of velocity components and temperature in a turbulent Rayleigh-Benard convection flow at a low Prandtl number and for large Rayleigh numbers are conducted in a series of experiments with durations of more than a thousand free fall time units. Multiple crossing ultrasound beam lines and an array of thermocouples at mid-height allow for a detailed analysis and characterization of the complex three-dimensional dynamics of the single large-scale circulation (LSC) roll in the cylindrical convection cell of unit aspect ratio which is filled with the liquid metal alloy GaInSn. We extract the superposition of short-term oscillations of the LSC with different orientation angles close to the top/bottom plates and the related sloshing motion in the mid-plane with the slow azimuthal drift of the mean roll orientation as a whole that proceeds on a hundred times slower time scale, and measure the internal temporal correlations of this complex large-scale flow. The coherent LSC drives a vigorous turbulence in the whole cell that is quantified by direct Reynolds number measurements at different locations in the cell. The velocity increment statistics in the bulk of the cell displays characteristic properties of intermittent small-scale fluid turbulence. We also show that the impact of the symmetry-breaking large-scale flow persists to small-scale velocity fluctuations thus preventing the establishment of isotropic turbulence in the cell center. Reynolds number amplitudes depend sensitively on beam line position in the cell such that different definitions have to be compared. The global momentum and heat transfer scalings with Rayleigh number are found to agree with those of direct numerical simulations and other laboratory experiments.


Publ.-Id: 29059

Microorganisms present in bentonites from a deep underground experiment

Lopez-Fernandez, M.; Drozdowski, J.; Kluge, S.; Cherkouk, A.

The deep geological repository is one of the internationally accepted options to dispose highly radioactive waste. For this, a multi-barrier system where the radioactive waste will be encapsulated in a technical barrier (metal containers) surrounded by a geotechnical barrier (e.g. compacted bentonite) deep underground in a stable geological formation (host rock) can be used. Bentonites might be used as sealing and backfilling material due to their good properties such as high swelling capacity and low hydraulic conductivity. However, indigenous microorganisms and those introduce during the repository construction and operation can affect these properties.
Bentonite core samples were collected from the Full-scale Engineered Barrier Experiment (FEBEX) in the frame of the FEBEX-Dismantling Project [1] at the Grimsel Test Site (Switzerland) to study their microbial diversity. For that, total DNA was extracted directly from the cores. In addition, sulfate- and iron-reducing microorganisms were enriched from the bentonite samples using specific media. From those enrichments total DNA was extracted and sulfate- and iron-reducing microorganisms were isolated. The microbial communities of the cores, the enrichments, as well as the isolates were analyzed by 16S rRNA gene sequencing. The results showed that the FEBEX bentonite microbial population was directly affected by the continuous high temperature. The dominant phylum in both enrichments was Firmicutes. Desulfosporosinus, Clostridium and Bacillus spp. were identified from the medium for sulfate-reducers, while Desulfitobacterium and Bacillus spp. were detected in the iron-reducing enrichment. Pure cultures were isolated from both enrichments, identifying spore-forming bacteria.
This study revealed that microorganisms were detected on the FEBEX bentonite after almost twenty years of continuous heating. Sulfate- and iron-reducing microbes were enriched by using favorable conditions in specific media. Therefore, it is important to characterize the microbial population of the bentonite used as geotechnical barrier, because microbes might compromise the safety of the deep geological repository of highly radioactive waste.


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

Publ.-Id: 29058

Combined Magnetron Sputtering- and Flash Lamp Annealing- Tool for Thin Film Processing under Vacuum Conditions

Begeza, V.; Rebohle, L.; Neubert, M.; Zhou, S.

Unintentional contaminations during the thin film processing can occur, wich can lead to serious quality and performance degradations. In this work a new tool is presented wich combines DC Magnetron Sputtering and the Flash Lamp Annealing technology. Both processes are performed under vacuum conditions, to keep the Oxygen and Hydrogen contamination of the film low.

Keywords: Flash Lamp Annealing; Magnetron Sputtering; thin film processing; vacuum

  • Lecture (Conference)
    44. Treffen der Nutzergruppe Heißprozesse und RTP, 03.-04.04.2019, Erlangen, Deutschland

Publ.-Id: 29057

Effect of Anions on the Changes in the Structure and Adsorption Mechanism of Zirconium Species at the Muscovite (001) – Water Interface

Yuan, K.; Bracco, J. N.; Schmidt, M.; Soderholm, L.; Fenter, P.; Lee, S. S.

