Materials Literature
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We present a new process for the synthesis of colloidal europium-doped yttrium vanadate with a particle diameter of about 10 nm. Nanocrystals are produced by precipitation of citrate complexes of rare-earth salts with sodium orthovanadate. NMR and IR studies show that the interaction between citrate ligands and lantha…
Four metakaolins were prepared by calcination of a natural Spanish kaolin (Navalacruz deposit, Zamora province) at 600, 700, 800, and 900 °C. These four metakaolins, more reactive than the parent kaolin, were submitted to acid and alkaline activations. Acid activation was carried out with 6 M HCl at room temperature a…
Gold nanoparticles (NPs) were prepared by reduction with salicylic acid in aqueous solution. The resulting dispersions were found to contain a mixture of flat triangular/hexagonal and smaller close-to-spherical NPs. As expected from theoretical considerations, such nanocolloids display two clearly differentiated surfa…
The electrochemistry of horse heart cytochrome c was studied by cyclic voltammetry at a glassy carbon electrode modified with single-wall carbon nanotubes (SWNTs). A pair of well-defined redox waves was obtained in cytochrome c aqueous solution at an activated SWNT film-modified electrode. The optimal conditions for a…
This paper describes a general approach that generates nanoscale hollow structures of metals by reacting solutions of appropriate salt solutions with solid templates of a more reactive metal. Typical examples include Au 3+, Pt 2+, and Pd 2+ salts and nanoparticles or nanowires of silver. The morphology, void space, an…
The title compound, trimercury(II) bis[selenite(IV)] selenate(VI), contains three crystallographically inequivalent HgII cations with coordination numbers of eight (denoted Hg1 and Hg2) and five (denoted Hg3). The corresponding coordination polyhedra around the metal atoms might be described as intermediates between a…
First-principles pseudopotential calculations using plane-wave basis functions have been made to quantitatively evaluate the formation energy of Cr/Al vacancies in ${\mathrm{MgCr}}_{2}{\mathrm{O}}_{4}$ and ${\mathrm{MgAl}}_{2}{\mathrm{O}}_{4}.$ Relaxation of atoms within the second nearest neighbor shell of the vacanc…
Abstract Polysiloxane diblock copolymers containing a pure polysiloxane backbone were prepared by the functionalization of poly(dimethylsiloxane)‐ b ‐poly(methylvinylsiloxane) copolymers. The copolymers were obtained by the sequential anionic copolymerization of either 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinylcyclotetras…
Three molecules with olefinic deuterons were obtained through H−D exchange of the C3 proton on the central bridging double bond of spiropyran photomerocyanines with deuterium oxide solution. Quadrupole coupling parameters were determined by simulation of the spinning sideband manifolds in spectra obtained using solid-…
A combination of reverse Monte Carlo, molecular dynamics, and lattice dynamics simulations were used to obtain structural and thermodynamic data for low-density amorphous ice. A thermodynamically discontinuous transformation to a phase with properties and a structure consistent with supercooled liquid water is found t…
The tetraamide ligand, DOTA-tetra(glycine ethyl ester), forms complexes with the lanthanide(III) cations that exist in solution predominantly as the square antiprism structure with single, slowly exchanging inner-sphere water molecule. Variable-temperature 1H and 17O NMR studies revealed that the bound water lifetimes…
Simulated annealing, in the form of temperature-controlled molecular dynamics, has been successfully applied to macromolecular X-ray structure optimization. The theory and practice of the method are reviewed, and some recent improvements are described.
The surfaces of kaolinite have been modified through intercalation with deuterated dimethylsulfoxide (d-DMSO). X-ray diffraction shows the kaolinite to be expanded from 7.2 to 11.19 Å. Modification of the surface has been explored through (a) changes to the hydroxyl surfaces of the kaolinite and (b) through changes to…
Pyrochlores have the striking feature that their radiation resistance is highly dependent on their composition. In this work, the propensity of a pyrochlore to transform to a cation-disordered structure and the influence of titanium ions is ascertained from the mechanisms of defect formation. A detailed study of defec…
Three poly(oxyethylene- block -oxybutylene) diblock copolymers, E 76 B 38, E 114 B 56, and E 155 B 76, were blended with poly(oxybutylene) homopolymer, B 14 and B 28, such that lamellae (lam), gyroid (gyr), hexagonally packed cylinders (hex), and body-centered-cubic (bcc) spheres were obtained in the melt. The nonisot…
Abstract Oligomeric methyl silsesquioxane (O‐MSSQ) precursors were prepared from methyl trimethoxysilane (MTMS) in a mixed solvent of methyl isobutyl ketone and tetrahydrofuran by variations in the pH and molar ratio of water to MTMS ( R 1 ). The molecular structures of O‐MSSQ were controlled by the reaction condition…
The polymorphic behavior of samples of isotactic polypropylene prepared with unbridged oscillating metallocene catalysts is analyzed and compared with the behavior of samples prepared with a chiral isospecific metallocene catalyst having similar amounts of defects of stereoregularity. In the samples prepared with the…
We investigated the paramagnetic resonance in single crystals of ${\mathrm{LiCuVO}}_{4}$ with special attention to the angular variation of the absorption spectrum. To explain the large resonance linewidth of the order of 1 kOe, we analyzed the anisotropic exchange interaction in the chains of edge-sharing ${\mathrm{C…
The aim of this study was to develop new biocompatible coatings for bone implants by the alternating deposition of oppositely charged polyelectrolytes. Polyelectrolyte films were built up with different terminating layers on which SaOS-2 osteoblast-like cells and human periodontal ligament (PDL) cells were grown. The…
${\mathrm{BiMn}}_{2}{\mathrm{O}}_{5}$ has been prepared in polycrystalline form by a citrate technique, and studied by neutron powder diffraction (NPD), specific-heat, and magnetization measurements. High-resolution NPD data show that ${\mathrm{BiMn}}_{2}{\mathrm{O}}_{5}$ is orthorhombic (space group $Pbam,$ $Z=4)$ an…