Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf
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42029 Publikationen
Status of the Leopard Laser Project in Nevada Terawatt Facility
Wiewior, P.; Astanovitskiy, A.; Aubry, G.; Batie, S.; Caron, J.; Chalyy, O.; Cowan, T.; Haefner, C.; Le Galloudec, B.; Le Galloudec, N.; Macaulay, D.; Nalajala, V.; Pettee, G.; Samek, S.; Stepanenko, Y.; Vesco, J.
Abstract
Nevada Terawatt Facility (NTF) currently operates a high-intensity laser systemLeopard. NTF already operates a powerful z-pinch device, called Zebra, for plasma and High Energy Density physics research. The unique research opportunities arise from the combination of NTFs terawatt Zebra z-pinch with 50-terawatt-class Leopard laser. This combination also provides opportunities to address fundamental physics of inertial fusion and high energy density physics with intense laser beam. We report on the status, design and architecture of the Leopard laser project. A first experiments carried out with Leopard will be also briefly mentioned.
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Journal of Fusion Energy 28(2009), 218-220
DOI: 10.1007/s10894-008-9176-8
Cited 3 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13339
Importance of magnetic resistive fields in the heating of a micro-cone target irradiated by a high intensity laser
DHumières, E.; Rassuchine, J.; Baton, S.; Fuchs, J.; Guillou, P.; Koenig, M.; Gremillet, L.; Rousseaux, C.; Kodama, R.; Nakatsutsumi, M.; Norimatsu, T.; Batani, D.; Morace, A.; Redaelli, R.; Dorchies, F.; Fourment, C.; Santos, J. J.; Adams, J.; Korgan, G.; Malekos, S.; Cowan, T. E.; Sentoku, Y.
Abstract
Obtaining keV ion temperatures at solid density, i.e. warm dense matter, in the laboratory would be of great interest to measure opacity and equations of state of matter under extremes conditions. Here we report a new means to effectively confine the energetic electrons and localize the energy deposition to a small, more uniformly heated, volume at the tip of nanofabricated micro-cone targets. This is achieved with very high contrast laser irradiation, which interacts with the cone wall to generate strong (~10 MG) localized resistive magnetic fields within the target bulk. Temperatures of up to ~200 eV are observed, with an input laser energy of 10 J. This new means has been investigated both experimentally and with Particle-In-Cell simulations.
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European Physical Journal - Special Topics 175(2009), 89-95
DOI: 10.1140/epjst/e2009-01123-6
Cited 2 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13338
THEREDA in an European context - comparison of thermodynamic databases
Brendler, V.
Abstract
- wird nachgereicht
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Vortrag (Konferenzbeitrag)
10. Koordinierungsgespräch FZD/IRC - PSI/LES, 28.-29.10.2009, Villigen, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-13337
Neues zur Fluoreszenz von Actiniden
Geipel, G.
Abstract
- wird nachgereicht
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Vortrag (Konferenzbeitrag)
10. Koordinierungsgespräch FZD/IRC - PSI/LES, 28.-29.10.2009, Villigen, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-13336
Reaction of Pu(IV) and Pu(III) with Fe minerals under anoxic conditions - XANES and EXAFS results
Kirsch, R.
Abstract
- wird nachgereicht
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Vortrag (Konferenzbeitrag)
10. Koordinierungsgespräch FZD/IRC - PSI/LES, 28.-29.10.2009, Villigen, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-13335
Characterization of an uranium accumulating plant in its terrestrial ecosystem and under laboratory conditions
Viehweger, K.
Abstract
- wird nachgereicht
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Vortrag (Konferenzbeitrag)
10. Koordinierungsgespräch FZD/IRC - PSI/LES, 28.-29.10.2009, Villigen, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-13334
Uranium(IV) colloids in near-neutral solutions - Preparation and stability
Dreissig, I.
Abstract
- wird nachgereicht
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Vortrag (Konferenzbeitrag)
10. Koordinierungsgespräch FZD/IRC - PSI/LES, 28.-29.10.2009, Villigen, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-13333
Influence of calcite on the sorption of U(VI) and HA onto Opalinus clay
Joseph, C.
Abstract
- wird nachgereicht
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Vortrag (Konferenzbeitrag)
10. Koordinierungsgespräch FZD/IRC - PSI/LES, 28.-29.10.2009, Villigen, Schweiz
Permalink: https://www.hzdr.de/publications/Publ-13332
Transition metal sulfide clusters below the cluster-platelet transition theory and experiment
Gemming, S.; Seifert, G.; Götz, M.; Fischer, T.; Ganteför, G.
Abstract
The structural and electronic properties of neutral and anionic molybdenum sulfide clusters with the composi-tion Mo3Sn (n=0-12) were studied by density-functional calculations. The theoretical results are confirmed by a comparison with photoelectron spectra of the correspond-ing W3Sn- anions providing experimental values for the vertical detachment energies and the HOMO-LUMO gaps. For sulfur contents up to n=9 the clusters are com-posed of a central Mo3 unit, which is decorated by bridg-ing, terminal and three-fold coordinated S atoms. For n>9, a cleavage of the Mo3 center is observed. The formation of disulfide like ions is found for Mo3S9 and larger spe-cies. In accordance with investigations of MoSn, Mo2Sn and Mo4Sn clusters, the heat of formation and the vertical detachment energy reaches a maximum in the sulfur-rich region beyond the composition Mo : S = 1 : 2.
Keywords: molybdenum sulfide; clusters; density-functional; pulsed-arc; HOMO-LUMO gap; tungsten sulfide
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Physica Status Solidi (B) 247(2010), 1069-1076
DOI: 10.1002/pssb.200945480
ISSN: 1521-3951
Cited 17 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13331
Adsorption of nucleotides on the rutile (110) surface
Gemming, S.; Enyashin, A.; Frenzel, J.; Seifert, G.
Abstract
The present study aims at the computer-aided design of suitably functionalizedoxide surfaces for the integration of nanotubes into multi-purpose nano-electronic devices. The adsorption of cytidine monophosphate on the rutile(110) surface is investigated by density-functional-based tight-binding calculations. The most favorable amchoring of the nucleotide is bidentate via oxygen sites of the phosphate part. Adsorption occurs preferentially at two neighboring five-fold coordinated Ti atoms along the [001] direction, thus opening a pathway to an ordered adsorption of nanotubes along [001]. The electronic densities of states show that the aromatic part of the cytidine part remains unchanged upon adsoption on rutile. This implies that no significant changes occur in the nanotube binding capacity by pi-stacking of the aromatic part, hence, nucleotide-functionalized oxide surfaces are ideal substrates for the ordered, stable and electronically and chemically inert immobilization of nanotubes.
Keywords: CNT; DNA; nanotube; nucleotide; surface functionalization; rutile; adsorption; chemisorption
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International Journal of Materials Research 101(2010), 758-764
DOI: 10.3139/146.110337
ISSN: 1862-5282
Cited 26 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13330
Electric field mediated switching of mechanical properties of strontium titanate at room temperature
Stöcker, H.; Zschornak, M.; Leisegang, T.; Shakhverdova, I.; Gemming, S.; Meyer, D. C.
Abstract
In situ application of an electric field to a SrTiO3 single crystal plate during nanoindentation led to a reversible change of the mechanical properties at room temperature. When a field of 8 kV/cm was applied, Meyer hardness and Young's modulus decreased by 0.6 GPa and 11 GPa, respectively. An explanation for this behaviour is given by the diffusion of oxygen vacancies resulting in a distortion of the perovskite-type of structure in the near-surface layer tested by nanoindentation. Simulations using density functional theory support the dependence of elasticity on the presence of vacancies. Thus, we can show the remarkable influence of electric fields on oxide materials which should be considered and used in designing future applications.
Keywords: strontium titanate; functional oxide; mechanical properties; density-functional; hardness; vacancy; point defect
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Crystal Research and Technology 45(2010), 13-17
DOI: 10.1002/crat.200900612
ISSN: 1521-4079
Cited 17 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13329
Surface Nanostructures Induced by Low Energy Ion Sputtering
Facsko, S.; Keller, A.; Ranjan, M.; Möller, W.
Abstract
Under special conditions low energy ion sputtering of solid surfaces leads to the formation of regular nanopatterns. These surfaces represent an interesting example of spontaneous pattern formation in nonequilibrium systems exhibiting different features like wavelength coarsening or a transition to spatiotemporal chaos. Different pattern types are observed for different experimental conditions, i.e. wavelike ripple patterns and hexagonally ordered dot arrays under oblique and normal ion incidence, respectively [1]. These patterns have gained increasing interest in recent years as templates for thin film growth. According to the model of Bradley and Harper (BH) [2], the regular patterns result from the competition between curvature dependent roughening and smoothing of the surface. Since the local erosion rate is higher in the valleys than on crests, the eroded surface is unstable. In the presence of smoothing mechanisms, however, a wave vector selection occurs and a periodic pattern with one spatial frequency is observed. The pattern formation can be described by continuum equations based on the BH model. Several extensions have been proposed in the last years, with the stochastic Kuramoto-Sivashinsky (KS) equation being the most prominent one [3]. However, although most experimental investigations on ion-induced pattern formation were performed under oblique ion incidence, only few theoretical studies focused on the corresponding anisotropic KS (aKS) equation. We will also present studies of thin film growth on these patterns. Depending on the interface energy of the metal film with the substrate the films grow in a conformal way reproducing the surface topography or as nanoparticles on the substrate surface. Furthermore, depending on deposition angle, substrate temperature, beam flux, and deposition time, the nanoparticles align parallel to the ripples, eventually coalescing and forming nanowires. Metal thin films grown in this way exhibit distinct optical properties due to their localized surface plasmon resonance. Because of the alignment these nanoparticles exhibit a strongly anisotropic plasmonic resonance [4]. In addition, the magnetic properties of ferromagnetic thin films grown on rippled surfaces are drastically change by the presence of the interface and surface periodic roughness [5].
[1] W. L. Chan and E. Chason, J. Appl. Phys. 101, 121301 (2007)
[2] R. Bradley and J. Harper, J. Vac. Sci. Technol. A 6, 2390 (1988)
[3] R. Cuerno and A.-L. Barabási, Phys. Rev. Lett. 74 4746 (1995)
[4] T.W.H. Oates, A. Keller, S. Facsko, et al., Plasmonics 2, 47 (2007).
[5] M. O. Liedke, B. Liedke, A. Keller, et al., Phys. Rev. B 75, 220407 (2007).
Keywords: ion beam sputtering; self-organized nanostructures
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Eingeladener Vortrag (Konferenzbeitrag)
International Conference on Metallurgical Coatings and Thin Films, 26.-30.04.2010, San Diego, USA
Permalink: https://www.hzdr.de/publications/Publ-13328
Self-aligned metal nanoparticles and nanowires grown on ripple-templates
Facsko, S.; Ranjan, M.; Keller, A.; Oates, T. W. H.; Rosen, J.
Abstract
Nobel metal nanoparticles exhibit distinct optical properties due to their localized surface plasmon resonance. They are used nowadays in various applications, like solar cells, nonlinear optical devices or sensors. Especially for nanoscale optics aligned equidistant chains of metal nanoparticles are favored [1]. Ion beam sputtered surfaces featuring self-organized ripple patterns are excellent templates for the alignment of these metal nanoparticles. Depending on deposition angle, substrate temperature, beam flux, and deposition time, the nanostructures align parallel to the ripples, eventually coalescing and forming nanowires [2]. Because of alignment the nanoparticles exhibit a strongly anisotropic plasmonic resonance [3]. We will present how Ag nanoparticles grow and align on ion beam rippled Si surfaces and how the optical properties depend on their shape, size, and alignment.
[1]S.A. Maier and H.A. Atwater, Jour. Appl. Phys. 98, 011101 (2005).
[2]T.W.H. Oates, A. Keller, S. Noda, et al., Appl. Phys. Lett. 93 (2008).
[3]T.W.H. Oates, A. Keller, S. Facsko, et al., Plasmonics 2, 47 (2007).
Keywords: self-aligned clusters; ripple pattern; anostructures
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Eingeladener Vortrag (Konferenzbeitrag)
MRS Fall Meeting, 29.11.-4.12.2009, Boston, USA
Permalink: https://www.hzdr.de/publications/Publ-13327
Selbstorganisierte Nanostrukturierung von Oberflächen mittels Ionenstrahlen
Facsko, S.; Keller, A.; Ranjan, M.
Abstract
Oberflächen und Grenzflächen spielen eine große Rolle in allen technologischen Bereichen. Kaum eine Anwendung kommt ohne Materialien aus, die aus Mehrfachschichten aufgebaut sind oder funktionale Oberflächen aufweisen. Die Herstellung und Erforschung dieser funktionalen Oberflächen bzw. Schichten mit Strukturen im Submikrometerbereich wurde deshalb in den letz-ten Jahren verstärkt vorangetrieben, da eine steigenden Nachfrage in der mikro- und optoe-lektronischen Industrie nach derartigen Strukturen zu erwarten ist. Zwei komplementäre Ansätze existieren zur Erzeugung von Nanostrukturen: Der Top-down- und der Bottom-up-Ansatz.
Der Top-down-Ansatz umfasst konventionelle Techniken wie optische oder Elektronen¬stahllithographie kombiniert mit Übertragung der geschriebenen Strukturen, während der Bot-tom-up-Ansatz Selbstorganisationsphänomene an Oberflächen oder beim Wachstum dünner Schichten ausnutzt. Die Ionenerosion von Festkörperoberflächen mit niederenergetischen Ionen ist eine vielversprechende Bottom-up-Methode zur Herstellung großflächiger Felder von Na-nostrukturen [1]. Diese Methode und Anwendungen, die darauf basieren, werden im Folgenden vorgestellt.
Keywords: surface nanostructures; ion beam sputtering
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Beitrag zu Proceedings
Mikro- und Nanosrtukturen an Oberflächen - Herstellung und Anwendungen, 9.10.2009, Dresden, Deutschland
Selbstorganisierte Nanosrtukturierung von Oberflächen mittels Ionenstrahlen
Permalink: https://www.hzdr.de/publications/Publ-13326
Analsyis of the spatial isotopic distributions during the burnup of UMOX- and ThMOX-fuels on unit cell basis
Merk, B.; Scholl, S.; Fridman, E.
Abstract
A detailed analysis of the plutonium burning in a representative PWR fuel pin is performed for comparison of the ThMOX and UMOX fuel performance. Special effort is made in the analysis of the changes in the spatial distribution of isotope concentrations during the burnup in a representative LWR fuel pin. This unique analysis of the changes in the spatial particle densities gives a new insight into the system behaviour. The different ways of plutonium breeding and reduction for the major isotopes of the two considered fuels are analyzed and discussed. Finally, the advantages and limitations of the use of Thorium based MOX fuel for the burning of plutonium are discussed. The calculations are performed with the licensing grade code module HELIOS 1.9.
Keywords: plutonium reduction; thorium fuels; actinide transmutation; PWRs
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Beitrag zu Proceedings
PHYSOR 2010, 09.-14.05.2010, Pittsburgh, USA -
Vortrag (Konferenzbeitrag)
PHYSOR 2010, 09.-14.05.2010, Pittsburgh, USA
Permalink: https://www.hzdr.de/publications/Publ-13325
A solution for the telegraphers equation with external source: application to YALINA - SC3A and SC3B
Merk, B.; Glivici-Cotruta, V.; Weiß, F. P.
Abstract
This work represents the detailed comparison of the analytical solutions for the space and time Telegraphers equations with the experimental results, obtained for the YALINA-Booster subcritical facility in 2008. The derivation of analytical solution for the Telegraphers equation with a special temporal shape of the external source is described. The Greens function method was applied. Qualitative results of the obtained solutions and the experimental results are analyzed. The special configuration of the YALINA-Booster facility is discussed.
Keywords: Yalina; experimental analysis; Greens function; Telegraphers equation
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Beitrag zu Proceedings
PHYSOR 2010, 09.-14.05.2010, Pittsburgh, USA -
Vortrag (Konferenzbeitrag)
PHYSOR 2010, 09.-14.05.2010, Pittsburgh, USA
Permalink: https://www.hzdr.de/publications/Publ-13324
Radiation enhanced diffusion in germanium
Schneider, H.; Bracht, H.; Klug, J. N.; Lundsgaard Hansen, J.; Bourgeard, D.; Liao, C. Y.; Haller, E. E.; Posselt, M.; Wündisch, C.
Abstract
Ge isotope heterostructures were irradiated with 2.5 MeV protons at temperatures between 550°C and 640°C. The applied proton flux was varied up to 3.8 μA per cm2. Secondary ion mass spectroscopy (SIMS) was utilized to record concentration profiles of the Ge-isotopes after the irradiation treatment. The SIMS profiles show a homogenous broadening of the multilayer structure. Continuum theoretical simulations were performed which are based on diffusion models that consider the formation of Frenkel-defects and their annihilation. Best fits to the experimental profiles are obtained when the boundary conditions for vacancies and self-interstitials are assumed differently. Ge self-interstitials are reflected at the surface, whereas the concentration of Ge vacancies approaches the thermal equilibrium value. To check these boundary conditions, experiments on the diffusion of n-type dopants under irradiation were performed.
Keywords: germanium diffusion irradiation
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Vortrag (Konferenzbeitrag)
25th International Conference on Defects in Semiconductors (ICDS-25), 20.-24.06.2009, St. Petersburg, Russia
Permalink: https://www.hzdr.de/publications/Publ-13323
Mikroskopische Aufnahmen neu gedeutet - Revolution in der Raster-Kelvin-Mikroskopie?
Baumgart, C.; Schmidt, H.
Abstract
In den letzten Jahren hat die Mikroskopie enorme Fortschritte gemacht. Moderne Mikroskope können Moleküle dreidimensional abbilden, kleinste Strukturen bis hin zu einzelnen Atomen erkennen und vor allem auch unterschiedliche Arten von Atomen sicher voneinander unterscheiden. Die "Raster-Kelvin-Mikroskopie" ist eine besondere Technik der Rasterkraft-Mikroskopie, wobei die ihr zugrunde liegende Methode auf Lord Kelvin zurück geht. Sie kam 1991 auf den Markt. Mit dem Raster-Kelvin-Mikroskop wurde eine wissenschaftliche Erklärung mitgeliefert, wie die Aufnahmen zu interpretieren seien. Daran rüttelt nun die Physikerin Christine Baumgart, die in der "Nanospintronik-Gruppe" am Forschungszentrum Dresden-Rossendorf (FZD) promoviert.
