Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31745 Publications
Impinging jet simulations using a multi-field approach with free surface detection
Hänsch, S.; Lucas, D.; Krepper, E.; Höhne, T.; Danciu, D.-V.;
The calculation of impinging liquid jets and the associated bubble entrainment is a challenging problem in two-fluid model applications. The various mechanisms behind these phenomena are not well understood and a better appreciation of them is vitally important for industrial and scientific issues. The difficulty of simulation arises from the fact that impinging jets show a mixture of both segregated and dispersed flow regimes. Therefore they demand a multi-fluid simulation to capture larger gas structures with resolved interfaces as well as many small bubbles of different sizes that require an averaged treatment. In order to deal with the complexity of these mechanisms a new CMFD-strategy of a generalized two-phase flow (GENTOP) is presented.
Currently, the GENTOP-concept combines a three-field simulation with the recently developed inhomogeneous Multiple Size Group (MUSIG)-approach. The flow is represented by a liquid phase, a polydispersed gas phase, containing different bubble size groups, and a continuous gas phase. Within the MUSIG-framework, transfers between the different bubble size groups due to bubble coalescence and -breakup are described. By modelling an additional mass transfer between the continuous and the polydispersed gas phase, transitions between different gas morphologies can be considered. The continuous gas phase summarizes all gas structures larger than a certain bubble diameter so that for these structures the gas-liquid interfaces are resolved. In order to blend the gaseous morphology basic ideas of the Algebraic Interfacial Area Density (AIAD)-model are used. Generalized formulations for interfacial area density and drag are introduced considering free surfaces within a multi-fluid simulation. This new concept can provide more detailed information about complex flow situations with higher gas fractions such as the impinging jet being just one particular application.
First results computed by the CFD-code CFX 13.0 are compared to experiments carried out at the HZDR and empirical correlations from literature. The flow field is adapted to the experiments considering inlet velocity of the jet v0=1.7m/s, jet length Lj=10mm and jet diameter d0=16mm as well as the dimensions of the water tank. The computational results show good qualitative agreement with the experiments regarding typical continuous and polydispersed gas structures. The values of air entrainment rate and bubble plume length are determined as quantitative values characterizing the results. Further developments consist of new generalized closure models for bubble coalescence and –breakup processes between continuous and dispersed gas phases.
Keywords: turbulent impinging jet, air entrainment, CMFD, gas-liquid interface, MUSIG-model, AIAD-model
  • Contribution to proceedings
    International Symposium on Multiphase Flow and Transport Phenomena, 22.-25.04.2012, Agadir, Marokko
  • Lecture (Conference)
    International Symposium on Multiphase Flow and Transport Phenomena, 22.-25.04.2012, Agadir, Marokko

Publ.-Id: 16805 - Permalink

Status der Protonentherapie auf Basis von Hochintensitätslasern – Erste Dosis-Effekt-Kurven Laser beschleunigter Protonen.
Karsch, L.; Baumann, M.; Beyreuther, E.; Burris-Mog, T.; Kraft, S.; Laschinsky, L.; Metzkes, J.; Naumburger, D.; Oppelt, M.; Richter, C.; Schramm, U.; Schürer, M.; Zeil, K.; Pawelke, J.;
no abstracts available
  • Lecture (Conference)
    17. Jahreskongress der Deutschen Gesellschaft für Radioonkologie, 02.-05.06.2011, Wiesbaden, Deutschland

Publ.-Id: 16803 - Permalink

Dosimetry and biological effectiveness of laser-accelerated particle beams
Karsch, L.; Baumann, M.; Beyreuther, E.; Burris-Mog, T.; Cowan, T.; Dammene, Y.; Enghardt, W.; Laschinsky, L.; Lessmann, E.; Kaluza, M. C.; Kraft, S.; Metzkes, J.; Naumburger, D.; Nicolai, M.; Richter, C.; Sauerbrey, R.; Schlenvoigt, H. P.; Schramm, U.; Schürer, M.; Sobiella, M.; Woithe, J.; Zeil, K.; Pawelke, J.;
Purpose: Before laser particle accelerators can be used for radiation therapy, the supply of stable, reliable and reproducible beams with sufficient particle intensity and useable energy spectra is required. Moreover, consequences on dosimetry as well as on radiobiological effectiveness have to be investigated for laser-accelerated and therefore ultra-shortly pulsed particle beams with very high pulse dose rate.
Method and Materials: In vitro cell irradiations have been established and performed within the German multi-institutional research project onCOOPtics for both laser-accelerated electron and proton beams.
The experimental setups at two lasers, the 10 TW JETI laser for electron and the 150 TW DRACO laser for proton beams, includes a dedicated system for routine cell sample irradiation and precise determination of applied dose. After extensive tuning and optimization of the laser systems and particle beams as well as test and calibration of all dosimetric components, systematic radiobiological experiments with several tumor and normal tissue cell lines have been performed over the last three years measuring dose-effect-curves for cell survival and DNA double strand break induction.
Results: No significant differences in biological effectiveness between laser-accelerated and conventional electron beams were found, apart from one cell line at one end point. The evaluation of the recently finished proton irradiation campaign is in progress.
Conclusion: Laser accelerators can be used for radiobiological experiments, meeting all necessary requirements like homogeneity, stability and precise dose delivery. Nevertheless, before fulfilling the much higher requirements for clinical application, several improvements concerning i.e. proton energy, spectral shaping and patient safety are necessary.
  • Contribution to proceedings
    SPIE Optics and Optoelectronics 2011, 18.-21.04.2011, Prague, Czech Republic
    Proceedings of SPIE Optics and Optoelectronics 2011, 132-133
  • Lecture (Conference)
    Dosimetry and biological effectiveness of laser-accelerated particle beams, 18.-21.04.2011, Prague, Czech Republic

Publ.-Id: 16802 - Permalink

The Energy Dependence of the Electric Dipole Strength in Heavy Nuclei
Junghans, A. R.; Beyer, R.; Grosse, E.; Rusev, G.; Schwengner, R.; Wagner, A.;
We investigate on the basis of new photon scattering measurements and photoneutron and average neutron resonance capture data how well Lorentzians adjusted to photoneutron data in the giant dipole resonances give a good description of the photon strength also below the neutron threshold. If deformation effects are properly taken into account it is verified that down to about 4 MeV for various nuclei with A £¾ 80 the previously employed differentiation between deformed and non-deformed nuclei is no longer necessary.

Publ.-Id: 16801 - Permalink

Stable proton pulses for the measurement of the biological effectiveness of laser accelerated particle beams.
Zeil, K.; Metzkes, J.; Kraft, S.; Cowan, T.; Karsch, L.; Pawelke, J.; Richter, C.; Sauerbrey, R.; Schramm, U.;
The advent of high power laser systems providing pulse rates of a few pulses per minute in the field of laser ion acceleration has brought medical applications such as ion therapy of cancer closer into reach. Although the proton energies are still not high enough for patient treatment, they are sufficient to start first experiments on dosimetry and the biological effectiveness. In contrary to conventional accelerators, the laser ion acceleration delivers proton bunches with a very high charge in short times with a broad energy spectrum. Thus new concepts in dosimetry and irradiation are necessary.
It is evident, that applications with biological material have demanding requirements to the proton energy spectrum and its stability. In this paper we present a robust scheme to provide stable energy spectra for first cell irradiation experiments performed with the Dresden 150 TW laser system DRACO at a dose rate of about 1 Gy/min. A second paper will concentrate on the radiobiological aspects of the experiment and the complex dosimetry issues.
In addition to the production of a reproducible proton spectrum the scheme involves magnetic filtering. Based on a simple non-focusing magnetic dipole equipped with two apertures it makes use of an energy dependent angular asymmetry of the proton spectra and protons with energies above 7 MeV originating from a 2 μm thick Titanium foil are led to the cell sample.
S.D. Kraft, et al., Dose dependent biological damage of tumour cells by laser-accelerated proton beams, New Journal of Physics 12, 085003(2010)
  • Invited lecture (Conferences)
    SPIE Optics and Optoelectronics 2011, 18.-21.04.2011, Prague, Czech Republic
  • Contribution to proceedings
    SPIE Optics and Optoelectronics 2011, 18.-21.04.2011, Prague, Czech Republic
    Proceedings of SPIE Optics and Optoelectronics 2011, 132

Publ.-Id: 16800 - Permalink

Development of a Neutron TOF Facility at KAERI
Song, T.-Y.; Park, S.-H.; Lee, B. C.; Lee, Y.-O.; Junghans, A. R.;
KAERI (Korea Atomic Energy Research Institute) is developing a neutron TOF facility by using KAERI's electron accelerator. KAERI has a superconducting electron accelerator which can produce 17 MeV pulsed electron beams with a pulse width of 20 ps. The pulse current and maximum frequency of the electron accelerator are 20 A and 2 MHz respectively. Fast neutrons can be used for cross-section measurements. A short pulse width can provide a good neutron energy resolution for fast neutrons at relatively short flight lengths. The time resolution related to a neutron source target should be small enough to utilize the short pulse width. We adopted the liquid Pb target which was developed by FDZ (Forschungszentrum Dresden-Rossendorf). The first step of the neutron source development is to simulate a neutron production. MCNPX was used to simulate the neutron production when electron beams irradiate the Pb target. Those simulations were performed by varying beam energies and target sizes to find out optimal variables related to the beam and target. The information of heat deposition in the target was studied by MCNPX since a proper cooling system should be considered to operate the liquid Pb target safely. The thermal-hydraulic analysis was performed based on the result of heat deposition calculation. The study of the detection system is under progress. The design of an experimental hall and a collimator system is also being progressed with the development of the detection system.

Publ.-Id: 16799 - Permalink

Laser particle acceleration for future ion beam therapy
Pawelke, J.;
no abstract available
  • Poster
    Meeting of the Scientific Advisory Board of University Cancer Center Dresden, 13.04.2011, Dresden, Deutschland

Publ.-Id: 16798 - Permalink

Dosimetrie und biologische Wirksamkeit Laser beschleunigter Protonenstrahlen
Karsch, L.; Baumann, M.; Beyreuther, E.; Burris-Mog, T.; Cowan, T.; Dammene, Y.; Enghardt, W.; Laschinsky, L.; Lessmann, E.; Kraft, S.; Metzkes, J.; Naumburger, D.; Richter, C.; Sauerbrey, R.; Schramm, U.; Schürer, M.; Sobiella, M.; Woithe, J.; Pawelke, J.;
Einleitung: Bevor die neue Technologie der Laser Beschleunigung in der Strahlentherapie eingesetzt werden kann, müssen Beschleuniger einen stabilen, steuerbaren Strahl mit genügender Strahlstärke liefern. Ausserdem müssen die entstehenden ultra kurzen, sehr intensiven Strahlpulse auf ihre biologische Wirksamkeit und dosimetrische Erfassung hin untersucht werden.
Methoden: Es wurde ein integriertes Dosimetrie- und Zellbestrahlungssystem (IDOCIS) entwickelt, getestet und umfangreich kalibriert.
Die Kombination verschiedener Dosimeter erlaubt eine präzise Absolutdosimetrie und Strahlüberwachung in Echtzeit. Nach zusätzlicher Modifizierung und Optimierung des 150 TW Lasersystems DRACO (FZD) wurden Zellbestrahlungen mit Laser beschleunigten Protonen durchgeführt.
Ergebnisse: Der Laserbeschleuniger lieferte überWochen einen stabilen und reproduzierbaren Protonenstrahl. Zusammen mit der präzisen dosimetrischen Erfassung mit Hilfe des IDOCIS wurden Dosiseffektkurven bestimmt.
Schlussfolgerung: Vor einem Einsatz Laser beschleunigter Protonen in der Strahlentherapie sind verschiedene Verbesserungen der Lasertechnik und die Durchführung von tierexperimentellen Studien notwendig.
  • Invited lecture (Conferences)
    75th Annual Meeting of the DPG and combined DPG Spring Meeting 2011, Radiation and Medical Physics Division, 13.-18.03.2011, Dresden, Deutschland

Publ.-Id: 16797 - Permalink

Experimental study of fragmentation products in the reactions 112Sn+112Sn and 124Sn+124Sn at 1A GeV
Föhr, V.; Bacquias, A.; Casarejos, E.; Enqvist, T.; Junghans, A. R.; Kelic-Heil, A.; Kurtukian, T.; Lukic, S.; Pérez-Loureiro, D.; Pleskac, R.; Ricciardi, M. V.; Schmidt, K.-H.; Taieb, J.;
Production cross sections and longitudinal velocity distributions of the projectilelike residues produced in the reactions 112Sn+112Sn and 124Sn+124Sn, both at an incident beam energy of 1A GeV, were measured with the high-resolution magnetic spectrometer, the Fragment Separator of GSI. For both reactions the characteristics of the velocity distributions and nuclide production cross sections were determined for residues with atomic number Z≥10. A comparison of the results of the two reactions is presented.

