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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in the evaluation of the lumbar herniated intervertebral disc (1993)
    Springer
    International orthopaedics 17 (1993), S. 241-244 
    Details
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Deux cent onze patients atteints de hernie discale lombaire, confirmée par imagerie par résonance magnétique (IRM) et représentant 242 niveaux, ont été répartis en cinq groupes. Le diagnostic IRM a été comparé aux constatations opératoires afin d'évaluer de façon prospective la précision diagnostique de la classification IRM. Il n'y a pas eu d'exploration discale négative. Pour la distinction entre protrusion et autres types de hernie discale, la sensibilité, la spécificité et l'exactitude de l'IRM ont été respectivement de 92%, 91% et 92%. Pour la séquestration discale, la sensibilité a été de 92%, la spécificité de 99% et l'exactitude de 97%. En ce qui concerne l'extrusion sous-ligamentaire, on a noté une sensibilité de 71%, une spécifité de 82% et une exactitude de 79%, tandis que pour les extrusions trans-ligamentaires la sensibilité a été de 52%, la spécifité de 92% et l'exactitude de 79%. L'exactitude moyenne pour la prévision du type de hernie discale a donc été de 85%. L'IRM de haute résolution est donc très efficace pour la détection des lésions discales et leur classification.
    Notes: Summary Two hundred and eleven patients with lumbar disc herniation at 242 levels were divided into 5 groups by their appearances on magnetic resonance imaging (MRI), and the findings at operation were compared to assess the accuracy of the MRI classification. There were no negative explorations. There was 92% sensitivity, 91% specificity and 92% accuracy for MRI in distinguishing protruded discs from other forms of lumbar disc herniation. For sequestrated discs there was 92% sensitivity, 99% specificity and 97% accuracy. In the extruded subligamentous type there was 71% sensitivity, 82% specificity and 79% accuracy, and 52% sensitivity, 92% specificity and 81% accuracy in the extruded transligamentous type. The overall accuracy of MRI predicting the types of herniated lumbar intervertebral disc was 85%. High resolution MRI is sensitive in detecting disc disease and specific in characterizing various subgroups of disc herniation, especially those which are sequestrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194188
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  • 2
    Electronic Resource
    Electronic Resource
    A study on the Kerr effect enhancement by the multidielectric layer structure : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5987-5988 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Many types of magneto-optical structures have been investigated to improve the MO Kerr effect. We have studied the enhancement of the MO Kerr effect in the Tb21Fe79 amorphous film having a multidielectric structure in which the TiO2 layer is sandwiched by SiNx layers. The variations of Kerr angle and reflectivity with the thickness of dielectric layer are calculated by using the reiterative formula [M. Mansuripur, G. A. N. Connel, and J. W. Goodman, J. Appl. Phys. 53, 4485 (1982)]. Experiment and simulation results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347813
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  • 3
    Electronic Resource
    Electronic Resource
    Heteroepitaxial wurtzite and zinc-blende structure GaN grown by reactive-ion molecular-beam epitaxy: Growth kinetics, microstructure, and properties (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 189-204 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reactive-ion molecular-beam epitaxy has been used to grow epitaxial hexagonal-structure α-GaN on Al2O3(0001) and Al2O3(011¯2) substrates and metastable zinc-blende-structure β-GaN on MgO(001) under the following conditions: growth temperature Ts=450–800 °C; incident N+2/Ga flux ratio JN+2/JGa=1–5; and N+2 kinetic energy EN+2=35–90 eV. The surface structure of the α-GaN films was (1×1), with an ≈3% contraction in the in-plane lattice constant for films grown on Al2O3(0001), while the β-GaN films exhibited a 90°-rotated two-domain (4×1) reconstruction. Using a combination of in situ reflection high-energy electron diffraction, double-crystal x-ray diffraction, and cross-sectional transmission electron microscopy, the film/substrate epitaxial relationships were determined to be: (0001)GaN(parallel) (0001)Al2O3 with [21¯1¯0]GaN(parallel)[11¯00]Al2O3 and [11¯00]GaN(parallel)[12¯10]Al2O3, (21¯1¯0)GaN(parallel)(011¯2)Al2O3 with [0001]GaN(parallel)[01¯11]Al2O3 and [01¯10]GaN(parallel)[21¯1¯0]Al2O3, and (001)GaN(parallel)(001)MgO with [001]GaN(parallel)[001]MgO.Films with