- GIT Labor-Fachzeitschrift 53(2009), 680-681
Permalink: https://www.hzdr.de/publications/Publ-13322
Heavily Ga-doped Germanium Layers Produced by Ion Implantation and Flash Lamp Annealing - Structure and Electrical Activation
Heera, V.; Mücklich, A.; Posselt, M.; Voelskow, M.; Wündisch, C.; Schmidt, B.; Skrotzki, R.; Heinig, K. H.; Herrmannsdörfer, T.; Skorupa, W.
Abstract
Heavily p-type doped Ge layers were fabricated by 100 keV Ga implantation and subsequent flash lamp annealing for 3 ms in the temperature range between 700°C and 900°C. For comparison some samples were annealed in a rapid thermal processor for 60 s. Ga fluences of 2x1015cm-2, 6x1015cm-2 and 2x1016cm-2 were chosen in order to achieve Ga peak concentrations ranging from values slightly below the equilibrium solid solubility limit of 4.9x1020 cm-3 up to 3.5x1021 cm-3 which corresponds to a maximum Ga content of about 8 at-%. The structure of the doped layer and the Ga distribution were investigated by Rutherford backscattering spectrometry in combination with ion channelling, cross-sectional electron microscopy and secondary ion mass spectrometry. Temperature dependent Hall effect measurements were carried out in order to determine the electrical properties of the Ga doped layers. It is shown that by flash lamp annealing Ga diffusion into the bulk can be completely avoided and the Ga loss by outdiffusion from the surface is reduced. The lowest sheet resistances of 36 Ohm/sq. was achieved for the medium Ga concentration annealed at 900°C. The best Ga activation values are 73%, 60% and 24% for the three Ga fluences under investigation. The Ga activation is correlated with the layer regrowth. Incomplete epitaxial regrowth as observed in some samples leads to lower activation.
Keywords: Germanium; Ga implantation; electrical activation; flash lamp annealing; rapid thermal annealing; Hall effect measurements
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Journal of Applied Physics 107(2010), 053508-1-053508-8
DOI: 10.1063/1.3309835
Cited 42 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13321
Novel and compact accelerator concepts for radiation therapy
Schramm, U.; Cowan, T. E.; Bock, S.; Bussmann, M.; Debus, A.; Erler, C.; Illing, R.; Jochmann Metzges, J.; Kluge, T.; Kraft, S.; Kroll, F.; Richter, C.; Richter, T.; Seidl, W.; Siebold, M.; Wünsch, R.; Schwoerer, K.; Liesfeld, B.; Amthor, K.-U.; Ziegler, W.; Jäckel, O.; Pfotenhauer, S.; Podleska, S.; Bödefeld, R.; Hein, J.; Polz, J.; Ronneberger, F.; Schlenvoigt, H.-P.; Beleites, B.; Sauerbrey, R.
Abstract
scaling (optimizing) of conventional techniques
novel techniques: dielectric wall accelerators
new concepts: laser plasma acceleration and
local beam guiding systems
Beteiligte Forschungsanlagen
- Hochfeld-Magnetlabor (HLD)
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Eingeladener Vortrag (Konferenzbeitrag)
440th WE Heraeus Seminar,, 14.09.2009, Frauenwörth, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13320
Die Kraft des Lichts
Sauerbrey, R.
Abstract
Wenn die Intensität von Laserlicht, das mit Materie wechselwirkt, 1018 W/cm2 übersteigt, wird die Bewegung der Elektronen im Laserfeld relativistisch. Dies führt zu einer Vielzahl neuer optischer Effekte, die unter dem Namen Relativistische Optik zusammengefasst werden. Der vielleicht wichtigste und zurzeit am meisten diskutierte neue Effekt, der in diesem Zusammenhang auftritt, ist die effiziente Laserbeschleunigung von Elektronen und Ionen. Mit Hochintensitätslasern kann man heute monochromatische Elektronenstrahlen mit Energien bis zu 1 GeV erzeugen. Kürzlich wurden auch monoenergetische Ionenstrahlen im MeV-Bereich durch Hochintensitätslaser erzeugt. In dem Vortrag werden die Mechanismen der Laser Teilchenbeschleunigung im Zusammenhang mit nun möglich erscheinenden Anwendungen dieser Teilchenstrahlen in der Medizin diskutiert.
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Sonstiger Vortrag
Kolloquium, 26.01.2009, Bochum, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13319
A solution for the Telegraphers equation with external source: development and first application
Merk, B.; Glivici-Cotruta, V.; Weiß, F. P.
Abstract
This work represents the detailed comparison of the analytical solutions for the space and time dependent diffusion and Telegraphers equations to the experimental results, obtained for the YALINA-Booster subcritical facility during the experimental campaign in 2008. The derivation of analytical solution for the Telegraphers equation with a special temporal shape of the external source (switch on followed by a switch off after a finite time period) is described. The Greens function method was applied. Qualitative results of the obtained solutions and the experimental results are analyzed.
The special configuration of the YALINA-Booster facility is discussed.
Keywords: Yalina; subcritical system; Telegrapher's equation; Green's function; experimental analysis
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Il Nuovo Cimento della Societa Italiana di Fisica B 125(2010)12, 1547-1559
DOI: 10.1393/ncb/i2010-10948-5
Cited 4 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13318
Domain-wall pinning and depinning at soft spots in magnetic nanowires
Vogel, A.; Wintz, S.; Moser, J.; Bolte, M.; Strache, T.; Fritzsche, M.; Im, M.-Y.; Fischer, P.; Meier, G.; Fassbender, J.
Abstract
The local modification of magnetic properties by ion irradiation opens the possibility to create pinning sites for domain walls in magnetic nanowires without geometric constrictions. Implantation of chromium ions into Ni80Fe20 nanowires is used to cause a local reduction of the saturation magnetization Ms and thus a decrease of the exchange energy associated with the domain wall. Field-driven pinning and depinning of a domain wall at the here so-called magnetic soft spots is directly observed using magnetic transmission soft X-ray microscopy. The pinning rate and the depinning field considerably depend on the wire width and the chromium fluence.
Keywords: Domain walls and domain structure; Intrinsic properties of magnetically ordered materials; Magnetic properties of nanostructures; Magnetization reversal mechanisms
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Poster
MML 2010 - IEEE 7th International Symposium on Magnetic Multilayers, 19.-24.09.2010, Berkeley, USA - IEEE Transactions on Magnetics 46(2010)6, 1708-1710
Permalink: https://www.hzdr.de/publications/Publ-13317
Untersuchung von Chlorophyllspezies in uranhaltigen Pflanzen
Woitha, D.
Abstract
In der vorliegenden Arbeit wurde die Auswirkung von Uran speziell auf Chlorophyll a und Chlorophyll b untersucht. Die Messungen erfolgten mittels HPLC-Analytik, mit photometrischen Messungen und Dünnschichtchromatographie. Es wurden die Absorptionsmaxima sowie die Retentionszeiten der Pigmente bestimmt. Den Untersuchungen lag die Frage zugrunde, ob ein Austausch des zentralen Magnesiums aus dem Chlorophyll-Molekül durch Uran möglich ist. Für die Messungen standen Proben von Löwenzahn und Arabidopsis zur Verfügung. Neben den hydroponisch herangezogenen Arabidopsis-Kulturen (mit und ohne Uranylnitrat in der Nährlösung) wurden auch Pflanzen einer unsanierten Uranerzhalde in Johanngeorgenstadt untersucht.
Die Messung von bioverfügbarem Uran in den Bodenproben aus Johanngeorgenstadt und die Akkumulation von 5 μg Uran pro g Frischgewicht in den Pflanzenblättern stellt die Voraussetzung eines Austausches von Magnesium gegen Uran im Chlorophyll-Molekül dar. Anhand der Chromatogramme und der Absorptionsspektren ließen sich jedoch keine Anzeichen für eine Modifikation des Chlorophylls identifizieren.
Keywords: Uran; Chlorophyll; Arabidopsis
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Bericht, sonstiger
Masterarbeit (Studiengang Biotechnologie): HS Anhalt, 2009
77 Seiten
Permalink: https://www.hzdr.de/publications/Publ-13316
Measuring the Saturation Magnetization in Samples with Unknown Magnetic Volume due to Intermixing by Ion Irradiation
Markó, D.; Lenz, K.; Strache, T.; Kaltofen, R.; Fassbender, J.
Abstract
We present a method to determine the saturation magnetization of samples for which the magnetic volume is unknown and thus cannot be calculated from the magnetic moment. This can happen, e.g., in multilayers, where the spacer material is likely to cause intermixing or whenever ion irradiation is used to modify the magnetic properties of samples on purpose. In both cases the active magnetic volume is altered from its nominal value in unknown manner. Therefore magnetometry like supraconducting quantum interference devices (SQUID) or vibrating sample magnetometry (VSM) fail, because they detect the magnetic moment but do not provide information on the respective magnetic volume. In this article we have used thin films of Permalloy (Py) and Py/Ta multilayers. Some of the Py/Ta samples were irradiated with Ne ions in order to modify the interfacial mixing. The saturation magnetization is determined by ferromagnetic resonance (FMR).
Keywords: Ferromagnetic Resonance; Saturation Magnetization; Ion Irradiation; Intermixing
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Beitrag zu Proceedings
MMM/Intermag, 18.-22.01.2010, Washington DC, USA
IEEE Transactions on Magnetics 46(2010)6, 1711-1714
Permalink: https://www.hzdr.de/publications/Publ-13315
Mode-locking via active gain modulation in quantum cascade lasers
Kuznetsova, L.; Wang, C. Y.; Gkortsas, V. M.; Diehl, L.; Kärtner, F.; Belkin, M. A.; Belyanin, A.; Li, X.; Ham, D.; Schneider, H.; Liu, H. C.; Capasso, F.
Abstract
A mode-locking mechanism by active gain modulation is studied numerically and experimentally. The parameter window for the emission of stable pulse trains was found. Pulses as short as 3ps (~0.5pJ) were characterized by second-order autocorrelation.
Keywords: Infrared and far-infrared lasers; mode-locked lasers; semiconductor lasers; quantum cascade lasers
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Vortrag (Konferenzbeitrag)
Conference on Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference. CLEO/QELS 2009, 02.-04.06.2009, Baltimore, MD, USA -
Beitrag zu Proceedings
Conference on Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference, CLEO/QELS 2009, 02.-04.06.2009, Baltimore, MD, USA
Proc. CLEO/QELS 2009 Persistent Link (OPAC): http://ieeexplore.ieee.org/servlet/opac?punumber=5197900
Permalink: https://www.hzdr.de/publications/Publ-13314
Recent results at LULI on fast electron transport with and without guiding cone in the context of fast ignitor
Baton, S. D.; Koenig, M.; Fuchs, J.; Gremillet, L.; Rousseaux, C.; Batani, D.; Morace, A.; Nakatsutsumi, M.; Kodama, R.; Norimatsu, T.; Nishida, A.; Dorchies, F.; Fourment, C.; Santos, J. J.; Rassuchine, J.; Cowan, T.
Abstract
We present experimental and numerical results obtained at LULI (Laboratoire pour lUtilisation des Lasers intenses) on propagation and energy deposition of laser-generated fast electrons into conical targets. The experimental measurements were performed by means of several diagnostics in order to assess the predicted benefit of conical targets over standard planar ones. Various configurations have been tried, regarding the laser parameters with the aim of optimizing the laser-to-target coupling. Our best results have been obtained when the laser was frequency-doubled at 0.53 μm, corresponding to interaction conditions without laser pedestal due to the ASE (Amplified Spontaneous Emission). Our data pinpoint the detrimental influence of the pre-plasma generated by the laser pedestal at 1.057 μm, whose confinement is enhanced in conical geometry as evidenced by shadowgraphic measurements which is also confirmed by 2D Cu-Ka transverse images obtained from Cu cones. The consequence is the filling of the cone, preventing the laser beam from efficiently reaching the cone tip. These experimental results are compared to 2D PIC simulations modeling of the laser-cone interaction.
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European Physical Journal - Special Topics 175(2009), 77-82
DOI: 10.1140/epjst/e2009-01121-8
Permalink: https://www.hzdr.de/publications/Publ-13313
Betriebserfahrungen mit der 40-MW-Photovoltaik-Anlage Waldpolenz
Rindelhardt, U.; Fröhler, D.
Abstract
Deutschlands bis dahin größte Photovoltaikanlage (PVA) wurde von 2007 bis 2008 in der Nähe von Leipzig errichtet und schrittweise in Betrieb genommen. Sie befindet sich auf einer militärischen Konversionsfläche. Die PVA ist auf einer Fläche von ca. 120 Hektar mit insgesamt 589000 rahmenlosen CdTe-Modulen von First Solar (Leistung zwischen 65 und 75 W) ausgerüstet, die gesamte Modulfläche liegt bei etwa 40 Hektar. Jeweils 45 Module sind auf einen Tisch montiert und elektrisch zu 5 Strings verschaltet. Die 12440 Tische bestehen aus Aluminium-Profilen mit eingerammten Pfosten.
Betriebsergebnisse der PVA Waldpolenz wurden für die Jahre 2008 und 2009 ausgewertet. Der saisonale Verlauf der Erträge folgt den jeweiligen Einstrahlungen. Die Jahreserträge entsprechen den Erträgen von ertragstarken benachbarten PVA mit kristallinen Modulen. Auffallend sind die hohen PR-Werte der PVA (Jahr 2008: 90 %).
Keywords: photovoltaic; CdTe module; pv plant; performance
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Beitrag zu Proceedings
25. Symposium Photovoltaische Solarenergie, 03.-05.03.2010, Staffelstein, Deutschland
25. Symposium Photovoltaische Solarenergie, Regensburg: Otti, 978-3-941785-23-6, 152-157 -
Poster
25. Symposium Photovoltaische Solarenergie, 03.02.-05.03.2010, Staffelstein, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13312
Laufwasserkraftwerke an der Saale
Rindelhardt, U.
Abstract
Die Arbeit beschreibt den Stand und die Perspektiven der Wasserkraftnutzung an der Saale in Thüringen und Sachsen-Anhalt. Das Arbeitsvermögen der derzeit bestehenden 33 Wasserkraftanlagen beträgt 120 GWh/a, dazu kommen 110 GWh/a regenerative Stromerzeugung aus den Pumpspeicherwerken Bleiloch und Hohenwarthe. Unter den derzeitigen Rahmenbedingungen ist ein Zubau um etwa 22 GWh/a möglich.
Keywords: Hydro power plants; Saale river
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Wassertriebwerk 58(2009)12, 231-240
ISSN: 0509-8858
Permalink: https://www.hzdr.de/publications/Publ-13311
The molecular dynamics simulation of ion-induced ripple growth
Sule, P.; Heinig, K.-H.
Abstract
The wavelength-dependence of ion-sputtering induced growth of repetitive nanostructures, such as ripples has been studied by molecular dynamics (MD) simulations in Si. The early stage of the ion erosion driven development of ripples has been simulated on prepatterned Si stripes with a wavy surface. The time evolution of the height function and amplitude of the sinusoidal surface profile has been followed by simulated ion-sputtering. According to Bradley-Harper (BH) theory, we expect correlation between the wavelength of ripples and the stability of them. However, we find that in the small ripple wavelength regime BH theory fails to reproduce the results obtained by molecular dynamics. We find that at short wavelengths < 35 nm the adatom yield drops hence no surface diffusion takes place which is sufficient for ripple growth. The MD simulations predict that the growth of ripples with wavelengths > 35 nm are stabilized in accordance with the available experimental results. According to the simulations, few hundreds of ion impacts in wavelength-long and few nm wide Si ripples are sufficient for reaching saturation in surface growth for wavelengths > 35 nm ripples. In another words, ripples in the long wavelength limit seems to be stable against ion-sputtering. A qualitative comparison of our simulation results with recent experimental data on nanopatterning under irradiation is attempted.
Keywords: surface patterning; self-organisation; ion erosion; computer simulation; molecular dynamics
- Journal of Chemical Physics 131(2009)20, 204704
Permalink: https://www.hzdr.de/publications/Publ-13310
Monte Carlo simulations of ion channeling in crystals containing extended defects
Turos, A.; Nowicki, L.; Stonert, A.; Pagowska, K.; Jagielski, J.; Muecklich, A.
Abstract
Monte Carlo simulations code of ion channeling in crystals containing extended defects has been developed. Bent channel model of lattice distortions produced by dislocations have been used for defect analysis in ion implanted GaN. To test the code energy dependence of dechanneling parameter has been calculated for crystals containing randomly displaced atoms and bent channels. It follows the 1/E and E1/2 dependence, respectively.
Keywords: Rutherford backscattering; ion channeling; Monte Carlo simulations; GaN epitaxial layers; ion bombardment; extended defects
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Vortrag (Konferenzbeitrag)
19th International Conference on Ion Beam Analysis, 07.-11.09.2009, Cambridge, United Kingdom -
Nuclear Instruments and Methods in Physics Research B 268(2010)11-12, 1718-1722
DOI: 10.1016/j.nimb.2010.02.046
Cited 31 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13309
Some lessons learned from the use of two-phase CFD for nuclear reactor thermalhydraulics
Bestion, D.; Lucas, D.; Boucker, M.; Anglart, H.; Tiselj, I.; Bartosiewicz, Y.
Abstract
Two-phase Computational Fluid Dynamics (2-phase CFD) is now increasingly applied to some Nuclear Reactor thermalhydraulic investigations. The main purpose of this paper is to give some guidance to two-phase CFD potential users, based on previous experience of these tools. This experience comes first from a Writing Group (WG3) of the OECD-CSNI-GAMA on the extension of CFD to two-phase safety issues which has identified a list of Nuclear Reactor Safety issues for which the use of 2-phase CFD can bring a real benefit and which proposed a general multi-step methodology. Then experience was gained with the NEPTUNE-CFD code which is being developed by EDF and CEA and sponsored by IRSN and AREVA-NP for nuclear application. Also the NURESIM Integrated Project of the European Commission 6th Framework Program has been using 2-phase CFD for Direct Contact Condensation, Pressurized Thermal Shock, boiling flow, DNB and Dry-Out investigations. Although some progress has been made on all these applications, several difficulties are encountered and are here identified. Based on this experience, this paper intends to update the state of the art, to review the main modeling difficulties and to make recommendations for future developments, validation and application of two-phase CFD. The choice of a basic model, of space and time resolution, the deterministic or statistical treatment of interfaces, the characterization of the interfacial structure, and the automatic recognition of the local flow structure are discussed. Transport of interfacial area, modeling of polydispersion and some closure problems for turbulent, wall, and interfacial transfers are also reviewed.