Multivalent cations primarily exist as polynuclear hydroxo and oxyhydroxo clusters and/or nanoparticles (NPs) in aqueous environments, where their interactions with mineral surfaces can be influenced by complexing anions. Here, we investigated the effect of background electrolyte anions (specifically ClO4-, Cl-, SO42-, and HPO42-) on the distribution of tetravalent Zr adsorbed on the negatively charged basal surface of muscovite mica. The experiments were conducted at constant pH (= 3), total Zr(IV) concentration (= 0.1 mM), and ionic strength (= 0.1 M). The Zr coverages measured by X-ray fluorescence (XRF) in ClO4- and Cl- systems were 1.3 and 2.1 Zr/AUC (where AUC = 46.72 Å2 is the area of the unit cell of the mica (001) surface), respectively, and mostly remained unchanged during the reaction time from 6 to 50 h. In these conditions, Zr adsorption occurred both as small NPs (with an average height of ~4 nm observed by ex situ atomic force microscopy, AFM) and in a ~2 nm-thick molecular layer (observed by in situ resonant anomalous X-ray reflectivity, RAXR). In comparison, higher Zr coverages that increased with reaction time (i.e., from ~4 to ~7 Zr/AUC from 6 to 50 h reactions) were observed in the SO42- system. Ex situ AFM revealed that the Zr uptake in this system occurred predominantly as NPs that were ca. 5 to 15 nm tall and 20 to 40 nm wide, but no evidence of the interfacial molecular-layer formation was observed by RAXR. In the HPO42– solution, all measurements unequivocally showed no significant Zr sorption, in stark contrast to the observations in the other solutions. Details of the Zr surface coverage and sorption modes are consistent with the known clustering of tetravalent Zr in solutions in the presence of these anions. These results demonstrate the significant impact of anions on the adsorption affinity and mechanism of Zr on the negatively charged mica surface.

Keywords: CTF/RAXR; Sorption; Zirconium; Nanoparticles; XRF; AFM

Publ.-Id: 29056

Towards the electronic structure of actinide oxides nanoparticles

Kvashnina, K.

Understanding the mechanisms of different chemical reactions with actinides at the atomic level is a key step towards safe disposal of nuclear wastes and towards the identification of physical-chemical processes of radionuclides in the environment. This contribution will provide an overview of the recently performed studies on Uranium, Thorium, Plutonium and Cerium oxide nanoparticles at the Rossendorf Beamline (ROBL)[1] of the European Synchrotron (ESRF) in Grenoble (France). This innovative, recently upgraded, world-wide unique experimental station, funded and operated by HZDR in Dresden (Germany) was used to study actinide systems by several experimental methods, mainely by X-ray absorption spectroscopy in high energy resolution fluorescence detection (HERFD) mode and resonant inelastic X-ray scattering (RIXS) at the An/Ln L3 and An M4,5 edge [2–5]. The experimental results have been analysed using a number of theoretical methods based on density functional theory and atomic multiplet theory. This research has received funding from European Research Council (ERC) under grant agreement 759696

  • Lecture (Conference)
    Goldschmidt2019, 18.-23.08.2019, Barcelona, Spain

Publ.-Id: 29055

Reduction of NpO2+ and TcO4- at the FeII-montmorillonite-water interface

Marques Fernandes, M.; Scheinost, A. C.; Baeyens, B.

The fate of the long-lived, redox-sensitive radionuclides neptunium (237Np) and technetium (99Tc) in deep geological radioactive waste repositories is a major environmental issue. Both elements are highly soluble in their oxidized redox state, and are not (TcO4-) or only weakly sorbed (NpO2+) by negatively charged clay minerals. In the presence of adsorbed and/or structural FeII, however, clay minerals have been shown to reduce (co-)adsorbed contaminants such as U and Se [1, 2], thereby increasing the solid-water distribution coefficient (retention) by several orders of magnitude. In order to investigate if, to which extent, and under which conditions NpV and TcVII are reduced to their tetravalent oxidation states, we conducted Np and Tc batch adsorption experiments with iron-free montmorillonite and with DCB-reduced Wyoming (2.9 wt. % Fe) montmorillonite under different experimental conditions (i.e. anoxic, electrochemical reduction, in the absence and presence of dissolved FeII). The final oxidation state and the type of surface complex formed was elucidated by X-ray absorption spectroscopy at Np-L3, Tc-K and Fe-K edges. We show that both adsorbed and structural FeII are able to reduce NpV and TcVII to NpIV and TcIV, respectively, but the extent strongly depends on the available amount of FeII and on the experimental conditions. The reduced Np strongly complexes towards co-adsorbed Fe and no NpO2 formation is observed. In the case of Tc, mainly TcO2-like nanoparticles form. Surface complexation via Fe is only observed at low Tc surface loadings.

