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  • 1
    Digitale Medien
    Digitale Medien
    Microwave dielectric properties of strained (Ba0.4Sr0.6)TiO3 thin films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 5448-5451 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ferroelectric Ba0.4Sr0.6TiO3 (BST) thin films grown on (001) MgO by pulsed laser deposition show a strong correlation between their structure and their microwave dielectric properties. Epitaxially grown BST films are observed by x-ray diffraction to be tetragonally distorted. The oxygen deposition pressure affects the magnitude of the tetragonal distortion (the ratio of in-plane and surface normal lattice parameters, D=a/c) of the deposited BST films. D varied from 0.996 to 1.004 at oxygen deposition pressure of 10–800 mTorr. The dielectric properties of BST films measured at microwave frequencies (1–20 GHz) exhibit an oxygen deposition pressure dependent dielectric constant (ε=100–600), and quality factor Q (1/tan δ=10–60). The BST film grown at the oxygen deposition pressure of 200 mTorr exhibits the highest figure of merit [% tuning in ε×Q0V, where % tuning is 100×(ε0−εb)/ε0, and ε0 and εb are dielectric constant at 0 and 80 kV/cm]. This corresponds to the film with the lowest distortion (D=1.001). The observed microwave properties of the films are explained by a phenomenological thermodynamic theory based on the strain along in-plane direction of the films. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1314619
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  • 2
    Digitale Medien
    Digitale Medien
    Highly oriented indium tin oxide films for high efficiency organic light-emitting diodes (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5371-5376 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Highly oriented indium tin oxide (ITO) thin films were grown by pulsed-laser deposition (PLD) on glass and single-crystal yttria-stabilized zirconia (YSZ) substrates. The structural, electrical, and optical properties of these films were investigated as a function of oxygen partial pressure. Films were deposited at substrate temperature of 300 °C in mixed gases (12 mTorr of argon and 1–50 mTorr of oxygen) using a KrF excimer laser (248 nm and 30 ns full width at half maximum) at a fluence of 1.2 J/cm2. ITO films (300 nm thick), deposited by PLD on YSZ at 300 °C in a gas mixture of 12 mTorr of argon and 6 mTorr of oxygen, exhibit a low electrical resistivity (1.6×10−4 Ω cm) with a high transparency (∼74%) at 550 nm. ITO films deposited on both glass and YSZ substrates have been used as an anode contact in organic light-emitting diodes. A comparison of the device performance for the two substrates shows that the device fabricated on the ITO/YSZ has a higher external quantum efficiency than that of the device fabricated on the ITO glass.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1461068
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  • 3
    Digitale Medien
    Digitale Medien
    Effect of quench depth on grain structure in quiescently ordered block copolymers (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 10196-10211 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Grain growth in a polystyrene–polyisoprene block copolymer melt is studied by time-resolved depolarized light scattering after a quiescent quench from the disordered to the ordered state. At shallow quench depths, classical nucleation and growth kinetics are observed. Grains comprising the equilibrated ordered phase nucleate and grow by consuming the surrounding disordered phase. In contrast, deep quenches result in the formation of disorganized grains with an average order parameter that is well below the equilibrium value. Small angle neutron scattering and rheological experiments were conducted to facilitate the interpretation of the light scattering data. We show that the nonequilibrium grain structure formed during deep quenches is due to extremely high nucleation density. Under these circumstances, the space required for the formation of equilibrated grains is unavailable. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1357796
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  • 4
    Digitale Medien
    Digitale Medien
    Measurements of the electron temperature by the Thomson scattering system on the Hanbit magnetic mirror device : Papers from the thirteenth topical conference on high temperature plasma diagnostics (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1118-1121 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A Thomson scattering system on the Hanbit magnetic mirror device has been installed to measure the electron temperature and density of the plasma in the central cell. The configuration is based on a standard 90° scattering scheme. The optical system consists of a Q-switched Nd:YAG laser, input optics, collection optics, spectrograph optics, detectors, and a data acquisition system. Although the laser beam path is about 50 m long and the background emissions are not low, the electron temperature measurements have been made at a single point on a shot-by-shot basis, in which the stray light was considerably suppressed by using a beam dump, a viewing dump, and baffles. The measured electron temperature is about 50–70 eV in experiments for plasma production and heating by ICRF of 200-kW-rf power using a slot antenna. A description of the installed system and the experimental results are presented. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1321749