the lowest extended defect number densities (nd(approximately-equal-to)1010 cm−2 threading dislocations with Burgers vector a0/3〈112¯0(approximately-greater-than)) and the smallest x-ray-diffraction ω rocking curve widths (5 min) were obtained using Al2O3(0001) substrates, Ts≥650 °C, JN+2/JGa≥3.5, and EN+2=35 eV. Higher N+2 acceleration energies during deposition resulted in increased residual defect densities. In addition, EN+2 and JN+2/JGa were found to have a strong effect on film growth kinetics through a competition between collisionally induced dissociative chemisorption of N2 and stimulated desorption of Ga as described by a simple kinetic growth model. The room-temperature resistivity of as-deposited GaN films grown at Ts=600–700 °C with EN+2=35 eV increased by seven orders of magnitude, from 10−1 to 106 Ω cm, with an increase in JN+2/JGa from 1.7 to 5.0. Hall measurements on the more conductive samples yielded typical electron carrier concentrations of 2×1018 cm−3 with mobilities of 30–40 cm2 V−1 s−1. The room-temperature optical band gaps of α-GaN and β-GaN were 3.41 and 3.21 eV, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353882
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  • 4
    Electronic Resource
    Electronic Resource
    Formation of a metastable ferromagnetic τ phase during containerless melt processing and rapid quenching in Mn-Al-C alloys (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 676-680 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Solidification of selected Mn-Al-C alloys during containerless levitation and rapid quenching has yielded the first report for a ferromagnetic metastable τ (L10) phase formed directly from the melt. Complete solidification to τ phase was interrupted by the competitive evolution of an equilibrium ε phase during recalescence. The amount of undercooling required to produce the metastable ferromagnetic τ phase in a Mn0.55Al0.433C0.017 alloy during solidification was estimated as approximately 470 K based on differential thermal analysis results. When the alloy carbon content was increased to 3.4 at. % (i.e., Mn0.55Al0.416Co0.034 alloy), a transition in structure development occurred so that the samples exhibited γ2 phase formation as well as τ and ε phases. Both microstructural observations and x-ray diffraction examination were used to guide the interpretation and the analysis of solidification pathways. The attainment of the high liquid undercooling required to nucleate the metastable τ phase from the melt may be facilitated by containerless processing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351326
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  • 5
    Electronic Resource
    Electronic Resource
    Domain wall observation and eddy current loss of (110)[001] oriented 17–22 μm thick Si-Fe tape-wound cores up to 5 kHz : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6256-6258 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dynamic magnetic domain observation and eddy current loss of tape-wound cores are discussed up to 5 kHz. The cores are made of 17–22 μm thick (110)[001] oriented silicon steel strips. Dynamic domain patterns were observed by using SEM on the surfaces of the tape-wound cores. In order to distinguish the moving domain walls from the standing ones, the drive frequency of the core should not be integral multiples of the scan frequency of the SEM(50.0 Hz). The model which includes dynamic wall number, wall bowing, and velocity of each domain wall agreed comparatively well with the measured eddy current losses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349984
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  • 6
    Electronic Resource
    Electronic Resource
    Nb-added high-coercivity Nd-Fe-B melt-spun ribbon with high remanence : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6477-6479 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of composition and additives on the microstructures and magnetic properties of Nd-Fe-B melt-spun ribbons were studied. Experimental results have revealed that homogeneous grain structure with fine grain size was obtained on composition close to 2-14-1 stoichiometry with additives. It was also found that Nb was very effective in increasing both remanence and coercivity in a Nd-Fe-B melt-spun ribbon. A high-energy product of 151.2 kJ/m3 (19.0 MGOe) was obtained from an isotropic (Nd0.5Pr0.5)12Fe72Co8B6Nb2 melt-spun ribbon with a remanence of 0.926 T and a coercivity exceeding 1200 kA/m (∼15 kOe).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349905
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  • 7
    Electronic Resource
    Electronic Resource
