Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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33407 Publications

Gastric Bypass Surgery Recruits a Gut – Striatal Dopamine Pathway to Reduce Fat Appetite in Obese Rats

Hankir, M. K.; Seyfried, F.; Hintschich, C. A.; Diep, T. A.; Kleberg, K.; Kranz, M.; Deuther-Conrad, W.; Tellez, L. A.; Rullmann, M.; Patt, M.; Teichert, S.; Sabri, O.; Brust, P.; Hansen, H. S.; de Araujo, I. E.; Krügel, U.; Fenske, W. K.
Roux-en-Y gastric bypass (RYGB) surgery produces well-documented improvements in maladaptive feeding behaviors, yet the underlying mechanisms remain ill-defined. As recognized mediators of fat intake, we evaluated the functional requirement of gut lipid-sensing and striatal dopamine signaling on healthier fat appetite after RYGB. We found that surgical rerouting of intestinal fat passage mobilized jejunal/ileal production of the dietary fat-derived molecule oleoylethanolamide (OEA). Vagal afferents link intestinal OEA signaling to nigrostriatal function. RYGB-treatment increased in vivo dorsal striatal dopamine release and dopamine-1-receptor density under conditions of high-fat meal consumption independently of bodyweight. Moreover, blocking OEA, vagal and dorsal striatal dopamine signaling all reversed the beneficial effects of surgery on fat appetite. Our findings suggest that RYGB re-sensitizes gut lipid-sensing to modify brain reward circuits compromised in obesity.

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Permalink: https://www.hzdr.de/publications/Publ-23617
Publ.-Id: 23617


In vivo demonstration of an active tumor pretargeting approach with peptide nucleic acid bioconjugates as complementary system

Leonidova, A.; Foerster, C.; Zarschler, K.; Schubert, M.; Pietzsch, H.-J.; Steinbach, J.; Bergmann, R.; Metzler-Nolte, N.; Stephan, H.; Gasser, G.
Aim
The ability of early-stage diagnosis of tumor malignancies and personalized treatment ultimately relies on the availability of highly tumor-affine compounds with purposeful pharmacological profile. Although monoclonal antibodies (mAbs) specifically bind to tumor-associated epitopes, the conventional concept of directly radiolabeled tumor-specific mAb has several drawbacks most prominently the prolonged radiation exposure of non-cancerous tissue. However, the concept of tumor pretargeting allows for the rational use of long-circulating high-affinity mAbs for non-invasive cancer radioimmunodetection and therapy. Our work describes a successful tumor pretargeting utilizing an EGFR-specific mAb and peptide nucleic acid (PNA) derivatives as the complementary system for specific radionuclide delivery to pretargeted tumor tissue.

Methods
After chemical synthesis, purification and detailed characterization of the individual components including antibody-PNA conjugates and different PNA oligomers, biodistribution studies were carried out using healthy Wistar rats. Finally, the pretargeting approach was evaluated in murine A431 tumor xenografts by single photon emission computed tomography.

Results
After optimizing the pharmacokinetic properties of PNA oligomers and investigating their hybridization properties, we elaborated a versatile conjugation protocol based on coupling a cysteine-functionalized PNA oligomer to a maleimido-functionalized mAb. The in vivo studies demonstrated a rapid and efficient accumulation of activity at the tumor site with a tumor-to-muscle ratio of > 8 and clearly distinguishable tumor visualization.

Conclusion
This successful tumor pretargeting study has demonstrated the high potential of this concept by applying radiolabeled complementary PNA strands as an alternative in vivo recognition and radionuclide transporting system. The next step involves the translation of these results to the application of therapeutic relevant radionuclides.
  • Lecture (Conference)
    NuklearMedizin 2016 - 54. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin e.V., 20.-23.04.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23616
Publ.-Id: 23616


Single-domain antibodies for specific nanoparticle targeting of the EGF-receptor

Zarschler, K.
For effective localization of functionalized nanoparticles at diseased tissues such as solid tumours or metastases through biorecognition, appropriate targeting vectors directed against selected tumour biomarkers are a key prerequisite. The diversity of such vector molecules ranges from proteins, including antibodies and fragments thereof, through aptamers and glycans to short peptides and small molecules.
The presented work focusses on the epidermal growth factor receptor (EGFR) acting as a model receptor, since it is overexpressed and/or deregulated in a variety of solid tumours. Thus, bioconjugation of EGFR-specific single-domain antibodies (sdAbs) to different nanomaterials and characterization of sdAb-conjugates covering in vitro cancer cell imaging, cell proliferation as well as EGFR phosphorylation and signalling are described. The specificity of the sdAb-conjugates is investigated by way of receptor RNA silencing techniques with increasing complexity in vitro by introducing increasing concentrations of human or bovine serum. The results show that sdAb-functionalised nanomaterials can effectively target the EGFR, even in more complex bovine and human serum conditions where targeting specificity is largely conserved for increasing serum concentration. For highly affine targeting ligands such as sdAbs, targeting a receptor such as EGFR with low serum competitor abundance, receptor recognition function can still be partially realised in complex conditions. Moreover, sdAb-mediated biorecognition of EGFR is not restricted to particular nanomaterials, but was observed to work efficiently in combination with a variety of materials.
  • Invited lecture (Conferences)
    Scientific Symposium "Targeting tumor angiogenesis with antibody-based technologies", 08.06.2015, Madrid, Spanien

Permalink: https://www.hzdr.de/publications/Publ-23615
Publ.-Id: 23615


Diagnostic and therapeutic targeting of EGF-receptor positive cancer cells using single-domain antibodies

Zarschler, K.
Single-domain antibodies (sdAbs) provide several advantages over classical antibodies and fragments thereof. Due to their small size and strict monomeric appearance combined with other important properties such as high solubility and stability as well as high specificity and affinity for the respective antigen, these proteins have been identified as attractive targeting moieties for molecular imaging and drug delivery. Furthermore, sdAbs are easily engineered into bivalent and bispecific constructs by genetic in-frame joining of two identical or two different sdAbs, respectively. This results in increased antigen binding through avidity effects and in enhanced construct specificity by simultaneous interaction with two different antigens, respectively.
In addition to intrinsic agonistic or antagonistic effects on their target, sdAbs appear to be ideally suited to create novel tailored derivatives equipped with innovative effector functions. The chemical or genetic linkage of sdAbs to accessory effector moieties such as toxins and enzymes results in a new class of target-specific anticancer therapeutics. Thereby, the sdAb guides the effector moiety to the diseased tissue, where it carries out its particular function.
Herein the application of radiolabelled epidermal growth factor receptor (EGFR) specific sdAbs as in vivo molecular imaging tracers as well as their intrinsic antagonistic effects on tumor cells will be described. Furthermore, the construction and characterisation of sdAb-based therapeutics will be exemplified. Thus, this contribution sheds light on the future application of sdAb derivatives in the field of cancer diagnosis and therapy.
  • Lecture (Conference)
    PACHIFICHEM 2015, 15.-20.12.2015, Honolulu, USA

Permalink: https://www.hzdr.de/publications/Publ-23614
Publ.-Id: 23614


Ultra-fast Thermal Processing

Rebohle, L.; Schumann, T.; Prucnal, S.; Skorupa, W.
Thermal processing in the subsecond range comprises modern, non-equilibrium annealing techniques which allow various material modifications at the surface without affecting the bulk. Flash lamp annealing (FLA) is one of the most diverse methods of short time annealing with applications ranging from the classical field of semiconductor doping to the treatment of polymers and flexible substrates. The presentation focuses on several FLA aspects which are especially important for thin film applications. In detail, it briefly introduces to the technological background, deals with the broad subject of temperature distributions and addresses constraints and other process issues like thermal stress or homogeneity. Finally, an overview of the various applications of FLA is given.
Keywords: flash lamp annealing, pulsed light sintering, semiconductors
  • Invited lecture (Conferences)
    The International Conference on Coatings on Glass and Plastics, 12.-16.06.2016, Braunschweig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23613
Publ.-Id: 23613


Subsecond thermal processing with flash lamps: equipment and modelling issues

Schumann, T.; Rebohle, L.; Skorupa, W.
This contribution presents an overview of the complex technical aspects of flash-lamp-annealing-tools for thermal processing in the millisecond range used at the Helmholtz Research Center Dresden-Rossendorf (HZDR). It outlines that Flash Lamp Annealing (FLA) is established as a high-performance alternative to Rapid Thermal Annealing and Furnace Annealing when it comes to treatment of the most advanced thin layer and coating materials, thus enabling the fabrication of novel electronic structures and materials classes. It shows the unique variety of parameters the HZDR is able to provide for applications ranging from annealing of implanted Si and Ge, transparent conductive oxides, photovoltaic materials, silver and copper inks on various non-metal substrates to exceptional applications (roof tiles, watchcases). It explains, how crucial parameters, such as emission spectrum, energy density, and preheat temperature are monitored to provide a reliable reproducibility. Modelling aspects regarding temperature distribution and heat transport within the millisecond range will also be addressed. Furthermore, a summary will be given of characteristic features of our tools to convey the diversity of the fields of application and the enormous range of possible research.
Keywords: flash lamp annealing
  • Poster
    The International Conference on Coatings on Glass and Plastics, 12.-16.06.2016, Braunschweig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23612
Publ.-Id: 23612


Flash lamp annealing for low-cost transparent conducting oxide layers

Rebohle, L.; Mathey, A.; Prucnal, S.; Wiesenhütter, K.; Vines, L.; Lindberg, P.; Svensson, B.; Bregolin, F. L.; Skorupa, W.
Aluminum-doped zinc oxide (AZO) is one of the most promising transparent conductive oxide material which is characterized by low resistivity, high transparency and most of all, by low cost of fabrication. AZO thin-films were deposited on p-type Si wafers via r.f. magnetron sputtering either at room temperature or at 400 °C followed by a thermal treatment in the millisecond range using flash lamp annealing (FLA). It is shown that FLA enhances the electrical activation of Al and minimizes secondary phase formation during post-deposition annealing. In addition, the optoelectronic and microstructural properties of the FLA treated samples are independent on the deposition temperature. As FLA is a cost-effective, easily scalable high-throughput technology, these results opens the possibility for a further, desirable cost reduction of the overall fabrication process.
Keywords: flash lamp annealing, doping, zinc oxide, transparent conducting oxide
  • Poster
    The International Conference on Coatings on Glass and Plastics, 12.-16.06.2016, Braunschweig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23611
Publ.-Id: 23611


X-ray spectroscopic study of the chemical state of “invisible” Au in synthetic minerals in the Fe-As-S system

Trigub, A. L.; Tagirov, B. R.; Kvashnina, K. O.; Chareev, D. A.; Nickolsky, M. S.; Shiryaev, A. A.; Baranova, N. N.; Mokhov, E. V. Kovalchuk A. V.
Minerals of the Fe-As-S system are ubiquitous components of Au ores in many deposits of hydrothermal origin, including world-class volcanogenic massive sulfide, low-temperature epithermal and mesothermal ones. The “invisible” (or refractory) form of Au is present in all types of hydrothermal ores and in many cases predominates. Knowledge of the “invisible” Au chemical state (local atomic environment/structural position, electronic structure and oxidation state) is a fundamental problem crucial for understanding conditions of the ore formation, is necessary for physical-chemical modeling of hydrothermal Au mineralization, and will help to create more efficient technologies of ore concentration and Au extraction. We report investigation of the “invisible” Au chemical state in synthetic analogues of natural minerals: pyrite (FeS2), arsenopyrite (FeAsS), and löllingite (FeAs2). The compounds were synthesized using hydrothermal (pyrite) and salt flux techniques (all the minerals) and studied using X-ray absorption fine structure spectroscopy (XAFS) in high energy resolution fluorescence detection (HERFD) mode in combination with first-principles quantum chemical calculations. The concentration of the “invisible” Au in the synthesized löllingite (800±300 ppm) was much higher compared to arsenopyrite (23±14 ppm), whereas the lowest Au content with zonal Au concentration profiles was observed in crystals of salt flux pyrite. The concentration of Au in the hydrothermal pyrite (40-90 ppm) is independent on sulfur fugacity and probably reflects the maximum Au solubility at the experimental P/T parameters (450 °C, 1 kbar). It is shown that Au replaces Fe in structure of löllingite, arsenopyrite, and hydrothermal pyrite. The nearest-neighbors Au-ligand distance increases by 0.14 Å (pyrite), 0.16 Å (löllingite), and 0.23 (As), 0.13 (S) Å for arsenopyrite relative to Fe-ligand distance in pure compounds. Distortion of the local atomic structure around the Au is negatively correlated with the distance and disappears at r > ~4 Å. The chemically bound Au is stable only in hydrothermal pyrite, whereas the pyrite synthesized in the absence of hydrothermal fluid contains only Au°. Heating (metamorphism) of hydrothermal pyrite results in decomposition of the chemically bound Au with formation of Au° nuggets which coarsen with temperature. Depending on chemical composition of the host mineral Au can play a role either of cation or anion: the Bader atomic partial charges of Au decrease in the order of pyrite (+0.4 e) > arsenopyrite (0) > löllingite (-0.4 e). Our results suggest that other noble metals (platinum group elements, Ag) can form the chemically bound refractory admixture in base metal sulfides/chalcogenides. The chemical state, as well as the concentration, of this form of noble metals can differ depending on the composition of the host mineral and the ore history.
Keywords: invisible gold, pyrite, arsenopyrite, löllingite, synthetic minerals, X-ray absorption spectroscopy, atomic charges

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Permalink: https://www.hzdr.de/publications/Publ-23610
Publ.-Id: 23610


Microbial Influence on Bentonite-Transformation

Matschiavelli, N.; Steglich, J.; Arnold, T.; Cherkouk, A.
Bentonites are clay silicates consisting mostly of montmorillonite. Due to their mineral composition, bentonites are characterized by a high swelling capacity and low hydraulic conductivity. Therefore, Bentonite is a promising raw material for serving as a natural clay barrier for the disposal of highly radioactive waste. To address the question, whether and to which extend microbial activity affects the respective parameters, selected bentonites can be supplied with a pore water solution and afterwards incubated for short- and long-term analyses at different temperatures in order to simulate the evolution of microbial activity and the resulting impact on Bentonite-transformation. For characterization the respective Bentonite samples will be analyzed considering their geochemistry, molecular biology and mineralogy – three divisions that influence each other directly. We expect that the obtained results could reveal variations in microbial diversity and a correlation with changes of geochemical parameters which could affect the composition and solubility of minerals, and furthermore the beneficial properties of bentonite. The gained information can be further used to indicate a trend in bentonite transformation, which is a prerequisite for evaluating the influence of prokaryotes on safety-relevant processes and properties in radioactive waste repositories.
  • Contribution to proceedings
    MIND Project Annual Meeting, 03.-04.05.2016, Granada, Spain
  • Lecture (Conference)
    MIND Project Annual Meeting, 03.-04.05.2016, Granada, Spain
  • Poster
    MIND Project Annual Meeting, 03.-04.05.2016, Granada, Spain

Permalink: https://www.hzdr.de/publications/Publ-23609
Publ.-Id: 23609


Clinical Validation of a New Digital Spectrometer System for Range Verification in Proton Therapy

Werner, T.; Petzoldt, J.; Hueso-González, F.; Berthold, J.; Rinscheid, A.; Enghardt, W.; Pausch, G.
Particle therapy is a promising technique for cancer treatment because of the characteristic dose deposition of protons in matter. As an alternative method to conventional photon therapy, it allows a precise irradiation of the tumor volume in the patient body, while sparing healthy, radiosensitive organs.
However, body modifications during the treatment period hinder the precise positioning of the Bragg peak in the target volume, and thus limits the accuracy of proton therapy.
These uncertainties and the lack of a suitable monitoring system, which should control the range in vivo and real-time during the irradiation, make it necessary to establish broad safety margins around the irradiated volume in the patient body. This decreases the effectiveness of the therapy and reduces the benefits compared to conventional photon therapy. To counteract this, many solutions for a clinically applicable system for online range verification are under discussion. One approach is the Prompt Gamma Timing (PGT) method. The energy-resolved timing spectra of the detected photons encode the range information of the primary protons and allow a real time range verification [1]. The concept of PGT was developed and tested in first experiments, which confirm that PGT is a promising method for range assessment [2]. Especially the simplicity of the concept according to the experimental implementation justifies a further development with special focus on clinical applications.
  • Lecture (Conference)
    IEEE Nuclear Science Symposium and Medical Imaging Conference, 29.10.-06.11.2016, Strasbourg, France

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Permalink: https://www.hzdr.de/publications/Publ-23608
Publ.-Id: 23608


Field-Induced Magnonic Liquid in the 3D Spin-Dimerized Antiferromagnet Sr3Cr2O8

Wang, Z.; Quintero-Castro, D. L.; Zherlitsyn, S.; Yasin, S.; Skourski, Y.; Islam, A. T. M. N.; Lake, B.; Deisenhofer, J.; Loidl, A.
We report on ultrasound and magnetization studies in three-dimensional, spin-dimerized Sr3Cr2O8 as a function of temperature and external magnetic field up to 61 T. It is well established [A. A. Aczel et al., Phys. Rev. Lett. 103, 207203 (2009)] that this system exhibits a magnonic-superfluid phase between 30 and 60 T and below 8 K. By mapping ultrasound and magnetization anomalies as a function of magnetic field and temperature we establish that this superfluid phase is embedded in a domelike phase regime of a hightemperature magnonic liquid extending up to 18 K. Compared to thermodynamic results, our study indicates that the magnonic liquid could be characterized by an Ising-like order but has lost the coherence of the transverse components.

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Permalink: https://www.hzdr.de/publications/Publ-23607
Publ.-Id: 23607


Characterization of a fast timing and energy spectroscopy system for real-time range verification in particle therapy

Rinscheid, A.; Berthold, J.; Enghardt, W.; Golnik, C.; Fiedler, F.; Hueso-González, F.; Kormoll, T.; Petzoldt, J.; Römer, K.; Werner, T.; Wolf, A.; Reichert, D.; Pausch, G.
A compact high-throughput gamma-ray timing and energy spectrometry systems has been characterized with respect to time and energy resolution at detector loads up to 1.5 Mcps by using 0.1-12.5 MeV bremsstrahlung and a common radioactive source. The detection system, developed for range assessment in particle therapy based on the Prompt Gamma-Ray Timing (PGT) technique, consist of a commercial ⌀2”×1” or ⌀2”×2” CeBr 3 scintillation detector with photomultiplier readout (Scionix), coupled to a digital plug-on spectrometer (U100) by Target Systemelektronik. The excellent time structure of the bremsstrahlung beam at ELBE (HZDR) allowed measuring the system time resolution simultaneously for 0.1-12 MeV photons. Also, the beam current and thus the detector load could be varied in a wide range. The energy resolution was determined in parallel with a 60 Co-source attached to the detector. Source and bremsstrahlung photons were separated by means of cuts in the timing spectra measured against the accelerator RF. The detection system could demonstrate a time resolution of < 260 ps (FWHM) for energies above 3 MeV with the smaller crystal, and an energy resolution of < 3.7% at 1.173 MeV for both crystals, up to detector loads of 1.4 Mcps and a corresponding system throughput of ~ 600 kcps. This fits well with the design goals of the detection system. Corresponding units shall be used for measuring PGT spectra during patients treatments with proton beams, in order to verify the proton beam range for single beam spots in Pencil Beam Scanning (PBS) mode. Range verification is considered a key for reducing margins and for improving precision and health outcome of particle therapy.
  • Lecture (Conference)
    2016 IEEE Nuclear Science Symposium and Medical Imaging Conference, 29.10.-06.11.2016, Strasbourg, France

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Permalink: https://www.hzdr.de/publications/Publ-23606
Publ.-Id: 23606


Ultraschall zur Bestimmung von Partikelbewegungen in flüssigem Metall

Hoppe, D.; Strumpf, E.
In flüssigem Metall schwebende Partikel können Echos von Ultraschall verursachen. Aus solchen Echos wird versucht, die entlang der Schallausbreitung vorkommenden Partikelbewegungen zu rekonstruieren. Konkret sind damit die Positionen gemeint, welche die Partikel vertikal oberhalb des Schallwandlers als Funktionen der Zeit einnehmen. Anhand solcher Funktionen soll dann auf Strömungsvorgänge im flüssigen Metall geschlossen werden.
Keywords: Flüssigmetall Ultraschall Partikelbewegungen

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Permalink: https://www.hzdr.de/publications/Publ-23605
Publ.-Id: 23605


Use of Target Capsules for Radiolabeling of Platinum Nanoparticles with a Modified Nirta® Solid Target Station (Cyclone 18/9)

Franke, K.
The increased use of nanoparticles (NP) in technical processes and consumer products requires a comprehensive and thorough nanosafety research. Challenging is the sensitive and selective detection of NP in different environments. Here radiolabeling offers a unique tool for even in situ detection of NP for nanosafety studies. Often radiotracers are introduced into NP via the NP synthesis process. Highest activity concentrations are achievable. However, this strategy requires careful characterization of the synthesized NP to allow a comparison with the commercially available NP. Mostly there is very little detailed knowledge about the commercial synthesis process. The direct activation of NP can overcome this limitation. In this study we present the use of a Cyclone 18/9 for the activation of 10 nm Pt-NP. The activation yields into the NP labeling with Au radionuclides.
Keywords: Platinum nanoparticles Cyclotron Radiolabeling Targetry Gold radioisotopes
  • Lecture (Conference)
    16th International Workshop on Targetry and Target Chemistry (WTTC16), 29.08.-01.09.2016, Santa Fe, USA

Permalink: https://www.hzdr.de/publications/Publ-23604
Publ.-Id: 23604


Measurement of the 92,93,94,100Mo(γ,n) reactions by Coulomb Dissociation

Göbel, K.; Adrich, P.; Altstadt, S.; Alvarez-Pol, H.; Aksouh, F.; Aumann, T.; Babilon, M.; Behr, K.-H.; Benlliure, J.; Berg, T.; Böhmer, M.; Boretzky, K.; Brünle, A.; Beyer, R.; Casarejos, E.; Chartier, M.; Cortina-Gil, D.; Chatillon, A.; Pramanik, U. D.; Deveaux, L.; Elvers, M.; Elze, T. W.; Emling, H.; Erhard, M.; Ershova, O.; Fernandez-Dominguez, B.; Geissel, H.; Górska, M.; Heftrich, T.; Heil, M.; Hellstroem, M.; Ickert, G.; Johansson, H.; Junghans, A. R.; Käppeler, F.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Labiche, M.; Langer, C.; Bleis, T. L.; Lemmon, R.; Lindenberg, K.; Litvinov, Y. A.; Maierbeck, P.; Movsesyan, A.; Müller, S.; Nilsson, T.; Nociforo, C.; Paar, N.; Palit, R.; Paschalis, S.; Plag, R.; Prokopowicz, W.; Reifarth, R.; Rossi, D. M.; Schnorrenberger, L.; Simon, H.; Sonnabend, K.; Sümmerer, K.; Surówka, G.; Vretenar, D.; Wagner, A.; Walter, S.; Waluś, W.; Wamers, F.; Weick, H.; Weig, M.; Winckler, N.; Winkler, M.; Zilges, A.
The Coulomb Dissociation (CD) cross sections of the stable isotopes 92,94,100 Mo , of the unstable isotope 93 Mo were measured at the L, /R 3 B setup at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of 92,94 Mo , 96,98 Ru in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction 93 Mo(γ,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94 Mo(γ,n) reaction is presented. Further analysis will complete the experimental database for the (γ,n) production chain of the p-isotopes of molybdenum.
  • Open Access Logo Contribution to proceedings
    Nuclear Physics in Astrophysics VI (NPA6), 19.-24.05.2013, Lisboa, Portugal
    Journal of Physics: Conference Series 665, London: IOPscience, 012034
    DOI: 10.1088/1742-6596/665/1/012034

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Permalink: https://www.hzdr.de/publications/Publ-23603
Publ.-Id: 23603


Radiation dosimetry of the α4β2 nicotinic receptor ligand (+)-[18F]Flubatine, comparing preclinical PET/MRI and PET/CT to first-in-human PET/CT results

Kranz, M.; Sattler, B.; Tiepolt, S.; Wilke, S.; Deuther-Conrad, W.; Donat, C.; Fischer, S.; Patt, M.; Schildan, A.; Patt, J.; Smits, R.; Hoepping, A.; Steinbach, J.; Sabri, O.; Brust, P.
Background: Both enantiomers of [18F]flubatine are promising radioligands for neuroimaging of α4β2 nicotinic acetylcholine receptors with positron emission tomography (PET) exhibiting promising pharmacokinetics which makes them attractive for different clinical questions. Ina previous preclinical study, the main advantage of (+)-[18F]flubatine compared to (-)-[18F]flubatine was its higher binding affinity suggesting that (+)-[18F]flubatine might be able to detect also slight reductions of α4β2 nAChRs and could be more sensitive than (-)-[18F]flubatine in early stages of Alzheimer's disease. To support the clinical translation, we investigated a fully image-based internal dosimetry approach for (+)-[18F]flubatine, coparing mouse data collected on a preclinical PET/MR system to piglet and first-in-human data acquired on a clinical PET/CT system. Time-activity curves (TACs) were obtained from the three species, the animal data extrapolated to human scale, exponentially fitted and the organ doses (OD), and the effective dose (ED) calculated with OLINDA.

