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  • 1
    Electronic Resource
    Electronic Resource
    Phase selection in interfacial reaction of Ni/amorphous Si multilayers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4313-4318 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interfacial reaction in Ni and amorphous Si (a-Si) multilayers (Ni/a-Si) has been studied. Transmission electron microscope observation was used to monitor the progress of the solid-state reaction. It was found that amorphous Ni-silicide phase [a-(Ni,Si)] is the first phase formed in the Ni and a-Si interfacial reaction. A relatively large composition range for the amorphous phase exists in these Ni/a-Si multilayers. In the as-deposited Ni/a-Si multilayers with shorter modulation period, the uniform a-(Ni,Si) phase forms at least in the composition range of 25–62 at. % Ni. These results are consistent with predictions from the calculated Gibbs free-energy diagram. The δ-Ni2Si phase is the preferred phase in the crystallization process of a-(Ni,Si) even for the equiatomic Ni/a-Si multilayers. The mechanism that controls phase selection in the Ni/a-Si interfacial reaction is discussed using nucleation theory. A nucleation control model for phase selection is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352814
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  • 2
    Electronic Resource
    Electronic Resource
    Solid-state amorphization reaction in polycrystalline Ni and amorphous Si multilayer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7217-7221 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Interdiffusion-induced solid-state amorphization reaction (SSAR) in polycrystalline Ni/amorphous Si multilayers has been studied using an in situ x-ray diffraction technique together with transmission electron microscope observations. The amorphization reaction was found to occur both on the Ni/Si interfaces in terms of a planar-layer growth model and along the grain boundaries in the Ni sublayers. Thermodynamic and kinetic interpretations for the SSAR at grain boundaries are presented and an amorphous growth model is also suggested for elucidating the SSAR in polycrystalline Ni/amorphous Si multilayers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352395
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  • 3
    Electronic Resource
    Electronic Resource
    Silicide formation in Co/amorphous Si multilayers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1578-1584 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied interfacial reactions in Co/amorphous Si(a-Si) multilayers by transmission electron microscopy. We found that an intermixed layer of amorphous cobalt silicide formed in the as-deposited state. To explain the solid-state amorphization reaction, two parameters were used. They were the thermodynamic driving force (heat of formation) and the interfacial energy. The initial amorphization reaction in Co/a-Si multilayers was thermodynamically and kinetically favored. However, the formed amorphous interlayer remained about 1 nm thick and did not grow thicker with increasing modulation period and annealing temperature. The reason for this phenomenon was that the amorphous interlayer acted as a diffusion barrier to impede the amorphization reaction in Co/a-Si multilayers. Co2Si phase was always the preferred phase in the crystallization process for different average compositions of the multilayers. The mechanism that controlled the phase selection in Co/a-Si interfacial reaction was interpreted by using the model of modified heat of formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357736
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  • 4
    Electronic Resource
    Electronic Resource
    Interdiffusion study of amorphous Ni–Si multilayer at low temperature (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2471-2474 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Little is known about the interdiffusion in the amorphous Ni–Si multilayer due to the lack of suitable experimental method. In this paper, the interdiffusion phenomena in the amorphous Ni–Si multilayer are investigated by an in situ x-ray diffraction technique. The temperature-dependent interdiffusivity obtained by monitoring the decay of the first-order modulation peak as a function of annealing time can be described in terms of the Arrhenius relation. The effective interdiffusivities can be expressed as De(T)=2.13 ×10−17 exp[−(0.61±0.02)/kBT] m2/s (423–613 K). A retarded interstitial diffusion mechanism is suggested to explain the diffusion process in the amorphous multilayer films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354684
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  • 5
    Electronic Resource
    Electronic Resource
    Stepwise C-H Cleavage of Two Methyl Groups of a Pentamethylcyclopentadienyl Ligand on a Tetraosmium Cluster (1994)
    s.l. : American Chemical Society
    Organometallics 13 (1994), S. 5113-5121 
    Details
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/om00024a062
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  • 6
    Electronic Resource
    Electronic Resource
    The anatomy of the segmental latissimus dorsi flap for reconstruction of facial paralysis (1994)
    Springer
    Surgical and radiologic anatomy 16 (1994), S. 239-243 
    Details
    ISSN: 1279-8517
    Keywords: Latissimus dorsi segmental flaps ; Transplantation ; Thoracodorsal artery ; Thoracodorsal nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le m. grand dorsal et sa vascularisation segmentaire ont été étudiés chez 68 sujets. Les artères segmentaires se distribuent régulièrement à l'intérieur du muscle, rendant possible le dessin de 4 à 6 lambeaux segmentaires. Parmi ceux-ci, le 3 ème ou le 4 ème lambeau segmentaires latéraux sont les plus fins et ont le plus long pédicule vasculaire.
