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  • 1
    Electronic Resource
    Electronic Resource
    Dihydropyridine Modulation of Voltage-Activated Calcium Channels in PC12 Cells: Effect of Pertussis Toxin Pretreatment (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In this study, we report the effect of pertussis toxin pretreatment on dihydropyridine modulation of voltage-sensitive calcium channels in PC12 cells. The rise in intracellular calcium concentration caused by potassium depolarization is not affected significantly by pertussis toxin pretreatment. Nicardipine, a dihydropyridine derivative, added either before or after potassium-induced depolarization, reduces the resultant elevation in cytosolic calcium level both in control and in pertussis toxin-treated cells. The dihydropyridine agonist Bay K 8644, when added before potassium, is able to enhance the potassium-induced spike of cytosolic calcium levels, an effect significantly reduced by pertussis toxin pretreatment. Moreover, the addition of Bay K 8644 after potassium holds the intracellular calcium concentration at a cytosolic sustained level during the slow inactivating phase of depolarization. This effect of Bay K 8644 is inhibited by nicardipine. Pertussis toxin pretreatment slightly weakens the effect of Bay K 8644 when added after potassium-induced depolarization, whereas it significantly reduces the nicardipine inhibition of cytosolic calcium rise stimulated by potassium and Bay K 8644, but not by potassium alone. In conclusion, our findings suggest that a pertussis toxin-sensitive guanine nucleotide regulatory protein could be involved in the interaction between dihydropyridine derivatives and voltage-dependent calcium channels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb01995.x
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  • 2
    Electronic Resource
    Electronic Resource
    Inhomogeneous pulsed laser melting of high-dose Ge-implanted silicon (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1833-1839 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pulsed laser melting of Si substrates implanted either with 74Ge+ ions at a nominal dose of 1017 cm−2 or 28Si+ ions at a dose of 1016 cm−2 has been investigated by time-resolved reflectivity using visible and infrared probe laser beams. In Si-implanted samples one reflectivity peak is observed during irradiation with 25 ns ruby laser pulses due to the formation and solidification of a liquid layer nucleated at the sample surface. Instead, Ge-implanted Si samples show different reflectivity spectra during irradiation in the same experimental conditions. Two reflectivity peaks have been observed in Ge-implanted samples for laser energy densities below 0.5 J/cm2 whose origin cannot be explained with the same melting dynamics as in pure Si samples. The results are explained assuming that during laser irradiation an inhomogeneous melting process occurs in Ge-implanted samples. On the basis of time-resolved reflectivity, electron microscopy, and Rutherford backscattering measurements, a melting model is suggested for the melting process of Ge-implanted samples. According to this model the liquid phase is nucleated just below the sample surface because of the reduced melting temperature caused by the Gaussian Ge implantation profile. The two reflectivity peaks originate from a time modulation of the liquid-solid ratio at the sample surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357703
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  • 3
    Electronic Resource
    Electronic Resource
    In situ and ex situ structural characterization of β-FeSi2 films epitaxially grown on Si(111) (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1224-1228 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structural properties of β-FeSi2 films grown on Si(111) are studied by means of several techniques. The films were grown in ultrahigh vacuum by solid phase epitaxy. The as-deposited Fe films were studied in situ by low energy electron diffraction (LEED) and Auger spectroscopy. Fe thicknesses were calibrated by Rutherford backscattering. The behavior of the FeMVV/SiLVV Auger peaks ratio intensity as a function of Fe thickness indicates a Stranski–Krastanov mode of growth. Annealing of the Fe layers at temperatures between 400 and 600 °C led to the β-FeSi2 formation. Sharp LEED patterns typical of the β-FeSi2 orthorhombic structure were obtained. X-ray double-crystal diffraction was carried out on a film about 200 A(ring) thick in order to determine the lattice mismatch between the β-FeSi2 and the Si(111) planes accurately. The measured value of (2.1±0.1)×10−2 unambiguously indicates that (101) epitaxy takes place only on Si(111). No elastic strain of the overlayer was evident. The full width at half maximum of the overlayer diffraction peak indicates a good crystalline quality. An upper limit for mosaic spread was determined to be about 0.05°.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351292
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  • 4
    Electronic Resource
    Electronic Resource
    Transition from relaxed to derelaxed amorphous silicon: Optical characterization (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2850-2855 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical constants of relaxed, derelaxed, and partially relaxed amorphous silicon (a-Si) in the range 0.4–0.9 μm are reported. The thermodynamical state of amorphous silicon (a-Si) has been changed either by thermal treatments or low dose ion implantation. Ellipsometry has been used to evaluate the complex refractive index for several amorphous states with enthalpy content between that of the fully relaxed and fully derelaxed a-Si. We observed a strong correlation between the electronic structure as probed by our optical measurements and the topological short-range order as probed by Raman scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354637
