A novel ozone gas sensor based on one-dimensional (1D) alpha-Ag2WO4 nanostructures

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vanadium-doped TiO2 anatase nanostructures: the role of V in solid solution formation and its effect on the optical properties

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rapid preparation of alpha-FeOOH and alpha-Fe2O3 nanostructures by microwave heating and their application in electrochemical sensors

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Complexes of platinum and palladium with beta-diketones and DMSO: Synthesis, characterization, molecular modeling, and biological studies

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Exploring copper nanostructures as highly uniform and reproducible substrates for plasmon-enhanced fluorescence

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

One-dimensional silicon and germanium nanostructures with no carbon analogues

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrocatalytic effect of Pb and Sn adatoms on the oxidation of 1-propanol on platinized platinum electrodes: Determination of the apparent activation energy

The electrocatalytic oxidation of 1-propanol was investigated on platinum electrodes modified by submonolayers of Pb and Sn in acid media. An increase of oxidation rates observed for both Pb and Sn, and the influence of theta values was investigated. The values of the apparent activation energy evaluated from the Arrhenius plots concerning the electrochemical oxidation of 1-propanol on modified platinzed platinum electrodes, reveal a significant decrease in the presence of upd Sn and Ph adatoms. A decrease from 56 to 26 U mol(-1) in the presence of Sn. and from 78 to 25 U mol(-1) for Ph adatoms are some illustrative values which reflect the promoting effect of the upd adatoms.

Platinum-Group Minerals in Chromitites of the Niquelandia Layered Intrusion (Central Goias, Brazil): Their Magmatic Origin and Low-Temperature Reworking during Serpentinization and Lateritic Weathering

A variety of platinum-group-minerals (PGM) have been found to occur associated with the chromitite and dunite layers in the Niquelandia igneous complex. Two genetically distinct populations of PGM have been identified corresponding to phases crystallized at high temperatures (primary), and others formed or modified during post-magmatic serpentinization and lateritic weathering (secondary). Primary PGM have been found in moderately serpentinized chromitite and dunite, usually included in fresh chromite grains or partially oxidized interstitial sulfides. Due to topographically controlled lateritic weathering, the silicate rocks are totally transformed to a smectite-kaolinite-garnierite-amorphous silica assemblage, while the chromite is changed into a massive aggregate of a spinel phase having low-Mg and a low Fe3+/Fe2+ ratio, intimately associated with Ti-minerals, amorphous Fe-hydroxides, goethite, hematite and magnetite. The PGM in part survive alteration, and in part are corroded as a result of deep chemical weathering. Laurite is altered to Ru-oxides or re-crystallizes together with secondary Mg-ilmenite. Other PGM, especially the Pt-Fe alloys, re-precipitate within the altered chromite together with kaolinite and Fe-hydroxides. Textural evidence suggests that re-deposition of secondary PGM took place during chromite alteration, controlled by variation of the redox conditions on a microscopic scale.

Towards an understanding on the role of precursor in the synthesis of ZnS nanostructures

Wurtzite-structured ZnS nanostructures have been synthesized by means of a microwave-solvothermal method at 140°C using three precursors (chloride, nitrate and acetate). Different techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy and photoluminescence (PL) measurements have been employed to characterize this material. The structure, surface morphology, chemical composition and optical properties were investigated as function of precursor. In order to complement experimental results, first principles calculations at DFT level were carried out in order to obtain the relative stability of the proposed intermediates along the formation mechanism. - See more at: http://www.eurekaselect.com/117237/article#sthash.GzvnCBTB.dpuf

Experimental and theoretical study on the structure, optical properties, and growth of metallic silver nanostructures in Ag3PO4

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adsorption kinetics of n-propanol on platinized platinum electrode in sulphuric acid solution

the adsorption kinetics of n-propanol on platinized platinum electrode in sulphuric acid solution is studied. Data on the influence of adsorption potential and of temperature are given. Values for the velocity constants and for activation energies are evaluated from the experimental data. © 1989.

Thermal analysis of coordination compounds. Part 3. Thermal decomposition of platinum complexes containing triphenylphosphine, triphenylarsine and triphenylstibine

Studies by thermogravimetric analysis (TG) and differential thermal analysis (DTA) of the complexes [PtCl2L2] (L is PPh3, AsPh3, SbPh3), [PtLn] (n = 3, L is SbPh3; n = 4, L is PPh3, AsPh3); [(PtL3)2N2]; [(PtL3)2C2] and [Pt(CO)2L2] (L is SbPh3) are described. Analysis of the TG and DTA curves showed that Pt(II) complexes of the type [PtCl2L2] have a higher thermal stability than the corresponding Pt(0) complexes of the type [PtLn], with the exception of [Pt(SbPh3)3], which is more stable than [PtCl2(SbPh3)2]. Thermal stabilities of each of the complexes are compared with those of the others in the series. Mechanisms of thermal decomposition of complexes of the types [PtCl2L2] and [PtLn] are proposed. Residues of the samples were characterized by chemical tests and IR spectroscopy. The residue from the thermal decomposition of [PtCl2L2] (L is PPh3, AsPh3) and [Pt(PPh3)4] is metallic platinum. For [Pt(AsPh3)4] the residue is a mixture of Pt and As, whereas for the complexes containing SbPh3 the residues are mixtures of Pt and Sb. In these cases, the proportional contents of Pt and As or Pt and Sb correspond to the stoichiometry of these elements in the respective complexes. The complexes {[Pt(SbPh3)3]2N2}, {[Pt(SbPh3)3]2C2} lose N2 or the ethynediyl group at 130-150°C and are transformed into [Pt(SbPh3)3]. © 1995.

Bio-hydrogen production based on catalytic reforming of volatiles generated by cellulose pyrolysis: an integrated process for ZnO reduction and zinc nanostructures fabrication

The paper presents a process of cellulose thermal degradation with bio-hydrogen generation and zinc nanostructures synthesis. Production of zinc nanowires and zinc nanoflowers was performed by a novel processes based on cellulose pyrolysis, volatiles reforming and direct reduction of ZnO. The bio-hydrogen generated in situ promoted the ZnO reduction with Zn nanostructures formation by vapor–solid (VS) route. The cellulose and cellulose/ZnO samples were characterized by thermal analyses (TG/DTG/DTA) and the gases evolved were analyzed by FTIR spectroscopy (TG/FTIR). The hydrogen was detected by TPR (Temperature Programmed Reaction) tests. The results showed that in the presence of ZnO the cellulose thermal degradation produced larger amounts of H2 when compared to pure cellulose. The process was also carried out in a tubular furnace with N2 atmosphere, at temperatures up to 900 °C, and different heating rates. The nanostructures growth was catalyst-free, without pressure reduction, at temperatures lower than those required in the carbothermal reduction of ZnO with fossil carbon. The nanostructures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The optical properties were investigated by photoluminescence (PL). One mechanism was presented in an attempt to explain the synthesis of zinc nanostructures that are crystalline, were obtained without significant re-oxidation and whose morphologies are dependent on the heating rates of the process. This route presents a potential use as an industrial process taking into account the simple operational conditions, the low costs of cellulose and the importance of bio-hydrogen and nanostructured zinc.

Produção de tomate em função da vibração das plantas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Pyrolysis and auto-gasification of black liquor in presence of ZnO: An integrated process for Zn/ZnO nanostructure production and bioenergy generation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)