Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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41875 Publications
Numerical modelling of a transient slug mixing experiment of the ROCOM test facility using CFX-5
Höhne, T.
Abstract
The coolant mixing is of relevance for two classes of accident scenarios boron dilution and cold-water transients. Experimental investigations and numerical simulations of coolant mixing in the downcomer and the lower plenum of PWRs was the topic of the EU-Project FLOMIX-R. The results of the project showed, that coolant mixing has a high relevance for nuclear safety. The coolant mixing is the only inherent mechanism, which reduces risks of power excursions. For the investigation of the relevant mixing phenomena, the Rossendorf test facility ROCOM has been used. ROCOM is a 1:5 scaled Plexiglas model of the PWR Konvoi allowing conductivity measurements by wire mesh sensors and velocity measurements by the LDA technique. Series of experiments were performed at ROCOM to study the mixing of a slug of lower borated water during the start-up of the first main circulation pump.
The CFD calculations were carried out with the code CFX-5. A complex hybrid mesh with the size of 2 million nodes and 4 million elements was used. The turbulence was modeled with the SST model.
Due to the strong momentum insertion during the pump start-up, a dominating horizontal component of the flow was observed near the inlet nozzle leading to a circumferential flow around the core barrel. Therefore, the injected slug is distributed into two main jets, and the maximum of the tracer concentration at the core inlet appears firstly at the location opposite to the loop where the tracer was injected. For turbulent flows the CFD-Code CFX-5 was validated for turbulent, momentum driven mixing. A better description of the mixing processes inside the RPV is the basis of a more realistic safety assessment concerning boron dilution scenarios.
Keywords: Boron Dilution; CFD; Coolant Mixing; PWR
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Lecture (Conference)
The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 3.10.2005, Avignon, France -
Contribution to proceedings
The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 02.-06.10.2005, Avignon, France
CD-ROM, paper 481
Permalink: https://www.hzdr.de/publications/Publ-6959
Numerical modelling of a buoyancy driven flow in a reactor pressure vessel using CFX-5
Höhne, T.; Scheuerer, M.; Kliem, S.
Abstract
The influence of density differences between the primary loop inventory and the Emergency Core Cooling water on the mixing in the downcomer of a Pressurised Water Reactor (PWR) was analyzed at the Rossendorf coolant mixing test facility ROCOM. ROCOM is 1:5 scaled model of a German PWR designed for experimental coolant mixing studies. It is equipped with advanced instrumentation, which delivers high-resolution information characterizing either temperature or boron concentration fields. A series of experiments was performed on mixing under the influence of density differences. Water with higher density was injected into the cold leg of the reactor model. Wire mesh sensors measuring the concentration distribution of a tracer added to the injected water were installed in the upper and the lower part of the downcomer. The data were used for CFD code validation. An experiment with 5% of nominal, constant flow rate in one loop (magnitude of natural circulation) and 10% density difference between ECC and loop water was selected for validation of the CFX-5 code. The turbulence was modeled with the BSL Reynolds stress turbulence model and a mesh with two million control volumes was used.
The results of the experiment as well as of the numerical calculations show, that buoyancy effects dominate the mixing. While at higher mass flow rates (close to nominal conditions) the injected slug propagates mainly in circumferential direction around the core barrel, the buoyancy effect partly suppresses this circumferential propagation. The ECC water falls down in an almost straight streamline and reaches the lower downcomer sensor position directly below the affected inlet nozzle. Therefore, the density effects play an important role during natural convection with ECC injection in PWRs. It was important to point out, that CFX-5 is able to cope the specific flow pattern and mixing phenomena.
Keywords: CFD; Turbulence; Buoyancy Driven Flow; PWR; Coolant Mixing
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Lecture (Conference)
The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 3.10.2005, Avignon, France -
Contribution to proceedings
The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 02.-06.10.2005, Avignon, France
CD-ROM, paper 480
Permalink: https://www.hzdr.de/publications/Publ-6958
Thermochromatographic Adsorption Studies of Curium and Berkelium
Hübener, S.; Eichler, B.; Taut, S.
Abstract
In preparation for thermochromatographic adsorption studies of Lr in metal columns at temperatures up to 2000 K we investigated the metal adsorption of Cm and Bk. Cm was chosen to model Lr as a trivalent metal and Bk as a trivalent actinide having a (divalent) fn+1s2 ground state configuration. 250Bk electroplated on tantalum and 248Bk/246Cm implanted in zirconium foils were used as actinide sources. To carry out an adsorption experiment the actinide sources were placed at the starting position of the thermochromatographic columns and hold for 30 min at 1850 K. Standard enthalpies of adsorption were calculated from the experimental results and compared with calculations using a semi-empirical method. Based on these results, the capability of the method for studying electronic and metallic state properties of the heaviest actinides up to Lr is discussed.
Keywords: heavy actinides; adsorption enthalpies; thermochromatography; metallic state
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Poster
Actinides 2005, 3.-9.7.2005, Manchester, UK -
Contribution to external collection
R. Alvarez, N.D. Bryan, I. May: Recent Advances in Actinide Science, Cambridge: RSC Publishing, 2006, 0-85404-678-X, 287-289
Permalink: https://www.hzdr.de/publications/Publ-6957
Experimental modelling and CFD simulation of air/water flow in a horizontal channel
Vallee, C.; Höhne, T.; Prasser, H.-M.; Sühnel, T.
Abstract
For the investigation of air/water slug flow, a horizontal channel with rectangular cross-section was build at Forschungszentrum Rossendorf. The channel allows the investigation of air/water co- and counter current flows under atmospheric pressure, especially the slug behaviour. Optical measurements were performed with a high-speed camera, and were complemented by simultaneous dynamical pressure measurements.
CFD simulation of the stratified co-current flow was performed using the code CFX-5 applying the two fluid model with the free surface option. The grid contains 400000 control volumes. The tubulence was modeled separately for each phase using the k, w-turbulence model. The results show wave formation up to slug development with closure of the whole channel cross section, where the slug is propagating towards the outlet of the channel with an increasing speed compared to the water velocity and an increase of the pressure level in the channel after the slug front.
The qualitative slug formation in the CFX calculation is in good agreement with the experiment, while the calculated pressure distribution shows higher peak values than the measured one.
Keywords: Multiphase flow; slug flow; CFD; Volume of Fluid model
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Lecture (Conference)
The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 3.10.2005, Avignon, France -
Contribution to proceedings
The 11th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), 02.-06.10.2005, Avignon, France
CD-ROM, paper 479
Permalink: https://www.hzdr.de/publications/Publ-6956
Validation of coupled codes using VVER plant measurements
Vanttola, T.; Hämäläinen, A.; Kliem, S.; Kozmenkov, Y.; Weiß, F.-P.; Kereszturi, A.; Hadek, J.; Strmensky, C.; Stefanova, S.; Kuchin, A.
Abstract
A data set of five transients at different VVER type nuclear power plants was collected in order to validate neutron kinetics/thermal hydraulics codes. Two of these transients drop of control rod at nominal power at Bohunice-3 of VVER-440 type and coast-down of 1 from 3 working MCPs at Kozloduy-6 of VVER-1000 type, were then utilised for code validation. Eight institutes contributed to the validation with 10 calculations using 5 different combinations of coupled codes. The thermal hydraulic codes were ATHLET, SMABRE and RELAP5 and the neutron kinetic codes DYN3D, HEXTRAN, KIKO3D and BIPR8. The general behaviour of both the transients was quite well calculated with all the codes. Even an elementary modelling of coolant mixing in reactor pressure vessel under asymmetric transients improved correspondence to the measurements. Some differences between the calculations seem to indicate that fuel modelling and treatment of VVER-440 control rods need further consideration. The simultaneous validation interacted with the data collection effort and thus improved its quality. The complexity of data collection systems and sometimes conflicting data, however, called for compromises and interpretation guides that also taught the analysts balanced plant modelling.
- Nuclear Engineering and Design 235(2005), 507-519 (2005)
Permalink: https://www.hzdr.de/publications/Publ-6954
Comprehensive uncertainty and sensitivity analysis for coupled code calculations of VVER plant transients
Langenbuch, S.; Krzykacz-Hausmann, B.; Schmidt, K.-D.; Hegyi, G.; Kereszturi, A.; Kliem, S.; Hadek, J.; Danilin, S.; Nikonov, S.; Kuchin, A.
Abstract
The development of coupled codes, combining thermal-hydraulic system codes and 3D neutron kinetics codes, is an important step to perform best-estimate calculations for plant transients of nuclear power plants. For applications in safety analysis, these coupled codes should be validated by benchmark calculations and, preferably, by comparison with plant transient data from operating plants. In addition, the results should be supplemented by applying uncertainty and sensitivity analysis methods, which allow to identify relevant parameters of models and solution procedures affecting the results and to quantify their relative importance. Both objectives were part of the VALCO project. The aspect of validation is presented in [S. Mittag, et al., 2004. Neutron-Kinetic Code Validation against Measurements in the Moscow V-1000 Zero-Power Facility, in press; T. Vanttola et al., 2004. Validation of coupled codes using VVER plant measurements, in press], the aspect of a comprehensive uncertainty and sensitivity analysis for coupled code calculations is the topic of this contribution. The results and experiences obtained by the analysis for two plant transients in a VVER-440 and a VVER-1000, respectively, are presented and discussed.
- Nuclear Engineering and Design 235(2005), 521-540
Permalink: https://www.hzdr.de/publications/Publ-6952
Uranium sorption and solubility under conditions relevant for the radioactive waste repository in Morsleben / Germany
Nebelung, C.; Baraniak, L.
Abstract
Uranium is of great importance for the Morsleben radioactive waste disposal site. Its retention by both backfilling materials and the overlying rock was determined in batch sorption experiments over a period of 400 days. There, the solution simulated the brines typical for this site. The observed retention at the backfilling and overlying rock materials was in the regions of 95.8 to 100% and 92.7 to 98.1%, respectively. The solubility of solid U3O8 in these brines was determined to be between 5*10-9 and 9*10-6 mol/L uranium.
