Materials Literature
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A pure carbon quantum dot can be designed by introducing pentagon-heptagon defects in a carbon nanotube. This system has completely confined electronic states induced by the presence of topological defects. By varying the distance between the pentagon-heptagon pairs, the energy difference, spatial confinement, and num…
Using mean-field theory with P 2 θ 2 coupling term in the free energy expansion, we calculate the polarization as a function of concentration for the AC * phase transition in a binary mixture of C7 and 10.O.4 liquid crystalline material. Our calculated values of polarization are in good agreement with the experimental…
Pulsed laser excitation induced conductance changes in colossal magnetoresistance material ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ were studied on the picosecond time scale. A two-component signal was seen consisting of a fast positive transient associated with the paramagnetic insulating state and…
Structural properties of the (NaCl-type) and (CsCl-type) phases of alkaline-earth oxides and their phase transition have been investigated with the periodic ab initio linear combination of atomic orbitals method implemented in the CRYSTAL program. The geometries have been optimized and the bulk modulus evaluated. The…
In colloidal suspensions containing a binary mixture of hard spheres depletion forces occur which substantially contribute to the interaction of the larger spheres among themselves and a wall, respectively. We investigated the depletion force acting on a large colloidal polystyrene sphere immersed in a solution of sma…
We present a simple ionic model which successfully reproduces the various types of compositional long-range order observed in a large class of complex insulating perovskite alloys. The model assumes that the driving mechanism responsible for the ordering is simply the electrostatic interaction between the different io…
We discuss magnetotransport in a low density electron gas coupled to spin fluctuations near and above a ferromagnetic transition. Provided the density is low enough [ $n\ensuremath{\lesssim}1/{\ensuremath{\xi}}^{3}(T)$, with $\ensuremath{\xi}(T)$ the ferromagnetic correlation length], spin polarons form in an intermed…
Direct evidence for freezing in two relaxor ferroelectrics, PbMg1/3Nb2/3O3 and PbSc1/2Ta1/2O3, at a certain temperature Tf≠0 K was obtained from the temperature dependence of the maximum relaxation time, τmax. It was shown that τmax(T) follows the Vögel–Fulcher (VF) law, and tends toward infinity as temperature approa…
To synthesize effective compatibilizers for the compatibilization of acrylic polymer–silk fibroin blend fibers, the homogeneous graft copolymerization of acrylonitrile onto silk fibroin, initiated by potassium persulfate–sodium bisulfite redox system in 60 wt % ZnCl2 aqueous solution was investigated. The percentage g…
Results of differential scanning calometry (DSC), x-ray diffraction (XRD), and F19 nuclear magnetic resonance (NMR) of InF3-based glasses, treated at different temperatures, ranging from glass transition temperature (Tg) to crystallization temperature (Tc), are reported. The main features of the experimental results a…
We present the results of a spectroscopic study carried out on a solid sample of 5,5″-bis(dicyanomethylene)-5,5″-dihydro-Δ2,2′:5′,2″-terthiophene. This compound bears a heteroquinonoid structure in its ground state and could be considered as a model of the structural changes induced by the different types of charge ca…
A novel adsorbent matrix is synthesized by coupling β-cyclodextrin to chitosan using 1,6-hexamethylene diisocyanate. The matrix is found insoluble in organic as well as acidic or alkaline media. The results of our preliminary study on its interaction with cholesterol indicates that the modified chitosan could be used…
Resole phenolic resins containing various p-cresol (PC) to phenol (P) mol ratios were prepared and characterized. These phenolic resins were blended with nitrile rubber (NBR) and the measurements of adhesive joint strength, stress–strain properties, DSC, TGA, DMA, TEM, and SEM were performed using a 50 : 50 NBR/phenol…
A simple yet reasonably accurate perturbation theory for the Gay–Berne model, capable of describing the uniform isotropic and nematic phases, as well as the layered smectic-A phase, is presented. The theory, in line with a previously proposed theory, is based on a perturbative scheme, but the reference system, a hard…
Utilizing high-resolution transmission electron microscopy, in tandem with molecular dynamics simulations, we conduct a fundamental study of the mechanical force–structure relationship of carbon nanotubes. We study the response of tubes to asymmetrical radial compressive forces, which are directly related to observed…
The mechanical properties (flexural modulus, static tensile strength, notched Izod impact strength), miscibility, thermal stability, and flame retardance of a poly(ethylene oxide) (PEO)-toughened phenolic resin glass pultruded composite were investigated. The mechanical properties of a pultruded glass fiber-reinforced…
Manganese/cerium composite oxide (MnO 2 /CeO 2 ) proved to be a potent solid catalyst for the catalytic wet oxidation (CWO) of aqueous phenol under mild treatment conditions (80−130 °C, 0.5 MPa O 2 pressure). Despite the fact this catalyst exhibited an important activity in eliminating completely phenol and total orga…
The metastable T−P phase diagram and the anomalies of the thermodynamic properties of supercooled water are calculated on the basis of a two-level thermodynamic model. Water is considered as a mixture of two components which differ in atomic configurations and correspond to low-density amorphous (lda) and high-density…
A comprehensive model has been developed to handle the reactions in polymers undergoing polycondensation reactions in the solid state. The polymer crystalline fraction is modeled as containing only repeat units, thus concentrating end groups and condensate in the amorphous fraction. In addition, by using a general fra…
The size dependence of the electronic spectrum of InAs nanocrystals ranging in radius from 10–35 Å has been studied by size-selective spectroscopy. An eight-band effective mass theory of the quantum size levels has been developed which describes the observed absorption level structure and transition intensities very w…