Bis-(µ2-oxo)-tetrakis{[1-feniltriazeno-1,3-diil)-2-(feniltriazenil)benzeno cobre(II) é um complexo tetranuclear que apresenta quatro íons Cu(II) coordenados por quatro ligantes 1,2-bis(feniltriazeno)benzeno em ponte, com uma cadeia diazoamínica desprotonada, e dois ligantes O2-. O complexo apresenta um processo de redução por dois elétrons a E1/2 = -0,95 V vs Fc+/Fc. Voltametria cíclica e espectroeletroquímica demonstraram um processo reversível. Quando imobilizado em eletrodo de pasta de carbono, o complexo eletrocatalisa a redução de O2 dissolvido em solução aquosa a -0,3 V vs SCE. A corrente obtida apresenta linearidade com a concentração de O2.

Bis-(µ2-oxo)-tetrakis{[1-feniltriazene-1,3-diil)-2-(phenyltriazenil)benzene copper(II) is a tetranuclear complex which shows four Cu(II) ions coordinated by four 1,2-bis(phenyltriazene)benzene bridged ligands, with one diazoaminic deprotonated chain, and two O2- ligands. The complex reduces at E1/2 = -0.95 V vs Fc+/Fc, a two electrons process. Cyclic voltammetric and spectroelectrochemical studies showed a reversible process. When immobilized on carbon paste electrode, the complex electrocatalyses the reduction of O2 dissolved on aqueous solution at -0.3 V vs SCE potential. The obtained current shows linearity with O2 concentration.

This paper presents an experimental study aiming to identify the means to minimize the reduction of the overall performance of a gasoline engine when employing the Exhaust-Gas Recirculation (EGR) technique that reduces NOx emissions. The increase of the compression ratio and turbocharging was evaluated as a mean to recover the original performance. The formation of pollutants and the engine performance were verified at full and partial loads. The results show that the combination of exhaust gas recirculation with turbocharger or through an increase of the compression ratio enhance the relation between the engine performance and the emission of NO. However, the turbocharger seemed to be more sensitive to the negative effects of the EGR technology.

O estudo químico das partes aéreas do extrato hexânico de Lychnophora pinaster forneceu, além de outras substâncias, o isômero E do ácido licnofórico, um sesquiterpeno anteriormente isolado de L. affinis.

The investigation of the hexane extract from aerial parts of Lychnophora pinaster provided, besides others substances, the E-isomer of lychnophoric acid, a sesquiterpene derivative previously isolated from L. affinis.

Ammonium salt derivatives of natural allylphenols were synthesized with the purpose of obtaining potential peripheral analgesics. These drugs, by virtue of their physicochemical properties, would not be able to cross the blood brain barrier. Their inability to enter into the central nervous system (CNS) should prevent several adverse effects observed with classical opiate analgesics (Ferreira et al., 1984). Eugenol (1) O-methyleugenol (5) and safrole (9) were submitted to nitration, reduction and permethylation, leading to the ammonium salts 4, 8 and 12. Another strategy applied to eugenol (1), consisting in its conversion to a glycidic ether (13), opening the epoxide ring with secondary amines and methylation, led to the ammonium salts 16 and 17. All these ammonium salts showed significant peripheral analgesic action, in modified version of the Randall-Sellito test (Ferreira et al. 1978), at non-lethal doses. The ammonium salt 8 showed an activity comparable to that of methylnalorphinium, the prototype of an ideal peripheral analgesic (Ferreira et al., 1984).