The project was supported by the BfS under the contract No.: 9M 212230-62
Keywords: sorption; solubility; uranium; Morsleben
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Poster
Actinides 2005 Manchester 4th-8th July 2005, conference -
Contribution to external collection
May I., Alvare R, Bryan N: Recent advances in Actinide Science, Cambridge, UK: RSC Publishing, 2006, 978-0-85404-678-2, 110-112
Permalink: https://www.hzdr.de/publications/Publ-6951
Study of the Neptunium(V) Reduction by Various Natural and Synthetic Humic Substances
Schmeide, K.; Geipel, G.; Bernhard, G.
Abstract
The time dependence of the reduction of Np(V) to Np(IV) by various natural and synthetic humic substances was studied under anaerobic conditions between pH 3.5 and pH 9. For Np speciation in solution liquid-liquid extraction, NIR absorption spectroscopy, laser-induced photoacoustic spectroscopy (LIPAS) and ultrafiltration were applied. In comparison to natural humic substances, synthetic humic acids lead to a stronger reduction of Np(V) to Np(IV). The Np(IV) formed in the course of the experiments is stabilized in form of Np(IV) humate complexes, whereas the remaining Np(V) occurs as NpO2+ ion or Np(V) humate depending on pH. The higher reduction potential of the synthetic humic acids can be attributed to their higher phenolic/acidic OH group contents compared to natural humic substances. The influence of phenolic/acidic OH groups on the redox behavior of humic substances was verified applying a synthetic humic acid with blocked phenolic/acidic OH groups.
Keywords: neptunium; pentavalent; tetravalent; humic acid; fulvic acid; complexation; reduction; synthetic; natural
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Contribution to external collection
Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field. Third Technical Progress Report (G. Buckau, ed.), Forschungszentrum Karlsruhe, Wissenschaftliche Berichte FZKA 7070, Karlsruhe, 19-31 (2005).
Permalink: https://www.hzdr.de/publications/Publ-6950
Untersuchungen zur Huminstoffbildung in Gegenwart von Kaolinit
Sachs, S.
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Lecture (others)
Workshop zum Forschungsvorhaben Migration von Actiniden im System Ton, Huminstoff, Aquifer, 11.-12.05.2004, Saarbrücken, Germany
Permalink: https://www.hzdr.de/publications/Publ-6949
Studies on the Redox Behavior of Humic Acids and the Redox Stability of U(VI) Humate Complexes
Sachs, S.
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Lecture (others)
Workshop zum Forschungsvorhaben "Humic Substances in Performance Assessment of Nuclear Waste Disposal : Actinide and Iodine Migration in the Far-Field", 26.-27.04.2004, Budapest, Hungary
Permalink: https://www.hzdr.de/publications/Publ-6948
Solubility Studies of Uranium(IV) by Laser-Induced Breakdown Detection (LIBD)
Opel, K.; Hübener, S.; Weiß, S.; Zänker, H.; Bernhard, G.
Abstract
Uranium plays an important role in the long term safety assessment of nuclear waste repositories. It is therefore necessary to determine its correct thermodynamic data. However, the solubility of tetravalent uranium is not easily to measure because it shows a strong tendency to hydrolyse and to form hydroxides and hydrous oxides of low solubilities. Reported solubility products of U(IV) species are often too high due to the neglection of colloidal particles. Laser-induced breakdown detection (LIBD) provides an opportunity to detect such colloids down to a size of some nanometres at concentrations in the ppt range.
Solutions of U(VI)/HClO4/NaClO4 were reduced in an electrochemical cell under inert gas. The resulting U(IV) solutions were titrated coulometrically. Samples of the solution were pumped into a cuvette and investigated for the presence of colloids by LIBD. The pH of the onset of colloid formation and the U(IV) concentration were used to determine the solubility product of uranium(IV) hydroxide.
Keywords: uranium; solubility product; colloids; LIBD; thermodynamics; anoxic; reduction
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Poster
Actinides 2005 Manchester, 04.-08.07.2005, Manchester, Great Britain -
Contribution to proceedings
Actinides 2005, 04.-08.07.2005, Manchester, Great Britain
Recent Advances in Actinide Science, Editors: May, I., Alvares, R., Bryan, N., Cambridge: The Royal Society of Chemistry 2006, 0-85404-678-X, 119-121
Permalink: https://www.hzdr.de/publications/Publ-6947
18F-Labelling of a potent nonpeptide CCR1 antagonist: Synthesis of 1-(5-chloro-2-{2-[(2R)-4-(4-[18F]fluorobenzyl)-2methylpiperazin-1-yl]-2-oxoethoxy}phenyl)urea in an automated module
Mäding, P.; Füchtner, F.; Johannsen, B.; Steinbach, J.; Hilger, C. S.; Friebe, M.; Halks-Miller, M.; Horuk, R.; Mohan, R.
Abstract
The synthesis of 1-(5-chloro-2-{2-[(2R)-4-(4-[18F]fluorobenzyl)-2methylpiperazin-1-yl]-2-oxoethoxy}phenyl)urea ([18F]4), a potent nonpeptide CCR1 antagonist, is described as a module-assisted two-step one-pot procedure. The final product was obtained utilizing the reductive amination of the formed 4-[18F]fluorobenaldehyde with a piperazine derivative and sodium cyanoborohydride. After HPLC purification of the final product ([18F]4, its solid phase extraction, formulation and sterile filtration, the isolated (not decay-corrected) radiochemical yields of ([18F]4 were between 7 and 13% (n=28). The time of the entire manufacturing process did not exceed 95 min. The radiochemical purity of ([18F]4 was higher than 95%, the chemical purity ≥60% and the enantiomeric purity >99.5%. The specific radioactivity was in the range of 59-226 GBq/µmol at starting radioactivities of 23.6-65.0 GBq ([18F]fluoride
Keywords: positron emission tomography; Alzheimer's disease; 4-[18F]fluorobenzaldehyde; reductive amination; CCR1 antagonist; automated module synthesis
- Journal of Labelled Compounds and Radiopharmaceuticals 49 (2006) 253-262
Permalink: https://www.hzdr.de/publications/Publ-6946
Synthese und Untersuchung von Substraten der viralen Thymidinlkinase und Fluor 18 Markierung geeigneter Verbindungen zum Monitoring der Geneexpression
Grote, M.
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Lecture (others)
Forschungszentrum Jülich, 16.12.2004, Jülich, Germany
Permalink: https://www.hzdr.de/publications/Publ-6945
Rhenium and technetium tricarbonyl complexes anchored by 5-HT1A receptor-binding ligands containing P,O/N donor atom sets
Palma, E.; Correia, J.; Domingos, A.; Santos, I.; Alberto, R.; Spies, H.
Abstract
The (2-methoxyphenyl)piperazine pharmacophore, a part of the WAY 100635 structure, has been functionalized with phosphinoarylbenzylamide or phosphinoarylbenzylamine chelator groups using propylene or hexylene alkyl chains as linkers (L2-L4). These heterofunctionalized phosphines bearing an arylpiperazine moiety have been used to stabilize rhenium tricarbonyl complexes of the type [Re(CO)(3)Br(kappa(2)-L)] (4, L = L2; 5, L = L3; 6, L = L4), which have been fully characterized, including by X-ray crystallographic analysis in the case of compounds 4 and 5. These monomeric complexes are six-coordinate, displaying a distorted octahedral coordination geometry with a facial arrangement of the carbonyl groups. The other three remaining positions are occupied by a bromide and by the bidentate heterofunctionalized phosphine, which coordinates through the phosphorus and the oxygen atom or through the phosphorus and the nitrogen atom in 4 and 5, respectively. The Tc-99m complexes (3a-6a!
) were also prepared and their characterization established by comparative HPLC, using the Re complexes as surrogates. The in vitro binding affinity for the 5HT(1A) receptor subtype and the selectivity against the 5HT(2A) receptors for the rheniurn complexes were determined. Compound 3 is the only one which presents a reasonable affinity and selectively towards 5HT(1A) (IC50 = 20 nM) and 5HT(2A) (IC50 = 4680 nM) receptors, respectively. When the spacer length between the chelate unit and receptor binding domain increased and/or the amide group in the chelator was replaced by a secondary amine unacceptable affinity values for 5HT(1A) receptors (IC50 = 200-1100 nM) and lost of selectivity were observed. (C) 2004 Elsevier B.V. All rights reserved.
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Journal of Organometallic Chemistry 689(2004), 4811-4819
DOI: 10.1016/j.jorganchem.2004.09.051
Cited 23 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-6944
Aktuelle Ergebnisse Fluoreszenzspektroskopischer Untersuchungen an Aktiniden und organischen Liganden
Geipel, G.
Abstract
Es werden neue Messergebnisse zur Fluoreszenz vom Americum(III) vorgestellt. Die Fluoreszenzzerfallszeit liegt im Nanosekundenbereich. Aufgrund der Analogie zum Curium(III) sollte auch beim Americum die Anzahl der Wassermoleküle in der Solvathülle die über die fluoreszenzzerfallskonstante ermittelt werden können. Es erschien aufgrund der Datenlage (Fluoreszenzzerfallszeit) ratsam, frühere Untersuchungen von Kimura zu wiederholen. Vorgestellt werden außerdem Untersuchungen zur Komplexbildung von Neptunium mit Vanillinsäure und von Kupfer(II) mit verschiedenen Dendrimeren.
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Invited lecture (Conferences)
BAM Berlin, 21.12.2004, Berlin, Germany
Permalink: https://www.hzdr.de/publications/Publ-6941
Stability of an electromagnetically levitated spherical sample in a set of coaxial circular loops
Priede, J.; Gerbeth, G.
