Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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32179 Publications
S100 proteins in health and disease
Pietzsch, J.;
kein Abstract verfügbar

Publ.-Id: 16251 - Permalink


Ultrafast X-ray computed tomography of gas-solid fluidized beds
Bieberle, M.; Barthel, F.; Hampel, U.;
Gas-solid fluidized beds find various applications in chemical and process engineering, for instance in fluid catalytic cracking, drying of particulate solids or polyolefin production. The gas-particle flow in fluidized beds is generally complex and difficult to observe, but exact information on voidage distribution and solid transport is urgently needed for assessment, monitoring, modelling and optimization of fluidized bed operation.
Only few of the currently available flow measurement techniques are applicable to dense fluidized beds. Optical imaging and laser-based methods are at the most merely able to capture the peripheral structure of the solids phase or to provide local information by using probes. For tomographic techniques, such as electrical capacitance tomography (ECT), positron emission tomography (PET) or common X-ray CT, it is in general difficult to provide high spatial and high temporal resolution at the same time.
We here introduce a much faster X-ray tomography approach which is based on electron beam scanning. There, an electron beam is rapidly swept along a circular target to produce a moving X-ray source. A static detector ring with 240 detector elements synchronously captures the radiation intensity. From the resulting radiographic projections of the object of interest non-superimposed cross-sectional density distributions are reconstructed. Beside its really fast scanning capability other advantages of this approach are the use of a single electron beam generator and the high versatility of the electron beam with respect to scan patterns and scanning speed. With our approach we have already demonstrated multiphase flow imaging with frame rates of up to 10.000 fps and a spatial resolution in the range of better than 1 mm.
The results presented here include studies at a bubbly fluidized bed with monodisperse spherical particles, in which the capability of the method to visualize the particle dynamics and the internal structure of the fluidized bed in very detail are demonstrated.
Keywords: tomography, ultrafast, fluidized bed, voidage, visualization
  • Lecture (Conference)
    gas-liquid and gas-liquid-solid reactor engineering congress (GLS 10), 26.-29.06.2011, Braga, Portugal

Publ.-Id: 16250 - Permalink


Ultrafast X-ray computed tomography for the analysis of gas-solid fluidized beds
Bieberle, M.; Barthel, F.; Hampel, U.;
Gas-particle flow in fluidized beds is generally complex and difficult to observe. But exact information on voidage distribution and solid transport is urgently needed for assessment, monitoring, modelling, and optimization of fluidized bed operation. So far, there was a lack of suitable measurement and imaging techniques to disclose the complex flow structures in fluidized beds with high spatial and temporal resolution. The recently developed ultrafast X-ray computed tomography technique is superior for such types of multiphase flows and its performance has been demonstrated in this study. Spatial resolution in the range of one millimetre and temporal resolution of several thousand cross-sectional images per second allows at the same time imaging and analysis of voidage structures as well as single particle movement. In this study, the capability of imaging fluidized bed behaviour at different column diameters and gas flow rates has been analysed.
Keywords: tomography, ultrafast, fluidized bed, voidage, visualization

Publ.-Id: 16249 - Permalink


A new radiolabeling method for commercial Ag0 nanopowder with 110mAg for sensitive nanoparticle detection in complex media
Hildebrand, H.; Franke, K.;
Nanoparticle (NP) tracking in complex media is still a challenge since NP concentrations are expected to be low compared to elemental background levels as it can be found in environmental matrices. This study presents a new method for radiolabeling of commercial silver nanopowder (Ag0-NPs, dp < 100 nm) with 110mAg radionuclides (t1/2 = 250 d) that provide an adequate time frame for particle detection, localization and tracking under various experimental conditions. The radiolabeling procedure ensures high efficiency, stability and consistency of particle properties. Detection of Ag0-NP in concentrations as low as 125 ng kg-1 could be reached. For the first time, an appropriate tool for life-cycle studies of commercial Ag0-NPs is provided without changing chemical composition of the material. This is of great importance e.g. for research in the field of nanotoxicology.
Keywords: radiolabeling, nanoparticle, silver, nanoparticle detection, nanoparticle tracking

Publ.-Id: 16248 - Permalink


Grain alignment in poly-Si films by means of Plasma Immersion Ion Implantation (PIII) in combination with Flash Lamp Annealing (FLA)
Endler, R.; Voelskow, M.; Skorupa, W.;
A series of experiments have been performed with the aim to improve the electrical and structural properties of CVD – deposited thin polycrystalline silicon films. Using an advanced ion implantation technique like Plasma-Immersion-Ion- Implantation (PIII) in combination with short time Flash-Lamp-Annealing (FLA) it has been shown that in comparison to the as deposited state a significant enlargement of the mean grain size occurs, accompanied by a more pronounced texturizing. Furthermore, the main crystallographic axes of the grains have been found to be mostly parallel to the direction of the particle stream. Whereas the enlargement of the mean grain size due to ion channelling was already reported by Reif et al. in the 80s, in the present work the SSIC technique (Seed Selection though Ion Channelling) was applied for the first time using the PIII process. This technique ensures a high throughput; additionally the costs for the implantation step can be reduced in comparison to conventional ion implantation. Furthermore, in contrast to the well known existing recrystallization techniques like cw-laser annealing or lateral zone melting recrystallization (ZMR), the proposed method circumvents problems arising from several mass transports characteristics of techniques based on melt processes.
Keywords: Flash Lamp Annealing, Poly-Si, SSIC
  • Poster
    Subtherm2011, 24.-27.10.2011, Dresden, BRD

Publ.-Id: 16247 - Permalink


Timing (a) FLASH
Tavella, F.; Stojanovic, N.; Geloni, G.; Gensch, M.;
Many fundamental processes in nature like chemical reactions or phase transitions occur on the few femtosecond time and few nanometres to few angstroms length scale. On a way to their understanding, great hope lies on investigations of their dynamic using the bright, coherent X-ray pulses from free electron lasers (FELs) that have a duration and wavelength commensurate with that of these processes.
We developed a method to measure the arrival time of the X-ray pulses at FLASH with respect to the pump-probe laser in the experimental hall on a few femtosecond timescale, making use of the THz beamline [1]. Method is easily transferable to other advanced light source working with ultrashort electron bunches and therefore of high general interest.
  • Open Access LogoContribution to external collection
    in: DESY Highlights 2011, Hamburg: DESY, 2012

Publ.-Id: 16246 - Permalink


The Rossendorf Beamline at ESRF: A multipurpose X-ray absorption spectroscopy and scattering beamline for Environmental and Materials Sciences
Scheinost, A. C.;
The Rossendorf Beamlines at ESRF is operated since 1997 by the Helmholtz Center Dresden-Rossendorf. As a multipurpose synchrotron x-ray beamline, it serves both inhouse and collaborative research in Environmental and Materials Science. Its optics provide tunable monochromatic x-rays to two experimental stations, the first specialized in bulk x-ray absorption spectroscopy for environmental radionuclide research, and the second specialized in a variety of scattering techniques to elucidate the structure of thin films and other materials. The first focus of my talk will be on the performance of the optics, which are donated to SESAME. I will then show some research examples, and give an overview on the organization, funding and personnel input, and productivity parameters (publications, projects, and outreach).
Keywords: Environmental Sciences, Materials Sciences, ROBL, Synchrotron
  • Invited lecture (Conferences)
    SESAME User Meeting 2011, 12.11.2011, Amman, Jordan

Publ.-Id: 16245 - Permalink


X-ray absorption spectroscopy for environmental sciences: examples and technical challenges
Scheinost, A. C.;
Due to its element specificity, low detection limit, and independence on long-range and crystalline order, X-ray absorption spectroscopy (XAS) is one of the most versatile tools to elucidate the electronic and molecular structure of almost any element in environmental samples. It is fundamental to study the speciation and structure of dissolved (aqueous) complexes, from the most simple solvated ion to polyatomic complexes, to colloids, amorphous and crystalline solids. Furthermore, it is extremely useful to study sorption and redox reactions at the water/solid interface. I will demonstrate its application in environmental chemistry to study the fate of metal contaminants in soils, sediments and water bodies.
Keywords: XAS, XAFS, EXAFS, XANES, environmental sciences
  • Invited lecture (Conferences)
    SESAME User Meeting 2011, 12.11.2011, Amman, Jordan

Publ.-Id: 16244 - Permalink


The Ksar Ghilane 002 shergottite – the 100th registered Martian meteorite Fragment
Llorca, J.; Roszjar, J.; Cartwright, J. A.; Bischoff, A.; Pack, A.; Ott, U.; Merchel, S.; Rugel, G.; Fimiani, L.; Ludwig, P.; Allepuz, D.; Casado, J. V.;
We report on the discovery of a new shergottite from Tunisia, Ksar Ghilane (KG) 002, which is the 100th Martian meteorite fragment registered in the Meteoritical Bulletin. This single stone, weighing 538 g, is a coarse-grained basaltic shergottite, mainly composed of maskelynitized plagioclase (~52 vol.%) and pyroxene (~37 vol.%). It also contains Fe-rich olivine (~4.5 vol.%), large Ca-phosphates, including both merrillites and Cl-apatites (~3.4 vol.%), minor amounts of silica or SiO22-normative K-rich glass, pyrrhotite, Ti-magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of ~4 mm and ~5 mm. Regarding texture, KG 002 shares some similarities with the evolved NWA 2800 Martian sample. Pyroxene compositions in KG 002 are Fs26-96En5-50Wo2-41 (n=82). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Most plagioclases (maskelynites) are Ab41-49An39-58Or1-7 in composition, but some can be as anorthitic as An94. Olivine occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. These minerals are Fa91-96 in composition. Ksar Ghilane 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets and low radiogenic He concentration. Two analyses of oxygen isotopes (delta18O=+5.09 and 5.26‰, delta17O=+3.0 and +3.2‰, and Δ17O=+0.28 and +0.43‰) confirm that this rock is a normal member of the SNC suite of meteorites. Bulk chemical analyses indicate that KG 002 belongs to the main group of basaltic shergottites and it is strikingly similar to the highly-evolved Los Angeles meteorite. According to the K, U, Ba and Sr abundances and fresh appearance of sulfides, KG 002 is not significantly weathered, although a positive Ce anomaly is recognized in the REE pattern. Ksar Ghilane 002 is slightly depleted in LREE and shows a positive Eu anomaly providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for Martian interior may be a dominant component in KG 002. 10Be, 26Al, and 53Mn measurements and comparison with theoretical Monte-Carlo calculations of production rates indicate that KG 002 has been exposed most likely as a single meteoroid body of 35-65 cm radius between 2.8 and 3.7 Ma. Ksar Ghilane 002 strongly resembles Los Angeles and NWA 2800 basaltic shergottites in element composition, petrography and mineral chemistry, suggesting a possible launch-pairing. The CRE ages of KG 002 and Los Angeles may suggest an ejection event at ~3.0 Ma.
Keywords: accelerator mass spectrometry, AMS, cosmogenic radionuclide, Mars, meteorite, noble gases

Publ.-Id: 16243 - Permalink


Influence of storage on the position of the germinal disc in the fertilized unincubated chicken egg
Burkhardt, A.; Meister, S.; Bergmann, R.; Koch, E.;
The breeding of male layer chickens is currently considered to be highly uneconomical. In Germany alone, 40 to 50 million newly hatched male chickens were killed annually immediately after hatching. Therefore, it is necessary to find a method for sexing chickens early in the embryonic development, preferably before incubation. The genotypic sex of an egg can be determined using information found in the germinal disc, so knowledge of the exact position of the germinal disc is essential for further sexing, or for other actions such as the in ovo injection of agents. Previous studies have shown that the germinal disc is located somewhere on top of the yolk. However, no studies have yet been performed that investigate the influence of time spent in horizontal storage on the position of the germinal disc. Magnetic resonance imaging was chosen to determine this influence on the position of the germinal disc. It was found that eggs placed horizontally for long periods of time befor!
e scanning had significant changes in the positions of their germinal discs compared with those of eggs scanned minutes after positioning. The position of the germinal disc in eggs, minutes after horizontal positioning, deviated 14.7 +/- 0.6 mm from the maximum vertical plane of the egg (zero position) in the z-direction; eggs scanned after 96 h of horizontal positioning showed a deviation of only 4.9 +/- 1.6 mm. The x-axis also exhibited changes in the position of the germinal disc over time. Immediately after horizontal positioning, the eggs showed a deviation of 0.4 +/- 0.4 mm in the x-direction, whereas the deviation after 96 h was 2.9 +/- 0.5 mm. These results show that horizontal positioning of the egg hours before the measurement is necessary.

Publ.-Id: 16242 - Permalink


On the effect of different placing ZrH moderator material on the performance of a SFR core
Merk, B.; Weiß, F.-P.;
The structure for the development of a fuel assembly design with reduced sodium void achieved by the use of the moderating material ZrH is investigated. In the study the sodium void effect, as well as the major feedback coefficients are analyzed. Besides the feedback coefficients, the influence on the operational parameters like neutron flux distribution, power distribution, and burnup distribution is investigated for the different possibilities of arranging the moderating material in the fuel assembly. Additionally, the fuel cycle parameters – breeding and minor actinide production – are analyzed. For a first evaluation of the behavior during transients the influence of temperature changes in the ZrH is studied.
Keywords: Sodium void effect, SFR, Fast reactor, Zirconium hydride, designable feedback coefficient.
  • Contribution to proceedings
    PHYSOR 2012 - Advances in Reactor Physics, 15.-20.04.2012, Knoxville, USA
  • Lecture (Conference)
    PHYSOR 2012 - Advances in Reactor Physics, 15.-20.04.2012, Knoxville, USA

Publ.-Id: 16241 - Permalink


On the possible gain of the application of the sp3 solution in nodal codes
Merk, B.;
The simplified PN method has attracted much attention in reactor physics. The implementation of an increased order expansion has the potential to improve the results. It is investigated if this potential can be released under the specific features of nodal codes with fuel assembly sized calculation cells.
One dimensional analytical solutions for the one and two energy-group diffusion, SP3 and P3 equations are derived. The results are compared with reference solutions calculated with ONEDANT and HELIOS. Tests are performed on the Brantley, Larsen one-group test case and on a pin cell with real reactor materials. For the evaluation of the differences between the diffusion and the SP3 solutions in the nodal code configuration, benchmark configurations are investigated.
A comparison of the diffusion and the SP3 results show improvements for the test case using fuel element size nodes when compared to a reference solution using the identical cross section basis. Comparing with a multi-group reference solution shows that the diffusion solution sometimes behaves better due to error cancellation. To achieve the full gain of the SP3 method in nodal calculations, a new standard for light water reactor calculations has to be defined with a refined energy-group structure.
Keywords: simplified PN, nodal calculations, reactor physics, analytical solutions, neutron transport.
  • Contribution to proceedings
    PHYSOR 2012 - Advances in Reactor Physics, 15.-20.04.2012, Knoxville, USA
  • Lecture (Conference)
    PHYSOR 2012 - Advances in Reactor Physics, 15.-20.04.2012, Knoxville, USA

Publ.-Id: 16240 - Permalink


An analytical solution for the consideration of the effect of adjacent fuel assemblies; comparison of rectangular and hexagonal structures
Merk, B.; Rohde, U.;
A new analytical method is described to deal with the Leakage Environmental Effect. The method is based on the analytical solution of the two group diffusion equation for two adjacent fuel assemblies. The quality of the results for this highly efficient method is demonstrated for quadratic fuel assemblies. In additional tests the transferability of the concept to hexagonal VVER-440 type fuel assemblies is shown and a comparison between the results for rectangular and hexagonal assemblies is given.
Keywords: Analytical solution, Homogenization, Cross-section preparation, Leakage assembly environmental effect, Diffusion equation
  • Contribution to proceedings
    PHYSOR 2012 - Advances in Reactor Physics, 15.-20.04.2012, Knoxville, USA
  • Lecture (Conference)
    PHYSOR 2012 - Advances in Reactor Physics, 15.-20.04.2012, Knoxville, USA

Publ.-Id: 16239 - Permalink


An analytical solution for the consideration of the effect of adjacent fuel assemblies; extension to hexagonal fuel assemblies
Merk, B.; Rohde, U.;
A new analytical method is described to deal with the Leakage Environmental Effect. The method is based on the analytical solution of the two group diffusion equation for two adjacent fuel assemblies. The quality of the results for this highly efficient method is demonstrated for quadratic fuel assemblies. In additional tests the transferability of the concept to hexagonal VVER-440 type fuel assemblies is shown.
Keywords: VVER, Analytical Solution, Homogenization, Cross Section Preparation, Leakage Assembly Environmental Effect
  • Contribution to proceedings
    AER Symposium, 19.-23.09.2011, Dresden, Deutschland
  • Lecture (Conference)
    AER Symposium, 19.-23.09.2011, Dresden, Deutschland

Publ.-Id: 16237 - Permalink


Accuracy of MR-based attenuation correction First experience with a whole-body PET/MR system
Schramm, G.; Brüning, E. M.; Langner, J.; Hofheinz, F.; Will, E.; Beuthien-Baumann, B.; Oehme, L.; Platzek, I.; Steinbach, J.; Laniado, M.; Kotzerke, J.; van den Hoff, J.;
Purpose/Introduction: Sequential PET/MR scanners for whole body investigations have been developed only recently and are starting to become commercially available. In 2011, one of the first of these combined systems (Ingenuity TF PET/MR, Philips) was installed at our institute. PET/MR is expected to offer new possibilities, in particular in the field of quantitative bimodal functional imaging [1]. Quantitative PET requires attenuation correction (AC) which is commonly based on a measurement of the photon attenuation using either a radioactive source in standalone PET (RSAC), or CT in PET/CT systems (CTAC). In PET/MR systems such a measurement cannot be performed, therefore AC is based on a dedicated MR measurement (MRAC) plus segmentation and tissue type identification [2]. Here, we report on a first evaluation of MRAC in whole body investigations with the new system.