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  • 5
    Electronic Resource
    Electronic Resource
    Pulsed laser heating measurement of relaxation-induced melting point increase in amorphous Si (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 614-617 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The difference in the melting temperature of unrelaxed and relaxed amorphous silicon has been determined by measuring the energy density threshold for surface melting during nanosecond laser irradiation (λ=347 nm). The melting onset was detected by time-resolved reflectivity technique. Using particular samples in which a surface unrelaxed layer was generated by reimplanting a 400-nm-thick relaxed amorphous Si (a-Si) the difference in the melting temperature has been determined independently of the thermal properties of the a-Si. The melting temperature of relaxed a-Si resulted to be only 3.9% higher than that of unrelaxed a-Si, while on the basis of calorimetric data an ∼14% difference was expected. The reasons for this discrepancy are discussed. In addition a 24% increase in the product of thermal conductivity and specific heat of a-Si upon relaxation has been found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103614
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  • 6
    Electronic Resource
    Electronic Resource
    Epitaxy enhancement of β-FeSi2 grown by ion beam assisted deposition (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2102-2104 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Iron silicide layers have been grown by 200 eV Ar+ beam assisted deposition of Fe onto 〈001〉 Si single crystals maintained at high temperatures. Polycrystalline FeSi has been formed at T=400 °C while partially epitaxial β-FeSi2 was obtained after deposition at 500 °C. Samples have been analyzed by Rutherford backscattering spectroscopy and transmission electron microscopy. The main effects of the ion beam have been the reduction of the average grain size of the polycrystallites for both phases and the enhancement of the epitaxial fraction for the β-FeSi2 phase. The role of the ion beam during the formation of the iron silicides has been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109465
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  • 7
    Electronic Resource
    Electronic Resource
    Liquid phase epitaxy of cubic FeSi2 on (111) Si induced by pulsed laser irradiation (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1132-1134 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial βFeSi2 layers thermally grown on (111) Si substrates have been irradiated by 25 ns ruby laser pulses in the energy density range 0.3–0.7 J/cm2. Rutherford backscattering analyses in combination with the channeling effect have shown that the silicide stoichiometry does not change for irradiations up to an energy density of 0.5 J/cm2, while alignment of the irradiated silicide along the [111] substrate normal direction is observed. Transmission electron diffraction in the plan view configuration showed that this silicide phase has a cubic symmetry with a lattice parameter very similar to that of Si. Diffraction patterns taken along different poles of the substrate indicated that the epitaxial phase is 180° rotated about the [111] normal direction like the B type NiSi2 and CoSi2 silicides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106430
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  • 8
    Electronic Resource
    Electronic Resource
    Pulsed laser melting and resolidification of metal silicide layers (1993)
    Springer
    International journal of thermophysics 14 (1993), S. 383-396 
    Details
    ISSN: 1572-9567
    Keywords: laser pulse ; suicide ; melting ; phase transition ; solidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Ti, Fe, and Co silicide layers, 80–200 nm thick, on top of single crystal silicon substrate have been melted by 25-ns ruby laser pulses and the resolidified structures have been analyzed by transmission electron microscopy, X-ray diffraction, and Rurtherford backscattering spectrometry. Metastable phases and/or epitaxial layers are obtained upon solidifcation. The transient molten layer has been monitored by means of time-resolved optical measurements with nanosecond resolution; in all cases solidification velocity of the order of 1 m · s−1 was observed, and in one case liquid undercooling as much as 800 K was estimated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566038
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  • 9
    Electronic Resource
    Electronic Resource
    Thermodynamic properties of amorphous silicon investigated by pulsed laser heating (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 141-151 
    Details
    ISSN: 1572-9567
    Keywords: amorphous Si ; laser irradiation ; melting temperature ; reflectivity ; relaxation ; thermal properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nanosecond (λ=347 nm, τ=25 ns) and picosecond (λ=532 nm, τ=20 ps) pulsed laser irradiation have been used to induce surface melting in ion implanted and annealed amorphous silicon layers. Time-resolved reflectivity technique was employed to detect the melting onset, from which the melting temperatures of the amorphous phases have been evaluated. Thermal properties of the relaxed amorphous have also been investigated, and in particular, the differences in the heat capacity and in the thermal conductivity of the relaxed amorphous with respect to the as-implanted one were determined. Using these results, the free energy diagram of both relaxed and unrelaxed amorphous silicon has been constructed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00503362
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