Materials Literature
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The reaction of a silsesquioxane trisilanol with methylmagnesium chloride leads to an unprecedented tetranuclear magnesium silsesquioxane complex 1 in high yield. The crystal structure shows an unusually short Mg-Cl bond, indicative of an electron-deficient magnesium atom; 1 has been used as transmetalation agent for…
In this article, we present a previously unreported morphology of bacterially precipitated calcite (determined using XRD, FTIR, and SAED) occurring subaqueously in Weebubbie Cave. Observations using FESEM and TEM revealed spindle-shaped crystals with curved [hk.0] faces lying parallel to the c-axis. Calcite precipitat…
The magnetic properties and structural phase transformations of Heusler alloys Ni/sub 2+x/Mn/sub 1-x/Ga and Ni/sub 2-x/Mn/sub 1+x/2/Ga/sub 1+x/2/ were investigated. It was found that the martensitic transformation temperature increases and the Curie temperature decreases with decreasing Mn concentration in the Ni/sub…
We report on an extended x-ray absorption fine structure (EXAFS) investigation on the local atomic order around rare earth (RE) ions in Er+Yb doped aluminophosphate glasses. Samples were obtained from the melt and the RE concentration ranged from 0.5 to 5 wt. %. EXAFS data were analyzed within the multiple scattering…
Cone-shaped pores as well as cylindrical pores with tapered ends of various geometrical forms were produced via one-side etching of latent ion tracks in thin polymer foils by applying a hydrostatically controlled, neutralizing counter solution on the membrane side opposite to the etchant. The sizes and shapes of the p…
Ni/sub 1-2x/Mn/sub x/Ga/sub x/ (x/spl sim/0.2 and 0.25) alloys in thin film form were prepared by ion-beam sputtering from alloy targets. For Si[001] substrates the structure/texture of the films are a function of the growth temperature (T/sub g/). The tetragonal martensite structure with a [220] texture was obtained…
A procedure was developed to fabricate oxide‐fiber‐reinforced minicomposites with a dense matrix and evaluate two oxidation‐resistant interface coatings, porous oxide (zirconia‐silica mixture) and monazite. The coatings were evaluated using Nextel TM 720‐fiber‐reinforced Blackglas TM ‐matrix minicomposites. Boron nitr…
Grafting of 2-hydroxyethyl methacrylate (2-HEMA) onto isotactic polypropylene (iPP) was carried out by free-radical polymerization using supercritical carbon dioxide (SC CO2) as a solvent and swelling agent. The iPP film was first impregnated with the monomer 2-HEMA and initiator benzoyl peroxide (BPO) with SC CO2 at…
The dynamics of ferroelectric liquid crystals confined in porous nitro-cellulose membrane (Synpor) are investigated by broadband dielectric spectroscopy, and a characterization of the mesomorphism is achieved by DSC and X-ray scattering. The complex inner membrane structure of random interconnected voids can be treate…
Molecular dynamics (MD) simulation provides a unique window into the microscopic processes controlling the properties of amorphous silicates of geochemical importance. Of special interest are changes in structure and dynamics around the glass transition temperature. Seventeen simulations for composition CaAl 2 Si 2 O…
CdS aggregates, composed of primary nanocrystalline particles, were synthesized in cyclohexane‐sorbitan monooleate (Span 80) reverse micelles at 80°± 1°C under mechanical agitation and sonication with varying Cd 2+ concentrations in the solutions. The critical micelle concentration (CMC) of the surfactant Span 80 in c…
Our synthetic attempts for the preparation oligo- and polyporphyrin arrays were reviewed in comparison with recent accomplishment in the related field. Especially, the synthesis and structural characteristics of huge monodisperse meso-meso linked porphyrin arrays with multidimensional architectures were focused. The A…
Mineralization in living organisms generates structures different from abiotic crystal growth. Mimicking biomineralization in vitro may become a way of synthesizing inorganic materials with useful microstructures. For example, the growth of calcium carbonate crystals in the presence of certain sea urchin proteins give…
Search coils and needle probes are existing experimental sensors that can measure flux distributions in electrical steels. This work investigates and evaluates the limitations of each method, proposes the use of a new modified needle probe method and gives reasons for its improved applicability and relative merits.
The modification of the bandgap structure of optical Fibonacci lattices that arises from an increase in the system size is analyzed. It is found that there is a minimum critical size of the Fibonacci lattice necessary to form a photonic bandgap. The analysis of localized photonic modes of Fibonacci lattices shows that…
Biological samples having different characteristics were observed by environmental scanning electron microscopy (ESEM). The environmental conditions for untreated biological samples was determined by optimizing sample temperature and chamber pressure. When the temperature was at 4 degrees - 6 degrees C and chamber pre…
A new synthesis of supermicroporous silica (1.6–2.0 nm diameter), using micelles of a quaternary ω-hydroxyalkylammonium salt, is presented by the authors. The material exhibits highly ordered pore arrays (see Figure). Details on pore size determination by adsorption techniques are given. In an outlook, the effects of…
The phonon Boltzmann transport equation is used to calculate the thermal conductivity in clamped silicon nanowires and study both boundary and confining effects of phonon scattering. The solution method includes partly diffuse and specular phonon reflections at the boundaries and introduces a spectral extinction coeff…
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We succeeded in plan-view dynamic observation of the initial formation process of carbon nanotubes from beta-SiC( 1 1 1) surfaces by time-resolved high resolution transmission electron microscopy. At 1360 degrees C, the flakes of graphite layers of a fibre orientation were formed on the SiC( 1 1 1) surfaces. From the…