INTERNATIONAL NANO LETTERS (INL)
Year:2013 | Volume:3 | Issue:3|Papers Count:12

Ni0.8-xCu0.2ZnxFe2O4 (x=0.0£0.6 with steps of 0.2) ferrite nanophase was achieved by sol–gel auto-combustion technique. The as-prepared samples were thermally characterized by thermogravimetry/differential thermal analysis to obtain firing temperature of the materials. The X-ray diffraction pattern indicates the formation of a single-phase cubic spinel structure and shows strong influence of the incorporation of Zn2+ metal ions on the spinel structure. The annealing treatment does not alter the crystal structure but increases the crystallinity of the samples. The morphological investigations and nanometric sizes of the samples were studied by scanning electron microscopy and transmission electron microscopy. The crystallographic texture due to annealing and Zn2+ ion doping was systematically investigated by Fourier transform infrared spectroscopy.

Nanoparticles of molecularly imprinted polymers (MIPs) were prepared by precipitation polymerization method. Glucose was used as a template molecule. The impact of different process parameters on the preparation of nanoparticles was investigated in order to reach the maximum binding capacity of MIPs. Experimental data based on uniform design were analyzed using artificial neural network to find the optimal condition. The results showed that the binding ability of nanoparticles of MIPs prepared under optimum condition was much higher than that of the corresponding non-imprinted nanoparticles (NIPs). The findings also demonstrated high glucose selectivity of imprinted nanoparticles. The results exhibited that the particle size for MIP nanoparticles was about 557.6 nm, and the Brunauer-Emmett-Teller analysis also confirmed that the particle pores were mesopores and macropores around 40 nm and possessed higher volume, surface area, and uniform size compared to the corresponding NIPs.

TiO2 doped with Cu2+ initiates the formation of brookite phase along with anatase. Doping of Cu2+ introduces structural defects into TiO2. The direct evidence is the low intense and broad diffraction peaks. Raman peaks of doped TiO2 are also broad and are blue shifted. Pure TiO2 exhibits an absorption in the UV region, the position of which is shifted towards the visible region on incorporation of Cu into it. The visible absorption peaks arise due to thed-d transition of Cu2+ in the crystalline environment of TiO2. Incorporation of Cu2+ distorts the local structure of TiO2, resulting in the loss of octahedral symmetry surrounding Cu2+. The Jahn-Teller distortion splits the 2Eg and 2T2g state of Cu2+ into several d states. Interaction of light excites the electron from ground to several of the excited states and gives the visible absorption peaks in the framework of TiO2. These Cu2+d states and oxygen defects create band states, thereby favoring electronic transition to these levels and resulting in lowering of band gap of TiO2. A direct confirmation is the increase in the magnitude of Urbach energy with the reduction in the band gap of doped TiO2.

In a new theoretical investigation, we study light transmission through a photonic crystal (PC) slab with limited boundaries at width. By using a tight binding model, photon dispersion relation and photon Green function for a perfect system are obtained. Then, based on the Lippmann-Schwinger formalism, we calculate the effects of disordering on light transmission in the PC channel. We found that the ratio of the electric field for a defected system with respect to a perfect system at a pecu-liar frequency is maximized for the wave vector corresponding to the first Brillouin zone (BZ) edge showing photon localization. The electric field difference of the first and second neighboring sites with respect to the defect site on the first BZ edges are depicted in several plots indicating frequency dependence which can be applicable in frequency filtering or resonating cavity studies.

In this article, Ru (4, 4'-dicarboxy-2, 2'-bipyridine) 2 (NCS) 2 dye (N3) and some derivatives were investigated using Density Functional Theory (DFT) calculations in solution to elucidate the influence of the environment and substituted groups on electronic properties. Full geometry optimization and investigation of electronic properties of N3 dye and some derivatives were performed using DFT and HF calculations. The singlet ground state geometries were fully optimized at the B3LYP/3-21G** level of theory through the Gaussian 98 program. Based on the computed results, the optoelectronic properties are sensitive to chemical solvent environments. Moreover, the properties of anatase cluster (TiO2) models have been investigated, and N3 dyes have been adsorbed on TiO2 nano-particle with diprotonated states. The modified N3 dyes highly affected the electronic structure. This leads to significant changes in the adsorption spectra as compared to the N3 dyes. Through hybrid methods, the properties of interfacial electronic coupling of the combined system were estimated. The results of some combined systems showed that the electronic coupling, lowest lowest unoccupied molecular orbitals, and the TiO2 conduction band resided in the visible region.

Nickel ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various concentrations of poly (vinylpyrrolidone) followed by calcination temperature. X-ray diffraction (XRD) analysis was performed to determine the degree of crystallinity of the ferrite nanoparticles. By transmission electron microscopy, the morphology and average particle size of the nickel ferrite nanoparticles were evaluated which had good agreement with the XRD results. Fourier transform infrared spectroscopy suggested the presence of metal oxide bands in all samples as well as the effective elimination of organic constituents after calcinations. Measurements of the extent of magnetization of the nickel ferrite nanoparticles synthesized in different concentrations were obtained at room temperature using a vibrating sample magnetometer.

