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33520 Publications

Rapid synthesis of sub-10 nm hexagonal NaYF4-based upconverting nanoparticles using Therminol 66

Hesse, J.; Klier, D. T.; Sgarzi, M.; Nsubuga, A.; Bauer, C.; Grenzer, J.; Hübner, R.; Wislicenus, M.; Joshi, T.; Kumke, M. U.; Stephan, H.ORC
We report a simple one-pot method for rapid preparation of sub-10 nm pure hexagonal (β-phase) NaYF4 based upconverting nanoparticles (UCNPs). Such nanocrystals are well-known for their high efficiency of energy upconversion. Using Therminol 66 as co-solvent, monodisperse UCNPs could be obtained in unusually short reaction time. By varying reaction time, reaction temperature, and the concentration of the dopants (Nd3+, Yb3+ sensitizer ions and Er3+ activator ions), it was possible to precisely control the particle size, crystalline phase, as well as the upconversion (UC) luminescence properties. The size and phase-purity of as-synthesized core and core-shell nanocrystals was assessed using complementary transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) studies. In-depth photophysical evaluation of the UCNPs was pursued using steady-state as well as time-resolved luminescence spectroscopy. An enhancement in UC intensity was observed when nanocrystals, doped with optimized concentration of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This is attributed to the suppression of surface-related luminescence quenching effects.
Keywords: core-shell; lanthanides; nanocrystal synthesis; photoluminescence; upconversion

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Permalink: https://www.hzdr.de/publications/Publ-26395
Publ.-Id: 26395


Performing clinical 18FDG-PET/MR imaging of the mediastinum using a dedicated, patient-friendly protocol

Peerlings, J.; Paulis, L.; Mitea, C.; Bakers, F.; Berbée, M.; Wierts, R.; Vöö, S.; Backes, W.; Wildberger, J.; Hoffmann, A.
Purpose:
To apply clinical 18FDG-PET/MRI, a trade-off between image quality (IQ), diagnostic accuracy, and patient compliance is required. This study aimed to develop a mediastinal-specific 18FDG-PET/MR protocol containing dedicated MRI-sequences able to produce robust, high-quality images with great patient compliance and diagnostic performance comparable to 18FDG-PET/CT.

Methods:
In this study, 15 healthy subjects and 10 patients with mediastinal malignancies (i.e., 8 non-small cell lung cancer, 2 oesophageal cancer) received 18FDG-PET/MR imaging immediately after 18FDG-PET/CT. PET/MR-sequences (T1-VIBE, T2-HASTE) on a Siemens Biograph mMR scanner were optimized by varying the following parameters: breath-hold (BH, in end-expiration), fat saturation (SPAIR), and electrocardiogram-triggering (ECG, in end-diastole). IQ of each sequence-variation was qualitatively scored on a 5-point scale by medical experts and quantitatively assessed by calculating signal-to-noise ratios (SNR), contrast relative to muscle-tissue (CR), standardized-uptake-values (SUVs), and tumour-to-blood ratios (TBRs). Differences in CR determined contrast between adjacent tissues and tumour visibility. Diagnostic accuracy of 18FDG-PET/MRI was compared to 18FDG-PET/CT, in reference to clinical reports and histo-/cytopathological analyses.

Results:
Quantitative analysis showed that T1-VIBE images acquired with ECG-triggering presented highest SNR for soft-tissues in the mediastinum (P<0.01) with high contrast between tumours and adjacent tissue, regardless of breath-hold or free-breathing acquisition. In qualitative analyses, IQ of T1-VIBE scans using BH and ECG triggering were scored highest with good reader-agreement (κ=0.62). Quantitative and qualitative IQ of T2-HASTE was not significantly affected by BH-acquisition (P>0.9). However, qualitative IQ of both T1-VIBE and T2-HASTE deteriorated with the addition of SPAIR. Diagnostic performance of 18FDG-PET/MR was not significantly different from 18FDG-PET/CT with similar staging, SUVs, and TBRs. However, T-status was more often over-staged on 18FDG-PET/CT, while N-status was more frequently under-staged on 18FDG-PET/MR.

Conclusion:
ECG-triggered T1-VIBE sequences acquired during short, multiple breath-holds are recommended for mediastinal imaging using 18FDG-PET/MR protocols. With dedicated protocols, 18FDG-PET/MR imaging could be implemented in thoracic oncology and aid in diagnostic evaluation, tailored treatment decision-making, and personalized patient care.
Keywords: 18F-FDG PET/MR PET/CT Mediastinum Esophageal carcinoma Non-small cell lung cancer

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Permalink: https://www.hzdr.de/publications/Publ-26394
Publ.-Id: 26394


Outlook on a new combined MRI/TI experiment

Seilmayer, M.; Stefani, F.; Gundrum, G.; Köppen, S.
In the project framework of DRESDYN a sodium based experiment investigating magneto rotational instability (MRI) an Tayler instability (TI) is going to be built. Since both instabilities are based on hydrodynamically stable but magnetized Taylor Couette flow, the magnetic field configuration distinguishes the different types of instabilities. The past experimental research successfully worked out helical MRI with a combination of axial and azimuthal magnetic field and azimuthal MRI with only a pure azimuthal field. In both cases the relevant field B[phi] ~ 1/r is
generated by a rather large insulated current running on the symmetry axis of the experiment. The most challenging type of instability still remains standard MRI (SMRI) which relays on pure axial magnetic field B[z]. Here the necessary high rotation rates and large dimensions do limit the experimental feasibility to trigger SMRI until now. Besides that, even a non-rotating fluid with zero velocity can be destabilized by Tayler instability. Here the current is driven through the liquid which gives a B[phi] ~ r dependence. Concluding, the aim of new experimental is to investigate the whole parameter space for the mentioned instabilities and corresponding transitions.

We like to present the latest stage of construction of a large scale liquid sodium Taylor-Couette experiment with a height of 2m and diameter of 0.8 m. In a rough approximation, the achievable boundary conditions will be up to 20 Hz rotation rate and up to 50kA of electrical current. In a more detail, there are some specific topics we like to discus.

First, there is the quasi coaxial system consisting of a central current carrying copper rod and five symmetric return paths which provides homogeneous magnetic field to the Taylor-Couette flow.
One challenging part is the design of the current distributor, which is supposed to divide the current into several equally weighted lines. Because of the individual characteristic resistance of all involved conductors an initial imbalance in the current distribution affecting the symmetry of the magnetic field is the result. So the adjustment of current distribution becomes mandatory to ensure maximum field homogeneity. An indirect access to set the current in all five return paths is to control the outflow temperature of the required water cooling. This is done by thermostatically operated valves in conjunction with the temperature dependent branch resistance. Finally, the calibrated system achieves less than 1% field in-homogeneity and works in a wide range of currents. Additional benefits of the presented approach will be the minimal stray field of the installation and cheap components.

Second, we designed a stacked magnetic field system to generate the axial component. Here 27 individual coils provide an almost homogeneous field with B[z] < 150 mT in the relevant volume. The most challenging aspect is the huge amount of electrical power (approximately 120 kW) which have to be cooled. The main advantage of the present geometry is the guaranteed access to all the sensors mounted on the outer cylinder surface. This is achieved by a special geometry to partially levitate the coil system.

[1]F. Stefani et al., PRE, 80(6), 2009.
[1]M. Seilmayer et al., PRL, 108(24), 244501, 2012.
[1]M. Seilmayer et al., IEEE Sensors Journal, DOI 10.1109/JSEN.2017.2765671, 2017.
Keywords: Experiment, Sodium, DRESDYN, Taylor-Couette
  • Poster
    GDRI DYNAMO MEETING, 26.-29.11.2017, Paris, Frankreich

Permalink: https://www.hzdr.de/publications/Publ-26393
Publ.-Id: 26393


Synthesis of High-Crystallinity DPP Polymers with Balanced Electron and Hole Mobility

Di Pietro, R.; Erdmann, T.; Carpenter, J. H.; Wang, N.; Shivhare, R. R.; Formanek, P.; Heintze, C.; Voit, B.; Neher, D.; Ade, H.; Kiriy, A.
We review the Stille coupling synthesis of P-(DPP2OD-T) (Poly[[2,5-di(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-3,6-diyl]-alt-[2,2′:5′,2″-terthiophene-5,5″-diyl]]) and show that high-quality, high molecular weight polymer chains are already obtained after as little as 15 min of reaction time. The results of UV−vis spectroscopy, grazing incidence wide-angle X-ray scattering (GIWAXS), and atomic force microscopy show that longer reaction times are unnecessary and do not produce any improvement in film quality. We achieve the best charge transport properties with polymer batches obtained from short reaction times and demonstrate that the catalyst washing step is responsible for the introduction of charge-trapping sites for both holes and electrons. These trap sites decrease the charge injection efficiency, strongly reducing the measured currents. The careful tuning of the synthesis allows us to reduce the reaction time by more than 100 times, achieving a more environmentally friendly, less costly process that leads to high and balanced hole and electron transport, the latter being the best reported for an isotropic, spin-coated DPP polymer.

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Permalink: https://www.hzdr.de/publications/Publ-26392
Publ.-Id: 26392


ns-laser driven magnetic phase transition in FeAl

Liedke, M. O.; Bali, R.; Gradauskaite, E.; Ehrler, J.; Wang, M.; Potzger, K.; Zhou, S.; Wagner, A.
FeAl alloys show temperature dependent magnetic phase transition (MPT) from a ferromagnetic disordered A2-phase to a paramagnetic ordered B2-phase. The B2-phase can be reversed back to the A2-phase, e.g, by ion irradiation. The most plausible explanation of MPT points in direction of the anti-site disorder (ASD), i.e., more Fe-Fe nearest neighbors due to disordering. However, variations of the lattice parameter, defects concentration, and secondary phases may play an important role, too. Here, we employ an excimer UV ns-laser to examine the role of ASD and defects onto magnetic properties. Three sample series with different initial order conditions were irradiated by several laser fluences: (i) as-grown semi-, (ii) Ne irradiated fully-disordered, and (iii) vacuum annealed ordered alloys. Two magnetic regimes were found depending on laser fluence: (i) in the low fluence range magnetization initially decreases, followed by (ii) subsequent monotonic increase for larger fluences. The positron annihilation spectroscopy measurements reveal changes of defects surrounding from Al- to Fe dominant, respectively, as well as of defects concentration. The results obtained by MOKE, VSM, AFM, and TEM will be discussed in detail.
Keywords: FeAl alloys, PAS, magnetic phase transition, ns-laser, anti-site disorder, positron annihilation spectroscopy
  • Lecture (Conference)
    DPG Spring Meeting 2017, 19.-24.03.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26391
Publ.-Id: 26391


Fe2+ ion irradiated JRQ steel investigated by nanoindentation and slow-positron Doppler broadening spectroscopy

Pecko, S.; Heintze, C.; Bergner, F.; Anwand, W.; Slugen, V.
A model reactor pressure vessel (RPV) steel, known as JRQ, was manufactured in Japan for IAEA neutron embrittlement research studies in late 80 s. This model alloy belongs to the commercially used steel of A533B-1 type and shows relatively large changes in mechanical properties after a neutron irradiation due to considerable copper content (0.15 wt%). In order to simulate neutron irradiation and investigate the hardening effect, studied specimens of JRQ steel were exposed to Fe2+ ion irradiation in five different exposures calculated using the SRIM code. The ion energy of 5 MeV, temperature at 300 °C and the flux of 1.0×1011 cm−2 s−1 were the same during the irradiations. The hardening was investigated and observed by means of nanoindentation technique and a defect profile of irradiated steels was measured by Slow-positron Doppler broadening spectroscopy (DBS). The observed increasing trend of nanohardness as a function of fluence is in good agreement with the trend observed on the basis of Vickers hardness measured for neutron-irradiated JRQ. This confirms that Cu precipitation is most likely responsible for the observed irradiation hardening and that neutron-irradiation-induced damage can be simulated using ion irradiation in the present case. We have also excluded open volume (vacancy type) defects in the crystal lattice of JRQ steel from a responsibility for the damage arising by the Fe2+ ion irradiation.
Keywords: Positron annihilation spectroscopy, Reactor pressure vessel steels, Nanoindentation, Iron irradiation

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Publ.-Id: 26390


Positronium formation in nanostructured metals

Čížek, J.; Melikhova, O.; Hruška, P.; Vlček, M.; Anwand, W.; Liedke, M. O.; Novotný, M.; Bulíř, J.
Positronium formation in Au films was studied using a magnetically guided continuous slow positron beam with variable energy. Black Au film with porous morphology was compared with conventional smooth Au film. In the smooth Au film positronium is formed on the film surface only. The black Au film exhibits porous sub-surface region containing micro-cavities interconnected with surface. Positronium is formed on inner surfaces of micro-cavities in the sub-surface region and travels through interconnected cavities towards the surface. 3-gamma annihilation of ortho-positronium leaves a clear signature in two-dimensional coincidence Doppler broadening spectra. Measurements of 3-gamma annihilation contribution calculated from single gamma-ray and coincidence Doppler broadening spectra were calculated and compared.
Keywords: Positronium, slow positron beam, porous metals, Au, coincidence Doppler broadening spectroscopy, positron annihilation spectroscopy

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Permalink: https://www.hzdr.de/publications/Publ-26389
Publ.-Id: 26389


Photon vs. proton radiochemotherapy: effects on brain tissue volume and perfusion

Petr, J.; Platzek, I.; Hofheinz, F.; Mutsaerts, H.; Asllani, I.; van Osch, M.; Seidlitz, A.; Krukowski, P.; Gommlich, A.; Beuthien-Baumann, B.; Jentsch, C.; Maus, J.; Troost, E.; Baumann, M.; Krause, M.; van den Hoff, J.
Background and Purpose: To compare the structural and hemodynamic changes of healthy brain tissue in the cerebral hemisphere contralateral to the tumor following photon and proton radiochemotherapy.

Materials and Methods: Sixty-seven patients (54.9±14.0 years) diagnosed with glioblastoma multiforme undergoing adjuvant photon (n=47) or proton (n=19) radiochemotherapy with temozolomide after tumor resection underwent T1-weighted and arterial spin labeling MRI. Changes in volume and perfusion before and 3 to 6 months after were compared between therapies.

Results: A decrease in gray matter (GM) (-2.2%, P<0.001) and white matter (WM) (-1.2%, P<0.001) volume was observed in photon-therapy patients compared to the pre-radiotherapy baseline. In contrast, for the protontherapy group, no significant differences in GM (0.3%, P=0.64) or WM (-0.4%, P=0.58) volume were observed. GM volume decreased with 0.9% per 10 Gy dose increase (P<0.001) and differed between the radiation modalities (P<0.001). Perfusion decreased in photon-therapy patients (-10.1%,
P=0.002), whereas the decrease in proton-therapy patients, while comparable in magnitude, did not reach statistical significance (-9.1%, P=0.12). There was no correlation between perfusion decrease and either dose (P=0.64) or radiation modality (P=0.94).

Conclusion: Our results show that the tissue volume decrease depends on radiation dose delivered to the healthy hemisphere and differs between treatment modalities. In contrast, the decrease in perfusion was comparable for both irradiation modalities. We conclude that proton therapy may reduce brain-volume loss when compared to photon therapy.

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Permalink: https://www.hzdr.de/publications/Publ-26388
Publ.-Id: 26388


Positronium probing of pores in zirconia nanopowders

Prochazka, I.; Cizek, J.; Lukac, F.; Melikhova, O.; Hruska, P.; Anwand, W.; Liedke, M. O.; Konstantinova, T. E.; Danilenko, I. A.
In the present paper, conventional positron lifetime measurements on selected zirconia-based nanopowders are reported. The nanopowders were doped with various metal cations (Y3+, Eu3+, Gd3+, Lu3+ and Mg2+). Lifetime experiments were conducted in air and supplemented with mass density measurements. In a range of lifetimes, from a few ns to ≈ 70 ns, up to two individual lifetime components could be identified. Such observations confirmed positronium (Ps) formation with subsequent ortho-Ps pick-off annihilation as well as the occurrence of pores of different size. Pore sizes were estimated using a shape-free model of the correlation between pore size and ortho-Ps lifetime. The origins of pores are discussed on the basis of the ortho-Ps data in combination with the results mass density measurements.
Keywords: positron lifetime, Positronium, zirconia nanopowders, mass density measurements, defects

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Permalink: https://www.hzdr.de/publications/Publ-26387
Publ.-Id: 26387


Microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb treated by plasma immersion Ti ion implantation and deposition

Kashkarov, E.; Nikitenkov, N.; Sutygina, A.; Laptev, R.; Bordulev, Y.; Obrosov, A.; Liedke, M. O.; Wagner, A.; Zak, A.; Weiß, S.
The effect of low energy plasma immersion ion implantation and deposition of titanium on microstructure, defect structure and hydrogen trapping in zirconium alloy Zr-1Nb was studied. Defect structure and distribution were analyzed by Doppler broadening using slow positron beam. The surface microstructure after modification is represented by nanostructured Ti grains with random orientation. The gradient distribution of titanium as well as vacancy type defects were analyzed. The concentration of vacancy type defects is rising with increasing bias voltage. Gas-phase hydrogenation of the Ti-modified Zr-1Nb alloy was performed at 400 °C for 60 min. The strong interaction of hydrogen with vacancy type defects was demonstrated. Two different changes in the defect structure after hydrogenation were observed: when a titanium film is formed on the surface (after deposition at 500 V) hydrogen trapping occurs with the formation of titanium hydride phases, while in the implanted layer (deposition at 1000 and 1500 V) hydrogen is trapped due to interaction with vacancy type defects. The physical basis of Ti diffusion and its influence on the evolution of defect structure after surface modification and hydrogenation were discussed.
Keywords: Zirconium, Ion implantation, Titanium, Diffusion, Surface modification, Hydrogen trapping, Microstructure, Slow positrons, Doppler broadening, Defects

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Permalink: https://www.hzdr.de/publications/Publ-26386
Publ.-Id: 26386


Polymer nanocomposites with silver nanoparticles formed by low-energy ion implantation: slow positron beam spectroscopy studies

Kavetskyy, T. S.; Liedke, M. O.; Srinivasan, N.; Wagner, A.; Krause-Rehberg, R.; Šauša, O.; Petkova, T.; Boev, V.; Stepanov, A. L.
Polymer nanocomposites formed by low-energy ion implantation were studied by means of positron annihilation spectroscopy with a variable-energy positron beam or slow positron beam spectroscopy. Silver ion implantation into polymethylmethacrylate (Ag:PMMA) and hybrid organic-inorganic ureasil (Ag:ureasil) was performed at different ion fluences with a constant energy of 30 keV and a current density of 1 µA/cm^2 in order to prepare Ag nanoparticles in the near-surface region of polymer matrix. Contribution of Doppler broadening slow positron beam spectroscopy technique for understanding Ag nanoparticles formation in Ag:PMMA and Ag:ureasil nanocomposite films is demonstrated.
Keywords: polymers, nanocomposites, PMMA, ureasil, ion implantation, silver nanoparticles, positron annihilation, slow positrons
  • Book chapter
    Janez Bonca and Sergei Kruchinin: NATO Science for Peace and Security Series A: Chemistry and Biology, P.O.Box 17, 3300 AA Dordrecht, The Netherlands: AK/Nato Publishing Unit, Springer, 2018, 293-300
    DOI: 10.1007/978-94-024-1304-5_21

Permalink: https://www.hzdr.de/publications/Publ-26385
Publ.-Id: 26385


Kinetic modeling of the new σ1 receptor ligand (-)-[18F]Fluspidine in the human brain.

