6 resultados para Flash! Vidas

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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Boiling points (T-B) of acyclic alkynes are predicted from their boiling point numbers (Y-BP) with the relationship T-B(K) = -16.802Y(BP)(2/3) + 337.377Y(BP)(1/3) - 437.883. In turn, Y-BP values are calculated from structure using the equation Y-BP = 1.726 + A(i) + 2.779C + 1.716M(3) + 1.564M + 4.204E(3) + 3.905E + 5.007P - 0.329D + 0.241G + 0.479V + 0.967T + 0.574S. Here A(i) depends on the substitution pattern of the alkyne and the remainder of the equation is the same as that reported earlier for alkanes. For a data set consisting of 76 acyclic alkynes, the correlation of predicted and literature T-B values had an average absolute deviation of 1.46 K, and the R-2 of the correlation was 0.999. In addition, the calculated Y-BP values can be used to predict the flash points of alkynes.

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Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. However, it is difficult to sinter it to high density at a reasonable temperature. Moreover, it presents a high grain boundary resistivity at intermediate temperatures. Flash grain welding was applied to compacted samples, starting from a temperature of 910 degrees C and applying, for a short time, an ac electric polarization of 40 V, 1000 Hz. At that frequency, the resulting current flows through the grain boundaries promoting a welding via a local Joule heating. A large decrease of the grain boundary resistivity was observed by impedance spectroscopy. Scanning electron microscopy observations of polished and etched surfaces revealed highly sintered regions. Attempts were also made to combine flash grain welding with conventional sintering. (C) 2012 Elsevier Ltd. All rights reserved.

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Vidas secas (1938) é o último romance de Graciliano Ramos, escrito depois da experiência do autor nos cárceres do Estado Novo, experiência por ele mesmo julgada essencial para a elaboração do livro. O artigo começa pela discussão acerca do sentido das exigências éticas e estéticas do romancista. Procura descrever a organização do romance a partir da combinação de contos, originalmente autônomos. Examina em seguida o episódio "Baleia", onde se discute o problema da domesticação e da educação. Termina com a análise da tensão entre a fala da utopia e o realismo crítico.

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O texto analisa a trama dos sonhos, dos desejos e da realidade de uma família de retirantes nordestinos que, tratados como bichos, sonham um dia fazer valer sua condição de homens. Embora atravessada pela dúvida e pela incerteza impostas pelos obstáculos de uma realidade desumana, a narrativa fala também da persistência de sonhos e desejos que não deixa morrer a esperança utópica dos personagens e do próprio autor, ainda que vaga, do advento de um mundo humanizado.

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Boiling points (T B) of acyclic alkynes are predicted from their boiling point numbers (Y BP) with the relationship T B(K) = -16.802Y BP2/3 + 337.377Y BP1/3 - 437.883. In turn, Y BP values are calculated from structure using the equation Y BP = 1.726 + Ai + 2.779C + 1.716M3 + 1.564M + 4.204E3 + 3.905E + 5.007P - 0.329D + 0.241G + 0.479V + 0.967T + 0.574S. Here Ai depends on the substitution pattern of the alkyne and the remainder of the equation is the same as that reported earlier for alkanes. For a data set consisting of 76 acyclic alkynes, the correlation of predicted and literature T B values had an average absolute deviation of 1.46 K, and the R² of the correlation was 0.999. In addition, the calculated Y BP values can be used to predict the flash points of alkynes.