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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 6228-6230 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the effects of texture and interfacial roughness on the exchange anisotropy in NiFe/Cu/NiFe/FeMn spin valves with different buffer layers (no buffer, Cu, or FeMn) on Si(100) or Si(111) substrates by magnetron sputtering. The crystalline structure, surface topology, and exchange anisotropy field (Hex) were characterized. The exchange anisotropy was established all in (111), (200), and (220) textured samples and there was no systematic relationship between the type of texture and Hex. However, it was found that Hex increased as the surface roughness decreased. The results lead us to believe that interfacial roughness rather than crystallographic texture controls the development of the exchange anisotropy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background In most epidemiological survey studies, only subjective symptoms and past medical history of asthma have been used as diagnostic criteria. Even though a questionnaire survey can be performed in a large population study at low cost, limitations such as lack of objectivity and poor predictability in non-specific bronchial hyperresponsiveness cannot be avoided.Objectives The purpose of this study was to elucidate the prevalence of current asthma based on questionnaires and methacholine bronchial provocation test, and the prevalence of atopy in Korea.Methods We performed modified ATS respiratory questionnaires and allergen skin-prick test with 10 common inhalant allergens among 3219 subjects aged 7–19 years in Seoul and a rural part of a small city, Chungju in Korea. Methacholine bronchial provocation tests were also performed among those who had asthma symptoms according to the questionnaire. The criteria of asthma was presence of both asthma symptoms and non-specific bronchial hyperresponsiveness. Atopy was defined as when an allergen induced weal size is same or larger than that caused by histamine.Results The prevalence of asthma based on questionnaires and methacholine bronchial provocation tests was 4.6%, while the prevalence of wheeze was 8.2% and 19.3% of total population complained of one or more respiratory symptoms related to asthma on the questionnaires. There was no significant difference according to age, sex and living area. The mean prevalence of atopy was 35.0% and the most common allergens were Dermatophagoides farinae (30.9%), Dermatophagoides pteronyssinus (27.5%), cat fur (20.4%) and cockroach (11.8%). The atopy prevalence in Chungju area was higher than that in Seoul and males showed a higher prevalence than females. The asthma prevalence was higher among atopies (6.8%) than among non-atopies (2.7%). None of questionnaire items were enough to predict the presence of bronchial hyperresponsiveness in terms of sensitivity, specificity and positive predictive value.Conclusion The prevalence rate of current asthma in Korea was 4.6% and the prevalence rate of atopy in Korea was 35.0%. Questionnaire-based surveys are not enough to predict the actual prevalence of asthma.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 26 (1996), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background There have been many studies concerning pathological changes in bronchial mucosa from asthmatics; however, few studies has been carried out to evaluate pathological changes according to the severity of asthma.Objective This study was designed to evaluate the cellular components in bronchoalveolar lavage fluid (BALF) and histologicai abnormalities in asthmatics according to the severity ot asthma.Methods Bronchoalveolar lavages, bronchoscopic biopsies and ultrastructural examinations were performed in 13 asthmatics and 11 (BAL) or four (biopsies) non-asthmatic controls. The proportions of epithelial cells and eosinophils in BALF were significantly increased in asthmatics and showed significant correlations with PC20Meth which reflects bronchial hyperresponsiveness. Light microscopic examination revealed loss of epithelium, inllammatory cell infiltrations and thickening of the basement membrane which also showed significant correlation with PC20Meth. Hypertrophy of airway smooth muscles and hyperplasia of mucous glands were prominent in asthmatics but there was no difference according to the severity of asthma. Ultra-structural examination revealed that basement membrane thickening on light microscopic examination is due to the increased subepithelial collagen deposition with normal thickeness of basal lamina.Conclusion These data suggest that loss of epithelial cells, infiltration of inflammatory cells, especially eosinophils, and increased deposition of subepithelial collagen play major roles in determining the severity of asthma and non-specific bronchial hyperresponsiveness.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2033-2035 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two sources of room temperature visible luminescence are identified from SiO2 films containing ion beam synthesized Si nanocrystals. From a comparison of luminescence spectra and photoluminescence decay lifetime measurements between Xe+-implanted SiO2 films and SiO2 films containing Si nanocrystals, a luminescence feature attributable to defects in the SiO2 matrix is unambiguously identified. Hydrogen passivation of the films selectively quenches the matrix defect luminescence, after which luminescence attributable to Si nanocrystals is evident, with a lifetime on the order of milliseconds. The peak energy of the remaining luminescence attributable to Si nanocrystals "redshifts'' as a function of different processing parameters that might lead to increased nanocrystal size and the intensity is directly correlated to the formation of Si nanocrystals. Upon further annealing hydrogen-passivated samples at low temperatures (〈500 °C), the intensity of nanocrystal luminescence increases by more than a factor of 10. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2511-2513 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Synthesis of Ge nanocrystals in SiO2 films is carried out by precipitation from a supersaturated solid solution of Ge in SiO2 made by Ge ion implantation. The films exhibit strong room-temperature visible photoluminescence. The measured photoluminescence peak energy and lifetimes show poor correlations with nanocrystal size compared to calculations involving radiative recombination of quantum-confined excitons in Ge quantum dots. In addition, the photoluminescence spectra and lifetime measurements show only a weak temperature dependence. These observations strongly suggest that the observed visible luminescence in our samples is not due to the radiative recombination of quantum-confined excitons in Ge nanocrystals. Instead, observations of similar luminescence in Xe+-implanted samples and reversible PL quenching by hydrogen or deuterium suggest that radiative defect centers in the SiO2 matrix are responsible for the observed luminescence. