Materials Literature
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We have used a sol−gel technique to obtain optically transparent hydrogels in which water is trapped within a tridimensional disordered silica matrix. A suitable aging of these hydrogels enables to have transparent noncracking samples down to cryogenic temperatures. We report the optical absorption spectra, in the nea…
Abstract Commercial products such as photographic materials and speciality papers manufactured by single or multilayer coating processes, all have some surface topographic structure. Nevertheless, for many materials, a uniform plane approximates their surface, and analyses of dynamic wetting, a fundamental physical pr…
Abstract Single‐wall nanotubes (SWNTs) embedded in polymer can be used as mechanical sensors because the position of the D* Raman band of SWNTs is strongly dependent on the strain transferred from the matrix to the nanotubes. In order to detect the stress (or strain) information in specific directions, polarized Raman…
We numerically analyze the origin of the transmission losses in left-handed structures. Our data confirms that left-handed structures can have very good transmission properties, in spite of the expectable dispersion of their effective permeability and refraction index. The large permittivity of the metallic components…
Commercially available α‐alumina powder with high‐purity, submicrometer particle size and narrow particle‐size distribution is used as starting material to prepare dense ceramic parts with transparent properties. The powder is dispersed and stabilized in a water‐based suspension. Controlled consolidation and drying by…
Abstract In this study, novel biodegradable polymers were synthesized by ring opening polymerization (ROP) of L ‐lactide on chitin in an N,N ‐dimethyl acetamide (DMAc)/lithium chloride (LiCl) solvent system, and chitin was used as macroinitiator to afford new materials. Lithium chloride (LiCl) was used as catalyst. Th…
We compare the vibrational properties of model SiO 2 glasses generated by molecular-dynamics simulations using the effective force field of van Beest et al. (BKS) with those obtained when the BKS structure is relaxed using an ab initio calculation in the framework of the density functional theory. We find that this re…
Cavity ring-down spectroscopy has been used to measure the absorbances, concentrations and temperatures of C2(a3Πu v=0) and CH(X2Π v=0) radicals in a ⩽10 kW dc arc jet used for chemical vapor deposition (CVD) of polycrystalline diamond films and operated with CH4/H2/Ar gas mixtures. Gas temperatures derived from the i…
The methodology developed for evaluating, by total reflection X-ray fluorescence, the main elements in used three-way catalysts for cars after more than 59 000 km is described. The analytical method does not require chemical manipulation of the samples, is quick (30 min for sample preparation and 10 min for analysis),…
A novel precursor, hexakis[μ-(diethylcarbamato-O:O‘)]-μ 4 -oxotetrazinc, (Zn 4 O(CO 2 NEt 2 ) 6 ) ( 1 ), for the single source chemical vapor deposition (SSCVD) growth of ZnO films has been developed. The structure and chemistry of resultant films were characterized using photoemission spectroscopy and diffraction tec…
[formula: see text] A simple straightforward synthesis for meso-monosubstituted, beta-unsubstituted porphyrins is reported. Porphyrins of this type are easily prepared by condensation of dipyrromethane, pyrrole-2-carbaldehyde, and the desired aromatic or aliphatic aldehyde. The method can be used for a variety of func…
Abstract The adsorption of metals by clay minerals is a complex process involving different mechanisms, and is controlled by different variables which can interact. The aim of this work was to study the retention mechanisms of Cd on illite. We obtained Cd adsorption isotherms at constant pH, adsorption edges as a func…
A surface modification technique was employed to functionalize electrically conductive polypyrrole (PPY) films with hyaluronic acid (HA). The PPY film was first graft copolymerized with 2-hydroxyethyl acrylate (HEA) and subsequently silanized with (3-aminopropyl)triethoxysilane (ATS) via Si−O bonding with the hydroxyl…
We investigate the transport properties of telescoping carbon nanotubes (TCNT's), where one nanotube slides into the other tube with a larger diameter, through multiband tight-binding theoretical calculations. In armchair TCNT's which consist of armchair nanotubes, since the two ${\ensuremath{\pi}}^{*}$ states of the…
Abstract Manufactured articles of semicrystalline polymers usually have a variation in texture (degree of crystallinity and crystal orientation) as a function of the depth from the external surface. This is often due to the fact that the crystallization process near the surfaces occurs at different conditions and rate…
The effects of changes in the fibre orientation on the mechanical properties of nonwoven composites were investigated through 3-point bending, short beam shear and tensile tests. Oxidized polyacrylonitrile(PAN) carded webs were needle-punched, and then carbonized to fabricate carbon composites with phenolic resin. The…
The stretch film industry has grown at phenomenal rates over the past 6-8 years. During that time, stretch film has evolved from monolayer to three layer and now commonly a five or seven layer product. This film is processed on equipment that varies in size and width along with other technological differences. This pa…
Latex waste products contain rubber hydrocarbon of very high quality, which is only lightly cross linked. Selected wastes such as thread waste and glove waste were modified into processable materials by a novel economic process and thermoplastic elastomers were prepared by blending these modified waste materials with…
Abstract New experimental data with respect to the solubility of natural and synthesized magadiite at elevated temperatures and in alkaline solutions are presented. The results show that the solubility of magadiite increases according to the expression ln(K mag ) = −8146· T (K) −1 − 5.71 from 20 to 100°C ( <mml:math x…
Abstract Quantification of aluminium in the presence of copper is a fundamental problem in XPS analysis due to peak overlap. This article presents and demonstrates the utility of a simple approach to alleviate this difficulty based on measurement of the P : S combination peak area ratio. It is particularly appropriate…