Becker, G. A.; Meyer, P. M.; Patt, M.; Hesse, S.; Luthardt, J.; Patt, J.; Rullmann, M.; Fischer, S.; Kluge, A.; Steinbach, J.; Wünsch, B.; Brust, P.; Sabri, O.
Der Abstract wird nachgereicht.
  • Abstract in refereed journal
    Nuklearmedizin 57(2018)-V9

Permalink: https://www.hzdr.de/publications/Publ-26384
Publ.-Id: 26384


EPR studies of the triangular-lattice antiferromagnet Cs2CuBr4

Schulze, E.; Ponomaryov, A. N.; Wosnitza, J.; Tanaka, H.; Zvyagin, S. A.
The spin dynamics of the spin-1/2 triangular-lattice antiferromagnet Cs2CuBr4 is probed by means of high-frequency electron paramagnetic resonance (EPR) spectroscopy. Temperature dependences of EPR parameters are studied in a broad temperature range between 1.4 and 200 K for different orientations of the applied magnetic field. In the high-temperature regime (T >> J/kB), an unusually broad and anisotropic resonance line is detected, suggesting a sizeable Dzyaloshinskii–Moriya interaction. Employing the theory of exchange narrowing, the ratio of the Dzyaloshinskii–Moriya vector components, Dc/Da ≈ 0.3, is estimated.
  • Open Access Logo Low Temperature Physics 43(2017), 1642-1646
  • Poster
    DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM) gemeinsam mit der European Physical Society (CMD), 11.-16.03.2018, Berlin, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-26383
Publ.-Id: 26383


Entwicklung von F-18-markierten Radioliganden zur molekularen Bildgebung des A2A Adenosinrezeptors

Lai, T. H.; Moldovan, R.-P.; Schröder, S.; Dukic-Stefanovic, S.; Ludwig, F.-A.; Fischer, S.; Deuther-Conrad, W.; Steinbach, J.; Brust, P.
Ziel: Adenosinrezeptoren wurden jüngst als potentielle neue Targets bei der Immuntherapie von Hirntumoren identifiziert. [1] Die Autoren haben sich das Ziel gesetzt, hochaffine und selektive Radioliganden für den A2A-Rezeptor-Subtyp zu entwickeln, mit deren Hilfe Hirntumoren bildgebend molekular charakterisiert und entsprechende adjuvante Therapien verbessert werden können.

Methodik: Basierend auf einer Pyrazolo[2,3-d]pyrimidin Leitverbindung [2] wurden 21 fluorierte Derivate synthetisiert. Die Bindungsaffinitäten zum A2A- und zum A1-Rezeptor wurden mittels CHO-Zellen bestimmt, welche die relevanten humanen Rezeptoren hoch exprimieren. Zwei Derivate mit hoher Affinität und Selektivität wurden ausgewählt, um entsprechende Präkursoren zu synthetisieren, welche für die Radiofluorierung durch aromatische nukleophile Substitution eingesetzt werden.

Ergebnisse: Strukturelle Modifikationen der Leitverbindung führten zu neuen Derivaten mit Affinitäten zwischen 0,93 nM und 369 nM (A2A) bzw. zwischen 31,3 nM und 2298 nM (A1). Das 4 Fluorbenzylderivat 1 (Ki(A2A) = 5,3 nM; Ki(A1) = 220 nM) und das 1-Brom-3-fluorbenzylderivat 2 (Ki(A2A) = 2,4 nM; Ki(A1) = 162 nM) wurden für die Radiofluorierung ausgewählt. Die Herstellung von [18F]1 erfolgte in ersten Experimenten über ein zweistufiges Verfahren ausgehend von 4 [18F]Fluorbenzaldehyd durch reduktive Aminierung mit dem Pyrazolo[2,3-d]pyrimidin-Baustein. Die Radiofluorierung von 2 wird unter Verwendung des entsprechenden Nitro-Präkursors realisiert.

Schlussfolgerung: Es wurden zwei fluorierte Pyrazolo[2,3-d]pyrimidin-Derivate mit hoher Affinität und Selektivität zum A2A-Rezeptor synthetisiert, welche die weitere Entwicklung für effiziente F-18-Markierungsverfahren und erste präklinische Untersuchungen rechtfertigen.

Literatur:
[1] Allard et al., Immunol Cell Biol. 2017, 95(4), 333-339.
[2] Gillespie et al., Bioorg. Med. Chem. Lett. 2008, 18, 2924–2929.
  • Lecture (Conference)
    Nuklearmedizin 2018 - 56. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 18.-21.04.2018, Bremen, Deutschland
  • Lecture (Conference)
    Nuklearmedizin 2018, 18.-21.04.2018, Bremen, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-26382
Publ.-Id: 26382


Nonlinear THz spectroscopy of low-dimensional materials

Helm, M.; König-Otto, J.; Schmidt, J.; Dimakis, E.; Winnerl, S.; Schneider, H.
Thanks to the development of powerful THz sources, both table-top and accelerator-based, highly nonlinear THz investigations of materials are possible today. Here we will present two recent examples of nonlinear spectroscopy on low-dimensional materials: resonant four-wave mixing in graphene under a magnetic field, and nonlinear THz spectroscopy of intersubband transitions in a semiconductor quantum well.
Graphene is predicted to be a highly nonlinear material due to its linear dispersion. Clear experimental observations are relatively scarce, however. In a magnetic field, the band structure splits up into non-equidistant Landau levels, giving rise to resonant behavior of the optical properties. We demonstrate resonantly enhanced four-wave-mixing (FWM) at a photon energy of 78 meV, resonant at a magnetic field of B = 4.5 T. The chi(3) character is clearly demonstrated by the power dependence of the four-wave-mixing signal and the narrower line shape as compared to the linear absorption. The FWM signal, proportional to the induced microscopic polarization, decays faster than the also measured pump-probe signal, beyond the time resolution of the experiment (4 ps).
Intersubband transitions in quantum wells, due to their similarities to atomic transitions, have been a playground for many fundamental optical and quantum mechanical effects as well as for novel devices for three decades. Nonlinear or quantum optical effects such as dressed states or electromagnetically induced transparency (EIT) were demonstrated, however, only in the mid-infrared range or probed in the near infrared. Here we employ our THz free-electron laser (FEL) in combination with THz time-domain spectroscopy to realize a true narrow-band pump – broad-band probe experiment: While pumping the 2-3 intersubband transition in a single GaAs/AlGaAs quantum well (at 3.5 THz = 15 meV), we probe the entire THz absorption up to 4 THz (including 1-2 and 2-3 transitions). The experiment allows one to extract the transmission change vs pump-probe time delay as well as the complete spectral shape of the transmission change at a specific time delay. We will discuss the observed spectra, including indications for the Autler-Townes splitting on the 1-2 transition.
Keywords: four-wave mixing, graphene., free-electron laser, pump-prbe, GaAs, quantum well, intersubband transition, Autler-Townes
  • Invited lecture (Conferences)
    MTSA 2017 & TeraNano-8, 19.-23.11.2017, Okayama, Japan

Permalink: https://www.hzdr.de/publications/Publ-26381
Publ.-Id: 26381


[18F]DBT10 als alpha7-Nikotinrezeptor-PET-Tracer von Schlaganfall assoziierter Neuroinflammation

Barthel, H.; Deuther-Conrad, W.; Patt, M.; Nitzsche, B.; Teodoro, R.; Härtig, W.; Luthardt, J.; Grunwald, T.; Brust, P.; Sabri, O.
Ziel
Nach ischämischem Schlaganfall treten neuroinflammatorische Prozesse auf, die therapeutische Targets darstellen, jedoch bisher nicht adäquat in vivo darstellbar sind. Während dieser Prozesse werden unter anderem alpha7-Nikotinrezeptoren (nAChRs) verstärkt exprimiert. [18F]DBT10 ist ein neuer alpha7-nAChR-Tracer, welcher in der vorliegenden Studie erstmals diesbezüglich untersucht werden sollte.

Methodik
Bei zehn erwachsenen Merino-Schafen wurde die linke A. cerebri media permanent okkludiert (pMCAO; Tag 1). Vor dem Eingriff sowie 4h, 7 und 14 Tage nach pMCAO wurden [18F]DBT10-Hirn-PET/MRT-Messungen (Siemens mMR, ca. 300MBq, 2h dynamisch, arterielle Blutproben, Blut-Metaboliten-HPLC) durchgeführt. Anhand direkt vorhergehender [15O]H2O-PET und simultaner Schlaganfall-MRT wurden die Schlaganfall-Kompartimente segmentiert. Direkt nach der PET/MRT am Tag 14 erfolgte ex vivo eine autoradiographische (AR) und histopathologische Hirnaufarbeitung. Zusätzlich zu den pMCAO-Schafen wurden Kontrollschafe (nicht-operiert, Schein-OP) untersucht.

Ergebnisse
[18F]DBT10 im Blut wurde mit einer HWZ von 18min metabolisiert, schnell aus dem Zerebellum ausgewaschen und erreichte in kortikalen Hirn-VOIs bei 60min p.i. ein Plateau. Die Kontrollschafe in die vor dem Eingriff zeigten keine [18F]DBT10-Auffälligkeiten. In den pMCAO-Schafen fanden sich Infarkt-bezogene [18F]DBT10-PETSpeicherdefizite nach 4h und am Tag 7 (SUVRs110-120min p.i. = 0,94±0,04 und 0,90±0,17), am Tag 14 jedoch eine intensive Mehranreicherung im Randbereich des Infarktes (SUVR110-120min p.i. =1,82±0,72; p<0,01). Diese ließ sich in der AR reproduzieren und korrelierte histopathologisch mit Mikroglia-Aktivierung und Makrophagen-Infiltration.

Schlussfolgerungen
Aus diesen Ergebnissen wird geschlussfolgert, dass [18F]DBT10 ein vielversprechender PET-Tracer zur Erfassung von alpha7-nAChR-assoziierter Neuroinflammation nach ischämischem Hirninfarkt ist. Weitere Untersuchungen sollen unter anderem der kinetischen Modellierung des Tracer-Verhaltens dienen.
  • Lecture (Conference)
    56. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 18. – 21.04.2018, 18.-21.04.2018, Bremen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26380
Publ.-Id: 26380


Monte-Carlo-Simulation und Berechnung der spezifischen absorbierten Strahlenenergiefraktionen (SAF) für ein VOXEL Phantom eines Ferkels für die Inkorporationsdosimetrie

Sattler, B.; Kranz, M.; Desbrée, A.; Rullmann, M.; Patt, M.; Deuther-Conrad, W.; Steinbach, J.; Sabri, O.; Brust, P.
Ziel: Vor erstmaliger Anwendung neuartiger Radiopharmaka im Menschen muss präklinisch eine Abschätzung der inneren Strahlenexposition des Menschen am Tiermodell erfolgen. Hierfür stehen computergenerierte VOXEL Phantome (VP) unterschiedlicher Tiermodelle zur Verfügung. Die Verschiedenen, teils regulatorisch für die klinische Anwendung zugelassenen Softwaretools für die Inkorporationsdosimetrie nutzen Implementationen dieser VP für die präklinische und klinische Dosimetrie. Basierend auf den anatomischen und geometrischen Verhältnissen enthalten die VP die in Zielorganen und Organsystemen absorbierte spezifische Fraktion der von Quellorganen ausgehenden/emittierten Strahlenenergie (specific absorbed fraction, SAF). Diese sind grundlegend für die in Organen und Organsystemen absorbierten Dosis (OD) nach dem MIRD Schema und werden durch Monte-Carlo-Simulation (MC) berechnet. Eigene Arbeiten haben gezeigt, dass im Vergleich zur Verwendung von Kleintieren mit Ferkeln eine den Verhältnissen am Menschen vergleichbarere Abschätzung der Strahlenexposition möglich ist. Daher wurde ein VP für Ferkel erstellt und dessen SAFs durch MC berechnet.
Methodik: Ein 12 kg Ferkel (8 Wochen) wurde nach i.v. Injektion von [18F]Flubatine (185.4 MBq) bis zu 4,5 h p.i. in einem PET/CT (SIEMENS Biograph 16) gemessen und die List-Mode Daten nach Standardkorrekturen rekonstruiert. Unter Nutzung der PET bzw. CT Daten und der Software ROVER (ABX, Radeberg) wurden 18 Organe vorwiegend manuell segmentiert und als DICOM Structure Set exportiert. Mit der Software OEDIPE [1] erfolgte die Zuordnung der Gewebeeigenschaften der segmentierten Organe nach ICRU [2]. Anschließend erfolgt die Simulation in MCNPX (v.2.6.0) mit 20 Millionen Events als Abbruchkriterium.
Ergebnisse: Mit OEDIPE gelingt unter Verwendung des Ergebnisses der MC-Simulation die Erzeugung der SAFs für ein VP des Ferkels. Für 28 Radionuklide wurden SAFs (mGy/MBq*s) für Gehirn, Leber, Gallenblase, Nieren, Dünn- und Dickdarm, Lunge, Herz, Pankreas, rotes Knochenmark, Milz, Magen, Schilddrüse, Thymus, Blase, Skelett, Wirbelsäule und Restkörper berechnet.
Schlussfolgerung: Unter Nutzung von OEDIPE wurde erstmals ein VP des Ferkels erzeugt und durch MC-Simulation die SAFs berechnet. Dieses VP steht der Implementation in verschiedenen am Markt verfügbare Softwaretools zur Verfügung. Seine Anwendbarkeit für die präklinische Inkorporationsdosimetrie wird nunmehr durch den Vergleich mit anderen, bereits implementierten VP weiter untersucht.
Keywords: Monte-Carlo, PET, Dosimetry, VOXEL Phantom
  • Abstract in refereed journal
    Nuklearmedizin 57(2018), V112
  • Lecture (Conference)
    56. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 18.-21.04.2018, Bremen, Deutschland

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Publ.-Id: 26379


Characterizing mineral wettabilities on a microscale by colloidal probe atomic force microscopy

Babel, B. M.; Rudolph, M.
For finely intergrown ores the characterization of reagent-mineral interactions in flotation systems holds difficult challenges for the applicability of standard techniques like hallimond tube tests or contact angle experiments or renders them impossible while other techniques might not work in an aqueous environment. We present the utilization of an atomic force microscope with a hydrophobic colloidal probe to characterize the wettabilities of individual mineral grains on a microscale. The sulfidic ore sample containing chalcopyrite, pyrite and quartz is investigated in an aqueous environment. The mineralogy of the sample is characterized by SEM+EDX and its wettability by contact angle measurements. Force mappings on the respective minerals are performed and allow a distinction between quartz, chalcopyrite and pyrite with the resulting force distributions. An additional focus in this paper lies on the heterogeneities within one mineral surface domain and the applicability for grain mappings.
Keywords: hydrophobic interaction, atomic force microscopy, wettabilities, adhesion imaging, flotation
  • Open Access Logo Minerals Engineering 121(2018), 212-219
    DOI: 10.1016/j.mineng.2018.02.003
  • Lecture (Conference)
    NanoScientific Forum Europe, 10.-12.10.2018, Freiberg, Deutschland

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Versatile Tri(pyrazolyl)phosphanes as Phosphorus Precursors for the Synthesis of Highly Emitting InP/ZnS Quantum Dots - Tri(pyrazolyl)phosphane als Vorstufen für die Synthese von stark emittierenden InP/ZnS-Quantenpunkten

Panzer, R.; Guhrenz, C.; Haubold, D.; Hübner, R.; Gaponik, N.; Eychmüller, A.; Weigand, J. J.
Tri(pyrazolyl)phosphanes (5R1,R2) are utilized as an alternative, cheap and low-toxic phosphorus source for the convenient synthesis of InP/ZnS quantum dots (QDs). From these precursors, remarkably long-term stable stock solutions (>6 months) of P(OLA)3 (OLAH=oleylamine) are generated from which the respective pyrazoles are conveniently recovered. P(OLA)3 acts simultaneously as phosphorus source and reducing agent in the synthesis of highly emitting InP/ZnS core/shell QDs. These QDs are characterized by a spectral range between 530-620 nm and photoluminescence quantum yields (PL QYs) between 51-62 %. A proof-of-concept white light-emitting diode (LED) applying the InP/ZnS QDs as a color-conversion layer was built to demonstrate their applicability and processibility.
Tri(pyrazolyl)phosphane werden als alternative kostengünstige und weniger toxische Phosphorquelle in der Synthese von InP/ZnS-Quantenpunkten (QDs) eingesetzt. Ausgehend von ihnen können langzeitstabile (>6 Monate) P(OLA)3-Stammlösungen (OLAH=Oleylamin) synthetisiert werden, aus denen sich die entsprechenden Pyrazole einfach zurückgewinnen lassen. P(OLA)3 fungiert in der Synthese von stark emittierenden InP/ZnS-QDs sowohl als Phosphorquelle als auch als Reduktionsmittel. Die erhaltenen Kern/Schale-Partikel zeichnen sich durch hohe Photolumineszenz-Quantenausbeuten von 51–62 % in einem Spektralbereich von 530-620 nm aus. Die Verarbeitung und Anwendung dieser InP/ZnS-QDs als Farbkonversionsschicht wurde anhand des Einsatzes in einer weißen Leuchtdiode demonstriert.
Keywords: hot injection, oleylamine, phosphorus, quantum dots, waste prevention - Heißinjektion, Oleylamin, Phosphor, Ressourcen-Schonung, Quantenpunkte

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Extremely high magnetoresistance and conductivity in the type-II Weyl semimetals WP2 and MoP2

Kumar, N.; Sun, Y.; Xu, N.; Manna, K.; Yao, M.; Süss, V.; Leermakers, I.; Young, O.; Förster, T.; Schmidt, M.; Borrmann, H.; Yan, B.; Zeitler, U.; Shi, M.; Felser, C.; Shekhar, C.
The peculiar band structure of semimetals exhibiting Dirac and Weyl crossings can lead to spectacular electronic properties such as large mobilities accompanied by extremely high magnetoresistance. In particular, two closely neighboring Weyl points of the same chirality are protected from annihilation by structural distortions or defects, thereby significantly reducing the scattering probability between them. Here we present the electronic properties of the transition metal diphosphides, WP2 and MoP2, which are type-II Weyl semimetals with robust Weyl points by transport, angle resolved photoemission spectroscopy and first principles calculations. Our single crystals of WP2 display an extremely low residual low-temperature resistivity of 3 nΩ cm accompanied by an enormous and highly anisotropic magnetoresistance above 200 million % at 63 T and 2.5 K. We observe a large suppression of charge carrier backscattering in WP2 from transport measurements. These properties are likely a consequence of the novel Weyl fermions expressed in this compound.