Results: The excreting organs (urinary bladder, kidneys, and liver) receive the highest organ doses in all species. Hence, a renal/hepatobiliary excretion pathway can be assumed. In addition, the ED conversion factors of 12.1 µSv/MBq (mice), 14.3 µSv/MBq (piglets) and 23.0 µSv/MBq (humans) were calculated which are well within the order of magnitude as known from other 18F-labeled radiotracers.

Conclusion: Although both enantiomers of [18F]flubatine] exhibit different binding kinetics in the brain due to the respective affinities, the effective dose revealed no enantiomer-specific differences among the investigated species. The preclinical dosimetry and biodistribution of (+)-[18F]flubatine was shown and the feasibility of a dose assessment based on image data acquired on a small animal PET/MR and a clinical PET/CT was demonstrated. Additionally, the first-in-human study confirmed the tolerability of the radiation risk of (+)-[18F]flubatine imaging which is well within the range as caused by other 18F-labeled tracers. However, as shown in previous studies, the ED in humans is underestimated by up to 50 % using preclinical imaging for internal dosimetry. This fact needs to be considered when applying for first-in-human studies based on preclinical biokinetic data scaled to human anatomy.
Keywords: Image-based internal dosimetry (+)-[18F]flubatine Preclinical hybrid PET/MRI, Radiation safaty, Nicotinic receptors, Dosimetry, OLINDA/EXM

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Permalink: https://www.hzdr.de/publications/Publ-23602
Publ.-Id: 23602


THEREDA, the thermodynamic reference database for a nuclear waste disposal in Germany

Bok, F.; Moog, H. C.; Altmaier, M.; Voigt, W.; Thoenen, T.
The disposal of nuclear waste including the assessment of long-term safety is still an open question in Germany. In addition to the still pending decision about the repository host rock (salt, granite, or clay) the basic necessity of a consistent and obligatory thermodynamic reference database persists. Such a database is essential to assess potential failure scenarios accurately and to make well-founded predictions about the long-term safety. Specific challenges are comprehensive datasets covering also high temperatures and salinities. Against this background, available databases do not suffice and are limited in their use, partly because of high restrictions and resulting incompleteness of reactions. Other databases rely on heterogeneous and therefore inconsistent data leading to incorrect model calculations. Due to these deficiencies THEREDA, a joint project of institutions leading in the field of safety research for nuclear waste disposal in Germany and Switzerland, was started in 2006.
THEREDA contains a relational databank whose structure has been designed in a way that promotes the internal consistency of thermodynamic data. Data considered cover the needs of Gibbs Energy Minimizers (ChemApp) and Law-of-Mass-Action programs (Geochemist’s Workbench, EQ3/6, PHREEQC) alike. Parameters for a variety of models describing interactions in mixed phases are included. Namely the Pitzer parameters to describe activity coefficients of hydrated ions and molecules are considered. Both thermodynamic and interaction parameters can be described by temperature functions.
THEREDA offers evaluated thermodynamic data for many compounds (solid phases, aqueous species, or constituents of the gaseous phase) of elements relevant according to the present state of research. In particular, all oxidation states expected for disposal site conditions are covered.
Ready-to-use parameter files are created from the databank in a variety of formats (generic ASCII type, and formats required by the geochemical speciation codes) and offered to the users. They are also used for internal test calculations – one essential element of the quality assurance scheme. The results are documented and provided to the users.
THEREDA is accessible via internet through www.thereda.de. This is not only a portal to the database, but shall also serve as an information and discussion platform on issues concerning the database. Thus we are confident to generate helpful feedback from the anticipated user community.
Keywords: THEREDA, Modelling, Solubility, Pitzer, Thermodynamic, Database
  • Poster
    17 International Symposium on Solubility Phenomena and Related Equilibrium Processes (ISSP17), 24.-29.07.2016, Geneva, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-23600
Publ.-Id: 23600


Oxygen solubility modelling in water and brines

Bok, F.; Moog, Helge C.
Dissolved molecular oxygen influences the chemistry of various redox reactions in the aqueous solution e.g. corrosion processes, microbial activity or the immobilisation of radionuclides. In the presence of dissolved oxygen, the poorly soluble (hydro)oxides of reduced actinides, e.g. U(OH)₄(am), PuO₂(am/cr) get oxidized and these elements become more soluble in water. Furthermore, the activity of dissolved oxygen is used as redox parameter in common geochemical codes (i.e. Geochemist’s Workbench®). Thus, the correct prediction of the O₂ solubility in water and saline solutions is necessary for the correct modelling of redox processes in water and in brines especially.
For reasons of consistency, the few existing sets of O₂-ion interaction coefficients for the Pitzer model cannot be used in combination with the THEREDA Pitzer model for the oceanic salt system and would result in wrong gas solubility calculation’s results. Therefore, a new and consistent set of solubility parameters was deduced using published O₂ solubility data in water and binary and ternary salt solutions from ~100 literature references.
First a critical review of the published data on oxygen solubility in water and salt solutions has been performed. Using these data, the temperature function of the O₂ Henry’s constant could be obtained valid for the temperature range 273–618 K. Then a consistent set of Pitzer interaction coefficients including its temperature function’s parameters was deduced for the calculation of the amount of dissolved oxygen in aqueous solution and brines. All parameters have been determined using the geochemical speciation software PHREEQC coupled with the parameter estimation software UCODE-2005.
A self-consistent set of Pitzer interaction coefficients for the description of oxygen solubility in binary and some ternary salt solutions could be obtained for the system Na⁺, K⁺, H⁺, Ca²⁺, Mg²⁺ / Cl⁻, SO₄²⁻, CO₃²⁻, PO₄³⁻, OH⁻ - H₂O(l). For the chloride and the sulphate subsystems, temperature function parameters could be obtained to describe the temperature dependency of the O₂ solubility in these salt solutions.
Keywords: Saline solutions, Redox, Oxygen, Pitzer, Solubility
  • Lecture (Conference)
    17 International Symposium on Solubility Phenomena and Related Equilibrium Processes (ISSP17), 24.-29.07.2016, Geneva, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-23599
Publ.-Id: 23599


Application of solvent extraction to environmental science - Identification of radioactive contaminants in surface water

Ikeda-Ohno, A.
Solvent extraction is a very traditional but still a very versatile technique with a variety of applications. This presentation will focus on the application of solvent extraction particularly to the environmental science associated with radioactive contamination.
Keywords: Solvent extraction, separation, surface water, environmental science, speciation, actinides, radionuclides, radioactive contamination
  • Invited lecture (Conferences)
    Interdisciplinary German-Japanese Symposium iJaDe2016 - 2nd German-Japanese Microsymposium "Solvent Extraction: From Fundamentals to Applications", 10.05.2016, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-23598
Publ.-Id: 23598


High Conductivity in Molecularly p-doped Diketopyrrolopyrrole–Based Polymer: the Impact of a High Dopant Strength and Good Structural Order

Karpov, Y.; Erdmann, T.; Raguzin, I.; Al-Hussein, M.; Binner, M.; Lappan, U.; Stamm, M.; Gerasimov, K. L.; Beryozkina, T.; Bakulev, V.; Anokhin, D. V.; Ivanov, D. A.; Günther, F.; Gemming, S.; Seifert, G.; Voit, B.; Kiriy, A.
[3]-Radialene-based dopant CN6-CP studied herein, with its reduction potential of +0.8 vs Fc/Fc+ and LUMO level of -5.88 eV, is the strongest molecular p-dopant reported in open literature so far. The efficient p-doping of the donor-acceptor copolymer PDPP(6-DO)2TT having the HOMO level of -5.5 eV was achieved which confirmed by UV-vis-IR spectroscopy studies and DFT calculations. Films of PDPP(6-DO)2TT doped by CN6-CP exhibit electrical conductivities up to 50 S/cm which is one of the highest conductivity for molecularly doped semiconducting polymers. The high conductivity is attributed to a good structural order in the doped polymer as confirmed by x-ray scattering studiesdue and its high doping level. CN6-CP shows a relatively good thermal stability up to 280°C and it withstands sublimation in vacuum which makes it potentially suitable for the doping of small semiconducting molecules processed by vacuum evaporation techniques. The superior electron affinity of CN6-CP significantly broadens the range of semiconductors that can be used in devices in the p-doped state.
Keywords: p-dopant, conjugated polymer, electrical conductivity, organic electronics

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Permalink: https://www.hzdr.de/publications/Publ-23597
Publ.-Id: 23597


Hopping Based Charge Transfer in Diketopyrrolopyrrole Based Donor-Acceptor Polymers: A Theoretical Study

Günther, F.; Gemming, S.; Seifert, G.
Diketopyrrolopyrrole (DPP) based materials have recently been considered as promising candidates for novel organic electronics.
In this article, we report an investigation on intermolecular charge transfer between DPP based polymers.

We use Marcus transfer theory and evaluate the required quantities, the reorganization energy and the coupling, by density functional-based tight binding (DFTB) calculations.
Since the coupling is dependent on the stacking geometry we employ an energy-weighted statistical approach to derive a single quantity, which can been entered in the Marcus formula.
This value contains the variation of the coupling when the stacking conformation is changed.
The application of this method, as we implement it in this study, does not require a detailed analysis of the energy landscape, but samples over large number of stacking possibilities on a regular, but very dense grid into account.
These average values can been used to analyze isomeric effects such as the orientation of units, the influence of the molecular structure as functionalization, or the importance of stacking properties as parallel and anti-parallel stacking.
The obtained results show that enhanced charge carrier mobilities can be achieved when specific molecular configurations are considered rather than by working with a set of random orientations.
Keywords: Diketopyrrolopyrrole, Hopping, Electronic Transfer, Marcus theory, density functional based tight binding

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Publ.-Id: 23596


Lutetium Fine Silicate (LFS): A new scintillator for range-verification applications in oncology

Roemer, K.; Pausch, G.; Bemmerer, D.; Fahmy, K.; Golnik, C.; Hueso-Gonzalez, F.; Iltzsche, M.; Lutz, B.; Petzoldt, J.; Weinberger, D.; Fiedler, F.
Proton therapy facilities are built all around the world for optimized cancer treatments. In order to fully exploit the advantages of this therapy, a proton range verification is mandatory. The most promising advances use either the positron emission tomography (PT-PET) approach or the prompt gamma emissions caused by nuclear reactions (by means of passive collimation, Compton cameras or prompt gamma timing). Gamma ray detectors in this field face unique requirements: Good properties with respect to energy, time and spatial resolution even when operated with high counting rates in rather high background environments.
Lutetium Fine Silicate (LFS) is a novel scintillation material which is especially designed for PET applications. Thus, in this work, the characteristics of LFS are determined for energy ranges which match the requirements of the prompt gamma ray monitors (i.e. up to 8 MeV). The usage of different photodetectors (i.e. PMT or Silicon-based read-out), depending on the particular application, is discussed.
Keywords: Scintillator, Photodetector, Proton range monitor
  • Lecture (Conference)
    2016 IEEE NSS/MIC, 29.10.-06.11.2016, Strasbourg, France
  • Poster
    2016 IEEE NSS/MIC, 30.10.-05.11.2016, Strassbourg, France

Permalink: https://www.hzdr.de/publications/Publ-23595
Publ.-Id: 23595


Determination of stability constants of selected U(VI) flavonol complexes by absorption and emission spectroscopy

Günther, A.; Geipel, G.
Flavonols are polyphenol compounds, which belong to the class of flavonoids. They are produced by plants and can be segregated by the root into the soil. Flavonols can bind metals, e.g. Co, Fe, Ni, Al, Zn and Pb due to the presence of the carbonyl group on the gamma-pyranone ring and the hydroxyl groups as substituents in different positions of the whole organic molecule. The interactions of these polyphenols with radioactive metals have been studied very rare up to now. In this work first results of spectroscopic investigations of the U(VI) complexation by flavonols with several number of hydroxyl groups and glycosidic substituent are presented and discussed. The flavonols and their U(VI) complexes have specific absorption bands and emission signals in the UV-Vis range, which were used for the calculation of deprotonation constants of organic ligands and of the stability constants of the formed U(VI) flavonol complexes in methanolic solution.
Keywords: Flavonol, Uran(VI), complexation, absorption, emission
  • Poster
    Biometals, 10.-15.07.2016, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-23594
Publ.-Id: 23594


Mobilisation of metals from Kupferschiefer sensu strictu in neutral to alkaline environment using bulk and biotechnologically produced organic acids

Kostudis, S.; Kutschke, S.; Pollmann, K.
The European Kupferschiefer deposits constitute a challenging local resource of a broad spectrum of metals such as copper, manganese, molybdenum, silver and zinc. In order to exploit them both efficiently and environmentally benignly, biotechnological leaching approaches are investigated. Commonly used acidophilic bioleaching is limited by high carbonate content of up to 18 % resulting in an increased pH value of more than 2. Hence, alternative processes such as neutral leaching are tested. Experiments were aiming at metal solubilisation using glutamic and citric acid as bulk chemicals, as well as biotechnologically produced citric acid. Subsequently, mobilisation of Cu, Mn, Mo, Co, Zn, Ga, Ag, Au, Ni and Pt has been reported. Results show that mostly the use of organic acids in neutral to alkaline pH range performs better in metal solubilisation than in acidic milieu.
Keywords: Kupferschiefer, black shale, leaching, organic acid, copper, trace metals, mobilisation
  • Contribution to proceedings
    Biohydrometallurgy '16, 20.-22.06.2016, Falmouth, United Kingdom
    Proceedings of Biohydrometallurgy '16

Permalink: https://www.hzdr.de/publications/Publ-23593
Publ.-Id: 23593


OECD PKL3 Project - Final Report on the ROCOM Tests

Kliem, S.; Franz, R.
In the frame of the OECD PKL 3 Project three groups of experiments have been conducted at the HZDR coolant mixing test facility ROCOM.
The first series concerned the influence of the coolant mixing in the reactor pressure vessel on the Natural Circulation Interruption (NCI). For that purpose boundary conditions (mass flow rates and temperatures in the individual loops at the inlet of the RPV) have been derived for subsequent tests in the ROCOM test facility on coolant mixing inside the pressure vessel. The ROCOM tests were designed to address the fluid/fluid mixing of hot and cold water in the RPV downcomer and in the lower plenum and the temperature distribution at the core inlet. A series of three quasi-stationary experiments was carried out. Boundary conditions were taken from the PKLIII test H4.1 (Schoen, 2014).
The second test series was dedicated to the investigation of the mixing of unborated coolant which is injected into the reactor pressure vessel in the late phase of an accident. It is assumed that the standard sources of the emergency core cooling water are not available. Unborated water is injected to ensure the core cooling. Due to the injection of unborated water, an occurrence of re-criticality in the shut-down reactor is threatening. This possible re-criticality depends in a dominant manner on the mixing of the injected water with the high-borated coolant in the reactor pressure vessel. The ROCOM experiments provided an insight into the mixing and therefore allow drawing corresponding conclusions.
The last series (consisting of one experiment) was on the investigation of the thermal-hydraulic behavior inside the RPV during the ECC-injection from ACCU into the cold leg of loop 1. It is based on the PKLIII test H3.1, which objective was to explore the effectiveness of ECC-injections from ACCU to restore operating conditions of RHRS during the core heat-up phase. The test H3.1 addressed the failure of RHRS under cold shut-down condition with open RCS (RPV closure head removed). Experimental results at the RPV inlet from the PKLIII test H3.1 Run 1 Phase C were used as boundary conditions for the corresponding ROCOM test.
Altogether six ROCOM tests have been conducted within the OECD PKL3 Project.
The current report describes the results of all tests.
  • Article, self-published (no contribution to HZDR-Annual report)
    Helmholtz-Zentrum Rossendorf 2016
    HZDR\FWO\2016\01
    118 Seiten

Permalink: https://www.hzdr.de/publications/Publ-23591
Publ.-Id: 23591


Reduction of Uranium(VI) by isolated, anaerobic microorganisms from the flooding water of the former uranium mine Königstein (Saxony/Germany)

Gerber, U.; Krawczyk-Bärsch, E.; Scheinost, A. C.; Arnold, T.
The former uranium mine Königstein (Saxony, Germany) is currently in the process of remediation. The under-ground is flooded in a controlled way, and the flooding water is cleaned up in an elaborate waste water treat-ment plant. Despite high uranium concentrations up to 13 mg/L and a low pH of 2.9, these waters contain a high microbial diversity as detected by culture-independent methods [1]. Microorganisms are known to interact with metals and radionuclides in different ways [2]. As a result, microorganisms can change the chemical behavior of metals and radionuclides. Anaerobic bacteria which are able to gain energy from the reduction of several metals are known to change the redox state of radionuclides. For instance, anaerobic sulfate-reducing bacteria (SRB) reduce U(VI) to U(IV) and thus change the migration behavior from the more soluble U(VI) into the insoluble U(IV) [3]. For that reason, these anaerobic living bacteria are able to use U(VI) as energy source. Genomic sequence analysis of the flooding water of Königstein revealed the presence of such anaerobic SRB. By culture dependent methods it was possible to isolate anaerobic microorganisms from the flooding water. They were then incubated with 10 mM glycerol using the flooding water as background solution. The uranium concentration was about 13 mg/L. During an incubation time of six weeks the redox potential decreased from 660 mV to 300 mV. After four and six weeks of incubation, the cells were separated from the incubation medium by centrifugation and then analyzed by U-LIII edge EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) measurements. By Iterative Target-Factor Analysis (ITFA) we determined that
100 % of U(VI) was reduced to U(IV). Simultaneously, investigations of the supernatant with UV-vis resulted in the same findings. The results show that naturally occurring anaerobic microorganisms within the flooding water of the former uranium mine Königstein are able to reduce U(VI) to U(IV).


REFERENCES

1. Zirnstein, I., Charakterisierung der mikrobiellen Biozönose im sauren Grubenwasser des ehemaligen Uranbergwerks Königstein, Institut für Ressourcenökologie, Dissertation, 2015, TU Dresden: Dresden.
2. Lloyd, J.R.M., L. E. , Interactions of microorganisms with radionuclides. Elsevier Science. 2002.
3. Lovley, D.R., et al., Enzymatic Iron and Uranium Reduction by Sulfate-Reducing Bacteria. Marine Geology, 1993. 113(1-2): p. 41-53.
Keywords: Uranium, Reduction, Bioremediation, Sulfate-reducing bacteria
  • Lecture (Conference)
    10th International Biometals Symposium, 10.-15.07.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23590
Publ.-Id: 23590


Evidence of uranium uptake in Acidovorax facilis cells by TRLFS and EF-TEM/EELS

Krawczyk-Bärsch, E.; Gerber, U.; Steudtner, R.
For bioremediation of uranium contaminated environments from activities such as uranium mining and uranium processing, microorganisms could be important due to their ability to immobilize radionuclides and heavy met-als. Since the main public concern is the possibility of radionuclide escaping and migrating into groundwater, there is an intense interest in the development of effective remediation methods. The aim is to improve biore-mediation strategies, based on a better understanding of binding mechanisms on the molecular level.