Metal complexes containing one or several bis(triorganylphosphine)palladium fragments attached to the C60 core and coordinated in olefinic h2 mode have been previously described. The number of carbon atoms of the single walled carbon nanotubes (SWCNTs) is the useful numerical and structural electrochemical properties contributing to the relationship between the structures of the h2_CmPd(dppf), h2_CmPd(dppr), and h2_CmPd(dppcym)2 (m=60 and 70) ligands (A to E) and [SWCNT(5,5)-armchair-CnH20] (n=20 to 190) 1 to 18 and the production of the [SWCNT (5,5)-armchair-CnH20][R] (R=h2-CmPd(dppf), h2-CmPd(dppr), and h2-CmPd(dppcym)2, n=20 to 300 and m=60 and 70) complexes 30 to 174. In this study, the relationship between the number of carbon atoms index and the first and second free energies of electron transfer (DGet(n), n=1,2) using the Rehm-Weller equation based on the first and second oxidation potentials (oxE1 and oxE2) of A to E for the predicted complexes 30 to 174 between 1 and 29 with exohedral metallofullerenes A to E, as [SWCNT(5,5)-armchair-CnH20][R] (R=h2-CmPd(dppf), h2-CmPd(dppr), and h2-CmPd(dppcym)2, n=20 to 300 and m=60 and 70) 30 to 174 was assessed. Here, the first and second free activation energies of electron transfer and the wavelengths of the electromagnetic photons in the photoelectron transfer process, DG#et(n) and l(n) (nm), respectively, for 30 to 174 in accordance with the Marcus theory and Planck's equation were also calculated.

In the present paper, influence of photon on resistance of non-180o domain wall in metallic magnetic nanowires has been studied using the semiclassical approach. The analysis has been based on the Boltzmann transport equation, within the relaxation time approximation. The one-dimensional Neel-type domain wall between two ferromagnetic domains with relative magnetization angle less than 180° is considered. By increasing this angle, the contribution of the domain wall in the resistivity of the nanowire becomes considerable. It is also found that the fundamental contribution of the domain wall in resistivity can be controlled by propagating photon. These results are valuable in designing spintronic devices based on magnetic nanowires.

In the present study, Fe3O4@SiO2 core–shell microspheres were prepared via two steps. First, Fe3O4 nanoparticles were synthesized by co-precipitation of Fe+3 and Fe+2 as reaction substrates and NaOH as precipitant. Second, the surface of Fe3O4 was coated with silica by hydrolysis of tetraethylorthosilicate as the silica source. Subsequently, in order to reduce the amount of interaction and the agglomeration of Fe3O4@SiO2 microspheres, the silica shell of these particles was modified by vinyltriethoxysilane as the silane coupling agent. The structural properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy analyses. The results indicated that the average sizes of Fe3O4 and Fe3O4@SiO2 particles were about 50 and 500 nm, respectively. Also, the surface characterization of Fe3O4@SiO2 microspheres showed that the silane coupling agent was covalently coupled with the silica surface.

Vanadium pentoxide (V2O5) thin films were grown on indium tin oxide-coated flexible Kapton substrates by homebuilt activated reactive evaporation technique. Film depositions were carried out at optimised oxygen partial pressure of 1×10-3 Torr and plasma power of 8 W, and we investigated their microstructural and optoelectrochromic properties as a function of substrate temperature. The V2O5 films grown at Ts=473 K exhibited a nano-crystalline nature as evidenced from X-ray diffraction, atomic force microscopy and Raman studies. The nanocrystalline films composed of vertical elliptical-shaped grainy morphology demonstrated a high optical transmittance of 75% with an estimated optical bandgap of 2.38 eV. The dry lithiated nano-crystalline V2O5 films demonstrated an optical modulation of 36.1% with a coloration efficiency value of 26.2 cm2/C at a wavelength of 550 nm. As-deposited nano-crystalline V2O5 thin films demonstrated a constant discharge capacity of about 60 mAh cm-2 mm-1 for a few cycles at room temperature in the potential window of 4.0 to 2.5 V.

Platinum nanoparticles (PNPs) were synthesized by chemical reduction of potassium hexachloroplatinate (IV) with trisodium citrate under vigorous stirring and addition of sodium dodecyl sulfate as stabilizer reagent. Reducing agent was chosen depending on the oxidation reactions and potential values of the chemical materials used in the experiment. The aim of this study is to investigate the effects of PNPs on the different cancer cell lines and cytotoxicity study of this nanomaterial. The morphology of PNPs was investigated by scanning electron microscope (XL30, Philips Electronics, Amsterdam, The Netherlands) with the ability to perform elemental analysis by EDX.Malvern Zetasizer 3000 HSA (Malvern Instruments, Worcestershire, UK) was used to determine the distribution of particle size and zeta potential of PNPs. The cytotoxicity property of the nanoparticles was evaluated by MTT assay on MCF-7 and HepG-2 cell lines, and the cytotoxic concentration 50% values were determined for 24 h.

Microbial bio fabrication is emerging as eco-friendly, simpler, and reproducible alternative to chemical synthesis of metals and semiconductor nanoparticles, allowing generation of rare geometrical forms such as nanotriangles and nanoprisms. Highly confined nanostructures like triangles/prisms are interesting class of nanoparticles due to their unique optical properties exploitable in biomedical diagnostics and biosensors. Here, we report for the first time a single-step biological protocol for the synthesis of gold nanotriangles using extract of endophytic actinomycetes Saccharomonosporasp., isolated from surface sterilized root tissues of Azadirachta indica A. Juss., when incubated with an aqueous solution of chloroaurate ions (AuCl-4 /1 mM). Thin, flat occasionally prismatic gold nanotriangles were produced when aqueous chloroaurate ions reacted with the cell-free extract as well as with the biomass of endophytic Saccharomonospora. It was evidenced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis that proteins of 42 and 50 kD were involved in biosynthesis as well as in stabilization of the nanoparticles. The particle growth process was monitored by UV–vis spectroscopy, and the morphological characterization was carried out by transmission electron microscopy and atomic force microscopy together with X-ray powder diffractions. Although the exact mechanism for this shape-oriented synthesis is not clear so far, the possibility of achieving nanoparticle shape control in a microbial system is exciting.