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  • 2000-2004  (9)
  • 1990-1994  (20)
  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 944-950 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photoionization mass spectrometry experiments, performed on an extensive size range of aluminum clusters produced by laser vaporization technique, are reported. Ionization potential values are deduced from individual photoionization efficiency curves for the smaller AlN clusters (N=36–112). Our results confirm and complete those previously published. The mass spectra of larger clusters (N≈250–1400) reveal a regular signal oscillation. Several additional experiments give proof that this striking pattern originates from size-dependent ionization threshold effects. This structure exhibits exact periodicity as a function of N1/3 or Ne1/3 (Ne the number of valence electrons).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 1793-1809 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Absorption spectra of lithium clusters containing four to eight atoms have been measured using depletion spectroscopy. Few intense transitions are observed, always located in two predominant spectral regions, ∼480 and 680 nm. The spectra are interpreted using ab initio configuration interaction (CI) calculations, leading to a complete characterization of the excited states and a straightforward determination of the ground state geometrical structure. Intense transitions are explained by interference effects in the transition amplitude and symmetry considerations. Comparisons with semiclassical models, in which an effective mass correction is introduced, are also presented.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 4030-4038 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report here the first experimental observation of bound–bound transitions between the ground X 2Σ+g and excited 1 2Πu states of Na+2. The basis of our experiment is to study doubly excited Rydberg states of Na2 by preparing a well-defined nd 1Λg singly excited Rydberg state of Na2 and then, by exciting the Na+2 core with a tunable laser. In this paper, we show that the ionic transitions may be directly deduced from the doubly excited Rydberg states spectra [C. Bordas, J. L. Vialle, and M. Broyer (submitted)]. We demonstrate that this technique is one of the most powerful to study the excited states of diatomic ions which are not predissociated. A detailed spectroscopic analysis of the 1 2Πu state has been performed and the results are compared with the more recent ab initio and pseudo- (or model-) potential calculations.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 2332-2336 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The observation of some new bands assigned to the Na3 X–A system has allowed a rather complete theoretical treatment of the A electronic state. It exhibits large quadratic Jahn–Teller interaction giving rise for the lower levels to a localization in a hindered pseudorotation well. The band positions and intensities are in agreement with the values Es=1847 cm−1 and Eloc=196 cm−1, respectively for the stabilization and pseudorotation barrier energies.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 754-755 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Under usual experimental conditions, aluminum clusters have specific geometric arrangement. By heating the nozzle, we obtain melted aluminum clusters, and a new periodicity appears in mass spectra, which corresponds to electronic shells up to 1800 electrons.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-198X
    Keywords: Growth hormone ; Growth hormone-binding protein ; Chronic renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Plasma growth hormone-binding protein (GH-BP) activity was evaluated in two groups of prepubertal children with chronic renal failure (CRF) who had been treated with recombinant human GH (rhGH). Group 1 consisted of eight children (mean chronological age 10.8 years) with advanced renal failure; group 2 consisted of nine children (mean chronological age 6 years) presenting with end-stage renal disease, who were on dialysis. Before treatment the specific binding of (125I)hGH to highaffinity GH-BP was low in the two groups (group 1, 17.3±1.6% of radioactivity; group 2, 14.2±1.4%) compared with the mean value obtained in normal prepubertal children (24.8±1.7%). No significant changes in GH-BP activity were found during the 1st year of GH therapy, although growth velocity and plasma levels of insulin-like growth factor-I increased significantly in both groups. The low GH-binding activity found in children with CRF supports the state of GH resistance. The reason for the absence of a GH-BP response to GH therapy has to be clarified.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-198X
    Keywords: Anaemia ; Chronic renal failure ; Haemodialysis ; Haemoglobin ; Recombinant human erythropoietin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This was an open-label multicentre study of recombinant human erythropoietin (r-HuEPO) in 116 children aged 6 months to 20 years with anaemia of chronic renal failure undergoing haemodialysis. Haemoglobin concentration at entry ranged from 3.4 to 9.5 g/dl. r-HuEPO was given intravenously two or three times per week, the starting dose being 75 U/kg per week. This was subsequently titrated in steps of 75 U/kg per week with the goal of increasing haemoglobin concentration at the rate of 1 g/dl per 4 weeks into the range 9.6–11.2 g/dl (6–7 mmol/l), with treatment then continued for up to 1 year with the aim of maintaining the haemoglobin concentration within the target range. Of the 115 children in whom efficacy could be evaluated, 93 (81%) achieved the target haemoglobin and a further 6 had a rise in haemoglobin concentration of at least 2 g/dl. At 52 weeks, the median maintenance dose for children〈30 kg was 225 U/kg per week, compared with 107 U/kg per week for children ≥30 kg. Analysis suggested that 150 U/kg per week would have been a more appropriate starting dose. The mean transfusion requirement fell from 8.9 to 0.7 units/patient per year. Of the 22 patients who failed to reach the target, 15 went on to transplantation and left the study prematurely. Sub-group analysis showed that similar doses lead to similar rates of rise in haemoglobin regardless of the severity of the original anaemia. Assessment of quality of life suggested that this may have improved with r-HuEPO. Twenty-four children needed initiation or increase of anti-hypertensive medication, suggesting that successful r-HuEPO therapy was associated with a tendency towards increased blood pressure. However, there were no significant mean changes in blood pressure, suggesting that the problem was successfully addressed by the changes in treatment. No child developed anti-r-HuEPO antibodies. The overall safety profile was excellent and no new r-HuEPO toxicities were identified in children.
    Type of Medium: Electronic Resource
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