Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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34122 Publications

ROBL - Synchrotronstrahlung für Ökologie und Materialforschung

Matz, W.

Populärwissenschaftliche Darstellung von ROBL. Beispiele zu Experimente im Bereich der Ökoradiochemie (Abwässer des Uranbergbaus) und der Materialforschung.

  • Lecture (others)
    Vortrag zum Tag der Offenen Tür des FZR , 11. September 1999

Permalink: https://www.hzdr.de/publications/Publ-3197
Publ.-Id: 3197


Elektronenbeschleuniger als Quellen elektromagnetischer Strahlung

Matz, W.; Seidel, W.

Erzeugung und Eigenschaften von Synchrotronstrahlung und Infrarotstrahlung aus FEL; Ausgewählte Anwendungsbeispieöle aus Physik, Werkstofforschung, Umweltstudien und Medizin.

Keywords: Synchrotronstrahlung; IR-Strahlung; FEL

  • Lecture (others)
    Lehrerfortbildung ´99 im FZR, 26. August 1999

Permalink: https://www.hzdr.de/publications/Publ-3195
Publ.-Id: 3195


Possibilities for real-time experiments at ROBL

Matz, W.

Description of the experimental set-up of the Materials Research Hutch. Report of first results from structural follow-up during in-situ annealing experiments. Discussion of possibilities for a in-situ deposition chamber.

Keywords: ROBL; high-temperature experiments; diffraction studies

  • Lecture (Conference)
    Workshop on real-time studies with x-ray synchrotron radiation, HMI Berlin, 21. Juni 1999

Permalink: https://www.hzdr.de/publications/Publ-3194
Publ.-Id: 3194


ROBL - a synchrotron research facility for the Institute of Ion Beam Physics and Materials Research of the FZR

Matz, W.; Schell, N.; Prokert, F.; Eichhorn, F.; Berberich, F.

Description of the Materials Research Set-up of ROBL. Presentation of the results obtained in the first year of operation.

Keywords: ROBL; X-ray diffraction; X-ray reflectometry

  • Poster
    Symposium 25 Jahre Strukturforschung am Lehrstuhl Prof. J. Peisl, LMU München, 12.-13. Nov. 1999

Permalink: https://www.hzdr.de/publications/Publ-3193
Publ.-Id: 3193


ROBL - a CRG Beam Line at the ESRF Dedicated to Radiochemistry and Materials Research

Matz, W.

Description of ROBL, its experimental possibilities and the research oppotunities for east European scientist under EC funding.

Keywords: ROBL

  • Lecture (Conference)
    European Round Table for Synchrotron Radiation and FEL, Meeting in Krakow, Poland, Nov. 9-10, 1999

Permalink: https://www.hzdr.de/publications/Publ-3192
Publ.-Id: 3192


BWR Physics and Thermohydraulics Complementary Actions to the IPSS - BWR R&D Cluster

Fiorini, G. L.; Friesen, E.; van der Hagen, T.; Lopez Jimenez, J.; Meloni, P.; Rindelhardt, U.

The project contributed to answer issues which are identified for future BWR plants:
- The design of innovative components
- An enlarged assesment of the performances
- A better understanding of the underlying physical phenomena.
The paper summarizes the main results of the project.

  • Lecture (Conference)
    Proc. of the FISA-99 Symposium on EU Research in Reactor Safety, Luxembourg, 29 November - 1 December 1999, p. 682
  • Contribution to proceedings
    Proc. of the FISA-99 Symposium on EU Research in Reactor Safety, Luxembourg, 29 November - 1 December 1999, p. 682

Permalink: https://www.hzdr.de/publications/Publ-3191
Publ.-Id: 3191


Balakovo-3 Ex-vessel Exercise: Intercomparison of Results

Borodkin, G. I.; Kovalevich, O. M.; Barz, H.-U.; Böhmer, B.; Stephan, I.; Ait Abderrahim, H.; Voorbraak, W.; Hogel, J.; Polke, E.; Schweighofer, W.; Seren, T.; Borodin, A. V.; Vikhrov, V. I.; Lichadeev, V. V.; Markina, N. V.; Grigoriev, E. I.; Troshin, V. S.; Penev, I.; Kinova, L.

The results of an intercomparison of neutron dosimetry measurements in the ex-vessel cavity of VVER-1000 type reactor are submitted. A good agreement of measured results of different independent participants was found for the different activation reactions. Evaluated absolute dosimetry data are presented. Also good agreement of neutron transport calculation results obtained by as Sn and Monte Carlo methods by independent laboratories with measurements is demonstrated.




Keywords: VVER; reactor cavity; dosimeter; dosimetry reactions; measurements; intercomparison; calculations

  • Lecture (Conference)
    Tenth International Symposium on Reactordosimetry, 12.- 17. 9. 1999, Osaka, Japan, ASTM STP 1398
  • Contribution to proceedings
    Tenth International Symposium on Reactordosimetry, 12.- 17. 9. 1999, Osaka, Japan, ASTM STP 1398

Permalink: https://www.hzdr.de/publications/Publ-3190
Publ.-Id: 3190


Monte Carlo Calculations of Neutron Fluence Spectra, Activation Measurements, Uncertainty Analysis and Spectrum Adjustment for the KORPUS Dosimetry Benchmark

Barz, H.-U.; Böhmer, B.; Konheiser, J.; Stephan, I.

: The KORPUS irradiation experiment has been used to test and demonstrate improvements of the pressure vessel dosimetry methodology developed in Rossendorf. The Monte Carlo Code TRAMO has been recently supplied with a new data treatment procedure for elastic scattering and with extended geometries. The new code version has been used to accurately calculate absolute neutron fluence spectra at detector positions in the KORPUS irradiation facility at the RIAR in Dimitrovgrad. The influence of used approximations on the obtained fluences was investigated with calculations for different model variants.
The activation rates calculated with these spectra have been compared with results of activation measurements with detectors irradiated at the International Dosimetry Benchmark at the KORPUS facility. Based on the measured data the calculated fluence spectra have been adjusted with help of the adjustment code system COSA3, a newly extended multispectrum version of COSA2. A comprehensive uncertainty analysis was accomplished for the fluence calculations and the measurements.


Keywords: KORPUS facility; Monte Carlo; transport calculation; TRAMO-code; activation measurements; spectrum adjustment; uncertainty analysis

  • Poster
    Tenth International Symposium on Reactordosimetry, 12.- 17. 9. 1999, Osaka, Japan, ASTM STP 1398
  • Contribution to proceedings
    Tenth International Symposium on Reactordosimetry, 12.- 17. 9. 1999, Osaka, Japan, ASTM STP 1398

Permalink: https://www.hzdr.de/publications/Publ-3189
Publ.-Id: 3189


Improved Covariance Analysis and Spectrum Adjustment for VVER-1000 Pressure Vessel Fluences

Böhmer, B.; Borodkin, G. I.; Manturov, G. N.

The assessment of the uncertainties of neutron transport calculation results caused by uncertainties of the input data is important for the direct use of the calculated fluences and even indispensable for the further improvement of the data by spectrum adjustment on the basis of experimental results. A former work of two of the authors has approached this topic first for a VVER-1000 using a one-dimensional reactor model and applying spectrum adjustment in a single spectrum approximation. In the present work 2D/1D-SN-synthesis calculations have been used to determine the neutron group spectrum covariances including cross-correlations between interesting positions. As possible sources of uncertainties neutron data and reactor model parameters were considered, whereas the uncertainties caused by the calculational method were considered negligible in view of the now available precision of Monte Carlo simulations. The input data uncer-tainties have been updated including newer information.
The calculated absolute group fluence spectra have been adjusted to measured ex-vessel cavity activation rates with help of the COSA3 generalized least squares multispectrum adjustment code. Adjusted fluences for different detector positions have been compared with corresponding fluences obtained with single spectrum adjustments. The results are discussed and conclusions have been drawn. Results obtained with Russian LUND- and ENDF/B-VI-based cross section and fission spectrum covariance data have been compared.


Keywords: Neutron transport calculation; sensitivity analysis; covariances; activation measurements; spectrum adjustment

  • Poster
    Tenth International Symposium on Reactordosimetry, 12.- 17. 9. 1999, Osaka, Japan, ASTM STP 1398
  • Contribution to proceedings
    Tenth International Symposium on Reactordosimetry, 12.- 17. 9. 1999, Osaka, Japan, ASTM STP 1398

Permalink: https://www.hzdr.de/publications/Publ-3188
Publ.-Id: 3188


Glutathione interaction with SNS/S mixed ligand complexes of oxorhenium(V): Kinetic aspects and characterization of the products

Nock, B.; Maina, T.; Tsortos, A.; Pelecanou, M.; Raptopoulou, C. P.; Papadopoulos, M.; Pietzsch, H.-J.; Stassinopoulou, C.; Terzis, A.; Spies, H.; Nounesis, G.; Chiotellis, E.

A series of oxorhenium(V) SNS/S mixed ligand complexes [ReO(Ln/L)] carrying different types of tridentate ligand [L1: C2H5N(CH2CH2S)2, L2: (C2H5)2NCH2CH2N(CH2CH2S)2, L3: C2H5SCH2CH2N(CH2CH2S)2 and L4: 2,6-(SCH2)2NC5H3] and the same monodentate coligand (L: C6H5S) have been synthesized and characterized by spectroscopic methods and elemental analyses. X-ray structure determination was performed for complexes 3 and 4. Complex 3 adopts the expected distorted trigonal bipyramidal geometry around the metal in a syn configuration, while complex 4, due to the aromatic character of the nitrogen of the SNS donor-atom set, exhibits a distorted square pyramidal geometry. The interaction of complexes 1 - 4 with glutathione (GSH) was studied by high performance liquid chromatography (HPLC), revealing the rapid formation of the respective daughter complexes 5 - 8, wherein the L coligand has been substituted by GS. The daughter complexes 5 - 8 have been characterized by ES-MS and a battery of NMR measurements involving HETCOR, COSY and NOESY procedures. Kinetic aspects of the interaction of complexes 1 ¾ 3 with GSH have been studied by isothermal titration microcalorimetry providing direct measurements of the interaction rate constants as well as the total enthalpy change. The reaction of complex 1 is characterized by the slowest and that of complex 2 by the fastest rate. This is in agreement with previously reported trends for analogous 99mTc complexes.

Keywords: oxorhenium complexes; X-ray structure determination; glutathion exchange; kinetic and thermodynamic investigations; microcalorimetry

  • Inorganic Chemistry 39 (2000) 4433-4441

Permalink: https://www.hzdr.de/publications/Publ-3186
Publ.-Id: 3186


Validation of 3D Synthesis RPV Neutron Fluence Calculations using VVER-1000 Ex-Vessel Reference Dosimetry Results (Invited Paper)

Borodkin, G.; Böhmer, B.

3D synthesis based on detailed and improved calculations by SN-codes DORT, ANISN and the BUGLE-96 library has been validated using reference activation data from the Balakovo-3 ex-vessel dosimetry benchmark. The 3D spatial neutron source distribution including pin-to-pin power variations and the complex baffle construction were modeled in detail. All particulars of reactor operation such as coolant temperature changes, assembly power asymmetry and fuel burnup influence on space-energy neutron source distributions were taken into account.
The discrepancies found do not exceed 10%. The average relation between calculated and measured valuse is 0,99. The calculated results show a systematic underestimation for 237Np(n,f) ( -6% on the average), 93Nb(n,n') ( -8%) and systematic overestimation for 58Ni(n,p) and 54Fe(n,p) ( +7%). Generally, the agreement between experiment and calculation is even closer as expected from uncertainty considerations.

  • Lecture (Conference)
    2000 ANS Annual Meeting, San Diego, California, June 4-8 2000, Trans. Am. Nucl. Soc., Vol.82,p.223-225 (2000)
  • Contribution to proceedings
    2000 ANS Annual Meeting, San Diego, California, June 4-8 2000, Trans. Am. Nucl. Soc., Vol.82,p.223-225 (2000)

Permalink: https://www.hzdr.de/publications/Publ-3185
Publ.-Id: 3185


Ion beam synthesis of graphite and diamond in silicon carbide

Heera, V.; Skorupa, W.; Pécz, B.; Dobos, L.

A high dose of 1x1018 cm-2, 60 keV carbon ions was implanted into single crystalline 6H silicon carbide (SiC) at elevated temperatures. The formation of carbon phases in the crystalline SiC lattice was investigated by cross sectional transmission electron microscopy. An amorphous, carbon rich phase was produced at 300oC. Precipitates of graphite were obtained at 600oC, whereas at 900oC small diamond grains were produced. These grains are in perfect epitaxial relation with the surrounding SiC lattice.

Keywords: Ion implantation; Ion beam synthesis; carbon; silicon carbide; diamond

  • Applied Physics Letters Vol. 76, Nr. 20, 15 May 2000, 2847-2849

Permalink: https://www.hzdr.de/publications/Publ-3184
Publ.-Id: 3184


Characterization of RF-sputtered platinum films by positron annihilation spectroscopy

Brauer, G.; Anwand, W.; Nicht, E.-M.; Kuriplach, J.; Prochazka, I.; Becvar, F.; Osipowicz, A.; Coleman, P. G.

Pt films on alumina substrates, both in their as-received and annealed states, have been extensively characterized by slow positron implantation spectroscopy (SPIS). Bulk Pt samples have been investigated by conventional positron annihilation spectroscopy (PAS) as well as by SPIS. A variety of state-of-the-art theoretical calculations have been performed to aid the interpretation of experimental findings. The research shows that a re-interpretation of earlier defect studies of bulk Pt by PAS is required in order to achieve a satisfactory agreement with the present experimental findings and theory.