Keywords: Technetium; Neptunium; ROBL; EXAFS; redox; clay; iron

  • Invited lecture (Conferences)
    Goldschmidt Conference, 18.08.2019, Barcelona, Spain

Publ.-Id: 29054

REMOO-2019 Blind Test Calculation Workshop (BTW)

Höhne, T.

A blind test benchmark of transient 2-phase flow simulation codes will be organized.
The purpose is to give participants an opportunity to test their code capability to predict onset of dryout, post-dryout heat transfer phenomena as well as subsequent rewetting in a boiling water rod bundle geometry under realistic operational conditions. Experimental data that will be used in the blind test have been obtained in a 4 by 4 rod bundle and include pressure drops along the bundle divided into six sub-sections, rod clad temperatures at fourteen elevations and coolant temperatures at six elevations.
For analyzed experimental case, steady-state initial and boundary conditions as well as transient forcing functions have been recorded together with above-mentioned parameters.

Keywords: CFD; Subchannel codes; dryout; post dryout; rod bundle

  • Lecture (Conference)
    The 9th International Conference & Workshop REMOO–2019, 16.-18.04.2019, Hong Kong, China

Publ.-Id: 29053

Adsorption of UVI and EuIII on illite: The important role of accessory minerals

Marques Fernandes, M.; Scheinost, A. C.; Huittinen, N.; Baeyens, B.

Adsorption models able to predict the fate of (radio-)contaminants at water-mineral interfaces are important tools to assess the risk related to their migration in natural environments. In general, adsorption in a multimineralic environment is assumed to be governed by the major reactive mineral constituents. A common procedure to predict the adsorption by a soil/rock entity is to combine in an additive way the adsorption models for each single mineral composing the mineral assemblage, i.e. based on the relative reactive amounts of each mineral.
Ideally, robust and reliable adsorption models should be developed for each environmentally relevant mineral based on experimental data obtained under a wide range of conditions to guarantee their predictive capability. For this it is of utmost importance to study the retention of contaminants on well-characterized minerals, under well-defined and controlled conditions.
Diocthahedral alumina-silicates such as illite and montmorillonite are common mineralogical components of soils and sedimentary rocks which control the migration of (radio-)contaminants in natural systems through their exceptional bulk physical and chemical properties.
In the present study we will illustrate how the adsorption properties of a presumably pure clay mineral, illite du Puy (IdP), can be strongly altered by an accessory mineral (< 0.5 wt.%). The adsorption of UVI as well EuIII on purified IdP (<0.5 µm) under certain conditions (i.e., pH, concentration, presence/absence of dissolved carbonate) showed an unexpected enhancement of the retention of UVI and trivalent actinides and lanthanides (Cm/Am/Eu). The application of extended X-ray absorption fine structure spectroscopy and time resolved laser fluorescence spectroscopy on IdP samples loaded with UVI and EuIII, respectively, clearly suggest complexation by phosphate groups not expected in IdP. For U, the formed surface complex could be identified as an autunite-like phase. In the case of Eu, the formation of a ternary apatite-like Eu-Ca-PO4 solid phase was observed. Furthermore, leached phosphate from the clay mineral resulted in the precipitation of non-sorbed EuIII as rhabdophane (EuPO4×nH2O). The accessory mineral phase itself responsible for this anomalous behaviour is difficult to identify with common analytical methods such as TEM or XRD due to e.g. the low concentration and/or amorphous nature of the accessory phase or the low electron density of its constituent elements. Repeated acid-pre-treatment of IdP released P and Ca, pointing towards an apatite-like accessory phase as source of phosphate for the formation of the UVI and EuIII solid phases. In the pre-treated solid phosphate complexation was greatly reduced. In the case of UVI, an inner-sphere surface complex on IdP edge sites could be identified in the XAFS investigations. Our results demonstrate that adsorption models calibrated over a wide range of experimental conditions, complemented by a molecular-level control and a true mechanistic understanding, is of paramount importance for reliable modelling of adsorption processes at the solid-liquid interface.