Subjects and Methods: Evaluation of MRAC is performed by a direct comparison of MRAC maps acquired with the Philips Ingenuity TF PET/MR and RSAC maps acquired with a Siemens ECAT Exact Hr+ PET scanner for 18 patients. Moreover, the quantitative influence of AC on the reconstructed images was investigated.

Results: In most cases the MRAC maps match the RSAC maps very well. Artefacts due to dental implants and sternal cerclages were found. In one case, the algorithm was not able to separate tissue from air in the patients lung. The influence of these artefacts on the reconstructed PET image will be reported.

Discussion/Conclusions: The vendor-provided MRAC algorithms yielded good results in our first patient measurements with respect to soft tissue and air segmentation. However, the algorithm relies on anatomic reference data and thus artefacts arise if the anatomy of the patient does not fit to the reference. In the future, an improved separation between tissue, bone and air without using anatomic reference data might be achieved with ultra short echo time sequences [3,4].

References:

[1] Pichler, B.J. et al., 2008, Sem. Nucl. Med., 199-208
[2] Martinez-Möller, A. et al., 2009, J. Nucl. Med., 520-526
[3] Catana, C. et al., 2010, J. Nucl. Med., 1431-1438
[4] Keereman, V. et al., 2010, J. Nucl. Med., 812-818
  • Lecture (Conference)
    ESMRMB Congress 2011, 06.-08.10.2011, Leipzig, D
  • Abstract in refereed journal
    Magnetic Resonance Materials in Physics, Biology and Medicine 24(2011), 199

Publ.-Id: 16236 - Permalink


Synthesis, colloidal stability and 64Cu labeling of iron oxide nanoparticles bearing different macrocyclic ligands
Barreto, J. A.; Matterna, M.; Graham, B.; Stephan, H.; Spiccia, L.;
The synthesis, solution stability and 64Cu2+ labeling of magnetite nanoparticles (NPs) coated with different macrocycles is reported, together with the stability of the resulting radioisotope-labeled NPs to transchelation by the competing ligand cyclam, and their stability in blood serum. Three macrocycles, 1,4-bis(2-pyridylmethyl)-1,4,7-triazacyclononane (dmptacn),1,4,8,11-tetraazacyclotetradecane (cyclam) and 1,4,7,10-tetraazacyclododecane (cyclen), and
3-aminopropyltriethoxysilane were used to modify the magnetite NPs. The ligands were covalently linked to the surface of the NPs with high efficiency by reaction of the corresponding
3-(3-(triethoxysiloxy)propoxy)propan-2-ol derivatives with the NPs. According to transmission electron microscopy (TEM), the uncoated magnetite NPs and macrocycle-functionalized congeners have an average diameter of 6 to 7 nm. The NPs form stable colloidal suspensions in 0.05 M aqueous 2-(N-morpholino)ethanesulfonic acid (MES) buffer, which consist of larger aggregates with a mean hydrodynamic size of about 200 nm. The NPs with the appended macrocycles can be efficiently labeled with 64Cu2+ ions and the radioactivity persists in rat plasma for at least 24 h. Challenge experiments with cyclam also indicate that the radiocopper complexes are highly stable, with the dmptacn-functionalized NPs showing the highest resistance to metal ion leakage. Overall, the dmptacn-functionalized iron oxide NPs provide an excellent platform for the development of robust multimodal cancer imaging/therapeutic agents.
  • New Journal of Chemistry 35(2011), 2705-2712

Publ.-Id: 16235 - Permalink


Concomitant targeting of cyclooxygenase-2 and oxidant stress pathways for radioprotection of endothelial cells.
Pietzsch, J.; Laube, M.; Pietzsch, F. J.; Bergmann, R.; Knieß, T.;
kein Abstract verfügbar
  • Contribution to external collection
    Lewis BS, Flugelman MY, Halon DA (eds.): Coronary Artery Disease: 2011 Update, Bologna: Medimond S. r. l - Monduzzi Editore International, 2011, 978-88-7587-619-7, 107-110

Publ.-Id: 16234 - Permalink


Site-selective radiolabeling of peptides by 18F-fluorobenzoylation with [18F]SFB in solution and on solid phase - a comparative study
Kuchar, M.; Pretze, M.; Knieß, T.; Steinbach, J.; Pietzsch, J.; Löser, R.;
Peptides labeled with short-lived positron-emitting radionuclides are of outstanding interest as probes for molecular imaging by positron emission tomography (PET). Herein, the site-selective incorporation of fluorine-18 into lysine-containing peptides using the prosthetic labeling agent N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB) is described. The reaction of [18F]SFB with four biologically relevant resin-bound peptides was studied and optimized. For comparison, each peptide was 18F-fluorobenzoylated in solution under different conditions and the product distribution was analyzed confirming the advantages of the solid phase approach. The method's feasibility for selective radiolabeling either at the N-terminus or at the lysine side chain was demonstrated. Labeling on solid phase with 18F]SFB resulted in crude 18F-fluorobenzoylpeptides whose radiochemical purities were typically greater than 90 % and that could be prepared in synthesis times from 65 to 76 min.

Publ.-Id: 16233 - Permalink


Biosorptive Kompositmaterialien für die Rückgewinnung von Wertstoffen: Neue Konzepte und Anwendungspotenziale
Pollmann, K.; Raff, J.; Kutschke, S.;
Es werden Konzepte zur Entwicklung von biosorptiven Materialien für die (Rück-)gewinnung von Metallen vorgestellt.
  • Invited lecture (Conferences)
    Biomining von Sekundärrohstoffen - Workshop 3 des Innovationsforums "Geobiotechnologie - mikrobiologische Verfahren in Bergbau und Umweltschutz", 14.-15.12.2011, Hannover, Deutschland

Publ.-Id: 16232 - Permalink


Herstellung von 61Cu mit hoher spezifischer Aktivität über die 64Zn(p,α)61Cu-Reaktion
Thieme, S.; Walther, M.; Rajander, J.; Pietzsch, H.-J.; Solin, O.; Steinbach, J.;
Ziel:
Die Herstellung von 61Cu hoher spezifischer Aktivität erfordert besonders aufwändige Maßnahmen, um Metallkontaminationen sowohl durch Cu-Isotope als auch durch andere Metalle zu minimieren. Dementsprechend müssen die herkömmlichen Methoden verfeinert werden, um 61Cu sowohl in hoher Qualität als auch effektiv herstellen zu können. Vergleichswerte über spezifische Aktivitäten von 61Cu sind in der Literatur selten zu finden. McCarthy et al. berichten zu spez. Aktivitäten von 61Cu im Bereich von 47 bis 190 GBq/µmol; erzeugt durch 61Ni(p,n)61Cu und 60Ni(d,n)61Cu-Reaktion. Eine Alternative dazu stellt die 64Zn(p,α)61Cu-Reaktion dar. Das hierfür genutzte Targetmaterial 64Zn (99,3% Isotopenanreicherung) ist im Vergleich zu angereichertem 61Ni weitaus weniger kostenintensiv.
Methoden:
Für die Bestrahlung am Zyklotron wird ein massiver Targetträger aus Gold verwendet, auf dem ca. 100 mg angereichertes 64Zn (99,3% Isotopenanreicherung) abgeschieden sind. Die radiochemische Trennung erfolgt über Ionenaustauschtechniken nach Literaturangaben. Die angewandte Methode nutzt eine Ionenaustauscherkaskade, die aus zwei Kationenaustauscher-Säulen und einer Anionenaustauscher-Säule besteht. Dabei sorgt der doppelte Kationenaustauscherschritt für die effektive Abtrennung von Galliumisotopen (66/67/68Ga) und die Anionenaustauscher-Säule für die Trennung des 61Cu vom Zn-Targetmaterial. Der Gesamtprozess zur Gewinnung des gereinigten 61Cu dauert eine Stunde. Die Methode umfasst die Wiedergewinnung des eingesetzten 64Zn, welches danach zur erneuten Verwendung zur Verfügung steht. Das optimierte Verfahren nutzt kleinere Ionenaustauschersäulen als bisher und ausschließlich wässrige Salzsäure; Details vgl. Thieme et al.. Die Ermittlung der spezifischen Aktivität erfolgt über TETA-Titrationen und ICP-MS-Analysen. Es wurden Bestrahlungen an zwei verschiedenen Zyklotronen durchgeführt: am Cyclone 18/9 (IBA, Belgien) des Instituts für Radiopharmazie, Dresden-Rossendorf und am CC 18/9 (Efremov Institut, St. Petersburg, Russland) des Turku PET Centre in Turku, Finnland.
Ergebnisse:
Die Bestrahlungen mit dem Cyclone 18/9 wurden mit 12 µA und 16 MeV durchgeführt. Dies führte innerhalb von 30 Minuten zu Ausbeuten von ca. 300 MBq 61Cu (EOB). Am CC 18/9 wurde mit 30 µA, 13 MeV, 30 Minuten gearbeitet. Dabei wurden ebenfalls 330-400 MBq 61Cu (EOB) erzeugt, bei einer Bestrahlungszeit von 3 Stunden bis zu 1150 MBq 61Cu (EOB). Am CC 18/9 wurde eine extrem hohe spezifische Aktivität des 61Cu von über 1000 GBq/µmol erreicht. Demgegenüber fielen die spezifischen Aktivitäten am Cyclone 18/9 deutlich ab, es konnte nur eine spezifische Aktivität von ca. 2 GBq/µmol erzielt werden. Wahrscheinlich tritt in diesem Fall eine Kontamination mit stabilem Kupfer schon während der Bestrahlung auf. Möglicherweise geht diese von der Targethalterung am Zyklotron aus, da sie nicht wie beim CC 18/9 komplett aus Aluminium, sondern größtenteils aus Messing besteht. Bisherige Versuche zum Schutz des Targetträgers und des Targetmaterials vor derartigen Kontaminationen bzw. der Versuch, Kontaminationen während des Trennprozesses zu verhindern, blieben erfolglos.
Schlussfolgerungen:
Die Ergebnisse zeigen, dass es prinzipiell möglich ist, 61Cu mit hoher spezifischer Aktivität mit Hilfe der 64Zn(p,α)61Cu-Reaktion herzustellen. Die genutzte radiochemische Trennmethode bietet sich hervorragend für eine routinemäßige Herstellung von 61Cu an.
  • Lecture (Conference)
    19. Jahrestagung der Arbeitsgemeinschft Radiochemie/Radiopharmazie der DGN, 15.-17.09.2011, Ochsenfurt, D

Publ.-Id: 16231 - Permalink


Materialcharakterisierungen mit Antimaterie: Atomaren Defekten auf der Spur
Wagner, A.;
Materialcharakterisierungen mit Antimaterie: Atomaren Defekten auf der Spur
  • Lecture (others)
    Tagung des Fachausschusses Materialcharakterisierung der Deutschen Gesellschaft für zerstörungsfreie Prüfung e.V., 07.-08.11.2011, Dresden, Deutschland

Publ.-Id: 16230 - Permalink


SiC growth modification and stress reduction in FLASiC assisted liquid phase epitaxy
Pezoldt, J.; Stauden, T.; Morales, F.; Polychroniadis, E. K.; Voelskow, M.; Skorupa, W.;
The defect density of the epitaxial SiC layers on Si result from the high defect density in the seeding layer formed by carbonization of the Si substrate. A method to reduce the defect density is flash lamp annealing. The recrystallisation can be improved if a three layers stack consisting of 3C-SiC/Si/3C-SiC/Si-substrate is used (iFLASiC-process). To improve the recrystallization C, Ge or both elements were added to Si. Ge and C additions to the Si and subsequent FLASiC processing l ead t o a s ubstantial increase o f t he m ass t ransfer. T he g rowth r ate r eached 1 0.0 μm/s. T he a chieved thickening of the lower layer strongly depends on the Si composition and is caused by the modification of the optical properties and the mass transport properties of the Si. Ge incorporation into Si and therefore into the Si melt enhance the mass transport from the upper SiC layer to the lower one. C incorporation into Si increases the available C contributing to SiC growth. Both elements lower the Si band gap increasing light absorption. Beside the growth modification the in plane strain in the 3C-SiC layer turns from tensile strain with a value of 0.0004 in the non buckling case to an in plane compressive strain with a strain value of - 0.0046. Non annealed layers of comparable thickness deposited under the same conditions exhibit tensile residual strain in the range of 0.002 to 0.006. FLASiC is not only able to improve the layer quality but also reduces the residual stress.
Keywords: Flash Lamp Annealing, SiC, Liquid Phase Epitaxy
  • Poster
    subtherm 2011 - International Topical workshop on Subsecond Thermal Processing of Advanced Materials, 25.-27.10.2011, Dresden, BRD

Publ.-Id: 16229 - Permalink


Synchrotron-based X-ray techniques for radioactive materials research: Understanding the chemical behaviour of radionuclides in solution
Ikeda, A.;
Treatment of spent nuclear fuels (SNFs) is one of the critical issues in the world’s nuclear power industry. The international consensus thus far is that the SNFs are supposed to be reprocessed to extract reusable nuclides (e.g., Pu or U) by solvent extraction, or buried deep in the ground to permanently isolate them from human contact. The basic- and applied research related with these SNFs treatments always requires fundamental information on the chemical behaviour of radionuclides in solution, since most chemical processes relevant to the treatment of SNFs (e.g., solvent extraction or geological disposal) occur in solution.
As one of the powerful experimental probes for radioactive materials research, synchrotron-based X-ray techniques have been extensively employed for the last few decades. This seminar will focus on the application of synchrotron-based X-ray methods to the study of radionuclides in solution systems, including the following three sub-topics: (1) X-ray absorption spectroscopy (XAS) and high energy X-ray scattering (HEXS) for characterizing the hydrolytic species of tetravalent cerium (Ce(IV)) in aqueous solution, (2) X-ray absorption spectroscopy for understanding the redox behaviour of actinides in aqueous solution, (3) multiple spectroscopic (XAS and UV-visible-NIR) and quantum chemical approach for acquiring structural information of individual chemical species in the mixed system.
Keywords: Synchrotron, XAS, HEXS, Actinides, Lanthanides, Solution, Spectroscopy
  • Invited lecture (Conferences)
    CLS internal seminar, 23.11.2011, Canadian Light Source, Saskatoon, Canada

Publ.-Id: 16227 - Permalink


ATHLET models for the Emergency Condenser and the Containment Cooling Condenser of the INKA test facility
Hristov, H. V.; Kozmenkov, Y.; Schäfer, F.;
The ATHLET code (GRS®) has been used for the numerical analyses of the EC (Emergency Condenser) and the CCC (Containment Cooling Condenser) performance at the INKA (INtegralversuchsanlage KArlstein) test facility. Three ATHLET 2.2 Cycle A models have been developed: EC, CCC and Integral model.
The EC model predictions for the postulated steady state scenario (EC characteristic curves) were compared with the old simulations (ATHLET 2.1 Cycle A model for of the EC). INKA EC transient run at 45 bar primary pressure was used as second validation step for the assessment of the different ATHLET versions influence on the numerical predictions. The EC ATHLET Cycle 2.2 A model validation was extended further with the transient EC INKA experiment at 80 bar primary pressure.
Technically, the CCC ATHLET model was based on the old CCC ATHLET 2.1 Cycle A one. However, significant improvements have been accomplished in order to make it capable of adequately representing the INKA CCC experimental layout and conditions. Two models have been developed to account for the different sparger designs. Experimental data (information) analyses have been in addition carried out due the initial poor model performance. The CCC ATHLET 2.2 Cycle A model ability to correctly capture the CCC heat transfer and in general the process has been demonstrated. Second CCC ATHLET model has been developed to incorporate the new sparger design. The model has been partly validated against the provided experimental data. While it was able to calculate well the initial stage of the experiment, it failed to represent the final one.
An integral INKA ATHLET model, which includes both the EC and the CCC, has been developed. This model incorporates the CCC one with new sparger design. Two LOCA scenarios have been postulated for the investigation of the EC-CCC performance under the INKA configuration. These scenarios include RPV (Reactor Pressure Vessel) and RSL (Reactor Steam Line) break. The EC – CCC joined operation under the break scenarios has been analysed.