Abstract
This paper presents a theoretical study of oscillatory and rotational instabilities of a solid spherical body levitated electromagnetically in axisymmetric coils made of coaxial circular loops. We apply our previous theory to analyze the static and dynamic stability of the sample depending on the AC frequency and the position of the sample in the coils for several simple configurations. An original analytical approach is introduced employing a gauge transformation for the vector potential. First we calculate the spring constants which define the frequency of small-amplitude oscillations. For static stability the spring constants must be positive. Dynamic instabilities are characterized by critical AC frequencies which, when exceeded, may result either in a spin-up or oscillations with increasing amplitude. It is found that the critical frequencies increase with the non-uniformity of the field. We show that for a spherically harmonic field the critical frequency for the spin-up instability in a field of degree l coincides with the critical frequency for the oscillatory instability in a field of degree l+1.
- IEEE Transactions on Magnetics 41(2005)6, 2089-2101
Permalink: https://www.hzdr.de/publications/Publ-6940
Untersuchungen zur Bindungsstruktur von kolloidgetragenem Uran mit EXAFS und ATR-FTIR
Ulrich, K.-U.; Foerstendorf, H.; Rossberg, A.; Weiß, S.; Zänker, H.
Abstract
Oxidiertes Uran ist ein mobiler Schadstoff, der auch mit verschiedenen Anionen wie Carbonat oder Sulfat wasserlösliche Komplexe bildet. Uranyl ist aber auch bekannt für seine hohe Affinität zu kolloidalen Fe-Oxyhydroxiden. Derartige Kolloide entfernen bei pH 5 8 sehr effektiv U(VI) aus der Lösung, da sie aufgrund ihrer geringen elektrostati-schen Stabilität leicht agglomerieren. Diese Reaktion kann bei Altlasten aus dem Uran-bergbau die Ausbreitung des Urans verringern, wenn saures Minenwasser z. B. durch Vermischung mit neutralem, oxischem Grundwasser entsäuert wird. Für zuverlässige Vorhersagen der Migration des Urans benötigt man Informationen über die Struktur und Stabilität der Uranbindung auf molekularer Ebene. Art und Struktur der Sorptionsspezies sind bis heute nicht vollständig geklärt.
Hauptziel dieser Arbeit ist die strukturelle Aufklärung der sorptiven Bindung von Uranyl an Kolloide in Bergwerkswässern. Wir untersuchten auch die Mitwirkung der anwesenden Hauptionen Sulfat, Silikat und Carbonat bei der Sorption von Uranyl an das Modellkolloid Ferrihydrit (Fh), um zu prüfen, ob ternäre Oberflächenkomplexe entstehen.
Die EXAFS-Resultate legen nahe, dass Uranyl bei den hier simulierten Bedingungen (pH 5.5) Oberflächenkomplexe mit Ferrihydrit-Kolloiden bildet, an denen Sulfat, Silikat oder Nitrat unbeteiligt sind. Die durch ATR-IR nachgewiesenen U(VI)-Carbonat-Oberflächenkomplexe sind mit EXAFS nicht zu erkennen. Eine mögliche Erklärung wä-re, dass Carbonat monodentat mit Uranyl verknüpft ist. Gegenwärtig prüfen wir, ob ein solcher Komplex mit EXAFS verifiziert werden kann. Unabhängig davon lassen sich die experimentellen EXAFS-Daten durch einen binären Fh=UO22+-Komplex mit neuer räumlicher Anordnung erklären. Zukünftige Untersuchungen befassen sich auch mit der Langzeitstabilität der Uranbindung.
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Contribution to external collection
Tagungsbeitrag Wasserchemische Gesellschaft der GdCH, 02.-04.05.2005, 133 - 137 -
Lecture (Conference)
Tagung der Wasserchemische Gesellschaft der GdCH, 04.05.2005, Bad Mergentheim, Germany
Permalink: https://www.hzdr.de/publications/Publ-6939
CW test of the TTF-III input coupler at Rossendorf
Bauer, S.; Belomestnykh, S.; Buechner, A.; Büttig, H.; Gabriel, F.; Knobloch, J.; Moeller, W.-D.; Pekeler, M.
Abstract
While many laboratories plan to use TESLA-like cavities and/or cryomodules in CW regime, the TTF-III coupler [1] has never been tested in CW mode to find out what is its average power limit and what parts of the coupler would require upgrade/redesign for higher average power operation. ACCEL, BESSY, Cornell, DESY and Rossendorf agreed to collaborate on such a test of the TTF-III coupler. ACCEL manufactured one TTF-III coupler free of charge and assembled it on the test stand in clean-room condition. DESY provided the test stand, some additional hardware and its know-how in testing TTF-III couplers. Cornell provided IR viewports, instrumentation feedthroughs and its expertise and help during the coupler test and tried to coordinate joint efforts. BESSY participated in the test and offered a follow-up test in the new HoBiCaT horizontal test facility [2]. The test happened at Rossendorf at their 10 kWCW klystron test transmitter from June 14 to June 18.
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Other report
ERL - Report ERL 04-10, 2004
Permalink: https://www.hzdr.de/publications/Publ-6938
Operation Experience with the ELBE Helium Plant
Schneider, C.
Abstract
The superconducting linear accelerator ELBE has a 200W at 1.8 K cryogenic plant. Two cold compressors are used for recompression of the Helium at the 4 K level and for stabilising the pressure in the accelerator cryostat. The talk will give an overview over the ELBE cryogenic system and will focus on the operation experience with the cold compressor system and the filling modes of the cryostat. Specific problems of the ELBE Helium plant concerning purity, maintenance and reliability will be discussed.
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Lecture (Conference)
Conference Cryogenics Operations 2004, Jefferson Laboratory, 30.03.-02.04.2004, Newport News, USA
Permalink: https://www.hzdr.de/publications/Publ-6937
Reduced sub-picosecond electron relaxation in GaNAs
Sinning, S.; Dekorsy, T.; Helm, M.; Mussler, G.; Däweritz, L.; Ploog, K. H.
Abstract
We report on time resolved femtosecond carrier dynamics in molecular beam epitaxy (MBE) grown GaNxAs1-x with a nitrogen fraction of 1.3 %. The intraband carrier relaxation time in GaNxAs1-x is found to be significantly larger than in GaAs. We compare the experimental results with carrier ? polar optical phonon scattering rates calculated within the band anticrossing model. From the results we conclude that the slowing down of the carrier relaxation is a result of the strongly modified band structure in GaNxAs1-x.
- Applied Physics Letters 86(2005), 161912
Permalink: https://www.hzdr.de/publications/Publ-6936
RPV investigations of Greifswald WWER-440 units: New dosimetry results and material testing concepts
Konheiser, J.; Rindelhardt, U.; Viehrig, H.-W.
Abstract
The investigation of the well documented different irradiation/annealing states of the four former Greifswald units are a special advantage to assess the reactor pressure vessel integrity and to check the corresponding rules.
The results of new, more accurate calculations of the neutron fluence will be given. Further, the change of the RPV dismantling strategy requires a new approach for the trepanning procedure. The new procedure will be shortly described as well as some aspects of the material investigation program.
Keywords: NPP; reactore pressure vessel; dosimetry
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Contribution to proceedings
Annual meeting on nuclear technology 2005, 10.-12.05.2005, Nürnberg, Germany
CD-ROM, 641
Permalink: https://www.hzdr.de/publications/Publ-6935
Bildung von eisenhaltigen Kolloiden bei der Verwitterung von Gesteinsmaterial
Zänker, H.; Arnold, T.; Hüttig, G.
Abstract
Risikoabschätzungen zur Migration von Schadstoffen durch geologische Formationen über den Wasserpfad unterscheiden zwischen mobilen und immobilen Schadstoffen. Die Schadstoffmobilität kann durch Kolloide beeinflußt werden. Die wichtigste Ursache für anorganische Kolloide in der Natur ist die Präzipitation von Sekundärmineralien. Verschiedene Publikationen existieren bereits zur Sekundärmineralkolloidbildung im Bulk von Wässern durch chemische Reaktionen nach der Mischung von Wässern unterschiedlicher Zusammensetzung oder nach dem Zutritt von Luft zu vorher isolierten Wässern. Die direkte Bildung von eisenhaltigen Sekundärmineralkolloiden an der Gestein-Wasser-Grenzfläche durch die Verwitterung von Gesteinsmaterial ist eine Alternative zum bekannten Kolloidbildungsmechanismus im Bulk von Wässern. Dieser Mechanismus ist von Bedeutung für die Kolloidentstehung bei der Verwitterung von frisch zerkleinertem Gestein in der ungesättigten Zone wie z. B. Gestein in Bergwerkshalden. Auch die nach diesem Mechanismus gebildeten eisenhaltigen Kolloide können den Transport von Schadstoffen beeinflussen, denn sie besitzen eine große spezifische Oberfläche und eine hohe Sorptionsaffinität.
Keywords: Weathering; Colloids; Phyllite; Ferrihydrite; Aluminosilicates; Centrifugation; Unsaturated Zone; Mine Dumps
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Contribution to proceedings
71. Jahrestagung der Wasserchemischen Gesellschaft in der GDCh, 02.-04.05.2005, Bad Megentheim, Germany
Tagungsband, 421 -
Poster
71. Jahrestagung der Wasserchemischen Gesellschaft in der GDCh, 02.-04.05.2005, Bad Mergentheim, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-6934
Modeling and regrowth mechanisms of flash lamp processing of SiC-on-silicon heterostructures
Smith, M.; Mcmahon, R.; Voelskow, M.; Skorupa, W.
Abstract
This paper describes the development of a thermal model for flash lamp processing of 3C-SiC on silicon substrates in the millisecond regime, the FLASiC process. The model is a numerical solution of the enthalpy equation, using a modified implicit Crank-Nicholson scheme to combine accurate prediction of melt depths with reasonable computation times. The model has been calibrated against experiments and then used to compute the temperature distribution in the wafer during annealing. The results show the time and extent of melting as a function of layer thickness, wafer preheat temperature, and pulse intensity and duration. The kinetics of melting and regrowth have also been considered.