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Publ.-Id: 26376


Simulation of a counter-current horizontal gas/liquid flow experiment at the WENKA channel using a droplet entrainment model

Höhne, T.; Gabriel, S.
One drawback today in simulating horizontal wavy two-phase flows is that there is no treatment of droplet formation mechanisms at the liquid surface. For self-generating waves and slugs, the interfacial momentum exchange and the turbulence parameters have to be modelled correctly. Furthermore, understanding and considering the mechanism of droplet entrainment for heat and mass transfer processes is of great importance in the nuclear industry.
Therefore a step of improvement of modelling liquid/gas interfaces is the consideration of droplet entrainment mechanisms. The proposed entrainment model assumes that due to liquid turbulence the interface gets rough and wavy leading to the formation of droplets. The new approach is validated against existing horizontal two-phase flow data from the WENKA (Water ENtraninment Channel KArlsruhe) channel.
Tests were carried out for water and air at ambient pressure and temperature. High speed videometry was applied to obtain velocities from flow pattern maps of the rising and falling fluid. In the horizontal part of the channel with partially reversed flow the fluid velocities were measured by planar particle image velocimetry. The test MP 28 with droplet generation at the reversed flow conditions was utilized to compare it with the simulation data. The agreement of the experimental findings and CFD results is acceptable. Also the droplet mass flow was compared and showed the applicability of the droplet entrainment model. Further work is necessary to validate the model for different flow conditions.
Keywords: CFD, horizontal flow, AIAD, droplet entrainment, two-phase flow, HAWAC, HZDR, OVM, PIV, Isokinetic Sampling Probe, WENKA

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Publ.-Id: 26375


The γ-ray angular distribution in fast neutron inelastic scattering from iron

Beyer, R.ORC; Dietz, M.; Bemmerer, D.; Junghans, A. R.; Kögler, T.; Massarczyk, R.; Müller, S.; Schmidt, K.; Schwengner, R.; Szücs, T.; Takacs, M. P.; Wagner, A.
The angular distribution of γ-rays emitted after inelastic scattering of fast neutrons from iron was determined at the nELBE neutron time-of-flight facility. An iron sample of natural isotopic composition was irradiated by a continuous photo-neutron spectrum in the energy range from about 0.1 up to 10 MeV. The de-excitation γ-rays of the four lowest excited states of ⁵⁶Fe and the first excited state of ⁵⁴Fe were detected using a setup of five high-purity germanium (HPGe) detectors and five LaBr₃ scintillation detectors positioned around the sample at 30°, 55°, 90°, 125° and 150° with respect to the incoming neutron beam. The resulting angular distributions were fitted by Legendre polynomials up to 4th order and the angular distribution coefficients a₂ and a₄ were extracted. The angular distribution coefficients of three transitions in ⁵⁶Fe are reported here for the first time. The results are applied to a previous measurement of the inelastic scattering cross section determined using a single HPGe detector positioned at 125°. Using the updated γ-ray angular distribution, the previous cross section results are in good agreement with reference data.
Keywords: nELBE, neutron time-of-flight, angular distribution, iron

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Publ.-Id: 26374


Uranium(VI) complexes with a calix[4]arene-based 8-hydroxyquinoline ligand: Thermodynamic and structural characterization based on calorimetry, spectroscopy, and liquid-liquid extraction

Bauer, A.; Jäschke, A.ORC; Schöne, S.ORC; Barthen, R.; März, J.ORC; Schmeide, K.ORC; Patzschke, M.ORC; Kersting, B.ORC; Fahmy, K.ORC; Oertel, J.; Brendler, V.ORC; Stumpf, T.
The environmental aspects of ore processing and waste treatment call for an optimization of applied technologies. There, understanding of the structure and complexation mechanism on a molecular scale is indispensable. Here, the complexation of U(VI) with a calix[4]arene-based 8-hydroxyquinoline ligand was investigated by applying a wide range of complementary methods. In solution, the formation of two complex species was proven with stability constants of log ß1:1 = 5.94±0.02 and log ß2:1 = 6.33±0.01, respectively. The formation of the 1:1 complex was found to be enthalpy driven (∆H1:1 = (– 71.5±10.0) kJ mol–1; T∆S1:1 = (–37.57±10.0) kJ mol–1), whereas the second complexation step was found to be endothermic and entropy driven (∆H2:1 = (32.8±4.0) kJ mol–1; T∆S2:1 = (68.97±4.0) kJ mol–1). Moreover, the molecular structure of [UO2(H6L)(NO3)](NO3) (1) was determined by single-crystal X-ray diffraction. Concluding, radiotoxic U(VI) was separated from a Eu(III)-containing solution by the calix[4]arene-based ligand in solvent extractions.
Keywords: calixarene ∙ uranium ∙ chelate ∙ X-ray crystal ∙ spectroscopic properties ∙ calorimetry ∙ density functional theory ∙ liquid-liquid extraction

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Publ.-Id: 26373


Investigations of the Effects of the Variation of Fuel Assembly Positions in a core of a PWR

Konheiser, J.; Müller, S. E.; Seidl, M.
This work shows the impact of possible variations of the core geometry on the signal values of the ex-core instrumentation of a pressurized water reactor (PWR). Based on the potential influence on the signals, neutron fluxes have been determined for selected fuel assembly displacements using stationary Monte Carlo calculations. First, critical calculations were carried out for the chosen core configurations and corresponding surface sources on the core barrel were determined. In a second step transport calculations for the ionization chambers were performed using the surface sources. Typical data of a German PWR were used for the investigations.
Variation of fuel assembly positions in the outer region of the core were studied, which were directly opposite to the ex-core instrumentation. An increase of the neutron flux at the chambers of up to 4% has been calculated for a change in position of 1 mm between some fuel assemblies. The reason is an improved moderation of neutrons because of the larger water gap. This causes an increase in local power which leads to a greater leakage of neutrons over the core barrel. In addition, a dependence of this effect as a function of cycle burnup was analyzed.
Keywords: PWR type reactor; Monte Carlo calculation; safety analysis; ex-core instrumentation
  • Lecture (others)
    17. AAA Workshop, 04.12.2017, Garching, Germany

Permalink: https://www.hzdr.de/publications/Publ-26372
Publ.-Id: 26372


Coupling of ferromagnetism and structural phase transition in V2O3/Co bilayers

Wang, C.; Xu, C.; Wang, M.; Yuan, Y.; Liu, H.; Dillemans, L.; Homm, P.; Menghini, M.; Locquet, J.-P.; Haesendonck, C. V.; Zhou, S.; Ruan, S.; Zeng, Y.-J.
Interfacial coupling in hybrid magnetic heterostructures is being considered as a unique opportunity for functional material design. Here, we present the temperature dependence of magnetic properties of V2O3/Co bilayers influenced by the structural phase transition that is accompanied by a metal–insulator transition in V2O3. Both the coercivity and the magnetization of Co layer are strongly affected by the interfacial stress due to the magnetostrictive effect in the ferromagnetic film. The observed change in coercivity is as large as 59% in a narrow temperature range. The changes in the magnetic properties are reproducible and reversible, which are of importance for potential applications.
Keywords: metal–insulator transition, magnetostrictive coupling, structural phase transition, heterostructure

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Publ.-Id: 26371


An orthotopic xenograft model for high-risk non-muscle invasive bladder cancer in mice: influence of mouse strain, tumor cell count, dwell time and bladder pretreatment

Huebner, D.; Rieger, C.; Bergmann, R.; Ullrich, M.; Meister, S.; Toma, M.; Wiedemuth, R.; Temme, A.; Novotny, V.; Wirth, M. P.; Bachmann, M.; Pietzsch, J.ORC; Fuessel, S.
Background: Novel theranostic options for high-risk non-muscle invasive bladder cancer are urgently needed. This requires a thorough evaluation of experimental approaches in animal models best possibly reflecting human disease before entering clinical studies. Although several bladder cancer xenograft models were used in the literature, the establishment of an orthotopic bladder cancer model in mice remains challenging.
Methods: Luciferase-transduced UM UC 3LUCK1 bladder cancer cells were instilled transurethrally via 24G permanent venous catheters into athymic NMRI and BALB/c nude mice as well as into SCID-beige mice. Besides the mouse strain, the pretreatment of the bladder wall (trypsin or poly-L-lysine), tumor cell count (0.5×106 – 5.0×106) and tumor cell dwell time in the murine bladder (30 min – 2 h) were varied. Tumors were morphologically and functionally visualized using bioluminescence imaging (BLI), magnetic resonance imaging (MRI), and positron emission tomography (PET).
Results: Immunodeficiency of the mouse strains was the most important factor influencing cancer cell engraftment, whereas modifying cell count and instillation time allowed fine-tuning of the BLI signal start and duration – both representing the possible treatment period for the evaluation of new therapeutics. Best orthotopic tumor growth was achieved by transurethral instillation of 1.0×106 UM UC 3LUCK1 bladder cancer cells into SCID-beige mice for 2 h after bladder pretreatment with poly-L-lysine. A pilot PET experiment using 68Ga-cetuximab as transurethrally administered radiotracer revealed functional expression of epidermal growth factor receptor as representative molecular characteristic of engrafted cancer cells in the bladder.
Conclusions: With the optimized protocol in SCID-beige mice an applicable and reliable model of high-risk non-muscle invasive bladder cancer for the development of novel theranostic approaches was established.
Keywords: bioluminescence, luciferase, orthotopic xenograft models, small animal multimodal imaging, magnetic resonance imaging, optical imaging, positron emission tomography, transurethral instillation, UM-UC-3 cell line, urothelial carcinoma

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Nitric oxide-releasing selective cyclooxygenase-2 inhibitors as promising radiosensitizers in melanoma cells in vitro

Bechmann, N.; Hauser, S.; Hofheinz, F.; Kniess, T.; Pietzsch, J.ORC
Expression of cyclooxygenase-2 (COX-2) and subsequent higher availability of eicosanoids are important modulators of tumor radioresistance. Additionally, elevated COX-2 protein is closely associated with hypoxia, which itself is a key promoter of tumor radioresistance. In this regard, selective COX-2 inhibitors (coxibs) containing a nitric oxide (NO)-releasing moiety (NO-coxibs) are hypothesized to act as bifunctional radiosensitizers. Therefore, novel NO-coxibs with a (pyrazolyl)benzenesulfonamide lead were investigated in vitro. As model, two human melanoma cell lines were exposed to several doses of X-ray in presence or absence of the novel NO-coxibs or the corresponding coxib during irradiation. Cells were examined in clonogenic cell survival assays to determine radiosensitizing effects under both normoxic and hypoxic conditions. COX-2 protein expression of two melanoma cell lines with a dissimilar baseline COX-2 synthesis was increased by irradiation and, furthermore, by experimental hypoxia. Radiosensitivity of both cell lines was significantly enhanced by the novel NO-coxibs and, to a lesser extent, also by the corresponding coxib. Moreover, the most potent NO-coxib 5 significantly increased the radiosensitivity of both cell lines also under hypoxic conditions. By administration of 5 the required radiation dose for 10% survival could be reduced from 6.6 Gy (DMSO control) to 5.2 Gy (p<0.01) for the ‘COX-2-positive’ A2058 cells and from 4.2 Gy (DMSO control) to 3.2 Gy for the ‘COX-2-negative’ Mel-Juso cells. The results confirm the auspicious bifunctional approach of the novel NO-coxibs as potential adjuvant radiosensitizers under normoxic and hypoxic conditions in vitro. Further studies are necessary to confirm the promising findings in vivo.
Keywords: Chemoradiotherapy, malignant melanoma, radiosensitization, multi-target approach, carbonic anhydrase-IX, CoCl2-induced hypoxia
  • Open Access Logo Annals of Radiation Therapy and Oncology 1(2017)2, 1010

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Energy balance of the carbon dioxide injection facility in Ketzin, Germany

Wiese, B. U.; Nimtz, M.
Injection of 67 kt carbon dioxide was carried out between 2008 and 2013 at the test site for geological storage in
Ketzin, Germany. The source carbon dioxide was delivered in liquid phase. The injection facility has had a three
step process chain: (i) pressure increase by a liquid pump, (ii) temperature increase by ambient air vaporizers
and (iii) temperature increase by an electrical vaporizer including phase change to gaseous conditions. The
ambient vaporizers reduced electrical power demand but the weather dependence induced some kind of uncertainty,
further their power could not be measured. In the cases when the carbon dioxide was evaporated
within the ambient vaporizers, the heat demand increased such that the driving temperature was not enough for
full vaporization. However, the gas to liquid ratio is unknown wherefore the heating power can not be calculated
over the ambient vaporizer. This is addressed, as the electric energy consumption was most reduced during the
two phase operation.
For these intervals, two phase gas–liquid conditions prevailed in the pipeline. Unlike conjectured, flow
conditions remained stable and did not vary significantly from single phase behavior. The current work – for the
first time – presents a detailed analysis of energy input and losses of the carbon dioxide injection process based
on field data and simulations. A modified process chain is proposed to switch the electric energy demand to an
ambient heat source, reducing the electrical energy use per ton carbon dioxide by up to 90 %. The work provides
insight for planning future injection devices that involve liquid carbon dioxide in the process chain.
Keywords: CCS, Injection facility, Storage, Carbon dioxide, Ketzin, Ambient air heat exchanger, Vaporization

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Chemical analysis of solid-liquid interfaces by in-situ Rutherford Backscattering Spectrometry

Baghban Khojasteh Mohammadi, N.; Heller, R.
Solid-liquid interfaces are important locations for various reactions to occur in biological, chemical and physical processes [1-3]. Recently, an experimental setup for in-situ Rutherford Backscattering Spectrometry (RBS) technique has been installed at the 2 MV Van-de-Graaff accelerator at Ion Beam Center (IBC) of the Helmholtz-Zentrum Dresden-Rossendorf to analyze solid-liquid interfaces as well as to conduct electro-chemistry experiments. The focus of the project is to perform experiments in different fields utilizing this quantitative, non-destructive and standard free ion beam analysis technique for solid-liquid interfaces. A Si3N4 window separates the liquid in the cell from vacuum in the beam line. He+ beam with E = 1.7 MeV is employed to bombard the samples. For feasibility tests, the cell was filled with air, Ne, He, Xe and DIH2O respectively and RBS and Particle Induced X-Ray Emission Spectroscopy (PIXE) spectra were recorded. To examine the efficiency of the technique, ion backscattering studies of the solid-liquid using 0.1M solutions of Cu(NO3) and AgNO3 have been performed and are compared to the literature [4].
[1] Kötz et al., Electrochimica acta. 31 (1986) 169.
[2] Morita et al., Radiation Physics and Chemistry. 49 (1997) 603.
[3] Hodnik et al., Accounts of chemical research. 49 (2016) 2015.
[4] Forster et al., Nuclear Instruments and Methods in Physics Research Section B. 28 (1987) 385.
Keywords: solid-liquid, interface analysis, in-situ RBS
  • Poster
    DPG Spring Meeting of the Condensed Matter Section (SKM), 11.-16.03.2018, Berlin, Deutschland

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Publ.-Id: 26367


Potential of asphericity as a novel diagnostic parameter in the evaluation of patients with Ga-68-PSMA-HBED-CC PET-positive prostate cancer lesions

Meissner, S.; Janssen, J.; Prasad, V.; Brenner, W.; Diederichs, G.; Hamm, B.; Hofheinz, F.; Makowski, M.
Background: The aim of this study was to evaluate the diagnostic value of the asphericity (ASP) as a novel quantitative parameter, reflecting the spatial heterogeneity of tracer uptake, in the staging process of patients with Ga-68-PSMA-HBED-CC positron emission tomography (PET)-positive prostate cancer (PC). In this study, 37 patients (median age 72 years, range 52-82 years) with newly diagnosed PC, who received a Ga-68-PSMA-HBED-CC PET fused with computed tomography (Ga-68-PSMA-PET/CT), a magnetic resonance imaging (MRI) of the prostate, and a core needle biopsy (within 74.2 8 +/- 80.2 days) with an available Gleason score (GSc) were extracted from the local database. The ASP and the viable tumor volume (VTV) was calculated using the rover software (ABX GmbH, Radeberg, Germany), a segmentation tool for automated tumor volume delineation. Additionally, parameters including total lesion binding rate (TLB), maximum, mean and peak standardized uptake value (SUVmax/mean/peak), prostate-specific antigen (PSA), D'Amico classification, and prostate imaging reporting and data system (PI-RADS) were analyzed.

