Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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31745 Publications
Modifizierbare Tc(III)/Re(III) Gemischtligandkomplexe zur Kopplung an Biomoleküle
Pietzsch, H.-J.;
  • Lecture (others)
    10. Arbeitstreffen der Arbeitsgemeinschaft Radiochemie / Radiopharmazie, Wien, 12.-14.09.2002

Publ.-Id: 5163 - Permalink


Erste Ergebnisse zu 18F-Molekülen mittels Komplexierungsreaktion
Noll, B.; Noll, S.; Wester, H.-J.;
  • Lecture (others)
    10. Arbeitstreffen der Arbeitsgemeinschaft Radiochemie / Radiopharmazie, Wien, 12.-14.09.2002

Publ.-Id: 5162 - Permalink


Sonogashira Reaktion mit 4-[18F]Fluoriodbenzol: eine neue Methode zur C-C Bindungsknüpfung in der 18F-Chemie
Knieß, T.;
  • Lecture (others)
    10. Arbeitstreffen der Arbeitsgemeinschaft Radiochemie / Radiopharmazie, Wien, 12.-14.09.2002

Publ.-Id: 5161 - Permalink


Synthese von 4-[18F]Fluormethyl-2-Chlor-Phenylisothiocyanat: eine neue prosthetische Gruppe zur Kopplung an Aminogruppen
Müller, M.;
  • Lecture (others)
    10. Arbeitstreffen der Arbeitsgemeinschaft Radiochemie / Radiopharmazie, Wien, 12.-14.09.2002

Publ.-Id: 5160 - Permalink


Homocystein: Von der Spezialanalyse zum Routineparameter
Pietzsch, J.;
  • Bioforum 9 (2002) 577-580

Publ.-Id: 5159 - Permalink


Protective effects of native but not oxidized HDL against proinflammatory respiratory burst activities of polymorphonuclear leukocytes induced by hypochlorite-oxidized LDL
Kopprasch, S.; Pietzsch, J.; Gräßler, J.;
  • Book (Authorship)
    In: Van Dyke, K.; Van Dyke, C.; Woodfork, K. (Ed.) Luminescence biotechnology: instruments and applications. CRC Press LLC, Boca Raton, 345-364

Publ.-Id: 5158 - Permalink


Local velocity measurements in lead-bismuth and sodium flows using the Ultrasound Doppler Velocimetry
Eckert, S.; Gerbeth, G.;
Design and optimisation of the thermal hydraulics of liquid metal reactor systems is strongly based on numerical simulations of the related fluid flow and heat & mass transfer processes. Whereas these numerical simulations are essentially based on local flow phenomena (small-scale vortices, turbulence or sub-grid scale modeling), experimental results are often limited to integral flow rates or local related data like temperature or pressure. Local velocity measurements would be highly desirable but are mostly lacking due to the very limited possibilities for velocity measurements in liquid metals.

During the last decades the Ultrasound Doppler Velocimetry (UDV) became a very powerful tool to measure the velocity structure of liquid flows. Because of the ability to work in opaque fluids and to deliver complete velocity profiles in real time it becomes very attractive for liquid metal applications. In addition, it can principally operate through the channel wall though a direct contact to the melt reduces ultrasonic losses. However, in case of hot metallic melts the user is confronted with a number of specific problems: First of all, the application of the ultrasonic transducers is usually restricted to maximum temperatures of 150°C. The transmission of a sufficient amount of ultrasonic energy from the transducer to the fluid has to be guaranteed. Here, the acoustic coupling and the wetting conditions have to be considered as important issues. Moreover, the flow has to be seeded with reflecting particles to obtain Doppler signals from the fluid.

The feasibility of velocity profile measurements by UDV has already been demonstrated for low temperature liquid metals like mercury [1] and gallium [2]. We report on first successful measurements in liquid sodium at 150°C [3]. We will present mean profiles of a flow in a rectangular duct exposed to an external, transverse magnetic field. To demonstrate the capability of UDV the transformation of the well-known turbulent, piston-like profile to an M-shaped velocity profile for growing magnetic field strength was observed. The significance of artefacts such as caused by the existence of reflecting interfaces in the measuring domain will be discussed. In the sodium case, the measurements were performed through the channel wall.

An integrated ultrasonic sensor with acoustic wave-guide has been developed to overcome the limitation of ultrasonic transducers to temperatures lower than 200°C. This sensor can presently be applied at maximum temperatures up to 800°C. Stable and robust measurements have been performed in various PbBi flows in our laboratory at FZR as well as at the THESYS loop of the KALLA laboratory of the Forschungszentrum Karlsruhe (FZK). We will present experimental results obtained in a PbBi bubbly flow at 250...300°C. Argon bubbles were injected through a single orifice in a cylindrical container filled with stagnant PbBi. Velocity profiles were measured in the bubble plume. Mean values of the liquid as well as the bubble velocity were extracted from the data and will be presented as function of the gas flow rate. At the THESYS loop of FZK stable velocity profils have been measured in a round tube of diameter 60mm during a period of about 72 hours at temperatures between 180°C and 350°C. Velocity profiles have been obtained at different temperatures for variations of the liquid flow rate. In the PbBi case, the acoustic wave-guide was always in direct contact to the melt. In addition, some results of UDV velocity measurements with a wave-guide in a CuSn alloy of about 620°C and in an Al melt of about 750°C will be presented.

  • Contribution to external collection
    NURETH-10 in Seoul (Korea), 05.-09.10.2003, Paper K00201

Publ.-Id: 5157 - Permalink


Vererbung des Metabolischen Syndroms
Julius, U.; Schwanebeck, U.; Böhmer, G.; Metzler, W.; Fücker, J.; Pietzsch, J.;
  • Poster
    37. Jahrestagung der Deutschen Diabetes-Gesellschaft, Dresden, 09.-11.05.2002
  • Abstract in refereed journal
    Diabetes und Stoffwechsel 11 (2002) S130

Publ.-Id: 5156 - Permalink


Intravasaler Lipidtransfer bei gestörter Glukosetoleranz (IGT)
Kirschner, E.; Pietzsch, J.; Julius, U.;
  • Poster
    37. Jahrestagung der Deutschen Diabetes-Gesellschaft, Dresden, 08.-11.05.2002
  • Abstract in refereed journal
    Diabetes und Stoffwechsel 11 (2002) S92

Publ.-Id: 5155 - Permalink


Hyperon--Nucleon Bound States and Electroproduction of Strangeness on 3,4He
Dohrmann, F.; Abbott, D.; Ahmidouch, A.; Ambrozewicz, P.; Armstrong, C. S.; Arrington, J.; Asaturyan, R.; Assamagan, K.; Avery, S.; Bailey, K.; Baker, O. K.; Beedoe, S.; Bitao, H.; Breuer, H.; Brown, D. S.; Carlini, R.; Cha, J.; Chant, N.; Christy, E.; Cochran, A.; Cole, L.; Collins, G.; Cothran, C.; Crowder, J.; Cummings, W. J.; Danagoulian, S.; Duncan, F.; Dunne, J.; Dutta, D.; Eden, T.; Elaasar, M.; Ent, R.; Ewell, L.; Fenker, H.; Fortune, H. T.; Fujii, Y.; Gan, L.; Gao, H.; Garrow, K.; Geesaman, D. F.; Gueye, P.; Gustafsson, K.; Hafidi, K.; Hansen, J. O.; Hinton, W.; Jackson, H. E.; Juengst, H.; Keppel, C.; Klein, A.; Koltenuk, D.; Liang, Y.; Liu, J. H.; Lung, A.; Mack, D.; Madey, R.; Markowitz, P.; Martoff, C. J.; Meekins, D.; Mitchell, J.; Miyoshi, T.; Mkrtchyan, H.; Mohring, R.; Mtingwa, S. K.; Mueller, B.; O'Neill, T. J.; Niculescu, G.; Niculescu, I.; Potterveld, D. H.; Price, J. W.; Raue, B. A.; Reimer, P. E.; Reinhold, J.; Roche, J.; Roos, P.; Sarsour, M.; Sato, Y.; Savage, G.; Sawafta, R.; Segel, R. E.; Semenov, A. Y.; Stepanyan, S.; Tadevosian, V.; Tajima, S.; Tang, L.; Terburg, B.; Uzzle, A.; Wood, S.; Yamaguchi, H.; Yan-1, C.; Yan-2, C.; Yuan, L.; Zeier, M.; Zeidman, B.; Zihlmann, B.;
The A(e,e'K+)YX reaction has been investigated in Hall C at Jefferson Lab. Data were taken for Q2 approx 0.35 and 0.5 GeV2 at a beam energy of 3.245 GeV for 3He,4He. The missing mass spectra are fitted with Monte Carlo simulations including Lambda, Sigma0, Sigma- hyperon production. Models for quasifree production are compared to the data, excess yields close to threshold are attributed to FSI. Evidence for Lambda-hypernuclear bound states is seen for 3,4He targets.
  • Lecture (Conference)
    Progress in Particle and Nuclear Physics 50(2003) 587-589, "Proceedings of the International School on Nuclear Physics, 24th Course, Erice, Sicily September 2002
  • Contribution to external collection
    Progress in Particle and Nuclear Physics 50(2003) 587-589, "Proceedings of the International School on Nuclear Physics, 24th Course, Erice, Sicily September 2002

Publ.-Id: 5154 - Permalink


Die Homozygotie der Pro12Ala-Variante des Peroxisomenproliferator-Aktivierten Rezeptors Gamma-2 (PPAR-Gamma -2) ist mit erhöhten Proinsulinwerten und einer gesteigerten Insulinresistenz assoziert: Daten der FAMES-Studie
Fischer, S.; Pihlajamäki, J.; Fuecker, K.; Hanefeld, M.; Laakso, M.; Julius, U.; Pietzsch, J.;
  • Poster
    37. Jahrestagung der Deutsche Diabetes Gesellschaft, Dresden, 08.-11.05.2002
  • Abstract in refereed journal
    Diabetes und Stoffwechsel 11 (2002) S28

Publ.-Id: 5153 - Permalink


Investigation of Marangoni convection in monotectic melts by resistance measurements
Neumann, H.; Plevachuk, Y.; Allenstein, F.;
Electrical resistance of monotectic melts strongly depends on the state of phase separation. The gravity driven sedimentation leads to an arrangement of the lighter phase above the heavier one,. Because resistance of both phases are different, the state of demixing can be determined by the overall melt resistance using the four-probe-method. Resistance of hypermonotectic Zn-Pb liquid alloys has been measured in a wide temperature range between 820°C and a monotectic line and its dependence on different parameters has been discussed. The results are compared with theoretical predictions. It was shown that the electrical resistance of the demixed melt changed if transport processes (Marangoni convection) took place under microgravity conitions. The measuring arrangement used in the microgravity experiment on Zn-Pb melts during the flight of TEXUS 39 is presented.
Keywords: monotectic alloys, electrical conductivity, Manangoni convection, phase separation, microgravity
  • Materials Science & Engineering A361 (2003) 155-164

Publ.-Id: 5152 - Permalink


Motion of a Nd-Fe-B melt in levitated or float-zone operated samples and its control
Gerbeth, G.; Priede, J.; Shatrov, V.; Hermann, R.; Filip, O.;
The microstructure of Nd-Fe-B alloys changes if the convection in the melt varies. A controlled influence on the melt flow is possible via magnetic fields or sample rotations. The experimental techniques behind are the electromagnetic levitation, mechanical sample rotations and a specially designed float-zone arrangement. We present theoretical/numerical results for the melt convection in those configurations. The melt flow in a levitated droplet is studied under the additional effect of a global sample rotation which may lead to a strong suppression of internal motions. A specially designed two-phase stirrer offers a strong influence on the melt flow in the float-zone facility.
  • Lecture (Conference)
    DPG-Tagung Dresden, 24.-28.03.2003, Symposium "Phasenumwandlungen in Schmelzen"

Publ.-Id: 5151 - Permalink


Microstructure of Nd-Fe-B alloys influenced by the melt hydrodynamics
Hermann, R.; Filip, O.; Gerbeth, G.; Priede, J.;
The solidification process and the resulting microstructure of Nd-Fe-B alloys in consideration of melt convection has been investigated using the electromagnetic levitation technique, forced rotation experiments and the application of alternating magnetic fields. The electromagnetic levitation technique, which allows the in-situ measurement of the solidification kinetics containerlessly, has been used in order to investigate the influence of the internal melt motion on the microstructure formation of Nd-Fe-B alloys, mainly with respect to the volume fraction and grain size of the a-Fe phase. Moreover, experiments where specially sealed samples were subjected to a well-defined forced rotation have been carried out. The determination of the a-Fe volume fraction by measuring the magnetic moment in a vibrating sample magnetometer (VSM) resulted in a distinct reduction of the a-Fe volume fraction in samples with strong rotation. The influence of the cooling rate and the undercooling level on the microstructure formation and phase distribution has been investigated as well. Furthermore, a new category of experiment has been started where a tailored magnetic field was applied in order to study the microstructure evolution due to an enhancement or suppression of the melt convection by additional alternating magnetic fields.
  • Lecture (Conference)
    DPG-Tagung Dresden, 24.-28.03.2003, Symposium "Phasenumwandlungen in Schmelzen"

Publ.-Id: 5150 - Permalink


Experimental and theoretical investigations of flashing induced instabilities at the CIRCUS test facility
Manera, A.; Schäfer, F.;
The CIRCUS test facility (CIRCUlation during Startup) has been built to study the start-up phase of a natural-circulation BWR. During the start-up so called flashing-induced instabilities can arise. This paper gives an overview about experimental results and the physics of the instabilities. The thermo-hydraulic code ATHLET is used to investigate the dynamic bevavior of the test facility.
  • Lecture (Conference)
    Annual Meeting on Nuclear Technology, May 20-22, 2003, Berlin, Germany, Proceedings, P. 89-92
  • Contribution to proceedings
    Annual Meeting on Nuclear Technology, May 20-22, 2003, Berlin, Germany, Proceedings, P. 89-92

Publ.-Id: 5149 - Permalink


Fundamental properties of erbium-ions-producing liquid metal alloy ion sources
Bischoff, L.; Mair, G.; Aidinis, C. J.; Ganetsos, T.;
We describe the electric characteristics and mass spectra of two liquid metal alloy ion sources;namely Er70Fe22Cr3Ni5 and Er69Ni31.Erbium ions are of great interest for optoelectronic applications.For the first time in the literature the energy spread of triply charged ions (Er 3+ ) is reported.

Keywords: Erbium, Liquid Metal Alloy Ion Source, Energy spread, Mass Spectra
  • Nuclear Instruments and Methods in Physics Research B 197 (2002) 282-287

Downloads:

Publ.-Id: 5148 - Permalink


Metalloradiopharmaceuticals in Nuclear Medicine
Spies, H.;
Radiopharmaceuticals are drugs containing a radionuclide and are used routinely in nuclear medicine for the diagnosis or therapy of various diseases. They are mostly small organic or inorganic compounds, but can also be macromolecules such as monoclonal antibodies or their fragments labeled with a radionuclide. Those agents whose biodistribution is determined by biological interaction, e. g. receptor binding, are termed target-specific radiopharmaceuticals.

For diagnostic imaging agents, technetium-99m is frequently the radionuclide of choice because it has optimal nuclide properties (half-life of 6h and appropriate Gamma-energy of 140 keV). The inconvenience of purchasing a short-lived radionuclide was overcome by the development of the 99Mo/99mTc generator, which is based on transient equilibrium between the parent radionuclide 99Mo (66h half-life) and the daughter radionuclide 99mTc (6h half-life). The generator makes this radionuclide both routinely available and economical. Finally, the 99mTc-radiopharmaceutical can easily be prepared in the clinic by means of prefabricated kits. So it is no surprise that more than 90% of routine in vivo imaging is performed with technetium-99m [1,2].

Table 1. Metal nuclides for diagnostic or therapeutic application

Beside technetium, many other radiometals have been or are being investigated for their uses in nuclear medicine [3]. This comprises not only radiometal-labeled agents used in gamma scintigraphy and positron emission tomography (PET), but also beta and alpha emitters for radionuclide therapy [4] (Table 1).
The development of effective metalloradiopharmaceuticals is a complex task which is not simply accomplished by attaching a radionuclide to a nonradiolabeled targeting vector (Fig.1).