Keywords: Nuclear Reactor Thermalhydraulics; Two-phase CFD; Direct Contact Condensation; Pressurized Thermal Shock; boiling flow; DNB; Dry-Out
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Beitrag zu Proceedings
The 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13), 27.09.-02.10.2009, Kanazawa, Japan
Proceedings of the 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13), Paper N13P1139
Permalink: https://www.hzdr.de/publications/Publ-13308
Spinodal decomposition and secondary phase formation in Fe-oversaturated GaN
Talut, G.; Reuther, H.; Grenzer, J.; Mücklich, A.; Shalimov, A.; Skorupa, W.; Stromberg, F.
Abstract
The flash-lamp annealing technique was applied to a GaN epilayer implanted with Fe in order to investigate the recovery of the crystal structure and the process of secondary phase formation. In the as-implanted state a spinodal decomposition occurs due to the oversaturation of Fe in GaN and a behavior similar to a spin-glass is observed. The precipitation occurs even after annealing for the shortest annealing time of 3 ms. Iron nitrides as well as bcc-Fe are formed upon annealing for 20 ms and are responsible for the ferromagnetic response. No indication of the formation of a diluted magnetic semiconductor is observed. The connection between the structure, magnetism and Fe-charge state was determined by x-ray diffraction, magnetometry and Mößbauer spectroscopy measurements.
Keywords: Fe; GaN; DMS; Mößbauer; flash-lamp annealing
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Physical Review B 81(2010), 155212
DOI: 10.1103/PhysRevB.81.155212
Cited 7 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13307
Preparation of shallow n+-layers in Ge using flash lamp annealing
Wündisch, C.; Posselt, M.; Schmidt, B.; Mücklich, A.; Skorupa, W.; Clarysse, T.; Simoen, E.; Hortenbach, H.
Abstract
Although the first transistor was made on germanium, most integrated circuits are fabricated using silicon substrates. The main reasons for the change from Ge to Si are the excellent physical properties of the SiO2/Si interface. Today SiO2 is more and more replaced by high-k dielectrics. This fact and the advantage of the higher carrier mobility in Ge compared to Si have led to a renewed interest in Ge as material in future CMOS applications. Previous investigations on the formation of ultra shallow junctions by ion beam processing have shown that p+-doping using B implantation yields junctions that meet the requirements for the 22 nm technology node, whereas the formation of n+-junctions by P or As is complicated by the high diffusivity and the low solubility of the dopants.
The present work deals with the application of millisecond flash lamp annealing (FLA) to samples containing an implanted surface layer of about 100 nm thickness. The layers were formed using P ions with an energy of 30 keV and a fluence of 3x1015 cm-2. The investigations are focused on solid phase recrystallization, dopant redistribution and dopant activation. The dependence of these effects on the heat transfer to the sample during FLA as well as on pre-amorphization and pre-annealing treatment is discussed. The results are compared to typical data achievable by conventional rapid thermal annealing (RTA) with durations of some seconds. Different characterization methods are employed. Channeling Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy (XTEM) are used to monitor the recrystallization of the amorphous layers formed during implantation. The depth distributions of P are measured by secondary ion mass spectrometry. In order to determine the sheet resistance variable probe spacing and micro four point probe measurements are utilized. Selected samples are studied by XTEM to search for precipitates and end-of-range defects. While in RTA the concentration dependent dopant diffusion hinders the formation of shallow n+ layers, FLA does not cause any diffusion but leads to dopant activation up to about 5x1019 cm-3.
Keywords: germanium; shallow junction; flash lamp annealing; diffusion; activation
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Vortrag (Konferenzbeitrag)
Nordic semiconductor meeting, 14.-17.06.2009, Reykjavik, Island
Permalink: https://www.hzdr.de/publications/Publ-13306
Millisecond flash lamp annealing of shallow implanted layers in Ge
Wündisch, C.; Posselt, M.; Schmidt, B.; Heera, V.; Schumann, T.; Mücklich, A.; Grötzschel, R.; Skorupa, W.; Clarysse, T.; Simoen, E.; Hortenbach, H.
Abstract
Shallow n+ layers in Ge are formed by phosphorus implantation and subsequent millisecond flash lamp annealing. Present investigations are focused on the dependence of P redistribution, diffusion and electrical activation on heat input into the sample and flash duration. Furthermore, the influence of pre-amorphization implantation and pre-annealing is studied. In contrast to conventional annealing procedures an activation up to 6.5×1019 cm-3 is achieved without any dopant redistribution and noticeable diffusion. Present results suggest that independently of pre-treatment the maximum activation should be obtained at a flash energy that corresponds to the onset of P diffusion. The deactivation of P is explained qualitatively by mass action analysis which takes into account the formation of phosphorus-vacancy clusters.
Keywords: Germanium; millisecond annealing; electrical activation; shallow junctions
- Applied Physics Letters 95(2009)25, 252107
Permalink: https://www.hzdr.de/publications/Publ-13305
Research at High Magnetic Fields
Wosnitza, J.
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Eingeladener Vortrag (Konferenzbeitrag)
ILL-TAS Scientists Outing, 01.-02.10.2009, Lamastre, Frankreich
Permalink: https://www.hzdr.de/publications/Publ-13304
Electronic properties of quasi-two-dimensional organic superconductors
Wosnitza, J.
Abstract
Since the discovery of the first organic superconductor, about 30 years ago, these materials revealed many fascinating properties and allowed to study fundamental low-dimensional physics. Besides superconductivity, the organic metals show a wealth of different ground states such as antiferromagnetic, spin-Peierls, spin-density-wave, and charge-density-wave phases. These ground states are accessible by tuning the structure, counter anion, magnetic field, temperature, and pressure. The study of these fertile phase diagrams has led to new theoretical concepts; however, a solid understanding of some of these states still remains a challenge. Even the normal metallic phase of these electronically low-dimensional metals reveals unusual properties sometimes not in line with conventional Fermi-liquid theory. Here, a review on selected normal-state and superconducting properties of the layered quasi-two-dimensional organic superconductors will be given. Thereby, the focus will be laid on the charge-transfer salts based on bisethylenedithiotetrathiafulvalene, or ET for short, the building block of most of the to-date known organic superconductors. Some basic features of the crystallographic structure, the highly anisotropic electronic band structure for some materials, as well as unusual electronic-transport properties will be highlighted. A brief overview on the superconducting properties including the recently reported evidence for the existence of a FuldeFerrellLarkinOvchinnikov state will be presented.
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Eingeladener Vortrag (Konferenzbeitrag)
I.F. Schegolev Memorial Conference "Low-Dimensional Metallic and Superconducting Systems", 10.-16.10.2009, Chernogolovska, Russia
Permalink: https://www.hzdr.de/publications/Publ-13303
Evolution of the Fermi Surface of the Electron-Doped High-Temperature Superconductor Nd2-xCexCuO4 Revealed by Shubnikovde Haas Oscillations
Helm, T.; Kartsovnik, M. V.; Bartkowiak, M.; Bittner, N.; Lambacher, M.; Erb, A.; Wosnitza, J.; Gross, R.
Abstract
We report on the direct probing of the Fermi surface in the bulk of the electron-doped superconductor Nd2-xCexCuO4 at different doping levels by means of magnetoresistance quantum oscillations. Our data reveal a sharp qualitative change in the Fermi surface topology, due to translational symmetry breaking in the electronic system which occurs at a critical doping level significantly exceeding the optimal doping. This result implies that the (π/a, π/a) ordering, known to exist at low doping levels, survives up to the overdoped superconducting regime.
- Physical Review Letters 103(2009), 157002
Permalink: https://www.hzdr.de/publications/Publ-13302
Complexation of curium(III) with pyoverdin-model compounds
Moll, H.; Bernhard, G.
Abstract
The aerobic groundwater bacterium Pseudomonas fluorescens (CCUG 32456) isolated from the aquifers at the Äspö Hard Rock Laboratory, Sweden secretes siderophores of the pyoverdin-type. Besides iron(III), these unique bioligands are also able to form strong complexes with actinides (e.g., U(VI), Np(V), and Cm(III)) [1-3]. For U(VI) and Np(V) we could show that mainly the catecholate and to less extend the hydroxamate functionalities of the pyoverdin molecule are involved in the actinide coordination [1, 2]. For Cm(III) it is still not clear which functional group of the pyoverdin molecule causes the great stability constants. In general, Cm(III) interactions with pyoverdin-model compounds and especially with chromophore-models are poorly understood. To address this lack, we thus present findings regarding the speciation of Cm(III) with 2,3dihydroxynaphthalene in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at trace Cm(III) concentrations (0.3 µM) over a wide pH range. TRLFS is a well established direct speciation technique for investigating the complexes formed by actinides in both geochemical and biochemical environments. Four Cm(III)- dihydroxynaphthalene species of the type MxLyHz could be identified from the spectroscopic measurements. The stability constants of these strong Cm(III)- bioligand complexes and their individual spectroscopic properties (excitation and emission spectra, lifetimes) are reported. TRLFS shows that Cm(III)- dihydroxynaphthalene species cause a strong red shift of the characteristic Cm(III) (aq) emission band at 593.8 to 614.4 nm. The findings of our Cm(III) speciation study in comparison with the literature indicate a stronger affinity of Cm(III) to the catechol functionality of the pyoverdin molecules as found for U(VI) and Np(V).
[1] H. Moll, M. Glorius, G. Bernhard, A. Johnsson, K. Pedersen, M. Schäfer, H. Budzikiewicz, Geomicrobiol. J. 25, 157-166 (2008).
[2] H. Moll, M. Glorius, A. Johnsson, M. Schäfer, H. Budzikiewicz, K. Pedersen, G. Bernhard, Radiochim. Acta, submitted (2009).
[3] H. Moll, A. Johnsson, M. Schäfer, K. Pedersen, H. Budzikiewicz, G. Bernhard, BioMetals 21, 219-228 (2008).
Keywords: Curium(III); TRLFS; Speciation; Pyoverdin; 2; 3-Dihydroxynaphthalene; excitation spectra; Chromophore-models
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Vortrag (Konferenzbeitrag)
RadChem 2010 - 16th Radiochemical Conference, 18.-23.04.2010, Marianske Lazne, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-13301
Photodisintegration of the p-nuclei 92Mo and 144Sm in the astrophysically relevant energy window
Nair, C.; Erhard, M.; Junghans, A. R.; Bemmerer, D.; Beyer, R.; Grosse, E.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.
Abstract
The heavy neutron deficient p-nuclei are produced in explosive stellar environments via photodisintegration reactions like (g ,n), (g ,p) and (g ,alpha) on r- or s- seed nuclei. The reaction rates of p-nuclei are mostly based on theoretical parameterizations using statistical model calculations. We study experimentally the photodisintegration rates of heavy nuclei at the bremsstrahlung facility of the superconducting electron accelerator ELBE of FZ Dresden-Rossendorf. Photoactivation measurements on the astrophysically relevant p-nuclei 92Mo and 144Sm have been performed with bremsstrahlung end-point energies from 10.0 to 16.5 MeV. The activation yields are compared with calculations using cross sections from recent Hauser-Feshbach models. The sensitivity of the statistical models to the input ingredients like photon strength function, optical potentials are tested against the experimental activation yield.
Keywords: photodisintegration; p-nuclei; photoactivation
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Beitrag zu Proceedings
International conference Nuclei in Cosmos- X, 27.07.-01.08.2008, Mackinac Island, Michigan, United States
Photodisintegration of the p-nuclei 92Mo and 144Sm in the astrophysically relevant energy window: Proceedings of Science
Permalink: https://www.hzdr.de/publications/Publ-13300
Application of Focused Ion and Electron Beams in Materials Research
Bischoff, L.
Abstract
At the beginning the lecture I will briefly give an overview about the organization of the Research Centre Dresden-Rossendorf with different Institutes and research topics. In the Institute of Ion Beam Physics and Materials Research the application of ion beams in advanced materials science is manifold: for example, they are used to generate new or improved functional surfaces, and they are ideally suited to produce micro- and nanostructures in semiconductors. For these purposes in the Institute a couple of modern ion beam instruments for the fabrication and analysis of nanostructures is available. Among them there are a mass separated focused ion beam (FIB) and a crossbeam system, consisting of a high resolution Ga-FIB and a scanning electron microscope (SEM), which will be discussed more in detail. During the last decades, focused ion beams became a very useful and versatile tool in microelectronics industry, as well as in the field of basic and applied research and became an indispensable tool in nanotechnology. For special purposes like ion milling, ion beam writing for doping or patterning on μm- and nm-scale without any lithographic steps Ga+ and increasingly other ion species are of great interest. An introduction in design and operation of mass separated FIB systems (e.g. CANION31Mplus), equipped with metal alloy liquid ion sources as well as the development and characterization of them will be given. The combination of a focused electron beam with a high resolution FIB column in a crossbeam arrangement (NVision40) enables the in-situ inspection and analysis of FIB fabricated nanostructures with a resolution down to one nm without surface damaging. An included gas injection system allows the MO-CVD of nanostructures of different materials using either the focused ion or the electron beam. The fabrication possibilities of nanostructures, like nanowires, nanobridges and nanocantilevers by ion beam synthesis using different kinds of focused ion beams will be demonstrated and possible applications will be mentioned. Some examples, like ion beam synthesis of CoSi2 nano-structures, the generation of fluorescent colour centres, sputtering investigations and applications, the formation of ripples under FIB irradiation or the fabrication of NEMS structures on SOI substrates will be shown to demonstrate the manifold utilization of the microbeam technology. Furthermore, the possibility of varying the flux in the FIB by changing the pixel dwell-time in a wide range gives the opportunity to investigate radiation damage and dynamic annealing effects in Si, Ge, SiC and other materials at elevated implantation temperatures using different projectile ion species. Finally, the state-of art of FIB applications for TEM lamella preparation, FIB lithography of thin films and ion beam microscopy will be presented and shortly discussed.
Keywords: Focused Ion Beam; Liquid Metal Ion Source; Electron Microscopy; Nanotechnology
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Eingeladener Vortrag (Konferenzbeitrag)
imdea nanociencia, 04.11.2009, Madrid, Spanien -
Eingeladener Vortrag (Konferenzbeitrag)
Kolloquiumsvortrag, 10.12.2009, Leipzig, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13299
Pipe dream
Azzopardi, B.; Hampel, U.; Hunt, A.
Abstract
Gas-liquid flows are central to oil and gas production and because of the very flexible nature of the interface between the fluids, the flows can be very complex exhibiting a wide variety of three dimensional structures. In the field the steel pipes in which these two-phase mixture flow make it difficult to observe them. Even in the laboratory where pipes can be made of transparent plastic, we can still normally only see what is occurring near the pipe wall as bubbles clustering near the wall, or wavy films of liquid flowing along the walls, obscure what is occurring at the middle of the pipe. One way in which these visual limitations can be overcome is to employ electrical tomography methods. In research at the University of Nottingham we are working with Forschungzentrum Rossendorf-Dresden from Germany and Tomoflow Limited to use electrical tomography to 'see' into the pipe.
Keywords: multi-phase flow; wire mesh sensors; electrical capacitance tomography
- TCE - The chemical engineer (2009)820, 39-41
Permalink: https://www.hzdr.de/publications/Publ-13298
Simulating Strongly Coupled Plasmas on High-Performance Computers
Bussmann, M.; Schramm, U.; Thirolf, P.; Habs, D.
Abstract
Simulating strongly coupled plasmas is a demanding computational task. When a plasma is strongly coupled, the mutual Coulomb energy between the plasma particles is much stronger than their kinetic energy. Such a system can undergo a phase transition into a state in which long-range ordering of the plasma constituents can be observed. In a realistic simulation of the plasma dynamics one has to compute the total mutual interaction of each particle with each other particle for particle numbers up to hundred thousand particles. To study the microscopic and macroscopic dynamics of the plasma on a long time scale one thus has to rely on the computational power which is only available at supercomputing centers such as the Leibniz Rechenzentrum.
Keywords: strong coupling; plasma; ocp; one-component plasma; simulation; molecular dynamics; checker-board algorithm; laser cooling; particle; highly-charged ion; hci; cooling; stopping
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Beitrag zu Proceedings
HLRB, KONWIHR and Linux-Cluster Review and Results Workshop, 08.-09.12.2009, Garching, Germany
Permalink: https://www.hzdr.de/publications/Publ-13297
GPU-based Particle-in-Cell Simulation
Burau, H.; Bussmann, M.; Schramm, U.; Cowan, T.; Widera, R.; Hönig, W.; Juckeland, G.
Abstract
Accelerating Plasma Simulations using novel computing hardware is a promising way towards a cost-efficient decrease of the runtime of realistic plasma simulations. We present a new particle-in-cell algorithm for simulating laser plasma acceleration of particles which has been developed to run on a NVIDIA GPU system. Using a sliding-window technique we are able to run large-scale 2D simulations of laser wakefield acceleration. We present the algorithm in detail and show that it is easy to extend to 3D geometries. We will conclude by discussing both obstacles and promises encountered when porting the algorithm to a standard CPU-based Linux cluster in which each node is equipped with one or more GPUs.
Keywords: gpu; gpgpu; cuda; particle-in-cell; pic; simulation; algorithm; cluster; message passing interface; pic; vampir; laser; plasma; acceleration
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Poster
ICNSP 09 - 21st International Conference on Numerical Simulation of Plasmas 2009, 06.-09.10.2009, Lisboa, Portugal
Permalink: https://www.hzdr.de/publications/Publ-13296
The economy of Yb:lasers
Siebold, M.
Abstract
Introduction of high-energy class diode-pumped solid-state lasers (HEC-DPSSLs) worldwide, efficiency limitations and energy extraction issues of high-energy laser based on Yb-doped materials, room-temperature vs. cryogenically cooled lasers, simulation and experimental results obtained with multi-pass pumping - a technique for efficiency enhancement.
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Sonstiger Vortrag
workshop on High-Energy Class Diode-Pumped Solid-State Lasers (HEC-DPSSL), 10.-12.06.2009, Dresden, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13295
Neue Materialien für Hochintensitätslaser sowie deren Anwendungen
Siebold, M.
Abstract
Erzeugung hoher Lichtintensitäten mittels Ultrakurzpulslaser, Laser-Teilchenbeschleunigung, diodengepumpte Festkörperlaser, neue Ytterbium-dotierte Lasermaterialien für Kurzpulslaserverstärker
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Eingeladener Vortrag (Konferenzbeitrag)
workshop: Festkörperlaser Materialien und Anwendungen, 10.-11.09.2009, Berlin, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13294
Diode-pumped chirped pulse amplification to the TW level using Yb:CaF2
Siebold, M.; Hornung, M.; Hein, J.; Uecker, R.; Debus, A.; Kaluza, M. C.
