Materials Literature
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Third-order nonlinear optical properties of As2S3 chalcogenide bulk glass are studied experimentally. Third-harmonic generation (THG) measurement shows the value of the third-order susceptibility χ(3) to be 5.6×10−19 m2/V2 (1.0×10−11 esu) at the funda- mental-light wavelength of 2.1 μm. This value is more than 300 tim…
The temperature dependences of the fluorescence lifetimes of ${\mathrm{Cr}}^{3+}$ doped insulating crystals, which have been used as temperature-sensing elements or have such potential uses for different temperature regions, are reviewed in terms of the crystal-field strength. Two single configurational coordinate mod…
A recently introduced bead-spring type model of polymer chains with purely repulsive interactions between the beads is modified to allow for attractive forces at intermediate distances. This new model is suitable for the study of thermal properties of three-dimensional polymer solutions and melts and can be efficientl…
Using Raman and infrared transmission spectroscopy, the vibrational properties of siloxene (${\mathrm{Si}}_{6}$${\mathrm{O}}_{3}$${\mathrm{H}}_{6}$) and its derivatives are investigated and interpreted in terms of various structural modifications of siloxene which have been proposed in the past. On the basis of experi…
We have solved the structure of a chorismate mutase (chorismate pyruvatemutase, EC 5.4.99.5), the 1.9-A crystal structure of the monofunctional enzyme from Bacillus subtilis. The structure determination process was an unusual one, involving 12 monomers of the enzyme in the asymmetric unit. This structure was solved by…
The crystal structure of the serine protease subtilisin Carlsberg in anhydrous acetonitrile was determined at 2.3 A resolution. It was found to be essentially identical to the three-dimensional structure of the enzyme in water; the differences observed were smaller than those between two independently determined struc…
The total energy of ZnO as a function of unit cell volume has been calculated for the zinc-blende, wurtzite, and rocksalt structures by the ab initio all-electron periodic Hartree-Fock linear-combination-of-atomic-orbitals method using a large Gaussian basis set that was variationally optimized for the solid state. Ex…
Mechanisms of thermoluminescence (TL) in aragonite have been studied using electron spin resonance (ESR) techniques. Natural aragonite shows a prominent TL glow peak at 613 K. Additional gamma irradiation enhanced this glow peak but displaces it slightly to 593 K, and induces two glow peaks at 393 and 493 K. Pre-annea…
When co-doped with La 3+ , Ba 3 (PO 4 ) 2 :Eu 2+ shows an intense thermally stimulated luminescence after X-ray irradiation. The phosphor is also optically stimulable. The stimulated emission is due to the Eu 2+ ion. In the absence of Eu 2+ a broad emission band is observed which is tentatively ascribed to a phosphate…
The authors used dynamic mechanical and dielectric thermal analyses together with infrared spectroscopy to identify molecular motions in polyaniline films cast from emeraldine base powder dissolved in the solvent N-methyl-2-pyrrolidinone (NMP). These relaxations include a librational ring motion at around -80 degrees…
The predicted rates of rise of water in glass capillaries of diameters 0.2 and 0.4 mm by a theory which includes the effect of inertia on the movement of the liquid are in satisfactory agreement with experimental data. With an immersion depth (dip length) in the liquid of about 3 mm at the commencement of wicking, the…
The synthesis of luminescent nanometer-scale Si clusters by spark ablation from a crystalline Si substrate is described. The cluster source, described in the text, generates clusters in a flowing Ar stream at atmospheric pressure. Electron microscopy reveals that the clusters have diameters in the 2–4 nm size range. T…
We investigate the stability, bonding, and geometric structure of recently discovered metallocarbohedrenes by the use of density-functional calculations. It is found that the previously proposed ${\mathit{T}}_{\mathit{h}}$ dodecahedron structure is dynamically unstable. Instead, a new, stable, and more strongly bound…
A new technique for the preparation of light emitting nanocrystalline (nc) silicon by a combination of plasma chemical vapor deposition and post-treatment consisting of oxidation and annealing in forming gas is reported. The advantage of this processing consists in the possibility of a control of the crystallite size…
Abstract By condensation of croconic acid ( 7 ) with 2‐(dialkylamino)‐thiophenes 6a – d and with 3‐(dialkylamino)phenols 9a – c the deeply colored, sparingly soluble croconic acid dyes (“croconines”) 8a – d and 10a – c , respectively, have been prepared. These croconines have been characterized by UV/Vis, IR, and 1 H‐…
Films of diblock copolymers with thicknesses less than a lamellar period on a noninteracting surface were found to be model systems for studying the late stages of two dimensional phase separation. It was found under conditions of constant surface coverage that the average particle size 〈R(t)〉, the inverse of the tota…
A combination of electron paramagnetic resonance and band structure calculations is used to show that the Pb2+ ions in lead zirconate titanate materials can act as shallow hole traps to give Pb3+ centers. The Pb3+ centers are created by optical illumination and are found to be metastable at room temperature. Their dec…
High coercivity, c-axis randomly in-plane oriented barium hexaferrite thin films have been successfully fabricated by using conventional rf diode sputtering and post-deposition annealing. Coercivities as high as 4100 Oe have been achieved. Ms, Sq, S*, SFD, and SFDr reach the values of about 270 emu/cc, 0.63, 0.90, 0.1…
The partial radial distribution functions g alpha beta (r) and partial structure factors S alpha beta (k) obtained in computer simulations of the ionic melts of stoichiometry MCl 2 with a recently introduced polarizable ion model are described. The calculated quantities exhibit distinctive structural features which ha…
Minimizing a Euclidean distance in the complex plane optimizes a wide class of correlation metrics for filters implemented on realistic devices. The algorithm searches over no more than two real scalars (gain and phase). It unifies a variety of previous solutions for special cases (e.g., a maximum signal-to-noise rati…