- vertraulich -
Nachfrage bei Dr. S. Kliem
  • Other report
    Dresden: HZDR, 2011
    94 Seiten

Publ.-Id: 16226 - Permalink


Synchrotron radiation-based X-ray diffraction during magnetron co-sputtering of Ni-Ti films
Martins, R. M. S.; Schell, N.; Mahesh, K. K.; Silva, R. J. C.; Braz Fernandes, F. M.;
The study of Ni-Ti shape memory alloy films is of great technological interest for applications in the field of microengineering. They can work as sensors and actuators at the same time. However, there are still important issues unresolved like formation of film texture and its control. Films exhibiting the two-way shape memory effect are also required. A better understanding of the underlying growth mechanisms and their microstructural development requires sophisticated in-situ techniques. A two-magnetron sputter deposition chamber mounted into the six-circle diffractometer of the Rossendorf Beamline at the European Synchrotron Radiation Facility has been used for the processing of the Ni-Ti films. The in-situ x-ray diffraction studies enabled us to identify the different steps of the structural evolution during deposition with a set of parameters as well as to evaluate the effect of changing parameters (Ti target power) during film growth. It has been found that the type of substrate plays an important role for the preferential orientation of sputtered Ni-Ti films. In some cases they exhibit a pronounced depth dependence of their preferential orientations. Amorphous SiO2 and TiN buffer layers have been used to successfully control their crystallographic orientations. This is an important achievement since the texture has a strong influence on the extent of the strain recovery of the Ni-Ti films. The deposition conditions leading to films mainly containing grains with (100) or (110) planes of the B2 phase parallel to the film surface are presented. The deposition of graded Ni-Ti films by changing deliberately the Ti:Ni ratio, thereby altering microstructure and transformation temperatures across the film thickness, has also been performed. The aim has been the optimization of the deposition parameters in order to fabricate films with a “two-way” actuation (films with a combination of superelasticity and shape memory characteristics). It will lead to the development of smaller devices due to an optimal design of microdevices regarding size and weight (i.e., no consideration has to be paid to a resetting spring).
  • Poster
    EUROMAT 2011 (Symposium A54: Shape Memory Alloys (SMA) - Materials and Devices), 14.-15.09.2011, Montpellier, France

Publ.-Id: 16225 - Permalink


Optimising the efficiency of pulsed diode pumped Yb:YAG laser amplifiers for ns pulse generation
Ertel, K.; Banerjee, S.; Mason, P.; Phillips, P.; Siebold, M.; Hernandez-Gomez, C.; Collier, J.;
We present a numerical model of a pulsed, diode-pumped Yb:YAG laser amplifier for the generation of high energy ns-pulses. This model is used to explore how optical-to-optical efficiency depends on factors such as pump duration, pump spectrum, pump intensity, doping concentration, and operating temperature. We put special emphasis on finding ways to achieve high efficiency within the practical limitations imposed by real-world laser systems, such as limited pump brightness and limited damage fluence. We show that a particularly advantageous way of improving efficiency within those constraints is operation at cryogenic temperature. Based on the numerical findings we present a concept for a scalable amplifier based on an end-pumped, cryogenic, gas-cooledmulti-slab architecture.
Keywords: Laser amplifiers; Lasers, pulsed; Lasers, ytterbium; Pumping

Publ.-Id: 16224 - Permalink


Simultaneous time and wavelength resolved spectroscopy under two-colour near infrared and terahertz excitation
Bhattacharyya, J.; Wagner, M.; Zybell, S.; Winnerl, S.; Stehr, D.; Helm, M.; Schneider, H.;
Time and wavelength resolved spectroscopy requires optical sources emitting very short pulses and a fast detection mechanism capable of measuring the evolution of the output spectrum as a function of time. We use table-top Ti:sapphire lasers and a free-electron laser (FEL) emitting ps pulses as excitation sources and a streak camera coupled to a spectrometer for detection. One of the major aspects of this setup is the synchronization of pulses from the two lasers which we describe in detail. Optical properties of the FEL pulses are studied by autocorrelation and electro-optic sampling measurements. We discuss the advantages of using this setup to perform photoluminescence quenching in semiconductor quantum wells and quantum dots. Carrier redistribution due to pulsed excitation in these heterostructures can be investigated directly. Sideband generation in quantum wells is also studied where the intense FEL pulses facilitate the detection of the otherwise weak nonlinear effect.
Keywords: Photoluminescence quenching, streak camera, time and wavelength resolved spectroscopy

Publ.-Id: 16223 - Permalink


Thickness independent magneto-optical coupling constant of nickel films in the visible spectral range
Mok, K. M.; Scarlat, C.; Kovacs, G. J.; Li, L.; Zviagin, V.; McCord, J.; Helm, M.; Schmidt, H.;
Magneto-optical properties of nominally 10, 20, and 30 nm thick ferromagnetic Ni films have been investigated at room temperature by vector-magneto-optical generalized ellipsometry under saturated magnetization conditions in the sample surface plane. The magneto-optical dielectric tensor of Ni has been determined by reflection Mueller matrix ellipsometry in the spectral range from 300 to 1100 nm. Different sets of magnetic field induced Mueller matrix elements enable us to identify the magnetization directions in the sample. The extracted magnetic field and thickness independent magneto-optical coupling constant is useful for modeling the Mueller matrix and complex Kerr angle of magnetized Ni thin films in layered sample systems in dependence of the incident angle of light, wavelength, and magnetization.
Keywords: Mueller matrix, generalized ellipsometry, magneto-optics, nickel

Publ.-Id: 16222 - Permalink


Formation of U(VI) lactate and citrate complexes and their sorption onto Opalinus Clay between 10 and 60°C
Schmeide, K.; Steudtner, R.; Bernhard, G.;
Results to the U(VI) complexation with lactate and citrate and the influence of these ligands on U(VI) sorption onto Opalinus Clay (OPA) (Mont Terri, Switzerland) between 10°C and 60°C are shown.
Keywords: Complexation, sorption, uranium(VI)
  • Poster
    Workshop "HiTAC – High Temperature Aqueous Chemistry", 09.11.2011, Karlsruhe, Germany

Publ.-Id: 16221 - Permalink


Wechselwirkungen von Actiniden mit Biomolekülen
Barkleit, A.;
Die Komplexierung von Uran(VI) und Cm(III) mit den Zellwandkompartimenten Lipopolysaccharid und Peptidoglycan, charakterisiert durch TRLFS, EXAFS und FT-IR, wird dargestellt.
Keywords: uranyl, curium, lipopolysaccharide, peptidoglycan, TRLFS, EXAFS, FT-IR
  • Invited lecture (Conferences)
    2. Workshop zum Innovationsforum Geobiotechnologie, 03.-04.11.2011, Dresden, Deutschland

Publ.-Id: 16220 - Permalink


Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots
Meier, G.; Vogel, A.; Wintz, S.; Gerhardt, T.; Bocklage, L.; Strache, T.; Im, M.-Y.; Fischer, P.; Fassbender, J.ORC; McCord, J.
New concepts of high-density and ultrafast nonvolatile data storage devices involve the controlled motion of magnetic domain walls (DWs) in nanowires [1]. To realize such a device, reproducible and reliable pinning sites for individual DWs are required. Geometric constrictions are widely used to create local confining potentials acting as pinning sites [2]. As an alternative, pinning sites can be induced via a local modification of magnetic properties by ion irradiation [3]. In this case, a variation in the wire geometry on the nanoscale is not required. Implantation of chromium ions into permalloy is known to cause alloying and structural defects which lead to a reduction in the saturation magnetization MS, and the magnetic anisotropy as well as to a change in the exchange constant and the damping parameter [4]. The strength of the pinning potential can be tuned by the chromium ion fluence applied to induce the so-called magnetic soft spots [3].
Micromagnetic simulations, high resolution magnetic transmission soft X-ray microscopy at beamline 6.1.2 of the Advanced Light Source in Berkeley, CA, USA, and electrical measurements of the anisotropic magnetoresistance are employed to characterize the pinning potential which significantly differs for transverse and vortex walls. We demonstrate field-induced DW pinning and depinning as well as reliable DW depinning by single current pulses in a permalloy nanowire containing a square-shaped magnetic soft spot [5]. Lower requirements on the lithography in comparison to geometric constrictions on the nanoscale, a smaller distribution of properties due to parallel processing during implantation, and fine tunability of the pinning potential via the chromium ion fluence make the magnetic soft spots a promising candidate for applications.
Financial support by the Deutsche Forschungsgemeinschaft via Grant Nos. FA314/3-2 and MC9/7-2, the SFB 668 and the GrK 1286 as well as the Forschungs- und Wissenschaftsstiftung Hamburg via the Exzellenzcluster “Nano- Spintronik” is gratefully acknowledged. Operation of the X-ray microscope is supported by the US Department of Energy under Contract No. DE-AC02-05-CH11231.
References: [1] D. A. Allwood, Gang Xiong, M. D. Cooke, C. C. Faulkner, D. Atkinson, N. Vernier, R. P. Cowburn, Science 296, 2003 (2002); S. S. P. Parkin, U. S. Patent No. US 683 400 5 (2004).
[2] M.-Y. Im, L. Bocklage, P. Fischer, and G. Meier, Phys. Rev. Lett. 102, 147204 (2009).
[3] A. Vogel, S. Wintz, J. Kimling, M. Bolte, T. Strache, M. Fritzsche, M.-Y. Im, P. Fischer, G. Meier, and J. Fassbender, IEEE Trans. Mag. 46, 1708 (2010).
[4] J. Fassbender and J. McCord, J. Magn. Magn. Mater. 320, 579 (2008).
[5] A. Vogel, S. Wintz, T. Gerhardt, L. Bocklage, T. Strache, M.-Y. Im, P. Fischer, J. Fassbender, J. McCord, and G. Meier, Appl. Phys. Lett. 98, 202501 (2011).
Keywords: domain wall; soft spot
  • Lecture (Conference)
    56th Annual Conference on Magnetism & Magnetic Materials, 30.10.-03.11.2011, Scottsdale, Arizona, USA

Publ.-Id: 16219 - Permalink


Microorganisms in potential nuclear waste disposal host rocks
Geissler, A.; Moll, H.; Bachvarova, V.; Lütke, L.; Selenska-Pobell, S.; Bernhard, G.;
It is known that microorganisms exist in host rocks of potential nuclear waste disposals. In this talk, some results will be presented from the current project about the microbial diversity in clay (Opalinus clay) and the interactions of dominant microorganisms with actinides. Especially the interactions of a Sporomusa sp. clay isolate with Curium(III) will be shown. In the second part of the talk, some information’s will be given about Halophiles in general and future plans to investigate the microbial diversity in salt rocks.
  • Lecture (Conference)
    ABC Salt Workshop, 07.-08.11.2011, Karlsruhe, Germany

Publ.-Id: 16218 - Permalink


Kinetics and Thermodynamics of Defects and Nanostructures
Posselt, M.;
Computer simulations using classical interatomic potentials are an efficient tool to investigate and understand atomic-level properties and processes in advanced materials. They allow the consideration of length and time scales which are often hardly accessible by experiments. However, the accuracy of the interatomic potentials employed in such type of simulations determines decisively the quality of the obtained results. Therefore, these potentials must be continuously improved and evaluated.
In the talk two applications of atomistic computer simulations are illustrated. The focus is on kinetics and thermodynamics of defects and nanostructures in materials for micro- and nanoelectronics and in structural materials for fission reactors.
The first example deals with the investigation of basic migration mechanisms of mono- and di-(self-)interstitials in Si using molecular dynamics simulations. Both the atomic mobility due to the presence of the defect and the defect mobility itself were determined. The mechanism of di-interstitial migration depends on temperature, in contrast to that of the mono-interstitial.
The subject of the second example is the structure, energetics and thermodynamics of coherent nanoclusters in bcc-Fe containing vacancies, Cu and Ni. For clusters up to a size of 200 monomers (vacancies, Cu and Ni atoms) the most stable configurations at T=0 are determined by Metropolis Monte Carlo simulations and their formation and binding energies are calculated. The temperature-dependent free formation and free binding energies of the nanoclusters are determined by taking into account configurational contributions which are calculated using the Wang-Landau Monte Carlo method.
Keywords: Si, mono-interstitials, di-interstitials, kinetics, Molecular Dynamics, Fe-based alloys, nanoclusters energetics, thermodynamics, Monte-Carlo simulations
  • Lecture (others)
    Seminarvortrag, Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, 24.10.2011, Livermore, USA
  • Lecture (others)
    Seminarvortrag, Materials Science Laboratory, Los Alamos National Laboratory, 27.10.2011, Los Alamos, USA

Publ.-Id: 16217 - Permalink


Structure, Energetics and Thermodynamics of Embedded Nanoclusters
Posselt, M.;
not available, please contact the author
Keywords: embedded nanoclusters, structure, energetics, thermodynamics
  • Lecture (others)
    Seminarvortrag, Department of Mathematical Sciences, Loughborough University, 20.10.2011, Loughborough, UK

Publ.-Id: 16216 - Permalink


Ion-beam mixing in crystalline and amorphous germanium isotope multilayer structures
Bracht, H.; Radek, M.; Kube, R.; Knebel, S.; Posselt, M.; Schmidt, B.; Haller, E.; Bougeard, D.;
Gallium (Ga) implantation induced self-atom mixing in crystalline and amorphous germanium (Ge) is investigated utilizing isotopically controlled Ge multilayer structures grown by molecular beam epitaxy. The distribution of the Ga ions and the ion-beam induced depth-dependent mixing of the isotope structure was determined by means of secondary ion mass spectrometry. Whereas the distribution of Ga in the crystalline and amorphous Ge is very similar and accurately reproduced by computer simulations based on binary collision approximation (BCA), the ion-beam induced self-atom mixing is found to depend strongly on the state of the Ge structure. The experiments reveal stronger self-atom mixing in crystalline than in amorphous Ge. Atomistic simulations based on BCA reproduce the experimental results only when unphysically low Ge displacement energies are assumed. Analysis of the self-atom mixing induced by silicon implantation confirms the low displacement energy deduced within the BCA approach. This demonstrates that thermal spike mixing contributes significantly to the overall mixing of the Ge isotope structures. The disparity observed in the ion-beam mixing efficiency of crystalline and amorphous Ge indicates different dominant mixing mechanisms. We propose that self-atom mixing in crystalline Ge is mainly controlled by radiation enhanced diffusion during the early stage of mixing before the crystalline structure turns amorphous, whereas in an already amorphous state self-atom mixing is mediated by cooperative diffusion events.
Keywords: ion-beam mixing, germanium, amorphous germanium