Keywords: uranium; autunite; apatite; XAFS; illite; sorption

  • Invited lecture (Conferences)
    Migration 2019, 15.-20.09.2019, Kyoto, Japan

Publ.-Id: 29052

A 224Ra-labeled polyoxopalladate as putative radiopharmaceutical

Gott, M.; Yang, P.; Kortz, U.; Stephan, H.; Pietzsch, H.-J.; Mamat, C.

Despite its attractive properties, internal targeted alpha therapies using 223/224Ra are limited to bone-seeking applications. As there is no suitable chelator available, the search for new carriers to stably bind Ra2+ and to connect it to biological target molecules is necessary. Polyoxopalladates represent a class of compounds where Ra2+ can be easily introduced into the Pd-POM core during a facile one-pot preparation. Due to the formation of a protein corona the connection to other targeting (bio)macromolecules is possible.

Keywords: Radium; Barium; POM; alpha-therapy


Publ.-Id: 29051

A Monte Carlo based radiation response model to assess variability of clinical RBE in proton therapy

Eulitz, J.; Lutz, B.; Wohlfahrt, P.; Dutz, A.; Enghardt, W.; Karpowitz, C.; Krause, M.; Troost, E. G. C.; Lühr, A.

The clinical implementation of a variable relative biological effectiveness (RBE) in proton therapy is currently controversially discussed. First clinical evidence indicates a variable proton RBE, which needs to be verified. In this study, a radiation response model for assessing clinical RBE variability is established. The model was applied to four selected glioma patients (grade III) treated with adjuvant radio(chemo)therapy and who developed late morphological image changes on T1-weighted contrast-enhanced (T1w-CE) magnetic resonance (MR) images within approximately two years of recurrence-free follow-up. The image changes were correlated voxelwise with dose and linear energy transfer (LET) values using univariable and multivariable logit functions. The model performance was assessed by the area-under-the-curve (AUC) performing a leave-one-out cross validation. The tolerance dose TD50 at which 50% of patient voxel experienced toxicity was interpolated from the model. A Monte Carlo (MC) framework was developed to simulate dose and LET distributions, which includes variance reduction (VR) techniques to decrease computation time. Its reliability and accuracy was evaluated based on dose calculations of the clinical treatment planning system (TPS) as well as absolute dose measurements performed in the patient specific quality assurance.
Morphological image changes were related to a combination of dose and LET. The multivariable model revealed a cross-validated AUC of 0.88 (95% confidence interval 0.80 – 0.95). The TD50 decreased linearly with increasing LET indicating an increase in biological effectiveness. The MC framework reliably predicted average TPS dose within the clinical target volume as well as absolute water phantom dose measurements within 2% accuracy using dedicated VR settings.
The observed correlation of dose and LET with late brain tissue damage suggests considering RBE variability for predicting chronic radiation-induced brain toxicities. The MC framework simulates precisely and time-efficiently radiation fields in patients. Hence, this study encourages and enables in-depth patient evaluation to assess the variability of clinical proton RBE.

Keywords: Proton Therapy; Clinical RBE; Monte Carlo; Passive Scattering

Publ.-Id: 29049

Improved electrode design for interdigitated large-area photoconductive terahertz emitters

Singh, A.; Welsch, M.; Winnerl, S.; Helm, M.; Schneider, H.

We study here the effect of the electrode parameters on the terahertz emission efficiency of large-area emitters based on interdigitated electrodes. Electrode parameters are optimized to get maximum terahertz emission by optimizing the balance condition among the emission efficiency of individual electrode pairs, number of emitters per unit area, and fraction of semiconductor exposed for optical pumping. A maximum enhancement by about 50 % in the peak to peak electric field is observed as compared to the previous state of the art design.

Keywords: Terahertz emitters; photoconductive switch; interdigitated electrode

Publ.-Id: 29048

Implementation of HZDR baseline model for poly-dispersed bubbly flow in OpenFOAM

Liao, Y.

The predictability of TFM-CFD is largely restricted by the reliability of closures that should reconstruct the information about the phenomena and processes occuring at the interface. The development of physically based models is severely obstructed by insufficient knowledge on the physics and numerous misleading work based on case-by-case tuning. A strategy towards general closures is necessary. A few years ago HZDR proposed a baseline model for TFM-CFD simulation of poly-dispersed bubbly flow with a fixed set of closures. It aims to identify the missing physics in the existing models and improve them step by step. In this work the baseline model is implemented and tested in the open source CFD code OpenFOAM for a large number of bubbly flow cases including vertical pipe flow and bubble column.

  • Lecture (Conference)
    CFD-Verbund, 11.-12.03.2019, Garching bei München, Deutschland

Publ.-Id: 29047

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