Materials Literature
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The structure of dioctahedral 2:1 phyllosilicates with different interlayer charge was studied theoretically using ab initio calculations. The standard Kohn-Sham self-consistent density functional method was used in the generalized gradient approximation (GGA), with numerical atomic orbitals as the basis set, by means…
Amorphous Si‐B‐C‐N ceramic powder samples obtained by thermolysis of boron‐modified polysilazane, {B[C 2 H 4 Si(H)NH] 3 } n , were isothermally annealed at different temperatures (1400–1800°C) and hold times (3, 10, 30, and 100 h). A qualitative and semiquantitative analysis of the crystallization behavior of the mate…
Realistic interactions that operate in condensed matter systems can exhibit complicated many-particle characteristics. However, it is often useful to seek a more economical description using at most singlet and pair effective interactions that are density dependent, to take advantage of the theoretical and computation…
The microstructural evolution and grain‐boundary influence on electrical properties of Ce 0.90 Gd 0.10 O 1.95 were studied. The nanoscale powders synthesized from a semibatch reactor exhibited 50% green density and 92% sintering density at 1200°C (∼200°C lower than previous studies). Impedance spectra as a function of…
Direct reaction of thiazolidine-2-thione (tzdtH), an anti-thyroidal agent with diiodine in a molar ratio of 1:2 caused the heterolytic cleavage of diiodine and formation of [{(tzdtH)2I+}·I3−·2I2] (1), whereas the reaction of benzothiazole-2-thione (bztzdtH) with diiodine in a molar ratio of 1:2 and 1:1 resulted in the…
Equal-channel angular pressing (ECAP) was used to refine the grain sizes of pure Al and an Al-3 wt% Mg alloy containing minor additions of either Sc or Zr. Following ECAP, the grain sizes were in the ultrafine submicrometre range. Diffusion couples were prepared from the fine-grained material produced by ECAP and from…
Al2O3:C single crystals are known to exhibit some variation of their thermoluminescence (TL) glow curve shape from sample to sample. This variation is attributed to the fact that the TL peak in Al2O3:C is produced by the set of several traps. It is important to understand what part of the trap distribution correlates…
This report provides an account of research undertaken at the University of East Anglia, United Kingdom, into phthalocyanine derivatives substituted at six or more of the nonperipheral sites by alkyl groups. When first prepared they were only the second series of substituted phthalocyanines known to exhibit columnar l…
Abstract Mixed ion‐conducting ceramic membranes are promising in oxygen separation from air due to their infinite permselectivity. Hollow‐fiber‐shaped membranes can provide a high surface area for such an application. A mathematical model for a hollow‐fiber La 0.6 Sr 0.4 Co 0.2 F 0.8 O 3−δ (LSCF) membrane module for a…
To develop a rigorous, mechanistic design method for asphalt overlays, one must have a method to accurately determine the response of the overlay system to various load conditions. This paper presents a cutting-edge nonlinear three-dimensional finite-element modeling approach for asphalt overlay analysis, including a…
Results of photo- and thermodegradation of chitosan of different degrees of deacetylation (DD) were discussed. On the basis of the results of thermodegradation under isothermal and dynamic conditions thermal stability of chitosan films, also photochemically modified samples (UV irradiated for 1 h), was estimated. Inve…
Molecular dynamics results on water confined in a silica pore in the low hydration regime are presented. Strong layering effects are found due to the hydrophilic character of the substrate. The local properties of water are studied as function of both temperature and hydration level. The interaction of the thin films…
High-resolution transmission electron microscopy and digital image processing were used to investigate in detail the structure of porous silicon (PS). It was found that PS is composed of rounded Si nanocrystals with characteristic sizes between 21 and 80 Å, embedded into an amorphous matrix and with no preferential or…
The main dosimetric characteristics are presented of newly prepared tissue-equivalent, highly sensitive thermoluminescent detector, Li,B4O7:Cu,Ag,P in the form of sintered pellets, developed at the Institute of Nuclear Sciences, Vinca. As a result of an advancement in the preparation procedure by the sensitising of ba…
Different kinds of clays based on sodium montmorillonite have been modified by (1) cationic exchange of alkylammonium ions and (2) covalent grafting of organosilane. We have prepared organophilic clays with different gallery heights (due to alkylammonium ions with alkyl chain length varying from 8 to 18 carbon atoms)…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTGlass Transition Temperatures of High-Density Poly(methyl methacrylate) BrushesShinpei Yamamoto, Yoshinobu Tsujii, and Takeshi FukudaView Author Information Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Jap…
Abstract The mechanism of flame retardancy and smoke suppression by melamine in flexible polyurethane foam has been investigated using cone calorimetry, TG, DSC and pyrolysis/GC/MS. The cone calorimetric results indicate that the addition of melamine into polyurethane foam was very effective at reducing heat release r…
A tactoid phase is obtained, which is an anisotropic mesophase dispersed in an anisotropic solution. A model is constructed that describes the shape of anisotropic regions, i.e., tactoids. It is demonstrated that the prolate shape of tactoids is caused by the competition between the elastic energy of the nematic phase…
A manganese(III)-substituted polyoxometalate of the "sandwich" structure, [MnIII2ZnW(ZnW9O34)2]10-, catalyzed the highly selective (>99.9%) epoxidation of alkenes, such as 1-octene, 2-octene, and cyclohexene with nitrous oxide. Reactions occurred in homogeneous media at 150 degrees C under 1 atm N2O. The epoxidation h…
Three thulium doped tellurite glass compositions have been investigated. The 1470 nm transition is radiative in these tellurite glasses and the radiative lifetimes are in the range of 350 to 470 μs. The 1470 nm fluorescence is broad with a full width at half maximum of 105 nm. Fibers have been drawn from these glasses…