Nanoparticles Embedded (nanoparticle + embedded)

Distribution by Scientific Domains


Selected Abstracts


Nanogold-Loaded Sharp-Edged Carbon Bullets as Plant-Gene Carriers

ADVANCED FUNCTIONAL MATERIALS, Issue 15 2010
Periyasamy S. Vijayakumar
Abstract The higher DNA delivery efficiency into plants by gold nanoparticles embedded in sharp carbonaceous carriers is demonstrated. These nanogold-embedded carbon matrices are prepared by heat treatment of biogenic intracellular gold nanoparticles. The DNA-delivery efficiency is tested on a model plant, Nicotiana tabacum, and is further extended to the monocot, Oryza sativa, and a hard dicot tree species, Leucaena leucocephala. These materials reveal good dispersion of the transport material, producing a greater number of GUS foci per unit area. The added advantages of the composite carrier are the lower plasmid and gold requirements. Plant-cell damage with the carbon-supported particles is very minimal and can be gauged from the increased plant regeneration and transformation efficiency compared with that of the commercial micrometer-sized gold particles. This is ascribed to the sharp edges that the carbon supports possess, which lead to better piercing capabilities with minimum damage. [source]


A quantitative morphological analysis of nanostructured ceria,silica composite catalysts

JOURNAL OF MICROSCOPY, Issue 2 2008
M. MOREAUD
Summary This study aims at examining the morphology of different catalysts, which are based on a dispersion of ceria nanoparticles embedded in a high surface area mesoporous silica framework. In order to fully describe the mesostructured composite material, we propose here a quantitative description of the microstructure based on a quantitative analysis of micrographs that were obtained via high-resolution transmission electron microscopy. We have therefore developed an automatic image analysis process in order to automatically and efficiently extract all the components of the catalyst images. A statistical and a morphological analysis of the spatial arrangement of the components of the catalyst are also presented. The study shows clear differences between the materials analysed in terms of the spatial arrangement and the total surface area of the ceria phase emerging into the pores, parameters of prime importance for the catalytic properties. Thus, the silica,ceria nanostructured composite materials, displaying large surface area up to 300 m2 g,1 are shown to exhibit highly rugged surfaces resulting from ceria nanoparticles emerging in the pores. [source]


Raman scattering of acoustical modes of silicon nanoparticles embedded in silica matrix,

JOURNAL OF RAMAN SPECTROSCOPY, Issue 1-3 2006
M. Ivanda
Abstract The Raman scattering from acoustical phonons of silicon quantum dots in glass matrix was investigated. Two peaks that correspond to symmetric and quadrupolar spheroidal vibrations were found. A model calculation for in- and off-resonance scattering conditions was used, which considered the homogeneous broadening due to interaction with matrix and the inhomogeneous broadening due to particle size distribution. A strong dependence of the light-to-vibration coupling coefficient on the particles size was needed for fitting the Raman data. This result suggests that resonance with electronic transitions of the silicon nanoparticles is important for excitation at 514.5 nm. The size distribution obtained from the Raman data is in agreement with the results of high-resolution transmission electron microscopy. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Low-wavenumber Raman scattering spectroscopy in studies of new gallium-doped silica glass-based transparent vitroceramic medium

JOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2001
R. Ceccato
Optically transparent, silica glass-based vitroceramic material doped with gallium oxide was obtained by standard glass fusion and appropriate thermal treatments. Low-wavenumber Raman scattering spectroscopy allowed the determination of the microstructure and in particular the size distribution of nanoparticles embedded in the amorphous matrix. The nanocrystal growth was accurately controlled by heat treatment conditions. Transmission electron microscopy and X-ray diffraction measurements revealed the presence of a single crystalline phase, spherical-shaped nanoaggregates, homogeneously distributed in the transparent composite medium. Copyright © 2001 John Wiley & Sons, Ltd. [source]


Mesostructured Silica for Optical Functionality, Nanomachines, and Drug Delivery

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2009
Yaroslav Klichko
Silica thin films and nanoparticles prepared using sol,gel chemistry are derivatized with active molecules to generate new functional materials. The mild conditions associated with sol,gel processing allow for the incorporation of a range of dopants including organic or inorganic dyes, biomolecules, surfactants, and molecular machines. Silica nanoparticles embedded with inorganic nanocrystals, and films containing living cells have also been synthesized. Silica templated with surfactants to create mesostructure contains physically and chemically different regions that can be selectively derivatized using defined techniques to create dynamic materials. Using two different techniques, donor,acceptor pairs can be doped into separated regions simultaneously and photo-induced electron transfer between the molecules can be measured. Mesoporous silica materials are also useful supports for molecular machines. Machines including snap-tops and nanoimpellers that are designed to control the release of guest molecules trapped within the pores are described. Mesoporous silica nanoparticles are promising materials for drug delivery and other biomedical applications because they are nontoxic and can be taken up by living cells. Through appropriate design and synthesis, multifunctional mesoporous silica nanoparticles for sophisticated bio-applications are created. [source]