    Magnetic properties of sputtered Fe thin films: Processing and thickness dependence (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1233-1241 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure and magnetic properties of polycrystalline Fe films with thicknesses of 200–1000 A(ring) have been investigated. The films were prepared by rf sputtering onto SiO2 substrates. The investigation was prompted by the lack of data on sputtered Fe films in this thickness regime as well as disagreement in the data for evaporated films. In addition to thickness, substrate temperature and deposition pressure were varied to examine their effect on the microstructure. The film microstructure was characterized by x-ray diffraction, transmission electron microscopy, and Auger spectroscopy. The polycrystalline films did not display a strong preferred orientation and had average grain sizes of 60–85 A(ring). Surface oxide layers formed upon exposure to air ranged from 10 to 80 A(ring), the thicker oxides formed on films with lower density. Magnetic hysteresis measurements were made with a vibrating sample magnetometer. Below 1000 A(ring), porosity and surface oxidation result in reductions up to 25% in the saturation magnetization. An anomalous peak in coercivity at film thicknesses of 300–500 A(ring) was observed, which can be explained by the change in domain wall type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354926
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  • 8
    Electronic Resource
    Electronic Resource
    Significant improvement in the surface smoothness of post-annealed Y-Ba-Cu-O thin films upon silver addition (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 856-858 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the effect of silver addition on the surface quality of rf-sputtered Y-Ba-Cu-O thin films. The Y-Ba-Cu-O-Ag films appear to have very smooth surfaces even if the post-annealing step is employed. The surface roughness of our ex situ grown Y-Ba-Cu-O-Ag film, having a 10.3 wt. % of silver, is within ±1% of the film thickness, which is more than 10 times better than the value of a typical post-annealed high-temperature superconducting film without silver.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346768
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  • 9
    Electronic Resource
    Electronic Resource
    Processing-properties relationships in Fe3O4 thin films (abstract) : 37th annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6313-6313 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: As part of a fundamental study of interface magnetism in Fe/Fe3O4 multilayer systems, we have examined the magnetic properties of polycrystalline Fe3O4 thin films. Fe3O4 thin films, deposited by reactive evaporation and sputtering, have been previously studied because they serve as a precursor for the formation of γ-Fe2O3. The film thicknesses used in these studies have typically been greater than 100 nm. We have examined the magnetic properties and microstructure of Fe3O4 films with thicknesses less than 100 nm, a regime in which the magnetic properties have been reported to be strongly dependent on thickness.1 The films were deposited by rf sputtering. The processing variables examined include substrate material, substrate temperature, oxygen partial pressure, and film thickness. The microstructural origins of the observed coercivity and anisotropy will be discussed, as well as trends in the saturation behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352682
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  • 10
    Electronic Resource
    Electronic Resource
    Femtosecond coherent transient infrared spectroscopy of CO on Cu(111) (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 4421-4427 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Femtosecond infrared coherent transients have been measured for the stretch vibration of CO on Cu(111). The free induction decay exhibits a dephasing time (T2) of 2±0.3 ps (and 2±0.1 ps assuming a single exponential decay between 2 and 3 ps). The decay was best fit by exponential relaxation, thereby suggesting that the CO vibrational band is almost entirely homogeneously broadened. The surface sum frequency spectrum was also measured at two coverages (0.10 and 0.45 L) using spectrally narrowed pulses. Interferences were observed leading to a determination of the relative phase and amplitude of the resonant and nonresonant second-order susceptibility in this system. The magnitude of the nonresonant susceptibility was only weakly dependent on coverage, suggesting that the nonresonant polarizability originates in the bulk Cu. Time and frequency domain results were in good agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463884
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