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Carvalho-Santos V.L.,Federal University of Minas Gerais | Carvalho-Santos V.L.,Instituto Federal Of Educaao | Moura-Melo W.A.,Federal University of Minas Gerais | Pereira A.R.,Federal University of Minas Gerais | Pereira A.R.,Max Planck Institute for the Physics of Complex Systems
Journal of Applied Physics | Year: 2010

The energetics associated to the ferromagnetic, vortex, and onionlike magnetization configurations are explicitly computed in the toroidal geometry. The analysis reveals that the vortex appears to be the most prominent of such states, minimizing total energy in every torus with internal radius r≳10 nm, or even in smaller ones provided that R/ℓex≳ 1.5 (R is the torus external radius and ex is the exchange length). This possibility of having very small nanomagnets comprising a vortex-type state, might have importance in higher density binary logic and/or storage and in novel mechanisms for cancer therapy applications. © 2010 American Institute of Physics. Source


Lira L.F.B.,Federal University of Pernambuco | Lira L.F.B.,Instituto Federal Of Educaao | Dos Santos D.C.M.B.,Federal University of Bahia | Guida M.A.B.,Federal University of Bahia | And 4 more authors.
Fuel | Year: 2011

In this work, a method for the determination of phosphorus in biodiesel (B100) using flow injection analysis with spectrophotometric detection (FIA-SD) is described. Samples were digested using an acid mixture in a heating block. The phosphorus concentrations obtained by the (FIA-SD) method were similar to those obtained by the official method. Recovery tests show results between 98.6% and 101.0% for biodiesel produced from sunflower and between 102.1% and 113.5% for biodiesel produced from castor and soybeans. The limits of detection (LOD) and quantification (LOQ) obtained using the FIA system were 0.14 mg L -1 and 0.46 mg L-1, respectively. © 2011 Elsevier Ltd. All rights reserved. Source


Martins M.A.P.,Federal University of Santa Maria | Rossatto M.,Instituto Federal Of Educaao | Prola L.D.T.,Federal University of Santa Maria | Pizzuti L.,Federal University of Grande Dourados | And 5 more authors.
Ultrasonics Sonochemistry | Year: 2012

The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R 3C(O)CHC(R1)OMe, where R3 = CF3, CCl3, CO2Et and R1 = Me, Et, Pr, Bu, i-Pent, CH2CH2CO2Me] with propargyl amines [R 2NHCH2CCH, where R2 = Pr, PhCH2] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%). © 2011 Elsevier B.V. All rights reserved. Source


Melo D.S.,Federal University of Minas Gerais | Melo D.S.,Instituto Federal Of Educaao | Pereira-Junior S.S.,Federal University of Minas Gerais | Dos Santos E.N.,Federal University of Minas Gerais
Applied Catalysis A: General | Year: 2012

The hydroaminomethylation (hydroformylation/reductive amination) of the naturally occurring monoterpenes, i.e., limonene, camphene, and β-pinene, was studied having as condensation counterparts the amines di-n-butylamine, morpholine or n-butylamine. Moderate to good yields (75-94%) were obtained employing [Rh(cod)(μ-OMe)]2 as pre-catalyst in the presence or not of triphenylphosphine or tribenzylphosphine as ancillaries in toluene, at 100 °C and 60 bar of an equimolar mixture of carbon monoxide and hydrogen. Some of the hydroaminomethylation products derived from limonene have biological activity and the products derived from camphene and β-pinene are new. © 2011 Elsevier B.V. All rights reserved. Source


Morte E.S.D.B.,Federal University of Bahia | Morte E.S.D.B.,Instituto Federal Of Educaao | Barbosa I.D.S.,Federal University of Bahia | Santos E.C.,Federal University of Bahia | And 2 more authors.
Food Chemistry | Year: 2012

In this study it was evaluated the variation of tin concentration in function of storage time in canned food samples by using an axial view inductively coupled plasma optical emission spectrometry (AX ICP OES). The effect of various parameters of the ICP OES, such as analytical lines, sample introduction systems and interferences were investigated. Eight emission lines for tin were tested, but only 283.998 nm line was found to be robust enough with respect to interferences and sensitivity, presenting a limit of quantification of 0.094 mg kg-1. A concentric nebuliser combined with a cyclonic chamber has shown better sensitivity than a V-groove nebuliser. Tin was determined in canned tomato sauce stored at room temperature (20.0 ± 1.8 °C) for 0, 30, 60, 90, 120 and 150 days. After 150 days, tin contents increased in the 43-91% range. Despite an increase of almost 100% for one sample, tin contents are well below the maximum level allowed by Agência Nacional de Vigilância Sanitária (ANVISA) regulation of 250 mg kg-1. © 2011 Elsevier Ltd. All rights reserved. Source

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