Abstract
We present a terawatt diode-pumped chirped pulse amplifier using single-crystalline Yb:CaF2 as the gain medium. A maximum pulse energy of 420 mJ and a repetition rate of 1 Hz was obtained. After recompression, a pulse energy of 197 mJ and a pulse duration of 192 fs were achieved, corresponding to a peak power of 1TW.
Keywords: Diode-pumped lasers; Ytterbium-doped solid state lasers; optical pulse generation and pulse compression
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Beitrag zu Proceedings
Ultra-Intense Laser Interaction Science (ULIS), 24.-29.05.2009, Frascati, Italia
Diode-pumped chirped pulse amplification to the TW level using Yb:CaF2, vol. 2109: American Institute of Physics, 119-122 -
Poster
Ultra-Intense Laser Interaction Science, 26.05.2009, Frascati, Italia
Permalink: https://www.hzdr.de/publications/Publ-13293
In-situ observation of secondary phase formation in Fe implanted GaN annealed in low pressure N-2 atmosphere
Talut, G.; Grenzer, J.; Reuther, H.; Shalimov, A.; Baehtz, C.; Novikov, D.; Walz, B.
Abstract
The formation of secondary phases in Fe implanted GaN upon annealing in low pressure N2-atmosphere was detected by means of in-situ x-ray diffraction and confirmed by magnetization measurements. A repeatable phase change from Fe2N at room temperature and Fe(3-x)N at 1023 K was observed in-situ. The phase transformation is explained by the change of lattice site and concentration of nitrogen within nitrides. The diffusion of Fe towards sample surface and oxidation with increasing annealing cycles limits the availability of secondary phase and hence the repeatability. At high temperature GaN dissolves and Ga as well as Fe oxidize due to presence of residual oxygen in the process gas. The ferromagnetism in the samples is related to nanometer sized interacting Fe(3-x)N crystallites.
Keywords: GaN; Fe-nitrides; DMS
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Applied Physics Letters 95(2009), 232506-1-232506-3
DOI: 10.1063/1.3271828
Cited 3 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13292
Xe ion beam induced ripple structures on differently oriented single-crystalline Si surfaces
Hanisch, A.; Biermanns, A.; Pietsch, U.; Grenzer, J.; Facsko, S.
Abstract
We report on Xe+ induced ripple formation at medium-energy on single crystalline silicon surfaces of different orientation using substrates with an intentional miscut from the [001] direction and a [111] oriented wafer. The ion beam incidence angle in respect to the surface normal was kept fixed at 65° and the ion beam projection was parallel or perpendicular to the [110] direction. By a combination of atomic force microscopy, X-ray diffraction and high resolution transmission electron microscopy we found that the features of surface and the subsurface rippled structures such as ripple wavelength and amplitude and the degree of order do not depend on the surface orientation as assumed in recent models of pattern formation for semiconductor surfaces.
Keywords: ripples nanostructures Xe self-organisation silicon miscut ion implantation
- Journal of Physics D: Applied Physics 43(2010)11, 112001
Permalink: https://www.hzdr.de/publications/Publ-13291
Bestimmung des Ausdampfverhaltens des Reaktorkerns bei Ausfall der Nachkühlung im Mitte-Loop-Betrieb bei geöffnetem Reaktordeckel auf Basis von Rechnungen mit dem Programm ATHLET
Kliem, S.
Abstract
Unter Verwendung des Rechenprogramms ATHLET wurde das Ausdampfverhalten des Reaktorkerns bei Ausfall der Nachkühlung untersucht. Dafür wurde der Primärkreislauf des Reaktors vom Austritt aus dem Pumpenbogen bis zum Eintritt in den Dampferzeuger modelliert. Bei einer fest vorgegebenen Nachzerfallsleistung von 22 MW wurde das axiale Profil variiert. Neben einem symmetrischen kosinusähnlichen Profil wurden jeweils ein Profil für den Beginn und das Ende eines Brennstoffzyklus eines typischen Druckwasserreaktorkerns verwendet.
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Artikel im Eigenverlag (nicht Beitrag zu HZDR-Jahresbericht)
Forschungszentrum Rossendorf 2009
FZD\FWS\2009\06
26 Seiten
ISSN: 1437-322X
Permalink: https://www.hzdr.de/publications/Publ-13290
Characterization and tuning of ultrahigh gradient permanent magnet quadrupoles
Becker, S.; Bussmann, M.; Raith, S.; Fuchs, M.; Weingartner, R.; Kunz, P.; Lauth, W.; Schramm, U.; Ghazaly, M. E.; Grüner, F.; Backe, H.; Habs, D.
Abstract
The application of quadrupole devices with high field gradients and small apertures requires precise control over higher order multipole field components. We present a new scheme for performance control and tuning; which allows the illumination of most of the quadrupole device aperture because of the reduction of higher order field components. Consequently, the size of the aperture can be minimized to match the beam size achieving field gradients of up to 500 T m -1 at good imaging quality. The characterization method based on a Hall probe measurement and a Fourier analysis was confirmed using the high quality electron beam at the Mainz Microtron MAMI.
Keywords: compact; permanent; magnetic; quadrupole; lens; beam focusing; multipole; tuning; halbach; electron beam; x-fel
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Physical Review Accelerators and Beams 12(2009)10, 102801
DOI: 10.1103/PhysRevSTAB.12.102801
Permalink: https://www.hzdr.de/publications/Publ-13289
Measurement of Radiation Hardness of PET Components
Fiedler, F.; Braess, H.; Enghardt, W.
Abstract
In-beam PET has given valuable feedback on treatment quality over the 11 years of operation time between 1997 and 2008 of the heavy ion treatment facility at the Gesellschaft für Schwerionenforschung (GSI) Darmstadt. Based on this technical expertise a next generation of in-beam PET scanners will be developed. An experiment addressing the question whether the detectors and electronic components used in state-of-the-art PET-systems can be also utilized to configure a future in-beam PET scanner was performed at the medical beam line of GSI. The equipment for a new in-beam PET scanner should be tested whether it will resist the fluence of secondaries arising from the patient treatment of about 5 years. A ^12C beam of an energy of E=430.10AMeV was stopped in a PMMA phantom. The primary particle fluence of this irradiation was equivalent to about 5300 patient fractions (3 GyE per fraction). The detectors were placed at several angles to simulate a higher secondary particle fluence, i.e. a longer time of usage. They have been exposed to a secondary particle fluence equivalent up to 13 years of usage in an in-beam PET scanner. The equipment was provided by CPS and tested before and after the experiment. No damage was found applying the standard test procedure. analyzing the detectors after the experiment.
Keywords: radiation hardness; in-beam PET; ion therapy
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Vortrag (Konferenzbeitrag)
2009 IEEE Nuclear Science Symposium and Medical Imaging Conference, 25.-31.10.2009, Orlando, USA -
Beitrag zu Proceedings
2009 IEEE Nuclear Science Symposium and Medical Imaging Conference, 23.10.-01.11.2009, Orlando, USA
Conference Record
Permalink: https://www.hzdr.de/publications/Publ-13288
A FAIR equation of state
Schulze, R.; Kämpfer, B.
Keywords: QCD; equation of state; FAIR; quasiparticles
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Sonstiger Vortrag
Institutsinternes WIP-Seminar, 16.10.2009, Dresden-Rossendorf, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13287
Discrimination of thioarsenites and thioarsenates by x-ray absorption spectroscopy
Suess, E.; Scheinost, A. C.; Bostick, B. C.; Merkel, B. J.; Wallschlaeger, D.; Planer-Friedrich, B.
Abstract
Soluble arsenic−sulfur compounds play important roles in the biogeochemistry of arsenic in sulfidic waters but conflicting analytical evidence identifies them as either thioarsenates (= AsV−sulfur species) or thioarsenites (= AsIII−sulfur species). Here, we present the first characterization of thioarsenates (mono-, di-, and tetrathioarsenate) by X-ray absorption spectroscopy and demonstrate that their spectra are distinctly different from those of AsIII−sulfur species, as well as from arsenite and arsenate. The absorption near edge energy decreases in the order arsenate > thioarsenates > arsenite > AsIII−sulfur species, and individual thioarsenates differ by 1 eV per sulfur atom. Fitted AsV−S and AsV−O bond distances in thioarsenates (2.13−2.18 Å and 1.70 Å, respectively) are significantly shorter than the corresponding AsIII−S and AsIII−O bond distances in AsIII−S species (2.24−2.34 Å and 1.78 Å, respectively). Finally, we demonstrate that thioarsenates can be identified by principal component analysis in mixtures containing AsIII−sulfur species. This capability is used to study the spontaneous reduction of tetrathioarsenate to AsIII−sulfur species (possibly trithioarsenite) upon acidification from pH 9.5 to 2.8.
Keywords: Arsenic; speciation; thioarsenite; thioarsenate; EXAFS; XANES
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Analytical Chemistry 81(2009)20, 8318-8326
DOI: 10.1021/ac901094b
Cited 89 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13286
System Solution for Particle Therapy PET
Shakirin, G.; Braess, H.; Fiedler, F.; Kunath, D.; Laube, K.; Parodi, K.; Priegnitz, M.; Enghardt, W.
Abstract
At present, positron emission tomography (PET) is the only available technique for an in-vivo, non-invasive monitoring of the dose delivery precision in highly conformal ion beam therapy. The successful exploitation of in-beam PET at the Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt, Germany during the last decade and a rising number of built or planned proton and heavier ion therapy facilities worldwide makes the development of a particle therapy PET (PT-PET) system of the next generation reasonable. The in-beam PET installation at GSI is a double-head positron scanner with a very limited solid angle which results in severe artifacts in the reconstructed images and in a low counting statistics. Thus, it is highly desirable to have larger solid angle coverage for PT-PET scanners of the next generation. However, increasing the effective area of a scanner might be limited by several requirements for the equipment of a radiotherapy treatment unit. Possible solutions for a prospective PT-PET system as well as a methodology for the evaluation of concurrent designs of the scanner taking into account the requirements of a therapy facility are discussed in this paper.
Keywords: in-beam PET; particle therapy; PT-PET
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Poster
2009 IEEE Nuclear Science Symposium and Medical Imaging Conference, 24.10.-01.11.2009, Orlando, USA -
Beitrag zu Proceedings
IEEE NSS MIC, 24.-31.10.2009, Orlando, USA
System Solution for Particle Therapy PET
Permalink: https://www.hzdr.de/publications/Publ-13285
Quark stars from lattice QCD
Schulze, R.; Kämpfer, B.
Abstract
At small net baryon densities ab initio lattice QCD provides valuable information on the finite-temperature equation of state of strongly interacting matter. Our phenomenological quasiparticle model provides a means to map such lattice results to regions relevant for future heavy-ion experiments at large baryon density; even the cool equation of state can be inferred to address the issue of quark stars. We report on (i) the side conditions (charge neutrality, beta equilibrium) in mapping latest lattice QCD results to large baryon density and (ii) scaling properties of emerging strange quark stars.
Keywords: QCD; quasiparticle model
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Vortrag (Konferenzbeitrag)
Dense Matter in Heavy-Ion collisions and Supernovae, 11.-13.10.2009, Prerow, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13284
Synthesis of new bifunctional chelators for conjugation to vector molecules for tumor targeting.
Heldt, J.-M.; Ruffani, A.; Zenker, M.; Walther, M.; Stephan, H.; Pietzsch, H.-J.; Steinbach, J.
Abstract
Problem:
The goal of this study is to prepare novel chelators suitable for conjugation to vector molecules which can be labeled by yttrium or copper in order to achieve high specific activities and to improve pharmacokinetics. In this context, new water soluble bifunctional DOTA- and bis(2-pyridylmethyl)triazacyclocyclononane (DMPTACN)-based chelators have been synthesized and conjugated to the monoclonal antibody Cetuximab which binds to HER2 of the epithelial growth factor receptor (EGFR) family which is over-expressed by various tumors.
Material and Method:
Both chelators have been conjugated to Cetuximab via thiourea-bridging. Radiolabeling of DOTA derivatives has been performed in aqueous ammonium acetate solution at r.t. using 86YCl3 or 90YCl3. Radiolabeling of DMPTACN conjugates with 64Cu was achieved in MES buffer solution at 50°C using 64CuCl2. The affinity of the bioconjugates towards EGFR was determined by ELISA.
Results:
The ELISA test showed that the affinity of the bioconjugates has decreased compared to native Cetuximab. A chelator/antibody molar ratio of 4 was achieved as determined by MALDI-TOF-MS for the DOTA-Cetuximab conjugate. Radiolabeling of DOTA-conjugates with 86Y and 90Y at 37°C requires optimization to improve radiochemical yield. DMPTACN-Cetuximab conjugates can be rapidly labeled with 64Cu under mild conditions in almost quantitative yield.
Conclusions:
DMPTACN- and DOTA-ligands are attractive bifunctional chelating agents which can be conjugated to vector molecules for PET-imaging and radiotherapy. In the near future, the work with the ligands investigated will be extended using the pre-labeling approach.
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Vortrag (Konferenzbeitrag)
Targeting and Imaging of the Tumor Microenvironment, 23.-26.09.2009, Berder island, France
Permalink: https://www.hzdr.de/publications/Publ-13283
Structure-activity relationship of radiocopper-labeled DMPTACN-Bombesin conjugates
Ruffani, A.; Stephan, H.; Bergmann, R.; Steinbach, J.; Gasser, G.; Spiccia, L.
Abstract
Aim:
Radiometal‐labeled peptide derivatives of bombesin are very interesting targeting vectors for certain types of cancer. Bombesin derivatives have shown very high selectivity and affinity to
G‐protein‐coupled gastrin‐releasing‐peptide‐receptor (GRPR), which is over‐expressed in a variety of tumors including breast‐, prostate‐ and pancreatic‐tumors. Consequently, the
application of radiolabeled bombesin‐analogs for both the diagnosis and therapy of such tumors is being intensively investigated. However, the development of chemically and radiolytically
stable compounds which can be easily radiolabeled presents significant challenges. We recently showed that bis(2‐pyridylmethyl)triazacyclocyclononane (DMPTACN) was a promising candidate
for radiocopper‐labeling. In this study we examine structure‐activity relationships for new [64Cu]DMPTACN bombesin derivatives including their biodistribution and pharmacokinetics in
prostate cancer (PC3) xenografted tumor mice.
Methods:
Stabilized bombesin derivatives β‐Ala‐β‐Ala‐[Cha13,Nle14]BBN(7‐14) and β‐homo‐Glu‐β‐Ala‐β‐Ala‐[Cha13, Nle14]BBN(7‐14) were conjugated to the N‐terminus with DMPTACN ligands containing either a carboxylate or phenylisothiocyanate pendant arm via amide coupling and thiourea‐bridging, respectively. Radiolabeling of DMPTACN‐BBN derivatives with 64Cu was performed in aqueous ammonium acetate solution (pH=6) at 50°C using [64Cu]CuCl2. The affinity of DMPTACN‐BBN derivatives for the GRPR was determined using a competitive displacement/binding assay in human prostate (PC3) cancer cells. Internalization data for the [64Cu]Cu‐DMPTACN bombesin derivatives were obtained in the same cell line. Partition coefficients of the radiocopper‐labeled complexes of the DMPTACN‐BBN derivatives were determined in a 1‐octanol/buffer system. Biodistribution studies were performed on Wistar rats and NMRI nu/nu mice bearing the human prostate tumor PC‐3. Tumor accumulation was evaluated with small animal PET.
Results:
Radiolabeling of DMPTACNBBN‐bioconjugates was achieved in 30 min, yielding >99% radiochemical purity and specific activity up to 30 GBq/μmol after HPLC. DMPTACN‐NCS derivatives could be rapidly labeled with 64Cu under mild conditions in almost quantitative yield. The DMPTACN‐BBN conjugates showed high affinity to the GRPR and high uptake in PC‐3 cells. PET studies on tumor‐bearing PC‐3 mice revealed an accumulation in the GRPR‐positive tissue. Clear visualization of the tumor tissue and noticeable delineation from healthy tissue was achieved.
Conclusion:
DMPTACN ligands are attractive chelates for the development of radiocopper pharmaceuticals featuring very high chemical and radiolytical stability. They can be effectively coupled to target‐oriented peptides, such as bombesin. However, many issues need to be resolved, including the metabolic stabilization of the peptides and the direct fixation of radiometalated conjugates in the tumor tissue. DMPTACN‐isothiocyanate was found to be rapidly and efficiently labeled with 64Cu. These features make it a promising candidate as a pre‐labeling building block for antibody and synthetic polymers.
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Vortrag (Konferenzbeitrag)
Annual Congress of the European Association of Nuclear Medicine (EANM´09), 10.-14.10.2009, Barcelona, Spain -
Abstract in referierter Zeitschrift
European Journal of Nuclear Medicine and Molecular Imaging 36(2009)Suppl. 2, S207
DOI: 10.1007/s00259-009-1227-5
Permalink: https://www.hzdr.de/publications/Publ-13282
Synthesis and Metabolic Stability of 11C-Labelled SU11248 Derivative as Inhibitor of Tyrosine Kinases
Knieß, T.; Bergmann, R.; Steinbach, J.
Abstract
Aim:
SU11248 is a novel inhibitor of receptor tyrosine kinases (RTKs) targeting vascular endothelial growth factor (VEGF) and plated‐derived growth factor (PDGF) [1]. Due to the fact that RTKs are overexpressed in some tumour entities, they might be a suitable target for cancer imaging by positron emission tomography (PET). A tyrosine kinase inhibitor labelled with a positron emitting isotope could represent a useful tool for monitoring levels of RTKs in tumour tissue by giving valuable information for anti‐angiogenic therapy. For this purpose we synthesized a methoxy substituted derivative of SU11248 and performed the radiosynthesis with the PET radionuclide carbon‐11 to the corresponding 11C‐labelled radiotracer. First investigations on the in vivo metabolic stability of the new 11C‐labelled SU11248 derivative are reported.
Materials and methods:
The radiolabelling was performed via 11C‐methylation reaction of the corresponding desmethyl precursor with [11C]MeI in a TRACERLab FXC gas phase synthesizer (GE). After purification by semi‐preparative HPLC and solid phase extraction the radiotracer was dispensed with E153 electrolyte solution and injected intravenously into male Wistar rats. For metabolite analysis blood samples were taken from the arteria femoralis at 1.5; 3; 5; 10, 20, 30 and 60 minutes past injection. After centrifuging blood samples 5 min 13.000 rpm at 4°C plasma was analyzed by radio HPLC.
