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33407 Publications

Application of synchrotron radiation excited X-ray microprobe techniques in material and environmental science

Somogyi, A.; Martinez-Criado, G.; Scheinost, A.; Tucoulou, R.
Synchrotron radiation excited X-ray microprobe techniques (-XRF/XAS, -XRD, imaging/tomography) give unique possibility for non-destructive, in situ investigation of several sample characteristics (elemental- and crystalline composition, chemical speciation, morphology) and different chemical, environmental processes within inhomogeneous samples. The ID22 X-ray microprobe beamline of the European Synchrotron Radiation Facility (ESRF, Grenoble, France) offers the simultaneous use of these techniques with m spatial resolution in the 6-30 keV energy range.

Material and environmental sciences are two scientific fields often requiring the combined investigation of the elemental distribution, chemical speciation, and crystalline structure of large number of samples with (sub)-micron spatial resolution. The new developments of the ID22 beamline can readily fulfill these requirements, as will be illustrated by the presented examples. The high 1010-5x1011 ph/s intensity of the micro-beam (depending on the spot-size, energy and focusing device) allows for continuous scanning -XRF measurements of sample areas of up to 1 mm2 with 0.6-2 m spatial resolution within <10-12 hours measurement time in case of high enough characteristics X-ray line intensities. Combination of scanning -XRF with -XANES (-EXAFS) gives information about the dependence of the oxidation state/chemical speciation of a given element from the elemental composition. The achromaticity of the commonly used KB focusing mirror makes the change of the excitation energy possible in the 7-18 keV energy region without significant change of the size and position of the focused beam. Thus, XANES measurements at different absorption edges are achievable, which allow to study the correlation among chemical speciation of different elements. Correlation between the chemical characteristics and the crystalline structure of the sample can be investigated by combining these techniques with -X-ray diffraction measurements.
  • Invited lecture (Conferences)
    Dispersive X-Ray Spectrometry, European Conference on Energy, 06.-11.06.2004, Alghero, Italy
  • Contribution to proceedings
    Dispersive X-Ray Spectrometry, European Conference on Energy, 06.-11.06.2004, Alghero, Italy
    Proceedings

Permalink: https://www.hzdr.de/publications/Publ-6990
Publ.-Id: 6990


Quantitative zinc speciation in soil with XAFS spectroscopy: Evaluation of iterative transformation factor analysis

Scheinost, A.; Rossberg, A.; Marcus, M.; Pfister, S.; Kretzschmar, R.
We employed a combination of selective sequential extractions and bulk XAFS spectroscopy, and extracted spectral XAFS components and their concentrations by iterative transformation factor analysis (ITFA), in order to determine the Zn speciation in a smelter-contaminated, acidic soil. We compared the speciation by ITFA with one we performed earlier using principal component analysis and linear combination fit. ITFA identified 4 different species, two different franklinite-type phases (Zn-Fe spinels), sphalerite (Zn sulfide) and Zn oxalate, the latter forming as a precipitate during chemical extraction with oxalate solution. The second spinel-type phase could be extracted with the help of ITFA, although no appropriate reference sample was available. Spinel 1 and 2 have Zn-O distances of 1.96 and 1.99 Å, and Zn-Fe distances of 3.53 and 3.48 Å, respectively. The results from ITFA gave much better fits of experimental spectra and are better in line with elemental mapping and XAFS microspectroscopy. The major advantage of investigating XAFS data with ITFA is the possibility to derive all species even when part of the references are not available.
  • Physica Scripta T115(2005), 1038-1040

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Permalink: https://www.hzdr.de/publications/Publ-6989
Publ.-Id: 6989


The Rossendorf Beamline at the ESRF: An XAS experimental station for actinide research

Scheinost, A.
The Rossendorf Beamline is in full operation since 1999. Its X-ray absorption spectroscopy station dedicated to actinide research is unique in Europe, and has served for about 80 different experiments in the past four years. An overview on the current status of operation modes, technical details and access conditions is presented.
  • Lecture (Conference)
    3rd Workshop on Speciation, Techniques, and Facilities for Radioactive Materials at Synchrotron Light, 14.-16.09.2004, Berkeley, United States

Permalink: https://www.hzdr.de/publications/Publ-6988
Publ.-Id: 6988


Chemical heterogeneity of humic substances and mobile soil colloids studied by X-ray microscopy and microspectroscopy

Schumacher, M.; Scheinost, A.; Christl, I.; Jacobsen, C.; Kretzschmar, R.
Humic substances are important sorbents for organic and inorganic contaminants such as heavy metals or radionuclides. They participate in many geochemical processes, affecting the quality of ground and surface waters, or the uptake of nutrients by plants. This property is due to their high surface area, the sorption of ions at charged hydrophilic functional groups and the sorption of non-polar organic compounds by hydrophobic surface sites [1,2].
The bulk chemical porperties of of humic substances can be investigated with a variety of methods like solid-state CP-MAS 13C-NMR spectroscopy, FT-IR spectroscopy, pyrolysis coupled with mass spectrometry or acid-base titrations. Although all of those methods have been applied widely to characterize colloids and their interaction with contaminants, methods which provide both in-situ imaging as well as spectroscopic characterization are rare. The Scanning Transmission X-ray Microscope (STXM) at beamline X1-A at the National Synchrotron Light Source (NSLS) is one of the few methods that may fill in this gap. Carbon X-ray absorption near-edge structure (C-1s XANES) as well as X-ray microscopy was employed to systematically monitor the chemical properties of humic substances. Furthermore, the colloidal fraction of different soil types was extracted and analyzed with C-1s XANES spectroscopy. The objectives of this study are (i) to characterize the spectroscopic features of humic substances and mobile soil colloids with C-XANES spectroscopy and X-ray microscopy and (ii) to evaluate a qualitative as well as quantitative comparison with other spectroscopic methods like solid-state CP-MAS 13C-NMR spectroscopy or FT-IR spectroscopy.

