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  • 1
    Electronic Resource
    Electronic Resource
    Photoconductivity of the germanium-doped solid solution p-GaAs0.94Sb0.06 (1997)
    Springer
    Semiconductors 31 (1997), S. 405-406 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A new mechanism of impurity photoconductivity in semiconductors has been discovered. The form of the long-wavelength photoconductivity spectra observed in p-GaAs0.94Sb0.06: Ge is satisfactorily explained in terms of resonance ionization of impurity levels by phonons excited during absorption of infrared radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187172
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  • 2
    Electronic Resource
    Electronic Resource
    Differential resistance of Au/GaAs1−x Sbx tunneling contacts in the zero-bias anomaly region. I. Contacts to n-GaAs1−x Sbx (1998)
    Springer
    Semiconductors 32 (1998), S. 513-516 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The current-voltage characteristics and the differential resistance R(V)=dV/dI of Au/n-GaAs1−x Sbx tunneling contacts were investigated. Schottky barriers were prepared on n-GaAs1−x Sbx epitaxial layers, which were specially not doped, in the composition range 0.01〈x〈0.125. It was shown that the curves R(V) in the electron density range 2×1018⩽n⩽7×1018 cm−3 and temperature range 4.2⩽T⩽295 K are described well by the tunneling theory employing a self-consistent calculation of the potential in the Schottky barrier region. A square-root dependence of the conductance G(V)=(dV/dI)−1 on the bias voltage V was observed in the zero-bias anomaly region in accordance with the Al’tshuler-Aronov theory of quantum corrections introduced in the density of states at the Fermi level by the characteristic features of the electron-electron interaction in disordered metals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187430
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  • 3
    Electronic Resource
    Electronic Resource
    The T-cell receptor β chain-encoding gene repertoire of a New World primate species, the cotton-top tamarin (1996)
    Springer
    Immunogenetics 45 (1996), S. 151-160 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The New World primate, the cotton-top tamarin (Saguinus oedipus), expresses major histocompatibility complex (MHC) class I molecules with limited diversity. The uniqueness of the cotton-top tamarin MHC class I loci may contribute to this species’ unusual susceptibility to viral infections and high incidence of ulcerative colitis. As a prelude to examining the effect of this limited MHC class I diversity on the tamarin CD8+ T-cell receptor (TCR) repertoire, we identified expressed tamarin TCR β chain (TCRB) cDNAs by anchored and inverse polymerase chain reaction. Sequence alignments and phylogenetic comparisons with human and rhesus macaque sequences identified homologues of 21 human variable (V) gene families. Only single variable region genes were identified in each of these tamarin VB families, with the exception of the VB 5, 9, and 13 families which were comprised of two or three distinct members. The multiple genes within these three VB families do not appear to have separate human homologues, but rather aligned equally well to a single human gene from their respective VB families. These genes appear to have arisen, therefore, by duplication of certain VB genes in the tamarin ancestors following their divergence from the lineage leading to Old World primates and hominoids. Homologues of 12 of the 13 human joining (J) region genes were also identified in the tamarin. Comparison of the proportion of nonsynonymous (pN) and synonymous (pS) substitutions occurring per site within tamarin variable region genes demonstrated a reduction in pN in the framework regions compared with pN in the presumed MHC contact regions (CDR1 and CDR2). Taken together, these findings illustrate that the TCR β chain-encoding genes of the cotton-top tamarin are similar in structure and degree of complexity compared with their Old World primate and human counterparts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050183
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  • 4
    Electronic Resource
    Electronic Resource
    Differential resistance of Au/GaAs1−x Sbx tunneling contacts near the zero-bias anomaly. II. Contacts to p-GaAs1−x Sbx (1998)
    Springer
    Semiconductors 32 (1998), S. 517-520 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The differential resistance R(V)=dV/dI of Au/p-GaAs1−x Sbx tunneling contacts was investigated. Schottky barriers were prepared on epitaxial layers of the solid solution p-GaAs1−x Sbx (0.045〈x〈0.125), which were doped with Ge from 0.01 to 5 at.%. It was shown that substantial features are present in the voltage dependences R(V) for Au/p-GaAs1−x Sbx contacts as compared with the data for Au/n-GaAs1−x Sbx structures. A square-root voltage dependence was observed for the conductance G(V)5(dV/dI)−1 versus the bias voltage V near the zero-bias anomaly, in agreement with Al’tshuler-Aronov theory for quantum corrections introduced in the density of states at the Fermi level by the characteristic features of the electron-electron interaction in disordered metals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187431
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  • 5
    Electronic Resource
    Electronic Resource
    Density-of-states anomaly and tunneling conductance of Au/p-GaAs0.94Sb0.06 contacts near the metal-insulator transition (1998)
    Springer
