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  • 1
    Digitale Medien
    Digitale Medien
    Thick AlxGa1−xAs: An intrinsically percolating barrier owing to its microscopic structural inhomogeneity (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2513-2515 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A significant charge transfer, which differs from tunneling, over thick AlxGa1−xAs barrier in GaAs/AlxGa1−xAs asymmetric double quantum wells is studied by cw photoluminescence excitation (PLE) and time-resolved photoluminescence. It is found that 300-A(ring)-thick Al0.3Ga0.7As barrier is universally "leaky'' with transport time of ∼300 ps, while AlAs and AlAs/GaAs digital alloy barriers with same thickness are not. Aided by a model calculation, we suggest that the intrinsic inhomogeneities in the alloy, which recent x-ray and scanning tunneling microscope studies revealed, may be responsible. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.117724
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  • 2
    Digitale Medien
    Digitale Medien
    Strong instantaneous contribution in femtosecond degenerate four-wave mixing from 350 μm InP due to virtual excitation (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 79-81 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have observed strong four-wave mixing (FWM) signals from the third up to the seventh order for a 350 μm undoped InP at 10 K with an excitation at far below the band gap. The third order spectrally resolved FWM signal shifts continuously to blue as time delay moves away from positive to negative. The peak intensities of the third and fifth order time-integrated FWM signals decrease rapidly as the detuning increases, as (detuning)−2 and (detuning)−6, respectively. The FWM signal at far below the band gap is attributable to the strong instantaneous contribution of the excitation pulse. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.118125
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  • 3
    Digitale Medien
    Digitale Medien
    Characterization of hydrogen-terminated Si(111) surfaces by sum-frequency surface vibrational spectroscopy (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3357-3359 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Sum-frequency surface vibrational spectroscopy was used to characterize H-terminated Si(111) surfaces prepared by different methods. It was found that flash heating of a sample to 1500 K followed by H2 dosing at 900 K yields a surface as good in quality as a wet chemically treated surface. Both surfaces are far superior than that prepared by atomic H adsorption. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.125350
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  • 4
    Digitale Medien
    Digitale Medien
    Two-color picosecond experiments on anti-Stokes photoluminescence in GaAs/AlGaAs asymmetric double quantum wells (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 3620-3622 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Two-color photoluminescence experiments are performed on the anti-Stokes photoluminescence in GaAs/AlGaAs asymmetric double quantum wells. Direct evidence for forbidden absorption is shown, and its many intriguing aspects, particularly the role of long-lived defects, are revealed. Our experiments shed light on the ongoing controversies between many different models. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.125407
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  • 5
    Digitale Medien
    Digitale Medien
    Effect of oestradiol-17β immersion treatments on sex reversal of mud loach, Misgurnus mizolepis (Günther) (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 28 (1997), S. 0 
    Details
    ISSN: 1365-2109
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Mud loach, Misgurnus mizolepis (Günther), were sex reversed using the immersion technique. Fry were raised in water containing 50, 100 or 200 μg oestradiol-17β I−1 for 1, 2 or 3 weeks. Survival rates decreased as dose and duration of treatment increased: in most instances they were significantly (P 〈 0.05) lower than those of the controls. Growth rates were unaffected except for fish in the 200 μg I−1 treatments. The 200 μg T−1 treatments for 2 and 3 weeks produced monosex female populations. The 100 μg I−1 treatment for 3 weeks produced 99% females and 1% intersex individuals. Histologically, ovaries of sex-reversed fish were similar to those of normal females. Morphologically, however, they were different in that the ovaries of sex-reversed fish were not connected to the genital pore. The hormone treatments affected the size and morphology of the pectoral fins, which exhibit sexual dimorphism in mud loach.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2109.1997.00925.x
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  • 6
    Digitale Medien
    Digitale Medien
    The effects of exopolymers on cell morphology and culturability of Leuconostoc mesenteroides during starvation (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 839-844 
    Details
    ISSN: 1432-0614