For our studies we used Acidovorax facilis (formerly Pseudomonas facilis), an aerobic Gram-negative Betapro-teobacteria, which is commonly found in soil. Experiments were performed in batch cultures under aerobic con-ditions at 25 °C using nutrient broth. The cells were grown to an optical density (OD600) of around 1.5. For U(VI) biosorption experiments the cultures were washed 2 times with tap water and then resuspended in tap water. After that UO2(NO3)2 was added to the solution to achieve an initial uranium concentration of 0.05 and 0.1 M, respectively, at a neutral pH range. The duration of the sorption experiments were limited to 48 h. As a re-sponse to uranium stress Acidovorax f. were forming extracellular polymeric substances (EPS) resulting in the formation of cell agglomerates. For separating the EPS from the bacteria, the cell agglomerates were ultra-centrifuged (40.000 x g) for 2 h at 10 °C. The cell pellet was used for time-resolved laser fluorescence spectros-copy (TRLFS). The U(VI) luminescence at 274 K was measured after excitation with laser pulses at 266 nm and with an average pulse energy of 300 μJ. The emitted fluorescence light of the cell pellet was recorded using an iHR550 spectrograph and an ICCD camera in the 370 – 670-nm wavelength range by averaging 100 laser pulses and using a gate of 2000 µs. The measured emission spectrum of the pellet is characterized by five emission bands. Their peak maxima were observed at 481.2, 497.8, 519.5, 544.1 and 569.3 nm ± 0.5 nm. In addition, the spectra of the Uranyl-complexes of lipopolysaccharide (R−O−PO3−UO2) and peptidoglycan (R−COO−UO2) were used for comparison. The reference spectra display band positions at 481.5, 498.1, 519.6, 542.9 and 567.5 nm for pH 4 [1] as well as 481.6, 498.1, 518.0, 539.0 and 566.0 nm for pH 4 [2], respectively. They show only a small deviation from those observed in our studies with the best agreement by those of the Uranyl-lipopolysaccharide-complex. Hence, it can be concluded that phosphoryl groups may be the main binding sites for uranyl, located in the lipopolysaccharide Acidovorax f. cells. But, at this moment it is not clear if it is bound on carboxylic functionality groups either.

Acidovorax f. cells were prepared for Energy-filtered transmission electron microscopy (EF-TEM) and electron energy-loss spectroscopy (EELS) by following the routine embedding protocol as described in [3]. The results provide microscopically and spectroscopically evidence of Uranium sorbed at the outer membrane of Acidovorax f. cells by showing high electron density and U ionization intensity peaks. The results support the TRLFS measurements and contribute to a better understanding of the binding mechanisms of U(VI) on Acidovorax f. cells.

[1] Barkleit, A. et al. (2008) Dalton Transaction, 2879–2886.
[2] Barkleit, A. et al. (2009) Dalton Transaction, 5379–5385.
[3] Lünsdorf, H. et al. (2001) Methods in Enzymology 331, 317–331.
Keywords: Uranium, TRLFS, Acidovorax facilis, TEM-EELS
  • Poster
    BioMetals 2016, 10th International Biometals Symposium, 10.-15.07.2016, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-23589
Publ.-Id: 23589


U(VI) reduction by anaerobic microorganisms isolated from the flooding water of the former uranium mine Königstein (Saxony)

Gerber, U.; Röder, G.; Krawczyk-Bärsch, E.; Arnold, T.; Scheinost, A. C.
The former uranium mine Königstein (Saxony, Germany) is currently in the process of remediation. The underground is flooded in a controlled way, and the flooding water is cleaned up in a dedicated waste water treatment plant. Despite high U concentrations up to 13 mg/L and a low pH of 2.9, these waters contain a high microbial diversity as detected by culture-independent methods. Microorganisms are known to interact with metals and radionuclides in different ways [1]. Anaerobic bacteria which are able to gain energy from the reduction of several metals, are known to change the redox state of metals and radionuclides. For instance, anaerobic sulfate-reducing bacteria (SRB) reduce U(VI) to U(IV) and thus change the migration behavior from the more soluble U(VI) into the less soluble U(IV) [2]. Genomic sequence analysis of the flooding water revealed the presence of such anaerobic SRB. By culture-dependent methods it was possible to isolate anaerobic microorganisms from the flooding water. They were incubated with 10 mM glycerol using the flooding water as background medium. During an incubation time of six weeks the redox potential decreased from 660 mV to 300 mV. After four and six weeks of incubation, the cells were separated from the incubation medium by centrifugation and than analyzed by U-LIII edge EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) measurements. By Iterative Target-Factor Analysis (ITFA) we determined that 100 % of U(VI) was reduced to U(IV). Simultaneously, investigations of the supernatant with UV-vis resulted in the same findings. The results show that naturally occurring anaerobic microorganisms within the flooding water of the former uranium mine Königstein are able to reduce U(VI) to U(IV).

1. Lloyd, J.R.M., L. E. , Interactions of microorganisms with radionuclides. Elsevier Science. 2002.
2. Lovley, D.R., et al., Enzymatic Iron and Uranium Reduction by Sulfate-Reducing Bacteria. Marine Geology, 1993. 113(1-2): p. 41-53.
Keywords: Uranium, Reduction, Sulfate-reducing bacteria, Bioremediation
  • Lecture (others)
    5. Workshop - TransAqua, 06.-07.04.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23587
Publ.-Id: 23587


Speciation studies of Rn/Ln with selected degradation products of organic LILW – New spectroscopic insights into the uranyl-acetate system –

Brinkmann, H.; Moll, H.; Arnold, T.
Organic polymers (e.g. cellulose, PVC, bitumen) present in low and intermediate level wastes (LILW) are exposed to ionizing radiation, alkaline pH, and organic degrading microorganisms. This may lead to the formation of smaller, water soluble organic compounds, affecting amongst others the chemical behavior and mobility of radionuclides (RN). In the worst case complexation will lead to an increased mobility and a decreased retention of RN in the barriers of a nuclear waste disposal. Therefore, the characterization of RN complexes with degradation products is necessary for the assessment of the safety and the long-term performance of a nuclear waste repository.
The presentation will give an overview of our planned activities in cooperation with our partners (UNIMAN, SCK·CEN, and UGR) to contribute to task 1.2 of WP 1. Here our focus and expertise lies on the application of different modern spectroscopic tools to directly characterize the speciation of Rn/Ln with organic degradation products and/or with selected microbes, to underpin the findings from UNIMAN and SCK·CEN. Current results obtained by TRLFS, cryo-TRLFS, and UV-vis giving new insights into the uranyl-acetate system will be presented.
Keywords: Uranium, Acetate, TRLFS, UV-vis, MIND
  • Lecture (others)
    MIND Project Annual Meeting 2016, 02.-04.05.2016, Granada, Spain

Permalink: https://www.hzdr.de/publications/Publ-23586
Publ.-Id: 23586


Development of a functional assay for the prediction of NP net removal rates in WWT

Schymura, S.; Hildebrand, H.; Franke, K.
Within recent years the growing application of nanoparticles (NPs) in products of everyday life caused raising concerns about their potential risks for humans and environment. Environmental concentrations of manufactured nanoparticles are predicted to be low, but significant. Key players in regulating NP influx into the environment are wastewater treatment plants (WWTP). The development of removal guidelines and a NP classification based on their likely fate in wastewater treatment (WWT) is mandatory to support WWTP operating companies and regulating agencies.
A potential approach based on suitable functional assays is developed within the project NanoSuppe in cooperation with an US-EPA initialized round robin test with various partners in the US. The idea is to use a simple test program to establish NP affinity coefficients with activated sewage sludge to predict net removal rates during WWT.
Within NanoSuppe, different NPs, such as TiO2, CeO2, MWCNT and Quantum dots, are radiolabeled for easy and highly sensitive detection and employed in batch sorption experiments with activated sludge from a local WWTP. Based on the theory developed by Barton et al., NP affinities for NP hetero-aggregation with the activated sludge are measured from the time-dependent sorption behavior and used as a means of categorizing NP in different groups.
We found that the results of such functional assays depend very much on the experimental setup, such as composition of the dispersion medium (or matrix solution) and consequently NP surface modification (which is to be expected). There is also a significant influence of mixing times and, more dominant, shaking intensity. One of the key parameters is the initial colloidal stability of the NPs in the used media. A suitable procedure that best reflects the situation during WWT is desirable and the predictive strength concerning net removal rates during WWT is to be verified in WWTP model experiments.
Keywords: Nanopartikel, nanoparticle Kläranlage, Wastewater Treatment Plant Heteroaggregation, Heteroaggregation
  • Poster
    Clustertreffen NanoCare, 03.-04.05.2016, Frankfurt am Main, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23585
Publ.-Id: 23585


Polyglycerol-Based Copper Chelators for the Transport and Release of Copper Ions in Biological Environments

Albrecht, R.; Fehse, S.; Pant, K.; Nowag, S.; Stephan, H.; Haag, R.; Tzschucke, C. C.
Here, the synthesis and characterization of three improved nanosystems is presented based on amino functionalized hyperbranched polyglycerol (hPG; M w = 16.8 kDa) as potential copper( II ) chelators. The ligands, N -methyl- N -picolylglycine amide, 2,6-pyridine dicarboxylic acid monoamide, and cyclam tetraacetic acid (TETA) monoamide, are covalently attached to the polymer with amide bonds. In this paper, the Cu( II ) loading capacity, the stability of the Cu( II )- loaded carriers at different pHs, with competing ligands and in human serum, as well as the transport of Cu( II ) in biological systems are investigated. For the fi rst time, a different cytotoxicity of functionalized polymer nanoparticles with and without Cu( II ) is observed. The cyclam-based carrier combines the highest loading capacity (29 Cu ions/nanoparticle), best stability with respect to pH and EDTA (45% remaining Cu after 24 h), lowest cytotoxicity (IC 50 > 100 × 10 −6 M (unloaded), 1500 × 10 −6 M Cu( II ); Cu:carrier 29:1), and the highest stability in human serum.

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Permalink: https://www.hzdr.de/publications/Publ-23584
Publ.-Id: 23584


Direct and Auger electron-induced, single- and double-strand breaks on plasmid DNA caused by 99mTc-labeled pyrene derivatives and the effect of bonding distance

Reissig, F.; Mamat, C.; Steinbach, J.; Pietzsch, H.-J.; Freudenberg, R.; Kotzerke, J.; Wunderlich, G.
It is evident that 99mTc causes radical-mediated DNA damage due to Auger electrons, which were emitted simultaneously with the known γ-emission of 99mTc. We have synthesized a series of new 99mTc-labeled pyrene derivatives with varied distances between the pyrene moiety and the radionuclide. The pyrene motif is a common DNA intercalator and allowed us to test the influence of the radionuclide distance on damages of the DNA helix. In general, pUC 19 plasmid DNA enables the investigation of the unprotected interactions between the radiotracers and DNA that results in single-strand breaks (SSB) or double-strand breaks (DSB). The resulting DNA fragments were separated by gel electrophoresis and quantified by fluorescent staining. Direct DNA damage and radical-induced indirect DNA damage by radiolysis products of water were evaluated in the presence or absence of the radical scavenger DMSO.
We demonstrated that Auger electrons directly induced both SSB and DSB in high efficiency when 99mTc was tightly bound to the plasmid DNA and this damage could not be completely prevented by DMSO, a free radical scavenger. For the first time, we were able to minimize this effect by increasing the carbon chain lengths between the pyrene moiety and the 99mTc nuclide. However, a critical distance between the 99mTc atom and the DNA helix could not be determined due to the significantly lowered DSB generation resulting from the interaction which is dependent on the type of the 99mTc binding motif. The effectiveness of the DNA-binding 99mTc-labeled pyrene derivatives was demonstrated by comparison to non-DNA-binding 99mTcO4–, since nearly all DNA damage caused by 99mTcO4– was prevented by incubating with DMSO.
Keywords: Auger emitter, 99mTc, plasmid DNA, pyrene, direct DNA damage, radiobiology, DNA

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Permalink: https://www.hzdr.de/publications/Publ-23583
Publ.-Id: 23583


Energy Resolution Improvement through Digital Pulse Shape Analysis at CdZnTe-Cross-Strip-Detectors

Weinberger, D.; Fiedler, F.; Kormoll, T.
CdZnTe is a semiconductor material with very good properties for gamma-ray detection. A relatively large band gap of 1.57 eV allows the use at room temperature without any additional cooling. Since holes are nearly immobile compared to electrons in CdZnTe, spectroscopic readout requires special techniques which reduce the depth dependence of the signal. One possibility is to apply an anode pattern which exploits the small pixel effect which induces a signal as the charge cloud is very close to the anode. However, a small current is already induced as the charge cloud travels the bulk. The additional drift current will be accumulated at the charge sensitive preamplifier and influences the base line determination algorithm and results in an additional energy input. We present a simple approach to eliminate the influence of this drift current with the use of pulse shape discrimination implemented in an FPGA of a sampling ADC board. With this algorithm and the known transfer function of the preamplifier a proper depth correction is possible to improve the spectral resolution.
Keywords: CdZnTe , detectors, Energy Resolution Improvement
  • Contribution to proceedings
    2016 IEEE NSS/MIC/RTSD, 29.10.-06.11.2016, Strasbourg, Frankreich
    Proceedings of 2016 IEEE NSS/MIC/RTSD
  • Poster
    2016 IEEE NSS/MIC/RTSD, 29.10.-06.11.2016, Strasbourg, Frankreich

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Permalink: https://www.hzdr.de/publications/Publ-23581
Publ.-Id: 23581


ESR modes in a Strong-Leg Ladder in the Tomonaga-Luttinger Liquid Phase

Zvyagin, S.; Ozerov, M.; Maksymenko, M.; Wosnitza, J.; Honecker, A.; Landee, C. P.; Turnbull, M.; Furuya, S.; Giamarchi, T.
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  • Lecture (Conference)
    APS March Meeting 2016, 14.-18.03.2016, Baltimore, USA

Permalink: https://www.hzdr.de/publications/Publ-23580
Publ.-Id: 23580


Numerical simulation of liquid metal batteries

Weber, N.; Beckstein, P.; Galindo, V.; Herreman, W.; Landgraf, S.; Nore, C.; Stefani, F.; Weier, T.
Considering the increasing deployment of renewable energies, large-scale stationary energy storage will be a key-technology for the future. One potentially ideal grid-scale energy storage system is the liquid metal battery (LMB), consisting of a totally liquid interior. The long life time and abundant raw materials of LMBs offer a very cheap way of building batteries.

Building LMBs cheap means to make them large. Strong currents in the order of kA will drive a fluid flow, which may increase the battery's performance, or lead to a short circuit in the worst case.

A numerial model for describing the MHD fluid flow is presented and used to describe the Tayler instability, electro-vortex flow and interface instabilities in LMBs.
  • Lecture (others)
    Vortrag am Departament de Física Aplicada an der Universitat Politècnica de Catalunya, 26.04.2016, Barcelona, Spanien

Permalink: https://www.hzdr.de/publications/Publ-23578
Publ.-Id: 23578


Open Access-Transformationsinitiative "OA2020"

Reschke, E.
Vorstellung der Open Access Transformationsinitiative OA2020
Keywords: Open Access, OA2020, publication fees, author publication charge, White Paper, DEAL
  • Lecture (others)
    Arbeitskreis Spezialbibliotheken Dresden - Frühjahrstreffen,, 20.04.2016, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-23577
Publ.-Id: 23577


Kerndatensatz Forschung

Reschke, E.
Vorstellung der Kategorien, die sich auf das Publizieren beziehen.
Keywords: Kerndatensatz, Research, Publications
  • Lecture (others)
    Arbeitskreis Spezialbibliotheken Dresden - Frühjahrstreffen, 20.04.2016, Dresden, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-23576
Publ.-Id: 23576


A novel scheme of Compton imaging for nuclear medicine

Pausch, G.; Golnik, C.; Schulz, A.; Enghardt, W.
The paper introduces a novel concept of gamma imaging, the Single-Plane Compton Imager (SPCI). An SPCI is a compact array of scintillation crystals with separate light readouts, arranged for example in a checkerboard configuration. The passive collimation of conventional gamma cameras is replaced by kind of a “soft” electronic collimation derived from the Compton kinematics. In contrast to Compton cameras, where individual scattering angles are determined event-by-event from coincident energy depositions in separate detector planes, the SPCI reconstructs activity distributions from accumulated “conditional” spectra by using Maximum Likelihood Expectation Maximization algorithms. The condition is a coincident energy deposition in two (adjacent) detector elements of a single plane, which occurs most likely due to Compton scattering in one element followed by absorption in the other one. The SPCI could overcome drawbacks of Anger and Compton cameras: (i) Image resolution and detection efficiency are no competing factors. Both improve with increasing detector area. (ii) The fraction of valid events per hit exceeds that of passively collimated systems or Compton cameras by orders of magnitude. (iii) A single detector construction could fit to a wide range of gamma energies. Last not least, optimal SPCI pixels sizes fit with pixel dimensions in PET scanners. SPCI could thus be based on recent detector developments for PET-MRI featuring individual Si-based pixel readouts.
Keywords: Gamma Kamera, Anger Kamera, Compton Kamera, SPECT, Szintillator, Bildgebung, Bildrekonstruktion, MLEM Gamma camera, Anger camera, Compton camera, SPECT, scintillator, imaging, image reconstruction, MLEM
  • Lecture (Conference)
    IEEE Nuclear Science Symposium and Medical Imaging Conference, 28.10.-06.11.2016, Strasbourg, France
  • Contribution to proceedings
    2016 IEEE Nuclear Science Symposium and Medical Imaging Conference, 29.10.-05.11.2016, Strasbourg, France
    2016 IEEE NSS/MIC Conference Record
    DOI: 10.1109/NSSMIC.2016.8069921

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Permalink: https://www.hzdr.de/publications/Publ-23575
Publ.-Id: 23575


Redox dependent interfacial reactivity of hexavalent radionuclides

Hellebrandt, S.; Knope, K. E.; Lee, S. S.; Lussier, A. J.; Stubbs, J. E.; Eng, P. J.; Soderholm, L.; Fenter, P.; Schmidt, M.
A solid comprehension of the geochemical behavior of radionuclides on a molecular level is essential to make reliable long-term predictions about the safety of a nuclear waste repository. The mobility of radionuclides in the environment and thus their hazard potential will also be controlled by the reactivity at the water/mineral interface. In order to understand these processes analytical methods shall ideally be both surface specific and sensitive. X-ray reflectivity techniques, particularly resonant anomalous X-ray reflectivity (RAXR) and crystal truncation rod (CTR) measurements have proved to be a successful combination to investigate geochemical interfacial regimes (Fenter 2002).
Plutonium is one of the most important radionuclides in term of nuclear waste disposal due to its long half-life period and high radiotoxicity. That’s why it has been subject of different studies over the last decades. While these studies could show an enhancement of the mobility of plutonium in the presence of colloidal matter, the formation of Pu(IV)-nanoparticles is still content of ongoing research (Walther & Deneke 2013). Recently, Schmidt et al. suggested a surface-catalyzed formation due to an enhanced concentration of Pu(III) at the surface in equilibrium with a small amount of Pu(IV). Part of the current study was to proof the viability of this mechanism, but also to investigate the interfacial reactivity of Pu’s various oxidation states.
The interaction of UO22+ and PuO22+ with muscovite mica and the effect on the actinides’ different redox properties were investigated using a combination of surface X ray diffraction, alpha spectrometry and grazing-incidence X-ray adsorption near-edge structure (GI-XANES) spectroscopy. Although, U(VI) often is used as a homologue for Pu(VI), this study show a completely different behavior of Pu(VI) and U(VI). Starting with a Pu(VI) solution, Pu(IV)-nanoparticles were formed and adsorbed on the mineral surface. The suggested formation mechanism is similar to that of Pu(III). No such adsorption or nanoparticle formation was observed for U. Our results reveal major differences between Pu and U concerning redox and adsorption behavior, influencing their mobility in the environment. Regarding the prediction of the fate of these contaminants’ in aqueous systems their different interfacial behavior is of importance. This in turn significantly effects the quality of predictions of the allocation of these contaminants in aqueous systems.
  • Lecture (Conference)
    2nd Conference on Key Topics in Deep Geological Disposal, 26.-28.09.2016, Köln, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23574
Publ.-Id: 23574


The microbiology of subsurface, salt-based nuclear waste repositories: Toward a realistic prediction of the microbial effects on repository performance

Swanson, J.; Cherkouk, A.; Bader, M.; Reed, D.
Only two countries in the world—Germany and the United States—currently host nuclear waste facilities in subterranean salt formations, although the concept is gaining traction in other countries, as well. The evaluation of such sites for their feasibility as waste repositories is extensive and multidisciplinary. Microbiology has been one of the weaker areas of investigation, and as a result, there is still uncertainty surrounding the possible effects of microbial activity on salt-based repository performance.
The success of a nuclear waste repository is measured as its ability to prevent the release of radionuclides into the surrounding environment or to limit that release to levels deemed acceptable by the appropriate regulatory agencies and public. Microorganisms are predicted to have diverse effects on nuclear waste repository performance, all of which involve their impact on radionuclide migration. These effects are due to any activities that may affect radionuclide speciation, solubility, or mobility, including 1) complexation with carbonate or organic ligands generated from the breakdown of organic waste; 2) complexation with microbially-generated ligands; 3) creation of a reducing environment through the consumption of oxygen or generation of hydrogen; 4) alteration of pH; 5) redox reactions; and 6) bioassociation that could lead to biocolloid transport.
Because the biogeochemistry of other deep geologic (e.g., granite, clay) settings differs significantly from subterranean salt, it is not possible to extrapolate microbial activity from one site type to the other. However, because of a lack of data, this is precisely what has been done in most safety case scenarios in salt. Thus, performance models assume the worst-case scenario: that the organisms present in rock salt will thrive on the organics present in the radioactive waste, leading to the generation of complexing agents that enhance radionuclide solubility, and that they will take up significant amounts of radionuclides and transport them away from the repository. The goal of current research being conducted by Los Alamos National Laboratory for the Waste Isolation Pilot Plant (WIPP) and by the Helmholtz-Zentrum Dresden-Rossendorf for the German repository concept, is to provide a more realistic view of the potential effects of microorganisms on salt-based nuclear waste repositories.
To reach this goal, both laboratories have been performing coordinated, culture-dependent and independent studies on halite and briny groundwater samples from the Salado Formation (US) and the Zechstein Formation (Germany). Isolates (e.g., Halobacterium sp., putatively noricense,
and others) undergo further investigation into their ability to degrade specific organic waste components (e.g., citrate, cellulose) under repository-relevant conditions and into their potential interactions with waste radionuclides (e.g., uptake, toxicity, and transformation). Results thus far suggest: 1) that the activity of repository-indigenous organisms will be constrained by the projected conditions (brine composition, anoxic atmosphere) and also by the lack of suitable organic substrates but that organisms located in the far-field (overlying briny groundwaters) will not; 2) that some organisms alter brine composition in ways that may affect radionuclide solubility; 3) that the radionuclides present in the waste are inhibitory, but not completely lethal, at their soluble concentrations in repository brine; and 4) that bioassociation of radionuclides appears to differ with oxidation state, organism, and brine composition.
An overview of our current knowledge regarding the microbial impact on salt-based nuclear waste repository performance will be presented and will emphasize the much-needed collaboration between those doing basic halophile research and those applying it in non-routine settings.
  • Lecture (Conference)
    Halophiles 2016, 22.-27.05.2016, San Juan, Puerto Rico

