Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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42029 Publications
Konzeption und prototypische Realisierung einer Datenbankanwendung für die Verwaltung von Betriebsparametern von Ionenstrahlbeschleunigern
Kunze, P.
Abstract
Es wird beschrieben, wie eine Datenbank für Betriebswerte eines Teilchenbeschleunigers aufgebaut wurde. Der Schwerpunkt der Betrachtungen liegt dabei auf der Theorie zum Aufbau einer solchen Datenbank.
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Other report
Dresden: HTW Dresden, Diplomarbeit, 2005
50 Seiten
Permalink: https://www.hzdr.de/publications/Publ-9890
Open charm and leptons at RHIC
Kämpfer, B.
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Lecture (Conference)
ECT* - Electromagnetic probes of hot and dense matter, 03.-11.06.2005, Trento, Italy
Permalink: https://www.hzdr.de/publications/Publ-9889
Quasi-particle description of QCD matter
Kämpfer, B.
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Lecture (Conference)
Probing QCD with High Energy Nuclear Collisions, 16.01.2005, Hirschegg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9888
Digitalisierung der Signalverarbeitung eines Rotorvoltmeters
Arnold, S.
Abstract
Das Ziel der Diplomarbeit war, auf Basis eines 32-Bit Mikrocontrollers wesentliche Teile der Signalverarbeitung eines Rotorvoltmeters von analoger Schaltungstechnik in eine digitale Verarbeitung zu überführen. Mit diesem Schritt kann das am Institut für Ionenstrahlphysik und Materialforschung des FZR eingesetzte Rotorvoltmeter eines Van-de-Graaff-Ionenbeschleunigers in seiner Anwendung wesentlich verbessert werden. Erwartet werden neben der einfacheren Parametrierung und der erhöhten Flexibilität des Gerätes vor allem auch eine Erhöhung der Stabilität im Betrieb durch den Wegfall von Drifterscheinungen analoger Schaltungstechnik.
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Other report
Chemnitz: TU Chemnitz, Diplomarbeit, 2006
50 Seiten
Permalink: https://www.hzdr.de/publications/Publ-9887
Digitalisierung der Funktion eines Meßgerätes zur Bestimmung der Beschleunigungsspannung von Van-de-Graaff-Ionenbeschleunigern
Voigtländer, G.
Abstract
Das Ziel der Diplomarbeit war, auf Basis eines 32-Bit Mikrocontrollers wesentliche Teile der Signalverarbeitung eines Rotorvoltmeters von analoger Schaltungstechnik in eine digitale Verarbeitung zu überführen. Mit diesem Schritt kann das am Institut für Ionenstrahlphysik und Materialforschung des FZR eingesetzte Rotorvoltmeter eines Van-de-Graaff-Ionenbeschleunigers in seiner Anwendung wesentlich verbessert werden. Erwartet werden neben der einfacheren Parametrierung und der erhöhten Flexibilität des Gerätes vor allem auch eine Erhöhung der Stabilität im Betrieb durch den Wegfall von Drifterscheinungen analoger Schaltungstechnik.
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Other report
Dresden: HTW Dresden, Diplomarbeit, 2004
50 Seiten
Permalink: https://www.hzdr.de/publications/Publ-9886
Low-energy tail of the giant dipole resonance in 98Mo and 100Mo deduced from photon-scattering experiments
Rusev, G.; Schwengner, R.; Dönau, F.; Erhard, M.; Grosse, E.; Junghans, A. R.; Kosev, K.; Schilling, K. D.; Wagner, A.; Becvar, F.; Krticka, M.
Abstract
Dipole-strength distributions in the nuclides 98Mo and 100Mo up to the neutron-separation energies have been studied in photon-scattering experiments at the superconducting electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf. In order to determine the dipole-strength distribution up to the neutron emission threshold statistical methods were developed for the analysis of the measured spectra. The measured spectra of scattered photons were corrected for detector response and atomic background by simulations using the code GEANT3. Simulations of gamma-ray cascades were performed in order to correct the intensities of ground-state transitions for feeding from high-lying levels and to determine their branching ratios. The photoabsorption cross sections obtained for 98Mo and 100Mo from the present (gamma,gamma) experiments are combined with (gamma,n) data from literature resulting in a photoabsorption cross section covering the full range from 4 to about 15 MeV of interest for nuclear astrophysics network calculations. Novel information about the low-energy tail of the Giant Dipole Resonance and the energy spreading of its strength is derived. The photoabsorption cross sections deduced from the present photon-scattering experiments are compared with existing data from neutron capture and 3He induced reactions.
Keywords: Photon scattering; nuclear structure; giant dipole resonance; dipole strength; photoabsorption cross section
Involved research facilities
- γ-ELBE DOI: 10.58065/24020
Related publications
- DOI: 10.58065/24020 is cited by this (Id 9885) publication
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Physical Review C 77(2008), 063421
DOI: 10.1103/PhysRevC.77.064321
Cited 80 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-9885
Defect profiling with positrons recent results on ion implanted 6H-SiC
Anwand, W.; Brauer, G.; Skorupa, W.
Abstract
Positron annihilation spectroscopy is used to analyse implantation defects in 6H-SiC.
Keywords: Positron annihilation Spectroscopy; SiC; defects
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Lecture (Conference)
Frühjahrstagung des Arbeitskreises Herstellung und Charakterisierung von massiven GaAs-, InP- und SiC-Kristallen der Deutschen Gesellschaft für Kristallwachstum und Kristallzüchtung (DGKK),, 31.03.-01.04.2004, Halle (Saale), Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9884
Ionenstrahlmodifikationen magnetischer Schichten
Abstract
In dem Vortrag werden die neuen Ergebnisse auf dem Gebiet der Cr- bzw. Ni-Implantation in Permalloy vorgestellt. Darüber hinaus wird über erste Ergebnisse der Bestrahlung von FeAl-Legierungen berichtet.
Keywords: ion irradiation; ion implantation; magnetism; permalloy; FeAl
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Lecture (Conference)
Workshop zur "Ionenstrahlphysik und Nanotechnologie", 10.-11.05.2007, Bochum, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9883
Early stage of ripple formation on Ge(001) surfaces under near-normal ion beam sputtering
Carbone, D.; Alejandro, A.; Raul, G.; Facsko, S.; Plantevin, O.; Metzger, T. H.
Abstract
We present a study of the early stage of ripple formation on Ge(001) surfaces irradiated by a 1 keV Xe+ ion beam at room temperature and near-normal incidence. A combination of a grazing incidence x-ray scattering technique and atomic force microscopy allowed us to observe a variation of the symmetry of the surface nanopattern upon increase of the ion fluence. The isotropic dot pattern formed during the first minutes of sputtering evolves into an anisotropic ripple pattern for longer sputtering time. These results provide a new basis for further steps in the theoretical description of the morphology evolution during ion beam sputtering.
Keywords: ion beam sputtering; nanostructures
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Nanotechnology 19(2008), 035304-035309
DOI: 10.1088/0957-4484/19/03/035304
Cited 36 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-9882
Polymorphism in Liquid Crystals from Star-shaped Mesogens
Gemming, S.; Popov, I.; Lehmann, M.
Abstract
Star-shaped molecules based on a phloroglucinol core with three oligobenzoate arms are powerful mesogens, that can be combined to columnar liquid crystalline materials and to soft organic crystals. The structural properties of such modern materials exhibit polymorphism at two different length scales. On the molecular level, the mesogens are highly flexible molecules with a large variety of almost isoenergetic conformers of different propensity towards a regular stacking in the bulk phase. On the supramolecular level, polymorphic structures occur, which comprise different liquid crystalline phases with anisotropic columnar order and soft crystals with a more isotropic three-dimensional ordering. For the smallest mesogen the present experimental structure data and computational results give evidence that the two forms of polymorphism are linked. Columnar liquid crystals form from a low-symmetry, folded conformer, which already accounts for the nano-segregation of the planar aromatic centre and the flexible aliphatic chain parts of the mesogen, whereas the soft, more isotropic crystals are grown from the C3-symmetric, star-shaped conformer. Molecular dynamics simulations confirm the stability of each structure at room temperature.
Keywords: liquid crystals; polymorphism; computer modelling; density-functonal methods
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Philosophical Magazine Letters 87(2007)11, 883-891
DOI: 10.1080/09500830701537959
Cited 7 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-9881
Comparison of different buncher cavity designs for the 4GLS ERLP
Wooldridge, E.; Beard, C. D.; Gerth, C.; Büchner, A.
Abstract
A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) presently being built at Daresbury Laboratory. A buncher is required for the ERLP downstream of the photocathode gun to decrease the relatively long bunches (20-30ps) from the GaAs cathode. Three different single-cell cavity designs were investigated: the Cornell buncher, the ELBE buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CSTs Microwave Studio and ASTRA. The fundamental frequency and field pattern of each buncher was investigated in Microwave Studio. The EU cavity was scaled from 500MHz to the required frequency for the buncher of 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.
Keywords: ELBE; RF; Buncher; Injector
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Poster
EPAC 2004, 05.-09.07.2004, Luzern, Schweiz -
Contribution to proceedings
EPAC 2004, 05.-09.07.2004, Luzern, Schweiz
Proceedings of EPAC 2004: European Physical Society Accelerator Group, 92-9083-232-0, 467-469
Permalink: https://www.hzdr.de/publications/Publ-9880
FIB induced growth of antimony nanowires
Schoendorfer, C.; Lugstein, A.; Bischoff, L.; Hyun, Y. J.; Pongratz, P.; Bertagnolli, E.
Abstract
The impact of high energy Ga ion beams focused to diameters below 100 nm on antimony (Sb) substrates offers a new approach for the formation of pure Sb nanowires. In contrast to several well-known processes for bottomup fabrication of one-dimensional nanostructures, for this process neither additional temperature treatment nor any additional material component is needed. Initially, the resulting nanostructures are completely amorphous and show very homogeneous diameters in the range of 20 nm. Lengths up to several microns can be achieved. Annealing at temperatures around 150 °C leads to re-crystallization of these nanowires.
Keywords: Nanowires; Nanofibers; Quantum wires; Antimony; Sb; Focused ion beam; FIB
- Microelectronic Engineering 84(2007)5-8, 1440-1442
Permalink: https://www.hzdr.de/publications/Publ-9879
Nuclear astrophysics measurements with photo-neutrons and bremsstrahlung at ELBE
Junghans, A. R.
