Mirrorless optical bistability in a nonlinear absorbing dielectric film

The optical transmissivity of a mirrorless, nonlinear, absorbing dielectric thin film is investigated numerically. The dielectric function in the film region is dependent on the intensity of the electromagnetic field. Multivalued solutions of transmissivity as a function of incident power are calculated for the steady-state wave equation. The numerical solution is applied to two different model dielectric functions. As the absorption parameter is increased, larger values of incident intensity are required to switch the systems between stable output states. Also, the peak values of transmissivity are reduced as the absorption is increased

Thermoelectric properties of Bi2Sr2Co2O9 whiskers under hydrostatic pressure

We report the temperature dependence of thermopower (S) in the ab plane of Bi2Sr2Co2O9 {BC-222} single crystalline whiskers under high pressure up to 1.2 GPa. Special modifications were made to our high-pressure transport measurement system to improve the measurement accuracy of S for whiskers with high resistance. Pressure improved the contact resistance dramatically. We observed a slight decrease of S and four-wire electrical conductivity (sigma) under high pressure. As a result, the power factor (S2sigma) was decreased less than 20% by pressure. From the temperature dependence of sigma, the band gap of BC-222 whiskers increase very slightly under high pressure

Thermoelectric properties of Bi2Sr2Co2O9 whiskers under hydrostatic pressure

We report the temperature dependence of thermopower (S) in the ab plane of Bi2Sr2Co2O9 {BC-222} single crystalline whiskers under high pressure up to 1.2 GPa. Special modifications were made to our high-pressure transport measurement system to improve the measurement accuracy of S for whiskers with high resistance. Pressure improved the contact resistance dramatically. We observed a slight decrease of S and four-wire electrical conductivity (sigma) under high pressure. As a result, the power factor (S2sigma) was decreased less than 20% by pressure. From the temperature dependence of sigma, the band gap of BC-222 whiskers increase very slightly under high pressure

Magneto-optical spectra of closely spaced magnetite nanoparticles

The Faraday rotation spectrum of composites containing magnetite nanoparticles is found to be dependent on the interparticle spacing of the constituent nanoparticles. The composite materials are prepared by combining chemically synthesized Fe 3O4 smagnetited nanoparticles s8-nm diameterd and polysmethylmethacrylated . Composites are made containing a range of nanoparticle concentrations. The peak of the main spectral feature depends on nanoparticle concentration; this peak is observed to shift from approximately 470 nm for sdilute compositesd to 540 nm concentrated . We present a theory based on the discrete-dipole approximation which accounts for optical coupling between magnetite particles. Qualitative correlations between theoretical calculations and experimental data suggest that the shifts in spectral peak position depend on both interparticle distance and geometrical configuratio

Synthesis and magnetic properties of CoPt–poly(methylmethacrylate) nanostructured composite material

We have prepared nanometer-sized CoPt particles dispersed in a poly~methyl methacrylate~PMMA!matrix, as a novel nanostructured magnetic plastic, through a soft chemical processing route. In this work, CoPt nanoparticles were successfully synthesized from a solution phase reduction system in the presence of capping ligands and stabilizing agents at high temperature. The CoPt nanoparticles were annealed at 400 °C for 3 h, and were subsequently re-dispersed inmethylmethacrylate~monomer! . The polymerization was induced by a UV source and the hardness of final product was adjusted by varying the amount of monomeric cross-link agent. Annealed bare CoPt nanoparticles as a ‘‘core’’ material and CoPt–PMMA composite material were characterized by using energy dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction, indicating that we are able to prepare CoPt nanoparticles with 10 nm in diameter ~after annealing by employing this high temperature colloidal processing method. Magnetic investigation of this CoPt–PMMA material indicates an intrinsic coercivity of 300 Oe at 300 K and 1665 Oe at 5 K

Synthesis and magnetic properties of CoPt–poly(methylmethacrylate) nanostructured composite material

We have prepared nanometer-sized CoPt particles dispersed in a poly~methyl methacrylate~PMMA!matrix, as a novel nanostructured magnetic plastic, through a soft chemical processing route. In this work, CoPt nanoparticles were successfully synthesized from a solution phase reduction system in the presence of capping ligands and stabilizing agents at high temperature. The CoPt nanoparticles were annealed at 400 °C for 3 h, and were subsequently re-dispersed inmethylmethacrylate~monomer! . The polymerization was induced by a UV source and the hardness of final product was adjusted by varying the amount of monomeric cross-link agent. Annealed bare CoPt nanoparticles as a ‘‘core’’ material and CoPt–PMMA composite material were characterized by using energy dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction, indicating that we are able to prepare CoPt nanoparticles with 10 nm in diameter ~after annealing by employing this high temperature colloidal processing method. Magnetic investigation of this CoPt–PMMA material indicates an intrinsic coercivity of 300 Oe at 300 K and 1665 Oe at 5 K

Self-assembly of FePt nanoparticles into nanorings

The application of nanoparticles as quantum dots in nanoelectronics demands their arrangement in ordered arrays. Shape controlled self-assembly is a challenge due to the difficulties of obtaining proper self-assembling parameters, such as solvent concentration, organic ligands, and nanoparticle size. In this article, hard magnetic FePt nanoparticles were synthesized using a combination approach of reduction and thermal decomposition. The nanoparticles are about 4.5 nm and appeared as truncated octahedral enclosed by the {100} and {111} crystal facets of fcc structure. The nanoparticles are of hexagonal close packing and orient randomly in the self-assembly nanoarrays. By diluting the solution for large-area self-assembly, monolayer, submonolayer, and multilayer nanorings of FePt nanoparticles were formed. The nanoring formation is determined by hydrodynamics, surface effects, and interaction between the FePt nanoparticles and substrates

Self-assembly PbSe Nanoparticles into Nanorings

ABSTRACT In this presentation, we report the self-assembly of monolayer and multilayer nanorings of PbSe nanoparticles. PbSe nanoparticles were synthesized by using a high temperature precipitation method. The nanoparticles are about 5 nm and appeared as truncated octahedral enclosed by the {100} and {111} crystal facets of fcc structure. The large area monodisperse self-assembly nanoarrays were obtained by dropping the high concentration solution of PbSe nanoparticles on the carbon grid. The nanoparticles are hexagonal close packed and oriented randomly in the nanoarrays. By diluting the solution for large area self-assembly, self-assembly of monolayer and multilayer nanorings can be achieved. The nanoring formation is determined by hydrodynamics, surface effects, and interaction between the nanoparticles and carbon grid

A dual process account of creative thinking

This article explicates the potential role played by type 1 thinking (automatic, fast) and type 2 thinking (effortful, logical) in creative thinking. The relevance of Evans's (2007) models of conflict of dual processes in thinking is discussed with regards to creative thinking. The role played by type 1 thinking and type 2 thinking during the different stages of creativity (problem finding and conceptualization, incubation, illumination, verification and dissemination) is discussed. It is proposed that although both types of thinking are active in creativity, the extent to which they are active and the nature of their contribution to creativity will vary between stages of the creative process. Directions for future research to test this proposal are outlined; differing methodologies and the investigation of different stages of creative thinking are discussed. © Taylor & Francis Group, LLC