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  • 1
    Electronic Resource
    Electronic Resource
    Electrochemical study of surface oxidation and collectorless flotation of arsenopyrite (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 1095-1103 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The surface oxidation of arsenopyrite in alkaline solutions has been studied by cyclic voltammetry. The initial oxidation of arsenopyrite surface produces ferric hydroxide and a realgar-like compound according to the following rection: At higher potentials, the oxidation of arsenopyrite results in elemental sulphur and arsenate according to the following overall reaction: $$FeAsS + 3H_2 O - \to Fe(OH)_3 + HASO_4^{2 - } + S^0 + 10H^ + + 8e^ -$$ Ferric hydroxide is precipitated and arsenate stays on the surface. Both elemental sulphur and realgar (AsS) are retained on the arsenopyrite substrate. Oxidation of arsenopyrite surfaces is not affected by potential cycling or by the presence of arsenic or sulphide species. The oxidation of hydroxyl ions takes place simultaneously with the arsenopyrite oxidation. Flotation tests demonstrated that freshly ground arsenopyrite is non-floatable in the absence of xanthate as collector. Good flotation was obtained for both freshly ground and aged arsenopyrite in the presence of EDTA. The flotation results support the reactions for arsenopyrite oxidation drawn from the electrochemical studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029592
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  • 2
    Electronic Resource
    Electronic Resource
    The surface oxidation of pyrite in alkaline solution (1990)
    Springer
    Journal of applied electrochemistry 20 (1990), S. 1033-1039 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The collector-less flotation of pyrite has been studied by conventional techniques and is correlated to the electrochemical behaviour of pyrite in alkaline solution (1m NaClO4, pH 11). It was concluded that the initial oxidation of pyrite produces a hydrophobic sulphur rich surface together with hydrophilic iron hydroxide species. Also upon grinding, the surface is covered by hydrophilic species and therefore no significant flotation was obtained in the absence of a collector. However, collectorless flotation was readily obtained in an iron complexing solution like EDTA. This indicates that the remaining sulphur-rich layer is responsible for the floatability of pyrite under these conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01019585
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  • 3
    Electronic Resource
    Electronic Resource
    Some remarks on Witten's method. Poincaré-Hopf theorem and Atiyah-Bott formula (1987)
    Springer
    Annals of global analysis and geometry 5 (1987), S. 161-178 
    Details
    ISSN: 1572-9060
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00128018
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of electron-interface-phonon interactions on interactions between electrons in double-heterostructures (1994)
    Springer
    The European physical journal 95 (1994), S. 225-229 
    Details
    ISSN: 1434-6036
    Keywords: 71.35.+z ; 73.20.Dx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Effects of electron-interface-phonon interaction on the interaction between electrons in double heterostructures are considered. It is found that the interaction potential between electrons caused by each of four interface-phonon modes is different. For electrons moving at the two interfaces of double heterostructure, the interaction energies of the electrons produced by the interaction with antisymmetric modes are positive which indicate that the forces between electrons are repulsive. The interaction energies caused by interaction with symmetric modes are negative and the forces are attractive. The resultant of the forces are attractive and become larger when the width of potential barrier decreases for InAs/GaSb/InAs double heterostructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01312195
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  • 5
    Electronic Resource
    Electronic Resource
    Observation of collimation and decollimation of an atomic beam in a misaligned standing wave (1994)
    Springer
    Applied physics 58 (1994), S. 327-331 
    Details
    ISSN: 1432-0649
    Keywords: 32.80.Pj ; 42.50.Vk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper reports an experimental study on the collimation and decollimation of an atomic beam in a misaligned standing wave, in which the effective detuning caused by the Doppler effect is affected by the longitudinal velocity of the atomic beam. The experiment shows that in a strong field with red detuning between laser field and atomic transition frequency, laser heating in a normal standing wave becomes laser cooling in a misaligned standing wave for an approriate misalignment angle. For blue detuning, laser cooling in a standing wave can also become laser heating in a misaligned standing wave for an appropriate condition. These results ca be used in controling atomic motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082629
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  • 6
    Electronic Resource
    Electronic Resource
    Morphology of a ‘superfast’ Mid-Ocean Ridge crest and flanks: The East Pacific Rise, 7°–9° S (1993)
    Springer
    Marine geophysical researches 15 (1993), S. 65-75 
    Details
    ISSN: 1573-0581
