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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1161-1168 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the electronic properties of the δ-modulation-doped Al0.30Ga0.70As/In0.15Ga0.85As heterojunction for a variety of different configurations. Experimental findings are compared with theoretical predictions based on the two-band effective mass approximation including strain, many-body, finite temperature, and DX center effects. We have also examined the case where the δ doping is placed in an embedded GaAs well within the Al0.30Ga0.70As. This is intended to reduce the effects of DX centers. In this instance, as the doping concentration is increased, experimentally determined channel density, ns, suggests higher saturation values, which may leave a residual electron density in the GaAs well. This residual charge density is parallel with the electron density in the InGaAs well and represents an additional conducting path. The features of the theoretical channel density versus doping density curves are confirmed by 300 and 1.6 K resistivity and Hall measurements, and Shubnikov–de Haas measurements made at 1.6 K.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 3066-3068 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Reflection high-energy electron diffraction intensity oscillations during Ge heteroepitaxy on Si(100) have been observed using a gas source molecular beam epitaxy system. Intensity oscillations can be observed over 6 ML (monolayers) of growth in the temperature range 400–650 °C. The oscillation frequency, however, varies from the first to subsequent layers and this variation is interpreted primarily as a change in the limiting growth kinetics as the surface composition changes from Si to Ge. Growth temperature and GeH4 flux dependence data indicate that the surface Ge concentration increases gradually, not abruptly, over the first several layers of deposition. Surface roughening effects which are attributed to Stranski–Krastanov type growth, are also found to contribute to the nonuniform oscillation frequency. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1116-1118 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The concentration and mobility of the two-dimensional electron gas present at the interface between strain-relaxed, lattice matched, InyAl1−yAs/InxGa1−xAs(x 〈 0.45), modulation doped heterojunctions grown by means of compositionally step-graded buffer layers on GaAs substrates, were measured at room temperature and at 77 K. The composition dependence of the electron density is attributed to the dependence of the band-gap energy of InxGa1−xAs and that of InyAl1−yAs on x, with a conduction band offset, ΔEc∼0.67ΔEg. The room temperature electron mobility increases from 9×103 cm2/V s for x=0.07 to 1.05×104 cm2/V s for x=0.45. Such strain-relaxed heterostructures have higher electron mobilities than similar pseudomorphic structures with the same sheet electron concentration.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1129-1131 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Modulation-doped In0.3Ga0.7As/In0.29Al0.71As heterostructures have been grown on GaAs substrates by molecular beam epitaxy using a compositionally step-graded InxGa1−xAs buffer layer. We found that the buffer layer produces essentially total relaxation with 〈2×106/cm2 dislocations present in the In0.3Ga0.7As layer. The structural perfection of this layer is reflected in the electrical and galvanomagnetic properties of its two-dimensional electron-gas channel which has a sheet-electron density of 1.2×1012/cm2, peak mobilities of 9 300 cm2/V s at room temperature and 31 000 cm2/V s at 77 K, and a mobility anisotropy of ∼4% along orthogonal 〈110〉 directions.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1351
    Keywords: Photoreception ; Extraretinal Photoreceptor ; Chromophore ; Opsin ; Reptile ; Immunocytochemistry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Since the beginning of this century evidence has accumulated which demonstrates that non-mammalian vertebrates possess photoreceptors situated deep within the brain. While many attempts have been made to localize these sensory cells, studies have either failed or been inconclusive. In this report we have used several experimental approaches to localize the deep brain photoreceptors of the lizard Anolis carolinensis. Using 3 antibodies that bind vertebrate cone opsins, we have immunolabelled cerebrospinal fluid (CSF)-contacting neurons located at the ventricular border within the nucleus ventromedialis of the septum. Western blot analysis indicates that these antibodies recognized a single 40 kD protein in ocular, anterior brain, and pineal extracts. Immunoblots of rodent brain did not show a similar protein band. We have also identified specific retinoids associated with phototransduction (11-cis and all-trans-3,4-didehydroretinaldehyde) within anterior brain extracts. This combined data provides the most detailed analysis of deep brain photoreceptors in any vertebrate. Consequently, we feel Anolis provides an excellent model to study this unexplored sensory system of the vertebrates.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-4475
    Keywords: Hydroxy-naphthalenic Schiff bases ; Schiff base copper(II) complexes ; Copper(II) complexes ; Crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurden die Schiffbasen-Liganden 3-[(Phenyl)-2-hydroxy-3H-naphth-3-yliden)-methyl]aldamin (1) und 3-[(Benzen-4-trifluoromethyl)-2-hydroxy-3H-naphth-3-yliden)-methyl]aldamin (2) inklusive der entsprechenden Kupfer(II)-KomplexeI undII dargestellt. VonI undII wurden die Kristallstrukturen ermittelt. KomplexI kristallisiert im triklinen System mita=10.804(5),b=12.589(5),c=10.369(3) Å, α=107.72(3), β=95.75(3) und γ=76.32(4)° in der Raumgruppe P $$\bar 1$$ mitZ=2. VerbindungII kristallisiert ebenfalls im triklinen System mita=10.718(2),b=13.861(4),c=10.110(9) Å, α=95.99(2), β=90.16(2) und γ=93.90(2)° in der Raumgruppe P $$\bar 1$$ mitZ=2. Die Geometrie rund um Cu ist in beiden Komplexen quadratisch-planar.
    Notes: Summary The Schiff base ligands, 3-[(Phenyl)-2-hydroxy-3H-Naphth-3-ylidene)methyl]aldamine (1) and 3-[(benzene-4-trifluoromethyl)-2-hydroxy-3H-naphth-3-ylidene)methyl]aldamine (2), and their corresponding Cu(II) complexes (I andII were synthesized. The crystal and molecular structures ofI andII were determined. CompoundI crystallizes in the triclinic crystal systema=10.804(5),b=12.589(5), andc=10.369(3) (Å), α=107.72(3), β=95.75(3), and γ=76.32(4)(°), in the space group P $$\bar 1$$ withZ=2. CompoundII crystallizes in the triclinic crystal systema=10.718(2),b=13.861(4), andc=10.110(9) (Å), α=95.99(2), β=90.16(2), and γ=93.90(2)(°), in the space group P $$\bar 1$$ withZ=2. The geometry around the metal atom in both complexesI andII is square planar.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 363 (1993), S. 554-558 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Vesicle fusion and the fusion pore conductance were measured by following the admittance of a beige mouse mast cell in the whole-cell mode of the patch-clamp technique6'7. Release of secretory products was measured with amperometry by placing a carbon fibre electrode very close to the cell ...
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Prostaglandins ; C18 Solid phase extraction ; Radioimmunoanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The aim of this study has been the evaluation of an automated system for on-line sample preparation using solid phase extraction and HPLC purification for the measurement of prostanoids in urine. We have established the optimum precolumn and column conditions for this analysis. The manual extraction —HPLC procedure furnishes lower recoveries and higher coefficients of variation than those obtained by the automated on-line procedure. The automated system has been applied to prostanoid analysis of human urine samples from subjects exposed to lead.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology techniques 8 (1994), S. 793-796 
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new simple electronic device for liquid flowrate measurement in laboratory or semipilot scale fermenters is presented. The flow meter is also applicable to pulsing or oscillating flow rates. This system allows either a direct measurement of the flow or implementation on a data acquisition system, if available.
    Type of Medium: Electronic Resource
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