Materials Literature
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On high performance military aircraft, small changes in both wing twist and wing camber have the potential to provide substantial payoffs in terms of additional lift and enhanced maneuverability. To achieve the required wing shape, actuators made of smart materials are currently being studied under an ARPA/WL contract…
Results from a study on the epilithic diatom communities of a polluted river (Río Grande de Tárcoles basin) and an unpolluted river (Río Savegre) in the Central and Southern part of Costa Rica are presented. In this context the taxonomy of diatoms, the most abundant group of algae found in both rivers, is discussed. A…
Abstract We report on the gas phase reactions of small Fe + n clusters ( n = 2–10) with O 2 , N 2 O and CO 2 in an FT‐ICR mass spectrometer. Under our experimental conditions, clusters of all sizes reacted readily with O 2 and all but the dimer reacted with N 2 O. Only the smallest Fe + n clusters ( n = 2–4) appeared…
The surface properties of acrylic films, obtained through UV curing of bisphenol-A-dihydroxyethyl diacrylate (BHEDA) mixed with fluorinated acrylic monomers, were investigated. Three fluorinated acrylates were selected in order to vary the film composition, namely: 2-(n-perfluorooctylsulphonamido-N-butyl)ethyl acrylat…
Extensive recent efforts to understand the intrinsic brittleness or ductility of materials have focused on crack-blunting mechanisms using the Peierls stress concept. So far, the effects due to newly created ledge surface during crack propagation have been either ignored or included within some semiempirical approxima…
In judging the effectiveness of methods of solving crystal structures, it is customary to use the mean phase error or the map correlation coefficient as a measure of success. When methods for ab initio phase determination are being developed, it is necessary to take into account that the solutions found may correspond…
There are several difficulties in calculating eddy currents in plates with thin slits by the finite element method (FEM). Under the influence of flat finite elements at slits, the accuracy of analysis decreases and the computation time increases. Using the A-/spl phi/ method, we propose a novel technique, which overco…
Novel liquid crystalline composites (LCC) based on a nematic liquid crystal and fine plate-like caly minerals have been prepared by mixing the two components. The observation of the LCCs by a polarized optical microscope revealed that the plate like particles of the clay mineral were dispersed homogeneously and their…
The magnetic properties and microstructure of barium ferrite films (BaFe12O19) coated by a sol-gel technique involving a spin coating of metal-organic compounds are investigated. The in-plane magnetic properties and the grain size are controlled by a Fe/Ba atomic ratio in the coating solution and annealing conditions.…
SiC/AIN composites with controlled interfacial solid solution were employed in the present work for investigating the effects of interfacial bonding and A1N polytypes on the mechanical properties. Platelike A1N polytypes and interfacial bonding were found to have substantial effects on the flexural strength, hardness,…
Shrinking device geometry has produced a need for lower dielectric constant materials for intermetal dielectric to reduce circuit RC time constants and intertrace ‘‘cross-talk’’ capacitance and reduce power consumption at high frequency. One such material is F-doped SiO2. This study utilized an electron cyclotron reso…
The nucleation and evolution of deformation patterns occurring during transgranular stress corrosion cracking (TGSCC) were studied in an attempt to produce new alternatives for addressing the nature of the embrittlement process. Flat, tensile α-brass (72% Cu-28% Zn) specimens were tested in 5 M aqueous ammonia (NH4OH)…
To simulate the electrochemical properties of acceptor‐doped lanthanum chromites as interconnectors for solid oxide fuel cells, theoretical analyses of the distribution of oxygen chemical potential, ionic leak current density, and area specific resistance are given. The results of the calculations using previously rep…
Facet formation and competition in selective epitaxial growth (SEG) of Si on SiO2− masked nanometer growth windows were studied experimentally and theoretically in gas source molecular beam epitaxy. The windows were patterned along [110] on Si(100) substrates. Mass accumulation around the edge of the SEG mesa top surf…
Hot-fillable, re-fillable, high oxygen-barrier and high UV-barrier containers cannot be conveniently made with poly(ethylene terephthalate). Copolyesters of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, prepared through either melt-polycondensation or blending, are very promising material fo…
When surface plasmon polaritons propagate on a corrugated surface, an energy gap opens up in the dispersion of the surface mode. We present the results of an experimental technique that directly images this gap. The technique is used to measure the width and the central frequency of the gap as a function of the gratin…
The heat transfer rate and efficiency of TE (thermoelectric) cooling systems were investigated. The emphasis of the present study is focused on the use of large-scale TE refrigerators for air conditioning applications. A one-dimensional heat transfer analysis was performed to determine the cooling power and electricit…
As the semiconductor industry inches towards integrated circuit technology based on silicon chips with features just 200 nm wide, researchers are trying to build carbon-based electronic devices that are hundreds of times smaller. These devices would be based on the remarkable electronic properties of carbon nanotubes…
We calculated the electronic states of ferroelectric perovskite oxides, A TiO 3 , using the discrete variational Xα cluster method. The bond order of the π bonds between Ti 3 d and O 2 p as a function of titanium ion displacement in PbTiO 3 shows a maximum. This result suggests that the magnitude of ferroelectricity i…
The stability and kinetics of unfolding and refolding of the P167T mutant of the TEM-1 beta-lactamase have been investigated as a function of guanidine hydrochloride concentration. The activity of the mutant enzyme was not significantly modified, which strongly suggests that the Glu166-Thr167 peptide bond, like the Gl…