Determination of Copper, Iron, Nickel and Zinc in fuel kerosene by FAAS after adsorption and pre-concentration on 2-aminothiazole-modified silica gel

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

Foam nest in Scinax rizibilis (Amphibia: Anura: Hylidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Spectroscopic characterization of schiff base-copper complexes immobilized in smectite clays

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

Copper toxicosis in sheep fed dairy cattle ration in São Paulo, Brazil

Intoxicação crônica por cobre foi observada em um rebanho de 20 ovinos no município de Franca, São Paulo. Três meses após o início do arraçoamento com feno e ração concentrada peletizada para bovinos de leite, seis animais apresentaram anorexia, icterícia severa e urina marrom escura, e vieram a óbito. Diagnosticou-se doença hemolítica com base em sinais clínicos, alterações macroscópicas observadas na necropsia e observações histológicas. À necropsia todos os ovinos apresentaram icterícia severa, fígado amarelado com padrão lobular evidente e rins escuros. As principais alterações histológicas incluíram necrose hepática periacinar e nefrose hemoglobinúrica. Acúmulos de cobre foram demonstrados nos hepatócitos e macrófagos pela coloração rodamina e níveis elevados de cobre mediante espectrofotometria de absorção atômica no soro, fígado e rins de dois ovinos afetados e na ração fornecida.

Vegetable-origin foam employed in dye extraction in tanning and leather processing facilities

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

SILVER DISSOLUTION ON COPPER-BASED ALLOYS

Electrical resistivity measurements and scanning electron microscopy was used to study the dissolution of silver on Cu-Ag and Cu-Al-Ag alloys. The results seem to indicate that the dissolution temperature is affected by the addition of aluminium.

Thermal behavior of copper(II) pseudohalide complexes containing bidentate amines

Pseudohalide complexes of copper(II) with aliphatic bidentate amines, [Cu(N-3)(2)(N,N-diEten)](2) 1, [Cu(NCO)(2)(N,N-diEten)](2) 2, [Cu(NCO)(2)(N,N-diMeen)](2) 3, [Cu(N-3)(NCS)(N,N'-diMeen)](2) 4 and [Cu(N-3)(NCO)(N,N-diMeen)](2) 5 (N,N-diEten=N,N-diethylethylenediamine; N,N-diMeen=N,N- dimethyl-ethylenediamine and N,N'-diMeen = N,N'-dimethylethylenediamine), were prepared, characterized and their thermal behavior was investigated by TG curves. According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving copper(II) oxide as final product. The mechanisms of decomposition were proposed and an order of thermal stability was established.

Solution infrared spectroscopy investigation of copper (II) azide-complexes.

The structure of the two azide-complexes, [Cu(N-3)(2)(N,N-diEten)](2) and [Cu(N-3)(2)(tmeen)](2), N,N-diEten=N,N-diethylethylenediamine; tmeen=N,N,N',N'-tetramethyethylenediamine in solutions of acetonitrile, acetone, tetrahydrofuran, chloroform and dichloromethane, were investigated by infrared spectroscopy. The data show that the complex [Cu(N-3)(2)(N,N-diEten)](2) mantains its structure in solution, while that for [Cu(N-3)(2)(tmeen)](2) is modified.

The effects of copper ions on the synthesis of periplasmic and membrane proteins in Acidithiobaeillus ferrooxidans as analyzed by SDS-PAGE and 2D-PAGE

The effects of 200 mM copper ions on the synthesis of membrane and periplasmic proteins were investigated in iron-grown cells of Acidithiobacillus ferrooxidans (At. ferrooxidans). Total membrane protein profiles of cells grown in the absence of copper ions (unadapted cells) and in the presence of copper ions (copper-adapted cells) were compared by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Crude preparations of outer membrane and periplasmic proteins were analyzed by SDS-PAGE. The synthesis of proteins was diminished or increased in the presence of copper ions. Low molecular weight proteins (< 14 kDa) were significantly repressed by copper. These proteins are probably acidic proteins located in the outer membrane. An over-expression of a periplasmic protein of about 17 kDa was detected in the copper-adapted cells and was assumed to be rusticyanin, a 16.5-kDa periplasmic copper protein present in At. ferrooxidans cells and involved in the electron-transport chain of the iron oxidation pathway. To our knowledge, this is the first report of a possible involvement of the rusticyanin and outer membrane proteins in the mechanism of copper resistance in At. ferrooxidans. (C) 2003 Elsevier B.V. All rights reserved.

Simultaneous determination of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry using a glassy carbon-mercury-film electrode

A new, versatile, and simple method for quantitative analysis of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry is described. These metals can be quantified by direct dissolution of fuel ethanol in water and subsequent voltammetric measurement after the accumulation step. A maximum limit of 20% (v/v) ethanol in water solution was obtained for voltammetric measurements without loss of sensitivity for metal species. Chemical and operational optimum conditions were analyzed in this study; the values obtained were pH 2.9, a 4.7-mum thickness mercury film, a 1,000-rpm rotation frequency of the working electrode, and a 600-s pre-concentration time. Voltammetric measurements were obtained using linear scan (LSV), differential pulse (DPV), and square wave (SWV) modes and detection limits were in the range 10(-9)-10(-8) mol L-1 for these metal species. The proposed method was compared with a traditional analytical technique, flame atomic absorption spectrometry (FAAS), for quantification of these metal species in commercial fuel ethanol samples.

On-line determination of Sb(III) and total Sb using baker's yeast immobilized on polyurethane foam and hydride generation inductively coupled plasma optical emission spectrometry

The yeast Saccharomyces cerevisiae was immobilized in cubes of polyurethane foam and the ability of this immobilized material to separate Sb(III) and Sb(V) was investigated. A method based on sequential determination of total Sb (after on-line reduction of Sb(V) to Sb(III) with thiourea) and Sb(Ill) (after on-line solid-liquid phase extraction) by hydride generation inductively coupled plasma optical emission spectrometry is proposed. A flow system assembled with solenoid valves was used to manage all stages of the process. The effects of pH, sample loading and elution flow rates on solid-liquid phase extraction of Sb(III) were evaluated. Also, the parameters related to online pre-reduction (reaction coil and flow rates) were optimized. Detection limits of 0.8 and 0.15 mu g L-1 were obtained for total Sb and Sb (III), respectively. The proposed method was applied to the analysis of river water and effluent samples. The results obtained for the determination of total Sb were in agreement with expected values, including the river water Standard Reference Material 1640 certified by the National Institute of Standards and Technology (NIST). Recoveries of Sb(III) and Sb(V) in spiked samples were between 81 19 and I I I 15% when 120 s of sample loading were used. (c) 2006 Elsevier B.V. All rights reserved.

Electrochemical studies with copper-based alloys: open-circuit potential oscillations in alkaline media

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)