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  • Posterior cruciate ligament  (1)
  • interfaces  (1)
  • 1
    ISSN: 1573-4846
    Schlagwort(e): electron dynamics ; colloids ; metal and semiconductor nano-particles ; interfaces ; femtosecond laser spectroscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The ultrafast dynamics of photoinduced electrons in several metal and semiconductor colloidal nanoparticle systems are characterized using femtosecond laser spectroscopy. Various preparation methods are used and, in several cases, modified for making particles with long-term stability and narrow and controllable size distributions. The particle size and size distribution are determined using transmission electron microscopy and electronic absorption spectroscopy. For aqueous gold and silver colloids, spatial size confinement is found to cause substantially slower electronic relaxation due to reduction of non-equilibrium electron transport and weaker electron-phonon coupling. In gold colloids, photoejection of electrons into the liquid is observed, which is attributed to a two-photon enhanced ionization process. The effect of surfactant on the electron dynamics in CdS colloids is examined and found to be significant, substantiating the notion that electrons are dominantly trapped at the liquid-solid interface. In Ru3+-doped TiO2 colloids, the electronic decay is found to be as fast as or even faster than in undoped TiO2 and other semiconductor colloids such as CdS, suggesting that ion doping of large bandgap semiconductor colloids is not necessarily effective in lengthening the electron lifetime. In almost all cases studied, the majority of the photoinduced electrons are found to decay within a few tens of picoseconds due to non-radiative relaxation. The results are discussed in the context of the potential applications of metal and semiconductor nano-particles in areas including photocatalysis and photoelectrochemistry.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Knee surgery, sports traumatology, arthroscopy 2 (1994), S. 234-237 
    ISSN: 1433-7347
    Schlagwort(e): Meniscus ; Biomechanics ; Posterior cruciate ligament ; Meniscofemoral ligament
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Sportwissenschaft
    Notizen: Abstract The meniscofemoral ligaments (MFL) of 26 human cadaver knees were studied to determine their structural importance. The incidence of at least one MFL in each of the specimens studied was 100%, and 46% of the specimens had both MFL ligaments (Humphry and Wrisberg). Another 23% had a single Humphry ligament, and the remaining 31% had a single Wrisberg ligament. A laser micrometer system was used to measure cross-sectional shape and area. The average cross-sectional areas of the Humphry and Wrisberg ligaments were 7.8±4.7 mm2 and 6.7±4.1 mm2, respectively. In specimens with both a Humphry and Wrisberg ligament, the larger ligament area was on average 100% greater than the smaller ligament area. The average ratios of the cross sectional areas of Wrisberg and Humphry to that for the PCL within the same knee were 12.0%±7.7% and 11.9%±5.7%, respectively. The structural properties of the MFL bone-ligament-meniscus complex and the mechanical properties of the MFL midsubstance were determined by uniaxial tensile testing. The average stiffness, ultimate load, and energy absorbed at failure were, respectively, 49.0±18.4 N/mm, 297.4±141.4 N and 1125.4±735.8 N/mm. The tangent modulus between 4% and 7% strain was 355.1±234.0 MPa. Our findings suggest that the MFL is a significant biomechanical structure in the knee because of its size, stiffness, and strength.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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