Results: The ASP mean differed significantly (p = 0.05) between the different GSc groups: GSc 6-7: 11.9 +/- 4.8%, GSc 8: 25.5 +/- 4.8%, GSc
9-10: 33.3 +/- 6.8%. A significant correlation between ASP and GSc (rho = 0.88; CI 0.78-0.94; p < 0.05) was measured. The ASP enabled an independent (p > 0.05) prediction of the GSc. A moderate correlation was measured between ASP and the D'Amico classification (rho = 0.6; CI 0.32-0.78; p < 0.05). The VTV showed a moderate correlation with the SUVmax (rho = 0.58; CI 0.32-0.76; p < 0.05) and the GSc (rho = 0.51; CI 0.23-0.72; p < 0.05).

Conclusion: The asphericity in Ga-68-PSMA-PET could represent a promising novel quantitative parameter for an improved non-invasive tumor staging of patients with PC.
Keywords: Prostatic neoplasms Positron emission tomography computed tomography Gleason score Asphericity Histopathology

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Drone-borne mineral exploration in Central-West Greenland

Zimmermann, R.ORC; Rosa, D.; Gloaguen, R.
During the last two field seasons, two different type of Unmanned Aerial Systems were tested and evaluated for mineral mapping in Central-West Greenland. A fixed wing system turned out to be more suitable as large areas can be covered faster and more efficiently.
In 2017, a sensefly ebeePlus fixed-wing system with a 4 channel multispectral Sequoia camera (4 channels in VIS-NIR with 1.2 MP + 16 MP RGB camera) was deployed. Flight altitude was set to achieve 11cm ground sampling distance (GSD). Processing followed in-house routines using Structure-from-Motion photogrammetry to get Digital Surface Models (DSM) and geometrically corrected orthomosaics. In total 6.4 km2 of the VMS showings in Kangiusap Kuua at Svartenhuk were covered. The VMS showings are hosted in the Nukavsak Fm of the Paleoproterozoic Karrat group. In certain stratigraphic horizon within the meta-turbidites, basalt flows with associated sulphide-rich sea-floor alteration occur. Flight plans were set to cover both alteration and host-rock. A validation dataset includes sampling and spectral characterisation of selected hand specimen.
Gossans are easily mappable by integrated morphological and spectral analysis as they form ridges with a distinct iron feature. Moreover, traces of fractures and faults, their spatial distribution and relation to the altered horizon is retrieved.
This further highlights the capability of drone-borne application for high-resolution reconnaissance mapping within short turn-around times. Intermediate insights from the project Multi-sensor drones for geological mapping (MULSEDRO) will facilitate the application of drones under unfavourable conditions.
  • Lecture (Conference)
    33rd Nordic Geological Winter Meeting, 10.-12.01.2018, København, Danmark

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Publ.-Id: 26365


Chelation of heavy group 2 (radio)metals by p-tert-butylcalix[4]arene-1,3-crown-6 and logK determination via NMR

Bauer, D.; Gott, M.; Steinbach, J.; Mamat, C.ORC
A crown-bridged calix[4]arene scaffold was investigated as lead compound for the ligation of heavy alkaline earth metals such as strontium and barium, which appear to be useful for radiopharmaceutical applications in diagnosis as well as in radiotherapy. The ability of p-tert-butylcalix[4]arene-1,3-crown-6 (1) in particular to chelate cations, such as group 1 and 2 metal ions or ammonium ions is well known. Also, the manifold possibilities of structural modification on the upper- and lower-rim as well as on the crown itself produce properties that may lead to a highly selective and effective chelating agent. In this work, titration experiments of the perchlorate salts of Ba2+, Sr2+ and Pb2+ with ligand 1 were performed to determine their stability constants (logK = 4.7, 4.3, and 3.3, respectively) by 1H NMR measurements in acetonitrile-d3.

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Permalink: https://www.hzdr.de/publications/Publ-26364
Publ.-Id: 26364


Feasible device architectures for ultra-scaled CNTFETs

Pacheco-Sanchez, A.; Fuchs, F.; Mothes, S.; Zienert, A.; Schuster, J.; Gemming, S.; Claus, M.
Feasible device architectures for ultra-scaled CNTFETs are studied down to 5.9 nm using a multiscale simulation approach covering electronic quantum transport simulations and TCAD numerical device simulations. Schottky-like and ohmic-like contacts are considered. The simplified approach employed in the numerical device simulator is critically evaluated and verified by means of comparing the results with electronic quantum simulation results of an identical device. Different performance indicators such as the switching speed, switching energy, the subthreshold slope, Ion/Ioff-ratio, among others, are extracted for different device architectures. These values guide the evaluation of the technology for different application scenarios. For high-performance logic applications, the buried gate CNTFET is claimed to be the most suitable structure.
Keywords: CNTFETs, Logic gates, Numerical models, Computer architecture, Performance evaluation, Electric potential, Effective mass

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Permalink: https://www.hzdr.de/publications/Publ-26363
Publ.-Id: 26363


Investigation of the environmental impact of nanoparticles using smart radiolabeling

Schymura, S.; Fricke, T.; Hildebrand, H.; Steudtner, R.; Hübner, R.; Mansel, A.; Franke, K.
The investigation of the environmental impact of nanoparticles is greatly hindered by a lack of suitable detection methods, especially at the low, environmentally relevant concentrations. The radiolabeling of nanoparticles can overcome these setbacks and provides a possibility of detecting nanoparticles at minimal concentrations against high elemental and particle backgrounds.
In addition to that the sophisticated use of different labeling strategies allows the direct measurement of processes such as dissolution and their relevant in, for example, plant uptake. Using different labeling stragies we produce radiolabeled CeO2 nanoparticles with different radioactivity release kinetics upon dissolution. This enabled us to measure the uptake and translocation of CeO2 nanoparticles in plants and to identify the predominant uptake pathway in the form of particles, as opposed to an uptake of their dissolved remains.
Keywords: Radiomarkierung, radiolabeling Nanopartikel, nanoparticles Umwelt, environment Pflanzen, plants
  • Lecture (Conference)
    13th Cycleur – European Network of Cyclotron Research Centers – Workshop, 23.-24.11.2017, Lissabon, Portugal

Permalink: https://www.hzdr.de/publications/Publ-26360
Publ.-Id: 26360


Novel Humanized and Highly Efficient Bispecific Antibodies Mediate Killing of Prostate Stem Cell Antigen-Expressing Tumor Cells by CD8+ and CD4+ T Cells

Feldmann, A.; Arndt, C.; Töpfer, K.; Stamova, S.; Krone, F.; Cartellieri, M.; Koristka, S.; Michalk, I.; Lindemann, D.; Schmitz, M.; Temme, A.; Bornhäuser, M.; Ehninger, G.; Bachmann, M.
Prostate cancer is the most common noncutaneous malignancy in men. The prostate stem cell Ag (PSCA) is a promising target for immunotherapy of advanced disease. Based on a novel mAb directed to PSCA, we established and compared a series of murine and humanized anti-CD3–anti-PSCA single-chain bispecific Abs. Their capability to redirect T cells for killing of tumor cells was analyzed. During these studies, we identified a novel bispecific humanized Ab that efficiently retargets T cells to tumor cells in a strictly Ag-dependent manner and at femtomolar concentrations. T cell activation, cytokine release, and lysis of target cells depend on a cross-linkage of redirected T cells with tumor cells, whereas binding of the anti-CD3 domain alone does not lead to an activation or cytokine release. Interestingly, both CD8+ and CD4+ T cells are activated in parallel and can efficiently mediate the lysis of tumor cells. However, the onset of killing via CD4+ T cells is delayed. Furthermore, redirecting T cells via the novel humanized bispecific Abs results in a delay of tumor growth in xenografted nude mice.

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Permalink: https://www.hzdr.de/publications/Publ-26359
Publ.-Id: 26359


Retargeting of T Cells to Prostate Stem Cell Antigen ExpressingTumor Cells: Comparison of Different Antibody Formats

Feldmann, A.; Stamova, S.; Bippes, C. C.; Bartsch, H.; Wehner, R.; Schmitz, M.; Temme, A.; Cartellieri, M.; Bachmann, M.
BACKGROUND. Prostate cancer (PCa) is the most common malignant disease in men. Novel treatment options are needed for patients after development of metastatic, hormone-refractory disease or for those who have failed a local treatment. The prostate stem cell antigen (PSCA) is expressed in >80% of primary PCa samples and bone metastases. Its expression is increased both in androgen-dependent and independent prostate tumors, particularly in carcinomas of high stages and Gleason scores. Therefore, PSCA is an attractive target for immunotherapy of PCa by retargeting of T cells to tumor cells.
METHODS. Aseries of different bispecific antibody formats for retargeting of T cells to tumor cells were described but, only very limited data obtained by side by side comparison of the different antibody formats are available. We established two novel bispecific antibodies in different formats. The functionality of both constructs was analyzed by FACS and chromium release assays. In parallel, the release of pro-inflammatory cytokines was determined by ELISA.
RESULTS AND CONCLUSIONS. Irrespective of the underlying antibody format, both novel bispecific antibodies cause an efficient killing of PSCA-positive tumor cells by preand non-pre-activated T cells. Killing and release of pro-inflammatory cytokines requires an antigen specific cross-linkage of the T cells with the target cells.
Keywords: single chain bispecific antibodies; prostate cancer; T cell targeting; immunotherapy

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Publ.-Id: 26358


Retargeting of Human Regulatory T Cells by Single-Chain Bispecific Antibodies

Koristka, S.; Cartellieri, M.; Theil, A.; Feldmann, A.; Arndt, C.; Stamova, S.; Michalk, I.; Töpfer, K.; Temme, A.; Kretschmer, K.; Bornhäuser, M.; Ehninger, G.; Schmitz, M.; Bachmann, M.
Bispecific Abs hold great potential for immunotherapy of malignant diseases. Because the first components of this new drug class are now entering clinical trials, all aspects of their mode of action should be well understood. Several studies proved that CD8+ and CD4+ effector T cells can be successfully redirected and activated against tumor cells by bispecific Abs both in vitro and in vivo. To our knowledge, this study provides the first evidence that bispecific Abs can also redirect and activate regulatory T cells against a surface Ag, independently of their TCR specificity. After cross-linking, via a bispecific Ab, redirected regulatory T cells upregulate the activation markers CD69 and CD25, as well as regulatory T cell-associated markers, like CTLA-4 and FOXP3. The activated regulatory T cells secrete the immunosuppressive cytokine IL-10, but, in contrast to CD8+ and CD4+ effector T cells, almost no inflammatory cytokines. In addition, the redirected regulatory T cells are able to suppress effector functions of activated autologous CD4+ T cells both in vitro and in vivo. Therefore, the potential risk for activation of regulatory T cells should be taken into consideration when bispecific Abs are applied for the treatment of malignant diseases. In contrast, an Ag/tissue-specific redirection of regulatory T cells with bispecific Abs holds great potential for the treatment of autoimmune diseases and graft rejection.

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Publ.-Id: 26357


Retargeting of regulatory T cells to surface-inducible autoantigen La/SS-B

Koristka, S.; Cartellieri, M.; Arndt, C.; Bippes, C. C.; Feldmann, A.; Michalk, I.; Wiefel, K.; Stamova, S.; Schmitz, M.; Ehninger, G.; Bornhäuser, M.; Bachmann, M.
The nuclear autoantigen La can be detected on the surface of dying cells. Here we present an assay which enables us to show that La protein is not limited to the surface of dying cells but will be released upon stress-induced cell death. As released La protein tightly binds to the surface of neighboring intact cells we asked the question whether or not La protein could serve as a stress-inducible target e.g. for redirecting of regulatory T cells (Tregs) into damaged tissues to downregulate an immune response. In order to provide first proof of concept we developed a novel fully humanized single-chain bispecific antibody (bsAb) which on the one hand is directed to the La antigen and on the other hand to the CD3 complex of T cells. A cross-linkage of Tregs with La-decorated target cells mediated by this bsAb resulted indeed in the activation of the Tregs in a target-dependent manner. Moreover, such bsAb activated Tregs displayed a potent suppressive capacity and negatively influenced proliferation, expansion and cytokine production of autologous CD4+ and CD8+ Teff cells.
Keywords: La/SS-B, Regulatory T cells, Single-chain bispecific antibodies, Immunotherapy

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Publ.-Id: 26356


Interaction of uranyl ion and DNA

Tsushima, S.; Takao, K.; Mochizuki, Y.; Rossberg, A.; Komeiji, Y.
Abstract for this presentation is only available in Japanese.
  • Poster
    Annual meeting of the Japanese Society for Extremophiles, 11.-12.11.2017, Tsukuba, Japan

Permalink: https://www.hzdr.de/publications/Publ-26355
Publ.-Id: 26355


Effect of isotropic stress on dislocation bias factor in bcc iron: an atomistic study

Bakaev, A.; Terentyev, D.; Chang, Z.; Posselt, M.; Olsson, P.; Zhurkin, E. E.
The effect of externally applied stress on the dislocation bias factor (BF) in bcc iron has been studied using a combination of atomistic static calculations and finite element integration. Three kinds of dislocations were considered, namely, a0/2〈1 1 1〉{1 1 0} screw, a0/2〈1 1 1〉{1 1 0} edge and a0〈1 0 0〉{0 0 1} edge dislocations. The computations reveal that the isotropic crystal expansion leads to an increasing or constant dislocation bias, depending on the Burgers vector and type of dislocation. On the other hand, compressive stress reduces the dislocation bias for all the dislocations studied. Variation of the dislocation BF depending on dislocation type and Burgers vector is discussed by analysing the modification of the interaction energy landscape and the capture efficiency values for the vacancy and self-interstitial atom.
Keywords: dislocation bias factor, external stress, Ferritic steels, molecular statics

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Publ.-Id: 26354


Combinatorial antigen recognition with balanced signaling promotes selective tumor eradication by engineered T cells

Kloss, C. C.; Condomines, M.; Cartellieri, M.; Bachmann, M.; Sadelain, M.
Current T-cell engineering approaches redirect patient T cells to tumors by transducing them with antigen-specific T-cell receptors (TCRs) or chimeric antigen receptors (CARs) that target a single antigen. However, few truly tumor-specific antigens have been identified, and healthy tissues that express the targeted antigen may undergo T cell–mediated damage. Here we present a strategy to render T cells specific for a tumor in the absence of a truly tumor-restricted antigen. T cells are transduced with both a CAR that provides suboptimal activation upon binding of one antigen and a chimeric costimulatory receptor (CCR) that recognizes a second antigen. Using the prostate tumor antigens PSMA and PSCA, we show that co-transduced T cells destroy tumors that express both antigens but do not affect tumors expressing either antigen alone. This ‘tumor-sensing’ strategy may help broaden the applicability and avoid some of the side effects of targeted T-cell therapies.

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Publ.-Id: 26353


Redirection of T cells with a first fully humanized bispecific CD33–CD3 antibody efficiently eliminates AML blasts without harming hematopoietic stem cells

Arndt, C.; von Bonin, M.; Cartellieri, M.; Feldmann, A.; Koristka, S.; Michalk, I.; Stamova, S.; Bornhäuser, M.; Schmitz, M.; Ehninger, G.; Bachmann, M.
Redirection of T cells with a first fully humanized bispecific
CD33–CD3 antibody efficiently eliminates AML blasts without
harming hematopoietic stem cells

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Publ.-Id: 26352


Elastic moduli of the distorted Kagome-lattice ferromagnet Nd3Ru4Al12

Suzuki, T.; Mizuno, T.; Takezawa, K.; Kamikawa, S.; Andreev, A. V.; Gorbunov, D. I.; Henriques, M. S.; Ishii, I.
The distorted kagome-lattice compound Nd3Ru4Al12 has the hexagonal structure. This compound is reported as a ferromagnet in which spins are aligned along the c-axis with the Curie temperature Tc = 39 K. The nature of localized f-electrons is expected in Nd3Ru4Al12, and magnetic anisotropy can be attributed to a crystal electric field (CEF) effect. We performed ultrasonic measurements on a Nd3Ru4Al12 single-crystalline sample in order to investigate the phase transition at TC and the CEF effect. All longitudinal and transverse elastic moduli increase monotonically with decreasing temperature, and no clear elastic softening due to a quadrupole interaction is detected under the hexagonal CEF. This result is in contrast to an isomorphic compound Dy3Ru4Al12 with a remarkable elastic softening of the transverse modulus C44. At the ferromagnetic phase transition, the moduli show obvious elastic anomalies, suggesting characteristic couplings between a strain and a magnetic order parameter.