Permalink: https://www.hzdr.de/publications/Publ-23573
Publ.-Id: 23573


The Role of Calcite in Nuclear Waste Disposal Sites

Hellebrandt, S. E.; Hofmann, S.; Jordan, N.; Schmidt, M.
In the safety assessment of nuclear waste disposal sites we have a look on different geochemical processes in the near and far field of a conceivable disposal site. These processes include sorption and incorporation as possibel mechanisms of radionuclide retention in a worst case scenario of an ingress of groundwater. Various minerals in the host rocks as well as primary and secondary phases in the geotechnical barrier were investigated under these conditions elsewhere. Calcite (CaCO3) can be found in every section of the containment and has a couple of features, which makes it interesting for further investigations. A high retention potential because of high sorption capacity as well as the possibility to incorporate guest ions into the crystal lattice at the Ca-ion position is distinctive for calcite [Schmidt 2008, Marques Fernandes 2008]. The long-lived radionuclides (e.g. Plutonium, Curium) determine the long-term radiotoxicity, which defines the considered timespan of the safety analysis. The trivalent radionuclides have an affinity to calcite because of their chemical properties (ionic charge and radius).
To investigate this affinity we conducted different experiments – coprecipitation and batch studies over various periods of time. We can show, that the incorporation of radionuclides and their homologues is dependent on several parameters: i.e. the grain size and specific surface area of calcite, amount and composition of impurities in the calcite and in the background solution. To investigate the structural incorporation we used site-selective timeresolved laser-induced fluorescence spectroscopy with Europium, which serves as a homologue for the trivalent radionuclides because of its great spectroscopic usability [Binnemans 2015] and its similar chemical behavoir. With this method we can distiguish between sorption of the Europium ion onto the calcite surface and incorporation into the crystal bulk by figuring out the amount of water molecules in the first coordination shell of the Europium ion – if there is no water left, incorporation took place. Furthermore we perform X-ray surface diffraction with two high resolution methods, crystal truncation rod and resonant anomalous X-ray-reflectivity. Our experiments were run in situ, which means we have a thin solution film above the crystall. We can demonstrate the influence of different background electolytes (sodium nitrate and sodium iodate) on calcite, which cause a significant surface destabilisation and hence a modification or prevention of sorption and incorporation mechanism. These results are important to examine sorption and structural incorporation on calcite as a process of radionuclide retention in the near and far field of nuclear waste disposal sites.

References
Binnemans, K. (2015): Interpretation of europium(III) spectra. Coord. Chem. Rev., 295, 1-45.
Schmidt, M. et al. (2008): Charge Compensation in Solid Solutions. Angew. Chem., Int. Ed., 47, 5846-5850
Marques Fernandes, M. et al. (2008): Incorporation of trivalent actinides into calcite: A time resolved laser fluorescence spectroscopy (TRLFS) study. Geochim. Cosmochim. Acta, 72, 464-474.
Keywords: Calcite, nuclear waste disposal site
  • Lecture (Conference)
    Key topics in deep geological disposal, 26.-28.09.2016, Köln, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23572
Publ.-Id: 23572


Incorporation of Eu(III) into Calcite under different Recrystallization conditions

Hellebrandt, S. E.; Hofmann, S.; Jordan, N.; Barkleit, A.; Schmidt, M.
Calcite is a ubiquitous mineral in the earth’s crust. Its capacity to incorporate guest ions with similar ionic radius as Ca2+ (e.g. Eu3+, Pu3+, and Am3+) makes it interesting for various environmental issues as well as for safety assessment of nuclear waste disposal sites. Here the trivalent later actinides with long half-lives (like Am and Cm) comprise the most of the long-term radiotoxicity.
For our experiments we used Eu as homologue because of its similar ionic charge and radius and its preferable luminescence properties [1]. We conducted batch studies with three calcite powders, which differ in their specific surface area (SSA) and recrystallization rates (Rr). The speciation of the incorporated Eu(III) was then investigated by site-selective time-resolved laser fluorescence spectroscopy. With increase of the recrystallization rate incorporation occurs faster and the speciation comes to be dominated by one species with its excitation maximum at 578.9 nm. Previous investigations of this process under growth [2] and phase transformation conditions [3] had not identified this species. A long lifetime of ~ 3000 µs demonstrates complete loss of hydration [4], consequently Eu must have been incorporated into the bulk crystal.
The results show a strong dependence of the incorporation kinetics on the recrystallization rate of the different calcites. The predominance of the newly identified species seems to be independent of this kinetic effect, however.
[1] Binnemans (2015) Coord. Chem. Rev. 295, 1-45
[2] Schmidt (2008) Angew. Chem., Int. Ed. 47, 5846-5850
[3] Schmidt (2010) J. Colloid Interface Sci. 351, 50-56
[4] Horrocks (1979) J. Am. Chem. Soc. 101, 334.
Keywords: Calcite, Recristallization, Europium, TRLFS, Incorporation
  • Lecture (Conference)
    Goldschmidt2016, 26.06.-01.07.2016, Yokohama, Japan

Permalink: https://www.hzdr.de/publications/Publ-23571
Publ.-Id: 23571


Evidence of a new Incorporation Species of Eu(III) in Calcite and its dependence of the background electrolyte

Hellebrandt, S. E.; Hofmann, S.; Jordan, N.; Barkleit, A.; Schmidt, M.
Calcite plays a significant role in nuclear waste disposal sites, both as a constituent of geological formations and as a secondary mineral, e.g. upon weathering of concrete. As such it has a direct impact on a repository’s safety and performance. Geochemically, calcite has the potential to adsorb as well as incorporate guest ions with a similar ionic radius, e.g. Eu(III), Pu(III) and Am(III), for Ca(II) in the host lattice. For the safety assessment of nuclear waste disposal sites these trivalent actinides with long half-lives (especially Am) dominate its long-term radiotoxicity and are thus of particular interest.
Schmidt et al. investigated the influence of different dissolved cations on the incorporation process by [1] time-resolved laser fluorescence spectroscopy (TRLFS) with Eu(III)/Cm(III). They could show that there exists a coupled substitution mechanism [Cm(III)/Eu(III) + Na(I) ↔ 2 Ca(II)]. The experiments by Schmidt, et al. were performed under growth conditions, representative of the formation of a secondary phase. Calcite already present as a constituent of the host rock, however, would be more likely to interact with the contaminants at, or very close to equilibrium. Under these conditions its reactivity will be governed by its recrystallization rate, and different interaction mechanism – and consequently different contaminant speciation – may be expected.
For our experiments we used Eu as homologue because of its similar ionic charge and radius, as well as its desirable luminescence properties [2]. We conducted batch studies with calcite powder in calcite saturated solutions with NaCl or KCl as background electrolyte. The speciation of the incorporated Eu(III) was then investigated by site-selective time-resolved laser fluorescence spectroscopy (TRLFS). The speciation of both systems is dominated by a species with its excitation maximum at 578.9 nm, which had not been identified in previous investigations of this process under growth [1] and phase transformation conditions [3]. A long lifetime of ~ 4000 µs demonstrates complete loss of hydration [4], consequently Eu must have been incorporated into the bulk crystal. The corresponding emission spectrum shows the maximum splitting pattern implying a low symmetry of the ligand field surrounding Eu(III)[2]. After 1 month reaction time the excitation spectrum of the calcite in contact with NaCl shows a strongly blue-shifted excitation spectrum compared to the same calcite with KCl, demonstrating the effect of the background electrolyte on the Eu(III) speciation. As the peak at 579.3 nm belongs to a sorption species, this indicates enhanced incorporation in NaCl background relative to the KCl system. This may indicate that also under recrystallization conditions coupled substitution of Eu(III) and Na(I) for two Ca(II) is required for incorporation. Incorporation remains a significant interaction mechanism in the KCl system, likely due to a considerable amount of naturally occurring Na in the calcite
The results show, that the speciation of Eu(III) in calcite depends on the conditions of its incorporation, i.e. growth versus recrystallization. A hitherto unknown incorporation has been identified, and our results strongly suggest incorporation under recrystallization conditions strongly depends on the availability of Na(I).
[1] M. Schmidt, Angew. Chem., Int. Ed. 2008, 47, 5846-5850.
[2] K.Binnemans, Coord. Chem. Rev. 2015,295, 1-45.
[3] M. Schmidt, J. Colloid Interface Sci. 2010, 351, 50-56.
[4] W. DeW. Horrocks, Jr., J. Am. Chem. Soc. 1979, 101, 334-340.
Keywords: Calcite, TRLFS, Europium, Incorporation
  • Poster
    Ninth international conference on nuclear and radiochemistry - NRC9, 29.08.-02.09.2016, Helsinki, Finland

Permalink: https://www.hzdr.de/publications/Publ-23570
Publ.-Id: 23570


Porting the Plasma Simulation PIConGPU to Heterogeneous Architectures with Alpaka

Zenker, E.; Widera, R.; Juckeland, G.; Worpitz, B.; Hübl, A.; Knüpfer, A.; Nagel, W. E.; Bussmann, M.
We discuss our experience on porting the CUDA-based plasma simulation code PIConGPU to heterogeneous platforms using the abstract kernel interface Alpaka. With the advent of next-generation architectures such as OpenPower, the full use of the hardware and the mapping of CPUs and GPUs to specific simulation tasks has become important. Performance portability is of great interest, but even more important is the ability to develop against a single interface to keep code testable and maintainable. We show how we can make use of the Alpaka library in real-world applications and how we achieve portability and performance.
Keywords: Supercomputing & HPC, Computational Physics, Performance Optimization
  • Lecture (Conference)
    GPU Technology Conference, 04.-07.04.2016, San Jose, California, USA

Permalink: https://www.hzdr.de/publications/Publ-23569
Publ.-Id: 23569


Speciation of trivalent actinides and lanthanides in body fluids

Barkleit, A.; Wilke, C.; Heller, A.; Ikeda-Ohno, A.; Stumpf, T.
In case of incorporation into the human body, radionuclides potentially represent serious health risks due to their chemo- and radiotoxicity. In order to assess their toxicological behavior, such as transport, metabolism, deposition, and elimination from the human organisms, the understanding of their in vivo chemical speciation on a molecular level is crucial. Due to their high specific radioactivity with very long half-lives, trivalent actinides (An(III)) are considered to be some of the problematic radionuclides particularly in the geological repository of radioactive wastes. The reliable safety and health assessment of the waste repositories requires the information about the behavior of An(III) in vivo. Nevertheless, little is known about the speciation of not only An(III) but also trivalent lanthanides (Ln(III)), non-radioactive chemical analogs of An(III), in body fluids.
In order to improve our understanding of the behavior of An(III) and Ln(III) in the human body, the present study focuses on the chemical speciation of An(III) and Ln(III) in the gastrointestinal tract. The human gastrointestinal system was simulated by using an in vitro digestion model, which was developed by Oomen et al. [1] and is the basis of an international unified bioaccessibility protocol [2]. To verify the model, natural human saliva samples were included in the speciation investigation. Because An(III) and Ln(III) are excreted mainly by the kidney [3, 4], their speciation in natural human urine was investigated to complete the metabolic pathway from oral ingestion through the digestive system till elimination.
The speciation of curium(III) (Cm(III)) and europium(III) (Eu(III)) in the gastrointestinal tract as well as in human natural saliva and urine has been studied by means of time-resolved laser-induced fluorescence spectroscopy (TRLFS). The standard model body fluids and the natural saliva and urine samples were spiked in vitro with Cm(III) and Eu(III) in trace metal concentrations.
The dominant chemical species in the human saliva was identified by a comparison of the natural human sample spectra with reference spectra obtained for synthetic saliva and individual components of the body fluid. Linear combination fitting analysis on the sample spectra indicates the formation of 60-90% inorganic- and 10-40% organic species of Cm(III)/Eu(III) in the salivary media. Ternary M(III) complexes containing phosphate and carbonate anions with the additional counter-cation calcium are formed as the main inorganic species. Complexes with the digestive enzyme α-amylase and the protein mucin (to a minor extent) represent the major part of the organic species.
When the M(III) reached the stomach, the metal complexes were dissociated due to the high acidic conditions. That is, Cm(III) and Eu(III) are mainly present as the aqua ion, and only a small part (about 20%) is coordinated by the protein pepsin. When entering the intestine the metal ions are strongly bound by the protective protein mucin and inorganic ligands (mainly carbonate and phosphate).
After transporting into the bloodstream and transformation into the urine via the kidney, the speciation of the metal ions strongly depends on the pH of the urine. When the pH is slightly acidic, the formation of Cm(III) and Eu(III) citrate complex dominates, whereas ternary complexes with phosphate and calcium as the main ligands and the additional participation of citrate and/or carbonate occur at around near-neutral pH [5].
These speciation studies in different body fluids pointed out that An(III) and Ln(III) are coordinated by both inorganic and organic molecules in the human body. Proteins (e.g. α-amylase, pepsin, mucin) would be the important organic binding partners. Furthermore, ternary inorganic complexes containing phosphate and carbonate anions with the additional counter-cation calcium are expected to be formed as the main inorganic species in almost all the body fluids.
References
[1] Oomen, A. G., Rompelberg, C. J. M., Bruil, M. A., Dobbe, C. J. G., Pereboom, D. P. K. H., Sips, A. J. A. M., Arch. Environ. Contam. Toxicol. 44, 281-287 (2003).
[2] Wragg, J., Cave, M., Taylor, H., Basta, N., Brandon, E., Casteel, S., Gron, C., Oomen, A., van de Wiele, T., British Geological Survey Open Report OR/07/027, Keyworth, Nottingham, 90 pp. (2009).
[3] Menetrier, F., Taylor, D. M., and Comte, A., Appl. Radiat. Isot. 66, 632–647 (2008).
[4] Taylor, D. M., Leggett, R. W., Radiat. Prot. Dosim. 105, 193–198 (2003).
[5] Heller, A., Barkleit, A., Bernhard, G., Chem. Res. Toxicol. 24, 193-203 (2011).
  • Poster
    9th International Conference on Nuclear and Radiochemistry NRC9, 29.08.-02.09.2016, Helsinki, Finland

Permalink: https://www.hzdr.de/publications/Publ-23568
Publ.-Id: 23568


Chemical speciation of An(III) and Ln(III) in human saliva

Barkleit, A.; Wilke, C.; Heller, A.; Stumpf, T.; Ikeda-Ohno, A.
In case of incorporation into the human body, radionuclides potentially represent serious health risks due to their chemo- and radiotoxicity. In order to assess their toxicological behavior, such as transport, metabolism, deposition, and elimination from the human organisms, the understanding of their in vivo chemical speciation on a molecular level is crucial. Due to their high specific radioactivity with very long half-lives, trivalent actinides (An(III)) are considered to be some of the problematic radionuclides particularly in the geological repository of radioactive wastes. The reliable safety and health assessment of the waste repositories requires the information about the behavior of An(III) in vivo. Nevertheless, little is known about the speciation of not only An(III) but also trivalent lanthanides (Ln(III)), non-radioactive chemical analogs of An(III), in body fluids.
In order to improve our understanding of the behavior of An(III) and Ln(III) in the human body, the present study focuses on the chemical speciation of An(III) and Ln(III) in saliva. Saliva is one of the most important body fluids to understand the behavior of these metals in the digestive system, as it is the very first contact medium in the human body in case of oral ingestion.
We report the first speciation study of curium(III) and europium(III) in human saliva by means of time-resolved laser-induced fluorescence spectroscopy (TRLFS). For TRLFS measurements, fresh saliva samples from humans have been spiked in vitro with Cm(III) or Eu(III). The dominant chemical spe-cies in the human saliva was identified by a comparison of the sample spectra with reference spectra obtained for synthetic saliva and individual components of the body fluid. Linear combination analysis on the sample spectra indicates the formation of about 60-90% inorganic- and 10-40% organic species of Cm(III)/Eu(III) in the salivary media. A ternary M(III) complex containing phosphate and carbonate anions with the additional counter-cation calcium is formed as the main inorganic species. Complexes with α-amylase and mucin (to a minor extent) represent the major part of the organic species. Thermodynamic calculation of the speciation, based on the recently determined stability constants for Cm(III) and Eu(III) complexes with α-amylase, also supports the experimentally determined speciation.
  • Poster
    10th International Biometals Symposium (Biometals 2016), 10.-15.07.2016, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-23567
Publ.-Id: 23567


An online, energy-resolving beam profile detector for laser-driven proton beams

Metzkes, J.; Zeil, K.; Kraft, S. D.; Karsch, L.; Sobiella, M.; Rehwald, M.; Obst, L.; Schlenvoigt, H.-P.; Schramm, U.
In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two spatial dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ~4mm and up to 9 energy ranges can be resolved with an energy resolution of ~1 MeV above 8 MeV proton energy. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energy can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source as well as the first detector application at a laser-driven proton source.
Keywords: laser-driven proton acceleration, scintillator-based online detectors

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Permalink: https://www.hzdr.de/publications/Publ-23566
Publ.-Id: 23566


Performance-Portable Many-Core Plasma Simulations: Porting PIConGPU to OpenPower and Beyond

Zenker, E.; Widera, R.; Hübl, A.; Juckeland, G.; Knüpfer, A.; Nagel, W. E.; Bussmann, M.
With the appearance of the heterogeneous platform OpenPower, many-core accelerator devices have been coupled with Power host processors for the first time. Towards utilizing their full potential, it is worth investigating performance portable algorithms that allow to choose the best-fitting hardware for each domain-specific compute task. Suiting even the high level of parallelism on modern GPGPUs, our presented approach relies heavily on abstract meta-programming techniques, which are essential to focus on fine-grained tuning rather than code porting. With this in mind, the CUDA-based open-source plasma simulation code PIConGPU is currently being abstracted to support the heterogeneous OpenPower platform using our fast porting interface cupla, which wraps the abstract parallel C++11 kernel acceleration library Alpaka.

We demonstrate how PIConGPU can benefit from the tunable kernel execution strategies of the Alpaka library, achieving portability and performance with single-source kernels on conventional CPUs, Power8 CPUs and NVIDIA GPUs.
Keywords: OpenPower, heterogeneous computing, HPC, C++11, CUDA, OpenMP, particle-in-cell, platform portability, performance portability
  • Contribution to proceedings
    International Workshop on OpenPower co-located with ISC High Performance, 23.06.2016, Frankfurt, Germany
    Lecture Notes in Computer Science, Vol. 9945, 293-301
    DOI: 10.1007/978-3-319-46079-6_21

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Permalink: https://www.hzdr.de/publications/Publ-23565
Publ.-Id: 23565


Alpaka - An Abstraction Library for Parallel Kernel Acceleration

Zenker, E.; Worpitz, B.; Widera, R.; Hübl, A.; Juckeland, G.; Knüpfer, A.; Nagel, W. E.; Bussmann, M.
Porting applications to new hardware or programming models is a tedious and error prone process. Every help that eases these burdens is saving developer time that can then be invested into the advancement of the application itself instead of preserving the status-quo on a new platform.

The Alpaka library defines and implements an abstract hierarchical redundant parallelism model. The model exploits parallelism and memory hierarchies on a node at all levels available in current hardware. By doing so, it allows to achieve platform and performance portability across various types of accelerators by ignoring specific unsupported
levels and utilizing only the ones supported on a specific
accelerator. All hardware types (multi- and many-core CPUs, GPUs and other accelerators) are supported for and can be programmed in the same way.
The Alpaka C++ template interface allows for straightforward extension of the library to support other accelerators and specialization of its internals for optimization.

Running Alpaka applications on a new (and supported) platform requires the change of only one source code line instead of a lot of #ifdefs.
Keywords: Heterogeneous computing, HPC, C++, CUDA, OpenMP, platform portability, performance portability
  • Contribution to proceedings
    The Sixth International Workshop on Accelerators and Hybrid Exascale Systems co-located with the 30th IEEE International Parallel & Distributed Processing Symposium, 23.-27.05.2016, Chicago Hyatt Regency Chicago, Illinois, USA
    Proceedings of the 30th IEEE International Parallel and Distributed Processing Symposium

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Publ.-Id: 23564


Spectroscopic studies on the interaction of europium(III) and curium(III) with components of the human mucosa

Wilke, C.; Barkleit, A.; Ikeda-Ohno, A.; Stumpf, T.
Lanthanide and actinide elements are exogenous metals, which have no essential role in normal biochemistry. Through different processes such as nuclear accidents, these heavy metals could be potentially released into the environment where they could be further incorporated eventually into the food chain and furthermore into the human gastrointestinal tract through oral ingestion. Because of their potential chemical- and radiotoxicity, it is important to understand their chemical and biological behavior in the human body. The digestive system is covered by a thick, viscoelastic mucosa membrane, which is a protective barrier to pathogens and toxic substances. The protective response in mucosa relies largely on the glycoprotein mucin. A previous spectroscopic screening with TRLFS (Time-Resolved Laser-Induced Fluorescence Spectroscopy) revealed mucin as a fundamental binding partner of Eu(III) as well as of Cm(III) in the human gastrointestinal tract. Based on these previous results, the present study focuses on this protein and its components to investigate its binding behavior with Eu(III) and Cm(III) as representatives of Ln(III) and An(III), respectively.
Keywords: lanthanides, actinides, Eu(III), Cm(III), TRLFS, spectroscopy, mucin
  • Contribution to proceedings
    Biometals - 10th International Biometals Symposium, 10.-15.07.2016, Dresden, Deutschland
    Proceedings of Biometals
  • Lecture (Conference)
    Biometals - 10th International Biometals Symposium, 10.-15.07.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23563
Publ.-Id: 23563


Dynamical properties of the sine-Gordon quantum spin magnet Cu-PM at zero and finite temperature

Tiegel, A. C.; Honecker, A.; Pruschke, T.; Ponomaryov, A.; Zvyagin, S. A.; Feyerherm, R.; Manmana, S. R.
The material copper pyrimidine dinitrate (Cu-PM) is a quasi-one-dimensional spin system described by the spin-1/2 XXZ Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions. Based on numerical results obtained by the density-matrix renormalization group, exact diagonalization, and accompanying electron spin resonance (ESR) experiments we revisit the spin dynamics of this compound in an applied magnetic field. Our calculations for momentum and frequency-resolved dynamical quantities give direct access to the intensity of the elementary excitations at both zero and finite temperature. This allows us to study the system beyond the low-energy description by the quantum sine-Gordon model. We find a deviation from the Lorentz invariant dispersion for the single-soliton resonance. Furthermore, our calculations only confirm the presence of the strongest boundary bound state previously derived from a boundary sine-Gordon field theory, while composite boundary-bulk excitations have too low intensities to be observable. Upon increasing the temperature, we find a temperature-induced crossover of the soliton and the emergence of new features, such as interbreather transitions. The latter observation is confirmed by our ESR experiments on Cu-PM over a wide range of the applied field.