Publ.-Id: 16796 - Permalink

Temperature dependence of the intraexcitonic AC Stark effect in semiconductor quantum wells
Wagner, M.; Teich, M.; Helm, M.; Stehr, D.;
We have investigated the temperature-dependent, intraexcitonic AC Stark effect that manifests itself in a line splitting of the heavy-hole 1s exciton transition in a GaAs/AlGaAs multi quantum well when the 1s-2p intraexciton transition is driven by intense THz light. The observed wavelength-dependent splitting at Helium temperature can still be distinguished at elevated temperatures up to 200 K. Although the thermal energy exceeds the exciton binding energy by a factor of 1.7, thermal exciton ionization influences the coherent nonlinear effect only indirectly via thermal line broadening. With a threefold transmission change on ultrafast timescales in a region accessible to Peltier-cooling the scheme could be promising for optical modulators.
Keywords: quantum well, intraexcitonic AC Stark effect, FEL, THz, temperature-dependent

Publ.-Id: 16795 - Permalink

Towards laser driven proton therapy: Radiobiological experiments.
Pawelke, J.;
no abstract available
  • Invited lecture (Conferences)
    Retreat of the Laser Particle Acceleration Department at the Helmholtz-Zentrum Dresden Rossendorf, 28.02.-01.03.2011, Griess, Österreich

Publ.-Id: 16794 - Permalink

Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment
Numazawa, S.;
This thesis addresses the metal nanocluster growth process on prepatterned substrates, the development of atomistic simulation method with respect to an acceleration of the atomistic transition states, and the continuum model of the ion-beam inducing semiconductor surface pattern formation mechanism.
Experimentally, highly ordered Ag nanocluster structures have been grown on pre-patterned amorphous SiO^2 surfaces by oblique angle physical vapor deposition at room temperature. Despite the small undulation of the rippled surface, the stripe-like Ag nanoclusters are very pronounced, reproducible and well-separated. The first topic is the investigation of this growth process with a continuum theoretical approach to the surface gas condensation as well as an atomistic cluster growth model. The atomistic simulation model is a lattice-based kinetic Monte-Carlo (KMC) method using a combination of a simplified inter-atomic potential and experimental transition barriers taken from the literature.
An effective transition event classification method is introduced which allows a boost factor of several thousand compared to a traditional KMC approach, thus allowing experimental time scales to be modeled. The simulation predicts a low sticking probability for the arriving atoms, millisecond order lifetimes for single Ag monomers and ≈1 nm square surface migration ranges of Ag monomers. The simulations give excellent reproduction of the experimentally observed nanocluster growth patterns.
The second topic specifies the acceleration scheme utilized in the metallic cluster growth model. Concerning the atomistic movements, a classical harmonic transition state theory is considered and applied in discrete lattice cells with hierarchical transition levels. The model results in an effective reduction of KMC simulation steps by utilizing a classification scheme of transition levels for thermally activated atomistic diffusion processes. Thermally activated atomistic movements are considered as local transition events constrained in potential energy wells over certain local time periods. These processes are represented by Markov chains of multi-dimensional Boolean valued functions in three dimensional lattice space. The events inhibited by the barriers under a certain level are regarded as thermal fluctuations of the canonical ensemble and accepted freely. Consequently, the fluctuating system evolution process is implemented as a Markov chain of equivalence class objects. It is shown that the process can be characterized by the acceptance of metastable local transitions. The method is applied to a problem of Au and Ag cluster growth on a rippled surface. The simulation predicts the existence of a morphology dependent transition time limit from a local metastable to stable state for subsequent cluster growth by accretion.
The third topic is the formation of ripple structures on ion bombarded semiconductor surfaces treated in the first topic as the prepatterned substrate of the metallic deposition. This intriguing phenomenon has been known since the 1960's and various theoretical approaches have been explored. These previous models are discussed and a new non-linear model is formulated, based on the local atomic flow and associated density change in the near surface region. Within this framework ripple structures are shown to form without the necessity to invoke surface diffusion or large sputtering as important mechanisms. The model can also be extended to the case where sputtering is important and it is shown that in this case, certain \lq magic' angles can occur at which the ripple patterns are most clearly defined. The results including some analytic solutions of the nonlinear equation of motions are in very good agreement with experimental observation.
Keywords: Nanocluster growth, Kinetic Monte-Carlo, Ion beam surface modification
  • Open Access LogoWissenschaftlich-Technische Berichte / Helmholtz-Zentrum Dresden-Rossendorf; HZDR-021 2012
    ISSN: 2191-8708


Publ.-Id: 16793 - Permalink

Focusing of short-pulse high-intensity laser-accelerated proton beams
Bartal, T.; Foord, M. E.; Bellei, C.; Key, M. H.; Flippo, K. A.; Gaillard, S. A.; Offermann, D. T.; Patel, P. K.; Jarrott, L. C.; Higginson, D. P.; Roth, M.; Otten, A.; Kraus, D.; Stephens, R. B.; Mclean, H. S.; Giraldez, E. M.; Wei, M. S.; Gautier, D. C.; Beg, N.;
Recent progress in generating high-energy (>50 MeV) protons from intense laser–matter interactions (1018–1021Wcm2; refs 1–7) has opened up new areas of research, with applications in radiography8, oncology9, astrophysics10, medical imaging11, high-energy-density physics12–14, and ion-proton beam fast ignition15–19. With the discovery of proton focusing with curved surfaces20,21, rapid advances in these areas will be driven by improved focusing technologies. Here we report on the first investigation of the generation and focusing of a proton beam using a cone-shaped target.We clearly show that the focusing is strongly affected by the electric fields in the beam in both open and enclosed (cone) geometries, bending the trajectories near the axis. Also in the cone geometry, a sheath electric field effectively ‘channels’ the proton beam through the cone tip, substantially improving the beam focusing properties. These results agree well with particle simulations and provide the physics basis for many future applications.

Publ.-Id: 16791 - Permalink

Biologische Wirksamkeit laserbeschleunigter Protonen im Vergleich zu konventionell beschleunigten Protonen.
Oppelt, M.; Beyreuther, E.; Burris-Mog, T.; Kraft, S.; Laschinsky, L.; Leßmann, E.; Metzkes, J.; Schramm, U.; Zeil, K.; Richter, C.;
Strahlentherapie zur Krebsbehandlung nutz ionisierende Strahlung um letale Schäden im Tumor zu applizieren. Aufgrund der Art der Energiedeposition von Protonen in Materie kann dies, vergliechen mit konventioneller Therapie mit Photonen oder Elektronen, wesentlich schonender für umliegendes gesundes Gewebe realisiert werden.
  • Open Access LogoContribution to proceedings
    20. Symposium Experimentelle Strahlentherapie und Klinische Strahlenbiologie, 10.-12.02.2011, Dresden, Deutschland
    Biologische Wirksamkeit laserbeschleunigter Protonen im Vergleich zu konventionell beschleunigten Protonen, ISSN 1432-864, Band 20, 73-77
  • Lecture (Conference)
    20. Symposium Experimentelle Strahlentherapie und Klinische Strahlenbiologie, 10.-12.02.2011, Dresden, Deutschland

Publ.-Id: 16790 - Permalink

Common Interests and Prospective Collaborations:Lawrence Livermore National Laboratory &Helmholtz-Zentrum Dresden-Rossendorf
Cowan, T. E.;
no abstract available
  • Lecture (Conference)
    LLNL Seminar, 24.04.2011, Livermore, USA

Publ.-Id: 16789 - Permalink

R&D Plans II: Helmholtz Activities
Cowan, T. E.;
no abstract available
  • Invited lecture (Conferences)
    EuCARD, EuroNNAc Workshop am CERN, 03.-06.05.2011, Genf, Schweiz

Publ.-Id: 16788 - Permalink

High Performance Radiation Sources at the ELBE Accelerator Facility at the Helmholtz-Zentrum Dresden-Rossendorf
Cowan, T. E.;
no abstract available
  • Invited lecture (Conferences)
    Workshop "The Helmholtz Association and the NRC “Kurchatov Institute”: Prospects & Priorities for an Intensified Strategic Research Co-operation", 24.05.2011, Moskau, Russland

Publ.-Id: 16787 - Permalink

Verification of ion range in moving targets with in-beam PET
Laube, K.; Bert, C.; Fiedler, F.; Helmbrecht, S.; Priegnitz, M.; Saito, N.; Enghardt, W.;
no abstract available
Keywords: in-beam PET, moving targets, ion beam therapy
  • Open Access LogoContribution to external collection
    Katrin Große: GSI Scientific Report 2011, Darmstadt: GSI Helmholtzzentrum für Schwerionenforschung, 2012

Publ.-Id: 16786 - Permalink

Lasergetriebene Protonenbeschleuniger auf dem Weg zur Strahlentherapie.
Beyreuther, E.; Baumann, M.; Burris-Mog, T.; Dammene, Y.; Enghardt, W.; Karsch, L.; Laschinsky, L.; Leßmann, E.; Metzkes, J.; Naumburger, D.; Oppelt, M.; Richter, C.; Schramm, U.; Schürer, M.; Woithe, J.; Zeil, K.; Pawelke, J.;
Parallel zu den Experimenten mit laserbeschleunigten Elektronen wurde das 150 TW Lasersystem DRACO (Dresden laser acceleration source) am Helmholtz-Zentrum Dresden-Rossendorf (HZDR) aufgebaut und in Betrieb genommen. Die im Vergleich zum JETI Lasersystem mehr als zehnfach höhere Laserleistung ermöglicht die Beschleunigung von Protonen bis zu einer Maximalenergie von 20 MeV und damit deren strahlenbiologische Charakterisierung in vitro (3,4). Die für die Bestimmung von Dosis-Effekt-Kurven am laserbeschleunigten Protonenstrahl zu erfüllenden Anforderungen, sowie deren Realisierung werden zusammen mit ersten strahlenbiologischen Ergebnissen sowie einem Ausblick auf die weitere Entwicklung im Beitrag präsentiert.
  • Open Access LogoContribution to proceedings
    20. Symposium Experimentelle Strahlentherapie und Klinische Strahlenbiologie, 10.-12.02.2011, Dresden, Deutschland
    Experimentelle Strahlentherapie und Klinische Strahlenbiologie, 1432-864X
  • Invited lecture (Conferences)
    20. Symposium Experimentelle Strahlentherapie und Klinische Strahlenbiologie, Dresden, 10.-12.02.2011, Dresden, Deutschland

Publ.-Id: 16785 - Permalink

Laser driven accelerators for proton therapy: Physical, technological and radiobiological aspects.
Pawelke, J.;
no abstract available
  • Invited lecture (Conferences)
    26th Conference on Clinical and Experimental Research in Radiation Oncology (CERRO 26), 15.-22.01.2011, Menuires, France

Publ.-Id: 16783 - Permalink

Research group laser-radiooncology
Pawelke, J.;
no abstract available
  • Invited lecture (Conferences)
    OncoRay Retreat, 12.-13.01.2011, Riesa, Deutschland

Publ.-Id: 16782 - Permalink

Eine Compton-Kamera für die in-vivo Dosimetrie bei der Partikeltherapie
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    Tagung des Wissenschaftlichen Beirates des HZDR, 23.11.2011, Dresden, Deutschland

Publ.-Id: 16781 - Permalink

Physics and instrumentation needs for improving hadron therapy
Enghardt, W.;
no abstract available
  • Invited lecture (Conferences)
    Workshop: Hadrontherapy in France, 28.-29.11.2011, Lyon, France

Publ.-Id: 16780 - Permalink

A historical perspective of Gerhard Kraft’s scientific achievements: The therapy project
Enghardt, W.;
kein Abstract verfügbar
  • Invited lecture (Conferences)
    Festkolloquium anlässlich des 70. Geburtstages von Gerhard Kraft, 01.11.2011, Darmstadt, Deutschland

Publ.-Id: 16779 - Permalink

Die Technologieplattform für translationale Forschung in der Protonentherapie am OncoRay Dresden
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    3 Ländertagung der ÖGMP, DGMP und SGSMP, 30.09.2011, Wien, Österreich

Publ.-Id: 16778 - Permalink

DiscussionProffered Papers: OncotechnologyThe impact of novel information processing to health care
Enghardt, W.;
no abstract available
  • Invited lecture (Conferences)
    2011 European Multidisciplinary Cancer Congress, 26.09.2011, Stockholm, Schweden