Photocatalytic Deposition of Silver Nanoparticles onto Organic/Inorganic Composite Nanofibers

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006
Sang Kyoo Lim
Abstract Summary: In this work, silver nanoparticles were embedded in electrospun organic/inorganic composite nanofibers consisting of PAN and TiO2 through photocatalytic reduction of the silver ions in silver nitrate solutions under UV irradiation. The morphology and diameter of PAN/TiO2 composite nanofibers could be controlled by varying the initial contents of TiO2 in the spinning solution. From TEM images and UV-Vis spectra, it has been confirmed that monodisperse silver nanoparticles with a diameter of ,2 nm were deposited selectively upon the titania of the as prepared composite nanofibers. The amount of Ag nanoparticles embedded on composite nanofibers was greatly influenced by the amount of TiO2 in composite nanofibers, reflecting the role of titania as the inorganic stabilizer and photocatalyst. Morphology of silver nanoparticles embedded on PAN/TiO2 composite nanofibers. [source]


Scaling behavior of plasmon coupling in Au and ReO3 nanoparticles incorporated in polymer matrices

PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010
Urmimala Maitra
Abstract Polymer nanocomposites containing different concentrations of Au nanoparticles have been investigated by small angle X-ray scattering and electronic absorption spectroscopy. The variation in the surface plasmon resonance (SPR) band of Au nanoparticles with concentration is described by a scaling law. The variation in the plasmon band of ReO3 nanoparticles embedded in polymers also follows a similar scaling law. Distance dependence of plasmon coupling in polymer composites of metal nanoparticles. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Ferromagnetic nanoparticles embedded in self-arranged matrices

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008
K. Rumpf
Abstract The investigated nanoscopic system, consisting of a non magnetic host material and precipitated ferromagnetic nanostructures shows a magnetic behaviour correlated to the size and shape of the deposited particles but also to their spatial distribution within the template which modifies the magnetic interactions between them. The nanostructures are deposited electrochemically into an etched silicon wafer exhibiting an array of channels of a few ten nanometers in diameter and a length up to 50 µm. The self-assembled grown templates offer the opportunity of tuning the magnetic properties by varying the geometrical characteristics of the membrane which can be loaded with different metals like Ni or Co with variable metal distribution. Magnetic characteristics like coercivity, magnetic anisotropy and temperature dependent magnetization give a survey about the structure and the magnetic interactions of the nanocomposite. This achieved ferromagnetic nanocomposite system is not only of interest for basic research but also gives rise to applications in magneto-optics, spintronics and sensor application. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Cooling-field dependence of exchange bias and asymmetric reversal modes in a nanoparticles system with ferromagnetic core and antiferromagnetic matrix morphology

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2009
Yong Hu
Abstract Interest in exchange bias (EB) in magnetic nanoparticles has increased in the past few years by virtue of its potential for application in fields such as ultrahigh-density magnetic recording. A modified Monte Carlo Metropolis method is performed to simulate the effect of cooling field on EB and asymmetric reversal modes of a granular system of ferromagnetic (FM) nanoparticles embedded in an antiferromagnetic (AFM) matrix, based on three-dimensional classical Heisenberg model. The results show that the EB first decreases slightly due to the energy barriers in the antiferromagnet, while the coercivity and vertical magnetization shift increase with the increase of cooling field, finally, they all level off as the cooling field is strong enough. Whereas the cooling- and measuring-field angular dependence of asymmetric reversal modes reveal asymmetric reversal mechanism and interesting rotation process of FM spins, confirming the existence of the net magnetization on the surface of AFM matrix. The reason may be due to the energy competition and geometric frustration of system. However, the strong interfacial coupling may change the intrinsic atomic configuration of antiferromagnet to influence the EB and reversal modes. [source]


Surface phonons in CdS1,xSex nanoparticles embedded in a dielectric medium

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2009
Yu. M. Azhniuk
Abstract Raman scattering by surface phonons in CdS1,xSex nanocrystals grown in a borosilicate glass matrix, is studied. CdSe-like and CdS-like surface phonon frequencies are shown to increase with the relevant component content in the nanocrystal composition. No clear size dependence of the surface phonon frequencies has been observed. On the other hand, surface phonons in CdS1,xSex nanocrystals exhibit resonant dependence on the Raman excitation wavelength. It is emphasized that measurements of Raman scattering by surface phonons in CdS1,xSex nanocrystals give no reason to judge upon the nanocrystal shape. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]