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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6822-6824 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The observation of a magnetization reversal and a superparamagnetic behavior are reported for films of copper ferrite sputtered in an oxygen atmosphere. X-ray diffraction studies indicate the presence of 14-nm nanoscale crystals of CuFe2O4 in the films. Data on the temperature dependence of the film magnetization M for zero-field-cooled (ZFC) and field-cooled (FC) show that ZFC and FC curves separate at a temperature Tf and that Tf decreases with increasing static field strength. For T〈Tf, M vs T data for low fields indicate the presence of a compensation point in virgin samples. For T(approximately-greater-than)Tf, a superparamagnetic character is evident form the high-field magnetization data. An average cluster size of 16 nm obtained from such data is in excellent agreement with the results of x-ray diffraction studies.
    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 75 (1994), S. 5873-5875 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nature of magnetism and electron paramagnetic resonance (EPR) spin dynamics in 30 A(ring) particles of FeOOH have been investigated in the range 5–350 K. X-ray diffraction shows that the particles are neither α-Fe2O3 nor α-FeOOH based and they convert to Fe3O4 (α-Fe2O3) on heating to 800 K in vacuum (air). Magnetization M vs T data show a blocking temperature TB in the range 40 K〈TB〈100 K so that for T≥100 K, scaling of M with H/T for H up to 50 kOe verifies superparamagnetism. In EPR, both the linewidth ΔH and the g value decreases upon increasing T so that near 300 K, g(approximately-equal-to)2.05 (characteristic of Fe3+). A model of motional narrowing is used to explain the ΔH vs T behavior. The dramatic changes in M, ΔH, g value, and the recoilless fraction of Mössbauer spectroscopy observed near 50 K are all related to the thermal motion of the superparamagnetic nanoscale particles.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 28 (1996), S. 1049-1054 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The injection-locking of an inhomogeneously pumped two-section semiconductor laser enhances continuous wave (CW) operation. The injected signal can be used to change the mode of operation of the laser from pulsation to CW. In the pulsation regime, it causes an increase of the pulsation frequency. In the CW operation regime, the injected signal causes a reduction in the modulation characteristics peak.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1436-5073
    Keywords: gallium determination ; semimethylthymol blue ; spectrophotometry ; visual complexometric titration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The composition, overall stability constant and molar absorptivity of the chelate of gallium(III) ion with semimethylthymol blue, SMTB, were determined spectrophotometrically in acetate buffer (pH 4.5–5). A violet Ga(SMTB) chelate was formed with logarithmic overall stability constant of 18.0±0.1 (I=0.1) and molar absorptivity of 4.25×104l mol−1cm−1 (λmax 580 nm). SMTB is proposed as a new reagent for the spectrophotometric determination of micro-molar amounts of gallium(III). The colour development depends on time, temperature, pH and buffer species. The interference of different cations, anions and organic acids on gallium(III) determination was also investigated. Beer's law was obeyed for 3.5–31.3 μgGa(III)/25ml (0.14–1.25 μg ml−1). SMTB was used for the spectrophotometric determination of gallium in different grade minerals and ores and the results were of acceptable error and relative standard deviation. Comparison between the two suggested methods and atomic absorption spectrometry for Ga(III) determination was carried out.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 52 (1991), S. 237-241 
    ISSN: 1432-0630
    Keywords: 2.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We investigate the effects of the ambient temperature (T), both temperature (T a )and time (t a )of annealing on the electrical conductivity (σ), and the Seebeck coefficient (S) of Sb2Te3. We concluded that both holes and electrons can participate to the conduction process. The material behaves as a semimetal. Although the Seebeck coefficient possesses a plus sign, the coefficient of S vs. $$\frac{1}{T}$$ plots was negative as a degenerate semiconductor. The decrease in value of S with increasing t a was attributed to a corresponding decrease in the amount of positional disorder which acts as an electron trap center.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 37 (1991), S. 813-827 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Im Temperaturbereich 320–500 K wurde das Temperaturleitvermögen, die spezifische Wärme und die Wärmeleitfähigkeit der binären Kompositionen Sb40Te60 bzw. Sb40Se60 und der ternären Komposition Sb40Te30Se30 untersucht. Man fand, daß die Umgebungstemperatur, der Se-Gehalt der Kompositionen und die Meßbedingungen entscheidende Faktoren sind, welche sowohl Wert als auch Verhalten der thermischen Parameter, weiterhin den Mechanismus des Wärmetransportes beeinflussen. Obwohl die untersuchten Kompositionen Halbleiterverhalten zeigten, war die freie Ladungsträgerkomponente der Wärmeleitfähigkeit so gering, daß sie vernachlässigt werden konnte. Somit konnte darauf geschlossen werden, daß die beobachtete Wärmeleitfähigkeit sowohl Photonen- als auch Phononenmechanismen zugeschrieben werden kann.
    Notes: Abstract The thermal diffusivities, specific heats and thermal conductivities of the binary compositions Sb40Te60 and Sb40Se60 and the ternary composition Sb40Te30Se30 were measured in the range ∼320 to 500 K. It was found that the environmental temperature, the content of Se in the composition and the conditions of measurements are decisive factors greatly influencing both the values and the behaviour ot the thermal parameters, and the mechanisms of thermal transport. Although the tested compositions exhibit semiconducting behaviour, the free charge carrier component of the thermal conductivity was so small as to be negligible. Thus, it could be concluded that the observed thermal conductivity is attributable to both photon and phonon mechanisms.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 27 (1992), S. 4685-4689 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Results of differential scanning calorimetry under isothermal and non-isothermal conditions on Bi10Se80In10 glass are reported and discussed. By using the Johnson-Mehl-Avrami equation the activation energies for crystal growth have been evaluated and the crystallization mechanism has been studied. The results indicate that the crystallization process is a two-dimensional growth. The average calculated value of activation energy is 330.2 kJ mol−1for Bi10Se80In10 chalcogenide.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1612-4766
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The braconid parasitoidMeteorus rubens (Nees) is a gregarious larval parasitoid ofAgrotis ipsilon (Hufn.). An olfactometer was used to check the attractiveness of the parasitoid to Hexane extract (kairomone) of its host that could be used in conjunction with releases of natural enemies. Female wasps are attracted in high numbers to the kairomone, compared with males. Respective rates of 94.3 and 22.3% are reported. In the control (no kairomone was used), the corresponding figures are 5.7 and 3.3%.
    Type of Medium: Electronic Resource
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