Publ.-Id: 16215 - Permalink


A Technology Platform for Translational Research on Laser Driven Particle Accelerators for Radiotherapy
Enghardt, W.; Bussmann, M.; Cowan, T.; Fiedler, F.; Kaluza, M.; Pawelke, J.; Schramm, U.; Sauerbrey, R.; Tünnermann, A.; Baumann, M.;
It is widely accepted that proton or light ion beams may have a high potential for improving cancer cure by means of radiation therapy. However, at present the large dimensions of electromagnetic accelerators prevent particle therapy from being clinically introduced on a broad scale. Therefore, several technological approaches among them laser driven particle acceleration are under investigation.
Parallel to the development of suitable high intensity lasers, research is necessary to transfer laser accelerated particle beams to radiotherapy, since the relevant parameters of laser driven particle beams dramatically differ from those of beams delivered by conventional accelerators: The duty cycle is low, whereas the number of particles and thus the dose rate per pulse are high. Laser accelerated particle beams show a broad energy spectrum and substantial intensity fluctuations from pulse to pulse. These properties may influence the biological efficiency and they require completely new techniques of beam delivery and quality assurance.
For this translational research a new facility is currently constructed on the campus of the university hospital Dresden. It will be connected to the department of radiooncology and host a petawatt laser system delivering an experimental proton beam and a conventional therapeutic proton cyclotron. The cyclotron beam will be delivered on the one hand to an iso-centric gantry for patient treatments and on the other hand to an experimental irradiation site. This way the conventional accelerator will deliver a reference beam for all steps of developing the laser based technology towards clinical applicability.
Keywords: Radiotherapy, photons, electrons, protons, ions, cyclotron, synchrotron, laser particle acceleration
  • Contribution to proceedings
    SPIE Optics + Optoelectronics, 18.-21.04.2011, Czech Republic, Prague
    Proceedings of the SPIE, Vol. 8079, 79681

Publ.-Id: 16214 - Permalink


CFD-Modellierung von Wandsieden und technische Anwendung
Krepper, E.; Rzehak, R.;
Die Verifikation von Auslegungsverbesserungen an Brennelement-Abstandhaltern und ihr Einfluss auf den kritischen Wärmestrom erfordert kostspielige Experimente. Deswegen ist die Ergänzung oder sogar der Ersatz dieser Experimente durch numerische Analysen von großem Interesse. CFD-Modelle haben das Potential der Entwicklung von Modellansätzen unabhängig von der bestimmten Geometrie.
Der Vortrag beschreibt den aktuellen Stand der CFD-Modellierung wan Wandsieden und mögliche Beiträge zur Brennelementauslegung. Mit dem aktuellen Stand ist zumindest die vergleichende qualitative Analyse möglich. Bessere quantitativ zuverlässige Resultate sind mit verbesserten Modellen möglich, die auf CFD-tauglichen Experimenten basieren. Der kürzliche Fortschritt bei der Kopplung des Wandsiedemodells mit einem Populationsbilanzmodell wurde gezeigt. Vieleversprechende Reultate sind mit der in Entwicklung befindlichen schnellen Röntgentomographie zu erwarten.
Keywords: CHF, CFD, mixing vanes, subcooled boiling, fuel assembly design, DEBORA tests, MUSIG model
  • Invited lecture (Conferences)
    Kompaktkurs "Kavitation", 27.-28.10.2011, Dresden, Deutschland

Publ.-Id: 16213 - Permalink


CFD-Modelling of subcooled boiling and their technical application
Krepper, E.; Rzehak, R.;
The verification of design improvements of a fuel assembly of a nuclear reactor core and their influence on the critical heat flux require expensive experiments. Therefore the supplementation or even the replacements of experiments by numerical analyses are of relevant interest in fuel assembly design. The CFD modeling has the potential of simulation independent on the certain geometry.
The presentation describes the actual state of CFX modeling of subcooled boiling and their possible contribution for rod bundle design. The comparative investigation of different designs is possible at least qualitatively. For more quantitatively reliable results the models have to be improved. In the presentation the demands on the accuracy of measured values are established. Most promising results are expected by tomographic methods like by fast X-ray tomography.
Keywords: CHF, CFD, mixing vanes, subcooled boiling, fuel assembly design, DEBORA tests
  • Invited lecture (Conferences)
    ANSYS Conference & 29. CADFEM Users’ Meeting 2011, 19.-21.10.2011, Stuttgart, Deutschland

Publ.-Id: 16212 - Permalink


An analytical solution of the time dependent diffusion equation in a composite slab
Glivici-Cotruta, V.; Merk, B.;
The time-dependent, one-dimensional diffusion equation is solved for a finite slab of two layers. An external source is supplied to one of the layers. The differential equations are subject to the reflecting boundary conditions at the two outer boundary surfaces. The flux and the current density are continuous across the interface between two media. The exact analytical solution is expressed in terms of a Green's function. The solution is developed by the application of the Laplace transformation.
Keywords: Green's function, diffusion, Laplace transformation, composite slab

Publ.-Id: 16211 - Permalink


Terrestrial cosmogenic radionuclides for geomorphology applications
Merchel, S.;
ohne Abstract, eingeladener Vortrag
Keywords: cosmogenic radionuclides, TCN, AMS accelerator mass spectrometry
  • Lecture (others)
    Seminar, School of Geography, Politics and Sociology, 02.11.2011, Newcastle upon Tyne, UK

Publ.-Id: 16210 - Permalink


The Emerging Opportunities of New Multimeric Cyclam Based Copper Chelators in Multimodal Imaging
Kubeil, M.;
kein Abstract verfügbar
  • Lecture (Conference)
    8th Supraphone Meeting, 07.-10.09.2011, Funchal, Portugal

Publ.-Id: 16209 - Permalink


Radioaktive Substanzen helfen beim Suchen und Zerstören von Tumoren
Kubeil, M.;
Der Vortrag bietet eine Übersicht und befasst sich mit den Möglichkeiten und der Bedeutung von Radiopharmaka hinsichtlich ihres Einsatzes für die nuklearmedizinische Diagnostik und Therapie von Krebserkrankungen.
  • Lecture (others)
    Dresdner Lange Nacht der Wissenschaften, 01.07.2011, Dresden, D

Publ.-Id: 16208 - Permalink


Radiopharmazie am Helmholtz-Zentrum Dresden-Rossendorf
Kubeil, M.;
kein Abstract verfügbar
  • Lecture (others)
    Patiententag im Ärztehaus, 04.05.2011, Sebnitz, D

Publ.-Id: 16207 - Permalink


Cyclampropionsäure-Derivate: Neue Chelatsysteme für nuklearmedizinische Anwendungen?
Kubeil, M.; Lehmann, T.; Stephan, H.; Steinbach, J.;
Die Entwicklung von mehrfunktionellen Komplexbildnern für Radiometallnuklide im Hinblick auf eine medizinische Anwendung stellt ein intensiv bearbeitetes Forschungsgebiet dar. Als sehr interessant erweisen sich makrocyclische Tetraamin-Systeme, die eine Mehrfachfunktionalisierung mit löslichkeitsvermittelnden, fluoreszierenden und zielsuchenden Einheiten am selben Molekülkern gestatten. Komplexe des 1,4,8,11-Tetraazacyclotetradecans (Cyclam) mit radioaktiven Kupferisotopen nehmen einen besonderen Stellenwert ein, da diese eine hohe thermodynamische Stabilität aufweisen, kinetisch inert sind und den Zugang zur nuklearmedizinischen Radiodiagnostik (64Cu) sowie Radiotherapie (67Cu) eröffnen.
Umfangreiche Untersuchungen zur Anwendung in der Radiopharmazie sind bisher zu Essigsäure-Derivaten des Cyclams - insbesondere zum 1,4,8,11-Tetraessigsäure-1,4,8,11-tetraazacyclotetradecan (TETA) - durchgeführt worden [1, 2]. Demgegenüber sind Propionsäure-Derivate I - IV in diesem Zusammenhang wenig untersucht [3]. Wir konnten zeigen, dass die Cyclamtetrapropionsäure IV unter physiologischen Bedingungen sehr stabile Komplexe mit 64CuII bildet und durch Kupplung von spezifischen Peptiden an dieses Ligandgerüst ein Targeting in biologischen Systemen möglich ist [4].

Es werden die Synthese von Cyclampropionsäure-Derivaten vorgestellt sowie koordinations- und radiochemische Aspekte dieser Liganden mit CuII diskutiert.

Literatur:

[1] R. Delgado, V. Felix, L. M. P. Lima, D. W. Price, Dalton Trans. 2007, 2734-2745.
[2] X. Liang, P. J. Sadler, Chem. Soc. Rev. 2004, 33, 246-266.
[3] M. Kuhlmann, H. Stephan, J. Steinbach, A. Röhrich, In “Technetium and other Radiometals in Chemistry and Medicine“, U. Mazzi, W. C. Eckelman, W. A. Volkert (Eds.), SGE Editoriali, Padova, Italy, 2010, 77-80.
[4] A. Röhrich, R. Bergmann, A. Kretzschmann, S. Noll, J. Steinbach, J. Pietzsch, H. Stephan J. Inorg. Biochem. 2011, submitted.
  • Lecture (Conference)
    GDCh-Wissenschaftsforum Chemie 2011, 04.-07.09.2011, Bremen, D

Publ.-Id: 16206 - Permalink


Nanomaterials: Applications in Cancer Imaging and Therapy
Stephan, H.;
kein Abstract verfügbar
  • Lecture (Conference)
    8th SUPRAPHONE Meeting, 07.-10.09.2011, Funchal, Portugal
  • Invited lecture (Conferences)
    Seminar, Beijing Normal University, College of Chemistry, 23.04.2013, Beijing, China

Publ.-Id: 16205 - Permalink


Pyridin-haltige Liganden des 1,4,7-Triazacyclononans (TACN): Vielseitig einsetzbare bifunktionelle Chelatoren für Radiokupfer
Stephan, H.; Ruffani, A.; Steinbach, J.;
Dreizähnige makrocyclische Liganden auf der Basis des 1,4,7-Triazacyclononans (TACN) bilden mit Metallionen Koordinationsverbindungen sehr hoher Stabilität. Aufgrund der kleinen Ringgröße des Makrocyclus sind die Zentralionen außerhalb der Ringebene in der Weise angeordnet, dass die Donoratome eine maximale Überlappung der Bindungsorbitale gestatten [1]. Dadurch wird eine hohe thermodynamische Stabilität bei gleichzeitig schneller Komplexbildungskinetik erzielt. Derartige Liganden weisen damit günstige Eigenschaften für einen Einsatz in der nuklearmedizinischen Diagnostik und Therapie auf. Der bekannteste Vertreter ist hier der hexadentate Ligand 1,4,7-Triessigsäure-1,4,7-triazacyclononan (NOTA), der sehr stabile Komplexe mit Radionukliden der dreiwertigen Metalle GaIII, InIII und YIII bildet, aber auch in der Diskussion für CuII ist [2].
Wir konnten zeigen, dass insbesondere Pyridin-haltige Derivate des TACN I sehr stabile Komplexe mit dem Radionuklid 64CuII bilden und damit nach entprechender Funktionalisierung mit spezifischen Peptiden und Proteinen in der nuklearmedizinischen Diagnostik eingesetzt werden können [3].
Es werden Arbeiten zur Synthese von kupplungsfähigen Markierungsbausteinen Ia – Ic sowie Konjugationsreaktionen mit geeigneten Biomolekülen vorgestellt. Der Einfluss von Pyridineinheiten auf die Koordinationsgeometrie und Stabilität von CuII-Komplexen sowie die Eignung ausgewählter radioaktiv markierter Komplexe für die Tumordiagnostik werden diskutiert.

Literatur:
[1] P. Chaudhuri, K. Wieghardt, Prog. Inorg. Chem. 1987, 37, 329-436.
[2] T. J. Wadas, E. H. Wong, G. R. Weisman, C. J. Anderson, Chem. Rev. 2010, 110, 2858-2902.
[3] G. Gasser, L. Tjioe, B. Graham, M. J. Belousoff, S. Juran,, M. Walther, J.-U. Künstler, R. Bergmann, H. Stephan, L. Spiccia, Bioconjugate Chem. 2008, 19, 719-730.
  • Lecture (Conference)
    GDCh-Wissenschaftsforum Chemie 2011 , 04.-07.09.2011, Bremen, D

Publ.-Id: 16204 - Permalink


Copper-mediated cross-linking of S100A4, but not of S100A2, results in proinflammatory effects in melanoma cells
Haase-Kohn, C.; Wolf, S.; Lenk, J.; Pietzsch, J.;
The aim of this study was to investigate the response to and the physiological consequences of copper-mediated cross-linking of S100A2 and S100A4, two members of the S100 family of EF-hand calcium-binding proteins. As demonstrated by electrophoresis and mass spectrometry techniques S100A2 and S100A4 show formation of cross-links due to copper-mediated oxidation of cysteine residues. For S100A4, but not for S100A2, this results in both increased activation of NFκB and secretion of TNF-α in human A375 and, to a higher extent, in RAGE-transfected melanoma cells. The data suggest that a prooxidative tumor microenvironment enhances proinflammatory and prometastatic action of S100A4.