    Notes: Summary The latissimus dorsi m. and its segmental vascularity were observed in 66 specimens. The segmental arteries were found to be regularly distributed within the muscle, making it possible to design 4–6 segmental flaps. Of these the lateral 3rd or 4th is the thinnest and has the longest vascular pedicle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01627677
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  • 7
    Electronic Resource
    Electronic Resource
    Calorimetric studies on the energy metabolism of an infaunal bivalve, Abra tenuis, under normoxia, hypoxia and anoxia (1993)
    Springer
    Marine biology 116 (1993), S. 73-79 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Direct calorimetry was employed to measure the energy metabolism of infaunal bivalves, Abra tenuis, collected from a tidal lagoon in the Fleet, southern England, in June 1989, at various oxygen partial pressures. A significant anaerobic component (i.e., 20% of total metabolic rate) was detected under normoxia, presumably brought about by the intermittent ventilatory activity of this bivalve under these conditions. Under hypoxia (2.3 to 10 kPa, or 11 to 48% of full air saturation), however, the energy metabolism was maintained fully aerobic; the measured heat equivalent of oxygen uptake was not significantly different from the theoretical ranges for fully aerobic catabolism. Under anoxia, the rate of heat dissipation was reduced to 5–6% of the normoxic rate of heat dissipation. This conserves energy expenditure and would thus increase resistance of A. tenuis to anoxia or emersion. Physiological compensation by A. tenuis under conditions of declining oxygen tension involved a marked increase in ventilation rate. Comparison between fed and starved individuals indicated that costly physiological processes, such as digestion, absorption and growth declined at 10 and 5 kPa and were arrested at PO 2 (oxygen partial pressure) levels below 2.3 kPa. The present study provides evidence that there are no major differences between the metabolic responses of epifaunal suspension-feeding (eg. Mytilus edulis) and infaunal deposit-feeding (eg. A. tenuis) bivalves when exposed to environmental hypoxic stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350733
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  • 8
    Electronic Resource
    Electronic Resource
    The inhibitory effect of the ventrolateral periaqueductal grey matter on neurones in the rostral ventrolateral medulla involves a relay in the medullary raphe nuclei (1993)
    Springer
    Experimental brain research 94 (1993), S. 295-300 
    Details
    ISSN: 1432-1106
    Keywords: Ventrolateral periaqueductal grey matter ; Nucleus raphe magnus ; Nucleus raphe obscurus ; Rostral ventrolateral medulla ; GABA ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Experiments were carried out in urethane-anaesthetised rats to determine whether the inhibition of neurones in the rostral ventrolateral medulla (RVLM) induced by stimulation in the ventrolateral periaqueductal grey matter (PAG), is mediated via a relay in the medullary raphe nuclei. Electrical stimulation in the ventrolateral part of the PAG (20-ms trains, 7 pulses, 5–100 μA) inhibited ongoing activity of neurones in the RVLM for periods of 10–120 ms (mean 43.6 ms). The duration of the inhibition was reduced by 51.1% after microinjection of GABA (40–160 nmol in volumes of 200–400 nl, 9/12 sites), but not 165 mM NaCl (8/8 sites) in nucleus raphe magnus (NRM) and the rostral half of nucleus raphe obscurus (NRO). In a further series of experiments, activation of neuronal perikarya at 17 sites in NRM or NRO by microinjection of d,l-homocysteic acid (5–40 nmol in volumes of 50–400 nl) inhibited ongoing activity of 9 out of 14 neurones in the RVLM, the other 5 being excited. We suggest that the inhibitory effect on neurones in the RVLM, which can be evoked by stimulation in the ventrolateral PAG, is mediated indirectly by activation of an inhibitory projection to the RVLM from NRM and the rostral half of NRO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230299
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  • 9
    Electronic Resource
    Electronic Resource
    Structural steps to oxidation of Ni(100) (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2025-2035 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper, we emphasize the temperature- and exposure-dependent development of low-energy electron diffraction patterns,measured quantitatively during oxidation of Ni(100) at 80 to 400 K. We find a strong temperature dependence in the development of LEED patterns associated with NiO. NiO(111) is favored by adsorption temperatures below 300 K, whereas a (7×7)-like structure is favored by adsorption temperatures of 300 to 400 K. Room temperature is a "crossover'' point between these two forms of the oxide. The final oxide depth is independent of adsorption temperature and, therefore, of epitaxial orientation, between 80 and 400 K. When the sample is heated in vacuum after adsorption, massive rearrangements take place above 500 K. Some of the nickel reverts to metallic nickel covered by a c(2×2) oxygen overlayer, and some forms NiO crystallites which are probably deeper than the initial oxide skin. Effectively, the parent oxide disproportionates into a less-oxygen-rich phase and a more-oxygen-rich phase. This is again independent of the orientation of the initial oxide epitaxy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458036
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  • 10
    Electronic Resource
    Electronic Resource
    Orientation dependence of intersubband absorption in AlAs/Ga1−xAlxAs X valley superlattices (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 3681-3685 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the first systematic studies of infrared absorption from interconduction subband transitions for AlAs/Ga1−xAlxAs X-valley superlattices grown in the [001], [115], [113], [112], [111], and [110] directions. In the AlAs quantum well material, electrons occupy X valleys with ellipsoidal constant energy surfaces. Due to the effective mass anisotropy of electrons in the ellipsoidal valleys, these structures can absorb normally incident radiation when the superlattice growth direction is not collinear with the principal axes of at least one of the ellipsoids (i.e., not grown along the 〈001(approximately-greater-than) directions). For both parallel and normal incidence radiation at wavelengths of 12–20 μm, peak absorption coefficients of 3000–6000 cm−1 were obtained for the [113] and [112] superlattices with well widths in the range of 30–50 A(ring) and sheet doping concentrations of 1012 cm−2. Their ability to detect normally incident light and to obtain absorption comparable to that in the GaAs/Ga1−xAlxAs superlattice detectors makes these novel structures promising for use as normal incidence infrared photodetectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352312
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