Results:
The synthesis of the non‐radioactive methoxy‐substituted SU11248 as well as the desmethyl precursor was accomplished by reacting 5‐methoxy‐ and 5‐hydroxyl‐oxindole with 5‐formyl‐2,4‐dimethyl‐1H‐pyrrole‐3‐carboxylic‐acid‐(2‐diethylaminoethyl)‐amide. Radiolabelling was achieved by reaction of the 5‐hydroxy‐substituted SU11248 derivative with [11C]CH3I in DMF/aqueous NaOH at 80°C. After semi‐preparative HPLC purification the 11C‐labelled radiotracer was obtained in 14‐17% decay corrected radiochemical yield at a specific activity of 162‐198 GBq/μmol at the end of synthesis in 94‐99% radiochemical purity. Metabolism analysis in rat plasma showed 96% of intact compound 3 min and 73% 60 min p.i., together with three more polar metabolites.
Conclusion:
The new 11C‐labelled derivative of SU11248 can be synthesized in good radiochemical yield, sufficient purity and high specific activity. The found metabolic stability in rat plasma showing 73% of intact radiotracer 60 min p.i. suggests that the 11C‐methoxy labelling group is preserved under in vivo conditions. These findings are encouraging for further investigation with this radiotracer on RTK expressing cells and tumour tissue to answer the question if this radiotracer would be a useful tool for monitoring angiogenic processes by PET. [1] Sun L., Liang C. et al., J. Med. Chem., 46, (2003), 1116
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Poster
Annual Congress of the European Association of Nuclear Medicine (EANM), 10.-14.10.2009, Barcelona, Spain -
Abstract in referierter Zeitschrift
European Journal of Nuclear Medicine and Molecular Imaging 36(2009)Suppl. 2, S310-S311
DOI: 10.1007/s00259-009-1227-5
Permalink: https://www.hzdr.de/publications/Publ-13281
Structural Aspects of Uranyl Complexes with Lipopolysaccharide
Barkleit, A.; Li, B.; Foerstendorf, H.; Rossberg, A.; Moll, H.; Bernhard, G.
Abstract
It is well-known that microorganisms play an important role in bioremediation. Because of the high retention capability of heavy metal ions, they significantly influence mobilization and immobilization of cations in soils. The prediction of the radionuclide transport in the environment and the improvement of technical bioremediation strategies require a detailed understanding of the binding mechanisms on a molecular level.
Lipopolysaccharide (LPS), the main part of the outer membrane of Gram-negative bacteria, sticks out of the cell wall and is in direct contact with the (aqueous) environment. With its high content of negatively charged functional groups (mainly carboxyl and phosphoryl groups) it plays a key role in protection of contaminants.
We investigated the uranyl LPS interactions to gain detailed information about the coordination sphere in the molecular environment of the uranyl ion. We focused on the identification of the coordinating functional groups over a wide pH range (from 2.5 to 7) and under different stoichiometric conditions. In particular, the discrimination between carboxyl and phosphoryl groups and their binding behaviours was elucidated by extended X-ray absorption fine structure (EXAFS) spectroscopy at the U LIII-edge and attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy. With respect to environmental conditions, samples with an excess of LPS were investigated by EXAFS. Furthermore, samples with equimolar ratios of uranyl and functional groups of LPS according to a slight deficit of phosphoryl groups were determined with FT-IR.
EXAFS spectra show great similarities to the uranyl mineral phase meta-autunite. A four-fold complexation of the uranium was derived from very short U Oeq distances of 2.28 Å and U P distances of 3.58 Å indicating unidentate coordinated phosphoryl groups. Furthermore, U U interactions can be observed at 5.2 Å and 6.9 Å.
FT-IR spectra show spectral evidence for both, carboxyl and phosphoryl coordination. A downshift of the antisymmetric stretching mode of the carboxylate group from 1576 (uncomplexed LPS) to 1530 cm−1 and an upshift of the symmetric stretching mode from 1404 (uncomplexed LPS) to 1455 cm−1 upon complexation provides evidence for a bidentate complexation to carboxylate groups. The antisymmetric and symmetric stretching modes of the complexing phosphoryl groups are observed at 1105 and 1060 cm−1.
In summary, we determined at high LPS excess preferential phosphoryl coordination, whereas with an increasing relative amount of uranyl ions, corresponding to a decreasing number of functional groups of LPS, additional carboxylate coordination becomes important. This complexation behaviour remains within a broad pH range from slight acidic to neutral values. Under the investigated experimental conditions, the coordination of uranyl ions to the LPS molecule is obviously controlled by the U/LPS concentration ratio irrespective from prevailing pH.
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Vortrag (Konferenzbeitrag)
RadChem 2010 - 16th Radiochemical Conference, 18.-23.04.2010, Marianske Lazne, Czech Republic
Permalink: https://www.hzdr.de/publications/Publ-13280
Investigations on seepage waters of the test site Gessenwiese by TRLFS
Baumann, N.; Arnold, T.
Abstract
The test field Gessenwiese was installed on a leaching heap at the former uranium mining area Ronneburg (western Thuringia) for investigations in acid mining drainage and in heavy metals retention, especially uranium (Grawunder A. et al. 2009). The uranium speciation in seepage water of the Gessenwiese was determined by TRLFS. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) posses some superior features, above all a very high sensitivity for fluorescent heavy metal ions. The predominance of TRLFS compared to other spectroscopic techniques, e.g. XRD and IR was showed in Baumann N. et al. (2008) in analyzing the speciation of U(VI) in a thin layer of an alteration product formed on depleted uranium. TRLFS analyses in seepage water of the Gessenwiese were carried out to compare it in a later stage with the uranium speciation in plants, which grow on that grassland and may take up uranium contaminated water.
Grawunder A. et al. Chem Erde-Geochem. 69 5-19 (2009)
Baumann N. et al. Environ. Sci. Technol. 42 8266-8269 (2008)
Keywords: Uranium; Speciation; TRLFS
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Beitrag zu Proceedings
16th Radiochemical Conference, 18.-23.04.10, Marienbad, Tschechische Republik
Chemické listy S - Booklet of Abstracts, Praha: CSAV, s190
Permalink: https://www.hzdr.de/publications/Publ-13279
Investigations on Stability and Structure of Thorium Colloids in near-neutral Solutions
Dreissig, I.; Weiss, S.; Zanker, H.; Hennig, C.; Brendler, E.; Bernhard, G.
Abstract
This work presents results about the formation of thorium(IV) colloids and precipitates in the presence of silicic acid. Three methods were used for the preparation of the thorium compounds:
- Experiment A: Silicic acid concentrations and ionic strengths were adjusted in the presence of preformed stable ThO2 colloids at neutral pH (0.4 mM Th; 0 3 mM Si; I = 0.05 M NaClO4)
- Experiment B: Precipitation of ThO2 colloids in the presence of silicic acid by neutralization from the acidic side of the pH scale (1 mM Th; 0-4.2 mM Si; I = 0.1 M NaClO4)
- Experiment C: Precipitation of Th(IV) colloids in the presence of silicic acid by neutralisation of a Th(IV) carbonate solution from the alkaline side of the pH scale (1 mM Th; 0-3 mM Si; I = 0.1 M NaClO4)
The zeta potentials of the thorium compounds in experiments A, B and C were determined by laser Doppler velocimetry at pH values of 2 10. These measurements allowed the estimation of the isoelectric points (IEPs) of the colloids and conclusions about the colloidal stability of the suspensions formed.
By the addition of silicic acid to preformed ThO2 colloids (experiment A), a significant shift of the IEPs from pH ~ 8.5 to lower values (pH ~ 6.5) was observed. Similar results were found in experiment B. Here, the IEP shifted from pH ~ 7.3 to pH ~ 6.0 in the presence of silicic acid. For both experiments the shift of the IEP was a function of the silicic acid concentration. Obviously, the significant amounts of silicate in/on the Th(IV) particles shift the IEP toward the IEP of pure silicic acid (pH < 3[1]).
On the other hand, the results of the zeta potential measurements on the Th(IV) colloids from experiment C demonstrated that the IEP did not change in the presence of varying amounts of silicic acid but remained constantly at pH ~ 5.2. It was also significantly lower than the IEPs of the colloids from experiments A and B formed under acidic conditions. The IEP behaviour of the experiment C colloids is not yet fully understood.
The results of 29Si solid state NMR and EXAFS spectroscopy of the thorium samples from experiment C showed that silicate was built in into the solid structure of ThO2. A possible mechanism is the partial replacement of the Th-O-Th bonds by bridging silicic acid and the formation of Th-O-Si-O-Th links. It is discussed whether the integration of silicic acid in the solid structure results in the formation of a still unknown thorium compound or a thorite (ThSiO4) like material was formed.
[1] R. K. Iler, K. Ralph, The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica, John Wiley & Sons, 1979.
Keywords: Colloid; nanoparticle; zetapotential; isoelectric point; thorium; Th(IV); silicic acid; silicate; EXAFS; 29-Si-NMR
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Beitrag zu Proceedings
RadChem 2010 - 16th Radiochemical Conference, 18.-23.04.2010, Marianske Lazne, Czech Republic
Radchem 2010 - BOOKLET OF ABSTRACTS CONFERENCE PROGRAMME
Permalink: https://www.hzdr.de/publications/Publ-13278
Effect of the Nature of Anions of Aluminum Salts Used to Synthesize a Precursor of the Al2O3-ZrO2 Ceramics on the Stabilization of the Tetragonal Modification of Zirconium Dioxide
Zharnylskaya, A. L.; Volkhin, V. V.; Reuther, H.
Abstract
Samples of a precursor for an aluminum oxide ceramics reinforced with zirconium oxide were synthesized by hydrolysis of various aluminum salts in the presence of a ZrO2 sol under conditions of urea decomposition at 90 degrees C and pH < 4 maintained, with hydrolysis products deposited onto the surface of ZrO2 sol particles. It was found that the nature of a salt anion affects the interaction of hydrolysis products of the aluminum cation with the surface of ZrO2 sol particles. The structure of products formed in thermal treatment of samples of a precursor for Al2O3-ZrO2 (T = 1250 degrees C) was characterized by X-ray phase analysis and scanning electron microscopy. The phase transition temperatures of the oxides Al2O3 and ZrO2 contained in the precursor were estimated using the results of thermal analysis of the samples in the temperature range 20-1300 degrees C.
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Russian Journal of Applied Chemistry 82(2009), 1364-1369
DOI: 10.1134/S1070427209080084
ISSN: 1070-4272
Cited 1 times in Scopus - Zurnal prikladnoj chimii 82(2009), 1268-1272
Permalink: https://www.hzdr.de/publications/Publ-13277
Improvement of Satellite Imaging Câmera Components Made of SS304 by Nitrogen PIII Treatments
Siqueira, R. H. M.; Ueda, M.; Lepienski, C. M.; Reuther, H.
Abstract
Improvement of Satellite Imaging Câmera Components Made of SS304 by Nitrogen PIII Treatments
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Poster
10th International Workshop on Plasma Based Ion Implantation and Deposition, 07.-11.09.2009, São José dos Campos, Brasil
Permalink: https://www.hzdr.de/publications/Publ-13276
Enhancement of Surface Properties of SAE 1070 by Chromium Plasma Immersion Ion Implantation and Deposition
Mello, C. B.; Ueda, M.; Oliveira, R. M.; Reuther, H.; Lepienski, C. M.
Abstract
Enhancement of Surface Properties of SAE 1070 by Chromium Plasma Immersion Ion Implantation and Deposition
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Vortrag (Konferenzbeitrag)
10th International Workshop on Plasma Based Ion Implantation and Deposition, 07.-11.09.2009, São José dos Campos, Brasil
Permalink: https://www.hzdr.de/publications/Publ-13275
Modificação da Superfície da Liga Ni-Ti Pela Implantação Iônica por Imersão em Plasma
Camargo, E. N.; Silva, M. M.; Baldissera, S.; Ueda, M.; Otubo, J.; Reuther, H.
Abstract
Modificação da Superfície da Liga Ni-Ti Pela Implantação Iônica por Imersão em Plasma
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Vortrag (Konferenzbeitrag)
64º Congresso da ABM Associação Brasileira de Metalurgia, Materiais e Mineração, 13.-17.07.2009, Expominas, Belo Horizonte, Brasil
Permalink: https://www.hzdr.de/publications/Publ-13274
Characteristics of Austenitic Stainless Steel Nitrided in a Hybrid Glow Discharge Plasma
Oliveira, R. M.; Ueda, M.; Silva, L. L. G.; Reuther, H.; Lepienski, C. M.
Abstract
Characteristics of Austenitic Stainless Steel Nitrided in a Hybrid Glow Discharge Plasma
- Brazilian Journal of Physics 39(2009), 554-558
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Vortrag (Konferenzbeitrag)
17th International Conference on Wear of Materials, 19.-23.04.2009, Las Vegas, USA
Permalink: https://www.hzdr.de/publications/Publ-13273
Nanoindentation response and microstructure of irradiated Fe-Cr alloys
Bergner, F.; Heintze, C.; Hernandez-Mayoral, M.
Abstract
Self-ion irradiation in combination with nanoindentation offers the possibility to characterize irradiation damage in a broad range of irradiation temperature and fluence. Nanoindentation results are reported for Fe-Cr alloys containing 2.5 to 12.5 at% Cr irradiated at ambient and elevated temperatures. The investigation also comprises dual-beam ion irradiations. The effects of indentation load, Cr content, fluence and irradiation temperature are discussed. We have found cases of both broad consistence with and deviations from reported trends. Hardening features are characterized by means of TEM. The results are compared with TEM, SANS and hardness data reported for neutron-irradiated conditions of the same alloys.
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Vortrag (Konferenzbeitrag)
IAEA Technical Meeting on Physics of Materials under Neutron and Charged Particle Irradiation, 16.-19.11.2009, Wien, Österreich
Permalink: https://www.hzdr.de/publications/Publ-13272
FP7 project LONGLIFE: Treatment of long term irradiation embrittlement effects in RPV safety assessment
Altstadt, E.; Bergner, F.; Hein, H.; Gillemot, F.; Serrano, M.; Brumovsky, M.; Lidbury, D.; Marcelles, I.
Abstract
In view of the increasing age of the European NPPs and envisaged life time extensions up to an EOL of 80 years, there is a need for an improved understanding of RPV irradiation embrittlement effects specific to long term operation (LTO). The project aims at: 1) improved knowledge on LTO phenomena relevant for European reactors; 2) assessment of prediction tools, codes, standards and surveillance guidelines. The scope of work comprises the analysis of LTO boundary conditions, microstructural investigations (e.g. LBP) and supplementary mechanical tests (e.g. RPV steels from decommissioned plants), training activities and elaboration of recommendations for RPV materials assessment and embrittlement surveillance under LTO conditions. The duration of the collaborative project will be 36 months with 15 partners participating.
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Eingeladener Vortrag (Konferenzbeitrag)
15th Workshop of the International Group on Radiation Damage Mechanisms in Pressure Vessel Steels (IGRDM-15), 11.-16.10.2009, Budapest, Ungarn
Permalink: https://www.hzdr.de/publications/Publ-13271
Fluence dependence of SANS and yield stress increase observed for low-Cu RPV steels
Bergner, F.; Ulbricht, A.; Viehrig, H.-W.
Abstract
The investigation is focussed on three low-Cu RPV steels, JPB, JPC and JFL, irradiated at 255°C up to several levels of neutron fluence. The SANS data obtained will be discussed as a function of fluence and correlated with measured values of the yield stress increase. There is strong evidence for a late-blooming effect from both SANS and hardening. The results will be compared with those from similar investigations for RPV steels and model alloys irradiated at higher temperatures and higher flux.
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Vortrag (Konferenzbeitrag)
15th Workshop of the International Group on Radiation Damage Mechanisms of Pressure Vessel Steels (IGRDM-15), 11.-16.10.2009, Budapest, Ungarn
Permalink: https://www.hzdr.de/publications/Publ-13270
The microstructure of neutron-irradiated Fe-Cr alloys: A small-angle neutron scattering study
Bergner, F.; Heintze, C.; Ulbricht, A.
Abstract
Ferritic-martensitic chromium steels are candidate materials for future applications in both Gen-IV fission and fusion technology. Experimental investigation of neutron-irradiated Fe-Cr model alloys is important in order to gain a better understanding of the interplay of chromium content and irradiation behaviour. Small-angle neutron scattering (SANS) is particularly well suited to unfold the size distribution of non-planar irradiation-induced nanoscale features such as defect-solute clusters, nanovoids and -particles. This size distribution represents a statistically reliable average over a macroscopic volume. Assumptions on the dominant type of features can be checked against the ratio of magnetic and nuclear scattering.
The materials investigated in this work are commercial-purity Fe-Cr alloys of nominal compositions Fe-2.5Cr, Fe-5Cr, Fe-9Cr and Fe-12.5Cr (at%). Neutron irradiation was performed in the reactor BR2 at Mol (Belgium) at a temperature of 300°C and neutron flux of 9 x 1013 cm-2 s-1 (E > 1 MeV) [Matijasevic, JNM 377 (2008) 147]. The neutron exposures expressed in units of displacements per atom correspond to 0.6 and 1.5 dpa. A wavelength of 0.58 nm and three detector-sample distances of 1, 4 and 16 m were used in the SANS experiments carried out at the SANS-2 facility of GKSS Geesthacht (Germany). The samples were placed in a saturation magnetic field in order to separate magnetic and nuclear contributions. The scattering curves obtained for the unirradiated conditions of the four Fe-Cr alloys were taken as reference.
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Vortrag (Konferenzbeitrag)
Joint EC-IAEA Topical Meeting on Development of New Structural Materials for Advanced Fission and Fusion Reactor Systems, 05.-09.10.2009, Barcelona, Spanien
Permalink: https://www.hzdr.de/publications/Publ-13269
Characterization of Fe-Cr alloys using SANS, nanoindentation and ultrasound
Heintze, C.; Bergner, F.; Ulbricht, A.
Abstract
Ferritic/martensitic Cr-steels are candidate structural materials for future nuclear applications. Fe-Cr alloys serve as model alloys for the investigation of the effect of Cr on microstructure, properties and irradiation behaviour. Industrial purity Fe-Cr alloys of Cr levels of 2.5, 5, 9 and 12 at% were produced at SCKCEN Mol within the MIRE project and characterized with respect to composition, microstructure, dislocation arrangement and tensile properties [M. Matijasevic et al., JNM 377 (2008) 147]. The present contribution is devoted to the complementary characterization of the same set of materials by means of small angle neutron scattering (SANS), depth-sensing nanoindentation and sound velocity measurements.