References
[1] Pignatello J.J., and Xing B. (1996) Environ. Sci. Technol. 30, 1-11.
[2] Grolimund, D., Elimelech, M., Borkovec, M., Barmettler, K., Kretzschmar, R., and Sticher, H. (1998) Environ. Sci. Technol. 32, 3562-3569.
  • Geochimica et Cosmochimica Acta 68(2004)11, A225-A225
  • Poster
    Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Dänemark
  • Contribution to proceedings
    14th Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Denmark
    Proceedings

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Permalink: https://www.hzdr.de/publications/Publ-6987
Publ.-Id: 6987


Zinc speciation in an artificially contaminated soil: Formation of a new mineral phase within 3 years

Kretzschmar, R.; Pfister, S.; Voegelin, A.; Scheinost, A.
The bioavailability and toxicity of Zn in contaminated soils strongly depend on its speciation. Initially, Zn speciation is determined by the primary contaminants. Over time, primary phases dissolve and Zn may adsorb to various soil components and eventually become incorporated into newly forming mineral phases. The practical relevance of this process for the attenuation of Zn bioavailability depends on the time scale over which new mineral phases form and the thermodynamic stability of the newly formed phase.
In this study, a field soil (pH 6.4, 1.5% organic carbon, 15% clay) was contaminated with filter dust from a brass foundry containing 98% zincite (ZnO). We followed the dissolution and redistribution of Zn over 4 years using bulk and micro XAFS analysis.
Bulk XAFS shows that within 18 months, most zincite dissolved and Zn attached to various soil components, mainly as an outer sphere complex. Micro XAFS reveals both remnants of undissolved zincite as well as regions of Zn specifically adsorbed to Mn/Fe oxides and beginning formation of a Zn bearing solid phase (phyllosilicate or mixed layered hydroxide). After 36 months, we observe a second shell in the bulk XAFS spectrum (~2.1 Zn @ 3.11 Å; 1st shell 5.8 O @ 2.04 Å), further supporting the formation of a Zn bearing mineral. Micro XAFS data for the same time reveal tetrahedrally coordinated specifically adsorbed Zn in Mn rich zones, Zn attached to organic material as an outer sphere complex, and octahedrally coordinated Zn in large diffuse parts of the soil matrix with a spectrum similar to the bulk XAFS.
Our results show that in a near neutral soil, ZnO dissolved within one to two years. A short transient phase, during which Zn is predominantly bound as an outer sphere complex, was followed by specific Zn adsorption and the onset of the formation of a Zn mineral phase. These results demonstrate that within a few years, Zn may be redistributed and attenuated in a near neutral soil. In ongoing studies, we investigate the long term efficiency of this immobilization process, e.g., during soil acidification.
  • Geochimica et Cosmochimica Acta 68(2004), 361-361
  • Lecture (Conference)
    14th Goldschmidt Conference, 05.-11.06.2004, Copenhagen, Denmark
  • Contribution to proceedings
    14th Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Denmark

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Permalink: https://www.hzdr.de/publications/Publ-6986
Publ.-Id: 6986


Fate of uranium in the environment

Scheinost, A.; Bernhard, G.; Selenska-Pobell, S.
Uranium is present in the Earth’s crust at an average concentration of 2 mg/kg, similar to As and Mo, but ten times higher than Sb. It is enriched in granitic and phosphate rocks, lignite and monazite sands, and occurs in numerous minerals, uraninite (pitchblende), carnotite, and autunite being most abundant. During mining and ore processing (World production of U 35,000 Mg/a), these relatively insoluble, U(IV) and/or U(VI) containing minerals are converted into highly soluble and mobile U(VI) aqueous species, which may present an immediate risk for the environment, or are converted back to less mobile chemical forms. We will give an overview of processes, which influence the fate of U in this greatly perturbed biogeochemical cycle.
Even at low redox potential and in equilibrium with uraninite, the aqueous solution of soils, the vadose zone and aquifers is dominated by U(VI) species. The extremely complex speciation of U(VI) is influenced by pH, dissolved carbonate and the presence of organic ligands. The mobility of these species is reduced by sorption processes to minerals, insoluble natural organic matter, and biota. On the other hand, the presence of carbonate and organic ligands with strong affinity for uranyl may prevent sorption to surfaces and enhance the mobility. The migration of U is furthermore influenced by the formation of, or sorption to mobile colloids.
A strong immobilization of U presents the reduction to U(IV) and the subsequent precipitation as uraninite or other minerals. This process may proceed as a catalytic reaction on inorganic surfaces. Microorganisms, however, which are abundant even in U waste piles with high heavy metal concentrations, may be more important for U(IV) mineral precipitation. Processes involved are a direct biological reduction of U(VI) or an indirect reduction by changing redox potential and pH of the aqueous solution. Microorganisms can reduce the U mobility also by processes like bioaccumulation and biomineralization. Alternatively, particular groups of microorganisms can mobilize U from the ores by direct and indirect (metabolic-conducted) oxidation of U(IV), a process called bioleaching. Microorganisms can also increase the U mobility by releasing chelating ligands into the environment. Thus, they play one of the key roles in the biogeochemical cycling of U.
  • Geochimica et Cosmochimica Acta 68(2004), 526-526
  • Invited lecture (Conferences)
    14th Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Denmark
  • Contribution to proceedings
    14th Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Denmark
    Proceedings

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Permalink: https://www.hzdr.de/publications/Publ-6985
Publ.-Id: 6985


Quantitative antimony speciation in Swiss shooting range soils

Scheinost, A.; Rossberg, A.; Hennig, C.; Vantelon, D.; Kretzschmar, R.; Johnson, C.
Antimony is used to harden the Pb cores of ammunition. Thus, between 4 and 10 tons of Sb are annually deposited on Swiss shooting ranges by bullets. Due to the relatively rapid weathering of the bullets, Sb is released into the soil, but little is known about its further fate. As part of investigations to determine the geochemical factors that control Sb mobility, we have determined the oxidation state and species of Sb in 6 shooting-range soils, using a combination of EXAFS (extended x-ray absorption fine structure) spectroscopy and ITFA (iterative transformation factor analysis), a technique particularly suited for quantitative speciation in complex matrices [1, 2].
Antimony concentrations varied between 1,000 and 17,000 mg/kg. In spite of a wide range of soil chemical conditions (pH, mineral and organic matter composition), we found only two Sb species. In the first species, Sb is surrounded by 6 O atoms at a distance of 1.97 Å, by 1 Fe atom at 3.09 Å, and by 2 Sb atoms at 3.33 Å. This arrangement suggests pentavalent Sb sorbed onto Fe or Mn oxides by forming a polynuclear inner-sphere sorption complex.
In the second species, Sb is surrounded by 2 O atoms at a distance of 1.98 Å, and by Sb atoms at 2.91 Å, 3.35 Å, 4.30 Å, and 4.52 Å. This structure is consistent with Sb(III) (hydr)oxide.
The (hydr)oxide species prevailed in a very acidic soil (pH 3.1), the sorption complex prevailed in a slightly acidic soil, and mixtures of both species occurred in calcareous soils (pH 7.5).
The results for Sb(V) are in agreement with previous findings suggesting that Sb is bound to Fe oxides. Antimony(III) solubility appears to be controlled by Sb(III) (hydr)oxide. Our results suggest that Sb remains tightly bound in soils, confirming our previous macroscopic observation that Sb is strongly enriched in the uppermost layer of a soil profile [3].

