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  • 1
    ISSN: 1432-0789
    Keywords: Key words Dead roots ; Fluorescein diacetate-active hyphae ; Field mesocosms ; Live roots ; Mor humus ; Mycorrhizae ; New Jersey Pinelands ; Spodosolic forest soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of live and dead roots on soil fungi were investigated experimentally in a spodosolic soil of the New Jersey Pinelands. Field mesocosm plots were constructed to have a layer of either C- and N-rich organic soil or a vermiculite substitute overlying a layer of sandy mineral soil with a very low organic content. The plots were also supplied with live pitch pine and blueberry roots or dead pitch pine roots in varying quantities based on naturally occurring densities (half, same, and double the ambient quantities). All plots were sampled 1 year after construction (June 1991), and three more times in two subsequent years (November 1991, June 1992, June 1993). In the presence of live roots, fluorescein diacetate-determined (FDA-active) fungal hyphae, total fungal hyphae, and soil moisture decreased significantly in the organic material, while no change was associated with the dead roots. The FDA-active fungal length in the live-root plots ranged from 40 to 165 m g–1 soil, and from 55 to 335 m g–1 soil in the dead-root plots. While the total fungal length in live-root plots remained constant over time (∼3000 m g–1 soil), the total fungal length in the dead-root plots increased from an initial value of 3000 to 〉4000 m g–1 soil at the conclusion of the study. Fungal lengths in mineral soil were higher under organic material than under the vermiculite substitute. Soil moisture was higher in the presence of live roots in mineral soils, but this did not increase the fungal abundance. Inputs of dead roots did not alter the fungal abundance. Overall, we demonstrated that live and dead roots had different effects on fungal abundance in soils with contrasting qualities, and in a spodosolic forest soil, roots could have ecosystem effects very different from those in agricultural soils.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-8663
    Keywords: barium titanate ; BaTiO3 ; ceramics ; ferroelectric thin films ; hydrothermal synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin films of polycrystalline, tetragonal BaTiO3 on oxidized Ti metal substrates were synthesized at 240°C under hydrothermal conditions. Microstructure and electrical properties of the films generated over a four week period of synthesis formed the focus of this study. The films displayed a smooth and shiny surface with a relatively dense structure and no observable cracks. Film thickness reached 0.5 μm after two weeks of synthesis and thereafter remained constant. Diameters of the grains on the film surface were in the range of 1∼2 μm. It is proposed that initial formation of the BaTiO3 film occurs by reaction of Ba2+ with solubilized titanium oxide on the Ti metal surface followed at later stages by an in-situ growth via reaction of TiOx with Ba2+ diffusing through the BaTiO3 film. X-ray diffraction and Raman spectroscopy indicated that the BaTiO3 films are tetragonal, and the films exhibited typical ferroelectric hysteresis loops at room temperature. However, no evidence of the dielectric anomaly (Curie transition) between 30 and 200°C was observed. Dielectric constant of the films at 1 kHz at room temperature was between 400–500. Both dielectric constant and tanδ exhibited low dispersion as a function of frequency at temperatures below 150°C, and the dispersion increased with temperature.
    Type of Medium: Electronic Resource
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