Publ.-Id: 16203 - Permalink


Production of 61Cu via the 64Zn(p,α)61Cu reaction with high specific activity
Thieme, S.; Walther, M.; Rajander, J.; Pietzsch, H.-J.; Solin, O.; Steinbach, J.;
Objectives:
Optimized production and separation parameters, use of only ultra-pure reagents with ppt-levels of metal traces are necessary for the production of high specific activities (SA) 61Cu. From previous studies regarding production of 61Cu there is little data on SA published. McCarthy et al. [1] measured SA ranging from 47 to 190 GBq/µmol for 61Cu produced via 61Ni(p,n)61Cu and 60Ni(d,n)61Cu reaction. An alternative method for production is the use of the 64Zn(p,α)61Cu reaction [2]. The use of 99% enriched 64Zn is considerably cheaper than use of enriched 61Ni.
Methods:
A target setup was developed using approximately 100 mg enriched 64Zn electroplated on a massive gold disk for proton irradiation. The radiochemical separation technique included recycling of the target material and was based on ion exchange methods described in the literature [3-8]. It consisted of a system of cation and anion exchange columns. This ion exchanger cascade included a twofold cation exchange step developed for effective removal of gallium by-products (66/67/68Ga) and one anion exchange step to separate 61Cu from the target material. This separation procedure took one hour. After the recycling procedure for the target material a new electrodeposition of the 64Zn could be carried out. The method used small ion exchange columns, aqueous hydrochloric acid solutions and is described in detail by Thieme et al. [2]. The SA was evaluated by TETA binding assay with radio TLC. Two different cyclotrons were used for the irradiations: a Cyclone 18/9 (IBA, Belgium) at the Insitute of Radiopharmacy in Dresden-Rossendorf with a home-made solid target holder and a CC 18/9 (Efremov Institute, St. Petersburg, Russia) at Turku PET Centre in Turku also with a home-made solid target holder.
Results:
With the Cyclone 18/9 the irradiations were performed with 12 µA of 16 MeV protons on target for 30 min and yielded about 300 MBq 61Cu at EOB. The CC 18/9 irradiations with 30 µA of 13 MeV protons on target for 30 min yielded 330-400 MBq 61Cu, and with 3 hours 1150 MBq 61Cu, respectively. SA of 500 GBq/µmol were achieved with the CC 18/9 which is equipped with a solid target holder completely made of aluminum preventing contamination of the target disk with non-radioactive copper. Compared to the low specific activities, less than 1 GBq/µmol was achieved at the Cyclone 18/9. This low SA is most likely caused by contamination with non-radioactive copper from the currently used solid target holder containing brass/copper parts.
Conclusions:
These results show the possibility to produce high SA 61Cu (SA up to 500 GBq/µmol) via the 64Zn(p,α)61Cu reaction at low proton energies. Together with the used radiochemical separation method it is possible to produce high quality 61Cu routinely.
  • Poster
    19th International Symposium on Radiopharmaceutical Scieneces (ISRS), 28.08.-02.09.2011, Amsterdam, Niederlande
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals 54(2011), S237

Publ.-Id: 16202 - Permalink


H-F hydrogen bonds as synthons in polymeric quantum magnets
Beyer, R.; Manson, J. L.; Schlueter, J. A.; Wosnitza, J.;
es hat kein Abstract vorgelegen
  • Poster
    2nd EuroMagNET Summer School, 05.-11.09.2010, Ameland, The Netherlands
  • Poster
    Phd Seminar, 22.-24.09.2010, Meissen, Deutschland

Publ.-Id: 16201 - Permalink


Magnetization in Magnetic Molecules
Kampert, E.;
es hat kein Abstract vorgelegen
  • Invited lecture (Conferences)
    2nd EuroMagNET Summer School, 05.-11.09.2010, Ameland, The Netherlands

Publ.-Id: 16200 - Permalink


THz-range free-electron laser ESR spectroscopy: techniques and applicatons in high magnetic fields
Ozerov, M.; Cizmar, E.; Kamensky, D.; Zherlitsyn, S.; Herrmannsdörfer, T.; Wosnitza, J.; Zvyagin, S. A.; Wünsch, R.; Seidel, W.;
es hat kein Abstract vorgelegen
  • Lecture (Conference)
    2nd EuroMagNET Summer School, 05.-11.09.2010, Ameland, The Netherlands

Publ.-Id: 16199 - Permalink


Specific Heat at mK Temperatures and DC fields up to 16 T
Götze, K.; Wolff-Fabris, F.; Uhlarz, M.; Wosnitza, J.;
es hat kein Abstract vorgelegen
  • Poster
    Phd Seminar, 22.-24.09.2010, Krögis, Deutschland

Publ.-Id: 16198 - Permalink


Magnetic quantum oscillations in the normal and superconducting state of borocarbide superconductors
Bergk, B.;
es hat kein Abstract vorgelegen
  • Lecture (Conference)
    22. Edgar Lüscher-Seminar, 12.-18.02.2011, Klosters, Switzerland

Publ.-Id: 16197 - Permalink


De Haas-van Alphen investigations of iron pnictides: first results
Wosnitza, J.;
es hat kein Abstract vorgelegen
  • Invited lecture (Conferences)
    Kick-off meeting of the SPP 1458 "High-temperature superconductivity in iron pnictides", 24.-25.02.2011, Dresden, Deutschland

Publ.-Id: 16196 - Permalink


Research at High Magnetic Fields
Wosnitza, J.;
es hat kein Abstract vorgelegen
  • Invited lecture (Conferences)
    22. Edgar Lüscher-Seminar, 12.-18.02.2011, Klosters, Switzerland

Publ.-Id: 16195 - Permalink


Activities at the Dresden High Magnetic Field Laboratory
Wosnitza, J.;
es hat kein Abstract vorgelegen
  • Invited lecture (Conferences)
    HGF-PNI Workshop at the Helmholtz-Zentrum Berlin, 17.01.2011, Berlin, Deutschland

Publ.-Id: 16194 - Permalink


Fluctuation conductivity in melt-textured YBaCuO samples under low magnetic fields
Dias, F. T.; Vieira, V. N.; Pureur, P.; Rodrigues Jr., P.; Obradors, X.; Wolff-Fabris, F.;
We have studied thermal fluctuations of the electrical conductivity in melt-textured YBa2Cu3O7 (YBCO) samples under low magnetic fields. Measurements were performed either for current applied parallel or perpendicular to the c-axis and fluctuation conductivity was studied in the proximity of the superconducting transition. Two melt processed samples were prepared with different concentrations of Y2Ba1Cu1O5 (Y211) phase. For the sample with lower concentration, 3D-Gaussian and genuine critical 3D-XY-E fluctuation regimes were identified in the conductivity parallel to the ab plane and a regime beyond 3D-XY was also observed. The 3D-XY-E scaling was also identified in the fluctuation conductivity along the c-axis. In the sample with higher concentration of the Y211 phase, disorder effects are relevant. The results indicate that the superconducting state in YBCO has a three-dimensional character, and suggest the presence of a sub-dominant order-parameter component that has an appreciable projection along the c-axis.

Publ.-Id: 16193 - Permalink


Enhanced magnetic properties of Bi-substituted cobalt ferrites
Franco, J. A.; Machado, F. L. A.; Zapf, V. S.; Wolff-Fabris, F.;
In this paper we present a magnetic study of Co1-xBixFe2O4 nanoparticles obtained by applying magnetic fields up to 14 T and for temperatures in the range of 5 to 340 K. Hysteresis loops yield a saturation magnetization (Ms), coercive field (Hc), and remanent magnetization (Mr) that vary significantly with temperature and bismuth content. The T-dependence of Ms obtained for H = 5 T presents a maximum at 150 K and a minimum at 25 K that are also dependent on the value of x. However, for H = 14 T, this anomalous behavior disappears and the magnetization smoothly approaches saturation down to 5 K. The magnetic cubic anisotropy constant for different Bi contents, determined by a “law of approach” to saturation, was found to be smaller than those values for pure cobalt ferrite nanoparticles and strongly dependent on temperature. A discussion on the implications of the anomalous behavior in the determination of the anisotropy constant in these sample materials is also presented.
  • Journal of Applied Physics 109(2011), 07A745

Publ.-Id: 16192 - Permalink


In situ monitoring of convection effects on segregation freckle formation
Shevchenko, N.; Eckert, S.; Boden, S.; Gerbeth, G.;
Visualizations of the solidification process were obtained by means of X-ray radioscopy within a Hele-Shaw cell filled with Ga-25wt%In alloy. The complete temperature field was measured in additional experiments by an infrared camera (Trotec IC 080 LV). The evolution of segregation channels (so-called ‘chimneys’) and microstructure of mushy zone was investigated and convection effects were highlighted. In the case of thermo-solutal convection the probability of chimney formation depends sensitively on variations of the horizontal temperature distribution. The temperature difference between the central part and the periphery of the solidification cell may cause a modification of the natural circulation inside the melt.
The second part of this study concerns the case when the natural convection is superimposed by an electromagnetically driven flow perpendicular to the dendrites growth direction. The main effects of forced melt flow are a modification of the dendritic structure and flow-induced redistribution of the solute concentration.
A quantitative assessment of the melt convection directly at the solid-liquid interface was obtained by applying the optical flow approach, which provided information about the velocity field. This quantitative analysis and experimental data of flow field and temperature distribution gives a better understanding of the interplay be-tween melt flow and solidification process.
Keywords: solidification, X-ray radiography, melt convection, segregation
  • Lecture (Conference)
    Modeling of Casting, Welding and Advanced Solidification Processes 2012 (MCWASP XIII), 17.-22.06.2011, Schladming, Österreich
  • Open Access LogoIOP Conference Series: Materials Science and Engineering 33(2012), 012035
    DOI: 10.1088/1757-899X/33/1/012035

Publ.-Id: 16191 - Permalink


Research at High Magnetic Fields - Activities at the Dresden High Magnetic Field Laboratory
Wosnitza, J.;
High magnetic fields are one of the most powerful tools available to scientists for the study, modification, and control of the state of matter. The application of magnetic fields, therefore, has become a commonly used instrument in condensed-matter physics. For the observation of many phenomena very high magnetic fields are es-sential. Consequently, the demand for the highest possible magnetic-field strengths is increasing. At the Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden, HLD), that in 2007 has opened its doors for external users, pulsed magnetic fields up to about 72 T are readily available and a European record field of 87.2 T has been reached. The laboratory has set the ambitious goal of reaching 100 T on a 10 ms timescale. As a unique feature, a free-electron-laser facility next door allows high-brilliance radiation to be fed into the pulsed field cells of the HLD, thus making possible high-field magneto-optical experiments in the range 3-250 µm. Cryotech-niques and different sample probes for a broad range of experimental techniques custom designed for the pulsed magnets are available for users. In-house research of the HLD focuses on electronic properties of strongly correlated materials at high magnetic fields. Besides introducing some highlights of the HLD experimental infra-structure, some recent scientific research results will be presented. This includes the determination of the doping-dependent evolution of the Fermi surface of elec-tron-doped high-temperature superconductors by means of Shubnikov de Haas measurements. The observed reconstruction of the Fermi surface gives evidence for the existence of a superlattice potential, the origin of which is still under debate. Fur-ther, the recently found evidence for the Fulde Ferrell Larkin Ovchinnikov state in an organic superconductor will be presented. Emphasis will be laid on such examples where neutron research at high fields might be able to contribute in unravelling topical open questions.
  • Invited lecture (Conferences)
    Workshop "Present Status and Perspectives of Neutron Research in High Magnetic Fields", 31.03.-01.04.2011, Berlin, Deutschland

Publ.-Id: 16190 - Permalink


Adjustment and verification of macroscopic melt flow during solidi-fication by means of various AC magnetic fields
Eckert, S.; Räbiger, D.; Vogt, T.; Gerbeth, G.;
AC magnetic fields unlock an enormous potential to realize a variety of flow structures in molten metals, which makes the electromagnetic stirring attractive for control-ling the melt flow during solidification. Many studies have shown that beneficial effects like a distinct grain refinement or the promotion of a transition from a columnar to an equiaxed dendritic growth (CET) can be obtained. However, electromagnetically-driven melt convection may also produce segregation freckles on the macro-scale especially in solute-rich alloys showing different equilibrium concentrations of solute in the mixed crystal and the surrounding melt. The achievement of superior casting structures needs a well-aimed control of melt convection during solidification, which in turn requires a detailed knowledge of the flow structures and a profound understanding of the complex interaction between melt flow, temperature and concentration field.
Previous investigations considered the use of time-modulated AC magnetic field to control the heat and mass transfer at the solidification front. It has been shown recently under laboratory conditions, that an accurate tuning of the magnetic field parameters can avoid segregation effects, however, a mismatch of the relevant modulation parameter may lead to worse results. Further investigations in form of numerical simulations accompanied by model experiments are necessary to achieve a quantitative understanding of the effect of fluid flow on the microstructure evolution.
This paper presents an experimental study which at first is focused on obtaining quantitative information about the isothermal flow field exposed to various magnetic field configurations. In a second step solidification experiments are carried out to verify the effect of a certain flow field on the solidification process. Furthermore, a new experimental set-up has been constructed to investigate electromagnetically-driven flows under realistic conditions of directional solidification, in particular the behaviour of the flow pattern in case of a propagating interface.
Keywords: solidification, electromagnetic stirring, rotating magnetic field, flow control
  • Lecture (Conference)
    Modeling of Casting, Welding and Advanced Solidification Processes 2012 (MCWASP XIII), 17.-22.06.2012, Schladming, Österreich
  • Open Access LogoIOP Conference Series: Materials Science and Engineering 33(2012), 012047
    DOI: 10.1088/1757-899X/33/1/012047

Publ.-Id: 16189 - Permalink


Recent Developments at the Dresden High Magnetic Field Laboratory
Wosnitza, J.;
At the Dresden High Magnetic Field Laboratory (Hochfeld-Magnetlabor Dresden, HLD), that in 2007 has opened its doors for external users, pulsed magnetic fields up to 70 T on a timescale of 150 ms as well as 60 T with 1.5 s pulse duration are available and a European record field of 87.2 T has been reached [1,2]. The laboratory has set the ambitious goal of reaching 100 T on a 10 ms timescale. As a unique feature, a free-electron-laser facility next door allows high-brilliance radiation to be fed into the pulsed-field cells of the HLD, thus making possible high-field magneto-optical experiments in the range 3-250 µm. Cryotechniques and different sample probes for a broad range of experimental techniques custom designed for the pulsed magnets are readily available for users. These techniques include magnetization, ultrasound, electron spin resonance, cyclotron resonance, as well as nuclear magnetic resonance and specific-heat measurements. Recent improvements in signal-to-noise ratios allow to resolve relative resistance changes in electrical-transport measurements of about 10-4 [3] and relative length changes in magnetostriction experiments of about 10-7 [4]. In reply to the very strong user demand an extension of the HLD with additional pulse-field cells, capacitor bank, and improved infrastructure will be built starting from 2011. In-house research of the HLD focuses on electronic properties of strongly correlated electron systems at high magnetic fields. Besides introducing some highlights of the HLD experimental infrastructure, some recent scientific research results will be presented.
  • Invited lecture (Conferences)
    2nd International Workshop on Frontier Science in Pulsed Magnetic Fields, 20.-22.04.2011, Wuhan, China

Publ.-Id: 16188 - Permalink


Flow oscillations driven by a rotating magnetic field in liquid metal columns with an upper free surface
Travnikov, V.; Eckert, K.; Nikrityuk, P. A.; Odenbach, S.; Vogt, T.; Eckert, S.;
Oscillatory flow instabilities in a liquid metal cylinder with a free upper surface, exposed to a rotating magnetic field (RMF), are analysed by numerical simulations of the axisymmetric Navier-Stokes equations. The critical Taylor number designating the onset of the oscillatory flow regime decreases with increasing aspect ratio A= H/R while the Taylor-number interval, where the flow oscillations occur, becomes narrower. The instability is initiated near the free surface, where an oscillatory variation of the size and position of the upper vortex in the secondary flow can be observed accompanied by a horizontal oscillation of the azimuthal velocity maximum at the free surface. The predicted flow regimes have been observed in corresponding model experiments with GaInSn using the Ultrasound Doppler Velocimetry (UDV) for flow field measurements. The occurrence of the oscillatory flow regime depends sensitively on the cleanliness of the liquid metal surface.
Keywords: computer simulation, fluid flows, magnetic fields, stirring

Publ.-Id: 16187 - Permalink


Polarization option for the Time-of-Flight Spectrometer FOCUS
Ackermann, R.; Filges, U.; Horisberger, M.; Holitzner, L.; Bollhalder, A.; Keller, P.; Schneider, M.; Stahn, J.; Straessle, T.; Embs, J. P.; Hempelmann, R.;
es hat kein Abstract vorgelegen
  • Poster
    ECNS 2011 (5th European Conference on Neutron Scattering), 19.-22.07.2011, Prague, Czech Republic

Publ.-Id: 16186 - Permalink


Status of the Pulsed-Magnet-Development Program at the Dresden High Magnetic Field Laboratory
Zherlitsyn, S.; Wustmann, B.; Herrmannsdörfer, T.; Wosnitza, J.;
The Dresden High Magnetic Field Laboratory (HLD) is a pulsed-field user facility which offers to researches a variety of experimental techniques combined with nondestructive pulsed magnetic fields. Recently a new, 9.5 MJ dualcoil magnet has been commissioned. This magnet has achieved magnetic field of 91.4 T in a 16 mm bore and it is available for users now. In this paper, we report on some key upgrades in the magnet design which have led to breaking the 90 T limit at the HLD. Further possible design improvements are discussed. In addition, we share our operational experience obtained with the pulsed magnets.
  • Lecture (Conference)
    MT22, 12.-16.09.2011, Marseille, France