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  • 5
    Digitale Medien
    Digitale Medien
    Microwave properties of tetragonally distorted (Ba0.5Sr0.5)TiO3 thin films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1185-1187 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A strong correlation is observed between the structure and the microwave dielectric properties of epitaxial Ba0.5Sr0.5TiO3 (BST) thin films deposited onto (001) MgO by pulsed laser deposition. Films were deposited at 750 °C in an oxygen pressure that was varied from 3 to 1000 mTorr. The tetragonal distortion (ratio of in-plane and surface normal lattice parameters, D=a/c) of the films depends on the oxygen deposition pressure. D varied from 0.996 at 3 mTorr to 1.003 at 800 mTorr. At microwave frequencies (1–20 GHz), BST films with low distortion have higher dielectric constants (ε∼500), and lower dielectric loss (tan δ∼0.02) compared to films with higher distortion. The correlation of the microwave properties with the film structure can be attributed to stresses and polarizability in the film. The BST film grown at the oxygen deposition pressure of 50 mTorr exhibits a large dielectric constant change and a low dielectric loss at the same time, which corresponds to the film in low stress (D=1.0004). For tunable microwave applications, BST films with low stress are desirable in order to achieve both low dielectric loss and large tunability. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.125977
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  • 6
    Digitale Medien
    Digitale Medien
    Anomalous oxygen annealing effects on La0.7Ca0.3MnO3 films grown on MgO substrates (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 353-355 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Epitaxial La0.7Ca0.3MnO3 thin films were grown on MgO (001) substrates by pulsed laser deposition. The as-grown films exhibit a metal–insulator transition at temperatures ranging from 200 to 230 K. Surprisingly, the transition temperature of postannealed films under O2 at 900 °C decreases by more than 100 K, featured with the colossal magnetoresistance. The O2 annealed films also show thermal hysteresis in resistivity and nonlinear I–V behavior. These results are interpreted in terms of Mn deficiency induced by large structural difference between film and substrate, and also discussed in viewpoint of a percolative phase transition. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1338972
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  • 7
    Digitale Medien
    Digitale Medien
    Alternative methods to describe virulence of Erwinia amylovora and host-plant resistance against fireblight (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant pathology 53 (2004), S. 0 
    Details
    ISSN: 1365-3059
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The evaluation of host-plant susceptibility to Erwinia amylovora and of colonization of host-plant tissue by individual strains was facilitated by labelling the pathogen with green fluorescent protein (GFP). Colonization of apple leaves assayed with a fluorescence microscope was associated with visual disease ratings on plants to describe virulence (= aggressiveness) of the fireblight pathogen. Resistance induced with 2,6-dichloro-isonicotinic acid (INA) and benzo(1,2,3-) thiadiazol-7-carbothioic acid-S-methyl ester (BTH, the active component of BION™) restricted colonization by the pathogen to an area adjacent to the inoculation site. Migration in leaves was associated with symptom formation on pear slices and host plants of mutant strains. Non-virulent E. amylovora mutants did not migrate into the leaf veins and strains with intermediate-to-low virulence moved slowly. To compare the migration efficiency of individual wild-type strains in apple and plum cultivars, a blend of five wild-type E. amylovora strains with specific numbers of short-sequence DNA repeats (SSRs) in the common plasmid pEA29 was applied to distinguish them by PCR. Fast-moving strains identified in the GFP assays were dominant, independent of the apple cultivar. When apple shoots, pear slices or leaves of apple plants were coinoculated with streptomycin (Sm)-resistant strains and the corresponding parent strains, Sm-resistant mutants were able to dominate the wild-type strain for tissue colonization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3059.2004.00954.x
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  • 8
    Digitale Medien
    Digitale Medien
    Immunophenotyping of inflammatory cells in lesional skin of the extrinsic and intrinsic types of atopic dermatitis (2004)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 151 (2004), S. 0 
    Details