Keywords: flash lamp; SiC; annealing; implantation
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Journal of Applied Physics 96(2004)9, 4843-4851
DOI: 10.1063/1.1786650
Cited 39 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-6932
Hochfrequenz-Elektronenquelle
Janssen, D.
Abstract
Der Erfindung liegt die Aufgabe zugrunde, die Erzeugung eines Elektronenstrahls mit einer extrem großen mittlerer Leistung und einer kleinen Emittanz mit einem einfachen HF-Koppler und geringen Kosten bei koaxialer Einkopplung und variabler externer Güte sowie geringer thermischer Belastung des supraleitenden Resonators zu erreichen.
Involved research facilities
- SRF Gun
-
Patent
Patentanmeldung DE 10 2004 055 256.8
Permalink: https://www.hzdr.de/publications/Publ-6931
Kohärente Terahertz-Strahlungsquelle
Dekorsy, T.; Dreyhaupt, A.; Winnerl, S.; Helm, M.
Abstract
Die Strahlungsquelle kann im Frequenzbereich von 10 GHz bis 50 THz arbeiten und spezielle Parameter erfüllen.
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Patent
Patentanmeldung DE 10 2004 046 123.6
Permalink: https://www.hzdr.de/publications/Publ-6929
Insulinresistenz (IR) und Lipoprotein (Lp)-subfraktionen (Sf) bei verschiedenen Graden der Glukosetoleranz (GT)
Weck, A.; Julius, U.; Pietzsch, J.
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Poster
39. Jahrestagung der Deutschen Diabetes-Gesellschaft, Hannover, 19.-22.05.2004 -
Abstract in refereed journal
Diabetes und Stoffwechsel 13(2004), 117
Permalink: https://www.hzdr.de/publications/Publ-6928
Rheumatoid arthritis synovial fluid LDL induce monocyte chemotaxis and adhesion
Pietzsch, J.; Bergmann, R.; Kopprasch, S.
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Poster
74th European Atherosclerosis Society Congress, Seville, 17.-20.04.2004 -
Abstract in refereed journal
Atherosclerosis 5(2004)Suppl. 1, 16
Permalink: https://www.hzdr.de/publications/Publ-6927
Anlage zur gesteuerten Erstarrung von Schmelzen elektrisch leitender Medien
Eckert, S.; Nikrityuk, P.; Grundmann, R.; Eckert, K.
Abstract
Es werden Instabilitäten gedämpft und das Kornwachstum während der Erstarrung von Legierungen gesteuert.
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Patent
Patentanmeldung DE 10 2004 044 637.7
Permalink: https://www.hzdr.de/publications/Publ-6926
Analysis of specific markers of protein oxidation in rheumatoid arthritis plasma and synovial fluid LDL
Pietzsch, J.; Bergmann, R.; Kopprasch, S.
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Poster
74th European Atherosclerosis Society Congress, Seville, Spain, 17.-20.04.2004 -
Abstract in refereed journal
Atherosclerosis 5(2004)Suppl. 1, 16
Permalink: https://www.hzdr.de/publications/Publ-6925
Integration nuklearmedizinischer Bilder in die Bestrahlungsplanung des nichtkleinzelligen Bronchialkarzinoms
Oehme, L.; Hoinkis, C.; Appold, S.; Beuthien-Baumann, B.; Pötzsch, C.; Baumann, M.; Kotzerke, J.
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Poster
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock
Permalink: https://www.hzdr.de/publications/Publ-6924
P0408-Faseroptischer Sensor zur Bestimmung von Stoff- und Phasenverteilungen
Hampel, U.; Schleicher, E.
Abstract
Es ist ein Sensor dargestellt, der in der Lage ist, die Stoffzusammensetzung mittels faseroptischer Refrakometrie an einer Vielzahl räumlicher Punkte eines Untersuchungsvolumens gleichzeitig zu messen, ohne eine Vielzahl von Anordnungen zu verwenden.
-
Patent
Patentanmeldung DE 10 2004 037 883.5
Permalink: https://www.hzdr.de/publications/Publ-6923
Increased LDL apolipoprotein B-100 oxidation in IGT and overt Type 2 diabetes
Julius, U.; Pietzsch, J.
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Poster
64th Scientific Sessions of the American Diabetes Association (ADA), Orlando, USA, 04.-08.06.2004 -
Abstract in refereed journal
Diabetes 53(2004), A231
Permalink: https://www.hzdr.de/publications/Publ-6922
Vorrichtung zur Vermeidung von Druckstößen in Rohrleitungssystemen
Prasser, H.; Dudlik, A.; Apostolidis, A.; Schlüter, S.; Wickl, G.
Abstract
Es wird eine kostengünstig zu realisierende und zuverlässig arbeitende Armatur in Rohrleitungssystemen angegeben.
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Patent
Patentanmeldung DE 10 2004 025 983.6 -
Patent
DE 10 2004 025 983 B4 - 06. Sept. 2007
Permalink: https://www.hzdr.de/publications/Publ-6921
Metallkomplexe auf der Basis von Tetrathiol-Liganden und deren Anwendung in der nuklearmedizinischen Diagnostik und Endoradionuklidtherapie sowie Verfahren zur Herstellung der Metallkomplexe
Heinrich, T.; Johannsen, B.; Pietzsch, H.; Seifert, S.; Spies, H.
Abstract
Es werden radiolytisch und metabolisch stabile Metallkomplexe vorgeschlagen, die zur Konjugation mit Biomolekülen geeignet sind sowie ein Verfahren zu ihrer Herstellung.
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Patent
DE 10 2004 022 461 A1
Permalink: https://www.hzdr.de/publications/Publ-6920
Effect of low density lipoproteins (LDL) isolated from subjects with normal and impaired glucose tolerance on the gene expression of CD36, SR-BI, and PPARγ
Graessler, J.; Westendorf, T.; Kopprasch, S.; Pietzsch, J.; Schroeder, H.
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Poster
74th European Atherosclerosis Society Congress, Seville, 17.-20.04.2004 -
Abstract in refereed journal
Atherosclerosis 5(2004)Suppl. 1, 83
Permalink: https://www.hzdr.de/publications/Publ-6918
Lipoprotein kinetics as measured with stable isotopes in familial combined hyperlipidemia and impaired glucose tolerance
Julius, U.; Pietzsch, J.
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Poster
15th International Symposium on Drugs Affecting Lipid Metabolism (DALM), Venedig , 24.-27.10.2004
Permalink: https://www.hzdr.de/publications/Publ-6917
LDL isolated from subjects with impaired glucose tolerance increase the expression of CD36 and PPARg in macrophages.
Westendorf, T.; Kopprasch, S.; Pietzsch, J.; Graessler, J.
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Poster
15th International Symposium on Drugs Affecting Lipid Metabolism (DALM), Venedig, 24.-27.10.2004
Permalink: https://www.hzdr.de/publications/Publ-6916
Design and biological evaluation of Tc-99m ligands derived from WAY 100635 for serotonin 5-HT1A receptor binding
Drews, A.; Heimbold, I.; Pietzsch, H.-J.; Johannsen, B.
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Contribution to external collection
Development of Tc-99m Agents for Imaging Central Neural System Receptors, IAEA Technical Reports Series no. 426(2004), Wien, Austria
Permalink: https://www.hzdr.de/publications/Publ-6915
Transition metal-mediated C-C and C-N bond forming reactions with the short-lived positron emitters 11C and 18F
Wüst, F.
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Invited lecture (Conferences)
Washington University, School of Medicine St. Louis, 12.10.2004, Washington, USA
Permalink: https://www.hzdr.de/publications/Publ-6914
Radiopharmaceutical Chemistry at the PET Center Rossendorf
Wüst, F.
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Invited lecture (Conferences)
Washington University, School of Medicine St. Louis, 08.10.2004, Washington, USA
Permalink: https://www.hzdr.de/publications/Publ-6913
Positronen-Emissions-Tomographie (PET): Wie radioaktive Substanzen den Körper biochemisch transparent machen
Wüst, F.
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Lecture (others)
Tag der offenen Tür, Forschungszentrum Rossendorf, 18.09.2004, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-6912
PET Radiochemistry and the Potential of PET in Drug Development and Evaluation
Wüst, F.
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Invited lecture (Conferences)
Boehringer Ingelheim, 07.04.2004, Germany
Permalink: https://www.hzdr.de/publications/Publ-6911
Aspekte der PET-Radiochemie in der Lebensmittelchemie
Wüst, F.
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Lecture (others)
1. Workshop Positronen-Emissions-Tomographie in der Lebensmittelforschung, 17.05.2004, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-6910
In vino sanitas. Den Geheimnissen des Weines auf der Spur
Pietzsch, J.
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Lecture (others)
Vortrag zur Langen Nacht der Wissenschaften, 25.06.2004, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-6909
Metabolismus oxidierter Proteine in vivo: Einblicke mit Kleintier-PET-Untersuchungen
Pietzsch, J.
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Lecture (others)
1. Workshop Positronen-Emissions-Tomographie in der Lebensmittelforschung, 17.05.2004, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-6908
Radiomarkierung von Polyphenolen und Flavonoiden mit PET-Radionukliden
Gester, S.
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Lecture (others)
1. Workshop Positronen-Emissions-Tomographie in der Lebensmittelforschung, 17.05.2004, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-6907
PET in clinical oncology and research
Beuthien-Baumann, B.
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Lecture (others)
European Master Course in Radiobiology, University College London and Gray Laboratory, 30.01.2004, London, UK
Permalink: https://www.hzdr.de/publications/Publ-6906
Früh- und Differentialdiagnose von Parkinsonsyndromen: Teilgebiet Nuklearmedizinische Diagnostik
Beuthien-Baumann, B.
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Lecture (others)
Klinische Visite Parkinson, 03.09.2004, Universitätsklinikum Carl Gustav Carus, Dresden, Germany
Permalink: https://www.hzdr.de/publications/Publ-6905
Low level CRP increases adhesion of leukocytes to endothelial cells and decreases phagocyte respiratory burst activities
Kopprasch, S.; Graessler, J.; Pietzsch, J.; Schröder, H.