SANS experiments were performed in the wide range of scattering vectors from 0.03 to 3 nm 1 using three different sample-detector distances. Incoherent and coherent scattering were identified and discussed as a function of Cr content. Depth-sensing nanoindentation was performed at maximum loads ranging from 1 to 500 mN and supplemented with Vickers hardness. Interestingly, some of the curves representing the load dependence of nanohardness for different Cr contents cross one another indicating an effect of Cr on the indentation-size effect. The velocity of both longitudinal and shear waves was measured using the ultrasound pulse-echo technique. The polycrystalline averages of the elastic constants were estimated as a function of Cr. First results on the effect of both ion and neutron irradiation will also be presented.
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Vortrag (Konferenzbeitrag)
EUROMAT 2009, 07.-10.09.2009, Glasgow, United Kingdom
Permalink: https://www.hzdr.de/publications/Publ-13268
Cluster dynamics simulation of point defect clusters in neutron irradiated pure iron
Gokhman, A.; Bergner, F.
Abstract
The effect of the size dependence of production rate of point defect clusters is taken into account in the cluster dynamics modeling of the simultaneous formation of vacancy clusters and self-interstitial atom clusters in neutron irradiated pure iron. The calibration of material parameters has been carried out. The correspondence between small angle neutron scattering, transmission electron microscopy and positron annihilation spectroscopy and cluster dynamics data is studied.
Keywords: Neutron irradiation; Pure iron; Cluster dynamics (CD)
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Radiation Effects and Defects in Solids 165(2010), 216-226
DOI: 10.1080/10420151003631928
ISSN: 1042-0150
Cited 29 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13267
Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering
Fan, J. C.; Zhu, C. Y.; Fung, S.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Anwand, W.; Skorupa, W.; To, C. T.; Yang, B.; Beling, C. D.; Ling, C. C.
Abstract
As-doped ZnO films were grown by the radio frequency magnetron sputtering method As the substrate temperature during growth was raised above ~400°C, the films changed from n-type to p-type. Hole concentration and mobility of ~6x10^17 cm^-3 and ~6 cm^2 V^-1 s^-1were achieved. The ZnO films were studied by secondary mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the As/Zn-2V/Zn shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of As-related shallow acceptor formation.
Beteiligte Forschungsanlagen
- P-ELBE
- Journal of Applied Physics 106(2009), 073709-1-073709-6
Permalink: https://www.hzdr.de/publications/Publ-13266
Hydrodynamische Untersuchungen in Festbettreaktoren mit Gittersensoren
Schubert, M.
Abstract
Kenntnisse über die Gas/Flüssig-Strömungen in chemischen Reaktoren und Kolonnen sind von elementarer Bedeutung für die Auslegung und den effizienten Betrieb. Besonders bei der Durchströmung von Schüttungen und Packungen könnten Fehlverteilungen auftreten und damit Druckverlust und Ausbeute nachteilig beeinflussen. Die am Forschungszentrum Dresden-Rossendorf entwickelten Gittersensoren stellen eine hybride Messtechnik dar, die die Vorteiler lokalen Sonden und tomographischer Verfahren kombiniert. In porösen Packungen können Flüssigkeitsanteile und Flüssigkeitsgeschwindigkeiten mit hoher zeitlicher Auflösung im Durchströmungsquerschnitt verteilt ermittelt werden.
Der Vortrag gibt eine Übersicht zu Anwendung und Untersuchungsmöglichkeiten von Gas/Flüssig-Strömungen in Packungen mit den Schwerpunkten Strömungsvisualisierung, Holdupverteilung und Geschwindigkeitsmessung. Exemplarisch wird die Anwendung der Gittersensoren für größere Reaktordurchmesser demonstriert.
Keywords: wire mesh sensors; liquid holdup; liquid velocity; industrial scale sensor
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Sonstiger Vortrag
Seminar "Sensoranwendung in der Chemieindustrie" der BASF Ludwigshafen, 14.10.2009, Ludwigshafen, Germany
Permalink: https://www.hzdr.de/publications/Publ-13265
Spatially resolved inline measurement of liquid velocity in trickle bed reactors
Schubert, M.; Khetan, A.; Da Silva, M. J.; Kryk, H.
Abstract
The flow pattern in trickle bed reactors is of an inhomogeneous nature due to a random packing structure. Thus, the local values for liquid phase ratio and velocity are spread over the whole cross-section and a global determination of these values ignores the fact that local phenomena dominate mass and heat transfer and eventually the reactor efficiency. Only if both parameters can be locally quantified, can a realistic picture of the flow fields be drawn.
A new wire-mesh sensor (WMS) setup based on the measurement of electrical permittivity of fluids was used, which can be applied to the packings of porous catalyst particles. A calibration method is proposed to get access to the liquid saturation. Axial velocity distributions are measured via a method based on the spatial tracer pulse time-of-flight between sensing points of two WMSs installed at a distance of few millimeters. The effects of gas and liquid flow rates on local liquid velocities were analyzed.
The proposed technique was validated against liquid collector data, which showed very good agreement. For this purpose, distributions of the volumetric flow rate were calculated by applying the continuity equation to the saturation and velocity data obtained from WMS.
Keywords: Capacitance wire-mesh sensor; Trickle bed reactor; Local liquid velocity; Liquid saturation
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Chemical Engineering Journal 158(2010)3, 623-632
DOI: 10.1016/j.cej.2010.02.009
Cited 34 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13264
Co-current descending two-phase flows in inclined packed beds: experiment versus simulations
Atta, A.; Schubert, M.; Nigam, K. D. P.; Roy, S.; Larachi, F.
Abstract
The effect of inclination angle of a packed bed on its corresponding gas-liquid flow segregation and liquid saturation spatial distribution was measured in co-current descending gas-liquid flows for varying inclinations and fluid velocities, and simulated using a two-phase Eulerian computational fluid dynamics framework (CFD) adapted from trickle-bed vertical configuration and based on the porous media concept. The model predictions were validated with our own experimental data obtained using electrical capacitance tomography. This preliminary attempt to forecast the hydrodynamics in inclined packed bed geometries recommends for the formulation of appropriate drag force closures which should be integrated in the CFD model for improved quantitative estimation.
Keywords: Inclined packed bed; Hydrodynamics; Two-phase segregated flow; Multiphase flow visualization; Electrical capacitance tomography; Computational fluid dynamics
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Canadian Journal of Chemical Engeneering 88(2010)5, 742-750
DOI: 10.1002/cjce.20340
Cited 27 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13263
Hydrodynamics of co-current two-phase flows in slanted porous media - modulation of pulse flow via bed obliquity
Schubert, M.; Hamidipour, M.; Duchesne, C.; Larachi, F.
Abstract
A packed bed operated with descending gas-liquid co-current flows in slanted configuration to force trickle flow pattern to segregate due to gravity was studied, in addition to dependences to inclination angle of liquid saturation and pressure drop. Inception of pulse flow regime could take place regardless of inclination angle and the transition from segregated/trickle regime to pulse flow regime was experimentally determined. The Grosser et al.1 flow regime transition model was modified by considering only axial components of the gas and liquid superficial velocities to predict the slant-dependent shifts in transition from segregated/trickle to pulse flow and was found to agree with experimental data. Pulse flow regime at different inclinations was characterized with respect to frequency, velocity and shape of pulses. Bed obliquity was unveiled as a new artifice to pulse flow modulation with possible prospects for catalytic reactions requiring antagonistically high-interaction regime mass transfer coefficients and partial catalyst wetting.
Keywords: Packed bed hydrodynamics; inclination; segregation; electrical capacitance tomography; flow regime transition; transition model
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AIChE Journal 56(2010)12, 3189-3205
DOI: 10.1002/aic.12237
Cited 39 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13262
KKW Krümmel: Spannungs- und Ermüdungsanalyse des Kernmantels für die Transiente am 28.06.2007
Altstadt, E.; Werner, M.
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Artikel im Eigenverlag (nicht Beitrag zu HZDR-Jahresbericht)
Forschungszentrum Rossendorf 2008
FZD\FWS\2008\09
20 Seiten
ISSN: 1437-322X
Permalink: https://www.hzdr.de/publications/Publ-13261
Dynamics of Mesoscopic Magnetic Objects
Quitmann, C.; Raabe, J.; Puzic, A.; Kuepper, K.; Wintz, S.
Abstract
We report on the dynamic properties of mesoscopic magnetic objects. Such objects have dimensions somewhat larger than the magnetic exchange length ξ. This leads to relatively simple and stable patterns of the magnetization which can be excited using magnetic field pulses. The subsequent dynamics can be studied using x-ray based magnetic microscopy. We show examples of high symmetry structures where the dynamics is relatively simple and can be analyzed quantitatively in terms of amplitude, frequency, damping and symmetry. Intentional defects allow modifying specific modes. When using high amplitude excitations the magnetization in such structures can be switched.
Keywords: magnetism; dynamics; vortex; XMCD
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Beitrag zu fremdem Sammelwerk
Beaurepaire, E.; Bulou, H.; Scheurer, F.; Kappler, J.-P.: Magnetism and Synchrotron Radiation - New Trends; Springer Proceedings in Physics, Vol. 133, Berlin, Heidelberg: Springer, 2010, 978-3-642-04497-7
Permalink: https://www.hzdr.de/publications/Publ-13260
Implantation, Diffusion, Activation, and Recrystallization of Gallium Implanted in Preamorphized and Crystalline Germanium
Hellings, G.; Wündisch, C.; Eneman, G.; Simoen, E.; Clarysse, T.; Meuris, M.; Vandervorst, W.; Posselt, M.; de Meyer, K.
Abstract
We investigated the as-implanted profiles, electrical activation, diffusion, and recrystallization of gallium implanted in germanium samples through the combination of secondary-ion mass spectrometry, transmission electron microscopy, and sheet resistance measurement. Because of their high activation level (4.4 x 1020 cm−3) without preamorphization, low activation temperature (400°C), and absence of diffusion (up to 700°C), Ga junctions in crystalline Ge are very promising candidates for implementation in germanium technology. In the amorphous Ge phase, an increased diffusivity of Ga was observed at temperatures above 400°C.
Keywords: germanium gallium diffusion activation recrystallization
- Electrochemical and Solid State Letters 12(2009), H417-H419
Permalink: https://www.hzdr.de/publications/Publ-13259
Millisecond flash lamp annealing of ultra-shallow implanted layers in Ge
Posselt, M.; Wündisch, C.; Schmidt, B.; Schumann, T.; Mücklich, A.; Skorupa, W.; Clarysse, T.; Simoen, E.; Hortenbach, H.
Abstract
In the past the lack of a stable native germanium oxide for surface passivation and gate dielectrics as well as the inability to epitaxially grow sufficiently thick defect-free germanium layers on silicon hindered the integration of germanium into the mainstream Si-based technology. Recent developments, such as high-k dielectrics and germanium-on-insulator substrates have made germanium a promising candidate for future high-mobility and low-power consumption devices. Therefore, electrical doping of germanium by ion implantation and subsequent annealing has drawn a renewed interest. Investigations on the formation of ultra shallow junctions by ion beam processing have shown that p+-doping using B yields junctions that meet the requirements for the 22 nm technology node, whereas the formation of n+-junctions by P or As is complicated by the high diffusivity and the low solubility of the dopants. Recently, the concentration-dependent diffusion of n-dopants like P, As and Sb has been explored, and it has been found that doubly negatively charged vacancies are the mobile species responsible for the migration of the dopant atoms. The application of conventional rapid thermal annealing (RTA) with durations of some seconds and temperatures above about 500 °C leads to the activation of the n-dopants but their fast concentration-dependent diffusion can generally be not prevented. On the other hand it has been shown that both the diffusion and the activation of the dopants does not depend significantly on the implantation damage, i.e. using the defect engineering schemes known from Si technology seems to be not promising. Therefore, in order to control junction depth and dopant activation ultra-short annealing by flash lamps or lasers are currently under investigation.
The present work deals with the application of millisecond flash lamp annealing (FLA) to samples containing an implanted surface layer of about 100 nm thickness. P or As ions were implanted at an energy of 30 or 90 keV, respectively, and a fluence of 3x1015 cm-2. The investigations are focused on solid phase recrystallization, dopant redistribution and dopant activation. The dependence of these effects on the heat transfer to the sample during FLA as well as on pre-amorphization and pre-annealing treatment is discussed. The results are compared to typical data achievable by RTA. Different characterization methods were employed. Channeling Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy (XTEM) were used to monitor the recrystallization of the amorphous layers formed during implantation. The depth distributions of P and As were measured by secondary ion mass spectrometry. In order to determine the sheet resistance variable probe spacing and micro four point probe measurements were utilized. Selected samples were studied by XTEM to search for precipitates and end-of-range defects. While in RTA the concentration dependent dopant diffusion hinders the formation of ultra-shallow n+ layers, FLA does not cause any diffusion. The maximum activation obtained by FLA is about 4x1019 and 2x1019 cm-3 for P and As, respectively. This is about 3-4 times higher than under typical RTA conditions. However, the activation and the sheet resistance achieved by FLA do not yet fulfill the ITRS requirements for the 22 nm technology node. Possible mechanisms responsible for dopant deactivation are discussed.
Keywords: germanium flash lamp annealing ion implantation
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Eingeladener Vortrag (Konferenzbeitrag)
216th Meeting of the Electrochemical Society, Symposium E10: ULSI Process Integration 6, 04.-09.10.2009, Vienna, Austria
Permalink: https://www.hzdr.de/publications/Publ-13258
Atomistic simulation of recrystallization of amorphous Si and Ge
Posselt, M.; Gabriel, A.
Abstract
Recrystallization of amorphous Si and Ge is an important issue both in the formation of ultra-shallow junctions and in photovoltaics. In the former case the relatively high fluences applied in dopant implantation or the use of pre-amorphization implantation lead to the formation of an amorphous layer. In the first stage of annealing the solid phase epitaxial regrowth (SPER) of the amorphous layer takes place. SPER leads to redistribution of dopants, and they are incorporated into the crystal either substitutionally or within clusters containing self-interstitials or vacancies. In Si the SPER process leaves beyond the original amorphous-crystalline interface the end-of-range damage which contains an excess of self-interstitials. During further annealing, free self-interstitials are emitted from the end-of-range damage and may cause an enhanced diffusion of the dopants. It is highly desirable to understand the processes occurring during SPER on the atomic level. This work presents results of classical molecular dynamics simulations of SPER in pure Si and Ge. While in the last decade several authors investigated SPER in Si, the regrowth of amorphous Ge layers has not been considered yet.
First of all a realistic atomic system with two amorphous-crystalline interfaces which are nearly parallel to a {100} plane is prepared and characterized. The structural properties of the amorphous and crystalline parts are in very good agreement with experimental data from literature. After preparation at 300 K the system is heated to a given temperature and the regrowth of the amorphous layer is monitored by different methods including visualization and statistical analysis. Two stages are found: The initial stage (0 - 3 ns) corresponds to the SPER process. Here, the amorphous part is contiguous and its thickness is large enough so that the two interfaces do not influence each other. In the final stage (4 - 5 ns) the amorphous region becomes thinner, and finally isolated amorphous regions may exist and recrystallize independently of each other. This may lead to the generation of stacking faults and defects. For a wide temperature range regrowth velocities are calculated for the SPER process and the results are drawn in an Arrhenius plot. From this presentation the effective activation energy of SPER and the corresponding pre-exponential factor are determined. The results are compared to experimental data from literature. Furthermore, the evolution of the roughness and the morphology of the amorphous-crystalline interface are investigated.
Keywords: silicon germanium recrystallization atomistic simulation
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Vortrag (Konferenzbeitrag)
XIIIth International Autumn Meeting on Gettering and Defect Engineering in Semiconductor Technology (GADEST 2009), 26.09.-02.10.2009, Döllnsee-Schorfheide, Germany
Permalink: https://www.hzdr.de/publications/Publ-13257
Intrinsic and extrinsic diffusion of indium in germanium
Kube, R.; Bracht, H.; Chroneos, A.; Posselt, M.; Schmidt, B.
Abstract
Diffusion experiments with indium (In) in germanium (Ge) were performed in the temperature range between 550 and 900 °C. Intrinsic and extrinsic doping levels were achieved by utilizing various implantation doses. Indium concentration profiles were recorded by means of secondary ion mass spectrometry and spreading resistance profiling. The observed concentration independent diffusion profiles are accurately described based on the vacancy mechanism with a singly negatively charged mobile In-vacancy complex. In accord with the experiment, the diffusion model predicts an effective In diffusion coefficient under extrinsic conditions that is a factor of 2 higher than under intrinsic conditions. The temperature dependence of intrinsic In diffusion yields an activation enthalpy of 3.51 eV and confirms earlier results of Dorner et al. [Z. Metallk. 73, 325 (1982)]. The value clearly exceeds the activation enthalpy of Ge self-diffusion and indicates that the attractive interaction between In and a vacancy does not extend to third nearest neighbor sites which confirms recent theoretical calculations. At low temperatures and high doping levels, the In profiles show an extended tail that could reflect an enhanced diffusion at the beginning of the annealing.
Keywords: diffusion indium germanium
- Journal of Applied Physics 106(2009), 063534
Permalink: https://www.hzdr.de/publications/Publ-13256
Tests of ELBE RF-Components with Increased RF-Power
Büttig, H.; Arnold, A.; Büchner, A.; Freitag, M.; Lehnert, U.; Michel, P.; Schurig, R.; Staats, G.; Teichert, J.; Voigtländer, J.; Winter, A.
Abstract
The RF-system of the superconducting electron linac ELBE (40 MeV, 1 mA CW) is in permanent operation since 2001, but it is not completely free of RF-trips. Experience gained within eight years of operation shows that the better the RF-components were conditioned the better is their electrical stability during long time operation. To be prepared for the planned ELBE upgrade with 16 kW of RF-power per cavity several test benches have been built to study the performance of RF-couplers and waveguide windows. In cooperation with Bruker BioSpin / France and CPI / USA the prototype of a 30 kW RF-amplifier based on an IOT had been tested with beam at ELBE. This paper gives an overview about tests of RF-components with increased RF-power at ELBE.
