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  • 1990-1994  (4)
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  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proton induced X-ray emission method in combination with a proton microprobe was applied to study the intramembranaceous ossification. As material sections of mouse embryo skulls from the 17th and 19th day of gestation were used. The morphology of the sample was examined by routine histochemical procedure performed on the sections adjacent to that irradiated by the proton microprobe. The measurements were made in line scan and raster scan mode. The concentrations of P, S, Cl, K, Ca, Fe and Zn were determined at each irradiated point. The average element concentrations were calculated for four parts of each section (bone, cartilage, mesenchymal tissue close to the bone and mesenchymal tissue in other places). The distributions of Ca and P (less markedly than Ca) concentrations almost exclusively correlate with localization of the bone while S, Cl and K concentrations show preference to the cartilage. The amount of inorganic material in flat bones of the 17-day embryo amounts to 14% of the dry mass. The material is characterized by a Ca/P ratio of bout 1.6 In the embryo 2 days older the amount of the inorganic phase is practically the same (15%) while the Ca/P ratio approaches 2. This suggests the presence of the precursor phase in the flat bone calcification. It is possible that octacalcium phosphate (Ca/P ratio equals to 1.72) is formed at the onset of the flat bone mineralization which transforms rapidly (in 2 days) to a more stable mineral (defective hydroxyapatite).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: 25.70.Cd ; 27.20.+n ; 21.10.Jx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Angular distributions of cross sections have been measured for single nucleon transfer reactions induced by 344.5 MeV12C ions on a12C target. DWBA analyses have been performed for transitions to discrete final states. Spectroscopic information has been derived and is compared with results of other studies.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: 25.40.−h
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The production ofK + mesons in proton-nucleus and deuteron-nucleus collisions is analyzed with respect to one-step nucleon-nucleon (NN → N ΛK +),Δ- nucleon (ΔN → N Λ K+) and two-step pion-nucleon (πN → K + Λ) production channels on the basis of experimental ground state momentum distributions and free on-shell production processes. Whereas forK + production in proton-nucleus reactions the secondary channelπN clearly dominates at subthreshold energies, meson and nucleon induced channels are of similar magnitude in deuteron-nucleus reactions. Contrary to nucleus-nucleus collisions theΔ induced reaction channels are found to be of minor importance. The experimental differentiation of the underlying microscopic reaction channels appears possible via differential proton —K + coincidence measurements as shown in detail by the microscopic simulations including proton rescattering.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 338 (1991), S. 187-191 
    ISSN: 1434-601X
    Keywords: 25.70.Np ; 21.60.Gx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A classical dynamical alpha-cluster model has been developed and applied in order to get inclusive energy spectra of alpha particles produced in the collision of12C +12C at the beam energy 28.7 MeV/A. Results of the calculations are compared with experimental data. The shapes of the experimental energy spectra and the absolute normalization at forward angles are approximately described without any free parameters. The model makes it possible to distinguish alpha particles originating from the compound system and from direct processes. The spectra at forward angles are dominated by projectile fragmentation processes. The cross section at larger angles is overestimated, which is partially due to emission of particles other than alpha particles in central collisions. The evaporation Hauser-Feshbach model predicts that alpha particles emitted from the compound nucleus constitute less than 26% of all emitted particles.
    Type of Medium: Electronic Resource
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