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We report the first formation of arrays of InN nanorods inside the nanoscale channels of mesoporous silica SBA-15. In(NO3)3 dissolved in methanol was incorporated into SBA-15 powder without prior pore surface functionalization. Formation of InN nanorod arrays was carried out by ammonolysis at 700 degrees C for 8 h. The final products have been characterized by FT-IR spectra, (29)Si MAS NMR spectra, Raman spectra, XRD patterns, TEM images, nitrogen adsorption-desorption isotherm measurements, and optical spectroscopy. The freestanding InN nanorods observed after silica framework removal with HF solution show diameters of 6-7.5 nm and lengths of 25-50 nm. Formation of a trace amount of In2O3 was also verified. The InN nanorods exhibit a broad band centered at around 550-600 nm, and a band gap energy of 1.5 eV was determined. No light absorption in the near-IR region was measured. The nanorods give a weak emission band centered at around 600 nm. These optical properties are believed to be related to the possible incorporation of oxygen during InN nanorod synthesis.
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PMID:Formation of indium nitride nanorods within mesoporous silica SBA-15. 1831 14

Three series of Au(I)-imidazole complexes with stoichiometries of [Au(Cn-bim)Cl], [Au(Cn-im)Cl], and [Au(Cn-im)2][NO3] x 2H2O (Cn-bim = N-CnH2n+1 -substituted benzimidazole and Cn-im = N-CnH2n+1-substituted imidazole) together with the compound of [Au(C18-bim)2][NO3] are synthesiszed. Typical structures of each series are determined by single crystal X-ray diffraction. The last series of compounds, are liquid crystals, and exhibit a wider mesophase range than their Ag(I) analogues. These Au(I) complexes form Au nanostructures both through chemical reduction or thermolysis. For the first time, N-long chain imidazole is utilized to stabilize colloidal Au in solution. Also for the first time, unique examples of simple thermolysis to produce large Au plates of nanothickness are demonstrated. Formation of a plate-like morphology through fusion of sphere-like nanoparticles at an early stage is evidenced by TEM images.
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PMID:Au(i)-benzimidazole/imidazole complexes. Liquid crystals and nanomaterials. 1836

Changes in morphology, surface reactivity and surface-enhancement of Raman scattering induced by modification of borate-stabilized Ag nanoparticles by adsorbed chlorides have been explored using TEM, EDX analysis and SERS spectra of probing adsorbate 2,2'-bipyridine (bpy) excited at 514.5 nm and evaluated by factor analysis. At fractional coverages of the parent Ag nanoparticles by adsorbed chlorides <0.6, the Ag colloid/Cl(-)/bpy systems were found to be constituted by fractal aggregates of Ag nanoparticles fairly uniform in size (10 +/- 2 nm) and SERS spectra of Ag(+)-bpy surface species were detected. The latter result was interpreted in terms of the presence of oxidized Ag(+) and/or Ag(n)(+) adsorption sites, which have been encountered also in systems with the chemically untreated Ag nanoparticles. At chloride coverages >0.6, a fusion of fractal aggregates into the compact aggregates of touching and/or interpenetrating Ag nanoparticles has been observed and found to be accompanied by the formation of another surface species, Ag-bpy, as well as by the increase of the overall SERS enhancement of bpy by factor of 40. The same Ag-bpy surface species has been detected under the strongly reducing conditions of reduction of silver nitrate by sodium borohydride in the presence of bpy. The formation of Ag-bpy is thus interpreted in terms of the stabilization of reduced Ag(0) adsorption sites by adsorbed bpy. The formation of reduced adsorption sites on Ag nanoparticle surfaces at chloride coverages >0.6 is discussed in terms of local changes in the work function of Ag. Finally, the SERS spectral detection of Ag-bpy species is proposed as a tool for probing the presence of reduced Ag(0) adsorption sites in systems with chemically modified Ag nanoparticles.
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PMID:SERS-activating effect of chlorides on borate-stabilized silver nanoparticles: formation of new reduced adsorption sites and induced nanoparticle fusion. 1840 31

