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  • 1
    Digitale Medien
    Digitale Medien
    Damage formation and substitutionality in 75As++-implanted diamond (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2986-2990 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Rutherford backscattering spectrometry (RBS) has been used to study damage formation and substitutionality in synthetic diamonds implanted with 250-keV 75As++ at either 600 °C or room temperature. Lattice damage following implantation at 600 °C was substantially less than damage following room-temperature implantation and appears to be composed of a higher fraction of extended defects. A significant portion of the As implanted at 600 °C was found to be in substitutional lattice sites with substitutional fractions as high as 50%. Changing the ion flux by three orders of magnitude during high-temperature implantation had no effect on either residual damage or substitutionality as indicated by the RBS analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.349326
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  • 2
    Digitale Medien
    Digitale Medien
    Investigation of the nonlinear behavior of a partially ionized, turbulent plasma in a magnetic field (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 488-499 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In this paper, a number of the methods of nonlinear dynamics are applied to the study of electrostatic turbulence in a magnetized, steady-state, partially ionized plasma. Electrostatic potential fluctuations were obtained by using a capacitative probe. These signals were captured, digitized, and recorded with a LeCroy transient recorder system interfaced to an IBM-AT personal computer. A commercially available software program was used to calculate power spectra, to reconstruct and plot phase portraits, take Poincaré sections, compute correlation dimensions and Lyapunov exponents, and to perform other manipulations of the time series of electrostatic potential fluctuations obtained from the plasma. Evidence of low-dimensional chaos was sought, and trends were investigated which related the state of the turbulence to such plasma parameters as the anode voltage (rms electrostatic potential), background gas pressure (collisionality), and magnetic induction. These variables were found to have a significant effect on the nonlinear dynamics of the plasma.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.346818
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  • 3
    Digitale Medien
    Digitale Medien
    Damage and deuterium trapping in highly-oriented pyrolytic graphite (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2225-2233 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In this work the buildup of damage due to deuterium implantation in highly-oriented pyrolytic graphite (HOPG) is investigated. HOPG was implanted with 10–30 keV D3+ at different target temperatures between room temperature and 773 K with fluences from 1014 to 1018 D/cm2. Subsequently, the damage due to the implantation and the retained deuterium were measured by Rutherford backscattering (RBS) in a channeling direction (RBSc) and by the D(3He, p)α nuclear reaction analysis (NRA), respectively. The damage of selected samples was additionally observed with transmission electron microscopy (TEM). The initial trapping efficiency is unity in the whole temperature and energy range. The maximum retention of the deuterium, however, depends on the temperature and implantation energy. The damage in HOPG measured with RBSc starts to saturate at 5×1015 D/cm2 (295 K) and 1.3×1017 D/cm2 (773 K). Both fluences are well below the fluence at which amorphization is observed in TEM.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.353126
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  • 4
    Digitale Medien
    Digitale Medien
    Kinetics of solid phase epitaxy in thick amorphous Si layers formed by MeV ion implantation (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1340-1342 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The kinetics of solid phase epitaxy (SPE) have been measured in MeV ion-implanted amorphous Si layers up to 5 μm thick. Epitaxial crystallization in these layers occurs at a constant rate throughout the entire film, without loss of interface planarity or competition from random nucleation or twin formation. The activation energy for SPE in thick layers is found to be 2.70 eV, in excellent agreement with the value determined previously in much thinner films. The SPE kinetics are shown not to depend on the implant dose for doses up to 1000 times the threshold for amorphization. The presence of water vapor in the annealing ambient during SPE results in the indiffusion of hydrogen and a concomitant reduction of the SPE growth rate at distances as great as 2 μm from the surface. This effect may have important implications for the development of a microscopic model of the SPE process in silicon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.103477
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  • 5
    Digitale Medien
    Digitale Medien
    Direct molecular-beam epitaxial growth of ZnTe(100) and CdZnTe(100)/ZnTe(100) on Si(100) substrates (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 818-820 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Epitaxial structures of ZnTe(100) and CdZnTe(100)/ZnTe(100) have been deposited by molecular-beam epitaxy onto Si(100) substrates misoriented from 0° to 8° towards the [011] direction. The films were characterized with x-ray diffraction, photoluminescence spectroscopy, optical microscopy, and stylus profilometry. Single-crystal CdZnTe(100) films comparable in structural quality to those obtained with growth on GaAs/Si composite substrates have been demonstrated on both 4° and 8° misoriented Si with the use of ZnTe buffer layers. X-ray rocking curves with FWHM less than 300 arcsec for ZnTe (400) and less than 160 arcsec for CdZnTe(400) have been obtained for as-grown films. Specular surface morphologies, superior to those obtained on GaAs/Si composite substrates, are also observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.109918
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  • 6
    Digitale Medien
    Digitale Medien
    Expression of murine VCAM-1 in vitro and in different models of inflammation in vivo: correlation with immigration of monocytes (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Experimental dermatology 3 (1994), S. 0 
