Materials Literature
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Abstract A series of new shape memory polymers are synthesized by the cationic copolymerization of regular soybean oil, low saturation soybean oil (LoSatSoy oil), and/or conjugated LoSatSoy oil with styrene and divinylbenzene, norbornadiene, or dicyclopentadiene initiated by boron trifluoride diethyl etherate or relat…
The ability of surface passivation to enhance the photoluminescence (PL) emission of Si nanocrystals in SiO2 has been investigated. No significant increase of the average nanocrystal size has been detected for annealings at 1100 °C between 1 min and 16 h. In contrast, the PL intensity steadily increases and reaches sa…
<div class="htmlview paragraph">As demand for wall-flow Diesel particulate filters (DPF) increases, accurate predictions of DPF behavior, and in particular of the accumulated soot mass, under a wide range of operating conditions become important. This effort is currently hampered by a lack of a systematic knowle…
Ab initio cluster and supercell methods are used to investigate the local geometry and optical properties of hydrogen defects in diamond. For an isolated impurity, the bond-centered site is found to be lowest in energy, and to possess both donor and acceptor levels. The neutral defect possesses a single local mode wit…
Magnetization reversal in magnetic nanostructures is investigated numerically over time-scales ranging from fast switching processes on a picosecond scale to thermally activated reversal on a microsecond time-scale. A simulation of the stochastic Landau-Lifshitz equation of motion is used as well as a time quantified…
We have investigated the swelling of acetone in fluorocarbon polymer films doped with different gold concentrations below the percolation threshold. The presence of the gold clusters in the polymer improves the mixing between the polymer and the acetone, which is not a good solvent for this kind of polymer. To explain…
<div class="htmlview paragraph">As legislation tightens in the Heavy Duty Diesel (HDD) area it is essential to develop systems with high activity and excellent durability for both Particulate Matter (PM) and NOx control. The Continuously Regenerating Trap (CRT™) system controls hydrocarbon (HC), CO and PM emissi…
We introduce a general Monte Carlo scheme for achieving atomistic simulations with monoelectronic Hamiltonians including the thermalization of both nuclear and electronic degrees of freedom. The kinetic Monte Carlo algorithm is used to obtain the exact occupation numbers of the electronic levels at canonical equilibri…
We have grown (InyGa1−y)1−xMnxAs ferromagnetic semiconductor layers with Mn composition of x up to 0.13 on InP substrates by molecular beam epitaxy. Near the lattice-matched composition, i.e., y∼0.53, the Curie temperature increases linearly with the ferromagnetically effective Mn composition xeff, following the empir…
A fourteen-fold anisotropy in the spin transport efficiency parallel and perpendicular to the charge transport is observed in a vertically biased (Ga, Mn)As-based spin-polarized light emitting diode. The spin polarization is determined by measuring the polarization of electroluminescence from an (In, Ga)As quantum wel…
Single-crystal CaAl2O4 fibers doped with Ce3+ or Tb3+ or double doped with Tb3+ and Ce3+ were prepared by the laser-heated pedestal-growth method. Ce3+-doped CaAl2O4 was found to have persistent phosphorescence in the blue violet lasting more than 10 h, while Tb3+-doped CaAl2O4 showed only a weak afterglow. However, l…
Although autogenous saphenous vein remains the standard for coronary and infrapopliteal bypass, many patients do not have a suitable vein. Attempts at developing a small-caliber vascular graft have failed largely due to occlusion, neointimal hyperplasia, or aneurismal degradation. We have designed and characterized a…
Aligned MWNT–PPy composite films show exceptional charge storage capacities and improved response times. The superior performance of these composites, compared to pure PPy films, is demonstrated and discussed. The Figure shows an SEM image of the fractured film cross section, illustrating the thickness of the PPy coat…
We report here synthesis of phase-pure magnetoelectric BiFeO3 thin films with controlled oxygen stoichiometry on Pt/TiO2/SiO2/Si substrate using pulsed-laser deposition technique. Saturated ferroelectric hysteresis loop has been observed in phase-pure and highly resistive BiFeO3 thin films. The dielectric response stu…
We report on the realization of wide band gap (5–6 eV), single-phase, metastable, and epitaxial MgxZn1−xO thin-film alloys grown on sapphire by pulsed laser deposition. We found that the composition, structure, and band gaps of the MgxZn1−xO thin-film alloys depend critically on the growth temperature. The structural…
We considered the trans → cis photoisomerization dynamics of the S 2 -excited azobenzene derivatives in terms of the potential energy gap between the n-π* (S 1 ) and the π-π* (S 2 ) state. The photoisomerization dynamics of trans -4-aminoazobenzene ( trans -4-AAB) which has an energy gap (3000−4000 cm -1 ) rather smal…
The specific surface area of amorphous Aerosil 200 and silica particles with 270 nm diameter prepared by the Stoeber method was investigated by a variety of experimental methods: nitrogen adsorption at 77 and 253 K; adsorption from ethanol/cyclohexane mixture; heats of wetting measurements; small-angle X-ray scatterin…
Supported transition metal oxides and vanadium-containing multi-metallic oxides were investigated to develop new catalysts for the catalytic destruction of highly toxic polychlorinated aromatic pollutants such as polychlorinated benzenes, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and/or bipheny…
Silver nanoparticles with an average size of ∼5 nm were deposited on the surface of preformed silica submicrospheres with the aid of power ultrasound. Ultrasound irradiation of a slurry of silica submicrospheres, silver nitrate, and ammonia in an aqueous medium for 90 min under an atmosphere of argon to hydrogen (95:5…
Relationship among Wigner crystal, charge order and Mott insulator is studied by the path-integral renormalization group method for two-dimensional lattices with long-range Coulomb interaction. In contrast to Hartree-Fock results, the solid stability drastically increases with lattice commensurability. The transition…