Materials Literature
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Ab initio and semiempirical calculations of large cluster models have been performed in order to study water adsorption and dissociation on pure, defective (vacancies) and doped (Li, Na, K, Ca, Fe) MgO (001) surfaces. The geometries of the adsorbed and dissociated molecules have been optimized preparatory to analysis…
This paper involves novel fabrication processes for polycrystalline α‐Al 2 O 3 ‐matrix composite fibers that contain nanosized yttrium aluminum garnet (YAG) particles. Dense α‐Al 2 O 3 /YAG nanocomposite fibers with a fine and homogeneous microstructure can be successfully fabricated via a modified sol‐gel process and…
Recent studies have shown that the measured flash widths from single and multibubble sonoluminescence are in subnanosecond or even picosecond regime. Here, we provide conclusive evidence for the existence of nanosecond multibubble sonoluminescence. This has become possible by our ability to find a medium from which ex…
New octupolar bithiophenic methyl cations belonging to the Crystal Violet family are described (see Figure). The synthesis and electrochemical properties of these cations, which should combine the second-order nonlinear optical properties of Crystal Violet with the electrochemical properties of heterocycles, are repor…
A simple model was developed for the interpretation of results stemming from the XPS analysis of polymer surfaces modified by polyethyleneimine adsorption followed by surface coupling of polysaccharides. Theoretical surface compositions were evaluated from the calculated XPS intensity arising from a layered structure…
Elastic constants of a bulk silicon crystal are calculated using the Monte Carlo (MC) technique in conjunction with an isoenthalpic-isotension-isobaric ensemble (HtN ensemble) and the Stillinger-Weber (SW) potential or one of the Tersoff potentials. This MC method is the counterpart of the Parrinello-Rahman HtN molecu…
The optical properties of cholesteric and chiral smectic-$C$ liquid crystals having a pitch shorter than the light wavelength are studied, both theoretically and experimentally. A particular emphasis is placed on the optical activity. For smectics, the optical rotation is maximum for a tilt angle of $45\ifmmode^\circ\…
The role of ammonium ions in order–disorder ferroelastic, ferroelectric and structural phase transitions was studied in mixed [(NH4)1–x Rb x ]3H(SO4)2 0 < x < 1 crystals by dielectric spectroscopy and ac calorimetry. A new superprotonic phase was detected in compounds with x > 0·6. It was found that small Rb concentra…
Summary Permafrost desiccates and indurates soil horizons. During summer, the perennially frozen ground under the active thawed layer creates confined conditions, Whereas in winter the closed system between the permafrost and the freezing front migrating downwards leads to irreversible changes in the soil structure an…
Abstract An investigation of the influence of the melt shear viscosities of polyethylenes (PE) on the morphology, barrier, and impact properties of polyethylene/modified polyamide PE/MPA bottles is reported. The melt shear viscosities of polyethylenes exhibited a significant influence on the deformation and morphology…
The objective of this research was to investigate the use of electrochemical noise (EN) for detecting stress corrosion crack (SCC) initiation in boiling water reactor (BWR) environments. Initial experiments examined the response of sensitized AISI Type 304 stainless steel (SS) in slow strain-rate tensile (SSRT) tests…
A method is described for converting video signals of analog scanning electron microscopes (SEMs) into digital images of high quality. A plug-in card commercially available for personal computers is used for the on-line analog/digital conversion. A Windows application program written by the authors, together with low-…
Abstract 2,2′-(Dihexyl-2,2′-bithienylidene-5,5′-diylidene)bis(propanedinitrile)s (dihexylbithienoquinonoid derivatives), in which two 3-hexylthiophene moieties are connected with head-to-tail (HT) and tail-to-tail (TT) orientations, were synthesized. HT bithienoquinonoid was isolated in a single form together with a s…
We grew large single crystals of reproducibly over a wide doping range using an improved travelling solvent floating zone (TSFZ) method. We performed a simulation on the lamp-image focusing to find an optimum condition for a steep temperature gradient along the rod. Based on the results of simulation, we adapted small…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOn the Mechanism of Matrix-Assisted Room Temperature PhosphorescenceChristine A. Mitchell, Richard W. Gurney, Sei-Hum Jang, and Bart KahrView Author Information Department of Chemistry, Box 351700 University of Washington, Seattle, Washington 98195-1700 Cite this: J. A…
Films of Ti oxide, Zr oxide, Ce oxide, Ti-Ce oxide, and Zr-Ce oxide were made by means of reactive dc magnetron sputtering in a multitarget arrangement. The films were characterized by x-ray diffraction and electrochemical measurements, both techniques being firmly connected to stoichiometric information. The optical…
The melting behavior and the isothermal crystallization kinetics of poly(butylene adipate), poly(butylene isophthalate) and their random copolymers were investigated by means of differential scanning calorimetry. Multiple endotherms, commonly observed on the melting polyesters, were found to be influenced by crystalli…
Optical properties of porous silicon superlattices are investigated using variable angle spectroscopic ellipsometry. Different phenomena such as in-depth inhomogeneities and interface transition regions are resolved and studied using various optical models. The optical properties of the samples are modified irreversib…
Abstract The covalent connection of a catalytically active transition metal center with a water‐soluble receptor (host molecule) generates a new type of supramolecular catalyst in which the features of molecular recognition, phase transfer catalysis and transition metal catalysis are combined in a single system. The f…
By solving numerically the full set of hydrodynamic equations governing the pulsation of a bubble, we show that shock waves are often absent in a stable sonoluminescing bubble. Nevertheless, for a wide range of physical parameters, a continuous compressional wave emerges and heats up the bubble, and the resulting blac…