References
[1] Scheinost A. C., Rossberg A., Marcus M., Pfister S., and Kretzschmar R. (2003) Physica Scripta, in press.
[2] Rossberg A., Reich T., and Bernhard G. (2003) Analyt. Bioanalyt. Chem. 376, 631-638
[3] Knechtenhofer L. A., Xifra I. O., Scheinost A. C., Flühler H., Kretzschmar R. (2003) J. Plant Nutr. Soil Sci. 166, 84-92.
  • Geochimica et Cosmochimica Acta 68(2004), 521-521
  • Lecture (Conference)
    14th Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Denmark
  • Contribution to proceedings
    14th Goldschmidt Conference, 05.-11.06.2004, Kopenhagen, Denmark

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Permalink: https://www.hzdr.de/publications/Publ-6984
Publ.-Id: 6984


Metal Oxides in Soils

Scheinost, A.
wird nachgereicht
  • Contribution to external collection
    in: Encyclopedia of Soils in the Environment, Amsterdam: Academic Press, 2004, 0123485304, 428-438

Permalink: https://www.hzdr.de/publications/Publ-6983
Publ.-Id: 6983


Laser-induced Spectroscopy: Tools to Study Actinide Speciation in Environmental Concentration Ranges

Geipel, G.
wird nachgereicht
  • Lecture (others)
    Eingeladener Vortrag, 06.12.2004, Praha, Czech Republic

Permalink: https://www.hzdr.de/publications/Publ-6982
Publ.-Id: 6982


Aquatische Kolloide II: Eine Übersichtsarbeit zur Probennahme, Probenaufbereitung und Charakterisierung

Hofmann, T.; Baumann, T.; Bundschuh, T.; von D. Kammer, F.; Leis, A.; Schmitt, D.; Schäfer, T.; Thieme, J.; Totsche, K.-U.; Zänker, H.
Kolloide sind Bestandteile aller aquatischen Systeme. Das Verhalten der Kolloide in der Umwelt, deren Mobilisierung, Transport und Abscheidung und somit auch die Relevanz sind noch nicht vollständig verstanden. Dies liegt zum Teil an der Tatsache, dass die Kolloidanalytik extrem aufwändig ist. Sie gehört nicht zur Standardanalytik eines Wasserlabors. Keine Technik ist bisher zufriedenstellend in der Lage, Kolloide in ihrem gesamten Größenbereich auch bei geringsten Konzentrationen gleichzeitig zu quantifizieren und zu identifizieren. In der Regel ist eine Kombination von verschiedenen Techniken notwendig, um ausreichend Informationen über das Verhalten der Kolloide zu erhalten. Für die Bestimmung der Oberflächeneigenschaften stehen kaum Methoden zur Verfügung. Eine weitere, nicht zu unterschätzende Schwierigkeit ist die Probennahme und Probenaufbereitung. Für die Untersuchung von Kolloiden sind spezielle Probennahmetechniken und Protokolle notwendig, da ansonsten die ungestörten, natürlichen Bedingungen durch (Probennahme-)Artefakte maskiert werden. Dieser Artikel soll in Form einer Übersichtsarbeit Hinweise zur Probennahme geben und die verschiedenen Möglichkeiten der Kolloidanalytik aufzeigen.

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Permalink: https://www.hzdr.de/publications/Publ-6981
Publ.-Id: 6981


Aquatische Kolloide I: Eine Übersichtsarbeit zur Definition, zu Systemen und zur Relevanz

Hofmann, T.; Baumann, T.; Bundschuh, T.; Kammer, F. V. D.; Leis, A.; Schmitt, D.; Schäfer, T.; Thieme, J.; Totsche, K.-U.; Zänker, H.
Kolloide sind Bestandteile aller aquatischen Systeme. Sie umfassen Feststoffe, deren Größe in zumindest einer Dimension zwischen 1 und 1.000 nm liegt. Sie können anorganischer (z. B. Tonteilchen, Karbonate oder Silikate) oder organischer (z. B. Ruß oder höhermolekulare organische Verbindungen wie Huminstoffe) Natur sein. Auch Bakterien, Viren, Sporen und Algen in diesem Größenbereich können zu den Kolloiden gerechnet werden (häufig als Bio-Kolloide bezeichnet). Kolloide können den Transport von (Schad-)stoffen im Untergrund und in Oberflächengewässern beeinflussen, insbesondere von Spurenelementen und hydrophoben organischen Verbindungen, oder zu unerwünschten Effekten wie Porenraumreduktion (Clogging) führen. Für die Hygiene des Trinkwassers ist das Verhalten von Bakterien, Viren und Sporen (den Bio-Kolloiden) von besonderer Bedeutung. Bisher ist das Verhalten von Kolloiden nur unzureichend verstanden. Dieser Artikel soll einen Beitrag zu dem Verständnis des physikalischen Verhaltens der Kolloide, deren Vorkommen in der aquatischen Umwelt sowie Relevanz in Form einer Übersichtsarbeit leisten.

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Permalink: https://www.hzdr.de/publications/Publ-6980
Publ.-Id: 6980


X-ray tomography: how to evaluate the reconstruction quality?

Chukalina, M.; Golosio, B.; Simionovici, A.; Funke, H.
Different reconstruction techniques are used to reconstruct the distribution of the physical characteristics, describing a sample under investigation, from a set of tomographic projections. We present a technique for the evaluation of the reconstruction quality. The technique is based on the comparison of two images (phantom and reconstructed image) by means of the correlation coefficient and of the mean square error between them. In parallel, the correlation coefficient and mean square error are calculated for the wavelet transforms of the phantom and reconstructed images. The scales for the wavelet transform are chosen in agreement with the major geometric parameters of the phantom. Then the correlation coefficient of the wavelet transform with the chosen scale yields an evaluation of the quality of the phantom parameters reconstruction. The accuracy of the parameters reconstruction is determined by the mean square error for the selected scale. The phantom used for the analysis is a medium with randomly distributed grains. The distribution is characterized by two parameters: grain size and grain density (average number of grains per unit area). The parameters are used as the scales for the wavelet transform calculation. We make a comparison of the Algebraic Reconstruction Technique (ART) and the Filtered Back Projection Algorithm.
Keywords: X-ray computer tomography; Reconstruction techniques; Quality of the reconstruction; Wavelet transform; Correlation coefficient

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Permalink: https://www.hzdr.de/publications/Publ-6979
Publ.-Id: 6979


Kolloide in Bergwerkswässern

Zänker, H.; Wichter, W.; Ulrich, K.-U.; Moll, H.; Hüttig, G.
Kolloide in Bergwerkswässern
  • Lecture (others)
    6. Arbeitstreffen des Arbeitskreises "Kolloide" der Wasserchemischen Gesellschaft in der GDCh, 09.03.2004, München, Germany

