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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 1503-1509 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dynamics of lithium ions in lithium bismuthate glasses have been studied in the frequency range from 10 Hz to 2 MHz and in the temperature range from 323 to 543 K. The composition dependence of the dc (direct current) conductivity has been explained in terms of the structure of bismuthate glasses. The activation energy has been analyzed in the framework of the Anderson–Stuart model. An additional energy term arising from the Madelung constant of glasses and the polarizability of the bismuth ions has been suggested to explain the discrepancy between the calculated and experimentally obtained values. The relaxation mechanism of these glasses has been explored by employing the modulus and conductivity formalisms and the microscopic parameters obtained from the analysis have been compared. Furthermore, the stretched exponential relaxation parameter and the dc conductivity have been correlated with the decoupling index. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3355-3359 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The preparation of vanadate glasses containing barium oxide and their electrical properties in the temperature range of 80–500 K have been reported in this article. Analysis of the electrical properties has been made in the light of different hopping models. The multiphonon assisted hopping model of small polarons in the nonadiabatic regime, proposed by D. Emin [Phys. Rev. Lett. 32, 303 (1974)] have been observed to describe the temperature dependence of the conductivity data of these glasses over the entire temperature range of measurement. The parameters obtained from the fits of the experimental data to this model are reasonable and consistent with the glass composition. J. Schnakenberg's model [Phys. Status Solidi 28, 623 (1968)] is also consistent with the temperature dependence of the conductivity data. Mott's optical phonon assisted hopping model at high temperatures provides smaller values of the localization length. However, Mott's variable range hopping model is valid at low temperatures. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 3243-3247 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have reported conductivity spectra at different temperatures for fluoride glasses of compositions 0.50ZrF4–(0.40−x)BaF2–0.10YF3–xNaF in the frequency range from 10 Hz to 2 MHz. We have analyzed the spectra using conductivity formalism and obtained the frequency exponent, concentration, and hopping frequency of charge carriers (F− ions) from the analysis. We have observed that the concentration of charge carriers is almost independent of temperature, but weakly dependent on composition, and the conductivity is essentially determined by the hopping frequency, i.e., the mobility. The frequency exponent is independent of temperature, but it shows very weak composition dependence. We have also presented a scaling of the conductivity spectra, which implies that the relaxation dynamics of charge carriers in fluoride glasses is independent of temperature and composition. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 21 (2001), S. 45-51 
    ISSN: 1434-6036
    Keywords: PACS. 71.23.Ft Quasicrystals – 61.44.-n Semi-periodic solids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We present a real space renormalization group (RSRG) method to study the lattice dynamics of a three component Fibonacci (3CF) quasicrystal. Phonon dispersion relations corresponding to different models of this lattice are obtained. Some features of the phonon dispersion curves are compared with experiments on real quasicrystal. It is observed that the positions of the strongest Bragg peaks calculated analytically are in perfect agreement with our RSRG calculations.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 19 (2000), S. 2231-2233 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 19 (2000), S. 41-43 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 57 (2000), S. 141-153 
    ISSN: 1573-0867
    Keywords: competition effects ; dhaincha ; flooding ; grain yield ; intercropping ; N accumulation ; rice varieties ; transplanted rice ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Green manuring of rice with dhaincha (Sesbania aculeata) is widely practised under irrigated puddle-transplanted conditions. In flood-prone lowlands, the rice is established through direct seeding early in the season and flooding occurs after 1–2 months of crop growth following regular rains. The low yields are due to poor crop stands and difficulty in nitrogen management under higher depths of water. The effect of green manuring with dhaincha intercropped with direct-seeded rice vis-à-vis the conventional practice of incorporating pure dhaincha before transplanting was investigated under flood-prone lowland conditions (up to 50–80 cm water depth) at Cuttack, India. Treatment variables studied in different years (1992, 1994 and 1995) were: rice varieties of different plant heights, crop establishment through direct seeding and transplanting, varying length of periods before dhaincha incorporation, and urea N fertilizer levels. Dhaincha accumulated 80–86 kg N ha-1 in pure stand and 58–79 kg N ha-1 when intercropped with direct-seeded rice in alternate rows at 50 days of growth. The growth of rice improved after dhaincha was uprooted manually and buried in situ between the rice rows when water depth was 10–20 cm in the field. The panicle number was lower but the panicle weight was higher with dhaincha green manuring than with recommended level of 40 kg N ha-1 applied as urea. The grain yield was significantly higher with direct seeding than with transplanting due to high water levels (〉60 cm) immediately after transplanting. Dhaincha manuring was at par with 40 kg N ha-1 as urea in increasing the yield of direct-seeded and transplanted crops. The highest yield of direct-seeded crop was obtained when 20 kg N ha-1 was applied at sowing and dhaincha was incorporated at 50 days of growth. The results indicate that green manuring of direct-seeded rice with intercropped dhaincha is beneficial for substituting urea fertilizer up to 40 kg N ha-1 and augmenting crop productivity under flood-prone lowland conditions.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International journal of anthropology 15 (2000), S. 109-124 
    ISSN: 1824-3096
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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