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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An electrochemical method is developed to quantitatively modify and spectroscopically monitor the size and shape of Ag nanotriangles fabricated by nanosphere lithography (NSL) on an indium tin oxide (ITO) electrode surface. AFM and SEM results demonstrate that the preferential order of electrochemical oxidation for a nanotriangle is, surprisingly, bottom edges first, then triangular tips, then out-of-plane height.
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PMID:Electrochemical tuning of silver nanoparticles fabricated by nanosphere lithography. 1617 65

Platinum nanoparticles directly attached to indium tin oxide (PtNP/ITO) were successfully fabricated by using an in situ chemical reductive growth method. In this method, PtNPs could be grown on the ITO surface via the one-step immersion into the growth solution containing PtCl4(2-) and ascorbic acid. The attached and grown PtNPs were spherical having an agglomerated nanostructure composed of small nanoclusters. From the morphological changes depending on the growth time, which were observed with an FE-SEM, PtNPs were found to be grown via the progressive nucleation mechanism. As the characteristics of the PtNP/ITO were those of a working electrode, it was found that the charge transfer resisivity was significantly lowered due to the grown PtNPs. Hence, for a typical redox system of [Fe(CN)6]3-/[Fe(CN)6]4-, the PtNP/ITO electrode exhibited the electrochemical responses similar to those of the bulk Pt electrode. Furthermore, it was clarified that the PtNP/ITO electrode had significant electrocatalytic properties for the oxygen reduction and methanol oxidation. The present PtNPs that had the agglomerated nanostructure may be promising for a new type of electrode material.
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PMID:In situ chemical reductive growth of platinum nanoparticles on indium tin oxide surfaces and their electrochemical applications. 1647 56

A selection of samples, obtained from a particular copper-alloy domestic artefact of Roman style from Pompeii, has been analysed by using different techniques (IR, Raman, SEM-EDX, FAAS), in order to investigate the chemical nature and composition of the metals utilised for such manufacturing pieces. The surface analysis of the bright red metallic microfragments conducted by different analytical techniques, emphasises the presence of pure unalloyed copper and confirms the absence of other metallic species on the upper layers. On the contrary, the mapping analysis of the section of the laminar metal of the investigated sample shows a consistent enrichment in tin content. Finally, destructive analysis by FAAS confirms that the artefact looks like a bronze metal alloy, with a medium Sn content of about 6.5%.
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PMID:Investigation on a Roman copper alloy artefact from Pompeii (Italy). 1683 55

The three-dimensional (3D) accessible pore structures (Imm space groups) of continuous mesoporous silica SBA-16 thin films have been prepared by a dip-coating technique in nonaqueous media under acidic conditions on indium-tin oxide glass (ITO). The films are oriented with the (111) crystal plane perpendicular to the surface of the film. On one hand, deposition of iron metal into the mesopores of SBA-16 films was achieved by using an electrochemical method. The Fe2O3 nanowire arrays were synthesized. The crystalline structures of porous Fe2O3 nanowires and nanorods were studied via TEM, SEM, and XRD. On the other hand, a small amount of Fe was deposited into the pores of the SBA-16 thin film as a catalyst, and carbon nanotube arrays formed inside the pores of SBA-16 film were fabricated by catalytic decomposition of acetylene at 700 degrees C. The second-order template synthesis method for preparing the ordered array of carbon nanotubes filled with Fe has been used. The carbon nanotubes are very uniform in diameter and length and are aligned vertically with respect to the SBA-16 film.
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PMID:Controlled growth of mesostructured crystalline iron oxide nanowires and Fe-filled carbon nanotube arrays templated by mesoporous silica SBA-16 film. 1685 Dec 55

An effective and facile approach for the preparation of multilayered nanostructure of gold nanorods (Au NRs) has been demonstrated. Linear polyethylenimine (LPEI) was selected as a polymeric adhesive layer, and an anionic polyelectrolyte poly(sodium styrenesulfonate) (PSS) was used as the linker of the positively charged Au NRs in multilayered nanostructure. They were deposited onto the LPEI-modified indium-doped tin oxide (ITO) substrate alternately using the layer-by-layer assembly technique via electrostatic interactions. The plasmonic property of the multilayered nanostructure of Au NRs is tunable by the controlled self-assembly process. FE-SEM was used to study the morphologies of the resulted substrates with Au NRs monolayer membrane and with Au NRs multilayered membrane. More importantly, it was found that the multilayered NRs films could be used as a surface-enhanced Raman spectroscopy (SERS) substrate for probing 4-aminothiophenol (4-ATP).
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PMID:Fabrication, characterization, and application in SERS of self-assembled polyelectrolyte-gold nanorod multilayered films. 1685 3

