Materials Literature
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Tetra(phenylethynyl)tin is an efficient initiator for the ring-opening polymerization of lactide, with or without the addition of isopropanol as a coinitiator, providing high activity and high molar mass polymers.
Diffractive optical elements to form one-parameter directivity diagrams are designed using the geometric optics. The field ray structure corresponding to the line-shaped directivity diagram is analyzed and curvilinear coordinates for calculating the eikonal are proposed. A new simplified formula for the eikonal functi…
A significant amount of work has been done in the past decade to reveal the unique structural and mechanical properties of carbon nanotubes and to explore what might be the key applications of these novel materials. Due to the difficulty in developing experimental techniques, there is still no report on the measured v…
We have recently proposed a nonlocal continuum crystal plasticity theory that is based on a statistical-mechanics description of the collective behaviour of dislocations. Kinetic equations for the dislocation density fields have been derived from the equation of motion of individual dislocations and have been coupled…
Abstract Two series of solid catalysts in which a chiral palladium or nickel complex with Schiff bases as ligands have been immobilized on ordered mesoporous silica supports (MCM‐41), delaminated ITQ‐2, ITQ‐6 zeolites and amorphous silica have been prepared. Hydrogenation of alkenes and imines was studied with the hom…
The successful commercialization of MRAM will rely on providing customers with a robust and reliable memory product. The intrinsic reliability of magnetoresistive tunnel junction (MTJ) memory bits and the metal interconnect system of MRAM are two areas of great interest due to the new materials involved in this emergi…
Abstract Starting with a BST (Ba 0.6 Sr 0.4 TiO 3 ) nanopowder with a mean diameter of about 50 nm, the average grain size increases from the nanometer to the micrometer range (from 70 nm to 1–2 μm) by thermal annealing between 700 and 1400 °C. The dielectric properties of these pressed powders has been determined, sh…
The surface of a liquid near a moving contact line is highly curved owing to diverging viscous forces. Thus, microscopic physics must be invoked at the contact line and matched to the hydrodynamic solution farther away. This matching has already been done for a variety of models, but always assuming the limit of vanis…
Adsorption in porous solids at room or low temperature is one of the possible storage modes of hydrogen gas. The storage efficiency in these materials depends on their physical properties and characteristics, the most important being their adsorption capacity, porosity, density, and the endo- or exothermic character o…
For the first time combined X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) experiments were carried out to probe the short- and long-range order in lanthanum-modified PbTiO 3 ceramic materials (Pb 1 - x La x TiO 3 ) for x ranging from 0 to 30 atom % of La. XRD results show that a tetragonal structure…
Abstract Based on finite element formulations for the strain gradient theory of microstructures, a convergence criterion for the C 0–1 patch test is introduced, and a new approach to devise strain gradient finite elements that can pass the C 0–1 patch test is proposed. The displacement functions of several plane trian…
We have studied the nanostructural and nanochemical changes occurring in pure ceria (CeO2) and CeO2–zirconia (ZrO2) catalysts during reduction. The reduction is carried out in an environmental transmission electron microscope in dry H2 at 2 Torr up to 800°C. We use in-situ electron-energy-loss spectroscopy to follow c…
The origin of the improvement of the ferroelectric and piezoelectric properties of KNbO 3 ceramics by the addition of small amounts of La and Fe has been investigated. The La/Fe-codoped KNbO 3 ceramics formed a single (K 1- x La x )(Nb 1- x Fe x )O 3 solid solution, and their unit-cell volume decreased significantly w…
AIM: To determine the effect of the aqueous extract of Mondia whitei (Periplocaceae) roots on testosterone production and fertility of male rats. METHODS: Adult male Wistar rats were used. In the acute study, 20 rats were randomly divided into 5 groups of 4 animals each. Four treated groups were administered orally a…
Abstract Electrospinning is a process by which ultrafine fibers which have diameters in the range of tens of nanometers to less than ten of micrometers can be produced. This process utilizes expulsion of charges as a means to very thin fiber formation. In this short report, the effects of some of the influencing solut…
Abstract Product mixtures of epoxidized fatty compounds can be analyzed by using 1 H NMR. Conversion of double bonds and selectivities to different products can easily be calculated. Moreover, if diunsaturated substrates are used in epoxidation reactions, yields to mono‐ and diepoxidized products can be determined. Th…
In order to clarify the thermodynamic relations of various phases in NaNbO 3 , the enthalpies of formation for the cubic ( Pm3m ), tetragonal ( P4/mbm ), orthorhombic ( Ccmm , Pnmm , Pbma ) and rhombohedral ( R3c ) phases in NaNbO 3 were calculated using a plane-wave pseudopotential method. The NaNbO 3 phase with a lo…
[structure: see text] A new type of glycocluster based on polyhedral oligosilsesquioxanes (POSS) has been efficiently prepared from unprotected mannoside and lactoside employing a convergent approach of thiol-radical addition reaction. The versatility of this approach was demonstrated by functionalization of mannoside…
Summary Significant progress has been made toward developing a quantitative understanding of the inhibitor/rock interaction. In this study, four common oil field inhibitors (three phosphonates and one polyacrylate) are compared using carbonate-rich formation material. In addition to calcite (CaCO3) in the reservoir ro…
Plastic deformation affects the hysteretic magnetic properties of steels because it changes the dislocation density, which affects domain-wall movement and pinning, and also because it places the specimen under residual strain. An earlier paper proposed a model for computing hysteresis loops on the basis of the effect…