Keywords: slow positron implantation spectroscopy (SPIS); conventional positron annihilation spectroscopy (PAS); Pt films on alumina; defect states; self-consistent LMTO calculations; atomic superposition calculations

  • Phys.Rev.B Vol. 62, No. 8, (2000) 5199-5206

Permalink: https://www.hzdr.de/publications/Publ-3183
Publ.-Id: 3183


Analysis of the OECD MSLB Benchmark using the Coupled Code DYN3D/ATHLET

Kliem, S.; Grundmann, U.; Rohde, U.

A full power MSLB analysis for the TMI-1 NPP using the coupled code DYN3D/ATHLET was performed in the frame of the OECD Benchmark for coupled neutron kinetics/thermohydraulics codes. The analysis shows a return-to-power after the scram. The impact of the description of coolant mixing inside the reactor pressure vessel was investigated. The exclusion of the coolant mixing enhances this second power peak by about a factor of two in comparison to the first calculation, where the coolant mixing is treated by means of an experimentally determined mixing ratio. The neglection of mixing applied in point kinetics calculations with compatible feedback coefficients shows the opposite effect on the obtained reactor power.

  • Contribution to proceedings
    Eighth International Conference on Nuclear Engineering (ICONE-8) 2000, Baltimore (USA), 2.-6. April 2000, Proceedings (CD-ROM) paper 8696
  • Lecture (Conference)
    Eighth International Conference on Nuclear Engineering (ICONE-8) 2000, Baltimore (USA), 2.-6. April 2000
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai 2000, Tagungsbericht S. 7-10
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai 2000

Permalink: https://www.hzdr.de/publications/Publ-3182
Publ.-Id: 3182


Nitrierung nichtrostender Stähle ohne Verlust ihrer Korrosionsbeständigkeit

Günzel, R.; Richter, E.; Möller, W.; Brusky, U.; Spies, H.-J.; Rammelt, U.; Plieth, W.

  • Freiberger Forschungshefte B 297 (1999)

Permalink: https://www.hzdr.de/publications/Publ-3181
Publ.-Id: 3181


DYN3D - Three Dimensional Core Model for Steady-State and Transient Analysis of Thermal Reactors

Grundmann, U.; Rohde, U.; Mittag, S.

DYN3D is a three-dimensional computer code for calculating transients in light-water reactor cores with quadratic (version DYN3D/R) or hexagonal (version DYN3D/H) fuel assembly geometry. Starting from the critical state (keff - value, critical boron concentration or critical power) the code allows to simulate the neutroniand thermal-hydraulic core response to reactivity changes caused by control rod movements and/or changes of the coolant core inlet conditions. Burn-up calculations can be performed. The depletion state can used as starting point for the transient. The steady state and transient Xe and Sm concentrations can be analyzed. The decay heat is takeinto account.

Keywords: LWR reactors; fuel rods; heat transfer; hexagonal-z; Cartesian geometry; neutron diffusion equation; flux; power distribution; reactivity; reactor cores; reactor kinetics; reactor safety; thermodynamics; three-dimensional; steady state conditions; transients; two-group theory; two-phase flow

  • Lecture (Conference)
    PHYSOR 2000 - Advances in Reactor Physics and Mathematics and Computation into the Next Millennium, Pittsburgh (USA), May 7-12,2000, Proceedings on CD-ROM, ANS Order No. 2700281
  • Contribution to external collection
    PHYSOR 2000 - Advances in Reactor Physics and Mathematics and Computation into the Next Millennium, Pittsburgh (USA), May 7-12,2000, Proceedings on CD-ROM, ANS Order No. 2700281

Permalink: https://www.hzdr.de/publications/Publ-3179
Publ.-Id: 3179


CAN EXTENDED DUALITY UNIQUELY EXPLAIN THE DILEPTON DATA IN HIC'S AT SPS?

Kämpfer, B.; Gallmeister, K.; Pavlenko, O.

Extended duality (i.e. the replacement of the thermal dilepton emissivity of hadron matter by that of q bar q annihilation)
is used to explain the dilepton data of heavy-ion experiments at CERN-SPS. Taking into account the background contributions (hadronic cocktail, Drell-Yan, semileptonic open charm decays) the spectral shapes of the CERES, NA38/50 and HELIOS-3 data in experiments with lead and sulfur beams can be well described while the normalizations of the sulfur beam data is problematic.

Keywords: dileptons; heavy-ion collisions

  • Contribution to HZDR-Annual report
    Proc. Hirschegg Meeting 2000, p. 219

Permalink: https://www.hzdr.de/publications/Publ-3178
Publ.-Id: 3178


The hydrolysis of dioxouranium(VI) investigated using EXAFS and 170-NMR

Moll, H.; Reich, T.; Szabo, Z.

The structure of dioxouranium(VI) as a function of pH at different (CH3)4N-OH concentrations has been investigated with the aid of U LIII EXAFS. Polynuclear hydroxo species were identified by an U-U interaction at 3.808 Å at pH = 4.1. The precipitate formed at pH = 7 has a schoepite like structure. In solution at high pH [0.5M (CH3)4N-OH], the EXAFS and data are consistent with the formation of a monomeric four coordinated uranium(VI) hydroxide complex UO2(OH)42- of octahedral geometry. The first shell contains two O atoms with a U=O distance of 1.830 Å, and four O atoms were identified at a U-O distance of 2.266 Å.
In strong alkaline solutions [> 1 M (CH3)4N)-OH], 17O-NMR spectra indicate the presence of two species, presumably UO2(OH)42- and UO2(OH)53-, which are in rapid equilibrium with one another at 268 K in aqueous solution.

Keywords: EXAFS; Uranyl; Hydrolysis; Structure; 17O-NMR

  • Radiochimica Acta 88(2000),411-415

Permalink: https://www.hzdr.de/publications/Publ-3176
Publ.-Id: 3176


HPLC-Analyse des Metabolismus von 6-[18F]Fluor-L-DOPA (FDOPA) im neonatalen Schweinehirn.

Vorwieger, G.; Brust, P.; Bauer, R.; Walter, B.; Bergmann, R.; Steinbach, J.; Füchtner, F.; Johannsen, B.

  • Lecture (Conference)
    35. Intern. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin e.V., Kassel 16.4.-19.4.1997.
  • Abstract in refereed journal
    Nuklearmedizin 36 (1997) A82.

Permalink: https://www.hzdr.de/publications/Publ-3175
Publ.-Id: 3175


Metabolism of L-6-[18F]fluoro-3,4-dihydroxyphenylalanine (FDOPA) in plasma and brain of neonatal pigs under the conditions of asphyxia.

Vorwieger, G.; Brust, P.; Walter, B.; Bergmann, R.; Bauer, R.; Steinbach, J.; Füchtner, F.; Johannsen, B.

  • Abstract in refereed journal
    J. Cereb. Blood Flow Metab. 17 (1997) S159

Permalink: https://www.hzdr.de/publications/Publ-3174
Publ.-Id: 3174


Production of Φ Mesons in Near-Threshold πN and N N Reactions

Titov, A.; Kämpfer, B.; Reznik, B.

We analyze the production of Φ mesons in πN and NN reactions in the near-threshold region, using throughoutly the conventional "non-strange'' dynamics based on such processes which are allowed by the non-ideal ω - Φ mixing.
We show that the occurrence of the direct Φ NN interaction may show up in different unpolarized and polarization observables in π N to NΦ reactions. We find a strong non-trivial difference between observables in the reactions pp to ppΦ and pn to pnΦ caused by the different role of the spin singlet and triplet states in the entrance channel for the Φ meson production mechanisms. A series of predictions for the experimental study of this effect is presented.

Keywords: pp reactions; phi production

  • European Physical Journal A7:543-557,2000 nucl-th/0001027

Permalink: https://www.hzdr.de/publications/Publ-3173
Publ.-Id: 3173


The Solar Proton Burning Process Revisted within a Covariant Model Based on the Bethe-Salpeter Formalism

Kaptari, L.; Kämpfer, B.; Grosse, E.

A covariant model based on the Bethe-Salpeter formalism is proposed for investigating the near-threshold deuteron disintegration via electromagnetic and weak interactions. The solar proton burning process $pp\to De^+\nu_e$ and
its astrophysical low-energy cross section factor $S_{pp}$ areconsidered within this formalism as well.
Results of numerical calculations of the energy dependence of relevant cross sections and of $S_{pp}$ are presented.
Our results confirm previous canonical values. The energy dependence of the $S_{pp}$ factor is rather close to phenomenological extrapolations commonly adopted in computations of solar nuclear reaction rates.

Keywords: solar pp burning process

  • J.Phys.G26:1423-1432,2000 nucl-th/0001026

Permalink: https://www.hzdr.de/publications/Publ-3172
Publ.-Id: 3172


Boundary layer control by means of electromagnetic forces

Weier, T.; Fey, U.; Gerbeth, G.; Mutschke, G.; Avilov, V.

nicht vorhanden

  • ERCOFTAC bulletin, No. 44, pp. 36-40, March 2000

Permalink: https://www.hzdr.de/publications/Publ-3171
Publ.-Id: 3171


Support of the Ukrainian supervisory authority in establishing a modern nuclear power plant monitoring

Beyer, M.; Carl, H.; Schumann, P.; Seidel, A.; Weiß, F.-P.; Zschau, J.; Nowak, K.

The type of monitoring of nuclear power plants in Ukraine practised early nineties provided the supervisory authority with only inadequate access to information about the current safety status of plants. For the Zaporozhye NPP, unit 5, a technical system to improve the operational monitoring has been designed, installed and commissioned for trial operation at the end of 1995 as a pilot project. The system complements existing operation checking and monitoring facilities by including modern means of information technology. It enables concentration on a continuous monitoring of the state of unit 5 in normal operation and in cases of anomalies or incidents so that when recognisable deviations from the regular plant operation occur, the authority can immediately inquire and if necessary impose conditions on the operator. In 1997 the Information and Crisis Centre of the Ukraine supervisory authority in Kiev has equipped with the most essential technical means necessary for quasi-simultaneous transfer of data and voice and for monitoring purposes and connected the Centre to the Zaporozhye system. A similar monitoring system for both VVER-440 units of the Rovno NPP by analogy with the pilot project was specified, put into operation and connected to the ICC in 1998.

Keywords: NPP; monitoring; Ukrainian supervisory authority

  • Kerntechnik Vol. 65; No.1; Februar 2000; Seiten 23 - 27

Permalink: https://www.hzdr.de/publications/Publ-3170
Publ.-Id: 3170


Crystal-GRID: Investigation on interatomic solid state potentials

Hauschild, T.; Jentschel, M.; Heinig, K.-H.; Möller, W.

  • Lecture (Conference)
    HERCULES (Higher European Research Course for Users of Large Experimental Systems), Grenoble, France, March, 1999

Permalink: https://www.hzdr.de/publications/Publ-3167
Publ.-Id: 3167


K- meson production in the proton-proton reaction at 3.67 GeV/c

Balestra, F.; Bedfer, Y.; Bertini, R.; Bland, L. C.; Brenschede, A.; Brochard, F.; Bussa, M. P.; Tchalyshev, V.; Seonho, C.; Debowski, M.; Dzemidzic, M.; Faivre, J. C.; Falomkin, I. V.; Fava, L.; Ferrero, A.; Foryciarz, J.; Fröhlich, I.; Frolov, S.; Garfagnini, R.; Gill, D.; Grasso, A.; Grosse, E.; Heinz, S.; Ivanov, V. V.; Jacobs, W. W.; Kühn, W.; Maggiora, A.; Maggiora, M.; Manara, A.; Panzieri, D.; Pfaff, H. W.; Piragino, G.; Pontecorvo, G. B.; Popov, A.; Ritman, J.; Salabura, P.; Tosello, F.; Vigdor, S. E.; Zosi, G.

  • Physics Letters B 468 (1999) 7-12

Permalink: https://www.hzdr.de/publications/Publ-3166
Publ.-Id: 3166


Measurements and CFX-simulations of a bubbly flow in a vertical pipe

Krepper, E.; Prasser, H.-M.

In the Forschungszentrum Rossendorf a measurements techniques test loop was constructed. Air water flow in a vertical tube was investigated using different two phase flow measuring techniques. The paper describes the used measuring techniques and some performed experiments. The code CFX-4.2 with its implemented two phase models was used, to simulate bubbly flow and to compare calculated void profiles with the measured results.
The two phase models of the code version CFX-4.2 are able, to describe void profiles with a near wall void maximum, which will be found for bubbly flow showing a monodisperse bubble size distribution. To model flow regimes showing a bubble size distribution and the occurrence of bubble coalescence and fraction, model extensions would be necessary. The consideration of larger bubbles, which may be deformed, requires the development of improved bubble force models.

Keywords: Two phase flow; Measurements; Computational fluid dynamics

  • Lecture (Conference)
    AMIF-ESF Workshop:"Computing methods for two-phase flow", Aussois, January 12-14, 2000, Conference-CD
  • Contribution to proceedings
    AMIF-ESF Workshop:"Computing methods for two-phase flow", Aussois, January 12-14, 2000, Conference-CD

Permalink: https://www.hzdr.de/publications/Publ-3165
Publ.-Id: 3165


Einfluss von Modifikationen des monodentaten Liganden in neutralen Technetium(3+1)-Gemischtligandkomplexen auf Lipophilie und Aufnahme im Rattenhirn.

Syhre, R.; Berger, R.; Friebe, M.; Pietzsch, H.-J.; Scheunemann, M.; Spies, H.; Johannsen, B.

