Phase-field methods for interfacial boundaries
A Landau-Ginzburg approach to an interface with finite thickness incorporates surface tension, anisotropy, curvature, and dynamics of the interface along with supercooling. Various aspects are rigorous.
Materials Literature
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Polyhedral oligometallasilsesquioxanes (POMSS) as models for silica-supported transition-metal catalysts. Synthesis and characterization of (C5Me5)Zr[(Si7O12)(c-C6H11)7]
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyhedral oligometallasilsesquioxanes (POMSS) as models for silica-supported transition-metal catalysts. Synthesis and characterization of (C5Me5)Zr[(Si7O12)(c-C6H11)7]Frank J. FeherCite this: J. Am. Chem. Soc. 1986, 108, 13, 3850–3852Publication Date (Print):June 1, 1986Pu…
High-pressure and high-temperature crystal chemistry of beryllium oxide
The crystal structure of synthetic BeO, bromellite, has been determined at several pressures to 5.0 GPa and several temperatures to 1183 K. The single variable atomic-positional parameter, z of oxygen, does not vary significantly with pressure, but does undergo a small increase with temperature. The hexagonal axial ra…
Integrated optics components and devices using periodic structures
The selected research activities on integrated optics components and devices using periodic structures are reviewed, with emphasis on the authors' works employing the electron-beam writing technique. The periodic structures include static gratings and dynamic ones produced through acoustooptic (AO) and electrooptic (E…
Performance Study of Aqueous Polyaniline Batteries
The characteristics of electrochemically produced polyaniline as the active material of secondary batteries were studied in aqueous electrolytes. The cell of the type, , has the maximum capacity of 108 Ah/kg and the energy density of 111 Wh/kg. The coulombic efficiency was close to 100% over at least 2000 complete cyc…
Site-directed mutagenesis and the role of the oxyanion hole in subtilisin.
Oligonucleotide-directed mutagenesis was used to investigate the nature of transition state stabilization in the catalytic mechanism of the serine protease, subtilisin BPN'. The gene for this extracellular enzyme from Bacillus amyloliquefaciens has been cloned and expressed in Bacillus subtilis. In the transition stat…
A Study of Chemically Synthesized Polypyrrole as Electrode Material for Battery Applications
We have studied the behavior of a chemically synthesized polypyrrole as electrode material. The different electrochemical methods that we have used for this characterization, namely, cyclic voltammetry, ac impedance measurements, and cyclic chronopotentiometry, have evidenced the role of the low frequency capacitance…
Compensating Defects in Highly Donor‐Doped BaTiO 3
Nb‐doped BaTiO 3 has been prepared with various Ba/(Ti + Nb) ratios such that single‐phase products will be obtained if the charged donor center is assumed to be compensated in turn by Ba vacancies, Ti vacancies, equal concentrations of the two cation vacancies, oxygen interstitials, or electrons. For air‐Fired sample…
Long-range internal stresses and asymmetric X-ray line-broadening in tensile-deformed [001]-orientated copper single crystals
Copper single crystals oriented for multiple slip with [001] axes have been deformed in tension and investigated by X-ray line-broadening measurements using {002} Bragg reflections. The intensity distributions of the broadened line profiles of the deformed crystals exhibit an asymmetry whose ‘sign’ depends on the part…
A model for conductor failure considering diffusion concurrently with electromigration resulting in a current exponent of 2
A model was constructed for electromigration failure where both Fickian diffusion and mass transport due to the electromigration driving force are considered concurrently. The solution to the resulting diffusion equation yields a current exponent of 2 and an activation energy consistent with grain-boundary self-diffus…
Magneto-Solid Mechanics
REVIEWSpresented in this section begin with two papers which sketch how to calculate the forces in hydrodynamic journal bearings and tilting pad bearings.Six papers then address instabilities due to: internal energy dissipation; asymmetries (such as bearing stiffnesses or inertias) which introduce time dependent param…
Resistencia química del hormigón XXV. Influencia de la adición de escoria a un cemento Portland. Estudio de la concentración iónica del sistema cemento 3/escoria-agua potable filtrada
This work, which follows on others, study the variation of the pH, and likewise the concentrations of the ions Ca (II) and SO4 (II) of the filtered potable water in which there were submerged the test specimens of mortar (1:3) made with a Portland cement (cement 3 < > P-450) and with the mixtures cement 3/slag = 85/15…
Inductively coupled plasma emission spectrometry
Inductively coupled plasma emission spectroscopy technique (ICP) raised as a step forward in traditional emission spectroscopy, has allowed the quantification, even from a trace, of the elements of a sample by means of the elimination of most of the chemical interferences. In this paper, a view of the subject is given…
False set in aireated cements
The influence of aireation on the appearance or elimination of the false setting in industrial portland cements is studied by means of infrared spectroscopy.
New test for determining fundamental transverse, longitudinal and torsional frequencies of concrete specimens
For twenty-five years The ASTM method used to determine reductions in concrete durability after freeze-thaw cycling has been C215-60. In this test the fundamental frequencies of a concrete specimen are compared. This test is time consuming, noisy and often inaccurate. In this paper a new method is proposed for measuri…
Nota Necrológica: Don Pablo
Noticias
Magnetic anisotropy of MnAl and MnAlC permanent magnet materials
The magnetocrystalline anisotropy of MnAl and MnAlC alloys, in the range of existence of the ferromagnetic τ phase, has been studied by using the singular point detection technique. The anisotropy field value at 293 K varies from 39 kOe for low manganese and high carbon content to 55 kOe for high manganese and carbon-…
Helmholtz’s theorem revisited
Helmholtz’s theorem for three-vectors is applicable to electrostatics and magnetostatics, but it must be generalized to antisymmetric second-rank tensors to be applicable to electromagnetism. A proof of Helmholtz’s theorem for three-vectors, which is shorter than the usual one, is given. Helmholtz’s theorem is shown t…
Mass transfer and electrochemical kinetic interactions in localized pitting corrosion
Abstract Identification and characterization of coupled diffusional and electrochemical kinetics effects was achieved under potentiostatic anodic dissolution conditions. A one‐dimensional artificial pit geometry with sample wire electrodes embedded in an inert support exposed to NaCl solutions was used to study the di…