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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and biological properties of 4-amino- and 4-bromo-4-norpyridoxol. New approaches for the modification of the 4 position of vitamin B6 (1976)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 19 (1976), S. 999-1002 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00230a003
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  • 2
    Electronic Resource
    Electronic Resource
    Guanylhydrazones with potential antileukemic activity. 1. Aza analogs of 4,4'-diacetyldiphenylurea bis(guanylhydrazone) (1973)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 16 (1973), S. 959-961 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00266a025
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  • 3
    Electronic Resource
    Electronic Resource
    Photoacoustic spectroscopic estimation of optical absorption and thermal diffusivity of amorphous Ge15AsxSe85−x (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 5292-5296 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoacoustic spectroscopy (PAS) has been applied to measure the composition dependent optical energy gap (Eo), optical absorption coefficient (α), and thermal diffusivity (σs) of glassy Ge15AsxSe85−x (0≤x≤25) alloys. The energy gap is found to decrease with increase of As concentration and shows a threshold behavior around x∼15, which corresponds to the average coordination number 〈r〉∼2.45. This behavior is found to be consistent with the Phillips-Thorpe theory. The variation of the optical gap (Eo) with composition (x) is analyzed on the basis of the Kastner's model of bond energies. The observed exponential edge (Urbach edge) can be considered as an internal Franz-Keldysh effect arising due to the charged impurity generated, as well as "frozen-in'' optical phonon-generated, electric microfields. It could be described in the framework of Tauc and Dow-Redfield model which ascribes the Urbach rule to the ionization of the exciton as an extension of the stark shift. The concentration (x) dependent thermal diffusivity (σs) estimated from the PAS studies also showed a similar critical behavior at the same concentration x (≈15) which arises due to the threshold percolation of rigidity of the system. The measurements of glass transition temperatures (Tg) and the magnetic susceptibilities (χ) of the samples also support this critical behavior around x=15. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363462
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  • 4
    Electronic Resource
    Electronic Resource
    Some analyses of potential profiles of forward-biased high-low junctions (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2496-2501 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A model calculation for the variation of the normalized potential against the normalized position for a forward-biased, below 2 thermal voltage, high-low junction has been made through numerical computations of Poisson's equation. The model is oriented to a junction with a sufficiently large doping difference between the two sides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357022
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  • 5
    Electronic Resource
    Electronic Resource
    Photoacoustic determination of the optical and thermal properties of isovalent S-substituted polymeric Ge–Se system (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 723-728 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Isovalent sulfur (S) -substituted glassy Ge0.05SxSe0.95−x (0≤x≤0.15) alloys have been prepared by quick quenching from the melt. The concentration (x) dependences of optical absorption, band gap, and thermal diffusivity of these alloys have been investigated at room temperature (300 K) by the photoacoustic spectroscopic (PAS) method in the spectral range of 350–800 nm. The small variation of the optical gap E0 with composition is analyzed on the basis of Kastner's model [in the small Ge limit of M. Lannoo and M. Bensoussan, Phys. Rev. B 16, 3546 (1977)], considering the electronegativity difference between the substituting atoms (Se and S) and bond energy calculation. The observed exponential edge (Urbach edge) can be considered as an internal Franz–Keldysh effect arising from the charged impurity-generated as well as "frozen-in'' optical-phonon-generated fields. This can be described in the framework of the Tauc and Dow–Redfield model. The phonon-assisted indirect transition at the band-tail region is also obtained from the present studies. The concentration-dependent thermal diffusivity, estimated from the PAS studies, showed a minimum around x=0.05 similar to the behavior of the observed optical energy gap. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360817
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamics of lithium ions in bismuthate glasses (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 1503-1509 
    Details
    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
    URL: http://dx.doi.org/10.1063/1.480717
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  • 7
    Electronic Resource
    Electronic Resource
    Dielectric relaxation in the lead–iron oxide glass system (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 6310-6313 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dielectric properties of the PbO–Fe2O3 glassy system are reported in the frequency range 102–106 Hz and in the temperature range 300–500 K. The experimental data have been analyzed in the light of the dipolar relaxation model. It is observed that this model is consistent with the frequency and temperature dependence of the complex dielectric constant. The network former PbO influences strongly the dielectric properties, yielding large values of static and high-frequency dielectric constants and a narrow distribution of relaxation times. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473619
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  • 8
    Electronic Resource
    Electronic Resource
    Transport properties of nonconventional lead cuprate glass (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 6270-6274 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dc electrical transport properties of the nonconventional lead cuprate glasses of compositions (CuO)x(PbO)100−x for x=15–50 mol % are reported in the temperature range 150–500 K. The experimental results have been analyzed in the light of existing theoretical models. It has been observed that the high-temperature conductivity data are consistent with Mott's nearest-neighbor hopping model, while at low temperatures Mott's variable-range-hopping model fits the data very well. The polaron hopping models of Schnakenberg and Emin can predict the conductivity data in the entire temperature range of measurement. The percolation model of Triberis and Friedman is not consistent with the experimental results. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470405
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  • 9
    Electronic Resource
    Electronic Resource
    Transport mechanism in nonconventional bismuth cuprate glass (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 10041-10045 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Temperature and compositional dependence of the electrical transport properties of the nonconventional binary bismuth cuprate glasses are reported for the first time. It has been observed that the phonon assisted small polaron hopping model in the nonadiabatic regime is consistent with the data only at high temperatures. The variable range hopping model can fit the low temperature data qualitatively. The polaron hopping models proposed by Schnakenberg [Phys. Status Solidi 28, 623 (1968)] and Emin [Phys. Rev. Lett. 32, 303 (1974)] can predict quantitatively the conductivity data in the entire temperature range of measurement for all glass compositions. The physical parameters obtained from the best fits of these models are found reasonable and consistent with the glass compositions. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471748
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  • 10
    Electronic Resource
    Electronic Resource
    Transport properties of semiconducting ternary vanadate glasses (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 1385-1389 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Measurements are reported for the electrical dc conductivity of the semiconducting vanadium tellurite glasses containing P2O5, Sb2O3, or Bi2O3 in the temperature range 80–450 K. The experimental data have been analyzed in the light of existing theoretical models. It has been observed that the general behavior of the electrical conductivity is similar for all glass compositions. The high temperature conductivity data are consistent with Mott's models of phonon-assisted polaronic hopping in the nonadiabatic regime, while at low temperatures variable range hopping is valid. The small polaron hopping model of Schnakenberg is the best model to interpret the temperature dependence of the activation energy and the conductivity in the entire temperature range. The percolation model applied to the polaron hopping regime is also found to be consistent with the temperature dependence of the conductivity data at high and low temperatures. The various parameters obtained by fitting these models to the experimental data are found to depend on glass forming oxides other than the vanadium oxide. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468924
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