Bei der Entwicklung von 99mTc-Radiopharmaka für Hirnfunktionsuntersuchungen stellt der Transport durch die Blut-Hirn-Schranke einen wesentlichen Faktor dar. Das gilt insbesondere für die Klasse von "3+1"-Gemischtligandkomplexen, die gegenwärtig im Mittelpunkt der Rezeptorligandforschung mit Technetium steht. Zum Verständnis der Strukturabhängigkeit des Transports wird anhand einer systematisch variierter Verbindungsreihe untersucht, wie sich Modifizierung des monodentaten Thiolliganden in neutralen, hirngängigen 99m/99Tc-(3+1) Gemischtligandkomplexen der angegebenen Struktur auf Lipophilie und Höhe der Aufnahme im Rattenhirn auswirken.
Alle Komplexe enthalten protonisierbare Aminogruppen, die entsprechend ihrem pKa-Wert, bei pH 7,4 in unterschiedlichem Maße geladen sind. Aus diesem Grunde wurde hier der pKa-Wert der Komplexe als ein relevanter Parameter für die Hirnaufnahme bewertet. Er wurde durch RP-HPLC bei unterschiedlichem pH ermittelt. Der Verteilungskoeffizient bei pH 7,4 (logD), wurde als Ausdruck der Lipophilie in die Betrachtungen einbezogen. Die Initiale Hirnaufnahme wurde bei der Ratte 2 min nach Tracerinjektion geprüft. (i.v.; männl. Wistar-Ratten; 5-6 Wochen alt).
Die pKa-Werte der Komplexe A und C lagen bei 10,1 bis 9,6. Diese nahezu vollständige Ionisation, bei relativ niedriger Lipophilie (logD 0,3 - 0,7), spiegelte sich in einer niedrigen Hirnaufnahme von 0,2 - 0,5 % ID wieder. Die Einführung eines Ether-Sauerstoffes in die Komplexe (D) erhöhte deren Lipophilie beträchtlich (logD 1,40-1,60)und brachte pKa-Werte von 9,5 bis 8,9. Diese Änderungen ließen die Hirnaufnahme signifikant auf Dosiswerte um 1% ansteigen. In ähnlicher Weise verbesserte die Einführung einer Morpholingruppe (B und E) die Lipophilieparameter der Komplexe (pKa 7,9/7,2, logD 1,2/2,6). Auch hier folgte eine gute initiale Hirnuptake von mehr als 1% ID. Ein zweites Sauerstoffatom im Komplex (F) beeinflusste dessen Lipophilieeigenschaften (pKa 8,3, LogD 2,3) ebenfalls drastisch. Mit diesem Tracer konnte eine sehr gute Aufnahme von 2,1% ID im Hirn registriert werden. Diese Ergebnisse zeigen, dass speziell die Einführung von Sauerstoffatom(en) in die monodentaten Thiol-Liganden der betrachteten Tc-(3+1) Gemischligandkomplexe zu günstigeren Lipophilieeigenschaften führt, die sich positiv auf deren Hirnaufnahme auswirken.

  • Lecture (Conference)
    35. Intern. Jahrestagung der Deutschen Gesellschaft für Nuklearmedizin e.V., Kassel 16.4.-19.4.1997
  • Abstract in refereed journal
    Nuklearmedizin 36 (1997) A35.

Permalink: https://www.hzdr.de/publications/Publ-3164
Publ.-Id: 3164


Synthese und Rezeptorbindungseigenschaften von Derivaten des 6-Methyl-8-a-Aminoergolins

Spies, H.; Noll, B.; Noll, S.; Brust, P.; Syhre, R.; Johannsen, B.

Im Rahmen unserer Arbeiten zu Technetium- und Rheniumkomplexen mit Affinität zu Rezeptoren von Neurotransmittern wird die Eignung des Ergolinsystems für das Design Dopamin D2-rezeptorbindender Technetiumtracer untersucht. Ausgehend von 6-Methyl-8alpha-aminoergolin wurden erstmalig Re- und Tc-Komplexe synthetisiert, die sich an Ergotalkalioden als Leitverbindung orientieren. Nach Einführung des als Haftatom benötigten Schwefels durch Mercapotoacetylierung der 8alpha-Aminogruppe bindet das Ergolin als monodentater Ligand an Re(V) bzw. Tc(V), die restlichen Metallvalenzen werden durch tridentate Komplexbildner unter Bildung neutraler Gemischtligandkomplexe abgesättigt. Die Rheniumverbindung wurde als kristalline Verbindung isoliert, Technetiumspecies wurden als radiochemisch reine Lösungen hergestellt.

Alle synthetisierten Verbindungen haben hohe Affinität zu Dopamin D2-Rezeptoren mit Ki-Werten zwischen 0.38 und 6.9 [Mn] für die organischen Komplexvorstufen bzw. 19.5. [Mn] für den Rheniumkomplex. Bioverteilungsuntersuchungen (Wistarratten) der technetiumkomplexe zeigen geringen Hirnuptake (0.19% Dosis/Organ 5 min p.i.) mit konstanter Speicherung in Putamen und Hippokampus über 10 bis 120 min. Die vorläufigen Ergebnisse zeigen, dass die Verbindungsklasse eine Basis für weitere potentiell Dopamin D2-bindende Radiotracer darstellt.

  • Lecture (Conference)
    35. Intern. Jahrestagung der DGN, Kassel, 16.-19.4.1997
  • Abstract in refereed journal
    Nuklearmedizin 36 (1997) A33.

Permalink: https://www.hzdr.de/publications/Publ-3163
Publ.-Id: 3163


True equilibrium bolus estimation (TREMBLE) confirms rapid transient equilibrium

Solling, T.; Brust, P.; Cunningham, V.; Wong, D. F.; Gjedde, A.

  • Poster
    First International Symposium on Functional Receptor Mapping of the living Brain, Aarhus, 16.-18.5.1997
  • Abstract in refereed journal
    NeuroImage 5 (1997) A29.

Permalink: https://www.hzdr.de/publications/Publ-3162
Publ.-Id: 3162


Comparative stability versus cysteine of mixed ligand 99mTc complexes containing monothiols of differing nucleophilicity.

Nock, B.; Tsoukalas, C.; Maina, T.; Pirmettis, I.; Papadopoulos, M.; Spies, H.; Johannsen, B.; Chiotellis, E.

Our work over the past few years has been focused on the design and evaluation of novel chelating systems suitable for oxorhenium and/or oxotechnetium that may lead to useful radioagents. Several 99mTc mixed ligand complexes carrying the SNS/S or the SNN/S donor atom set have shown promising biological properties for future application. The in vivo stability and thereby biological properties of these complexes is greatly dependent on the electronic and lipophilic character of the monothiol.
We report here on the comparative resistance to cysteine substitution of two parallel series of 99mTcO{[Et2NCH2CH2N(CH2CH2S)2](p-RPhS)} and 99mTcO-[(Et2NCH2CH2NCH2CH2S) (p-RPhS)] complexes wherein the phenyl monothiolate coligand is substituted in the p-position by R: -NH2 (electron donating group), -H and NO2 (electron withdrawing group). The electronic influence on cysteine substitution rate can thus be investigated.
All above complexes are prepared at tracer level using glucoheptonate as transfer ligand and are purified by organic extraction and HPLC. Their structure has been previously resolved by comparison with authentic samples. The 99mTc complexes are stable in solution in the absence of thiol for long periods of time. Competition experiments with cysteine are performed in aqueous medium at pH 7.4 and using two different cysteine concentrations, 10 mM and 1 mM, by incubation at 37°C. Aliquots of the incubate withdrawn at 0, 15, 30, 60, 120 min and 24 h time intervals are subjected to HPLC analysis. A RP C18 column is eluted by TEAP buffer pH 7.4/EtOH gradient system, whereby all radioactive ingredients are well separated.
All complexes are attacked by cysteine under the above conditions forming mixtures of intermediates, that with time lead to total loss of the original 99mTc compounds. Relative resistance to cysteine substitution is directly proportional to monothiol nucleophilicity in both series of complexes: -NH2 > -H> -NO2. Since the free thiol content - mainly cysteine and its derivatives - varries in vivo, mixed ligand systems as the above can be used for directing and trapping 99mTc in tissues of choice by finely monitoring stability via the monothiol.

  • Poster
    Congress of the European Association of Nuclear Medicine, Glasgow, Scottland, 23.-27.8.1997
  • Abstract in refereed journal
    Eur. J. Nucl. Med. 24 (1997) 990

Permalink: https://www.hzdr.de/publications/Publ-3161
Publ.-Id: 3161


Identification of cancer cells by a combination of FTIR spectroscopy and PET

Steiner, G.; Richter, T.; Salzer, R.; Bergmann, R.; Rodig, H.; Johannsen, B.

A combination of FTIR spectroscopy and positron emission tomography (PET) is shown to provide new information on tissue. Here we give a first demonstration on the potential of this combination in discriminating tumor tissue from healthy tissue. Examples are taken of cancer grown in muscle tissue in mice. Immediately before thin sections of the cancer tissue were prepared, a radiotracer was injected in the living mouse. Subsequently a native section was immobilized on a CaF2 window and an autoradiographic image was recorded from that immobilized section. FTIR maps of the thin sections were obtained by using an infrared microscope equipped with computerized XY stage and MCT detector. Principal component analysis was chosen for chemometric evaluation of the spectra. Evaluated data were reassembled into two dimensional maps and compared with the corresponding PET image.

Keywords: FTIR spectroscopy; FTIR mapping; cancer; tumor; autoradiography; radiotracer; positron emission tomography; principal component analysis

  • Lecture (Conference)
    SPIE, Photonics West 2000, "Spectral Imaging: Instrumentation, Applications and Analysis" (3920) San Jose, CA, USA, 22.1.2000 - 28.1.2000
  • Contribution to external collection
    SPIE, Photonics West 2000, "Spectral Imaging: Instrumentation, Applications and Analysis" (3920) San Jose, CA, USA, 22.1.2000 - 28.1.2000

Permalink: https://www.hzdr.de/publications/Publ-3160
Publ.-Id: 3160


Probing the time scale of asymmetric fission

Kamanin, D. V.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-282 Dezember 1999
    ISSN: 1437-322X

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-3159
Publ.-Id: 3159


Bericht der Herbsttagung der Studiengruppe für Elektronische Instrumentierung vom 27. bis 29. September 1999 im Forschungszentrum Rossendorf/Dresden

Gabriel, F.

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-280 November 1999
    ISSN: 1437-322X

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-3158
Publ.-Id: 3158


Studies of in vivo labelling of nucleic acids with 99mTc complexes. First results: uptake in cultured cells.

Kampf, G.; Noll, B.; Noll, S.; Spies, H.; Franke, W.-G.; Johannsen, B.

99mTc labelled nucleobases are expected to be precursors for in vivo radioactive labelling of DNA. This offers the possibility for visualization of tumours developing in surroundings of non-dividing tissue as e.g. brain.
The aim of the study was achieve uptake of 99mTc complexes of derivatized nucleic acid precursors, especially mercaptoamide functionalized uracil derivatives, into proliferating cells.
The 99mTc complexes were prepared by ligand exchange on 99mTc(V) gluconate both as mixed ligand complexes according to the "3+1 principle" and as complexes formed by (MAG)n chelators coupled to nucleobases.
Uptake of 7 selected compounds into the crude cytosolic and nuclear fractions of cultured V79 cells was checked. Pulse labelling for 4 hrs showed cellular uptake of some compounds. Best results were about 20% cellular uptake, and thereof up to 40% in the nuclear fraction. The corresponding results with 3HTdR controls were 20% and 75% respectively.
Postincubation experiments showed an increase of the percent 99mTc radioactivity in the nuclear fraction by a factor of 2. This means integration of the complex in the nucleus from the pool present in the cytosol after the initial incubation. No radioactivity was released into the postincubation medium.
The results are encouraging, making evident that complex compounds of this kind can be taken up into the cell nucleus.

  • Abstract in refereed journal
    Eur. J. Nucl. Med. 24 (1997) 991
  • Poster
    Congress of the European Association of Nuclear Medicine, Glasgow, Scottland, 23.-27.8.1997

Permalink: https://www.hzdr.de/publications/Publ-3157
Publ.-Id: 3157


A high-energy resolution observed from a YAP: Ce scintillator.

Kapusta, M.; Balcerzyk, M.; Moszynski, M.; Pawelke, J.

An energy resolution of 4.38+-0.11% was obtained for 662 keV gamma-rays with a 3x3x20 mm3 YAP:Ce crystal with its long face coupled to an XP2020Q photomultiplier. The measured number of photoelectrons of 5290+-80 phe/MeV implies a photoelectron statistical contribution of 4.18+-0.04% and hence a YAP intrinsic energy resolution of 1.3+-0.5%, the lowest value ever observed for scintillators. The relative light output of the YAP crystal measured for energies between 14.4 keV and 1.275 MeV was constant withing +-2%. These observations are consistent with the assumption that there is a direct correlation between energy resolution of scintillators and nonproportionality of their light output versus energy.

  • Nuclear Instruments and Methods in Physics Research A 421 (1999) 610-613

Permalink: https://www.hzdr.de/publications/Publ-3156
Publ.-Id: 3156


Computer simulation of ion-beam-induced processes in solids: An overview of the activities at the FZ Rossendorf

Posselt, M.

  • Lecture (others)
    Environmental Molecular Science Laboratory at Pacific Northwest National Laboratory, Richland, WA, USA, May 7,1999

Permalink: https://www.hzdr.de/publications/Publ-3155
Publ.-Id: 3155


Atomistische Simulation der Ionenimplantation und ihre Anwendung in der Si-Technologie

Posselt, M.

  • Lecture (Conference)
    Institut für Physik der Universität Augsburg, January 28,1999

Permalink: https://www.hzdr.de/publications/Publ-3154
Publ.-Id: 3154


Synthesis of new materials by ion beams

Heinig, K.-H.

