This study evaluated the metalloproteomic profile of muscle tissue samples from Nile tilapia (Oreochromis niloticus). Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) methods was used for protein fractionation and identification based on image analysis. Determination of Ca, Cu, Fe, Mn and Zn was performed in the protein spots by flame and/or graphite furnace atomic absorption spectrometry (FAAS, GFAAS), the protein spots were characterized by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). FAAS and GFAAS determinations have indicated the presence of calcium in seven protein spots, iron in only one spot, manganese in six spots, and zinc in two spots. Of the seventeen protein spots where the presence of metal ions was detected, ten were characterized by ESI-MS/MS.

Copper fractionation in plasma, muscle and liver of Nile tilapia was performed after protein separation by 2D-PAGE. SR XRF analysis indicated the presence of copper in three protein spots of plasma, and in two protein spots of muscle and liver, respectively. Copper ions were found to be distributed mostly in proteins that had a molar mass of less than 54 kDa and greater than 13 kDa and a pI in the 5.3-9.3 range. The copper concentration bound to these proteins was determined by GFAAS which showed concentrations in the 1.20-4.82 mg g-1 range.

The aim of the present work was to develop and optimize a method for determination of bioavailable phosphorus in samples of feces and fish feed using ultrasound extraction and subsequent quantification by visible spectrophotometry. Using as extractor solution HNO3 0.50 mol L-1, the great conditions of extraction established were: sample mass - 100 mg, samples granulometry - < 60 µm, sonification time - five cycles of 40 s and ultrasound potency - 136 W. The proposed method was applied in studies of digestibility of this nutrient in different feeds used in diets of juvenile of Nile tilapia.

Neste trabalho, um método simples, rápido e sensível, é proposto para determinação de manganês em amostras de fezes e rações de peixes por espectrometria de absorção atômica em forno de grafite (GFAAS) utilizando-se a introdução direta de suspensões das amostras no tubo de grafite. Os limites de detecção (LOD) e de quantificação (LOQ) calculados em relação a 20 leituras do branco das suspensões (0,50 % m/v de fezes ou ração isentas de manganês) foram de 28 e 92 µg kg¹ para as suspensões padrão de fezes e de 34 e 110 µg kg¹ para as suspensões padrão de ração. O método proposto foi aplicado em estudos de biodisponibilidade de manganês em diferentes amostras de rações de peixes e os resultados mostraram-se de acordo com os resultados obtidos utilizando-se amostras previamente mineralizadas por digestões ácidas em forno de microondas.

This paper presents a simple, fast and sensitive method to determine manganese in samples of feces and fish feed by graphite furnace atomic absorption spectrometry (GFAAS) by the direct introduction of slurries into the graphite tube. The limits of detection (LOD) and quantification (LOQ) calculated for 20 readings of the blank of the standard slurries (0.50 % m/v of feces or feed devoid of manganese) were 28 and 92 µg kg-1 for the standard feces slurries and 34 and 110 µg kg-1 for the standard feed slurries. The proposed method was applied in bioavailability studies of manganese in different fish feeds and their results proved compatible with those obtained for samples mineralized by acid digestion using microwave oven.

Este artigo descreve os resultados da fotodegradação de três tipos de fluidos de corte solúveis e emulsionavéis em meio aquoso, usando TiO2 como catalisador em suspensão e radiação UV. O TiO2 mostrou ser um catalisador efetivo na degradação dos fluidos de corte investigados. A velocidade de degradação depende do pH e da natureza dos fluidos. O melhor desempenho do catalisador foi observado em pH = 8,0 para todos os fluidos, quando mais de 70% da carga orgânica foi decomposta.

This paper describes results of the photo-degradation of three types of soluble and emulsive cutting fluids in an aqueous medium, using TiO2 as catalyst in suspension and UV radiation. The TiO2 proved to be an effective catalyst for the degradation of the cutting fluids investigated. The degradation rate depends on pH and nature of the fluids. The best performance of catalyst was observed at pH 8.0 for all the fluids when most of 70% of the organic load was decomposed.

Este trabalho descreve a síntese e caracterização da titânia modificada pelo ligante 2-aminotiazol e sua aplicação na foto-redução de íons Hg (II) em meio aquoso. Espectros obtidos na região do infravermelho confirmaram a modificação química da matriz de titânia. A quantidade de grupos 2-aminotiazol ligados à superfície da titânia foi determinada por meio da análise de nitrogênio, utilizando-se o método de Kjeldahl. Todos os experimentos de foto-redução foram feitos em um foto-reator cilíndrico termostatizado a 298 K. O catalisador modificado, 2-aminotiazol titânia (TiAT), apresentou maior capacidade de foto-redução dos íons Hg(II) nos valores de pH estudados (3, 7 e 9). Além disso, os estudos de sorção mostraram que o TiAT apresentou um menor tempo de equilíbrio e uma maior capacidade de sorção dos íons Hg(II), demonstrando que o processo de sorção desempenha um papel fundamental no mecanismo de foto-redução.

This work describes the synthesis and characterization of 2-aminothiazole-modified titania and its application on Hg (II) photoreduction in aqueous medium. Infrared spectroscopy confirmed the chemical modification of the titania matrix. The number of 2-aminothiazole groups attached to the titania was determined by Kjeldahl's method. The photocatalytic experiments were carried out in a cylindrical photoreactor thermostatted at 298 K. The resulting modified photocatalyst 2-aminothiazole titania (TiAT) revealed an enhance in the Hg (II) photoreduction capacity at studied pH values (3, 7 and 9). In addition, sorption studies showed that the photocatalyst TiAT presented a lower equilibrium time and a higher sorption capacity of Hg(II) ion, demonstrating that sorption plays a fundamental role in the photoreduction mechanism.

The silica gel was obtained from sand and its surface was modified with POCl3 to produce Si-Cl bonds on the silica surface. Ethylenediamine was covalently bonded onto the chlorinated silica surface. The adsorption of the chlorides of divalent cobalt, nickel and copper was qualitatively studied to show that the bonding of ethylenediamine onto the silica gel surface produces a solid base capable of chelating metal ions from solution. The experiments illustrate the extraction of silica gel, its reactivity, the development of modified surfaces and its application in removing metal ions from water and are deigned for undergraduate inorganic chemistry laboratories.

This work describes a modified sol-gel method for the preparation of V2O5/TiO2 catalysts. The samples have been characterized by N2 adsorption at 77K, x-ray diffractometry (XRD) and Fourier Transform Infrared (FT-IR). The surface area increases with the vanadia loading from 24 m² g-1, for pure TiO2, to 87 m² g-1 for 9wt.% of V2O5. The rutile form is predominant for pure TiO2 but became enriched with anatase phase when vanadia loading is increased. No crystalline V2O5 phase was observed in the catalysts diffractograms. Two species of surface vanadium observed by FT-IR spectroscopy a monomeric vanadyl and polymeric vanadates, the vanadyl/vanadate ratio remains practically constant.