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Lecture (Conference)
15th International Symposium on Drugs Affecting Lipid Metabolism (DALM), 24.-27.10.2004, Venedig, Italy
Permalink: https://www.hzdr.de/publications/Publ-6904
Listmode Based Movement Correction in PET
van den Hoff, J.
-
Invited lecture (Conferences)
Workshop on Physical and Chemical Aspects of PET Radiopharmaceuticals, 19.-22.09.2004, Bratislava, Slovakia
Permalink: https://www.hzdr.de/publications/Publ-6903
Brain Trauma Elicits Increased AADC Acticity in Newborn Piglets
Brust, P.; Walter, B.; Hinz, R.; Müller, M.; Kuwabara, H.; Füchtner, F.; Bauer, R.; Steinbach, J.
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Lecture (Conference)
Neuroreceptor Mapping 2004 Meeting, 15.-18.07.2004, Vancouver, Canada -
Abstract in refereed journal
NeuroImage 22(2004)2, T140
Permalink: https://www.hzdr.de/publications/Publ-6902
Early Alzheimers Disease with apathy or depression: Differences in regional brain metabolism
Spirling, S.; Lüdecke, S.; Kalbe, E.; Beuthien-Baumann, B.; Lenz, O.; Zündorf, G.; Herholz, K.; Holthoff, V. A.
-
Abstract in refereed journal
American Psychological Association 2004 New Research Program NR 663
Permalink: https://www.hzdr.de/publications/Publ-6901
Quanten-Kaskaden-Laser-Struktur
Georgiev, N.; Dekorsy, T.; Helm, M.; Semtsiv, M.; Dreßler, S.; Ziegler, M.; Masselink, W.
Abstract
Es wird eine Quanten-Kaskaden-Laser-Struktur zur Verfügung gestellt, welche die Herstellung von Quanten-Kaskaden-Lasern, die bei Zimmertemperatur emittieren können, ermöglicht.
-
Patent
DE 10 2004 009 531 A1 -
Patent
DE 102004009531B4
Permalink: https://www.hzdr.de/publications/Publ-6900
Synthesis and biological characterization of fluorinated N-benzoylpolyamines as substrates for tissue transglutaminase
Pietzsch, J.; Knop, K.; Rode, K.; Wüst, F.; Bergmann, R.; van den Hoff, J.
-
Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004), A78
Permalink: https://www.hzdr.de/publications/Publ-6899
P0403 - Verfahren zur Korrektur der beim Monitoring der strahlentherapeutischen Behandlung mittels in-beam Positronen-Emissions-Tomographie erhaltenen Messwerte
Enghardt, W.; Pawelke, J.; Parodi, K.; Crespo, P.
Abstract
Es wird die Fehlerquote bei der in-beam PET weiter gesenkt, in dem ihre statistische Sicherheit erhöht wird.
-
Patent
DE 10 2004 009 784 A1 -
Patent
DE 10 2004 009 784 B4 - 10. Dez. 2009
Permalink: https://www.hzdr.de/publications/Publ-6898
Verfahren zur Verbesserung der Strahleigenschaften einer supraleitenden Hochfrequenz-Fotoelektronenquelle
Janssen, D.
Abstract
Mit der Erfindung soll die Effektivität der supraleitenden HF-Fotoelektrode und die Strahleigenschaft, insbesondere die transversale Emittanz, für mittlere und hohe Leistungen verbessert werden.
Involved research facilities
- SRF Gun
-
Patent
DE 10 2004 005 612 A1
Permalink: https://www.hzdr.de/publications/Publ-6897
Hydromechanische Maschine
Hoppe, D.; Kernchen, R.
Abstract
Mit der Erfindung wird erreicht, dass die sprunghafte Veränderung des übertragenen Drehmnoments nicht mehr oder in sehr abeschwächter Form geschieht und die Drehmomentveränderung über dem Drehzahlverhältnis zwischen Pumpen- und Turbinenrad weitgehend kontinuierlich erfolgt.
-
Patent
DE 10 2004 001 047.1-12 -
Patent
DE 10 2004 001 047 A1
Permalink: https://www.hzdr.de/publications/Publ-6896
Assessment of metabolism of native and oxidized low density lipoprotein in vivo: insights from high resolution animal positron emission tomography studies
Pietzsch, J.; Bergmann, R.; Wuest, F.; Pawelke, B.; van den Hoff, J.
-
Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004), A77
Permalink: https://www.hzdr.de/publications/Publ-6895
Intercomparison of sampling and measurement of Be-7 in air at four high-altitude locations in Europe
Tositti, L.; Hübener, S.; Kanter, H.-J.; Ringer, W.; Sandrini, S.; Tobler, L.
Abstract
For several years Be-7 measurements have been conducted at high-altitude stations in Austria (Sonnblick, 3106 m), Switzerland (Jungfraujoch, 3580 m), Germany (Zugspitze, 2962 m), and Italy (Mt. Cimone 2165 m) with the aim to support a study on vertical ozone transport in the Alps (VOTALP project).
Aerosol samples, collected on filtering media with high volume samplers, are analysed for Be-7 by high-resolution gamma-spectrometry.
Prior to evalution of the Be-7 time series of the four stations, both sampling and measurement procedures were cheked for comparibility. The results of an intercomparison exercise performed within the mentioned project are reported.
Keywords: Be-7; Gamma-spectrometry; Aerosol; Intercomparison
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Applied Radiation and Isotopes 61(2004)1497-1502
DOI: 10.1016/j.apradiso.2004.04.003
Cited 19 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-6894
Forschung für Mensch und Umwelt 2001/2002
Ottow, S.; (Editor)
-
Wissenschaftlich-Technische Berichte FZR-349 Januar 2003
ISSN: 1437-322X
Downloads
Permalink: https://www.hzdr.de/publications/Publ-6893
Far-IR spectroscopy of the nonlinear susceptibility of GaAs with an FEL
Dekorsy, T.; Helm, M.; Yakovlev, V.; Seidel, W.; Keilmann, F.
Abstract
The non-linear optical properties of solid state materials in the THz frequency region are to a large extent unexplored due to missing high-intensity coherent light sources in this frequency range. Although recent advances in table-top laser based THz systems have been enormous, free-electron lasers (FEL) are at present still the only tunable lasers which provide high peak intensities and a sufficient narrow spectral width to perform nonlinear spectroscopy at THz frequencies. Recently we investigated the dispersion of the second order nonlinear susceptibility (c(2)) in thin GaAs crystals below the optical phonon resonance via second harmonic generation (SHG) experiments with an FEL [1]. These experiments provide insight into the relative contributions of higher-order cohesive lattice forces to c(2). The nonlinear optical susceptibility in polar semiconductors in the THz frequency range is strongly influenced by the presence of optical phonons and should exhibit several peculiarities: A strong resonant enhancement of the SHG at half the frequency of the TO phonon (8.0 THz in GaAs) and at the TO phonon itself as well as a zero-crossing for frequencies between 4.0 THz and the TO phonon resonance due to the cancellation of higher order ionic and electronic contributions was predicted [2]. The experiments are performed with the THz FEL FELIX (Nieuwegein, Netherlands), which delivers picosecond pulses with µJ energy. We could observe both the resonance and the zero-crossing of c(2) below the Reststrahlen-band for the first time. From the value obtained for the zero-crossing of the nonlinear susceptibility we conclude that the contribution of the phonon interaction through the second-order lattice dipole moment has to be significantly smaller and the contribution from the third-order lattice potential anharmonicity has to be larger than determined previously [3]. Besides the relevance for the THz nonlinear susceptibility these terms are also important for two-phonon sidebands in the infrared absorption, phonon decay [3] and for a quantitative description of Raman spectra [4]. We propose that SHG below the optical phonon resonance is an elegant method to quantitatively determine the higher-order potential contributions to the nonlinear susceptibility.
[1] T. Dekorsy et al., Phys. Rev. Lett. 90, 055508 (2003).
[2] A. Mayer and F. Keilmann, Phys. Rev B 33, 6954 (1986).
[3] C. Flytzanis, Phys. Rev. B 6, 1264 (1972); Phys. Rev. Lett. 29, 772 (1972).
[4] S. Go, H. Bilz, and M. Cardona, Phys. Rev. Lett. 34, 580 (1975).
Keywords: FEL; nonlinear; THz; phonon-polariton; GaAs; resonance
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Lecture (Conference)
International Conference on Low Energy Electrodynamics in Solids, LEES 04, Kloster Banz, Germany, 19.7.-23.7.2004
Permalink: https://www.hzdr.de/publications/Publ-6890
N-Arylation of indoles with 4-[18F]fluoroiodobenzene: synthesis of 18F-labelled σ2 receptor ligands for positron emission tomography (PET)
Wüst, F.; Knieß, T.
Abstract
Summary: The palladium-mediated N-arylation of indoles with 4-[18F]fluoroiodobenzene as a novel radiolabelling method has been developed. Optimized reaction conditions were elaborated by variation of different catalyst systems (CuI/1,2-diamines and Pd2(dba)3/phosphine ligands), based and solvents in the reaction of indole with 4-[18F]fluoroiodobenzene. Optimized reaction conditions (Pd2(dba)3/(2-(dicyclohexyl-phosphino)-2´-(N,N-dimethylamino)-biphenyl, NaOBut, toluene, 100 °C for 20 min) were applied for the synthesis of 18F-labelled σ2 receptor ligands [18F]-11 and [18F]-13 which were obtained in 91 and 84 % radiochemical yields, respectively.
Keywords: N-arylation; 4-[18F]fluoroiodobenzene; σ2 ligands
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Journal of Labelled Compounds and Radiopharmaceuticals 48(2005), 31-43
DOI: 10.1002/jlcr.893
Cited 31 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-6887
Recursively Coupled FEM-Analysis Of Pressure Vessel Creep Failure Experiments
Willschütz, H.-G.; Altstadt, E.; Weiss, F.-P.