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Lecture (others)
Physikalisch-Technische Bundesanstalt Dep. 6.4, 01.09.2005, Braunschweig, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9876
Search for pygmy strength in Molybdenum isotopes close to particle separation energies
Grosse, E.
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Lecture (Conference)
Nuclear Physics in Astrophysics-II, 16.-20.05.2005, Debrecen, Hungary
Permalink: https://www.hzdr.de/publications/Publ-9875
Sterne und Kerne - Die Entstehung der chemischen Elemente durch nukleare Prozesse in Urknall, Sternen und Supernovae
Grosse, E.
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Lecture (others)
Tag der offenen Tür, 30.04.2005, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9874
Energie aus der Kernfusion und aus der Kernspaltung
Grosse, E.
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Lecture (others)
Jugendzentrum Pi, 03.03.2005, Freiberg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9873
Isovector Proton-Neutron Pairing
Frauendorf, S.
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Lecture (Conference)
INT Program 05-3: Nuclear Structure Near the Limits of Stability, 14.11.2005, Seattle, USA
Permalink: https://www.hzdr.de/publications/Publ-9872
New Symmetries of rotating nuclei
Frauendorf, S.
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Lecture (Conference)
Colloquium, Physics Division, 15.-16.12.2005, Argonne, USA
Permalink: https://www.hzdr.de/publications/Publ-9871
Infrarotspektroskopie an Proteinen: Fluoreszenz-IR-Kreuzkorrelation
Fahmy, K.
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Lecture (Conference)
Anwendertreffen Bruker Ettlingen, 28.11.2005, Ettlingen, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9870
Structure and pH sensitivity of transmembrane helix 3 of rhodopsin
Fahmy, K.
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Lecture (Conference)
European Conference on the Spectroscopy of Biological Molecules, 06.09.2005, Aschaffenburg, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9869
Coupling of helix 8 of rhodopsin to the retinal Schiff base studied by infrared and fluorescence cross-correlation spectroscopy
Fahmy, K.
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Lecture (Conference)
Sektionstagung Deutsche Gesellschaft für Biophysik, 05.05.2005, Münster, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9868
Infrared and fluorescence spectroscopic studies on molecular switching by G protein.coupled receptors
Fahmy, K.
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Lecture (others)
Deutsche Universität in Kairo, 22.03.2005, Kairo, Egypt
Permalink: https://www.hzdr.de/publications/Publ-9867
Molecular switching by GPCRs
Fahmy, K.
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Lecture (others)
Université Strasbourg, 21.02.2005, Strasbourg, France -
Lecture (others)
Universität Osnabrück, 19.04.2005, Osnabrück, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9866
High resolution grazing incidence diffraction on lateral nanostructures created by focused ion beam implantation on semiconductor surfaces
Grenzer, J.; Bischoff, L.; Posselt, M.; Pietsch, U.
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Lecture (Conference)
Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Grossgeräten (SNI-2006), 04.-06.10.2006, Hamburg, Germany
Permalink: https://www.hzdr.de/publications/Publ-9865
X-ray studies of semiconductor surfaces modified by focused ion beam implantation
Grenzer, J.; Bischoff, L.; Posselt, M.; Pietsch, U.
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Lecture (Conference)
8th Biennial Conference on High Resolution X-ray Diffraction and Imaging, 19.-22.09.2006, Karlsruhe, Germany -
Lecture (Conference)
Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Grossgeräten (SNI-2006), 04.-06.10.2006, Hamburg, Germany
Permalink: https://www.hzdr.de/publications/Publ-9864
Influence of energetic ions on the L10 ordering of FePt films fabricated by magnetron sputtering
Cantelli, V.; von Borany, J.; Grenzer, J.; Fassbender, J.
Abstract
Due to the high uniaxial anisotropy L10-ordered FePt is currently the most favored candidate for future high density storage applications. With respect to a feasible fabrication technology, it is necessary (i) to produce such films on amorphous substrates, and (ii) to enable a low processing temperature (T<400°C). FePt films deposited at RT only exhibit the face-centered cubic A1-phase. Thus, either deposition or a post-deposition heat treatment at temperatures above typically 500°C is required, in order to achieve the L10-phase. We report on the L10 ordering of stoichiometric FePt thin films fabricated on SiO2/Si substrates by magnetron sputtering at various temperatures (RT - 400°C). Using a low deposition rate of about 0.6 Å/s and an Ar pressure of 0.3 Pa the ion/atom-ratio during deposition is » 1 where the ions exhibit energies of about 20 eV. In addition, FePt films have been irradiated subsequently with He ions of 50 keV and fluencies between 1x1015 and 3x1016 cm−2 for comparison. The kinetics of A1-L10 transition and ordering have been investigated with in-situ X-ray diffraction at the Synchrotron-beamline ROBL at ESRF. L10 ordered FePt films with an ordering parameter S=0.8 have been achieved already for an overall process temperature below 350°C. The results are discussed in terms of ion-assisted activation and segregation which supports the atomic relocation during L10 ordering.
Keywords: FePt; L10 transition; magnetron sputtering; ion irradiation
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Lecture (Conference)
15th Intn Conf. on Ion Beam Modification of Materials, 18.-22.09.2006, Taormina, Italy
Permalink: https://www.hzdr.de/publications/Publ-9863
Structural studies of ion beam synthesized nanocrystals: diamond in SiC and SiC in diamond
Eichhorn, F.; Heera, V.; Weishart, H.; Schell, N.
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Lecture (Conference)
13th ESRF User Meeting, 12.02.2003, Grenoble, France
Permalink: https://www.hzdr.de/publications/Publ-9862
The Rossendorf CRG Beamline ROBL for radiochemistry and materials research
Schell, N.
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Lecture (others)
Institute of Physics of the Academy of Sciences, 11.09.2003, Warsaw, Poland
Permalink: https://www.hzdr.de/publications/Publ-9861
Melt stirring during directional solidification using modulated magnetic fields
Willers, B.; Räbiger, D.; Dong, J.; Eckert, S.; Nikrityuk, P. A.; Eckert, K.
Abstract
The imposition of an RMF on a solidifying metal column causes problems like the occurrence of typical segregation pattern or a deflection of the upper free surface leading to surface defects or the entrainment of gas. The RMF application provides a permanent radial inward flow along the solidification front. Such flow is responsible for the transport of solute to the axis of the ingot resulting in typical freckle segregation pattern in form of vertical channels filled with alloy of eutectic composition. In this paper we present a new innovative method of electromagnetic stirring using a modulated RMF which offers a considerable potential for a well-aimed modification of casting properties Solidification experiments as well as numerical simulations were carried out considering the directional solidification of Pb Sn alloys from a water cooled copper chill. A modulated rotating magnetic field (RMF) was applied for melt agitation. Thermocouples were used to measure the temperature field during solidification. The velocity field in the liquid phase was determined by means of Ultrasound Doppler velocimetry (UDV). Our numerical model is based on the classical mixture formulation. The comparison between numerical simulations and solidification experiments delivered a good agreement. Our results demonstrate the modulation magnetic field enables an effective control of the flow field and the structure of the solidified samples. Modifications of the grain structure and macrosegregation effects are discussed with respect to the details of the flow field.
Keywords: solidification; Pb-Sn alloys; convection; rotating magnetic field; Ultrasound Doppler Velocimetry
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Lecture (Conference)
EUROMAT2007 - European Congress on Advanced Materials and Processes, 10.-13.09.2007, Nürnberg, Germany
Permalink: https://www.hzdr.de/publications/Publ-9860
Materials research with synchrotron radiation at the Rossendorf Beamline ROBL at ESRF
Schell, N.
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Lecture (others)
University of Sao Paulo, 20.03.2003, Sao Paulo, Brazil -
Lecture (others)
CENIMAT F.C.T./Universidade Nova de Lisboa, 04.04.2003, Lisbon, Portugal
Permalink: https://www.hzdr.de/publications/Publ-9859
PET-guided Radiotherapy - Fact or Fiction
Enghardt, W.
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Invited lecture (Conferences)
Workshop of the Belgian Foundation against Cancer Emerging Hadron Therapy Projects in Europe, 13.11.2005, Brüssel, Belgium
Permalink: https://www.hzdr.de/publications/Publ-9858
Heavy Ion Tumour Therapy and In-Beam Position Emission Tomography
Enghardt, W.
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Lecture (others)
TU Dresden, 06.06.2005, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9857
Data Processing for In-Beam Position Emission Tomography
Enghardt, W.
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Invited lecture (Conferences)
Real Time Conf. 2005, 08.06.2005, Stockholm, Sweden
Permalink: https://www.hzdr.de/publications/Publ-9856
Zentrum für Innovationskompetenz für Medizinische Strahlenforschung in der Onkologie Dresden
Enghardt, W.
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Lecture (others)
Berufsakademie Riesa, 31.05.2005, Riesa, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9855
In-beam PET bei der Krebstherapie mit Ionenstrahlen
Enghardt, W.
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Invited lecture (Conferences)
Atominst. der österreichischen Univ., 13.04.2005, Wien, Austria
Permalink: https://www.hzdr.de/publications/Publ-9854
PET-geführte Strahlentherapie - Vision oder Realität
Enghardt, W.
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Lecture (others)
Medizinische Fakultät, 17.01.2005, Dresden, Deutschland -
Lecture (Conference)
GDC Jahrestagung 2005, Fachgruppe Nuklearchemie, 12.09.2005, Düsseldorf, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9853
RPC detectors at ELBE
Dohrmann, F.
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Lecture (Conference)
CBM Collab. Meeting, 10.09.2005, Piaski, Poland
Permalink: https://www.hzdr.de/publications/Publ-9852
Testing RPC detectors at ELBE
Dohrmann, F.
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Lecture (Conference)
HADES Collab. Meeting, 10.06.2005, Dubna, Russia
Permalink: https://www.hzdr.de/publications/Publ-9851
Tests of RPC detectors at ELBE: Status report
Dohrmann, F.
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Lecture (Conference)
CBM Collab. Meeting, 10.03.2005, Darmstadt, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9850
Quasiparticle Model of QCD Matter and the QCD Critical End Point
Bluhm, M.
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Lecture (others)
Universität Bielefeld, 20.09.2005, Bielefeld, Deutschland -
Lecture (Conference)
VI Workshop, 07.10.2005, Prerow, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9849
Strongly Interaction Matter within a Quasiparticle Perspective with Critical End Point Effects
Bluhm, M.
