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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 3088-3097 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: (C60)nCq+ cationic clusters are produced in a laser vaporization source by quenching the vapors from C60 and graphite targets. They are analyzed in the gas phase by abundance and photofragmentation time-of-flight mass spectroscopy. Among the large number of expected isomers, the present experiments give evidence for the stability of special arrangements that may result from the attachment of preformed carbon rings to the fullerene cage. The particular case of C10 will be discussed, considering the results obtained on complexes with one, two or even three C60 molecules. This study reveals that the incorporation of large molecules into carbon cages could be an essential mechanism during the growth process of larger fullerenes and that the polymerization of C60 molecules is promoted by carbon links involving a single atom or a dimer. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 1970-1973 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We measured the electric polarizability of NaNC60 (N=1–34) molecules. The experimental values can be interpreted by the existence of a permanent electric dipole for every size. This cannot be explained by a metal shell around the C60, but this is in agreement with a sodium cluster bound to the C60. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8436-8445 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: (C60)nSim+ cationic clusters are produced in a laser vaporization source by quenching the vapors from two independent C60 and silicon targets. They are analyzed in the gas phase by abundance and photofragmentation time-of-flight mass spectroscopy. For complexes containing only one C60 molecule, silicon is unlikely to wet the fullerene surface. Mass spectroscopic studies are rather in favor of a three-dimensional growth of silicon clusters weakly bound to C60. For larger systems, one can distinguish two classes of silicon atoms: most of them group in the form of compact islands (or clusters) and some others are directly involved in the linkage of C60 molecules. Particular geometric structures for the stable polymers (C60Si)n−2(C60)2+, (C60Si)n−1C60+, and (C60Si)n+ are postulated. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-198X
    Keywords: Key words Blood transfusion ; Cyclosporine ; Renal transplantation ; Cytotoxic antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Pretransplant transfusions were repeatedly shown to be associated with improved graft survival in the ”pre-cyclosporine era,” and have recently been shown to be beneficial in patients on modern immunosuppressive regimes. In an attempt to improve this transfusion effect and minimize the potential development of cytotoxic antibodies, we have given these transfusions, with concomitant cyclosporine cover, prior to transplantation. Ninety-two renal transplantations were performed in 91 children in the study group (group 1) and all received pretransplant transfusions with cyclosporine cover. Results were compared with a preceding group of 102 children (104 transplantations) who had received pretransplant transfusions without cyclosporine cover (group 2). There were 70 cadaver and 22 living-related donor (LRD) transplants in group 1, and 88 cadaver and 16 LRD transplants in group 2. Graft survival rates (1- and 5-year) for cadaver transplantation were 96% and 90% in group 1 compared with 78% and 64% in group 2 (P=0.001). For LRD transplantation, these figures were 95% and 87% in group 1 and 81% and 69% in group 2. There was no difference between the two groups in terms of age at transplantation, sex, donor age, HLA-A, -B, -DR mismatches, or cold and warm ischemia times. All cadaver graft recipients received quadruple, sequential immunosuppression post transplant. However, 9 patients in group 1 were changed to tacrolimus for recurrent rejection episodes. No patient developed persistent lymphocytotoxic antibodies post transfusion or side effects of cyclosporine. Cyclosporine can be safely given with whole blood prior to transplantation with no adverse effect and no sensitization. Graft survival was significantly improved in this group of patients and graft loss due to rejection was exceptional. This effect should be further evaluated in prospective studies.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric nephrology 14 (2000), S. 523-524 
    ISSN: 1432-198X
    Keywords: Key words Renal transplant ; Altruistic donor ; Ethics ; Living non-related donor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-6079
    Keywords: PACS. 33.15.Kr Electric and magnetic moments (and derivatives), polarizability, and magnetic susceptibility - 33.55.Be Zeeman and Stark effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: A non perturbative approach is used to solve the problem of a rigid linear molecule with both a permanent dipole moment and a static dipole polarizability, in a static electric field. Eigenenergies are obtained and compared to perturbative low field and high field approximations. Analytical expressions for the orientation parameters and for the gradient of the energy are given. This non perturbative approach is applied to the simulation of beam deviation experiments in strong electric field. Results of simulations are given for inhomogeneous alkali dimers. For LiNa, the simulations are compared to experimental data. For LiK, deviation profiles have been simulated in order to prepare future experiments on this molecule.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 12 (2000), S. 147-151 
    ISSN: 1434-6079
    Keywords: PACS. 33.15.Kr Electric and magnetic moments (and derivatives), polarizability, and magnetic susceptibility - 34.70.+e Charge transfer - 61.48.+c Fullerenes and fullerene-related materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We have measured the electric dipole moment of isolated alkali-C60 molecules (with alkali = Li, Na, K, Rb, and Cs) by molecular beam deflection experiments. The dipole increases from 12.4 D for LiC60 to 21.5 D for CsC60. These results are compared to those deduced from an analytical polarizable-ion model. This comparison shows that there is a strong electron transfer from the alkali atom to the C60 cage, which is almost complete for KC60 and RbC60.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-6079
    Keywords: PACS. 36.40.-c Atomic and molecular clusters – 61.46.+w Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals – 71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons – 78.47.+p Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The effects of surface-induced lattice contraction on the size evolution of the surface plasmon resonance and of the electronic thermalization time in small silver clusters have been investigated in the framework of a mixed classical/quantum model. The increase of the conduction-electron density results in a blue-shift trend for decreasing cluster size. However this effect is counterbalanced by the increase of the dielectric function associated to the ionic-core background. Agreement with the blue-shift trend observed in experiment is recovered by introducing an inner surface skin of vanishing ionic-core polarizability having a thickness practically unchanged as compared to previous estimations. The influence of the lattice contraction on the electron dynamics is also discussed. It is shown that this influence is negligible as compared to the surface effects arising from the spillout and the inner skin of reduced ionic-core polarizability which are both responsible for a decrease of the electron thermalization time as the particle size decreases.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-6079
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. (C60) m Na n clusters are produced in a tandem laser vaporization source and analyzed by photoionization and photofragmentation time-of-flight mass spectroscopy. At low sodium coverage, the special behavior of (C60) m=1,2Na n clusters $(n\leq 6m)$ is consistent with a significant electron transfer from the first six adsorbed atoms towards each of the C60 fullerenes and an ionic-like bonding in this size range. However, the stability of the (C60)Na3 + cation is found much more pronounced than the one of (C60)Na7 + predicted to be a magic size under the hypothesis of a full charge transfer from the metal atoms to the C60 molecule. When more sodium atoms are present, metal-metal bonds tend to become preponderant and control the cluster properties. Relative to the number of sodium atoms, an odd-even alternation in their stability is explained by the high dissociation rates for even-numbered clusters. The even clusters evaporate neutral sodium atoms whereas odd ones prefer to evaporate Na2 molecules. The hypotheses for the growth of a sodium droplet that does not wet the fullerene surface or for the formation of a concentric metallic layer are discussed in the light of this study.
    Type of Medium: Electronic Resource
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