Fig.1. Schematic representation of the bifunctional approach as a strategy of radiopharmaceutical design

Because of the unphysiological nature of the radiometal, the structure of the biomolecule where the chelate is appended, will be altered and the biodistribution will change drastically. The search for metalloradiopharmaceuticals involves therefore chelate systems that stable bind the radiometal, and, since it will be directly involved in optimizing the biochemical properties of the radiopharmaceutical, it has to be compatible in structure and physicochemical properties. In recent years, new chelate systems have been developed (Fig.2) for binding technetium (as well its congener rhenium) at oxidation states V, III, and I involving metallnitrido cores (1) [5], mixed-ligand complexes (2) [6] and metal-tricarbonyl derived complexes (3) [7,8].
  • Invited lecture (Conferences)
    10th Conference International Isotope Society, European Division, Bad Soden, 06.-07.06.2002

Publ.-Id: 5147 - Permalink


New '3+1' Tc(V) oxocomplexes containing a tridentate H2PNS ligand and different monodentate ligands for the 5HT1A receptor
Fernandes, C.; Correia, J. D. G.; Santos, I.; Spies, H.; Seifert, S.;
The stability of the complexes of '3+1' type depends not only on the nature of the tridentate ligand but also on the nature of monodentate co-ligand.[1,2] The recently introduced (tri)bidentate heterofunctionalized phosphines, (H2PNX; X=O,S), which are quite versatile in terms of charge and denticity towards the [M=O]3+ core, form '3+1' mixed-ligand complexes with different thiolated monodentate co-ligands.[3,4] These complexes show different in vitro stabilities, confirming the importance of the nature of the donor atoms on the stability. Using the H2PNS ligand and a thiolated arylpiperazine derivative we succeeded on the preparation of the stable '3+1' oxocomplex [M(O)(eta3- PNS)(SCH2CH2NHCH2CH2CH2(2-MeOPhpip))] (M = Re, 99mTc). In spite of its high stability, the complex showed low affinity for the 5HT1A receptor (120 nM ± ).[5]
These results prompted us to introduce some chemical modifications in the monodentate co-ligand, in order to increase the affinity and selectivity to the receptor. So, herein we report on the synthesis and characterization of the new thiolated arylpiperazine derivatives and on the preparation of the corresponding '3+1' oxocomplexes at the macroscopic and at the n.c.a. level (80-95% yield). The 99mTc-complexes obtained were identified by comparing their radioactive HPLC profiles with those of the analogous Re complexes. After purification by semi-preparative HPLC, the radiochemical purity of the complexes is higher than 95%.
The stability of the purified 99mTc-complexes was studied in saline, 0.01M PBS (pH 7.4) at 37ºC, and all of the complexes revealed stable. No significant exchange with glutathione (1mM and 10mM solutions, 37ºC) was observed.
In order to determine the effect of the chemical modifications introduced in the monodentate ligand, binding affinities and specificities for the 5HT1A receptor have still to be evaluated.

Acknowledgements: This work is being supported by the COST Action B12.

References
[1] Syhre, R.; Seifert, S.; Spies, H.; Gupta, A.; Johannsen, B.; Eur. J. Nucl. Med. 1998, 25:793.
[2] Seifert S. et al Radioch. Acta, in press.
[3] Correia, J. D. G.; Domingos, A.; Santos, I.; Eur. J. Inorg. Chem. 2000, 7:1523.
[4] Correia, J. D. G.; Domingos, A.; Paulo, A.; Santos, I.; J. Chem. Soc. , Dalton Trans. 2000, 14: 2477.
[5] Fernandes, C.; Correia, J. D. G.; Gano, L.; Santos, I.; Seifert, S.; Syhre, R.; Spies, H.; J. Labelled Cpd. Radiopharm. 2001, 44, Suppl. 1, S518.
  • Poster
    Conference on Advances and Perspectives in Radiotracer Development, Rossendorf, 07.-08.03.2002

Publ.-Id: 5146 - Permalink


A new approach for a 11C-C bond formation: Synthesis of 17alpha-(3'-[11C]Prop-1-ynyl)-3-methoxy-3,17beta-estradiol
Wüst, F.; Zessin, J.;
Introduction
To expand the scope of 11C-labelled compounds, novel 11C-C bond forming reactions gain more and more attention [1]. The versatile availability of [11C]methyl iodide makes this labelling precursor favourable in several transition-metal mediated cross-coupling reactions. In this contex, technically simple, high-yielding and functional group tolerating reactions are of particular interest. The Sonogashira copper-palladium catalysed coupling of terminal alkynes with aromatic and vinylic halides [2] represents such a reaction. To the best of our knowledge, the Sonogashira-reaction has not yet been employed in 11C-chemistry. Herein, we describe a modified Sonogashira-like reaction [3] for labelling the terminal alkyne group of the potent contraceptive steroid mestranol 1 with [11C]methyl iodide.

Results and Discussion
The classical conditions of the Sonogashira reaction (Pd0, CuI and TEA or DIPA as thebase) can not be employed for 11C-labelling with [11C]methyl iodide due to the rapid quaternization the amine base. Therefore, we tested alternative catalyst/base combinations. By using tetrakis(triphenylphosphine)-palladium(0) (TTPP), copper(I) iodide, and 1,8-bis(dimethylamino)naphthalene as a non-nucleophilic base, about 5% of [11C]methyl iodide was converted into [11C]2. Similar results were obtained using the catalyst TTPP and silver oxide as the base. However, in the reaction of 1 with tris-(dibenzylidineacetone)-dipalladium(0), triphenylarsine, and tetrabutylammonium fluoride, 42-53% of [11C]MeI was converted into [11C]2

Scheme 1: 11C-labelling of steroid 1

Conclusion
We developed a new method for a 11C-C bond formation employing the cross-coupling of terminal alkynes with [11C]methyl iodide via a Sonogashira-like reaction in sufficient radiochemical yields.

References
[1] B. Långström et al. Acta Chem. Scand. 53 (1999) 651-669.
[2] K. Sonogashira et al. Tetrahedron Lett. (1974) 4467-4470.
  • Poster
    Conference on Advances and Perspectives in Radiotracer Development, Rossendorf, 07.-08.03.2002

Publ.-Id: 5145 - Permalink


Cytosine deaminase as an enzyme for monitoring suicide gene therapy
Grote, M.; Gupta, A.; Noll, S.; Knieß, T.; Noll, B.; Johannsen, B.; Schackert, H. K.;
Introduction
Besides the herpes simplex virus type-1 thymidine kinase (HSV-1 TK), cytosine deaminase (CD) presents another system for gene therapy. CD catalyses the hydrolytic deamination of cytosine to form uracil. Its lack in mammalian cells and the ability to convert 5-fluorocytosine to the cell-toxic 5-fluorouracil makes it suitable for use in several gene therapy protocols [1,2]. An appropriate radiolabelled cytosine derivative would make it possible to monitor gene expression with positron emission tomography (PET), providing a sufficient amount of the tracer is trapped in the tumor cells. For this purpose, several cytosine derivatives were tested.

Results
CD was obtained by over-expression and following purification from transformed E. coli bacteria in good yields. The specific activity and KM were determined using cytosine and 5-fluorocytosine. Some compounds (listed in table 1) were incubated in tris-buffer solution containing the isolated enzyme. Samples were taken and the rate of metabolites formation determined by HPLC.

For cytosine, the specific activity of 38 U/mg enzyme (one unit is the amount of enzyme catalysing the deamination of 1 µmol substrate per minute at 25°C) and a KM of 0.63 mM falls in the range of further data published [3,4]. For 5-fluorocytosine, the decrease in specific activity (2.1 U/mg protein) and the increase of KM (5.2 mM) of one dimension is also in good agreement with published data [1]. Additionally, it was shown that the CD tolerates some structural variations of its possible substrates. Beside substances which are varied at the 5-position (5-fluorocytosine, 5-methylcytosine), N-substituted derivatives like N-methylcytosine and N-hydroxycytosine are also accepted. This results offer a number of fluorine-18 labelled compounds as candidates for monitoring gene therapy.

Table 1
-----------------------------------------------------------------------
Turnover to the corresponding product in % after
Compound............10 min.....30 min.....60 min
-----------------------------------------------------------------------
Cytosine...............88.84......100..........100
5-Fluorocytosine......9.39.......22.42........28.61
5-Methylcytosine.....1.07.........5.94........10.25
N-Methylcytosine....1.47..........5.22.........8.53
N-Hydroxycytosine.20.11.......31.23........42.88

References
[1] Rowley, S. et al. J. Surgical Oncology 1996, 61, 42-48.
[2] Haberkorn, U. et. al. J. Nucl. Med. 1996, 37, 87-94.
[3] Ipata, P. L. Methods Enzymol. 1978, 51, 394-401.
[4] Balestreri, E. et al. Biochim Biophys Acta 1973, 315, 443-448.
  • Poster
    Conference on Advances and Perspectives in Radiotracer Development, Rossendorf, 07.-08.03.2002

Publ.-Id: 5144 - Permalink


Competitive reactions observed during the synthesis of 18F-labelled compounds intended for monitoring gene therapy
Grote, M.; Noll, S.; Noll, B.; Johannsen, B.;
Introduction
For monitoring gene expression of the herpes simplex virus type-1 thymidine kinase (HSV-1 tk), several reporter probes such as acycloguanosine analogues labelled with fluorine-18 have been described [1]. Studying several methods for radiolabelling eligible precursors with the isotope fluorine-18, we noticed highly varying yields, depending on the precursor used. This is due to the occurrence of competitive reactions that reduce the labelling yields of the tracers.

Results
Conversion of the precursors 5 and 6 into [18F]FHPG 1 and [18F]FHBG 2, but also into the non-radioactive fluorine compounds, resulted in a much lower yield compared to the methylated derivatives 7 and 8.

The nucleophilic fluorination with Kryptofix K2.2.2 to prepare the labelled compounds 1-4 was performed according to [2,3]. The unreacted 18F was removed by purification with a silica gel cartridge eluted with CH2Cl2/MeOH 85:15. In splitting off the methoxytrityl protection groups by of aqueous HCl, the precursors behave different. With the acycloguanosines derivatives 1 and 3 bearing an oxygen in their side-chain a by-product was delivered. The carba-analogues 2 and 4 are stable under these conditions.

Non-radioactive fluorination of compounds 5 and 6 delivers a N1/O (from -OTs) bridged structure (characterized by 1H NMR, IR, MS and elemental analysis) as by-product in a yield of 20%. This concurrent reaction was also observed in the 18F-labelling experiments. Since the methyl group in the N1-position inhibits the cyclisation, 7 and 8 do not form such a by-product.
The splitting off the methoxytrityl protection groups by aqueous HCl is accompanied by decomposition. The two-phase system water-dichloromethane did not allow a satisfying control of the reaction temperature and in consequence, the acyclic side-chain of 1 and 3 was splitted off to result a by-product. These problems were overcome by using methanolic HCl as splitting agent. Its miscibility with CH2Cl2 allows a better reaction control, resulting in shorter reaction times and reducing the by-products.

References
[1] Wiebe, L. I. et al. Q. J. Nucl. Med. 1997, 41, 79-89.
[2] Alauddin, M. M. et al. Nucl. Med. Biol. 1998, 25, 175-180.
[3] Alauddin, M. M. et al. Nucl. Med. Biol. 1999, 26, 371-376.
[4] Shiue, G. G. et al. Nucl. Med. Biol. 2001, 28, 875-883.
  • Poster
    Conference on Advances and Perspectives in Radiotracer Development, Rossendorf, 07.-08.03.2002

Publ.-Id: 5143 - Permalink


Speciation of Uranium in Biologial Systems
Bernhard, G.;
keinen Abtract
  • Lecture (Conference)
    Center of Inovation and Excellence, Tokyo 27.08.2002

Publ.-Id: 5142 - Permalink


Zur Umweltchemie des Urans
Bernhard, G.;
keinen Abtract
  • Lecture (others)
    Forschungszentrum Karlsruhe, INE, 04.11.2002

Publ.-Id: 5141 - Permalink


Wohin mit dem Atommüll?
Bernhard, G.;
keinen Abtract
  • Lecture (others)
    Forschungszentrum Rossendorf 14.09.2002

Publ.-Id: 5140 - Permalink


Uranium speciation in plants
Bernhard, G.;
keinen Abtract
  • Lecture (Conference)
    Konferenz University of Tokyo, 27.08.2002

Publ.-Id: 5139 - Permalink


Development and Verification of a Reactor Dynamics Code for Molten Salt Reactors with Flowing Fuel
Krepel, J.; Grundmann, U.; Rohde, U.;
The development of DYN3D-MSR code is described in the paper. This code is based on a three-dimensional code DYN3D for calculation of steady states and transients in light water reactors LWR, which was developed in FZR. The MSR modification of DYN3D code is designed to calculate steady states and transients of Molten Salt Reactors. The fuel of this reactor should be liquid in a form of molten salt mixture and should act also as a coolant. The thermal-hydraulic and neutron kinetic characteristic will differ from classical LWR. For the code development a MSR design with fuel floating in channels inside hexagonal graphite structure is considered. The first step of development is a 1D version, which is based on a numerical method for hexagonal fuel element geometry from original code and which includes new models describing fuel flow. DYN1D-MSR as the first step of 3D version development is already an effective tool for transient analysis of MSR. The first results for fuel flow slowdown have shown the ability to provide space dynamics calculations.
Keywords: Code development, reactor dynamics, molten salts, neutronic calculation, delayed neutrons
  • Lecture (Conference)
    Annual Meeting on Nuclear Technology 2003, Berlin, 15. - 17. May 2003
  • Contribution to proceedings
    Annual Meeting on Nuclear Technology 2003, Berlin, 15. - 17. May 2003

Publ.-Id: 5138 - Permalink


Fundamentals of quantitative PET data analysis
Willemsen, A. T. M.; van den Hoff, J.;
Drug analysis and development with PET should fully exhaust the ability of this tomographic technique to quantify regional tracer concentrations in vivo. Data evaluation based on visual assessment of regional image contrast is not sufficient for this purpose since much of the information present in dynamically acquired data is not used by these approaches. Compartment modelling of dynamic PET data is generally the method of choice since it allows a quantitative assessment of the underlying pharmacokinetic parameters describing drug transport, metabolism and molecular interactions. We present here an overview of key issues of compartment modelling with specific attention to the assumptions underlying the various models and their limitations. We believe that a thorough understanding of the applicability of models is mandatory for the development, successful execution and analysis of quantitative PET studies. Otherwise, meaningful and interpretable results will often not be obtained.
  • Curr Pharm Des 8 (16) (2002) 1513-1526

Publ.-Id: 5137 - Permalink


Impaired glucose phosphorylation and transport in skeletal muscle cause insulin resistance in HIV-1-infected patients with lipodystrophy
Behrens, G. M. N.; Boerner, A.-R.; Weber, K.; van den Hoff, J.; Ockenga, J.; Brabant, G.; Schmidt, R. E.;
Insulin resistance is a frequently observed side effect of highly active antiretroviral therapy (HAART). Currently, very little is known about the mechanisms or specific tissues involved. We aimed to identify possible defects in skeletal muscle glucose uptake andhietabolism in HIV patients receiving HAART. Whole-body glucose disposal and oxidation were determined by combination of the euglycemic-hyperinsulinemic clamp technique and indirect calorimetry. Muscle glucose uptake of the thighs was measured simultaneously by dynamic 2[18F]fluoro-2-deoxy-D-glucose positron emission tomography. Patients receiving HAART had signs of lipodystrophy as confirmed by dual energy x-ray absorptiometry. Whole-body glucose disposal was significantly reduced in these patients compared with untreated patients. Analysis of kinetic constants using a three-compartment model indicated reduced skeletal glucose uptake caused by significantly impaired glucose transport and phosphorylation. Skeletal muscle glucose uptake was reduced by 66% in treated patients and explained 46% and 43% of whole-body glucose disposal in patients on HAART and therapy-naive patients, respectively. Insulin-stimulated whole-body oxidative and nonoxidative glucose disposal was significantly lower in the treated group, as was suppressive insulin action on lipolysis. To our knowledge, this is the first report providing in vivo evidence that, in lipodystrophic HIV patients, impaired glu-
cose transport and phosphorylation cause redu ' ced insulin-mediated glucose uptake.
  • The Journal of Clinical Investigation 110 (2002) 1319-1327