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Lecture (Conference)
Extreme QCD, 04.08.2005, Swansea, England
Permalink: https://www.hzdr.de/publications/Publ-9848
Possible Critical End Point Effects on the QCD Equation of State
Bluhm, M.
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Invited lecture (Conferences)
ITP, 27.05.2005, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9847
Equation of state strongly interacting matter
Bluhm, M.
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Lecture (Conference)
DPG Tagung Berlin, 08.03.2005, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9846
Soft chiral vibrations in Mo-106
Zhu, S.; Hamilton, J.; Ramayya, A.; Gore, P.; Rasmussen, J.; Dimitrov, V.; Frauendorf, S.; Xu, R.; Hwang, J.; Fong, D.; Yang, L.; Li, K.; Chen, Y.; Zhang, X.; Jones, E.; Luo, Y.; Lee, I.; Ma, W.; Cole, J.; Drigert, M.; Stoyer, M.; Ter-Akopian, G.; Daniel, A.
Abstract
High-spin states in neutron-rich Mo-106 were investigated by detecting the prompt gamma-rays in the spontaneous fission of Cf-252 with Gammasphere. Several new bands are observed. Two sets of Delta I = 1 bands in Mo-106 are found to have all the characteristics of a new class of chiral vibrational doublets. Tilted axis cranking calculations support the chiral assignment and indicate that the chirality is generated by neutron h(11/2) particle and mixed d(5/2), g(7/2) hole coupled to the short and long axis, repectively.
- European Physical Journal A 25(2005)Suppl.1, 459-462
Permalink: https://www.hzdr.de/publications/Publ-9845
Suppression of band crossing in the neutron-rich nuclei Yb-172,Yb-173 due to the absence of a static pair field
Venkova, T.; Cast, W.; Lieder, R.; Bazzacco, D.; de Angelis, G.; Lieder, E.; Pasternak, A.; Menegazzo, R.; Lunardi, S.; Alvarez, C.; Ur, C.; Martinez, T.; Axiotis, M.; Napoli, D.; Urban, W.; Rzaca-Urban, T.; Frauendorf, S.
Abstract
High-spin states in the neutron-rich nuclei Yb-172,Yb-173 have been populated in a Er-170(Li-7,(p,d,t)chi n) incomplete-fusion reaction and the emitted gamma-radiation was detected with the GASP array. The signature partners of the 7/2(+)[633] rotational band of the odd-N Yb-173 isotope have been newly established and were observed up to spin values of (45/2(+)) and (43/2(+)), respectively. The ground-state band of the even-even nucleus Yb-172 has been observed up to a spin value of (22(+)). No band crossings were found in these bands. To explain this observation; it is proposed that the static pair field is absent; considering that the neutron odd-even mass differences reach for these nuclei very small values and that the band crossing is absent in cranked shell modell calculations without pairing. The results indicate, however, that strong dynamic correlations are still present.
- European Physical Journal A 26(2005), 19
Permalink: https://www.hzdr.de/publications/Publ-9844
Experimental investigations for head loss build up at clogged strainers after LOCA
Alt, S.; Hampel, R.; Kästner, W.; Grahn, A.; Krepper, E.
Abstract
During Loss-of-Coolant-Accidents (LOCA) in nuclear reactors insulation materials of pipes and pressure vessels can be released inside of drywells and containments under the impingment forces of steam and water jets. A portion of dislodged fragments of thermal insulation materials would transport to the screens and strainers arranged forwards of Emergency-Core-Cooling-System (ECCS) pumps. Within the German competence network East for nuclear engineering at the University of Applied Sciences Zittau/Görlitz (FH) and the Research Centre Rossendorf (FZR) generic investigations has been carried out for the development and improvement of CFD-models for the analytic simulation of insulation-water-two phase flow based on an experimental generated data basis. This paper presents the description of the test facility Ring line-II and results of separate effect experiments regarding the behaviour of water-insulation fragments flow at a horizontal perforated plate used as strainer in BWR plants with the insulation material MD2-1999.
Keywords: Loss-of-Coolant-Accident; insulation material; Emergency-Core-Cooling-System (ECCS); two-phase flow; strainer clogging; sedimentation; resuspension
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Contribution to proceedings
Annual Meeting on Nuclear Technology 2006, 16.-18.05.2006, Aachen, Germany
CD-ROM
Permalink: https://www.hzdr.de/publications/Publ-9843
The nanostructure evolution during and after magnetron deposition of Au films
Schell, N.; Jensen, T.; Petersen, J. H.; Andreasen, K. P.; Bottiger, J.; Chevallier, J.
Abstract
The evolution of the nanostructure of magnetron sputtered Au films has been experimentally studied. At a synchrotron-radiation beam line, during growth and subsequent annealing, in-situ X-ray diffraction has been carried out to follow the texture, the grain size, the microstrain and lattice-plane distances. With BraggBrentano geometry, only (111) grains, having a (111) plane parallel to the film surface, have been observed, while, with glancing incidence and exit X-ray diffraction, (111)* grains, having one of their (111) planes perpendicular to the film surface, have also been observed. Both during growth and subsequent annealing, the (111) texture changed, and some (111)* grains recrystallized and/or the orientation of the grains changed. The microstrain decreased drastically during the first few minutes of growth (300 A) while, simultaneously, the size of the coherently diffracting domains increased. Subsequently, the microstrain became constant, and the rate of increase of the size of coherently diffracting domains leveled off. Initially, during the first few minutes of annealing, a large decrease in the microstrain was observed simultaneously with a dramatic rise of the size of the coherently diffracting domains. After this initial annealing period, as during film growth, the microstrain became constant, and the rate of increase of the size of coherently diffracting domains leveled off.
The activation energy for the initial growth of the coherent diffracting domains was found to be Q=(0.25 +/- 0.03) eV, and the activation energy for normal grain growth was found to be Q=(0.99 +/- 0.04) eV.
Finally, the thin-film stress was followed during growth and subsequent annealing. A tensile contribution to the stress was observed during island coalescence.
Keywords: Nanocrystalline Au; Nanostructure; In-situ X-ray diffraction; Growth; Magnetron sputtering
-
Lecture (Conference)
MRS Fall Meeting, 01.-05.12.2003, Boston, USA
Permalink: https://www.hzdr.de/publications/Publ-9842
Investigation of steel surfaces treated by a hybrid ion implantation technique
Reuther, H.; Richter, E.; Prokert, F.; Ueda, M.; Beloto, A. F.; Gomes, G. F.
-
Lecture (Conference)
Int. Conf. on the Applications of the Mössbauer Effect, 21.-25.09.2003, Muscat, Oman
Permalink: https://www.hzdr.de/publications/Publ-9841
In-situ GIXRD characterization of the crystallization of Ni-Ti sputtered thin films
Martins, R. M. S.; Silva, R. J. C.; Braz Fernandes, F. M.; Pereira, L.; Gordo, P. R.; Maneira, M. J. P.; Schell, N.
-
Lecture (Conference)
2nd Int. Materials Symposium, 14.-16.04.2003, Campus da Caparica, Portugal
Permalink: https://www.hzdr.de/publications/Publ-9840
Entstehung der chemischen Elemente im Universum
Grosse, E.
-
Lecture (others)
Naturwissenschaften Aktuell der Fakultät Mathematik und Naturwissenschaften, 20.10.2005, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9839
Symmetries in Nuclear Physics
Frauendorf, S.
-
Lecture (others)
6th Nordic Summer School in Nuclear Physics, 08.-19.08.2005, Hillerod, Denmark
Permalink: https://www.hzdr.de/publications/Publ-9838
Investigation of Biological Mechanism by Spectroscopic Methods
Fahmy, K.
-
Lecture (others)
Biozentrum Basel, 01.01.2005, Basel, Switzerland
Permalink: https://www.hzdr.de/publications/Publ-9837
Formation of Uranium(IV) Colloids
Zänker, H.; Opel, K.; Weiß, S.; Hübener, S.; Bernhard, G.
Abstract
Tetravalent uranium is the typical form of uranium in reducing natural waters such as deep groundwaters or waters of the deeper zones of abandoned uranium mines. The colloidal behaviour of uranium(IV) was investigated. Coulometric titrations of strongly acidic U(IV) solutions in HClO4/NaClO4 medium (I = 0.2 M) were carried out in order to find the pH of first colloid formation. Laser-induced breakdown detection (LIBD) was applied for the detection of traces of uranium colloids as the pH was increased. The pH values at the onset of colloid formation were used for thermodynamic calculations aimed at determining the solubility products of crystalline and amorphous uranium dioxide (cf. [1]). Furthermore, the UO2·xH2O(am) colloids were investigated for their colloidal stability. Zeta potentials of ≥ 30 mV were found for pH values of less than 4. The point of zero charge was at pH ~ 6.9. Colloidal suspensions of 10-3 M UO2·xH2O(am) at a pH value of 2.5 proved to be stable over > 1.5 years. The interaction of the forming UO2·xH2O(am) colloids with other colloid-forming species was tested. Therefore, coulometric titrations of U(IV) solutions in the presence of (a) dissolved Al(III) and (b) dissolved silicate were carried out. The presence of Al(III) does not significantly influence the formation of the UO2·xH2O(am) colloids, and the presence of U(IV) does not significantly influence the behaviour of Al(III). There is more interaction of the U(IV) with silicate. Silicate, on the one hand, does not significantly influence the pH value of first UO2·xH2O(am) colloid formation, i.e. it does not significantly influence UO2·xH2O(am) solubility. However, the presence of U(IV) significantly influences the precipitation behaviour of the silicate (formation of U(IV)-Si pseudocolloids due to co-precipitation). The nature of the interaction between the silicate and the U(IV) is not yet known. Adsorption of the silicate onto the UO2·xH2O(am) colloids and/or formation of a coffinite (USiO4) precursor come into question. Measurements by extended X-ray absorption fine structure (EXAFS) spectroscopy with synchrotron radiation to elucidate the local structure around the U(IV) atoms in the pseudocolloids are underway. Reference: [1] Opel K., Weiß S., Hübener S., Zänker H., Bernhard G. Radiochim. Acta, 95 (2007) 143-149.
Keywords: colloids; reducing waters; tetravalent uranium
-
Lecture (Conference)
43. Meeting of the German Colloid Society, 08.-10.10.2007, Mainz, Germany
Permalink: https://www.hzdr.de/publications/Publ-9836
An in-situ grazing incidence X-ray diffraction study of the crystallisation of the crystallisation of Ni-Ti thin films
Braz Fernandes, F. M.; Martins, R.; Silva, R. J. C.; Marques, A.; Martins, R. M. S.; Schell, N.