Abstract
The hypothetical scenario of a severe accident with core meltdown and formation of a melt pool in the lower plenum of a Light Water Reactor Pressure Vessel (RPV) can result in the failure of the RPV and the discharging of the melt to the containment. One accident management strategy could be to stabilize the in-vessel debris or melt pool configuration in the RPV as one major barrier against uncontrolled release of heat and radionuclides into the containment of the plant.
To obtain an improved understanding and knowledge of the melt pool convection, the vessel creep, possible failure processes and modes occurring during the late phase of a core melt down accident the FOREVER-experiments have been performed at the Division of Nuclear Power Safety of the Royal Institute of Technology, Stockholm. These experiments were simulating the behavior of the lower head of the RPV under the thermal loads of a convecting melt pool with decay heating.
An axisymmetric Finite Element (FE) model was developed to simulate these experiments. First the temperature field within the melt pool and within the vessel wall was calculated with a CFD-Model. But due to the lack of a turbulence model for very high internal Rayleigh numbers of up to 1017 in the prototypic case and due to the very time consuming CFD-solution, the Effective Conductivity Convectivity Model (ECCM) as proposed by Bui has been implemented. Once the temperature field in the vessel wall is evaluated, the transient structural mechanical calculations are then performed applying a creep model which takes into account the large temperature, stress and strain variations. The creep model includes the primary, secondary and tertiary creep stages.
In the prior work only a one-way coupling between the thermal and the mechanical model was applied: first the transient temperature field was calculated and then the transient mechanical calculation was performed applying the appropriate temperature field at each time step. To take into account the melt level drop by thermal expansion the initial level was lowered by hand. The feedback from the viscoplastic deformation to the temperature field was not correctly considered in the one-way coupling. On the other hand the earlier investigations showed that slight temperature shifts of only 10 K at an overall temperature level clearly above 1000 K had significant effects concerning the failure time of the vessel.
To overcome the disadvantages of the single coupling model a new recursively coupled model is developed. This paper deals with the new results and so far the results show that a recursively coupled thermal and mechanical solution is closer to reality than a single coupled model where the mechanical deformations have no impact to the thermal model. Due to the scaling effect it is expected, that the fully coupled model is necessary to be able to perform reliable best estimate calculations for prototypic light water reactor scenarios.
Keywords: LWR core melt down scenario; creep failure experiments; recursively coupled FEM-analysis
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Contribution to proceedings
Annual Meeting on Nuclear Technology 2005, 10.-12.05.2005, Nürnberg, Germany, Proceedings on CD-ROM, Paper 311, pp. 202-208
Permalink: https://www.hzdr.de/publications/Publ-6884
Assessment of metabolism of native and oxidized low density lipoprotein in vivo: insights from animal positron emission tomography (PET) studies.
Pietzsch, J.; Bergmann, R.; Wuest, F.; Pawelke, B.; van den Hoff, J.
-
Lecture (Conference)
74th European Atherosclerosis Society Congress, 17.-20.04.2004, Seville, Spain -
Abstract in refereed journal
Atherosclerosis 5(2004)Suppl. 1, 143-144
Permalink: https://www.hzdr.de/publications/Publ-6883
Integration nuklearmedizinischer Bilder in die Bestrahlungsplanung des nichtkleinzelligen Bronchialkarzinoms.
Oehme, L.; Hoinkis, C.; Appold, S.; Beuthien-Baumann, B.; Pötzsch, C.; Baumann, M.; Kotzerke, J.
-
Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004), A130
Permalink: https://www.hzdr.de/publications/Publ-6882
Nutzung von Mehrprozessorsystemen für den routinefähigen Einsatz listmode-basierter Bewegungskorrektur in der PET
Langner, J.; Bühler, P.; Pötzsch, C.; van den Hoff, J.
-
Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004)V189, 10
Permalink: https://www.hzdr.de/publications/Publ-6881
Konventionelles Staging und Staging mit FDG-PET bei Patienten mit Morbus Hodgkin unter Berücksichtigung der Therapieentscheidung
Kühnel, G.; von Ruthendorf-Przewoski, J.; Naumann, R.; Beuthien-Baumann, B.; Reiß, A.; Kotzerke, J.; Laniado, M.
-
Lecture (Conference)
Deutscher Röntgenkongress, 20.-22.05.2004, Wiesbaden, Germany -
Abstract in refereed journal
RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin 176(2004), S249
Permalink: https://www.hzdr.de/publications/Publ-6880
Atemtriggerung zur Verbesserung der Darstellung und Abgrenzbarkeit von intrathorakalen Raumforderungen in der PET
Just, U.; Pötzsch, C.; Bühler, P.; Beuthien-Baumann, B.; van den Hoff, J.
-
Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004), V192
Permalink: https://www.hzdr.de/publications/Publ-6879
Mikro-PET-Untersuchungen zu Bioverteilung und Metabolismus von F-18-fluorbenzoylierten Aminosäuren und Dipeptiden in den Nieren
Hultsch, C.; Wüst, F.; Pawelke, B.; Bergmann, R.
-
Abstract in refereed journal
Nuklearmedizin 43(2004), P40
Permalink: https://www.hzdr.de/publications/Publ-6878
Depression and regional cerebral glucose metabolism in early dementia
Holthoff, V. A.; Herholz, K.; Perani, D.; Sorbi, S.; Beuthien-Baumann, B.; Kalbe, E.
-
Abstract in refereed journal
European Journal of Neurology (2004)Suppl. 172
Permalink: https://www.hzdr.de/publications/Publ-6877
Synthese eines Fluor-18 markierten COX-2
Höhne, A.; Bergmann, R.; Wüst, F.
-
Abstract in refereed journal
Nuklearmedizin 43(2004), V173 -
Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-6876
Depressive Symptoms and regional cerebral glucose metabolism in patients with MSA and PSP
Herting, B.; Holthoff, V. A.; Triemer, A.; Poetrich, K.; Herholz, K.; Beuthien-Baumann, B.; Reichmann, H.
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Abstract in refereed journal
J Neurol Sciences, Abstraktband 2004
Permalink: https://www.hzdr.de/publications/Publ-6875
Schweres Schädel-Hirn-Trauma löst im unreifen Gehirn eine Erhöhung der dopaminergen Aktivität aus
Brust, P.; Walter, B.; Füchtner, F.; Müller, M.; Hinz, R.; Kuwabara, H.; Steinbach, J.; Bauer, R.
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Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004) A97
Permalink: https://www.hzdr.de/publications/Publ-6874
High-intensity THz radiation pulses from a scalable photoconductive device
Winnerl, S.; Dreyhaupt, A.; Krenz, M.; Stehr, D.; Dekorsy, T.; Helm, M.
Abstract
Photoconductive emitters are an attractive way for impulsive generation of THz radiation. There are two main categories, namely large-aperture emitters and interdigitated electrodes coupled to antennas. Large-aperture emitters have the advantage of a high active volume, while interdigitated structures provide high electric fields for efficient acceleration of photogenerated carriers. We present a large-aperture emitter consisting of a interdigitated metal-semiconductor-metal (MSM) structure, which combines both advantages. A second metallization layer, which is electrically insulated from the first one, blocks the optical excitation in every second period of the MSM structure, resulting in an unidirectional acceleration of carriers in the device. Focussing fs optical pulses with an average power of 100 mW from a Ti:sapphire oscillator on the emitter lead to THz field amplitudes of up to 85 V/cm (Ubias = 65 V). Excitation with unfocussed radiation from a 1 kHz repetition rate Ti:sapphire amplifier system (average power 10 mW) provided THz field amplitudes of 6 kV/cm (Ubias = 23 V). In case of the excitation with the Ti:sapphire amplifier system a pronounced nonlinear behavior of the THz field amplitude with respect to both the excitation density and the bias electric field was observed.
Keywords: THz emitter; photoconductive device; ultrafast processes in semiconductors
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Lecture (Conference)
DPG Frühjahrstagung, Fachverband Halbleiterphysik, 4.-9.3.2005, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-6873
Einfluss von klinischen Charakteristika auf den regionalen cerebralen Glukosestoffwechsel bei der unipolaren Depression
Beuthien-Baumann, B.; Zündorf, G.; Lüdecke, S.; Triemer, A.; Schierz, K.; Herholz, K.; Holthoff, V.
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Lecture (Conference)
42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock, Germany -
Abstract in refereed journal
Nuklearmedizin 43(2004), A82
Permalink: https://www.hzdr.de/publications/Publ-6872
Can [F18]FDG Positron emission tomography replace bone marrow biopsy in staging of patients with malignant lymphoma?
Naumann, R.; Beuthien-Baumann, B.
- Clinical Lymphoma 5(2004), 127
Permalink: https://www.hzdr.de/publications/Publ-6871
Regional cerebral metabolism in early Alzheimers disease with clinically significant apathy or depression
Holthoff, V.; Beuthien-Baumann, B.; Kalbe, E.; Lüdecke, S.; Lenz, O.; Zündorf, G.; Spirling, S.; Schierz, K.; Winiecki, P.; Herholz, K.
Abstract
BACKGROUND: Alzheimer's disease (AD) is clinically characterized by cognitive impairment and behavioral disturbances. The aim of the study was to identify regional alterations in brain function associated with neuropsychiatric symptoms in early AD. METHODS: Patients underwent measures of cerebral glucose metabolism applying positron emission tomography (PET) and (18)F-fluorodeoxyglucose. Neuropsychiatric symptoms were assessed using the Neuropsychiatric Inventory (NPI). Positron emission tomography images of patients suffering a neuropsychiatric symptom of clinical significance (NPI subscore for a specific item >/=4 points) were compared with the images of patients without the specific symptom under study (NPI subscore for a specific item = 0 points). RESULTS: A total of 53 patients with AD (Mini-Mental State Examination [MMSE] 22.5 +/- 2.94 points) entered the study. Of all symptoms, apathy and depression were most frequently encountered. The patient group with apathy (n = 17) revealed significant decreases in left orbitofrontal regions when compared with patients free of apathy. Depression of clinical significance (n = 10) was associated with hypometabolism in dorsolateral prefrontal regions. CONCLUSIONS: These findings support the notion that different functional circuits underlie apathy and depression in early AD.