Publ.-Id: 16777 - Permalink

Laser Accelerated Proton Therapy
Enghardt, W.;
no abstract available
  • Invited lecture (Conferences)
    2011 European Multidisciplinary Cancer Congress, 26.09.2011, Stockholm, Schweden

Publ.-Id: 16776 - Permalink

The Future Proton Irradiation Facility at OncoRay Dresden
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    Enlight Annual Meeting 2011, 03.09.2011, Marburg, Deutschland

Publ.-Id: 16775 - Permalink

ENVISIONEuropean NoVel Imaging Systems for ION therapy
Enghardt, W.;
kein Abstract verfügbar
  • Invited lecture (Conferences)
    Enlight Annual Meeting 2011, 03.09.2011, Marburg, Deutschland

Publ.-Id: 16774 - Permalink

Future Proton Irradiation Facility at OncoRay
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    Seminar am Institut für Kern- und Teilchenphysik, 14.07.2011, Dresden, Deutschland

Publ.-Id: 16773 - Permalink

Laser beschleunigte Protonenstrahlen
Enghardt, W.;
Kompakte Protonen- und Ionenbeschleuniger
Physik der Laserbeschleunigung
Stand von Forschung und Entwicklung
  • Lecture (others)
    Weiterbildung Klinik und Poliklinik für Strahlentherapie und Radioonkologie Universitätsklinikum C.G. Carus Dresden, 05.07.2011, Dresden, Deutschland

Publ.-Id: 16772 - Permalink

A Technology Platform for Translational Researchon Laser Driven Particle Acceleratorsfor Radiotherapy
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (Conference)
    SPIE Optics+Optoelectronics, 21.04.2011, Prag, Tschechische Republik

Publ.-Id: 16771 - Permalink

Erfolgreich gegen Krebs: Präzisionsbestrahlung und mathematische Zellmodellierung
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (Conference)
    Helmholtz-Humboldt-Sonntagsvorlesung, 10.04.2011, Berlin, Deutschland

Publ.-Id: 16770 - Permalink

Das Nationale Zentrum für Strahlenforschung in der Onkologie - OncoRay, Dresden
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    23. Weiterbildungsveranstaltung Mitteldeutscher Medizinphysiker, 08.-09.04.2011, Dresden, Deutschland

Publ.-Id: 16769 - Permalink

ENVISION Report on WP3 In-beam single particle tomography
Enghardt, W.;
no abstract available
  • Lecture (others)
    ENVISION Annual Meeting, 04.02.2011, Lyon, Frankreich

Publ.-Id: 16768 - Permalink

Structural Study on 2,2′-(Methylimino)bis(N,N-Dioctylacetamide) Complex with Re(VII)O4- and Tc(VII)O4- by 1H NMR, EXAFS, and IR Spectroscopy
Saeki, M.; Sasaki, Y.; Nakai, A.; Ohashi, A.; Banerjee, D.; Scheinost, A. C.; Foerstendorf, H.;
The structures of the complex of 2,2'-(methylimino)bis(N,N-dioctylacetamide) (MIDOA) with M-(VII)O-4(-) (M = Re and Tc), which were prepared by liquid-liquid solvent extraction, were investigated by using H-1 nuclear magnetic resonance (NMR), extended X-ray absorption fine structure (EXAFS), and infrared (IR) spectroscopy. The H-1 NMR spectra of the complex of MIDOA with Re(VII)O-4(-) prepared in the organic solution suggest the transfer of a proton from aqueous to organic solution and the formation of the H(+)MIDOA ion. The EXAFS spectra of the complexes of H(+)MIDOA with Re(VII)O-4(-) and Tc(VII)O-4(-) show only the M-O coordination of the aquo complexes, suggesting that the chemical state of M(VII)O-4(-) was unchanged during the extraction process. The results from H-1 NMR and EXAFS, therefore, provide evidence of M(VII)O-4(-)center dot center dot center dot H(+)MIDOA complex formation in the organic solution. The IR spectra of Re(VII)O-4(-)center dot center dot center do!
t H(+)MIDOA and Tc(VII)O-4(-)center dot center dot center dot H(+)MIDOA were analyzed based on the structures and the IR spectra that were calculated at the B3LYP/cc-pVDZ level. Comparison of the observed and calculated IR spectra demonstrates that an intramolecular hydrogen bond is formed in H(+)MIDOA, and the M(VII)O-4(-) ion interacts with H(+)MIDOA through multiple C-H-n center dot center dot center dot O hydrogen bonds.
Keywords: liquid-liquid solvent extraction, solvent extraction process, Complexation, DFT

Publ.-Id: 16767 - Permalink

Laser driven proton accelerators on the way to application in cancer therapy?
Enghardt, W.;
no abstract available
  • Lecture (others)
    470. WE-Heraeus-Seminar, 15.12.2010, Bad Honnef, Deutschland
  • Lecture (Conference)
    Seminar am Kernfysisch Versneller Instituut, 28.01.2011, Groningen, Niederland

Publ.-Id: 16766 - Permalink

Neue Strahlenarten in der Radioonkologie:Übersicht und Bewertung
Enghardt, W.;
1. Physikalische Eigenschaften von Ionenstrahlen
2. Bestrahlungsfeld-Formierung für Ionenstrahlen
3. Kernreaktionen
4. Exotische Strahlen
  • Lecture (others)
    Strahlenschutz und Qualitätssicherung, 26.-27.11.2010, Dresden, Deutschland

Publ.-Id: 16765 - Permalink

Das Dresdener Protonenprojekt
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    Fachgespräch im Sächsischen Staatsministerium für Umwelt und Landwirtschaft, 25.11.2010, Dresden, Deutschland

Publ.-Id: 16764 - Permalink

Image based in-vivo dosimetry for proton and ion tumour therapy
Enghardt, W.;
no abstract available
  • Lecture (Conference)
    Physikalisches Kolloquium, 12.11.2010, Bonn, Deutschland

Publ.-Id: 16763 - Permalink

Neue Entwicklungen in der Strahlentherapie
Enghardt, W.;
kein Abstract verfügbar
  • Lecture (others)
    15. Strahlenschutzseminar der Staatlichen Fortbildungsstätte Reinhardtsgrimma, 11.-12.11.2010, Reinhardtgrimma, Deutschland

Publ.-Id: 16762 - Permalink

Technologie für die Radiotherapie
Enghardt, W.;
1.Die Wechselwirkung ionisierender Strahlung mit (belebter) Materie
2.Die Formen der Strahlentherapie
3.Exkurs in die Radionuklid- und Brachytherapie
4.1. Die Erzeugung von Photonen- und Elektronenstrahlen für
die Strahlentherapie (Elektronen-Linearbeschleuniger)
4.2. Ionenstrahl-Therapie
4.3. Adaptive Strahlentherapie
  • Lecture (others)
    Vorlesungen, 28.06.2010, Dresden, Deutschland

Publ.-Id: 16761 - Permalink

Moderne Technologie für die Strahlentherapie von Tumoren
Enghardt, W.;
1. Die Wechselwirkung ionisierender Strahlung mit (belebter) Materie
2. Moderne strahlentherapeutische Techniken
3. Photonen- und Elektronenstrahlen für die Therapie
4. Ionenstrahl-Therapie
5. Adaptive Strahlentherapie
  • Lecture (others)
    Fakultät Maschinenwesen, 25.05.2010, Dresden, Deutschland

Publ.-Id: 16760 - Permalink

Medical Radiation Sciences
Enghardt, W.;
kein Abstract verfügbar
  • Invited lecture (Conferences)
    Sitzung des Fachausschusses Strahlenschutz des Länderausschusses für Atomkernenergie, 18.02.2010, Bonn, Deutschland

Publ.-Id: 16759 - Permalink

Prospects in Medical Imaging - Summary
Enghardt, W.;
no abstract available
  • Invited lecture (Conferences)
    Workshop "Physics for Health in Europe", 02.-04.02.2010, Genf, Schweiz

Publ.-Id: 16758 - Permalink

Helmholtz Beamline at the European XFEL
Cowan, T. E.;
Kein Abstract vorhanden
  • Lecture (others)
    European XFEL Science Advisory Committee, 29.09.2011, Hamburg, Deutschland
  • Invited lecture (Conferences)
    Workshop on Petawatt-Lasers at Hard X-ray Light Sources, 05.-09.09.2011, Dresden, Deutschland

Publ.-Id: 16757 - Permalink

Prospects for Laser-Driven Ion Beam Therapy
Cowan, T. E.;
Kein Abstract vorhanden
  • Lecture (Conference)
    OSA Frontiers in Optics 2011, 16.-20.10.2011, San Jose, USA

Publ.-Id: 16756 - Permalink

Laser-acceleration of ions and their potential for Radiation Therapy
Cowan, T. E.;
Kein Abstrakt vorhanden
  • Lecture (Conference)
    Light at Extreme Intensities 2011, 14.-18.11.2011, Szeged, Ungarn

Publ.-Id: 16755 - Permalink

Helmholtz Beamlines
Cowan, T. E.;
Kein Abstract vorhanden
  • Invited lecture (Conferences)
    LAALA 2011 Sino-German Symposium on Laser Acceleration and Applications of Lasers at Accelerators, 05.-08.12.2011, Beijing, China

Publ.-Id: 16754 - Permalink

Multi-scale thermalhydraulic analyses performed in NURESIM and NURISP projects
Bestion, D.; Lucas, D.; Anglart, H.; Niceno, B.; Vyskocil, L.;
The NURESIM and NURISP successive projects of the 6th and 7th European Framework Programs joined the efforts of 21 partners for developing and validating a reference multi-physics and multi-scale platform for reactor simulation. The platform includes system codes, component codes, and also CFD or CMFD simulation tools. Fine scale CFD simulations are useful for a better understanding of physical processes, for the prediction of small scale geometrical effects and for solving problems that require a fine space and/or time resolution. Many important safety issues usually treated at the system scale may now benefit from investigations at a CFD scale. The Pressurized Thermal Shock is investigated using several simulation scales including Direct Numerical Simulation, Large Eddy Simulation, Very Large Eddy Simulation and RANS approaches. At the end a coupling of system code and CFD is applied. Condensation Induced Water-Hammer was also investigated at both CFD and 1-D scale. Boiling flow in a reactor core up to Departure from Nucleate Boiling or Dry-Out is investigated at scales much smaller than the classical sub-channel analysis codes. DNS was used to investigate very local processes whereas CFD in both RANS and LES was used to simulate bubbly flow and Euler-Lagrange simulations were used for annular mist flow investigations. Loss of Coolant Accidents are usually treated by system codes. Some related issues are now revisited at the CFD scale. In each case the progress of the analysis is summarized and the benefit of the multi-scale approach is shown.
Keywords: CFD, simulation, PTS, CHF, Reflooding, water hammer
  • Contribution to proceedings
    20th International Conference on Nuclear Engineering, ICONE20, 30.07.-02.08.2012, Anaheim, USA

Publ.-Id: 16753 - Permalink

Opportunities for Compression Science with the Helmholtz Beamline at the European XFEL
Cowan, T. E.;
  • Invited lecture (Conferences)
    Dynamic Compression Sector, DCS @ APS Workshop, 19.-20.01.2012, Argonne, USA

Publ.-Id: 16752 - Permalink

Hollow Beam creation with continuous diffractive phase mask at PHELIX
Brabetz, C.; Eisenbarth, U.; Kester, O.; Stoehlker, T.; Cowan, T. E.; Zielbauer, B.; Bagnoud, V.;
We propose and demonstrate a method for shaping the focus of high intensity lasers into an annular or “donut” mode. The method, based on helical phase plates, has been implemented at the PHELIX laser facility.
  • Contribution to proceedings
    CLEO 2012, 08.-10.05.2012, San Jose, USA

Publ.-Id: 16751 - Permalink

Influence of the copper impurity level on the irradiation response of reactor pressure vessel steels investigated by SANS
Wagner, A.; Ulbricht, A.; Bergner, F.; Altstadt, E.;
Reactor pressure vessel (RPV) steel, when exposed to neutron irradiation, induces the formation of nano-sized features. Using small angle neutron scattering (SANS) we have studied the neutron fluence dependence of the precipitate volume fraction for high-Cu and low-Cu materials separately. Cu-rich precipitates have long been recognized to play the dominant role in embrittlement of Cu-bearing RPV steels. In contrast, Mn-Ni-rich precipitates seem to govern embrittlement in the case of low levels of impurity Cu. The objective is to work out the resulting differences from the microstructural point of view. For low-Cu materials, the volume fraction was found to be within the detection limit of SANS at fluences below an apparent threshold fluence, whereas the slope increases considerably beyond. The relationship between irradiation-induced yield stress increase and precipitate volume fraction was also considered. We have derived estimates of the obstacle strength for Cu-rich precipitates and for Mn-Ni-rich precipitates.
Keywords: Neutron irradiation; Irradiation hardening; Iron base alloy; Reactor pressure vessel steel; Cu impurity; SANS; Microstructure

