Materials Literature
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Abstract SERS technique wae used to study the chemiesorption kinetics of Methylene Blue (MB) on the HNO 3 ‐etched silver surface. The adsorption kinetic parameters were deduced from different vibrational modes at a low concentration of 3.5 × 10 −6 mol/L, and it showed that MB adsorbed uniformly (monolayerly) on silver…
A new method for the numerical generation of nanotube caps based on unfolding of caps onto honeycomb lattice is developed. Expressions connecting the components of the tubular vector and coordinates of pentagonal defects on the honeycomb lattice are derived. Numerical solutions of the Diophantine equations give a full…
Dynamics in solution and photochromic properties of radical copolymers of 4-(4-oxy-4′-cyanoazobenzene)but-1-yl methacrylate, 6-(4-oxy-4′-cyanoazobenzene)hex-1-yl methacrylate, and 8-(4-oxy-4′-cyanoazobenzene)oct-1-yl methacrylate with (–)-menthyl methacrylate were investigated. 13C NMR and 2D HETCOR spectroscopy allow…
It is well known that, due to the absence of an intrinsic length scale, conventional rate-independent plasticity theories fail to explain the size effects observed in problems such as shear-flow localization, nanoindentation tests and precipitate hardening. Consequently, several new nonlocal/gradient constitutive theo…
Abstract The structural and thermal properties of polyhydroxybutyrate (PHB) gels in dimethylformamide (DMF) are presented and discussed. The dilute and semi‐dilute mixed PHB/DMF system undergoes a phase separation on cooling at a temperature T gel, producing a gel in which the crystalline fraction is of the order of 5…
A quantum mechanical technique based on the local density approximation has been used to predict the geometries, energetics and electronic structures of small clusters consisting of one to four pairs of atoms, (MX) n , n = 1-4. The materials modelled were NaF, NaCl, NaBr, MgO, AlN and Sic. Convergence, as a function o…
Hydrotalcites were prepared with various Mg/Al ratios. The influence of pH and alkaline solution of the precipitation were examined. The compounds are well cristallized when the precipitation is done with NaOH + Na2CO3 alkaline solutions at pH near 10. These samples contain Cl- and (CO3)2- compensating anions in the i…
David A. Siqueiros Beltrones, Edna Sanchez Castrejon, Structure of Benthic Diatom Assemblages from a Mangrove Environment in a Mexican Subtropical Lagoon, Biotropica, Vol. 31, No. 1 (Mar., 1999), pp. 48-70
Reactions of 2,2′-dipyridylamine (dpyam) with cadmium halides yield crystals of [Cd(dpyam)(H 2 O )Cl 2 ] (1), [Cd(dpyam)Br 2 ] (2), and [Cd(dpyam)I 2 ] (3). With CuCl 2 and KCN a complex [Cu(dpyam )CN] · H 2 O (4) is obtained. Depending on the size of the halide ions the coordination changes from octahedral in 1 to tr…
The rate at which a drug enters the bloodstream is an important characteristic of any drug product because it may have a marked influence on the biological response elicited by the drug. Before entering the bloodstream a solid dosage form (tablet or capsule) must first dissolve and then the drug in solution is absorbe…
Electron energy-loss spectra of (V 1- x Cr x ) 2 O 3 ( x =0.012) at the antiferromagnetic insulating (AFI), paramagnetic metallic (PM) and paramagnetic insulating (PI) phases have been measured using a high-resolution transmission electron energy-loss spectroscopy (EELS) microscope. The changes in the EELS spectra at…
Andisols of the Kitakami mountain range were derived from a mixture of tephras and long range eolian dust deposited during the Quaternary. Thus, the relative proportions of the components of the mixture determined the unique properties of the soils. Soils of the northern and central parts of the mountain range were de…
Two new ferroelectric liquid crystals, 4-[(S)-1-(ethoxycarbonyl)]ethyl 4-[4-(9-decenyloxy)biphenyl]azobenzoate (10) and its ester analogue 4-[(S)-1-(ethoxycarbonyl)]ethyl {[4-(9-decenyloxy)]biphenyl-4'-yl}carbonyloxybenzoate (17), and side chain polysiloxane copolymers and terpolymers containing various amounts of 10…
The steady-state and time-resolved fluorescence and 1H NMR spectra of a stilbenesulphonic acid salt, commonly used as an optical brightening agent, was studied as a function of concentration in aqueous solution. The aggregates, formed at higher concentrations, were shown to be predominantly dimers with the central sti…
A model of a stochastic froth is introduced in which the rate of random coalescence of a pair of bubbles depends on an inverse power law of their sizes. The main question of interest is whether froths with a large number of bubbles can grow in a stable fashion; that is, whether under some time-varying change of scale…
Barium titanate ceramics having grain sizes between 0.5μm and 20μm were used in a comparative investigation of the ferro-para phase transition, by recording the temperature dependencies of the heat capacity and pyrocharge. The experimental results and the theoretical approach suggest that internal stresses are the mai…
X-ray photoelectron diffraction fine structure of Si(100) is studied with precise angle-resolved X-ray photoelectron spectroscopy. Polar-angle intensity distributions of the Si 2p photoelectron emission excited by Al Kα X-rays are measured from H-terminated Si(100) along some azimuthal angles, and are qualitatively in…
The influence of phosphate (P) on the adsorption‐desorption of zinc (Zn) and on Zn fractions was examined for four variable charge soils. The soils were two kaolinitic Alfisols and two Andisols containing high amount of amorphous materials. Zinc adsorption‐desorption isotherms were produced using a batch protocol invo…
Abstract The stabilization effect of alkyltin thioglycolates was determined by the measurement of discoloration of PVC formulations. The results were interpreted considering the structure of these compounds, their equilibration with alkyltin chlorides, and their postulated association with chlorine atoms at PVC primar…
<div class="htmlview paragraph">Carbon canisters have been adapted for automobile use since the early 1970s to control evaporative emissions. Stringent emission regulations and the requirement for an enhanced evaporative emissions test procedure, make this an important issue. The air and evaporative fuel from th…