- Biological Psychiatry 57(2005) 412-421
Permalink: https://www.hzdr.de/publications/Publ-6870
Functional imaging of vegetative state applying Single Photon Emission Tomography and Positron Emission Tomography
Beuthien-Baumann, B.; Holthoff, V. A.; Rudolf, J.
Abstract
Nuclear medicine techniques, such as single photon emission tomography (SPECT) and positron emission tomography (PET) have been applied in patients in a vegetative state to investigate brain function in a non invasive manner. Parameters investigated include glucose metabolism, perfusion at rest, variations of regional perfusion after stimulation, and benzodiazepine receptor reduction of glucose metabolism and perfusion. While patients post-anoxia exhibit a rather homogenous cortical reduction of glucose metabolism, patients after head trauma often show severe cortical and sub-cortical reductions at the site of primary trauma. To distinguish reduced glucose metabolism due to neuronal inactivation from neuronal loss, flumazenil-PET, and indicator of benzodiazepine receptor density, could add valuable information on the extent of brain damage. Activation studies focus on the evaluation of residual brain network, looking for processing in secondary projection fields. So far the predictive strength concerning possible recovery for the individual patient is limited, and PET und SPECT are not routine procedures in the assessment of patients in a vegetative state.
- Neuropsychological Rehabilitation 15(2005)3/4, 276-282
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Permalink: https://www.hzdr.de/publications/Publ-6869
Electro-vortex flows in a square layer of liquid metal
Kolesnichenko, I.; Khripchenko, S.; Buchenau, D.; Gerbeth, G.
Abstract
We study electro-vortex flows generated by electro-magnetic forces in a shallow square layer of liquid metal. The force driving the flow is produced by the interaction between the electric current flowing through the layer and its own magnetic field. Rotational parts of that force are particularly caused by ferromagnetic yokes placed around the layer. Depending of the position and type of those yokes flows of one-, two- or four-eddies are initiated. The basic flow structure and the related velocity oscillations have been investigated both by experimental techniques using the ultrasound Doppler velocimetry and by numerical calculations. Compared to the single vortex flow the double vortex flow shows a much higher level of large-scale velocity oscillations. The theoretical model turned out to be in good agreement with the experimental data.
- Magnetohydrodynamics 41(2005)1, 39-51
Permalink: https://www.hzdr.de/publications/Publ-6868
High-Intensity THz Radiation Pulses from a Scalable Large-Aperture Emitter
Winnerl, S.; Krenz, M.; Dreyhaupt, A.; Stehr, D.; Dekorsy, T.; Helm, M.
Abstract
Using a novel metal-semiconductor-metal (MSM) structure, we combine a large-active-emitter volume with strong electric fields for carrier acceleration. We obtain THz field amplitudes of 6 kV/cm using excitation pulse energies of 10 µJ.
Keywords: Terahertz emitter; photoconductive materials; ultrafast processes in semiconductors
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Lecture (Conference)
Conference on Lasers and Opto-Electronics 2005, Baltimore, USA -
Abstract in refereed journal
CLEO/QELS & PhAST Technical Digest CD-ROM, Berlin 2005: "Physik seit Einstein" (2005)
Permalink: https://www.hzdr.de/publications/Publ-6866
On the feasibility of dose quantification with in-beam PET data in radiotherapy with 12C and proton beams
Parodi, K.
Abstract
This thesis has contributed to the achievement of in-beam PET as a promising clinical monitoring technique. In response to a pressing medical demand, this work has provided a tool for quantification of local dose deviations in case of observed discrepancies between the measured and expected PET images. The implemented interactive approach described in chapter 3 is in clinical use since 2001. It provides the radio-oncologist with a valuable feedback which may allow a prompt reaction in the strategy of the therapy prior to the delivery of the successive treatment fraction in case of significant deviations between planned and actually applied dose. ...
Keywords: PET; ion therapy
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Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-415, November 2004
ISSN: 1437-322X
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Permalink: https://www.hzdr.de/publications/Publ-6865
Darstellung und Charakterisierung von Glycoclustern auf der Basis von PAMAM-Dendrimeren mit Cyclam-Core
Röhrich, A.; Stephan, H.
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Lecture (others)
Institutsseminar, Universität Bonn, 01.12.2004, Bonn, Germany
Permalink: https://www.hzdr.de/publications/Publ-6864
The Surface Layer Protein of the Bacillus sphaericus Isolate JG A-12 from a Uranium Waste Pile
Raff, J.; Kirsch, R.; Kutschke, S.; Mertig, M.; Selenska-Pobell, S.; Bernhard, G.; Pompe, W.
Abstract
Many bacteria possess a crystalline protein or glycoprotein surface layer (S-layer) as the outermost component of their cell wall. The interest in bacterial S-layers increased in the last time. This protein might be applied as biomolecular template for making nanostructures, e.g. for the development of biosensors. The surface layer of a natural Bacillus sphaericus isolate JG A-12, recovered from a uranium waste pile, was analyzed and compared to the surface layer
of a reference strain (Bacillus sphaericus NCTC 9602). The molecular weights of the S-layer proteins of both, the reference strain NCTC 9602 and the strain JG A-12, were examined with a denaturating polyacrylamid gel electrophoresis and were estimated to be approximately 135 kDa. In addition to that, the first 20 amino acids at the N-termini of the 135 kDa proteins of the strains 9602 and JG A-12 were identical. However, no similarity to the S-layer proteins of
the Bacillus sphaericus strains 2362 and P-1 was found. Interestingly, in the case of the uranium waste isolate, in addition to the S-layer protein a second, smaller protein with a size of 30 kDa was copurified. The amino acid sequence of the N-terminus of the 30 kDa protein was significantly different from those of the S-layer proteins. This small protein possesses a similarity to many flagellins of different bacteria. The S-layer of the reference strain Bacillus
sphaericus NCTC 9602 and of the uranium waste isolate JG A-12 were also characterized using transmission electron microscopy after negative staining. Both S-layers have a p4 symmetry with lattice constants of 12,9 nm (S-layer of Bacillus sphaericus NCTC 9602) and 12,5 nm (S-layer of JG A-12). It seems, that the reference strain Bacillus sphaericus NCTC 9602 and the isolate JG A-12 possess the S-layer protein with same structure.
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Poster
99TH General Meeting of the American Society for Microbiology (ASM), May 30 - June 3, 1999, Chicago, Illinois, USA
Permalink: https://www.hzdr.de/publications/Publ-6863
Biosorption of Heavy Metals by Sol-Gel Immobilized Bacillus sphaericus Cells, Spores and S-Layers
Soltmann, U.; Raff, J.; Selenska-Pobell, S.; Matys, S.; Pompe, W.; Böttcher, H.
Abstract
Different types of biocers were prepared by dispersing vegetative cells, spores and surface layer proteins (S-layers) of Bacillus sphaericus JG-A12 in aqueous silica nanosols, gelling or coating on glass, and drying. The enzymatic activity of embedded B. sphaericus cells depends noticeably on the water content of the biocer. The cells are destroyed by drying and shrinkage of the silica network whereas embedded spores retain their ability for germination. The biosorption
of uranium and copper of these biocomposites was investigated. Biocers with cells possess the highest metal binding capacity compared to matrices with spores or S-layers. An additional increasement of the metal binding capacity is achieved by using penetration reagents like sorbitol. For renewed use biosorpted uranium and copper can be completely removed from the biocers by using aqueous citric acid. The use of spores as biocomponent offers new interesting possibilities for the preparation of storage-stable bioactive biocers.
- Journal of Sol-Gel Science and Technology, 26: 1209-1212 (2003)
Permalink: https://www.hzdr.de/publications/Publ-6862
Impact of FDG Positron Emission Tomography in addition to conventional staging procedures in patients with Hodgkin´s lymphoma
Naumann, R.; Beuthien-Baumann, B.; Reiss, A.; Kühnel, G.; Schulze, J.; Haenel, A.; Bredow, J.; Kropp, J.; Haenel, M.; Laniado, M.; Ehninger, G.
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Poster
45th Meeting of the American Society of Haematology; San Diego, 06.-09.12.2003
Permalink: https://www.hzdr.de/publications/Publ-6861
Novel Re and 99mTc 3+1 oxocomplexes with high affinity for the 5-HT1A receptor.
Fernandes, C.; Bergmann, R.; Correia, J. D. G.; Gano, L.; Santos, I.; Spies, H.; Seifert, S.
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Poster
7th FIGIPS Meeting in Inorganic Chemistry, Lisbon, Portugal, 11.-15.06.2003
Permalink: https://www.hzdr.de/publications/Publ-6860
Síntese, Caracterizaçăo e Avaliaçăo Biológica de Complexos Lipofílicos de 99mTc
Fernandes, C.; Kniess, T.; Seifert, S.; Spies, H.; Gano, L.; Santos, I.
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Poster
Contendo Grupos Siloxo Hidrolisáveis, 1ş Congresso da Sociedade Portuguesa de Cięncias Farmacęuticas, Lisbon, Portugal, 04.-16.04.2003
Permalink: https://www.hzdr.de/publications/Publ-6859
Positron Emission Tomography (PET): Fundamentals and the potential role in drug research and development
Wüst, F.
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Invited lecture (Conferences)
PET-Tagung der BAYER AG; Wuppertal, 16.06.2003
Permalink: https://www.hzdr.de/publications/Publ-6858
Linearisations in compartment modelling
van den Hoff, J.
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Invited lecture (Conferences)
XV Annual PET Pharmacokinetic Course; Montreal, 25.-30.06.2003
Permalink: https://www.hzdr.de/publications/Publ-6857
Untersuchungen zum in vivo-Metabolismus nativer und oxidierter Lipoproteine am Tiermodell mittels PET
Pietzsch, J.