Publ.-Id: 16750 - Permalink

Stopping power dependence of nitrogen sputtering yields in copper nitride films under swift-ion irradiation: exciton model approach
Gordillo, N.; González-Arrabal, R.; Rivera, A.; Munnik, F.; Agulló-López, F.;
Nitrogen sputtering yields as high as 2×103 N / ion are obtained by irradiating N-rich-Cu3N films (N concentration (33±2) at.%) with Cu ions at energies in the range 10-42 MeV. The kinetics of N sputtering as a function of ion fluence is determined at several energies (stopping powers) for films deposited on both, glass and silicon substrates. The kinetic curves show a three stage-behaviour: an initial inhibition stage I of low sputtering yield, followed by a more extended linear region II that finally reaches a saturation stage III at a low remaining nitrogen fraction (5-10 %). For the case of silicon substrates the contribution of the initial stage is not significant. The sputtering rate of stage II is found to be independent of the substrate and to linearly increase with electronic stopping power (Se). A Se threshold for nitrogen depletion of ~3.4 keV/nm is estimated. Experimental kinetic data are successfully analysed within the bulk molecular recombination model. All features are in accordance with electronic excitation mechanisms, showing for the first time evidence of the excitonic model.
Keywords: Copper nitride, ion beam modification of materials, swift heavy ion irradiation, electronic sputtering

Publ.-Id: 16749 - Permalink

Atomic Layer Deposition of Aluminum and Titanium Phosphates
Hämäläinen, J.; Holopainen, J.; Munnik, F.; Heikkilä, M.; Ritala, M.; Leskelä, M.;
The atomic layer deposition (ALD) of phosphate containing thin films using reactions between metal halide and phosphorus source without any additional oxygen sources was examined. Two very common metal halides, AlCl3 and TiCl4, were used in conjunction with trimethyl phosphate (TMPO) to grow corresponding metal phosphate films. Aluminum phosphate thin films were deposited at temperatures between 150 and 400 °C while titanium phosphate films grew between 275 and 450 °C. Amorphous films of Al2.6PO7.0 and Al1.6PO5.6 were deposited at 200 and 300 °C, respectively, while the amorphous titanium phosphate films deposited at 300 and 400 °C consisted of Ti0.8PO3.9 and Ti0.6PO3.5 (Ti1.2P2O7). The films were analyzed using high temperature XRD to study the crystallization and stability of the deposited films. Also the surface morphology of the annealed films was examined by FESEM.

Publ.-Id: 16748 - Permalink

Lithium Phosphate Thin Films Grown by Atomic Layer Deposition
Hämäläinen, J.; Holopainen, J.; Munnik, F.; Hatanpää, T.; Heikkilä, M.; Ritala, M.; Leskelä, M.;
Lithiumphosphate, Li3PO4, has been considered a potential electrolytematerial for lithiumion batteries and CO2 sensors in particular if the films can be made dense and of high quality already at low thickness. In this work, Li3PO4 thin films were deposited by atomic layer deposition (ALD) between 225 and 350°C using trimethyl phosphate and either of the two lithium sources, namely lithium hexamethyldisilazide or lithium tert-butoxide. The deposited films showed slightly crystalline Li3PO4 structure in X-ray diffraction and the elastic recoil detection analysis confirmed this stoichiometry with some carbon and hydrogen impurities. The crystallinity and thermal stability of the films at elevated temperatures in N2 were also examined. The long term stability of the deposited Li3PO4 films under ambient air may be an issue for the applicability of these processes.

Publ.-Id: 16747 - Permalink

Radiation field characterization and shielding studies for the ELI Beamlines Facility
Ferrari, A.; Amato, E.; Margarone, D.; Cowan, T.; Rus, B.;
The ELI (Extreme Light Infrastructure) Beamlines Facility in the Czech Republic, which is planned to complete the installation in 2015, is one of the four pillars of the ELI european project. Several laser beamlines with ultrahigh intensities and ultrashort pulses are foreseen, offering versatile radiation sources in an unprecedented energy range: laser-driven particle beams are expected to range between 1 GeV and 50 GeV for electrons and from 100 MeV up to 3 GeV for protons. The number of particles delivered per laser shot is estimated to be 109-1010 for the electron beams and 1010-1012 for the proton beams.
The high energy and current values of the produced particles, together with the potentiality to operate at 10 Hz laser repetition rate, require an accurate study of the primary and secondary radiation fields to optimize appropriate shielding solutions: this is a key issue to minimize prompt and residual doses in order to protect the personnel, reduce the radiation damage of electronic devices and avoid strong limitations in the operational time.
A general shielding study for the 10 PW (0.016 Hz) and 2 PW (10 Hz) laser beamlines is presented here. Starting from analytical calculations, as well as from dedicated simulations, the main electron and proton fields produced in the laser-matter interaction have been described and used to characterize the "source terms" in full simulations with the Monte Carlo code FLUKA. The secondary radiation fields have been then analyzed to assess a proper shielding. The results of this study and the proposed solutions for the beam dumps of the high energy beamlines are presented, together with a cross-check analysis performed with the Monte Carlo code GEANT4.
Keywords: particle acceleration from laser-matter interaction, shielding, Monte Carlo, radiation protection
  • Lecture (Conference)
    Plasma Production by Laser Ablation (PPLA 2011), 21.-23.09.2011, Catania, Italia

Publ.-Id: 16746 - Permalink

Hysteretic anomalous Hall effect in a Mn-rich, amorphous Ge:Mn nanonet
Bürger, D.; Zhou, S.; Höwler, M.; Ou, X.; Kovacs, G. J.; Reuther, H.; Mücklich, A.; Skorupa, W.; Helm, M.; Schmidt, H.;
In a previous work [1], we fabricated ferromagnetic Ge:Mn by Mn ion implantation and pulsed laser annealing (PLA) and observed hysteretic Hall resistance below 10 K. By applying different PLA conditions we fabricated a percolating, Mn-rich, amorphous Ge:Mn nano-network with hysteretic Hall resistance up to 30K. This nano-network is embedded in crystalline Ge:Mn between 5 nm and 40 nm under the sample surface.
We applied chemical and physical etching to confirm the contribution of the nano-network to the magnetic properties. The nano-network has a significant influence on the correlation between magnetism and anomalous Hall resistance. In the future such nano-networks may be used to spin-polarize free charge carriers in semiconductors at room temperature.
[1] S. Zhou et al., Phys. Rev. B 81, 165204 (2010)
Keywords: pulsed laser annealing, instability, GeMn
  • Poster
    IFW Winterschool, 15.-18.01.2012, Oberwiesenthal, Deutschland

Publ.-Id: 16745 - Permalink

From ore to concentrate -a systematic geometallurgical study on the Cavanacaw Au Deposit, Northern Ireland
Birtel, S.; Wunderlich, I.; Gutzmer, J.;
A systematic geometallurgical assessment was carried out to follow changes of mineralogical composition and microfabric following the ore extracted from a single mined block extracted at the Cavanacaw Au Mine from the open pit (in situ ore) through the entire beneficiation process. SEM-based image analyses was used as major analytical tool to carry out the investigation on the finely disseminated Au ores. First of all no Au was found in the tailings, the beneficiation plant recovers the bulk of the sulfides and electrum to the concentrate, and finally Au liberation is good. Despite of these positive assesment results illustrate, there are still some losses that appear to be systemic. In particular, large electrum grains (>60 µm) that are abundant in the original uncrushed material only make a minor contribution to the final concentrate. Due to the ductile behaviour of electrum, fracturing of larger electrum grains into smaller grain sizes appears unlikely – it is thus suspected that these larger particles may be lost during processing.
Furthermore, our results clearly reveal that narrow high grade and sulphide-rich veins are higher in gold grade than the final flotation concentrate. This results from processing a mixture of high grade ore and partly mineralised wall rock. To reduce processing costs it should thus be considered to introduce optical sorting to separate the high-grade vein from lower grade mineralised wall rock. Such pre-selection may further improve recovery
Keywords: geometallurgy, in-situ analyses, hydrothermal Au deposit
  • Lecture (Conference)
    Conference in Minerals Engineering 2012, 07.-08.02.2012, Luleaa, Schweden
  • Contribution to proceedings
    Conference in Minerals Engineering, 07.-08.02.2012, Luleaa, Sweden
    Luleaa Reprints 2012, 41-49

Publ.-Id: 16744 - Permalink

Irradiation of a Thorium-Plutonium Rodlet: Experiment and Benchmark Calculations
Insulander-Björk, K.; Mittag, S.; Nabbi, R.; Rineiski, A.; Schitthelm, O.; Vezzoni, B.;
A benchmark exercise for thorium-plutionium fuel, based on experimental data, has been carried out. A thoriumplutonium oxide fuel rodlet was irradiated in a PWR for four consecutive cycles, to a burnup of about 37MWd/kgHM.
During the irradiation, the rodlet was inserted into a guide tube of a standardMOX fuel assembly. After the irradiation, the rod was subjected to several PIE measurements, including radiochemical analysis. Element concentrations and radial distributions in the rodlet, multiplication factors and distributions within the carrier assembly of burnup and power were calculated. Four participants in the study simulated the irradiation of the MOX fuel assemblies including the thorium-plutonium rodlet using their respective code systems; MCBurn, HELIOS, CASMO-5 and ECCO/ERANOS combined with TRAIN. The results of the simulations and the measured results of the radiochemical analysis were compared and found to be in fairly good agreement when the calculated results were calibrated to give the same burnup of the thorium-plutonium rodlet as that experimentally measured. Average concentrations of several minor actinides and fission products were well reproduced by all codes, to the extent that can be expected based on known uncertainties in the experimental setup and the cross section libraries. Calculated results which could not be confirmed by experimental measurement were compared and only two significant anomalies were found, which can probably be addressed by limited modifications of the codes.
Keywords: Thorium, plutonium, benchmark, experiment, simulation, LWR

Publ.-Id: 16743 - Permalink

Separation of a potential VAChT radioligand from its nitro precursor - an HPLC study for optimization of F-18-radiosynthesis
Wenzel, B.; Fischer, S.; Hiller, A.; Brust, P.; Steinbach, J.;
1. Introduction
The F-18-benzoyl group is a useful functionality for the development of PET-radiotracers in order to introduce F-18 in a simple one step radiosynthesis. Since nitro leaving groups are common for the nucleophilic F-18-substitution, we utilized a nitro precursor for F-18-labeling of a vesamicol analog to evaluate it as new radioligand for the vesicular acetylcholine transporter (VAChT), which is an interesting target for imaging of presynaptic cholinergic deficiencies using PET.
The separation of a F-18-labeled compound from its nitro precursor in the radiosynthesis is often challenging, accordingly we firstly used the approach of reduction of the remaining nitro precursor to its amine, because this amine is normally easier to isolate from the radiotracer by semi-preparative HPLC than the nitro precursor itself. However, in order to avoid this additional step during the radiosynthetic procedure, we were interested to develop a suitable HPLC method to separate directly the radiotracer from its nitro precursor. Several analytical HPLC columns and eluent systems were investigated.

2. Materials & Methods
Because of the basic character of the analytes (tertiary amines) several columns were selected which are specially designated for the separation of basic analytes due to their potential to reduce peak tailing (LiChrospher Select B, Nucleosil AB, Reprosil Gold, Reprosil-Pur Basic HD). To study the influence of possible pi-pi-interactions, especially of the nitro precursor, we also used different phenyl and cyano columns (Nucleodur Sphinx, Fortis Phenyl, Reprosil Phenyl, LiChrospher CN). For comparison also a bare silica phase and commonly used AQ phases were investigated.
Aqueous acetonitrile and methanol mixtures with ammonium acetate, triethylamine/acetic acid, and trifluoroacetic acid were used as typical eluent systems.

