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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3196-3199 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Epitaxial Ga2Se3 layers were grown on GaP (100) and GaAs (100) by metal–organic chemical vapor deposition and the heterovalent exchange reaction, respectively. Measurements of the sample reflectance were carried out in the spectral range from 70 to 50 000 cm−1 (∼10 meV−6.2 eV). The dielectric functions in the far infrared were determined from the reflectance measurements and are dominated by strong phonon features of the substrate and the layers. Substrate related multiphonon absorbances and Fabry–Perot interference dominate the mid infrared range. The spectra in the visible spectral range reveal Fabry–Perot interferences up to 2.6 eV indicating a fundamental band gap energy in the blue spectral range in contrast to the previously reported lower value of 2 eV. Further electronic transition energies were observed at 3.9, 4.7, and 5.0 eV. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 395-399 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Sulphur from an electrochemical source has been used to dope GaSb grown by molecular-beam epitaxy. The incorporation of sulphur in the epilayers has been measured by secondary ion mass spectrometry, and the effects of substrate temperature during growth and of the antimony-to-gallium flux ratio have been studied.The incorporation has been found to be a strong function of substrate temperature, varying from ∼100% below 435 °C to ∼1% at 525 °C. The incorporation also increases with antimony overpressure, varying by a factor of 3 on changing the antimony-to-gallium flux ratio from 1:1 to 4:1. The substrate temperature dependence is described by a simple kinetic model. The electrical activity of the incorporated sulphur is shown to be close to 100%.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3988-3990 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Rectifying contacts have been made by depositing epitaxial films of aluminum on both homo- and heteroepitaxial layers of n-type GaSb grown by molecular-beam epitaxy. The barrier heights determined from the current-voltage and capacitance-voltage characteristics of these contacts were 0.54 and 0.56 eV, respectively. The significance of these results is briefly discussed.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 131-137 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Experimental data are presented for the Hall coefficient and the apparent Hall mobility over the temperature range 160–500 K for five samples of molecular-beam epitaxially grown sulfur-doped GaSb. The donor concentration of the different samples varied between 3.3×1017 and 7.5×1016 cm−3, and the native acceptor concentration between 8×1016 and 1.2×1016 cm−3. The samples show a large spread in the apparent carrier activation energy. A two valley compensated conduction model is presented that shows that the variation in apparent carrier activation energy results from different compensation ratios in the samples. This model also shows that the constant value of the Hall coefficient observed at high temperatures is not due to donor exhaustion but carrier promotion to the lower mobility L1 band. Using constraints provided by secondary ion mass spectrometry and capacitance-voltage measurements on the samples, as well as growth data, it is shown that a narrow spread of values for the donor binding energy around 60 meV is required to account for the data. It is suggested that this spread is due to the formation of a donor band and to the strongly attractive central cores of the sulphur donors.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1645-1647 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A deep state possessing similar properties to those reported for DX centers in the AlGaAs system has been observed at atmospheric pressure in GaSb moderately doped with sulfur. The first detailed deep level transient spectroscopy study of this material has revealed a large energy barrier to electron capture and a correspondingly small capture cross section for this deep level. The deep level activity of selenium- and tellurium-doped GaSb has also been investigated.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The variation in stomatal characters in leaves from one Alnus glutinosa (L.) Gaertn. tree is analysed. Measurements were taken from over 70 sites on the abaxial surfaces of representative ‘sun’ and ‘shade’ leaves having the same insertion point. The mean values of stomatal density and index in the shade leaf were significantly lower (71 and 93%, respectively) than those for the sun leaf. Within leaves, up to 2.5-fold differences in stomatal density values were observed. Contour maps derived from the data reveal non-random trends over the leaf surface. Correlations between stomatal density, epidermal cell density and stomatal index indicate that the variation in stomatal density within leaves arose primarily from local differences in stomatal differentiation, rather than from local differences in leaf expansion. This research demonstrates that a high level of variation in stomatal characters occurs both within and between leaves. We conclude that a well-defined sampling strategy should be used when estimating stomatal characters for (tree) leaves. Furthermore, the leaf's insertion point and situation within the tree crown should be taken into account. We discuss the implications of these findings for palaeoclimatic interpretations and emphasize the need for great caution when drawing conclusions based solely on stomatal characters.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Experimental dermatology 2 (1993), S. 0 
    ISSN: 1600-0625
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract Vitiligo is an acquired melanin pigmentary disorder manifesting itself by expanding depigmented lesions of the skin. To date, the etiopathomechanism of vitiligo has not been convincingly elucidated and a number of seemingly mutually opposed hypotheses with equal likelihood still coexist. Concurrent theories on vitiligo etiology, together with supportive evidence, are reviewed here. Due to the observed variation in clinical manifestations of the disease, it seems likely that the etiology of vitiligo may differ among patients. Therefore several theories on vitiligo etiopathogenesis have been combined to formulate a convergence theory for vitiligo. also presented in this article. This theory stales that stress, accumulation of toxic compounds, infection, autoimmunity. mutations, altered cellular environment and impaired melanocyte migration and or proliferation can all contribute to vitiligo etiopathogenesis in varying proportions.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Crystal Growth 127 (1993), S. 703-706 
    ISSN: 0022-0248
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Journal of Crystal Growth 121 (1992), S. 121-131 
    ISSN: 0022-0248
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 10
    ISSN: 1524-475X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Wound healing can be accelerated by removing necrotic tissue. Various methods of wound debridement have been developed, including enzymatic debridement. Recently potent proteolytic enzymes were isolated from the intestine of Euphausia superba (Antarctic krill) that might be useful for degrading necrotic tissue. The purpose of this study was to evaluate the debriding properties of krill enzymes, using a specially designed animal model and a computerized analysis system. In 10 female domestic pigs, each weighing 20 kg, 6 artificial ulcers were made on each animal's back using electrokeratome, followed by application of trichloracetic acid. Ulcers were treated twice daily for 7 days with either krill enzymes at different concentrations or with saline. Reduction of necrotic tissue was measured daily using computerized wound analysis. Histological examination included the determination of bromodeoxyuridine incorporation in order to detect cell proliferation as well as routine stains. The debriding effect of krill enzymes at a concentration of ≥ 3.0 casein units per ml was significantly better than saline control treatment (p 〈 0.05). The effect was dose dependent, and granulation tissue formation was enhanced. In conclusion, krill enzymes are effective in wound debridement, as measured in this animal model.
    Materialart: Digitale Medien
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