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  • 1
    Digitale Medien
    Digitale Medien
    Characterization of AlAs/GaAs superlattice barriers using electrical barrier height analysis (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 4765-4767 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Electrical barrier height measurements on n+-GaAs–insulator–n-GaAs structures with short-period AlAs/GaAs superlattices forming the insulator show the effective conduction-band discontinuity (ΔEC) of a superlattice barrier (SLB) to be defined by the lowest superlattice energy state. Five structures with different AlAs and GaAs SLB layer thicknesses are investigated. A SLB with GaAs layers greater than 10 monolayers is found to have a ΔEC defined by Γ-valley states in the GaAs layers, while a SLB with GaAs and AlAs layers less than 10 monolayers and with thicker AlAs layers than GaAs layers is found to have a ΔEC defined by X-valley states in the AlAs layers. The SLB with GaAs and AlAs layers less than 10 monolayers and thicker GaAs layers than AlAs layers behaves as a random alloy. Negative differential resistance is observed in the current-voltage characteristic of the sample whose barrier height is defined by Γ-valley states in the GaAs layers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.341194
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  • 2
    Digitale Medien
    Digitale Medien
    Photocurrent spectroscopy of InxGa1−xAs/GaAs multiple quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2230-2232 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Photocurrent spectra of InxGa1−xAs/GaAs multiple quantum well structures grown by molecular beam epitaxy are studied in the presence of electric fields perpendicular to the heterointerface. Several Δn=0 allowed and Δn≠0 forbidden excitonic transitions are observed. Both negative and positive shifts of exciton transitions are found. Good agreement is found between the photocurrent observations and calculations using a multiband effective-mass approach, taking into account the strain-induced splitting.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.101132
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  • 3
    Digitale Medien
    Digitale Medien
    Parametric study of AlAs/GaAs superlattice double-barrier diodes (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 207-209 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Quantum well diodes with barriers formed by thin, short-period binary AlAs/GaAs superlattices were fabricated and found to have very high peak-to-valley current ratios. The effects of varying the AlAs and GaAs layers in the barriers are studied. The peak current density is found to decrease by orders of magnitude for monolayer increases in the AlAs layer thicknesses. Tunneling current peaks due to both resonance levels in the quantum well and resonance levels in the superlattice barriers are observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.100132
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  • 4
    Digitale Medien
    Digitale Medien
    AlGaAs/GaAs double barrier diodes with high peak-to-valley current ratio (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 121-123 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report the largest peak-to-valley current (PVC) ratios to date from AlGaAs/GaAs double barrier (either alloy barrier or superlattice barrier) diodes. PVC ratios as high as 3.6 and 21.7 were obtained from an AlAs/GaAs superlattice barrier structure at 300 and 77 K, respectively. In an alloy barrier structure with x=0.42 (x=0.3), PVC ratios of 3.9 (2.2) and 14.3 (7.0) were observed at 300 and 77 K, respectively. We attribute these excellent results to a "two-step'' spacer layer incorporated in the devices studied which facilitated the growth of high material quality.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.98588
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  • 5
    Digitale Medien
    Digitale Medien
    Lymphatics of the Skin (1986)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of dermatology 25 (1986), S. 0 
    Details
    ISSN: 1365-4632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-4362.1986.tb03443.x
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  • 6
    Digitale Medien
    Digitale Medien
    EXPERIMENTAL CHARACTERISATION OF DYNAMIC TENSILE AND FRACTURE TOUGHNESS PROPERTIES (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 12 (1989), S. 0 
    Details
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— —An experimental procedure for obtaining material tensile and fracture toughness properties at rates applicable to shock loading is reported. A variant of the key curve approach to determine dynamic J-R curves is described and results are presented for a nickel aluminium bronze alloy for actuator loading rates in the range 0.75–7500 mm/s.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-2695.1989.tb00550.x