3. Results
The aims of this HPLC study were: (i) to find a suitable separation method in which the fluoro compound clearly elutes in front of the nitro precursor, and (ii) to get more information about the suitability of different column types regarding separation data such as retention, peak tailing and resolution.
In general, with almost all columns the two compounds could be separated, however, the quality of separations was different and surprisingly, changes in elution order were observed. For example, using aqueous acetonitrile/ammonium acetate as eluent system, the fluoro compound elutes in front of the nitro precursor at low content of organic modifier. In contrast, a reversed retention behavior was observed at high content of acetonitrile which was also found by using methanol as organic modifier. Additionally, we observed that not all columns, designated to be especially appropriate for basic analytes, showed satisfying separation properties. Finally, a phenyl column was selected for the semi-preparative separation of the 18-F-labeled radiotracer from its nitro precursor and a reduction of the total radiosynthesis time by one hour could be achieved .

4. Conclusion
Due to this intensive analytical HPLC study, we were able to select a suitable column for an improved purification of a radiotracer from its remaining nitro precursor, which resulted in a considerable shortening of the radiosynthetic procedure.
  • Poster
    16th European Symposium on Radiopharmacy and Radiopharmaceuticals, 26.-29.04.2012, Nantes, France

Publ.-Id: 16742 - Permalink

Regioselektive Synthese neuer Vesamicolanaloga als potenzielle Liganden für den vesikulären Acetylcholintransporter im Gehirn
Jäckel, P.;
Es ist kein Abstract vorhanden.
  • Thesis / Students' report
    HTW Dresden, 2011
    48 Seiten

Publ.-Id: 16741 - Permalink

Multilayer Deposition and Resuspension Studies of Aerosol Particles between Periodic Steps in Turbulent Channel Flows
Lustfeld, M.; Barth, T.; Banowski, M.;
Radioactive carbonaceous aerosol particles deposit within the primary circuit of a high temperature reactor (HTR). These particles can pose a considerable threat if resuspended by a shock wave in the case of an unlikely loss-of-coolant accident and partially released into the environment (Kissane, 2009).
Stempniewicz et al. (2010) carried out simulations of the spatial and temporal development of carbonaceous dust deposits in the primary circuit of a HTR. Maximum dust layer thickness after full operation time of 60 years was well above 10 mm. However, the underlying multilayer models require additional experimental verification.
Therefore, particle deposition and resuspension experiments of multilayer graphite deposits have been conducted in a small-scale test facility. The results for particle layer thickness have been correlated to corresponding flow data as measured by means of a 2C2D Particle Image Velocimetry (PIV) system.
The experimental facility consists of a ventilated square duct (d = 100 mm), which is operated with air at ambient conditions. The average air velocity can be regulated over the range u = 1..7 m/s, corresponding to Reynolds numbers between Red = 8.9k..42k. As flow obstacles, periodic steps have been chosen (Fig. 1) allowing the comparison of results with previous studies on monolayer deposition (e.g. Lai et al., 1999).
Graphite aerosol particles (Thielmann Graphite, 23061) have been injected into the duct 15 diameters upstream of the test section by means of a dust disperser TOPAS - SAG 410. Setting the mass flux to 80 g/h an average mass concentration of airborne particles of up to 2 g/m³ is established. The aerodynamic particle size distribution of the graphite particles was determined by means of a TSI – APS 3321confirming that the particles cover well the range of interest for HTR conditions (quantiles:
dP,10 = 1.83 µm, dP,50 = 4.40 µm and dP,90 = 10.64 µm).
The deposition experiments have been conducted under different flow conditions and the development of graphite particle deposits in the vicinity of the steps have been observed by hourly laser triangulation measurements. Subsequently, the generated multilayer has been resuspended at a higher flow velocity and the thickness of the remaining structure has been measured using the same techniques.
Results show that for a relatively low Reynolds number of Red = 8.9k (Fig.2), deposition is mainly governed by gravitational settling and the deposition rate is almost independent of position and time. On the other hand, subsequent resuspension at higher flow velocities (Red =27.2k) reveals a strong relation between flow field and remaining layer (Fig.3), which is further being investigated.
Keywords: Carbonaceous particles, deposition, High Temperature Reactor, periodic steps, resuspension
  • Lecture (Conference)
    European Aerosol Conference, 04.-09.09.2011, Manchester, United Kingdom

Publ.-Id: 16740 - Permalink

Influence of probe nozzle diameter on aerosol particle size distribution for isokinetic sampling in gas streams
Barth, T.; Lustfeld, M.;
Isokinetic sampling from stacks and ducts is a widely used method for air pollution control in many industrial and environmental applications.
During the last 40 years, U.S. EPA developed reference methods for air pollutant emission sampling of stationary sources, which included a compendium of technical guidelines for the monitoring of aerosol particles. One of the main parts of the sampling system is the sampling probe nozzle for which it was suggested in the reference methods that the lower bound diameter should be greater than di = 6 mm (Cohen, 2001). The influences of sampling nozzle tube diameter, the velocity ratio between free stream and the sampling tube as well as the tube inclination have been considered widely (Vincent, 2007). On the other hand, the influence of tube diameter has not been quantified by means of aerosol particle size spectrometry yet.
McFarland et al. (1997) as well as Peters and Leith (2004) experimentally investigated the deposition losses of aerosol particles in pipe bends. Both found a strong increase of deposition losses in the sampling tube for particle Stokes number of Stk > 0.3.
In this work, the influence of the nozzle diameter of the sampling probe on the aerosol particle size distribution was investigated by means of TSI APS 3321 and TOPAS LAP 321 measurements.
The considered gas/aerosol test facility is a small scale wind tunnel, which consists of a HEPA at the inlet and a square duct section in diameter of dhyd = 10 cm and length of l = 20dhyd = 2 m. The test section, where sampling takes place, is followed by a diffuser stage, an electrical precipitator and a radial fan in order to generate the desired pressure head. The average air velocity can be regulated over the range u = 1..7 m/s, corresponding to Reynolds numbers between Red = 8.9k..42k. In order to achieve isokinetic sampling, the flow rate of the sampling device has been accurately adjusted using Particle Image Velocimetry data.
AC Fine Test Dust (ISO 12103-1, dnom = 0.1..80 µm, bimodal distribution) was injected 17 diameter lengths upstream of the sampling point by means of a dust disperser TOPAS SAG 410. Four probe nozzle diameters di = [3,5,7,9] mm were chosen.
Figure 1 displays the volume weighted aerodynamic particle size distribution of AC Fine under variation of nozzle tube diameter as measured by the APS 3321. The modal dP,aero = 5 µm is roughly independent of nozzle size, whereas the values of the distribution for particle diameters above dP,aero > 12 µm increase continuously with increasing nozzle diameter.
A similar upward tendency in size distribution with increasing nozzle diameter is observed in the LAP measurement results (not shown here). This leads to the conclusion that deposition losses due to inertia, which consequently affect the larger particles, can be considerably reduced by accordingly increasing tube nozzle diameter. In addition, a comparison of aerodynamic particle size (APS 3321) and scattering particle size (LAP 321) will be presented.
Keywords: deposition, instrumentation, measurement, sampling, spectrometry
  • Poster
    European Aerosol Conference, 04.-09.09.2011, Manchester, United Kingdom

Publ.-Id: 16739 - Permalink

Effect of an electromagnetic brake on the turbulent melt flow in a continuous casting mold
Miao, X.; Timmel, K.; Lucas, D.; Ren, Z.; Eckert, S.; Gerbeth, G.;
This paper presents numerical and experimental investigations with respect to the fluid flow in the continuous casting process under the influence of an external DC magnetic field. Numerical calculations were performed by means of the software package CFX with an implemented RANS-SST turbulence model. The non-isotropic nature of the MHD turbulence was taken into account by specific modifications of the turbulence model. The numerical results were validated by flow measurements carried out in a small-scale mockup using the eutectic alloy GaInSn. The jet flow discharging from the submerged entry nozzle was exposed to a level magnetic field spanning across the entire wide side of the mold. The comparison between our numerical calculations and the experimental results displays a very well agreement, in particular, we were able to reconstruct the peculiar phenomenon of an excitation of non-steady, non-isotropic large-scale flow perturbations due to the application of the DC magnetic field. Another important result of our study is the feature that the electrical boundary conditions, namely the wall conductivity ratio, have a serious influence on the mold flow just as it is exposed to an external magnetic field.
Keywords: continuous casting, fluid flow, electromagnetic brake, CFD modelling, RANS model

Publ.-Id: 16738 - Permalink

ELBE Upgrade
Michel, P.;
Until 2014 ELBE will be upgraded to a Centre for High Power Radiation Sources. The concept contains additional broad and narrow band coherent THz sources and the development of a 500 TW Ti:Sa Laser and even a 2 PW diode pumped Laser system. Laser plasma electron acceleration and proton acceleration experiments for medical applications are planed. Additionally coupled electron laser beam experiments like Thomson scattering or injection of ELBE electron into the laser plasma will be done.
Keywords: broad and narrow band coherent THz sources; 500 TW Ti:Sa Laser; 2 PW diode pumped Laser system
  • Lecture (others)
    Superconducting Accelerators for FEL- and Bremsstrahlung Applications Workshop, 31.01.-03.02.2011, Antalya, Türkei

Publ.-Id: 16737 - Permalink

Radionuclide-labeled Substances for Molecular Therapy of Tumors
Steinbach, J.;
kein Abstract verfügbar
  • Invited lecture (Conferences)
    Helmholtz-Kurchatov-Workshop, 24.05.2011, Moskau, Russland

Publ.-Id: 16735 - Permalink

Overview about ELBE and Project Organization
Michel, P.;
A superconducting Electron Linac with high Brilliance and low Emittance (ELBE) which provides an average beam current of 1 mA with maximum beam energy of 36 MeV was constructed in the Forschungszentrum Dresden-Rossendorf, Germany. The electron beam is used to generate infrared light (Free Electron Lasers), MeV-Bremsstrahlung, X-rays (electron channelling), fast neutrons and positrons. The ELBE secondary beams are used for a wide range of basic research like semiconductor physics, nuclear astrophysics and radio biological investigations. Furthermore a 150 TW Ti:Sa Laser delivers high intense and very short laser pulses used for laser plasma acceleration of electrons and protons.
ELBE was built by an internal project group of the Rossendorf research center. The professional structure of this project group, the project management tools and the available budget and the schedules will be discussed, as well.
Keywords: Electron LINAC; infrared light; MeV-Bremsstrahlung, X-rays
  • Lecture (others)
    Superconducting Accelerators for FEL-and Bremsstrahlung Applications Workshop, 31.01.-03.02.2011, Antalya, Türkei

Publ.-Id: 16734 - Permalink

Affinität und Spezifität neuer Vesamicol-Derivate für die Positronen-Emissions-Tomographie
Schweiger, S.;
Es ist kein Abstract vorhanden.
  • Thesis / Students' report
    Universität Leipzig, 2011
    53 Seiten

Publ.-Id: 16733 - Permalink

Synthese und Charaterisierung mehrfunktionaler Cyclam-Liganden mit Propionsäuregruppen
Lehmann, T.;
kein Abstract verfügbar
  • Other
    Technische Universität Dresden, Fakultät Mathematik und Naturwissenschaften, FR Chemie und Lebensmit, 2011
    75 Seiten

Publ.-Id: 16729 - Permalink

Entwicklung von Indolylalkylamin-basierten Radiotracern für den Serotonintransporter
Funke, U.;
kein Abstract verfügbar
  • Doctoral thesis
    Universität Leipzig, Fakultät Chemie und Mineralogie, 2011
    231 Seiten

Publ.-Id: 16728 - Permalink

Affinitätsuntersuchungen von Cetuximab-Konjugaten an Tumorzellen mit unterschiedlichen EGFR-Expressionen
Jacob, A.;
kein Abstract verfügbar
  • Diploma thesis
    Technische Hochschulle Mittelhessen, Gießen, 2011
    62 Seiten

Publ.-Id: 16727 - Permalink

Zellaufnahme und Zelltoxizitätsuntersuchungen mit rheniumhaltigen Clusterverbindungen
Völkner, C.;
kein Abstract verfügbar
  • Bachelor thesis
    Hochschule für Technik und Wirtschaft Dresden, FB Maschinenbau/Verfahrenstechnik, 2011
    62 Seiten

Publ.-Id: 16726 - Permalink

EGRF-spezifische Peptide mit Pyridin-haltigen 1,4,7-Triazacyclononan-Liganden: Synthese, 64Cu-Markierung und Interaktion mit FaDu-Zellen
Hesse, J.;
kein Abstract verfügbar
  • Diploma thesis
    Technische Universität Bergakademie Freiberg, Fakultät Chemie und Physik, 2011
    79 Seiten

