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  • 1
    Digitale Medien
    Digitale Medien
    Nanostructure of thin amorphous hydrogenated carbon films studied by positron annihilation and photoluminescence (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 404-410 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We deposited polymer-like a-C:H films using the plasma-enhanced chemical vapor deposition technique and characterized film microstructure by variable-energy positron lifetime spectroscopy, photoluminescence (PL), and UV-visible absorption spectroscopy. It was confirmed that PL occurs from a chromophore in a sp2 cluster as a result of fast recombination of a photoexcited electron-hole pair. Positron annihilation lifetime spectroscopy showed that positronium (Ps) formation takes place via electron-positron recombination in the sp3 matrix. The lifetime of ortho-positronium (o-Ps) in our a-C:H films was similar to that in polyethylene, indicating their polymer-like nature. The relative PL efficiency increased by about an order of magnitude with increasing film band gap from 1.3 to 3.4 eV, which can be related to the decreasing concentration of nonradiative centers. On the other hand, Ps formation was much less influenced by the band gap and nonradiative centers. Comparison of this result with that for polyethylene mixed with carbon-black nanoparticles, where a considerable reduction in Ps formation was observed, showed that nonradiative centers were of a different nature from the defects on the carbon nanoparticle surface. This work demonstrated the usefulness of positron lifetime spectroscopy combined with optical measurements to study the nanostructure of a-C:H. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1378063
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  • 2
    Digitale Medien
    Digitale Medien
    Adhesion between Te-based alloy films and fluorocarbon sublayers during the ablative hole opening process (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 865-872 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Adhesion between thin Te-based alloy films and fluorocarbon polymer sublayers, prepared by sputtering or plasma polymerization, was investigated by observing the 1 μm-sized ablative hole opening process with a focused laser beam. Interpretations of the mechanisms for the change in energy required for the hole opening and pit geometry were based on the framework of studies of the ablative hole opening process for optical recording. Observations suggest that the molten material flow during the hole opening includes a ductile fracture and a viscous flow of the molten sublayer material as well as of active layer material. Adhesion acts as an energy barrier against the above mentioned flow of molten material during the hole opening process. Since the fluorocarbon films used in the present work had highly cross-linked structures, the adhesion was mainly dominated by the dynamic force of adhesion. Therefore, the hole opening process was mainly affected by the dynamic force of adhesion rather than the static force, which is dominated by the surface energy of the sublayer. There was a good correlation between the dynamic force of adhesion estimated by the peel-off strength and the concentrations of the -CF- and -C-CF- structures estimated from C1s spectra obtained by x-ray photoelectron spectroscopy. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.359011
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  • 3
    Digitale Medien
    Digitale Medien
    Magnetoresistance, Hall effect, and thermoelectric power in spin valves (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5927-5932 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Comparison of the magnetoresistance (MR) on two groups of spin-valve multilayers, NiO/NiFe/Cu/NiFe/Cu/NiO and NiO/NiFe/Cu/NiFe/Cu, has been made in order to investigate the possibility of the enhanced specular scattering at NiO/metal interface. No clear difference in MR between the two systems has been found, suggesting that the enhancement of specular scattering at interfaces is not the origin of the large MR. For the field direction almost perpendicular to the plane, we found a sensitive angular dependence of MR along with a large unidirectional anisotropy. To sort out any specific characteristics of the spin-valve system compared to the multilayers, thermoelectric power and Hall effect have been investigated for the first time. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.367457
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  • 4
    Digitale Medien
    Digitale Medien
    Nanoporous structure of sputter-deposited silicon oxide films characterized by positronium annihilation spectroscopy (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1704-1706 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Positronium annihilation was applied to characterize the nanoporous structure of thin silicon oxide films sputter-deposited at different argon pressures ranging from 0.1 to 2.0 Pa. At higher argon pressures, the 3γ decay probability of ortho-positronium (o-Ps) was substantially enhanced. A comparison of this result with that obtained for capped samples indicated that: (a) 3γ annihilation is due to the intrinsic decay of o-Ps diffusing out from the film into vacuum and (b) films deposited at high argon pressures contain highly connected, open pores. Positron lifetime spectroscopy measurements on the capped films showed that the characteristic size of the pores can be as large as 2.6 nm, depending on the argon pressure. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1428787
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  • 5
    Digitale Medien
    Digitale Medien
    In situ observation of silicon hydrides on Si(100) surfaces during synchrotron-radiation-stimulated Si2H6 gas source molecular beam epitaxy (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2364-2366 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Silicon hydrides (SiHn) on the Si(100) surface during synchrotron-radiation (SR) stimulated Si2H6 gas source molecular beam epitaxy has been observed in situ at low temperatures (≤400 °C), by means of infrared reflection absorption spectroscopy using CoSi2 buried metal layer substrates. At high temperatures (400 °C, 370 °C), SiH is a dominant surface species, while with temperature decrease from 275 to 50 °C, the number of SiH decreases, and, on the other hand, SiH2 and SiH3 appear and increase. This result explains the change of reflection high-energy diffraction pattern from 2×1 to 1×1. The SiH in the bulk network has not been observed. SR irradiation on the film at 140 °C after deposition shows that SiH2 and SiH3 are easily decomposed to SiH and that SiH decomposes much more slowly than SiH2 and SiH3. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.114346