Permalink: https://www.hzdr.de/publications/Publ-6978
Publ.-Id: 6978


Die Welt der vernachlässigten Dimensionen

Zänker, H.; Richter, W.; Hüttig, G.; Moll, H.; Brendler, V.; Hübener, S.; Opel, K.
wird nachgereicht

Beitrag zu "Forschung für Mensch und Umwelt. Jahresbericht 2003 des FZR"
  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-398 Mai 2004, 42-51

Permalink: https://www.hzdr.de/publications/Publ-6977
Publ.-Id: 6977


Local “annealing” and domain patterning of amorphous films by He-ion irradiation

McCord, J.; Fassbender, J.ORC; Liedke, M. O.; Frommberger, M.; Mönch, I.; Gemming, T.; Schäfer, R.; Quandt, E.; Schultz, L.
The magnetic anisotropy in amorphous soft magnetic FeCoSiB films is modified by He-ion irradiation. A realignment of uniaxial anisotropy depending on the applied field direction in the irradiated areas is observed by magnetometry and complementary domain observation by Kerr microscopy. Using irradiation together with photolithography the films were treated locally, resulting in ‘anisotropy patterned’ structures. Complicated periodic domain patterns form due to the confined anisotropy distribution. Overall magnetic properties and domain patterns can be adjusted.
Keywords: magnetism, magnetic anisotropy, Kerr microscopy, ion irradiation, patterning, lithography, soft magnetic, alloys
  • Contribution to external collection
    in: IFW Jahresbericht 2004, Dresden: IFW Dresden, 2005, 14-17

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Permalink: https://www.hzdr.de/publications/Publ-6976
Publ.-Id: 6976


Material related fundamentals of cutting techniques for GaAs wafer manufacturing

Hammer, R.; Bergner, F.; Flade, T.; Jurisch, M.; Kleinwechter, A.; Schaper, M.
Driven by the requirement of high cutting efficiency and improvement of wafer flatness wire sawing of GaAs single crystals under brittle material removal conditions has been studied. Crack nucleation and crack propagation were investigated by indentation and scratching tests on polished {100}-oriented semi-insulating GaAs wafers. Based on these results a concept has been developed to control the force balance in the cutting slits so that the deflection of the wires perpendicular to the cutting planes is minimal resulting in cuts of high flatness. The concept has been successfully introduced in mass production of GaAs wafers.
Keywords: Semi-insulating GaAs; Ductile-to-brittle transition; Indentation tests; Crack nucleation; Wire sawing
  • Zeitschrift für Metallkunde 96(2005), 785-791

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Permalink: https://www.hzdr.de/publications/Publ-6975
Publ.-Id: 6975


Characterization of 6H-SiC surfaces after ion implantation and annealing using positron annihilation spectroscopy and atomic force microscopy

Brauer, G.; Anwand, W.; Skorupa, W.
Systematic Slow Positron Implantation Spectroscopy (SPIS) and Atomic Force Microscopy (AFM) studies of various 6H-SiC samples are presented to clear the role of conductivity type, crystal quality, ion implantation (B+, Al+, N+), and annealing (1.650 °C) on the formation of continuous long furrows (undulations) running in one direction across the wafer surface. It is found that the observed changes in surface morphology are primary the result of thermal activation and thus occur independent of conductivity type, crystal quality, and type of ion implantation. In terraces in-between the long furrows, stripe like islands with a discrete height in the nanometer range have been observed which may have some link with the ion implantation chosen. SPIS results clearly indicate the formation of vacancy clusters in n-type material which are connected with the mobility of nitrogen in the samples at elevated temperatures. It is found that defect profiling by SPIS is not influenced by the changes in surface morphology observed due to annealing.
Keywords: 6H-SiC, ion implantation, vacancy-type defects, annealing, slow positron implantation spectroscopy, step bunching, atomic force microscopy
  • Journal of Applied Physics 99(2006), 023523

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Permalink: https://www.hzdr.de/publications/Publ-6974
Publ.-Id: 6974


Strömungsinstabilitäten bei Stoffübergang und chemischer Reaktion an der ebenen Grenzfläche zwischen zwei nicht mischbaren Flüssigkeiten

Grahn, A.
In verfahrenstechnischen Anlagen der Flüssig-Flüssig-Stoffübertragung kommt es an der Phasengrenze zwischen den nicht mischbaren Flüssigphasen häufig zur Ausbildung hydrodynamischer Instabilitäten. Sie sind mit komplexen Geschwindigkeitsfeldern in den Flüssigphasen, insbesondere in den grenzschichtnahen Regionen verbunden und führen zu einem starken Anstieg der pro Zeiteinheit übertragenen Stoffmenge. Die Lösung der Diffusionsgleichung reicht in diesem Fall zur Vorausberechnung des für Auslegungszwecke bedeutsamen Stoffdurchgangskoeffizienten nicht mehr aus. Chemische Reaktionen stellen Quellen oder Senken von Wärme und Stoff dar, die das Auftreten von Instabilitäten begünstigen und die mathematische Beschreibung zusätzlich erschweren.

Im Rahmen der vorliegenden Arbeit wurden experimentelle und numerische Untersuchungen zum Flüssig-Flüssig-Stoffübergang in einem vertikalen Kapillarspalt durchgeführt. Reaktionsfreie Stoffübergänge und solche mit einer exothermen chemischen Reaktion an der Phasengrenze zeigten eine große Vielfalt von Konvektionsstrukturen, wie Rollzellen, Thermiken und das doppeldiffusive Fingerregime. Die Visualisierung der Transportvorgänge erfolgte durch das Schattenschlierenverfahren. Die Beobachtungen wurden hinsichtlich geometrischer Eigenschaften von Konvektionsstrukturen sowie deren zeitlicher Änderung ausgewertet. Dazu zählten insbesondere das Längenwachstum von Thermiken und horizontale Wellenlängen von Fingerstrukturen.

Zur mathematischen Beschreibung der Phänomene im Kapillarspalt wurde ein Modell entwickelt, welches auf den gekoppelten, zweidimensionalen Transportgleichungen von Impuls, Wärme und Stoff beruht. Es berücksichtigt dichte- und grenzflächenspannungsgetriebene Instabilitätsmechanismen sowie die besonderen Durchströmungseigenschaften des Kapillarspalts. Die Phasengrenze wurde als eben angenommen. Die Lösung der Modellgleichungen erfolgt auf numerischem Wege durch ein Computerprogramm.

