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  • 1995-1999  (5)
  • 1990-1994  (5)
  • 1998  (5)
  • 1991  (5)
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  • 1995-1999  (5)
  • 1990-1994  (5)
Year
  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Coherent cw operation of a 10×10×2 grating-surface-emitting diode laser array in a ring configuration is demonstrated. At near twice the threshold current, the ring array exhibits a high degree of spatial coherence (an average of 86%) between emitting grating sections and a narrow linewidth of 28 MHz. The far field fringe visibility is 80% and 88% in the lateral and longitudinal directions, respectively.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2208-2210 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Separate-confinement heterostructure diode lasers containing a strained Al0.18In0.20Ga0.62 As single quantum well active layer and Al0.25Ga0.75As confining layers have been fabricated from structures grown on GaAs substrates by low-pressure organometallic vapor phase epitaxy. The emission wavelength of these devices is 814 nm. Threshold current density is as low as 103 A cm−2 for cavity length L=1500 μm, and differential quantum efficiency as high as 90% for L=280 μm. The characteristic temperature T0 is 214 K between 10 and 40 °C, and 159 K between 40 and 80 °C. Preliminary tests of cw operation suggest that these lasers are more reliable than AlGaAs/AlGaAs lasers.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1165-1166 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gain-guided Ga0.84In0.16As0.14Sb0.86/Al0.75 Ga0.25As0.06Sb0.94 double-heterostructure lasers emitting at ∼2.2 μm have been operated cw at heat sink temperatures up to 30 °C. The maximum output powers obtained at 5 and 20 °C were 10.5 and 4.6 mW/facet, respectively. For pulsed operation of broad-stripe lasers 300 μm wide and 1000 μm long, the threshold current density was as low as 940 A/cm2, the lowest room-temperature value reported for diode lasers emitting beyond 2 μm.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2634-2635 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained InGaAs/AlGaAs quantum well diode lasers have been fabricated on Si substrates for the first time. A GaAs buffer layer was grown on each Si wafer by temperature-cycled organometallic vapor phase epitaxy (OMVPE). The wafer was then transferred to a second reactor for OMVPE growth of a graded-index separate-confinement heterostructure single-quantum well laser structure. For lasers with a cavity length of 1000 μm, room-temperature pulsed threshold current densities as low as 174 and 195 A/cm2 have been obtained for active layer compositions of In0.02Ga0.98As and In0.05Ga0.95As, respectively. One laser with an In0.05Ga0.95As active layer operated cw for 56.5 h, a record lifetime for GaAs-based diode lasers on Si.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 876-878 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained single-quantum-well, broadened-waveguide GaInAsSb/AlGaAsSb diode lasers have exhibited room-temperature threshold current densities as low as 50 A/cm2, one of the lowest values reported for diode lasers at room temperature. These lasers, grown by molecular beam epitaxy, have emission wavelengths of ∼2.05 μm, characteristic temperature of 65 K, internal quantum efficiency of 95%, and internal loss coefficient of 7 cm−1. Single-ended cw power of 1 W is obtained for a 100-μm aperture. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 25 (1998), S. 305-315 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Hot-wire measurement and multi-smoke wire flow visualization method are employed to study vortex pairing in the jet column mode under two-frequency forcing with controlled initial phase differences. For the range of 0.3〈St D 〈0.6, vortex pairing can be easily controlled by means of the fundamental and its subharmonic forcing with varying initial phase differences. As stable vortex pairing dominates, the variation of the subharmonic component with the initial phase difference changes from a sine shape to a cusp-like shape. The harmonics of the subharmonic also show similar trends. The detuning induces the amplitude and phase modulations of the u-signal in the time trace and the sideband growth in the spectra. The u-signal reflects the subharmonic variation with the initial phase difference in its envelope. For 0.6〈St D 〈0.9, non-pairing advection of vortices due to improper phase difference is sometimes observed under single-frequency forcing. In this case, vortex pairing can be made to occur by the addition of a subharmonic with very small amplitude. As the initial level of this subharmonic is increased, the onset position of vortex pairing moves upstream. In this range, the initial phase difference is not an effective parameter in controlling vortex pairing.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract NiCrAlY bond coat and ZrO2–8 wt% Y2O3 top coat with various thicknesses were deposited on Hastelloy X by plasma spraying. Residual stress was calculated by the finite element method (FEM) to explain the variations in the bond strength and thermal fatigue characteristics with the thickness of the bond coat and top coat. The bond strength of thermal barrier coatings (TBCs) increased with decreasing maximum residual stress in the y-direction of the top coat. The thermal fatigue characteristics increased with decrease of the maximum principal residual stress of the top coat and the thickness of oxidation layer of the bond coat.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A recombinant strain of Saccharomyces cerevisiae, GAL-GO2, was developed to facilitate the production of extracellular glucose oxidase (GOD). The recombinant strain secreted 85% (8.7 U/ml) of the total GOD (10.3 U/ml) produced in shake flask culture. For further enhancement of GOD production, optimization of the speed of agitation and the rate of aeration in a stirred tank fermentor was carried out. Response surface methodology with appropriate statistical experimental design was employed for this purpose. The maximal level of extracellular GOD was achieved when the speed of agitation and the rate of aeration were 420 rpm and 0.25 vvm, respectively. The enzyme production was increased by 74% compared to the level obtained under unoptimized conditions.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of radioanalytical and nuclear chemistry 151 (1991), S. 373-378 
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Instrumental neutron activation analysis has been applied to semiconductor grade silicon to study the concentration levels of impurity elements, the contamination during the single crystal growing process, and the vertical and radial distributions of impurities, along with the decontamination effect in the analysis. Twenty elements of Au, Br, As, W, Cr, Co, Na, Eu, La, Se, Zn, U, Th, Hf, Fe, Sb, Ag, Ce, Tb and Ta have been analyzed in p- and n-type wafers, single crystals and a polycrystal by a single comparator method using two comparators of gold and cobalt. Considerable surface contamination has been found and could be removed by etching the surface with nitric and hydrofluoric acid before and after irradiation. The impurity concentration has been found to be generally increased in the process of single crystal growth. The vertical and radial distributions of impurities have revealed that some impurity elements were more concentrated in the top region of a single crystal rod than in the middle region, and that Br, Cr, La, Eu and Sb were enriched in the central region and As, U and Fe in the outer region.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 19 (1998), S. 419-422 
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The turbulent drag reduction characteristics of the rod-like polysaccharide xanthan gum dissolved in water was investigated using a rotating disk apparatus. The ultrasonic degradation method was adopted to obtain polymer fractions of different molecular weights of xanthan gum for this study. The drag reduction curve was then plotted to observed the universal characteristics of xanthan gum, and the intrinsic concentration was found to be an extremely useful quantity in normalizing the drag reduction data for different molecular weights.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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