  • Lecture (Conference)
    CSNSM, ORSAY Campus, France, May 3, 1999

Permalink: https://www.hzdr.de/publications/Publ-3153
Publ.-Id: 3153


Structural studies on technetium coordination ability of cysteine-containing peptides

Johannsen, B.; Kirsch, S.; Jankowsky, R.; Noll, B.; Spies, H.; Dinkelborg, L.; Hilger, C. S.; Semmler, W.

In 99mTc labelling of specific peptides, 99mTc has to be introduced at a position of the peptide molecule which would tolerate inclusion of the label without adversely affection the receptor or other specific binding. Although for direct labelling of peptides Tc-binding sequences remote from the receptor-binding sequence have been successfully introduced, the corrdination mode of such peptides is still poorly understood. The aim of our studies was I) to clarify for simple N,S-donor building blocks, such as cysteine derivatives, how the ligands bind Tc(V) and II) to determine in solution the coordination mode of a 99Tc-labelled endothelin derivative, containing the sequence -Cys-Gly-Cys-, which is a potential agent for imaging atherosclerosis. X-ray asorption spectroscopy proved to be a valuable tool in obtaining direct structural information from the noncrystalline material and solution species. The performed studies have shed more light on the subtle interplay of the donor groups of the ligand, including the hitherto uncommon occurrence of both a deprotonated and a neutral nitrogen donor group in bis-bidentate S,N oxometal(V) complexes. EXAFS analysis of the 99Tc-labelled Cys-containing endothelin derivative revealed that coordination of the [TcO]3+ core is restricted to the sequence -Cys-Gly-Cys-. Under the labelling condition used (ligand exchange reaction with Tc(V) gluconate), the preferred coordination by the cysteinyl thiol group surprisingly prevents involvement of any donor atom other than sulphur, thus forming purely S-coordinate 1:2 complexes in form of two isomers.

  • Abstract in refereed journal
    Eur. J. Nucl. Med. 24 (1997) 990
  • Poster
    Congress of the European Association of Nuclear Medicine, Glasgow, Scottland, 23.-27.8.1997

Permalink: https://www.hzdr.de/publications/Publ-3152
Publ.-Id: 3152


Determination of the as-implanted defect structure in silicon by a combined simulation method

Posselt, M.

  • Lecture (Conference)
    MRS-ICAM99 Conference, Symposium JJ: Multiscale Materials Modeling, Beijing, China, June 13-18, 1999

Permalink: https://www.hzdr.de/publications/Publ-3151
Publ.-Id: 3151


Theoretische Beschreibung von Implantationsprozessen. Grundlagen, Methoden, Anwendungen

Posselt, M.

  • Invited lecture (Conferences)
    Sommerschule "Nukleare Sonden und Ionen", Bad Blankenburg, Germany, Sept. 21-25, 1998 (invited lecture)

Permalink: https://www.hzdr.de/publications/Publ-3148
Publ.-Id: 3148


The dopaminergic system is altered under neonatal asphyxia-studies with[18F]FDOPA.

Brust, P.; Bergmann, R.; Bauer, R.; Walter, B.; Vorwieger, G.; Füchtner, F.; Steinbach, J.; Will, E.; Linemann, H.; Johannsen, B.

There is evidence that the dopaminergic system is sensitive to asphyxia. However, the respective enzyme activities have not been measured in the living neonatal brain yet. In this study, FDOPA was used to estimate the activity of the aromatic amino acid decarboxylase (AADC) and the relative changes of monoamine oxidase (MAO) and catechol-o-methyl-transferase (COMT) in the neonatal pig brain.
Two PET studies were performed under control conditions and under 2-hour asphyxia in each of 6 piglets and combined with measurements of cerebral blood flow (CBF) and volume (CBV). Plasma metabolites of FDOPA were also determined by HPLC.
As expected asphyxia elicited a 3-fold elevation of the CBF and increased the CBV by 40%. The blood-brain transfer of FDOPA, K1, and the clearance rate constant from brain, k2, were unchanged. However, the rate of [F-18]fluoro-dopamine synthesis, k3, was increased in striatum from 0.038±0.016 min-1 to 0.056±0.028 min-1. Also, the rate of conversion of FDOPA to 3-O-methyl-FDOPA (OMFD) by COMT in plasma decreased during asphyxia from 0.0080±0.0015 min-1 to 0.0046±0.0010 min-1. Measurement of metabolites in tissue indicates that similar changes occurred also in the brain. Furthermore, the amount of FDOPAC as product of brain MAO activity was significantly decreased under asphyxia.
Increase of the extracellular level of dopamine is expected to be involved in severe disturbances of neuronal metabolism during asphyxia, e.g. by generating free radicals and quinones. In this study, evidence for an increase of the AADC activity and a decrease of MAO activity during asphyxia was obtained which may contribute to the increase of extracellular dopamine.

  • Abstract in refereed journal
    Eur. J. Nucl. Med. 24 (1997) 1043.
  • Poster
    Congress of the European Association of Nuclear Medicine, Glasgow, Scottland, 23.-27.8.1997

Permalink: https://www.hzdr.de/publications/Publ-3147
Publ.-Id: 3147


Computer simulation of defect evolution during high-energy ion implantation and subsequent annealing

Heinig, K.-H.; Jäger, H.-U.

  • Lecture (Conference)
    IUMRS-ICAM99 Conference, Symposium M: Si-based Materials and Devices, Beijing, China, June 13- 18, 1999

Permalink: https://www.hzdr.de/publications/Publ-3146
Publ.-Id: 3146


Gold Complexes with Potentially Tri- and Tetradentate Phosphinothiolate Ligands.

Ortner, K.; Hilditch, L.; Dilworth, J.; Zheng, Y.; Abram, U.


Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- = 2-(N,N-dimethylamino-methyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3-SH-2-R-3)2 (H2L1a: R = SiMe3, H2L1b: H) and P(C6H3-SH-2)3 (H3L2) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different oxidation states, +I and +III, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl4]-. A dinuclear complex having two Au(III) centres can be isolated from the reaction of [Au(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained which contains a three-coordinate gold atom.
Comparatively short gold-gold distances have been found in the dinuclear complexes (2.978(2) A and 3.434(1) Å). They are indicative of weak gold-gold interactions, which is unusual for gold(III).




Keywords: Gold complexes; Phosphinothiolate complexes; Crystal structures; Gold-gold interactions

  • Inorganische Chemie

Permalink: https://www.hzdr.de/publications/Publ-3145
Publ.-Id: 3145


Multiscale modeling of nucleation and growth of nanocrystals

Heinig, K.-H.; Strobel, M.

  • Lecture (Conference)
    IUMRS-ICAM99 Conference, Symposium JJ: Multiscale Materials Modeling, Beijing, China, June 13- 18, 1999

Permalink: https://www.hzdr.de/publications/Publ-3144
Publ.-Id: 3144


Nanocrystal formation by ion beam synthesis: in-beam TEM observation and modeling

Heinig, K.-H.; Ruault, M. O.; Strobel, M.; Bernas, H.

  • Lecture (Conference)
    E-MRS Spring Meeting, Symposium 1 - Microcrystalline and Nanocrystalline Semiconductors, Strasbourg, France, June 1-4, 1999

Permalink: https://www.hzdr.de/publications/Publ-3143
Publ.-Id: 3143


Formation of d-layers of Ge nanocrystals in SiO2

Heinig, K.-H.; Schmidt, B.; Markwitz, M.; Strobel, M.; von Borany, J.; Klimenkov, M.

  • Lecture (Conference)
    E-MRS Spring Meeting, Symposium 1 - Microcrystalline and Nanocrystalline Semiconductors, Strasbourg, France, June 1-4, 1999

Permalink: https://www.hzdr.de/publications/Publ-3142
Publ.-Id: 3142


Modeling of impurity gettering in silicon by ion implantation induced defects

Heinig, K.-H.; Jäger, H.-U.

  • Lecture (Conference)
    E-MRS Spring Meeting, Symposium F - Process Induced Defects in Semiconductors, Strasbourg, France, June 1-4, 1999

Permalink: https://www.hzdr.de/publications/Publ-3141
Publ.-Id: 3141


Simultaneous measurement of cerebral blood flow and [18F]FDOPA metabolism in newborn piglets

Brust, P.; Bauer, R.; Walter, B.; Bergmann, R.; Vorwieger, G.; Steinbach, J.; Füchtner, F.; Will, E.; Linemann, H.; Johannsen, B.

  • Abstract in refereed journal
    NeuroImage 5 (1997) A25.
  • Lecture (Conference)
    First International Symposium on Functional Receptor Mapping of the living Brain, Aarhus, Denmark, 16.-18.5.1997

Permalink: https://www.hzdr.de/publications/Publ-3139
Publ.-Id: 3139


Crystal-GRID: Investigation of interatomic solid state potentials

Hauschild, T.; Jentschel, M.; Heinig, K.-H.; Börner, H. G.; Möller, W.

  • Lecture (Conference)
    HERCULES (Higher European Research Course for Users of Large Experimental Systems), Grenoble, France, March, 1999

Permalink: https://www.hzdr.de/publications/Publ-3138
Publ.-Id: 3138


Effect of asphyxia on dopa decarboxylase activity in the brain of neonatal pigs.

Brust, P.; Bauer, R.; Walter, B.; Bergmann, R.; Vorwieger, G.; Steinbach, J.; Füchtner, F.; Will, E.; Linemann, H.; Obert, M.; Zwiener, U.; Johannsen, B.

  • Abstract in refereed journal
    J. Cereb. Blood Flow Metab. 17 (1997) S161
  • Lecture (Conference)
    BRAIN 97, Baltimore, USA, 15.-19.6.1997

Permalink: https://www.hzdr.de/publications/Publ-3137
Publ.-Id: 3137


Classical MD simulations of atomic displacernents in 4H-, 6H-, and 3C-SIC

Belko, V.; Chagarov, E.; Posselt, M.

  • Lecture (Conference)
    E-MRS 1999 Spring Meeting, Symposium L: Ab-Initio Approaches to Microelectronics Materials and Process Modelling, Strasbourg, France, June 1-4,1999

Permalink: https://www.hzdr.de/publications/Publ-3133
Publ.-Id: 3133


Phase Formation in Aluminium Implanted Titanium and the Correlated Modification of Mechanical and Corrosive Properties

Tsyganov, I.; Wieser, E.; Matz, W.; Mücklich, A.; Reuther, H.; Pham, M. T.; Richter, E.

Surface modification of titanium is of interest considering the necessary improvement of mechanical properties of this material for applications as e.g. medical implants. This work is devoted to the formation of a layer with a high content of the titanium aluminides Ti3Al and TiAl below the surface by high dose aluminium implantation. If the maximum aluminium concentration exceeds 20 at.% precipitation of Ti3Al is detected by XRD already in the as-implanted state. For maximum aluminium concentrations between 50 and 55 at.% the phase TiAl is found beside Ti3Al after annealing at 700oC. For a double implantation resulting in an aluminium concentration of about 60 at.% in the depth range between 100 and 200 nm a disordered fcc TiAl phase is observed after implantation as precursor for the ordered tetragonal TiAl formed by subsequent annealing at 600oC. The influence of a pre-implantation of 3x1017 V/cm2 on the phase formation is also reported.
The depth dependent maximum hardness in the near surface range increases with increasing Al dose up to a factor 4. Significantly enhanced wear resistance is observed for Al doses >1018 cm-2 after annealing. High dose implantation of Al into Ti results in an enhanced corrosion in 5 M HCl. However, subsequent annealing reduces the corrosion current compared to unimplanted Ti.

Keywords: titanium; ion implantation; aluminium; intermetallic phases; wear; corrosion

  • Thin Solid Films 376 (2000) 188

Permalink: https://www.hzdr.de/publications/Publ-3132
Publ.-Id: 3132


Strukturierung von epitaktischen CoSi2/Si-Heterostrukturen durch lokale Oxidation

Antons, A.; Klinkhammer, F.; Kappius, L.; Heinig, K.-H.; Trinkaus, H.; Mantl, S.

  • Lecture (Conference)
    DPG-Frühjahrstagung des AK Festkörperphysik, Münster, March 22-26,1999

Permalink: https://www.hzdr.de/publications/Publ-3131
Publ.-Id: 3131


Nanostructured arrays formed by finely focused ion beams

Zuhr, R. A.; Budai, J. D.; Datskos, P. G.; Meldrum, A.; Thomas, K. A.; Warmack, R. J.; White, C. W.; Feldman, L. C.; Strobel, M.; Heinig, K.-H.

  • Contribution to external collection
    Mat. Res. Soc. Symp. Proc. 536 (1999) 251

Permalink: https://www.hzdr.de/publications/Publ-3130
Publ.-Id: 3130


Defects remaining in MeV-ion-implanted and armealed Si away from the peak of the nuclear energy deposition profile

Kögler, R.; Yankov, R. A.; Posselt, M.; Danilin, A. B.; Skorupa, W.

  • Nucl. Instr. Meth. B147 (1999) 96

Permalink: https://www.hzdr.de/publications/Publ-3128
Publ.-Id: 3128


Simulations for impurity gettering in silicon by ion implantation induced defects

Heinig, K.-H.; Jäger, H.-U.

  • Lecture (Conference)
    Proc. First ENDEASD (European Network on Defect Engineering of Advanced Semiconductor Devices) Workshop, C. Claeys, (ed.), p. 294, Santorini, Greece, April 1999
  • Contribution to proceedings
    Proc. First ENDEASD (European Network on Defect Engineering of Advanced Semiconductor Devices) Workshop, C. Claeys, (ed.), p. 294, Santorini, Greece, April 1999

Permalink: https://www.hzdr.de/publications/Publ-3127
Publ.-Id: 3127


Monte Carlo ion-implantation simulation for deep ULSI transistors

Feudel, T.; Strecker, N.; Krause, U.; Schmidt, B.; Posselt, M.