Das Modell ist in der Lage, die beobachteten Instabilitätsphänomene qualitativ richtig wiederzugeben. Mit Hilfe von Simulationsrechnungen konnte der Mechanismus aufgeklärt werden, der zum schnelleren Rückgang des Stoffdurchgangskoeffizienten im Rollzellenregime der rein grenzflächenspannungsgetrieben Instabilität im Vergleich zum Vorgang mit überlagerter Dichtekonvektion führt. Des Weiteren gelang der Nachweis des doppeldiffusiven Fingerregimes beim Stoffübergang mit exothermer Grenzflächenreaktion. Die berechnete Erhöhung des Stoffdurchgangskoeffizienten stimmt mit Angaben in experimentellen Arbeiten anderer Autoren überein.
Keywords: Interfacial Phenomena, Marangoni Effect, Rayleigh-Bénard Instability, Double Diffusive Instability, Capillary Gap, Hele-Shaw Cell, Fingering Instability, Liquid-Liquid Mass Transfer, Chemical Reaction, Roll Cell, Thermal, Computational Fluid Dynamics
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-417 2005

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Permalink: https://www.hzdr.de/publications/Publ-6973
Publ.-Id: 6973


THz radiation and Bloch oscillations - old visions and new approaches

Winnerl, S.
Different ways of generation of THz radiation are reviewed and our scalable emitter for intense pulsed THz radiation is presented. In the second part of the talk issues ralated to Bloch gain such as the fundamental understanding of the role of scattering processes and the role of electric field domains are adressed. Our approach to search for Bloch gain is discussed.
Keywords: THz radiation, semmiconductor superlattices, Bloch gain
  • Lecture (others)
    Conensed matter theory seminar, 15.12.2004, Oulu, Finland

Permalink: https://www.hzdr.de/publications/Publ-6972
Publ.-Id: 6972


Dynamics of MSR

Krepel, J.; Grundmann, U.; Rohde, U.; Weiss, F.-P.
Dynamics of the Molten Salt Reactor - one of the 'Generation IV' concepts - was studied in this paper. The graphite-moderated channel type MSR was selected for the numerical simulation of the reactor with liquid fuel. The MSR dynamics is very specific because the fuel flow influences the delayed neutrons distribution. Presently, there are not many accessible numerical codes appropriate for the MSR simulation, therefore the DYN3D-MSR code was developed based on the FZR in-house code DYN3D. It allows calculating of full 3D transient neutronics in combination with parallel channel type thermal-hydraulics. By means of DYN3D-MSR, several transients typical for the liquid fuel system were analyzed. Those transients were initiated by reactivity insertion, by overcooling of fuel at the core inlet, by the fuel pump start-up or coast-down, or by the blockage of selected fuel channels. The results of these transient studies have shown that the dynamic behavior of MSR is acceptable with respect to the reactor safety.
Keywords: Molten Salt, Liquid Fuel, Reactor Dynamics, MSR
  • Contribution to proceedings
    Structural mechanics in reactor technology, SmiRT18, 08.-12.08.2005, Beijing, China

Permalink: https://www.hzdr.de/publications/Publ-6971
Publ.-Id: 6971


Plasma Immersion Ion Implantation Under Industrially Relevant Conditions

Ueda, M.; Wei, R.; Reuther, H.
Plasma Immersion Ion Implantation Under Industrially Relevant Conditions
  • Invited lecture (Conferences)
    The Second International Workshop on Particle Beams &Plasma Interaction on Material and, 25.11.2004, Chiang Mai, Thailand

Permalink: https://www.hzdr.de/publications/Publ-6970
Publ.-Id: 6970


V1000CT-1 benchmark analyses with the DYN3D/RELAP5 and DYN3D/ATHLET coupled code systems

Kozmenkov, Y.; Grundmann, U.; Kliem, S.; Rohde, U.; Weiss, F.-P.
Plant-measured data provided within the specification of the OECD/NEA VVER-1000 coolant transient benchmark (V1000CT) were used to validate the DYN3D/RELAP5 and DYN3D/ATHLET coupled code systems. Phase 1 of the benchmark (V1000CT-1) refers to the MCP (main coolant pump) switching on experiment conducted in the frame of the plant-commissioning activities at the Kozloduy NPP Unit 6 in Bulgaria. The experiment was started at the beginning of cycle (BOC) with average core expose of 30.7 effective full power days (EFPD), when the reactor power was at 27.5% of the nominal level and 3 of 4 MCPs were operating. The transient is characterized by a rapid increase in the primary coolant flow through the core and, as a consequence, a decrease of the space-dependent core inlet temperature. Control rods were not changing their positions during the transient. Both DYN3D/RELAP5 and DYN3D/ATHLET analyses were based on the same reactor model, including identical MCP characteristics, boundary conditions, benchmark-specified nuclear data library and nearly identical nodalization schemes. In addition to validation of the coupled code systems against measured data, a code-to-code comparison between simulation results has been performed to evaluate relevant thermohydraulic models of the system codes RELAP5 and ATHLET.
Keywords: Coupled code systems, 3D neutron kinetics, code validation, code-to-code comparison, VVER-1000 model, coolant transient benchmark, main coolant pump.
  • Contribution to proceedings
    11th International Top. Meeting on Nuclear Reactor Thermal-Hydraulics, 02.-06.10.2005, Avignon, France
    Proceedings CDROM paper 254
  • Lecture (Conference)
    11th International Top. Meeting on Nuclear Reactor Thermal-Hydraulics NURETH11, 02.-06.10.2005, Avignon, France

Permalink: https://www.hzdr.de/publications/Publ-6969
Publ.-Id: 6969


Atomistic study of the migration of di- and tri-interstitials in silicon

Posselt, M.; Gao, F.; Zwicker, D.
A comprehensive study on the migration of di- and tri-interstitials in silicon is performed using classical molecular dynamics simulations with the Stillinger-Weber potential. At first the structure and energetics of the di- and the tri-interstitial are investigated, and the accuracy of the interatomic potential is tested by comparing the results with literature data obtained by tight-binding and density-functional-theory calculations. Then the migration is investigated for temperatures between 800 and 1600 K. Very long simulation times, large computational cells and different initial conditions are considered. The defect diffusivity, the self-diffusion coefficient per defect and the corresponding effective migration barriers are calculated. Compared to the mono-interstitial, the di-interstitial migrates faster, whereas the tri-interstitial diffuses slower. The mobility of the di- and the mono-interstitial is higher than the mobility of the lattice atoms during the diffusion of these defects. On the other hand, the tri-interstitial mobility is lower than the corresponding atomic mobility. The migration mechanism of the di-interstitial shows a pronounced dependence on the temperature. At low temperature a high mobility on zigzag-like lines along a <110> axis within a {110} plane is found, whereas the change between equivalent <110> directions or equivalent {110} planes occurs seldom and requires a long time. At high temperature a frequent change between equivalent <110> directions or {110} planes is observed. During the diffusion within {110} planes the di-interstitial moves like a wave packet so that the atomic mobility is lower than that of the defect. On the other hand, the change between equivalent {110} migration planes is characterized by frequent atomic rearrangements. The visual analysis of the tri-interstitial diffusion reveals complex migration mechanisms and a high atomic mobility. The diffusivities and effective migration barriers obtained are compared with the few data from the literature. The implications of the present results for the explanation of experimental data on defect evolution and migration are discussed.
Keywords: defects, diffusion, silicon, computer simulations