Publ.-Id: 5136 - Permalink


Discrimination between Alzheimer dementia and controls by automated analysis of multicenter FDG PET
Herholz, K.; Salmon, E.; Perani, D.; Baron, J.-C.; Holthoff, V.; Frölich, L.; Schönknecht, P.; Ito, K.; Mielke, R.; Kalbe, E.; Zündorf, G.; Delbeuck, X.; Pelati, O.; Anchisi, D.; Fazio, F.; Kerrouche, N.; Desgranges, B.; Eustache, F.; Beuthien-Baumann, B.; Menzel, C.; Schröder, J.; Kato, T.; Arahata, Y.; Henze, M.; Heiss, W.-D.;
A new diagnostic indicator of FDG PET scan abnormality, based on age-adjusted t statistics and an automated voxel-based procedure, is presented and validated in a large data set comprising 110 normal controls and 395 patients with probable Alzheimer's disease (AD) that were studied in eight participating centers. The effect of differences in spatial resolution of PET scanners was minimized effectively by filtering and masking. In controls FDG uptake declined significantly with age in anterior cingulate and frontolateral perisylvian cortex. In patients with probable AD decline of FDG uptake in posterior cingulate, temporoparietal, and prefrontal association cortex was related to dementia severity. These effects were clearly distinct from age effects in controls, suggesting that the disease process of AD is not related to normal aging. Women with probable AD had significantly more frontal metabolic impairment than men. The new indicator of metabolic abnormality in AD-related regions provided 93% sensitivity and specificity for distinction of mild to moderate probable AD from normals, and 84% sensitivity at 93% specificity for detection of very mild probable AD (defined by Mini Mental Score 24 or better). All regions related to AD severity were already affected in very mild AD, suggesting that all vulnerable areas are affected to a similar degree already at disease onset. Ventromedial frontal cortex was also abnormal. In conclusion, automated analysis of multicenter FDG PET is feasible, provides insights into AD pathophysiology, and can be used potentially as a sensitive biomarker for early AD diagnosis.
  • NeuroImage 17 (2002) 302-316

Publ.-Id: 5135 - Permalink


Investigations on redox-active pyridinium-salt/dihydropyridine bearing Tc- and Re-complexes
Rother, A.; Knieß, T.; Bergmann, R.; Kraus, W.; Jungclas, H.; Spies, H.;
Potentially redox-active NAD+/NADH-analogous pyridinium- and quinolinium-salt bearing Re- and 99mTc-mixed-ligand complexes were synthesized. The complexes vary in the chelate type, the oxidation state of the metal, the spacer length to the chelate and the substituent at the pyridine/quinoline nitrogen. The complexes were reduced to dihydropyridines and dihydroquinolines respectively and investigations concerning their stability against reoxidation were performed. In competition experiments with NADH the quinoliniuni-salt/dihydroquinoline bearing complexes display enzymatic inhibition of the lactate dehydrogenase.
Keywords: redox delivery system, pyridinium-salt, 1,4-dihydropyridine, NAD+/NADH, Re- and Tc-mixed-ligand-complexes
  • Lecture (Conference)
    6th International Symposium on Technetium in Chemistry and Nuclear Medicine, Bressanone/I, 04.-07.09.2002
  • Contribution to external collection
    In: Technetium, Rhenium and Other Metals in Chemistry and Nuclear Medicine (Edited by Nicolini M., Mazzi U.) SGEditoriali Padova 2002, 73-78

Publ.-Id: 5134 - Permalink


FDG-PET in the pretherapeutic evaluation of primary squamous cell carcinoma of the oral cavity and the involvement of cervical lymph nodes
Hlawitschka, M.; Neise, E.; Bredow, J.; Beuthien-Baumann, B.; Haroske, G.; Eckelt, U.; Franke, W.-G.;

Purpose:
The diagnostic role of positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) in squamous cell carcinoma of the oral cavity is evaluated.

Procedures:
In 38 patients, the results of FDG-PET, magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound were compared. The standard uptake values (SUV) of FDG-PET were correlated to histopathological grading and DNA-image cytometry.

Results:
In the case of lymph node metastases, the sensitivity of FDG-PET (93%) was higher than the sensitivity for the compared methods. The specificity was best for CT. SUVs of diploid tumor cell lines seemed to be lower than in non-diploid tumor cell lines.

Conclusions:
The high sensitivity and the high negative predictive value of PET may lead to more restrictive therapeutic regimens regarding lymph. node metastases. Studies are necessary regarding possible relationships between glucose metabolism and tumor grading.
Keywords: FDG-PET; MRI; CT; Ultrasound; Squainous Cell Carcinoma; Oral Cavity; Lymph Node Metastasis; Grading; DNA-image Cytometry.
  • Molecular Imaging and Biology Vol. 4, No. 1 (2002) 91-98

Publ.-Id: 5132 - Permalink


Diagnostic value of 18F-FDG positron emission tomography for detection and treatment control of malignant germ cell tumors
Tsatalpas, P.; Beuthien-Baumann, B.; Kropp, J.; Manseck, A.; Tiepolt, C.; Hakenberg, O. W.; Burchert, W.; Franke, W. G.; Wirth, M. P.;
Introduction:
The role of positron emission tomography (PET) with 2-[18F]fiuoro-2-deoxy-D-glucose ([18F]FDG) is currently under evaluation in urologic oncology. The aim of the present study was to investigate the use of [18F]FDG positron emission tomography ([18F]FDG-PET) in the detection and treatment control of malignant germ cell tumors compared to computed tomography (CT).
Materials and Methods:
Thirty-two PET studies and CT scans were carried out in 23 patients with histologically proven germ cell tumors (10 seminomas, 12 non-seminomatous germ cell tumors (NSGCT), 1 unclassified serologic recurrent disease) Lugano stage I-III. The scans were done either after initial diagnosis (n = 21) and/or within 3-45 days after chemotherapy was completed (n = 11). PET and CT were validated either by histology (n = 7) or clinical follow-up of 6-11 months after the last PET study has been performed (n = 16). Sensitivity, specificity, accuracy, positive and negative predictive values were determined for PET and CT. Differences between PET and CT for parameters of diagnostic value were evaluated by chi2 test.
Results:
Although not statistically significant, the sensitivity, accuracy and negative predictive value were higher for PET than for CT with respect to the detection of metastatic infradiaphragmatic and supradiaphragmatic lesions after initial diagnosis. The specificity and positive predictive value of PET and CT were comparable. After chemotherapy, PET was found to be significantly superior in specificity and accuracy compared to CT with respect to infradiaphragmatic lesions (p < 0.05). False-positive PET findings in supradiaphragmatic lesions after chemotherapy occurred in the case of inflammatory processes and resulted in a loss of specificity and accuracy compared to CT (p < 0.05).
Conclusions:
These preliminary results demonstrate [18F]FDG-PET to be a useful diagnostic tool for the initial staging and treatment control in patients with germ cell tumors. Possible advantages compared to CT, however, are as yet not clearly defined. The possibility of false-positive PET findings due to reactive supradiaphragmatic inflammatory processes early after chemotherapy have to be considered.


Keywords: 18F-FDG positron emission tomography; Computed tomography; Testis cancer; Treatment control
  • Urologia Internationalis 68 (2002) 157 - 163

Publ.-Id: 5131 - Permalink


Analysis of irradiation induced creep of bolts of a PWR core baffle
Altstadt, E.; Fischer, E.; Kumpf, H.; Nagel, G.; Sgarz, G.; Weiß, F.-P.;
The core baffle of a PWR is loaded by the pressure difference between bypass and core and by temperature profiles developing from gamma heating and heat transfer into the coolant. Strain, deformation and gaps between the sheets resulting from this load are determined considering the effect of neutron irradiation induced creep of the core baffle bolts. The finite element code ANSYS is applied for the thermal and mechanical analyses. The FE-model comprises a complete 45° sector of the core baffle structure including the core barrel, the formers, the core baffle sheets and about 230 bolt connections with non-linear contact between the single components and the effect of friction.
The analysis shows that some of the bolts loose a significant part of their pre-stress during operation, especially those bolts that are located in the neutron flux maximum. However, the load is taken over by other bolts located at lower flux positions. This global stress relocation is a self regulating process, which keeps the mechanical and geometrical stability of the core baffle structure till end of life.
Keywords: Pressure water reactor; irradiation induced creep; gamma heating; neutron flux; thermal analysis; finite element method
  • Lecture (Conference)
    Tagungsband der Jahrestagung Kerntechnik 2003, Berlin 20. -22. Mai 2003, S. 591-594
  • Contribution to proceedings
    Tagungsband der Jahrestagung Kerntechnik 2003, Berlin 20. -22. Mai 2003, S. 591-594

Publ.-Id: 5130 - Permalink


Impact of moisture from ambient on ion beam synthesis of nanocrystals in thin SiO2 layers
Schmidt, B.; Heinig, K.-H.; Grambole, D.; Herrmann, F.; Perego, M.;
The scaling-down of the gate oxide thickness in modern MOS memory devices below 20 nm requires low energy ion implantation for ion beam synthesis (IBS) of nanocrystals (NC) in SiO2. Lowering the ion energy, the implanted and damaged SiO2-layer will be located closer to the SiO2 surface and the interaction of this layer with the ambient becomes more and more dangerous. In the damaged near surface layer the high number of broken bonds due to displaced Si and O atoms forms in the glassy network pathes, which are open for diffusion and in which moisture from the ambient can be absorbed. Therefore chemical reactions of the implanted impurities with hydrogen and oxygen must be expected during subsequent annealing. Water 16, H2O18) absorption in Si-, Ge-, and Sn-implanted SiO2 layers has been studied by H-depth profiling using Nuclear Reaction Analysis (NRA) and by O18-depth profiling using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), respectively. H- and O-depth profiles were measured after storage under clean room conditions and after additional wet cleaning, as well as after annealing. The amounts of H and O incorporated into as-implanted SiO2 already during storage are comparable with the concentration of the implanted impurities and are sufficient to interfere significantly with the precipitation and Ostwald-ripening of NCs during IBS.
  • Lecture (Conference)
    International Workshop on Nanostructures for Electronics and Optics - NEOP - Dresden, Germany October 6 - 9, 2002
  • Contribution to proceedings
    International Workshop on Nanostructures for Electronics and Optics - NEOP - Dresden, Germany October 6 - 9, 2002

Publ.-Id: 5129 - Permalink


Self-organized NcC-layers by conventional ion implantation (status report for WP2)
Schmidt, B.; Heinig, K.-H.; Müller, T.; Stegemann, K.-H.;
The report includes results of hydrogen depth profiling using Nuclear Reaction Analysis (NRA) as well as 18O depth profiling using Time-of-Fligt Secondary Ion Mass Spectroscopy (ToF-SIMS) in as implanted SiO2-layers. The measured depth profiles of H and 18O, respectively, clearly show, that as-implanted SiO2-layers soak in humidity from the ambient, which significanly influences the processes of nanocluster growth in thin SiO2-layers during thermal processing of these layers.
  • Lecture (others)
    NEON Meeting, January 17-18, 2002, Athens, Greece

Publ.-Id: 5128 - Permalink


Erzeugung von Nanostrukturen durch Ionenbestrahlung
Schmidt, B.;
Es wird ein Überblich über die Möglichkeiten der Anwendung der Ionenstrahltechnik zur Erzeugung von Nanostrukturen durch Ionenimplantation und anschließender termischer Behandlung gegeben. Nanostrukturen, wie Nanocluster, Nanodrähte, Ketten von Nanoclustern usw. bilden sich dabei durch die Phasenseparation in übersättigten Festkörperlösungen und Selbstorganisation. Desweiteren werden die Selbstorganisation von 2D Anordnungen von Nanoclustern durch Ionenbestrahlung von Grenzflächen (z.B. SiO2/Si) sowie die Modifizierung von Nanostrukturen unter Ionenbestrahlung (Inverses Ostwald-Reifen) diskutiert.
Zum Schluß wird beispielhaft gezeigt, welche Möglichkeiten sich durch den Einsatz eines feinfokussierten Ga-Ionenstrahls zur Bestrahlung von Silizium ergeben, um 3D-Strukturelemente im nm-Bereich herzustellen.
  • Lecture (others)
    Frühjahrssitzung des Arbeitskreises Plasmaoberflächentechnologie, 13.-14. Mai 2002, Universität Kassel, Institut für Technische Physik (IMA)

Publ.-Id: 5127 - Permalink


Substrate orientation, doping and plasma frequency dependencies of structural defect formation in hydrogen plasma treated silicon
Ulyashin, A. G.; Job, R.; Fahrner, W. R.; Richard, O.; Bender, H.; Claeys, C.; Simoen, E.; Grambole, D.;
The formation of structural defects in hydrogen plasma treated (100)- and (111)-oriented p-type Czochralski (Cz) Si and in [100]-oriented n-type Si was studied by Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The samples were treated either by a 110 MHz or 13.56 MHz hydrogen plasma at 250 gradC for 60 min. The distribution of hydrogen was studied by nuclear reaction analysis. It is found that, after the hydrogen plasma treatment, the surface of Cz Si is structured and the roughness of the surface depends on the orientation and doping level of the substrate. The defect density increases for (100)-oriented wafers for the higher plasma frequency but for (111)-oriented wafers it is lower, applying the same hydrogen plasma frequency. Different defect types were found: stacking faults on { 111 } planes,dislocations and circular shaped defects exhibiting a strong stress field. The formation of nearly free hydrogen molecules (Raman shift of about 4150 cm -1 ) was observed by Raman spectroscopy after the plasma hydrogenation. It was found that the H2 molecule concentration depends on the concentration of structural defects. The hydrogen molecules can be formed in both n- and p-type Si, unlike the case of remote plasma hydrogenation.
  • J. Phys.: Condens. Matter 14 (2002) 13037-13045

Publ.-Id: 5126 - Permalink


Application of Master-Curve Approach in RPV Integrity Assessment
Viehrig, H.-W.;
The Master Curve (MC) concept allows to quantify the variation of fracture toughness with the temperature throughout the ductile-to-brittle transition region of ferritic steels. Limit curves of fracture toughness for defined failure probabilities and a refer-ence temperature, T0, can be determined using this method. MC Approach and the associated T0 as defined in the standard ASTM E1921, is rapidly moving to the appli-cation in the integrity assessment of nuclear reactor pressure vessels (RPV). T0 is a fracture mechanics defined ductile-to-brittle transition temperature which replaces reference temperatures based on a correlation of Charpy V-notch and NDT tests in the RPV integrity assessment.
The presentation gives an overview about the MC approach and the application to dif-ferent western and Russian WWER-type RPV steels. Further, the influence of the test conditions as test temperature and loading rate on the MC evaluation is assessed.
Keywords: fracture toughness, Master Curve, reactor pressure vessel, integrity assessment
  • Lecture (others)
    Arbeitskreis Nucleare Werkstoffe des Paul Scherrer Instituts, Villingen, 28. November 2002

Publ.-Id: 5125 - Permalink


Biomaterials-Body Interaction
Maitz, M. F.;
Four seminar talks without abstract
- Principles of biomaterials testing
- Biomaterials in bone
- Biomaterials in blood
- The complement system
Keywords: Biomaterial, hemocompatibility, bone, complement
  • Lecture (others)
    Southwest Jiaotong University, Chengdu, China. 14.10.-08.11.2002

Publ.-Id: 5124 - Permalink


Depth profiles of Argon incorporated into Boron Nitride films during preparation and their temperature dependent evolution
Deyneka, N.; Zhang, X. W.; Boyen, H.-G.; Ziemann, P.; Fukarek, W.; Kruse, O.; Möller, W.;
no abstract

Publ.-Id: 5123 - Permalink


Small Angle Neutron Scattering Measurements of the Ageing under Neutron Irradiation and Recovery of Reactor Pressure Vessel Steels and Iron Alloys
Ulbricht, A.; Böhmert, J.; Viehrig, H.-W.;
Irradiated heats representing WWER 440-type and 1000-type base and weld metal in their chemical composition, heats of the ASTM steels A533B Cl. 1 (JRQ), A508 Cl. 3 (JFL) and iron test alloys were investigated.
The radiation defects detected by SANS correlate with the radiation hardening and embrittlement. The ratio between nuclear and magnetic neutron scattering provides information on the type of radiation defects.
Keywords: embrittlement microstructure reactor pressure vessel steel small angle neutron scattering
  • Lecture (others)
    Tables Rondes du LABORATOIRE LÉON BRILLOUIN, Thème D: Systèmes désordonnés et Matériaux, CEA/Saclay, FRANCE, 28 Novembre 2002.