Titanium carbide (TiC) nanoparticles are readily deposited onto tin-doped indium oxide (ITO) electrodes in the form of thin porous films. The nanoparticle deposits are electrically highly conducting and electrochemically active. In aqueous media (at pH 7) and at applied potentials positive of 0.3 V vs. SCE partial anodic surface oxidation and formation (at least in part) of novel core-shell TiC-TiO2 nanoparticles is observed. Significant thermal oxidation of TiC nanoparticles by heating in air occurs at a temperature of 250 degrees C and leads first to core-shell TiC-TiO2 nanoparticles, next at ca. 350 degrees C to TiO2 (anatase), and finally at temperatures higher than 750 degrees C to TiO2 (rutile). Electrochemically and thermally partially oxidized TiC nanoparticles still remain very active and for some redox systems electrocatalytically active. Scanning and transmission electron microscopy (SEM and TEM), temperature dependent XRD, quartz crystal microbalance, and voltammetric measurements are reported. The electrocatalytic properties of the core-shell TiC-TiO2 nanoparticulate films are surveyed for the oxidation of hydroquinone, ascorbic acid, and dopamine in aqueous buffer media. In TiC-TiO2 core-shell nanoparticle films TiO2 surface reactivity can be combined with TiC conductivity.
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PMID:Electrochemical properties of core-shell TiC-TiO2 nanoparticle films immobilized at ITO electrode surfaces. 1711 52

Mechanical properties of nanoparticle chain aggregates (NCA) including tensile strength and Young's modulus were measured using an instrument incorporating an AFM tip under SEM imaging. The NCA were studied individually and as network films. Carbon NCA were made by laser ablation of graphite, and SnO2 NCA were made by oxidation of a tin compound. The films were deformable and showed elastic behavior. NCA serve as reinforcing fillers in rubber and films of SnO2 NCA for trace gas detection.
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PMID:Mechanical properties of nanoparticle chain aggregates by combined AFM and SEM: isolated aggregates and networks. 1716 82

The direct oxidation of n-heptane to ester using air as the oxidant under mild conditions assisted by sulfated tin oxide (SO(4)(2-)/SnO(2)) and Co modified sulfated tin oxide (SO(4)(2-)/SnO(2)-Co(2)O(3)) prepared by chemical co-precipitation method and characterized by means of SEM, XRD, FT-IR and XPS techniques was studied. From the results it was found that the catalytic activity of SO(4)(2-)/SnO(2)-Co(2)O(3) is higher than that of SO(4)(2-)/SnO(2) in this target reaction, and two asymmetric esters: diisobutyl phthalate and cyclohexylmethyl tridecyl oxalate that have not been reported in the directly oxidation of n-heptane by traditional method have been obtained. The possible mechanism was also discussed.
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PMID:Direct oxidation of n-heptane to ester over modified sulfated SnO2 catalysts under mild conditions. 1732 Oct 46

Cryogenic scanning electron microscopy (cryo-SEM) was used to investigate microstructure development of composite coatings prepared from dispersions of antimony-doped tin oxide (ATO) nanoparticles (approximately 30 nm) or indium tin oxide (ITO) nanoparticles (approximately 40 nm) and latex particles (polydisperse, D(v): approximately 300 nm). Cryo-SEM images of ATO/latex dispersions as-frozen show small clusters of ATO and individual latex particles homogeneously distribute in a frozen water matrix. In contrast, cryo-SEM images of ITO/latex dispersions as-frozen show ITO particles adsorb onto latex particle surfaces. Electrostatic repulsion between negatively charged ATO and negatively charged latex particles stabilizes the ATO/latex dispersion, whereas in ITO/latex dispersion, positively charged ITO particles are attracted onto surfaces of negatively charged latex particles. These results are consistent with calculations of interaction potentials from past research. Cryo-SEM images of frozen and fractured coatings reveal that both ceramic nanoparticles and latex become more concentrated as drying proceeds; larger latex particles consolidate with ceramic nanoparticles in the interstitial spaces. With more drying, compaction flattens the latex-latex particle contacts and shrinks the voids between them. Thus, ceramic nanoparticles are forced to pack closely in the interstitial spaces, forming an interconnected network. Finally, latex particles partially coalesce at their flattened contacts, thereby yielding a coherent coating. The research reveals how nanoparticles segregate and interconnect among latex particles during drying.
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PMID:Cryo-SEM studies of latex/ceramic nanoparticle coating microstructure development. 1785 20

Hydrophilic silica (SiO2) nanoparticles were dispersed in solutions of poly(methyl methacrylate) (PMMA) and in solutions of a commercial poly(alkyl siloxane) (Rhodorsil 224), and the suspensions were sprayed on glass surfaces. The effect of the particle concentration on the hydrophobic character of PMMA-SiO2 and Rhodorsil-SiO2 films was investigated and showed the following: (i) Static contact angles (theta s), measured on surfaces that were prepared from dilute dispersions (particle concentration <1% w/v), increase rapidly with particle concentration and reach maximum values (154 and 164 degrees for PMMA-SiO2 and siloxane-SiO2, respectively). Further increases in particle concentration do not have any effect on theta s. (ii) The effect of particle concentration on the contact angle hysteresis (thetaAlpha - thetaR) is more complicated: as the particle concentration increases, we first notice an increase in hysteresis, which then decreases and finally becomes constant at elevated particle concentrations. The lowest thetaAlpha - thetaR values were 5 degrees for PMMA-SiO2 and 3 degrees for siloxane-SiO2, respectively. (iii) SEM and AFM images show that a two-length-scale hierarchical structure is formed on the surface of the superhydrophobic films. It is demonstrated that superhydrophobicity can be achieved using various hydrophilic nanoparticles (alumina and tin oxide nanoparticles were successfully tested) and that the substrate has almost no effect on the hydrophobic character of the applied coatings, which were produced on silicon, concrete, aluminum, silk, wood, marble, and of course glass. The results are discussed in light of Wenzel and Cassie-Baxter models.
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PMID:Superhydrophobic composite films produced on various substrates. 1872 Sep 65


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