-
Lecture (Conference)
13th ESRF User Meeting, 12.02.2003, Grenoble, France
Permalink: https://www.hzdr.de/publications/Publ-9834
Universeller Gateway zum Datenaustausch zwischen dem Steuerungssystem der Strahlenquelle ELBE und den Datenaufnahmesystemen der Experimentatoren
Jainsch, R.
Abstract
Software zum Datenaustausch zwischen dem Steuerungssystem der Strahlenquelle ELBE und den Datenaufnahmesystemen der Experimentatoren
-
Lecture (others)
Herbsttagung der Studiengruppe für Elektronische Instrumentierung im FZ Rossendorf, 27.-29.09.2004, Rossendorf, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-9833
Metal island/polymer composite films: novel properties and applications
Oates, T. W. H.
-
Lecture (others)
Group of Macromolecular Physics, Charles University, 10.12.2004, Prague, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-9832
Titanium-based layers prepared by metal plasma immersion ion implantation and deposition as hemocompatible surfaces
Tsyganov, I.; Maitz, M. F.; Richter, E.
-
Lecture (Conference)
5th International Young Scientists Conference on Problems of Optics and High Technology Material Science, 28.-31.10.2004, Kyiv, Ukraine
Permalink: https://www.hzdr.de/publications/Publ-9831
Structure and properties of titanium based coatings prepared by metal plasma immersion ion implantation and deposition
Tsyganov, I.; Maitz, M. F.; Wieser, E.; Richter, E.; Reuther, H.
-
Poster
9 Int. Conf. on Plasma Surface Engineering, 13.-17.09.2004, Garmisch-Partenkirchen, Germany
Permalink: https://www.hzdr.de/publications/Publ-9830
Blood Compatibility of Titanium-Based Coatings Prepared by Metal Plasma Immersion Ion Implantation and Deposition
Tsyganov, I. A.; Maitz, M. F.; Wieser, E.
-
Lecture (Conference)
7th International Conference on Modification of Materials with Particle Beams and Plasma Flows, 25.-29.07.2004, Tomsk, Russia
Permalink: https://www.hzdr.de/publications/Publ-9829
Electrical resistance of ultrathin films determined by in situ spectroscopic ellipsometry
Oates, T. W. H.
-
Lecture (Conference)
5th International Young Scientists Conference, 28.-31.10.2004, Kyiv, Ukraine
Permalink: https://www.hzdr.de/publications/Publ-9828
Optical and electronic properties of ultrathin silver films for biosensor applications
Oates, T. W. H.; Ryves, L.; Bilek, M. M. M.; Mckenzie, D. R.
-
Lecture (Conference)
EMRS Fall meeting, 06.-10.09.2004, Warsaw, Poland
Permalink: https://www.hzdr.de/publications/Publ-9827
Blood compatibility of metal oxide surfaces prepared by metal plasma immersion ion implantation and deposition
Maitz, M. F.; Fitz, T.; Pham, M. T.; Richter, E.
-
Lecture (Conference)
7th World Biomaterials Congress, 17.-21.05.2004, Sydney, Australia
Permalink: https://www.hzdr.de/publications/Publ-9826
Modified NiTi for improved biocompatibility
Maitz, M. F.; Pham, M. T.; Shevchenko, N.
-
Poster
6th Asian Symposium on Biomedical Materials, 19.-22.07.2004, Chengdu, China
Permalink: https://www.hzdr.de/publications/Publ-9825
Combined application of multiple ion energies for simultaneous growth and stress relaxation at thin film deposition
Kolitsch, A.; Abendroth, B.; Gago, R.; Fitz, R.; Möller, W.
-
Invited lecture (Conferences)
ECAART-8 2004, 8th European Conference on Accelerators in Applied Research and Technology, 20.-24.09.2004, Paris, France
Permalink: https://www.hzdr.de/publications/Publ-9824
Application of combined low and high energy ion assistance for film formation and stress relaxation of cBN thin films
Kolitsch, A.; Abendroth, B.; Gago, R.; Fitz, R.; Möller, W.
-
Invited lecture (Conferences)
IV International Symposium Ion Implantation and Other Application of Ions and Electrons ION 2004, 14.-17.04.2004, Kazimierz Dolny, Poland
Permalink: https://www.hzdr.de/publications/Publ-9823
Bonding environment in films deposited from Ar/CH4 and Ar/CH4/N2 ECR discharge: effect of voltage polarization on the growth process
Camero, M.; Gago, R.; Gómez-Aleixandre, C.; Albella, J. M.
-
Poster
PSE2004, 13.-17.09.2004, Garmisch-Partenkirchen, Germany
Permalink: https://www.hzdr.de/publications/Publ-9822
Symmetries in nuclear structure
Frauendorf, S.
Abstract
The symmetries of the rotating mean field and their consequences for rotational bands are discussed. Chirality of rotating triaxial nuclei differs from the chirality of molecules and mass-less particles, because the roles of space inversion and time reversal are exchanged. The experimental consequences of chirality and mass regions where it is expected are discussed. Rotational bands of the predicted shapes with tetrahedral symmetry are ΔI=2 sequences with alternating parity. Breaking of the isospin rotational symmetry by the isovector pair field leads to isorotational bands. The low spin spectra of N=Z nuclei can be explained combining mean-field calculations that take only isovector pairing into account with the concept of isorotational bands. The possible appearance of an isoscalar pair field at high spin would manifest as a pair-rotational band consisting of even-spin states in the even-even and odd-spin states in odd-odd N=Z nuclei.
- Nuclear Physics A 752(2005), 203-212
Permalink: https://www.hzdr.de/publications/Publ-9821
Structural and optical properties of ß-FeSi2 phase prepared by ion beam synthesis
Ayache, R.; Bouabellou, A.; Eichhorn, F.; Richter, E.
-
Poster
E-MRS Fall Meeting, 06.-10.09.2004, Warsaw, Poland
Permalink: https://www.hzdr.de/publications/Publ-9820
Structural and optical properties of ß-FeSi2 phases prepared by ion beam synthesis
Ayache, R.; Bouabellou, A.; Richter, E.
-
Poster
E-MRS Spring Meeting, 24.-28.05.2004, Strasbourg, France
Permalink: https://www.hzdr.de/publications/Publ-9819
Design and synthesis of radiotracers for imaging cyclooxygenase-2(COX-2) expression
Wüst, F.
-
Invited lecture (Conferences)
Seminars on Drug Discovery and Development, 09.05.2007, Zürich, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-9818
Optical characterization of beta-FeSi2 layers formed by ion beam synthesis
Ayache, R.; Bouabellou, A.; Richter, E.
-
Poster
E-MRS Spring Meeting, 24.-28.05.2004, Strasbourg, France
Permalink: https://www.hzdr.de/publications/Publ-9817
Synthesis of 18F-labeled stilbenes from 4-(18F)fluorobenzaldehyde using the Horner-Wadsworth-Emmons reaction
Wüst, F.; Gester, S.; Pietzsch, J.
Abstract
Introduction:
The coupling of phosphonic acid esters with carbonyl compounds, also referred to as the Horner-Wadsworth-Emmons reaction, represents a powerful carbonyl olefination reaction to form C-C double bonds, exhibiting E-configuration exclusively.
This work describes the application of the Horner-Wadsworth-Emmons reaction as novel labeling technique in 18F-chemistry. Various 18F-labeled E-configured stilbenes could be synthesized through the coupling of benzylic phosphonic acid esters with readily available 4-[18F]fluorobenzaldehyde 1 as labeling precursor (Fig. 1).
Experimental:
The carbonyl-olefination reaction was performed via a multi-step/one-pot reaction by the coupling of benzylic phosphonic acid esters (3,5-bis-methoxymethoxybenzyl)-phosphonic acid diethyl ester 2a, (4-methoxymethoxybenzyl)-phosphonic acid diethyl ester 3a and (4-dimethyl-aminobenzyl)phosphonic acid diethyl ester 4a) with 4-[18F]fluorobenzaldehyde to give the corresponding 18F-labeled stilbenes [18F]2b, [18F]3b and [18F]4b exclusively as the expected E-isomers after deprotection. The radiochemical yields ranged from 9 to 22% (based upon [18F]fluoride, including HPLC purification). The specific activity reached up to 90 GBq/μmol.
Results and Discussion:
The reaction can be applied for the synthesis of polyphenolic compounds and aromatic amines bearing an E-configured stilbene backbone as pharmaceutically interesting compounds. Several E-configured stilbene-based polyphenols are known to be potential anticancer compounds. In the case of amine group-containing stilbene compound [18F]4b, structural comparable stilbenes have been reported as potential ligands to bind to Aβ-plaques found in the brain of patients with the neurodegenerative Alzheimer's disease. Preliminary radiopharmacological studies including small animal PET of compound [18F]4b in normal rats showed promising brain uptake. Results on the radiopharmacological characterization of compound [18F]4b will be presented.
Conclusion:
The described method opens a convenient access to a large number of 18F-labeled compounds bearing an E-configured stilbene backbone.
Acknowledgement: The authors wish to thank S. Preusche for radioisotope production and T. Krauss for technical assistance.
Keywords: Stilbenes; [18F]Fluorobenzaldehyde; Horner-Wadsworth-Emmons Reaction
-
Lecture (Conference)
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S54
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9816
Ion-induced stress relaxation during magnetron sputtering deposition of cubic boron nitride thin films
Abendroth, B.; Gago, R.; Eichhorn, F.; Kolitsch, A.; Möller, W.
-
Lecture (Conference)
PSE2004, 13.-17.09.2004, Garmisch-Partenkirchen, Germany
Permalink: https://www.hzdr.de/publications/Publ-9815
On the synthesis of fullerene-like CNx by IBAD: role of film-forming species, ion bombardment and film growth rate
Abrasonis, G.; Gago, R.; Vinnichenko, M.; Mücklich, A.; Kreissig, U.; Kolitsch, A.; Möller, W.
-
Lecture (Conference)
PSE2004, 13.-17.09.2004, Garmisch-Partenkirchen, Germany
Permalink: https://www.hzdr.de/publications/Publ-9814
Organometallic technetium-99m RGD-peptide conjugates with tunable lipophilicity
Künstler, J.-U.; Seidel, G.; Decristoforo, C.; Haubner, R.; Giglio, J.; Leon, E.; Rey, A.; Pietzsch, H.-J.