Publ.-Id: 5122 - Permalink


Arbeiten am Forschungszentrum Rossendorf zum sicherheitsorientierten Monitoring exothermer chemischer Reaktionen
Kryk, H.; Hessel, G.; Schmitt, W.;
Gegenstand der Forschungstätigkeiten der Arbeitsgruppe Verfahrenschemie bilden Untersuchungen zur Erhöhung der Anlagen- und Umweltsicherheit sowie der Effektivität chemischer Prozesse. Die Arbeiten erstrecken sich über ein weites Feld, angefangen bei der Reaktionsaufklärung und der Ermittlung von Stoffeigenschaften mittels Reaktionskalorimetrie, einschließlich der Nutzung chemischer Analytik, über numerische und experimentelle Prozesssimulation, experimentelle Arbeiten zur Modellierung reagierender Strömungen bis hin zur Erarbeitung von Prozessführungsstrategien und Methoden zum Monitoring chemischer Prozesse.
Gegenstand des Vortrags ist ein Überblick über die experimentelle Ausstattung der Arbeitsgruppe Verfahrenschemie und die Forschungstätigkeiten anhand zweier Beispiele.

Die Arbeitsgruppe verfügt über mehrere Reaktionskalorimeter (RC1, DSC, PhiTecII), die in Verbindung mit entsprechender Analysentechnik (Insitu-Spektrometer, HPLC) zur Reaktionsaufklärung und zur Ermittlung thermokinetischer Parameter chemischer Prozesse Verwendung finden.
Ein modular aufgebauter automatischer Laborreaktor (Miniplant) dient der experimentellen Simulation chemischer Prozesse, einschließlich scale-up-/ scale-down-Untersuchungen.
Darüber hinaus verfügt die Abteilung über eine schnelle Impuls-Röntgenanlage, die zukünftig verstärkt zur Visualisierung und, in Verbindung mit entsprechender Bildverarbeitungs-, Modellierungs- und Simulationssoftware (CFD), zur Modellierung hydrodynamischer Prozesse in Chemieapparaten verwendet wird.

Reaktionen zur Herstellung von Grignard-Reagenzien haben aufgrund der Verwendung dieser Reagenzien für zahlreiche organische Synthesen eine besondere Bedeutung in der chemischen Industrie. Großtechnisch werden diese Reaktionen als Semibatch-Prozesse unter Rückfluss-Kühlung bei Siedetemperatur des Lösungsmittels betrieben.
Die Experimente wurden im Reaktionskalorimeter RC1 durchgeführt. Im Gegensatz zur industriellen Prozessführung und zu bisherigen Untersuchungen wurden die Reaktionen zur Minimierung der Fehlereinflüsse der Bilanzierung im geschlossenen Drucksystem realisiert. Weiterhin erfolgte die Erfassung der Konzentrationsverläufe während der Reaktion mittels Insitu-FTIR-Spektroskopie.

Das durch die Arbeitsgruppe Verfahrenschemie entwickelte Online-Monitoring-System MoSys ist ein Softwaresystem, das dem Operator zusätzliche Informationen über den Prozessfortschritt, das voraussichtliche Reaktionsende, die Akkumulationen von Edukten oder Zwischenprodukten, den Durchmischungszustand oder die Gefahr einer thermischen Explosion durch unzureichende Kühlung zur Verfügung stellt. Zusätzliche Prozessmesstechnik in Form von Online-Analytik wird nicht benötigt. Das Zustandserkennungssystem basiert auf adaptiven Stoff- und Wärmebilanzen.
MoSys wurde auf der Grundlage von Experimenten im automatischen Laborreaktor entwickelt. Als Modellprozess wurde die heterogen katalysierte Hydrierung eines Nitroaromaten ausgewählt.
Ein derartiges Online-Zustandserkennungssystem ist bei allen ausreichend exothermen Batch- und Semibatch-Prozessen einsetzbar, wenn die Nutzinformationen in der Wärme- und Stoffbilanz enthalten sind. Neben einer Erhöhung der Anlagen- und Umweltsicherheit wird durch den Einsatz des Zustandserkennungssystems weiterführendes Prozesswissen generiert, das als Grundlage für eine Prozessoptimierung genutzt werden kann.

Der Vortrag endet mit einem Ausblick auf geplante Forschungsarbeiten der Abteilung für Experimentelle Thermofluiddynamik auf dem Gebiet der Verfahrenschemie.
  • Lecture (others)
    DECHEMA/GVC-Arbeitsausschuss "Sicherheitsgerechtes Auslegen von Chemieapparaten" 54. Sitzung vom 11.-12. Dezember 2002 im DECHEMA-Haus, Frankfurt am Main

Publ.-Id: 5121 - Permalink


Biocere auf Basis bakterieller Membranproteine für schwermetall-bindende Filter zur Behandlung von industriellen Abwässern und kontaminiertem Grundwasser
Selenska-Pobell, S.; IfW-Gruppe; IfAA-Gruppe; Feinchemie Sebnitz;
Die Reinigung schwermetallbelasteter Abwässer erlangt zunehmende Bedeutung, bedingt durch die negativen Auswirkungen der giftigen oder radioaktiven Substanzen auf Gesundheit und Umwelt. Herkömmliche Reinigungsverfahren sind oft kostenintensiv und weniger effizient. Der Einsatz innovativer Entfernung von toxischen Substanzen oder Radionukliden aus Abwässern. Ausgangspunkt sind Silicium- oder Metalloxid-Sole, die durch Hydrolyse der entsprechenden Alkoxide gebildet werden. So entstehen stabile nanokristalline Dispersionen, die durch Änderung des pH-Wertes oder durch Temperaturerhöhung schnell gelieren und damit die Biokomponenten effektiv immobilisieren.....
  • Lecture (others)
    Statusseminar in Dresden 19.11.2002

Publ.-Id: 5120 - Permalink


Humic Colloid-Borne Migration of Uranium in Sand Columns
Artinger, R.; Rabung, T.; Kim, J. I.; Sachs, S.; Schmeide, K.; Heise, K. H.; Bernhard, G.; Nitsche, H.;
Column experiments were carried out to investigate the influence of humic colloids on subsurface uranium migration. The columns were packed with well-characterized aeolian quartz sand and equilibrated with groundwater rich in humic colloids (dissolved organic carbon (DOC): 30 mg dm-3). U migration was studied under an At/1% CO2 gas atmosphere as a function of the migration time, which was controlled by the flow velocity or the column length. In addition, the contact time of U with groundwater prior to introduction into a column was varied. U(VI) was found to be the dominant oxidation state in the spiked groundwater. The breakthrough curves indicate that U was transported as a humic colloid-borne species with a velocity up to 5% faster than the mean groundwater flow. The fraction of humic colloid-bome species increases with increasing prior contact time and also with decreasing migration time. The migration behavior was attributed to a kinetically controlled association/dissociation of U onto and from humic colloids and also a subsequent sorption of U onto the sediment surface. The column experiments provide an insight into humic colloid-mediated U migration in subsurface aquifers.
  • Journal of Contaminant Hydrology 58 (2002) 1-12.

Publ.-Id: 5119 - Permalink


Weiterentwicklungen bei der Synthese von Huminsäuremodellverbindungen und Untersuchungen zur Komplexierung und Sorption von Neptunium mit Huminsäuren
Sachs, S.; Schmeide, K.;
kein Abstract
  • Lecture (others)
    Workshop PSI-FZR, Forschungszentrum Rossendorf, Rossendorf, Germany, 21.-22.10.2002

Publ.-Id: 5118 - Permalink


Experimental validation of the porous media approach for rod bundle geometry under crossflow conditions.
Kliem, M.;
At present, there are two possible approaches, which practically are used for the thermal-hydraulic analysis of the reactor core in simulations, where crossflow effects are relevant: the representation of the core by a system of separated parallel flow subchannels with provision of a forced crossflow mixing by implementation of additional formulations and the porous body approach, in which the core geometry is replaced by a structure of homogenized zones of porous media. When crossflow is comparable with flow along the bundles, the porous body approach is the only one suitable method to perform steady-state and transient flow calculations for safety analyses.
The CFD – code CFX-4 offers a porous region model for the modelling of the core geometry as a homogenized medium. This model is characterised by a set of properties (volume porosity, resistance to flow and so on).
The Core Crossflow Experimental Facility (CCEF) was built with the objective to obtain experimental data for the flow in a rod bundle under the conditions of forced crossflow with relatively low Reynolds numbers and variable flow angle.
The test section of CCEF (a plexi-glass model) contains the test rod bundle. The test rod bundle is based on the geometry of a typical PWR with a pitch/diameter ratio of 1.33 and was scaled with a factor 1.5. The crossflow was induced by an asymmetrical outlet condition for the bundle. The test bundle consists of the 100 plexiglass rods, arranged in 4 rows. Additional internals, which are typical for a reactor core geometry, were not installed in the test section. The working fluid in the experiments was water. For the velocity measurements the one-component laser-Doppler anemometer (LDA) was used.
Calculations for the comparison with experimental data were performed in two different approaches. The detailed geometry was created for the calculation of flow fields with k-e turbulence model and a relative simple geometry of the test section for the flow simulations in the porous region approach.
The results of the experimental investigations on the CCEF and the comparison with the calculations, performed with CFX-4 Code in the geometry of the test section are presented in this paper.
Keywords: PWR, CFD, rod bundle, Experiment, porous.
  • Lecture (Conference)
    11th International Conference on Nuclear Engineering, Tokyo, Japan, April 20-23, 2003 ICONE11-36502
  • Contribution to proceedings
    11th International Conference on Nuclear Engineering, Tokyo, Japan, April 20-23, 2003 ICONE11-36502

Publ.-Id: 5117 - Permalink


An inverse glance at MHD
Stefani, F.; Gerbeth, G.;
We give an overview about our recent activities to solve inverse problems appearing in various branches of MHD. The very general problem, the full reconstruction of velocity or turbulence parameters of fluid flows with arbitrary magnetic Reynolds numbers from externally measured magnetic fields varying in space and time, is tackled from two different corners. First, we explore the restricted inverse dynamo problem of determining, from a limited number of spectral data, the radial profile alpha(r) of an isotropic alpha^2 dynamo model. Among our results is the construction of oscillatory dynamos of this type, which might be of some interest for stellar dynamos. Second, we consider the topic of contactless velocity reconstruction in industrial applications with moderate magnetic Reynolds numbers from the measured deformation of two different external magnetic fields.
  • Lecture (Conference)
    5. MHD-Tage, Forschungszentrum Rossendorf, 25.-26. 11. 2002

Publ.-Id: 5116 - Permalink


Sampling and Characterization of Natural Rock Material
Sachs, S.; Mibus, J.; Bernhard, G.;
kein Abstract
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field", Manchester, Great Britain, 25.-26.11.2002

Publ.-Id: 5115 - Permalink


Numerical experience with the integral equation approach to dynamos in finite domains
Xu, M.; Stefani, F.; Gerbeth, G.;
The integral equation approach to steady dynamos in finite domains is employed to solve the eigenvalue problem for spherically symmetric, isotropic alpha^2 dynamo models. Three examples of the function alpha(r) with steady and oscillatory solutions are considered. A convergence rate proportional to the inverse square of the number of grid points is achieved. Based on this method, a convergence accelerating strategy is developed and the convergence rate is improved dramatically. The computed results show a good agreement with analytical results and results obtained by a differential equation solver. Typically, quite accurate results can be obtained with a few tens of grid points.
  • Poster
    5. MHD-Tage, Forschungszentrum Rossendorf, 25-26. 11. 2002

Publ.-Id: 5114 - Permalink


Progresses in the Development of Highly-Reducing Synthetic Humic Acids and in the Study of the Influence of Phenolic OH Groups on the Interaction Behavior of Humic Acids with Neptunium(V)
Sachs, S.;
kein Abstract
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field", Manchester, Great Britain, 25.-26.11.2002

Publ.-Id: 5113 - Permalink


Aktuelle Ergebnisse zur Synthese und Charakterisierung von Huminsäuren mit ausgeprägter Redoxfunktionalität
Sachs, S.;
kein Abstract
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Untersuchungen über die Komplexierung und die Migration von Actiniden und nichtradioaktiven Stoffen mit Huminsäuren unter geogenen Bedingungen, Leipzig, Germany, 26.-27.06.2002

Publ.-Id: 5112 - Permalink


Synthesis and Characterization of Humic Acids with Different Functional Properties
Sachs, S.;
kein Abstract
  • Lecture (others)
    Workshop zum Forschungsvorhaben "Humic Substances in Performance Assessment of Nuclear Waste Disposal: Actinide and Iodine Migration in the Far-Field", Paris, France, 23.-24.04.2002

Publ.-Id: 5111 - Permalink


ROCOM experiments on the coolant mixing in the upper plenum of a PWR
Kliem, S.; Prasser, H.-M.; Grunwald, G.; Höhne, T.; Rohde, U.; Weiß, F.-P.;
The reactor core of light water reactors consists of fuel elements with different enrichment and exposure. This circumstance is responsible for differences in the heat release of the single fuel elements. As a consequence, the fuel element outlet temperatures differ, too. Differences of more than 30 K are reached in the stationary state at full power. It is known, that these differences in the outlet temperatures do not fully vanish during the travelling of the coolant through the upper plenum. Thus, a certain temperature profile is still existing over the cross section of the hot leg nozzle. In order to study the coolant mixing inside the upper plenum, special tests have been carried out at the test facility ROCOM (Rossendorf Coolant Mixing Model).
  • Lecture (Conference)
    Jahrestagung Kerntechnik, Berlin,20.-22.Mai 2003, Proceedings pp. 73-76
  • Contribution to proceedings
    Jahrestagung Kerntechnik, Berlin,20.-22.Mai 2003, Proceedings pp. 73-76

Publ.-Id: 5110 - Permalink


Attenuation and scatter correction for in-beam PET monitoring of tumour irradiations with heavy ions
Pönisch, F.; Enghardt, W.; Lauckner, K.;
An in-beam dual head positron camera is used to monitor the dose application in situ during the tumour irradiation with carbon ion beams at the experimental heavy ion therapy facility at GSI Darmstadt.
Therefore, a positron emission tomograph has been mounted directly at the treatment site.
A fully 3D reconstruction algorithm based on the Maximum Likelihood Expectation Maximisation (MLEM) algorithm has been developed and adapted to this spatially varying imaging situation.
The scatter and attenuation correction is included into the forward projection step of the Maximum Likelihood image reconstruction.
This requires an attenuation map containing the information on the material composition and densities. This information is derived from the X-ray computed tomograms of the patient and the patient fixation system including the head-rest.
The normalisation of scattered events relative to the unscattered events is done by a global scatter fraction factor which is estimated by means of a Monte Carlo simulation. The feasibility of the proposed algorithm is shown by means of computer simulations, phantom measurements as well as patient data.
Keywords: PET attenuation scatter correction "heavy ion therapy"
  • Physics Medicine and Biology vol. 48 (2003) 2419-2436

Publ.-Id: 5109 - Permalink


Different Simulations of the Phase 2 of the OECD/NRC BWR Turbine Trip Benchmark with the Code DYN3D
Grundmann, U.; Rohde, U.; (Editors)
The OECD/NRC Boiling Water Reactor (BWR) Turbine Trip (TT) Benchmark based on the turbine trip test 2 (TT2) in the reactor Peach Bottom 2 [1] is approved for vali-dating the coupled system thermal-hydraulic and 3D neutron kinetics codes for BWR's. The phase 2 of the benchmark consists in the calculation of the core re-sponse for given thermal-hydraulic boundary conditions. This part of the benchmark is used for the validation of the DYN3D code [2].

The transient was initiated by the closure of the turbine stop valve. The pressure wave, which is moved to the core is attenuated by the opening of the bypass valve. When the wave reaches the core the void in the core is reduced, which results in an increase of the reactivity and power. The power peak is limited by the Doppler effect and the reactor scram.

The standard calculation with DYN3D is based on the consideration of 764 coolant channels (1 channel per fuel assembly), the consideration of the assembly disconti-nuity factors (ADF), the phase slip model of MOLOCNIKOV. The consideration of assembly discontinuity factors (ADF) is possible not in all three-dimensional codes. DYN3D allows calculations with and without the ADF to study their influence on this transient. Several participants of the benchmark perform calculations with 33 ther-mal-hydraulic channels, which correspond to the thermal-hydraulic map used in the TRAC-BF1/NEM model [1]. The influence of the number of coolant channels is stud-ied also in this paper. The phase slip model of MOLOCHNIKOV [3] is the standard model of DYN3D for void fraction calculation. A comparison was made with the ZUBER-FINDLAY model [4]. The cross sections sets were condensed over radial planes to generate sets for the one-dimensional simulation, which was also per-formed with DYN3D. The results of the different options are compared with the re-sults of the standard calculation.