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  • 7
    Digitale Medien
    Digitale Medien
    THE EFFECT OF SPECIMEN SIZE ON THE CTOD R-CURVE BEHAVIOUR OF A TITANIUM ALLOY (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 12 (1989), S. 0 
    Details
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— —This paper presents preliminary results from a large experimental programme to study geometry and size effects in CTOD R-curves. The results presented were obtained from unloading compliance R-curve tests performed at room temperature on different sized single-edge-notch bend specimens made from Ti–3Al–2V alloy. The crack growth resistance was measured in terms of both the conventional CTOD, δ0, (i.e. as defined in BS 5762) and CTOD corrected for crack growth, δR. It was found that the δ0 and δR R-curves were independent of specimen size up to crack extensions corresponding to approximately 10–15% of the original uncracked ligament. Also, after crack extensions of 30–40% of the initial ligament the δ0 and δR R-curves exhibited well defined upswings. The upswing in the CTOD R-curves is thought to be a result of a reduction in crack tip constraint.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-2695.1989.tb00539.x
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  • 8
    Digitale Medien
    Digitale Medien
    THE EFFECT OF SPECIMEN SIZE ON THE J R-CURVE BEHAVIOUR OF A TITANIUM ALLOY (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 12 (1989), S. 0 
    Details
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— —This paper presents preliminary results from a large experimental programme to study geometry and size effects in J R-curves, The results presented were obtained from unloading compliance R-curve tests performed at room temperature on different sized single-edge-notch-bend specimens made from Ti-3Al–2V alloy. The crack growth resistance was measured in terms of the standard fracture resistance J (i.e. not corrected for crack growth), J corrected for crack growth, and the J modified parameter proposed by Ernst. It was found that the best agreement was exhibited by the R-curves based on the standard fracture resistance J, which displayed reasonable size independence up to, and in many cases beyond crack growths corresponding to 50% of the initial uncracked ligament.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-2695.1989.tb00538.x
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  • 9
    Digitale Medien
    Digitale Medien
    The effect of monensin on intracellular transport and secretion of α-amylase isoenzymes in barley aleurone (1986)
    Springer
    Planta 167 (1986), S. 252-259 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Aleurone (enzyme secretion) ; α-Amylase ; Gibberellin and enzyme secretion ; Hordeum (enzymes) ; Monensin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of monensin on the secretion of α-amylase and other enzymes from the aleurone layer of barley (Hordeum vulgare L. cv. Himalaya) was studied by electrophoresis followed by fluorography and by pulse-chase and organelle-isolation experiments. Monensin markedly inhibits the secretion, but not the synthesis, of α-amylase, acid phosphatase, and at least four other proteins from the aleurone layer. Monensin treatment causes α-amylase to accumulate within the protoplast, but its effect on the different α-amylase isoenzymes is not equal. The accumulation of isoenzyme 2 is not influenced by monensin while isoenzymes 1, 3 and 4 are not secreted but rather accumulate in the cell when monensin is included in the incubation medium. The α-amylase and acid-phosphatase activities which accumulate within the aleurone cells following treatment with monensin are localized in an organelle having a buoyant density greater than that of endoplasmic reticulum and less than that of mitochondria. In pulse-chase experiments with [35S]methionine, labelled proteins accumulate in this organelle in the presence of monensin and do not appear in the incubation medium. We conclude that monensin inhibits the secretion of proteins from the barley aleurone layer by influencing their intracellular transport.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00391423
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  • 10
    Digitale Medien
    Digitale Medien
    Global and seasonal variability of the temperature and composition of the middle atmosphere (1985)
    [s.l.] : Nature Publishing Group
    Nature 313 (1985), S. 439-443 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The Stratospheric and Mesospheric Sounder on board the experimental meteorological satellite Nimbus 7, launched in 1978, was designed to study the global structure, radiative properties, chemistry and dynamics of the stratosphere and mesosphere. The instrument obtained data over a four and a half ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/313439a0
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