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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of poly(tetramethyldisilylene-co-styrene) (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 5165-5170 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00046a008
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  • 2
    Electronic Resource
    Electronic Resource
    Density functional theory for calculation of elastic properties of orthorhombic crystals: Application to TiSi2 (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 4891-4904 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theoretical formalism to calculate the single crystal elastic constants for orthorhombic crystals from first principle calculations is described. This is applied for TiSi2 and we calculate the elastic constants using a full potential linear muffin-tin orbital method using the local density approximation (LDA) and generalized gradient approximation (GGA). The calculated values compare favorably with recent experimental results. An expression to calculate the bulk modulus along crystallographic axes of single crystals, using elastic constants, has been derived. From this the calculated linear bulk moduli are found to be in good agreement with the experiments. The shear modulus, Young's modulus, and Poisson's ratio for ideal polycrystalline TiSi2 are also calculated and compared with corresponding experimental values. The directional bulk modulus and the Young's modulus for single crystal TiSi2 are estimated from the elastic constants obtained from LDA as well as GGA calculations and are compared with the experimental results. The shear anisotropic factors and anisotropy in the linear bulk modulus are obtained from the single crystal elastic constants. From the site and angular momentum decomposed density of states combined with a charge density analysis and the elastic anisotropies, the chemical bonding nature between the constituents in TiSi2 is analyzed. The Debye temperature is calculated from the average elastic wave velocity obtained from shear and bulk modulus as well as the integration of elastic wave velocities in different directions of the single crystal. The calculated elastic properties are found to be in good agreement with experimental values when the generalized gradient approximation is used for the exchange and correlation potential. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368733
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  • 3
    Electronic Resource
    Electronic Resource
    Itinerant metamagnetism and possible spin transition in LaCoO3 by temperature/hole doping (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 291-303 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic structure of the perovskite La1−xSrxCoO3 has been obtained as a function of Sr substitution and volume from a series of generalized-gradient-corrected, full-potential, spin-density-functional band-structure calculations. The energetics of different spin configurations are estimated using the fixed-spin-moment (FSM) method. From the total energy versus spin magnetic moment curve for LaCoO3 the ground state is found to be nonmagnetic with the Co ions in a low-spin (LS) state, a result that is consistent with the experimental observations. Somewhat higher in energy, we find an intermediate-spin (IS) state with spin moment ∼1.2μB/%f.u. From the anomalous temperature dependent susceptibility along with the observation of an IS state we predict metamagnetism in LaCoO3 originating from an LS-to-IS transition. The IS state is found to be metallic and the high-spin (HS) state of LaCoO3 is predicted to be a half-metallic ferromagnet. With increasing temperature, which is simulated by a corresponding change of the lattice parameters, we have observed the disappearance of the metamagnetic solution that is associated with the IS state. The FSM calculations on La1−xSrxCoO3 suggest that the hole doping stabilizes the IS state and the calculated magnetic moments are in good agreement with the corresponding experimental values. Our calculations show that the HS state cannot be stabilized by temperature or hole doping since the HS state is significantly higher in energy than the LS or IS state. Hence the spin-state transition in LaCoO3 by temperature/hole doping is from an LS to an IS spin state and the present work rules out the other possibilities reported in the literature. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1418001
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  • 4
    Electronic Resource
    Electronic Resource
    Biological control of surface temperature in the Arabian Sea (1991)
    [s.l.] : Nature Publishing Group
    Nature 349 (1991), S. 54-56 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The thermal structure of the surface (mixed) layer of the ocean depends on the various processes acting in it and on it. Heat (sensible and latent) and momentum are exchanged between ocean and atmosphere by turbulent processes acting at the free surface and at the base of the mixed layer5'6. In ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/349054a0
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  • 5
    Electronic Resource
    Electronic Resource
    Desynapsis in Alocasia indica Schott (1972)
    Springer
    Genetica 43 (1972), S. 231-235 
    Details
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: In a culture of Alocasia indica (2n=28), one plant was found to be desynaptic. At pachytene, pairing apparently was complete, but at diakinesis and metaphase I on the average only 2.36 and 1.53 bivalents respectively were found. Desynapsis is of the medium-strong type according to Prakken. Later meiotic stages were irregular and pollen sterility was 95%. The origin must have been spontaneous mutation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123629
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  • 6
    Electronic Resource
    Electronic Resource
    On the method of bae for the determination of kinetic parameters from DTA curves (1980)
    Springer
    Journal of thermal analysis and calorimetry 18 (1980), S. 29-34 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a corrigé l'erreur mathématique de la méthode proposée par Bae pour la détermination des paramètres cinétiques à partir des courbes d'ATD. L'équation proposée ne contient pas de constantes thermiques relatives à l'appareil et peut être appliquée aux courbes d'ATD par une méthode itérative. Les résultats obtenus en appliquant cette équation aux courbes d'ATD expérimentales pour la décomposition du bicarbonate de sodium sont en bon accord avec ceux obtenus à partir de mesures isothermes, même si le porte-échantillon de l'appareil d'ATD est du type coupelle isolée au lieu du type bloc recommandé par Bae.
