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  • 1
    Electronic Resource
    Electronic Resource
    A lattice model describing hydrogen bonding in polymer mixtures (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6166-6174 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A Flory lattice model is used to obtain an expression for the free energy of mixing polymers that hydrogen bond. The derivation is based on the determination of the probability that a mixture of the nonhydrogen bonded chains would spontaneously occur in a configuration equivalent to the hydrogen bonded system. Our result has three parts. The usual contribution to the free energy from mixing covalent chains, a contribution from the hydrogen bonds that is equal to the result that would be obtained if the segments were not covalently linked, and a "correction'' term that accounts for the excess entropy of mixing introduced by the second term. A consequence of this model is that there should be no dependence of the equilibrium constants describing hydrogen bonding upon covalent chain length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458340
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  • 2
    Electronic Resource
    Electronic Resource
    Surface mediated radical recombination luminescence: O+NO+Ni (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 7147-7156 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Results of an experimental investigation of the chemiluminescence produced by the interaction of atomic oxygen and nitric oxide on a nickel foil surface are reported. Visible luminescence which depends linearly on the atomic oxygen and nitric oxide fluxes, on the substrate temperature, and on the substrate temperature history has been observed under conditions for which the three-body gas-phase reaction of O and NO is negligible. The intensity of the luminescence is greater than can be accounted for by the gas-phase two-body radiative recombination reaction of O and NO. The time, flux, and temperature dependences, along with the intensity of the emission support strongly the notion that the observed luminescence stems from excited species, most probably electronically excited NO2, formed in a surface mediated reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454365
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  • 3
    Electronic Resource
    Electronic Resource
    A geometric formulation of the equivalence principle (1995)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 36 (1995), S. 1328-1346 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The principle of equivalence says that at any given space–time point, there exists a local coordinate system with respect to which the three-acceleration of a freely falling test body vanishes regardless of its three-velocity. In this article, a more intrinsic and geometric criterion for free fall motion is provided. The criterion is much simpler than a recently proposed criterion that is based on the Desargues property. For space–times of dimension greater than 2, the Desargues property is a theorem. It is shown that it suffices to require that a version of Pasch's axiom is satisfied; that is, two paths in a plane intersect up to corrections of order cursive-epsilon3, where cursive-epsilon is the scale parameter of a shrinking process. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.531364
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  • 4
    Electronic Resource
    Electronic Resource
    Harmonic analysis of directing fields (1990)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 31 (1990), S. 127-130 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The structure of a directing field is determined by the projective structure of space-time and by various tensor (force) fields. Given a sufficient variety of such directing fields, which can be measured directly given only the ability to track material bodies with respect to an arbitrary coordinate system, it is shown how the projective and tensor fields involved can be determined (and hence measured). This method employs the technique of harmonic analysis on the forward unit hyperboloid. For the important and physically relevant case of an electromagnetic directing field, the projective structure and the electromagnetic field tensor can be determined using only one class of charged monopoles characterized by a given charge-to-mass ratio. The method also provides a new empirical criterion for determining whether or not a directing field is geodesic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528870
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  • 5
    Electronic Resource
    Electronic Resource
    Electron paramagnetic resonance as a quantitative tool for the study of multiwalled carbon nanotubes (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 9788-9793 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have described a method that maximizes the phase separation of graphitic particles (GP) and multiwalled carbon nanotubes (MWNT) in solutions of various organic polymeric hosts. This involves the formation of sediment and a solute. These components were characterized for MWNT and GP content using electron paramagnetic resonance (EPR) measurements. All EPR signals could be deconvoluted into nanotube and GP components. When normalized, these components are representative of the mass of MWNT and GP present. This allows us to make quantitative measurements of nanotube and GP content in different environments. The most successful polymer host was poly (m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) (PmPV). In this case the solute contained 63% of the added nanotubes with only 2% of the added graphite remaining. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1322032