  • Lecture (Conference)
    Proc. 1999 Semiconductor TCAD Workshop, vol. 2, p. 7. 1, Hsinchu, Taiwan, May 1999
  • Lecture (Conference)
    1999 Semiconductor TCAD Workshop, Hsinchu, Taiwan, May 4-6,1999
  • Contribution to proceedings
    Proc. 1999 Semiconductor TCAD Workshop, vol. 2, p. 7. 1, Hsinchu, Taiwan, May 1999

Permalink: https://www.hzdr.de/publications/Publ-3126
Publ.-Id: 3126


Modeling of Ge nanocluster evolution in ion implanted Si02 layers

Borodin, V. A.; Heinig, K.-H.; Schmidt, B.

  • Nuclear Instr. Meth. B 147 (1999) 286

Permalink: https://www.hzdr.de/publications/Publ-3125
Publ.-Id: 3125


Performance Ratio im Detail: PV-Generatorleistung und Anlagenertrag

Rindelhardt, U.; Teichmann, G.

Das Performance Ratio (PR) als wichtigste Kenngröße einer netzgekoppelten Photovoltaikanlage wird analysiert. Durch Unterscheidung zwischen der nominalen Generatorleistung und der Nennleistung des Generators können einerseits gemessenen Werte des PR interpretiert und andererseits aus gemessenen Werten des PR auf relativ einfache Weise die Generatornennleistung ermittelt werden. Das Verfahren wird an verschiedenen Anlagen verifiziert.
Die qualifizierte Ermittlung des PR einer Anlage ist wichtige Voraussetzung für eine belastbaren Ertragsvorhersage einer PV-Anlage.

Keywords: Photovoltaik; Performance Ratio

  • Poster
    Tagungsband 15. Symposium Photovoltaische Solarenergie, 15.-17. März 2000, Staffelstein, S. 331
  • Contribution to proceedings
    Tagungsband 15. Symposium Photovoltaische Solarenergie, 15.-17. März 2000, Staffelstein, S. 331

Permalink: https://www.hzdr.de/publications/Publ-3123
Publ.-Id: 3123


Low temperature hydroxyapatite coating of titanium via sodium ion implantation

Pham, M. T.; Matz, W.; Reuther, H.; Richter, E.; Steiner, G.

Na ions were implanted into pure Ti surfaces. New surface phases were shown to be incorporated into the surface: sodium titanates Na2TiO3 (in the as-implanted state) and Na2Ti6O13 (after 20 min heating at 700 °C in air). A variable level of rugged surface in porosity and roughness was observed depending on the applied ion dose and energy. Upon exposing to simulated body fluid, such ion-implanted surfaces were revealed to enhancedly elicit hydroxyapatite nucleation and growth.

Keywords: biocompatibility; titanium; hydroxyapatite; surface coating; ion implantation

  • Thin Solid Films 379 (2000) 50-56

Permalink: https://www.hzdr.de/publications/Publ-3122
Publ.-Id: 3122


Basic investigations of an integrated modulator for plasma immersion ion implantation

Günzel, R.; Hornauer, U.; Rogozin, A.; Astrelin, V.

The replacement of the external high voltage modulator by an integrated plasma based modulator recently presented, would appreciably reduce the costs of plasma immersion ion implantation equipment. Hence an inherent restriction of the integrated modulator is the limited maximum current supplied by the integrated modulator during the application of the high voltage pulse to the sample. The aim of the present publication is to investigate possibilities to overcome this limitations. Detailed investigations are presented on the response of a plasma if electrons are extracted by a large electrode with special emphasis on the processes near the wall and near the control grid of the modulator.
Switching off the negative bias voltage of the grid, controlling the electron flow to the anode, results in an increase of the plasma floating potential from -8V to about 60V, as revealed by probe measurements. All electrons leaving the plasma are collected by the anode. Further during the off - time of the grid voltage a 2 to 3 fold increase of the plasma density was observed.

Keywords: PIII; PSII; high voltage modulation

  • Surf. Coat. Technol. 136 (2001) 47

Permalink: https://www.hzdr.de/publications/Publ-3121
Publ.-Id: 3121


Measurements and CFX-simulations of a bubbly flow in a vertical pipe

Krepper, E.; Prasser, H.-M.

In the Forschungszentrum Rossendorf a measurements techniques test loop was constructed. Air water flow in a vertical tube was investigated using different two phase flow measuring techniques. Air was injected into an upward water flow at normally conditions applying different injection modes. Different tests with different relations of air and water superficial velocity were performed. For each test stationary conditions were settled. The paper describes the measuring techniques used and some experiments performed. Applying a wire mesh sensor, developed in FZR, the cross section of the void fraction could be determined. The time resolution achieved by the signal processing unit is 1024 frames per second. The spatial resolution equals 3 mm. At the investigated flow velocities, the bubble diameter distributions could be determined. Using the code CFX-4.2, void profiles over the tube cross section were calculated. The development of the void profiles is mainly influenced by bubble forces, which act perpendicular to the flow direction. Therefore the comparison of the calculated with the measured results for bubble flow regimes is a good validity test for the implemented two phase flow models. The two phase models of the code version CFX-4.2 are able to describe void profiles with a near wall void maximum, which will be found for bubbly flow showing a monodisperse bubble size distribution. To model flow regimes showing a bubble size distribution and the occurrence of bubble coalescence and diffraction, model extensions would be necessary. The consideration of larger bubbles, which may be deformed, requires the development of improved bubble force models.

  • Lecture (Conference)
    3rd Int. Conf. on Advances in Fluid Mechanics, Montreal May 2000; in: M. Rahman, C.A. Brebbia (Ed.): Advances in Fluid Mechanics III, pp. 23-31, WITPress Southampton, Boston 2000, ISBN 1-85312-813-9
  • Contribution to external collection
    3rd Int. Conf. on Advances in Fluid Mechanics, Montreal May 2000; in: M. Rahman, C.A. Brebbia (Ed.): Advances in Fluid Mechanics III, pp. 23-31, WITPress Southampton, Boston 2000, ISBN 1-85312-813-9

Permalink: https://www.hzdr.de/publications/Publ-3120
Publ.-Id: 3120


Ion beam synthesis of semiconductor nanoclusters for opto- and microelectronics applications

von Borany, J.; Heinig, K.-H.; Skorupa, W.

  • Book (Authorship)
    in: Advances in Solid State Physics 39, pp. 171-181, ed. by B. Kramer, Vieweg-Verlag Braunschweig/Wiesbaden 1999

Permalink: https://www.hzdr.de/publications/Publ-3119
Publ.-Id: 3119


Technetium and Rhenium in Nuclear Medicine

Pietzsch, H.-J.; Johannsen, B.

The appreciation of short-lived radionuclides in nuclear medicine has led to the development of radionuclide generators that serve as a convenient source of these radionuclides to prepare a wide range of radiopharmaceuticals. Of all the potentially useful generator systems, the 99mTc generator has found the most widespread use. Although originally chosen because of its excellent disintegration characteristics and its ready availability, 99mTc would not be so widely used today were it not for its ability to exhibit a versatile coordination chemistry.
During the first phase of research into the development of 99mTc based imaging agents in the 1970s the agents were relatively simple in nature (pertechnetate, colloids, particles, albumin, and complexes with DTPA, phosphonates). Then new complexes have been developed which provide images of flow and metabolism, e.g. kidney and liver functions as well as regional heart and brain perfusion. Antibodies, antibody fragments and numerous peptides have been successfully labelled with 99mTc. Progress in technetium chemistry has led to an assortment of building blocks in the form of various cores and valuable combinations of donor groups in a number of chelating ligands. Research is still going on to extend and improve these tools. Using new concepts and methods, current research is being directed at an area of technetium chemistry well beyond perfusion tracers to open a window on biochemistry. The recent advances in the design of new technetium 99mTc imaging agents illustrate the continued expansion of the use.

Rhenium and technetium belong to the same group of the periodic table and have similar chemical properties. Radioisotopes of rhenium (186Re and 188Re) have been suggested as radiopharmaceuticals for therapy. Similar to the in-house use of the 99mTc generator for the preparation of a great variety of 99mTc labeled diagnostic agents, the 188Re generator can provide the therapeutically useful radionuclide for the preparation of 188Re agents for bone pain palliation, cancer therapy, radiotherapy of chronic degenerative joint diseases and brachytherapy to reduce restenosis risks after coronary dilatation.

  • Lecture (Conference)
    Congress of the South American Pharmaceutical Federation, Montevideo/Uruguay, 26.-28.4.2000

Permalink: https://www.hzdr.de/publications/Publ-3118
Publ.-Id: 3118


Workshop on Measuring techniques for steady state and transient multiphase flows 1999

Prasser, H.-M.; Schaffrath, A.

The third workshop on Measuring Techniques for Steady State and Transient Multiphase Flows took place at the Forschungszentrum Rossendorf (FZR) at the 14 Oktober 1999. This series of meetings was initiated by the Institute for Safety Research of the FZR and by the Institute of Process Technology, Process Automation and Measuring Techniques of the University of Applied Science Zittau. The workshop was supported by the Deutsche Gesellschaft für Chemisches Apparatewesen, Chemische Technik und Biotechnologie (DECHEMA) and the Section Thermo and Fluiddynamics of the Kerntechnische Gesellschaft. Two main lectures and 9 technical papers dealt with wall thermography, acoustic and gamma source water level measurement, electro diffusion, optical tomography and velocity and mass flow measurements with wire mesh sensors.

Keywords: Measuring Techniques for Steady State and Transient Multiphase Flows

  • Kerntechnik 64 (1999) 5-6, p. 309-311

Permalink: https://www.hzdr.de/publications/Publ-3117
Publ.-Id: 3117


Nachrechnung der Oak Ridge Versuche (THTL) zur thermohydraulischen Instabilität

Hainoun, A.; Schaffrath, A.

Bis Mitte der 90er Jahre wurde in den USA an der Entwicklung eines Höchstflußreaktors (ANSR: Advanced Neutron Source Reactor) gearbeitet, dessen Neutronenfluß den der derzeit betriebenen Hochflußreaktoren (z.B. dem HFR in Grenoble) um mindestens eine Größenordnung übertreffen sollte. Der aus 15 kg hochangereichertem Uran bestehende Kern besaß eine Leistung von 330 MWth, ein Volumen von 67,5 l sowie eine Kernstandzeit von 17 Tagen.

Zur thermohydraulichen Auslegung der Brennelemente des ANSR wurde am Oak Ridge National Laboratory die THTL (Thermal Hydraulic Test Loop) Versuchsanlage aufgebaut. Die hierbei durchgeführten Experimente dienten dazu, die Auslegungsgrenzen gegen Einsatz von Strömungsinstabilität (THI) und Überschreitung der kritischen Heizflächenbelastung (DNB) im unterkühlten Siedebereich zu bestimmen. Die Experimente sind durch sehr hohe Wärmestromdichten (bis zu 1680 W/cm²) sowie Strömungsgeschwindigkeiten (bis zu 28 m/s) bei einem Systemdruck von 17 bar charakterisiert.

Im nachfolgenden Beitrag soll nun die Nachrechnung ausgewählter THTL-Experimente mit dem von der Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH entwickelten Thermohydraulikprogrammsystems ATHLET beschrieben. Dieses wurde hierzu um ein von Hainoun entwickeltes Modell zur Beschreibung der Dampfbildung beim unterkühlten Sieden erweitert und anhand der Nachrechnung von Experimenten zur Strömungsinstabilität und Voidverteilung im Bereich niedriger Drücke (kleiner 2 bar) und mäßiger Geschwindigkeiten (kleiner 5 m/s) validiert. Die hier vorgestellte Nachrechnung der THTL-Experimente stellt somit eine umfangreiche Ereiterung des Anwendungsbereiches dar. Zukünftig ist es somit möglich, mit ATHLET Sicherheitsanalysen für Hochflußreaktoren durchzuführen.

Keywords: Forschungsreaktoren; THTL-Experimente; Advanced Neutron Source Reactor; Oak Ridge National Laboratory; ATHLET; thermohydraulische Instabilität; kritische Heizflächenbelastung

  • Lecture (Conference)
    Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai 2000, Tagungsbericht S. 523-529
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai 2000, Tagungsbericht S. 523-529

Permalink: https://www.hzdr.de/publications/Publ-3116
Publ.-Id: 3116


Application of high-resolution gamma spectroscopy to the study of atomic collision cascades in solids

Jentschel, M.; Hauschild, T.; Börner, H. G.; Heinig, K.-H.; Fujimoto, H.

In the Crystal-GRID (Gamma Ray induced Doppler Broadening) technique one uses the fact that atomic nuclei can be excited by a
thermal neutron capture reaction. The de-excitation process takes place via the emission of gamma-quanta. The emission of the first
gamma-quantum after the neutron capture leads to a recoil of the excited nucleus. Typical recoil energies are
in the range of several hundreds of eV and therefore much higher than the displacement threshold of the atom. The recoiling atom will start to
collide with its neighbours losing successively kinetic energy until
thermal energies are reached.