    Abstract: Zusammenfassung Der mathematische Fehler der von Bae zur Bestimmung kinetischer Parameter aus DTA-Kurven vorgeschlagenen Methode wurde korrigiert. Die vorgeschlagene Gleichung enthält keine thermischen Konstanten der Geräte und kann für DTA-Kurven durch eine iterative Methode angewandt werden. Die durch Anwendung dieser Gleichung bei experimentellen DTA-Kurven der Zersetzung von Natriumbicarbonat erhaltenen Ergebnisse sind mit den aus isothermen Messungen erhaltenen gut vergleichbar, selbst wenn die DTA-Probenbehälter-Zusammenstellung dem isolierten Bächertyp und nicht dem von Bae empfohlenen Blocktyp entsprach.
    Notes: Abstract The mathematical error in the method proposed by Bae for the determination of kinetic parameters from DTA curves has been corrected. The proposed equation does not contain thermal constants of the apparatus, and can be applied to DTA curves by an iterative method. The results obtained by the application of this equation to experimental DTA curves for the decomposition of sodium bicarbonate compared well with those from isothermal measurements, even when the DTA sample holder assembly was of the isolated cup-type instead of the block-type assembly recommended by Bae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01909451
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetic and Thermochemical Parameters for the Reaction Between Lead Oxide and Titanium Dioxide (1999)
    Springer
    Journal of materials science 18 (1999), S. 341-343 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1006655911756
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  • 8
    Electronic Resource
    Electronic Resource
    Electrical resistivity of plasma-sprayed titanium diboride coatings (1993)
    Springer
    Journal of materials science 28 (1993), S. 1655-1658 
    Details
    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 Plasma-sprayed TiB2 coatings (50–600 μm thick) on alumina substrates have been developed and characterized. X-ray diffraction studies, thermal analysis and oxygen analysis of the coatings show that there is appreciable oxidation of TiB2 during the spray process. Partial oxidation of the boride during spraying strongly influences the electrical conductivity of the coatings, which is found to be 100–1000 times less than that of pure TiB2. Although use of argon as shield gas during the spray process brings down the resisitivity substantially, partial oxidation of TiB2 could not be totally avoided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363363
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  • 9
    Electronic Resource
    Electronic Resource
    Oligomerization of styrene over molybdenum oxide on silica-alumina catalyst (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 2133-2144 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Styrene was found to yield saturated and unsaturated linear oligomers in the presence of a surface-supported catalyst, molybdenum oxide on silica-alumina. The reaction rates, the structure, and the molecular weight distribution of the products were found to be controlled by the choice of the solvent. Higher-molecular-weight fractions were favored in isooctane, whereas low-molecular-weight oligomers were preferred in dioxane. The reaction followed first-order kinetics with respect to the monomer. End-group analysis suggests a probable cationic mechanism. Approximate transfer constants KtrKp were deduced from product distribution data. The behavior of the surface-supported catalyst was compared with other cationic catalyst systems.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.170210722
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  • 10
    Electronic Resource
    Electronic Resource
    Correlation of binder mechanical properties with microstructure for poly(butadiene-acrylonitrile-methacrylic acid) terpolymer: 13C-NMR and pyrolysis-GC studies (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 753-766 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 13C-NMR spectroscopy (22.5 MHz) was used to characterize poly(butadiene (B)-acrylonitrile (A)-methacrylic acid (M)) liquid terpolymers prepared by emulsion polymerization. The sequence distribution of the monomers in the terpolymers was described in terms of triads BBB, ABA, ABB, BBA, MBB, and AMB and was found to vary with the mode of addition of methacrylic acid monomer. The NMR data was found to be in good agreement with a mechanism of polymerization in which methacrylic acid is preferentially involved in initiation reactions by a thiyl radical arising from the reaction of the chain modifier, 1-dodecanethiol, and cyanoisopropyl radical generated from AIBN initiator. Binders obtained by curing the liquid terpolymers with an epoxy resin showed widely varying mechanical properties with tensile strength varying from 4.3 to 0.6 kg/cm2 and elongation at break from 130 to 450%. It was found that tensile strength increases and elongation decreases with the number of acrylonitrile units between the methacrylic acid crosslinks. Good correlation was obtained between triad population ratio [ABB + BBA] [BBvB]/[ABA][MBB] and the mechanical properties of the binders. Pyrolysis-GC data at 550 and 600°C confirmed the results obtained from 13C-NMR, and the mole ratio of butadiene to arylonitrile in the pyrolyzates showed correlation with the properties of binders.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420319
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