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Publ.-Id: 23562


Comparison Between the Magnetic Irreversibility and Zero Resistance of High-Quality Melt-Processed YBaCuO Superconductors

Dias, F. T.; Vieira, V. D. N.; Wolff-Fabris, F.; Kampert, E.; Hneda, M.; Schaf, J.; Farinela, G. F.; Gouvea, C. D.; Rovira, J. J. R.
This paper portrays a detailed study of the magnetic irreversibility limit Tirr (H) and of the zero resistance point Tc0 (H) of three different top-seeding melt-textured YBa2Cu3O7−δ superconducting samples, with well-aligned c-axis and doped with a high density of nonsuperconducting Y2Ba1Cu1O5 (Y211) pinning centers. We have performed measurements for applied magnetic fields up to 140 kOe and for the whole set of the different field–current configurations. The magnetization measurements were performed using an MPMS-XL SQUID magnetometer and a vibrating sample magnetometer, both from Quantum Design. The electric transport measurements were made using a physical properties measurement system from Quantum Design. The goal of this exhaustive study is obtaining precise data about magnetic flux mobility along the various directions in the sample for the different field–current configurations, thereby defining the nature and effects, due to the strength and anisotropy of the pinning mechanisms and disclosing the various physical mechanisms dissipating electric transport in these systems below the superconducting transition temperature. We discuss our results in terms of the anisotropic flux pinning by the Y211 grains dispersed into the superconducting matrix.

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Publ.-Id: 23561


Electron spin resonance in a strong-rung spin-1/2 Heisenberg ladder

Ponomaryov, A. N.; Ozerov, M.; Zviagina, L.; Wosnitza, J.; Povarov, K. Y.; Xiao, F.; Zheludev, A.; Landee, C.; Cizmar, E.; Zvyagin, A. A.; Zvyagin, S. A.
Cu(C8H6N2)Cl2, a strong-rung spin-1/2 Heisenberg ladder compound, is probed by means of electron spin resonance (ESR) spectroscopy in the field-induced gapless phase above Hc1. The temperature dependence of the ESR linewidth is analyzed in the quantum field theory framework, suggesting that the anisotropy of magnetic interactions plays a crucial role, determining the peculiar low-temperature ESR linewidth behavior. In particular, it is argued that the uniform Dzyaloshinskii-Moriya interaction (which is allowed on the bonds along the ladder legs) can be the source of this behavior in Cu(C8H6N2)Cl2.

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Permalink: https://www.hzdr.de/publications/Publ-23560
Publ.-Id: 23560


Tunnelling magnetoresistance of the half-metallic compensated ferrimagnet Mn2RuxGa

Borisov, K.; Betto, D.; Lau, Y. C.; Fowley, C.; Titova, A.; Thiyagarajah, N.; Atcheson, G.; Lindner, J.; Deac, A. M.; Coey, J. M. D.; Stamenov, P.; Rode, K.
Tunnel magnetoresistance ratios of up to 40% are measured between 10K and 300K when the highly spin-polarized compensated ferrimagnet, Mn2RuxGa, is integrated into MgO-based perpendicular magnetic tunnel junctions. Temperature and bias dependences of the tunnel magnetoresistance effect, with a sign change near −0.2 V, reflect the structure of the Mn2RuxGa interface density of states. Despite magnetic moment vanishing at a compensation temperature of 200K for x ≈ 0.8, the tunnel magneto resistance ratio remains non-zero throughout the compensation region, demonstrating that the spin-transport is governed by one of the Mn sub-lattices only. Broad temperature range magnetic field immunity of at least 0.5T is demonstrated in the same sample. The high spin polarization and perpendicular magnetic anisotropy make Mn2RuxGa suitable for applications in both non-volatile magnetic random access memory cells and terahertz spin-transfer oscillators.
Keywords: Tunneling Magnetoresistance, Half-Metal, Mn-based alloys, MRAM, Spin Polarisation, Heusler alloy, Ferrimagnetic, Perpendicular Magnetic Anisotropy

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Permalink: https://www.hzdr.de/publications/Publ-23559
Publ.-Id: 23559


Dual-energy CT-based assessment of patient tissue variability and its influence on particle therapy planning

Wohlfahrt, P.; Möhler, C.; Negwer, F.; Troost, E.; Enghardt, W.; Greilich, S.; Richter, C.
The accuracy of particle therapy is currently limited by uncertainties in range prediction using a heuristic conversion from CT number to stopping-power ratio (SPR). The clinical application of dual-energy CT (DECT) contributes to reduce CT-related uncertainties and to quantify the influence of tissue variability on SPR prediction. DECT offers the opportunity to provide a patient-specific CT-number-to-SPR prediction. Based on routinely used DECT patient scans, this study shows differences between adults and children, which has to be clinically regarded.
  • Lecture (Conference)
    47. Jahrestagung der Deutschen Gesellschaft für Medizinische Physik (DGMP) e. V., 07.-10.09.2016, Würzburg, Deutschland

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Publ.-Id: 23558


Cooperative effects of adsorption, reduction, and polymerization observed for hexavalent actinides on the muscovite basal plane

Hellebrandt, S.; Knope, K. E.; Lee, S. S.; Lussier, A. J.; Stubbs, J. E.; Eng, P. J.; Soderholm, L.; Fenter, P.; Schmidt, M.
Reliable long-term predictions about the safety of a potential nuclear waste repository must be based on a sound, molecular-level comprehension of the geochemical behavior of the radionuclides. Especially, their reactivity at the water/mineral interface will control their mobility and thus hazard potential.1 Understanding the geochemical behavior of plutonium has been particularly challenging, due to its multitude of accessible oxidation states and its capability to form nanoparticles or eigencolloids. Despite the generally accepted importance of Pu(IV)-nanoparticles for Pu’s chemical4-6 and environmental behavior,2, 3, 7, 8 the mechanism of their formation is still the subject of ongoing research.9 Several previous studies have identified Pu(IV) nanoparticles to be the final state of adsorbed Pu, starting from both higher10-12 and lower oxidation states,13 on both redox active10, 12 and redox inactive substrates.11, 13 In our own previous work we suggested a mechanism, in which the enhanced concentration of Pu(III) at the interface, in combination with the presence of minor quantities of Pu(IV) in equilibrium, drives the formation of these nanoparticles in an effectively surface-catalyzed reaction.13 This mechanism would be independent of Pu’s initial oxidation state assuming there is adequate amounts of Pu(IV) present in equilibrium. In order to be able to understand these processes analytical techniques that allow selectively probing the mineral/water interface and elucidating processes at the interface under in situ conditions are required. X-ray reflectivity techniques, such as crystal truncation rod (CTR) measurements and resonant anomalous x-ray reflectivity (RAXR) have proven to be valuable tools for geochemical studies concerning reactions in the interfacial regime14, especially for complex reactions of the actinides.13, 15
To further elucidate the interfacial reactivity of Pu in its various oxidation states, and to test the viability of the mechanisms discussed above for Pu(III), we study the reactivity of hexavalent PuO22+ at the muscovite (001) basal plane and compare it to the behavior of ostensibly analogous UO22+ ([Pu] = 0.1 mmol L-1, [U] = 1 mmol L-1, pH = 3.2 ± 0.2, I(NaCl) = 0.1 mol L-1) using resonant anomalous X-ray reflectivity (RAXR) and crystal truncation rods (CTR), as well as grazing-incidence X-ray adsorption near-edge structure (GI-XANES) spectroscopy and alpha spectrometry. The RAXR data indicate that adsorbed Pu has a broad distribution that extends up to 60 Å from the surface. Independent quantification of the adsorption of Pu by alpha spectrometry finds a coverage of 8.3 Pu/AUC (where AUC = 46.72 Ų is the surface unit cell area). The observed broad structure and large coverage cannot be explained by ionic adsorption of PuO22+, indicating adsorption of Pu(IV) oxo nanoparticles. GI-XANES confirms that most Pu at the interface was tetravalent. These observations corroborate a redox-partner independent mechanism for the interfacial formation of Pu(IV) oxo nanoparticles put forward previously. Uranium exhibits clearly different behavior. No discernible RAXR signal was detected, indicating no adsorption of UO22+. GI-XANES and alpha spectrometry also showed very weak signal, in agreement with the RAXR findings, and in the case of GI-XANES indicating predominantly hexavalent U. Our results reveal significant differences between Pu and U in terms of mineral uptake, greatly impacting their geochemical mobility and potentially useful for predicting the fate of these contaminants’ in the aqueous environment.

1. H. Geckeis, J. Lützenkirchen, R. Polly, T. Rabung and M. Schmidt, Chemical Reviews, 2013, 113, 1016-1062.
2. A. B. Kersting, D. W. Efurd, D. L. Finnegan, D. J. Rokop, D. K. Smith and J. L. Thompson, Nature, 1999, 397, 56-59.
3. A. P. Novikov, S. N. Kalmykov, S. Utsunomiya, R. C. Ewing, F. Horreard, A. Merkulov, S. B. Clark, V. V. Tkachev and B. F. Myasoedov, Science, 2006, 314, 638-641.
4. L. Soderholm, P. M. Almond, S. Skanthakumar, R. E. Wilson and P. C. Burns, Angewandte Chemie-International Edition, 2008, 47, 298-302.
5. K. E. Knope and L. Soderholm, Chemical Reviews, 2012, 113, 944-994.
6. V. Neck, M. Altmaier and T. Fanghänel, Comptes Rendus Chimie, 2007, 10, 959-977.
7. R. J. Silva and H. Nitsche, Radiochimica Acta, 1995, 70/71, 377-396.
8. A. B. Kersting, Inorganic Chemistry, 2013, 52, 3533-3546.
9. C. Walther and M. A. Denecke, Chemical Reviews, 2013, 113, 995-1015.
10. R. Kirsch, D. Fellhauer, M. Altmaier, V. Neck, A. Rossberg, T. Fanghänel, L. Charlet and A. C. Scheinost, Environmental Science & Technology, 2011, 45, 7267-7274.
11. A. E. Hixon, Y. Arai and B. A. Powell, Journal of Colloid and Interface Science, 2013, 403, 105-112.
12. A. E. Hixon and B. A. Powell, Environmental Science & Technology, 2014, 48, 9255-9262.
13. M. Schmidt, S. S. Lee, R. E. Wilson, K. E. Knope, F. Bellucci, P. J. Eng, J. E. Stubbs, L. Soderholm and P. Fenter, Environmental Science & Technology, 2013, 47, 14178-14184.
14. P. Fenter, Reviews in Mineralogy and Geochemistry, 2002, 49, 149-220.
15. M. Schmidt, S. Hellebrandt, K. E. Knope, S. S. Lee, J. E. Stubbs, P. J. Eng, L. Soderholm and P. Fenter, Geochimica et Cosmochimica Acta, 2015, 165, 280-293.
Keywords: sorption, nanoparticles, muscovite, plutonium, uranium, x-ray reflectivity, CTR, RAXR
  • Lecture (Conference)
    Ninth International Conference on Nuclear and Radiochemistry - NRC9, 29.08.-02.09.2016, Helsinki, Finnland

Permalink: https://www.hzdr.de/publications/Publ-23557
Publ.-Id: 23557


Fate of Plutonium at a Former Nuclear Testing Site in Australia

Ikeda-Ohno, A.; Shahin, L. M.; Howard, D.; Collins, R. N.; Payne, T. E.; Johansen, M. P.
A series of the British nuclear tests conducted on mainland Australia between 1953 and 1963 dispersed long-lived radioactivity and nuclear weapons debris, the legacy of which is a long-lasting source of radioactive contamination to the surrounding biosphere. A reliable assessment of the environmental impact of these types of radioactive contaminants and their implications for human health requires an understanding of their physical/chemical characteristics on the molecular scale. However, mainly due to the technical difficulties associated with the chemical diversity of environmental samples, these contaminants have never been characterized adequately. In this study, we identify the chemical form of plutonium (Pu), one of the most problematic radionuclides dispersed, in the local soils collected from one of the former weapons test sites, Maralinga. We herein reveal the first direct spectroscopic evidence that the Pu legacy exists as particulates of fine Pu oxyhydroxide compounds, a very concentrated and low-soluble form of Pu, which will serve as ongoing radioactive sources far into the future. We also verify that the Pu in the particles originated in the so-called “Minor trials” that involved the dispersal of weapon components by highly explosive chemicals, not in the nuclear explosion tests called “Major trials”. The obtained results help us to understand the chemical transformation of the original Pu materials dispersed in the semi-arid environment more than fifty years ago. These findings further highlight the importance of the comprehensive physical/chemical characterization of Pu contaminants for reliable environmental- and radiotoxicological assessment, which is significantly influenced by the original physical/chemical form of the contaminant.
Keywords: Plutonium, Nuclear weapons tests, Environmental contamination, Characterisation, Synchrotron, X-ray fluorescence microscopy, X-ray absorption spectroscopy

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Publ.-Id: 23556


Metal pad roll instability in liquid metal batteries

Weber, N.; Beckstein, P.; Galindo, V.; Stefani, F.; Weier, T.; Herreman, W.; Nore, C.
Considering the increasing deployment of renewable energies, large-scale stationary energy storage will be a key-technology for the future. One potentially ideal grid-scale energy storage system is the liquid metal battery (LMB), consisting of a totally liquid interior. The long life time and abundant raw materials of LMBs offer a very cheap way of building batteries.

Building LMBs cheap means to make them large. Strong currents in the order of kA will drive a fluid flow, which may increase the battery's performance, or lead to a short circuit in the worst case.

A numerial model for describing the MHD fluid flow is presented and used to describe the Tayler instability, electro-vortex flow and interface instabilities in LMBs.
Keywords: simulation OpenFOAM liquid metal battery
  • Contribution to proceedings
    10th PAMIR International Conference: Fundamental and Applied MHD, 20.06.2016, Cagliari, Italien

Permalink: https://www.hzdr.de/publications/Publ-23555
Publ.-Id: 23555


Statistical Hadronization Model analysis of hadron yields in p+Nb and Ar+KCl at SIS18 energies

Agakishiev, G.; Arnold, O.; Balanda, A.; Belver, D.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Böhmer, M.; Boyard, J. L.; Cabanelas, P.; Castro, E.; Chernenko, S.; Destefanis, M.; Dohrmann, F.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Finocchiaro, P.; Fonte, P.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzon, J. A.; Gernhäuser, R.; Gilardi, C.; Göbel, K.; Golubeva, M.; Gonzalez-Diaz, D.; Guber, F.; Gumberidze, M.; Heinz, T.; Hennino, T.; Holzmann, R.; Ierusalimov, A.; Iori, I.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Koenig, I.; Koenig, W.; Kolb, B. W.; Kornakov, G.; Kotte, R.; Krasa, A.; Krizek, F.; Krücken, R.; Kuc, H.; Kühn, W.; Kugler, A.; Kurepin, A.; Ladygin, V.; Lalik, R.; Lange, J. S.; Lang, S.; Lapidus, K.; Lebedev, A.; Liu, T.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michalska, B.; Mihaylov, D.; Michel, J.; Moriniere, E.; Mousa, J.; Müntz, C.; Münzer, R.; Naumann, L.; Pachmayer, Y. C.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Rehnisch, L.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schmah, A.; Schuldes, H.; Schwab, E.; Siebenson, J.; Sobolev, Y. G.; Spataro, S.; Spruck, B.; Ströbele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Trebacz, R.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Weber, M.; Wendisch, C.; Wirth, J.; Wisniowski, M.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y.
The HADES data from p+Nb collisions at a center of mass energy of sqrt(sNN)= 3.2 GeV are analyzed employing a statistical hadronization model. The model can successfully describe the production yields of the identified hadrons π0, η, Λ, K0s, ω with parameters Tchem = (99+-11) MeV and μb = (619+-34) MeV, which fits well into the chemical freeze-out systematics found in heavy-ion collisions. In addition, we reanalyze our previous HADES data from Ar+KCl collisions at sqrt(sNN= 2.6 GeV with an updated version of the model. We address equilibration in heavy-ion collisions by testing two aspects: the description of yields and the regularity of freeze-out parameters from a statistical model fit. Despite this success, the model fails to describe the observed Ξ- yields in both, p+Nb and Ar+KCl. Special emphasis is put on feed-down contributions from higher-lying resonance states as a possible explanation for the observed excess.

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Permalink: https://www.hzdr.de/publications/Publ-23554
Publ.-Id: 23554


Synthesis and kinetic characterisation of water-soluble fluorogenic acyl donors for transglutaminase 2

Wodtke, R.; Schramm, G.; Pietzsch, J.; Pietsch, M.; Löser, R.
Small glutamate-containing peptides that bear coumarin derivatives as fluorescent leaving groups attached to the gamma-carboxylic group of the Glu residue were synthesised and investigated towards their potential to act as substrates for transglutaminase 2 (TGase 2). Their synthesis was accomplished by an efficient solid-phase approach. The excellent water solubility of the compounds enabled their extensive kinetic characterisation regarding TGase 2-catalysed hydrolysis and aminolysis. The influence of the substitution pattern at the coumarin skeleton on the kinetic properties was studied. Derivatives containing 7-hydroxy-4-methylcoumarin (HMC) revealed superior properties over their 7-hydroxycoumarin counterparts; analogous amides are not accepted as substrates. Z-Glu(HMC)-Gly-OH, which exhibited the most optimal substrate properties among the investigated derivatives, was selected for the exemplary kinetic characterisation of acyl acceptor substrates and irreversible inhibitors.
Keywords: enzyme assays, inhibitors, reactive peptides, solid-phase synthesis, transferases

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Permalink: https://www.hzdr.de/publications/Publ-23553
Publ.-Id: 23553


A Python-based interface for batch processing of image reconstruction jobs for Philips PET systems

Maus, J.; Schramm, G.; Oehme, L.; Hofheinz, F.; Petr, J.; van den Hoff, J.
Ziel/Aim:
Retrospective manual processing of large amounts of patient data is time consuming and error prone. This is especially true for repeated image reconstructions since the vendor software usually does not allow batch processing. To overcome this limitation we have developed a batch processing interface for our Philips PET system that is also suitable for application in a clinical context.
Methodik/Methods:
We have used Python3 to develop a framework that allows to run reconstructions with vendor-provided protocols and to modify parameters beforehand. The framework includes functions to list patient studies, run/abort a reconstruction, copy patient data from/to servers and to modify incorrectly entered parameters like injection time or dose. The framework targets current Philips PET systems. It has been tested with a Ingenuity-TF PET/MR system consisting of a EBW workstation and PRS+CIRS recon servers. In addition to basic image reconstruction tasks the framework also allows to add custom user defined data processing. In our case we added a MR-based attenuation segmentation algorithms as well as amplitude-based respiratory gating methods which we developed in-house. Furthermore, to facilitate the use by clinical staff the framework also comes with PyQt5-based graphical user interface.
Ergebnisse/Results:
The framework transparently interacts with the recon servers of the vendor. Images reconstructed with both interfaces were verified to be identical. MR-based attenuation segmentation and respiratory gating were also validated. The framework can be used in batch processing environments either via direct use of the implemented functions, the supplied command-line tools or via the graphical user interface.
Schlussfolgerungen/Conclusions:
The developed framework/tools are compatible with all common Philips PET systems and greatly facilitates reprocessing of large amounts of patient data.
  • Poster
    54. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 20.-23.04.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23552
Publ.-Id: 23552


Relationship between asphericity of FDG uptake in the primary tumor and prognostic molecular signatures in NSCLC

Apostolova, I.; Kalinski, T.; Ego, K.; Steffen, I. G.; Furth, C.; Buchert, R.; Derlin, T.; Hofheinz, F.; Amthauer, H.
Ziel/Aim:
Asphericity (ASP) is a novel FDG-PET-based tumor heterogeneity measure which quantitatively characterizes the deviation of the tumor’s metabolic volume from sphere shape. In order to understand its biological correlates we investigated the relationship with molecular signatures known to be prognostic in NSCLC.

Methodik/Methods:
The study included 84 consecutive patients (18 females, 66.4±8.8 years) with newly diagnosed NSCLC in whom FDG-PET/CT had been performed prior to therapy. Primary tumor resection specimens and core biopsies were used for basic histopathology and determination of the Ki-67 proliferation index. EGFR status, VEGF, p53 and ALK expression were obtained in a subgroup of 44 patients. The FDG PET image of the primary tumor was delineated by an automatic algorithm based on adaptive thresholding accounting for local background. ASP and SUVmax were considered as quantitative PET measures.