During the collision process a second gamma-ray might be emitted by the atomic nucleus and, as the emitter was moving, the energy of the
gamma-quantum
will be Doppler shifted. The Doppler-shift is a very direct indicator to study the motion of the emitting particle and yields information on the
recoil
process of the atom. However, due to the isotropic orientation of the recoil direction one observes a
Doppler-broadening of the the Intensity distribution I(Eg2). The sensitivity of the technique to the study of atomic collision processes is
enhanced if single crystalline targets are used. In this case the microscopic anisotropy of the slowing down process induces a characteristic
fine structure of the Doppler-broadened line shapes. Measurements with differently aligned targets with respect to the axis of observation give
different line shapes I(Eg2) and allow therefore to accumulate information on the microscopic collision processes. A detailed description of the
experimental technique will be given together with an overview on already performed experiments. In these experiments the comparison of
experimental data to predictions deduced from Molecular Dynamics simulations has allowed to obtain new repulsive interatomic potentials.

Currently, the measurement of I(Eg2) is carried out using a double flat crystal geometry, which allows to obtain a relative energy resolution of
(Delta E)/E = 10-6. The very small solid angle of 10-11 of this geometry requires the use of massive targets. This limits significantly the variety
of compounds, which can be studied by this technique. The use of a double Dumond geometry would allow to overcome this problem. Recent
technical improvements of the GAMS5 spectrometer towards a double bent crystal geometry will be demonstrated. The current status of the
spectrometer and the expected capabilities will be presented.

Keywords: Crystal-GRID; crystal spectrometer; Dumond geometry; gamma ray spectroscopy; interatomic potential; Molecular Dynamics simulation; nuclear level lifetime

  • Lecture (Conference)
    2nd Workshop on Methods and Applications of Curved Crystal X-Ray Optics, Weimar, Germany, October 4-7, 1999

Permalink: https://www.hzdr.de/publications/Publ-3114
Publ.-Id: 3114


XPS investigations for the study of Ge clustering in SiO2

Ostwald, S.; Schmidt, B.; Heinig, K.-H.

  • Lecture (Conference)
    8th European Conf. on Appl. of Surface and Interface Analysis (ECASIA´99), Sevilla, Spain, October 4-8, 1999

Permalink: https://www.hzdr.de/publications/Publ-3113
Publ.-Id: 3113


Transverse cooling or heating of channeled ions by electron capture and loss

Assmann, W.; Huber, H.; Karamian, S. A.; Andersen, J. U.; Posselt, M.

  • Lecture (Conference)
    8th Int. Conf. on Atomic Collisions in Solids (ICACS18), Odense, Denmark, August 3-8, 1999

Permalink: https://www.hzdr.de/publications/Publ-3112
Publ.-Id: 3112


Crystal-GRID: Study of orientation-dependent slowing-down in single-crystalline ZnS

Hauschild, T.; Heinig, K.-H.; Jentschel, M.; Börner, H. G.; Möller, W.

Crystal-GRID is a direct method to study orientation-dependent slowing down of recoil atoms in mono-crystals at intermediate recoil velocities of up to 1 Angstrom/fs. The method is based on the excitation of nuclei by neutron capture and their deexcitation by successive photon emissions. A first photon emission leads to a recoil of a few 100 eV. Special deexcitation channels are considered where the recoiling nucleus is not yet at rest when the second photon is emitted. The Doppler shifted energy of this second gamma quantum is measured. When observing many deexcitations a Doppler broadened gamma line shape is obtained.

The slowing down of recoiling atoms is anisotropic due to the regular and discrete positions of the collision partners in a lattice. The use of single-crystalline targets allows to observe this anisotropy via a pronounced structure of the Doppler broadened gamma line. As the Doppler shift only depends on the projection of recoil velocities on the axis of observation, different line shapes can be obtained when performing various measurements with crystals aligned differently.

Measurements have been carried out with the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL. Doppler broadened line shapes could be obtained using ZnS single crystals in three orientations. They are compared to predictions from molecular dynamics (MD) simulations. Thereby, parameters of classical interatomic potentials describing the slowing down have been extracted.

Detailed results will be presented for ZnS, showing that the universal screened Coulomb potentials (ZBL, KrC) have to be modified in the examined energy region. Using the modified potentials, effects such as channelling and blocking have been studied by computer simulations. It will be discussed to which extent the potential corrections are important for simulations of ion beam techniques.

Keywords: Crystal-GRID; gamma ray spectroscopy; interatomic potential; Molecular Dynamics simulation; nuclear level lifetime; ZnS

  • Lecture (Conference)
    14th Int. Conf. on Ion Beam Analysis (IBA-14) and 6th European Conf. on Accelerators in Applied Research and Technology (ECAART-6),Dresden, Germany, July 26-30, 1999
  • Lecture (Conference)
    8th Int. Conf. on Atomic Collisions in Solids (ICACS18), Odense, Denmark, August 3-8, 1999

Permalink: https://www.hzdr.de/publications/Publ-3111
Publ.-Id: 3111


"Inverse" Ostwald ripening due to ion irradiation: An athermal process studied by Monte Carlo simulations

Strobel, M.; Heinig, K.-H.; Möller, W.

  • Lecture (Conference)
    Gordon Research Conference on Materials Processes Far From Equilibrium, Plymouth, NH, USA, July 11-16, 1999

Permalink: https://www.hzdr.de/publications/Publ-3110
Publ.-Id: 3110


Ion beam induced nanocrystals - an introduction to nanocrystal session

Heinig, K.-H.

  • Lecture (Conference)
    Gordon Research Conference on Materials Processes Far From Equilibrium, Plymouth, NH, USA, July 11-16, 1999

Permalink: https://www.hzdr.de/publications/Publ-3109
Publ.-Id: 3109


Transverse cooling or heating of channeled ions by electron capture and loss

Assmann, W.; Huber, H.; Karamian, S. A.; Grüner, F.; Mieskes, H. D.; Andersen, J. U.; Posselt, M.; Schmidt, B.

We have measured the angular distribution of energetic heavy ions after passage through a Si crystal for an incident beam with an isotropic angular distribution over angles much larger than the critical angle for channeling. Strong redistribution of the flux has been observed, in some cases an enhancement along channeling directions, and in other cases a reduction. The phenomenon is not predicted by channeling theory and cannot be reproduced by computer simulations. We propose a new mechanism: cooling or heating of the transverse motion of channeled ions due to repeated capture and loss of electrons. The cooling effect is analogous to Sisyphus cooling of very cold, trapped atoms in a strong laser field.

  • Phys. Rev. Lett. 83 (1999) 1759

Downloads:

Permalink: https://www.hzdr.de/publications/Publ-3107
Publ.-Id: 3107


Coolant Mixing in Pressurized Water Reactors at Constant Coolant Flow in the Primary Circuit

Grunwald, G.; Höhne, T.; Prasser, H.-M.; Weiß, F.-P.

During transients in Pressurised Water Reactors the quality of the coolant may differ from one loop to another. Both an undesired decrease of the boron acid concentration (boron dilution transient) and a decrease of the coolant temperature in case of a main steam line break lead to a positive reactivity insertion, which may cause a power excursion. In general, both temperature and boron acid concentration at the inlet nozzles of the reactor vessel can vary as independent functions of time. On the way to the core entrance the coolant from different loops is mixed in the threedimensional turbulent flow field inside the complex boundary conditions of downcomer and lower plenum. The consequences to the reactor core depend very sensitively on the degree of mixing. In the present work, a German 1300 MW PWR was investigated. For this purpose, the ROCOM test facility (Rossendorf Coolant Mixing Model) was built. The new facility disposes of four complete loops with controllable pumps in each of them. This allows to study a wide range of different mixing scenarios. The presented results on stationary mixing, i.e. mixing of a permanently disturbed coolant flow in one of the loops with running circulation in all four loops are in good agreement with the results of previous work. The maximum value of the averaged mixing scalar at the core inlet was found to be about 90 %, i.e. 90 % of the coolant arriving at the most affected fuel element origins from the disturbed loop. New information was obtained concerning the transient behaviour of the concentration field. The experiments have shown the mechanism of mixing in case of short plugs. Furthermore, strong fluctuations of the instantaneous mixing scalar were found, especially at the slopes of the averaged distribution. These fluctuations where quantified for the first time. It has to be checked whether these effects must be considered in 3D neutron kinetic models.

Keywords: coolant mixing; pressurized water reactor; boron delution transient; main steam line break; coolant mixing experiments; conductivity sensors

  • Lecture (Conference)
    Jahrestagung Kerntechnik 2000, 23.-25. Mai 2000 in Bonn, Proceedings pp. 109-114.
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2000, 23.-25. Mai 2000 in Bonn, Proceedings pp. 109-114.

Permalink: https://www.hzdr.de/publications/Publ-3106
Publ.-Id: 3106


Stability of axially symmetric flow driven by a rotating magnetic field in a cylindrical cavity

Grants, I.; Gerbeth, G.

The present paper deals with the stability analysis of a swirling-recirculating axially symmetric liquid metal flow driven by the rotating magnetic field in a cylinder of finite dimensions. The limit of linear stability with respect to axially symmetric perturbations is found for the diameter to height ratios 1 and 0.5. This oscillatory instability is shown to be of other type than the expected Taylor-Görtler vortices. Several linearly unstable steady solutions are found and the flow is shown to be unstable to finite amplitude Taylor-Görtler type vortices in sub-critaical regime. The energy of critaical finite amplitude perturbation is estimated numerically.

  • Journal of Fluid Mechanics (2001), Vol. 431, pp 407-426

Permalink: https://www.hzdr.de/publications/Publ-3105
Publ.-Id: 3105


Generation and detection of fluorescent color centers in diamond with submicron resolution

Martin, J.; Wannemacher, R.; Teichert, J.; Bischoff, L.; Köhler, B.

Flourescent color-center patterns have been written on surfaces of synthetic type-Ib diamonds with spatial resolution below 180 nm via irradiation with focused ion and electron beams and subsequent annealing. The patters are detected and spectroscopically analyzed using confocal optical microscopy. From the spatial extent of the color-center distributions, the activation energy for diffusion of vacancies in diamond is determined as (2.55+-0.15)eV. Dtailed information about the formation of color centers in diamond is obtained employing the three-dimensional spatial resolution of the confocal microscope combined with spectral resolution. In particular, the distributions of two color centers, ascribed to different charge states of the NV defect in diamond, have been spatially mapped and shown to depend strongly on the irradiation dose.

Keywords: diamond; color center; focused ion beam irradiation; electron beam irradiation; vacancy diffusion; confocal microscopy

  • Applied Physics Letters 75 (1999) 3096-3098

Permalink: https://www.hzdr.de/publications/Publ-3104
Publ.-Id: 3104


Pecularities of isotopic temperatures obtained from p + A collisions at 1 GeV

Andronenko, M.; Andronenko, L.; Neubert, W.; Seliverstov, D.

The nuclear temperatures obtained from inclusive measurements of double isotopic yield ratios of fragments produced in 1 GeV p+A collisions amount to about 4 MeV nearly independent from the target mass.

  • Eur. Phys. J. A, Vol. 8, Nr. 1, pp.9-13

Permalink: https://www.hzdr.de/publications/Publ-3103
Publ.-Id: 3103


Acoustic waterhammer simulations with consideration of fluid-structure interaction (FSI)

Repp, T.

The results (maximum pressure amplitude and tangential stresses) of acoustic waterhammer simulations with consideration of fluid-structure interaction in straight and bended pipes are shown and compared with analytical results for some ratios of wall thickness to diameter and bending radius to diameter. A adjusted formula is described for the maximum dynamic tangential stress.

Keywords: waterhammer; fluid-structure interaction; acoustic simulation; pipe; pipe bend; wave

  • Lecture (Conference)
    Sammelband Workshop Kompetenzerhalt Kerntechnik, Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai
  • Contribution to proceedings
    Sammelband Workshop Kompetenzerhalt Kerntechnik, Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai

Permalink: https://www.hzdr.de/publications/Publ-3101
Publ.-Id: 3101


Steady dynamos in finite domains: an integral equation approach

Stefani, F.; Gerbeth, G.; Rädler, K.-H.

The paper deals with the integral equation approach to steady kinematic dynamo models in finite domains based on Biot-Savart's law. The role of the electric potential at the boundary is worked out explicitly. As an example, a modified version of the simple spherical alpha-effect dynamo model proposed by Krause and Steenbeck is considered in which the alpha-coefficient is no longer constant but may vary with the radial coordinate. In particular, the results for
the original model are re-derived. Possible applications of this integral equation approach for numerical simulations of dynamos in arbitrary geometry and for inverse dynamo theory are sketched.

  • Astronomische Nachrichten 321 (2000) 65-73

Permalink: https://www.hzdr.de/publications/Publ-3100
Publ.-Id: 3100


Detection of metastable defective regions in ion-implanted Si by means of metal gettering

Kögler, R.; Posselt, M.; Yankov, R. A.; Kaschny, J. R.; Werner, P.; Danilin, A. B.; Skorupa, W.

  • Contribution to external collection
    MRS Symp. Proc. 469 (1997) 224

Permalink: https://www.hzdr.de/publications/Publ-3099
Publ.-Id: 3099


Nachweis und Analyse neutroneninduzierter Defektstrukturen in Eisenlegierungen

Ulbricht, A.; Böhmert, J.; Nikolaev, Y.

Nach Bestrahlung unter WWER-Reaktor-typischen Bedingungen werden an Testlegierungen mikrostrukturelle Veränderungen mit Neutronenkleinwinkelstreuung untersucht und dabei gezielt der Einfluß, der als versprödungsfördernd geltende Elemente Cu, P und Ni, herausgearbeitet.

  • Lecture (Conference)
    Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai, Tagungsbericht S. 587
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2000, Bonn, 23.-25. Mai, Tagungsbericht S. 587

Permalink: https://www.hzdr.de/publications/Publ-3098
Publ.-Id: 3098


Dissipative Strukturbildung bei exothermen Grenzflächenreaktionen

Grahn, A.; Prasser, H.-M.