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Publ.-Id: 26351


Magnetohydrodynamic instabilites in aluminium reduction cells

Weber, N.; Herreman, W.; Horstmann, G.; Nore, C.; Weier, T.
Übersicht über Theorie und numerische Simulation von Aluminium-Reduktionszellen.
  • Lecture (others)
    Aluminium-Reduktions-Treffen, 16.11.2017, Wuppertal, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26350
Publ.-Id: 26350


Magnetic nanomaterials

Josten, E.; Glavic, A.; Meertens, D.; Wetterskog, E.; Bersgtröm, L.; Brückel, T.; Lindner, J.
Magnetic nanomaterials and their assembly in highly correlated structures are of great interest for future applications as e.g. spin-based data storage media or as material for magnon-spintronics. These systems exhibit unique physical properties like superparamagnetism or symmetry breaking emerging due to their limited size. Individual nanomaterials can be combined as building blocks for so called superstructures where the combination of the different functionalities creates a novel multi-functional system.
Recently, more and more well-defined nanoobjects became available and the advances in measurement methods allow a characterization of these systems. For example, single micrometer-sized three-dimensional magnetic nanoparticle assemblies are available, exhibiting a high degree of structural order close to that of an atomic crystal [1,2]. These systems provide a good basis for the magnetic investigation of nanoparticle superstructures.
The work to be presented focuses on the fundamental structural and magnetic research on such objects and their functionalization. For the investigation we make use of different complementary measurement methods like small angle x-ray and neutron scattering or using microresonators, which provide the necessary sensitivity for the investigation of magnetic properties of a single nano- or micrometer-sized object using ferromagnetic resonance (FMR) [3].
Keywords: nanoparticles, scattering
  • Invited lecture (Conferences)
    JCNS Workshop 2017, 10.-13.10.2017, Tutzing, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26349
Publ.-Id: 26349


Highly ordered 3D nanoparticle superlattices investigated by microresonator ferromagnetic resonance

Josten, E.; Narkowicz, R.; Kakay, A.; Meertens, D.; Lennart, B.; Brückel, T.; Fassbender, J.; Lindner, L.
Magnetic nanoparticles and their assembly into highly correlated superstructures are of great interest for future applications, e.g. as material for magnon-spintronic. These systems are not only distinguished by the obvious miniaturization but by their novel physical properties emerging due to their limited size and ordered arrangement. These superstructures are formed from nanometer-sized building blocks ordered like atoms in a crystal, which render them a new class of materials.
Recently, single micrometer-sized three-dimensional magnetic nanoparticle assemblies became available, exhibiting a high degree of structural order close to that of an atomic crystal. These systems provide a good basis for the magnetic investigation of nanoparticle superstructures.

Novel microresonators, provide the necessary sensitivity for the investigation of magnetic properties of nano- and micrometer-sized objects using ferromagnetic resonance (FMR) [1,2]. Due to the much higher filling factor as compared to conventional microwave cavities, they offer several orders of magnitude increased sensitivity gain. A focused ion beam was used to isolate an individual 3D mesocrystal from an ensemble and to transfer it into the microresonator loop (Fig. 1). The FMR study reveals the magnetic anisotropy of the single mesocrystal (Fig. 2), which is corroborated by micromagnetic simulations. It was possible for us to functionalize the system and to set the magnetic easy axis of the mesocrystal via pre-defining their shape.
Keywords: nanoparticle
  • Lecture (Conference)
    INTERMAG Europe 2017, 24.-28.04.2017, Dublin, Irland

Permalink: https://www.hzdr.de/publications/Publ-26348
Publ.-Id: 26348


Direct measurement of the flow field with GeoPET as the starting point for reactive transport modelling

Kulenkampff, J.; Karimzadeh, L.; Eichelbaum, S.; Lippmann-Pipke, J.; Fischer, C.
We present a RTM workflow which is based on the direct experimental derivation of effective volume and velocity vector field from sequential positron emission tomograms (PET) of the tracer transport in geologic materials. The focus on tracer concentration incorporates unconstrained upscaling from molecular sensitivity to the millimeter scale. This workflow allows minimizing deviations from the experiment and computational expenses.
Keywords: tracer, dynamics of flow, process tomography, reactive transport
  • Lecture (Conference)
    Computational Methods in Water Resources (CMWR), 03.-07.06.2018, Saint Malo, France

Permalink: https://www.hzdr.de/publications/Publ-26347
Publ.-Id: 26347


Felsenkeller 5 MV underground accelerator: Towards the Holy Grail of Nuclear Astrophysics 12C(α,γ)16O

Bemmerer, D.
Underground ion accelerator laboratories such as the LUNA 0.4 MV accelerator in Italy are indispensable in order to precisely measure charged particle induced nuclear reaction cross sections. The rock overburden attenuates the cosmic ray induced background and enables the measurement of very low interaction rates. The first of the new generation of higher-energy underground accelerators is the Felsenkeller 5 MV machine in Dresden/Germany, under construction and due to open late 2017. The cross sections of several nuclear reactions relevant to nucleosynthesis in a supernova and/or its precursor are not well known, with effects on the nucleosynthetic output of these events. Of these reactions, it is planned to study the 12C(alpha,gamma), 22Ne(alpha,gamma), 40Ca(alpha,gamma), and several other cases at Felsenkeller. The scientific motivation and state of work will be reviewed. It is hoped that the Felsenkeller accelerator will be widely used, including researchers from as many German universities as possible.
Keywords: Underground nuclear astrophysics Felsenkeller Helium burning
  • Invited lecture (Conferences)
    Arbeitstreffen Kernphysik, 02.-09.03.2017, Schleching, Deutschland
  • Lecture (Conference)
    Workshop on Nuclear Astrophysics at the Dresden Felsenkeller, 26.-28.06.2017, Dresden, Deutschland
  • Lecture (Conference)
    Nuclear Physics in Astrophysics VIII, 20.06.2017, Catania, Italien
  • Invited lecture (Conferences)
    16th International Symposium on Capture Gamma-Ray Spectroscopy and Related Topics (CGS16), 19.09.2017, Shanghai, China

Permalink: https://www.hzdr.de/publications/Publ-26346
Publ.-Id: 26346


Molecular encapsulator on the surface of magnetic nanoparticles. Controlled drug release from calcium Ferrite/Cyclodextrin–tethered polymer hybrid

Ramasamy, S.; Reuther, H.; Adyanpuram, M. N. M. S.; Enoch, I. V. M. V.; Potzger, K.; Samathanam, B.
Magnetic nanoparticles (MNPs) are intriguing due to their potency to deliver anti-cancer drugs. This paper presents the inference from our experimental attempts to add merit to the concept of magnetic drug carrier, by designing calcium ferrite nanoparticles and coating them with a biocompatible dextran tethered with a hydrophobic cavity-containing molecule, β-cyclodextrin (β-CD). The size, crystal system, and the morphology of the MNPs are studied. The magnetic properties are explored using vibrating sample magnetometry, SQUID and Mössbauer spectroscopy. The roughly 75 nm MNPs, encapsulated with the β-CD–dextran conjugate allows a slow and sustained in vitro release of the loaded anti-cancer drug, Camptothecin, from the polymer shell. The study of cytotoxicity reveals that the loaded Camptothecin retains its potency as efficient as an effective carrier of the anti-cancer drug. Further, the toxicity of the nanomaterial is tested on an organism which is highly sensitive to toxicity i.e., brine shrimp (Artemia salina). The polymer coating brings down the toxicity of the MNPs.
Keywords: Cyclodextrin Drug release Host-guest interface Magnetic nanoparticles Surface functionalization

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Publ.-Id: 26345


Felsenkeller 5 MV underground accelerator: Muon, neutron, 𝛾-ray background and project status

Bemmerer, D.
Motivated by the success of the world's only underground ion accelerator, LUNA 0.4 MV in Italy, a project for a higher-energy underground accelerator is underway in Dresden. A 5\,MV Pelletron accelerator with double charging chains and provision for intensive ^1H^+, ^4He^+, and ^{12}C^+ beams based on external and internal ion sources is currently being installed in the Felsenkeller underground site in Dresden. Civil construction work in Felsenkeller will be completed in August 2017. The nine Felsenkeller tunnels are shielded from cosmic rays by 45\,m rock overburden, attenuating the background in radiation detectors. New data on the muon, neutron, and $\gamma$ background in Felsenkeller will be shown, and used for a discussion on the feasibility of low-background experiments there. The new accelerator will be open for outside users, and its most important experimental capabilities will be summarized.
Keywords: Underground Nuclear Astrophysics Felsenkeller
  • Lecture (Conference)
    Frühjahrstagung, 30.03.2017, Münster, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26344
Publ.-Id: 26344


Recent progress on hydrogen and helium burning at the LUNA 400 kV underground accelerator

Bemmerer, D.
n-beam radiative-capture experiments at low astrophysical energies require experiments in ultra-low background conditions. The Laboratory for Underground Nuclear Astrophysics (LUNA) 0.4\,MV accelerator at INFN Gran Sasso, Italy, is so far the only underground ion accelerator in the world. Recent progress at LUNA regarding the $^{22}$Ne(p,$\gamma$)$^{23}$Na [1,2], $^{22}$Ne($\alpha$,$\gamma$)$^{26}$Mg, and $^{17}$O(p,$\alpha$)$^{14}$N [3] reactions will be reviewed. The project for the new, 3.5 MV LUNA-MV accelerator is on track and will be summarized.
Keywords: Nuclear Astrophysics Hydrogen burning
  • Lecture (Conference)
    Frühjahrstagung, 27.03.2017, Münster, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26343
Publ.-Id: 26343


Constraining the 7Be(p,gamma)8B S -factor with the new precise 7Be solar neutrino flux from Borexino

Takács, M. P.; Bemmerer, D.; Junghans, A. R.; Zuber, K.
Among the solar fusion reactions, the rate of the 7Be(p,γ)8B reaction is one of the most difficult to determine rates. In a number of previous experiments, its astrophysical S-factor has been measured at E = 0.1-2.5 MeV center-of-mass energy. However, no experimental data is available below 0.1 MeV. Thus, an extrapolation to solar energies is necessary, resulting in significant uncertainty for the extrapolated S-factor. On the other hand, the measured solar neutrino fluxes are now very precise. Therefore, the problem of the S-factor determination is turned around here: Using the measured 7Be and 8B neutrino fluxes and the Standard Solar Model, the 7Be(p,γ)8B astrophysical S-factor is determined at the solar Gamow peak. In addition, the 3He(α,γ)7Be S-factor is redetermined with a similar method.
Keywords: Nuclear Astrophysics Solar neutrinos Nuclear reaction rate Solar fusion

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Publ.-Id: 26342


LUNA: Status and Prospects

Broggini, C.; Bemmerer, D.; Caciolli, A.; Trezzi, D.
The essential ingredients of nuclear astrophysics are the thermonuclear reactions which shape the life and death of stars and which are responsible for the synthesis of the chemical elements in the Universe. Deep underground in the Gran Sasso Laboratory the cross sections of the key reactions responsible for the hydrogen burning in stars have been measured with two accelerators of 50 and 400 kV voltage right down to the energies of astrophysical interest. As a matter of fact, the main advantage of the underground laboratory is the reduction of the background. Such a reduction has allowed, for the first time, to measure relevant cross sections at the Gamow energy. The qualifying features of underground nuclear astrophysics are exhaustively reviewed before discussing the current LUNA program which is mainly devoted to the study of the Big-Bang nucleosynthesis and of the synthesis of the light elements in AGB stars and classical novae. The main results obtained during the study of reactions relevant to the Sun are also reviewed and their influence on our understanding of the properties of the neutrino, of the Sun and of the Universe itself is discussed. Finally, the future of LUNA during the next decade is outlined. It will be mainly focused on the study of the nuclear burning stages after hydrogen burning: helium and carbon burning. All this will be accomplished thanks to a new 3.5 MV accelerator able to deliver high current beams of proton, helium and carbon which will start running under Gran Sasso in 2019. In particular, we will discuss the first phase of the scientific case of the 3.5 MV accelerator focused on the study of 12C+12C and of the two reactions which generate free neutrons inside stars: 13C(α,n)16O and 22Ne(α,n)25Mg.
Keywords: Nuclear Astrophysics LUNA Laboratory Underground for Nuclear Astrophysics

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Publ.-Id: 26341


Modification of surface properties of solids by femtosecond LIPSS writing: comparative studies on silicon and stainless steel

Varlamova, O.; Hoefner, K.; Ratzke, M.; Reif, J.; Sarker, D.
We investigate the implication of modified surface morphology on wettability of stainless steel (AISI 304) and silicon (100) targets covered by laser-induced periodic surface structures (LIPSS) on extended areas (10 × 10 mm2). Using multiple pulses from a Ti: Sapphire laser (790 nm/100 fs/1 kHz) at a fluence in the range of 0.35–2.1 J/cm2 on a spot of 1.13 × 10− 4 cm2, we scanned the target under the spot to cover a large area. A systematical variation of the irradiation dose by changing the scanning speed and thus dwelling time per spot results in the formation of surface patterns ranging from very regular linear structures with a lateral period of about 500–600 nm to complex patterns of 3D microstructures with several-µm feature size, hierarchically covered by nano-ripples.

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Publ.-Id: 26340


Surface modifications of crystal-ion-sliced LiNbO3 thin films by low energy ion irradiations

Bai, X.; Shuai, Y.; Gong, C.; Wu, C.; Luo, W.; Böttger, R.; Zhou, S.; Zhang, W.
Single crystalline 128°Y-cut LiNbO3 thin films with a thickness of 670 nm are fabricated onto Si substrates by means of crystal ion slicing (CIS) technique, adhesive wafer bonding using BCB as the medium layer to alleviate the large thermal coefficient mismatch between LiNbO3 and Si, and the X-ray diffraction pattern indicates the exfoliated thin films have good crystalline quality. The LiNbO3 thin films are modified by low energy Ar+ irradiation, and the surface roughness of the films is decreased from 8.7 nm to 3.4 nm. The sputtering of the Ar+ irradiation is studied by scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy, and the results show that an amorphous layer exists at the surface of the exfoliated film, which can be quickly removed by Ar+ irradiation. A two-stage etching mechanism by Ar+ irradiation is demonstrated, which not only establishes a new non-contact surface polishing method for the CIS-fabricated single crystalline thin films, but also is potentially useful to remove the residue damage layer produced during the CIS process.
Keywords: 128°Y-cut LiNbO3; Single crystalline thin films; Crystal ion slicing; BCB bonding; Ar+ irradiation

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Publ.-Id: 26339


Die Bestimmung des neutroneninduzierten Spaltquerschnitts von ²⁴²Pu

Kögler, T.
Präzise neutroneninduzierte Spaltquerschnitte von Actinoiden wie den Plutoniumisotopen haben für die Entwicklung zukünftiger Transmutationstechnologien eine große Bedeutung. Die Unsicherheiten des ²⁴²Pu-Spaltquerschnitts im schnellen Bereich des Spektrums betragen derzeit etwa 21 %. Aktuelle Sensitivitätsstudien haben gezeigt, dass nur eine Reduzierung dieser Unsicherheiten auf unter 5 % verlässliche neutronenphysikalische Simulationen zulässt.
Diese anspruchsvolle Aufgabe konnte im Rahmen der vorliegenden Arbeit an der Neutronen-Flugzeitanlage nELBE durchgeführt werden. Dünne, homogene und großflächige Actinoiden-Proben wurden dem Helmholtz-Zentrum Dresden - Rossendorf innerhalb des TRAKULA-Verbundprojektes zur Verfügung gestellt. Eingesetzt in eine neu entwickelte Spaltionisationskammer ermöglichten sie eine akkurate Bestimmung des Spaltquerschnitts relativ zu ²³⁵U. Die Flächendichten der Plutoniumschichten wurden anhand der spontanen Spaltrate von ²⁴²Pu bestimmt. Aufwändige Teilchentransportsimula-
tionen (durchgeführt mit Geant 4, MCNP 6 und FLUKA) wurden genutzt, um die auftretende Neutronenstreuung zu korrigieren. Die gewonnenen Ergebnisse sind im Rahmen ihrer Unsicherheiten in guter Übereinstimmung mit aktuellen Kerndatenevaluierungen. /
Neutron induced fission cross sections of actinides like the Pu-isotopes are of relevance for the development of nuclear transmutation technologies. For ²⁴²Pu, current uncertainties are of around 21 \%. Sensitivity studies show that the total
uncertainty has to be reduced to below 5\% to allow for reliable neutron physics simulations. This challenging task was performed at the neutron time-of-flight facility of the new German National Center for High Power Radiation Sources at HZDR, Dresden. Within the TRAKULA project, thin, large and homogeneous deposits of ²³⁵U and ²⁴²Pu have been produced successfully. Using two consecutively placed fission chambers allowed the determination of the neutron induced fission cross section of ²⁴²Pu relative to ²³⁵U. The areal density of the Plutonium targets was calculated using the measured spontaneous fission rate. Experimental results of the fast neutron induced fission of ²⁴²Pu acquired at nELBE will be presented and compared to recent experiments and evaluated data. Corrections addressing the neutron scattering are discussed by using
results of different neutron transport simulations (Geant4, MCNP6 and FLUKA).
Keywords: Kernspaltung, Wirkungsquerschnitt, schnelle Neutronen, nELBE, Spaltionisationskammern/ fission, cross section, fast neutrons, nELBE, fission ionization chambers
Related publications
Fast-neutron-induced fission cross section of Pu(242) … (Id 28970) HZDR-primary research data are used by this publication
  • Doctoral thesis
    TU Dresden, 2017
    Mentor: Dr. Arnd R. Junghans
    187 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-26338
Publ.-Id: 26338


Determination of the γ-Ray-Angular Distribution in the Inelastic Scattering of Fast Neutrons on ⁵⁶Fe at nELBE

Dietz, M.
The inelastic neutron scattering reaction on 56Fe was studied at the nELBE time-of-flight facility of HZDR. The incoming neutron energy ranges in the fast neutron spectrum from 100 keV to 10 MeV, where high precision nuclear data are needed. Regarding the recent CIELO evaluation on 56Fe, there is a great interest in improving the knowledge of inelastic scattering angular distribution and increasing the resolution on the few literature data of gamma-ray-angular distribution.
To investigate angular distributions of the emitted gamma-rays, a new detector setup has been installed. It contains five HPGe detectors and five LaBr3 scintillation detectors, which can be set under different angles. For this measurement they were positioned under 30°; 55°; 90°; 125° and 150°, relative to the beam axis. By cyclical measurement with and without the natural Fe-target the intrinsic and the neutron induced background from the setup, except the target, has been subtracted. Corrections for gamma-self-absorption inside the target and extended source effciency were achieved using GEANT4 simulations.
The gamma-ray-angular distribution data measured with the HPGe detectors are compared with data from D. L. Smith, Argonne, 1976. Due to the much better time resolution in LaBr3 detectors high resolution data have been obtained and very interesting resonant structures have been observed for the gamma-ray-angular distribution. In the end, the influence of angular distribution coeffcient a4 is demonstrated by a anisotropy correction factor for experiments, using only one detector under an angle of 125°.
Keywords: nELBE, inelastic neutron scattering, Fe-56, angular distribution
  • Master thesis
    TU Dresden, 2016
    Mentor: Arnd R. Junghans

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Permalink: https://www.hzdr.de/publications/Publ-26336
Publ.-Id: 26336


Untersuchungen zur katalytischen Aktivität von Au(III) Verbindungen

Patzschke, M.
In diesem Betrag stellen wir von uns durchgeführte Untersuchungen zur katalytischen Aktivität verschiedener Gold(III) Verbindungen vor.