Publ.-Id: 16725 - Permalink

18F- and 11C-radiolabeled 1,2-diaryl substituted indoles as potential probes for monitoring cyclooxygenase-2 (COX-2) -radiosynthesis and cell uptake studies
Kniess, T.; Laube, M.; Graf, F.; Steinbach, J.; Pietzsch, J.;
Aim: Cyclooxygenase-2 (COX-2) is an enzyme induced during inflammation, but overexpression of COX-2 also has been observed in carcinogenic processes. Noninvasive monitoring and quantitative characterization of functional expression of
COX-2 by means of PET would substantially improve understanding of the role of this enzyme during manifestation and progression of inflammatory diseases and cancer. Herein we report first radiosynthesis and cellular uptake studies of two
highly affine COX-2 inhibitors having a 1,2-diaryl substituted indole scaffold.
Materials and methods: The highly affine COX-2 inhibitors 3-(4-fluorophenyl)-2-(4-methylsulfonylphenyl)-1H-indole 1 and 3-(4-methoxyphenyl)-2-(4-methylsulfonylphenyl)-1H-indole 2 (both IC50 COX-2 ~ 20 nM) [1] served as nonradioactive references. The 18F-radiolabeled tracer [18F]1 was synthesized by nucleophilic substitution of an appropriate trimethylammonium-substituted aromatic precursor with [18F]fluoride and subsequent McMurry cyclization. The 11C-radiolabeled probe [11C]2 was formed via a methylation reaction of the corresponding desmethyl precursor with [11C]CH3I. Different human tumor cell lines showing selectively high COX-2 (FaDu, HT-29, A2058) or COX-1 expression (A375) were used to study the overall uptake or cellular association of [18F]1 and [11C]2 in vitro. To further differentiate the specific contribution of COX-1 and COX-2 to overall tracer uptake, unstimulated human monocytic leukemia cells (THP-1) and phorbol ester stimulated THP-1 macrophages (THP-1M) were used as models. The cell tracer uptake experiments using compounds [18F]1 and [11C]2 (0.4 MBq/mL) were performed in quadruplicate at 37°C for 30, 60, and 120 min.Results:[18F]1 was synthesized from [18F]fluoride in 10% yield (d.c.) in 98% radiochemical purity with a specific activity of 74-91 GBq/μmol. The 11Cradiolabeled compound [11C]2 was obtained in 23% yield (d.c.) in 99% radiochemical purity with a specific activity of 79-89 GBq/μmol. The radiotracer cellular uptake in each model used correlated well with the observed COX protein synthesis. Cell models with prominent COX-2 overexpression showed a substantially higher uptake of both [18F]1 and [11C]2 in the order FaDu>HT29>THP-1M>A2058 when compared to COX-1 overexpressing A375 cells. The lowest cellular uptake was observed in THP-1 showing no or very low baseline expression of both COX-1 and COX-2.
Conclusion:The new radiolabeled COX-2 inhibitors were synthesized in good radiochemical yield and high purity. Cellular studies demonstrated well correlation of the overall radiotracer uptake with COX expression/protein synthesis rate. Further exploration of the new COX-2 inhibitors [18F]1 and [11C]2 regarding in vivo metabolic stability and biodistribution, including dynamic small animal PET investigations in tumor bearing mice, is currently under the way.[1] Hu W., Bioorg. Med. Chem. 11, (2003), 1153
  • Poster
    Annual Congress of the European Association of Nuclear Medicine (EANM) 2011, 15.-19.10.2011, Birmingham, UK
  • Abstract in refereed journal
    European Journal of Nuclear Medicine and Molecular Imaging 38(2011), S233

Publ.-Id: 16723 - Permalink

Biotechnologische Verfahren zur Sicherung von Rohstoffen
Pollmann, K.; Raff, J.; Kutschke, S.;
Vorstellung von geplanten Arbeiten am HIF
  • Open Access LogoContribution to external collection
    in: Acamonta- Zeitschrift für Freunde und Förderer der Technischen Universität Bergakademie Freiberg, Freiberg: TUBA Freiberg, 2011, 26-27

Publ.-Id: 16722 - Permalink

Combined PET/MRI system in Head and Neck Cancer: Initial Experience
Beuthien-Baumann, B.; Platzek, I.; Schneider, M.; Gudziol, V.; Langner, J.; Brüning, E. M.; Laniado, M.; Kotzerke, J.; van den Hoff, J.;
The recently introduced whole-body PET/MRI systems combine the unique metabolic imaging capabilities of positron emission tomography (PET) and the excellent soft tissue contrast of magnetic resonance imaging (MRI). The aim of this pilot study was to evaluate the feasibility of PET/MRI for initial staging of head and neck cancer.
Materials and Methods:Ten male patients aged (age 52 to 78 years, median age 62.8 y) with histologically proven squamous cell carcinoma of the head and neck region were examined using both a stand-alone PET scanner and a wholebody
PET/MRI scanner. Scanning started 60 minutes after intravenous administration of 350 MBq [18-F]-2-fluoro-2-deoxy-D-glucose (FDG) for the body trunk to exclude distant metastases. PET/MRI of the head and neck region followed immediately the first scan. The study was approved by the local ethics committee. A four-point-scale was used for qualitative evaluation of PET image quality. Furthermore, the signal-to-noise ratio (SNR) of the tumor and of both cerebellar hemispheres were determined for both PET data sets and used for semiquantitative comparison of image quality. Results were compared using the Wilcoxon matched-pair test.Results:The primary tumor was detected by PET/MRI in all 10 patients, by PET in 9 out of 10 cases, and by MRI in 9 out of 10 cases. Seven patients had lymph nodes suspect for metastatic disease. In two patients, lymph nodes considered suspect using MRI showed no pathological FDG uptake. In contrast, a single patient had lymph nodes considered suspect by PET but not by MRI. Visual evaluation of PET images showed consistent results (including regional contrast) for both scanners. There were no statistically significant differences regarding SNR between conventional PET and PET/MRI for the tumor and for both cerebellar hemispheres (p > 0.05).
Conclusion: PET/MRI of head and neck cancer is feasible with a whole-body PET/MRI scanner with excellent image quality and - fusion. While previously available PET/MRI systems were largely restricted to brain examinations, whole-body PET/MRI scanners allow comprehensive tumor staging. Further patients will be examined to evaluate the clinical role of PET/MRI in head and neck cancer.
  • Poster
    Annual Congress of the European Association of Nuclear Medicine (EANM) 2011, 15.-19.10.2011, Birmingham, UK
  • Abstract in refereed journal
    European Journal of Nuclear Medicine and Molecular Imaging 38(2011), S345

Publ.-Id: 16721 - Permalink

Ion beams as a tool for advanced structural characterization in ZnO-based materials
Redondo-Cubero, A.; Lorenz, K.; Alves, E.; Gago, R.; Hierro, A.; Vinnichenko, M.; Chauveau, J.-M.; Nakamura, A.; Krause, M.; Temmyo, J.; Muñoz, E.; Brandt, M.; Henneberger, F.;
This work shows the application of ion beam techiques to the structural characterization of different ZnO compounds. Taking advantage of ion channelling phenomena in combination with some specific nuclear resonances, the individual evaluation of defects in the IIb-metal and O sublattices is achieved.
  • Invited lecture (Conferences)
    SPIE Photonics West, Optoelectronic Materials and Devices, Oxide-based Materials and Devices III (Conference 8263), 22.-25.01.2012, San Francisco, USA

Publ.-Id: 16720 - Permalink

On the action of magnetic gradient forces in microstructured copper deposition
Mutschke, G.; Tschulik, K.; Weier, T.; Uhlemann, M.; Bund, A.; Alemany, A.; Fröhlich, J.;
The relative influence of the Lorentz force and the magnetic gradient force on micro-structured copper deposition is studied with simple magnetic elements consisting of cylindrical permanent magnets are placed closely behind the surface of the cathode. Analytical findings and numerical simulations reveal that for magnets of small diameter the magnetic gradient force dominates. Experimental investigations find that the thickness of the deposited copper layer increases in the vicinity of the magnets. The combined analysis of simulations and experiments shows that this enhancement of mass transfer results from a local convection towards the electrode which is forced by the magnetic gradient force.
Keywords: electrodeposition, Lorentz force, magnetic gradient force
  • Magnetohydrodynamics 48(2012)2, 299-304

Publ.-Id: 16719 - Permalink

Neue biotechnologische Verfahren zur (Rück)Gewinnung seltener Industriemetalle
Raff, J.;
Vorstellung der aktuellen und geplanten Forschungsarbeiten zum Thema (Rück)Gewinnung seltener Industriemetalle mittels biotechnologischer Verfahren am Helmholtz-Institut Freiberg für Ressourcentechnologie (HIF) und am Institut für Ressourcenökologie.
  • Lecture (others)
    Vortrag bei der Gesellschaft zur Förderung von Medizin-, Bio- und Umwelttechnologien e.V. (GMBU), Arbeitsgruppe "Funktionelle Schichten", 07.03.2012, Dresden, Deutschland

Publ.-Id: 16718 - Permalink

Anchoring functional molecules on TiO(2) surfaces: A comparison between the carboxylic and the phosphonic acid group
Luschtinetz, R.; Gemming, S.; Seifert, G.;
The adsorption of formic acid on clean TiO(2) anatase (101) and rutile (110) surfaces is studied by density-functional-based methods and compared with the results for coupling related phosphonic acids to titania surfaces. The preferred adsorption mode of the formic acid on both surfaces is a dissociative bridging bidentate complex, which is similar to the adsorption geometry of phosphonic acid. Higher adsorption energies and shorter Ti-O bond lengths indicate that phosphonic acid binds more strongly to TiO(2) than formic acid. The preference for the bidentate adsorption mode is supported by a detailed analysis of the charge distribution in the adsorption complexes. The strong interfacial electronic coupling between the adsorbate orbitals and the electronic states of the anatase (101) surface slab leads to additional states in the band gap of the clean surface. For rutile (110) no or only weak coupling of the adsorbate orbitals and the surface states occurs at the band edges, which leads to an increase of the band gap.
Keywords: density functional, DFT, transport, surface, organic electronics

Publ.-Id: 16717 - Permalink

Structure and properties of molybdenum sulfide nanostructures
Gemming, S.;
Overview presentation on the dependence of dimensionality, structure, size, composition, electronic properties and preparation conditions of molybdenum sulfide nanostructures at the Seifert group seminar.
Keywords: molybdenum sulfide, density functional, brim state, conductivity, transport
  • Lecture (others)
    Workshop Electronic Structure of Novel Materials, 23.06.2011, Meissen, Deutschland

Publ.-Id: 16716 - Permalink

Nanostructures – Small and Beautiful
Gemming, S.; Facsko, S.; Erbe, A.;
Overview presentation of FWIO activities.
Keywords: density functional, transport, ion-beam
  • Invited lecture (Conferences)
    Kristallographisches Oberseminar, 27.05.2011, München, Deutschland

Publ.-Id: 16715 - Permalink

Transport through nanostructures
Gemming, S.;
DFTEM 2011 Tutorial on nanoscale electronic transport
Keywords: DFT, density functional, transport
  • Invited lecture (Conferences)
    CECAM Workshop "Density Functional Theory and Transmission Electron Microscopy" 2011, 24.-28.07.2011, Lausanne, Schweiz

Publ.-Id: 16714 - Permalink

Density Functional Theory + Transmission Electron Microscopy - Introduction to Density Functional Theory
Gemming, S.;
Workshop DFTEM 2011 - Introductory Lecture to DFT
Keywords: density functional, DFT
  • Invited lecture (Conferences)
    CECAM-Workshop "Density Functional Theory and Transmission Electron Microscopy" 2011, 24.-28.07.2011, Lausanne, Schweiz

Publ.-Id: 16713 - Permalink

Ecto-ATPase inhibition: ATP and adenosine release under physiological and ischemic in vivo conditions in the rat striatum
Melani, A.; Corti, F.; Stephan, H.; Müller, C. E.; Donati, C.; Bruni, P.; Vannucchi, M. G.; Pedata, F.;
In the central nervous system (CNS) ATP and adenosine act as transmitters and neuromodulators on their own receptors but it is still unknown which part of extracellular adenosine derives per se from cells and which part is formed from the hydrolysis of released ATP. In this study extracellular concentrations of adenosine and ATP from the rat striatum were estimated by the microdialysis technique under in vivo physiological conditions and after focal ischemia induced by medial cerebral artery occlusion. Under physiological conditions, adenosine and ATP concentrations were in the range of 130 nmol/L and 40 nmol/L, respectively. In the presence of the novel ecto-ATPase inhibitor, PV4 (100 nmol/L), the extracellular concentration of ATP increased 12-fold to ~360 nmol/L but the adenosine concentration was not altered. This demonstrates that, under physiological conditions, adenosine is not a product of extracellular ATP. In the first 4 h after ischemia,
adenosine increased to ~690 nmol/L and ATP to ~50 nmol/L. In the presence of PV4 the extracellular concentration of ATP was in the range of 450 nmol/L and a significant decrease in extracellular adenosine (to ~270 nmol/L) was measured. The contribution of extracellular ATP to extracellular adenosine was maximal in the first 20 min after ischemia onset. Furthermore we demonstrated, by immunoelectron microscopy, the presence of the concentrative nucleoside transporter CNT2 on plasma and vesicle membranes isolated from the rat striatum. These results are in favor that adenosine is transported in vesicles and is released in an excitation–secretion manner under in vivo physiological conditions. Early after ischemia, extracellular ATP is hydrolyzed by ecto-nucleotidases which significantly contribute to the increase in extracellular adenosine. To establish the contribution of extracellular ATP to adenosine might constitute the basis for devising a correct putative purinergic strategy aimed at protection from ischemic damage.
Keywords: ATP; Adenosine; Microdialysis; Focal cerebral ischemia; Rat