Abstract
Introduction:
Radiolabeled RGD-peptides have been studied for in vivo targeting of integrin receptors which are over-expressed in carcinomas [1]. The high pharmacological influence of the radiometal complex and limitations of various labelling concepts are reasons for exploring new approaches. The so-called 4+1 mixed-ligand chelate system, [Tc(NS3)(CN-R)], is an interesting alternative due to high labelling efficiency and in vivo stability [2]. Here we present the application of this concept to the labelling of the peptide c(RGDyK).
Experimental:
The figure shows the labelled peptides, corroborated upon coinjection with the corresponding rhenium compounds. The RGD-peptide, serving as monodentate ligand, was functionalized with 4-(isocyanomethyl)benzoic acid (L1) and 4-isocyanobutanoic acid (L2). 99mTc labelling was performed starting from 99mTc-EDTA followed by ligand exchange reaction with a mixture of the appropriate isocyanide-modified peptide and a tetradentate ligand (NS3R). The resulting series of 99mTc peptide conjugates [99mTc(NS3R)(L-c(RGDyK))] with R = R1, R2, R3 and L = L1, L2 was evaluated in biodistribution studies using tumour-bearing mice.
Results and Discussion:
The radiochemical yield was about 60 % after labelling 0.05-0.1 mg of isocyanide-modified peptide. Purification by HPLC resulted in radiochemical purity > 95 %. The stability of the 99mTc conjugates in PBS was higher than 90 % after 24 h. Distribution ratios (logD, octanol/PBS, pH 7.4) covered the range from -0.59 ± 0.14 for [99mTc(NS3R1)(L1-c(RGDyK))] to -3.3 ± 0.2 for [99mTc(NS3R3)(L2-c(RGDyK))]. The compounds exhibited only low tumour uptake and a fast hepatobiliary elimination. Substitution of the tripodal chelator bearing R1 or R2 by the carboxyl group-bearing ligand NS3R3 resulted in a predominant urinary excretion.
Conclusion:
The "4+1" mixed-ligand approach enables the 99mTc-labelling of c(RGDyK). The chelate unit dominates the biodistribution profile which could be influenced by varying the tripodal chelator.
[1] Haubner, R., Wester, H.-J. Curr. Pharm. Design 10 (2004) 1439-1455.
[2] Seifert, S. et al., Bioconjugate Chem. 15 (2004) 856-863.
IAEA, CSIC, FMP-CHLCC, Lab. de vacunas recombinantes, Fac. de Medicina, Uruguay for financial support.
Keywords: Tc '4+1' Complexes; Tc-Labeled Peptide; RGD Peptide; Isocyano-Modified Peptide
-
Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S226
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9813
Determination of In concentration in InGaAs/GaAs epilayers in the early state of anisotropic stress relaxatio
Sass, J.; Mazur, K.; Eichhorn, F.; Strupinski, W.; Turos, A.
-
Lecture (Conference)
Int. Conf. on Experimental and Computing Methods in High Resolution Diffraction Applied for Structure Characterization of Modern Materials, 13.-17.06.2004, Zakopane, Poland
Permalink: https://www.hzdr.de/publications/Publ-9812
Family of Equations of State Based on Lattice QCD: Impact on Flow in Ultrarelativistic Heavy-Ion Collisions
Bluhm, M.; Kämpfer, B.; Schulze, R.; Seipt, D.; Heinz, U.
Abstract
We construct a family of equations of state within a quasiparticle model by relating pressure, energy density, baryon density and susceptibilities adjusted to first-principles lattice QCD calculations. The relation between pressure and energy density from lattice QCD is surprisingly insensitive to details of the simulations. Effects from different lattice actions, quark masses and lattice spacings used in the simulations show up mostly in the quark-hadron phase transition region which we bridge over by a set of interpolations to a hadron resonance gas equation of state. Within our optimized quasiparticle model we then examine the equation of state along isentropic expansion trajectories at small net baryon densities, as relevant for experiments and hydrodynamic simulations at RHIC and LHC energies. We illustrate its impact on azimuthal flow anisotropies and transverse momentum spectra of various hadron species.
-
Physical Review C 76(2007), 034901
DOI: 10.1103/PhysRevC.76.034901
Cited 75 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-9811
Fluorine-18 radiolabeling of S100/calgranulins: a potential approach for characterization of receptors for advanced glycation endproducts in vivo
Hoppmann, S.; Haase, C.; Schwietzke, U.; Wüst, F.; Steinbach, J.; Pietzsch, J.
Abstract
Introduction:
The interaction of S100/calgranulins, a multigenic family of Ca2+-modulated proteins, with receptors for advanced glycation endproducts, e.g., RAGE and AGERs, is hypothesized to be of high relevance in the pathogenesis of various diseases including cardiovascular diseases, inflammatory processes, and cancerogenesis. However, data concerning the role of circulating S100/calgranulins in these pathologies are scarce. Furthermore, it is currently not known whether RAGE or AGERs are universal S100/calgranulin receptors in vivo. One reason for this is the shortage of suitable radiolabeling methods for direct assessment of metabolic pathways of S100/calgranulins in vivo. We report a novel radiotracer approach using radiolabeling of recombinant human S100A1 with fluorine-18 (18F) and the application of 18F-labeled S100A1 (18F-S100A1) in dynamic small animal positron emission tomography (PET) studies in rats.
Experimental:
Human S100A1 was cloned in the bacterial expression vector pGEX-6P-1 and expressed in E. coli strain BL21. Radiolabeling of purified S100A1 was performed by conjugation with N-succinimidyl-4-(18F)fluorobenzoate ([18F]SFB). 18F-S100A1 was used for investigations of stability in vitro and in vivo. The metabolic fate of 18F-S100A1 in rats in vivo was delineated by dynamic PET studies using a dedicated small animal PET system.
Results and Discussion:
Radiolabeling of S100A1 with [18F]SFB at pH 7.4 resulted in 18F-S100A1 specifically labeled at the N-terminal glycine residue with radiochemical yields of 2-6% (decay-corrected) and effective specific activities of 0.5-1 GBq/µmol, respectively. In vitro experiments, and biodistribution and metabolite studies in rats in vivo revealed high stability for the 18F-S100A1. The organ-specific in vivo distribution and kinetics of 18F-S100A1 correlated well with the anatomical localization of receptors for advanced glycation endproducts, e.g., in blood vessels and lungs. In the presence of glycated human low density lipoprotein (glycLDL), a well characterized RAGE ligand, mean plasma residence time of 18F-S100A1 increased by 40% from 29.6±1.5 min to 41.3±2.1 min and lung associated retention of 18F-S100A1 decreased by 57% first indicating circulating S100A1 to be a specific ligand for receptors for advanced glycation endproducts in rats in vivo. Data were compared to former small animal PET studies using the 18F-labeled glycLDL.
Conclusion:
Radiolabeling of S100/calgranulins with 18F and the use of small animal PET provides novel probes to delineate functional expression of RAGE and AGERs under normal and pathophysiological conditions in rodent models of disease in vivo.
Acknowledgement: This study was supported in part by the DFG (grant no. Pi 304/1-1).
Keywords: S100 Proteins; Small Animal PET; Inflammation; Cancerogenesis; Receptors for Advanced Glycation End Products
-
Lecture (Conference)
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S28
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9810
[18F]FBAM and [18F]FBOM: novel prosthetic groups for the mild labeling of thiol group-containing biomacromolecules
Vogler, L.; Berndt, M.; Pietzsch, J.; Wüst, F.
Abstract
Introduction:
The incorporation of 18F into peptides and proteins usually takes advantage of prosthetic groups, also referred to as bifunctional labeling agents. This approach comprises 18F incorporation into a small organic molecule capable of being linked to peptides and proteins under mild conditions. This work deals with a comparative discussion on the synthesis and application of N-[6-(4-[18F]fluorobenzylidene)aminooxyhexyl]-maleimide ([18F]FBAM) and 4-[18F]fluorobenzaldehyde-O-(2-{2-[2-(pyrol-2,5-dion-1-yl)ethoxy]ethoxy}ethyl)oxim ([18F]FBOM) as novel prosthetic groups for the mild and selective conjugation to thiol group-containing biomacromolecules (Fig. 1).
Experimental:
The aminooxy-functionalized labeling precursor for radiosynthesis of [18F]FBAM was prepared in a convenient three-step synthesis sequence in a total yield of 59%. The corresponding labeling precursor for the radiosynthesis of [18F]FBOM succeeded in a four-step reaction sequence in 14% total yield. Formation of the prosthetic groups [18F]FBAM and [18F]FBOM was achieved through condensation reaction with [18F]fluorobenzaldehyde to form the desired oximes in radiochemical yields of 20-30% ([18F]FBAM) and of 14-19% ([18F]FBOM), respectively.
Results and Discussion:
The syntheses were carried out in a remotely-controlled radiofluorination module allowing the convenient and reliable performance of the radiolabeling reactions. The radiochemical purity exceeded 95% and the specific activity ranged from 50 to 80 GBq/µmol. The total synthesis time was 70 to 80 min. The lipophilicity was determined to be logP=2.71 for [18F]FBAM and logP=0.84 for [18F]FBOM. The usefulness of [18F]FBAM and [18F]FBOM as thiol-reactive group prosthetic group was demonstrated by the reaction with glutathion, low density lipoproteins (LDL) and modified neurotensin derivatives. Reaction of [18F]FBAM and [18F]FBOM with glutathione showed that the use of as little as 1 µg/ml glutathione after 30 min provides excellent radiochemical yields of 95% of the desired coupled products. Labeling of LDL showed superior results with [18F]FBAM, whereas comparable results for both prosthetic groups were obtained for the labeling of modified neurotensin derivatives.
Conclusion:
The ease of production and the excellent performance in radiolabeling reactions make compounds [18F]FBAM and [18F]FBOM very promising prosthetic groups for the mild and selective conjugation to thiol group-containing biomacromolecules.
Keywords: Prosthetic Group; 18F-Labeling; Maleimide
-
Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S117
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9809
68Ga-, 86Y- and 111In-radiolabeled anti-tenascin-C oligonucleotide aptamers as a potential probe for tumor imaging
Friebe, M.; Hecht, M.; Borkowski, S.; Seifert, S.; Noll, B.; Wüst, F.; Stephens, A. W.; Hilger, C. S.; Bergmann, R.; Johannsen, B.; Dinkelborg, L. M.