    Details
    ISSN: 1600-0625
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract VCAM-1 (vascular cell adhesion molecule-1) is a cytokine-in-ducible adhesion molecule which is known to mediate adhesion of mononuclear cells to endothelial cells in vitro via binding to the integrin VLA-4 (very late antigen-4). To further elucidate the role and regulation of VCAM-1 in vivo, we compared in vitro and in vivo expression of VCAM-1 in response to cytokines and investigated immunohistochemically the expression of VCAM-1 in three murine models of experimental inflammation. These models differed with regard to the pathogenetic mechanism and the subsequent infiltrate: allergic contact dermatitis (ACD) to DNFB as a T cell-controlled, DTH type of inflammation, cutaneous infection with Leishmania major as a chronic granulomatous inflammation and the cauterized cornea as a model for acute inflammation. VCAM-1 was found to be markedly enhanced on vascular endothelia in all types of inflammation and after subcutaneous administration of LPS and TNF-a. Administration of IL-4, however, failed to induce VCAM-1 both in vivo and in vitro. The increased VCAM-1 expression in the inflammatory models correlated with the appearance of infiltrating monocytes/ macrophages. A concomitant influx of CD4-positive/CD8-positive lymphocytes was only observed in ACD and Leishmaniasis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1600-0625.1994.tb00286.x
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  • 7
    Digitale Medien
    Digitale Medien
    Substance P and calcitonin gene-related peptide modulate leukocyte infiltration to mouse skin during allergic contact dermatitis (1994)
    Springer
    Archives of dermatological research 286 (1994), S. 341-346 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Neuropeptides ; Inflammation ; Macrophages ; Endothelium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) on leukocyte infiltration during allergic contact dermatitis (ACD) in mice were studied. Concomitant topical application of SP or CGRP with the allergen oxazolone resulted in enhanced leukocyte recruitment at the sites of challenge. Immunohistochemical studies revealed that the numbers of T-helper (L3T4+) and cytotoxic (Lyt-2) lymphocytes and infiltrating macrophages (BM8+) were increased. In addition, ICAM-1 and MHC class II molecule expression by these cells was enhanced after neuropeptide application. Analysis by confocal laser scanning microscopy revealed an increase in the immunoreactivity for SP and CGRP in nerve fibres during the course of ACD. Flow cytometry studies showed that SP and CGRP did not upregulate expression of the adhesion molecules ICAM-1 and VCAM-1 by murine endothelial cell lines in vitro. This suggests that increased infiltration of leukocytes during ACD is not a consequence of direct neuropeptide-promoted upregulation of endothelial adhesion molecules in vivo. In conclusion, our observations provide evidence for a modulatory role of neuropeptides in the pathogenesis of ACD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00402226
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  • 8
    Digitale Medien
    Digitale Medien
    Rapid effects of insulin on cyclic GMP location in an intact protozoan (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 476-481 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Insulin ; cyclic GMP ; immunocytology ; Tetrahymena pyriformis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract We studied rapid changes in location of cyclic GMP inTetrahymena pyriformis. Insulin caused cGMP localization in cilia and near the plasma membrane (0.5–1 min). Later (1–5 min) cGMP localization was diffuse in cytoplasm with perinuclear accentuation. Inactive insulin analogs did not elicit these changes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01928167
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  • 9
    Digitale Medien
    Digitale Medien
    Changes in body temperature and circulating levels of interleukin-6 after intra-arterial injections or infusions of tumor necrosis factor α in guinea pigs (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 815-820 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Cytokines ; tumor necrosis factor α ; interleukin-6 ; body temperature ; fever ; radiotelemetry ; guinea pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Tumor necrosis factor α (TNF) is released systematically during the early phase of endotoxin induced fever. To study the effects of this cytokine in guinea pigs, 2 μg TNF were intra-arterially injected as a bolus or slowly infused within 60 min. Both modes of administration induced a biphasic elevation of the animals' abdominal temperature lasting 6 h and stimulated the release of endogenous interleukin-6 (IL-6)-like activity. The second phase of the thermal response and the release of endogenous IL-6-like activity were significantly higher, when TNF was slowly infused into the animals' circulation, in spite of a transiently higher TNF-like activity after the bolus injection of TNF. Both TNF and IL-6 may therefore be regarded as candidates to trigger the febrile response in guinea pigs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01956462
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  • 10
    Digitale Medien
    Digitale Medien
    Interaction of atomic hydrogen with the graphite single-crystal surface (1992)
    Springer
    Applied physics 55 (1992), S. 489-492 
    Details
    ISSN: 1432-0630
    Schlagwort(e): 79.60.−i ; 82.65.−i
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have studied the chemisorption of atomic hydrogen on the basal plane of natural graphite single crystals. LEED and angle-resolved photoemission were used to characterize the clean surface. The adsorption of H saturates at rather low exposures, accompanied by a decrease of the work function by Δφ=(100±20) meV. The photoemission spectra indicate a clear carbon-hydrogen interaction, leading to shifts of substrate bands by up to about 200 meV. No detectable etching of the surface occurs at room temperature, in agreement with earlier work. Our results are qualitatively consistent with theoretical considerations about a strong H(1s)-C(2p z) chemical bond.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00348338
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