Materials Literature
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The atomic-scale dynamics of the glass-to-liquid transition are, in general, poorly understood in inorganic materials. Here, two-dimensional magic angle spinning nuclear magnetic resonance spectra collected just above the glass transition of K(2)Si(4)O(9) at temperatures as high as 583 degrees C are presented. Rates o…
The selective catalytic reduction reaction of nitric oxide bv ammonia over vanadia-titania catalysts is one of the methods of removing NOx pollution. In the present study, it has been possible to identify the reaction mechanism and the nature of the active sites in these catalysts by combining transient or steady-stat…
A simple technique is described here that produces aligned arrays of carbon nanotubes. The alignment method is based on cutting thin slices (50 to 200 nanometers) of a nanotube-polymer composite. With this parallel and well-separated configuration of nanotubes it should be possible to measure individual tube propertie…
Abstract A comprehensive non-LTE analysis of Na I lines was performed in order to investigate the photospheric abundance of sodium in typical bright A–F supergiants. Along with the strongest subordinate line, Na I λ8195, newly observed for this study, which enabled us to determine the Na abundance of A supergiants for…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
A technique of mapping a region of reciprocal space near a given substrate reflection using a standard powder diffractometer enabling (θ−ω/2θ) scan is applied to investigate superlattices grown on misoriented substrate. The parameters describing superlattice geometry are calculated on the basis of collected diffractio…
Abstract Experiments were performed to study the variation upon storage at room temperature of both the bound rubber and the rheological properties of filled rubber compounds, prepared either with high cis ‐1,4 polybutadiene or with natural rubber and various levels of a reinforcing carbon black. It was found that the…
The electric permittivity of ceramic NaNbO 3 : x Mn (x=0-1 wt.%) was measured in the range 20-500 degrees C. The Mn dopant induces an additional anomaly in the epsilon (T). The temperature of the maxima in epsilon (T) is shifted under applied axial pressure. The X-ray test proved that the anomalies in epsilon (T) are…
The characterization of nanometer-scale phase separation in sputtered, amorphous, metal-Ge and Fe-Si films has led to the observation of a new microstructure that extends through the metal-insulator transition. The phase separated regions, which are dependent on deposition conditions, are well correlated and of the or…
Abstract In this article, the graft copolymerization of methy methacrylate with canna‐starch under the initiating of manganic pyrophosphate was investigated systemly. It was found that the percentage of grafting, grafting efficiency, and rate of grafting were all dependent, to some extent, on the concentration of the…
OBJECTIVE: The purpose of this study was to demonstrate that gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) could be used as a contrast medium in CT as an alternative to iodine-based compounds. MATERIALS AND METHODS: Solutions of different concentrations of Gd-DTPA and iopromide were scanned in a tissue equi…
We present a new electro-chemical method for incorporating high concentration Er ions deep into porous silicon layers and its intense photoluminescence at ∼1.54 μm at room temperature. Porous silicon layers prepared by anodic etching of p-type silicon substrates in HF/H2O are immersed in ErCl3/ethanol solution. Then t…
Abstract Binary blend films from lactide‐rich poly( D ‐lactide‐co‐glycolide) (PDLG) and poly( L ‐lactide‐co‐glycolide) (PLLG) were obtained by casting methylene chloride solutions of the two mixed copolymers with different D‐ and L‐lactide contents ( X DI and X LI ), and their crystallization was studied by differenti…
The response of a soft-phonon ferroelectric material subjected to a high-intensity optical pulse of duration much shorter than the period of the phonon is modeled using a classical, finite-temperature simulation. It is found that complete, permanent reversal of the orientation of the ferroelectric domains may occur ev…
Abstract Stress relaxation behavior of chemically treated short sisal fiber‐reinforced natural rubber composite was studied. The effect of bonding agent, strain level, fiber loading, fiber orientation, and temperature has been studied in detail. The existence of a single relaxation pattern in the unfilled stock and a…
Abstract This article examines the blood compatibility of chitosan grafted with 2‐hydroxyethyl‐methacrylate (HEMA) using 60 Co gamma radiation. The effect of various syntheses conditions on the grafting was determined. The solvent composition has a marked effect on the degree of grafting. Maximum yield was obtained in…
Switchable polarization can be significantly suppressed in Pb(Zr,Ti)O3 thin films by optical, thermal, and electrical processes. The optical (thermal) suppression effects occur by biasing the ferroelectric near the switching threshold and illuminating the material with band-gap light (heating the material to ≊100 °C).…
Abstract The effect of zinc catalysts on the hydrolytic depolymerization of polyethylene terephthalate (PET) melts in excess water was studied using a 2‐L stirred pressure reactor at temperatures of 250, 265, and 280°C. The main products of the reaction were found to be terephthalic acid, ethylene glycol, and diethyle…
Computer simulations and experimental studies were combined to design copolymers that enhance the strength of polymer composites. These copolymers contain side chains that associate across the boundary between phase-separated regions to form a "molecular velcro" that effectively binds the regions together. This behavi…
The scaling of the cubic nonlinearity gamma with chain length in polyenic molecules has received considerable theoretical attention. Earlier experimental investigations have been restricted to oligomers with fewer than 20 double bonds because of problems associated with the synthesis and solubility of conjugated molec…