Magnetic Studies of Polycrystalline and Single-Crystal NaxCoO2
We have investigated the preparation and bulk magnetic properties of NaxCoO2 in the range 0.5
Materials Literature
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Reversibility Window, Aging, and Nanoscale Phase Separation in GexAsxS1-2x Bulk Alloy Glasses
The non-reversing enthalpy near Tg, DHnr, in bulk GexAsxS1-2x glasses is found to display a global minimum (~0) in the 0.11 < x < 0.15 range, the reversibility window. Furthermore, the DHnr term is found to age for glass compositions both below (x < 0.11) and above (x > 0.15) the window but not in the window. Glass co…
Magnetodielectric Effects from Spin Fluctuations in Isostructural Ferromagnetic and Antiferromagnetic Systems
We report on the effects of spin fluctuations, magnetic ordering, and external magnetic field on the dielectric constant of the ferromagnet ${\mathrm{S}\mathrm{e}\mathrm{C}\mathrm{u}\mathrm{O}}_{3}$, and the antiferromagnet ${\mathrm{T}\mathrm{e}\mathrm{C}\mathrm{u}\mathrm{O}}_{3}$. A model based on the coupling betwe…
Ferroelectricity in Barium Titanate Quantum Dots and Wires
Properties of BaTiO3 colloidal quantum dots and wires are simulated using a first-principles-based approach. Large atomic off-center displacements (that are robust against capping matrix materials) are found to exist in very small (<5 nm) dots. We further determine the size dependences of electrical and electromechani…
Modulation of Thermoelectric Power of Individual Carbon Nanotubes
Thermoelectric power (TEP) of individual single walled carbon nanotubes (SWNTs) has been measured at mesoscopic scales using a microfabricated heater and thermometers. Gate electric field dependent TEP modulation has been observed. The measured TEP of SWNTs is well correlated to the electrical conductance across the S…
Polyolefins: The most promising large‐volume materials for the 21st century
Abstract Polyolefins (POs) constitute an extremely interesting family of materials. They include large‐volume materials such as polyethylene and polypropylene and specialty materials. Outstanding scientific and technology developments have led to the most aggressive, endless, always increasing, successful growth speed…
Vapor-liquid coexistence in many-body dissipative particle dynamics
Many-body dissipative particle dynamics is constructed to exhibit vapor-liquid coexistence, with a sharp interface, and a vapor phase of vanishingly small density. The application to fluid mechanics problems involving free surfaces is illustrated by simulation of a pendant drop. The model is an unusual example of a so…
Layer by Layer Buildup of Polysaccharide Films: Physical Chemistry and Cellular Adhesion Aspects
The formation ofpolysaccharide films based on the alternate deposition of chitosan (CHI) and hyaluronan (HA) was investigated by several techniques. The multilayer buildup takes place in two stages: during the first stage, the surface is covered by isolated islets that grow and coalesce as the construction goes on. Af…
The ASTRAL Compendium in 2004
The ASTRAL Compendium provides several databases and tools to aid in the analysis of protein structures, particularly through the use of their sequences. Partially derived from the SCOP database of protein structure domains, it includes sequences for each domain and other resources useful for studying these sequences…
SCOP database in 2004: refinements integrate structure and sequence family data
The Structural Classification of Proteins (SCOP) database is a comprehensive ordering of all proteins of known structure, according to their evolutionary and structural relationships. Protein domains in SCOP are hierarchically classified into families, superfamilies, folds and classes. The continual accumulation of se…
Controlling Surface Morphology of Electrospun Polystyrene Fibers: Effect of Humidity and Molecular Weight in the Electrospinning Process
Electrospinning is a technique used to produce micron to submicron diameter polymeric fibers. The surface of electrospun fibers is important when considering end-use applications. For example, the ability to introduce porous surface features of a known size is required if nanoparticles need to be deposited on the surf…
Generation of the second and third harmonics of femtosecond Cr: forsteritelaser pulses in SiC/PMMA nanopowder films
Second- and third-harmonic generation in silicon carbide ( SiC ) nanopowders embedded in a polymethyl methacrylate ( PMMA ) film are studied using nano-, pico-, and femtosecond laser pulses. Second- and third-harmonic generation processes are shown to allow the detection of absorptive agglomerates of nanocrystals in t…
Nonlinear behavior of piezoelectric lead zinc niobate–lead titanate single crystals under ac electric fields and dc bias
The nonlinear behaviors of the dielectric and piezoelectric responses of 〈001〉 oriented Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) single crystals for x=4.5% and 8% have been investigated as a function of ac electric fields and dc bias fields. At relatively low applied fields, the polarization and strain of PZN-PT single cryst…
Síntesis y caracterización Mössbauer de magnetitas dopadas con Cu y Cr
Se presenta una investigación Mössbauer detallada de magnetitas preparadas bajo diferentes condiciones hidrotermales y dopadas con Cu y Cr. Las muestras fueron caracterizadas utilizando la espectrometría Mössbauer a temperatura ambiente, espectroscopia infrarroja y difracción de rayos X. Los resultados Mössbauer muest…
Anti-localisation to strong localisation: The interplay of magnetic scattering and structural disorder
We study the effect of magnetic scattering on transport in a system with strong structural disorder, using exact finite-size calculation of the low-frequency optical conductivity. At weak electron-spin coupling, spin disorder leads to a decrease in resistivity, by weakening the quantum interference precursors to Ander…
In-Situ Soft X-ray Studies of Toluene Catalytic Oxidation on the Pt(111) Surface
The catalytic oxidation of toluene on the Pt(111) surface has been characterized, in flowing oxygen pressures up to 0.01 Torr, using temperature-programmed fluorescence yield near-edge spectroscopy (TP-FYNES). During TP-FYNES oxidation experiments in flowing oxygen pressures, a dehydrogenated C 7 H 7 η 7 -phenylmethyl…
Computer simulation of liquid-crystal surface modification
Metropolis Monte Carlo simulations are used to study the interplay between two different anchoring effects of spherocylinders on a modified surface consisting of hard walls onto which liquid-crystal molecules have been perpendicularly grafted. By varying both the length and grafting density of the surface molecules, a…
Crystallization-Induced Microdomain Coalescence in Sphere-Forming Crystalline−Amorphous Diblock Copolymer Systems: Neat Diblock versus the Corresponding Blends
Crystallization in the microdomains of crystalline−amorphous diblock copolymers may induce domain coalescence when the crystallization temperature lies above the T g of the amorphous matrix. In this study, the perturbation of microdomain structure driven by isothermal crystallization and postannealing in a poly(ethyle…
Near band edge recombination mechanisms in GaTe
GaTe samples of p-type have been investigated by analyzing the photoluminescence (PL) response for different excitation intensities at energies higher than the band gap. The PL intensity variation of recombination peaks as a function of the excitation intensity has been measured and fitted by a power law. The results…
The role of the cooperative Jahn–Teller effect in the charge-ordered La1−xCaxMnO3 (0.5⩽x⩽0.87) manganites
Based on the magnetoresistance, magnetization, ultrasound, and crystallographic data, we studied the role of the cooperative Jahn–Teller (JT) effect in the charge-ordered (CO) state for La1−xCaxMnO3. We found that, with increasing the fraction of Q3 mode of JT distortion and decreasing that of Q2 mode in the CO state,…