Keywords: ELBE-RF System; Superconducting Radio Frequency; RF 1.3 GHz; RF-Power Coupler; 1.3GHz Waveguide Window; RF-Coupler Test Bench; Resonant Ring (1.3GHz); 1.3GHz CW-RF
Beteiligte Forschungsanlagen
- SRF Gun
-
Poster
14-th International Conference on RF Superconductivity,SRF09 20.-25.09.2009, 20.-25.09.2009, Berlin, Dresden, Deutschland -
Beitrag zu Proceedings
14th International conference on RF Superconductivity, SRF09, 20.-25.09.2009, Berlin, Dresden, Deutschland
Proceedings SRF 2009
Permalink: https://www.hzdr.de/publications/Publ-13255
Side Effects on the Heart and Skeleton of Growing Mice Attributed to Chronic Imatinib Exposure
Suttorp, M.; Boehme, J.; Vaitl, J.; Mosch, B.; Pursche, S.; Jung, R.; Bergmann, R.; Fischer, R.; Pietzsch, J.; Bornhaeuser, M.; Gasser, J. A.
Abstract
Objectives: Chronic myeloid leukemia (CML) is effectively treated by Imatinib (IM) via inhibition of the BCR-ABL tyrosine kinase. However, also related tyrosine kinases like abl, c-Kit, PDGF-R, and c-FMS are blocked by IM. As shown in adult humans and mice, abl-controlled protein folding as part of the endoplasmatic stress response in heart myoblasts as well as bone "remodeling" depending on PDGF-R and c-FMS is impaired under imatinib exposure (Dewar AL et al 2005, Kerkelä R et al 2006, Fitter S et al 2008). The influence of IM on the growing heart and skeleton of immature animals has not been studied so far. With respect to treatment of pediatric CML we report alterations in these organs of juvenile mice chronically exposed to IM during the growth period.
Methods: From the age of 414 weeks (w) [development milestones of mice: weaning 3 w; puberty 7 w; epiphysial lines closure 18 w] C3H/Neu male and female wild-type mice were chronically exposed to IM via the drinking water at concentrations of 500 mg/l (group A), 750 mg/l (group B), and 1000mg/l (group C). Femur length and overall skeletal development was analysed by whole body X-ray analysis using a mammography device. Bone metabolic activity was assessed by total body Na18F PET and CT after 5w and 10w of exposure using dedicated small animal tomographs. Bone mineral density and microstructure of tibiae were analysed by pQCT and microCT (resolution 12.5µ m) while the number of osteoclasts and resorption lacunae in femora and vertebrae was assessed by histomorphometry. Plasma concentration of IM, osteocalcin, and activity of the tartrate resistant acid phosphatase (TRAP5b) was also determined. The heart was examined histologically and ultrastructurally by electron microscopy.
Results: IM was tolerated well and mean uptake of 80 mg/kg/d
A. 110 mg/kg/d
B. and 150 mg/kg/d
C. resulted in serum levels of 60674 ng/ml, 36242 ng/ml and 51534 ng/ml, respectively.
Body weight gain was delayed in groups B and C until the age of 8 w while no change in overall growth, development and behaviour was observed at 14 w. At higher doses of IM and at younger age there was a non-significant trend to a reduction in femur length. Heart morphological examination exhibited an increased number (p<0.05) of hypertrophic cardiomyocytes (toxic damage) paralleled by ultrastructural alterations in mitochondria, myofibrils, and nucleus. In the skeleton, no significant differences compared to controls concerning 18F-kinetics and uptake in vertebrae and femura could be demonstrated. However, IM dose-dependently reduced the number of osteoclasts and resorption lacunae (p<0.05); these effects were less pronounced in female mice. Tibia cortical thickness was increased significantly in males by 6.1% (B) and 11.2% (C), respectively, and 7.5% in females (C). By microCT cancellous bone exhibited a significant increase in trabecular bone mass density and volume and number resulting in an increase in trabecular connectivity in males by 63% (B) and 64% (C), respectively, and in females by 22% (B) and 38% (C), respectively. Bone biomarkers indicated a significant reduction of TRAP5b activity while osteocalcin levels remained unchanged.
Conclusion: In juvenile mice, a chronic exposure of IM resulted in toxic damage of the cardiomyocytes at higher dose rates. However, these alterations do not necessarily imply also a functional impairment which can only be studied in vivo. In the skeleton, IM reduced the number of osteoclasts and resorption lacunae in long bones but not in vertebrae. IM showed an antiresorptive effect in cancellous bone and increased cortical thickness and trabecular number by inhibiting the expansion of the marrow cavity. The effects were more pronounced in male mice and at younger age.
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Poster
Annual Meeting American Society of Hematology, 06.-09.12.2008, San Francisco, USA -
Abstract in referierter Zeitschrift
BLOOD 112(2008), 402
Permalink: https://www.hzdr.de/publications/Publ-13254
NMR Studies and Crystal Structure Determinations of CF3 Group-containing Bicyclic phenolates
Mamat, C.; Reinke, H.; Langer, P.
Abstract
Three new CF3-substituted bicyclic Salicylate derivatives were synthesized by the TiCl4-mediated cyclization Of trifluoromethyl-containing ketones with 1,3-bis(silyl enol ethers) and characterized by NMR and IR, spectroscopy, Mass spectrometry and elemental analysis. The crystal structures of the bicyclic derivatives have been determined by single crystal X-ray analysis. All structures exhibit hydrogen bonding.
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Zeitschrift für Naturforschung Section B - A Journal of Chemical Sciences 64(2009)4, 423-426
ISSN: 0932-0776
Permalink: https://www.hzdr.de/publications/Publ-13252
Luminescence properties of uranium(VI) citrate and uranium(VI) oxalate species and their application for the determination of complex formation constants
Günther, A.; Steudtner, R.; Schmeide, K.; Bernhard, G.
Abstract
For the first time, the interaction of uranium(VI) with citric acid and oxalic acid in aqueous solution was investigated using time-resolved laser-induced fluorescence spectroscopy (TRLFS) between pH 2 and 4. The complex species UO2cit− and (UO2)2(cit)22− formed in citrate medium as well as UO2ox and UO2(ox)22- formed in oxalate medium show no luminescence emissions at room temperature. However, by coupling the fluorescence measurement technique with a low temperature system (-120 °C, cryo-TRLFS), emission signals of the various complex species could be detected. The emission signals are bathochromic shifted in comparison to the emission maxima of the uncomplexed uranyl(VI) cation. Using the spectroscopic data, the corresponding complex formation constants were calculated, which corroborate literature data.
Keywords: uranium(VI); citric acid; oxalic acid; time-resolved laser-induced fluorescence spectroscopy; cryogenic measurement technique
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Radiochimica Acta 99(2011), 535-541
DOI: 10.1524/ract.2011.1847
Cited 28 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13251
QCD Sum Rules for D and Ds Mesons in Dense and Hot Nuclear Matter
Hilger, T.
Abstract
Tool: QCD sum rules, Goal: D mesons → CBM / FAIR, Outlook: charm near Tc
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Vortrag (Konferenzbeitrag)
International Conference on Strangeness in Quarkmatter 09 (SQM 09), 27.09.-02.10.2009, Buzios, Brazil
Permalink: https://www.hzdr.de/publications/Publ-13250
Radiokupfer-markierte Peptide auf der Basis neuer bifunktioneller Chelatliganden
Stephan, H.; Bergmann, R.; Steinbach, J.
Abstract
Die erfolgreiche klinische Anwendung von radioaktiv markierten Somatostatin-Peptid-Analogen für die Bildgebung von rezeptorexprimierenden Tumoren hat die Modifizierung anderer Regulatorpeptide wie Neurotensin, RGD-Peptide oder Bombesin als mögliche Tumordiagnostika und therapeutika vorangetrieben.[1] Auf dem Weg zu diesen neuen radioaktiven Arzneimitteln sind eine Reihe unterschiedlicher Aufgaben zu lösen. Das betrifft insbesondere die Entwicklung von chemisch und radiolytisch stabilen Verbindungen, die eine unkomplizierte Markierung der Peptide mit geeigneten Radionukliden erlauben. 99mTc-, 64Cu- und 68Ga-markierte Peptide eignen sich dabei prinzipiell zur Tumordiagnostik. Analoge Verbindungen mit den Partikelstrahlern 67Cu und 188Re weisen ein großes Potenzial zur Therapie von Tumoren auf. Zur stabilen Fixierung von radioaktiven Kupfernukliden sind beispielsweise Pyridin-haltige makrocyclische Amine I und Bispidin-Liganden II entwickelt worden, die gleichzeitig eine Konjugation von Peptiden erlauben. Auf der Basis stabilisierter Bombesinderivate konnten durch Anwendung geeigneter Peptidkupplungsreaktionen entsprechende Biokonjugate hergestellt werden. Diese Verbindungen bilden unter physiologischen Bedingungen mit schneller Kinetik sehr stabile Radiokupferkomplexe. Ligandenaustauschexperimente und radiopharmakologische in-vitro- und in-vivo-Untersuchungen belegen eine sehr hohe Komplexstabilität. Studien zur Bioverteilung eines Bombesinkonjugates mit I ergaben eine hohe Anreicherung im Pankreas, dem Zielorgan mit der höchsten Dichte am Gastrin Releasing Peptidrezeptor.[2] PET-Studien an PC3-Tumor-Mäusen unter Einsatz des 64Cu markierten Bispidin-Bombesin-Derivates belegen eine gute Tumoranreicherung dieser Verbindung sowie eine klare Visualisierung des Tumors.[3]
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Vortrag (Konferenzbeitrag)
GDCh-Wissenschaftsforum Chemie 2009, 30.08.-02.09.2009, Frankfurt/M., Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13249
Autoradiographic studies of rhenium-188-hydroxyethylidine diphosphonate in normal skeleton and osteoblastic bone metastases in a rat model of metastatic prostate cancer
Liepe, K.; Geidel, H. H.; Bergmann, R.; Haase, M.; Runge, R.; Kotzerke, J.
Abstract
Aim
The quantitative distribution of bone-seeking radiopharmaceuticals in trabecular bone, cortical bone and in skeletal metastases is required for calculation of radiation-absorbed dose in radionuclide therapy. An animal model of intraosseous tumor cell administration was developed to simulate osteoblastic metastases for autoradiographic study of radionuclide localization.
Methods In 45 Copenhagen rats R3327-MATLyLu syngeneic prostate cancer cells were given intraosseously in both the femori. Rhenium-188-hydroxyethylidine diphosphonate (HEDP) was administered intravenously 17 +/- 1 days after cells instillation and these animals were euthanized at 4, 24 and 48 h after injection of the radiopharmaceutical. The uptake of radiopharmaceutical was estimated in normal skeleton and the bone metastases by means of region of interest analysis using autoradiography. The tumor to nontumor ratio and the fractional uptake in cortical bone and trabecular bone were quantified.
Results
The uptake of rhenium-188-HEDP in cortical bone was 33.5% and in trabecular bones was 66.5% after 4 h, 34.6 and 65.4% after 24 h, and 35.9 and 64.1% after 48 h, respectively. Assuming a theoretic cortical-trabecular distribution of 50-50%, (MIRDOSE) calculation, radiation-absorbed dose to bone marrow was underestimated by 26%. In bone metastases, an inhomogeneous distribution with a minimal and maximal tumor to nontumor ratio of 3:1 and 14:1 after 4 h, 5: 1 and 14: 1 after 24 h, and 5:1 and 16:1 after 48 h was observed.
Conclusion
The MIRDOSE model underestimates the radiation-absorbed dose to the bone marrow because of demonstrable differences in the uptake of rhenium-188-HEDP in cortical and trabecular bone and inhomogeneous uptake in skeletal metastases.
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Nuclear Medicine Communications 30(2009), 693-699
DOI: 10.1097/MNM.0b013e32832cc23c
ISSN: 0143-3636
Cited 9 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13248
Prätherapeutisches [18F]FMISO hypoxisches Volumen ist ein signifikanter prognostischer Faktor für die lokale Tumorkontrolle nach Einzeldosisbestrahlung von FaDu-Tumoren in Nacktmäusen/Pretherapeutic [F-18]FMISO hypoxic volume is a significant prognostic factor for local tumour control after single dose radiation of FaDu- tumours in night mouse
Schütze, C.; Bergmann, R.; Mosch, B.; Yaromina, A.; Zips, D.; Hessel, F.; Thames, H. D.; Mäding, P.; Kotzerke, J.; Baumann, M.; Beuthien-Baumann, B.
Abstract
Hintergrund:
Präklinische und klinische Untersuchungen haben gezeigt, dass das Ausmaß der prätherapeutischen Tumorhypoxie das Ergebnis einer Strahlentherapie solider Tumoren beeinflusst. Derzeit werden strahlentherapeutische Interventionen wie z. B. Dosis-Eskalation partieller hypoxischer Subvolumina untersucht. In dieser Studie wurde in einer einzelnen, in Nacktmäusen transplantierten humanen Tumorzelllinie untersucht, ob das prätherapeutische [18F]FMISO hypoxische Tumorvolumen (HV) oder die Intensität des Tracer-uptakes (maximaler Standard uptake
value SUVmax) mit der lokalen Tumorkontrolle nach Einzeldosisbestrahlung korreliert.
Methoden:
Die hSCC Zelllinie FaDu wurde subkutan auf das rechte Hinterbein von NMRI Nacktmäusen transplantiert. 70 Tiere wurden bei einem Tumorvolumen von 165-343 mm³ in das Experiment aufgenommen. Jedes Tier erhielt am Tag 0 eine PET-Untersuchung (MicroPET® P4, CTI Molecular Imaging Inc) mit dem Hypoxie-Marker 18F]FMISO ([18F]Fluormisonidazol) unter Anästhesie. Die Auswertung erfolgte mittels 3D-regions of interest über dem Tumor (ROVER software, ABX GmbH, Radeberg, Germany). Bestimmt wurde das [18F]FMISO hypoxische Volumen (HV) und der SUVmax. Anschließend wurden die Tumoren entsprechend des medianen hypoxischen Volumens für Einzeldosisbestrahlungen mit 25 Gy oder 35 Gy unter normalem Blutfluss randomisiert. Die Einzeldosisbestrahlungen erfolgten mit 200 kV Röntgenstrahlen (0.5 mm Cu, ~ 1 Gy min-1). Der experimentelle Endpunkt war die lokale Tumorkontrolle am Tag 120 nach Bestrahlung.
Ergebnisse:
Die lokalen Tumorkontrollraten nach Bestrahlung mit 25 Gy waren niedriger als nach Bestrahlung mit 35 Gy (22% vs. 69%, Logrank-Test p< 0.0001). Die Spanne der HV reichte von 38-353 mm³, der Median HV betrug 112 mm³ (95%CI: 92; 128 mm³). Für Tumoren < Median HV betrug die lokale Kontrollrate 33% nach 25 Gy vs. 82% nach 35 Gy (p=0.001). In Tumoren > Median HV betrug die lokale Kontrollrate 15% nach 25 Gy vs. 53% nach 35 Gy (p=0.0005). In der multivariaten Cox-Analyse konnte nach Korrektur für Dosis und Tumorvolumeneffekte ein signifikanter Effekt des HV als kontinuierliche Variable (p=0.009) oder dichotome Variable (Stratifikation entsprechend des Median HV) (p=0.039) nachgewiesen werden. Der SUVmax war bezüglich der Prognose der Heilungswahrscheinlichkeit nicht relevant.
Schlussfolgerungen:
Das [18F]FMISO hypoxische Tumorvolumen ist ein signifikanter unabhängiger Prädiktor für das Ergebnis einer Bestrahlung mit hohen Einzeldosen in FaDu hSCC. Diese Ergebnisse unterstützen die Hypothese, dass ein prätherapeutisches [18F]FMISO-PET wichtige Informationen für die Verschreibung einer heterogenen Bestrahlungsdosis in
hypoxischen Subvolumina individueller Tumoren liefern kann. Weitere Experimente mit anderen Tumormodellen und fraktionierter Bestrahlung sind notwendig.
Gefördert im Rahmen des EU-Projektes BioCare Molecular Imaging for Biologically Optimized Cancer Therapy proposal# 505785 und DFG Projekt Ba 1433.
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Vortrag (Konferenzbeitrag)
DEGRO 2009 - 15. Jahreskongress der Deutschen Gesellschaft für Radioonkologie, 11.-14.06.2009, Bremen, Deutschland -
Abstract in referierter Zeitschrift
Strahlentherapie und Onkologie 185(2009)Suppl. 1, 22-23
ISSN: 0179-7158
Permalink: https://www.hzdr.de/publications/Publ-13247
InIII and GaIII Complexes of Sugar-Substituted Tripodal Trisalicylidene Imines: The First 68Ga-Labelled Sugar Derivative
Gottschaldt, M.; Bohlender, C.; Pospiech, A.; Görls, H.; Walther, M.; Müller, D.; Klette, I.; Baum, R. P.; Schubert, U. S.
Abstract
Gallium and indium complexes derived from salicylaldimines of 1,1,1-tris(aminomethyl)ethane (TAME) with pendantxylose, glucose and galactose units have been synthesised as model compounds for potential application as radiotracers. The formed neutral complexes have been characterised by NMR spectroscopy, elemental analysis, mass spectrometry and, in the case of the galactose-bearing InIII complex, by single-crystal X-ray structure analysis. Octahedral coordination was observed with the appearance of an equilibrium of - and -isomers at the metal centre. The glucose-appended ligand was radiolabelled with 68GaIII ions in up to 98 % yield depending on the prevailing pH value. The in vitro stability of the radioactive complex was examined by challenge experiments against apo-transferrin and blood plasma. Very high stability was observed; even after a period of 2 h, 90 % of the complex could still be detected.
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European Journal of Inorganic Chemistry 28(2009), 4298-4307
DOI: 10.1002/ejic.200900561
Cited 7 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-13246
Circulating S100A12: a novel player in atherosclerosis?
Pietzsch, J.
Abstract
S100A12 is a member of the S100 family of EF-hand calcium-binding proteins. Besides calcium binding S100A12 also shows high affinity for zinc and copper ions. Extracellular S100A12 is predominantly secreted by granulocytes and monocytes and is part of the innate immune response.