In this study production of fine particle Fe2O3 via microwave processing of Fe(NO3)3.nH2O followed by low temperature annealing was reported. XRD was used to characterize the structural properties of nanoparticles. Approximate particle sizes were between 3-13 nm according to Scherrer's equation. Single point BET measurement results also show that samples have large surface area and they are nanometer sized particles. TEM study was conducted to examine the structure of the nanoparticles. TEM figure is in good agreement with the results obtained from Scherrer's equation using XRD spectra. In order to characterize the magnetic properties of the nanoparticles VSM (Vibrating Sample Magnetometer) was used. From these results it can be concluded that the sample containing only maghemite phase exhibits superparamagnetic behaviour, on the other hand sample containing both hematite and maghemite phases shows paramagnetic behaviour above 300 K, superparamagnetic behavior at lower temperatures.
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PMID:Preparation of iron oxide nanoparticles by microwave synthesis and their characterization. 1846 87

Iron oxide thin films were prepared by spin-coating a gel solution of iron(III) nitrate dissolved in 2-methoxyethanol and acetylacetone on glass and quartz substrates. The film thickness was adjusted by changing the spinning rate of the spin coater. Annealing was carried out between 300 degrees C to 600 degrees C to investigate the phases present in the films. Viscosity of the main solution was found as 0.0035 Pa.s by viscosity measurement. TGA/DTA analyses showed that heat treatment should be done between 330 degrees C and 440 degrees C in order to produce maghemite thin films. SEM studies showed that single layer thickness of the films were between 65 and 80 nm. The structural characteristics were evaluated by changing the experimental parameters which are annealing temperature, annealing time and thickness of the films. From the X-ray diffraction analysis, maghemite formation was observed with decreasing annealing temperature, annealing time and film thickness. TEM results verified the presence of the maghemite phase by electron diffraction and selected area electron diffraction (SAED) methods. According to UV-Vis results transmittance of the films decreases with increasing annealing temperature.
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PMID:Characterization of iron oxide thin films prepared by sol-gel processing. 1846 25

Aqueous micellar solutions of the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) and sodium nitrate (NaNO(3)) were examined using steady and dynamic rheology, small-angle neutron scattering (SANS) and cryogenic-transmission electron microscopy (cryo-TEM). Upon addition of NaNO(3), the CTAB spherical micelles transform into long, flexible wormlike micelles, conveying viscoelastic properties to the solutions. The zero-shear viscosity (eta(0)) versus NaNO(3) concentration curve exhibits a well-defined maximum. Likewise, upon increase in temperature, the viscosity decreases. Dynamic rheological data of the entangled micellar solutions can be well described by the Maxwell model. Changes in the structural parameters of the micelles with addition of NaNO(3) were inferred from SANS measurements. The intensity of scattered neutrons at the low q region was found to increase with increasing NaNO(3) concentration. This suggests an increase in size of the micelles and/or decrease of intermicellar interactions with increasing salt concentration. Analysis of the SANS data using prolate ellipsoidal structure and Yukawa form of interaction potential between micelles indicates that addition of NaNO(3) leads to a decrease in the surface charge of the ellipsoidal micelles and consequently an increase in their length. The structural transition from spherical to entangled threadlike micelles, induced by the addition of NaNO(3) to CTAB micelles is further confirmed by cryo-TEM.
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PMID:Viscoelastic micellar water/CTAB/NaNO(3) solutions: rheology, SANS and cryo-TEM analysis. 1848 41

