Materials Literature
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Natural phosphate is basic enough to promote the epoxidation of electron-deficient alkenes with dilute aqueous hydrogen peroxide. A simple modification with sodium nitrate leads to the probably most active, water compatible and recyclable basic catalyst described for this reaction. It promotes the epoxidation of a lar…
Pressure-induced amorphization of materials with negative thermal expansion is believed to arise from uncorrelated tiltings of polyhedra, kinetically frozen in an orientationally disordered state at room temperature. The transition to an amorphous phase in zircon tungstate ZrW 2 O 8 occurs above 1.5 GPa upon cold comp…
Removal of NOx (NO in the presence of O2) by CeO2–ZrO2 binary oxides was investigated. CeO2–ZrO2 prepared by a modified sol–gel method [CZ(SG)] showed high NOx sorption capacity, while CeO2–ZrO2 prepared by a coprecipitation method [CZ(CP)] was not effective. In both cases, NOx was found to be removed by adsorption on…
Above the semiconductor-to-metallic transition (SMT) temperature ( T p ), transport properties of the La 1− x Pb x MnO 3+δ (0 ≤ x ≤ 0.5)-type mixed valence oxides with T p between 230 and 275 K (depending on x ) have been thoroughly examined for a small-polaron hopping conduction mechanism of the carriers. Although th…
Abstract Liquid‐crystalline (LC) hybrid polymers with functionalized silsesquioxanes with various proportions of LC monomer were synthesized by the reaction of polyhedral oligomeric silsesquioxane (POSS) macromonomer with methacrylate monomer having an LC moiety under common free‐radical conditions. The obtained LC hy…
A one-pot synthesis is reported of water-soluble cadmium sulfide nanoclusters capped with cysteine ester, with an average size of 2.0 nm and fluorescing in the blue region, establishing the possibility of using these as fluorescent biological probes.
The molecular structures, the nuclear magnetic shieldings, and the aromatic ring-current shieldings (ARCS) have been calculated for Al 4 2-, Al 4 Li -, and Al 4 Cu - at the Hartree−Fock (HF) level, the second-order Møller−Plesset (MP2) level, the coupled-cluster singles and doubles (CCSD) level, and the coupled-cluste…
The effect of microbial control of souring on the extent of corrosion was studied in a model system consisting of pure cultures of the nitrate-reducing, sulfide-oxidizing bacterium (NR-SOB) Thiomicrospira sp. strain CVO and the sulfate-reducing bacterium (SRB) Desulfovibrio sp. strain Lac6, as well as in an SRB consor…
This paper presents general methods of preparing three-dimensionally ordered macroporous (3DOM) metals or alloys via templated precipitation and subsequent chemical conversion of metal salts (acetates, oxalates) within colloidal crystals of poly(methyl methacrylate) (PMMA) or polystyrene (PS) spheres. Three approaches…
MoSe2 and WSe2 nanotubes are obtained by the reduction of the corresponding triselenides in hydrogen or by the decomposition of the ammonium selenometallates in a hydrogen atmosphere.
When butylamine in relatively high concentrations (0.1−0.25 M) is added to a colloidal solution of CdSe nanoparticles (NPs) that are approximately 1.6 nm in diameter, the band gap absorption changes from a broad, relatively weak absorption centered at 445 nm to a narrow, relatively strong absorption centered at 414 nm…
Impregnation of hyper-cross-linked polystyrene (HPS) with tetrahydrofuran (THF) or methanol (ML) solutions containing platinic acid results in the formation of Pt(II) complexes within the nanocavities of HPS. Subsequent reduction of the complexes by H2 yields stable Pt nanoparticles with a mean diameter of 1.3 nm in T…
Sulfonic acid groups anchored to the surface of mesoporous MCM-41 silica have been identified with S K-edge XANES spectra and the material is an efficient catalyst for the liquid phase condensation of phenol with acetone to form Bisphenol-A with high selectivity.
The magnetic, transport, and thermoelectric properties of a Tl-based misfit cobaltite have been investigated. Although this material exhibits a metallic behavior, the thermopower (Seebeck) is large, with room temperature values close to +90 \ensuremath{\mu} V/K. Compared to previously studied misfit cobalt oxides $[{\…
A new heterogeneous catalyst, Sn-MCM-41, is described for the Baeyer-Villiger reaction with hydrogen peroxide which selectively activates the carbonyl function for the nucleophilic attack by the oxidant, with high chemoselectivities when double bonds are present in the molecule.
The crystal structure, magnetic and electrical transport properties of the sodium-doped lanthanum manganites La 1- x Na x MnO 3 (0.07⩽ x ⩽0.40) have been studied in detail using x-ray powder diffraction, atomic absorption spectroscopy, a SQUID (superconducting quantum interference device) magnetometer and the four-pro…
The cell seeding density and spatial distribution in a 3-D scaffold are critical to the morphogenetic development of an engineered tissue. A dynamic depth-filtration seeding method was developed to improve the initial cell seeding density and spatial distribution in 3-D nonwoven fibrous matrices commonly used as tissu…
The temperature dependencies of the resistivity and magnetization of a series of Ni 2+ x Mn 1- x Ga ( x = 0-0.09) alloys were investigated. Along with the anomalies associated with ferromagnetic and martensitic transitions, well-defined anomalies were observed at the temperature of premartensitic transformation. The p…
Constitutive equations are derived for the viscoelastic behavior of particle-reinforced rubbers at isothermal loading with finite strains. A filled rubber is thought of as a composite medium where inclusions with high and low concentrations of junctions between chains are randomly distributed in a host matrix. The inc…
The photochemical and electrochemical properties of four chlorin-C60 or porphyrin-C60 dyads having the same short spacer between the macrocycle and the fullerene are examined. In contrast with all the previous results on porphyrin-fullerene dyads, the photoexcitation of a zinc chlorin-C60 dyad results in an unusually…