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  • 6
    Electronic Resource
    Electronic Resource
    All directing fields that are polynomial in the (n−1) velocity are geodesic (1989)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 30 (1989), S. 1030-1033 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: It is proven that all directing fields that are polynomial in the (n−1) velocities ξα1 are, in fact, cubic in these variables; so that they are geodesic directing fields (projective structures). This result, in conjunction with previously published work, entails that (n−1) forces must be nonpolynomial in the (n−1) velocities. A large class of acceleration fields that give rise to directing fields is briefly discussed in order to illustrate the source of this nonpolynomial behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528371
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  • 7
    Electronic Resource
    Electronic Resource
    The dependence of DNA tertiary structure on end conditions: Theory and implications for topological transitions (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 10990-10996 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Explicit expressions are derived for the equilibrium configurations of long segments of a DNA double helix subject to boundary conditions of the type imposed by DNA-bending proteins at the ends of otherwise free segments. The expressions, which are exact within the framework of Kirchhoff's theory of elastic rods, show that, in appropriate ranges of parameters, small changes in end conditions can result in large changes in tertiary structure. A discussion is given of the implications of this observation for understanding the action of bending proteins and of proteins that induce topological transitions that change the linking number of closed loops of DNA. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467849
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  • 8
    Electronic Resource
    Electronic Resource
    Theory of the influence of end conditions on self-contact in DNA loops (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 9101-9109 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Explicit solutions of the equations of Kirchhoff's theory of elastic rods are employed to derive properties of the tertiary structure of a looped segment of DNA that is subject to geometric constraints imposed at its end points by bound proteins. In appropriate circumstances small changes in such boundary data cause a nearly planar loop to undergo a continuous and reversible transition that can be described as a 180° rotation taking the loop from an uncrossed to a singly crossed structure in which sequentially separated base pairs are brought into proximity. Expressions are derived relating points and angles of crossing to end conditions, and results are presented that facilitate the calculation of changes in elastic energy during such transitions. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470021
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  • 9
    Electronic Resource
    Electronic Resource
    Strained layer InGaAs channel negative-resistance field-effect transistor (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 378-380 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report experimental results on a negative-resistance field-effect transistor (NERFET), grown by metalorganic chemical vapor deposition, which incorporates a strained In0.18Ga0.82As channel layer adjacent to the barrier. The thin InGaAs layer provides higher mobility and enhanced carrier confinement for the channel electrons. This device structure yields a significant increase in the drain current peak-to-valley ratio over comparable GaAs-AlGaAs NERFETs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342552
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  • 10
    Electronic Resource
    Electronic Resource
    Enhanced brightness in organic light-emitting diodes using a carbon nanotube composite as an electron-transport layer (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 969-975 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the effects of using a composite fabricated from carbon nanotubes and a host polymer, poly(m-phenylene-vinylene-co-2,5-dioctyloxy-p-phenylene-vinylene) (PmPV), as an electron-transport layer in organic light-emitting diodes. Double layer devices using this composite as an electron-transport layer, triple layer devices with a composite electron-transport layer, and poly(9-vinylcarbazole) as a hole-transport layer, as well as poly(2,5-dimethoxy-1,4phenylene-vinylene-2-methoxy- 5(2′-ethylhexyloxy)-1,4-phenylene-vinylene (M3EH-PPV) single layer devices were prepared. Current–voltage–luminance and electroluminescent spectral measurements were performed using six different nanotube powder to polymer mass ratios (0%, 2%, 4%, 8%, 16%, and 32%) for all device structures studied. dc transport and photoluminescence behavior of the polymer-nanotube composite were also investigated. Although a potential barrier is introduced at the M3EH-PPV/composite interface, a significant increase in efficiency was observed using the composite. The best efficiency was obtained for those devices with an electron-transport layer of mass ratio 8%. In addition, on doping with nanotubes, electron conductivity in the composite increased by over 4 orders of magnitude with little quenching of photoluminescence. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1383023
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