We present our investigations on the catalytic activity of Au(III) complexes in organic synthesis.
Keywords: ab initio, DFT, computational chemistry, gold chemistry, catalysis
  • Lecture (others)
    Organisch-Chemisches Kolloquium, 12.12.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26335
Publ.-Id: 26335


Orca for computational actinide chemistry

Patzschke, M.
The program package Orca will be introduced and the use in computational actinide chemistry will be demonstrated.
Keywords: computational chemistry, ab initio, DFT, relativistic effects
  • Invited lecture (Conferences)
    ThUL School 2017, 16.-20.10.2017, Jülich, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26334
Publ.-Id: 26334


Computational Spectroscopy

Patzschke, M.
In the contribution we discuss the application of computational chemistry to calculate spectroscopical parameters. We first present the foundations of computational chemistry in a very short form. We will show problems and advantages of DFT. Then we will show how spectroscopical parameters (IR,UV-VIS,NMR) can be calculated and what accuracy can be expected.
Keywords: computational chemistry, DFT, ab initio, actinides, spin-orbit coupling, relativistic effects
  • Invited lecture (Conferences)
    ThUL School 2017, 16.-20.10.2017, Jülich, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26333
Publ.-Id: 26333


VVER-1000 RPV lower head model related to late in-vessel phenomena in case of hypothetical severe accident

Gencheva, R.; Grudev, P.; Stefanova, A.; Jobst, M.; Wilhelm, P.
This work discusses the progress in the development of an ASTEC computational model for investigation of molten corium pool behaviour in the lower head of a VVER-1000 reactor in case of a hypothetical accident with core degradation. The model was tested with variation of characterizing parameters which could have an influence on the molten pool behaviour and respectively the response behaviour of the reactor pressure vessel wall. An accident scenario with external cooling of the RPV wall was analysed. The preliminary code results give an estimation of the thermal load on the RPV wall. The sensitivity of the model depending on RPV wall nodalization was investigated. The analysis is performed in support to the numerical investigations realized within the frames of the EU HORIZON 2020 IVMR project (grant agreement number 662157).
Keywords: VVER-1000, severe accident, RPV, lower head, in-vessel
  • Contribution to proceedings
    27th Symposium of AER on VVER Reactor Physics and Reactor Safety, 17.-20.10.2017, München, Deutschland, 205-213
  • Lecture (Conference)
    27th Symposium of AER on VVER Reactor Physics and Reactor Safety, 17.-20.10.2017, München, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26332
Publ.-Id: 26332


Sorption competition and kinetics of trivalent cations (Eu, Y and Cm) on corundum (α-Al2O3): a batch sorption and TRLFS study

Virtanen, S.; Meriläinen, S.; Eibl, M.; Rabung, T.; Huittinen, N.
In this study we have combined batch sorption and laser spectroscopic investigations to study the sorption of Eu(III) and Cm(III), on the aluminum oxide corundum in single- and multi-metal systems. Experiments were performed using a constant equilibrium time as a function of pH (pH-edges) or at constant pH as a function of equilibrium time (kinetic experiments) in 0.01 M NaClO4 and carbonate free conditions. The objective was to investigate how the sorption behavior of trivalent actinides and lanthanides is affected by the presence of another trivalent metal, Y(III). Our hypothesis was that the addition of higher concentrations of trivalent Y(III) together with a chemically similar trivalent metal, would affect the sorption behavior of that metal. Batch experiments show that when the concentration of competing Y(III) is high enough (1×10-4 M) to occupy most of the surface sites, there is a clear shift in the position of the Eu(III) pH-edge to higher pH. Spectroscopic studies using time-resolved laser fluorescence spectroscopy (TRLFS) clearly confirm sorption competition between the trivalent metals Cm(III) and Y(III), but they also indicate a change in the surface speciation of the trivalent actinide in the presence of the competing metal if the concentration of that competing metal is high enough.
Keywords: Sorption competition, Eu(III), Cm(III), Y(III), TRLFS, corundum, α-Al2O3

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Permalink: https://www.hzdr.de/publications/Publ-26331
Publ.-Id: 26331


The influence of bentonite colloids on neptunium(V) migration in granitic rock

Elo, O.; Hölttä, P.; Huittinen, N.
In Finland, the repository for spent nuclear fuel (SNF) will be excavated at a depth of about 500 meters in the fractured crystalline bedrock in Olkiluoto at Eurajoki implemented by Posiva Oy. The engineered barrier systems (EBS), consisting of a solid fuel capsule, a copper-iron canister and the bentonite buffer should prevent the migration of radionuclides to the biosphere. Montmorillonite, the main mineral of bentonite, is like other aluminosilicates known to retain radionuclides, thus, preventing them from migrating from the repository with the groundwater. Bentonite erosion resulting in the formation of colloids may have a direct impact on the overall performance of the bentonite buffer. The potential relevance of colloids for radionuclide transport is highly dependent on the formation of colloids, the stability and mobility of colloids in different chemical environments, and their interaction with radionuclides [1]. Stable and mobile bentonite colloids can be formed when the glacial meltwater dilutes the groundwater. In these mildly oxic conditions, neptunium(V) will be present in its pentavalent oxidation state as the neptunyl cation (NpO2+), which is rather soluble, highly mobile and poorly adsorbed. Due to the long half-life of Np-237 (2.144·106 y), it will be a major dose contributor after 100,000 years in the SNF repository.
In our previous study, the interaction of Np(V) with Na-montmorillonite purified from MX-80 bentonite and corundum was investigated [2]. Corundum was used as a reference mineral in order to study the aluminol surface sites present on clay minerals, which are regarded as the main adsorption sites for radionuclide attachment [3]. This study aimed at investigating two processes: retardation of Np(V) on the bentonite colloids and granitic rock and the effect of the stable and mobile bentonite colloids on the migration of Np(V) in intact and crushed granitic rock columns.
The materials used in this study were colloids prepared from MX-80 Volclay type bentonite (76% montmorillonite) and Kuru Grey granite. Np(V) sorption on these materials under stagnant conditions was studied as a function of pH, solid concentration, time, and Np(V) concentration. The sorption experiments as a function of pH (3-11), were performed at a constant Np(V) concentration of 10-6 M. The sorption isotherms as a function of Np(V) concentration were conducted at concentration from 10-9 to 5·10-6 M at pH 8, 9, and 10. Solid concentrations were 0.08 g/L and 0.8 g/L for colloids and 40 g/L for granite. The samples were prepared by adding a small aliquot of colloid stock solution or crushed granite, Np-237 tracer and the background electrolyte in 20 ml polypropylene vials. The solution was buffered to the desired pH and after one week equilibration time the solid phase was separated from the liquid by centrifugation and 1 ml aliquots were taken immediately for liquid scintillation counting (Perkin Elmer Tri-Carb 3100 TR or Quantulus liquid scintillation counter). All the batch sorption studies were conducted in 10 mM NaClO4 either in carbonate-free N2-atmosphere (bentonite colloids, 0.08 g/L) or under ambient air conditions (granite and bentonite colloids 0.8 g/L).
The effect of bentonite colloids on Np(V) migration was studied in column experiments, where the column material was either crushed granite (grain size 0.01-0.1 mm) or an intact drill core of the Kuru Grey granite. The crushed granite column diameter was 1.5 cm and the length 15 cm. Drill core columns were constructed from Kuru grey granite cores which were placed inside a tube to form a flow channel (L = 28 cm, w = 4.4 cm) representing an artificial fracture formed by the 0.5 mm gap between the core and the tube [3]. In the experiments, colloid solution was injected into the water flow and the colloid breakthrough was detected by photon correlation spectroscopy (PCS) measurements. The column experiments were performed under ambient air conditions in 10 mM NaClO4 solution using flowrates of 1.5 mL/h, 0.8 mL/h, and 0.3 mL/h. The Np-tracer was injected into the flow, through an injection loop of known volume. The flow conditions in the columns were determined using chloride (36Cl-) as a conservative tracer. The effect of bentonite colloids on Np(V) transport at pH 8 and pH 10 was determined in the absence and presence of colloids (0.7 and 0.9 g/L). The colloid concentration in the collected fractions was determined by PCS and the Np(V) concentration was determined after PCS measurements from the same samples by liquid scintillation counting.
Np(V) adsorption onto MX-80 bentonite colloids and crushed Kuru Grey granite in 10 mM NaClO4 is shown as a function of pH in Figure 1a and as a function of Np concentration in Figure 1b. Sorption onto colloids was rather weak (20%) at pH 8 and higher adsorption occurred only above pH 10. According to the pH-edge results, the sorption isotherms for bentonite colloids are as expected, linear and the slopes are close to one another. The weak sorption of Np(V) on the colloids indicates that Np(V) will be mobilized as a neptunyl cation in solution. Despite the low uptake of Np(V) by the bentonite colloids, the obtained column results show that Np(V) breakthrough from the granite columns is enhanced in the presence of colloids (Figure 2).
  • Poster
    16th International Conference on Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere, 10.-15.09.2017, Barcelona, Spain

Permalink: https://www.hzdr.de/publications/Publ-26330
Publ.-Id: 26330


Complexation of trivalent actinides and lanthanides with aqueous phosphates at elevated temperatures (25-80°C)

Huittinen, N.; Jordan, N.; Lösch, H.
The incorporation of actinides in solid lanthanide phosphates crystallizing in the monazite structure has been intensely investigated in the past decades due to the relevance of these monazites as potential ceramic phases for the immobilization of specific high level radioactive waste (HLW) streams [1-3]. In recent years, understanding the incorporation behaviour of trivalent dopants in the LnPO4×nH2O rhabdophane structure, which is the hydrated phosphate precursor in the synthesis of monazites through precipitation routes and a potential secondary mineral controlling actinide solubility in dissolution and re-precipitation reactions of monazite host-phases, has been given more attention [4,5]. Despite the large interest in lanthanide phosphates and the interaction of actinides with these solids, very little data is available on the complexation of lanthanides and actinides with aqueous phosphates, even though these complexation reactions precede any aqueous synthesis of monazite ceramics and are expected to occur in natural waters as well as in the proximity of monazite-containing HLW repositories. It also suffers from an almost systematic absence of independent spectroscopic validation of the stoichiometry of the proposed complexes. Both from the perspective of aqueous rhabdophane synthesis, which is often carried out at elevated temperatures, and heat-generating HLW immobilization in monazites, the lanthanide and actinide complexation reactions with aqueous phosphates under ambient conditions should be complemented with data obtained at higher temperatures.

In the present work, time-resolved laser fluorescence spectroscopy (TRLFS) has been employed to study the phosphate complexation of Eu3+ (5×10-6 M) and Cm3+ (5×10-7 M) as a function of total phosphate concentration (0-1 M ΣPO4) in the temperature regime 25-80°C, using NaClO4 as a background electrolyte. These studies have, in a first step, been conducted in the acidic pH-range (pH = 1) to avoid precipitation of solid Eu or Cm rhabdophane. Both trivalent metal cations form a complex with the anionic H2PO4- species, i.e. EuH2PO42+ and CmH2PO42+. As expected, the complexation reaction occurs at lower total phosphate concentration when increasing the temperature. In addition, our preliminary results show the presence of a second Eu-phosphate species which is tentatively assigned to Eu(H2PO4)2+. The presence of this species will be verified with mass-spectrometric methods.
Temperature-dependent complexation constants for the identified species will be derived from the recorded luminescence emission spectra. These will be recalculated to standard conditions with the van´t Hoff equation and the Specific Ion Interaction Theory. For this, the required ion interaction coefficients have been preliminary determined at 25 °C by varying the ionic strength (0.6 to 3 M).
  • Poster
    16th International Conference on Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere, 10.-15.09.2017, Barcelona, Spain

Permalink: https://www.hzdr.de/publications/Publ-26329
Publ.-Id: 26329


Charaterization of actinide(IV) complexes with imine type ligands

Radoske, T.
The progress on the PhD thesis is presented in an oral talk. The results include complexes of tetradentate and hexadentate salen complexes with several actinides in tetravalent state.
Keywords: actinide, salen, complex, thorium, uranium, SC-XRD
  • Lecture (others)
    FENABIUM Projekttreffen, 10.05.2017, Leipzig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26328
Publ.-Id: 26328


European standard on small punch testing of metallic materials

Bruchhausen, M.; Holmström, S.; Altstadt, E.; Dymacek, P.; Jeffs, S.; Lancaster, R.; Lacalle, R.; Matocha, K.; Petzova, J.
Life extension of aging nuclear power plant components requires knowledge of the properties of the service-exposed materials. For instance, in long term service the tensile and creep properties might decline and the ductile-to-brittle transition temperature (DBTT) might shift towards higher temperatures. Monitoring of structural components in nuclear power plants receives much attention – in particular in the context of lifetime extension of current plants, where the amount of material available for destructive testing is limited. Much effort has therefore been invested in the development of miniature testing techniques that allow characterizing structural materials with small amounts of material. The small punch (SP) test is one of the most widely used of these techniques. It has been developed for nuclear applications but its use is spreading to other industries.
Keywords: small punch test; tensile properties; fracture; creep; standardization
  • Contribution to proceedings
    ASME 2017 Pressure Vessels and Piping Conference PVP2017, 16.-20.07.2017, Hawaii, USA
    Proceedings of the ASME 2017 Pressure Vessels and Piping Conference PVP2017
    DOI: 10.1115/PVP2017-65396

Permalink: https://www.hzdr.de/publications/Publ-26327
Publ.-Id: 26327


Selective THz control of magnetic order: new opportunities from superradiant undulator sources

Kovalev, S.; Wang, Z.; Deinert, J.; Awari, N.; Chen, M.; Green, B.; Germanskiy, S.; de Oliveira, T. V. A. G.; Lee, J. S.; Deac, A.; Turchinovich, D.; Stojanovic, N.; Eisebitt, S.; Radu, I.; Bonetti, S.; Kampfrath, T.; Gensch, M.
Recent advancements of accelerator technology enable the generation of carrier-envelope-phase stable THz pulses with high-fields at adjustably high repetition rates. The appropriate choice of THz radiator allows generating narrow-band, spectrally dense, multicycle THz transients of tunable THz frequency which are ideally suited to selectively excite low-energy excitations such as magnons or phonons. They also allow one to study the frequency dependence of nonresonant THz-field interactions with various order parameters with high dynamic range. In this paper we discuss the future prospects of this new type of THz light sources for studying the coherent control of magnetic order based on recent results.
Keywords: Terahertz, THz control, magnetic order

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Permalink: https://www.hzdr.de/publications/Publ-26326
Publ.-Id: 26326


Structure Analysis of Pipe Section Reactor for Pipe-Wall Reaction: A Computational Fluid Dynamics Analysis Approach

Hua, P.; Ma, S.; Ding, W.; Zhang, J.
Pipe section reactor (PSR) is a well-controlled laboratory reactor, which is used to simulate the water quality variations in drinking water distribution systems. However, the hydraulics condition within PSR, which is an essential prerequisite of the water quality studies, still remains unclear. Consequently, the objective of this study is to analyze the hydraulic conditions within PSR by means of a computational fluid dynamics (CFD) approach. The influences of configuration parameters on the hydraulic conditions were tested including propeller diameter, inclined angle of the propeller, distance between the top and inner cylinder, distance between the bottom and inner cylinder, outer cylinder length, baffle length, number of the baffles, rotational speed of the propeller, and inner and outer cylinder diameters. According to the CFD analysis, an optimal structure of PSR was suggested. The data presented here could facilitate the PSR application and improve the simulation of water quality in distribution systems
Keywords: Chlorine decay; Computational fluid dynamics; Pipe section reactor; Structure optimization

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Permalink: https://www.hzdr.de/publications/Publ-26325
Publ.-Id: 26325


Dynamics of a solid particle attachment to a gas bubble in a liquid

Baba, K.; Kotani, Y.; Lecrivain, G.; Yamamoto, R.; Taniguchi, T.
An extended smooth profile method which can deal with particle-dynamics dispersed in a binary fluid is presented. The smooth profile method, originally developed for the simulation of particle transport in a homogeneous fluid, has been successfully combined with a binary fluid model based on Ginzburg-Landau free energy functional. In this approach, the three types of interfaces among particles and two fluids are treated as diffuse interfaces. By using the method, we simulated the attachment and detachment dynamics of a colloidal particle to the surface of a position fixed bubble in a Newtonian fluid under various capillary numbers. It is found that the method can reproduce the three micro-processes associated with the particle attachment ((i) particle approach, (ii) collision, (iii) sliding down on the bubble surface) (Gregory et al, 2016). The present method will make it possible to simulate a froth flotation process, where the capture of hydrophobic particles by rising bubbles is of primary importance.
Keywords: Flotation; Direct Numerical Simulation; Smoothed Profile Method; Immersed Boundary Method
  • Contribution to proceedings
    49th Autumn Meeting of the Society of Chemical Engineers Japan, 20.-22.09.2017, Nagoya University, Japan
    Proceedings of the 49th Autumn Meeting of the Society of Chemical Engineers Japan