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract Biofilm formation by bacterial cells can be used to modify the subsurface permeability for the purpose of microbial enhanced oil recovery, bio-barrier formation, and in situ bioremediation. Once injected into the subsurface, the bacteria undergo starvation due to a decrease in nutrient supply and diffusion limitations in biofilms. To help understand the starvation response of bacteria in biofilms, the relationship between exopolymer formation and cell culturability was examined in a batch culture. The average cell diameter was observed to decrease from 0.8 μm to 0.35 μm 3 days after starvation began. Cell chain fragmentation was also observed during starvation. Cells that underwent starvation in the presence of insoluble exopolymers showed a slower rate of decrease in cell diameter and in cell chain length than cells without insoluble exopolymers. The rate of decrease in the average cell diameter and cell chain length were determined using a first order decay model. Cells starved in the presence of exopolymers showed greater culturability than cells starved without exopolymers. After 200 days starvation, 2.5 × 10−3% cells were culturable, but no increase in cell number was observed. During starvation, the exopolymer concentration remained constant, an indication that the exopolymer was not consumed by the starving bacteria as an alternative carbon or energy source.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002530051601
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  • 7
    Digitale Medien
    Digitale Medien
    Effect of surface roughness on a turbulent wall-attaching offset jet (1995)
    Springer
    Experiments in fluids 19 (1995), S. 38-42 
    Details
    ISSN: 1432-1114
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The flow characteristics of a two-dimensional offset jet discharged parallel to a rough wall is experimentally investigated by using a split film probe. The distributions of the mean velocity and turbulent stresses in the flow field are obtained and compared with those of the wall attaching offset jet on a smooth wall. It is found that the wall-attaching region on the rough wall is longer than on the smooth wall for the same offset height and the jet speed. The normal distance of the maximum velocity point is farther away from the wall than that for the smooth wall case because of the thick wall boundary layer established by the surface roughness. It is also found that the roughness of the wall accelerates the relaxation process towards redeveloped plane wall jet and that it exhibits a quite different turbulent diffusion behavior especially near the wall from that in the wall jet over a smooth surface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192231
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  • 8
    Digitale Medien
    Digitale Medien
    1.3 μm planar buried heterostructure distributed feedback lasers grown by four-step MOVPE (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 459-464 
    Details
    ISSN: 1572-817X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract Data are presented on InGaAsP/InP planar buried heterostructure (PBH) distributed feedback (DFB) lasers operating at 1.3 μm. A four-step MOVPE process and holographic lithography are employed to fabricate these lasers. The CW laser threshold and the slope efficiency from these lasers are 9 mA and 0.23 mW mA-1 per facet at room temperature. Single-longitudinal-mode operation with side-mode suppression of more than 35 dB is obtained at 5 mW.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00563584
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  • 9
    Digitale Medien
    Digitale Medien
    LP MOVPE growth of AlGalnP/GalnP and its application to visible laser diodes (1995)
    Springer
    Optical and quantum electronics 27 (1995), S. 465-471 
    Details
    ISSN: 1572-817X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract High-quality and uniform bulk layers of (Al x Ga1−x )0.5In0.5P (x=0–0.7) and AlGalnP/GainP quantum wells (QWs) are grown on 2°-off (100) GaAs substrates by low-pressure metal organic vapour phase epitaxy at a low growth rate of 0.3 nm s-1. The amount of lattice mismatch and the variation of PL peak energy of (Al0.5Ga0.5)0.5In0.5P on the 50-mm substrate are less than 6×10-4 and 2 meV, respectively. (Al0.5Ga0.5)0.5In0.5P/Ga0.5In0.5P SQWs show narrow PL spectra even from a 0.6 nm well measured at 20 K. The variation of PL peak energy from (Al0.5Ga0.5)0.5In0.5P/Ga0.5In0.5P MQWs is less than 10 meV. Also, as-cleaved AlGalnP/GalnP lasers fabricated by a three-step MOVPE show a pulsed threshold current of 82 mA at room temperature, output power of 12 mW, and the lasing wavelength at 668.2 nm.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00563585
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  • 10
    Digitale Medien
    Digitale Medien
    Thermal conductivity of R32 and its mixture with R134a (1995)
    Springer
    International journal of thermophysics 16 (1995), S. 1193-1201 
    Details
    ISSN: 1572-9567
    Schlagwort(e): R134a, R32 ; R32+R134a mixture ; thermal conductivity ; transient hot-wire method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The liquid thermal conductivity of R32 (CH2F2) and R134a (CF3CH2F) was measured in the range from 223 to 323 K and from 2 to 20 MPa by the transient hot-wire method. The thermal conductivity of the R32+R134a mixture was also measured in the same range by varying the mass fraction of R32. The measured data are analyzed to obtain a correlation in terms of temperature, pressure and composition of the mixture. The uncertainty of our measurements is estimated to be within ±2%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02081287
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