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Publ.-Id: 6968


Structural and chemical characterization of functional SiOxCy:H coatings for polymeric lenses

Fernandez-Hidalgo, P.; Martin-Palma, R. J.; Conde, A.; Gago, R.; Simancas, J.; Garcia-Diego, I.; Egio, A.; Martinez-Duart, J. M.
The deposition of suitable hard protective coatings onto organic substrates for ophthalmic applications faces several challenges, such as proper surface preparation to ensure the adhesion to the rigid substrate and a delicate balance between hardness and flexibility. In this work it is shown that SiOxCy :H-based protective coatings grown by plasma enhanced chemical vapor deposition (PECVD) from mixtures of hexamethyldisiloxane and oxygen, can be used as protective buffer coatings between the soft and easily scratchable substrate and the antireflection stack that might be applied on top of it. These coatings must show absence of optical absorption and require index matching with the substrate. To meet these conditions, a three-phase multifunctional coating PECVD deposition method has been developed, in which a progressive decrease towards the surface in the carbon content of the SiOxCy:H hard coat has been implemented. Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy characterization of the individual layers that compose the multilayer functional structure has been performed. The comparison of the results obtained from each spectroscopy shows the complementarity of these techniques and allows optimizing the protective coating performance from the optical and mechanical points of view.
  • Journal of Vacuum Science and Technology B 22(2004)5, 2402-2408
    DOI: 10.1116/1.1795834

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Publ.-Id: 6967


First in-beam PET imaging with LSO/APD array detectors.

Crespo, P.; Kapusta, M.; Pawelke, J.; Moszynski, M.; Enghardt, W.
The performance and in-beam imaging capabilities of two position-sensitive gamma-ray detectors consisting of Hamamatsu avalanche photodiode arrays (S8550) individually coupled to crystals of cerium-doped lutetium oxyorthosilicate (LSO) are presented. The two detectors were operated in coincidence at the medical beam line of the Gesellschaft für Schwerionenforschung, in Darmstadt, Germany. In a first set of experiments, their imaging performance was tested before, during, and after the irradiation of phantoms of polymethylmethacrylate with carbon ion beams with fluences equivalent to 1000 typical daily therapeutic fractions. Only minor energy, time, and spatial resolution deterioration was observed, with the initial values being recovered after stopping the irradiation. A second set of experiments successfully imaged the depth distribution of positron emitter radionuclides created in a phantom that stopped the high-energy carbon ion beam. The particular details for the in-beam PET acquisition are shortly outlined. The obtained results show that LSO is a suitable material for in-beam PET and that its coupling with avalanche photodiode arrays is feasible for a PET system dedicated to in-beam monitoring of ion therapy.
Keywords: avalanche photodiode (APD), ion therapy, lutetium oxyorthosilicate (LSO), positron emission tomography (PET),proton therapy

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Publ.-Id: 6966


Synthesis of silicon nanocrystal memories by sputter deposition

Schmidt, J.-U.
Aim of this work was, to investigate the preparation of Si NC memories by sputter deposition. The milestones are as follows:
- Review of relevant literature.
- Development of processes for an ultrathin tunnel-oxide and high quality sputtered SiO2 for use as control-oxide.
- Evaluation of methods for the preparation of an oxygen-deficient silicon oxide inter-layer (the precursor of the Si NC layer).
- Characterization of deposited films.
- Establishment of techniques capable of probing the phase separation of SiOx and the formation of Si NC.
- Establishment of annealing conditions compatible with the requirements of current CMOS technology based on experimental results and simulations of Si NC formation.
- Preparation Si NC memory capacitors using the developed processes.
- Characterization of these devices by suitable techniques. Demonstration of their memory functionality.
Keywords: Sputter deposition, Silicon nanocrystals, charge storage, Nanocrystal MOS devices
  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-425 2005

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Permalink: https://www.hzdr.de/publications/Publ-6965
Publ.-Id: 6965


Neptunium(V) Reduction by Various Natural and Synthetic Humic Substances

Schmeide, K.
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field (HUPA)", 18.-19.10.2004, Karlsruhe, Germany

Permalink: https://www.hzdr.de/publications/Publ-6964
Publ.-Id: 6964


Untersuchung der Redoxstabilität von Neptunium(V) in Gegenwart natürlicher und synthetischer Huminstoffe

Schmeide, K.
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Migration von Actiniden im System Ton, Huminstoff, Aquifer", 12.-13.10.2004, Heidelberg, Germany

Permalink: https://www.hzdr.de/publications/Publ-6963
Publ.-Id: 6963


Auswertung der Komplexierungsdatenbasis bezüglich weiterführender Experimente und der Weiterentwicklung des Ladungsneutralisationsmodells

Schmeide, K.; Brendler, V.
  • 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-6962
Publ.-Id: 6962


Colloid-chemical Investigation of the Kaitzbach Stream

Schmeide, K.; Zänker, H.; Weiß, S.; Ulrich, K.-U.
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field (HUPA)", 26.-27.04.2004, Budapest, Hungary

Permalink: https://www.hzdr.de/publications/Publ-6961
Publ.-Id: 6961


CFD- analysis of the mixing pattern under various flow conditions at the ROCOM test facility using CFX-5

Höhne, T.; Kliem, S.; Rohde, U.
The coolant mixing in the downcomer and the lower plenum of pressurized water reactors (PWR) is significant for safety assessment of boron dilution and cold water transients.

The research project FLOMIX-R within the 5th Framework Programme of EC had the objective to obtain experimental data on the relevant coolant mixing phenomena using improved measurement techniques with enhanced resolution in space and time for CFD validation.

Recent experiments at the Rossendorf test facility ROCOM were integrated into this research project. ROCOM is a 1:5 scaled Plexiglas model of a German PWR allowing conductivity measurements by wire mesh sensors for analyzing the mixing pattern at selected positions in the reactor pressure vessel and velocity measurements by LDA technique.