Publ.-Id: 16185 - Permalink


Manganese-doped (1-x)BiScO3-xPbTiO3 high-temperature ferroelectrics: Defect structure and mechanism of enhanced electric resistivity
Drahus, M.; Jakes, P.; Erdem, E.; Schaab, S.; Chen, J.; Ozerov, M.; Zvyagin, S.; Eichel, R.;
The effect of multivalency manganese doping on the defect structure and enhanced electrical resistivity is studied for the high-temperature piezoelectric (1 - x)BiScO3-xPbTiO3 (BSPT) solid-solution system by means of multifrequency electron paramagnetic resonance spectroscopy combined with conductivity measurements. The results show that manganese is rather incorporated on a scandium than a titanium site as an isovalent substitute (MnScx) instead of acceptor-type centers, such as Mn(Ti)', Mn(Ti)'', or Mn(Sc)'. The enhanced electric resistivity is found being on the one hand due to the trapping of conduction electrons at the manganese functional center sites (Mn(Sc)(x) + e' -> Mn(Sc)'). On the other hand, through the formation of (Mn(Sc)' - V(O)(center dot center dot))(center dot) defect complexes the ionic conductivity is reduced. Concerning the overall mechanism of charge compensation in that material, both kinds of defects mutually compensate.
  • Physical Review B 84(2011), 064113

Publ.-Id: 16184 - Permalink


Metastable Bi8Ni8S by Reductive Pseudomorphosis of Bi8Ni8SI2
Kaiser, M.; Isaeva, A.; Skrotzki, R.; Schwarz, U.; Ruck, M.;
The bimetallic subsulfide Bi8Ni8S was synthesized by reduction of Bi8Ni8SI2 with n-BuLi. Bi8Ni8S is metastable and decomposes exothermically at about 180°C. In a pseudomorphosis, the shiny black crystals of the precursor were preserved, while the iodide ions were extracted and the pre-formed 1\infinity[Bi8Ni8S] fragments rearranged into a pseudo-hexagonal rod packing [space group Pbam, a = 1750.14(7) pm, b = 1007.7(2) pm, c = 419.6(3) pm]. The rods have an effective diameter of about 1 nm and consist of an outer octagonal tube of bismuth atoms and an inner octagonal tube of nickel atoms. This arrangement markedly resembles the columnar Ta4Te4Si structure type. The difference comes with the disulfide groups that reside on the cen-tral axis. Interatomic distances inside the rods are almost not affected by the reduction, and thus the electronic band structure is not much altered. Yet, the additional electrons raise the Fermi level into a local maximum of the density of states and occupy predominantly antibonding Ni–Ni and S–S states. The dominant Bi–Ni multicenter bonding is accompanied by localized two-center bonds between nickel atoms. The charges of the nickel atoms as well as ELI-D basin populations of Ni– Ni and Ni–Bi bonds change considerably, indicating that the tube is (un)charging quite flexibly and acts as an electron reservoir. In contrast to the iodide precursor, the weak Pauli paramagnetism of Bi8Ni8S is slightly enhanced and spin correlations are observed below 20 K.

Publ.-Id: 16183 - Permalink


Uniaxial R2Co17 Ferrimagnets in High Magnetic Fields
Skourski, Y.; Andreev, A. V.; Kuz’Min, M.; Wosnitza, J.;
Rare-earth intermetallic compounds R2Co17 and R2Fe17 form an interesting group of magnetic materials and their properties have been extensively studied in the last decades. In these compounds, as generally in R-T transition-metal compounds, the strongest interaction is the 3d-3d interaction which primarily determines TC. The 4f-3d interaction, although much weaker than the 3d-3d interaction, is of special importance since it couples the strongly anisotropic R-sublattice moment to that one of much less anisotropic T-sublattice. R2Co17 and R2Fe17 compounds (crystallizing in the hexagonal Th2Ni17-type structure), where R is a heavy rare-earth element, are ferrimagnetic and high magnetic fields are needed to induce changes in the magnetic configuration.
  • Lecture (Conference)
    MISM (Moscow International Symposium on Magnetism), 21.-25.08.2011, Moscow, Russia

Publ.-Id: 16182 - Permalink


Field-Induced Gap in Quantum Spin-1/2 Chains in Strong Magnetic Fields
Zvyagin, S. A.; Ozerov, M.; Wosnitza, J.; Cizmar, E.; Feyerherm, R.; Manmana, S. R.; Mila, F.;
The low-temperature excitation spectrum in copper pyrimidine dinitrate, a spin-1/2 antiferromagnetic chain with alternating g-tensor and Dzyaloshinskii-Moriya interactions that exhibits a eld-induced spin gap, is probed by means of ESR spectroscopy in magnetic elds up to 63 T. In particular, we report on a minimum of the gap in the vicinity of the saturation field Hsat = 48:5 T associated with a transition from the sine-Gordon region (with soliton-breather elementary excitations) to a spin-polarized state (with magnon excitations). This interpretation is fully conrmed by the quantitative agreement over the entire eld range of the experimental data with the DMRG calculations for spin-1/2 Heisenberg chain with a staggered transverse field.
This work was partly supported by the DFG and EuroMagNET II under the EU contract 228043.
  • Poster
    26th International Conference on Low Temperature Physics, 10.-17.08.2011, Beijing, China

Publ.-Id: 16181 - Permalink


Anisotropic Dirac Fermions in a Bi Square Net of SrMnBi2
Park, J.; Lee, G.; Wolff-Fabris, F.; Koh, Y. Y.; Eom, M. J.; Kim, Y. K.; Farhan, M. A.; Jo, Y. J.; Kim, C.; Shim, J. H.; Kim, J. S.;
We report the observation of highly anisotropic Dirac fermions in a Bi square net of SrMnBi2, based on a first-principles calculation, angle-resolved photoemission spectroscopy, and quantum oscillations for high-quality single crystals. We found that the Dirac dispersion is generally induced in the (SrBi)+ layer containing a double-sized Bi square net. In contrast to the commonly observed isotropic Dirac cone, the Dirac cone in SrMnBi2 is highly anisotropic with a large momentum-dependent disparity of Fermi velocities of ~8. These findings demonstrate that a Bi square net, a common building block of various layered pnictides, provides a new platform that hosts highly anisotropic Dirac fermions.
  • Physical Review Letters 107(2011), 126402

Publ.-Id: 16180 - Permalink


Magnetic phase diagram of CeAu2Ge2: High magnetic anisotropy due to crystal electric field
Fritsch, V.; Pfundstein, P.; Schweiss, P.; Kampert, E.; Pilawa, B.; von Löhneysen, H.;
CeAu2Ge2 single crystals (with tetragonal ThCr2Si2 structure) have been grown in Au-Ge flux (AGF) as well as in Sn flux (SF). X-ray powder diffraction and EDX measurements indicate that in the latter case, Sn atoms from the flux are incorporated in the samples, leading to a decrease of the lattice constants by ≈0.3% compared to AGF samples. For both types of samples, a strong anisotropy of the magnetization M for the magnetic field B parallel and perpendicular to the c direction is observed with M||/M⊥ ≈ 6–7 in low fields just above 10 K. This anisotropy is preserved to high fields and temperatures and can be quantitatively explained by crystal electric field effects. Antiferromagnetic ordering sets in around 10 K as previously found for polycrystalline samples. From the magnetization data of our single crystals we obtain the phase diagrams for the AGF and SF samples. The magnetic properties depend strongly on the flux employed. While the AGF samples exhibit a complex behavior indicative of several magnetic transitions, the SF samples adopt a simpler antiferromagnetic structure with a single spin-flop transition. This effect of a more ordered state induced by disorder in form of Sn impurities is qualitatively explained within the anisotropic next-nearest neighbor Ising (ANNNI) model, which assumes ferromagnetic and antiferromagnetic interactions in agreement with the magnetic structure previously inferred from neutron-scattering experiments on polycrystalline CeAu2Ge2 by Loidl et al.
  • Physical Review B 84(2011), 104446

Publ.-Id: 16179 - Permalink


Stacking-order dependent transport properties of trilayer graphene
Jhang, S. H.; Craciun, M. F.; Schmidmeier, S.; Tokumitsu, S.; Russo, S.; Yamamoto, M.; Skourski, Y.; Wosnitza, J.; Tarucha, S.; Eroms, J.; Strunk, C.;
We reportmarkedly different transport properties ofABA- andABC-stacked trilayer graphenes. Our experiments in double-gated trilayer devices provide evidence that a perpendicular electric field opens an energy gap in the ABC trilayer, while it causes the increase of a band overlap in the ABA trilayer. In a perpendicular magnetic field, the ABA trilayer develops quantum Hall plateaus at filling factors of nu = 2,4,6, . . . with a step of Δnu = 2, whereas the inversion-symmetric ABC trilayer exhibits plateaus at nu = 6 and 10 with fourfold spin and valley degeneracy.
  • Physical Review B 84(2011), 161408(R)

Publ.-Id: 16178 - Permalink


Saturation Field of Frustrated Chain Cuprates: Broad Regions of Predominant Interchain Coupling
Nishimoto, S.; Drechsler, S.-L.; Kuzian, R. O.; van den Brink, J.; Richter, J.; Lorenz, W. E. A.; Skourski, Y.; Klingeler, R.; Büchner, B.;
A thermodynamic method to extract the interchain coupling (IC) of spatially anisotropic 2D or 3D spin-1/2 systems from their empirical saturation field Hs(T = 0) is proposed. Using modern theoretical methods we study how Hs is affected by an antiferromagnetic (AFM) IC between frustrated chains described in the J1-J2-spin model with ferromagnetic 1st and AFM 2nd neighbor in-chain exchange. A complex 3D-phase diagram has been found. For Li2CuO2 and Ca2Y2Cu5O10, we show that Hs is solely determined by the IC and predict Hs \apprx 61 T for the latter. With Hs \approx 55 T from magnetization data one reads out a weak IC for Li2CuO2 close to that obtained from inelastic neutron scattering.
  • Physical Review Letters 107(2011), 097201

Publ.-Id: 16177 - Permalink


The impact of heavy Ga doping on superconductivity in germanium
Skrotzki, R.; Herrmannsdörfer, T.; Heera, V.; Fiedler, J.; Mücklich, A.; Helm, M.; Wosnitza, J.;
We report new experimental results on how superconductivity in gallium-doped germanium (Ge:Ga) is influenced by hole concentration and microstructure. Ion implantation and subsequent flash-lamp annealing at various temperatures have been utilized to prepare highly p-doped thin films consisting of nanocrystalline and epitaxially grown sublayers with Ga-peak concentrations of up to 8 at.%. Successive structural investigations were carried out by means of Rutherford-backscattering spectrometry in combination with ion channelling, secondaryion-mass spectrometry, and high-resolution cross-sectional transmission electron microscopy. Hole densities of 1.8·1020 to 5.3·1020 cm-3 (0.4 to 1.2 at.%) were estimated via Hall-effect measurements revealing that only a fraction of the incorporated gallium has been activated electrically to generate free charge carriers. The coincidence of a sufficiently high hole and Ga concentration is required for the formation of a superconducting condensate. Our data reflect a critical hole concentration of around 0.4 at.%. Higher concentrations lead to an increase of Tc from 0.24 to 0.43 K as characterized by electrical-transport measurements. A short mean-free path indicates superconductivity in the dirty limit. In addition, small critical-current densities of max. 20 kA/m2 point to a large impact of the microstructure

Publ.-Id: 16176 - Permalink


Improvement of CBERS-3/4 Imaging Camera Pin-pull Components by Plasma Immersion Ion Implantation
Ueda, M.; Fernandes, B. B.; Mello, C. B.; Lepienski, C. M.; Reuther, H.; Evangelista, S. H.;
Improvement of CBERS-3/4 Imaging Camera Pin-pull Components by Plasma Immersion Ion Implantation
  • Lecture (Conference)
    11th International Workshop on Plasma Based Ion Implantation & Deposition, PBII&D 2011, 08.-12.09.2011, Harbin, China

Publ.-Id: 16175 - Permalink


S100 proteins and RAGE in cancer
Pietzsch, J.;
RAGE, the receptor for advanced glycation endproducts, is a pattern recognition receptor that belongs to the immunoglobulin superfamily. In homeostasis, RAGE is expressed ubiquitously high only in the lung, and moderate to low in a wide range of cells such as endothelial cells, mononuclear phagocytes, smooth muscle cells, mesangial cells, and certain neurons. It is found either as a membrane-bound or soluble protein that is markedly and quickly upregulated by stress in both epithelial and inflammatory cells. RAGE binds multiple ligands, including advanced glycation end products (AGEs), amyloid fibrils, amphoterin, and various members of the S100 family of EF-hand calcium-binding proteins such as S100A4, S100A8/A9, S100A11, S100A12, and S100B. Activation and upregulation through a positive feedback loop of RAGE and, subsequently, perpetual RAGE S100 engagement effects the activation of diverse signaling cascades that initiate and stimulate chronic stress and survival pathways, depending on the distinct interacting S100 protein, environment, and developmental stage. This can result in chronic inflammation and is supposed a setting in which predominantly epithelial malignancies can arise. Therefore, exploring the function of RAGE and its panoply of S100 ligands in the setting of inflammation is critically important in understanding the role of this receptor in carcinogenesis and metastasis, but also in other pathological conditions such as radiation therapy-related vascular dysfunction. In this review, we summarize novel findings on RAGE S100 protein interaction and subsequently triggered signaling cascades from published reports and own ongoing studies. In particular, a comprehensive evaluation of S100 protein metabolism in rodent models using fluorine-18 radiolabeled recombinant S100 proteins and small animal positron emission tomography, further underlining the role of RAGE S100 protein interaction in normal and disease states in vivo, is demonstrated. These recent experiments also support the potential of RAGE and its S100 ligands as attractive theragnostic markers and targets, respectively.
  • Abstract in refereed journal
    Amino Acids 41(2011), S33
  • Invited lecture (Conferences)
    12th International Congress on Amino Acids, Peptides and Proteins, 01.-05.08.2011, Beijing, China

Publ.-Id: 16174 - Permalink


Phosphopeptides with improved cellular uptake properties as ligands for the polo-box domain of polo-like kinase 1
Richter, S.; Neundorf, I.; Loebner, K.; Gräber, M.; Berg, T.; Bergmann, R.; Steinbach, J.; Pietzsch, J.; Wuest, F.;
Human polo-like kinase 1 (Plk1) is involved in cell proliferation and overexpressed in a broad variety of different cancer types. Due to its crucial role in cancerogenesis Plk1 is a potential target for diagnostic and therapeutic applications. Peptidic ligands can specifically interact with the polo-box domain (PBD) of Plk1, a C-terminal located phosphoepitope binding motif. Recently, phosphopeptide MQSpTPL has been identified as ligand with high binding affinity. However, a radiolabeled version of this peptide showed only insufficient cellular uptake. The present study investigated peptide dimers consisting of PBD-targeting phosphopeptide MQSpTPL and a cell-penetrating peptide (CPP) moiety. The new constructs demonstrate superior uptake in different cancer cell-lines compared to the phosphopeptide alone. Furthermore, we could demonstrate binding of phosphopeptide-CPP dimers to PBD of Plk1 making the compounds interesting leads for the development of molecular probes for imaging Plk1 in cancer.
Keywords: Phosphopeptides; Cell-penetrating peptides; Polo-like kinase 1; Polo-box domain; Cellular uptake

Publ.-Id: 16173 - Permalink


Long optical undulators with Traveling-Wave Thomson Scattering towards tunable, high-yield sources in the hard X-ray range
Debus, A.; Steiniger, K.; Siebold, M.; Jochmann, A.; Irman, A.; Bussmann, M.; Schramm, U.; Cowan, T.; Sauerbrey, R.;
Thomson sources, either driven by small linacs or laser-wakefield accelerated (LWFA) electrons are compact in size and can provide ultrashort, hard X-ray pulses of high brilliance. However, the finite Rayleigh length at small interaction diameters makes it increasingly difficult in head-on (180°) Thomson scenarios to avoid higher laser intensities and thus the onset of the nonlinear regime. Effectively, such a geometry limits the peak brilliance of all future Thomson sources.

