Materials Literature
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High-resolution calorimetric studies have been made of the liquid crystal phase transitions for several dispersions of 70-\AA{}-diam silica spheres (aerosil) in octylcyanobiphenyl (8CB) as a function of silica density ${\ensuremath{\rho}}_{S}.$ The excess specific heat peaks associated with the nematic-isotropic $(N\e…
Polarized Raman spectra of single and polycrystalline ${R}_{1\ensuremath{-}x}{A}_{x}{\mathrm{MnO}}_{3} (R=\mathrm{L}\mathrm{a},\mathrm{P}\mathrm{r};A=\mathrm{C}\mathrm{a},\mathrm{S}\mathrm{r})$ ceramic samples were studied as a function of temperature. For the rhombohedral ${\mathrm{LaMnO}}_{3.1}$ and ${\mathrm{La}}_{…
We study theoretically the phase diagram of perovskite manganites taking into account the double degeneracy of the ${e}_{g}$ orbitals in a ${\mathrm{Mn}}^{3+}$ ion. A rich phase diagram is obtained in the mean-field theory at zero temperature as functions of $x$ (hole concentration) and ${J}_{S}$ (antiferromagnetic in…
A new class of soluble electroluminescent poly(p-phenylenevinylene)s (PPVs) is introduced here. Alkoxy-substituted 2-phenyl PPVs (see Figure for a schematic representation) are found to exhibit very good solubility in the conjugated state, good film-forming properties, high molecular weights, and excellent electrolumi…
Abstract Partial oxidation of methane in monolithic catalysts at very short contact times offers a promising route to convert natural gas into syngas (H 2 and CO), which can then be converted to higher alkanes or methanol. Detailed modeling is needed to understand their complex interaction of transport and kinetics in…
Biologically controlled mineralization features an orchestrated balance among various controlling factors such as spatial delineation, template promotion, crystal growth modification and cessation, and so on. Highly ordered calcium carbonate lamellae formed in the nacreous layers of mollusk (aragonite), the foliated c…
Powder X‐ray diffractometry (XRD) and Raman scattering measurements were used to study the structural changes of compositionally homogeneous metastable ZrO 2 solid solutions induced by ScO 1.5 doping. The crystal structures of monoclinic, tetragonal, cubic, and rhombohedral (Sc 2 Zr 7 O 17 , ß‐phase) solid‐solution ph…
A laboratory study was conducted to elucidate the influence of chemical and physical parameters on corrosion of type 1018 carbon steel (CS, UNS G10180) and 5% Cr-0.5% Mo steel in oils containing naphthenic acids (NAs) for application to crude oil refinery systems. Effects of test duration, temperature, and acid concen…
Infrared spectroscopy has been used to analyze the structural changes in samples prepared by the sol-gel method. Silica gels were prepared from alcoholic solutions of tetraethylorthosilicate (TEOS) with different H2O/TEOS molar ratios. The IR spectra of these gels, in the Si–O bond stretching region, shows that their…
Deformation twinning has been studied in a precipitation-strengthened Mg-7.7 at.% Al alloy by transmission electron microscopy. The nature of the interaction between the twins and the second phase was found to be dependent on the relative thickness of the twin and the precipitate. Twins were observed to engulf, bypass…
The Perdew-Burke-Ernzerhof generalized gradient approximation to the density functional theory is tested with respect to sensitivity to the choice of the value of the parameter \ensuremath{\kappa}, which is associated with the degree of localization of the exchange-correlation hole. A study of structural and dynamical…
Electronic transport properties of quasicrystals are discussed theoretically. By means of ab initio linear muffin tin orbitals calculations, electronic band structure and corresponding Fermi surfaces of several quasicrystalline approximants are obtained. A criterion for distinguishing between metallic and anomalous tr…
Calculations of the magnetic entropy change $\ensuremath{\Delta}{S}_{\mathrm{mag}}$ and the magnetocaloric effect (i.e., the adiabatic temperature change) $\ensuremath{\Delta}{T}_{\mathrm{ad}}$ in ${\mathrm{DyAl}}_{2},{\mathrm{ErAl}}_{2},$ and ${\mathrm{DyNi}}_{2}$ using a Hamiltonian that takes into account the effec…
Conjugates between cytochrome c (Cc) and colloidal Au particles have been prepared. These conjugates, purified by centrifugation/resuspension, provide a reproducible means of positioning a biomolecule analyte between two metal surfaces: the metal nanoparticle to which the biomolecule is bound and an aggregated Ag sol…
The introduction of a strong acoustic field to an aqueous solution results in the generation of cavitation microbubbles. The growth and collapse of these microbubbles focuses and transfers energy from the macroscale (acoustic wave) to the microscale (vapor inside the bubbles) producing extremely high localized pressur…
This paper reviews the methods and techniques developed to simulate dislocation dynamics on a mesoscopic scale. Attention is given to techniques of acceleration and to the implementation of special boundary conditions. Typical results concerning the deformation of a bulk crystal, the effect of image forces and the com…
A constitutive framework for the elasto-viscoplastic response of metals that utilizes polycrystal plasticity is presented together with a corresponding numerical integration procedure. The single crystal equations are written in an intermediate configuration obtained by elastically unloading the deformed crystal witho…
The high-temperature resistivity of ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ and ${\mathrm{La}}_{0.7}{\mathrm{Ba}}_{0.3}{\mathrm{MnO}}_{3}$ thin films on various substrates ${\mathrm{LaAlO}}_{3},{\mathrm{SrTiO}}_{3},$ and Si was investigated. We show that the intrinsic resistivity of high-quality epi…
Significant improvements in the fracture resistance of self‐reinforced silicon nitride ceramics have been obtained by tailoring the chemistry of the intergranular amorphous phase. First, the overall microstructure of the material was controlled by incorporation of a fixed amount of elongated ß‐Si 3 N 4 seeds into the…
This paper summarizes the results of a comprehensive experimental study to quantify the effects of strain rate on concrete compressive and tensile strengths. Direct compression and splitting tensile tests were conducted at quasi-static rates (between 10−7/s and 10−5/s) in a standard MTS machine to establish the “stati…