S100A12 is markedly overexpressed in inflammatory compartments, and elevated serum levels of S100A12 are found in patients suffering from various inflammatory and metabolic disorders. In this regard, binding of copper by S100A12 is assumed to play a pathogenic role. In vitro experiments show that copper-bound S100A12 can function as a pro-oxidant agent by supporting both copper reduction and copper redox-cycling, respectively. As a consequence, copper-bound S100A12 enhances and accelerates oxidation of human low density lipoprotein lipids and apolipoproteins, respectively. Furthermore, copper-bound S100A12 stimulates proinflammatory activation of endothelial cells, granulocytes, and monocytes. These processes were substantially suppressed in the presence of redox-inert copper-chelating or radical-scavenging agents. Clinical examinations show significantly elevated plasma S100A12 levels in subjects with impaired glucose tolerance, newly-diagnosed diabetes mellitus Type 2, and acute rheumatoid arthritis (1.5 to 3-fold higher than in control subjects). In the patient groups, plasma S100A12 is strongly associated with plasma markers of both LDL oxidation and inflammation, and, additionally, with ultrasonically measured carotid atherosclerosis. It is suggested that oxidation processes mediated by copper-bound S100A12 are involved in accelerated atherogenesis in proinflammatory states.
Supported by Deutsche Forschungsgemeinschaft (Pi 304/1-1)
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Eingeladener Vortrag (Konferenzbeitrag)
11th International Congress on Amino Acids, Peptides and Proteins, 03.-07.08.2009, Wien, Österreich -
Abstract in referierter Zeitschrift
Amino Acids 37(2009)Suppl. 1, S78
DOI: 10.1007/s00726-009-0320-1
ISSN: 0939-4451
Permalink: https://www.hzdr.de/publications/Publ-13245
Molecular imaging of the receptor for advanced glycation endproducts
Pietzsch, J.; Hoppmann, S.
Abstract
The receptor for advanced glycation endproducts (RAGE) is a member of the immunoglobulin superfamily and has been implicated in the pathogenesis of various disorders including inflammatory processes and cancerogenesis. However, data concerning the functional expression of RAGE in inflammatory compartments and other pathologies in vivo are scarce. We report a multi-radiotracer approach using radiolabeling of various RAGE ligands, including glycated low-density lipoproteins (glycLDL), glycated albumin (glycBSA), and S100 proteins (S100B and S100A12) with the positron emitter fluorine-18 (18F) and the application of 18F-labeled RAGE ligands in dynamic small animal positron emission tomography (PET) studies. Radiolabeling of proteins was performed by conjugation with N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) causing no adverse alterations of the biological functionality of the proteins in vitro. Biodistribution and metabolite studies in rodent normal, inflammatory, and tumor models revealed high stability for the 18F-RAGE ligands in vivo. The in vivo kinetics of 18F-RAGE ligands, with or without presence of specific ligands or inhibitors of RAGE and, additionally, various scavenger receptors, in rodent models was quantified by PET, and correlated well with the anatomical localization of RAGE, e.g., in lung, endothelium, inflammatory lesions, and tumors.
18F-radiolabeling of glycLDL, glycBSA, and S100 proteins and the use of small animal PET provide a potential approach to measure the functional expression of RAGE under normal and pathophysiological conditions in vivo.
Supported by Deutsche Forschungsgemeinschaft (Pi 304/1-1)
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Eingeladener Vortrag (Konferenzbeitrag)
11th International Congress on Amino Acids, Peptides and Proteins, 03.-07.08.2009, Wien, Österreich -
Abstract in referierter Zeitschrift
Amino Acids 37(2009)Suppl. 1, S39
DOI: 10.1007/s00726-009-0320-1
ISSN: 0939-4451
Permalink: https://www.hzdr.de/publications/Publ-13244
Fluorine-18 radiolabeling of S100/calgranulins: potential probes for molecular imaging of receptor for advanced glycation endproducts
Hoppmann, S.; Haase, C.; Richter, S.; Strobel, K.; Steinbach, J.; Pietzsch, J.
Abstract
The interaction of S100/calgranulins, a multigenic family of Ca2+-modulated proteins, with the receptor for advanced glycation endproducts (RAGE) is hypothesized to be of high relevance in the pathogenesis of various diseases including cardiovascular diseases, inflammatory processes, and cancerogenesis. However, data concerning the role of circulating S100 proteins in these pathologies are scarce. Furthermore, it is currently not known whether RAGE is an universal S100 receptor. One reason for this is the shortage of suitable radiolabeling methods for direct assessment of the metabolic fate of circulating S100 proteins in vivo. We report a novel radiotracer approach using radiolabeling of recombinant human S100A1 with the positron emitter-fluorine-18 (18F) by conjugation with N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) and the use of [18F]fluorobenzoylated S100A1 (18F-S100A1) in dynamic small animal positron emission tomography (PET) studies in rats. Human S100A1 was cloned as a fusion protein in the bacterial expression vector pGEX-6P-1 and expressed in E. coli strain BL21. Radiolabeling of S100A1 with [18F]SFB at pH 7.4 resulted in 18F-S100A1 specifically labeled at the N-terminal glycine residue with radiochemical yields of 2-6% (decay-corrected) and effective specific activities of 0.5-1 GBq/µmol, respectively. In vitro experiments, and biodistribution and metabolite studies in rats in vivo revealed high stability for the 18F-S100A1. The metabolic fate of 18F-S100A1 in rats in vivo was delineated by dynamic PET studies using a dedicated small animal PET system. The organ-specific in vivo distribution and kinetics of 18F-S100A1 correlated well with the anatomical localization of RAGE, e.g., in lungs and in the vascular system. In the presence of molar excess of glycated human low density lipoprotein (glycLDL), a well characterized RAGE ligand, the mean plasma residence time of circulating 18F-S100A1 increased by 40% from 29.6 ± 1.5 min to 41.3 ± 2.1 min and, vice versa, tissue-associated retention of 18F-S100A1 decreased by approximately 50% in lungs and 32% in large blood vessels, respectively. These findings indicate first circulating S100A1 to be a specific ligand for RAGE in rats in vivo. In conclusion, radiolabeling of S100/calgranulins with 18F and the use of small animal PET provide novel probes to delineate functional expression of RAGE under normal and pathophysiological conditions in rodent models of disease in vivo.
Keywords: multiligand receptors; pattern recognition; S100 proteins; 18F-labeled prosthetic group; small animal positron emission tomography; animal models
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Beitrag zu fremdem Sammelwerk
Xiaoyuan Chen: Recent Advances of Bioconjugation Chemistry in Molecular Imaging, Kerala (India): Trivandrum: Research Signpost, 2008, 978-81-308-0210-7, 329-351
Permalink: https://www.hzdr.de/publications/Publ-13243
Synthesis, 64Cu-Labeling and Biodistribution of DOTA-Glycodendrimers
Jäger, K.; Stephan, H.; Bergmann, R.; Steinbach, J.; Appelhans, J.; Voit, D.
Abstract
The utilization of dendrimers in medicine holds great potential in emerging applications of diagnostic imaging, as well as the promise of new capabilities for delivering therapies tailored and targeted for specific diseases. In this perspective, radiolabeled dendritic frameworks are gaining in importance, particularly for the use in tumor imaging and therapy.[1] Pegylation as well as carbohydration of radiolabeled compounds is of considerable interest to improve the pharmacokinetics, biocompatibility, and tumor accumulation.[2,3]
In this context, DOTA-modified glycodendrimers with dense maltose shell (Figure: structure of 4th generation dendrimer) were selected from the point of view to use the highly homogenous dendritic structure for improved tumor imaging and therapy and to enhance the biocompatibility of dendrimers by the decoration with carbohydrates. The outcome of the synthetic effort was the synthesis of 4th and 5th generation glycodendrimers with the variation of chemically attached DOTA chelators (1, 3, 9 DOTA units/4th generation dendrimer; 9 and 18 DOTA units/5th generation dendrimer), which form stable complexes with a large number of radiometals. The multivalent decoration with DOTA on dendrimer surface was also stimulated by the facts that radiolabeling kinetics can be accelerated and to achieve enhanced specific activity.
The labeling conditions of the glycodendrimers synthesized with 64Cu were optimized, and the influence of reaction time, temperature, buffer conditions and the dendrimer amount on the radiochemical yield were studied using Radio-TLC and Radio-SEC. The radiocopper(II) complexes of the DOTA-functionalized glycodendrimers show a high in vitro stability. Preliminary biodistribution studies of 64Cu-labeled 4th generation dendrimers with maltose shell in healthy Wistar rats indicate the preferred accumulation in the liver.
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Poster
GDCh-Wissenschaftsforum Chemie 2009, 30.08.-02.09.2009, Frankfurt am Main, Deutschland
Permalink: https://www.hzdr.de/publications/Publ-13242
Visualizing inflammation activity in rheumatoid arthritis with Tc-99m Anti-CD4-mAb fragment scintigraphy - First results of a proof of principle study
Steinhoff, K.-G.; Pierer, M.; Sorger, D.; Seese, A.; Künstler, J. U.; Emmrich, F.; Sabri, O.; Hesse, W.; Siegert, J.; Piegla, U.; Pietzsch, H.-J.; Seidel, W.; Laub, R.
Abstract
T‐cell‐located CD4 antigen represents one of the therapeutic targets in rheumatoid arthritis (RA). However, up to now it has not been possible to visualize this target in vivo. The aim of our study was to assess the safety and tolerability of a Technetium 99 labelled anti‐CD4 antibody fragment (Tc‐99m‐anti‐CD4) in patients with active synovitis due to rheumatoid arthritis and to evaluate its potential as a marker of disease activity. Methods: In the present phase I proof of principle study 5 patients (3 female, 2 male, 58 to 71 years) with RA were examined. Planar whole body scans as well as separate hand and feet scintigraphies were taken 30 minutes, 1, 2, 4, 8 and 24 hours after application of 585 +/‐ 115 MBq Tc‐99m‐anti‐CD4. The obtained scintigramms were analysed visually and compared with clinical data in 68 joints per patient. Active inflammation was clinically defined by swelling and tenderness in at least one joint (gold standard). Patients were clinically re‐evaluated 7 days p.i. Results: Neither infusion related adverse events nor adverse events during follow up were observed. No increase in HAMA titres was seen. All 5 patients had positive scans in 25 of 37 clinically affected joints. Positive scans were also found in 19 out of 227 joints without evidence of swelling or tenderness yielding a 7% rate of false positive joints and a 32% rate of false negative joints. Conclusion: Scintigraphy with Tc‐99m‐anti‐CD4 is a new promising technique for evaluation of inflammatory activity in patients with RA. Tracer uptake in clinically inconspicuous joints strongly indicates diagnostic potential of 99Tc anti CD4. Based on the few patients investigated, it seems that inflammation is detected with apparently higher specificity than sensitivity. Whether this technique is eligible for prognostic disease evaluation needs to be analysed in further studies as well as the pathophysiological background of clinically affected joints lacking tracer uptake.
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Vortrag (Konferenzbeitrag)
Annual Congress of the European Association of Nuclear Medicine 2009 (EANM), 10.-14.10.2009, Barcelona, Spain -
Abstract in referierter Zeitschrift
European Journal of Nuclear Medicine and Molecular Imaging 36(2009)Suppl. 2, S210
ISSN: 1619-7070
Permalink: https://www.hzdr.de/publications/Publ-13241
Synthesis and biological evaluation of new [Tc(N)(R2PS)]-based mixed compounds as analogues of WAY 100635
Bolzati, C.; Cavazza-Ceccato, M.; Refosco, F.; Salvarese, N.; Pietzsch, H.-J.; Bergmann, R.; Bandoli, G.
Abstract
Aim: This study was focused on evaluating the applicability of a new labelling procedure to the preparation of Tc(N)‐based target specific compounds. The chemistry is based on the use of the [Tc(N)Cl(R2PS)(PPh3)] species (R2PS = alkyl‐phosphino‐thiolate ligand), which selectively reacts with an appropriate mono‐negative chelate, such as a dithiocarbamate (DTC), to give neutral [Tc(N)(R2PS)(DTC)] compounds. The 2‐methoxyphenylpiperazine (2‐MPP) pharmacophore, which displays a potent and specific affinity for 5HT1A receptors, was selected as functional group and conjugated to the dithiocarbamate unit through different spacers. Method: The synthesis of [99m/99gTc(N)(R2PS)(Ln)] complexes, and their in vitro stability as well as their biological in‐vitro and in‐vivo assays were investigated. Stability studies were performed by considering: i) stability toward transchelation with Cysteine and Glutatione ii) binding to the serum proteins; ii) stability in rat serum, human serum and rat liver homogenates. The in vitro affinity for the 5HT1A receptors of the technetium complexes was assessed by measuring the ability of the compounds to compete with [3H]‐8‐OH‐DPAT binding in isolated membranes from rat cerebral cortex. The biodistribution profile of the best radiolabeled compound and its in vivo stability were evaluated in Sprague‐Dawley rats. Results: [99mTc(N)(R2PS)(Ln)] complexes were prepared in high yield (>90%) using a multi‐step procedure. The chemical identity of 99mTc‐complexes was determined by HPLC comparison with the corresponding 99gTc‐complexes. All complexes were found to be inert toward transchelation with an excess of free Glutathione and Cysteine. No significant in vitro serum protein binding and no notable biotransformation of the native compound into different species by the in vitro action of the serum and liver enzymes were shown. Nanomolar affinities for the 5‐HT1A receptor were obtained for [99mTc(N)(PSiso)L3] (IC50 = 1.5 nM), a reduction of the affinity were observed for the other complexes as a function of the reduction of the alkyl chain length interposed between the DTC group and the bioactive molecule. A negligible brain uptake was displayed from in vivo distribution data of [99mTc(N)(PSiso)L3]. Conclusion This work describes the application of a new labelling procedure for incorporating a bioactive molecule into a stable dissymmetric 99mTc(N)‐complex. Despite the favourable binding properties, the lack of BBB penetration indicates that these particular complexes may not be useful for CNS‐receptor mapping. Further studies should be performed in order to clarify the reason for this behaviour and to evaluate the usefulness in peripheral applications.
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Vortrag (Konferenzbeitrag)
Annual Congress of the European Association of Nuclear Medicine (EANM) 2009, 10.-14.10.2009, Barcelona, Spain -
Abstract in referierter Zeitschrift
European Journal of Nuclear Medicine and Molecular Imaging 36(2009)Suppl. 2, S220
ISSN: 1619-7070
Permalink: https://www.hzdr.de/publications/Publ-13240
Photochemistry of uranium(VI) revisited: A density functional theory study
Tsushima, S.; Fahmy, K.
Abstract
Photochemical reduction of uranium(VI) in the presence of organic substances is a well known and well studied process, but its reaction mechanism has not yet been fully verified. One of the difficulties in studying uranium photochemistry is the involvement of photo-excited states which is difficult to assess solely by experiments. Quantum chemical calculation is capable of predicting the properties of excited state uranium(VI), and therefore can provide possible photochemical reaction mechanisms and reaction pathways. Here, we have studied the photochemical reduction of uranium(VI) in the presence of several organic ligands, namely methanol, ethanol, and oxalic acid, by density functional theory (DFT) calculations. We were able to reproduce entire reaction pathways which demonstrates the validity of the DFT approach in further exploring uranium(VI) photochemistry.
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Vortrag (Konferenzbeitrag)
Spring 2010 National Meeting and Exposition, Symposium on "Lanthanides and Actinides: a Chemist's Perspective", 21.-25.03.2010, San Francisco, U.S.A.
Permalink: https://www.hzdr.de/publications/Publ-13239
Jahre: 2024 2023 2022 2021 2020 2019 2018 2017 2016
Seiten: [1.] [2.] [3.] [4.] [5.] [6.] [7.] [8.] [9.] [10.] [11.] [12.] [13.] [14.] [15.] [16.] [17.] [18.] [19.] [20.] [21.] [22.] [23.] [24.] [25.] [26.] [27.] [28.] [29.] [30.] [31.] [32.] [33.] [34.] [35.] [36.] [37.] [38.] [39.] [40.] [41.] [42.] [43.] [44.] [45.] [46.] [47.] [48.] [49.] [50.] [51.] [52.] [53.] [54.] [55.] [56.] [57.] [58.] [59.] [60.] [61.] [62.] [63.] [64.] [65.] [66.] [67.] [68.] [69.] [70.] [71.] [72.] [73.] [74.] [75.] [76.] [77.] [78.] [79.] [80.] [81.] [82.] [83.] [84.] [85.] [86.] [87.] [88.] [89.] [90.] [91.] [92.] [93.] [94.] [95.] [96.] [97.] [98.] [99.] [100.] [101.] [102.] [103.] [104.] [105.] [106.] [107.] [108.] [109.] [110.] [111.] [112.] [113.] [114.] [115.] [116.] [117.] [118.] [119.] [120.] [121.] [122.] [123.] [124.] [125.] [126.] [127.] [128.] [129.] [130.] [131.] [132.] [133.] [134.] [135.] [136.] [137.] [138.] [139.] [140.] [141.] [142.] [143.] [144.] [145.] [146.] [147.] [148.] [149.] [150.] [151.] [152.] [153.] [154.] [155.] [156.] [157.] [158.] [159.] [160.] [161.] [162.] [163.] [164.] [165.] [166.] [167.] [168.] [169.] [170.] [171.] [172.] [173.] [174.] [175.] [176.] [177.] [178.] [179.] [180.] [181.] [182.] [183.] [184.] [185.] [186.] [187.] [188.] [189.] [190.] [191.] [192.] [193.] [194.] [195.] [196.] [197.] [198.] [199.] [200.] [201.] [202.] [203.] [204.] [205.] [206.] [207.] [208.] [209.] [210.] [211.] [212.] [213.] [214.] [215.] [216.] [217.] [218.] [219.] [220.] [221.] [222.] [223.] [224.] [225.] [226.] [227.] [228.] [229.] [230.] [231.] [232.] [233.] [234.] [235.] [236.] [237.] [238.] [239.] [240.] [241.] [242.] [243.] [244.] [245.] [246.] [247.] [248.] [249.] [250.] [251.] [252.] [253.] [254.] [255.] [256.] [257.] [258.] [259.] [260.] [261.] [262.] [263.] [264.] [265.] [266.] [267.] [268.] [269.] [270.] [271.] [272.] [273.] [274.] [275.] [276.] [277.] [278.] [279.] [280.] [281.] [282.] [283.] [284.] [285.] [286.] [287.] [288.] [289.] [290.] [291.] [292.] [293.] [294.] [295.] [296.] [297.] [298.] [299.] [300.] [301.] [302.] [303.] [304.] [305.] [306.] [307.] [308.] [309.] [310.] [311.] [312.] [313.] [314.] [315.] [316.] [317.] [318.] [319.] [320.] [321.] [322.] [323.] [324.] [325.] [326.] [327.] [328.] [329.] [330.] [331.] [332.] [333.] [334.] [335.] [336.] [337.] [338.] [339.] [340.] [341.] [342.] [343.] [344.] [345.] [346.] [347.] [348.] [349.] [350.] [351.] [352.] [353.] [354.] [355.]