Materials Literature
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Hall crosses were used to measure the magnetic properties of arrays of ferromagnetic, nanometer-scale iron particles. The arrays typically consist of several hundred particles of 9 -- 20 nm in diameter. It is shown that the sensitivity of the measurements can be improved by matching the areas of the Hall cross and the…
A glass surface may still flow below the bulk glass transition temperature, where the underlying bulk is frozen. Assuming the existence at T=T* of a bulk thermodynamical glass transition, we show that the glass-vapor interface is generally wetted by a liquid layer of thickness ~ -ln(T*-T) when T--> T*. Contrary to sta…
In-plane magnetic field is found to change drastically the photoluminescence spectra and kinetics of interwell excitons in GaAs/AlGaAs coupled quantum wells. The effect is due to the in-plane magnetic field induced displacement of the interwell exciton dispersion in a momentum space, which results in the transition fr…
We propose a new model to implement organic exciton-semiconductor exciton hybridization by embedding a semiconductor quantum dot array into an organic medium. A Wannier-Mott transfer exciton is formed when the exciton in each semiconductor dot interacts via the multipole-multipole coupling with other excitons in the d…
This study concerns a molecular dynamics (MD) simulation, using the embedded-atom method (EAM), of the self-diffusion of an interstitial in the bcc metal tungsten (W) at 2000 K. It is found that the interstitial moves only along 111 diagonals and that the switches to other non-parallel directions take place through a…
We introduce a schematic nonlinear diffusion model where density fluctuations induce a rich out-of-equilibrium dynamics. The properties of the model are studied by numerical simulations and analytically in a mean field approximation. At low temperatures and high densities we find a long off-equilibrium glassy region,…
The effect of concentration of antioxidants on the Mooney scorch time of two grades of epoxidized natural rubbers (ENR 25 and ENR 50) and one grade of natural rubber (SMR L) was studied using a Monsanto automatic Mooney viscometer (MV 2000). Three types of antioxidants, viz., 2,2′-methylene-bis(4-methyl, 6-tertbutylph…
Thermal conductivity of a single-crystal lead magnesium niobate titanate-(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 with x=0.34 has been studied at temperatures from 20 to 320 K and in an applied electric field. The thermal conductivity of the crystal is similar to that of a typical amorphous solid both in the temperature dependen…
The effect of chain extender structure on properties and morphology of α,ω-bis(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS) and poly(hexamethylene oxide) (PHMO) mixed macrodiol-based aliphatic polyurethane elastomers was investigated using tensile testing, differential scanning calorimetry (DSC), and dynamic mec…
Nonextractable styrene-acrylonitrile copolymer-montmollironite (SAN- MMT) nanocomposites were prepared by two different intercalation process: (1) a usual one-step emulsion copolymerization in the presence of the Na 1 -MMT; and (2) a solution copolymerization with MMT modified by dimethyl dihydrogenated tallow ammoniu…
We report calculations of the transport properties of multiwalled carbon nanotubes based on a scattering-theoretic approach that takes into account scattering within each tube, between tubes, and at the metal contacts. We find that only the outer tube contributes to the conductance, as has been implied by experiments.…
Pharmaceutical products consist of a great range of meticulously produced formulations intended for human and veterinary use. From consumer-oriented, over-the-counter products to life-supportive pr...
Dynamically vulcanized poly(vinyl chloride)–epoxidized natural-rubber thermoplastic elastomers (PVC–ENR TPEs) were prepared using a semi-EV vulcanization system. The compounds were melt-mixed, and the rheological behavior was evaluated. The effect of curatives concentration on the rheological behavior using the shear…
To fabricate a platelet-compatible polymer, phosphorylcholine (PCe) was introduced onto the surface of polyethylene (PE) using a novel synthetic process. Acrylic acid was graft-copolymerized on the surface of PE by UV irradiation, using both the peroxide preirradiation and the simultaneous methods. Benzophenone and Mi…
Halogenation and addition of some heavy metallic oxides have been in use for a few decades to impart flame-retarding properties to polymers. In this study bromine was added to the polymer (polyester of propylene glycol + phthalic anhydride) by means of decabromodiphenyloxide (DBDPO) at varying concentrations. In addit…
The biodegradability of low density polyethylene (LDPE)/starch and LDPE/starch/starch acetate (STAc) blends was tested and observed to be dependent on STAc content. The binary and ternary blends containing up to a maximum concentration of 30% starch were examined for their thermal, mechanical, and morphological proper…
An amorphous selenium network structure was constructed by combination of a lattice random walk and ab initio molecular dynamic (MD) simulation. The static structure factor, pair correlation function, and vibrational and electronic density of states simultaneously agree with experiment. For the first time, we study st…
The electron dynamics is studied in silver nanoparticles of different sizes embedded either in a silicate glass or in a porous alumina matrix, using time-resolved optical spectroscopy. The femtosecond pump–probe measurements, made under various conditions of excitation, reveal that the energy relaxation is faster as t…
Scaling of the ferroelectric and piezoelectric properties in Pt/SrBi2Ta2O9/Pt thin films was studied. Focused ion beam milling was used to fabricate submicron devices (1×1, 0.5×0.5, 0.25×0.25, 0.09×0.09, and 0.07×0.07 μm2) and scanning force microscopy was used to examine their piezoelectric response. It was found tha…
Neutral $\mathrm{Ti}{}_{8}\mathrm{C}{}_{12}$ and $\mathrm{Ti}{}_{14}\mathrm{C}{}_{13}$ clusters are produced in the gas phase with pulsed-nozzle laser vaporization. Infrared multiphoton excitation with a pulsed free-electron laser results in thermionic electron emission for these clusters, and the parent molecular ion…