Wavelet-Based determination of Cu and Pb in water samples using potentiometric stripping analysis with a Lab-Made potentiostat

This paper demonstrates the possibility of simultaneously determining lead and copper in mineral, river and tap water by potentiometric stripping analysis using a low-cost lab-made potentiostat and a wavelet-based signal processing method. Pb(II) and Cu(II) concentrations were found to be in the range 3-7 µg L-1. Relative standard deviations were on average smaller than 3%, which is satisfactory in view of the trace concentration. For comparison, the determination was also carried out by using a high-end commercial equipment (μAutolab Type II, Eco Chemie). The average and standard deviation of the results were similar to those obtained with the lab-made potentiostat. No significant statistical difference was verified according to a paired t-test at a confidence level of 95%

Alternativas culturais para o manejo do nematoide das lesões radiculares durante a entressafra da soja no Mato Grosso.

O objetivo do trabalho foi avaliar os efeitos de diferentes práticas culturais adotadas na entressafra sobre a população do nematoide das lesões radiculares (Pratylenchus brachyurus) e os danos causados por ele na soja na safra 2012/2013

Caracterização do módulo de crescimento do pinhão-manso (Jatropha curcas L.) na microregião geográfica de Teresina-Piauí.

O pinhao-manso (Jatropha curcas L.) e uma oleaginosa bastante promissora para producao de oleo. Entretanto, pesquisas com essa Euforbiacea na regiao Meio-Norte do Brasil praticamente nao existem, e atualmente ha uma forte demanda por parte dos empresarios para obter informacoes tecnicas sobre o manejo dessa planta para a producao de oleo (biodiesel). Para a exploracao racional dessa especie de forma economica, ambiental e socialmente sustentada, ainda faltam informacoes basicas, exigindo a experimentacao em diversas areas e dentre essas se destaca a da fisiologia de producao..

Performance of Nellore steers submitted to different weaning strategies.

The experiment evaluated the performance of Nellore steers submitted to different weaning strategies, in Corumbá/MS ? Brazil. The Nellore steers (n=48; 123±22 days of age; 110.8±21.67 kg of BW) were stratified by BW, and managed in a rotational stocking in Brachiaria humidicola pastures (2 hectares/animal), between September 2015 and June, 2016

Caracterização biométrica e molecular do caprino Nambi no Estado do Piauí.

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Photo-induced electron transfer in supramolecular materials of titania nanostructures and cytochrome c

In the present paper, we report on the molecular interaction and photochemistry of TiO2 nanoparticles (NPs) and cytochrome c systems for understanding the effects of supramolecular organization and electron transfer by using two TiO2 structures: P25 TiO2 NPs and titanate nanotubes. The adsorption and reduction of cytochrome c heme iron promoted by photo-excited TiO2, arranged as P25 TiO2 NPs and as nanotubes, were characterized using electronic absorption spectroscopy, thermogravimetric analysis, and atomic force microscopy. In an aqueous buffered suspension (pH 8.0), the mass of cytochrome c adsorbed on the P25 TiO2 NP surface was 2.3 fold lower (0.75 μg m−2) than that adsorbed on the titanate nanotubes (1.75 μg m−2). Probably due to the high coverage of titanate nanotubes by adsorbed cytochrome c, the low amount of soluble remaining protein was not as efficiently photo-reduced by this nanostructure as it was by the P25 TiO2 NPs. Cytochrome c, which desorbed from both titanium materials, did not exhibit changes in its redox properties. In the presence of the TiO2 NPs, the photo-induced electron transfer from water to soluble cytochrome c heme iron was corroborated by the following findings: (i) identification by EPR of the hydroxyl radical production during the irradiation of an aqueous suspension of TiO2 NPs, (ii) impairment of a cytochrome c reduction by photo-excited TiO2 in the presence of dioxane, which affects the dielectric constant of the water, and (iii) change in the rate of TiO2-promoted cytochrome c reduction when water was replaced with D2O. The TiO2-promoted photo-reduction of cytochrome c was reverted by peroxides. Cytochrome c incorporated in the titanate nanotubes was also reversibly reduced under irradiation, as confirmed by EPR and UV-visible spectroscopy21974177426CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP475235/2010-0; 2011/01541-0Sem informação2008/04849-0; 2009/15558-1; 2011/01541-

Coexistence of antiferromagnetism and superconductivity in the Anderson lattice

We study the interplay between antiferromagnetism and superconductivity in a generalized infinite-$U$ Anderson lattice, where both superconductivity and antiferromagnetic order are introduced phenomenologically in mean field theory. In a certain regime, a quantum phase transition is found which is characterized by an abrupt expulsion of magnetic order by d-wave superconductivity, as externally applied pressure increases. This transition takes place when the d-wave superconducting critical temperature, $T_c$, intercepts the magnetic critical temperature, $T_m$, under increasing pressure. Calculations of the quasiparticle bands and density of states in the ordered phases are presented. We calculate the optical conductivity $\sigma(\omega)$ in the clean limit. It is shown that when the temperature drops below $T_m$ a double peak structure develops in $\sigma(\omega)$.Comment: 18 pages, 13 figure