Keywords: nuclear reactors, boiling water reactors, turbine trip, experiments, benchmarks, code validation, best estimate analysis, transient, reactor cores, neutron kinetics, thermal hydraulics, three-dimensional kinetics, assembly discontinuity factors, one-dimensional kinetics, boiling models, slip correlation, void fraction, power excusion, power distribution, eigenvalue
  • Lecture (Conference)
    Annual Meeting on Nuclear Technology, Berlin, May 20 - 22, 2003
  • Contribution to proceedings
    Annual Meeting on Nuclear Technology, Berlin, May 20 - 22, 2003

Publ.-Id: 5108 - Permalink


Simulation of creep tests with French or German RPV-steel and investigation of a RPV-support against failure
Willschütz, H.-G.; Altstadt, E.; Sehgal, B. R.; Weiss, F.-P.;
Investigating the hypothetical core melt down scenario for a light water reactor (LWR) a possible failure mode of the reactor pressure vessel (RPV) and its fail-ure time has to be considered for a determination of the loadings on the con-tainment. Numerous experiments have been performed accompanied with ma-terial properties evaluation, theoretical, and numerical work (Rempe, 1993, Theofanous, 1997, Chu 1999).
For pre- and post-test calculations of Lower Head Failure experiments like OLHF or FOREVER it is necessary to model creep and plasticity processes. Therefore a Finite Element Model is developed at the FZR using a numerical approach which avoids the use of a single creep law employing constants de-rived from the data for a limited stress and temperature range. Instead of this a numerical creep data base (CDB) is developed where the creep strain rate is evaluated in dependence on the current total strain, temperature and equivalent stress. A main task for this approach is the generation and validation of the CDB. Additionally the implementation of all relevant temperature dependent material properties has been performed. For the consideration of the tertiary creep stage and for the evaluation of the failure times a damage model accord-ing to an approach of Lemaitre is applied.
The validation of the numerical model is performed by the simulation of and comparison with experiments. This is done in 3 levels: starting with the simula-tion of single uniaxial creep tests, which is considered as a 1D-problem. In the next level so called “tube-failure-experiments” are modeled: the RUPTHER-14 and the “MPA-Meppen”-experiment. These experiments are considered as 2D-problems. Finally the numerical model is applied to scaled 3D-experiments, where the lower head of a PWR is represented in its hemispherical shape, like in the FOREVER-experiments. This report deals with the 1D- and 2D-simulations.
An interesting question to be solved in this frame is the comparability of the French 16MND5 and the German 20MnMoNi5-5 RPV-steels, which are chemi-cally nearly identical. Since these 2 steels show a similar behavior, it should be allowed on a limited extend to transfer experimental and numerical data from one to the other.
After analyzing the FOREVER calculations, it seems to be advantageous to introduce a vessel support which can unburden the vessel from a part of the mechanical load and, therefore, avoid the vessel failure or at least prolong the time to failure. This can be a possible accident mitigation strategy. Additionally, it is possible to install an absolutely passive automatic control device to initiate the flooding of the reactor pit to ensure external vessel cooling in the event of a core melt down.
Keywords: Core melt down accident, high temperature material properties and creep data base, French and German RPV-steel, FEM-calculations of 1D-, 2D, and 3D-tests.
  • Annals of Nuclear Energy, vol 30, 10, pp 1033-1063

Publ.-Id: 5107 - Permalink


Beta decay of 57Zn
Jokinen, A.; Nieminen, A.; Äystö, J.; Borcea, R.; Caurier, E.; Dendooven, P.; Gierlik, M.; Gorska, M.; Grawe, H.; Hellström, M.; Karny, M.; Janas, Z.; Kirchner, R.; La Commara, M.; Martinez-Pinedo, G.; Mayet, P.; Penttilä, H.; Plochocki, A.; Rejmund, M.; Roeckl, E.; Sawicka, M.; Schlegel, C.; Schmidt, K.; Schwengner, R.;
Beta-delayed proton decay of 57Zn has been investigated at the GSI on-line isotope separator. The studied 57Zn nuclei were produced in fusion evaporation reactions by using a150 MeV 32S beam on a 28Si target. Beta-delayedprotonsweremeasuredbyacharged-particle
telescope detector.The observed decay pattern was used to construct the level scheme of 57Cu and to extract the beta feeding distribution. The experimental results are compared with shell-model calculations.
Keywords: Fusion evaporation reaction, on-line isotope separation, beta-delayed proton decay, Gamow-Teller strength, shell model calculations.
  • European Physical Journal direct A3, 1 (2002)

Publ.-Id: 5106 - Permalink


Post Test Calculation of Tube Creep Failure Experiments
Willschütz, H.-G.; Altstadt, E.;
For numerical simulations of Lower Head Failure experiments like OLHF or FOREVER it is necessary to model creep and plasticity. Therefore a FE Model is de-veloped using a numerical approach which avoids the use of a single creep law. In-stead of this a numerical creep data base (CDB) is developed where the creep strain rate is evaluated in dependence on the current strain, temperature and stress. For this approach the generation and validation of the CDB is necessary. For an evalua-tion of the failure times a damage model according to Lemaitre [1] is applied.
The validation of the numerical model is performed by the simulation of and compari-son with experiments. This is done in 3 levels: the simulation of single uniaxial creep tests, which is considered as a 1D-problem; so called “tube-failure-experiments”: the RUPTHER-14 and the “MPA-Meppen”-experiment. These experiments are consid-ered as 2D-problems. Finally the numerical model is applied to scaled 3D-experiments, where the lower head of a PWR is represented in its hemispherical shape, like in the FOREVER-experiments.
An interesting question to be solved in this frame is the comparability of the French 16MND5 and the German 20MnMoNi55 RPV-steels, which are chemically nearly identical. If these 2 steels show a similar behavior, it should be allowed to transfer experimental and numerical data from one to the other.
Keywords: Creep of RPV-steel, FEM simulation of tube failure experiments
  • Lecture (Conference)
    Jahrestagung Kerntechnik 2003, Berlin, 20.-22. Mai 2003, Tagungsband S. 141-146
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2003, Berlin, 20.-22. Mai 2003, Tagungsband S. 141-146

Publ.-Id: 5104 - Permalink


Si-nanocrystal memory devices prepared by r.f. magnetron sputtering.
Schmidt, J. U.; Schmidt, B.;
kein Abstrakt
Keywords: Si nanocrystal memory photoluminescence infrared spectroscopy electrical testing
  • Poster
    MRS Conference, Fall 2002, Boston, USA

Publ.-Id: 5103 - Permalink


Complex Formation of Uranium(IV) with Phosphate and Arsenate
Geipel, G.;
Heavy metals in the aquatic environment are normally transported as a complexed species. Knowledge about the complex formation is therefore an essential constituent in prediction of the migration of these elements.
Especially in Saxony and Thuringia the intense uranium mining and milling causes a wide variety of contaminated waters. These seepage and mine waters contain several inorganic and organic complex forming agents [1, 2].
We studied the complex formation of uranium(IV) with phosphoric acid and arsenic acid in strong acid solution by UV-vis Spectroscopy and Laser-induced Photoacoustic Spectroscopy (LIPAS). In both systems the formation of a one to one complex was detected. The dependency of the complex formation on the concentration of hydrogen ions in the solution leads to the conclusion, that one proton is released during the complex formation reaction. Studying the complex formation as function of ionic strength we can extrapolate the formation constant at infinite dilution using the SIT theory.
Including the protonation constants for phosphoric and arsenic acid, respectively, we obtained the formation constants according to the complex formation reaction

U4+ + 2H+ + XO43- ? UH2XO43+ (1)

for X = P log ß0 = 25.23 ± 0.13 and for X = As log ß0 = 23.94 ± 0.08.
Comparing these data with the corresponding uranium(VI) systems [3,4] it can be seen that the binding tendency of the dihydrogenarsenate is lower than that of dihydrogenphosphate. Also the binding tendency of the uranium(VI) is lower than that of uranium(IV). This is an expected behavior.
The specific ionic interaction coefficients for the uranium(IV) phosphate and arsenate system are calculated to be e(UH2XO43+ - ClO4-) = 0.42 and 0.46 in the phosphate and in the arsenate system, respectively.

[1] G. Geipel, G. Bernhard, M. Rutsch, V. Brendler, H. Nitsche; Speciation in Water Released from Mining and Milling Facilities In T.E. Baca and T. Florkowski (eds.), The environmental Challenges of Nuclear Disarmament, Kluwer Academic Publishers, 2000, p. 323-332
[2] G. Bernhard, G. Geipel, V. Brendler, H. Nitsche; Speciation of Uranium in Seepage Waters from a Mine Tailing Pile Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS); Radiochimica Acta, 74, 87, (1996)
[3] I. Grenthe, J. Fuger, R. J. Lemire, A. B. Muller, C. Nguyen-Trung and H. Wanner, Chemical Thermodynamics of Uranium, 1st ed. , Elsevier Science Publishers, Amsterdam, 1992.
[4] M. Rutsch, G. Geipel, V. Brendler, G. Bernhard, H. Nitsche; Interaction of uranium (VI) with arsenate (V) in aqueous solution studied by time-resolved laser-induced fluorescence spectroscopy, Radiochimica Acta 86, 135-141 (1999)
  • Contribution to HZDR-Annual report
    UMH, Freiberg 15.-21.9.2002

Publ.-Id: 5102 - Permalink


Mixed rhenium(I) tricarbonyl complexes for the development of radiopharmaceuticals for CNS-receptor imaging
Garcia, R.; Paulo, A.; Domingos, A.; Santos, I.; Spies, H.; Pietzsch, H.-J.; Bergmann, R.; Alberto, R.;
The agostic B-H...Re bond in complex [Re{kappa3-H(µ-H)B(timMe)2}(CO)3] (1) (timMe=2-mercapto-1-methylimidazolyl) is easily cleaved by functionalized isonitriles, bearing a (2-methoxyphenyl)piperazine moiety (part of WAY 100635), leading to the novel complexes [Re{kappa3-H(µ-H)B(timMe)2}(C=NR-WAY)(CO)3] (R= butylene (4), pentylene (5) or hexylene (6)). These mixed Re(I) tricarbonyl complexes (4-6) have been fully characterized by the usual analytical techniques, which included X-ray diffraction analysis in case of 4. Complexes 4-6 can be seen as suitable surrogate molecules of potential 99mTc-radiopharmaceuticals for imaging of 5-HT1A subtype of serotonin receptors.
Keywords: Rhenium, isonitriles, poly(mercaptoimidazolyl)borates, 5-HT1A receptors
  • Poster
    6th International Symposium on Technetium in Chemistry and Nuclear Medicine, Bressanone/I, 04.-07.09.2002
  • Contribution to external collection
    In: Technetium, Rhenium and Other Metals in Chemistry and Nuclear Medicine (Edited by Nicolini M., Mazzi U.) SGEditoriali Padova 2002, 143-145

Publ.-Id: 5101 - Permalink


Complex Formation of Uranium(IV) with Phosphate and Arsenate
Geipel, G.; Bernhard, G.; Brendler, V.;
Heavy metals in the aquatic environment are normally transported as a complexed species. Knowledge about the complex formation is therefore an essential constituent in prediction of the migration of these elements.
Especially in Saxony and Thuringia the intense uranium mining and milling causes a wide variety of contaminated waters. These seepage and mine waters contain several inorganic and organic complex forming agents [1, 2].
We studied the complex formation of uranium(IV) with phosphoric acid and arsenic acid in strong acid solution by UV-vis Spectroscopy and Laser-induced Photoacoustic Spectroscopy (LIPAS). In both systems the formation of a one to one complex was detected. The dependency of the complex formation on the concentration of hydrogen ions in the solution leads to the conclusion, that one proton is released during the complex formation reaction. Studying the complex formation as function of ionic strength we can extrapolate the formation constant at infinite dilution using the SIT theory.
Including the protonation constants for phosphoric and arsenic acid, respectively, we obtained the formation constants according to the complex formation reaction

U4+ + 2H+ + XO43- ? UH2XO43+ (1)

for X = P log ß0 = 25.23 ± 0.13 and for X = As log ß0 = 23.94 ± 0.08.
Comparing these data with the corresponding uranium(VI) systems [3,4] it can be seen that the binding tendency of the dihydrogenarsenate is lower than that of dihydrogenphosphate. Also the binding tendency of the uranium(VI) is lower than that of uranium(IV). This is an expected behavior.
The specific ionic interaction coefficients for the uranium(IV) phosphate and arsenate system are calculated to be e(UH2XO43+ - ClO4-) = 0.42 and 0.46 in the phosphate and in the arsenate system, respectively.

[1] G. Geipel, G. Bernhard, M. Rutsch, V. Brendler, H. Nitsche; Speciation in Water Released from Mining and Milling Facilities In T.E. Baca and T. Florkowski (eds.), The environmental Challenges of Nuclear Disarmament, Kluwer Academic Publishers, 2000, p. 323-332
[2] G. Bernhard, G. Geipel, V. Brendler, H. Nitsche; Speciation of Uranium in Seepage Waters from a Mine Tailing Pile Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS); Radiochimica Acta, 74, 87, (1996)
[3] I. Grenthe, J. Fuger, R. J. Lemire, A. B. Muller, C. Nguyen-Trung and H. Wanner, Chemical Thermodynamics of Uranium, 1st ed. , Elsevier Science Publishers, Amsterdam, 1992.
[4] M. Rutsch, G. Geipel, V. Brendler, G. Bernhard, H. Nitsche; Interaction of uranium (VI) with arsenate (V) in aqueous solution studied by time-resolved laser-induced fluorescence spectroscopy, Radiochimica Acta 86, 135-141 (1999)
  • Lecture (Conference)
    Uranium Mining and Hydrogeology III, Freiberg 15.-21.9.2002

Publ.-Id: 5100 - Permalink


fs-Sluorescence Spectroscopy of Actinides with Organic Ligands
Geipel, G.;
keinen Abtract
  • Lecture (Conference)
    Konferenz, University of Tokyo 27.8.2002

Publ.-Id: 5099 - Permalink


New Results in fs-Fluorescence Spectroskopy of Actinides with Organic Ligands The University of Tokyo, August 28. 2002
Geipel, G.;
keinen Abtract
  • Lecture (Conference)
    Konferenz, University of Tokyo, 28.8.2002

Publ.-Id: 5098 - Permalink


Komplexbildung mit organischen Liganden
Geipel, G.;
keinen Abstract
  • Lecture (Conference)
    Intern. Seminar, Institut für Radiochemie, FZR, 23.6.2002

Publ.-Id: 5097 - Permalink


Komplexbildung von Uran mit organischen Liganden-Untersuchung mittels Ultrakurzzeitspektroskopie
Geipel, G.;
keinen Abstract
  • Lecture (Conference)
    Internes Seminar mit der WISMUT, Rossendorf, 7.5.2002

Publ.-Id: 5096 - Permalink


Laserspektroskopie im Institut für Radiochemie-Speziation von Schwermetallen am Beispiel der Actiniden
Geipel, G.;
keinen Abstract
  • Lecture (Conference)
    Bundesanstalt für Materialprüfung Berlin, 13.3.2002

Publ.-Id: 5095 - Permalink


Rhenium- and technetium complexes of the "supernitrido" type [M(N)(PNP)(X-Y)] bearing functionalized dithiol ligands. A versatile approach for the labelling of biomolecules
Bolzati, C.; Cazzola, E.; Duatti, A.; Jung, C. M.; Pietzsch, H.-J.; Refosco, F.; Spies, H.; Tisato, F.;
Neutral nitrido M(V) heterocomplexes of the type [M[N)(PNP)(S-S)] (M=99Tc, Re, 99mTc; PNP=diphosphinoamine; S-S=dithiolate) have been prepared and fully characterised at macroscopic as well as nca levels. Chirality introduced at the dithiolate framework by insertion of a carboxylic group induces the formation of syn- and anti- diastereoisomers.
Keywords: technetium, supernitrido, dithiol ligands
  • Poster
    6th International Symposium on Technetium in Chemistry and Nuclear Medicine, Bressanone/I, 04.-07.09.2002
  • Contribution to external collection
    In: Technetium, Rhenium and Other Metals in Chemistry and Nuclear Medicine (Edited by Nicolini M., Mazzi U.) SGEditoriali Padova 2002, 175-177

Publ.-Id: 5094 - Permalink


Synthese, Charakterisierung und Löslichkeit von Erdalkaliuranylcarbonaten M2[UO2(CO3)3]·xH2O; M: Mg, Ca, Sr, Ba
Amayri, S.;
no abstract delivered from author
  • Open Access LogoWissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-359 November 2002

Downloads:

Publ.-Id: 5093 - Permalink


Bewertung der Neutronenversprödung von WWER-Druckbehälterstählen anhand der Ergebnisse der Bestrahlungsexperimente Rheinsberg
Böhmert, J.; Viehrig, H.-W.; Ulbricht, A.;
Im WWER-Prototyp-Reaktor WWER-2 des KKW Rheinsberg ist ein umfangreiches Bestrahlungsprogramm zur Untersuchung der Anfälligkeit von WWER-Reaktordruckbehälter(RDB)-Stählen und -Schweißwerkstoffe gegen Neutronenversprödung durchgeführt worden. Dabei wurden insgesamt 21 Chargen derartiger Stähle bestrahlt. Zusätzlich wurden Druckbehälterstähle nach ASTM-Spezifikation in das Programm einbezogen. Die Nachbestrahlungsuntersuchungen umfassten Charpy-Kerbschlagbiegeversuche, Zugversuche, Härtemessungen und bruchmechanische Prüfungen. Außerdem wurden von jeder Charge auch strukturanalytische Untersuchungen mit der Neutronenkleinwinkelstreumethode in das Programm einbezogen. Obwohl das Bestrahlungsprogramm Rheinsberg in erster Linie der Verbreiterung der Datenbasis zum Bestrahlungsverhalten von WWER-Druckbehälterstählen und nicht der systematischen Untersuchung bestimmter Einflussparameter dienen sollte, lässt der umfangreiche Datensatz, der nach Abschluss der Untersuchungen zur Verfügung steht, auch interessante Rückschlüsse über die kausalen Zusammenhänge zwischen den metallurgischen Eingangsparametern und der Neutronenfluenz einerseits und den strahlenbedingten Eigenschafts- und Gefügeänderungen andererseits zu. Der Beitrag bewertet unter diesem Aspekt die erhaltenen Ergebnisse.

