Materials Literature
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The optical absorption spectra of LaMnO 3 single crystals, pure and slightly doped with Ce and Sr (7%), were studied in the middle IR region. Ellipsometry measurements were performed in the visible region to determine real and imaginary permittivity parts. The energies of the onset of indirect transitions in LaMnO 3 a…
A new Monte Carlo move for polymer simulations is presented. The “wormhole” move is build out of reptation steps and allows a polymer to reptate through a hole in space; it is able to completely displace a polymer in time N2 (with N the polymer length) even at high density. This move can be used in a similar way as co…
Dimethylimidazolidinone/lithium chloride (DMI/LiCL) is shown to be an effective solvent system for a variety of celluloses, including the high molecular weight cellulose of cotton, when a swelling pretreatment in sodium hydroxide is incorporated. DMI/0.5% LiCl is suitable for use as a mobile phase in gel permeation ch…
FUNCTIONALIZED SILICA OBTAIN BY SOL-GEL METHOD. Some aspects of the chemistry involved in the preparation and characterization of functionalized silicon oxide by sol-gel method are considered in this work. The synthesis was performed with different silicon alcoxide precursors and the influence of the acid and basic ca…
Structures of Pt-nanowires, synthesized in channels of silica mesoporous materials MCM-41, SBA-15 and MCM-48, were investigated by transmission electron microscopy. One dimensional (1D) Pt-nanowires were formed inside the channels of the MCM-41, and were single crystals with a length of several tens to several hundred…
Andalusite is easily converted to mullite and silica on heating. A better understanding of the mullitization mechanisms provides new information on use of this mineral in refractory castables. By using specific particle‐size distributions for andalusite‐based high‐alumina castables, the primary mullite formation can b…
Band structures of both wurtzite and rock-salt ZnO were investigated using the ab initio pseudopotential method with both local density approximation (LDA) and GW approximation. The error in approximating 3d electrons as core electrons was investigated for both LDA and quasiparticle calculations. The differences betwe…
The polarization phenomenon, involved in the mechanisms of emission from carbon nanotubes, is investigated by means of a self-consistent resolution of Poisson's equation. We show that the field enhancement, responsible for the emission, varies in a logarithmic way with the nanotube length. This leads, for most of the…
OBJECTIVES: From animal and clinical studies it is known that prevention of 'over-distention' of vein grafts by using extravascular support ameliorates the arterialization process in vein grafts with subsequent more favorable patency. The most ideal support is a biodegradable, porous, elastic graft (Biomaterials, 15 (…
Differential thermal analyses (DTA) and thermogravimetric analyses (TG) were carried out on sodalite, tugtupite, danalite, and helvite using a Netzsch STA 409 EP/3/D simultaneous TG–DTA apparatus. In the DTA and TG experimental run, a weighed amount of finely powdered sample was heated from 20 to 1450°C at a constant…
A new model was developed to study the effect of ferrous ion oxidation on the corrosion of active iron. When ferrous hydroxide precipitate is present at the iron surface as the result of corrosion, the solution boundary layer near the iron surface is saturated with ferrous hydroxide and the pH and ferrous ion concentr…
Abstract Cobalt(III) complex has been heterogenized onto a mesoporous material SBA-15 and successfully applied to the liquid phase oxidation of p-xylene in spite of not using either a solvent or bromide ion.
The microstructures of fine‐grained β‐SiC materials with α‐SiC seeds annealed either with or without uniaxial pressure at 1900°C for 4 h in an argon atmosphere were investigated using analytical electron microscopy and high‐resolution electron microscopy (HREM). An applied annealing pressure can greatly retard phase t…
In near edge X-ray absorption fine structure (NEXAFS) spectra of carbon (C) and nitrogen (N) K-edge regions were measured for the stable radical compound lithium phthalocyanine (LiPc). The observed spectra were compared with those of metal free Pc ( H 2 Pc ), copper Pc (CuPc), and zinc Pc (ZnPc). The spectral features…
The polarization-dependent optical response of vitreous titanium dioxide films was determined by infrared reflection–absorption spectroscopy (IRAS). The predominant nearest-neighbor coordination (short-range order) in the films was characteristic of crystalline anatase. A dielectric function ε(ν) was constructed, base…
Structural modulations in solid solutions of C 3 S doped with various amounts of ZnO were investigated via the selected‐area electron diffraction method. Three monoclinic modifications (M(I), M(II), and M(III)) were identified in the solid solutions. The modifications had pseudohexagonal subcells that were modulated t…
The dead-end radical copolymerization of 1,1-difluoroethylene (or vinylidene fluoride, VDF or VF 2 ) with hexafluoropropene (HFP) initiated by hydrogen peroxide for obtaining original fluorinated telechelic elastomers is presented. The influence of the process (solution or emulsion) and the nature and amounts of solve…
Highly ordered uniform ZnTe nanohole arrays were successfully fabricated by reactive ion etching using anodic alumina template. These ZnTe nanohole arrays transferred exactly the hexagonal lattice pattern of the original alumina template. Using this method ordered ZnTe nanoholes with pore diameter from 10 nm to severa…
We present neutron diffraction data of NiO nanoparticles measuring the total magnetization and the sublattice magnetization at various temperatures. Electron microscopy shows that the particles are disc shaped with average diameter of about 12 nm and a thickness of about 2 nm. The Néel temperature (≈ K) is less than f…
On trouve la nabesite dans des venues complexes d'albitites a tugtupite sur le plateau de Kvanefjeld, a l'extreme nord-ouest du complexe alcalin d'Ilimaussaq, dans le sud du Groenland, Elle se presente en cavites, revouverte de cristaux d'albite, en association avec gmelinite, neptunite, analcime, gonnardite, lovdarit…