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background  There is a subgroup of atopic dermatitis (AD) patients with normal total and specific IgE levels and negative skin tests towards common allergens. This form of the disease has been referred to as the ‘intrinsic’ form of AD. Although previous studies have demonstrated differences in the cytokine profile between the extrinsic and intrinsic subtypes, the pathogenesis of both subtypes of AD remains unclear.Objectives  To compare the inflammatory micromilieu in both forms of AD.Methods Immunophenotyping of the inflammatory cells was performed in lesional and nonlesional skin from 18 patients with extrinsic and 17 with intrinsic AD.Results  Immunohistochemical analysis revealed a high proportion of CD4+ T cells in the dermis, with a similar CD4/CD8 ratio in the two groups. The expression levels of other T-cell markers and epidermal Langerhans cells were increased in both forms of AD. Although the T-cell repertoires in the two subtypes were similar, dermal infiltration of eosinophils and eosinophil granular proteins was more prominent in the extrinsic type than in the intrinsic type. Eotaxin immunoreactivity was also significantly higher in the extrinsic subtype.Conclusions  The data suggest that although the overall inflammatory microenvironment in the two subtypes appears to be similar, differences in T-cell cytokine production might contribute to the differential tissue eosinophilia in these subtypes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2133.2004.06027.x
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  • 9
    Digitale Medien
    Digitale Medien
    Histopathological parameters determining lesion colours in the naevus of Ota: a morphometric study using computer-assisted image analysis (2004)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 150 (2004), S. 0 
    Details
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background  Naevus of Ota manifests various colours ranging from light brown to blue. Naevus colours have been claimed to reflect the depth of melanin pigments but the claim has rarely been substantiated by quantitative studies.Objectives  We attempted both quantitative and qualitative analyses of the naevus of Ota to find out relations between histological patterns or parameters of melanin/melanocytes and lesion colours.Methods  Lesion colours were determined by one of the authors and were confirmed by a separate panel of dermatologists. Forty biopsy specimens of naevus of Ota were evaluated by both computer-assisted quantitative image analysis and a previously proposed conventional pattern analysis.Results  The mean area fraction (AFmean) of melanin, the depth of the maximum area fraction of melanin (level of AFmax) and the depth of the deepest infiltrating melanocyte were significantly greater or deeper for bluish lesions than brownish lesions. Based on the qualitative pattern analysis we found that all the brownish lesions demonstrated superficial dermal melanin pigments, whereas bluish lesions tended to show more heterogeneous histological patterns. Eyelid lesions, all of which were bluish, revealed greater AFmean value than cheek lesions, presenting as either brownish or bluish colours.Conclusions  Quantitative analysis indicated that pigment density measures such as AFmean could be as important as the depth of melanocytes in the explanation of the lesion colours in naevus of Ota. However, qualitative pattern analysis failed to link specific patterns with lesion colours, especially in bluish lesions, probably due to the lack of consideration of the pigment density.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2133.2004.05902.x
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  • 10
    Digitale Medien
    Digitale Medien
    ABUNDANCE OF BOTTLENOSE DOLPHINS IN THE BAYS, SOUNDS, AND ESTUARIES OF NORTH CAROLINA (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 19 (2003), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: We conducted a mark-recapture survey of bottlenose dolphins Tursiops truncatus in the bays, sounds, and estuaries of North Carolina during July 2000, using photographic identification techniques. During this survey we took 7,682 photographs of dolphins and, of these, 3,457 images were of sufficient quality for analysis. We identified 306 dolphins from distinctive nicks and notches on their dorsal fins. Eighry-six dolphins were photographed on more than one occasion during the course of the survey; one dolphin was photographed on four separate days. We then applied the results of our photographic analyses to several mark-recapture models and examined potential violations of the assumptions of these models, including an unexpected correlation between photo quality and mark distinctiveness. Our analysis suggests that our results are robusr to possible violations of these assumptions. The resulting estimates were then scaled to account for the proportion (0.46) of unmarked dolphins in the population. Our best estimate of the number of dolphins present in the inshore waters of North Carolina during July 2000 is 1,033 with a 95% Confidence Interval of 860–1,266 (CV = 0.099). Most dolphins were found in the northern part of the study area, which includes the second largest estuarine system in the United States.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.2003.tb01092.x
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