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  • 6
    Digitale Medien
    Digitale Medien
    GaN hexagonal microprisms with smooth vertical facets fabricated by selective metalorganic vapor phase epitaxy (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2196-2198 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Selective growth of GaN was performed by low-pressure metalorganic vapor phase epitaxy using a mask-patterned GaN epitaxial layer on a (0001) sapphire substrate. GaN hexagonal microprisms of 5–16 μm in diameter, with smooth vertical facets and no ridge growth, were fabricated on a (0001) sapphire substrate. This vertical {11¯00} facet of GaN was parallel to a {112¯0} face of the sapphire substrate. Both the use of an epitaxial GaN layer on the sapphire substrate and low working pressure contributed to obtaining smooth top and vertical facet surfaces. Also, the stripe structures of GaN were obtained that had a rectangular cross section. Moreover, the selection of the mask-patterning direction was found to be important because of the 30° rotation of the crystallographic orientation between the GaN layer and the sapphire substrate. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.119379
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  • 7
    Digitale Medien
    Digitale Medien
    Chemical and Histological Characterization of Raw Muscle from Soft and Hard Crabs of Snow Crab Chionoecetes opilio (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 66 (2001), S. 0 
    Details
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: : Chemical analysis showed soft snow crab muscle to have a higher water content and a lower protein content than hard crab muscle. Histological observations revealed frequent occurrences of disintegrated regions in muscle fibers and pericellular connective tissue of soft snow crab muscle tissue. Salinity of the free body fluid recovered from the meropodites of the soft snow crab was significantly higher than that of the hard snow crab. Sensory evaluation revealed differences in texture and taste between soft and hard crabs, which corresponded well to their compositional and histological differences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2621.2001.tb11324.x
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  • 8
    Digitale Medien
    Digitale Medien
    Time-differential perturbed-angular-correlation and emission Moessbauer studies on 99Ru dispersed in YBa2Cu3O6.8 and YBa2Cu3O6 (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 10629-10634 
    Details
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/j100026a029
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  • 9
    Digitale Medien
    Digitale Medien
    Novel dinucleotide repeat polymorphism in the first exon of the STAT-6 gene is associated with allergic diseases (2001)
    Oxford, UK : Blackwell Science, Ltd
    Clinical & experimental allergy 31 (2001), S. 0 
    Details
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background T helper-type 2 cytokines, such as interleukin-4 (IL-4) and IL-13, may play a central role in allergic diseases. The protein known as ‘signal transducers and activators of transcription 6’ (STAT-6) is a key transcription factor involved in both IL-4- and IL-13-mediated biological responses.Objective The objective of this study was to evaluate the possible role of the STAT-6 gene in modulating atopy in the Japanese population.Methods We screened all 23 exons of the STAT-6 gene from 10 subjects for mutations by direct polymerase chain reaction (PCR) sequencing. The STAT-6 gene polymorphisms were genotyped by PCR fragment length polymorphism analysis and PCR-SSCP analysis. The IL-4 receptor Q576R polymorphism was also examined by PCR-SSCP analysis.Results We found a novel dinucleotide repeat polymorphism in the first exon of the STAT-6 gene. The genotypes were classified into four groups according to the number of GT repeats present, from 13 to 16. The frequency of the A1 allele (326 bp, containing 13 repeats of GT) was higher in children with allergic diseases (bronchial asthma, atopic dermatitis and/or food-related anaphylaxis) than controls, although this was not statistically significant (P = 0.0158). In addition, a strong association between the A1 and A3 allele (containing 15 repeats of GT) heterozygote and allergic diseases was identified (P = 0.0002). However, the levels of IgE were not related to the GT repeat polymorphism in the allergic subjects. The GT repeat polymorphism was not associated with the polymorphism in the IL-4 receptorachain gene (Q576R) and there was no association between the G2964A variant and allergic diseases.Conclusion This suggests that genetic variation in the STAT-6 gene may be associated with predisposition to allergic diseases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2222.2001.01191.x
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  • 10
    Digitale Medien
    Digitale Medien
    Increased serum nitrate levels in infants with atopic dermatitis (2001)
    Copenhagen : Munksgaard International Publishers
    Allergy 56 (2001), S. 0 
    Details
    ISSN: 1398-9995
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background: The pathogenesis of atopic dermatitis (AD) is still unknown. A recent study has shown that inducible nitric oxide synthase (iNOS) is expressed in the atopic skin lesion, suggesting the involvement of nitric oxide in the skin inflammation of AD. The purpose of the study was to examine serum nitrate (NO3) levels in relation to the disease severity in children with AD. Methods: Serum nitrate levels were assessed in relation to the skin scores in 88 patients with atopic dermatitis (AD) (aged 0.4–8 years: mean±SD, 2.2±1.9, 41 boys and 47 girls) and 12 nonatopic children (aged 0.8–4 years: mean±SD, 1.8±0.9, seven boys and five girls). Results: Serum nitrate levels of patients with AD were significantly increased as compared to nonatopic controls and were also correlated with the disease severity. The skin scores were significantly correlated with serum nitrate levels as well as peripheral eosinophil counts. Conclusions: Our results indicate that nitric oxide may be involved in the pathogenesis of vasodilation and erythema in AD skin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1034/j.1398-9995.2001.00131.x
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