Ergebnisse/Results:
Ki-67 correlated with SUVmax (Spearman rho=0.325, p=0.002) as well as with ASP (rho=0.232, p=0.018). Both correlations were considerably stronger in adenocarcinomas than in squamous cell carcinomas. Multivariate logistic regression of Ki-67 included only ASP. Neither SUVmax nor ASP correlated with p53. ASP but not SUVmax was associated with VEGF (AUC=0.789, p=0.024) and showed a tendency towards association with EGFR positivity (AUC=0.722, p=0.065). All tumors were ALK negative. Univariate Cox regression revealed progression free survival (PFS) to be associated with stage (p=0.004) and ASP (p<0.001). Overall survival (OS) was associated with stage (p=0.001), Ki-67 (p=0.008), and ASP (p<0.001). Multivariate Cox regression included ASP (p=0.001) and stage (p=0.044) for PFS, but only ASP (p=0.015) for OS.

Schlussfolgerungen/Conclusions:
Molecular signatures of proliferation and angiogenesis seem to contribute to asphericity of primary lung tumors.
  • Poster
    54. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-23.04.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23551
Publ.-Id: 23551


Asphericity of somatostatin receptor expression in SPECT/CT as a predictor of response to PRRT in neuroendocrine neoplasms

Wetz, C.; Apostolova, I.; Hofheinz, F.; Steffen, I. G.; Kupitz, D.; Ruf, J.; Furth, C.; Amthauer, H.
Ziel/Aim:
To assess the value of the lesion's spatial heterogeneity, quantified as asphericity (ASP), of somatostatin receptor (SSR)–expression to predict response to peptide receptor radionuclide therapy (PRRT) in patients with metastatic, SSR positive gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN).

Methodik/Methods:
From 06/2011 to 05/2013 all GEP-NEN-patients who obtained pretherapeutic In-111-DTPA-Octreotid (Octreoscan®) prior to Lu-177-DOTATATE-PRRT were retrospectively enrolled in this study. SPECT/CT of thorax and abdomen was performed on Discovery NM/CT670, GE. SSR expression in 20 NEN patients (m, n=14; f, n=6; age 54-87, mean 72.6 years) was qualitatively and quantitatively assessed by measuring Krenning Score, a metastases to liver uptake ratio (M/L ratio) and ASP. Response to PRRT was evaluated on lesion basis using RECIST 1.1 and lesion were classified as responding (RL (SD, PR, CR); n=57) and non-responding (NRL (PD); n=20). The value of Krenning Score, M/L ratio and ASP for response prediction was compared by using mann-whitney-u-test and receiver-operating-curves (ROC).

Ergebnisse/Results:
77 NEN metastases (liver n=40; lymph-node n=24; bone n=11; pancreas n=2) showed SSR expression. Higher ASP was significantly associated with poorer response (PD: 10.35±1.09; SD: 2.88±0.36; PR: 1.73±0.49, CR: 0.66±0.18; p<0.001). ROC-analyses revealed the highest ROC for discrimination between RL and NRL for ASP (AUC 0.96, p<0.001) followed by Krenning Score (AUC 0.85, p<0.001) and M/L ratio (AUC 0.82, p<0.001).The best cut-off value for ASP was <5.12 (sensitivity and specificity, 90% and 93%).

Schlussfolgerungen/Conclusions:
ASP of somatostatin expression in pretherapeutic SPECT/CT seems to be a helpful parameter to predict response to PRRT on a lesion basis in patients with metastatic NEN.
  • Poster
    54. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-23.04.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23550
Publ.-Id: 23550


Novel radioligands for cyclic nucleotide phosphodiesterase imaging with positron emission tomography: An update on developments since 2012

Schröder, S.; Wenzel, B.; Deuther-Conrad, W.; Scheunemann, M.; Brust, P.
Cyclic nucleotide phosphodiesterases (PDEs) are a class of intracellular enzymes that inactivate the secondary messenger molecules, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Thus, PDEs regulate the signaling cascades mediated by these cyclic nucleotides and affect fundamental intracellular processes. Pharmacological inhibition of PDE activity is a promising strategy for treatment of several diseases. However, the role of the different PDEs in related pathologies is not completely clarified yet. PDE-specific radioligands enable non-invasive visualization and quantification of these enzymes by positron emission tomography (PET) in vivo and provide an important translational tool for elucidation of the relationship between altered expression of PDEs and pathophysiological effects as well as (pre-)clinical evaluation of novel PDE inhibitors developed as therapeutics. Herein we present an overview of novel PDE radioligands for PET published since 2012.
Keywords: Positron emission tomography; phosphodiesterases; cyclic nucleotide signaling; PDE inhibitors; PDE radioligands; imaging

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Permalink: https://www.hzdr.de/publications/Publ-23549
Publ.-Id: 23549


The TurbEFA Field Experiment - Measuring the Influence of a Forest Clearing on the Turbulent Wind Field

Queck, R.; Bernhofer, C.; Bienert, A.; Schlegel, F.
Abstract Forest ecosystems play an important role in the interaction between the land surface and the atmosphere. Measurements and modelling efforts have revealed significant uncertainties in state-of-the-art flux assessments due to spatial inhomogeneities in the air-flow and land surface. Here, a field experiment is used to describe the turbulent flow across a typical Central European forest clearing. A three-dimensional model of the inhomogeneous forest stand was developed using an innovative approach based on terrestrial laser-scanner technology. The comparison of the wind statistics of two measurement campaigns (5 and 12 months long) showed the spatial and temporal representativeness of the ultrasonic anemometer measurements within the canopy. An improved method for the correction of the vertical velocity enables the distinction between the instrumental offsets and the vertical winds due to the inclination of the instrument. Despite a 13 % fraction of deciduous plants within the otherwise evergreen canopy, the effects of phenological seasons on the velocity profiles were small. The data classified according to the wind speed revealed the intermittent nature of recirculating air in the clearing. Furthermore, the development of sub-canopy wind-speed maxima is explained by considering the velocity moments and the momentum equation (including measurements of the local pressure gradient). Clearings deflect the flow downward and feed the sub-canopy flow, i.e., advective fluxes, according to wind speed and, likely, clearing size, whereas local pressure gradients play an important role in the development of sub-canopy flow. The presented dataset is freely available at the project homepage.
Keywords: Forest inhomogeneity, Metström, Momentum balance, Turbulence measurements, Vegetation model

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Publ.-Id: 23548


Contactless inductive flow tomography in the presence of electromagnetic brakes

Ratajczak, M.; Wondrak, T.; Martin, R.; Stefani, F.
The contactless inductive flow tomography (CIFT) is a measurement technique that reconstructs the global flow structure of an electrically conducting fluid. This works by applying a magnetic field, measuring the flow-induced perturbations of that field outside the vessel and solving the underlying inverse problem. A promising candidate for the application of CIFT is continuous casting of steel, for which online information of the mould flow could be vitally important to control the casting process with electromagnetic brakes (EMBr). We demonstrate that CIFT magnetic field measurements in the presence of EMBr's are possible in the laboratory scale using gradiometric induction coil sensors and choosing an appropriate excitation frequency.
Keywords: contactless inductive flow tomography, continuous casting of steel, gradiometric sensor, magnetic field measurement, electromagnetic brake
  • Contribution to proceedings
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia
  • Lecture (Conference)
    10th PAMIR International Conference -- Fundamental and Applied MHD, 20.-24.06.2016, Cagliari, Italia

Permalink: https://www.hzdr.de/publications/Publ-23546
Publ.-Id: 23546


Acoustic signatures of the phases and phase transitions in Yb2Ti2O7

Bhattacharjee, S.; Erfanifam, S.; Green, E. L.; Naumann, M.; Wang, Z.; Granovsky, S.; Doerr, M.; Wosnitza, J.; Zvyagin, A. A.; Moessner, R.; Maljuk, A.; Wurmehl, S.; Büchner, S.; Zherlitsyn, S.
We report on measurements of the sound velocity and attenuation in a single crystal of the candidate quantum-spin-ice material Yb2Ti2O7 as a function of temperature and magnetic field. The acoustic modes couple to the spins magnetoelastically and, hence, carry information about the spin correlations that sheds light on the intricate magnetic phase diagram of Yb2Ti2O7 and the nature of spin dynamics in the material. Particularly, we find a pronounced thermal hysteresis in the acoustic data with a concomitant peak in the specific heat indicating a possible first-order phase transition at about 0.17 K. At low temperatures, the acoustic response to magnetic field saturates hinting at the development of magnetic order. The experimental data are consistent with a first-order phase transition from a cooperative paramagnet to a ferromagnet below T ≈ 0.17 K, as shown by fitting the data with a phenomenological mean-field theory.

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Publ.-Id: 23545


Optimized small animal tumor model for the radiobiological characterization of low energy laser accelerated protons

Beyreuther, E.; Brüchner, K.; Baumann, M.; Gotz, M.; Karsch, L.; Krause, M.; Leßmann, E.; Schmidt, M.; Schürer, M.; Pawelke, J.
There is no abstract
  • Poster
    NCRO Retreat, 14.-16.04.2016, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-23544
Publ.-Id: 23544


Zinc Influence on the Formation and Properties of Pt/Mg(Zn)AlO x Catalysts Synthesized From Layered Hydroxides

Belskaya, O. B.; Stepanova, L. N.; Gulyaeva, T. I.; Erenburg, S. B.; Trubina, S. V.; Kvashnina, K.; Nizovskii, A. I.; Kalinkin, A. V.; Zaikovskii, V. I.; Bukhtiyarov, V. I.; Likholobov, V. A.
Layered double hydroxides (LDH) containing Al3+, Mg2+ and Zn2+ cations in a ratio of Zn/(Mg+Zn) = 0, 0.05, 0.1, 0.2, 0.5, 0.7 and 1.0 were synthesized. The effect of zinc content on the phase composition of LDH and on the structural parameters, textural characteristics and acid-base properties of the corresponding mixed oxides were studied. This type of supports was used to obtain non-acid platinum catalysts Pt/Mg(Zn)AlOx. The formation of supported platinum particles, their composition, dispersion and electronic state were examined by means of TPR, TEM, XPS and EXAFS. The possibility to obtain bimetallic PtZn particles, whose structure and strength of interaction with the support depend on the zinc content of the support, was demonstrated. It was found that the presence of zinc atoms in the platinum environment decreases the particle size of active metal and stabilizes platinum in the active metallic state that ensures high activity of the catalyst in dehydrogenation of propane at a selectivity for propylene above 99%.
Keywords: zinc containing layered double hydroxides, platinum catalysts, propane dehydrogenation, XPS, EXAFS

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Publ.-Id: 23543


Modelling horizontal two-phase flows using generalized models

Höhne, T.; Porombka, P.
Stratified two-phase flows are relevant in many industrial applications, e.g. pipelines, horizontal heat exchangers and storage tanks. The numerical simulation of free surface flows can be performed using phase-averaged multi-fluid models, like the homogeneous and the two-fluid approaches, or non-phase-averaged variants. The approach shown in this paper within the two-fluid framework is the Algebraic Interfacial Area Density (AIAD) model. It allows the macroscopic blending between different models for the calculation of the interfacial area density and improved models for momentum transfer in dependence on local morphology. A further step of improvement of modelling the turbulence is the consideration of sub-grid wave turbulence (SWT) that means waves created by Kelvin-Helmholtz instabilities that are smaller than the grid size. A first CFD validation of the approach is performed by means of experimental data of horizontal adiabatic stratified flow from the HAWAC and WENKA facilities. More verification and validation of the approach is necessary – more CFD grade experimental data are required for the validation.
Keywords: CFD, AIAD, HAWAC, WENKA

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Publ.-Id: 23542


Validation of turbulence parameters at the interface of horizontal multiphase flows

Höhne, T.
Stratified two-phase flows are relevant in many industrial applications, e.g. pipelines, horizontal heat exchangers and storage tanks. The numerical simulation of free surface flows can be performed using phase-averaged multi-fluid models, like the homogeneous and the two-fluid approaches, or non-phase-averaged variants. The approach shown in this paper within the two-fluid framework is the Algebraic Interfacial Area Density (AIAD) model. It allows the macroscopic blending between different models for the calculation of the interfacial area density and improved models for momentum transfer in dependence on local morphology. A further step of improvement of modelling the turbulence was the consideration of sub-grid wave turbulence (SWT) that means waves created by Kelvin-Helmholtz instabilities that are smaller than the grid size. A first CFD validation of the approach was done for an adiabatic case of the HAWAC channel. More verification and validation of the approach is necessary – more CFD grade experimental data are required for the validation.
Keywords: Multiphase flow, AIAD, CFD, HAWAC
  • Contribution to proceedings
    ICMF-2016 – 9th International Conference on Multiphase Flow, 22.-27.05.2016, Florenz, Italien
    CD-ROM
  • Lecture (Conference)
    ICMF-2016 – 9th International Conference on Multiphase Flow, 22.-27.05.2016, Florenz, Italien

Permalink: https://www.hzdr.de/publications/Publ-23541
Publ.-Id: 23541


IAEA CRP benchmark of ROCOM BORON DILUTION and PTS test cases for the use of CFD in reactor design

Höhne, T.; Kliem, S.
Over the last 15 years, considerable effort has been expended in assembling the available information on the use of CFD in the nuclear reactor safety field. Typical application areas here are heterogeneous mixing and heat transfer in complex geometries, buoyancy-induced natural and mixed convection, etc., with specific reference to NRS accident scenarios such as Pressurized Thermal Shock (PTS), boron dilution, hydrogen build-up in containments, thermal fatigue and thermal striping issues, etc.
The nuclear industry now also recognizes that CFD codes have reached the desired level of maturity for them to be used as part of the NPP design process, and it is the objective of a IAEA CRP to assess the current capabilities of such codes in this regard, and contribute to the technology advance in respect to their verification and validation. The development, verification and validation of CFD codes in respect to NPP design necessitates further work on the complex physical modelling processes involved, and on the development of efficient numerical schemes needed to solve the basic equations.
Therefore, two sets of ROCOM CFD-grade test data were made available to set up an IAEA benchmark, relating to boron dilution (pump start-up) and Pressurized Thermal Shock (PTS) scenarios. The first experiment deals with boron dilution scenarios during start-up of the first coolant pump. The second benchmark deals with the injection of the relatively cold Emergency Core Cooling (ECC) water which can induce buoyancy-driven stratification
The Benchmark activities will help to analyse the CFD code capabilities for CFD in nuclear reactor design applications.
Keywords: CFD, ROCOM, IAEA
  • Contribution to proceedings
    Computational Fluid Dynamics for Nuclear Reactor Safety Applications - CFD4NRS-6, 13.-15.09.2016, Cambrigde, USA
    CD-ROM
  • Lecture (Conference)
    Computational Fluid Dynamics for Nuclear Reactor Safety Applications - CFD4NRS-6, 13.-15.09.2016, Cambrigde, USA

Permalink: https://www.hzdr.de/publications/Publ-23540
Publ.-Id: 23540


Multimodal Somatostatin Receptor Theranostics Using [64Cu]Cu-/[177Lu]Lu-DOTA-(Tyr3)octreotate and AN-238 in a Mouse Pheochromocytoma Model.

Ullrich, M.; Bergmann, R.; Peitzsch, M.; Zenker, E.; Cartellieri, M.; Bachmann, M.; Ehrhart-Bornstein, M.; Block, N.; Schally, A.; Eisenhofer, G.; Bornstein, S.; Pietzsch, J.; Ziegler, C.
Pheochromocytomas and extra-adrenal paragangliomas (PHEO/PGLs) are rare catecholamine-producing chromaffin cell tumors. For metastatic disease, no effective therapy is available. Overexpression of somatostatin type 2 receptors (SSTR2) in PHEO/PGLs promotes interest in applying therapies using somatostatin analogs linked to radionuclides and/or cytotoxic compounds, such as [(177)Lu]Lu-DOTA-(Tyr(3))octreotate (DOTATATE) and AN-238. Systematic evaluation of such therapies for the treatment of PHEO/PGLs requires sophisticated animal models. In this study, the mouse pheochromocytoma (MPC)-mCherry allograft model showed high tumor densities of murine SSTR2 (mSSTR2) and high tumor uptake of [(64)Cu]Cu-DOTATATE. Using tumor sections, we assessed mSSTR2-specific binding of DOTATATE, AN-238, and somatostatin-14. Therapeutic studies showed substantial reduction of tumor growth and tumor-related renal monoamine excretion in tumor-bearing mice after treatment with [(177)Lu]Lu-DOTATATE compared to AN-238 and doxorubicin. Analyses did not show agonist-dependent receptor downregulation after single mSSTR2-targeting therapies. This study demonstrates that the MPC-mCherry model is a uniquely powerful tool for the preclinical evaluation of SSTR2-targeting theranostic applications in vivo. Our findings highlight the therapeutic potential of somatostatin analogs, especially of [(177)Lu]Lu-DOTATATE, for the treatment of metastatic PHEO/PGLs. Repeated treatment cycles, fractionated combinations of SSTR2-targeting radionuclide and cytotoxic therapies, and other adjuvant compounds addressing additional mechanisms may further enhance therapeutic outcome.
Keywords: neuroendocrine tumors, catecholamines, DOTATATE, PET, SPECT, optical in vivo imaging, doxorubicin

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Publ.-Id: 23539


First-in-man incorporation dosimetry of (S)-(-)-[18F]fluspidine

Sattler, B.; Kranz, M.; Wuest, N.; Patt, M.; Meyer, P.; Deuther-Conrad, W.; Fischer, S.; Wuensch, B.; Brust, P.; Sabri, O.
Objectives: (S)-(-)-[18F]fluspidine has been pre-clinically proven to be a distinctive radioligand for imaging 1-receptors with PET [1]. In this study, the biokinetics was studied first in man. To assess the radiation risk, the biodistribution, organ doses (OD) and the effective dose (ED) were determined.
Methods: Whole body dosimetry was performed in 4 healthy volunteers (2m, 2f; age: 22.5±2.7y weight: 62.5±8.4.5kg). They were sequentially PET/CT-imaged up to 7h post i.v. injection of 264±17 MBq, 8 bed positions (BP) per frame, 1.5 to 6 min/BP, followed by CT-attenuation correction and iterative reconstruction. All micturated urine was collected up to 7 hours post injection. Urine was weighed and samples measured for radioactivity concentration [Bq/ccm] in a well counter. All relevant organs were defined by volumes of interest. Exponential curves were fitted to the time-activity-data (%ID/organ). The ODs were calculated using the stylized adult male model as implemented in OLINDA v1. The ED was calculated using tissue weighting factors as published in ICRP60 and 103.
Results: The highest OD [µSv/MBq] was received by the liver (76.0±17.7), the gall bladder wall (60.7±10.6) and the small intestine (56.9±10.6). The highest contribution to the ED [µSv/MBq] was by the stomach wall (3.8±0.4), the lungs (3.4±0.3) and the liver (3.0±0.4). The conversion factor [µSv/MBq] to estimate the ED to humans is 22.1±1.3 (ICRP60) and 21.0±1.3 (ICRP103), respectively.
Conclusions: The effective dose was calculated to be 6.3 mSv/300MBq. This is in the order of magnitude as for other 18F-labeled PET-compounds. The results provide a rationale for further clinical study phases and the development of this tracer as a clinical tool for PET imaging 1-receptors.
References:
[1] Brust P, Deuther-Conrad W, Becker G, Patt M, Donat CK, Stittsworth S, Fischer S, Hiller A, Wenzel B, Dukic-Stefanovic S, Hesse S, Steinbach J, Wunsch B, Lever SZ, and Sabri O (2014) Distinctive in vivo kinetics of the new sigma1 receptor ligands (R)-(+)- and (S)-(-)-18F-fluspidine in porcine brain. J Nucl Med 55[10], 1730-1736.
  • Poster
    Annual Meeting of the Society of Nuclear Medicine, 10.-15.06.2016, San Diego, USA
  • Abstract in refereed journal
    Journal of Nuclear Medicine 57(2016)2, 10P

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Publ.-Id: 23538


Gender differences in color processing in mice as revealed with functional PET

Kranz, M.; Njemanze, P.; Amend, M.; Wehrl, H.; Brust, P.
OBJECTIVES: Color processing is a central component of mammalian vision. Noninvasive functional transcranial Doppler ultrasound has recently revealed gender-related differences of color processing which include right hemisphere pattern for Blue/Yellow chromatic opponency by men while a left hemisphere pattern was found for women. In the present study, 18F-FDG was used to investigate a similar paradigm in mice with functional PET.
METHODS: Ten anaesthetized CD-1 mice were repeatedly injected on different days with 12 MBq 18F-FDG and subjected in random order to separate monocular stimulation of the left and right eye with white, blue and yellow lights, respectively, for 20 min. A gelatin-(Wratten)-filters-containing chromatoscope was specially designed for that purpose. Subsequently a whole body T1 weighted MR (gradient echo sequence) was performed for anatomical orientation. The SUV of 18F-FDG was determined at 27.5, 32.5, 37.5 and 42.5 min p.i. in the whole cortex and in the left and right visual cortex. Data were analyzed with MANOVA and t-test.
RESULTS: Male mice have significantly higher SUV than female mice in the cortical area, right and left visual cortex in dark baseline condition and during stimulation with white, blue and yellow lights through the right eye but not left (Table). In male mice, the change in SUV was responsive to Blue/Yellow pairs, while in female mice, the response was only to Blue. In male mice, the SUV was highest during Blue stimulation in the left visual cortex through the right eye compared to right visual cortex. Similarly, the SUV was highest during Yellow stimulation in the left visual cortex through the right eye compared to the right visual cortex. Conversely, in female mice, the SUV was highest during Blue stimulation in the right visual cortex through the left eye compared to left visual cortex (Figure). In female mice, there was no change during stimulation with Yellow.
CONCLUSION: The observation in mice is opposite to that in humans where right hemisphere cognitive style for Blue/Yellow opponency was found in men, but a left hemisphere style in women. It is postulated, that the ontogenetic and phylogenetic evolutionary trends for cerebral dominance for color underwent a change during mammalian evolution to humans, perhaps related to left hemisphere dominance for language in most subjects.
  • Poster
    Annual Meeting of the Society of Nuclear Medicine, 10.-15.06.2016, San Diego, USA
  • Abstract in refereed journal
    Journal of Nuclear Medicine 57(2016)2, 141P

Permalink: https://www.hzdr.de/publications/Publ-23537
Publ.-Id: 23537


Preclinical PET/MR: Defining novel roles for phosphodiesterase 10A in brain and brown adipose tissue (BAT) in the regulation of energy homeostasis

