Embedded nanoparticles

DoeringW.E., Nie S.M., Spectroscopic tags using dye-embedded nanoparticles and surface-enhanced Raman scattering, Anal. Chem. 2003 75 6171-6176. 

Manufacturers have already begun to take advantage of some of these nanoparticle properties. Sunscreens, which protect users from burns by absorbing or deflecting harmful rays, are often made from chemicals such as titanium dioxide or zinc oxide that are particularly effective. These sunscreens often leave a whitish residue—which used to be common on the nose of a pool or beach lifeguard—but when companies embedded nanoparticles of titanium dioxide or zinc oxide instead of bulkier particles, the creams become transparent yet maintained or even increased their effectiveness. With no embarrassing residue, these sunscreens have become popular. 

Nanoparticle materials are important because they exhibit unique properties due to size effects, quantum tunneling, and quantum confinement. As sizes of embedded particles are reduced to the nanometer scale, the surface-to-bulk ratio increases significantly. Therefore, surface effects can dominate bulk properties and an understanding of nanosurfaces becomes important. In this chapter, we discuss characterization of vacancy clusters that reside on surfaces of embedded nanoparticles as well as studies on the correlation of surface vacancy clusters to the properties of the nanomaterials. 

Considerable interest also has been directed at the use of multicomponent composites where, in theory, the most useful properties from each phase can be realized in the whole. This includes metallodielectric structures where a metallic phase imparts, for example, a high index or more exotic effect (e.g., plasmon resonance) and a low-loss or property-tunable dielectric phase. The dielectric phase can be ceramic or polymeric and also has included ferroelectric polymers, embedded nanoparticles, and organic/inorganic hybrids. ... 

Part VI discusses novel advanced electrocatalytic materials, including polymer-embedded nanoparticle electrodes for PEM fuel cells and synthetic diamond-supported electrocatalyst nanoparticles for toxic organic compound treatment. 

Micro-Raman spectroscopy was used to characterise 4H-SiC layers grown from a variety of precursor systems.381 FTIR data were able to characterise hydrogenated amorphous silicon nitride films with embedded nanoparticles. Oxidation leads to the appearance of an Si O feature at 1070 cm 1,382 Raman spectra were used to determine the degree of micro-crystallinity of pc Si I I layers, using the intensity ratio of bands at 520 cm-1 and 480 cm-1.383 IR and Raman spectra were used to determine the effects of neutron irradiation on a-SiC H films.384 A range of a-SiCx I I and a-SiCxNy H films were studied using IR spectroscopy 385 similar experiments were carried out on a-Si i xGcx Il,F films.386... 

The catalytic properties of mesoporous materials with embedded nanoparticles are mainly determined by the type of the inclusion (particle). All catalytic reactions, which are normally known for the particular metals or alloys, can be carried out with mesoporous soHds containing nanoparticles. The important advantage of mesoporous oxides is their stability at high temperatures. Due to this feature, mesoporous oxides with nanoparticles can be successfully used as catalysts in such reactions where nanoparticles embedded in polymeric systems cannot be employed. Another probable advantage of mesoporous catalysts is an appropriate use of pores as nanoreactors of certain size. This can be applicable to large molecules or to cyclization reaction where pore size and shape will influence the reactive path [90]. However, for mesoporous solids with nanoparticles such applications are not reported so far. 

Can embedding nanoparticles of silver into a polymer give the polymer antimicrobial properties Researchers tested the antimicrobial properties of a new composite material- the polymer poly(4-vinyl-N-hexylpyridinium bromide), known as NPVP, which attracts cations. It is known that silver ions from silver bromide and silver nitrate exhibit antimicrobial activity. Silver bromide was embedded into the NPVP polymer. Scientists tested the antimicrobial properties of the composite material. Their results, illustrated in the graph, show the growth of E. coli bacteria over a period of approximately four hours. Each line represents the E. coli population in response to the introduction of a particular substance. 

For the calculations of the optical properties of polymer films with embedded nanoparticles, two routes can be selected. In the exact route, the extinction cross sections Cact(v) of single particles are calculated. The calculated extinction spectra for single particles—or, better, a summation of various excitation spectra for a particle assembly—can be compared with the experimental spectra of the embedded nanoparticles. In the statistic route, an effective dielectric function e(v) is calculated from the dielectric function of the metal e(T) and of the polymer material po(v) by using a mixing formula, the so-called effective medium theory. The optical extinction spectra calculated from the effective dielectric functions by using the Fresnel formulas can be compared with the experimental spectra. 

W. E. Doering and S.M. Nie, Spectroscopic Tags Using Dye-Embedded Nanoparticles and Surface-Enhanced Raman Scattering, Anal. Chem. 75, 6171 (2003)... 

Avasthi, D. K., Mishra, Y. K., Singh, R, and J. R Stoquert. 2010. Ion tracks in silica for engineering the embedded nanoparticles. Nuclear Instruments and Methods in Physics Research B 268 3027-3034. 

An alternative basket type has been developed and licensed which is constructed out of Metamic-HT, a metal matrix composite made by embedding nanoparticles of aluminum oxide and fine boron carbide powder on the grain boundaries of aluminum resulting in improved structural strength properties at elevated temperatures. This allows the basket to serve as both a structural component and a neutron absorber. 

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