Development of an electrochemical sensor for determination of dissolved oxygen by nickel-salen polymeric film modified electrode

An amperometric oxygen sensor based on a polymeric nickel-salen (salen = N,N'-ethylene bis(salicylideneiminato)) film coated platinum electrode was developed. The sensor was constructed by electropolymerization of nickel-salen complex at platinum electrode in acetonitrile/tetrabutylammonium perchlorate by cyclic voltammetry. The voltammetric behavior of the sensor was investigated in 0.5 mol L-1 KCl solution in the absence and presence of molecular oxygen. Thus, with the addition of oxygen to the solution, the increase of cathodic peak current (at -0.25 V vs. saturated calomel electrode (SCE)) of the modified electrode was observed. This result shows that the nickel-salen film on electrode surface promotes the reduction of oxygen. The reaction can be brought about electrochemically, where the nickel(II) complex is first reduced to a nickel(I) complex at the electrode surface. The nickel(I) complex then undergoes a catalytic oxidation by the molecular oxygen in solution back to the nickel(II) complex, which can then be electrochemically re-reduced to produce an enhancement of the cathodic current. The Tafel plot analyses have been used to elucidate the kinetics and mechanism of the oxygen reduction. A plot of the cathodic current vs. the dissolved oxygen concentration for chronoamperometry (fixed potential = -0.25 V vs. SCE) at the sensor was linear in the 3.95-9.20 mg L-1 concentration range and the concentration limit was 0.17 mg L-1 O-2. The proposed electrode is useful for the quality control and routine analysis of dissolved oxygen in commercial samples and environmental water. The results obtained for the levels of dissolved oxygen are in agreement with the results obtained with a commercial O-2 sensor. (C) 2012 Elsevier B.V. All rights reserved.

O equilíbrio econômico-financeiro dos contratos de concessão de rodovias federais e estaduais sob a égide da Lei 8.987/95

Pós-graduação em Direito - FCHS

Titanium in Dentistry: Historical development, state of the art and future perspectives

Titanium is a metallic element known by several attractive characteristics, such as biocompatibility, excellent corrosion resistance and high mechanical resistance. It is widely used in Dentistry, with high success rates, providing a favorable biological response when in contact with live tissues. Therefore, the objective of this study was to describe the different uses of titanium in Dentistry, reviewing its historical development and discoursing about its state of art and future perspective of its utilization. A search in the MEDLINE/PubMed database was performed using the terms 'titanium', 'dentistry' and 'implants'. The title and abstract of articles were read, and after this first screening 20 articles were selected and their full-texts were downloaded. Additional text books and manual search of reference lists within selected articles were included. Correlated literature showed that titanium is the most used metal in Implantology for manufacturing osseointegrated implants and their systems, with a totally consolidated utilization. Moreover, titanium can be also employed in prosthodontics to obtain frameworks. However, problems related to its machining, casting, welding and ceramic application for dental prosthesis are still limiting its use. In Endodontics, titanium has been used in association to nickel for manufacturing rotatory instruments, providing a higher resistance to deformation. However, although the different possibilities of using titanium in modern Dentistry, its use for prostheses frameworks still needs technological improvements in order to surpass its limitations. © 2012 Indian Prosthodontic Society.

Maracatu em São Paulo: expressões artísticas e culturais de Lokan Oba - Maracatu Nação

Pós-graduação em Artes - IA

Previsão de cargas elétricas através de uma Rede Neural Híbrida Back-ART Fuzzy

Pós-graduação em Engenharia Elétrica - FEIS

A tradição legitimada: um estudo sobre o suplemento literário sabático, do jornal O Estado de S. Paulo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Boosted objects and jet substructure at the LHC. Report of BOOST2012, held at IFIC Valencia, 23rd-27th of July 2012

This report of the BOOST2012 workshop presents the results of four working groups that studied key aspects of jet substructure. We discuss the potential of first-principle QCD calculations to yield a precise description of the substructure of jets and study the accuracy of state-of-the-art Monte Carlo tools. Limitations of the experiments' ability to resolve substructure are evaluated, with a focus on the impact of additional (pile-up) proton proton collisions on jet substructure performance in future LHC operating scenarios. A final section summarizes the lessons learnt from jet substructure analyses in searches for new physics in the production of boosted top quarks.

Flores do abismo, imagens do inconsciente [2012]

Presented in a rehearsal form, this article aims to bring out a historical discussion about the relationship between art-madness in Brazil. Result of a research that had as object the critical fortune written on the first exhibit of the Museum of Images of the Unconscious, this work aims to connect two little closer fields: art criticism and mental health, especially since Mário Pedrosa’s work. It was possible to ascertain, throughout the investigation, that there was a position taken by art critics at that time (the 1940s), that position is basically divided into two, briefly explored here: those who encouraged the exhibits, and thereby attested the artistic value of the work produced in the studio of Pedro II Psychiatric Center (where it was founded the Museum); and those who decried the artistic character of "unconscious images", as would be known the works that were produced there. Thus, we can say that, indeed, the virgin art – so entitled by Pedrosa – functioned as a kind of sting to the renewal of our health practices, but mainly influenced the completion of a cycle of modernism in our country.

O estado da arte sobre as temáticas sexualidade, educação sexual e gênero nos encontros nacionais de didática e prática de ensino - ENDIPE (1996-2012)

Pós-graduação em Educação Escolar - FCLAR