A few benchmark problems based on selected experiments were used to study the effect of different turbulent mixing models under various flow conditions, to investigate the influence of the geometry, the boundary conditions, the grid and the time step in the CFD analyses. In doing the calculations the Best Practice Guidelines for nuclear reactor safety calculations have been followed. Results of this numerical mixing studies will be discussed.
Keywords: FLOMIX-R, CFD, Coolant Mixing, ROCOM, PWR
  • Lecture (Conference)
    13th International Conference on Nuclear Engineering 2005, 16.05.2005, Beijing, China
  • Contribution to proceedings
    13th International Conference on Nuclear Engineering, 16.-20.05.2005, Beijing, China
    CD-ROM

Permalink: https://www.hzdr.de/publications/Publ-6960
Publ.-Id: 6960


Numerical modelling of a transient slug mixing experiment of the ROCOM test facility using CFX-5

Höhne, T.
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
  • 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
Publ.-Id: 6959


Numerical modelling of a buoyancy driven flow in a reactor pressure vessel using CFX-5

Höhne, T.; Scheuerer, M.; Kliem, S.
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
  • 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
Publ.-Id: 6958


Thermochromatographic Adsorption Studies of Curium and Berkelium

Hübener, S.; Eichler, B.; Taut, S.
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
  • 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

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Publ.-Id: 6957


Experimental modelling and CFD simulation of air/water flow in a horizontal channel

Vallee, C.; Höhne, T.; Prasser, H.-M.; Sühnel, T.
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
  • 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
Publ.-Id: 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.
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)

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Publ.-Id: 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.
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

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Publ.-Id: 6952


Uranium sorption and solubility under conditions relevant for the radioactive waste repository in Morsleben / Germany

Nebelung, C.; Baraniak, L.
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
  • 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

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Publ.-Id: 6951


Study of the Neptunium(V) Reduction by Various Natural and Synthetic Humic Substances

Schmeide, K.; Geipel, G.; Bernhard, G.
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
  • 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).

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Publ.-Id: 6950


Untersuchungen zur Huminstoffbildung in Gegenwart von Kaolinit

Sachs, S.
  • 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
Publ.-Id: 6949


Studies on the Redox Behavior of Humic Acids and the Redox Stability of U(VI) Humate Complexes

Sachs, S.
  • 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
Publ.-Id: 6948


Solubility Studies of Uranium(IV) by Laser-Induced Breakdown Detection (LIBD)

Opel, K.; Hübener, S.; Weiß, S.; Zänker, H.; Bernhard, G.
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
  • 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

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Publ.-Id: 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.
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

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Publ.-Id: 6946


Synthese und Untersuchung von Substraten der viralen Thymidinlkinase und Fluor –18 Markierung geeigneter Verbindungen zum Monitoring der Geneexpression

Grote, M.
  • Lecture (others)
    Forschungszentrum Jülich, 16.12.2004, Jülich, Germany

Permalink: https://www.hzdr.de/publications/Publ-6945
Publ.-Id: 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.
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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Permalink: https://www.hzdr.de/publications/Publ-6944
Publ.-Id: 6944


Aktuelle Ergebnisse Fluoreszenzspektroskopischer Untersuchungen an Aktiniden und organischen Liganden

Geipel, G.
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.
  • Invited lecture (Conferences)
    BAM Berlin, 21.12.2004, Berlin, Germany

Permalink: https://www.hzdr.de/publications/Publ-6941
Publ.-Id: 6941


Stability of an electromagnetically levitated spherical sample in a set of coaxial circular loops

Priede, J.; Gerbeth, G.
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

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Publ.-Id: 6940


Untersuchungen zur Bindungsstruktur von kolloidgetragenem Uran mit EXAFS und ATR-FTIR

Ulrich, K.-U.; Foerstendorf, H.; Rossberg, A.; Weiß, S.; Zänker, H.
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.
  • 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
Publ.-Id: 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.
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.
  • Other report
    ERL - Report ERL 04-10, 2004

Permalink: https://www.hzdr.de/publications/Publ-6938
Publ.-Id: 6938


Operation Experience with the ELBE Helium Plant

Schneider, C.
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.
  • Lecture (Conference)
    Conference Cryogenics Operations 2004, Jefferson Laboratory, 30.03.-02.04.2004, Newport News, USA

Permalink: https://www.hzdr.de/publications/Publ-6937
Publ.-Id: 6937


Reduced sub-picosecond electron relaxation in GaNAs

Sinning, S.; Dekorsy, T.; Helm, M.; Mussler, G.; Däweritz, L.; Ploog, K. H.
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

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Permalink: https://www.hzdr.de/publications/Publ-6936
Publ.-Id: 6936


RPV investigations of Greifswald WWER-440 units: New dosimetry results and material testing concepts

Konheiser, J.; Rindelhardt, U.; Viehrig, H.-W.
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
  • 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
Publ.-Id: 6935


Bildung von eisenhaltigen Kolloiden bei der Verwitterung von Gesteinsmaterial

Zänker, H.; Arnold, T.; Hüttig, G.
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
  • 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
Publ.-Id: 6934


Modeling and regrowth mechanisms of flash lamp processing of SiC-on-silicon heterostructures

Smith, M.; Mcmahon, R.; Voelskow, M.; Skorupa, W.
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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Permalink: https://www.hzdr.de/publications/Publ-6932
Publ.-Id: 6932


Hochfrequenz-Elektronenquelle

Janssen, D.
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.
  • Patent
    Patentanmeldung DE 10 2004 055 256.8

Permalink: https://www.hzdr.de/publications/Publ-6931
Publ.-Id: 6931


Kohärente Terahertz-Strahlungsquelle

Dekorsy, T.; Dreyhaupt, A.; Winnerl, S.; Helm, M.
Die Strahlungsquelle kann im Frequenzbereich von 10 GHz bis 50 THz arbeiten und spezielle Parameter erfüllen.
  • Patent
    Patentanmeldung DE 10 2004 046 123.6

Permalink: https://www.hzdr.de/publications/Publ-6929
Publ.-Id: 6929


Insulinresistenz (IR) und Lipoprotein (Lp)-subfraktionen (Sf) bei verschiedenen Graden der Glukosetoleranz (GT)

Weck, A.; Julius, U.; Pietzsch, J.
  • 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
Publ.-Id: 6928


Rheumatoid arthritis synovial fluid LDL induce monocyte chemotaxis and adhesion

Pietzsch, J.; Bergmann, R.; Kopprasch, S.
  • 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
Publ.-Id: 6927


Anlage zur gesteuerten Erstarrung von Schmelzen elektrisch leitender Medien

Eckert, S.; Nikrityuk, P.; Grundmann, R.; Eckert, K.
Es werden Instabilitäten gedämpft und das Kornwachstum während der Erstarrung von Legierungen gesteuert.
  • Patent
    Patentanmeldung DE 10 2004 044 637.7

Permalink: https://www.hzdr.de/publications/Publ-6926
Publ.-Id: 6926


Analysis of specific markers of protein oxidation in rheumatoid arthritis plasma and synovial fluid LDL

Pietzsch, J.; Bergmann, R.; Kopprasch, S.
  • 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
Publ.-Id: 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.
  • Poster
    42. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin, 21.-24.04.2004, Rostock

