Materials Literature
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Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and four-wave mixing (FWM) experiments were performed simultaneously to study the initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats between the A-B excitons were found \textit{only for positive time delay} in both PP an…
We present evidence that the insulator-to-metal transition in ${\mathrm{L}\mathrm{a}}_{1\ensuremath{-}x}{\mathrm{C}\mathrm{a}}_{x}{\mathrm{M}\mathrm{n}\mathrm{O}}_{3}$ near $x\ensuremath{\sim}0.2$ is driven by the suppression of coherent Jahn-Teller distortions, originating from $d$-type orbital ordering. The orbital-…
Conserved growth models that exhibit a nonlinear instability in which the height (depth) of isolated pillars (grooves) grows in time are studied by numerical integration and stochastic simulation. When this instability is controlled by the introduction of an infinite series of higher-order nonlinear terms, these model…
Epitaxial films of LaCuOS1−xSex (x=0–1) solid solution were grown on MgO (001) substrates and their electrical and optical properties were examined. Sharp emission due to room-temperature exciton with binding energy of ∼50 meV is observed for all x values. Hall mobility becomes large with an increase in the Se content…
Silver nanoparticles arranged in two-dimensional arrays experience quadrupolar coupling of plasmon resonances when irradiated with visible light. This coupling leads to the formation of the coherent plasmon mode characterized by an intense narrow resonance in the blue spectral range in the extinction spectrum. The cou…
Gold nanoparticles with an average size of ∼5 nm were deposited on the surface of preformed silica submicrospheres with the aid of power ultrasound. The sonochemical reduction was carried out by ultrasonic irradiation in an argon atmosphere at room temperature. Ultrasonic irradiation of a slurry of silica submicrosphe…
It has been shown recently that while bulk gold is chemically inert, small Au clusters are catalytically active. The reasons for this activity and its dramatic dependence on cluster size are not understood. We use density functional theory to study O2 binding to Au clusters and to a Au(111) surface modified by adsorpt…
Ordered mesoporous silica adsorbents were prepared by grafting amino- and carboxylic-containing functional groups onto MCM-41 for the removal of Acid blue 25 and Methylene blue dyes from wastewater. The amino-containing OMS−NH 2 adsorbent has a large adsorption capacity and a strong affinity for the Acid blue 25. It c…
The derivation, implementation, and validation of a method to calculate spin–orbit coupling (SOC) contributions to the hyperfine coupling (HFC) is reported. Due to this development it is now possible to calculate the complete ligand and metal nuclei HFCs at a consistent level of theory, i.e., spin unrestricted Hartree…
The exceptional mechanical and physical properties observed for carbon nanotubes has stimulated the development of nanotube-based composite materials, but critical challenges exist before we can exploit these extraordinary nanoscale properties in a macroscopic composite. At the nanoscale, the structure of the carbon n…
We fabricated ZnO thin-film transistors by rf magnetron sputtering on Si substrates held near room temperature. The best devices had field-effect mobility of more than 2 cm2/V s and an on/off ratio>106. These ZnO films had resistivity ∼105 ohm cm, with high optical transparency (>80% for wavelength &…
Gas-phase reactions of silane (SiH 4 ) and diborane (B 2 H 6 ) are investigated using ab initio calculations at the MP2/6-311++g** level. Initially SiH 4 and B 2 H 6 are only weakly attracted to each other. Under thermal activation, the two molecules can overcome an energy barrier of 33.87 kcal/mol to associate into a…
The synthesis of calcium pyrophosphate, doped with zinc(II) ions at different [Zn]/[Ca] molar ratios, showed that the zinc ions partially substitute Ca 2+ ions. The undoped particles are observed to form small crystals, which become amorphous spherical particles as the zinc content increases.
Adsorption kinetics of (125)I-radiolabeled alpha-chymotrypsin at pH 8.6 was studied in a laminar regime between two walls of poly(ethyleneterephthalate) tracked films and membranes. Adsorption kinetics in the presence of solution (10 microg/mL), desorption by rinsing with buffer, and the following exchange of proteins…
A water-soluble polythiophene with pendant phosphonic acid groups, poly(3-(3‘-thienyloxy)propanephosphonate) (P3TOPP), has been synthesized. Matrix-assisted laser desorption ionization (MALDI) measurements showed that P3TOPP is an oligomer with an average chain length of 10 monomer units. In aqueous solutions it could…
We synthesized a novel alkylammonium/magnesium phyllosilicate hybrid compound by hydrothermal reaction from a mixture of octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, silica sol, and Mg(OH) 2 . The structure of the hybrid compound was studied by XRD, TEM, electron diffraction, high-resolution solid-stat…
The electroresistance (ER) and magnetoresistance (MR) of ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ (LSMO) thin films with different thicknesses (t) are investigated. We found a metallic-to-insulating (M-I) transition in films with $t=80\mathrm{nm}.$ For the 80-nm film, a giant room-temperature ER rati…
A series of simple (CoS(2), Co(9)S(8), NiS(2), NiS, Ni(3)S(2)) and mixed sulfides (NiCo(2)S(4), Ni(0.33)Co(0.67)S(2), Ni(3)Co(6)S(8), CuCo(2)S(4), Cu(0.33)Co(0.67)S(2)) was prepared using low-temperature procedures. To obtain the mixed sulfides, the mixtures of the solutions of the corresponding salts were precipitate…
Abstract A new synthetic procedure toward substituted dithiophthalides, 5,6‐dialkyloxydithiophthalide and 5,6‐dithioalkyldithiophthalide, is presented. 5,6‐Dithiooctyldithiophthalide was obtained from 4,5‐dichlorophthalic acid in an eight‐step reaction with an overall yield of 26%. 5,6‐Dioctyloxydithiophthalide was ob…
The kinetics and mechanism of morphological transition from nonequilibrium lamella to cylinder microdomain in a polystyrene- block -poly(ethylene- co -but-1-ene)- block -polystyrene (SEBS) triblock copolymer were studied by using time-resolved synchrotron small-angle X-ray scattering (SAXS), transmission electron micr…