We present a novel concept, Traveling-wave Thomson scattering (TWTS), which allows obtaining centimeter to meter long optical undulators, where interaction length and diameter are independent of each other. With an ultrashort, high-power laser pulse in an oblique angle scattering geometry using tilted pulse fronts, electrons and laser remain overlapped while both beams travel over distances much longer than the Rayleigh length.
This allows realizing side-scattering in laser-electron beam interactions, without compromises with regard to luminosity or overlap. Furthermore, the smallest achievable scattered bandwidth is controlled by the width of a cylindrically focused laser beam and thus is independent of the ultrashort laser bandwidth. Due to the flexibility in side-scattering angle, photon energies become tunable over a large spectral range without requiring a change in electron energy.

TWTS is particularly interesting for “pink beam” experiments at hard X-rays in which high photon yields in single, ultrashort pulses are needed. Above 100keV photon energy, this approach potentially leads to peak brilliances that are beyond the capabilities of existing synchrotron radiation sources and 2-3 orders of magnitudes higher than in current head-on Thomson scattering designs.

Towards experimental realization, we show how such a Traveling-wave setup has to be implemented. An emphasis is put on the use of varied-line spacing (VLS) gratings for dispersion precompensation of the laser beam at large interaction angles to achieve the required overlap between laser and electrons within the interaction region.
Keywords: Traveling-wave Thomson-scattering, hard X-ray, high brilliance
  • Lecture (Conference)
    RREPS 2011 -- International Symposium "Radiation from Relativistic Electrons in Periodic Structures", 12.-16.09.2011, Diamond light source, RAL, United Kingdom

Publ.-Id: 16172 - Permalink


Cell-based Testing of the Binding affinity of Cetuximab conjugates for Radionuclide marker
Ingargiola, M.; Dittfeld, C.; Zenker, M.; Heldt, J.-M.; Steinbach, J.; Runge, R.; Kotzerke, J.; Kunz-Schughart, L.;
kein Abstract verfügbar
  • Abstract in refereed journal
    Strahlentherapie und Onkologie 187(2011), 95
  • Poster
    17. Jahrestagung der Deutschen Gesellschaft für Radioonkologie (DEGRO), 02.-05.06.2011, Wiesbaden, D

Publ.-Id: 16171 - Permalink


Induction of DNA double-beach breaks via Y-96-DTPA-Cetuximab in human SCC cell lines to establish EGFR-directed tumour inactivating therapies
Kasten-Pisula, U.; Saker, J.; Zenker, M.; Heldt, J.-M.; Baumann, M.; Steinbach, J.; Petersen, C.; Dikomey, E.;
kein Abstract verfügbar
  • Abstract in refereed journal
    Strahlentherapie und Onkologie 187(2011), 58
  • Lecture (Conference)
    17. Jahrestagung der Deutschen Gesellschaft für Radioonkologie (DEGRO), 02.-05.06.2011, Wiesbaden, D

Publ.-Id: 16170 - Permalink


Evaluation of a sensor for measurement of temperature field in mixing processes
Schäfer, T.; Schubert, M.; Hampel, U.;
Chemical processes are often controlled by monitoring pressure and temperature in the process chamber. However, usually these parameters are only available at selected positions, e.g. the inlet and outlet. And they are often not sufficient to operate the processes at the limit, i.e., to ensure high production rates and safety requirements, respectively. The knowledge of temperature fields is even more required if multiphase processes with a high tendency of segregation are considered due to occurrence of dead zones or by-passes.
A sensor concept for two-dimensional measurement of temperature fields for the monitoring of mixing processes was developed and tested. The sensor consists of a 32x32 matrix of small NTC temperature sensors. The measurement electronics is based on a multiplexing driving scheme. This set up enables the measurement of liquid temperatures at the surface of the sensor in each crossing point of the matrix. Applying the new electronic scheme, scanning frequencies up to 100 Hz allow fast temperature measurement to derive conclusions about heat transfer, flow regimes and mixing conditions.
The sensor performance was tested in two experimental setups. Heated phantoms of known geometric shape were applied to study the spatial resolution of the sensor. Furthermore, the 32x32 temperature sensor was installed at the wall of a flat mixing chamber. The flow chamber was fed by two liquid streams of different temperature connected at the inlet ports. Temporal evolution of the mixing temperature and steady-state mixing temperature patterns were observed.
  • Lecture (Conference)
    8th European Congress of Chemical Engineering, 25.-29.09.2011, Berlin, Deutschland
  • Open Access LogoContribution to proceedings
    8th European Congress of Chemical Engineering, 25.-29.09.2011, Berlin, Deutschland, 25.-29.09.2011, Berlin, Deutschland
    Proceedings of the 8th European Congress of Chemical Engineering / 1st European Congress of Applied Biotechnology

Publ.-Id: 16169 - Permalink


The Fulde-Ferrell-Larkin-Ovchinnikov State in Layered Organic Superconductors
Wosnitza, J.;
es hat kein Abstract vorgelegen
  • Lecture (Conference)
    9th International Symposium on Crystalline Organic Metals, Superconductors and Ferromagnets (ISCOM 2011), 25.-30.09.2011, Poznan - Gniezno, Poland
  • Invited lecture (Conferences)
    The 10th International Conference on Research in High Magnetic Fields, 03.-06.07.2012, Wuhan, China

Publ.-Id: 16168 - Permalink


Evidence for a novel superconducting state in layered organic superconductors at high magnetic fields
Wosnitza, J.;
  • Invited lecture (Conferences)
    Humbodt-Kolleg, Cooperation and Networking of Universities and Research Institutes, "study by doing research" - NANO-2011, 07.-09.10.2011, Chisinau, Moldova
  • Invited lecture (Conferences)
    Sino-German Bilateral Workshop on Emergent Phases in Correlated and Topological Matter, 01.-06.04.2012, Hangzhou, China

Publ.-Id: 16167 - Permalink


Irradiation of human melanoma cells: Effects on cellular properties and Eph receptor/ephrin expression
Mosch, B.; Pietzsch, D.; Steinbach, J.; Pietzsch, J.;
X-ray irradiation has an influence on survival and metastatic properties of tumor cells. In turn, metastasis and cellular motility can be modified by EphA2 and EphA3, two members of the Eph receptor/ephrin family of receptor tyrosine kinases. However, links between irradiation, Eph receptor expression and modification of metastasis-relevant cellular properties have not yet been shown. In this study, we irradiated one pre-metastatic and three metastatic human melanoma cells lines, including one self-generated metastatic cell line with X-rays. At day 1 and day 7 post irradiation we analyzed cellular viability, proliferation, motility, adhesion, migration, and clonal growth. Additionally, selected Eph receptors and ephrin ligands were analyzed regarding radiationdependent changes in mRNA and protein content.

In all cell lines a dose-dependent decrease in viability and cell growth for up to 1 week after irradiation was demonstrated. Motility was decreased 1 day after treatment but showed recurrence at 7 days after X-ray. In adhesion to fibronectin, we detected an irradiation-induced increase with similar decrease in migration and clonal growth. Thus, we assume that X-ray acts merely antimetastatic on the investigated melanoma cells. For EphA2 we detected an increase in mRNA in 2 of 3 metastatic cell lines, with simultaneously decreased protein level. EphA3 was found to be upregulated in mRNA and protein in 3 of 4 cell lines. Expression of ephrinA1 and A5 was generally low and seemed unaffected by irradiation.
In conclusion, our data indicate irradiation-induced downregulation of EphA2 and up-regulation of EphA3 in human melanoma cells, leading to anti-metastatic effects such as decreased motility and migration and increased adhesion to fibronectin. Ongoing studies will further clarify underlying mechanisms and the importance of EphA2 and EphA3 in melanoma metastasis.
  • Poster
    14. Jahrestagung der Gesellschaft für Biologische Strahlenforschung, 13.-15.09.2011, Rheinbach, D

Publ.-Id: 16166 - Permalink


Entwicklung von [90Y]Y-CHX-A´´-DTPA-Cetuximab für die kombinierte interne und externe Bestrahlung von Tumoren: Radiochemie und erste in-vivo-Ergebnisse
Heldt, J.-M.; Koi, L.; Zenker, M.; Brüchner, K.; Dittfeld, C.; Bergmann, R.; Mosch, B.; Pietzsch, H.-J.; Pietzsch, J.; Zips, D.; Kunz-Schughart, L. A.; Baumann, M.; Steinbach, J.;
Hintergrund:
Der epidermale Wachstumsfaktor-Rezeptor (EGFR) wird in einer Vielzahl maligner Tumore überexprimiert. Die Hemmung des Rezeptors durch den monoklonalen Antikörper Cetuximab (C225) in Kombination mit fraktionierter Bestrahlung führte bei dieser Tumorentität (prä)klinisch zu einer verbesserten lokalen Tumorkontrolle (1).
Ziel:
Radiochemische Entwicklung, Charakterisierung und Herstellung von [90Y]Y-CHX-A´´-DTPACetuximab ([90Y]C225). Präklinische Evaluierung von [90Y]C225 in Kombination mit externer Bestrahlung. Kann [90Y]C225 die lokale Tumorkontrolle in Mäusen nach externer Bestrahlung weiter verbessern?
Methoden:
CHX-A´´-DTPA wurde über Thioharnstoffkupplung in HEPES-Puffer bei pH 7,2 mit C225 konjugiert. Die Reinigung des Konjugates erfolgte durch Ultrafiltration. Das Chelator-C225-Verhältnis wurde durch MALDI-TOF-MS bestimmt. Die Affinität gegenüber EGFR wurde durchflusszytometrisch ermittelt. Die Radiomarkierung erfolgte in MES-Puffer durch 30-minütige Inkubation mit [90Y/86Y]YCl3 bei pH 6,1 und 30°C. Die radiopharmakologische Charakterisierung erfolgte mittels Ex-vivo-Autoradiographie ([90Y]C225) und Kleintier-Positronen-Emissions-Tomographie ([86Y]C225) nach intravenöser Applikation in NMRI-Nacktmäusen (nu/nu) mit subkutan xenotransplantiertem humanen Plattenepithelkarzinom (FaDu) als Modell. Im Rahmen der Therapieexperimente wurden FaDu-NMRI(nu/nu)-Mäuse mit [90Y]C225 (je 2,8 MBq/13 μg C225 i.v.) und/oder externer Bestrahlung (26, 32 und 38 Gy, 200 kV Röntgen, 0,5 mm Cu-Filter, 1,1 Gy/min, Einzeldosis) behandelt. Endpunkte der Therapieexperimente waren Wachstumsverzögerung und lokale Tumorkontrolle 180 Tage nach externer Bestrahlung.
Ergebnisse:
Es wurden 4 CHX-A´´-DTPA-Moleküle an C225 gekuppelt. Das Konjugat weist mit einem KD-Wert von 0,33 nM im Vergleich zu nativem C225 keinen Affinitätsverlust gegenüber EGFR auf. Bei der Radiomarkierung mit [90Y]YCl3 wurden reproduzierbar spezifische Aktivitäten bis zu 9 GBq/mg C225 und radiochemische Ausbeuten von >95% erzielt. Autoradiographie und PET zeigten 48 h p.i. eine hohe Anreicherung im Tumor. Diese Ergebnisse zeigen, dass das Konjugat für Therapieversuche geeignet ist. Die Kombinationstherapie wurde gut toleriert und es konnten im Vergleich zu den Kontrolltieren histologisch keine Organveränderungen festgestellt werden. Die Tumorkontrolle nach alleiniger externer Bestrahlung zeigt einen klaren Dosiseffekt. Nach 26 Gy externer Bestrahlung war eine signifikant höhere Tumorkontrolle nach Applikation von 13 μg [90Y]C225 im Vergleich zu alleiniger externer Bestrahlung oder zu externer Bestrahlung und unmarkiertem Cetuximab zu verzeichnen.
Referenzen:
(1) Krause et al. Radiother Oncol. 2005 Feb;74(2):109-15
Gefördert durch das BMBF (02NUK006), Kompetenzverbund Strahlenforschung
  • Poster
    14. Jahrestagung der Gesellschaft für biologische Strahlenforschung, 13.-15.09.2011, Rheinbach, D
  • Abstract in refereed journal
    Journal of Labelled Compounds and Radiopharmaceuticals 54(2011), S568

Publ.-Id: 16165 - Permalink


High Molecular Weight Coffee Melanoidins Are Inhibitors for Matrix Metalloproteases
de Marco, L. M.; Fischer, S.; Henle, T.;
High molecular (above 10 kDa) melanoidins isolated from coffee beans of varying roasting degree were found to be efficient inhibitors for the zinc-containing matrix metalloproteases MMP-1, MMP-2, and MMP-9 with IC50 values ranging between 0.2 and 1.1 mg/mL in vitro. The inhibitory potential increased with roasting degree. No or only slight inhibition of other zinc-containing peptidases closely related to MMPs, namely, Clostridium histolyticum collagenase and angiotensin converting enzyme, was found, indicating specific structural features of melanoidins to be responsible for the interaction with MMPs. A continuous increase on the apparent molecular weight of melanoidins as well as incorporation of phenolic substances into the melanoidin structure with progress of roasting was observed, concomitant with a significant increase in the carbon/nitrogen of the melanoidins. This suggests that the melanoidins are mainly formed by incorporation of carbohydrates and phenolic compounds onto a proteinaceous backbone. As MMP-1, MMP-2, and MMP-9 play a pivotal role in pathogenesis of colorectal cancer, studies on possible physiological effects of melanoidins are mandatory.
Keywords: Coffee melanoidins; roasting; Maillard reaction; glycation; polyphenols; matrix metalloproteases; bioactivity
  • Journal of Agricultural and Food Chemistry 59(2011)21, 11417-11423
    DOI: 10.1021/jf202778w

Publ.-Id: 16164 - Permalink


Combined internal and external Radiation Therapy of Tumors: First Results with Y-90-DTPA Cetuximab in FaDu Tumors
Zips, D.; Koi, L.; Bruchner, K.; Zenker, M.; Heldt, J.-M.; Bergmann, R.; Mosch, B.; Pietzsch, H.-J.; Pietzsch, J.; Steinbach, J.; Baumann, M.;
kein Abstract verfügbar
  • Abstract in refereed journal
    Strahlentherapie und Onkologie 187(2011), 55
  • Lecture (Conference)
    17. Jahrestagung der Deutschen Gesellschaft für Radioonkologie (DEGRO), 02.-05.06.2011, Wiesbaden, D

Publ.-Id: 16163 - Permalink


A trigonal nodal SP3 method with mesh refinement capabilities - development and verification
Duerigen, S.; Bilodid, Y.; Fridman, E.; Mittag, S.;
The neutronics model of the nodal reactor dynamics code DYN3D developed for 3D analyses of steady states and transients in Light-Water Reactors has been extended by a simplified P3 (SP3) neutron transport option – to overcome the limitations of the diffusion approach at regions with significant anisotropy effects.
To provide a method being applicable to reactors with hexagonal fuel assemblies and to furthermore allow flexible mesh refinement, the nodal SP3 method has been developed on the basis of a flux expansion in trigonal-z geometry.
In this paper, the derivation of the trigonal SP3 method is presented in a condensed form and a verification of the methodology on quasi-pin level is performed by means of single-assembly test examples. The corresponding pin-wise few-group cross sections were obtained by the deterministic lattice code HELIOS. The power distributions were calculated using both the trigonal DYN3D diffusion and SP3 solver and compared to the HELIOS reference solutions. Close to regions with non-negligible flux anisotropies, e.g., caused by the presence of a strong absorbing material, the power distribution calculated by DYN3D-SP3 shows a significant improvement in comparison to the diffusion method.
Keywords: simplified P3, SP3, nodal method, trigonal, triangular, hexagonal, mesh refinement, pin level
  • Open Access LogoContribution to proceedings
    PHYSOR 2012 Advances in Reactor Physics, 15.-20.04.2012, Knoxville, Tennessee, USA
  • Lecture (Conference)
    PHYSOR 2012 Advances in Reactor Physics, 15.-20.04.2012, Knoxville, Tennessee, USA

