Materials Literature
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The quarter-wavelength (λ∕4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range…
We report optical absorption and luminescence measurements on the $1.4\text{\ensuremath{-}}\mathrm{eV}$ center in diamond. We show that the zero-phonon lines have a temperature-dependent Ni-isotope shift, that the isotopic shifts induced by carbon and nickel are opposite in sign, and that a local vibronic mode is pres…
The effects of Dy addition on the electrical properties of BaTiO 3 have been studied by analyzing equilibrium electrical conductivity as a function of temperature, oxygen partial pressure (Po 2 ) and composition. In(Ba 1- x Dy x )TiO 3+0.5 x , the conductivity follows the -1/4th power dependence of Po 2 at high oxygen…
A method of fabricating gold nanocrystals coated polypyrrole (PPy) tubules was developed by coating carboxylic acid–thiol-capped or citrate-reduced gold nanoparticles on polypyrrole tubule templates. Electrostatic interaction between gold nanoparticles and PPy tubules was used as a driving force for this assembly proc…
The kinetics of the thermal cis-trans isomerization was determined in a series of crown ethers containing the azobenzene moiety incorporated into the crowns of various sizes (10- to 19-membered crowns), dissolved in liquid isooctane and in polymer matrixes (PMMA and polystyrene). The kinetic parameters (activation ene…
Template-directed processes involving polysaccharide, dextran, and preformed zeolite crystals/nanoparticles are used to prepare elaborate porous frameworks of interconnected filaments of NaY zeolite/silica nanoparticles, as well as macroscopic fibers of crystallographically aligned silicalite nanocrystals (see picture…
Silica aerogels were patterned with CdS using a photolithographic technique based on local heating with infrared (IR) light. The solvent of silica hydrogels was exchanged with an aqueous solution of the precursors CdNO3 and NH4OH, all precooled to a temperature of 5°C. Half of the bathing solution was then replaced by…
Second-harmonic microscopy has been applied to characterize the second-order nonlinear layer in fused silica plates thermally poled at 280 °C and 3.5 kV for different time intervals. The nonlinear layer is found only under the anode surface and to be ∼5μm deep under the anode for a poling time of 30 min. Progression o…
Disordered cubic ${\mathrm{ZrMo}}_{2}{\mathrm{O}}_{8}(Pa\overline{3},\phantom{\rule{0.2em}{0ex}}Z=4)$ is known to display isotropic negative thermal expansion (NTE) below 600 K. We report high-pressure inelastic neutron scattering experiments up to 2.5 kbar in this material using the IN6 spectrometer at Institut Laue-…
Magnetic properties of the transition metal oxide $\mathrm{Ba}\mathrm{Co}{\mathrm{O}}_{3}$ are analyzed on the basis of the experimental and theoretical literature available via ab inito calculations. These can be explained by assuming that the material is formed by noninteracting ferromagnetic clusters of about $1.2\…
We report on the heterobimetallic system, Eu[Ag(x)Au(1-x)(CN)(2)](3) (x = 0-1) in which sensitization of europium luminescence occurs by energy transfer from [Ag(x)Au(1-x)(CN)(2)](-) donor excited states. The donor states have energies which are tunable and dependent on the Ag/Au stoichiometric ratio. These layered sy…
Recently, a new family of piezoelectric perovskite materials based on the solid solution (1- x )BiMeO 3 – x PbTiO 3 (where Me is one or a combination of cations with sum valance +3) have been developed. Specifically, the (1- x )BiScO 3 – x PbTiO 3 (BS–PT) system is noted for its high Curie temperature ( T C =450°C) an…
The room temperature thermoelectric figure of merit and power factor are calculated for bulk and nanowires made of CdTe, ZnTe, ZnSe, and ZnS, of the zincblende structure. To this end, an iterative solution of the Boltzmann transport equation is used to obtain the electronic transport properties. The lattice thermal co…
Various polyamine dendrimers with a triethanolamine core inhibit the activity of the Candida ribozyme by forming RNA-dendrimer complexes via electrostatic interactions.
The liquid-phase oxidation of benzene was carried out in aqueous acetic acid solvent over V-substituted heteropolyacids (V−HPAs) using molecular O 2 and ascorbic acid as the oxidant and reducing reagent, respectively. Phenol was exclusively obtained as the oxygenation product. The elimination of the V species from the…
We investigate the possibility to use coated metallic nanoparticles for single-molecule surface-enhanced spectroscopy by extending the Mie theory. The aggregates of metallodielectric spheres of Au and Ag show a strong local intensity enhancement in the cavity between particles, which can result in up to a 1014-fold in…
Molecular dynamics simulations have recently shown that the presence of grown-in twin boundaries in nc-Al promotes slip activity in the form of twin boundary migration. In this letter we investigate the effect of grown-in twin boundaries on the plastic deformation mechanism in nc-Ni and Cu, and show that (1) for these…
Abstract Relationship between the rheological properties and morphology of dynamically vulcanized thermoplastic elastomers (TPVs) based on Ethylene Propylene Diene Monomer (EPDM) and Polypropylene (PP) blends containing 20, 40 and 60% of EPDM were studied. The samples were prepared in a laboratory internal mixer at a…
A novel synthesis of branched poly(methacrylic acid)s (PMAAs) is reported via conventional solution free radical polymerization of MAA with divinylbenzene (DVB) as the branching comonomer. Controlled levels of dodecanethiol (DDT) have been used successfully to inhibit network formation and gelation. Quantitative methy…
Abstract The effects of adding nanoclay to polyamide‐6 (PA‐6) neat resin, and the effects of processing parameters on cell density and size in microcellular injection‐molded components were investigated. In addition, the crystal sizes, structures, and orientation were analyzed with the use of x‐ray diffraction (XRD) a…