Materials Literature
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We have studied the structural and superconducting properties of MgB$_2$ thin films made by pulsed laser deposition followed by in situ annealing. The cross-sectional transmission electron microscopy reveals a nanocrystalline mixture of textured MgO and MgB$_2$ with very small grain sizes. A zero-resistance transition…
The viscoplastic deformation (creep) of crystalline materials under constant stress involves the motion of a large number of interacting dislocations. Analytical methods and sophisticated `dislocation-dynamics' simulations have proved very effective in the study of dislocation patterning, and have led to macroscopic c…
We present a lattice model to study the equilibrium phase diagram of ordered alloys with one magnetic component that exhibits a low temperature phase separation between paramagnetic and ferromagnetic phases. The model is constructed from the experimental facts observed in Cu$_{3-x}$AlMn$_{x}$ and it includes coupling…
A relatively high critical temperature, Tc, approaching 40 K, places the recently-discovered superconductor magnesium diboride (MgB2) intermediate between the families of low- and copper-oxide-based high-temperature superconductors (HTS). Supercurrent flow in MgB2 is unhindered by grain boundaries, unlike the HTS mate…
We have performed high resolution x-ray photoemission spectroscopy experiments on the Ru(0001) surface, both clean and covered with well-defined amounts of oxygen up to 1 monolayer coverage. For the clean surface we detected two distinct components in the Ru ${3d}_{5/2}$ core-level spectra, for which a definite assign…
A theoretical study of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepan-2-one (DXO) and l -lactide (LLA) with stannous(II) 2-ethylhexanoate (Sn(Oct) 2 ) is presented. The B3LYP density functional method has been used for the quantum chemical calculations. Our results support a coordination−insertion mec…
Recent high resolution Compton scattering experiments clearly reveal that there are fundamental limitations to the conventional local density approximation (LDA) based description of the ground state electron momentum density (EMD) in solids. In order to go beyond the framework of the density functional theory (DFT),…
Poly(methyl methacrylate) (PMMA) and polystyrene (PS)/clay nanocomposites were prepared via in-situ bulk polymerization. The compatibility of the initiator and monomer with the clay surface was found to profoundly affect the clay dispersion. By using a surfactant containing a polymerizable group to modify the clay sur…
Fluoroalkylsilane treatment of super-hydrophobic, aligned carbon nanotube films (see electron micrograph) prepared by pyrolysis of metal phthalocyanines results in the films having both super-hydrophobic and super-lipophobic properties, namely they are super-“amphiphobic” surfaces.
Superparamagnetic iron oxide MR imaging contrast agents have been the subjects of extensive research over the past decade. The iron oxide particle size of these contrast agents varies widely, and influences their physicochemical and pharmacokinetic properties, and thus clinical application. Superparamagnetic agents en…
A critical review of adsorption methods that are currently used in the characterization of ordered organic−inorganic nanocomposite materials is presented, and the adsorption methodology that is potentially useful for this characterization, but has not yet been applied, is discussed. The ordered organic−inorganic nanoc…
Emission spectra of silicon oxide molecules in the spectral range from 228 to 246 nm have been observed in a pulsed discharge and a laser-produced plasma. The vibrational bands belonging to the Δυ = -1,0, + 1 sequences of the SiO A 1 Π-X 1 Σ + system have been reproduced by computer simulations in order to determine t…
The coordination chemistry of the title bifunctional ligand with Y(NO3)3 and Er(NO3)3 is described, and the molecular structures of the bis-chelates {M[(Ph2P(O)CH2)2C6H4]2(NO3)2}(NO3) are compared with the structures formed by the trifunctional ligand [(Ph2P(O)CH2)2C5H3NO].
We demonstrate that density-functional theory can be used to study the charge-order/disorder transition in ${\mathrm{Cs}}_{2}\mathrm{Au}(\mathrm{I})\mathrm{Au}(\mathrm{III}){\mathrm{Cl}}_{6}.$ The ground-state structure of this mixed-valence compound is reproduced with satisfactory accuracy, and a discontinuous phase…
High-dimensional energy landscapes of complex systems often exhibit a very complicated structure, with many local minima separated by a multitude of barriers of various heights. For the analysis of the dynamics on such landscapes, simplified models based on combining many microstates to form physically relevant macros…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis of Dendrimers Containing 1,3,4-OxadiazolesBert Verheyde and Wim DehaenView Author Information Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium [email protected]Cite this: J. Org. Chem. 2001, 66, 11, 4062–4064Publica…
The optical and magneto-optical (MO) spectra of Tm monochalcogenides are investigated theoretically from first principles, using the fully relativistic Dirac linear combination of muffin-tin orbitals band structure method. The electronic structure is obtained with the local-spin-density approximation (LSDA), as well a…
Abstract Nanophase‐separated poly(2‐hydroxyethyl methacrylate)‐ l ‐polyisobutylene (PHEMA‐ l ‐PIB) amphiphilic conetworks were obtained by crosslinking α,ω‐bismethacrylate‐terminated polyisobutylene (PIB) via copolymerization with silylated 2‐hydroxyethyl methacylate, followed by the hydrolysis of the silylether group…
We report here an in situ x-ray diffraction investigation of the structural changes in carbon single-wall nanotube bundles under quasihydrostatic pressures up to 13 GPa. In contrast with a recent study [Phys. Rev. Lett. 85, 1887 (2000)] our results show that the triangular lattice of the carbon nanotube bundles contin…
To investigate the effects of electron-donating and electron-withdrawing substituents upon the reaction of porphyrins with osmium tetraoxide, and the pinacol-pinacolone rearrangement of the resulting diols, a series of meso-substituted porphyrins were prepared by total synthesis. Porphyrins with electron-donating subs…