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Lecture (Conference)
11. Jahrestagung der AG Radiochemie/Radiopharmazie; Leipzig-Brehna, 18.09.2003
Permalink: https://www.hzdr.de/publications/Publ-6856
Synthetische Arbeiten in der medizinischen Chemie und der Re/Tc-Chemie
Heinrich, T.
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Lecture (others)
Dies Academicus 2003; Zittau, 04.06.2003
Permalink: https://www.hzdr.de/publications/Publ-6855
Erfahrungen bei der Verwendung von kommerziellen Ausrüstungen für die PET-Radiopharmakaherstellung
Füchtner, F.
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Lecture (Conference)
11. Jahrestagung der AG Radiochemie/Radiopharmazie; Leipzig-Brehna, 18.09.2003
Permalink: https://www.hzdr.de/publications/Publ-6854
Status and perspectives in neurotensin receptor PET imaging
Bergmann, R.
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Lecture (Conference)
International Workshop Radiolabelled peptides in tumour research; Leipzig, 26.05.2003
Permalink: https://www.hzdr.de/publications/Publ-6853
Experience with neurotensin and bombesin labelled with fluorine-18
Bergmann, R.
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Lecture (Conference)
European Association of Nuclear Medicine Annual Congress 2003; Amsterdam, 23.-27.08.2003
Permalink: https://www.hzdr.de/publications/Publ-6852
[N-methyl(11)C]meta-Hydroxyephedrine positron emission tomography in Parkinson's disease and multiple system atrophy
Berding, G.; Schrader, C. H.; Peschel, T.; van den Hoff, J.; Kolbe, H.; Meyer, G. J.; Dengler, R.; Knapp, W. H.
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Eur J Nucl Med Mol Imaging (2003) 30:127-31
DOI: 10.1007/s00259-002-1019-7
Cited 38 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-6851
Spektroskopische Untersuchungen zur Wechselwirkung von Actiniden mit Huminsäuren unter Einsatz von spezifischen Huminsäure-Modellverbindungen
Sachs, S.
Keywords: Huminsäuren; Komplexierung; Actinide; Neptunium; Uran; Huminsäure-Modellverbindungen; EXAFS; NIR; LIPAS
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Invited lecture (Conferences)
4. Mainzer Symposium über Spurenanalytik, Johannes Gutenberg-Universität Mainz, 26.11.2004, Mainz, Germany
Permalink: https://www.hzdr.de/publications/Publ-6850
Enzymatischer Test potentieller Substrate der Herpes Simplex Virus 1 Thymidinkinase zum Monitoring der Genexpression
Grote, M.; Noll, B.; Noll, S.; Knieß, T.; Johannsen, B.
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Poster
GDCh Jahrestagung in Würzburg, 23.09.-29.09.2001
Permalink: https://www.hzdr.de/publications/Publ-6848
Study of the Redox Stability of Uranium(VI) in Presence of Humic Substances
Sachs, S.; Geipel, G.; Bernhard, G.
Abstract
We studied the stability of the oxidation state of U(VI) in the presence of natural humic acid from Aldrich and synthetic acids Hyd-Glu and Cat-Gly representing humic acid model substances with pronounced redox functionalities. Using laser-induced photoacoustic spectroscopy we obtained the first spectroscopic proof for the reduction of U(VI) to U(IV) by the applied synthetic humic acids. In contrast to that, no spectroscopic indications for an Aldrich humic acid-mediated reduction of U(VI) were found. From that we concluded that both humic acid-like products show higher U(VI) redox capacities than Aldrich humic acid.
Keywords: Uranium; U(VI); U(IV); Humic Acids; Synthetic Humic Acids; Redox Processes; LIPAS
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Contribution to external collection
Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field. Third Technical Progress Report (G. Buckau, ed.), Forschungszentrum Karlsruhe, Wissenschaftliche Berichte, FZKA 7070, Karlsruhe 2005, 9-18.
Permalink: https://www.hzdr.de/publications/Publ-6847
Magnetic domain structure of micro-patterned PtMn/NiFe exchange bias bilayers
Potzger, K.; Bischoff, L.; Liedke, M. O.; Hillebrands, B.; Rickart, M.; Freitas, P.; McCord, J.; Fassbender, J.
Abstract
The local modification of magnetic properties by means of ion irradiation has been demonstrated for perpendicularly magnetized Co/Pt [1], for amorphous soft magnetic alloys [2] and for exchange-bias systems [3-5]. In all cases the magnetic features are not determined by the patterning itself, but by the micromagnetic feature sizes. Therefore, if the pattern sizes are close to the intrinsic length scales of the system under investigation a change in the overall magnetic behaviour is expected. For an exchange bias system this intrinsic length scale is in the range between 100 1000 nm [5].
The aim of the present study is to investigate the domain structure of a micro-patterned exchange bias system during magnetization reversal. Special attention is paid to the interaction between adjacent features changing the overall magnetic behaviour of the system. As a test system we chose a bottom pinned exchange bias bilayer consisting of 20 nm PtMn and 6 nm NiFe, capped with 5 nm of Ta, prepared by ion beam and physical vapour deposition. PtMn is chosen as the antiferromagnetic material due to its technological relevance and due to the chemically ordered L10-phase which is required in order to obtain a large exchange bias field. This phase can easily be disordered by means of ion irradiation leading to a very low ion fluence required to suppress the exchange bias effectively [6]. Thus sputtering effects are minimized. Using a 25 keV Ga+ focused ion beam (FIB) a stripe array consisting of 1 µm wide lines exposed to a fluence 21014 Ga/cm2 separated by 1 µm spacing is created. The long axes of the lines are oriented parallel to the exchange bias direction.
The global magnetic properties of the stripe array were analyzed by means of magneto-optic Kerr effect magnetometry (MOKE) and Kerr microscopy. It was found, that the overall loop shift in the patterned region is reduced to ~30 Oe compared to an exchange bias field of 180 Oe in the unpatterned area. After saturation in an applied field of +800 Oe there is no domain pattern observed in remanence by Kerr microscopy. With increasing negative field first the magnetization in the irradiated stripes reverse. This leads to an alignment of the soft magnetic (irradiated) stripes parallel to the applied field direction while the magnetization of the non-irradiated stripes remains antiparallel. After saturation at -500 Oe and increase of the applied field a hysteretic behaviour was observed that is consistent with the MOKE-measurements leading to a remaining domain contrast in remanence.
At an applied field between -12 Oe and -80 Oe a sharp contrast originating from Néel walls between irradiated and non-irradiated regions is observed by magnetic force microscopy. Moreover, a successive increase of the domain width in the irradiated areas at the expense of those in the non-irradiated areas is observed. At an applied magnetic field of about -100 Oe the magnetization in the non-irradiated area is nearly completely reversed due to the influence of the adjacent soft magnetic areas which are reversed at lower field values already. A magnetization ripple as a remainder of the non-irradiated stripes persists up to large negative field values consistent with the large exchange bias field in the completely unpatterned region.
References
[1]J. Lohau, A. Moser, C. T. Rettner, M. E. Best, B. D. Terris, Appl. Phys. Lett. 78, 990 (2001).
[2]J. McCord, J. Fassbender, M. Frommberger, M.O. Liedke, E. Quandt, L. Schultz, Appl. Phys. Lett., submitted.
[3]A. Mougin, S. Poppe, J. Fassbender, B. Hillebrands, G. Faini, U. Ebels, M. Jung, D. Engel, A. Ehresmann, H. Schmoranzer, J. Appl. Phys. 89, 6606 (2001).
[4]J. McCord, R. Schäfer, K. Theis-Bröhl, H. Zabel, J. Schmalhorst, V. Höink, H. Brückl, T. Weis, D. Engel, A. Ehresmann, J. Appl. Phys. accepted.
[5]S. Blomeier, D. McGrouther, S. McVitie, R. ONeill, J. N. Chapman, M. C. Weber, B. Hillebrands, J. Fassbender, J. Magn. Magn. Mater. accepted.
...
Keywords: magnetism; exchange-bias; magnetic patterning; MFM; ion irradiation; Kerr microscopy; patterning
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Poster
Intermag 2005, Nagoya
Permalink: https://www.hzdr.de/publications/Publ-6846
Spectroscopic Characterization of Synthetic Becquerelite, Ca[(UO2)6O4(OH)6]8H2O, AND SWARTZITE, CaMg[UO2(CO3)3]12H2O
Amayri, S.; Arnold, T.; Foerstendorf, H.; Geipel, G.; Bernhard, G.
Abstract
Becquerelite, Ca[(UO2)6O4(OH)6]8H2O, and swartzite, CaMg[UO2(CO3)3]12H2O, have been synthesized and identified by X-ray powder diffraction (XRD). Chemical compositions were verified by ICPMS and AAS. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) and Fourier-transformed infrared spectroscopy (FTIR) were used for the first time to characterize these phases. In becquerelite, there are four fluorescence emission bands, at 518.9, 535.6, 553.4, and 578.9 nm, and a characteristic fluorescence lifetime of 3.1 ± 0.2 s. Swartzite shows six characteristic fluorescence emission bands, at 472.3, 488.9, 509.0, 531.1, 554.7, and 578.9 nm, and a fluorescence lifetime of 59.4 ± 0.1 s. The FTIR spectra of becquerelite are characterized by an intense asymmetric stretching vibration (v3 UO2
2+ mode) band at 946 cm-1, with shoulders at approximately 925 and 902 cm-1. Swartzite shows its characteristic v3 UO2
2+ mode of the uranyl cation at 898 cm-1. As natural U6+-bearing samples commonly form thin coatings on rock or mineral surfaces or as a component mixed with other solids, it is generally difficult to identify small quantities of these secondary phases. Spectroscopic methods like TRLFS and FTIR spectroscopy are found to be promising methods to identify such secondary phases.
Keywords: uranium; synthesis; TRLFS spectroscopy; FTIR; spectroscopy
- The Canadian Mineralogist 42(2004)4, 953 962
Permalink: https://www.hzdr.de/publications/Publ-6845
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