  • Lecture (Conference)
    Jahrestagung Kerntechnik 2003, Tagungsbericht, 20. - 22. 05. 2003, Berlin, S. 595-598
  • Contribution to proceedings
    Jahrestagung Kerntechnik 2003, Tagungsbericht, 20. - 22. 05. 2003, Berlin, S. 595-598

Publ.-Id: 5092 - Permalink


Dispersion of the nonlinear susceptibility of GaAs in the THz range
Dekorsy, T.; Helm, M.; Yakovlev, V. A.; Seidel, W.; Keilmann, F.;
We investigate the nonlinear susceptibility of GaAs via SHG with a free-electron laser below the optical phonon resonance. The observation of a maximum and a zero-crossing allows the quantitative determination of higher-order lattice potentials.
Keywords: nonlinear optics, second harmonic generation, higher order lattice potential, free-electron laser, GaAs
  • Lecture (Conference)
    Quantum Electronics and Laser Science Conference (QELS), 2003, Baltimore, Maryland, USA, Mai 2003
  • Contribution to proceedings
    Quantum Electronics and Laser Science Conference (QELS), 2003, Baltimore, Maryland, USA, Mai 2003

Publ.-Id: 5091 - Permalink


Synthesis of hydroxyl silylated rhenium and (99mTc)technetium "3+1" oxo-complexes with the H2PNS tridentate ligand
Fernandes, C.; Knieß, T.; Santos, I.; Seifert, S.; Spies, H.; Zablotskaya, A.;
Oxo-complexes of general formula [99mTc(O)(PNS)(S(CH2)nOSiR3)] (3a-c) were synthesized by direct reduction of [99mTcO4]- with stannous chloride in the presence of the tridentate H2PNS and of the monodentate [HS(CH2)nOSiR3] ligands (n=2, R=Ph; (1a); n=3, R=Ph, (1b); n=3, R=Et, (1c)). The 99mTc complexes were characterized by comparison of their HPLC profiles with the analogous rhenium complexes (2a-c). Complexes 3a-c were obtained with high radiochemical purity (>95%) and their stability was investigated in PBS pH 7.4, rat plasma and against glutathione, at 37°C. The pH influence on the cleavage of the O-Si bond was also investigated.
Keywords: hydroxylsilylated thiols, Re, 99mTc, phosphines
  • Poster
    6th International Symposium on Technetium in Chemistry and Nuclear Medicine, Bressanone/I, 04.-07.09.2002
  • Contribution to external collection
    In: Technetium, Rhenium and Other Metals in Chemistry and Nuclear Medicine (Edited by Nicolini M., Mazzi U.) SGEditoriali Padova 2002, 211-233

Publ.-Id: 5090 - Permalink


Simultaneous occurrence of Hodgkin's lymphoma and eosinophilic granuloma: A potential pitfall in positron emission tomography imaging
Naumann, R.; Beuthien-Baumann, B.; Fischer, R.; Kittner, T.; Bredow, J.; Kropp, J.; Ockert, D.; Ehninger, G.;
Positron emission tomography (PET) with [18F]fluorodeoxyglucose [18F]FDG has evolved as a method if increasingly clinical importance in the management of patients with malignant lymphoma. However, inflammatory lesions also accumulate [18F]FDG and may cause difficulties with interpretation. This report deals with 2 patients with simultaneous occurrence of Hodgkin's lymphoma and eosinophilic granuloma, a rare but known coincidence of diseases. In the first case, Hodgkin's disease could not be differentiated from eosinophilic granuloma. Positron emission tomography showed increased [18F]FDG uptake both in lymphoma manifestations and in the granuloma. In the second case with proven Hodgkin's disease, post-treatment examination showed a positive PET lesion in the mediastinal residual mass, which was interpreted as viable lymphoma. However, histologic examination revealed that it was an eosinophilic granuloma.
Keywords: Hodgkin's disease, 2-[18F]fluorodeoxyglucose, Eosinophilic granuloma, Langerhans cell histiocytosis, Chemotherapy, Mediastinoscopy, Radiation therapy
  • Clinical Lymphoma Vol. 3, No. 2 (2002) 121-124

Publ.-Id: 5089 - Permalink


Bioactivity of small technetium complexes
Pietzsch, H.-J.; Johannsen, B.;
Early evidence that small technetium compounds may be subject to active transport processes was provided by the historical serependipitous finding that pertechnetate was handled by the sodium-iodide symporter in the thyroid gland. The pertechnetate ion can mimic the iodide ion, despite its different nature and geometry.
Starting from this observation 99mTc radiotracers are designed for probing and imaging a distinct biochemical reaction of diagnostic relevance. Such biochemical reactions are transmembrane processes, binding reactions, enzymatic conversions, possibly redox reactions, etc., and key proteins or enzymes are the targets of the 99mTc diagnostic agents. "Bioactivity" is therefore required in the sense of the 99mTc species being able to participate in the biochemical reaction of interest, being bound or processed.
Keeping the artificiality of technetium in the human body in mind, the feasibility of biochemical Tc-99m probes can only be based on imperfection of the target specificity, on the tolerance of the target molecule towards a substrate mimic that accidentally fits the target molecule to some extent, despite its different chemical nature. This will be examplified by the development of 99mTc ligands for brain receptors.
The possibility of using biochemical99mTc probes for various CNS receptors is due to the tolerance of the target molecules towards metal-based mimics. As the high in-vitro affinities to various neuroreceptors in the nanomolar and subnanomolar range indicate, molecular recognition of complex technetium molecules has become possible.
However, one main issue in developing CNS receptor imaging agents remains the very low or totally absent brain uptake. After two decades of research into brain 99mTc perfusion agents it has now become feasible for certain technetium complexes to cross the blood-brain barrier. In contrast, a suitable combination of a high receptor affinity with a sufficient brain uptake was not achieved. Systematic studies of model technetium compounds with various logP and pKa values provided rules for selected homologous series of complexes but did not really help to tackle the problem. Since a wide variety of chemically diverse compounds, among them lipophilic cations such as 99mTc MIBI, 99mTc tetrofosmin or Q-series compounds, may be actively transported out of the cell by P-glycoprotein, it might also affect the transport of potentially receptor-binding 99mTc agents.

To conclude, approaches to specific small technetium radiopharmaceutical tracers have not changed much in recent years. From a coordination chemistry point of view, the design of new 99mTc radiopharmaceuticals starts conceptually with the modification of the coordination environment around the metal with a variety of chelators. Diversity of the chelate unit is needed, and considerable research has consequently been devoted to designing improved and new chelate types, resulting in a flourishing technetium chemistry. New impetus has come in particular from the progress made in technetium(I) chemistry.
Although this knowledge explosion in the technetium chemistry has been translated into targeted radiopharmaceutical research activity the number of newly launched Tc-99m radiopharmaceuticals is stagnant, at least in a short-term perspective. The development of biochemically specific, small technetium and rhenium complexes remains therefore a challenging, rewarding and often frustrating activity.
  • Lecture (Conference)
    Jahrestagung der Deutschen Pharmazeutischen Gesellschaft, Berlin, 9.-12.10.2002
  • Abstract in refereed journal
    Archiv der Pharmazie Pharmaceutical and Medicinal Chemistry 335, Suppl. 1 (2002) 40

Publ.-Id: 5088 - Permalink


Exclusive charge exchange reaction pD --> n (pp) within the Bethe-Salpeter formalism
Kaptari, L. P.; Kämpfer, B.; Semikh, S. S.; Dorkin, S. M.;
The exclusive charge exchange reaction pD --> n (pp) at intermediate energies is studied within the Bethe-Salpeter fromalism. The final state interaction in the detected pp pair at nearly zero excitation energy is described by the 1S0 component of the Bethe-Salpeter amplitude. Results of numerical calculations of polarization observables and differential cross section persuade that, as in the non-relativistic case, this reaction (i) can be utilized as a "relativistic deuteron polarimeter" and (ii) delivers further information about the elementary nucleon-nucleon charge exchange amplitude.
Keywords: charge exchange amplitude, Bethe-Salpeter formalism
  • European Physical Journal A 17(1); 119-192 2003

Publ.-Id: 5087 - Permalink


Baryon Resonance Dynamics in πN → N V Reactions Near Threshold
Kämpfer, B.; Titov, A. I.; Reznilk, B. L.;
The ρ - ω interference in the exclusive reaction π N → N' e^+ e^- is studied within a schematic model including the established baryon resonances up to 1720 MeV. Near threshold the interference can be used to separate the isoscalar part of the electromagnetic current. The role of various baryon resonances is highlighted.
Keywords: baryon resonances
  • Nucl. Phys. A 721: 583c-586c Jun 30 2003

Publ.-Id: 5086 - Permalink


Atomic processes at bonded Si-interfaces studied by molecular dynamics: tailoring densities and band gaps?
Scheerschmidt, K.; Conrad, D.; Belov, A.;
Molecular dynamics simulations using empirical potentials have been employed to describe atomic interactions at interfaces created by the macroscopic wafer bonding process. Investigating perfect or distorted surfaces of different semiconductor materials enables one to study the elementary processes and the resulting defects at the interfaces, and to characterize the ability of the potentials used. Twist rotation due to misalignment and bonding over steps influence strongly the bondability of larger areas and create new types of structural units at the bonded interfaces. Ab initio density functional based simulations establish the structural units to be the stable minimum configurations and enable to predict modified electronic properties.
Keywords: Molecular dynamics, wafer bonding, interface structure
  • Computational Materials Science 24 (2002) 33-41

Publ.-Id: 5085 - Permalink


Coolant Mixing Studies for the Analysis of Hypothetical Boron Dilution Transients in a PWR
Grunwald, G.; Höhne, T.; Kliem, S.; Prasser, H.-M.; Rohde, U.; Weiß, F.-P.;
PWR transients caused by a perturbation of boron concentration or coolant temperature at the inlet nozzles depend on the mixing inside the reactor pressure vessel (RPV). Initial steep gradients are partially reduced by turbulent mixing with the ambient coolant in the RPV. However, the assumption of an ideal mixing in the downcomer and the lower plenum of the reactor leads to unrealistically small reactivity inserts. Moreover, the reactivity differences between ideal mixing and total absence of mixing are too large to be acceptable for safety analyses. In reality, a partial mixing takes place. For realistic predictions it is necessary to study the mixing within the three-dimensional flow field in the complicated geometry of a PWR. For this purpose, a 1:5 scaled model (ROCOM) of the German PWR KONVOI was built. The emphasis was put on extensive measuring instrumentation and on maximum flexibility of the facility to cover different test scenarios. The use of special electrode-mesh sensors together with a salt tracer technique allows to measure concentration fields within the downcomer and at the core entrance with a high resolution in space and time. Especially the instrumentation in the downcomer provides detailed information about the mixing phenomena. The obtained data was used to support code development for mixing modeling and validation.
Scenarios investigated are: (1) Steady-state flow in several coolant loops with a temperature or boron concentration perturbation in one of them. (2) Transient flow situations with flow rates changing in time in one or more loops, such as pump start-up scenarios with deborated slugs in one of the loops or onset of natural circulation after boiling-condenser-mode. (3) Gravity driven flow caused by large density gradients, e.g. mixing of cold ECC water with the warmer inventory in the RPV. In all cases, the experimental results show an incomplete mixing with typical concentration and temperature distributions at the core inlet which strongly depend on the conditions of the considered scenario. CFD calculations were found to be in good agreement with the experiments but take long calculation times.
Therefore, an efficient semi-analytical model (Semi-Analytical Perturbation Reconstruction) has been developed allowing the description of the coolant mixing inside the RPV by the superposition of response functions at the core entrance on Dirac-shaped perturbations in the cold leg. The validation of the model against experimental data from the ROCOM-facility is presented.
SAPR provides realistic time-dependent boron concentration fields at the core inlet that can be used for the analysis of a hypothetical boron dilution transient after start-up of the first main coolant pump in a generic four-loop PWR. Core calculations were performed with the 3D reactor dynamics code DYN3D. By varying the initial slug volume it was found, that for the given core loading pattern slugs of less than 20 m3 do not lead to re-criticality of the shut-off reactor. Calculations with the bounding slug volume of 36 m3 show, that the corresponding reactivity insertion does not result in core damage.

Keywords: BORON DILUTION, COOLANT MIXING, ROCOM TEST FACILITY, COMPUTATIONAL FLUID DYNAMICS, NEUTRON KINETICS
  • Lecture (Conference)
    11. International Conference on Nuclear Engineering ICONE-11, Tokyo, Japan, April 20-23, 2003, Proceedings CD-ROM paper 36325
  • Contribution to proceedings
    11. International Conference on Nuclear Engineering ICONE-11, Tokyo, Japan, April 20-23, 2003, Proceedings CD-ROM paper 36325

Publ.-Id: 5084 - Permalink


Perspectives and trends in radiopharmaceutical Chemistry
Johannsen, B.;
Radiopharmaceutical Chemistry has dramatically developed for over five decades together with the wide availability of an increasing number of artificially produced radioisotopes. Target and radionuclide chemistry, new labelling methods for radiohalogens and carbon-11 and radiometal chemistry are providing the tools that are required to meet the challenge of radiopharmaceutical development. The preparation and handling of radionuclides and radiopharmaceuticals has become a specialized function, and application of radioactive diagnostic and therapeutic agents constitutes one of the great advances in non-invasive medicine.
Diagnostic radiopharmaceuticals make the human body biochemically transparent with respect to individual molecular reactions. Conventional imaging with radiotracers based on the readily available generator nuclide technetium-99m or iodine-123 as well as positron emission tomography (PET), mainly with [18F]fluorodeoxyglucose, have done much to localize and recognize lesions and to predict the efficacy of treatment. The focus of radiopharmaceutical research is on the development of new tracers that bind preferentially to specific sites of action which diagnostics or therapy can be based upon. This involves the design and development of tracers for apoptosis, hypoxia, angiogenesis, detection of unstable plaques, gene therapy monitoring, imaging cardiac innervation, antibody-based reactions and a vast array of ligand-receptor interactions. Cell membrane and intracellular receptors have become a major domain of radiopharmaceutical research, involving neurotransmitters, hormones, growth factors, and cytokines. For example, new development of analogues, chelators and radionuclides leads to progress in peptide receptor imaging. While numerous radiolabelling peptides are being studied, the majority are those that target somatostatin receptors present on various tumours. The future application of radiolabelled peptides in tumour scintigraphy may be aimed at their in vivo use as prognostic predictors.