A controlled and up-scalable route for the biosynthesis of silver nanopartilces (NPs) mediated by fungal proteins of Coriolus versicolor has been undertaken for the first time. The fungus when challenged with silver nitrate solution accumulated silver NPs on its surface in 72h which could be reduced to 1h by tailoring the reaction conditions. Under alkaline conditions, the reaction was much faster and could easily proceed at room temperature even without stirring. The resulting Ag NPs displayed controllable structural and optical properties depending on the experimental parameters such as pH and reaction temperatures. The average size, morphology, and structure of particles were determined by AFM, TEM, XRD and UV/Visible absorption spectrophotometry. Fourier transform infrared study disclosed that the amino groups were bound to the particles, which was accountable for the stability of NPs. It further confirmed the presence of protein as the stabilizing and capping agent surrounding the silver NPs. Experiments were conducted both with, media in which fungus was initially harvested and that of pristine fungal mycelium alone. Under normal conditions, in the case of media extracellular synthesis took place whereby other than the fungal proteins, glucose was also responsible for the reduction. In the case of fungal mycelium, the intracellular formation of Ag NPs, could be tailored to give both intracellular and extracellular Ag NPs under alkaline conditions whereby the surface S-H groups of the fungus played a major role.
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PMID:Biomimetic synthesis and characterisation of protein capped silver nanoparticles. 1862 50

Metal Fe or Cu doped P25 titania was prepared using the photodeposition method and characterized by TEM, ICP, XRD and UV-Vis, further tested for photocatalytic nitrate reduction and TN removal, under 20 W UV lamp irradiation. The influencing factors such as the pH values of solution, stirring gas, metal loadings, hole scavenger formic acid amount and co-doped Ag-Cu/TiO2 are investigated and discussed in detail. The experimental results after 2 h reaction indicated that with the increase of Cu loadings, nitrate conversion increases too, while a loading of 0.5% is optimal for highest N2 selectivity and TN (total nitrogen) removal. Using N2 as stirring gas and under acidic conditions, the N2 selectivity is lower (62%), but the highest conversion of nitrate and removal of TN can reach 36.9% and 23.2% respectively. Using CO2 as stirring gas, the highest selectivity for nitrogen 88.4% is obtained with 0.5% Cu/TiO2, 0.06 mol/L formic acid. Under the same conditions, using the prepared bimetallic titania (1%, 1:1 Ag/Cu), the conversion of nitrate and removal of TN are 48.1%, 34.2%, and N2 selectivity is 72.2%.
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PMID:[Photocatalytic reduction of nitrate using metal-doped titania]. 1906 39

The present work describes ceric ammonium nitrate (CAN) initiated graft copolymerization of acrylamide onto cellulose-based filter paper followed by entrapment of silver nanoparticles. The copolymerization was carried out in aqueous solution, containing 2M acrylamide monomer and 16mM N,N'-methylene bisacrylamide (MB) crosslinker. The optimum initiation time and grafting reaction temperature were found to be 15min and 30 degrees C, respectively. The silver nanoparticles were loaded into grafted filter paper by equilibration in silver nitrate solution followed by citrate reduction. The formation of silver nanoparticles has been confirmed by TEM and SAED analysis. The novel nano silver loaded filter paper has been investigated for its antimicrobial properties against E.coli. This newly developed material shows strong antibacterial property and thus offers its candidature for possible use as antibacterial food-packaging material.
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PMID:Graft copolymerization onto cellulose-based filter paper and its further development as silver nanoparticles loaded antibacterial food-packaging material. 1913 Dec 17

Magnetic iron oxide nanoparticles were successfully prepared by a novel reverse precipitation method with the irradiation of ultrasound. TEM, XRD and SQUID analyses showed that the formed particles were magnetite (Fe(3)O(4)) with about 10nm in their diameter. The magnetite nanoparticles exhibited superparamagnetism above 200K, and the saturation magnetization was 32.8 emu/g at 300 K. The sizes and size distributions could be controlled by the feeding conditions of FeSO(4).7H(2)O aqueous solution, and slower feeding rate and lower concentration lead to smaller and more uniform magnetite nanoparticles. The mechanisms of sonochemical oxidation were also discussed. The analyses of sonochemically produced oxidants in the presence of various gases suggested that besides sonochemically formed hydrogen peroxide, nitrite and nitrate ions contributed to Fe(II) ion oxidation.
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PMID:Preparation of superparamagnetic magnetite nanoparticles by reverse precipitation method: contribution of sonochemically generated oxidants. 1920 Jul 71


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