Materials Literature
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We present a simple method for the optical manipulation and spectroscopy of colloidal silver nanoparticles in aqueous solution using optical tweezers combined with dark-field microscopy. Because of their localized plasmon resonances, single trapped metal nanoparticles can be used as efficient near-field optical probes…
Autocatalysis during the thermal dehydrochlorination of poly(vinyl chloride) (PVC) is shown to be a free-radical process that converts the ordinary monomer units of the polymer into chloroallylic structures that have low thermal stabilities. In the first stage of dehydrochlorination, conjugated polyene sequences are c…
Fibers of single wall carbon nanotubes extruded from super-acid suspensions exhibit preferred orientation along their axes. We characterize the alignment by x-ray fiber diagrams and polarized Raman scattering, using a model which allows for a completely unaligned fraction. This fraction ranges from 0.17 to 0.05±0.02 f…
ZnS:Mn was produced in nanocrystalline form by a chemical method using polyvinylpyroledone as a chemical capping agent. Mn was stoichiometrically substituted for Zn in ZnS. The manganese (Mn) concentration was varied over its whole solid solution limit in ZnS, i.e., from 0 to 40%. In the high concentration regime this…
We investigated three different modeling approaches to simulate the crystallization behavior of Ge2Sb2Te5 in optical and, very recently, electrical phase-change memories. The first of these models is based on the Johnson–Mehl–Avrami–Kolmogorov (JMAK) formalism to calculate the fraction of crystallized material during…
We present a conduction model aimed at describing bipolar transport and space charge phenomena in low density polyethylene under dc stress. In the first part we recall the basic requirements for the description of charge transport and charge storage in disordered media with emphasis on the case of polyethylene. A quic…
Clusters of magnets: The first examples of manganese single-molecule magnets (SMMs) consisting exclusively of trivalent metal centers are reported. These are hexanuclear clusters containing the [MnIII6(μ3-O)2(μ2-OR)2]12+ core (see picture, Mn yellow, O red) and have an S=4 ground state. Variation of the oxygen-contain…
The magnetic and structural properties of cobalt-implanted ZnO single crystals are reported. High-quality, (110)-oriented single-crystal Sn-doped ZnO substrates were implanted at ∼350 °C with Co to yield transition metal concentrations of 3–5 at. % in the near-surface (∼2000 Å) region. After implantation, the samples…
Platinum, palladium, and silver nanotubes of 6–7-nm outer diameters are synthesized by the reduction of metal salts confined to lyotropic mixed-surfactant liquid crystals (see picture). The lyotropic liquid crystals act as a template and are formed by the 1:1 combination of medium and large surfactant molecules into a…
In this communication, we first report the direct synthesis of high-quality carbon nitride nanotubes (CNNTs) with inner diameters of 50-100 nm and wall thicknesses of 20-50 nm with the C(3)N(4) stoichiometry on a high-yield of 40%via a simple benzene-thermal process involving the reaction of C(3)N(3)Cl(3) with NaN(3)…
Porous silicon exhibits extremely rich morphological features resulting from a set of very complex reaction processes at the silicon/electrolyte interface. Numerous theories have been proposed since its discovery more than four decades ago, but there is still a lack of complete understanding of the formation mechanism…
Formation mechanism of ${\mathrm{H}}_{2}{\mathrm{T}\mathrm{i}}_{3}{\mathrm{O}}_{7}$ nanotubes by single-step reaction of crystalline ${\mathrm{T}\mathrm{i}\mathrm{O}}_{2}$ and NaOH has been investigated via transmission electron microscopy examinations of series specimens with different reaction times and extensive ab…
An incoherent particle model has been developed to calculate the phonon thermal conductivity of superlattice nanowires. This is an extension of the photon net-radiation method and Schuster–Schwarzschild approximation to dispersive acoustic phonons in a gray medium. By comparing the roughness and geometric variations o…
RATIONALE AND OBJECTIVES: Superparamagnetic iron oxides (SPIO) used as magnetic resonance (MR) contrast agents undergo specific uptake by macrophages. The purpose of this study was first to determine the mechanism of macrophage uptake for Ferumoxides by using competition experiments with specific ligands of scavenger…
Recent progress in fundamental studies on multiporphyrin arrays has provided structural parameters for the molecular design of artificial light-harvesting antennae which mimic the wheel-like antenna complexes of photosynthetic purple bacteria. Covalent and noncovalent approaches have been employed for the construction…
Citrate ion, a commonly used reductant in metal colloid synthesis, undergoes strong surface interaction with silver nanocrystallites. The slow crystal growth observed as a result of the interaction between the silver surface and the citrate ion makes this reduction process unique compared to other chemical and radioly…
Dendrimers are versatile, derivatisable, well-defined, compartmentalised chemical polymers with sizes and physicochemical properties resembling those of biomolecules e.g. proteins. The present critical review (citing 158 references) briefly describes dendrimer design, nomenclature and divergent/convergent dendrimer sy…
Polymer brushes produced by controlled surface-initiated polymerization provide a route to surfaces coated with well-defined thin polymer films that are covalently bound to the substrate. All of the major controlled polymerization techniques have been applied to the synthesis of polymer brushes and examples of each ar…
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Abstract The chemiluminescence under isothermal and nonisothermal conditions accompanying the oxidation of some polymers (polyolefins, polyamides, and polysaccharides) has been examined from the viewpoint of its relationship with the rate of oxidation. The chemical structure of a given type of polymer plays a decisive…