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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of experimental and theoretical physics 87 (1998), S. 186-199 
    ISSN: 1090-6509
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract First-principles calculations are performed relating to the stability of a series of perovskite crystals with respect to transition to the ferroelectric and the antiferroelectric state. The calculations employ the generalized Gordon-Kim method, in which the total charge density of an ionic crystal is represented as a superposition of the densities of the individual ions. In the spirit of the nonequilibrium thermodynamics of Leontovich the charge density of an individual ion is calculated in the presence of external auxiliary fields which deform this density. Multipole deformations up to quadrupole are taken into account. The actual magnitude of the deformation is found by minimizing the total energy of the crystal in the Thomas-Fermi-Dirac approximation. The calculated values of the ion shifts in the ferroelectric phase for BaTiO3, and also the electron contribution to the dielectric constant ε ∞ and the dynamic Born effective charges Z eff are found to be in good agreement with the experimental data. The proposed method allows one to obtain an analytical expression for ε ∞, Z eff, and the dynamic vibration matrix. It is shown that these expressions formally coincide with the expressions arising in the phenomenological models of the polarized and deformed ion. Analysis of the expressions obtained confirms the validity of the classical theory of ferroelectrics of displacement type for perovskite crystals.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Crystallography reports 45 (2000), S. 487-492 
    ISSN: 1063-7745
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Propagation of electromagnetic waves in stratified bianisotropic chiral structures is described by the 4 × 4 matrix method. At arbitrary layer parameters, the amplitude and the polarization characteristics (intensity, polarization azimuth, and ellipticity) of reflected and transmitted electromagnetic waves are studied as functions of the angle of the wave incidence onto the structure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Crystallography reports 45 (2000), S. 827-832 
    ISSN: 1063-7745
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reflection and transmission of light in anisotropic planar structures consisting of layers coherently and incoherently interacting with light have been considered. The reflection and transmission matrices for mul-tilayered structures are obtained for the general case of an arbitrary incidence angle. The optical characteristics of the structure are studied as functions of its parameters for the particular case of a magneto-gyrotropic film on the substrate.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1063-7788
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This article reports the results of experiments aimed at producing hypothetical long-lived superheavy elements located near the spherical-shell closures with Z≥114 and N≥72. For the synthesis of superheavy nuclei, we used a combination of neutron-rich reaction partners, with a 244Pu target and a 48Ca projectile. The sensitivity of the present experiment exceeded by more than two orders of magnitude previous attempts at synthesizing superheavy nuclides in reactions of 48Ca projectiles with actinide targets. We observed new decay sequences of genetically linked alpha decays terminated by spontaneous fission. The high measured alpha-particle energies, together with the long decay times and spontaneous fission terminating the chains, offer evidence for the decay of nuclei with high atomic numbers. The decay properties of the synthesized nuclei are consistent with the consecutive alpha decays originating from the parent nuclides 288,289114, produced in the 3n-and 4n-evaporation channels with cross sections of about a picobarn. The present observations can be considered experimental evidence for the existence of the “island of stability” of superheavy elements and are discussed in terms of modern theoretical approaches.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical sciences 37 (1987), S. 1144-1149 
    ISSN: 1573-8795
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider a system of differential equations $$\dot x$$ =P(x,t) + X(x,t), (x,t) ∈ Rn* R where P ∈ C7(Rn* R) and is a positively homogeneous function of x of degree m, larger than one, and the function X is small in comparison with P at infinity. In terms of the Lyapunov-Krasovskii function of the corresponding homogeneous system a certain submanifold of the unit sphere is defined. It is shown that if this submanifold is not contractible, then the quasihomogeneous system being considered has at least one bounded solution. The proof is based on the topological principle of Wazewski.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-8779
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Siberian mathematical journal 27 (1986), S. 187-192 
    ISSN: 1573-9260
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Siberian mathematical journal 32 (1991), S. 28-32 
    ISSN: 1573-9260
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Eignung von (I) als Extraktionsmittel wurde untersucht. Es erwies sich als hochselektives Reagens gegenüber Cu(II). Die pH-Abhängigkeit der Verteilung des Reagens zwischen wäßrigen und organischen Phasen wurde untersucht. Die Verteilungskonstante für Chloroform-Wasser ist logK D =4,24±0,06, für Methylisobutylketon-Wasser logK D =1,15±0,04. Cu(II) wird als Chelat der Zusammensetzung Cu∶L=1∶1 extrahiert. Die Extraktionskonstanten sind: logK ex(CHCl3)=−3,78±0,13 bzw. logK ex(MIBK)=−3,23±0,02. Die Extraktion des Kupfers kann mittels Askorbinsäure beschleunigt werden. Der Einfluß anderer Elemente wurde geprüft: nur Hg2+ und Pd4+ werden deutlich mitextrahiert. Das Verfahren wurde zur Kupferbestimmung in einigen hochreinen Salzen vorgeschlagen. Seine Nachweisgrenze beträgt 0,01 ppm in der organischen Phase.
    Notes: Summary The extraction properties of 6,8,15,17-tetramethyldibenzo-5,9, 14,18-tetra-azacyclotetradecene have been studied. It has been shown that the reagent possesses high selectivity towards copper(II). The pH-dependence of the distribution of the reagent between aqueous and organic phases has been studied. The distribution constants are logK D =4.24±0.06 for chloroform-water and logK D =1.15±0.04 for methyl isobutyl ketone-water. Copper(II) is extracted as the 1∶1 chelate CuL. The extraction constants are logK ex (CHCl3)=−3.78±0.13, logK ex(MIBK)=−3.23±0.08. The copper(II) extraction can be accelerated by introduction of ascorbic acid. The effect of other elements has been investigated, and only Hg2+ and Pd2+ are appreciably extracted. The procedure has been proposed for the extraction and atomic-absorption determination fo copper in some salts of high purity, with a detection limit of 0.01 ppm in the organic phase.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Optics and spectroscopy 89 (2000), S. 737-741 
    ISSN: 1562-6911
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The lateral shift of a light beam reflected from the interface between an optically transparent dielectric and a medium for which the frequency dependences of the real and imaginary parts of the permittivity have a resonant form is investigated. At certain radiation frequencies and angles of incidence, a negative displacement of the reflected beam along the interface takes place.
    Type of Medium: Electronic Resource
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