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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 276-282 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Micro-Raman scattering experiments have been carried out to study a SiGe/Si photoelastic optical channel waveguide structure. A Si3N4 stressor stripe was fabricated on a SiGe/Si planar waveguide to create local stress variation beneath the stripe. To characterize the local stress distributions which create the channel waveguide structure, we obtained Si–Si Raman peak shifts in the SiGe layer by utilizing spatially resolved Raman spectra both from the top surface across the width of the Si3N4 stripe and from an edge (i.e., a waveguiding region) beneath the stripe. Longitudinal optical phonon shifts observed from the top surface show a significant increase in compressive stress within the stripe width and in tensile stress just outside of stripe edges for a sample annealed at 600 °C. To map local changes of stresses in the waveguiding region beneath the stripe, spectra from two transverse optical phonons were measured from the edge and interpreted using the Raman polarization selection rules. The Si–Si Raman peak shifts obtained were used to find strain components and, in turn, to model resultant local refractive index variations which give rise to optical confinement via the photoelastic effect. Model calculations show good agreement with the experimental data and provide mode profiles for both transverse magnetic and transverse electric propagation. These experiments contribute to a more detailed understanding of the complex stress and refractive index distributions present in photoelastic semiconductor optical channel waveguide structures, structures which are potentially useful for optical device technology. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 214-216 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use micro- and nano-photoluminescence to study the temperature-dependent excitonic emission from CdSe quantum dots embedded in a ZnSe matrix. By varying the spatial resolution from 200 nm to 1.7 μm, we are able to study the temperature dependence of the ultranarrow (∼200 μeV) emission from excitons confined to single quantum dots, as well as statistical ensembles of up to 200 dots. By measuring the quenching of the photoluminescence (PL) with temperature, we find compelling evidence that the PL emission from these samples results from two different kinds of states. Similar to previous work, we find that a broad PL line persists to 300 K with an activation energy of ∼40 meV. However, we find that the ultranarrow lines are quenched at about 60 K, indicating an effective activation energy of only 4.0 meV. © 1999 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 73 (1998), S. 3399-3401 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the evolution of molecular beam epitaxy (MBE)-grown, CdSe self-assembled quantum dots on ZnSe surfaces using microphotoluminescence techniques. Bare CdSe dots at room temperature undergo Ostwald ripening over a time scale measured in days. At the elevated temperatures maintained for MBE growth and dot formation, ripening is expected to progress much faster. Capping the dots with a thin ZnSe layer "freezes" the ripening, allowing one to sample different stages of the dot evolution and subsequent characterization. We have grown eleven samples, each with a different time interval, or growth interruption, between dot formation and capping; the growth interruption times ranging from 0 to 300 s, during which the samples were kept at 300 °C. Using microphotoluminescence spectroscopy, we have resolved the sharp emission peaks due to individual dots in each sample and, by analyzing the ensemble characteristics, have identified a new regime in the evolution of CdSe dots. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1813-1815 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report resonant photoluminescence from CdSe/ZnSe self-assembled quantum dots. When CdSe quantum dots are resonantly excited, excitonic sharp micro-photoluminescence peaks originating from individual quantum dots are strongly enhanced in the region corresponding to optical phonon energies below the excitation. The phonons active in this process are identified as the longitudinal optical (LO) phonons from the CdSe dots, as the interface phonons, and tentatively as the LO phonons from the two-dimensional-like precursor layers. These observations suggest that exciton recombination via phonons is a major relaxation process under resonant excitation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1287-1289 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report Raman imaging of stress in a SiGe/Si optical channel waveguide structure. The difference in thermal expansion coefficients between a Si3N4 stripe and a SiGe layer creates a significant localized stress profile beneath the stripe, which can result in optical confinement suitable for optical waveguide fabrication. We image these areas utilizing Raman polarization selection rules for two transverse optical phonons, relate the Raman peak shifts to strain components, and then to refractive index changes via the photoelastic effect. These micro-Raman images provide spatially resolved two-dimensional refractive index information on the waveguiding region of a channel waveguide structure. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 1194 (1994), S. 166-170 
    ISSN: 0005-2736
    Keywords: (V. vulnificus) ; Calcium ion ; Colloid-osmotic hemolysis ; Cytolysin ; Hemolysis ; Inhibition
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Molecular Basis of Disease 1227 (1994), S. 87-91 
    ISSN: 0925-4439
    Keywords: Alloxan ; Calcium ; Diabetes mellitus ; Hydrogen peroxide ; Verapamil
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1437-1596
    Keywords: Key words Quadruplex ; Short tandem repeat ; DNA typing ; Korean population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Notes: Abstract We present the results of a population study in Korea for four new tetrameric short tandem repeat (STR) loci employing multiplex PCR amplification, polyacrylamide gel electrophoresis of the PCR products and silver staining, which allow single base pair resolution and rapid typing. The loci tested were D18S1270, D14S608, D16S3253 and D21S1437 and all loci showed no significant deviations from Hardy-Weinberg equilibrium in more than 100 unrelated Koreans. This allelic frequency data can be used in forensic analyses and paternity tests to estimate the frequency of a multiplex PCR based DNA profile in the Korean population.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron Letters 35 (1994), S. 2357-2360 
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The CD8/CD4 hybrid DNA construct used for generating transgenic mice is shown in Fig. 1. The resulting /3-AprCD8/4+ transgenic mice (H-2d) were crossed with mice (H-2b) expressing a transgenic a/3TCR specific for the male (H-Y) antigen in the context of class I H-2Db MHC antigens6 (a£TCR+ ...
    Type of Medium: Electronic Resource
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