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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4920-4922 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetophotoluminescence excitation spectroscopy has been employed to study GaAs-AlGaAs coupled double quantum wells. The investigations were undertaken at liquid helium temperatures and in magnetic fields up to 15 T applied parallel to the growth direction. In zero magnetic field, under flat-band conditions, the spectrum is dominated by ground-state excitonic transitions between electron and hole states with envelope functions of the same symmetry. In a magnetic field, the oscillator strengths of excited excitonic states are enhanced and four series of transitions are observed. The spectral features corresponding to the ground state and the excited states have been analyzed and these results were utilized to determine the exciton binding energies for several excitonic transitions of different subbands in this coupled double quantum-well structure. A number of additional features are visible at higher magnetic fields; some of these peaks are believed to be associated with 2p exciton transitions between hole and electron states with envelope functions of opposite parity due to exciton mixing. A comparison is made between the experimental results and theoretical calculations which include these effects.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4095-4102 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ferroelectric twin-domain structures in epitaxial Pb(Zr, Ti)O3 (PZT) thin films grown on various single-crystal substrates such as MgO(001), KTaO3(001), and SrTiO3(001) were investigated by two-dimensional reciprocal space mapping using synchrotron x-ray diffraction. Each system showed a characteristic domain structure. PbTiO3 thin films grown on MgO(001) showed highly c-axis oriented domain structures consisting of a periodic array of 90° twinlike domains. Perfectly c-axis oriented films were obtained on SrTiO3(001), while the films grown on KTaO3(001) showed a-domain dominant structures with a small amount of c domains embedded in matrix a domains. Contributions of net elastic strain stored in each heteroepitaxial layer and its relaxation to the final domain structures were evaluated considering thermodynamic equilibrium relief of coherency strain by misfit dislocation generation at the film growth temperature. A comparison between theoretical consideration and experimental results clearly demonstrates that the nature of effective misfit strain and its relaxation during film growth play a critical role in the formation of domain structures in epitaxial PZT thin films. Moreover, it was verified that the control of such critical strain factors by changing film composition could modify dominant domain structures in a drastic way. In addition, it was found that the crystalline quality of the films is closely correlated to the tilting nature of the domain structure in each system and coherency strain across the 90° domain boundary is accommodated mainly by the domain tilt of the minor domain. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8035-8038 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strain relaxation and its effect on domain formation of epitaxial PbTiO3 thin films grown on MgO (001) substrates were investigated as a function of film thickness by two-dimensional reciprocal space mapping using synchrotron x-ray diffraction. Within a few hundreds of angstrom region, it was observed that c-domain abundance, α, was critically dependent on film thickness. As the film thickness increased further, α was saturated at a value of ∼0.75. The HK mesh scan on PbTiO3 (100) reflections revealed that directional tilting of a domains with four-fold symmetry began to develop as the film thickness exceeded 650 Å. Thermodynamic equilibrium relief of the coherency strain was evaluated based on Mattews–Blakslee criteria that determine thickness dependent misfit accommodation. This theoretical consideration with experimental results led us to conclude that the unrelaxed residual misfit strain has a significant effect on the domain formation, particularly in the region below the thickness of 1000 Å. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2863-2867 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Shubnikov–de Haas and Van der Pauw Hall effect measurements at 1.5 K have been carried out to investigate the existence of a two-dimensional electron gas and to determine subband energies in a Si-delta-doped Al0.27Ga0.73As/GaAs single quantum well. The fast Fourier transformation results for the S-dH data indicate clearly the occupation of two subbands in edge delta-doped Al0.27Ga0.73As/GaAs quantum wells. Capacitance-voltage profiling and temperature-dependent photoluminescence measurements have been performed to characterize the properties of edge delta-doped Al0.27Ga0.73As/GaAs quantum wells. Using these experimental results and a self-consistent numerical method which took into account the exchange-correlation effects, the electron subband energies were determined. These results indicate that edge delta-doped Al0.27Ga0.73As/GaAs single quantum wells are similar to the asymmetrical potential wells occupied by relatively high electron carrier densities.