Materials Literature
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The heterostructures of Zn–ZnO coaxial nanocables and ZnO nanotubes with an average diameter of 30 nm have been synthesized by simple pyrolysis of zinc acetylacetonate. High-resolution transmission electron microscopy analyses reveal that the Zn core and the ZnO sheath of the nanocables have an epitaxial relationship…
We use confocal microscopy to study particle motion in colloidal systems. Near the glass transition, motion is inhibited, as particles spend time trapped in transient "cages" formed by neighboring particles. We measure the cage sizes and lifetimes, which, respectively, shrink and grow as the glass transition approache…
The magnetocaloric effect (MCE) originated from the itinerant-electron metamagnetic transition for La(FexSi1−x)13 compounds has been investigated. With increasing Fe concentration, the MCE is enhanced and both the isothermal magnetic entropy change ΔSm and the adiabatic temperature change ΔTad for the compound with x=…
We present calculations of quantized conductance and magnetoresistance in nanosize point contacts between two ferromagnetic metals. When conductance is open for only one conduction electrons spin-projection, the magnitude of magnetoresistance is limited by the rate of conduction electron spin-reversal processes. For t…
The stress profile and reorientation of grains, in response to a point force applied to a preloaded two dimensional granular system, are calculated in the context of a continuum theory that incorporates the texture of the packing. When high friction prevents slip at the inter-grain contacts, an anisotropic packing pro…
Molecular dynamics simulations of the diffusion of limonene into molten polyethylene were performed in order to explore the possibility of using atomistic simulations to predict the diffusion of “larger” solute molecules in polymers. The system contained 6000 anisotropic united atom methylene units with a molar mass o…
A single crystal of KVTeO(5), potassium vanadium tellurite, has been grown. The present structure determination has been conducted together with the refinement of the NaVTeO(5) homologue, sodium vanadium tellurite, for the sake of precise comparison. The network consists of [VTeO(5)](n) ribbons built up by VO(4) tetra…
Using the dynamic density functional (DDF) simulation technique, we studied the domain morphology and dynamics of phase separation in a mixture of long and short block copolymers. The simulation results well reproduce the recent results of the X-ray scattering experiment and the TEM observation on a mixture of long an…
This work reexamines and updates earlier investigations on the phase behaviour of the Gay-Berne liquid crystal model, concentrating on the effect of varying temperature. Constant volume and constant pressure Monte Carlo simulations are combined for systems consisting of N = 500 molecules along different isotherms over…
Copper ions on over-exchanged Cu−MCM-22 were monitored by CO and NO adsorption at 300 K and NO adsorption at 77 K. Two different species of both Cu(I) and Cu(II) ions were produced by vacuum thermal treatment at 823 K. Cu I −CO complexes were formed upon CO adsorption and converted to Cu I −(CO) 2 complexes upon incre…
We propose a new theoretical method to study hydrogen-bonded supramolecular liquid crystals. It is based on our recent theory of associating polymer solutions combined with McMillan's molecular theory of liquid crystallization. We derive phase diagrams of supramolecular liquid crystals consisting of two different spec…
The processes governing adsorption of poly( o -methoxyaniline) (POMA) are analyzed by investigating the kinetics of adsorption and adsorption isotherms of a POMA layer on already adsorbed layer-by-layer films of POMA/poly(ethenesulfonic acid) (PVS). The kinetics of adsorption comprises two steps, namely, a first-order…
Samples of poly(2,2‘-dioxybiphenylphosphazene) were prepared according to procedures previously reported in the literature and submitted to thermal degradation at temperatures between 100 and 200 °C during periods of time ranging from 6 to 250 h. Experimental characterization of the parent polymer and the degraded sam…
Variable-temperature FTIR measurements were performed on amorphous films of isotactic and syndiotactic PMMA, followed by a detailed analysis of the temperature dependence of integrated band intensities for C−O stretching modes in the region 1050−1300 cm -1 . The use of computerized FTIR instrumentation and modern meth…
In the present study we examined the oxygen-transport properties of poly(ethylene naphthalate) (PEN) isothermally crystallized from the melt (melt crystallization) or quenched to the glass and subsequently isothermally crystallized by heating above the glass transition temperature (cold crystallization). The gauche /…
The packing of binary and polydisperse unimodal and bimodal ensembles of hard spheres in the limit of high pressure is studied using a sequential addition algorithm. Upon fixing the number of particles, and their size distribution, the average (maximum) packing fraction is determined for systems of up to 20 000 partic…
Active sites for photometathesis on mesoporous silica materials, FSM-16 and MCM-41, and amorphous silica, which are generated by dehydroxylation of surface isolated hydroxyl groups at high temperature above 673 K, were investigated by some spectroscopies such as FTIR, ESR, VUV−UV, and photoluminescence. FTIR study rev…
Random copolymers of methyl methacrylate with polyhedral oligomeric silsesquioxane (POSS) were synthesized and blended with PS and PMMA homopolymer thin films. The effects of the POSS on phase segregation were studied using a variety of complementary techniques. The results showed that these copolymers were efficient…
A systematic approach is developed for the in situ control of the crystal size distribution, and is applied to the aqueous crystallization of paracetamol (acetaminophen) as a model pharmaceutical system. This involves the determination of the solubility curve and the metastable limit, and the operation of concentratio…
The classical Cahn-Hoffman capillarity vector formalism for anisotropic interfaces, widely used to analyze capillary and surface patterning processes in metallurgical systems, is applied to nematic liquid crystalline interfaces. The nematic capillarity vector is derived and expressed in terms of nematic surface energi…