Permalink: https://www.hzdr.de/publications/Publ-6924
Publ.-Id: 6924


P0408-Faseroptischer Sensor zur Bestimmung von Stoff- und Phasenverteilungen

Hampel, U.; Schleicher, E.
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
Publ.-Id: 6923


Increased LDL apolipoprotein B-100 oxidation in IGT and overt Type 2 diabetes

Julius, U.; Pietzsch, J.
  • 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
Publ.-Id: 6922


Vorrichtung zur Vermeidung von Druckstößen in Rohrleitungssystemen

Prasser, H.; Dudlik, A.; Apostolidis, A.; Schlüter, S.; Wickl, G.
Es wird eine kostengünstig zu realisierende und zuverlässig arbeitende Armatur in Rohrleitungssystemen angegeben.
  • 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
Publ.-Id: 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.
Es werden radiolytisch und metabolisch stabile Metallkomplexe vorgeschlagen, die zur Konjugation mit Biomolekülen geeignet sind sowie ein Verfahren zu ihrer Herstellung.
  • Patent
    DE 10 2004 022 461 A1

Permalink: https://www.hzdr.de/publications/Publ-6920
Publ.-Id: 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.
  • 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
Publ.-Id: 6918


Lipoprotein kinetics as measured with stable isotopes in familial combined hyperlipidemia and impaired glucose tolerance

Julius, U.; Pietzsch, J.
  • Poster
    15th International Symposium on Drugs Affecting Lipid Metabolism (DALM), Venedig , 24.-27.10.2004

Permalink: https://www.hzdr.de/publications/Publ-6917
Publ.-Id: 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.
  • Poster
    15th International Symposium on Drugs Affecting Lipid Metabolism (DALM), Venedig, 24.-27.10.2004

Permalink: https://www.hzdr.de/publications/Publ-6916
Publ.-Id: 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.
  • 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
Publ.-Id: 6915


Transition metal-mediated C-C and C-N bond forming reactions with the short-lived positron emitters 11C and 18F

Wüst, F.
  • Invited lecture (Conferences)
    Washington University, School of Medicine St. Louis, 12.10.2004, Washington, USA

Permalink: https://www.hzdr.de/publications/Publ-6914
Publ.-Id: 6914


Radiopharmaceutical Chemistry at the PET Center Rossendorf

Wüst, F.
  • Invited lecture (Conferences)
    Washington University, School of Medicine St. Louis, 08.10.2004, Washington, USA

Permalink: https://www.hzdr.de/publications/Publ-6913
Publ.-Id: 6913


Positronen-Emissions-Tomographie (PET): Wie radioaktive Substanzen den Körper biochemisch transparent machen

Wüst, F.
  • Lecture (others)
    Tag der offenen Tür, Forschungszentrum Rossendorf, 18.09.2004, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-6912
Publ.-Id: 6912


PET Radiochemistry and the Potential of PET in Drug Development and Evaluation

Wüst, F.
  • Invited lecture (Conferences)
    Boehringer Ingelheim, 07.04.2004, Germany

Permalink: https://www.hzdr.de/publications/Publ-6911
Publ.-Id: 6911


Aspekte der PET-Radiochemie in der Lebensmittelchemie

Wüst, F.
  • Lecture (others)
    1. Workshop Positronen-Emissions-Tomographie in der Lebensmittelforschung, 17.05.2004, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-6910
Publ.-Id: 6910


In vino sanitas. Den Geheimnissen des Weines auf der Spur

Pietzsch, J.
  • Lecture (others)
    Vortrag zur „Langen Nacht der Wissenschaften“, 25.06.2004, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-6909
Publ.-Id: 6909


Metabolismus oxidierter Proteine in vivo: Einblicke mit Kleintier-PET-Untersuchungen

Pietzsch, J.
  • Lecture (others)
    1. Workshop „Positronen-Emissions-Tomographie in der Lebensmittelforschung“, 17.05.2004, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-6908
Publ.-Id: 6908


Radiomarkierung von Polyphenolen und Flavonoiden mit PET-Radionukliden

Gester, S.
  • Lecture (others)
    1. Workshop Positronen-Emissions-Tomographie in der Lebensmittelforschung, 17.05.2004, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-6907
Publ.-Id: 6907


PET in clinical oncology and research

Beuthien-Baumann, B.
  • 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
Publ.-Id: 6906


Früh- und Differentialdiagnose von Parkinsonsyndromen: Teilgebiet Nuklearmedizinische Diagnostik

Beuthien-Baumann, B.
  • Lecture (others)
    Klinische Visite Parkinson, 03.09.2004, Universitätsklinikum Carl Gustav Carus, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-6905
Publ.-Id: 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.
  • 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
Publ.-Id: 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
Publ.-Id: 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.
  • 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
Publ.-Id: 6902


Early Alzheimer’s 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
Publ.-Id: 6901


Quanten-Kaskaden-Laser-Struktur

Georgiev, N.; Dekorsy, T.; Helm, M.; Semtsiv, M.; Dreßler, S.; Ziegler, M.; Masselink, W.
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
Publ.-Id: 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
Publ.-Id: 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.
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
Publ.-Id: 6898


Verfahren zur Verbesserung der Strahleigenschaften einer supraleitenden Hochfrequenz-Fotoelektronenquelle

Janssen, D.
Mit der Erfindung soll die Effektivität der supraleitenden HF-Fotoelektrode und die Strahleigenschaft, insbesondere die transversale Emittanz, für mittlere und hohe Leistungen verbessert werden.
  • Patent
    DE 10 2004 005 612 A1

Permalink: https://www.hzdr.de/publications/Publ-6897
Publ.-Id: 6897


Hydromechanische Maschine

Hoppe, D.; Kernchen, R.
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
Publ.-Id: 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
Publ.-Id: 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.
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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Permalink: https://www.hzdr.de/publications/Publ-6894
Publ.-Id: 6894


Forschung für Mensch und Umwelt 2001/2002

Ottow, S.; (Editor)
  • Open Access Logo Wissenschaftlich-Technische Berichte FZR-349 Januar 2003

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Permalink: https://www.hzdr.de/publications/Publ-6893
Publ.-Id: 6893


Far-IR spectroscopy of the nonlinear susceptibility of GaAs with an FEL

Dekorsy, T.; Helm, M.; Yakovlev, V.; Seidel, W.; Keilmann, F.
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
  • 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
Publ.-Id: 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.
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
  • Journal of Labelled Compounds and Radiopharmaceuticals 48(2005), 31-43
    DOI: 10.1002/jlcr.893

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Permalink: https://www.hzdr.de/publications/Publ-6887
Publ.-Id: 6887


Recursively Coupled FEM-Analysis Of Pressure Vessel Creep Failure Experiments

Willschütz, H.-G.; Altstadt, E.; Weiss, F.-P.
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
  • 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 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
Publ.-Id: 6878


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