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 125 (1996), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The Late Carboniferous and Permo-Triassic red beds of the Pyeongan Supergroup in the Okcheon zone, southern part of the Korean Peninsula, were found to contain three components of remanence. These components, which are resolved by thermal demagnetization, are characterized by high (Hhc for Late Carboniferous and Hhpc for Permo-Triassic), intermediate (Hm) and low (HI) unblocking temperatures. As the maximum unblocking temperature spectra of the Hhc (Hhpt) component often overlapped the Hm spectra above 680° C, 3° to 5° C steps were needed above 670° C to resolve the Hhc-(Hhpt-) component magnetization.The tilt-corrected mean direction of the Hhc component red beds is D = 255.5°, 1 = -2.4° (α95= 20.8°), and that of the Hhpt component is D = 271.9°, 1= -33.4° (α95= 16.5°). the precisions of mean directions of Hhc and Hhpt components improve after tilt correction and allow the directions to be distinguished from each another. This indicates that both Hhc and Hhpt component magnetizations were acquired during or shortly after the deposition of the red beds.According to micropetrographic observations, the haematite in the red beds can be divided into three types: detrital specularite (A), non-detrital specularite (B), and pigmental haematite (C). Type A grains are tens of micrometres in size, and many of them are martite. the remanent magnetization of type A is possibly depositional remanent magnetization (DRM), post-DRM or chemical remanent magnetization (CRM) acquired close to the deposition time, whereas that of types B and C is of CRM origin acquired during and after folding, respectively. the time of folding is well established as a Triassic to Jurassic event. We believe that the remanent magnetization carried by type A grains is primary, and is correlated to Hhc-(or Hhpt-) component magnetization.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2277
    Keywords: Cardiac donors ; Ultrastructural changes heart, brain death, Triiodothyronine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electromicroscopic examinations were carried out on 30 myocardial biopsies taken from 22 human donor hearts immediately after excision (prestorage) or immediately before transplantation (post-storage). All electron micrographs were independently examined by two morphologists. Eleven structures were examined in each micrograph, and each structure was scored according to the degree of injury. A good interobserver correlation was obtained in 84 % of the structures scored. In the prestorage left ventricular biopsies (n = 11), approximately 20 %–25 % showed moderate to severe ultrastructural injury. The ultrastructural injury observed in the poststorage left ventricular biopsies (n = 15) was no different from that in the prestorage group, particularly injury to the sarcomere and mitochondria. A similar degree and pattern of injury was seen in the right ventricle (n = 4). There was no evidence that an ischemic storage period of less than 6 h increased the degree of injury seen. However, there was a higher incidence of moderate to severe injury in those hearts excised from donors initially dependent on high inotropic support.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 236 (1996), S. 201-214 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract MHD simulation study is performed to investigate magnetic reconnection induced by the Kelvin Helmholtz instability in the initially sheared magnetic field geometry as well as in the uniform magnetic field geometry. Slow mode rarefaction structures seen in the uniform field case are not observed in the sheared field case. Dynamo action is less prominent and the conversion of plasma flow energy into the other forms of energy is also smaller in the sheared field case than in the uniform field case. Momentum transport is mostly due to the hydrodynamic stress in the sheared field case, while the electromagnetic stress is dominant in the uniform field case. The long term evolutions are also markedly different in the two cases. In the uniform field geometry, the magnetic field lines twisted due to the Kelvin Helmholtz instability become reconnected and flattened so that they resume the straight field line structure which resembles the initial field geometry. The magnetic field, however, is not uniform with smaller intensity in the central region where the pressure balance is partially maintained by the enhanced thermal pressure. In the initially sheared magnetic field geometry, magnetic reconnection continues to operate until the end of the simulation and the conversion of the flow energy into the thermal energy is still seen.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 240 (1996), S. 249-261 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract MHD simulation study is performed to investigate magnetic reconnection induced by the Kelvin Helmholtz instability in the parallel configuration of the uniform magnetic field geometry as well as the sheared field geometry. Highly distorted magnetic field lines due to Kelvin Helmholtz instability become reconnected and flattened so that they resume the straight field line structure in the final stage. When the initial magnetic field is sheared, magnetic islands formed as a result of magnetic reconnection are transported toward the weak field region but they soon disappear since these islands are of small scales and suffer strong diffusions. Morphological change in the long term evolution is most dramatic in the small range of magnetic field intensity in both the uniform field case and the sheared field case, which is not too strong to stabilize vortex growing early on or too weak to have negligible effect on the instability. Energy conversion and the momentum transport are also most effective in this small range.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 1177-1189 
    ISSN: 1572-8943
    Keywords: DSC ; mercury porosimetry ; pore size distribution ; porous glass ; thermoporosimetry ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pore size distributions (PSDs) of microporous glass, which were controlled by acid leaching subsequent to phase separation of CaO-Al2O3-B2O3-SiO2 glass, were determined via both mercury porosimetry and thermoporosimetry (thermal porosimetry). As a result, the pore radii, the cumulative pore volumes, and the surface areas determined via thermoporosimetry were in good agreement with those determined via mercury porosimetry. It was revealed that thermoporosimetry could be applied to pore structure analysis for porous materials having pore sizes at least up to 58 nm in radius.
    Type of Medium: Electronic Resource
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