Targeted radiotherapy with peptides labelled with radionuclides emitting alpha or beta particles, or Auger or conversion electrons may become a new cancer treatment modality. This orientation has provided an impetus to research in the production and chemistry of new therapeutic radionuclides (e.g. 111In, 103mRd, 67Cu, 177Lu, 90Y, 188Re, 211At, 211Bi, 213Bi), as well as new bifunctional chelators. The advantages of targeted "cell surgery" with radiotherapeutics appears obvious. Therefore, continuing improvements are to be expected. The advent of selective targeting of radiolabelled monoclonal antibodies against tumour-associated antigens is a major breakthrough not only for cancer detection and monitoring, but also for therapy. So far, radioimmunotherapy has been more successful in the radiosensitive haematological malignancies. E.g. lymphomas and leukaemia's as compared with solid tumours. Progress in radiometal coordination chemistry and the ability to generate new constructs, such as bivalent antibodies or fusion proteins will hopefully open opportunities for new radiotherapeutics.

Radioactive compounds have been applied in creative ways to study drug action directly in laboratory animals and in humans. Because both drug pharmacokinetics and drug pharmacodynamics can be measured, radiotracer development both for labelled drugs and for labelled tracers is a key area in this field. The short half-lives of the radionuclides set limits to the period of the studies. For direct measurements of drug pharmacokinetics the drug usually must be labelled with carbon-11 to avoid changing the characteristics of the parent molecule. Fluorine-18 also is used if the drug has a fluorine atom. PET also made it possible to assess the effects of drugs on e.g. glucose metabolism, blood flow or neurotransmission using well-est...
  • Invited lecture (Conferences)
    Plenarvortrag: Jahrestagung der Deutschen Pharmazeutischen Gesellschaft, Berlin, 9.-12.10.2002
  • Abstract in refereed journal
    Archiv der Pharmazie Pharmaceutical and Medicinal Chemistry 335, Suppl. 1 (2002) 43

Publ.-Id: 5082 - Permalink


18F-fluorophenylation: Method for radiolabelling of peptides and amino acids in aqueous media
Patt, J.; Bergmann, R.; Steinbach, J.;
Despite all efforts in peptide labeling there is a still lack in suitable methods. Reaction of 4-[F-18]fluorobenzenediazonium chloride with a cysteinyl residue of a peptide provides a route for the no carrier added (n.c.a.) F-18-radiolabeling of peptides in aqueous media. Furthermore radiolabeled conjugates of cysteine might be interesting compounds for tumor imaging with PET. 4-[F-18]fluoroaniline was prepared in >60% radiochemical yield by reacting 1,4-dinitrobenzene with n.c.a. [F-18]fluoride in a microwave oven and subsequent catalytic reduction. After diazotization with NaNO2 and addition of ammonia or hydroxylamine solution cysteine or glutathione as a model peptide (GSH) were reacted with the generated diazonium cation. The reaction of 4-[F-18]fluorobenzenediazonium ion with 0.1M cysteine solution resulted in almost quantitative yields of S-4-[F18]fluorophenyldiazocysteine which was converted by UV irradiation to S-4-[F-18]fluorophenylcysteine (45%, based on 4-[F-18]fluoroaniline). S-4-[F-18]fluorophenyl-L-cysteine showed rapid and high uptake in HT29 cells and thus might be interesting for tumor imaging with PET. 75% of S-4-[F-18]fluorophenyldiazo-GSH were obtained for a GSH concentration of 1.3 mM, nearly quantitative yields at higher concentrations (based on 4-[F-18]fluoroaniline). UV-irradiation ends up in S-[F-18]fluorophenyl-GSH in good yields. In the same way the [F-18]fluorophenylcysteinyl group serves as a substitute for homophenylalanine in labeled peptides.
  • Lecture (Conference)
    Jahrestagung der Deutschen Pharmazeutischen Gesellschaft, Berlin, 9.-12.10.2002
  • Abstract in refereed journal
    Archiv der Pharmazie Pharmaceutical and Medicinal Chemistry 335, Suppl. 1 (2002) 40

Publ.-Id: 5081 - Permalink


Fundamentals of PET-radiochemistry
Wüst, F.;
Positron emission tomography (PET) is a powerful imaging technique using compounds labeled with short-lived positron emitting radioisotopes for the in-vivo study of molecular interactions and molecular pathways in the human body. The unique sensitivity and specificity of PET make the methodology also a very attractive scientific tool in drug development and evaluation. In combination with appropriately labeled radiotracer, PET offers exceptional possibilities to study physiology, metabolism, pharmacokinetics and modes of action of novel drugs. The key element in PET is the PET-radiotracer, a compound labeled with a short-lived positron emitter. The most useful positron-emitters carbon-11 and fluorine-18 have half-lives measured in minutes, being 20.4 min and 109.8 min. respectively. Consequently, times dominates all aspects of PET, and the radiotracer must be synthesized within a time frame compatible with the half-life of the radioisotope. Thus, the extensive development of the radiochemistry of positron-emitters carbon-11 and fluorine-18 is fundamental but also a special challenge. In this context, the recent developments of organic PET radiochemistry and its potential impact on drug development and evaluation will be discussed.
  • Invited lecture (Conferences)
    4. Jahreskongress für Klinische Pharmakologie, Wiesbaden, 7.-9.11.2002 (invited lecture)
  • Abstract in refereed journal
    European Journal of Clinical Pharmacology 7 (Vol. 58) (2002) S92

Publ.-Id: 5080 - Permalink


Ion beam-stimulated phase formation in fused silica
Deskovskaya, A.; Richter, E.; Komar, V.;
Phase formation involving implanted impurities is a most important ion beam-stimulated process in solids since it leads to formation of layers with different properties in glasses. In initial quartz glasses, new phases of mNa2O-SiO2 and mLi2O-nSiO2 were produced at different depths from the surface. It was found that these ion.synthesized glasses and glasses of the same elemntal composition obtained by conventional methods are structurally similar. The effect of ion beam-stimulated liquidation was found for the first time in ion-implanted glasses. The size of liquidation microphases is in the range10-200nm.
Keywords: phase formation; glasses; ion synthesis
  • Lecture (Conference)
    Surface and Coatings Technology 158-159 (2002) 508-512
  • Contribution to external collection
    Surface and Coatings Technology 158-159 (2002) 508-512

Publ.-Id: 5079 - Permalink


Novel tumourtropic ester derivatives of 99mTc(V)-mesoDMSA with low affinity for bone tissue
Seifert, S.; Syhre, R.; Spies, H.; Johannsen, B.;
Starting from our previous finding that pentavalent 99m Tc(V)DMSA, a useful agent for localization of osteosarcoma and bone metastases, already loses its bone affinity when one ester group is introduced into the complex molecule we studied the impact of esterification in more detail. This paper reports on the evaluation of various 99mTc(V)DMS ester complexes in rats and tumour-bearing nude mice with regard to their tumour retention and improvement of the tumour to tissue ratios. The distribution patterns of the complexes A ([ 99m TcO(DMSA) 2]-), B ([99mTcO(DMSA/DMSEt)]-) and C ([99mTcO(DMSEt)2]-) are gradually changed with the number of ester groups in the anionic complex. However, the asymmetric diester complex D ([99mTcO(DMSA/DMSEt2)]-) is very slowly cleared, especially from the blood of nude mice. Moreover, this complex differs significantly from the symmetric complex C in its elimination behaviour from the liver and kidneys. The tumour uptake is maintained with complexes which contain one or two non-hydrolyzable ester functions. Preliminary biodistribution studies of the monoethyl and diethyl ester complexes B, C, and D in comparison with A in tumour-bearing nude mice showed similar uptake into the human squamous cell carcinoma (FaDu) as well as into the human colonic cell carcinoma (HT29) of nude mice. The low bone accumulation of B, C and D results in excellent tumour to bone ratios, e.g. approx. 3:1 for the ester complex B compared to approx. 1:2 for complex A. Differences were observed in the accumulation and elimination behaviour of the complexes A and B in various bone structures of rats. The age-dependent uptake of A and B was compared in long bone (femur) and in cranial bone of rats. The results suggest that ester-functionalized 99mTc(V)DMS complexes and their 188Re analogues may be superior to 99mTc(V)/188Re(V)DMSA in diagnostic and therapeutic nuclear medicine.
  • Nuclear Medicine Communications (2003) 24: 1175-1183

Publ.-Id: 5078 - Permalink


Investigation of aperture SNOM levers fabricated by FIB patterning and wet chemical etching
Renger, J.; Grafström, S.; Eng, L.; Schmidt, B.; Bischoff, L.;
Aperture probes for near-field optical microscopy are currently limited in tip geometry due to the etching process involved in the production of fiber tips [1] or the principal crystallographic planes when dealing with silicon-based SNOM tips integrated into a microfabricated cantilever [2]. Also, the reproducibility in tip production is still small. Therefore, a novel concept for the micofabrication of aperture SNOM probes with user-defined shapes and aperture sizes has been proposed by Schmidt, Bischoff and Eng [3]. These tips are directly incorporated into a cantilever which properties may be varied in a broad range. We believe that the SNOM-levers will offer novel applications in biology and material science.
To produce such cantilevers with an integrated optical tip, focused ion beam (FIB) 3D-patterning was used to define both the tip and cantilever as a monolithic structure in the silicon substrate. By varying the ion dose of implanted gallium ions we are able to construct levers with various force constants at small cantilever lengths of < 20 µm. A point-like FIB irradiation of Si, leading to hole erosion by sputtering, allows us to produce tips having a truncated Gaussian shape of high aspect ratio. Various forms are possible, including open and closed tips. This method allows to achieve hollow tips of less than 100 nm in diameter. The cantilever and tip structure predefined by Ga+-FIB implantation and sputtering is subsequently etched in KOH:H2O solutions to remove the surrounding silicon, not irradiated by the FIB. Ga-doped areas are more resistant against the etchant during the wet anisotropic etching process so that the SNOM lever is finally formed as a free-standing structure.
We present investigations of the mechanical and optical properties of the levers and the tips, respectively. The micromechanical cantilever structures with lateral dimensions of a few microns and a thickness of only some tens of nanometers were tested interferometrically to deduce their lowest mechanical resonance frequency which was found to be in the range of 0.5 to 5 MHz, depending on their lateral dimensions and the cross section shape. The corresponding spring constants range from 0.01 to ~1 N/m offering a lot of new applications. For studying the optical properties the light transmission through as-constructed apertures within a flat extended support was investigated for different apertures and cone sizes.


References
[1] R. Stöckle, C. Fokas, V. Deckert, B Sick, B. Hecht and U.P. Wild, Appl. Phys. Lett. 75, 160 (1999)
[2] Witec GmbH, Ulm (Germany), http://www.witec.de/snom.html
[3] Patentanmeldung 100 57 656.7 (21.11.2000)
[4] B. Schmidt, L. Bischoff, and J. Teichert, Sensors and Actuators A 61, 369 (1997)
  • Lecture (Conference)
    7th International Conference on Near Field Optics and Related Techniques, August 11-15, 2002, Rochester, NY, USA

Publ.-Id: 5077 - Permalink


Synthesis and biological activity of ‚3+1' mixed ligand (3-thiapentane-1,5-dithiolato)oxorhenium(V) complexes bearing 1,2,3,4-tetrahydro(iso)quinoline and quinoline
Zablotskaya, A.; Segal, I.; Germane, S.; Shestakova, I.; Lukevics, E.; Knieß, T.; Spies, H.;
‚3+1' mixed ligand oxorhenium(V) complexes of the type ReO(SSS)S(CH2)nHetN have been synthesized by the reaction of the preliminary prepared tetrahydro(iso)quinolyl containing monodentate ligands with chloro(3-thiapentate-1,5-dithiolato)oxorhenium(V). The newly synthesized ligands and complexes were characterized by elemental analysis, IR, 1H, and 13C NMR spectroscopy. Metal complexes were screened for psychotropic and antitumour activities and receptor-binding properties and were found to be active in this respect.
Keywords: oxorhenium complexes; tetrahydroquinoline; tetrahydroisoquinoline; quinoline; 3-thiapentane-1,5-dithiolate; psychotropic activity; antitumour activity; receptor-binding porperties; NMR spectra, toxicity
  • Applied Organometallic Chemistry 16 (2002) 550-555

Publ.-Id: 5076 - Permalink


Raman spectroscopy of germanium nanoparticles in amorphous silicon oxide films
Wellner, A.; Pillard, V.; Bonafos, C.; Carrada, M.; Claverie, A.; Stegemann, K. H.; Schmidt, B.;
Silicon and germanium nanocrystals display unusual and fascinating properties such as visible photoluminescence. These properties have led to a tremendous amount of research in nanostructures as they create new possibilities for applications in optoelectronics and microelectronics. One of these potential applications is the use of nanocrystals as storage elements within the gate oxide of memory devices. One of the major challenges for the generation of such devices is the fine-tuning of the nanocrystals in terms of size and position. Usually transmission electron microscopy is employed for obtaining this information. We have explored Raman spectroscopy as an alternative non-destructive and less time consuming tool for the characterisation of germanium nanocrystals.
The germanium nanocrystals were produced by ion implantation into a 500 nm thick silica layer followed by thermal annealing at various temperatures and for different durations. Raman spectroscopy was performed at room temperature using excitation wavelengths ranging from 468 nm to 530 nm. The Raman spectra were obtained in the 001(110,110)001 backscattering configuration with respect to the silicon substrate. This orientation of the silicon substrate is crucial since the second order Raman peak of silicon at about 300 cm-1 is supressed and does not mask the Raman peak arising from the germanium nanoparticles. Samples annealed for one hour at 700°C to 800°C show a broad band centred at 280 to 300 cm-1 similar to amorphous germanium, whereas samples annealed at higher temperatures always exhibited sharp well defined peaks which indicate crystalline material. TEM measurements confirmed the presence of Ge nanocrystals. The Raman peak position was found to depend on the annealing time. Samples annealed at 950°C for 15 min exhibited a peak at 298 cm-1 whereas samples annealed for 1 hour displayed a peak at 303.5 cm-1. The Raman peak position of a Ge single crystal was measured at 300 cm-1; therefore the peaks are shifted. They were also found to be asymmetrically broadened in comparison to bulk germanium. A negative shift and broadening of the Raman peak is characteristic of a phonon confinement effect and tensile stress while a positive shift indicates the presence of compressive stress. Accordingly we have analysed the spectra in terms of both, stress effects and phonon confinement. Our model uses an improved description of the phonon dispersion and produces excellent results for silicon nanocrystals. The mean cluster size was measured by TEM. Ge nanocrystals grown for 15 min at 950°C are about 6nm in diameter and experience tensile stress of 200 MPa. Nanocrystals grown for 60 min have a mean diameter of 14 nm and are under compressive stress of about 800 MPa.
Finally Raman interferometry experiments are planned to measure the spatial organization of a nanocrystal plane within an ultrathin oxide layer. This technique has already been used as a powerful method to probe local order (disorder) in quantum wells and dots.
  • Lecture (Conference)
    Int. Conf. on Superlattices, Nano-Structures and Nano-Devices, July 22-26, 2002, Toulouse, France

Publ.-Id: 5075 - Permalink


Impact of ambient atmosphere on as-implanted amorphous insulating layers
Schmidt, B.; Grambole, D.; Herrmann, F.;
Low energy ion implantation into SiO2 causes a damaged near surface layer. The high number of broken bonds due to displaced Si and O atoms forms in the glassy network pathes, which are open for diffusion and in which moisture from the ambient can be absorbed. Therefore chemical reactions of the implanted impurities with hydrogen and oxygen must be expected during subsequent annealing. Water absorption in heavy ion-damaged SiO2 layers has been studied by hydrogen depth profiling using the Nuclear Reaction Analysis (NRA). SiO2 was implanted with ions of different mass (Si, Ge, Sn) and doses in the range 1013...1016 cm-2. H depth profiles were measured after storage under clean room conditions and after additional wet cleaning, as well as after annealing. At the surface and in the region of the implanted profile, the H concentration reaches 5-10 at% after storage and increases during wet chemical cleaning up to 12 at% for implantation doses >1x1014 cm-2.
Keywords: SiO2, ion implantation, water absorption
  • Nuclear Instruments and Methods B 191 (2002) 482-486