Kranz, M.; Hankir, M. K.; Wagner, S.; Deuther-Conrad, W.; Teodoro, R.; Fenske, W. K.; Brust, P.
OBJECTIVES: Phosphodiesterase type 10A (PDE10A) is highly enriched in the striatum and a potential therapeutic target for brain diseases. It is suggested that PDE10A is also involved in the regulation of food intake. By using the novel selective radioligand 18F-AQ28A [1] we evaluated expression of PDE10A in brain and BAT of lean, diet-induced (DIO) and genetically obese mice. As BAT activation could be visualized by using small animal PET/MR using 18F-FDG [2], we also assessed whether inhibition of PDE10A modulates BAT activity.
METHODS: Female CD1 and C57BL/6 mice were studied with either 18F-AQ28A or 18F-FDG. After anesthesia (1.8% isoflurane in 60%O2/40% air) and i.v injection of the tracer, a 1 h PET/MR scan was done for all groups. After image coregistration volumes of interest were created for striatum, hypothalamus, interscapular BAT and skeletal muscle. The selectivity of 18F-AQ28A towards PDE10A was proven by baseline (n=3) and blocking (n=3) experiments with the PDE10A inhibitor MP-10. DIO in CD1 mice was achieved by 16 weeks free access to a high-fat, high-sugar diet. Leptin-deficient ob/ob C57BL/6 mice (n=5) were used as a genetic model of obesity. The first set of CD1 mice (n=10) was divided into lean (n=5) and DIO (n=5) and received 18F-AQ28A. A second group (n=10) of lean CD1 mice were fasted and housed overnight under thermoneutral conditions and received either i.p. injection of MP-10 (n=5) or vehicle (n=5) followed 30 min later by i.v. injection of FDG. After a recovery period, the second group received either an i.p. injection of MP-10 (n=5) or vehicle (n=5) and 2 h later were sacrificed and BAT, hypothalamus and striatum were collected. Relative mRNA expression of PDE10A and thermoregulatory genes in BAT and neuropeptides in striatum and hypothalamus as well as the indirect neuronal activity marker Fos were analyzed by real-time quantitative PCR.
RESULTS: Blocking with MP-10 showed selectivity of 18F-AQ28A towards PDE10A (SUV15min striatum blocking/baseline: 0.54±0.08/1.02±0.19; p<0.01). A 7-fold higher mRNA expression of PDE10A in striatum compared to hypothalamus was found (p<0.001). In lean mice, 18F-AQ28A showed selective symmetrical accumulation in BAT (SUV55min: 0.44±0.04) with low uptake in the adjacent skeletal muscle (SUV55min: 0.20±0.02; p<0.01). Higher PDE10A levels (p<0.05) in striatum and BAT were found for DIO (SUV15min:1.36±0.10 / SUV55min:0.82±0.08) and for ob/ob mice (SUV15min:1.91±0.08 / SUV55min:0.77±0.04) compared to normal weight mice. Acute administration of MP-10 to lean mice resulted in significantly higher FDG uptake by BAT (SUV55min: 0.40±0.01) compared to vehicle administration (SUV55min: 0.25±0.02; p<0.01) and an increase in Pgc1alpha (2-fold), Ucp1 (1.6-fold) and Cidea (1.6-fold) mRNA expression (p<0.01, p<0.05 and p<0.05, respectively) was found. In striatum, acute administration of MP-10 increased expression of Fos (4-fold) and preproenkephalin (2.9-fold) (p<0.0001 and p<0.05 respectively) whereas in hypothalamus there were no changes in gene expression found.
CONCLUSION: A novel thermoregulatory role for PDE10A was demonstrated and related to obesity. PDE10A selectively regulates gene expression in striatum. The data suggest that PDE10A inhibitors offer the potential to treat obesity by increasing thermogenesis and reducing hedonic feeding through recruiting BAT and striatal circuits.
  • Lecture (Conference)
    Annual Meeting of the Society of Nuclear Medicine 2016, 11.-15.06.2016, San Diego, USA
  • Abstract in refereed journal
    Journal of Nuclear Medicine 57(2016)2, 200P

Permalink: https://www.hzdr.de/publications/Publ-23536
Publ.-Id: 23536


Varying Chirality Across Nicotinic Acetylcholine Receptor Subtypes: Selective Binding of Quinuclidine Triazole Compounds

Sarasamkan, J.; Scheunemann, M.; Apaijai, N.; Palee, S.; Parichatikanond, W.; Arunrungvichian, K.; Fischer, S.; Chattipakorn, S.; Deuther-Conrad, W.; Schüürmann, G.; Brust, P.; Vajragupta, O.
The novel quinuclidine anti-1,2,3-triazole derivatives T1-T6 were designed based on the structure of QND8. The binding studies revealed that the stereochemistry at the C3 position of the quinuclidine scaffold plays an important role in the nAChR subtype selectivity. Whereas the (R)-enantiomers are selective to α7 over α4β2 (by factors of 44-225) and to a smaller degree over α3β4 (3-33), their (S)-counterparts prefer α3β4 over α4β2 (62-237) as well as over α7 (5-294). The (R)-derivatives were highly selective to α7 over α3β4 subtypes compared to (RS)- and (R)-QND8. The (S)-enantiomers are 5−10 times more selective to α4β2 than their (R) forms. The overall strongest affinity is observed for the (S)-enantiomer binding to α3β4 (Ki, 2.25-19.5 nM) followed by their (R)-counterpart binding to α7 (Ki, 22.5-117 nM), with a significantly weaker (S)-enantiomer binding to α4β2 (Ki, 414-1980 nM) still above the very weak respective (R)-analogue affinity (Ki, 5059-10436 nM).
Keywords: Nicotinic acetylcholine receptor, positron emission tomography, quinuclidine anti-1,2,3-triazole, click chemistry

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Publ.-Id: 23535


Prediction and compensation of magnetic beam deflection in MR-integrated proton therapy: A method optimized regarding accuracy, versatility and speed

Schellhammer, S. M.; Hoffmann, A. L.
The integration of magnetic resonance imaging (MRI) and proton therapy for on-line image-guidance is expected to reduce dose delivery uncertainties during treatment. However, the proton beam experiences a Lorentz force induced deflection inside the magnetic field of the MRI scanner, and several methods have been proposed to quantify this effect. We analyze their structural differences and compare results of both analytical and Monte Carlo models. We find that existing analytical models are limited in accuracy and applicability due to critical approximations, especially including the assumption of a uniform magnetic field. As Monte Carlo simulations are too time-consuming for routine treatment planning optimization and on-line plan adaption, we introduce a new method to quantify and correct for the beam deflection, which is optimized regarding accuracy, versatility and speed. We use it to predict the trajectory of a mono-energetic proton beam of energy E0 traversing a water phantom behind an air gap within an omnipresent uniform transverse magnetic flux density B0. The magnetic field induced dislocation of the Bragg peak is calculated as function of E0 and B0 and compared to results obtained with existing analytical and Monte Carlo methods. The deviation from the Bragg peak position predicted by Monte Carlo simulations is smaller for the new model than for the analytical models by up to 2 cm. The model is faster than Monte Carlo methods, less assumptive than the analytical models and applicable to realistic magnetic fields. To compensate for the Bragg peak dislocation, a numerical optimization strategy is introduced and evaluated. It includes an adjustment of both the proton beam entrance angle and the energy of up to 25° and 5 MeV, depending on E0 and B0. This strategy is shown to effectively reposition the BP to its intended location in the presence of a magnetic field.
Keywords: proton therapy, image-guided radiotherapy, IGPT, magnetic resonance imaging, MR guidance, beam trajectory prediction

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Publ.-Id: 23534


The strange implications of electron-electron scattering in graphene

Helm, M.; König-Otto, J. C.; Mittendorff, M.; Pashkin, A.; Schneider, H.; Winnerl, S.; Wendler, F.; Winzer, T.; Malic, E.; Knorr, A.
Electron-electron scattering in graphene gives rise to some unexpected behavior in the electron dynamics, as observed by pump-probe measurements.
When excited with a near-infrared femtosecond laser pulse, the pump-probe signal depends on the angle between the linear polarization of the pump and the probe pulse, which is due to preferential excitation of electrons perpendicular to the laser electric field. This indicates an anisotropic distribution function in momentum space that is preserved by electron-electron scattering, since it mainly occurs collinearly along the Dirac cone. Only after 150 fs the distribution function is rendered isotropic through optical-phonon scattering. The effect is even more pronounced when exciting at small photon energies (88 meV), below the optical-phonon energy: In this case the anisotropic distribution function survives for as long as 5 ps, when it is finally thermalized by non-collinear Coulomb scattering. These results challenge the common view of ultrafast thermalization by electron-electron scattering.
When a magnetic field is applied to graphene, Landau levels are formed that can be selectively excited by circular-polarized radiation. In a pump-probe experiment, exciting and probing all possible transitions between the n=-1, n=0 and n=+1 Landau levels in slightly n-type graphene, we observe an unexpected sign reversal of the n=0 →1 probe signal when pumping the -1→0 transition. This directly reflects the fact that the n=0 Landau level is depleted by electron-electron Auger-type scattering, even though it is optically pumped at the same time.
Both effects can be quantitatively reproduced by a microscopic calculation based on the graphene Bloch equations, and shed new light on the possibility of infrared and THz devices based on hot carriers in graphene.
Keywords: graphene, pump-probe, free-electron laser, Landau levels
  • Invited lecture (Conferences)
    International Conference on Terahertz Emission, Metamaterials and Nanophotonics (TERAMETANANO 2016), 03.-10.04.2016, Cartagena, Colombia

Permalink: https://www.hzdr.de/publications/Publ-23533
Publ.-Id: 23533


Prompt γ-ray based proton range verification: From experiments to clinical application

Priegnitz, M.; Nenoff, L.; Barczyk, S.; Golnik, C.; Hotoiu, L.; Keitz, I.; Smeets, J.; Trezza, A.; Vander Stappen, F.; Werner, T.; Fiedler, F.; Prieels, D.; Baumann, M.; Enghardt, W.; Pausch, G.; Richter, C.
no abstract available
  • Poster
    National Center for Radiation Oncology 2nd Scientific Retreat, 14.-16.04.2016, Dresden, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23531
Publ.-Id: 23531


Comparison of in silico, electrochemical, in vitro and in vivo metabolism of a homologous series of (radio)fluorinated sigma1 receptor ligands designed for positron emission tomography

Wiese, C.; Große Maestrup, E.; Galla, F.; Schepmann, D.; Hiller, A.; Fischer, S.; Ludwig, F. A.; Deuther-Conrad, W.; Donat, C. K.; Brust, P.; Büter, L.; Karst, U.; Wünsch, B.
The imaging of σ1 receptors in the brain by fluorinated radiotracers will be used for the validation of σ1 receptors as drug targets as well as for differential diagnosis of diseases in the central nervous system. The biotransformation of four homologous fluorinated PET tracers 1′-benzyl-3-(ω-fluoromethyl to ω-fluorobutyl)-3H-spiro[2]benzofuran-1,4′-piperidine] ([18F]1–4) was investigated. In silico studies using fast metabolizer (FAME) software, electrochemical oxidations, in vitro studies with rat liver microsomes, and in vivo metabolism studies after application of the PET tracers [18F]1–4 to mice were performed. Combined liquid chromatography and mass spectrometry (HPLC–MS) analysis allowed structural identification of non-radioactive metabolites. Radio-HPLC and radio-TLC provided information about the presence of unchanged parent radiotracers and their radiometabolites. Radiometabolites were not found in the brain after application of [18F]2–4, but liver, plasma, and urine samples contained several radiometabolites. Less than 2 % of the injected dose of [18F]4 reached the brain, rendering [18F]4 less appropriate as a PET tracer than [18F]2 and [18F]3. Compounds [18F]2 and [18F]3 possess the most promising properties for imaging of σ1 receptors in the brain. High σ1 affinity (Ki=0.59 nm), low lipophilicity (logD7.4=2.57), high brain penetration (4.6 % of injected dose after 30 min), and the absence of radiometabolites in the brain favor the fluoroethyl derivative [18F]2 slightly over the fluoropropyl derivative [18F]3 for human use.
Keywords: Homologous fluorinated sigma1 receptor ligands; positron emission tomography; biotransformation; electrochemical oxidation; rat liver microsomes; in vivo metabolism

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Publ.-Id: 23530


Beta-Amyloid-PET-Bildgebung des Gehirns - DGN-Handlungsempfehlung

Barthel, H.; Meyer, P. T.; Drzezga, A.; Bartenstein, P.; Boecker, H.; Brust, P.; Buchert, R.; Coenen, H. H.; Fougère, C. L.; Gründer, G.; Grünwald, F.; Krause, B. J.; Kuwert, T.; Schreckenberger, M.; Tatsch, K.; Langen, K. J.; Sabri, O.
Seit Kurzem sind mehrere Radiopharmaka für die klinische Positronen-Emissions-Tomographie (PET) von mit der Alzheimer-Krankheit assoziierten zerebralen beta-Amyloid(Aß-Plaques zugelassen. Mit der zunehmenden Verbreitung dieser Methode entsteht der Bedarf für entsprechende Handlungsanweisungen. Diese S1-Leitlinie der Deutschen Gesellschaft für Nuklearmedizin beschreibt die adäquate Vorgehensweise bei der Aß-Plaque-PET-Bildgebung. Maßnahmen zur Patientenvorbereitung, zur Anamnese-Erhebung und zu Vorsichtsmaßnahmen werden ebenso vorgestellt wie die betreffenden Radiopharmaka, Maßnahmen zur PET-Daten-Gewinnung, -Verarbeitung, -Analyse und -Befundung. Damit soll ein Beitrag zur Qualitätssicherung in der Nuklearmedizin in Deutschland geleistet werden.
Keywords: beta-Amyloid, Plaques, Positronen-Emissions-Tomographie, PET, Leitlinie

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Publ.-Id: 23529


Rational Structure-Based Rescaffolding Approach to de Novo Design of Interleukin 10 (IL-10) Receptor-1 Mimetics

Ruiz-Gómez, G.; Hawkins, J. C.; Philipp, J.; Künze, G.; Wodtke, R.; Löser, R.; Fahmy, K.; Pisabarro, M. T.
Tackling protein interfaces with small molecules capable of modulating protein-protein interactions remains a challenge in structure-based ligand design. Particularly arduous are cases in which the epitopes involved in molecular recognition have a non-structured and discontinuous nature. Here, the basic strategy of translating continuous binding epitopes into mimetic scaffolds cannot be applied, and other innovative approaches are therefore required. We present a structure-based rational approach involving the use of a novel customized PROSITE-based regular expression syntax to define minimal descriptors of geometric and functional constraints signifying relevant unctionalities for recognition in protein interfaces of non-continuous and unstructured nature. These descriptors feed a search engine that explores the currently available three-dimensional chemical space of the Protein Data Bank (PDB) in order to identify in a straightforward manner regular architectures containing the desired functionalities, which could be used as templates to guide the rational design of small natural-like scaffolds mimicking the targeted recognition site. The application of this rescaffolding strategy to the discovery of natural scaffolds incorporating a selection of functionalities of interleukin-10 receptor-1 (IL-10R1), which are relevant for its interaction with nterleukin-10 (IL-10) has resulted in the de novo design of a new class of potent IL-10 peptidomimetic ligands.
Keywords: de novo design; peptidomimetics; IL-10 receptor mimetic; 3D functional descriptors; proteinprotein interactions

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Publ.-Id: 23528


Liquid velocity determination using thermal anemometry in two-phase flows: new developments

Neumann, M.; Bieberle, A.; Hampel, U.
This article is intended to give an overview of novel approaches to apply thermal anemometry measuring technique for the determination of gas and liquid velocities in two-phase flows, which are currently being pursued at Helmholtz-Zentrum Dresden-Rossendorf. Thermal anemometers are commonly used for determination of local fluid velocities within single phase flows. Because of their high temporal resolution they are also capable of determining velocity fluctuations, as they are common in highly turbulent flows in technical applications and devices. These experimental data are, amongst others, required for validation and development of CFD codes. However, since turbulent two-phase flows (e.g. bubbly flows) are predominant in technical applications, the application of thermal anemometers is highly desired there as well. But, interpretation of those measurement signals is rather complex, since they contain information of both phases, e.g. liquid and gas respectively. To overcome these difficulties, application-oriented adoptions of this measurement technique have to be made. The here presented approaches comprise sophisticated design modifications of the probe itself as well as a novel operation mode. It is intended to utilize such a probe especially for the velocity measurement of the liquid phase in two-phase flows within complex geometries at high temporal resolution.
Keywords: Thermal anemometry, two-phase flow
  • Contribution to proceedings
    Specialists Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal Hydraulics (SWINTH) 2016, 15.-17.06.2016, Livorno, Italia
    Liquid velocity determination using thermal anemometry in two-phase flows: new developments, Pisa, Italy: Grafiche Caroti, 978-88-902391-9-9, 3-73
  • Lecture (Conference)
    Specialists Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal Hydraulics (SWINTH) 2016, 15.-17.06.2016, Livorno, Italia

Permalink: https://www.hzdr.de/publications/Publ-23527
Publ.-Id: 23527


Production and purification of no-carrier-added 139Ce at the Leipzig cyclotron CYCLONE® 18/9

Mansel, A.; Franke, K.
The global demand for the lanthanides has dramatically increased. Therefore, a detailed understanding of ore chemistry and separation methods is needed. To study these processes, the use of the radiotracer technique is a marvellous method to observe the chemical behaviour of such elements. 139Ce (T1/2 = 137.6 d, Eγ = 166 keV, Iγ = 80%) was chosen as a representative element (radionuclide) for the lanthanide elements. We produced 139Ce using the nuclear reaction 139La(p,n)139Ce by means of irradiation of a few tens mg [natLa]La2O3 at the Leipzig cyclotron CYCLONE® 18/9[1]. At an irradiation time of 3 h, an effective proton current of 2.9 µA and a maximal proton energy of 12.5 MeV, an activity of ~0.5 MBq 139Ce was achieved. The irradiated La2O3 was dissolved in conc. nitric acid and fumed to dryness. For the separation of the radionuclide from the target material, we used the tetravalent oxidation state of cerium by means of an oxidative application with a mixture of dichromate/sulfate in 9 M nitric acid. For the first time, UTEVA® Resin was used to separate the tetravalent cerium (Ce4+) in no-carrier-added (n.c.a.) form from the trivalent lanthanum (La3+) by ion exchange chromatography in column technique, as used for plutonium (Pu4+) separations from trivalent actinides (e.g. Am3+)[2]. The 139Ce4+ ions were washed from the column by 1 mM nitric acid. After evaporation of the combined cerium fractions, the 139Ce was dissolved in 1 mM nitric acid to give a stock solution with an activity concentration of ~1 MBq/ml. The radiochemical yield of n.c.a. 139Ce was 94% ± 5%. With a detection limit of 10 Bq/ml, a concentration range down to ~0.3 pmol/l n.c.a. 139Ce can be achieved. From the dissolution of the irradiated target until preparation of the stock solution, only 5 h are necessary. The chemical purity of the stock solution was evaluated by ICP-MS.
By a weekly in-house production of n.c.a. 139Ce, we can use this radionuclide in our institute (or cooperation partners) for actual studies in liquid-liquid extraction by means of calixarenes or radiolabelling of CeO2-nanoparticles.
References:
[1] C. Vermeulen et al. (2007) Nucl. Instr. Meth. B 255, 331. [2] E. P. Horwitz et al. (1992) Anal. Chim. Acta 266, 25.
Keywords: Lanthanides; No-carrier-added Cerium-139; Proton induced nuclear reaction; Radiochemical separation; UTEVA® Resin
  • Poster
    9th International Conference on Nuclear and Radiochemistry NRC9, 29.08.-02.09.2016, Helsinki, Finland

Permalink: https://www.hzdr.de/publications/Publ-23526
Publ.-Id: 23526


Two-Phase Flow Studies in Complex Geometries

Neumann, M.; Bieberle, A.; Hampel, U.
In many industrial applications, two-phase flows are predominant and consist often of a liquid and a gaseous phase. Especially in nuclear power plants, those multiphase flow regimes are heavily linked to safety related issues, e.g. behavior of vapor phase in BWRs, nucleate boiling at fuel rods or steam generator tubes as well as loss of coolant accident. One approach for the safety evaluation of nuclear facilities and the prediction of hazardous conditions is the utilization of numerical models and CFD tools. Unfortunately, these methods still need a high number of empirical correlations as closure models up to now, which makes a safe prediction nearly impossible.
Additionally, most of the components in industrial applications provide complex geometries, which create pronounced three-dimensional flow phenomena, e.g. in bends, valves, junctions or heat exchangers. Especially the numerical description of those two-phase flow fields is a challenging task, which requires further experimental data for the development and validation of existing models. At the Helmholtz-Zentrum Dresden - Rossendorf (HZDR) studies in a vertical pipe have already been performed [1]–[3]. In these studies, a movable obstacle was used to create three-dimensional flow phenomena, which was analyzed applying wire-mesh sensor technique. Both, the motion unit of the obstacle and the wire-mesh sensor were thereby located in the flow channel, disturbing the flow field. Furthermore, the wire-mesh sensor only provided single-plane measurements.
In this contribution, continued two-phase flow studies will be described using the ultrafast electron beam X-ray scanner ROFEX to additionally measure hydrodynamic parameters of the flow field around new designed obstacles contactless.
  • Contribution to proceedings
    47th Annular Meeting on Nuclear Technology, 10.-12.05.2016, Hamburg, Deutschland
  • Lecture (Conference)
    47th Annular Meeting on Nuclear Technology, 12.05.2016, Hamburg, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23525
Publ.-Id: 23525


A pilot study to use the 36Cl bomb peak as a tracer for groundwater flow velocities in the Western Dead Sea catchment

