Materials Literature
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Abstract This paper describes a material derived from natural sources that can be used to crosslink a variety of polymers over a broad temperature range to produce gels for conformance applications. Delayed crosslinked polymer systems have been used for many years in conformance applications. For the past decade, the…
Metal nanowires exhibit a number of interesting properties: their electrical conductance is quantized, their shot-noise is suppressed by the Pauli principle, and they are remarkably strong and stable. We show that many of these properties can be understood quantitatively using a nanoscale generalization of the free-el…
The GaSb and Ga0.62In0.38Sb nanocrystals were embedded in the SiO2 films by radio-frequency magnetron co-sputtering and were grown on GaSb and Si substrates at different temperatures. We present results on the 10K excitonic photoluminescence (PL) properties of nanocrystalline GaSb and Ga0.62In0.38Sb as a function of t…
A major issue in the development of the technology of nitride based materials is the choice of substrate. The structural and optical properties of the layers are intimately connected to the substrate material used in the epitaxial growth. Key issues include lattice matching of substrate and epitaxial layer and the dif…
Abstract A series of new polyimides containing alicyclic units and alkyloxy side chains were prepared from 9,10‐dialkyloxy‐1,2,3,4,5,6,7,8‐octahydro‐2,3,6,7‐anthracenetetracarboxylic 2,3:6,7‐dianhydrides and various aromatic diamines. Their physical properties and structures were investigated. Polymers were obtained w…
Uniformly BN-coated silicon carbide nanowires have been synthesized via the vapor–liquid–solid growth mechanism. Nanoscale Ni–C grains were used as catalysts and a mixture of boron and silica was heated to simultaneously generate SiO and B2O2 vapors. The uniform coating was explained based on the TEM observations. The…
The reaction of [Mn(dmptacn)OH(2)](2+) and [Ni(dmptacn)OH(2)](2+) (dmptacn = 1,4-bis(2-pyridylmethyl)-1,4,7-triazacyclononane) with each cyano ligand on ferricyanide results in the assembly of heteropolynuclear cations around the cyanometalate core and reduction of Fe(III) to Fe(II). In [[Mn(dmptacn)CN](6)Fe][ClO(4)](…
A conformational analysis is done in order to investigate on the mobility of joints separating d helical sequences from l ones along molecules of polystyrene and polypropylene both isotactic and syndiotactic in solution or in the liquid state. Results indicate that, in the case of isotactic polystyrene, severe interac…
The influence of hydrogenated Si(100) dimers on the geometry and electronic structure of neighboring bare dimers is studied by scanning tunnel microscope (STM) and ab initio calculations. Two coverage regimes are of interest. First, the presence of isolated hydrogenated dimers is shown to perturb neighboring bare dime…
The H-bonding interaction between the oxopurine base hypoxanthine and water is investigated using matrix-isolation FT-IR spectroscopy combined with theoretical density functional theory and ab initio methods. For vibrational frequency predictions, only the DFT/B3-LYP method is used, while for the prediction of relativ…
The nature of the charge carriers in conducting polypyrrole highly doped with p-toluenesulphonate and their behavior under pressure was investigated by high-pressure Raman spectroscopy. Changes of band positions and relative intensities of bands assigned to the radical cation (polaron) or the dication (bipolaron) were…
[reaction: see text] Novel two-dimensional octupoles containing donors at the core and acceptors at the edge of peripheral groups were synthesized by Horner-Wittig reactions. These chromophores show very large first hyperpolarizability and good thermal stability and are attractive candidates for nonlinear optical mate…
In this paper, we present detailed performance analyses of three types of two-stage thermoelectric (TE) coolers, which are supplied with serial, parallel and separate electric currents, respectively, with respect to the ratio n of the TE couple number between the stages. The analyses are all carried out at three optim…
The behavior of the disorder-induced D band in the Raman spectrum of single-wall carbon nanotubes (SWCNT's) was investigated both theoretically and experimentally. The measured maximum position of the D band for SWCNT bundles exhibits an oscillation superimposed on a linear shift, when the laser excitation energy ${E}…
The microscopic mechanism beyond the optical anisotropy of an ionic crystal which occurs for short wavelengths is investigated. The electron-hole, two particle propagator and its analytical behaviour close to the band edge of the one particle continuum plays a major role for the mechanism of this optical anisotropy. E…
We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response is employed to explain the e…
We have performed molecular dynamics simulations to study the effect of an external electric field on a macroion in the solution of multivalent Z:1 salt. To obtain plausible hydrodynamics of the medium, we explicitly make the simulation of many neutral particles along with ions. In a weak electric field, the macroion…
We report a new method of synthesis of an Au nanoparticle-conductive polyaniline composite by using H2O2 both for reduction of HAuCl4 and polymerization of aniline in the same aqueous medium: the electrical conductivity of the composite has been measured to be two orders of magnitude higher than the polymer itself.
Abstract Plant fibers are of increasing interest for use in composite materials. They are renewable resources and waste management is easier than with glass fibers. In the present study, longitudinal stiffness and strength as well as morphology of unidirectional sisal–epoxy composites manufactured by resin transfer mo…
The behavior of the Fréedericksz threshold voltage of a planarly oriented sample filled with liquid crystalline azobenzene material possessing a nematic phase is investigated under UV illumination. It is found that the anchoring strength strongly decreases with the UV-exposure time due to the photoisomerization proces…