Abstract
Introduction:
The matrix protein tenascin-c (TN-C) represents an interesting target for molecular imaging in oncology due to it´s high abundance in a variety of human tumors such as lung, breast and brain tumors [1]. First radiolabeled anti-TN-C antibodies could successfully proof the concept of tumor-TN-C targeting [2]. However, a persistently high blood level hampers their use for targeted imaging. Aptamers, a class of rapidly clearing high affinity oligonucleotides, have been introduced successfully to molecular imaging by the application of the Tc-99m labeled TN-C Targeting Aptamer-1 (TTA-1) [3]. Here we report on the radiolabeling, binding affinity and biodistribution of this novel targeting aptamer labeled with metal PET isotopes.
Experimental:
Labeling with Ga(III), Y(III), and In(III) was performed in a one pot reaction after conjugation of a DOTA-type chelating moiety to TTA-1-MAG2. In-111 was included in the study as a surrogate for Ga and Y in long term stability and affinity tests. The labeling was carried out in the presence of the aptamer-chelator conjugate and the respective radiometal in acetate buffer. Degradation was investigated in human plasma employing PAGE. Affinity for human TN-C was determined in a nitrous cellulose filter binding assay. Athymic mice, bearing the human U251 tumor cell line, were injected with the radiolabeled TTA-1 derivatives.
Results and Discussion:
Addition of the radiometal salts yielded the respective labeled aptamer conjugates in high yields (60 80 %). Ultrafiltration of the products led to > 95 % of pure material as determined by PAGE and HPLC methods. The biological stability in human plasma ranged from 68 % (In-111) to 95 % (Y-86) of intact material after 6 hr. Binding affinity for human TN-C revealed a KD of 1 nM (In-111). A maximum tumor uptake of 2.0 % ID/g (Ga-68), 1 hr p.i. and T/Non Tumor ratios of 5.1 (T/blood), 0.2 (T/kidney), 0.7 (T/liver) 1 hr p.i. proved to be adequate to image the U251 tumor xenograft in mice. Tumor visualization was possible for both Ga-68 and Y-86 labeled TTA-1.
Conclusion:
The introduction of a DOTA-type chelating moiety could be successfully used to radiolabel the aptamer probe with In, Ga and Y. The stability against nuclease degradation along with a significant tumor accumulation, high T/ blood levels and the imaging capabilities in PET-scans make these compounds promising candidates for further evaluation as multi-tumor imaging agents.
Acknowledgement:
1. R. Chiquet-Ehrismann, Cell 47, 131 (1986)
2. P. Riva, Cancer 73, 1076 (1994)
3. B.J. Hicke, J. Nuc. Med. 47, 668-678 (2006).
Keywords: Aptamers; Oligonucleotides; PET; Ga-68; Tumor Targeting
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Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S387
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9808
Radiolabeling of multimeric neurotensin(8-13) analougues with the short-lived positron emitter fluorine-18
Hultsch, C.; Berndt, M.; Bergmann, R.; Wüst, F.
Abstract
Introduction:
Neurotensin receptors are expressed with high incidence in several human tumour entities. Thus, radiolabeled neurotensin derivatives might be used for tumour targeting. However, its application is limited by insufficient metabolic stability. Metabolic stability might be improved by the synthesis of multimeric peptides.
Experimental:
Three methods for 18F-labeling of dimeric and tetrameric neurotensin(8-13) derivatives were evaluated with respect to the labeling yield and the required peptide amounts.
Results and Discussion:
Labeling using N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) gave low radiochemical yield for the dimeric peptides. Coupling of the tetramer with [18F]SFB was not successful. Furthermore, labeling of aminooxy-functionalized neurotensin(8-13) derivatives using 4-[18F]fluorobenzaldehyde ([18F]FBA) was investigated. High yields of up to 96% were obtained for the dimer whilst coupling of the tetramer only gave low yields of up to 10%.
In contrast to these findings, labelling of sulfhydryl-functionalized neurotensin(8-13) derivatives using the maleinimide 4-[18F]fluorobenzaldehyde O-[6-(2,5-dioxo-2,5-dihydro-pyrrol-1-yl)-hexyl]-oxime ([18F]FBAM) resulted in high radiochemical yields for both, the dimer and the tetramer, being 94% and 40%, respectively. Therefore, [18F]FBAM seems to be the most suitable 18F-labeling agent for multimeric neurotensin(8-13) derivatives. The synthesized 18F-labeled multimeric neurotensin derivatives are depicted in Fig. 1.
Conclusion:
In summary, 18F-radiolabeling of dimeric and tetrameric NT(8-13) derivates was investigated. Suitable results were obtained by labeling of the sulfhydryl-functionalized peptides using [18F]FBAM. Using [18F]SFB or [18F]FBA as the labeling agent gave only low radiochemical yields. Furthermore, labeling of the dimer gave better radiochemical yields than labeling of the tetramer independent from the labeling method which was used. Therefore, the nature of the peptide exhibits a strong influence on the coupling reaction.
Keywords: Neurotensin; Fluorine-18; Tumor Targeting; Multimer
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Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S118
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9807
Synthesis of 18F-labeled neurotensin(8-13) via copper-mediated 1,3-dipolar [3+2]cycloaddition reaction
Wüst, F.; Ramenda, T.; Bergmann, R.
Abstract
Introduction:
Click chemistry is a generic term for a set of reactions, which make use of several selective and modular building blocks to create heteroatom C-X-C links. The copper(I)-catalyzed 1,2,3-triazole formation from azides and terminal acetylenes according to a 1,3-dipolar [3+2]cycloaddition is a particularly powerful linking reaction due to its high degree of specificity and the biocompatibility of the reactants. Recently the first application of click chemistry in 18F chemistry has been reported [1]. Herein we report an alternative click chemistry strategy suitable for 18F labeling reactions.
Experimental:
The labeling strategy was exemplified by the synthesis of 18F-labeled neuropeptide neurotensin NT(8-13) [18F]3 (Fig. 1).
Results and Discussion: 4-[18F]Fluoro-N-(prop-2-ynyl)benzamide [18F]2 as novel terminal alkyne building block was prepared in 90% radiochemical yield by the reaction of readily available N-succinimidyl-4-[18F]fluorobenzoate [18F]SFB with propargyl amine. Purification of [18F]2 was performed by solid phase extraction. Coupling of 18F-labeled terminal alkyne with azide-functionalized NT(8-13) 1 gave the corresponding 18F-labeled NT(8-13) derivative [18F]3 in 66% yield as determined by radio-HPLC. Receptor binding of NT(8-13) derivative [19F]3 was investigated using the human colon adenocarcinoma cell line HT-29. The peptides inhibited the binding of [3H]-NT, showing a typical sigmoid curve. The in vitro binding affinity of NT(8-13) derivative [19F]3 was determined to be 66 nM.
Conclusion:
In summary, the use of [18F]fluoro-N-(prop-2-ynyl)benzamide [18F]2 as suitable click chemistry building block allows the convenient radiolabeling of 18F-labeled small molecular weight compounds as well as peptides as exemplified for the synthesis of 18F-labeled NT(8-13) [18F]3. This offers the application of click chemistry to the synthesis of a broad array of novel 18F-labeled compounds.
References:
[1] J. Marik, J.L. Sutcliffe, Tetrahedron Lett. 47 (2006) 6681-6684.
Keywords: Click Chemistry; 18F-Labeling; PET
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Lecture (Conference)
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S38
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9806
FZD research activities for VVER NPPs
Rindelhardt, U.
Abstract
Within the framework of reactor safety research of the German Federal Ministry of Economics, the scientific-technical cooperation of selected topics with Russian institutions is supported. Some of these topics are performed by the Institute of Safety Research of the Forschungszentrum Dresden-Rossendorf (FZD) together with Russian institutes. The paper summarizes selected results for the following topics:
Contribution to the validation of the Russian thermalhydraulic code KORSAR
Safety analysis for VVER Reactors
3D fluiddynamic calculations
Neutron embrittlement of RPV vessels
Validation of neutron fluence calculations
Post operation investigation of RPV material from Greifswald NPP
Neutron dosimetry of VVER 1000
Keywords: Reactor safety research; VVER
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Invited lecture (Conferences)
Best Practice Seminar COVERS, 20.-22.06.2007, Madrid, Spain
Permalink: https://www.hzdr.de/publications/Publ-9805
The (224) asymmetrical reflection from laterally patterned heteroepitaxial inGaAs/GaAs layers
Mazur, K.; Sass, J.; Eichhorn, F.; Strupinski, W.; Turos, A.; Kowalik, A.
-
Lecture (Conference)
Int. Conf. on Experimental and Computing Methods in High Resolution Diffraction Applied for Structure Characterization of Modern Materials, 13.-17.06.2004, Zakopane, Poland
Permalink: https://www.hzdr.de/publications/Publ-9804
In-situ studies of Ni-Ti thin films
Martins, R. M. S.; Braz Fernandes, F. M.; Silva, R. J. C.; Beckers, M.; Schell, N.
-
Lecture (Conference)
Shape Memory and Superelastic Technology SMST-Europe, 03.-07.10.2004, Baden-Baden, Germany
Permalink: https://www.hzdr.de/publications/Publ-9803
Radiosynthesis and radiopharmacological charakterization of n.c.a. sodium [18f]fluoroacetate in tumor bearing mice
Bergmann, R.; Richter, S.; Wüst, F.
Abstract
Introduction:
[18F]Fluoroacetate is discussed as an alternative to the well-established PET radiotracer [11C]acetate for the diagnosis and treatment monitoring of prostate cancer. The first automated synthesis of [18F]fluoroacetate was reported very recently by Sun and co-workers [1]. Herein we describe an alternative convenient remotely-controlled synthesis of no-carrier-added sodium [18F]fluoroacetate and its radiopharmacological evaluation in tumor bearing mice.
Experimental:
Three ethyl esters and three tert.-butyl esters containing either a methanesulfonyloxy- (OMs), p-toluenesulfonyloxy- (OTs) or p-nitrobenzene-sulfonyloxy (ONs) leaving group were investigated as labeling precursors.