    Keywords: East Pacific Rise ; multibeam sonar surveying ; Mid-Ocean Ridge ; magmatic plumbing system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Detailed bathymetric data from a Hydrosweep multibeam sonar survey of a 250 km-long portion of the ‘superfast’-spreading southern East Pacific Rise crest and flanks show that the along-axis variation in morphology and axial depth differs significantly from that observed at the fast-spreading northern East Pacific Rise. While the deep mantle upwelling pattern is similar under the northern and southern East Pacific Rise, our observations require that the connectivity of the shallow, subcrestal plumbing system be more efficient beneath the ‘super-fast’ spreading southern East Pacific Rise than beneath the slower spreading northern East Pacific Rise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01204152
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  • 7
    Electronic Resource
    Electronic Resource
    Homoclinic orbits and mixed-mode oscillations in far-from-equilibrium systems (1987)
    Springer
    Journal of statistical physics 48 (1987), S. 151-199 
    Details
    ISSN: 1572-9613
    Keywords: Homoclinic tangency ; bifurcation theory ; periodic attractors ; chaos ; hyperbolic repellor ; symbolic dynamics ; chemical thermokinetics ; cool flame-ignition oscillations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonlinear autonomous dynamical systems with ahomoclinic tangency to a periodic orbit are investigated. We study the bifurcation sequences of the mixed-mode oscillations generated by the homoclinicity, which are shown to belong to two different types, depending on the nature of the Liapunov numbers of the basic periodic orbit. A detailed numerical analysis is carried out to show how the existence of a tangent homoclinic orbit allows us to understand in a quantitative way a particular and regular sequence of cool flame-ignition oscillations observed in a thermokinetic model of hydrocarbon oxidation. Chaotic cool flame oscillations are also observed in the same model. When the control parameter crosses a critical value, this chaotic set of trajectories becomes globally unstable and forms a Cantor-like hyperbolic repellor, and the ignition mechanism generates ahomoclinic tangency to the Cantor set of trajectories. The complex bifurcation diagram may be globally reconstructed from a one-dimensional dynamical system, thanks to the strong contractivity of thermokinetics. It is found that a symbolic dynamics with three symbols is necessary to classify the periodic windows of the complex bifurcation sequence observed numerically in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01010405
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  • 8
    Electronic Resource
    Electronic Resource
    Monte-Carlo study of reactive ion-beam assisted film growth (1993)
    Springer
    Applied physics 56 (1993), S. 561-565 
    Details
    ISSN: 1432-0630
    Keywords: 68.55 ; 79.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A Monte-Carlo computer program which is composed of ion implantation simulation and deposition calculation is described. It is applied to study TiN film growth by reactive ion-beam assisted deposition in a N2 gas environment. The relationship between film composition and nitrogen partial pressure in the processing chamber is established. The influence of ion energy, atomic arrival rate ratio and ion species on the thickness of the film is studied. We also investigated the intermixing at the interface region between the film and substrate. The calculated data are compared with experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331405
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  • 9
    Electronic Resource
    Electronic Resource
    In situ preparation of Bi-Sr-Ca-Cu-O superconducting films by laser sputtering (1989)
    Springer
    Applied physics 49 (1989), S. 221-223 
    Details
    ISSN: 1432-0630
    Keywords: 74.70 ; 42.60 ; 81.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Superconducting films of Bi-Sr-Ca-Cu-O on (100) MgO substrates have been fabricated by XeCl-excimer-laser sputtering from ceramic targets of Bi2.5Sr2Ca2Cu3Oy in O2 atmosphere. The films were polycrystalline with the c-axis (30.80±0.02Å) preferably oriented normal to the substrate surface. Without post-annealing the films showed metallic resistance behavior with zero resistance temperatures of up to Tc(0) }- 79 K. The critical current density of the films had values of up to jc(50K)}- 104 A/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616303
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  • 10
    Electronic Resource
    Electronic Resource
    Superconductivity of Bi2 (Sr0.9Ca0.1)2 CuO y single crystals (1994)
    Springer
    Applied physics 58 (1994), S. 73-75 
    Details
    ISSN: 1432-0630
    Keywords: 74.62Bf ; 74.25−9
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Bi2 (Sr0.9Ca0.1)2 CuO y single crystals were grown by the self-flux method. The temperature dependence of resistance and ac susceptibility measurements showed that the as-grown crystal is semiconductive between 4.2 K and 300 K. However, after annealing in air for more than 20 days the crystal became superconducting with a T c of 66 K obtained from the R-T curve. The ac susceptibility data also showed a strong superconducting transition at 71 K. X-ray diffraction indicated that the structure of the as-grown and the annealed crystal both are orthorhombic. The T c of 71 K of the Bi2 (Sr0.9Ca0.1)2 CuO y crystal may be due to the increase of oxygen content in the crystal after the long-time annealing in air. It is suggested that the superconductivity of the Ca-doped 2201 phase of the Bi-based system, which up to now was found to have a T c=7–22 K, is similar to the 2201 phase of the Tl-based system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331520
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