Publ.-Id: 16162 - Permalink


The ELBE Control System – 10 Years of Experience with Commercial Control, SCADA and DAQ Environments
Justus, M.; Herbrand, F.; Jainsch, R.; Kretzschmar, N.; Leege, K.-W.; Michel, P.; Schamlott, A.;
The electron accelerator facility ELBE is the central experimental site of the Helmholtz-Zentrum Dresden-Rossendorf, Germany. Experiments with Bremsstrahlung started in 2001 and since that, through a series of expansions and modifications, ELBE has evolved to a 24/7 user facility running a total of seven secondary sources including two IR FELs. As its control system, ELBE uses WinCC on top of a networked PLC architecture. For data acquisition with high temporal resolution, PXI and PC based systems are in use, applying National Instruments hardware and LabVIEW application software. Machine protection systems are based on in-house built digital and analogue hardware. An overview of the system is given, along with an experience report on maintenance, reliability and efforts to keep track with ongoing IT, OS and security developments. Limits of application and new demands imposed by the forthcoming facility upgrade as a centre for high intensity beams (in conjunction with TW/PW femtosecond lasers) are discussed.
Keywords: ELBE, control system
  • Contribution to proceedings
    ICALEPCS 2011 - 13th International Conference on Accelerator and Large Experimental Physics Control Systems, 10.-14.10.2011, Grenoble, France
    Proceedings of the ICALEPCS 2011
  • Poster
    ICALEPCS 2011 - 13th International Conference on Accelerator and Large Experimental Physics Control Systems, 12.10.2011, Grenoble, France

Downloads:

Publ.-Id: 16161 - Permalink


Effect of He+ Irradiation on a Short- Range Order in Fe-Cr Alloys
Dubiel, S. M.; Reuther, H.; Cieslak, J.;
Fe-Cr alloys play an important role both in science and technology. The former stems from their interesting and unique properties which make them to be regarded as model alloys. The latter follows from the fact that they are a basic component of stainless steels (SS) that, thanks to their properties, have been used as construction materials in various branches of industry like power plants or fusion and fission reactors. In these applications they often undergo radiation damage that causes degradation of materials properties. A new generation of SS should provide better characteristics, and, in particular, better resistance to the radiation damage. To achieve this goal, one has to better understand effects caused by the radiation like short-range ordering (SRO).
  • Poster
    31st International Conference on the Applications of the Mössbauer Effect (ICAME2011), 25.-30.09.2011, Kobe, Japan

Publ.-Id: 16160 - Permalink


Chiral QCD sum rules for open-charm mesons
Hilger, T.; Kämpfer, B.; Leupold, S.;
QCD sum rules for chiral partners in the open-charm meson sector are presented at nonzero baryon net density or temperature. We focus on the differences between pseudo-scalar and scalar as well as vector and axial-vector D mesons and derive the corresponding Weinberg-type sum rules. This allows for the identification of such QCD condensates which drive the nondegeneracy of chiral partners in the lowest order of the strong coupling αs and which, therefore, may serve as “order parameters” for chiral restoration (or elements thereof).

Publ.-Id: 16159 - Permalink


Matching 4D Porous Media Fluid Flow GeoPET Data with COMSOL Multiphysics Simulation Results
Lippmann-Pipke, J.; Kulenkampff, J.; Gründig, M.; Richter, M.;
Introduction: Our GeoEPT-method allows the 4D monitoring of transport processes in geological material on laboratory scale (Gründig et al., 2007; Kulenkampff et al., 2008; Richter et al., 2005). We apply COMSOL Multiphysics for reproducing our experiments and extracting parameter sets for our 4D problems. We learn that importing realistic structures from computer tomography (CT) as well as matching our experimental and simulated 4D data sets are complex tasks.

Use of COMSOL Multiphysics: A granite drill core (length = 198 mm, diameter = 50 mm) with a prominent fracture is scanned by means of a medical CT with a spatial resolution of about 1 mm³ (3∙106 voxels, Figure 1, bottom). The data segmentation is conducted with Avizo® Fire under consideration of beam hardening effects. A voxel based fracture geometry is transferred to COMSOL Multiphysics in stl-file format (11 MB, Figure 1, top). After scaling the geometry object and converting it to solid, we allocate the material water to its volume of about 20 ml. First Laminar flow is assigned to the domain and solved stationary. By attributing No slip walls, initial (u = 0, p0 = 0), inflow (u0 = 2∙10-5 m/s) and outflow conditions (p = 0) the experimental conditions are well represented by the model. A user-controlled mesh (free tetrahedral, normal element size) calibrated for Fluid dynamics consists of ~370,000 elements (Figure 2). The stationary flow and pressure field is solved by the GMRES solver in less than four minutes. We add Transport of a diluted species with a Gaussian concentration-input function (standard deviation ~14 min at t = 30 min) for simulating our time dependent experiment (Figure 3). This computing time amounts to additional 23 minutes.

Results: We obtain 4D simulation results covering 10 hours with 10 min resolution. The 4D data sets (Figure 3) as well as breakthrough curves (BTC) are matched with our 4D experimental results obtained in GeoPET experiments (Figure 4). Although effects caused by filter plates at the flange facings were not yet considered in the COMSOL, model the BTC matches fairly well.

Conclusion: The development of algorithms for flow pattern identification, parameterisation of pattern evolution and pattern tracking might allow for quantitative similarity studies of 4D flow and transport processes. In parallel, refining the geometry on the basis of higher resolution CT measurements will help approaching better matches between simulated and measured 4D data sets of flow and transport in heterogeneous geological media.

Outlook: Intermediate and long-term aim of such matching attempts of 4D simulation results with corresponding measurement results is (A) to quantify the effect a simplified geometry from high resolution CT measurements has on the quality of reproducing our real GeoPET flow and transport monitoring results, (B) to quantify the effect a simplified geometry has on the quality of reactive transport in geological material, when additional interactions have to be considered and (C) to evaluate appropriate algorithms for reducing high resolution, high dimension, complex physics models to continuum scale models capable of capturing the relevant processes ruling on the field scale.

References:
Gründig, M., Richter, M., Seese, A. and Sabri, O., 2007. Tomographic radiotracer studies of the spatial distribution of heterogeneous geochemical transport processes. Appl. Geochem., 22: 2334-2343.
Kulenkampff, J., Gründig, M., Richter, M. and Enzmann, F., 2008. Evaluation of positron emission tomography for visualisation of migration processes in geomaterials. Physics and Chemistry of the Earth, 33: 937-942.
Richter, M., Gründig, M., Zieger, K., Seese, A. and Sabri, O., 2005. Positron Emission Tomography for modelling of geochmical transport processes in clay. Radiochim. Acta, 93: 643-651.
  • Lecture (Conference)
    COMSOL Multiphysics Konferenz, 26.-28.10.2011, Stuttgart/Ludwigburg, Deutschland

Publ.-Id: 16158 - Permalink


Neutrons in cultural heritage research
Kockelmann, W.; Chapon, L. C.; Engels, R.; Schelten, J.; Neelmeijer, C.; Walcha, H.-M.; Artioli, G.; Shalev, S.; Perelli-Cippo, E.; Tardocchi, M.; Gorini, G.; Radaelli, P. G.;
Neutron radiation is a highly penetrating probe, routinely used for non-destructive testing of engineering components and for analysis of the structure and dynamics of novel advanced materials. The same analytical techniques can be employed for characterizing objects of art, museum pieces and archaeological findings. In particular, neutron radiography, neutron diffraction and neutron activation analysis provide valuable and complementary information to address questions of provenance, authenticity, fabrication techniques and conservation. This paper surveys some basic concepts and recent applications of neutrons in cultural heritage research at the ISIS neutron spallation source.
Keywords: Cultural heritage, Neutron diffraction, Texture analysis, Prompt gamma activation analysis

Publ.-Id: 16157 - Permalink


Uranium: from geosphere to biosphere
Geipel, G.;
Depleted uranium used a ammunition corrodes in the environment forming mineral phases and then dissolved uranium species like uranium carbonates (Schimmack et al. 2007) and hydroxides. These hydroxide species were contacted with plant cells (canula). After 24 h contact time the cells were fractionated and the uranium speciation in the fraction was determined by TRLFS (time resolved laser-induced fluorescence spectroscopy) at room temperature as well at 120K. It could be shown that the uranium speciation in the fractions is different to that in the nutrient solution. Comparison of the emission bands with literature data allows assignment of the uranium binding forms.
Keywords: Uranium, plant cells, speciation, bioligands
  • Lecture (others)
    Metal Metabolism Seminar (eingeladener Vortrag), 13.10.2011, London, Großbritanien

Publ.-Id: 16156 - Permalink


Direct determination of uranium speciation in eukaryotic cells – challenges and limitations
Geipel, G.; Viehweger, K.; Bernhard, G.;
Application of laser-induced and time-resolved methods allow the direct determination of uranium speciation at extremely low concentrations. This behaviour can be directly observed due to the extraordinary luminescence properties of uranium-(VI).
Some examples for luminescence properties of uranium species relevant to the environment are shown. As for example carbonate species do not show any luminescence behaviour at room temperature cryogenic techniques were applied to decrease the quench processes of the excited species and to determine the uranium speciation. Change of this speciation can be observed due to a change in luminescence properties (emission wavelength and luminescence lifetime). Due to different dependence of the lifetime on temperature for the several uranium species additional luminescence measurements of the prepared solutions at room temperature and in the frozen state give more detailed information about the uranium speciation.
Contact of dissolved uranium with living cells at ambient conditions changes dramatically the uranium speciation. Besides of several organic phosphate binding forms although other uranium species were found as uranium bond to phenolic and thiol groups. Some of them do not emit any luminescence at room temperature. Nevertheless the low temperature measurements allow the assignment of species not fluorescing at room temperature, due to strong dynamic quench effects of H2O molecules and COO- groups. By use of the combined temperature dependent methods for several plant cell compartments we can now assign the uranium speciation in more detail.
Besides this plant cells provide a reducing environment in order to prevent oxidative stress. Due to the redox properties of uranium, it might be possible that uranium-(VI) in a cell matrix is reduced. By laser-induced photo-acoustic spectroscopy we were able to detect also uranium-(IV).
Keywords: Uranium, Cell compartments, speciation
  • Lecture (Conference)
    10th symposium on remediation, 03.-06.10.2011, Jena, Deutschland

Publ.-Id: 16155 - Permalink


Laser-Induced Time-Resolved Luminescence Measurements
Geipel, G.;
First results on luminescence of upconverting Nanoparticles are given
  • Lecture (others)
    Kick-Off Meeting Helmholtz Virtual Institute “Functional Nanomaterials for Multimodality Cancer Imaging”, 06.-07.10.2011, Dresden, Deutschland

Publ.-Id: 16154 - Permalink


Interactions of Biomolecules with Heavy Metals
Geipel, G.; Viehweger, K.;
Heavy metals are explained from a radiochemist’s view. The Interaction of uranium with widespread flavanoids like quercetin have been discussed. Additionally glutathione can be seen as a multifunctional ligand. Information about the binding of uranium is provided. Last not least some onformation about binding forms of uranium in cell compartments of plant cells were given
Keywords: uranium, glutathione, quercetin, cytoplasma
  • Lecture (others)
    Supraphone meeting, 07.-10.09.2011, Funchal, Spanien

Publ.-Id: 16153 - Permalink


Temperature Depending Investigations to the Sorption of Eu(III) on Opalinus Clay
Schott, J.; Acker, M.; Barkleit, A.; Brendler, V.; Taut, S.; Bernhard, G.;
Presently, argillaceous rock formations are under investigation as potential host rocks for nuclear waste repositories. In addition to the diffusion the sorption of radionuclides on mineral phases is an important physicochemical process in a nuclear waste repository in the case of a water inleakage. Concerning the required long-term safety and risk assessment of the storage of high-level radioactive waste the understanding of these processes is essential.
Opalinus Clay (OPA) is a complex composed argillaceous rock. This natural occurring clay rock is discussed as host rock formation for nuclear waste repositories.
In a repository based on argillaceous rock an initial temperature of around 100°C is expected due to the radioactive decay and the release of geothermal energy. But although elevated temperatures are able to influence the sorption behaviour of radionuclides on mineral phases the temperature effect is still investigated insufficiently.
The investigations concentrated on the sorption of Eu(III) on OPA under realistic OPA pore water conditions (pH 7.6, I = 0.4 mol•L-1) up to 50°C. In addition to the temperature dependent investigations the influence of organic matter (tartrate, citrate) on the Eu(III) sorption on OPA was studied up to 50°C.
The Eu(III) sorption is characterized by a very strong sorption to the clay surface. A significant temperature dependency of the Eu(III) sorption was observed. In the presence of tartrate or citrate the Eu(III) sorption decreases with rising ligand concentration. A surface species, most likely a EuCO3 surface species, was detected using TRLFS. The formation of a surface species containing tartrate or citrate was not observed with TRLFS.
Keywords: sorption, Eu(III), Opalinus Clay, temperature, organic matter
  • Contribution to proceedings
    HiTAC-High Temperature Aqueous Chemistry, 09.11.2011, Karlsruhe, Germany
  • Poster
    HiTAC-High Temperature Aqueous Chemistry, 09.11.2011, Karlsruhe, Germany

Publ.-Id: 16152 - Permalink


Spektroskopische Untersuchungen von U(VI) in salinaren Lösungen
Steudtner, R.; Schmeide, K.;
Im Vortrag werden die experimentellen Schwierigkeiten bei der spektroskopischen Charakterisierung von U(VI) in salinaren Lösungen aufgezeigt. Desweiteren wird der Einflusses von der Ionenstärke auf die U(VI)-Komplexierung durch Citronensäure vorgestellt.
Keywords: Speziation - UV/VIS - TRLFS - ATR FT-IR - Komplexierung
  • Lecture (others)
    1. Workshop des Verbundprojekts „Rückhaltung endlagerrelevanter Radionuklide im natürlichen Tongestein und in salinaren Systemen“, 11.-12.10.2011, Dresden, Deutschland

Publ.-Id: 16151 - Permalink


NURESIM - A european simulation platform for nuclear reactor safety: Multi-scale and multi-physics calculations, sensitivity and uncertainy analysis
Chauliac, C.; Aragones, J.-M.; Bestion, D.; Cacuci, D. G.; Crouzet, N.; Weiss, F.-P.; Zimmermann, M. A.;
for Nuclear Reactors called NURESIM is being developed. This development follows a roadmap which is consistent with the SRA (Strategic Research Agenda) of the European SNETP (Sustainable Nuclear Energy Technology Platform). After delivery of two successive versions during the course of the NURESIM project, the numerical simulation platform is presently being developed in the frame of the NURISP European Collaborative Project (FP7), which includes 22 organizations from 14 European countries.
NURESIM intends to be a reference platform providing high quality software tools, physical models, generic functions and assessment results.
The NURESIM platform provides an accurate representation of the physical phenomena by promoting and incorporating the latest advances in core physics, two-phase thermal-hydraulics and fuel modelling. It includes multi-scale and multi-physics features, especially for coupling core physics and thermalhydraulics models for reactor safety. Easy coupling of the different codes and solvers is provided through the use of a common data structure and generic functions (e.g., for interpolation between nonconforming meshes).
More generally, the platform includes generic pre-processing, post-processing and supervision functions through the open-source SALOME software, in order to make the codes more user-friendly.
The platform also provides the informatics environment for testing and comparing different codes. For this purpose, it is essential to permit connection of the codes in a standardized way. The standards are being progressively built, concurrently with the process of developing the platform.
The NURESIM platform and the individual models, solvers and codes are being validated through challenging applications corresponding to nuclear reactor situations, and including reference calculations, experiments and plant data. Quantitative deterministic and statistical sensitivity and uncertainty analyses tools are also developed and provided through the platform.
A Users’ Group of European and non-European countries, including vendors, utilities, TSOs, and additional research organizations (beyond the current partners) has also been established in order to enhance the role of the simulation platform in meeting the needs of the nuclear industry, as applied to current and future nuclear reactors.
This presentation summarizes the achievements and ongoing developments of the simulation platform in core physics, thermal-hydraulics, multi-physics, uncertainties and code integration.
Keywords: NURESIM, SRA, NURISP
  • Nuclear Engineering and Design 241(2011), 3416-3426

Publ.-Id: 16150 - Permalink


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