Materials Literature
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The electronic structure of spherical PbS and PbSe quantum dots is calculated with a four-band envelope-function formalism. This calculation accounts for both exciton energies and wave functions with the correct symmetry of the materials. The selection rules and the strength of the dipole transitions of lead-salt quan…
Cell adhesion and spreading of chick embryo vascular and corneal explants grown on rough and smooth poly (methyl methacrylate) (PMMA) were analyzed to test the cell response specificity to substratum surface properties. Different degrees of roughness were obtained by sand-blasting PMMA with alumina grains. Hydrophilic…
The rheology of end-tethered polymer layered silicate nanocomposites is investigated using linear viscoelastic measurements in oscillatory shear with small strain amplitudes. Two systems consisting of poly(ε-caprolactone) and nylon-6 with varying amounts of layered silicate (montmorillonite) are examined. The storage…
Erbium doped materials are of great interest in thin film integrated optoelectronic technology, due to their Er3+intra-4f emission at 1.54 μm, a standard telecommunication wavelength. Er-doped dielectric thin films can be used to fabricate planar optical amplifiers or lasers that can be integrated with other devices o…
The synthesis of epitaxially grown, wurtzite CdSe/CdS core/shell nanocrystals is reported. Shells of up to three monolayers in thickness were grown on cores ranging in diameter from 23 to 39 Å. Shell growth was controllable to within a tenth of a monolayer and was consistently accompanied by a red shift of the absorpt…
Siguiendo el planteamiento efectuado en la I parte de este trabajo, en esta II parte se caracteriza la recristalización dinámica de un acero comercial microaleado con un contenido medio de carbono desde el punto de vista de su inicio y de su cinética. Con este objeto se efectuaron ensayos de compresión uniaxial en cal…
In this paper, a review of Transmission Electron Microscopy (TEM) for the characterization of materials is presented. TEM is a technique which allow the crystallographic and chemical characterization of materials with high spatial resolution. Now, TEM allows the visualization of rows of atoms as well as defects like d…
Abstract. Analyses of the chemical composition of rapidly percolating soil water were used to study the genesis of a shallow podzol in a Campinarana forest and a clayey ferralsol from a typical rainforest located in North Manaus (Amazonia, Brazil). The samples were collected in lysimeters and analysed for Ca2+, Na+, K…
To understand the role of the amino acid residue at position 172 in the conformational stability, four mutant enzymes of Thermus thermophilus 3-isopropylmalate dehydrogenase in which Ala172 was replaced with Asp, Glu, Asn, and Gln were prepared by site-directed mutagenesis. Three mutants were more stable than the wild…
Prepared by the Technical Committee on Optimal Structural Design of the Technical Administrative Committee on Analysis and Computation of the Technical Activities Division of the Structural Engineering Institute of ASCE
To explore the optimized colossal magnetoresistance (MR), i.e., higher MR with lower field, magnetotransport properties of single-crystalline perovskite manganites have systematically been investigated. Near x=1/2 with intrinsic instability of charge ordering (a 1/1 ordering of Mn3+/Mn4+), the one-electron bandwidth (…
Brillouin light scattering has been used to study the elastic properties of an InSe film grown epitaxially on a hydrogen-terminated non-reconstructed Si(111) surface. Both generalized Rayleigh-Sezawa and Love acoustic modes have been revealed, and their velocity dispersions measured as functions of the ratio between t…
The short-pulse laser crystallization and interference structuring of amorphous germanium films were investigated by time resolved reflection measurements and Raman spectroscopy. We demonstrate that submicrometer crystalline structures with very sharp lateral interfaces can be produced by laser interference crystalliz…
The ordering temperatures Tc1 (disordered β to B2 order) and Tc2 (B2 to L21 order) have been obtained in Cu–Al–Ni shape memory alloys with different concentrations by electrical resistivity. The dependence of the ordering temperatures on the concentration has been established. Also, a modification of the theoretical c…
A poly(t-butyl acrylate)/gold nanocomposite sandwich was annealed to induce diffusion of the gold particles, which was monitored using Rutherford backscattering spectrometry. Marker motion experiments were also performed to probe particle and polymer mobilities independently. The experiments revealed that particle mob…
We investigate a wetting reversal transition in thin films of two-phase mixtures of poly(ethylene-propylene) (PEP) and its deuterated analog (dPEP) on substrates covered by self-assembled monolayers (SAM) whose surface energy, ${\ensuremath{\gamma}}_{\mathrm{SAM}}$, is tuned by varying the SAM composition. As ${\ensur…
We have studied thin liquid films made from semidilute polyelectrolyte solutions. The disjoining pressure (due to interaction between film surfaces) has been measured as a function of the film thickness. We observe pressure oscillations, corresponding to film stratification. The oscillations become sharper as the poly…
We investigated the reduction mechanism of surface oxide on aluminum alloy powders containing magnesium, by x-ray photoelectron spectroscopy using synchrotron radiation (SR-XPS). The reduction is the initial reaction in a new aluminum nitridation method developed by one of the authors. In heating the powders to 823 K,…
Magnetic excitations have been investigated in the spin dimer material ${\mathrm{VODPO}}_{4}\ifmmode \dot{}\else \.{}\fi{}\frac{1}{2}{\mathrm{D}}_{2}\mathrm{O}$ using inelastic neutron scattering. A dispersionless magnetic mode was observed at an energy of 7.81(4) meV. The wave vector dependence of the scattering inte…
By studying the growth of Cu2O islands during the initial oxidation stage of Cu(001) with in situ transmission electron microscopy, it is found that the dominant mechanism for the growth of three-dimensional islands is surface diffusion of oxygen. However, there exists a non-negligible contribution to the metal oxide…