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  • 1995-1999  (2)
  • atomic images  (1)
  • forest floor vegetation  (1)
  • 1
    ISSN: 1572-9605
    Keywords: Nd1Ba2Cu3Oy thin film ; scanning probe microscope ; surface stability ; morphology ; atomic images
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Recently, superconducting Nd1Ba2Cu3Oy (Ndl23) thin films with high superconducting transition temperature (T c) have been successfully fabricated at our institute employing the standard laser ablation method. In this paper, we report the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half-integer number of thec-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. This result is supported byI-V STS measurements. The surface morphology of the Nd123 thin films is compared with that of thec-axis-oriented Y1Ba2Cu3Sy thin films. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive. The results of STS measurements together with the fact that we are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5036
    Keywords: acid deposition ; biological neutralization ; dwarf bamboo (Sasa) ; forest floor vegetation ; soil acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Adjacent plots (1 m2) with and without communities of dwarf bamboo (Sasa), i.e. Sasa- and ref-plots, were selected in mountainous areas, which were relatively low in soil buffer capacity. The following parameters were studied: chemical properties of surface (0-30 cm) soil (at 6 sites), elemental abundances in the soil-Sasa ecosystem (at 6 sites), effect of artificial acid rain on the above two parameters (at 1 site), and chemical properties of throughfall and stemflow of Sasa (at 2 sites including one on a plain). Average values of pH(H2O), base saturation and the ratio of exchangeable (K+Mg+Ca)/exchangeable Al in surface soil were 4.35±0. 53, 25.2±14.3% and 0.41±0.28, respectively, in Sasa-plots and 4.26±0.63, 20.0±9.6%, and 0.28±0.13, respectively, in ref-plots. Though not significant, all soil parameters had higher values in Sasa-plots, i.e. Δx = ca. 0.1 unit, 5% and 0.13, respectively. When the abundance of elements (exchangeable cations in soil of 30 cm depth plus elements in litter and Sasa biomass) in the ecosystem was compared between the two plots, K (and often other basic cations) was higher in Sasa-plots than in ref-plots, whereas Al was lower. Artificial acid rain (1.5 L of 0.05 M H2SO4 applied monthly for 10 months) induced a reduction of Na, K, Mg and Ca in a ref-plot, but in a Sasa-plot only Na and K were reduced whereas Mg and Ca were completely retained. The composite samples of throughfall and stemflow of Sasa were ca. 0.5 higher in pH and richer in K, Mg and Ca than the ambient precipitation. The amounts (equivalents) of elements released by Sasa were in the order K 〉 Ca 〉 Mg. It was determined that about 87% and 98% of K, 76% and 87% of Ca, and 39% and 93% of Mg were of Sasa origin in the composite samples at a mountainous site (cambisol soil type) and a plain site (andosol soil type), respectively. Sasa communities may have a significant role in retention of basic cations in surface soil and prevention of soil acidification because of recycling elements in the soil-Sasa ecosystem.
    Type of Medium: Electronic Resource
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