Materials Literature
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The reaction of racemic 5,5′,6,6′- tetramethyl-3,3′-di-tert-butyl-1,1′-biphenyl-2,2′-diol (biphenolate-H2) with 4 mol equiv. of nBuLi yields [(μ3,μ3-biphenolate)2Li4(nBuLi)4] (1) in high yield. 1 further reacts with 4 mol equiv. of 2,4-dimethyl-3-pentanol in the presence of tetrahydrofuran (THF) or cyclohexene oxide (…
We report on the transient-enhanced shape transformation of nano-structured Si(001) surfaces upon in vacuo annealing at relatively low temperatures of 1175K - 1225K for a few minutes. We find dramatic surface mass transport concomitant with the development of low-energy facets on surfaces that are covered by native ox…
We present results of the magneto-crystalline anisotropy energy (MAE) calculations for chemically ordered $L1_0$ CoPt and FePt alloys taking into account the effects of strong electronic correlations and spin-orbit coupling. The local spin density + Hubbard U approximation (LSDA+U) is shown to provide a consistent pic…
We measure phonon dispersion and linewidth in a single crystal of MgB_2 along the Gamma-A, Gamma-M and A-L directions using inelastic X-Ray scattering. We use Density Functional Theory to compute the effect of both electron-phonon coupling and anharmonicity on the linewidth, obtaining excellent agreement with experime…
Based on ab initio total energy calculations we show that two magnetic states of rhodium atoms together with competing ferromagnetic and antiferromagnetic exchange interactions are responsible for a temperature induced metamagnetic phase transition, which experimentally is observed for stoichiometric alpha-FeRh. A fir…
Assemblies consisting of nanosized silver particles, 4-aminothiophenol, and the smooth macroscopic surface of silver metal (Ag/PATP/Ag) were prepared and characterized by surface-enhanced Raman spectroscopy. The Raman spectrum of 4-aminothiophenol in the assemblies is similar to that obtained on the electrochemically…
We study atomistically the fracture of single crystal silicon at atomically sharp notches with opening angles of 0 degrees (a crack), 70.53 degrees, 90 degrees and 125.3 degrees. Such notches occur in silicon that has been formed by etching into microelectromechanical structures and tend to be the initiation sites for…
The bandstructure of pentacene is calculated using first-principles density functional theory. A large anisotropy of the hole and electron effective masses within the molecular planes is found. The band dispersion of the HOMO and the LUMO is analyzed with the help of a tight-binding fit. The anisotropy is shown to be…
Measurements of light emission from a scanning tunneling microscope probing a Na overlayer on the (111) surface of Cu are reported along with results of a model calculation that essentially agree with the experimental ones. The observed light emission spectra show two characteristic features depending on the bias volt…
Plasma treatment of polymers encompasses a variety of plasma technologies and polymeric materials for a wide range of applications and dates back to at least the 1960s. In this article we provide a brief review of the United States patent literature on plasma surface modification technologies and a brief review of the…
Experiments designed to investigate surface degradation of XLPE by corona discharges between circular electrodes are described. Charge injection behavior was also studied by measuring the surface potential V/sub s/, which was found to be radially symmetrical and strongly influenced by the particular conditions of the…
The damage in power capacitor dielectrics by harmonics in power networks is investigated. Five typical distorted waves generated by an HV (high-voltage) harmonic testing installation were recorded in tests of four model types of capacitors. Results show that all waves containing harmonics of different order have damag…
A solar photovoltaic (PV) thermoelectric generator (TEG) hybrid system combines the economics of a solar photovoltaic system with the reliability and heating capability of a thermoelectric generator system. The solar system provides power during seasons with abundant sunshine while the thermoelectric generator system…
A description is given of the principles and practice regarding degree-of-polymerization (DP) measurements and applications in which they are used to evaluate the degree of aging. The authors discuss the possibility of expediting lifetime predictions using expert system techniques. Experience shows that the DP measure…
A research program has been initiated to determine if propylene carbonate can be used as an insulator in the high-voltage accelerator field. Electrical properties, such as dielectric strength, resistivity, frequency response, and surface tracking, have been investigated. Initial tests show that propylene carbonate can…
The Solidification Using a Baffle in Sealed Ampoules (SUBSA) and Pore Formation and Mobility Investigation (PFMI) furnaces were developed for operation in the International Space Station (ISS) Microgravity Science Glovebox (MSG). Both furnaces were launched to the ISS on STS-111, June 4, 2002, and are currently in use…
Abstract Polymerization of styrene in aqueous dispersions of the dodecanamide derivative of poly(propyleneimine) dendrimer DAB‐ dendr ‐(NH 2 ) 64 and sodium dodecyl sulfate (SDS) produced stable latices. With initial SDS concentrations of 10 mM or less, molar ratios of SDS to dendrimer end groups ranging from 2.3:1 to…
The technological revolution and busy schedule compel human society to search for better civic amenities. This leads to the use of modern personal care goods such as disposable diapers and sanitary napkins. Presently, all of the goods use microporous polyolefin films. The high-strength microporous polyolefin films als…
Electric stress, voltage waveshape, temperature, contaminants and insulation resistance to oxidation have been analyzed as to their influence on triggering breakdown of a water-treed polymer. The transition from a water tree to an electrical tree is dependent on several factors, including voltage waveshape, and magnit…
A laboratory investigation was undertaken to study the nature of surface charge decay and its mechanism with several synthetic organic materials after both corona and contact charging in different environments. Some results for low-density polyethylene (LDPE) are presented and discussed. The behaviour of the decay sho…