Der Bericht beschäftigt sich mit spontaner Grenzflächenkonvektion und -turbulenz beim Stoff- und Wärmeübergang an fluiden Phasengrenzen zwischen zwei nicht mischbaren Phasen. Solche Effekte sind von großer industrieller Bedeutung, da die erzielten Stoffübergangsraten um ein Vielfaches über den bei gewöhnlicher Diffusion auftretenden liegen. Zwei unterschiedliche Mechanismen sind der „Motor“ für die Instabilitäten: Marangoni-Instabilität: Die Grenzflächenspannung ist eine Funktion der Temperatur und der Grenzflächenkonzentration des ausgetauschten Stoffes. Schwankungen der Temperatur und der Konzentration entlang der Phasengrenze führen folglich zu Grenzflächenspannungsgradienten. Grenzflächenspannungsgetriebene Instabilitäten äußern sich durch rollenförmige oder polygonale Konvektionszellen, Eruptionen oder Turbulenz an der Phasengrenze. Schwerkraftgetriebene Instabilität: Die Dichte ist ebenfalls eine Funktion der Temperatur und der Konzentration des gelösten Stoffes. Der Transport eines Stoffes über eine fluide Phasengrenze verändert die Zusammensetzung und die Dichte der angrenzenden Flüssigkeitsschichten, sodass instabile Dichteschichtungen auftreten können. Temperaturgradienten entstehen dabei durch Freisetzung von Reaktions- und/oder Lösungsenthalpie. Auftriebsbewegungen haben die Form von Thermiken (engl. plumes, thermals). Die Phänomene der Grenzflächenkonvektion werden in einer vertikalen Kapillarspaltgeometrie untersucht. Neben Stoffsystemen mit reaktivem Stoffübergang (Neutralisation von Karbonsäuren, Hydrolyse und Veresterung von Alkanoylhloriden) kamen auch solche mit reaktionsfreiem Stoffübergang (Karbonsäuren, Tensid) zur Anwendung. Die instabile Dichteschichtung, die durch den Konzentrationsgradienten infolge der Stoffdiffusion erzeugt wird, führt zu Auftriebskonvektion in Form von Thermiken. Die Anwesenheit einer exothermen Reaktion bewirkt eine Vergrößerung des Längenwachstums der Thermiken in der oberen Phase durch Aufprägung eines zusätzlich destabilisierenden Temperaturgradienten. In der unteren Phase kommt es dagegen zum Entstehen des doppeldiffusiven Fingerregimes bei Überlagerung des destabilisierenden Konzentrationsgradienten durch den stabilisierenden Temperaturgradienten. Beim Übergang eines Tensids konnten die für diese Stoffklasse charakteristischen Rollzellen, die durch Grenzflächenspannungsgradienten angetrieben werden, beobachtet werden. Diese Konvektionsstrukturen bleiben auf einen schmalen Bereich ober- und unterhalb der Phasengrenze beschränkt.
Die Transportgleichungen für Impuls, Stoff und Wärme wurden in ihrer 2-dimensionalen Form in einen Rechenkode umgesetzt und der Übergang einer einzelnen Komponente simuliert. Die hydrodynamischen Bedingungen an der Phasengrenze wurden so formuliert, dass lokale Änderungen der Zusammensetzung und der Temperatur zu Grenzflächenspannungsgradienten führen und die Phasengrenze damit dem Marangonieffekt unterliegt. Die Stoffeigenschaften wurden mit Ausnahme der Dichte im Volumenkraftterm der Impulsgleichung als konstant angenommen, sodass dichtegetriebene Konvektionen simuliert werden können. Die verschiedenen Konvektionsformen werden durch die Simulation qualitativ gut wiedergegeben. Bei Marangonikonvektion kommt es zu einer Verschiebung des steilen Konzentrationsgradienten von der Phasengrenze in die Kerne der Phasen, was zum schnellen Absterben der Marangonikonvektion führt. Die Wiedergabe des Längenwachstums der Thermiken durch Simulation eines realen Stoffsystems ist zufriedenstellend. Ebenso gibt die Simulation eine realistische Abschätzung zu erwartender Stoffströme bei Anwesenheit hydrodynamischer Instabilitäten. Größere Abweichungen zwischen Simulation und Experiment sind jedoch bei der horizontalen Größenskala der Fingerstruktur festzustellen, die wahrscheinlich auf die Boussinesq-Approximation zurückzuführen sind.

Keywords: Marangoni instability; Rayleigh-Bénard convection; mass transfer; fluid-fluid interface; numerical simulation; capillary gap experiments; chemical reaction; interfacial chemical reaction

  • Open Access Logo Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-307 Dezember 2000
    ISSN: 1437-322X

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Permalink: https://www.hzdr.de/publications/Publ-3097
Publ.-Id: 3097


Rhenium- und Technetiumverbindungen als potentielle Substrate und Modulatoren von P-Glykoprotein: Untersuchungen an Hirnzellen in vitro

Bergmann, R.; Brust, P.; Matys, S.; Pietzsch, H.-J.; Scheunemann, M.; Johannsen, B.

Die mit 99mTc-MIBI und ähnlichen Verbindungen nachweisbare Expression von P-Glykoproteinen (Pgp), z.B. In Tumoren, ist auch für den Transport von Substanzen durch die Blut-Hirn-Schranke (BHS) von Bedeutung. Die Pgp sind eine Komponente der multidrug resistance. In der BHJS bilden sie ein funktionelle Barriere zum Schutz des Gehirns vor toxischen Substanzen, indem sie die Pgp-Substrate in einem ATP-abhängigen Prozess vom Gehirn in das Blut transportieren. In RT-PCR Studien an amortalisierten Endothelzellen von Rattenhirnkapillaren (RBE4) wurde die Expression der Genprodukte von mdr1a und verstärkt von mdr1b, ähnlich den Verhältnissen bei frisch präparierten Rattenhirnmikrogefäßen, nachgewiesen. Zur Beurteilung von Transportvorgängen durch die Pgp an der BHS wurden deshalb in-vitro-Studien mit RBE-4-Zellen durchgeführt. Funktionell wurde die Pgp-Aktivität charakterisiert durch die Zellaufnahme und den Efflux von [99mTc]MIBI, [3H]Colchicin und [3H]Vinblastin unter Standardbedingungen und bei Hemmung der Pgp. Da die Akkumulation dieser Tracer ganz wesentlich von der metabolistischen Lage der Zellen abhängt wurden in ausgewählten Experimenten Simultanmessungen mit [18F]FDG und anderen Stoffwechseltracern durchgeführt. Mit dem so etablierten Modell konnte der Einfluss von mehr als 20 neuen 99Tc- bzw. Re-Komplexen auf die Pgp Aktivität untersucht werden. Es zeigt sich, dass verschiedene Substanzen zu Veränderungen der Tracerakkumulation in den RBE4-Zellen führen. So wurden Komplexe identifiziert, deren Wirkung mit der des Pgp-Inhibitors Verapamil vergleichbar ist. So erhöht sich z.B. spezifisch die nach 1 h in den Zellen verbleibende [99mTc]MIBI Aktivität bei der Applikation von einer 99Tc- oder analogen Re-Substanz auf 1157±72% bzw. 1117±56% und von Verapamil (je 10 µM) auf 859±103% der Kontrolle.
Die Ergebnisse lassen erwarten, dass Tc- oder Re-Komplexe nicht nur Substrate, sondern auch Modulatoren der Pgp sein können.

  • Lecture (Conference)
    Intern. Jahrestagung DGN, Kassel, 16.-19.04.1997
  • Abstract in refereed journal
    Nuklearmedizin 36 (1997) A34

Permalink: https://www.hzdr.de/publications/Publ-3096
Publ.-Id: 3096


Syntheses and Structures of Thorium(IV) Complexes with Bis(diphenylphosphino)ethane dioxide, Ph2P(O)CH2CH2P(O)Ph2, and Bis-(diphenylphosphoryl)amide, [Ph2P(O)NP(O)Ph2]-

Bonfada, E.; Schulz Lang, E.; Zan, R. A.; Abram, U.


Dedicated to Prof. Hans Hartl on the occassion of his 60th birthday

The cationic thorium(IV) complexes [Th{Ph2P(O)CH2CH2P(O)Ph2}2(NO3)3]NO3 and [Th{Ph2P(O)NP(O)Ph2}3(dmso)2]NO3 have been synthesized by reactions of Th(NO3)4 · 5H2O with bis(diphenylphosphino)ethane dioxide, Ph2P(O)CH2CH2P(O)Ph2 (L1), or ammonium bis-(diphenylphosphoryl)amide, (NH4)[Ph2P(O)NP(O)Ph2] (NH4L2), and subsequent recrystallization from dimethyl sulfoxide. The products have been studied spectroscopically and by X-ray crystallography.
The thorium atom is ten-co-ordinate in the [Th(L1)2(NO3)3]+ cation with a co-ordination sphere which does not meet one of the idealized polyhedra for ten-co-ordination. Th-O bonds have been found in the range between 2.342(3) (phosphine oxide) and 2.599(4) Å (nitrate).
An eight-co-ordinate thorium atom is found in the [Th(L2)3(dmso)2]+ cation. The almost ideal square-antiprismatic environment of the metal is occupied by oxygen atoms with Th-O bond lengths between 2.363(6) and 2.392(11) Å.

Keywords: Thorium complexes; Phosphine oxides; Bis(diphenylphosphoryl)amide; Crystal structure

  • Originalmitteilung in Zeitschrift Naturforschung

Permalink: https://www.hzdr.de/publications/Publ-3095
Publ.-Id: 3095


Rhenium Compounds Containing Heterocyclic Thiols - Syntheses and Structures

Schmidt-Brücken, B.; Abram, U.

Reactions of trans-[ReOCl3(PPh3)2] with 1,3-thiazoline-2-thiol (thiazSH), pyridine-2-thiol (pyrSH) or pyrimidine-2-thiol (pyrmSH) result in the formation of rhenium(V) oxo complexes or rhenium(III) species depending on the conditions applied. mer-[ReOCl3(thiazSH)(OPPh3)], trans-[ReCl3(PPh3)(thiazSH)2], [ReO(2-propO)(PPh3)Cl(pyrS-S,N)], cis-[ReCl2(PPh3)2(pyrS-S,N)] and [ReCl2(PPh3)2(pyrmS-S,N)] have been isolated from such reactions and structurally characterized.
cis-[ReCl2(PPh3)2(pyrS-S,N)] and [ReCl2(PPh3)2(pyrmS-S,N)] are obtained in better yields by ligand substitution on trans-[ReCl3(MeCN)(PPh3)2]. The reaction between (n-Bu4N)[ReOCl4] and purine-6-thiole (purinSH) results in the formation of the oxo-bridged [O{ReO(purinS-S,N)2}2].

Keywords: Rhenium Complexes; Heterocyclic Thiols; Crystal Structures

  • Anorganische allg. Chemie

Permalink: https://www.hzdr.de/publications/Publ-3093
Publ.-Id: 3093


[Au(Et2dtc)2][TcNCl4] - Synthesis and Structure

Abram, U.

[Au(Et2dtc)2][TcNCl4] (Et2dtc- = N,N-diethyldithiocarbamate) is formed by the reaction of [Au(CO)Cl] with [TcN(Et2dtc)2] in dichloromethane. The solid state structure of the compound is characterized by a large triclinic unit cell (a = 9.422(2), b = 22.594(5), c = 32.153(7) Å, a = 72.64(1), b = 85.19(1), g = 86.15(1)°, Z = 12) and shows an unusual arrangement due to long-range interactions between the technetium atoms and sulfur atoms of the [Au(Et2dtc)2]+ units (3.45 - 3.56 Å ) which assemble two anions and one cation to {[TcNCl4][Au(Et2dtc)2][TcNCl4]}- moieties.






Keywords: Technetium complexes; Gold complexes; Nitrido compounds; X-ray structure

  • Anorganische allg. Chemie

Permalink: https://www.hzdr.de/publications/Publ-3092
Publ.-Id: 3092


EXAFS as a tool for bond length determination in the environment of heavy atoms

Hennig, C.; Reich, T.; Roßberg, A.; Funke, H.; Bernhard, G.

The scattering amplitude of a heavy atom structure is generated mainly by the contribution of the heavy scatterers, because the scattering amplitude is proportional to the electron density. In the case of a low scattering part of light atoms this may lead to incorrect calculation of atomic coordinates. Is the structure model similar to correct structure, then it is very difficult to find an independent criterion for the accuracy of the bond lengths.

  • J. Synchrotron Rad. 8, 695-697 (2001)

Permalink: https://www.hzdr.de/publications/Publ-3091
Publ.-Id: 3091


Technetium and rhenium complexes with thioether ligands. VI. Synthesis and structural characterization of mixed-ligand oxorhenium(V) complexes containing bidentate dithioethers and monothiolato ligands.

Reisgys, M.; Spies, H.; Johannsen, B.; Leibnitz, P.; Pietzsch, H.-J.

  • Chem. Ber. 130 (1997) 1343-1347

Permalink: https://www.hzdr.de/publications/Publ-3089
Publ.-Id: 3089


Präzision in der Tumorbekämpfung: Positronen-Emissions-Tomographie (PET) überwacht die Zielgenauigkeit bei der Schwerionen-Tumortherapie.

Enghardt, W.; Hinz, R.; Lauckner, K.; Pawelke, J.; Pönisch, F.

kein Abstrakt

  • WGL-Journal, Vol. 1 (2000) 7-8

Permalink: https://www.hzdr.de/publications/Publ-3088
Publ.-Id: 3088


Uptake of 169Yb complexes in normal and tumour cells: influence of ligand and metabolic cell activity and stabilityx of cellular association

Kampf, G.; Knop, G.; Franke, W.-G.; Bergmann, R.; Johannsen, B.