Permalink: https://www.hzdr.de/publications/Publ-26324
Publ.-Id: 26324


On the Role of the Electrical Field in Spark Plasma Sintering of UO2+x

Tyrpekl, V.; Najii, M.; Holzhäuser, M.; Freis, D.; Prieur, D.; Martin, P.; Cremer, B.; Murray-Farthing, M.; Cologna, M.
The electric field has a large effect on the stoichiometry and grain growth of UO2+x during Spark Plasma Sintering. UO2+x is gradually reduced to UO2.00 as a function of sintering temperature and time. A gradient in the oxidation state within the pellets is observed in intermediate conditions. The shape of the gradient depends unequivocally on the direction of the electrical field. The positive surface of the pellet shows a higher oxidation state compared to the negative one. An area with larger grain size is found close to the positive electrode, but not in contact with it. We interpret these findings with the redistribution of defects under an electric field, which affect the stoichiometry of UO2+x and thus the cation diffusivity. The results bear implications for understanding the electric field assisted sintering of UO2 and non-stoichiometric oxides in general.
Keywords: UO2, SPS, XANES

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Permalink: https://www.hzdr.de/publications/Publ-26323
Publ.-Id: 26323


Serpent-DYN3D solution of the X2 benchmark: fresh core at HZP

Bilodid, Y.; Fridman, E.
In this work, the hot zero power experiments conducted during the startup of the fresh core of Khmelnitsky-2 NPP are modelled with the Serpent and DYN3D codes.
  • Lecture (Conference)
    7th International Serpent User Group Meeting, 06.-09.11.2017, Gainesville, FL, USA

Permalink: https://www.hzdr.de/publications/Publ-26322
Publ.-Id: 26322


Nuclear data uncertainty quantification for the FREYA fast critical experiments

Fridman, E.; Aufiero, M.
This study summarizes some initial results of nuclear data uncertainty quantification for the FREYA fast critical experiments
  • Lecture (Conference)
    7th International Serpent User Group Meeting, 06.-09.11.2017, Gainesville, FL, USA

Permalink: https://www.hzdr.de/publications/Publ-26321
Publ.-Id: 26321


Modeling of Phenix EOL experiments with Serpent-DYN3D

Nikitin, E.; Fridman, E.
This study presents the Serpent-DYN3D solution of the Phenix EOL benchmark
Keywords: Serpent, DYN3D, SFR, Phenix
  • Lecture (Conference)
    7th International Serpent User Group Meeting, 06.-09.11.2017, Gainesville, FL, USA

Permalink: https://www.hzdr.de/publications/Publ-26320
Publ.-Id: 26320


Software Concept for Automated Synthesis and Analysis of Resource-Technological Image Data in Scientific Large-Scale Infrastructures

Oertel, W.; Kaever, P.; König, S.; Pour, R.; Renno, A. D.; Rugel, G.; Ziegenrücker, R.ORC; Zierer, R.
The document describes the concept of a software system that synthesises and analyses image data from multidimensional measurement data generated in scientific large-scale infrastructures. The aim is to reach a new level of efficiency, competency, and flexibility by combining highly efficient algorithms with domain-specific knowledge and changeable control structures. Applications are established to investigate samples or mass flows of rock, ore, material, or waste in ion beam analytics respectively recycling facilities.
  • Poster
    Workshop 3D-NordOst 2017 20. Anwendungsbezogener Workshop zur Erfassung, Modellierung, Verarbeitung und Auswertung von 3D-Daten, 07.-08.12.2017, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26319
Publ.-Id: 26319


Geostatistics with compositional data, an overview

Tolosana-Delgado, R.; Mueller, U.; van den Boogaart, K. G.; Pawlowsky-Glahn, V.; Egozcue, J. J.
This paper presents an overview of results for the geostatistical analysis of collocated multivariable data sets, in which the variables form a composition, i.e. where the components inform of the relative important of the parts forming a whole. Such data sets occur most often in mining, hydrogeochemistry and soil science, but the results gathered here are relevant for any regionalised compositional data set. The paper covers the basic definitions, the analysis of the spatial codependence between components, mapping methods of cokriging and cosimulation honoring the compositional constraints, the role of pre- and post-transformations like logratios or multivariate normal score transforms, and block-support upscaling. Proofs of all statements are included in an appendix.

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Permalink: https://www.hzdr.de/publications/Publ-26318
Publ.-Id: 26318


Evaluation of gamma-ray strength functions

Schwengner, R.
Gamma-ray strength functions deduced from nuclear resonance fluorescence (NRF) and from light-ion induced reactions are compared.
Model assumptions in the analysis and differences in the reaction mechanisms and their influence on the results are considered.
New results from NRF experiments at ELBE and from calculations within the shell model are presented.
Keywords: Nuclear resonance fluorescence, light-ion induced reactions, absorption cross sections, dipole strength functions.
  • Invited lecture (Conferences)
    2nd Research Coordination Meeting of the Coordinated Research Project on Updating the Photonuclear Data Library and generating a Reference Database for Photon Strength Functions, 16.-20.10.2017, Wien, Österreich

Permalink: https://www.hzdr.de/publications/Publ-26317
Publ.-Id: 26317


Development of novel benzomidazotriazine derivatives for PET imaging of phosphodiesterase 2A (PDE2A)

Ritawidya, R.; Scheunemann, M.; Brust, P.
Ziel: Cyclic nucleotide phoshodiesterases (PDEs) are enzymes that hydrolyze cyclic AMP and cyclic GMP. These ubiquitous second messengers are involved in important cellular processes, such as proliferation, differentiation, migration, survival, and apoptosis. Accordingly PDEs are regarded as therapeutic targets to alter these processes. The expression of PDE2A was found to be related to a variety of tumors (1). Our aim was to synthesis novel PDE2A inhibitors based on the benzoimidazotriazine (BIT) moiety that might be prospective as a lead compound for the development of an F-18 labeled ligand for PDE2A imaging with PET.

Methodik: Three BIT derivatives (BIT1, BIT2, BIT3) were prepared (in 7-10 steps) by introducing different moieties to the C-1 and C-8 position of a BIT intermediate, using two-step Suzuki coupling and bromination. The derivatives were characterized by NMR, MS, and HPLC. Thereafter, the inhibitory potential of the three new compounds towards PDE2A and other PDE subtypes was estimated. Thereafter other derivatives were synthesized using a similar strategy. For radiolabeling, the nitro precursor of BIT1 was prepared employing a four-step synthesis, starting from Miyaura-Borylation instead of Suzuki coupling reaction.

Ergebnisse: BIT derivatives were successfully prepared in 6-8 % overall yield. The affinity and selectivity of BIT1 (82.9 % inhibition of PDE2A3 at 10 nM) was much higher than that of BIT2 and BIT3 (8.52 % and 13.2 % inhibition, respectively). Furthermore, BIT1 provided a promising IC50 of 3.33 nM. The precursor nitro-BIT1 was successfully obtained and is expected to be suitable for one-step radiofluorination via aromatic nucleophilic substitution.

Schlussfolgerungen: It is suggested that BIT1 if radiolabeled with the PET radionuclide F-18 using nitro-BIT1 precursor via aromatic nucleophilic substitution could be a promising PDE2A imaging agent.

Literatur:
(1) S. Schröder et al. Molecules 2016, 21, 650.
  • Poster
    56. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 18.-21.04.2018, Bremen, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26316
Publ.-Id: 26316


P1504 - Pockelszellen-Treiberschaltung mit ohmschen, induktiven oder kapazitiven Elementen

Bergmann, T.; Bergmann, F.; Siebold, M.; Löser, M.
Die Treiberschaltung umfasst einen ersten Knoten (J1), welcher mit einem ersten Anschluß der Pockelszelle (CP) verbindbar ist, einem zweiten Knoten (J2), welcher mit einem zweiten Anschluß der Pockelszelle (CP) verbindbar ist, wobei der erste Knoten (J1) über eine erste Schalteinheit (S1) mit einem ersten Potential (+HV) verbindbar ist und der zweite Knoten (J2) über eine zweite Schalteinheit (S2) mit dem ersten Potential (+HV) verbindbar ist, und wobei der erste Knoten (J1) über einen ersten Widerstand (R1) mit einem zweiten Potential (-HV) verbindbar ist und der zweite Knoten (J2) über einen zweiten Widerstand (R2) mit dem zweiten Potential (-HV) verbindbar ist, und wobei der erste Knoten (J1) mit dem zweiten Knoten (J2) über eine Serienschaltung aus einem dritten Widerstand (R3) und einer Induktivität (L1) verbunden ist.
  • Patent
    EP3128673 - Offenlegung: 08.02.2017, Nachanmeldungen: US

Permalink: https://www.hzdr.de/publications/Publ-26315
Publ.-Id: 26315


Advanced inertial position tracking of sensor particles in fluid flows of large industrial containers

Arefin, S.; Reinecke, S.; Hampel, U.
In this paper, a concept for inertial position tracking of flow following sensor particles based on data fusion of inertial sensors is presented. The employed data fusion technique is quaternion based and uses an extended Kalman filter algorithm. A generalized sensor system kinematics has been developed to test the filter algorithm where three data conditions have been considered. Eventually, first simulation results are compared which shows the performance of the filter regarding sensor drift and noise are being discussed.
Keywords: data fusion, Kalman filter, position tracking, sensor particle, flow follower
  • Open Access Logo Contribution to proceedings
    13. Dresdner Sensor-Symposium 2017, 04.-06.12.2017, Dresden, Deutschland
    13. Dresdner Sensor-Symposium 2017, Wunstorf: AMA Service GmbH, 978-3-9816876-5-1, 213-218
    DOI: 10.5162/13dss2017/P2.08
  • Poster
    13. Dresdner Sensor-Symposium, 04.-06.12.2017, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26312
Publ.-Id: 26312


Noncentrosymmetric Superconductor BeAu

Amon, A.; Svanidze, E.; Cardoso, R.; Wilson, M. N.; Rosner, H.; Bobnar, M.; Schnelle, W.; Lynn, J. W.; Gumeniuk, R.; Hennig, C.; Luke, G. M.; Borrmann, H.; Leithe-Jasper, A.; Grin, Y.
Noncentrosymmetric superconductors have attracted tremendous research interest due to the possibility of mixed spin-singlet and spin-triplet pairing in these materials. In this work, physical properties of a noncentrosymmetric superconductor BeAu were investigated. It was established that BeAu undergoes a structural phase transition from a room-temperature noncentrosymmetric FeSi structure type to a high-temperature CsCl structure type at Ts = 860 K. The room-temperature modification exhibits a superconducting transition below Tc = 3.3 K. The values of lower (Hc1 = 32 Oe) and upper (Hc2 = 335 Oe) critical fields are rather small, confirming that this Type II (κG−L=2.3) weakly coupled (λe−p= 0. ∆ Ce/γnTc≈1.26) superconductor can be well understood within the Bardeen-Cooper-Schrieffer theory. The muon spin relaxation analysis indicates that the time-reversal symmetry is preserved when the superconducting state is entered, supporting conventionalsuperconductivity in BeAu. From the density functional calculations, a considerable contribution of the Be electrons to the superconducting state was established. Moreover, on average, a rather small mass renormalization was found, consistent with the experimental data.

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Permalink: https://www.hzdr.de/publications/Publ-26311
Publ.-Id: 26311


FFLO States in Layered Organic Superconductors

Wosnitza, J.
In this short review, the recently found experimental evidence that Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) states are realized in quasi-two-dimensional (2D) organic superconductors is reported. At low temperatures and when a high magnetic field is aligned parallel to the conducting organic layers, an upturn of the upper critical field much beyond the Pauli limit is observed, as proven by thermodynamic measurements. Under certain conditions, a second thermodynamic transition emerges inside the FFLO state. Nuclear magnetic resonance (NMR) work has added strong microscopic support for the realization of the FFLO state. The NMR spectra in the FFLO phase can very well be explained by a nonuniform one-dimensionally modulated superconducting order parameter. All These features, appearing only in a very narrow angular region close to parallel-field orientation, give robust evidence for the realization of the FFLO state in organic superconductors.

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Permalink: https://www.hzdr.de/publications/Publ-26310
Publ.-Id: 26310


„Simulation based Life Cycle Assessment of Circular Economy Systems”

Reuter, M. A.
The ISO 14000 norm provides a framework in which a continuous improvement of the environmental performance of a process may be realised. Life Cycle Assessment (LCA) forms an integral part of ISO 14000, however, ist inventory analysis presently often simplifies process routes for metals processing to simple averaging black-boxes that represent whole process. This approach hardly makes it possible to capture the detail of complex interconnected material processing systems as found in metals processing.

• HSC Chemistry platform may be used to create process flowsheet models and link them to Life Cycle Assessment (LCA) tools.
• Environmental footprints - which are based on the physical process models – will meet element and energy balances.
• Process models make it possible to optimize process yields and profits, and the connection to LCA will also optimize environmental footprints.
• Outotec Silver refining process is used to demonstrate this procedure.
• Exergy analysis of a power plant will show the thermodynamic basis.
  • Invited lecture (Conferences)
    European Congress and Exhibition on Advanced Materials and Processes - EUROMAT 2017, 17.-22.09.2017, Thessaloniki, Griechenland

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Permalink: https://www.hzdr.de/publications/Publ-26309
Publ.-Id: 26309


Fairphone

Reuter, M. A.; Ballester, M.; van Schaik, A.
Fairphone is a social enterprise since 2013 using the power of business to tackle step by step the social and environmental challenges of the electronics industry.
By manufacturing our own products we are able to work with partners to increase the increase the sustainability in the supply chain at the same time that we grow the demand for such products in the market. Fairphone.
Keywords: Fairphone
  • Invited lecture (Conferences)
    Circular-CRM IdeaCamp on Innovation & Research in the E-waste Recycling Chain: Improving Circular Economy of Critical Raw Materials (CRMs) / IdeaCamp and Workshop, 13.-14.09.2017, Aachen, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-26308
Publ.-Id: 26308


Pt and Au bimetallic and monometallic nanostructured amperometric sensors for direct detection of hydrogen peroxide: Influences of bimetallic effect and silica support

Liu, W.; Hiekel, K.; Hübner, R.; Sun, H.; Ferancova, A.; Sillanpää, M.
The non-enzyme direct electrochemical sensing of hydrogen peroxide (H2O2) by nanostructured electrodes of Pt- and Au-containing bimetallic or monometallic nanocatalysts including paramecium-like nanostructures of PtAu supported on silica nanorods, Pt and Au nanoparticles supported on silica nanorods, and the non-supported Pt and Au nanoparticles (NPs) is reported. The nanocatalysts modified electrodes were fabricated by simple self-assembling on 3-aminopropyl-trimethoxysilane (APTMS) modified glassy carbon. The cyclic voltammetric and amperometric results showed that PtAu supported on silica nanorods has superior performance over the corresponding monometallic counterparts, with a broad linear range from 5.0 µM to 72000 µM for H2O2, a detection limit of 2.6 µM, a sensitivity of 46.7 µA mM-1cm-2 at a lower working potential of -0.20 V vs SCE, and has good stability and reproducibility. In addition, a systematic test showed that the non-supported Pt NPs sensor has a surprisingly high performance, even better than the paramecium-like nanostructure of PtAu supported on silica nanorods, where the existence of silica nanorod templates in the nanocatalysts retards the electrocatalytic reduction/oxidation of H2O2. Among the nanocatalysts tested in this work, the Pt NPs sensor showed fastest response within 3 s, a broad linear response from 5 µM to 58000 µM, a detection limit of 4.2 µM, and the highest sensitivity of 110.3 µA mM-1cm-2 at the lowest working potential of -0.08 V vs SCE. Notably, the performance of the Pt NPs sensor is also among the best Pt-containing monometallic or bimetallic nanostructured electrochemical sensors toward H2O2 reported so far. This work shows a simple method to fabricate H2O2 electrochemical sensors of high performance and indicates the importance of considering not only bimetallic effects but also the influences of the nanostructure of nanocatalysts on the electrocatalytic performance and electrochemical sensing property.
Keywords: Platinum, Bimetallic effect, Support material, Electrocatalyst, Amperometric sensor, Hydrogen peroxide
  • Sensors and Actuators B 255(2018), 1325-1334

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Permalink: https://www.hzdr.de/publications/Publ-26307
Publ.-Id: 26307


Fast neutron measurements at the nELBE time-of-flight facility

Junghans, A. R.; Beyer, R.; Grosse, E.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Schwengner, R.; Wagner, A.
The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV.
nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.
Keywords: nELBE, neutron time of flight, transmission, total cross section, inelastic scattering, fission

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Permalink: https://www.hzdr.de/publications/Publ-26306
Publ.-Id: 26306


Generation of high-avidity, WT1-reactive CD8+ cytotoxic T cell clones with anti-leukemic activity by streptamer technology

Tunger, A.; Wehner, R.; von Bonin, M.; Kühn, D.; Heidenreich, F.; Matko, S.; Nauerth, M.; Rücker-Braun, E.; Dietz, S.; Link, C. S.; Eugster, A.; Odendahl, M.; Busch, D. H.; Tonn, T.; Bonifacio, E.; Germeroth, L.; Schetelig, J.; Bachmann, M. P.; Bornhäuser, M.; Schmitz, M.
Summary: In summary, we demonstrated that the expansion of WT1 peptide-specific CD8+ T cells by peptide-loaded MoDCs followed by streptamer-based selection represents an attractive strategy to significantly enrich such T cells prior to cloning. By using this technology, we generated high-avidity, WT1 peptide-reactive CD8+T cell clones with anti-leukemic activity. This strategy may be particular useful for the generation of CD8+T cell clones from healthy donors, in which blood circulating T cells recognizing tumor-associated antigens are rare or not detectable.
Keywords: WT1, CD8+ cytotoxic T cell clones, streptamer technology

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Permalink: https://www.hzdr.de/publications/Publ-26305
Publ.-Id: 26305


On the estimation of ultimate tensile stress from small punch testing

Altstadt, E.; Houska, M.; Simonovski, I.; Bruchhausen, M.; Holmström, S.; Lacalle, R.
Finite element simulations of the small punch test are performed in order to critically evaluate and improve empirical correlations for the estimation of the ultimate tensile stress from force-deflection and force-displacement curves. For this purpose, generic elastic-plastic material properties are used. A systematic variation of the ultimate tensile stress and total uniform elongation is performed to investigate the effects of these parameters of the uniaxial stress-strain curve on the characteristics of small punch test curves. It is shown, that the maximum force Fm of the small punch test curve is not the appropriate parameter for the estimation of the ultimate tensile stress. Instead, the force Fi at a punch displacement of 1.29 times the specimen thickness (or alternatively at bottom deflection of 1.1 times the specimen thickness) should be used. This force is associated with the onset of plastic instability. A correlation between the force Fi and the ultimate tensile strength is proposed and validated by more than 100 small punch tests of nine different steel heats.
Keywords: small punch test; finite-element analysis; plasticity; hardening; ultimate tensile stress

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Permalink: https://www.hzdr.de/publications/Publ-26303
Publ.-Id: 26303


Exploratory investigation of PSCA-protein expression in primary breast cancer patients reveals a link to HER2/neu overexpression.