Results and Discussion:
The optimized radiosynthesis of n.c.a. sodium [18F]fluoroacetate was performed in two steps: (1) Incorporation of fluorine into (methanesulfonyloxy)-acetic acid tert.-butyl ester 1 as the superior labeling precursor in acetonitrile at 100°C for 5 min followed by (2) acidic hydrolysis of the resulting [18F]fluoroacetic acid tert.-butyl ester at 100°C for 10 min to afford [18F]fluoroacetic acid. Several consecutive purification steps using anion exchange cartridges (Alltech Maxi-Clean SAX) and Sep-Pak neutral alumina cartridges gave sodium [18F]fluoroacetate in very reproducible radiochemical yields (20-25%, decay-corrected, n=20) in high radiochemical purity (>95%) within 50 min (Fig. 1).
Radiopharmacological studies were performed using rats and tumor bearing mice. Metabolism studies in arterial blood showed no metabolites after 60 min p.i. [18F]Fluoroacetate was readily accumulated in HT-29 tumors (tumor/muscle 1.75 ± 0.20 mean ± SEM, n=6) as shown in small animal PET studies (Fig. 2).
References: [1] L.-Q. Sun et al. Nucl. Med. Biol., 2006, 33, 153-158.
Conclusion:
The robust and reproducible remotely-controlled two step/one pot synthesis of [18F]fluoroacetate starting from readily available (methanesulfonyloxy)-acetic acid tert.-butyl ester 3a as a novel labelling precursor represents an alternative to the published procedures. A comparing discussion of data obtained with [11C]acetate in rats and mice will be presented.
Keywords: 18F-Labeling; [18F]Fluoroacetate
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Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S466
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9802
Synthesis, biodistribution and metabolite analysis of different [86Y]DOTA-L-RNA oligonucleotides in rats
Schlesinger, J.; Koezle, I.; Bergmann, R.; Klussmann, S.; Wüst, F.; Pietzsch, H.-J.; Steinbach, J.
Abstract
Introduction:
Mirror-image oligonucleotides are constructed of an L-configured ribose or deoxyribose. This modification leads to an extraordinary high metabolic stability against enzymatic degradation in biological environments. The radiolabeling of an L-oligonucleotide with the positron emitter 86Y (t1/2 = 14.7 h) is done via the bifunctional chelator approach. The influence of two different [86Y]DOTA chelates on the radiopharmacological properties of [86Y]DOTA-L-oligonucleotides was investigated with an L-RNA 12mer 1 (sequence: 5'-Aminohexyl UGA CUG ACU GAC-3' MW 3975). Both 86Y-labeled L-RNAs 3a, 5a were characterized by a comparative biodistribution study in Wistar rats and metabolite analyses.
Experimental:
The amine functionality of the 5'-hexylamine modified L-RNA 1 was used for conjugations with DOTA-NHS ester 2 and (S)-p-SCN-bz-DOTA 4, accomplished in the formation of a selective amide bond 3 and thiourea bond 5, respectively. After 86Y-labeling of 3 and 5 biodistribution studies were performed for each compound 3a, 5a with eight Wistar rats.
Results and Discussion:
Both DOTA-modified L-RNAs 3, 5 were radiolabeled with 86Y(III) (QSA Global, Germany) with radiochemical yields of 76 % and 85 %, respectively. High renal excretions were found for both 86Y-labeled L-RNAs 3a, 5a whereas differences in the retention were observed for the radiolabeled compounds in the kidneys and the adrenal glands. The standardized uptake value (SUV) of compound 3a in the kidneys reached 10 ± 2.0 after 5 min and decreased to 6.1 ± 0.53 after 60 min. For compound 5a the SUV in the kidneys increased from 13 ± 1.6 after 5 min to 14 ± 1.1 after 60 min. Remarkably high SUVs (3.5 ± 0.48 and 3.2 ± 0.33) were also observed in the adrenal glands after 60 min for both compounds. The SUVs in other organs were below 1.0 after 60 min for 3a and 5a in this study. Over 85% intact 3a and 5a were found in urine samples of Wistar rats 60 min after application of 3a, 5a as confirmed by Radio-HPLC.
Conclusion:
Differences in the kidney excretion profile of 3a and 5a indicate an influence of the different chemical attachments of the [86Y]DOTA chelates to L-RNA 1. The high metabolic stability of the L-RNA suggests the potential of L-oligonucleotides as molecular probes for PET.
Acknowledgement: This work was supported by the EU-FP6 integrated project BioCare contract no.: 505785.
Keywords: 86Y; DOTA; L-RNA; Oligonucleotides
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Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S462
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9801
In-situ X-ray diffraction during sputtering of Shape Memory Alloy (SMA) Ni-Ti thin films
Martins, R. M. S.; Braz Fernandes, F. M.; Silva, R. J. C.; Schell, N.
-
Lecture (Conference)
DPG-Frühjahrstagung, 08.-12.03.2004, Regensburg, Germany
Permalink: https://www.hzdr.de/publications/Publ-9800
Gallium-68 complexes with tripodal NS3 ligands: in vitro and in vivo stability studies
Noll, B.; Schiller, E.; Kraus, W.; Bergmann, R.; Pietzsch, H.-J.
Abstract
Introduction:
We report on formation and structures of 68Ga '4+1' complexes, [Ga(NS3)R], with the tripodal ligand tris(2-mercaptoethyl) amine (NS3) and water or secondary amines as co-ligands (R). To improve the bio-behavior of such compounds new hydrophilic NS3 chelators have been introduced. Challenge experiments with transferrin have been performed to study the influence of the co-ligand on the in vitro stability of the gallium complexes. Their in vivo stability was evaluated in the rat using HSA microspheres.
Experimental:
68Ga was eluted from a 68Ge/68Ga generator (Obninsk, Russia) as GaCl3 in hydrochloric solution (0.1 M) and added to the aqueous solution of the oxalate salt of the NS3 ligand in presence of the corresponding amine. Ga complexes were formed in aqueous solution at ambient temperature. Challenge experiments were carried out at 37°C with the plasma protein transferrin (5 mg/ml), the exchange was controlled by thin layer chromatography on silicagel (Merck) and methanol as eluent.
Results and Discussion:
The labelling procedure with 68Ga generator eluate runs in high yield under weakly alkaline conditions within some minutes. It is not necessary to heat the reaction mixture so that sensitive molecules can also be labelled. Challenge experiments with apotransferrin were carried out for several hours. Amine-coordinated complexes as well as non-amine compounds showed high in vitro stability within 240 minutes. The in vivo stability of the complexes was evaluated in the rat using HSA microspheres. 68Ga-labelled HSA microspheres were completely accumulated in the lung. In small animal PET studies no significant loss of 68Ga activity was observed within three hours.
Conclusion:
The '4+1' mixed-ligand approach enables the 68Ga-labelling of biomolecules under physiological conditions. The lipophilicity of the complexes can be controlled by introducing pharmacological modifiers (e.g. PEG, glucosamine, crown ether) into the tetradentate ligand and/or derivatization of the monodentate ligand. Moreover, the described approach allows the functionalization of a biomolecule with the tripodal as well as with the monodentate ligand.
Keywords: Gallium Complexes; Tripodal Ligand; In Vitro Stability; In Vivo Stability; Tris(2-Mercaptoethyl) Amine
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Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S244
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9799
Experimental hypoxia as a potent stimulus for radiotracer uptake in vitro: comparison of different tumor cells and primary endothelial cells
Treite, F.; Oswald, J.; Mäding, P.; Schwenzer, B.; Bergmann, R.; Pietzsch, J.
Abstract
Introduction:
Hypoxia is a common feature of solid malignant tumors. The vascular endothelial growth factor (VEGF) is upregulated by hypoxia inducible factors (HIFs) as a result of central hypoxia and plays an outstanding role for the formation of new tumoral blood vessels by promoting proliferation and migration of endothelial cells. Beside [18F]fluorodeoxyglucose (18F-FDG) as standard radiotracer for tumor imaging with PET, oxygenation status in experimental and human tumors can be visualized by using [18F]fluoromisonidazole (18F-FMISO).
Experimental:
The aim of our study was the evaluation of the uptake of the radiotracers 18F-FDG and 18F-FMISO under standardized hypoxic conditions in various primary endothelial cells compared with three tumor cell lines in vitro. Experimental hypoxia was characterized by measurement of expression of HIF-1α, VEGF and various VEGF receptors by quantitative real-time PCR.
Results and Discussion:
Experimental hypoxia was confirmed by significant upregulation of characteristic hypoxia-related genes like VEGF in all analyzed primary endothelial cells and the tumor cell lines. VEGF receptors 1, 2 and 3 were almost absent in tumor cells and only expressed in endothelial cells. In contrast, the VEGF co-receptor Neuropilin-1 showed an increased expression in tumor cells under experimental hypoxia. In comparison to normoxic conditions, cellular uptake of 18F-FDG was significantly increased under experimental hypoxia in both tumor and endothelial cells. Otherwise, uptake of 18F-FMISO was always higher in tumor cells than in endothelial cells under hypoxic conditions.
Conclusion:
Our data showed a strong dependence of 18F-FDG uptake on the availability of oxygen in vitro. The study demonstrates relevance of endothelial cells as one important part of the tumor microenvironment under hypoxic conditions. This may have implications when performing PET studies aiming at the visualization and characterization of highly vascularized tumors, in particular, when using 18F-FDG.
Keywords: 18F-FMISO; 18F-FDG; Vascular Endothelial Growth Factor
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Poster
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S421
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9798
In-situ XRD during sputtering of Shape Memory Alloy (SMA) Ni-Ti thin films
Martins, R. M. S.; Braz Fernandes, F. M.; Silva, R. J. C.; Beckers, M.; Schell, N.
-
Lecture (Conference)
14th ESRF User Meeting, 10.-11.02.2004, Grenoble, France -
Lecture (Conference)
ESRF Science Days, 26.-28.05.2004, Aussois, France
Permalink: https://www.hzdr.de/publications/Publ-9797
Short-wavelength (lambda < 4 micrometer) intersubband transitions and quantum cascade lasers in InP-based material systems
Helm, M.
Keywords: quantum cascade laser; infrared
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Lecture (others)
Seminarvortrag am Deptartment of Electrical Engineering, Princeton University, 26.02.2004, Princeton, NJ, USA
Permalink: https://www.hzdr.de/publications/Publ-9796
X-ray grazing incidence diffraction: A tool to optimize focused ion beam implantation
Grenzer, J.; Bischoff, L.; Pietsch, U.
