Materials Literature
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The ${D}_{1}$ and ${D}_{2}$ vibrational ring modes of normal and densified silica are investigated using a time resolved pump-probe technique and spontaneous Raman spectroscopy. The vibrational response function of both techniques is derived and compared to the experimental results obtained on three samples of silica…
The temperature-dependent optical properties of ZnO nanosheets and nanowires fabricated on conductive brass substrates with different surface-to-volume ratios and morphologies are investigated. The near band edge and deep-level emission mechanisms are studied. The blueshifted donor bound exciton D 0X peak and enhanced…
We propose orbital fluctuations in a multiband ground state as the superconducting pairing mechanism in the new iron-based materials. We develop a general SU(4) theoretical framework for studying a two-orbital model and discuss a number of scenarios that may be operational within this orbital fluctuation paradigm. The…
The development of ternary nanoscale materials with controlled cross-sectional doping is an important step for the use of chemically prepared quantum dots for nanoscale engineering applications. We report cross-sectional, elemental doping with the formation of an alloyed CdSSe nanocrystal from the thermal decompositio…
Universal solubility: A variety of monodisperse nanocrystals have been synthesized in an “amphibious” reaction bath consisting of an amphiphilic multidentate ligand and low-molecular-weight polyethylene glycols (PEGs). These particles are instantly soluble in nearly all solvents and retain their characteristic optical…
Self-assembly is a promising route for controlling the nanoscale structure and material properties of coatings, yet it remains difficult to control the microstructure of these systems. In particular, self-assembling materials typically have complex and delicate energy landscapes, which are sensitive to defects, making…
A general one-step method for the growth of supported porphyrin and phthalocyanine single-crystalline nanowires is reported. This methodology permits the growth of a novel type of open core@shell organic nanowires. These 1D heterostructured materials consist in inner porphyrin nanowire cores wrapped by phthalocyanine…
Quantum chemical calculations at DFT (BP86) and ab initio levels (CCSD(T)) have been carried out for transition metal carbon complexes [MX2(PR3)2(C)] with various combinations of M = Fe, Ru, Os, X = F, Cl, Br, I, and R = H, Me, Ph, Cyc. Calculations have also been performed for [RuCl2(PMe3)(NHC)(C)] and [RuCl2(NHC)2(C…
meso-Tetraarylporphycenes, structural isomers of meso-tetraarylporphyrins, were synthesized by the acid-catalyzed oxidative coupling reaction for the first time which is an alternative synthetic methodology to the traditional McMurry coupling reaction. The structure of the macrocycle and Ni(II) complex are characteriz…
One of the major limitations to the use of fuel cell systems in vehicular transportation is the lack of hydrogen storage systems that have the required hydrogen storage density and moderate enthalpy of dehydrogenation. Organic liquid H(2) carriers that release H(2) endothermically are easier to handle with existing in…
Unsupported and γ-Al 2 O 3 -supported Ba and Pb titanate catalysts were prepared, characterized and studied in the combustion of methane, as a test reaction for VOCs’ catalytic combustion. They present good catalytic activities, and after dispersion (5%) on γ-Al 2 O 3 the specific activity of the supported perovskite…
A phenomenological Landau-theory model, where a crystal on cooling from a state with polar symmetry exhibits a maximum of dielectric permittivity and polarization-field hysteresis loops, is offered. The model is equivalent to that of a true ferroelectric in a weak external dc bias. Permittivity maximum occurs as a res…
Abstract The effect of phase‐pure cristobalite (a high temperature crystalline polymorph of silica) on the adhesive characteristics of hydroxyl terminated polydimethylsiloxane (PDMS) was studied. The potential advantages of PDMS/cristobalite composite system as an adhesive for aerospace applications are also discussed…
Abstract The formation of clay intercalates with three different kinds of organic ammonium salts, when mixed in the presence of synthetic or natural polyisoprene rubber, has been investigated. X‐ray diffraction and transmission electron microscopy (TEM) experiments have shown that intercalates with organic bilayers, r…
Abstract A new route for adding self‐healing properties to soluble polymers is presented briefly. Self‐healing block copolymers (polystyrene‐ block ‐polybutadiene block ‐polystyrene from Sigma‐Aldrich) were obtained by dissolving the polymer in a solvent that neither dissolves the microbubbles nor deactivate the Grubb…
The porous structure and the periodic array of cavities in ordered mesoporous materials with large, three-dimensionally arranged and interconnected pores is thoroughly described by combining electron tomography, small-angle X-ray diffraction, and nitrogen sorption techniques. We used the ability of the electron tomogr…
Abstract Homogeneous tridentate Schiff base vanadium catalysts derived from salicylaldehydes and tert ‐leucinol or tert ‐leucine are known to be excellent catalysts for the asymmetric oxidation of α‐hydroxy esters including ethyl mandelate. Herein, new analogous supported, semi‐soluble and insoluble catalysts are synt…
A brief overview of the nucleoside-based lipid family is presented in this article. These molecules dispersed in non-aqueous and aqueous solvents are yielding a large variety of supramolecular systems including vesicles, ribbons, gels and two-dimensional assemblies. Nucleoside-based amphiphiles have been also investig…
In the last decade, the popularity of sulfur SAD anomalous dispersion experiments has spread rapidly among synchrotron users as a quick and streamlined way of solving the phase problem in macromolecular crystallography. On beamline 10 at SRS (Daresbury Laboratory, UK), a versatile design has allowed test data sets to…
Abstract Effects of precipitated silica (PSi) and silica from fly ash (FA) particles (FASi) on the cure and mechanical properties before and after thermal and oil aging of natural rubber (NR) and acrylonitrile–butadiene rubber (NBR) blends with and without chloroprene rubber (CR) or epoxidized NR (ENR) as a compatibil…