Publ.-Id: 16712 - Permalink

Study of differences in the VEGFR2 inhibitory activities between semaxanib and SU5205 using 3D-QSAR, docking, and molecular dynamics simulations
Munoza, C.; Adasmea, F.; Alzate-Morales, J. H.; Vergara-Jaquea, A.; Kniess, T.; Caballero, J.;
Semaxanib (SU5416) and 3-[4'-fluorobenzylidene]indolin-2-one (SU5205) are structurally similar drugs that are able to inhibit vascular endothelial growth factor receptor-2 (VEGFR2), but the former is 87 times more effective than the latter. Previously, SU5205 was used as a radiolabelled inhibitor (as surrogate for SU5416) and a radiotracer for positron emission tomography (PET) imaging, but the compound exhibited poor stability and only a moderate IC50 toward VEGFR2. In the current work, the relationship between the structure and activity of these drugs as VEGFR2 inhibitors was studied using 3D-QSAR, docking and molecular dynamics (MD) simulations. First, comparative molecular field analysis (CoMFA) was performed using 48 2-indolinone derivatives and their VEGFR2 inhibitory activities. The best CoMFA model was carried out over a training set including 40 compounds, and it included steric and electrostatic fields. In addition, this model gave satisfactory cross-validation results and adequately predicted 8 compounds contained in the test set. The plots of the CoMFA fields could explain the structural differences between semaxanib and SU5205. Docking and molecular dynamics simulations showed that both molecules have the same orientation and dynamics inside the VEGFR2 active site. However, the hydrophobic pocket of VEGFR2 was more exposed to the solvent media when it was complexed with SU5205. An energetic analysis, including Embrace and MM-GBSA calculations, revealed that the potency of ligand binding is governed by van der Waals contacts
Keywords: Kinase inhibitors; VEGFR2; Semaxanib; QSAR; CoMFA; Docking; Molecular dynamics; Protein-ligand interactions; MM-GBSA

Publ.-Id: 16711 - Permalink

Radiolabeled small molecule inhibitors of VEGFR – recent advances
Kniess, T.;
The vascular endothelial growth factor (VEGF) is a key regulator of neovascularization and an elevated level of VEGF is known to correlate with increased metastatic invasion. Anti-angiogenic therapies focus on targeted inhibition of overexpressed growth factors with the aim of suppressing tumor proliferation, one approach is the attempt to block the intracellular tyrosine kinase at the adenosine triphosphate (ATP) binding site with small molecule inhibitors. For most effective treatment these targeted tumor therapies are accompanied with a more sensitive need for dose optimization and monitoring the therapeutic response. Direct non-invasive molecular imaging of tumor vascularization and of the angiogenic process in vivo would facilitate the selection of patients and help to evaluate the efficacy of an anti-angiogenic therapy. Radionuclide-based imaging technologies like PET and SPECT are progressively affecting the clinical diagnosis and treatment of cancer. A non-invasive and a reliable quantitative method to determine in vivo the levels of VEGFR expression using radiolabeled small molecules would help to develop a customized VEGFR-targeted chemotherapy. This review will give an overview on radiolabeled derivatives of small molecule VEGFR inhibitors basing on lead structures that have been approved or have reached clinical trials. It is covering aspects of the radiosynthesis as well the results of radiopharmacological and biological evaluation.
Keywords: Anti-angiogenic, tumor therapy, VEGFR, PET, tyrosine kinase inhibitors, radiolabeling

Publ.-Id: 16710 - Permalink

Module-assisted preparation of 64Cu with high specific activity
Thieme, S.; Walther, M.; Pietzsch, H.-J.; Henniger, J.; Preusche, S.; Mäding, P.; Steinbach, J.;
In this work the production of 64Cu via the 64Ni(p,n)64Cu reaction with optimized conditions for low current irradiation is presented. Different target setups and cleaning steps for lowering metal contaminations in the product were applied. 64Cu with high specific activities up to 1685 GBq/µmol were produced despite low overall activity ( ~ 4.2 GBq per run). The module processing leads to a highly reproducible, reliable product quality (< 1 µg Cu and < 7 µg Ni). Beside its diagnostic value 64Cu may be of interest even for therapeutic purposes due to its decay characteristics.

Publ.-Id: 16709 - Permalink

Measurement of blood flow in rodents using radioactive microspheres
Bergmann, R.; Richter, T.; Schiller, E.; Bos, A.; Kniess, T.; Hofheinz, F.; van den Hoff, J.; Pietzsch, J.;
Aim: Regional blood flow represents an important physiological parameter in experimental animals of various disease models. The ‘gold standard’ in large animals is to inject microspheres into the left ventricle using heart catheters; the number of microspheres trapped in the tissue capillaries is directly proportional to blood flow. Injection of radioactive microspheres directly into the left ventricle allows easy assessment of relative blood flow using imaging technologies. Absolute blood flow quantification will be also possible after additional arterial catheterization (required for reference blood sampling). However, up to now this technique has been rarely used in small rodents. In this pilot study we evaluated the technique in small rodents (mouse, rats) using radioactive microspheres.

Methods: Human serum albumin microspheres (20 µm diameter) were modified with NOTA. NOTA-microspheres were radiolabeled with Ga-68, Cu-64 or with F-18-fluoro-benzyol-succinimide using non modified microspheres. The number of injected microspheres was varied between 50,000 and 500,000. The microspheres were directly injected into the left ventricle over a time period of 30 s in desflurane-anesthetized animals on a heating pad. The animals were sacrificed 60 s after the end of injection. Total body activity was measured using a dose calibrator followed by small animal PET scan. The PET images were coregistered with MRI or CT images for identification of the tissues of interest. Standard uptake values were calculated and used for determination of relative blood flow.

Results: Radiolabeling resulted in high radiochemical yields and purity. The microsphere distribution was derived from the radioactivity distribution in the organs. The microspheres were virtually completely trapped (>99%) in the capillary bed. The injection is the most critical step of the experimental procedure. The number of applied microspheres was the limiting factor for measurements in low flow areas, where the number of measured microspheres was below 400. The heart was not included because of potential injury of the coronary arteries. The highest perfusion was found in the kidneys and the cerebellum while the blood flow in the anesthetized animals was low in the cerebral cortex. In rats it was also possible to assess the high flow in the thyroid gland.

Conclusion: This pilot study shows that the microsphere technique allows imaging and assessment of relative organ blood flow. This work will be continued to enable absolute blood flow measurements as well.
  • Poster
    ESRR'12 - 16th European Symposium on Radiopharmacy and Radiopharmaceuticals, 26.-29.04.2012, Nantes, France
  • Abstract in refereed journal
    Quarterly Journal of Nuclear Medicine and Molecular Imaging 56(2012), 52-53

Publ.-Id: 16708 - Permalink

Formation of nanoclusters with varying Pb/Se concentration and distribution after sequential Pb+ and Se+ ion implantation into SiO2
Markwitz, A.; Carder, D. A.; Hopf, T.; Kennedy, J.; Kuei, C. T.; Mücklich, A.; Osipowicz, T.;
First results obtained from electron beam annealed sequentially implanted Pb+ (29 keV) and Se + (25 keV) ions into a SiO2 matrix are presented. Key results from Rutherford backscattering spectrometry and transmission electron microscopy investigations are: (1) Pb and Se atoms are found to bond in the SiO2 matrix during implantation, forming into nanoclusters even prior to the annealing step, (2) Pb and Se atoms are both present in the sample after annealing at high temperature (T = 760 °C, t = 45 min) and form into PbSe nanoclusters of varying sizes within the implanted region, and (3) the broader concentration profile of implanted Se creates a number of secondary features throughout the SiO2 film, including voids and hollow shell Se nanoclusters. A sequential ion implantation approach has several advantages: selected areas of nanocrystals can be formed for integrated circuits, the technique is compatible with present silicon processing technology, and the nanocrystals are embedded in an inert matrix - making them highly durable. In addition, a higher concentration of nanocrystals is possible than with conventional glass melt techniques.

Publ.-Id: 16707 - Permalink

PBF Changes In Areas Of Aspiration-Induced Acute Lung Injury Within Two Hours.
Richter, T.; Bergmann, R.; Pietzsch, J.; Ragaller, M.;
RATIONALE: Acid-aspiration is recognized as a risk factor for subsequent development of acute lung injury or ARDS. Areas of aspiration induced injury matches regions of high pulmonary blood flow (PBF) in the early stage of acute lung injury, as we shown recently. The aim this project was to characterize the changes of spatial PBF distribution as a function of time after injury.
METHODS: The protocol was approved by the Animal Studies Committee of the Landesdirektion Dresden. Eleven anesthetized, spontaneous breathing male Wistar rats were scanned with a small animal CT scanner before and after injury. Positron emission tomography (PET) was carried out after aspiration-induced lung injury. Aspiration was achieved by installation of 0.1 HCl (0.4 ml/kg body weight) through a tracheostomy tube. Pulmonary blood flow (PBF) was calculated from the radioactivity distribution in the lungs of infused 68Ga-DOTA-human serum albumin microspheres ten minutes after injury in group 1 (n=6) and two hours after injury in group 2 (n=5). CT- and PET images were co-registered. Areas of injury, as identified from CT derived changes in density, were labeled with a spherical mask. Regions of interest were derived using a threshold (80% of maximum) within the masks. Identical masks were used for the contralateral lung as reference. PBF was calculated and compared as a fraction of injured and reference side with Wilcoxon matched-pairs signed rank test. The PBF-fraction after the different time points was compared between the groups by unpaired t test with Welch's correction. RESULTS: Data presented are median (interquartile range). CT images after injury showed areas of lung injury different in size and location within the groups. Fraction of PBF was higher in group 1 (1.34 (1.15-1.45)) compared to group 2 (0.9 (0.85-1.06); P=0.0014) shown in Figure 1. The difference between both groups was determined by a high PBF in injured lung regions compared to the contralateral reference side at 10 min after injury (P = 0.03), whereas at 120 min after aspiration, injured regions have shown similar PBF compared to the contralateral reference side (0.81).
CONCLUSION: Regional PBF is increased 10 minutes after acid aspiration in regions of lung injury. This effect disappears within two hours after injury in anesthetized rats. These PBF-changes may be important for early treatment strategies after acid aspiration.
  • Lecture (Conference)
    American Thoracic Society International Conference, 18.05.2011, Denver, USA
  • Abstract in refereed journal
    American Journal of Respiratory and Critical Care Medicine 183(2011), A6155