Link, T.; Kuithan, F.; Ehninger, A.; Kuhlmann, J. D.; Kramer, M.; Werner, A.; Gatzweiler, A.; Richter, B.; Ehninger, G.; Baretton, G.; Bachmann, M.; Wimberger, P.; Friedrich, K.
Background: Prostate stem cell antigen (PSCA) has been suggested as biomarker and therapeutic target for prostate cancer. Recent advances showed that PSCA is upregulated in other cancer entities, such as bladder or pancreatic cancer. However, the clinical relevance of PSCA-expression in breast cancer patients has not yet been established and is therefore addressed by the current study.
Methods: PSCA-protein expression was assessed in 405 breast cancer patients, using immunohistochemistry (PSCA antibody MB1) and tissue microarrays.
Results: PSCA-expression was detected in 94/405 patients (23%) and correlated with unfavorable histopathological grade (p=0.011) and increased Ki67 proliferation index (p=0.006). We observed a strong positive correlation between PSCA-protein expression and HER2/neu receptor status (p<0.001). PSCA did not provide prognostic information in the analyzed cohort. Interestingly, the distribution of PSCA-expression among triple negative patients was comparable to the total population.
Conclusion: We identified a subgroup of PSCA-positive breast cancer patients, which could be amenable for a PSCA-targeted therapy. Moreover, given that we found a strong positive correlation between PSCA- and HER/neu expression, targeting PSCA may provide an alternative therapeutic option in case of trastuzumab resistance.
Keywords: breast cancer, PSCA, HER2/neu, therapeutic target

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Permalink: https://www.hzdr.de/publications/Publ-26302
Publ.-Id: 26302


Local formation of InAs nanocrystals in Si by masked ion implantation and flash lamp annealing

Rebohle, L.; Wutzler, R.; Prucnal, S.; Hübner, R.; Georgiev, Y. M.; Erbe, A.; Böttger, R.; Glaser, M.; Lugstein, A.; Helm, M.; Skorupa, W.
The integration of high-mobility III-V compound semiconductors emerges as a promising route for Si device technologies to overcome the limits of further down-scaling. In this work, we investigate the possibilities to form InAs nanocrystals in a thin Si layer at laterally defined positions with the help of masked ion beam implantation and flash lamp annealing. In detail, a cladding layer was deposited on a silicon-on-insulator (SOI) wafer and patterned by electron beam lithography in order to serve as an implantation mask. The wafer was subsequently implanted with As and In, followed by flash lamp annealing leading to the formation of InAs nanoparticles in the implanted areas. The structures were investigated by Raman spectroscopy, scanning and transmission electron microscopy as well as energy-dispersive X-ray spectroscopy. Depending on the size of the implantation window, several, one or no nanoparticle is formed. Finally, the perspectives for using this technique for the local modification of Si nanowires are discussed.
Keywords: ion implantation, flash lamp annealing, III-V integration into silicon, nanocrystal, InAs, liquid phase epitaxy

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Permalink: https://www.hzdr.de/publications/Publ-26301
Publ.-Id: 26301


Deposition and properties of Fe(Se,Te) thin films on vicinal CaF2 substrates

Bryja, H.; Hühne, R.; Iida, K.; Molatta, S.; Sala, A.; Putti, M.; Schultz, L.; Nielsch, K.; Hänisch, J.
We report on the growth of epitaxial Fe1+δSe0.5Te0.5 thin films on 0°, 5°, 10°, 15° and 20° vicinal cut CaF2 single crystals by pulsed laser deposition. In situ electron and ex situ x-ray diffraction studies reveal a tilted growth of the Fe1+δSe0.5Te0.5 films, whereby under optimized deposition conditions the c-axis alignment coincides with the substrate [001] tilted axis up to a vicinal angle of 10°. Atomic force microscopy shows a flat island growth for all films. From resistivity measurements in longitudinal and transversal directions, the ab- and c-axis components of resistivity are derived and the mass anisotropy parameter is determined. Analysis of the critical current density indicates that no effective c-axis correlated defects are generated by vicinal growth, and pinning by normal point core defects dominates. However, for H||ab the effective pinning centers change from surface defects to point core defects near the superconducting transition due to the vicinal cut. Furthermore, we show in angular-dependent critical current density data a shift of the ab-planes maxima position with the magnetic field strength.

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Permalink: https://www.hzdr.de/publications/Publ-26300
Publ.-Id: 26300


Acoustic Properties of Crystals with Jahn–Teller Impurities: Elastic Moduli and Relaxation Time. Application to SrF2:Cr2+

Averkiev, N. S.; Bersuker, I. B.; Gudkov, V. V.; Zhevstovskikh, I. V.; Sarychev, M. N.; Zherlitsyn, S.; Yasin, S.; Shakurov, G. S.; Ulanov, V. A.; Surikov, V. T.
A new approach to evaluate the relaxation contribution to the total elastic moduli for crystals with Jahn–Teller (JT) impurities is worked out and applied to the analysis of the experimentally measured ultrasound velocity and attenuation in SrF2:Cr2+. Distinguished from previous work, the background adiabatic contribution to the moduli, important for revealing the impurity relaxation contribution, is taken into account. The temperature dependence of the relaxation time for transitions between the equivalent configurations of the JT centers has been obtained, and the activation energy for the latter in SrF2:Cr2+. as well as the linear vibronic coupling constant have been evaluated.

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Permalink: https://www.hzdr.de/publications/Publ-26299
Publ.-Id: 26299


Mass spectrometry-based identification of a naturally presented receptor tyrosine kinase-like orphan receptor 1-derived epitope recognized by CD8+ cytotoxic T cells

Heidenreich, F.; Rücker-Braun, E.; Walz, J. S.; Eugster, A.; Kühn, D.; Dietz, S.; Nelde, A.; Tunger, A.; Wehner, R.; Link, C. S.; Middeke, J. M.; Stölzel, F.; Tonn, T.; Stevanovic, S.; Rammensee, H. G.; Bonifacio, E.; Bachmann, M.; Zeis, M.; Ehninger, G.; Bornhäuser, M.; Schetelig, J.; Schmitz, M.
Mass spectrometry-based identification of a naturally presented receptor tyrosine kinase-like orphan receptor 1-derived epitope recognized by CD8+ cytotoxic T cells

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Permalink: https://www.hzdr.de/publications/Publ-26298
Publ.-Id: 26298


Isolation of Proteins from Polyacrylamide Gels

Koristka, S.; Arndt, C.; Bergmann, R.; Bachmann, M.
Minute amounts of proteins are required for immunization of mice for the development of antibodies including monoclonal antibodies. Here we describe a rapid procedure for the isolation of proteins from polyacrylamide gels after sodium dodecyl sulfate polyacrylamide gel electrophoresis in sufficient amounts for immunization of animals.
Keywords: Polyacrylamide gels, Isolation of proteins
  • Book chapter
    Kurien B., Scofield R.: Electrophoretic Separation of Proteins. Methods in Molecular Biology, Totowa, NJ, USA: Human Press, 2019, 461-465
    DOI: 10.1007/978-1-4939-8793-1_38

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Permalink: https://www.hzdr.de/publications/Publ-26297
Publ.-Id: 26297


Gel drying methods

Feldmann, A.; Berndt, N.; Bergmann, R.; Bachmann, M.
There are several reasons for drying of polyacrylamide gels after gel electrophoresis. E.g. if autoradiography should be performed from radioactive-labeled proteins. Another reason may be to simply store the gel in the laboratory book. Aside laborious commercial solutions, especially for storage of the dried gel in the lab book the here presented simple and cheap drying protocol may be sufficient.
Keywords: Polyacrylamide gels; Proteins; Gel drying
  • Book chapter
    Biji T. Kurien, R. Hal Scofield: Methods in Molecular Biology (Methods and Protocols), Totowa, NJ, USA: Human Press, 2018, 269-271
    DOI: 10.1007/978-1-4939-8745-0_31

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Permalink: https://www.hzdr.de/publications/Publ-26296
Publ.-Id: 26296


Silver Staining Techniques of Polyacrylamide Gels

Berndt, N.; Bergmann, R.; Arndt, C.; Koristka, S.; Bachmann, M.
After SDS-polyacrylamide gel electrophoresis the separated proteins have to be visualized by staining in the gel. The same is true after transfer of separated proteins to a blotting membrane in order to verify an efficient transfer and to visualize the amount of protein(s) which remained in the gel. Several different staining techniques exist for staining of proteins in SDS-polyacrylamide gels. The sensitivity of these staining procedures are different, also the expenditure of time and other aspects. Still, silver staining is among the most sensitive and reliable staining.
  • Book chapter
    Biji T. Kurien, R. Hal Scofield: Methods in Molecular Biology (Methods and Protocols), Totowa, NJ, USA: Human Press, 2018, 47-52
    DOI: 10.1007/978-1-4939-8745-0_7

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Permalink: https://www.hzdr.de/publications/Publ-26295
Publ.-Id: 26295


Native Polyacrylamide Gels

Arndt, C.; Koristka, S.; Feldmann, A.; Bachmann, M.
Proteins can easily be separated by polyacrylamide gel electrophoresis (PAGE) in the presence of a detergent and under (heat-) denaturing and (non- or) reducing conditions. The most commonly used detergent is sodium dodecyl sulfate (SDS). The major function of SDS is to shield the respective charge of the proteins present in the mixture to be analyzed and to provide all proteins with a negative charge. As a consequence, the proteins will be separated according to their molecular weight. Electrophoresis of proteins can also be performed in the absence of SDS. Using such “native” conditions, the charge of each of the proteins, which will depend on the primary amino acid sequence of the protein (isoelectric point) and the pH during electrophoresis, will mainly influence the mobility of the respective protein during electrophoresis. Here we describe a starting protocol for “native” PAGE.
Keywords: “Native” polyacrylamide gels, “Blue native” polyacrylamide gels, Proteins
  • Book chapter
    Kurien B., Scofield R.: Electrophoretic Separation of Proteins. Methods in Molecular Biology, Totowa, NJ, USA: Human Press, 2019, 87-91
    DOI: 10.1007/978-1-4939-8793-1_8

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Permalink: https://www.hzdr.de/publications/Publ-26294
Publ.-Id: 26294


Coomassie-Brilliant Blue Staining of Polyacrylamide Gels

Arndt, C.; Koristka, S.; Feldmann, A.; Bergmann, R.; Bachmann, M.
Over the past a series of staining procedures for proteins were published. Still, the most commonly used staining dye for proteins is Coomassie-Brilliant Blue. The major reasons are: Coomassie-Brilliant Blue staining is simple, fast and sensitive. As Coomassie-Brilliant Blue is almost insoluble in water a series of procedures including colloidal aqueous procedures were described.
Keywords: Coomassie Brilliant Blue, Polyacrylamide gels, Proteins
  • Book chapter
    in: Methods in Molecular Biology (Methods and Protocols), Totowa, NJ, USA: Human Press, 2018, 27-30
    DOI: 10.1007/978-1-4939-8745-0_4

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Permalink: https://www.hzdr.de/publications/Publ-26293
Publ.-Id: 26293


Local formation of III-V nanocrystals in Si by ion implantation and flash lamp annealing

Rebohle, L.; Wutzler, R.; Prucnal, S.; Hübner, R.; Georgiev, Y.; Erbe, A.; Böttger, R.; Helm, M.; Skorupa, W.
This presentation gives a short overview of our recent investigations devoted to the formation of III-V nanocrystals in bulk Si, in SOI substrates and at laterally defined positions. The group III and group V elements are incorporated by ion beam implantation, and the formation of III-V nanocrystals is due to liquid phase epitaxy during flash lamp annealing.
Keywords: ion implantation, flash lamp annealing, III-V integration into silicon, nanocrystal, liquid phase epitaxy
  • Lecture (Conference)
    42. Treffen der Nutzergruppe Heißprozesse und RTP, 08.11.2017, Itzehoe, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-26292
Publ.-Id: 26292


Microstructure and charge trapping in in ZrO2- and Si3N4-based superlattice layer systems with Ge nanoparticles

Seidel, S.; Rebohle, L.; Prucnal, S.; Lehninger, D.; Hübner, R.; Klemm, V.; Skorupa, W.; Heitmann, J.
Ge was deposited on silicon as a superlattice with 10 layers of Ge embedded in Si3N4 or ZrO2 matrices via plasma enhanced chemical vapor deposition or RF-sputtering, respectively. Raman spectroscopy, transmission electron microscopy and capacitance-voltage (CV) measurements were performed in order to investigate the structural and electrical properties of the superlattices. It will be shown that, in contrast to furnace annealing, flash lamp annealing of Ge-ZrO2-superlattices leads to crystalline Ge nanoparticles in an amorphous matrix. As revealed by CV measurements, these layers show excellent charge storage capabilities. In comparison, a higher thermal budget is needed to crystallize Ge in case of Si3N4-based superlattices, and no significant charge trapping could be detected during CV measurements.
Keywords: Ge nanocrystals, zirconium oxide, silicon nitride, superlattice, flash lamp annealing

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Permalink: https://www.hzdr.de/publications/Publ-26291
Publ.-Id: 26291


Quantification of MRI visibility and artefacts at 3T of liquid fiducial marker in a pancreas tissue mimicking phantom

Schneider, S.; Jølck, R. I.; Troost, E. G. C.; Hoffmann, A. L.
Introduction:
Image-guided radiotherapy (IGRT) of pancreatic ductal adenocarcinoma (PDAC) based on implanted fiducial markers and daily orthogonal kV X-ray imaging or cone-beam computed tomography (CBCT) has been shown to significantly reduce the setup error as compared to bony alignment1. In state-of-the-art IGRT solid gold markers are implanted into the pancreas using endoscopic ultrasonography (EUS), a procedure that is well established and generally well tolerated. However, solid gold markers not only deteriorate image quality in both CT and MRI, but additionally cause significant dose alterations in particle therapy, showing local dose perturbations up to 80% of the prescribed dose. Recently, a new biodegradable liquid marker has been developed, which forms a semisolid gel after injection into soft tissue. This marker may particularly benefit patients with PDAC who are scheduled for particle therapy, because it can be implanted using very thin (≤25 G) needles, its low Z-elemental (non-ferrous and non-magnetic) composition causes minimal proton dose perturbation in soft tissues, its size and visibility on X-ray images, CT and CBCT can be adjusted by controlling the injected volume and compound composition, and its soft-surface adhesiveness may decrease migration behaviour relative to solid markers. So far, the characteristics of the liquid marker on magnetic resonance imaging (MRI) have not been investigated.
It is the aim of the present work to provide a quantitative, pulse sequence-independent assessment of the visibility and artefacts of the new liquid fiducial marker on MRI and compare them against those of two gold markers commonly applied in IGRT of PDAC.
Methods:
To quantify the propensity of the different markers to generate signal voids and signal shifts on MRI, a spherical gel phantom mimicking the relaxation properties of healthy pancreatic tissue at 3 Tesla was constructed. Different volumes (10 µL, 25 µL, 50 µL and 100 µL) of the liquid marker (BioXmark®, Nanovi Radiotherapy A/S) were casted into the gel as well as four Gold Anchor™ (Naslund Medical AB; 0.28 mm diameter, 10 mm and 20 mm length) and three VisiCoil™ (IBA Dosimetry; 0.35 mm diameter, 5 mm and 10 mm length) markers, implanted in different orientations. MR relaxometry was performed to quantify the size and magnitude of the decrease in the effective transversal relaxation time T2* and water proton density ρ(H) relative to pure water as a measure of potential visibility, and to quantify the size and magnitude of the increase in magnetic field inhomogeneity ΔB0 as a measure of potential signal artefacts. The phantom was scanned with a 3.0 T Philips Ingenuity TF PET/MR scanner using an 8-channel head coil.
Results:
The solid fiducial markers showed a direct linear relationship between the potentially visible size and artefact size. The liquid fiducial marker showed a tendency towards a potentially visible size at smaller artefacts. Liquid markers from 25-100 μL generated visible volumes comparable to the visible size of the solid markers. The visible magnitude was the largest for the liquid fiducial marker with volumes of 25μL – 100μL showing no correlation with the magnitude of artefact. The solid markers showed a strong non-linear correlation between magnitude of visibility and artefact. The gold-iron alloy marker induced the strongest artefacts.
Discussion:
The liquid fiducial marker causes signal voids on MRI due to its absence of water hydrogen atoms without strongly affecting the magnetic field in the surrounding tissue. The alteration of the static magnetic field was found to be the main effect leading to the visibility of the solid fiducial markers.
Conclusion:
BioXmark® has beneficial MRI properties regarding the trade-off between potential visibility and artefacts compared to the tested solid gold markers that are currently being used for IGRT of PDAC. Contrary to the solid markers, an increase in visibility of BioXmark® was not directly coupled to an increase in artefact. Due to the proton density effect, BioXmark® behaves comparably in all pulse sequences if acquired at similar resolution.
  • Poster
    Joint annual meeting IMSRM-ESMRB 2018, 16.-21.06.2018, Paris, Frankreich

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Permalink: https://www.hzdr.de/publications/Publ-26290
Publ.-Id: 26290


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