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 34 (2004), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Toluene diisocyanate (TDI)-induced asthma is an inflammatory disease of the airways characterized by airway remodelling due, at least in part, to an excess of extracellular matrix deposition in the airway wall. The ratio of matrix metalloproteinase-9 (MMP-9) and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1) may be a marker of the balance between airway tissue destruction and repair.Objective We determined whether an imbalance of the MMP-9 : TIMP-1 molar ratio is present before and/or after challenge with TDI.Methods We used a murine model of TDI-induced asthma to evaluate the MMP-9 and TIMP-1 balance in the lung.Results The expression of MMP-9 and TIMP-1 mRNAs and proteins in the lungs increased at 7 h after TDI inhalation and continued for up to 72 h. Immunohistochemical and immunocytological analyses in the lungs of TDI-exposed mice revealed increases of immunoreactive MMP-9 and TIMP-1. There were significant correlations between the levels of MMP-9 or TIMP-1 and the number of neutrophils, lymphocytes, or eosinophils. The molar ratio of MMP-9/TIMP-1 significantly decreased at 7 h after TDI inhalation and continued up to 72 h.Conclusion These data suggest that TDI-induced asthma may be associated with an imbalance between MMP-9 and TIMP-1, which could be useful as a marker of airway inflammation and airway remodelling in this disease.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 14 (2004), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Allergy 56 (2001), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Buckwheat flour (BF) is known as a potent food allergen. Sensitization to it usually occurs by ingestion but also by inhalation in occupational or domestic exposure. Buckwheat chaff-stuffed pillows (BCP) can be contaminated with BF during the process of pilling, and many Korean children and adults use BCP for health reasons. Methods and Results: We here present three cases of BF allergy in children using BCP, who had been treated as nonatopic asthmatics after undergoing the routine allergy skin tests and serologic tests. We took careful clinical histories, and performed skin prick tests (SPT), the radioimmunoassay (RIA) for specific IgE, the BCP-elimination test, the BF bronchial provocation test, and IgE Western blot. All three children showed positive skin reactions to BF, but none of them had positive reactions to house-dust mites. Nocturnal asthmatic symptoms were improved during 7 days of BCP elimination, and asthmatic responses were observed by bronchial provocation tests with homemade BF extract. Serum BF-specific IgE antibodies and several IgE-binding proteins were detected by RIA and Western blot analysis, respectively. Conclusions: Thus, a small amount of BF attached to BCP can induce BF sensitization, and BCP should be considered a main cause of childhood nocturnal asthma in those asthmatics exposed to these pillows.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Berlin, Germany : Blackwell Verlag GmbH
    Anatomia, histologia, embryologia 32 (2003), S. 0 
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In this immunocytochemical study on the constitutive expression of Pax-7 protein in the postnatal chicken brain, Pax-7 showed region and cell type specific expression. In the optic tectum, only cells in grey matter showed positive immunoreactivities (IRs), whereas those in the white matters did not show any IRs. In thalamic nuclei and several pontine nuclei, we also localized Pax-7 positive IRs. On the contrary, in the cerebellum, Pax-7 was mainly localized within the Bergmann glia, whereas Purkinje cells did not show any IRs. In double immunolabelling studies, most of the Pax-7 IRs did not originate from neuroglial cells such as oligodendrocytes, microglia or astrocytes, but from neurons, with the exception of Bergmann glia in the cerebellum. The presence of Pax-7 IRs in the adult chicken brain could suggest that Pax-7 might play a role in maintaining normal physiological function in some postnatal chicken brain cells.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 50 (1994), S. 1768-1770 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of advanced manufacturing technology 16 (2000), S. 739-747 
    ISSN: 1433-3015
    Keywords: Key words: Assembly modelling; Feature-based; Injection moulds; Object-oriented
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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