  • Nucl. Med. Biol. 24 (1997) 349-355

Permalink: https://www.hzdr.de/publications/Publ-3087
Publ.-Id: 3087


Studies on Tumour cell-targeting with radiometals

Kampf, G.; Franke, W.-G.; Knop, G.; Wunderlich, G.; Brust, P.; Johannsen, B.

  • Book (Authorship)
    Radioactive Isotopes in Clinical Medicine and Resarch XXII (ed. by H. Bedrgmann, A. Kroiss, H.Sinzinger 1997, Birkhäser Verlag Basel/switzerland) 441-444

Permalink: https://www.hzdr.de/publications/Publ-3086
Publ.-Id: 3086


Non-volatile memory effects of ion-beam synthesized Ge and Si nanoclusters in thin SiO2 layers: electrical characterization vs. microstructure

Gebel, T.; von Borany, J.; Skorupa, W.; Möller, W.; Thees, H.-J.; Wittmaack, M.; Stegemann, K.-H.

Nanocluster memories are promising for future non-volatile memory applications. In this work thin SiO2 films were implanted with Ge+ and Si+ and annealed subsequently. Charge storage effects of the MOS capacitors have been studied through I-V and high frequency C-V measurements. Positive voltage pulses lead to a positive flatband voltage shift of the C-V curve. Detrapping by applying negative voltage pulses leads to a negative shift. The achieved programming window using 6 V / 100 ms pulses for Ge based structures is higher than that for Si (2.0 V vs. 0.2 V). However the retention times for Si based memories are longer. For dedicated process parameters microstructural investigations (RBS, XTEM) of Ge+ implanted SiO2 layers showed two bands of clusters, one near the interface SiO2/Si and one in the center of the SiO2 layer.

Keywords: nanocluster; nanocrystal; non-volatile memory

  • Lecture (Conference)
    MRS Fall Meeting, Symposium T, Boston, Nov. 29 - Dec. 3, 1999
  • Contribution to external collection
    Mat. Res. Soc. Symp. Proc. 592, T6.10.1 (2000)

Permalink: https://www.hzdr.de/publications/Publ-3084
Publ.-Id: 3084


Different response of cerebral and non-cerebral endothelial cells to cytotoxic hypoxia

Ahlemeyer, B.; Brust, P.; Johannsen, B.

  • Neurochem. Int. 31 (1997) 39-44

Permalink: https://www.hzdr.de/publications/Publ-3082
Publ.-Id: 3082


Triphenylarsonium-[11C]Methylid - Ein neuer 11C-Präkursor zur Synthese von 11C-Indolderivaten

Zessin, J.; Steinbach, J.; Johannsen, B.

Derivate des Indols sind Verbindungen mit vielfältigen physiologischen Funktionen und daher als Radiotracer von Interesse. Für die Synthese solcher 11C-Verbindungen kann man die Umsetzung von Arsoniumyliden mit o-Aminobenzoylverbindungen zu Indolen (Bravo, 1970) nutzen.
Methyltriphenylarsoniumiodid (MTPAI) als Vorstufe des Triphenylarsoniummethylids (TPAM) kann ausgehend von Methyliodid hergestellt werden. Mit [11C]Methyliodid ermöglicht dieser reaktionsweg die direkte Darstellung von 11C-markierten Indolen.

Der erste syntheseschritt umfasst die Quaternisierung von Triphenylarsin mit [11C]Methyliodid zu [11C]MTPAI. Ausreichende Reaktionsgeschwindigkeiten werden nur in Gegenwart stark polarer Lösungsmittel erreicht. Innerhalb von 10 min bei 120°C wurden in THF/DMSO (3:1) radiochemische Ausbeuten von 67% (bezogen auf [11C]CH3I, zerfallskorrigiert) und in Ethanol 76% erreicht.
Im zweiten Schritt erfolgt die in situ Generierung von [11C]TPAM durch Butyllithium und nachfolgend die Umsetzung mit o-Aminobenzaldehyd zu [2-11C]Indol.
Durch Verwendung von Alkyl-o-aminophenylketonen können 3-alkylierte [2-11C]Indole hergestellt werden. O-Aminoacetophenon ergibt 3-Methyl-[2-11C]Indol und o-Aminopropiophenon 3-Etyl-[2-11C]Indol.
Ausgehend von dem neuen 11C-Präkursor Triphenylarsonium[11C]methylid sind 11C-kernmarkierte Indole mit radiochemischen Ausbeuten von 23 - 31% (bezogen auf [11C]CH3I, zerfallskorrigiert) herstellbar.

  • Lecture (Conference)
    36. Intern. Jahrestagung DGN, Leipzig, 01.-04.04.1998
  • Abstract in refereed journal
    Nuklearmedizin 37 (1998) A44

Permalink: https://www.hzdr.de/publications/Publ-3081
Publ.-Id: 3081


Rhenium complexes of 17Alpha-substituted estradiol capable of binding to the estrogen receptor

Wüst, F.; Katzenellenbogen, J. A.; Spies, H.; Johannsen, B.

The gonadal steroids are implicated in hormone-dependent cancers of the breast and prostate.
In order to image estrogen receptor positive tumors by using 99mTc based radiopharmaceuticals, we have synthesized novel rhenium(V), (III) and (i) complexes of 17Alpha-substituted estradiol. In our first investigations we used rhenium as a model for the radioactive technetium.

These complexes represent new classes of estrogen receptor-binding rhenium complexes.
The binding affinities (lamb-cytosol) at 0°C reveal RBA values of about 23% for the oxorhenium(V) complexes when X = O and 8% when X = S. The RBA values at 25°C are 10% for the oxorhenium(V) complexes when X = O and 15% when X = S. For the rhenium(III) and rhenium(I) complexes the RBA values are significantly lower for 0°C and 25°C, ranging from 0.6% to 2.5%.
Further studies will investigate the stability of these complexes under in vivo conditions using the corresponding 99mTc-complexes.

  • Lecture (Conference)
    Joint Congrss of the European Association of Nuclear Medicine and the World Federation of Nuclear medicine and Biology, Berlin 30.08.-04.09.1998
  • Abstract in refereed journal
    J. Nucl. Med. 25 (8) (1998) 866

Permalink: https://www.hzdr.de/publications/Publ-3080
Publ.-Id: 3080


The scenario of three-dimensional instabilities of the cylinder wake in an external magnetic field. A linear stability analysis

Mutschke, G.; Gerbeth, G.; Shatrov, V.; Tomboulides, A.

A more detailed look is given on the scenario of 3-D instabilities taking place in the MHD cylinder flow when oncoming flow and magnetic field are parallel, thus extending our previous letter \cite{PHFL97}. The results presented here are in the frame of a linear stability analysis in the range 100As the strength of the magnetic field is increased, a non-monotonic behaviour of 3-D instability is found. This is mainly due to the fact that the underlying 2-D flow changes considerably from periodic to steady flow while different instability mechanisms are superimposed. The behaviour at weak magnetic fields depends on the Reynolds number
and is either a damping or an enhancing influence on 3-D instability. At the critical value of 2-D instability $N_c^{2D}$
a local maximum in the 3-D instability curve occurs which leads to 3-D instability at Reynolds numbers down to $Re \sim 150$,
i.e.~lower than in the hydrodynamic cylinder flow. Increasing $N$ further, 3-D instability is first being damped while for larger values of the magnetic field 3-D instability is generally amplified. Therefore, 3-D steady flows at strong magnetic fields may also exist at Reynolds numbers which are considerably lower than the critical
Reynolds number for the onset of three-dimensionality of purely hydrodynamic cylinder flow.
For transverse magnetic fields, a mainly monotonic and much stronger damping of three-dimensionality as compared to the aligned field case is found when the strength of the magnetic field increases.

Keywords: Fluid dynamics; MHD; Flow Stability; Linear Stability Analysis

  • Physics of Fluids Vol 13, No 3, (March 2001) pp. 723-734

Permalink: https://www.hzdr.de/publications/Publ-3079
Publ.-Id: 3079


Diagnostische Treffsicherheit von 18F-FDG bei differenziertem Schilddrüsenkarzinom: Vergleich von dediziertem PET und Koinzidenzkamera

Tiepolt, C.; Beuthien-Baumann, B.; Kühne, A.; Bredow, J.; Burchert, W.; Kropp, J.; Franke, W.-G.

Die hohe diagnostische Treffsicherheit von 18F-FDG erfordert für die breite klinische Anwendung eine leichte Verfügbarkeit der Methode. Die Koinzidenzkameratechnik bietet möglicherweise eine Alternative zu dediziertem PET. Unsere Untersuchung soll im intraindividuellen Vergleich der Befunde die klinische Relevanz der Unterschiede der Meßmethoden analysieren.
METHODIK: Untersucht wurden 20 Patienten mit differenziertem Schilddrüsenkarzinom ( 5 papilläre, 15 follikuläre; pT2-4) nach Thyreoidektomie und Radiojodablation. Zum Zeitpunkt der Diagnosestellung waren bei 8 Patienten Lymphknoten-/Fernmetastasen bekannt. Vor der Untersuchung wurde eine 12-stündige Nahrungskarenz eingehalten. Die Untersuchung erfolgte 60 min nach Injektion von 300 MBq 18F-FDG mit einem dedizierten PET-System (ECAT EXACT HR+) sowie 4 h nach Applikation mit einer Koinzidenzkamera (Solus EPIC). Für den Vergleich der Verfahren wurden jeweils die nicht schwächungskorrigierten Daten herangezogen. Bei allen Patienten lag im zeitlichen Abstand von 4 d bis 2 Monaten eine 131I Ganzkörperszintigraphie vor

Ergebnisse:......Koinzidenz..........PET..............131I
----------------------------------------------------------------------------------
Hals....................15.....................26..................4
Thorax.................32.....................55................18
Skelett..................3.......................5..................6
Gesamtzahl.........50.....................86................38

Die 86 mit PET nachgewiesenen Läsionen waren mit der Koinzidenzkamera zu 27% gleich gut, zu 31% schlechter erkennbar. In 42% der Fälle war eine Detektion mit der Koinzidenztechnik nicht möglich. In Abhängigkeit von der Läsionsgröße bestand eine 94%-ige Übereinstimmung beider Verfahren oberhalb 1,5 cm und eine 64%-ige Übereinstimmung im Bereich von 1-1,5 cm. Die mit PET nachgewiesenen Läsionen unter 1 cm waren mit der Koinzidenzkamera nicht erkennbar. Hinsichtlich des klinischen Staging wurde mit der Koinzidenztechnik bei 13 Patienten der gleiche Lymphknotenstatus und bei 18 Patienten der gleiche Metastasenstatus wie mit PET ermittelt. 5 Patienten wurden auf Grund kontralateralen Lymphknotenbefalls, der nur mit PET nachweisbar war, zu niedrig eingestuft. Bei je 2 Patienten war eine richtige Einstufung des Lymphknoten- und Metastasenstadiums mit der Koinzidenzkamera nicht möglich.

  • Lecture (Conference)
    37. Intern. Jahrestagung DGN, Ulm, 14.-17.04.1999
  • Abstract in refereed journal
    Nuklearmedizin 38 (1999) A55

Permalink: https://www.hzdr.de/publications/Publ-3078
Publ.-Id: 3078


16Alpha-[18F]Fluorestradiol für die Routine

Römer, J.; Füchtner, F.; Steinbach, J.; Johannsen, B.

16Alpha-[18F]Fluorestradiol [18FES) hat sich in klinischen Studien als geeigneter PET-Tracer zur Darstellung humaner primärer und metastatischer Brustumore erwiesen. Im PET-Zentrum Rossendorf wurde daher ein schnelles Darstellungsverfahren für 18FES ausgearbeitet und diese Synthese automatisiert, um 18FES qualitätsgerecht für die medizinische Anwendung verfügbar zu machen.
Wir verwendeten ein modifiziertes [18F]FDG-Modul der Fa. Nuclear Interface. Die Bedingungen der manuellen Synthese wurden gemäß Schema 1 optimiert.

Im modifizierten Synthesemodul erforderten die Fluorierung des Präkursors (1) und die zweistufige Hydrolyse zum 18FES einen Zeitbedarf von 30 min, die notwendige Feinreinigung mittels HPLC 20 min. Nach Sterilfiltration war 18FES knapp 1 h nach EOB in einer zerfallskorrigierten Ausbeute von 50% verfügbar.
Die Fluorierung lief mit durchschnittlicher Ausbeute von 70% ab. Ein einfaches Hydrolyseverfahren gewährte hohe Umsetzung zum 18FES und die Abtrennung des unumgestzten [18F]Fluorids. Ein reproduzierbar auftretendes fluor-markiertes Nebenprodukt mit 5 - 10 % Aktivitätsanteil machte eine semipräparative RP-HPLC-Reinigung unumgänglich. Die Elution erfolgte isokratisch mit ethanolischer physiologischer Kochsalzlösung und lieferte in einem scharfen Peak chemisch und radiochemisch reines 18FES.

Die Ergebnisse zeigen, dass 18FES in einem automatischen Modul sicher und reproduzierbar dargestellt werden kann. Damit wird eine zukünftige regelmäßige Herstellung von 18FES für die medizinische Anwendung möglich.

  • Poster
    36. Intern. Jahrestagung DGN, Leipzig, 01.-04.04.1998
  • Abstract in refereed journal
    Nuklearmedizin 37 (1998) A50

Permalink: https://www.hzdr.de/publications/Publ-3077
Publ.-Id: 3077


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