Materials Literature
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We report on the pressure dependence of the local segmental and normal modes of a type-A polymer (polyisoprene) using dielectric spectroscopy. We find that external pressure exerts a stronger influence on the dynamics of the segmental mode as compared to the longest normal mode which results in the crossing of the two…
The interlayer magnetoresistance of layered metals in a tilted magnetic field is calculated for two distinct models for the interlayer transport. The first model involves coherent interlayer transport, and makes use of results of semiclassical or Bloch-Boltzmann transport theory. The second model involves weakly incoh…
Organically capped zinc sulfide nanoparticles doped with different manganese concentrations were prepared under similar conditions. Only the doping concentration was varied. Photoluminescence and electron-spin-resonance (ESR) investigations show some new results. At an optimum concentration of Mn doping a maximum in t…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTA New Approach to Hyperbranched Polymers by Ring-Opening Polymerization of an AB Monomer: 4-(2-Hydroxyethyl)-ε-caprolactoneMingjun Liu, Nikolay Vladimirov, and Jean M. J. FréchetView Author Information Department of Chemistry, Unive…
We previously identified the prpBCDE operon, which encodes catabolic functions required for propionate catabolism in Salmonella typhimurium. Results from (13)C-labeling experiments have identified the route of propionate breakdown and determined the biochemical role of each Prp enzyme in this pathway. The identificati…
Nanocrystalline europium doped yttria was synthesized using a chemical vapor technique. The powder was characterized by x-ray diffraction, transmission electron microscopy, and ultraviolet spectroscopy. For the first time it was possible to obtain single phase Y2O3:Eu nanoparticles crystallized in the cubic structure…
We investigate the phase behavior of symmetric AB diblock copolymers confined into a thin film. The film boundaries are parallel, impenetrable and attract the A component of the diblock copolymer. Using a self-consistent field technique [M. W. Matsen, J. Chem. Phys. 106, 7781 (1997)], we study the ordered phases as a…
We find that solvability theory selects a set of stationary solutions of the Saffman-Taylor problem with coexistence of two \it unequal \rm fingers advancing with the same velocity but with different relative widths $λ_1$ and $λ_2$ and different tip positions. For vanishingly small dimensionless surface tension $d_0$,…
A model is presented for the development of stress during electromigration. Formally similar to a thermal stress model, it provides a method of calculating all of the components of the stress tensor and clearly couples vacancy transport and stress evolution with the boundary conditions that apply to the metal. Analyti…
Magnetoresistance measurements in the CPP geometry have been performed on single electrodeposited Co nanowires exchange biased on one side by a sputtered amorphous GdCo layer. This geometry allows the stabilization of a single domain wall in the Co wire, the thickness of which can be controlled by an external magnetic…
We have developed a pair-potential approach for the evaluation of van der Waals interaction between carbon nanotubes in bundles. Starting from a continuum model, we show that the intertube modes range from 5 ${\mathrm{cm}}^{\ensuremath{-}1}$ to 60 ${\mathrm{cm}}^{\ensuremath{-}1}.$ Using a nonorthogonal tight-binding…
We consider core electron photoemission in a localized system, where there is a charge transfer excitation. Examples are transition metal and rare earth compounds, chemisorption systems, and high-${T}_{c}$ compounds. The system is modeled by three electron levels, one core level, and two outer levels. In the initital…
In this paper we analyze the optical absorption in porous silicon. This is the first attempt to explicitly demonstrate that it is not possible to extract the band gap of low-dimensional nanostructures like porous silicon from a Tauc plot of $\sqrt{\ensuremath{\alpha}\ensuremath{\Elzxh}\ensuremath{\omega}}$ vs \ensurem…
A subazaporphyrin (SubAP), tert -butylated and crowned subphthalocyanines (tBSubPc and SubCRPc), a μ-oxo dimer of tert -butylated SubPc {(tBSubPc) 2 O}, a subnaphthalocyanine (SubNc), and monosubstituted type unsymmetrical phthalocyanine (Pc) and naphthalocyanine (Nc) analogues have been synthesized. In particular, un…
This paper reports two fundamental observations on the size-dependent optical properties of colloidal gold nanoparticles. First, faceted gold nanocrystals in the size range of 63 ± 3 nm have been found to be highly efficient for surface-enhanced Raman scattering (SERS). These nanocrystals are identified from a heterog…
We present an efficient approach to describe the electronic transport properties of extended systems. The method is based on the surface Green's function matching formalism and combines the iterative calculation of transfer matrices with the Landauer formula for the coherent conductance. The scheme is applicable to an…
The compound [Fe(cyclam)(NCS)(2)](TCNQ)(2), where cyclam is 1,4,8,11-tetraazacyclotetradecane and TCNQ is a partially reduced 7,7,8,8-tetracyanoquinodimethane fragment, has been obtained from the corresponding thiocyanate by metathesis reaction. The compound crystallizes in the triclinic system, space group P&onemacr;…
Difunctional hydroxyl-terminated and vinyl-terminated poly(dimethylsiloxane) (PDMS) precursors with similar molecular weight distributions were used to synthesize end-linked networks in bulk with appropriate tetrafunctional cross-linkers. Composite PDMS elastomers from the same precursors were also synthesized with lo…
A conducting polymer, polypyrrole (PPy), has been deposited from aqueous media onto a submicrometer-sized poly(ethylene glycol)-stabilized polystyrene (PS) latex. Deposition experiments were carried out at two different initial pyrrole concentrations, and the latex concentration was systematically adjusted in order to…
An unusual temperature and concentration behavior of resistivity in $La_{0.7}Ca_{0.3}Mn_{1-x}Cu_xO_3$ has been observed at slight $Cu$ doping ($0\leq x \leq 0.05$). Namely, introduction of copper results in a splitting of the resistivity maximum around a metal-insulator transition temperature $T_0(x)$ into two differe…