Publ.-Id: 16706 - Permalink

SUV-measurements and patient-specific corrections thereof in pediatric Hodgkin-lymphoma: Is there a benefit for PPV in early response assessment by FDG-PET?
Furth, C.; Meseck, R. M.; Steffen, I. G.; Schoenberger, S.; Denecke, T.; Henze, G.; Hautzel, H.; Hofheinz, F.; Großer, O.; Hundsdoerfer, P.; Amthauer, H.; Ruf, J.;
Background: To evaluate the influence of different SUV-measurements and patient-specific corrections thereof on the positive predictive value (PPV) of FDG-PET in pediatric Hodgkin lymphoma (pHL) using SUV-based response assessment.
Methods: PET-datasets of 33 children [female, n = 13, male, n = 20; range of age, 8.0–17.8 (mean, 15.0) years; follow-up, 44.5–83.3 (mean 63.0) months] with HL were analyzed retrospectively. PET-scans were obtained baseline (PET1) and after two cycles of chemotherapy (PET2). Within the leading lesion maximal SUV (SUVmax) and mean SUVs were generated by using isocontur-thresholds for different volumes of interest: Absolute, SUV2.5; relative to SUVmax, SUVmean40% to SUVmean70%. Generated SUVs were adjusted to body weight (SUV) and corrected for body surface area (SUV_BSA), patient's blood glucose and a combination thereof. The decrease in SUV or respective derivates thereof between PET1 and PET2 (ΔSUV) was assessed for response prediction using receiver operating characteristics (ROC)-analysis.
Results: Three patients had recurrence of disease. ROC-analysis showed the most accurate differentiation of responders and non-responders for ΔSUVmax_BSA [AUC, 0.97; P = 0.0026; sensitivity, 100%; specificity, 93.3%; PPV, 60.0%; negative predictive value (NPV), 100%; accuracy, 93.3%]. However, comparable results were obtained for conventional ΔSUVmax-determination (AUC, 0.96; P = 0.0112; sensitivity, 100%; specificity, 90.0%; PPV, 50.0%; NPV, 100%; accuracy, 90.9%). Threshold-based approaches were less effective or technically not performable in all patients.
Conclusions: At early response assessment by FDG-PET, patient-specific correction of ΔSUVmax by BSA improves PPV without impairment of excellent NPV in pHL. However, it is not statistically superior to simple ΔSUVmax-analyses. Larger cohorts are needed to investigate this observation.
Keywords: FDG-PET; Hodgkin lymphoma; pediatrics; response assessment; SUV

Publ.-Id: 16705 - Permalink

Suitability of bilateral filtering for edge-preserving noise reduction in PET
Hofheinz, F.; Langner, J.; Beuthien-Baumann, B.; Oehme, L.; Steinbach, J.; Kotzerke, J.; van den Hoff, J.;
Background: To achieve an acceptable signal-to-noise ratio (SNR) in PET images, smoothing filters (SF) are usually employed during or after image reconstruction preventing utilisation of the full intrinsic resolution of the respective scanner. Quite generally Gaussian-shaped moving average filters (MAF) are used for this purpose. A potential alternative to MAF is the group of so-called bilateral filters (BF) which provide a combination of noise reduction and edge preservation thus minimising resolution deterioration of the images. We have investigated the performance of this filter type with respect to improvement of SNR, influence on spatial resolution and for derivation of SUVmax values in target structures of varying size.
Methods: Data of ten patients with head and neck cancer were evaluated. The patients had been investigated by routine whole body scans (ECAT EXACT HR+, Siemens, Erlangen). Tomographic images were reconstructed (OSEM 6i/16s) using a Gaussian filter (full width half maximum (FWHM): Γ0 = 4 mm). Image data were then postprocessed with a Gaussian MAF (FWHM: ΓM = 7 mm) and a Gaussian BF (spatial domain: ΓS = 9 mm, intensity domain: ΓI = 2.5 SUV), respectively. Images were assessed regarding SNR as well as spatial resolution. Thirty-four lesions (volumes of about 1-100 mL) were analysed with respect to their SUVmax values in the original as well as in the MAF and BF filtered images.
Results: With the chosen filter parameters both filters improved SNR approximately by a factor of two in comparison to the original data. Spatial resolution was significantly better in the BF-filtered images in comparison to MAF (MAF: 9.5 mm, BF: 6.8 mm). In MAF-filtered data, the SUVmax was lower by 24.1 ± 9.9% compared to the original data and showed a strong size dependency. In the BF-filtered data, the SUVmax was lower by 4.6 ± 3.7% and no size effects were observed.
Conclusion: Bilateral filtering allows to increase the SNR of PET image data while preserving spatial resolution and preventing smoothing-induced underestimation of SUVmax values in small lesions. Bilateral filtering seems a
promising and superior alternative to standard smoothing filters.
Keywords: quantification, PET, SUVmax, bilateral filtering, spatial resolution, image filtering

Publ.-Id: 16704 - Permalink

Automatic volume delineation in oncological PET. Evaluation of a dedicated software tool and comparison with manual delineation in clinical data sets
Hofheinz, F.; Pötzsch, C.; Oehme, L.; Beuthien-Baumann, B.; Steinbach, J.; Kotzerke, J.; van den Hoff, J.;
Aim: Evaluation of a dedicated software tool for automatic delineation of 3D regions of interest in oncological PET. Patients, methods: The applied procedure encompasses segmentation of user-specified subvolumes within the tomographic data set into separate 3D ROIs, automatic background determination, and local adaptive thresholding of the background corrected data. Background correction and adaptive thresholding are combined in an iterative algorithm. Nine experienced observers used this algorithm for automatic delineation of a total of 37 ROIs in 14 patients. Additionally, the observers delineated the same ROIs also manually (using a freely chosen threshold for each ROI) and the results of automatic and manual ROI delineation were compared.
Results: For the investigated 37 ROIs the manual delineation shows a strong interobserver variability of (26.8±6.3)% (range: 15% to 45%) while the corresponding value for automatic delineation is (1.1±1.0)% (range: <0.1% to 3.6%). The fractional deviation of the automatic volumes from the observer-averaged manual ones is (3.7±12.7)%. Conclusion: The evaluated software provides results in very good agreement with observer-averaged manual evaluations, facilitates and accelerates the volumetric evaluation, eliminates the problem of interobserver variability and appears to be a useful tool for volumetric evaluation of oncological PET in clinical routine.

Publ.-Id: 16703 - Permalink

Change of SUV and metabolic volume products after use of rigid coregistration algorithms in F18-FDG-PET
Steffen, I. G.; Hofheinz, F.; Grosser, O. S.; Furth, C.; Denecke, T.; Plotkin, M.; Amthauer, H.; Ruf, J.;
Aim: Image fusion of anatomical and functional data is an established procedure in nuclear medicine. Whereas elastic image fusion is expected to alter the information of the transformed data, we assessed whether rigid transformations also change the information contained in the PET-data.
Methods: F-18-FDG-PET/CT (Biograph 16, Siemens Medical, Erlangen, Germany) data of 14 tumor patients with a total of 18 solid pulmonary lesions were included in this retrospective analysis. For coregistration, rigid fast (RF) and rigid slow (RS) transformation algorithms of the Fusion7d-software were employed (Fusion7d, Mirada Solutions Ltd./Siemens Medical, Erlangen, Germany). Original PET-images (voxel size: 0.417cm x 0.417cm x 0.5cm) were fused with the attenuation-corrected CT (LR, voxel size: 0.417cm x 0.417cm x 0.5cm) and diagnostic CT (HR, voxel size: 0.098cm x 0.098cm x 0.1cm).PET data were saved in the respective CT-geometry and CT-resolution. Segmentation of lesions was performed using a 3D ROI volume determination software with automatic background detection (Rover, ABX GmbH, Radeberg, Germany). SUVmax, SUVmean, volume and metabolic volumes (volume*SUVmax and volume*SUVmean) of the lesions were determined in the original and in the coregistered PET data and compared. SUVmax in original PET ranged from to 1.6-30.9 (mean±SD, 8.8±7.0). CT-segmented volumes ranged from 1-58 ml (mean±SD, 9.9±15 ml).
Results: The relative differences of volume between original data and rigid fast fused-data ranged from 2-45% (mean±SD, 19%±13%) for LR-coregistration and from 0-12% (mean±SD, 3%±3%) for HR-coregistration. Fusing data with the rigid slow algorithm resulted in relative volume differences ranging from 1-48% (mean±SD, 20%±18%) for LR-coregistration and from 0-14% (mean±SD, 4%±4%) for HR-coregistration. Analyzing relative differences of metabolic volume products (volume*SUVmax) between original data and rigid fast fused-data ranged from 0-33% (mean±SD, 12%±9%) for LR-coregistration and from 0-11% (mean±SD, 3%±3%) for HR-coregistration. After fusion with the rigid slow method differences of volume*SUVmax ranged from 0-41% (mean±SD, 13%±13%) for LR-coregistration and from 0-16% (mean±SD, 4%±5%).Conclusions:Transformation of PET data by rigid coregistration algorithms results in a redistribution of the respective voxel information in the new coordinate system. Volumetric analysis based on a source-to-background algorithm showed substantial differences between original and coregistered data, which may have a potential impact on e.g. PET-based planning of radiotherapy or the assessment of treatment response by measurement of metabolic burden in follow-up studies. This effect is dependent on the source data (CT) resolution. The extent of the observed effect on the data of modern high resolution PET-systems remains to be evaluated.
  • Poster
    Annual Congress of the European Association of Nuclear Mediciene (EANM) 2011, 15.-19.10.2011, Birmingham, UK
  • Abstract in refereed journal
    European Journal of Nuclear Medicine and Molecular Imaging 38(2011), S269

Publ.-Id: 16702 - Permalink

A method for model-free recovery correction in PET
Hofheinz, F.; Langner, J.; Will, E.; Oehme, L.; Beuthien-Baumann, B.; van den Hoff, J.;
Objectives : As is well known, limited spatial resolution leads to partial volume effects and consequently to limited signal recovery. Determination of the true activity concentration of a target structure is thus compromised even at target sizes much larger than the reconstructed spatial resolution. This leads to serioussize-dependent underestimates of true signal intensity in hot spotimaging. For quantitative PET in general and in the context of therapy assessment in particular it is therefore mandatory to perform an adequate recovery correction (RC). The goal of our work was to
developand to validate a model-free RC for hot spot imaging.
Methods : The algorithm proceeds in two steps. Step 1: automatic estimation of the true object volume V with an automatic thresholdbased method and the corresponding total activity A within V. Step 2:automatic determination of the background corrected activity fractionB, which is measured outside the object due to the partial volume effect. The recovery coefficient is then given by R = A/(A+B). For validation, we used a cylindrical phantom with six sphere inserts(volume: 2.5 - 27
ml) and performed measurements at three different target/background levels. RC was computed using the analytical convolution of the object function with the best fitting Gaussianpoint spread function and then compared to the results of the model-free approach.
Results : For the investigated target/background contrasts the model-free approach yields RC values which agree very well with the known (computable) RC values for the spheres (mean deviation +/-5%). The model-free nature of the approach allows, however, direct application to real patient data where the exact target shape is not known and model-based RC would fail.
Conclusions : The described method provides an easy and essentially automated way of doing quantitative RC in oncological hot spotimaging. It works well for sufficiently high contrast (>5) and a homogeneous background. The limits of the method have to be investigated further.
  • Poster
    Annual Congress of the European Association of Nuclear Medicine (EANM) 2011, 15.-19.10.2011, Birmingham, UK
  • Abstract in refereed journal
    European Journal of Nuclear Medicine and Molecular Imaging 38(2011), S268

Publ.-Id: 16701 - Permalink

Synthesis and Molecular Structure of tert-Butyl 4-(2-tert-butoxy-2-oxoethyl)piperazine-1-carboxylate
Mamat, C.; Flemming, A.; Köckerling, M.;
The crystal and molecular structure of tert-butyl 4-(2-tert-butoxy-2-oxoethyl)-piperazine-1-carboxylate is reported. The title compound crystallizes from a petroleum ether/ethyl acetate mixture in the monoclinic space group P 21/c with four molecules in the unit cell. The unit cell parameters are: a = 8.4007(2) Å, b = 16.4716(4) Å, c = 12.4876(3) Å; β = 90.948(1)° and V = 1727.71(7) Å3. Bond lengths and angles of this piperazine-carboxylate are typical.
Keywords: piperazines; building blocks; X-ray structure

Publ.-Id: 16700 - Permalink

The Synthesis and Molecular Structure of 2-(4-Methoxybenzyl)-4-nitro-2H-indazole
Ebert, K.; Köckerling, M.; Mamat, C.;
Two novel indazole derivatives protected with p-methoxybenzyl group were synthesized and characterized. The crystal and molecular structure of 2-(4-methoxybenzyl)-4-nitro-2H-indazole as one out of the two regioisomers is reported. The compound was obtained from a saturated petroleum ether/ethyl acetate mixture and crystallizes in the triclinic space group P`1. The unit cell parameters are: a = 6.8994(1) Å, b = 9.8052(2) Å, c = 11.1525(2) Å; α = 71.729(1)°, β = 79.436(1)°, γ = 74.349(1)° and V = 685.83(2) Å3. There are two independent molecules found in the asymmetric unit.
Keywords: indazoles; protecting group; p-methoxy benzyl; X-ray structure

Publ.-Id: 16699 - Permalink

Effect of the processing of embedded Ge nanocrystals upon the Si-SiO2 interface state and border trap density
Beyer, R.; Burghardt, H.; von Borany, J.;
  • Lecture (Conference)
    14th European Conference on Applications of Surface and Interface Analysis (ECASIA'11), 05.09.2011, Cardiff, Wales

Publ.-Id: 16697 - Permalink

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