Wilske, C.; Suckow, A.; Roediger, T.; Geyer, S.; Weise, S. M.; Merchel, S.; Rugel, G.; Pavetich, S.; Merkel, B. J.; Siebert, C.
The aquifer system of the western Dead Sea catchment is stressed by semi-arid to arid climate conditions, limited groundwater recharge rates and increasing water abstractions for human water needs. The groundwater flow system is dominated by two main Cretaceous limestone aquifers with karst characteristics and discharging in springs in the Lower Jordan Valley and Dead Sea region. The karst properties give reason to assume parts of the flow system having high transmissivities and groundwater flow velocities, respectively. For estimating recharge rates and rain water infiltration time periods, 36Cl and 3H were used, with the anthropogenic bomb peaks as input functions.
The chloride content in groundwater of the limestone aquifers enriches after contact with the saline Quaternary sediments and groundwater in the Lower Jordan Valley. The 36Cl/Cl ratios in groundwater were found to be up to 1E-12 in the recharge area and decrease to 1E-14 in the discharge area. Groundwaters in the recharge area show partly 36Cl/Cl ratios comparable to those in recent precipitation. The wide range of 36Cl/Cl in the recharge area indicates different stages of chlorine isotope and elemental mixing within the recharge area or aquifer system. This may be due to varying Cl input (dependent on altitude and coastal proximity), varying 36Cl input (regional variation in fallout) or both. Together with 3H analyses it is possible to evaluate the recent rain water component in the springs emerging from the uppermost part of the Cretaceous aquifers.
Our results show that a combination of the 36Cl/Cl and 3H measurements in groundwater and a correlation to the atmospheric input curves of 36Cl/Cl and 3H allow estimating the admixture of post-bomb recharge in groundwater.
Keywords: 36Cl/Cl, tritium, groundwater age dating, Western Dead Sea catchment, AMS
  • Lecture (Conference)
    43rd IAH International Congress “Groundwater and society: 60 years of IAH”, 25.-29.09.2016, le Corum , Montpellier, France

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Permalink: https://www.hzdr.de/publications/Publ-23523
Publ.-Id: 23523


Bestimmung langlebiger Radionuklide mittels Beschleunigermassenspektrometrie (AMS): Applikationen und metrologische Aspekte

Merchel, S.
Die Bestimmung langlebiger Radionuklide (t1/2 = ~ka bis Ma) profitierte maßgeblich in den letzten Jahrzehnten von den technischen Entwicklungen auf dem Gebiet der hochsensitiven Beschleunigermassenspektrometrie (accelerator mass spectrometry, AMS). Die AMS besitzt gegenüber der konventionellen Massenspektrometrie den Vorteil, dass sie Störsignale, hervorgerufen von Molekülionen oder Isobaren, effektiver unterdrücken kann. Typische Nachweisgrenzen liegen im Bereich von 10-15 (Radionuklid/stabiles Nuklid) bzw. 105 Radionuklidatome oder 10-9 Bq.
Die Anwendungsfelder der Methode haben sich stark ausgeweitet: Die anfänglich bevorzugt untersuchten Proben aus der Kosmochemie, der Astrophysik und den Kernreaktionsdaten, werden zunehmend von Proben aus den Bereichen Strahlenschutz, Nuklearsicherheit, Nuklearentsorgung, Radioökologie, Phytologie, Ernährungswissenschaften, Toxikologie und Pharmakologie verdrängt. Die größte Bedeutung der angewandten AMS-Forschung liegt allerdings in den Geo- und Umweltwissenschaften. So können mit den kosmogen „in-situ“ produzierten Nukliden 10Be, 26Al und 36Cl relativ plötzlich auftretende prähistorische Ereignisse wie Vulkanausbrüche, Bergstürze, Tsunamis, Meteoriteneinschläge, Erdbeben und Gletscherbewegungen datiert werden. Anhand dieser Gletscherbewegungen und Untersuchungen an Eisbohrkernen können zudem Klimaveränderungen rekonstruiert werden.
Die Qualitätssicherung in der AMS (mit Ausnahme von 14C/12C) ist ein wichtiger, aber bisher leider vernachlässigter Aspekt. Wenige Ringversuche mit desaströsen Ergebnissen und das fast komplette Fehlen primärer Referenzmaterialien (mit Ausnahme von 41Ca/Ca) zeigen, dass die AMS zwar extrem nachweisempfindlich und oft auch präzise ist, aber momentan leider keine rückführbaren Daten liefert. Der Einsatz metrologisch rückgeführter Referenzmaterialien wäre allerdings für fast alle AMS-Applikationen wünschenswert und für wenige zwingend erforderlich.
Keywords: AMS, metrology, standard, reference material, radionuclide
  • Invited lecture (Conferences)
    Abteilungskolloquium der Abteilung 6 „Ionisierende Strahlung“ der Physikalisch-Technischen Bundesanstalt, 31.05.2016, Braunschweig, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23522
Publ.-Id: 23522


Novel Biotechnological Approaches for the Recovery of Metals from Primary and Secondary Resources

Pollmann, K.; Kutschke, S.; Matys, M.; Kostudis, S.; Hopfe, S.; Raff, J.
Microorganisms have developed various mechanisms to deal with metals, thus providing numerous tools that can be used in biohydrometallurgical processes. “Biomining” processes, that includes bioleaching and biooxidation processes, facilitate the degradation of minerals accompanied by a release of metals. These processes are especially attractive for low-grade ores and are used on industrial scale mainly for sulfidic ores. In biosorption processes, biomass or certain biomolecules are used to bind and concentrate selected ions or other molecules from aqueous solutions. Biosorptive materials can be an environmentally friendly and efficient alternative to conventional methods such as ion exchange resins. Other interesting mechanisms are bioaccumulation, bioflotation, bioprecipitation, and biomineralisation. Although these processes are well known and have been studied in detail during the last decades, the recent strong progress of biotechnologies such as genetic enginnering and molecule design as well as their combination with novel developments of material sciences such as nanotechnologies facilitate new strategies for the application of biotechnologies in mineral processing. The article gives a summary of current activities in this field that are performed in our group.
Keywords: biomining; biohydrometallurgy; bioleaching; biosorption; nanomaterials

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Permalink: https://www.hzdr.de/publications/Publ-23521
Publ.-Id: 23521


Role of Transient Reflection in Graphene Nonlinear Infrared Optics

Suess, R. J.; Winnerl, S.; Schneider, H.; Helm, M.; Berger, C.; de Heer, W. A.; Murphy, T. E.; Mittendorff, M.
Understanding the optical response of graphene at terahertz frequencies is of critical importance for designing graphene-based devices that operate in this frequency range. Here we present a terahertz pump-probe measurement that simultaneously measures both the transmitted and reflected probe radiation from multilayer epitaxial graphene, allowing for an unambiguous determination of the pump-induced absorption change in the graphene layers. The photon energy in the experiment (30 meV) is on the order of the doping level in the graphene which enables the exploration of the transition from interband to intraband processes, depending on the amount of pump-induced heating. Our findings establish the presence of a large, photoinduced reflection that contributes to the change in sign of the relative transmitted terahertz radiation, which can be purely positive or predominantly negative depending on the pump fluence, while the change in absorption is found negative at all fluences. We develop a hot carrier model that confirms the sign-reversible nature of the relative transmitted terahertz radiation through the graphene multilayer and determine that this behavior originates from either an absorption-bleached or reflection-dominated regime. The theoretical results are incorporated into a model utilizing an energy balance equation that reproduces the measured pump-probe data. These findings, which extend to mid- and far infrared frequencies, show the importance of considering reflection in graphene-light interactions and have implications for the design of future terahertz photonic components.
Keywords: Ultrafast dynamics, graphene, infrared spectroscopy, terahertz

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Publ.-Id: 23520


Surface modified ultrasmall nanoparticles as dual labelled imaging agents

Singh, G.; Licciardello, N.; Hunoldt, S.; Bergmann, R.; Faramus, A.; de Cola, L.; Stephan, H.
The development of multimodal imaging agents for biomedical applications is a growing field of research. The idea behind the use of nuclear and optical dual labelled imaging probes is the possibility to synergistically exploit the advantages of positron emission tomography (PET) and optical imaging. The use of dual imaging probes enhances sensitivity, spatial and temporal resolution, tissue penetrability and allows the simultaneous acquisition of complementary information which can improve diagnosis and treatment of diseases.
The utilization of nanomaterials in medicine holds a promising potential in emerging applications of diagnostic imaging as well as the prospect of new capabilities for delivering targeted therapies tailored for specific diseases. Due to their biocompatibility, luminescence properties and the possibility to covalently functionalize their surface, water-soluble ultrasmall (<5 nm) silicon nanoparticles (SiNPs) are excellent candidates in this perspective.(1,2)
Amine-terminated ultrasmall silicon nanoparticles were prepared according to a reported method with slight modifications.(3) Here we report the functionalization of amine-terminated SiNPs with the sulfo-cyanine 5 dye (sCy5) to obtain an optical imaging probe and with biomolecules, such as single-domain antibodies (sdAb) for active targeting of a cancer biomarker. SiNPs are also modified with radiolabel such as 64Cu, coordinated to bispidines(4), to obtain a dual, nuclear and optical, probe.
The functionalization of SiNPs with dyes, radiotracers and targeting molecules will open the path for targeted dual imaging of cancer, possibly allowing diagnosis and therapy in in vivo systems.

References
1) M. Rosso-Vasic et al., J. Mater. Chem. 2009, 19, 5926.
2) C. -H. Lai et al., Nano Lett. 2016, 16, 807−811.
3) Y. Zhong et al., J. Am. Chem. Soc. 2013, 135, 8350.
4) H. Stephan et al., Chem. Eur. J. 2014, 20, 17011.
Keywords: Silicon nanoparticles, Biomedical applications, Radiolabeling, Positron emission tomography, Optical imaging
  • Poster
    European Chemistry Congress, 11.-15.09.2016, Seville, Spain

Permalink: https://www.hzdr.de/publications/Publ-23519
Publ.-Id: 23519


Modellierung und Validierung von Feldionisation in parallelen Particle-in-Cell-Codes

Garten, M.
Die Modellierung von Feldionisation in Particle-in-Cell(PIC)-Codes ist eine wichtige Voraussetzung zur Untersuchung der Wechselwirkung hochintensiver, ultrakurzer Laserpulse mit Materie. Es existieren bereits zahlreiche Modelle, die akkurate Vorhersagen im Bereich nicht-relativistischer Intensitäten und oberhalb atomarer Zeitskalen treffen können. Weiterhin existieren auch zahlreiche PIC-Codes, die für den Einsatz auf CPUs konzipiert wurden und Feldionisation berücksichtigen. Das Ziel dieser Arbeit ist die Modellierung von Feldionisation auf neuen, hochparallelen GPU-Architekturen. Diese werden in den letzten Jahren verstärkt für wissenschaftliche Simulationen eingesetzt und bieten einen deutlichen Geschwindigkeitsvorteil gegenüber CPUs. Die Modellierung von Feldionisation auf GPGPUs birgt einige Herausforderungen und es ist das erweiterte Ziel dieser Arbeit, die Implementierung auch zu verifizieren. Dabei wird ein Einblick in die Schwierigkeiten gegeben, die bei der Anwendung existierender Ionisationsmodelle durch Einschränkungen der Modelle selbst, des PIC-Schemas sowie der Plasmadynamik zu beachten sind. In Folge dieser Arbeit wurde PIConGPU, der derzeit schnellste, vollständig relativistische Particle-in-Cell-Code der Welt, um ein allgemeines Werkzeug zur Modellierung von Ionisation erweitert. Dieses ermöglicht die Simulation neuer und spannender physikalischer Anwendungsfälle im Bereich der Laser-Plasmaphysik.
Keywords: Particle-In-Cell, field ionization, GPGPU, PIConGPU, ADK, BSI
  • Master thesis
    HZDR, TU Dresden, 2015
    Mentor: Prof. Dr. Thomas Cowan, Prof. Dr. Ulrich Schramm, Dr. Michael Bussmann
    0097 Seiten

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Permalink: https://www.hzdr.de/publications/Publ-23518
Publ.-Id: 23518


Instrumentation for experiments on a fuel element mock-up for the study of thermal hydraulics for loss of cooling or coolant scenarios in spent fuel pools

Arlit, M.; Partmann, C.; Schleicher, E.; Schuster, C.; Hurtado, A.; Hampel, U.
After the Fukushima accident the focus in nuclear safety research has been extended to the spent fuel pool. In the consequence of a longer persisting station black out or loss of integrity of the pool, the cooling of the fuel elements can potentially not be guaranteed. Thus, the investigation of the thermal hydraulics of potential accident scenarios is of great scientific interest. The German national joint project SINABEL (SIcherheit NAsslager BrennElement-Lagerbecken) deals with the experimental investigation and the modelling of thermal hydraulics during the dry-out of a spent fuel pool in the consequence of a loss of cooling scenario. For this purpose a fuel element mock-up with electrically heated rods is constructed. During a dry-out scenario the water in the fuel element mock-up heats up to boiling temperature and evaporates. The water level decreases due to the continuing heating and the rods will be exposed to steam atmosphere. Parameters that have to be measured are the surface temperature of the rods, the height of the water level and the temperature as well as the velocity of the steam in the subchannels of the rod bundle.
The fuel element mock-up is designed according to the original dimensions of a BWR fuel element with pitch-to-diameter ratio- P/D = 1.24 and rod diameter D = 10 mm in a 10 x 10 square array. The housing consists of several metal boxes. To avoid heat sinks (adiabatic situation with no radial heat flow) the components are produced without flanges and are surrounded by a compact thermal insulation. The accessibility for instrumentation and other installations is reduced to the top side. The surface temperatures of the rods are measured by thermocouples and the water level by pressure transducers and electrical needle probes respectively.
For measuring both the temperature and the velocity of the steam in the small sub-channels no standard instrumentation is available. The applicability of established measurement techniques, such as Particle Imaging Velocimetry or Pitot tube, is not given due to constructional aspects of the test facility and the given flow properties (high temperatures, low velocities). Therefore, in this study a newly developed measurement system will be used. The experimental operating conditions are temperatures up to ϑ = 500 °C and very low local steam velocities down to v = 0.01 m/ s. Furthermore, the flow is expected to be laminar. The requirement for spatial resolution is to have one measurement point per subchannel in all subchannels of one rod bundle quadrant.
The presented solution is a thermal anemometry grid sensor TAGS, that is grid-type arrangement of special temperature-sensor elements measuring both, the temperature and the velocity nearly simultaneously. The sensitive elements are mounted on a ceramic grid-like structured substrate and connected to each other in a matrix arrangement. This sensor is connected to a special excitation and data acquisition electronics, applying the measurement technique of resistance thermometry for temperature measurement and thermal anemometry for velocity measurement. Within the paper a detailed description of the instrumentation of the fuel element mock-up in general and more specifically the TAGS are presented together with first results.
Keywords: Spent fuel pool, temperature measurement, thermal anemometry, grid sensor
  • Contribution to proceedings
    SWINTH-2016 (Specialists Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal Hydraulics), 15.-17.06.2016, Livorno, Italy
    Proceedings of SWINTH-2016
  • Lecture (Conference)
    SWINTH-2016 (Specialists Workshop on Advanced Instrumentation and Measurement Techniques for Nuclear Reactor Thermal Hydraulics), 15.-17.06.2016, Livorno, Italia

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Publ.-Id: 23517


Thermal anemometry grid sensor for flow velocity measurement in the subchannels of a fuel element mock-up during dry-out

Arlit, M.; Schleicher, E.; Hampel, U.
For the determination of steam velocities in the subchannels of a fuel element mock-up during dry-out no suitable measurement techniques are available under the given boundary conditions of high temperatures and restricted accessibility. The newly developed thermal anemometry grid sensor closes this gap. Within the paper applied methods, technological aspects as well as a special calibration procedure for the measurement in superheated steam are presented.
Keywords: Thermal Anemometry, Grid Sensor, Temperature grid sensor
  • Contribution to proceedings
    47th Annual Meeting on Nuclear Technology, 10.-12.05.2016, Hamburg, Deutschland
    Proceedings of the 47th Annual Meeting on Nuclear Technology
  • Lecture (Conference)
    47th Annual Meeting on Nuclear Technology, 10.-12.05.2016, Hamburg, Deutschland

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Permalink: https://www.hzdr.de/publications/Publ-23516
Publ.-Id: 23516


Investigation of the Radial Effect On the Transition Velocities in a Bubble Column Based On the Modified Shannon Entropy

Nedeltchev, S.; Hampel, U.; Schubert, M.
A new method for flow regime identification in a bubble column (0.15 m in ID) based on a modification of the Shannon entropy (SE) algorithm was developed. The bubble column was equipped with a perforated plate distributor (14 holes, Ø 4×10-3 m) and operated with an air-deionized water system at ambient conditions. The newly introduced dimensionless ratio of minimum SE to maximum SE was capable of identifying the main transition velocities at three different dimensionless radial positions (r/R): 0.0 (core), 0.63 (inversion point) and 0.88 (annulus).
In the core of the column the new parameter identified successfully three transition velocities Utrans at 0.034, 0.089 and 0.134 m/s. They mark the end of the gas maldistribution regime, the onset and the end of the churn-turbulent flow regime, respectively. Three Utrans values (at 0.045, 0.089 and 0.124 m/s) were also identified in the annulus of the column. However, the second transition velocity identified the boundary between the first and second transition sub-regimes. The third transition velocity distinguished the onset of the churn-turbulent flow regime. It was found that in the core of the column both the transition and churn-turbulent flow regimes start earlier, which is due to the earlier onset of the bubble coalescence caused by higher gas fraction in the column center.
At the inversion point of the axial liquid velocity the end of the gas maldistribution regime is shifted to a somewhat higher Utrans value (0.067 m/s). The second transition sub-regime begins at 0.101 m/s, whereas the onset of the churn-turbulent regime is identified at 0.124 m/s.
The SE algorithm was also applied to both the first and second half of the time series and the ratio of both SEs was successfully used as a flow regime identifier.
Keywords: Bubble column, Gas holdup fluctuations, Wire-mesh sensor, Transition velocities, Modified Shannon entropy

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Permalink: https://www.hzdr.de/publications/Publ-23515
Publ.-Id: 23515


Application of X-ray absorption spectroscopy to actinide research

Scheinost, A. C.
An overview will be given on the applications of x-ray absorption spectroscopy to actinide research, including topics in nuclear waste management and development of fourth generation nuclear fuel
Keywords: XAFS Nuclear fuel nuclear waste disposal
  • Invited lecture (Conferences)
    11th School on the Physics and Chemistry of the Actinides, 13.-16.03.2016, Grenoble, France

Permalink: https://www.hzdr.de/publications/Publ-23514
Publ.-Id: 23514


Distillation Tray Efficiency Modeling: A Forgotten Chapter

Vishwakarma, V.; Schubert, M.; Hampel, U.
Cross-flow trays are highly reputed among vapour-liquid contacting devices due to their versatility. They have been into existence for two centuries; still the estimation of their mass transfer efficiency relies mostly on experience. There have been numerous attempts in the past to understand the nature of liquid mixing and flow patterns on trays. However, very few have managed to relate their findings with tray efficiency.
The present work aims at reviewing mathematical models developed for predicting distillation tray efficiency. These models were developed by considering simplified assumptions namely plug flow, uniform vapour composition, constant froth height etc. It is needless to mention the requirement of an improved mathematical model accounting real flow scenarios. This work also attempts to encourage the fraternity of fluid separation technology to revive the efficacy of tray modeling.
Keywords: Distillation Trays, Murphree Tray Efficiency, Eddy Diffusion Model, Residence Time Distribution
  • Poster
    Jahrestreffen der ProcessNet-Fachgruppe Fluidverfahrenstechnik, 16.-17.03.2016, Garmisch-Partenkirchen, Germany

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Permalink: https://www.hzdr.de/publications/Publ-23512
Publ.-Id: 23512


A gas cell for stopping, storing and polarizing radioactive particles

Sytema, A.; van den Berg, J. E.; Böll, O.; Chernowitz, D.; Dijck, E. A.; Grasdijk, J. O.; Hoekstra, S.; Jungmann, K.; Mathavan, S. C.; Meinema, C.; Mohanty, A.; Müller, S. E.; Nuñez Portela, M.; Onderwater, C. J. G.; Pijpker, C.; Willmann, L.; Wilschut, H. W.
A radioactive beam of 20Na is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenological model.
Keywords: β decay; Gas catcher; Polarization in buffer gas; Plasma

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Permalink: https://www.hzdr.de/publications/Publ-23511
Publ.-Id: 23511


Controlled polar asymmetry of few-cycle and intense mid-infrared pulses

Schmidt, C.; Bühler, J.; Mayer, B.; Pashkin, A.; Leitenstorfer, A.; Seletskiy, D.
We demonstrate synthesis of ultrabroadband and phase-locked two-color transients in the multi-terahertz frequency range with amplitudes exceeding 13 MV cm−1. Subcycle polar asymmetry of the electric field is adjusted by changing the relative phase between superposed fundamental and second harmonic components. The resultant broken symmetry of the field profile is directly resolved via electro-optic sampling. Access to such waveforms provides a direct route for control of low-energy degrees of freedom in condensed matter as well as non-perturbative light–matter interactions under highest non-resonant electric bias.
Keywords: polar asymmetry, THz, harmonic synthesis, quantum control, mid-infrared, high field, non-perturbative light–matter interaction

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Permalink: https://www.hzdr.de/publications/Publ-23510
Publ.-Id: 23510


Magnetically patterned rolled-up exchange bias tubes: A paternoster for superparamagnetic beads

Ueltzhöffer, T.; Streubel, R.; Koch, I.; Holzinger, D.; Makarov, D.; Schmidt, O. G.; Ehresmann, A.
We realized a deterministic transport system for superparamagnetic beads in a paternoster-like manner with position-dependent trajectories and velocities by rolling up exchange bias layer systems with engineered parallel stripe magnetic domains to tubular architectures possessing distinct azimuthally aligned magnetic domain patterns. By applying periodic pulse sequences of very weak external magnetic fields and taking advantage of the magnetic stray field emerging from the tubular structures, we demonstrate the transport for different superparamagnetic beads either in or above the rolled-up tubes acting as channels. This transport mechanism features high step velocities and remote control of not only the direction and trajectory but also the velocity of the transport without the need of fuel or catalytic material. Therefore, this approach paves the way towards novel 3D-applications in biotechnology, including particle transport related phenomena in lab-on-a chip and lab-in-a-tube devices.
Keywords: Rolled-up tube, exchange bias, ion bombardment induced magnetic patterning, particle transport, superparamagnetic beads, lab-in-a-tube, lab-on-a-chip

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Permalink: https://www.hzdr.de/publications/Publ-23509
Publ.-Id: 23509


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