Materials Literature
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The formation of iron oxide films and their roles in determining the dry wear properties of low alloy steel couples are described. Essentially, alpha-Fe<SUB>2</SUB>O<SUB>3</SUB>, haematites (Fe<SUB>3</SUB>O<SUB>4</SUB>), wustite (FeO) and oxide mixtures were the predominant compositions found in four regions of mild o…
Lead is one of the poisonous elements for de-NO x catalysts especially in the case of municipal waste incineration plants. Samples of a commercial selective catalytic reduction catalyst were impregnated with different amounts of Pb(NO 3 ) 2, and their catalytic activities were studied. The XPS and SEM analysis showed…
Poly(lactide) is synthesized by ring-opening copolymerization of various combinations of l -lactide, d -lactide, and meso -lactide. The influence of the stereochemical differences of the three lactides on the kinetics of melt copolymerization was determined by monitoring the change in the polymer stereosequence distri…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHemiporphyrazines as Targets for the Preparation of Molecular Materials: Synthesis and Physical PropertiesFernando Fernández-Lázaro, Tomás Torres, Bernd Hauschel, and Michael HanackView Author Information Departamento de Química Orgánica (C-I), Universidad Autónoma de Madrid…
Oxidized and reduced cobalt(II) hexacyanoferrates were fabricated and characterized in the presence of alkali metal (Li +, Na +, K +, Cs + ) and Co 2+ countercations. Formal potentials of hexacyanoferrate(III,II) redox reactions are sensitive to the choice of electrolyte cation, and they correlate well with the sizes…
Classification, nomenclature, and structure representation are presented for dendritic and star polymers in SCION, a DuPont proprietary scientific and technical online database. The problems of registering dendritic and hyperbranched structural repeating units (SRUs) with odd numbers of crossing bonds are described, a…
Reaction of Ag[C3(CN)5] and [MnIIITPP]Cl (TPP = meso-tetraphenylporphinato) leads to [MnIIITPP]+[C3(CN)5]-, which has been crystallographically, spectroscopically, and magnetically characterized.This complex forms a 1-D ···D+A-D+A-··· coordination polymer with [C3(CN)5]- (A) having an unusual μ asymmetric bridge bondi…
Zirconia-based systems have been extensively studied for some 25 years, and a wealth of exciting results has been amassed. This book tracks the progress made in the field; from very early phase stability work, to modern approaches which involve quite sophisticated models for the transformation toughening that is assoc…
In the absence of suitable single crystals, the problem of determining the connectivity pattern of the title compound (and of its phenyl analogue), i.e. that of discriminating between two markedly different stereoisomers, has been solved by the powder diffraction technique. The structure was solved by ab initio XRPD m…
To improve adhesion between polypyrrole and glass, new pyrrole-substituted organotrialkoxysilanes coupling agents are synthesized and studied. Solubility, hydrolysis, and self-condensation features in aqueous solutions are investigated by IR, 1 H, and 29 Si NMR spectroscopies. Varying the experimental conditions of py…
We present first-principles total-energy calculations of (001) surfaces of SrTiO3. Both SrO-terminated and TiO2-terminated surfaces are considered, and the results are compared with previous calculations for BaTiO3 surfaces. The major differences are in the details of the relaxed surface structures. Our calculations a…
Monte Carlo simulations with an effective Hamiltonian parametrized from first principles are performed to study the dielectric response of BaTiO3 as a function of temperature, with particular emphasis on the behavior of the dielectric constant near the transition from the ferroelectric tetragonal phase to the paraelec…
The elastic theory of quasicrystals considers, in addition to the normal displacement field, three phason degrees of freedom. We present an approximative solution for the elastic Green's function of icosahedral quasicrystals, assuming that the coupling between the phonons and phasons is small.
First-principles calculations are performed to investigate alloying and ferroelectric effects in lead zirconate titanate (PZT) with high Ti composition. We find that the main effect of alloying in the paraelectric phase of PZT is the existence of two sets of B-O bonds, i.e., shorter Ti-O bonds vs. longer Zr-O bonds. O…
The electronic ground state of a periodic crystalline solid is usually described in terms of extended Bloch orbitals; localized Wannier functions can alternatively be used. These two representations are connected by families of unitary transformations, carrying a large degree of arbitrariness. We have developed a loca…
Starch ethers having side chains of various lengths, controlled and uniform degrees of substitution, and various amylose/amylopectin ratios were obtained by a one-step chemical modification of starch. Factors influencing the phase behavior of these starch ethers were carefully examined, and the ones having short side…
The improvements in mechanical properties obtained by orienting starch−ether films were further examined, specifically with regard to their dependence on degree of substitution of the starch and on its amylose/amylopectin ratio. It was found that the degree of substitution had little or no influence on the mechanical…
In the presence of dioxygen, four cobalt complexes of linear tetrapyrroles, Co(OEB) (OEB is the trianion of octaethylbiliverdin), [Co II (OEBOx)]I 3 (OEBOx is the monoanion of the oxidized form of octaethylbiliverdin), Co II (OEFB) (OEFB is the octaethylformylbiliverdin dianion), and Co II (OEBOMe) (OEBOMe is the dian…
Abstract Although the traditional fluid loss control systems used in high permeability completions have received considerable discussion in literature, most of the documentation reviews the application of individual systems only; little is provided on how to evaluate which method is best suited for a given situation.…
Methylpheophorbide- a (a chlorophyll a analog) was converted into methyl 13 1 -deoxypyropheophorbide- a 2 in excellent yield. The Ni(II) complex of 2 on hydrogenation and subsequent Vilsmeier reaction with phosphorus oxychloride and 3-( N, N -dimethylamino)acrolein produced Ni(II) methyl 20-(2-formylvinyl)-13 1 -deoxy…