-
Lecture (Conference)
7th Biennial Conf. on High Resolution X-Ray Diffraction and Imaging, 07.-10.09.2004, Prague, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-9795
Silicon light-emitting pn diodes
Helm, M.
Keywords: light emitter; silicon
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Lecture (others)
Seminarvortrag am Department of Electrical Engineering, Princeton University, 11.02.2004, Princeton, NJ, USA
Permalink: https://www.hzdr.de/publications/Publ-9794
Annealing of ITO films: in situ studies of structure and resistance
Cantelli, V.; Rogozin, A.; Shevchenko, N.; Vinnichenko, M.; Prokert, F.; Kolitsch, A.; Möller, W.
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Lecture (Conference)
ESRF Science Days, 26.-28.05.2004, Aussois, France
Permalink: https://www.hzdr.de/publications/Publ-9793
Re-188 complexes with tetradentate S4 ligands derived from MESO-DMSA for labeling of biomolecules
Seifert, S.; Jentschel, C.; Bergmann, R.; Steinbach, J.; Pietzsch, H.-J.
Abstract
Introduction:
Various Tc and Re chelates are currently under investigation for stable labeling of biomolecules. Unfortunately, most of the 188Re chelates degrade more rapidly than the 99mTc analogues which is limiting the further development of rhenium-based therapeutic agents. To overcome this problem, we developed a tetradentate S4 ligands derived from DMSA [1].
Experimental:
Labeling. To a kit vial, containing 5 mg oxalic acid, 5 mg γ-cyclodextrin, 5 mg ascorbic acid and 0.01 - 0.05 mg Sn-S4 complex, 1.0 ml of perrhenate eluate (50500 MBq) was added. After heating at 50 °C for 60' the yield was 90 93% (HPLC and TLC). For stability and biodistribution studies the isomers were separated by semi-preparative HPLC. The identity of the species obtained was confirmed by comparison with the HPLC profiles of fully characterized reference 185/187Re analogues.
Biodistribution: Male Wistar rats (5 6 weeks old), 0.5 ml of the 188Re complex solution (0.5 MBq) was injected into the tail vein under slight ether anesthesia. After the injection, the rats were sacrificed by heart puncture 5 min and 60 min post injection.
Results and Discussion:
A kit formulation was developed which contains only microgram amounts of the S4 ligand stabilized in the form of a stannous complex. Several isomers were separated by HPLC from the preparation solutions and characterized in vitro and in vivo. All of them were absolutely stable in rat and human plasma solutions. Challenge experiments with cysteine corroborated the high inertness of the isomers towards ligand exchange reactions. Samples of blood, intestine and urine of rats confirmed the high in vivo stability of the 188Re complexes. Biodistribution studies resulted in a high uptake and fast clearance from the liver of the more lipophilic cis and trans isomers of complex I (logDo/w 1.5 - 1.7), whereas the hydrophilic isomers of complex II (logDo/w about -1.75) were preferentially excreted via the renal pathway. The low level of radioactivity in the stomach indicated good in vivo stability too.
Conclusion:
The 188Re-S4 complexes offer the possibility of stable and high specific activity labeling of biomolecules. Their charge and lipophilicity may be controled by various possibilities to introduce functional groups. The amine group of the bridging framework makes available a position for coupling biomolecules.
[1] S. Seifert et al., Bioconjugate Chem. 2006, 17, 1601-1606.
Keywords: Rhenium-188 Complexes; Bridged DMSA Ligand; Tetrathiol Ligand; Stability; Radiotherapy
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Lecture (Conference)
17th International Symposium on Radiopharmaceutical Sciences, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S10
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9792
Growth of sputter-deposited Ti1-xAlxN investigated by in-situ x-ray diffraction
Beckers, M.; Schell, N.; Martins, R. M. S.; Möller, W.
-
Lecture (Conference)
Symp. of the Belgium and Dutch Vacuum Society, 09.-10.12.2004, Gent, Belgium
Permalink: https://www.hzdr.de/publications/Publ-9791
86Y-labelled human serum albumin microspheres (DOTA-HSAM): In vivo stability depends on surface structure of the spheres
Schiller, E.; Pietzsch, H.-J.; Bergmann, R.; Pietzsch, J.; Noll, B.; Sterger, A.; Wunderlich, G.
Abstract
Introduction:
Radiolabelled particles are an attractive tool in the therapy of malignancies of the liver. We consider particles manufactured from denatured human serum albumin (HSAM) as useful carriers of therapeutic radionuclides, e.g. Y-90.
Experimental:
Two batches of HSAM (ROTOP Pharmaka GmbH; diameter: 20 30 μm) with smooth or rough surface, as determined by REM, were used for our studies. HSAM were functionalized by coupling DOTA via its isothiocyanate derivative in aqueous solution at pH 8.5 to lysine ε-amino groups on the surface of the spheres. Stability of Y-86 labelled DOTA-HSAM was investigated both in vitro (DTPA challenge) and in vivo (i. v. injection into the tail vein of healthy Wistar rats).
Results and Discussion:
Approximately 25 DOTA molecules per molecule HSA could be attached as estimated from elemental analysis of DOTA-HSAM. Y-86 labelling was performed under optimized conditions in 96 ± 1 % yield. No significant differences between smooth- and rough-surfaced HSAM were found for both, DOTA coupling and Y-86-labelling. In DTPA challenge experiments 98 ± 0 % of the radioactivity were still particle-associated after 24 hours incubation at 37 °C. In the in vivo experiments radiolabelled smooth and rough microspheres were completely trapped in the lungs. After 48 h the two batches differed significantly in their biodistribution pattern. For the clearance of radioactivity from the lungs decay-corrected half-lives of 85 h (rough microspheres) and 187 h (smooth microspheres) were calculated.
Conclusion:
For the preparation of HSA-derived microspheres for radiotherapeutic application smooth-surfaced spheres are superior to rough spheres due to their higher in vivo stability.
-
Poster
17th International Symposium on Radiopharmceutical Scieneces, 30.04.-04.05.2007, Aachen, Deutschland -
Abstract in refereed journal
Journal of Labelled Compounds and Radiopharmaceuticals 50(2007)Suppl. 1, S224
ISSN: 0362-4803
Permalink: https://www.hzdr.de/publications/Publ-9790
Repair kinetics of DNA double strand breaks induced in human mammary epithelial cells
Beyreuther, E.; Dörr, W.; Lessman, E.; Pawelke, J.
Abstract
The introduction of mammography screening programs in some countries initiated a continuous discussion about the benefit or possible accompanied risk of the used radiation qualities. Contributing to this discussion we used different methods, such as clonogenic survival and the analysis of chromosomal aberrations by FISH, to study biological effects with the human mammary epithelial cell line 184A1, which is of interest especially for the induction of breast cancer. Radiation qualities applied were 10 and 25 kV soft X-rays and a 200 kV X-ray tube as reference radiation source. Furthermore, we develop these methods and investigate the repair kinetics of DNA double strand breaks (DSB) with cell line 184A1 to learn more about the underlying processes.
The DNA damage response, following irradiation, includes an efficient DSB recognition system as well as different DSB repair mechanisms. Important contributions to these processes are the phosphorylation of histone H2AX (gH2AX) and the localization and phosphorylation of the p53 binding protein 1 (53BP1) at the sides of DNA DSBs. Both molecules are essential for the recognition of DNA DSBs and hence for the induction of repair processes. Using appropriate antibodies, the phosphorylated molecules can be visualized as nuclear foci and their time-dependent formation can be followed after irradiation.
The time-dependent formation of gH2AX- and 53BP1-foci was used in the present work to investigate the induction and rejoining of DNA DSBs up to 48 hours after irradiation. Two different antibodies were used to visualize and quantify the foci induced by two different doses of 0.25 and 2 Gy of 25 and 200 kV X-rays, respectively.
The kinetics obtained after irradiations with 2 Gy show a similar shape and therefore energy independence for both energies, which can be explained by the same underlying repair processes. Shortly after irradiation the number of foci per cell shows a steep increase, resulting in a maximum after 2 hours and a subsequent 2-phase decrease. Although the position of the maximum is the same, the number of foci per cell differs for 25 kV and 200 kV X-rays, being 7.99 ± 0.12 and 6.19 ± 0.10, respectively. The rejoining of DSBs, deduced by the decrease of number of foci per cell can be divided in a first phase, which seems to be faster, and a slower second one. During the first phase, the number of foci per cell is reduced to about 50 % of the maximum and in the second phase they are reduced to the control level, whereas for 25 kV a significant number of foci per cell remain. These results implicate that, on the one hand, the number of the induced DNA DSBs is significantly higher for 25 kV X-rays and, that on the other hand, some DSBs remain unrepaired. These DSBs can influence the genomic integrity and can result in chromosomal aberrations.
First experiments for the irradiation with 0.25 Gy of 25 kV show the same shape as that with higher dose, but the maximum is derived at 30 minutes after irradiation. The maximum number of foci per cell was 4.03, which is about the half compared to a dose of 2 Gy with the same energy.
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Poster
10th International Wolfsberg Meeting, 12.-14.05.2007, Wolfsberg Conference Center, Ermatingen, Switzerland -
Abstract in refereed journal
Molecular Radiation Biology/Oncology 7(2007)
ISSN: 3980881946 -
Poster
Oncoray, Strategie-Meeting, 08.-09.01.2008, Gröditz, Germany
Permalink: https://www.hzdr.de/publications/Publ-9788
New measurements of physical properties of PbBi alloys
Plevachuk, Y.; Sklyarchuk, V.; Eckert, S.; Gerbeth, G.
Abstract
Lead-bismuth alloys are under intense consideration as target material of spallation sources. The thermohydraulic design of such a target or related coolant systems requires a reliable data basis regarding the temperature dependent physical properties of such alloys. We present new measurements of the electrical conductivity and the thermoelectric power up to about one hundred degree above the melting point for various alloy compositions. For the eutectic alloy the measurements were performed up to a temperature of 1000 K including, in addition, viscosity, thermal conductivity and surface tension. A comparison with data and scaling relations available in literature will be given. New temperature scaling relations will be derived for each of those properties, which we recommend as input for thermohydraulic simulations.
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Lecture (Conference)
IV International Workshop on Materials for HLM cooled Reactors and Related Technologies, 21.-23.05.2007, Rom, Italy
Permalink: https://www.hzdr.de/publications/Publ-9787
Years: 2024 2023 2022 2021 2020 2019 2018 2017 2016
Pages: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.] [351.] [352.] [353.] [354.] [355.]