Publ.-Id: 5074 - Permalink


Radiation induced defects in SiO2
Fitting, H.-J.; Trukhin, A. N.; Barfels, T.; Schmidt, B.; von Czarnowski, A.;
Cathodoexcitation in the study of silicon dioxide films on silicon substrate has evealed many interesting properties of luminescence centers. The main luminescent enters in SiO2 films are the red luminescence R (1.85 eV) of the non-bridging oxygen hole enter (NBOHC) and the twofold- coordinated (divalent) silicon with a blue B (2.7 eV) and a UV band (4.4 eV). Especially the latter ones are produced under irradiation, but from existing precursors.
Morimoto et al. concluded that the blue luminescence (B) is related to interstitial oxygen. Therefore, in the present paper we want to compare a direct oxygen implantation with a direct silicon implantation into SiO2 layers producing an oxygen surplus in the first case and an oxygen deficit in the second case, respectively.
Thermally grown SiO2 layers of thicknesses d = 500 nm have been implanted by Si+ and O+ ions of energy 150 and 100 keV, respectively, and a uniform implantation dose of Di = 5 . 1016 ions/cm2. Thus the implantation profiles are expected with a concentration maximum of nearly 4 at% at the half depth dm 250 nm of the SiO2 layers. After thermal annealing to 900 oC for 1 hour in vacuum the typical red and blue luminescence bands are increased.
Generally we may state: Implanting oxygen increases the red band R (? =650 nm) but does not affect the blue band B (? = 460 nm). Silicon surplus increases the amplitude of the blue (B) luminescence, but reduces the amplitude of the red (R) one.
Studying the irradiation dose dependence of these blue and red bands we have established defect kinetics in SiO2 including six main defects and precursors, so the non-bridging oxygen hole center (NBOHC) for the red luminescence, the twofold coordinated silicon as the oxygen deficient center ODC2 for the blue luminescence and the mobile oxygen as the main transmitter between precursors and the radiation induced defects. The kinetics is described by a set of eight differential equations which predict the dose dependence of the cathodoluminescence. The experimental CL dose dependences of the red (R) and blue (B) luminescence intensities are in a good agreement with the calculated ones according to the model.
  • Lecture (Conference)
    9th Europhysical Conference on Defects in Insulating Materials EURODIM 2002. June 30 - July 5, 2002. Wroclaw, Poland

Publ.-Id: 5073 - Permalink


Formation and structure of Sn nanoclusters in thin SiO2 films
Spiga, S.; Franciulli, M.; Ferretti, N.; Boscherini, F.; Schmidt, B.;
The increasing interest in low-dimensional materials is based on both fundamental and technological issues. Recently, Sn nanoclusters have been proposed as potential candidates for charge storage. However, a better understanding of formation and properties of nanocrystals is required for their technological applications. Sn nanoclusters have been formed in thin SiO2 films by ion implantation (80 KeV, 1x1016 cm-2) and annealing at different temperatures. The high brilliance of third generation sources at high energies makes it feasible to perform Sn K edge spectroscopy on these systems in which the Sn concentration is at the detection limit for XAS. In particular, we have used fluorescence - detected XAS at the GILDA beamline of the ESRF to probe the local structure of the implanted Sn atoms. Complementary structural information have been obtained by 119Sn Conversion Electron Mössbauer Spectroscopy (CEMS) and Transmission Electron Microscopy (TEM). XAS has provided unique information on the local environment of Sn nanoclusters in the SiO2 with respect to different annealing conditions. Sn ions are fully oxidized in the as-implanted state, while after annealing also the ß-Sn phase is found.
By comparing XAS data with CEMS and TEM we concluded that the metallic ß-Sn phase is related to the bigger crystalline nanoclusters formed after annealing, while the oxidized Sn is present in the matrix as dissolved SnO or as small oxide precipitates.
  • Lecture (Conference)
    E-MRS-2002, June 18-21, 2002 Strasbourg, France

Publ.-Id: 5072 - Permalink


EXAFS and CEMS investigation of the local structure of Sn implanted SiO2
Spiga, S.; Franciulli, M.; Montavan, R.; Boscherini, F.; Ferretti, N.; Schmidt, B.; Grötzschel, R.; Mücklich, A.;
The ion beam synthesis (IBS) of nanoparticles in amorphous matrix has received great attention in the last years as a promising technique for nanocrystal formation in insulating layers. Metallic and semiconducting nanoclusters embedded in SiO2 have been recognized as potential materials for the production of memory devices and optoelectronic components. Sn nanoclusters has been proposed, together with Si and Ge nanoclusters, as potential candidates for charge storage. One of the critical point for the technological application of nanocrystals is that they must be isolated and similar in size. In addition, their position and spacing, their structure and stability after formation should be controllable.
In this work we address the formation of Sn nanoclusters by ion implantation and thermal treatments in thin SiO2 films (< 100 nm), where the cluster formation mechanism is not well understood yet. The local structure of Sn in SiO2 has been addressed by 119 Sn CEMS and EXAFS. EXAFS and CEMS analyses provided unique information on the local atomic and electronic environment of Sn in SiO2.
Sn 2+ and Sn 4+ oxidized phases or the Sn 0 metallic phase have been found under different annealing conditions. By comparing these data with TEM and RBS analyses we concluded that metallic beta-Sn phase is related to big Sn crystalline clusters formed after annealing, while the oxidized Sn is due to atoms dissolved in the matrix or in small precipitates of SnO2 or SnOx. In addition, the formation mechanism of Sn nanoclusters may be influenced by H2O absorption in the highly damaged SiO2 film after ion implantation, and by in-diffusion of moisture during the annealing. Low energy ion implantation (10–15 keV) showed the possibility for a better control of the cluster size distribution and positioning inside the SiO2 films. This may be relevant for the application of this kind of nanoclusters for charge storage applications in memory devices. Preliminary electrical characterization confirmed the memory effects in MOS capacitors with Sn nanocrystals embedded in the gate oxide.
  • Lecture (Conference)
    Silicon Workshop, February 6-8, 2002, INFM Sede, Genova, Italy

Publ.-Id: 5071 - Permalink


Modeling and measurements of two-phase Pb-Sn alloy solidification in an external magnetic field
Nikrityuk, P. A.; Eckert, K.; Grundmann, R.; Willers, B.; Eckert, S.;
The aim of this work is to predict the influence of the external magnetic field on the solidification process of two-component material. Based on the continuum model of two-phase flow a mathematical model for the directional solidification of a binary alloy in an applied magnetic field is presented. The model includes mass, momentum, energy and species conservation equations and additional relationships describing the temperature-solute coupling. The geometry under study is a cylindrical mold with adiabatic walls and cooled bottom. The macroscale transport in the solidification of alloys is governed by the progress of the two-phase mushy zone which is treated by means of a porous medium approach.
The results of calculation are compared with experimental data. The experiments as well as the calculations showed that by rotation of the liquid phase caused by the Lorentz force, the solidifcation front has a non-linear surface.
Keywords: metallic alloys, Pb-Sn, solidification, convection, rotating magnetic field
  • Journal of Thermal Science, Vol. 12, 2003, pp. 357-362

Publ.-Id: 5070 - Permalink


CL and EDX depth profiling in Ge-implanted SiO2 layers
Fitting, H. J.; Barfels, T.; Schmidt, B.; von Czarnowski, A.;
The lateral resolution of energy dispersive X-ray analysis (EDX) and cathodoluminescence (CL) mapping in a scanning electron microscope (SEM) can be extended to depth analysis by means of varying the electron beam energy, Eo, and thus the excitation range R(E).Comparing the Ge atom profiles nGe(x) shift with those of the CL center profiles nCL(x) after thermal annealing a much smaller displacement of the Ge atom concentration with respect to the profile shift of the luminescent centers towards the surface was detected.
  • Lecture (Conference)
    Proceedings of the 15th International Congress on Electron Microscopy, Vol. 1: Physical, Materials and Earth Sciences, pp. 797-798, September 1-6, 2002, Durban, South Africa
  • Contribution to proceedings
    Proceedings of the 15th International Congress on Electron Microscopy, Vol. 1: Physical, Materials and Earth Sciences, pp. 797-798, September 1-6, 2002, Durban, South Africa

Publ.-Id: 5069 - Permalink


Cathodoluminescence of Ge+, Si+, and O+ implanted SiO2 layers and the role of mobile oxygen in defect transformation
Fitting, H.-J.; Barfels, T.; Trukhin, A. N.; Schmidt, B.; Gulans, A.; von Czarnowski, A.;
Thermally grown SiO2 layers of thickness d = 500 nm have been implanted by Ge+, Si+, and O+ ions of energy 350, 150, and 100 keV, respectively, and a uniform implantation dose of Di = 5E16 ions/cm2. Thus the implantation profiles are expected with a concentration maximum of nearly 4 at% at the half-depth dm = 250 nm of the SiO2 layers. After thermal annealing to 900 °C for 1 h in dry nitrogen or vacuum the typical violet luminescence band (at 400 nm) of the Ge+ implanted centers is increased more than 200-fold and the Ge luminescent center depth profile is shifted from about 250 to 170 nm towards the surface as determined by cathodoluminescence (CL) depth profiling. Implanting oxygen increases the red band ( at 650 nm) but does not affect the blue band (at 460 nm). Silion surplus increases the amplitude of the blue (B) luminescence, but reduces the amplitude of the red (R) one.
Studying the irradiation dose dependence of these blue and red bands we have established defect kinetics in SiO2 including six main defects and precursors, including the non-bridging oxygen hole center for the red luminescence, the twofold-coordinated silicon as the oxygen deficient center ODC(2) for the blue luminescence and the mobile oxygen as the main transmitter between precursors and the radiation induced defects. The kinetics are described by a set of eight differential equations which predict the dose dependence of the CL.
  • Journal of Non-Crystalline Solids 303 (2002) 218-231

Publ.-Id: 5068 - Permalink


Catohodoluminescence Depth Profiling in SiO2:Ge Layers
Barfels, T.; Schmidt, B.; von Czarnowski, A.; Fitting, H.-J.;
For investigation of luminescent center profile cathodoluminescence measurements are used under variation of the primary electron energy Eo = 2..30 keV. Applying a constant incident power regime (Eo x Io = const), the depth profiles of luminescent centers are deduced from the range of the electron energy transfer profiles dE/dx.
Thermally grown SiO2 layers of thickness d = 500 nm have been implanted by Ge+-ions of energy 350 keV and doses (0.5-5)E16 ion/cm2. Thus Ge profiles with a concentration maximum (0.4-4)at% at the depth of dm = 240 nm are expected. Afterwards the layers have been partially annealed up to Ta = 1100 °C for one hour in dry nitrogen. After thermal annealing, not only the typical violet luminescence (at 400 nm) of the Ge centers is strongly increased but also the luminescence center profiles are shifted from about 250 nm to 170 nm depth towards the surface. This process should be described by Ge diffusion processes, precipitation and finally Ge nanocluster formation. Additionally, a Ge surface layer is piled-up extending to a depth of roughly 25 nm.
Keywords: Cathodoluminescence; SiO2; Ge implantation; depth profiling, thermal annealing
  • Microchim. Acta 139 (2002) 11-16

Publ.-Id: 5067 - Permalink


Process Simulations on Size and Location Control of Si Nanocrystals at Ion Beam Synthesis in Thin Gate Oxides
Müller, T.; Heinig, K.-H.; Möller, W.;
Silicon nanocrystal (NC) based nonvolatile memories are currently an active subject of study. In order to synthesize NCs in the gate oxide, ion implantation followed by annealing is the most compatible method with the current CMOS technology. Although, the process of phase separation during annealing and the influence of the very close Si/SiO2 interface is not completely understood.
In this contribution, binary collision simulations of highfluence Si implantation are combined with kinetic 3D lattice Monte Carlo simulations of NC formation by phase separation during annealing. For low concentrations of implanted Si, NCs form via nucleation, growth and Ostwald ripening, whereas for high concentrations Si separates from SiO2 by spinodal decomposition. In both regimes, the close Si/SiO2 interface has substantial influence on the NC formation. Specifically, it leads to a self-adjusted NC-free tunneling oxide at the interface, which has the just right thickness (2 .. 4 nm) to act as barrier for NC charging by direct electron tunneling. However, the evolution of NCs during annealing differs in the two regimes. It is shown that a constant tunneling distance and a constant mean NC diameter can be achieved in the nucleation regime at high NC densities ( > 1x1012 cm-2). This is not the case for spinodal decomposition. Thus, it is predicted that the technological demands on the NC synthesis for nonvolatile memories are fulfilled best in the nucleation regime.
  • Lecture (Conference)
    International Workshop on Nanostructures for Electronics and Optics NEOP, October 6 - 9, 2002, Dresden, Germany

Publ.-Id: 5066 - Permalink


Nanocluster Formation by Low Energy Si Implantation - Basic Mechanisms II
Müller, T.; Heinig, K.-H.;
[no abstract]
  • Lecture (others)
    Project Meeting of the European Growth Project NEON, January 17-21, 2002, Athens, Greece

Publ.-Id: 5065 - Permalink


Competing influence of damage buildup and lattice vibrations on the shape of ion range profiles in Si
Posselt, M.; Mäder, M.; Grötzschel, R.; Behar, M.;
Phosphorus depth profiles in Si obtained by 140 keV implantation into the [001] axial channel direction and into a direction 70 off axis are investigated at two different doses (5x1013 and 5x1015 cm-2)for implantation temperatures of 350 0C and room temperature (RT). At low dose and at channeling incidence, the penetration depth of implanted ions is higher at RT than at 350 0C This behavior is caused by the dechanneling of lattice vibrations. At high dose, the temperature dependence of the shape of the implantation profiles is opposite that at low dose, due to the enhanced dechanneling by defect accumulation at RT. On the other hand, damage buildup does not occur at elevated temperature. The temperature dependence of the profiles obtained by tilted implantation is much less than for the channeled implants. The P profiles measured can be reproduced very well by atomistic simulations which take into account both lattice vibrations and defect accumulation during ion bombardment.
Keywords: ion implantation, channeling, radiation damage, thermal vibrations, computer simulation
  • Applied Physics Letters 83 (2003) 545

Publ.-Id: 5064 - Permalink


Experimental and simulation studies of the channeling phenomena for high energy implantation
Guo, B. N.; Variam, N.; Jeong, U.; Mehta, S.; Posselt, M.; Lebedev, A.;
As device geometries scale, there is an increasing trend for high energy CMOS well implants to migrate to small incidence angles (near zero degree), and therefore avoid the well spacing limitations caused by shadowing and encroachments of the ion beam by the photoresist mask. However, this transition results in the replacement of traditional de-channeling profiles by channeled dopant profiles. From a device engineering perspective, accurate models of channeled profiles are becoming more important. The degree of channeling is dependent on the acceptance angle, incident angle, dopant species, energy, dose and extent of damage induced in the crystal. This paper discusses both experimental and simulation results that shed light on the contribution of these factors. In addition, the control requirements on ion implantation parameters from a channeling perspective will also be discussed.
Keywords: ion implantation, semiconductor technology, channeling
  • Lecture (Conference)
    14th International Conference on Ion Implantation Technology (IIT2002), Taos, USA, September 22-27, 2002
  • Contribution to external collection
    IEEE Proceedings of the 14th Int. Conf. on Ion Implantation Technology, IIT 2002, Taos, NM, USA, Sept. 22-27,IEEE, Piscataway, USA, 2003, IEEE Publications EX505-TBR,p.131

Publ.-Id: 5063 - Permalink


Characterizing the Kinetics of Heterogeneous Exothermic Reactions
Biskup, K.; Bothe, H.; Hessel, G.; Kryk, H.; Schmitt, W.; Tefera, N.;
The catalytic hydrogenation of aromatic nitro compounds is a complex exothermic process influenced by the competing effects of the mass transfer and the kinetics. In reaction calorimeters, several methods were applied to determine the parameters of kinetics and mass transfer under different process conditions. It was found that a bad quality of the aromatic nitro compound and disadvantageous process conditions can cause an accumulation of intermediates which probably deactivate the catalyst and lead to low reaction rates.
  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-268 Juli 1999, 71-80

Publ.-Id: 5061 - Permalink


Calorimetric Investigation of the Formation of Grignard Reagents
Hessel, G.; Hulzer, G.; Palitzsch, P.; Schmitt, W.; Tefera, N.; Weiss, F.-P.;
A novel technique for the determination of the thermodynamic and kinetic parameters of the Grignard reagent formation is described. Instead of operating under the spontaneous exothermic initiation of Grignard reactions, the calorimetric measurement was carried out in a closed reactor pressure vessel. In that way, the increase of the reactor temperature and the pressure can be used for detecting the initiation of the Grignard-reagent formation as shown by comparison with the on-line profiles of the concentration of the Grignard reagent measured by FTIR-spectroscopy simultaneously. Results showed that the molar reaction enthalpy of a Grignard reagent could be determined by a closed reactor vessel more accurately than under reflux conditions.
  • Contribution to HZDR-Annual report
    Wissenschaftlich-Technische Berichte / Forschungszentrum Rossendorf; FZR-284 Februar 2000, 29-34

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Publ.-Id: 5058 - Permalink


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