    Semiconductors 32 (1998), S. 1270-1276 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The tunneling-current anomaly in Au/p-GaAs0.94Sb0.06 contacts at zero bias voltage (V) → 0) is investigated. Epitaxial layers of the solid solution GaAs0.94Sb0.06 are doped with germanium and have a conductivity close to that at the metal-insulator transition. The square-root dependence of the differential conductance G(V)=(dV/dI)−1 at small values of eV〉kT TT predicted by the Al’tshuler-Aronov theory of quantum corrections to the density of states at the Fermi level in disordered conductors is observed. Satisfactory agreement between the experimental data and theory is observed at hole densities (p) in the layers greater than the critical density for the metal-insulator transition p c , but the relative magnitude of the anomaly is sharply smaller at p〈p c . This confirms the specificity of the condition k F l⩾1 (instead of ) for applicability of the theory for the density-of-states anomaly appearing as a result of electron-electron interactions in a three dimensional electron gas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187613
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  • 6
    Electronic Resource
    Electronic Resource
    The quartic anharmonic oscillator and its associated nonconstant magnetic field (1997)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 38 (1997), S. 4887-4899 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Quantum mechanical anharmonic oscillators and Hamiltonians for particles in external magnetic fields are related to representations of nilpotent groups. Using this connection the eigenfunctions of the quartic anharmonic oscillator with potential Vα(x)=(α+(x2/2))2 can be used to determine the eigenfunctions of a charged particle in a nonconstant magnetic field, of the form Bz=β2+β3x. The quartic anharmonic oscillator eigenvalues for low-lying states are obtained numerically and a function which interpolates between α(very-much-less-than)0 (a double harmonic oscillator) and α(very-much-greater-than)0 (a harmonic oscillator) is shown to give a good fit to the numerical data. Approximate expressions for the quartic anharmonic oscillator eigenfunctions are then used to get the eigenfunctions for the magnetic field Hamiltonian. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531924
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallization and preliminary X-ray studies of Pseudomonas putida histidine ammonium-lyase (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 681-683 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Histidine ammonium-lyase from P. putida was expressed in Escherichia coli, purified to homogeneity, and crystallized by the vapour-diffusion method using polyethylene glycol 3350 as the precipitant. The crystals, which diffract to at least 2.5 Å resolution, exhibit the symmetry of space group P212121, with unit-cell parameters a = 89.7, b = 138.2 and c = 164.8 Å. The asymmetric unit contains a tetramer, and the crystals have a Vm value of 2.41 Å3 Da−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444997017848
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of hydrophobic and hydrophilic channel walls on the structure and diffusion of water and ions (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 7985-7999 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular dynamics simulations are carried out to determine the effects of channel wall structure on water and ion properties. We compare hydrophobic (Lennard-Jones 5-3 and atomic) and molecular-hydrophilic cylindrical pores of 2–6 Å in effective radius, relevant to the study of most significant biological ion channels including gramicidin A, ACh, and potassium channels, and to the study of many microporous materials. Large variations in levels of self-diffusion and rotational correlation within hydrophobic channels are explained in terms of water geometry, hydrogen bonding, and dipole correlation. The differing levels of water structure and self-diffusion in hydrophobic and hydrophilic pores arise because of marked differences in the preferred orientation of water dipole moments, and due to hydrogen bonding with molecules on the pore lining. Axial sodium ion diffusion does not experience large variations with pore size, despite anomalous stability in moderate-sized hydrophobic pores. We attribute this to the ability of ions to diffuse along troughs of water density. Ion diffusion along the pore axis exhibits a general increase with channel radius in hydrophobic channels but remains fairly low in hydrophilic channels. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480132
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of Enantiomerically Pure Stereogenically Labile 4-Aryl-2-hydroxytetronic Acids from Enantiomerically Pure Silyl-Protected Mandelaldehydes: aci-Reductone Analogs of Propionic Acid Nonsteroidal Anti-inflammatory Agents (1995)
    s.l. : American Chemical Society
    The @journal of organic chemistry 60 (1995), S. 3334-3341 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00116a015
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  • 10
    Electronic Resource
    Electronic Resource
    Interaction of laminar far wake with a free surface (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 8 (1996), S. 421-429 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Wave disturbances caused by the uniform translatory motion of a submerged body on or beneath the free surface of a viscous fluid are investigated analytically. The submerged body is idealized as an Oseenlet or an Oseen doublet, and exact solutions in closed integral forms are obtained. Based on these exact solutions, asymptotic representations of the wave amplitude for large Reynolds numbers based on the deep-water wavelength at large distances downstream of the body are derived. The results obtained show explicitly the effect of the laminar wake on the amplitude and the phase of the surface waves thus created. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868796
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