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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1208-1210 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strained-layer (111)B In0.2Ga0.8As/GaAs p-i-n quantum well structures grown with exciton transitions well resolved at room temperature have been studied by photoreflectance spectroscopy. Using the reduced mass deduced from experiments, the built-in electric field in the barrier region is obtained from the above band-gap Franz–Keldysh oscillations. The strain-induced piezoelectric field is then determined directly from a comparison of the periods of Franz–Keldysh oscillations in different samples. Numerical solutions for the exciton transitions from the derived potential profiles are in good agreement with the experimental results. The piezoelectric constant is also determined using the piezoelectric field. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2659-2661 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline thin films of Ba(ZrxTi1−x)O3 with x=0–0.4 and a thickness of ∼180 nm were deposited on platinum-coated silicon substrates by rf magnetron sputtering at 500 °C. Ba-rich targets were used to prepare films of stoichiometric composition. The film having x=0.12 exhibited a satisfactory dielectric property of dielectric constant, k≈300, and dissipation factor, tan δ〈0.02, at frequencies from 103 to 106 Hz under ambient temperatures ranging from 20 to 180 °C. More importantly, the film showed a very stable and highly insulative characteristic against applied voltage. The leakage current density J increases only smoothly to a value less than 10−7 A/cm2 followed by an Ohmic relation of J=σE with σ=1.4×10−14 (Ω cm)−1 up to an extremely high electric field E of 5.6 MV/cm without any sign of abrupt increase of leakage current or electrical breakdown. Also, no time-dependent electric degradation was observed for the film subjected to an electric field as high as 5 MV/cm at room temperature up to 3600 s of measurement. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1629-1630 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion gettering effect has been observed in high-temperature superconducting YBa2Cu3O7 material. Silicon ions were implanted into the material and subsequent high-temperature annealing produced ion movement from a low concentration region to a higher concentration region where the damage of the crystal structure is severe. This gettering effect could be used to make a superconductor-nonsuperconductor-superconductor trilayer structure within a single YBCO film. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 6914-6916 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The title compounds were confirmed to have the Th2Zn17 type rhombohedral structure (space group R3¯m) except for Ho2Fe16Al and Ho2Fe15Al2 which have the Th2Ni17 type hexagonal structure (space group P63/mmc) while Ho2Fe13Al3 is a mixture of the two phases with the hexagonal phase dominant. A larger unit cell favors the formation of an ordered rhombohedral phase rather than a disordered hexagonal phase. Both the substitution of Fe by Al and the insertion of C can expand the cell and lead to the formation of an ordered rhombohedral phase. The site preferences of Al are somewhat different with and without C. In both series, C is mainly found at the 9e interstitial site. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 1595-1601 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InGaAs/GaAs (111)B quantum well p-i-n structures grown by gas source molecular beam epitaxy have been investigated with a photoreflectance technique. Using the reduced mass deduced from experiments, the built-in electric field is obtained from the above band-gap Franz–Keldysh oscillations (FKOs). The strain-induced piezoelectric field is then determined directly from the comparison of the periods of FKOs in different samples. Numerical solutions for exciton transition energies with the experimentally derived potentials are in good agreement with experimental results. Hence, the piezoelectric constant can be determined using the piezoelectric field. The temperature dependences of the quantized energy levels indicate that the influence of temperature on exciton transitions is essentially the same as that of the gaps of the relevant bulk constituent materials. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 39 (1998), S. 329-344 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we consider the second law of thermodynamics for a dissipative system and its symmetry property in terms of contact geometry. We first show that the inaccessibility condition of Caratheodory and the assumption of semipositive definite property of the dissipative energy are equivalent to Clausius' inequality. The inaccessibility condition then gives rise to a generalized Gibbs relation (GGR). By means of the GGR a 1-form ω can be defined such that the zero of ω reproduces the GGR. Such 1-form ω has the property ω∧(dω)n≠0 and ω∧(dω)n+1=0. The integral surface of the GGR is an n-dimensional 1-graph space G (Legendre submanifold) of a 1-jet space J1(En,R), where En is the base space of J1(En,R) with thermodynamic variables as its coordinates. The (2n+1)-dimensional J1(En,R) equipped with the 1-form ω is also called a contact bundle K, where the intensive thermodynamic variables are considered as the contact elements to K at every x. Next we construct an isovector field Xf such that the inaccessibility condition is invariant under the contact transformations generated by Xf. Finally, suppose under some specific assumptions the dynamical equations of the thermodynamic variables x can be approximated by the flow equations of a vector field XG on G. We can lift XG to Xf such that the 1-graph space G as well as the inaccessibility condition are preserved under the contact transformations generated by Xf. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 6854-6860 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report extensive density functional theory calculations, using pseudopotentials with a plane-wave basis, for the properties of the (010) face of molybdenum trioxide (α-MoO3). The surface is modeled by a one-layer slab. Calculated bond lengths compare favorably with experimental measurements. The bonding of the different oxygen species to molybdenum is analyzed using the crystal orbital overlap population. This analysis indicates that the bonding is a combination of ionic and covalent character for all oxygen species. The terminal oxygen exhibits covalent bonding to Mo which is stronger than either of the two bridging oxygens. We also study the adsorption of hydrogen on this surface. Hydrogen is most strongly adsorbed over the terminal oxygen, followed by the asymmetric bridging oxygen, and then the symmetric bridging oxygen. This trend is explained in terms of simple chemical concepts. The inclusion of full surface relaxation is important for even a qualitative description of adsorbate bonding. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, U.K. and Cambridge, USA : Blackwell Publishers
    Plant pathology 47 (1998), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Monarda yellows occurring in southern Alberta was found to be associated with a phytoplasma. Using two pairs of universal primers, 16S ribosomal DNA fragments (about 1.5 and 1.2 kb) were amplified separately by polymerase chain reaction (PCR) from DNA samples that had been extracted from infected monarda. No such DNA bands were observed using DNA samples from uninfected monarda. The DNA fragment (1.2 kb) amplified by nested-PCR was analysed and compared with western aster yellows (AY27, Canada), eastern aster yellows (EAY, USA), French hydrangea aster yellows (AYHF), Belgium hydrangea aster yellows (AYHB), clover proliferation (CP, Canada) and potato witches'-broom (PWB, Canada) by means of restriction fragment length polymorphism (RFLP) using endonucleases AluI, MseI, HpaII, Sau3AI, KpnI and RsaI. The results showed that monarda yellows phytoplasma belongs to the aster yellows subclade and is different from CP and PWB. This is the first report of aster yellows phytoplasma infecting monarda.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 2229-2231 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 0-0 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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