marcio lima | UFPA - Federal University of Pará (original) (raw)

Papers by marcio lima

Revista Brasileira De Medicina Do Esporte, 2007

INTRODUÇÃO: A capacidade de variar a freqüência cardíaca representa importante papel fisiológico ... more INTRODUÇÃO: A capacidade de variar a freqüência cardíaca representa importante papel fisiológico na vida diária. As variações dos intervalos RR estão na dependência de moduladores biológicos, como o sistema nervoso autônomo. Essas variações constituem a variabilidade da freqüência cardíaca (VFC). MÉTODOS: 10 indivíduos atletas (Atl) e 10 sedentários (Sed) (20-35 anos) foram submetidos a eletrocardiografia digital, em repouso, antes, durante e após a manobra. Os valores de RR foram tratados (software Matlab 6.1), no domínio do tempo. RESULTADOS: Os grupos Sed e Atl apresentaram freqüência cardíaca média igual a 73,59bpm ± 2,5 e 51,01bpm ± 2,4, respectivamente. Quanto aos intervalos RR, o grupo de Sed apresentou média de 826,58ms ± 5,3 e o grupo Atl, 1.189,18 ± 6,9. O tempo de retorno simpático após a manobra 72 ± 12s (Sed) 37 ± 6s (Atl). O tempo de retorno parassimpático foi de 80 ± 11s (Sed) 40 ± 8s (Atl). O pNN50 foi de 10 ± 3,3 (Sed) e 42,10 ± 6,9 (Atl). O valor da variação dos RR acima da média de todo o sinal foi de 343 ± 40ms (Sed) e 175 ± 39ms (Atl). A variação abaixo da média de todo o sinal foi de 281 ± 27ms (Sed) e 425 ± 26ms (Atl). CONCLUSÕES: A análise da VFC associada à manobra de Valsalva pode representar uma ferramenta simples, mas importante, para possíveis inferências sobre aptidão física.

Physica Status Solidi-rapid Research Letters, 2007

Physica Status Solidi-rapid Research Letters, 2007

Physica Status Solidi B-basic Solid State Physics, 2007

In the present work we first report on a successful incorporation of single-walled carbon nanotub... more In the present work we first report on a successful incorporation of single-walled carbon nanotubes (SWCNTs) into silica matrix prepared using an inorganic sol–gel method. Through this route non-aqueous solvents are avoided and the stability of the carbon nanotubes suspensions is not affected. SWCNTs produced by Catalytic Chemical Vapor Deposition (CCVD) were dispersed in deionized water using an amphilic surfactant. As a precursor for the silica matrix an inexpensive silicic acid was used. By this route SWCNTs/silica composites were produced in the form of films and pellets. Microhardness measurements and electron microscopy suggest an important interaction between SWCNTs and the silica matrix what is important from the application point of view. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Materials Chemistry, 2007

Physica Status Solidi B-basic Solid State Physics, 2007

The production of Fe–Mo/MgO by Solution Combustion Synthesis (SCS) for use as catalysts in single... more The production of Fe–Mo/MgO by Solution Combustion Synthesis (SCS) for use as catalysts in single-walled carbon nanotube (SWNT) synthesis was evaluated. Glycine, urea, citric acid and polyethylene glycol 200 and 400 were tested as combustible agents (CA). Iron and magnesium nitrates and ammonium molybdate were used as catalyst precursors. Four different proportion ratios of combustible/metals salts were tested. The addition of CA greatly effects the morphology and density of the produced catalyst. Carbon nanotubes were evaluated using thermogravimetric analysis, Raman spectroscopy, scanning and transmission electron microscopes and by measuring the electrical conductivity of the carbon nanotubes dispersed in chloroform. The highest absolute carbon yield was obtained with the urea, but carbon nanotubes with higher G/D ratios were produced with glycine as the CA. However, the higher yield of carbon per volume of catalyst was produced using polyethylene glycol. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Materials Chemistry, 2008

Physica Status Solidi B-basic Solid State Physics, 2007

A new method for continuous production of carbon nanotube (CNT) catalysts is proposed in this stu... more A new method for continuous production of carbon nanotube (CNT) catalysts is proposed in this study. The method is a modification of the solution combustion synthesis and was called continuous solution combustion synthesis (CSCS). The method consists of the atomization of the modified combustion synthesis precursor solution in a pilot flame. A combustible, like ethanol, is added to the precursor solution to improve the evaporation of the solvent and the atomization. The ignition of the precursor solution is self-sufficient. A fine and porous powder is produced. The powder, collected through an electrostatic precipitator, has superior performance as a carbon nanotube catalyst. When comparing the production of Fe–Mo/MgO catalyst synthesized by the continuous method with the conventional route, it was observed that the amount of carbon nanotubes increased by 52 wt%, and the G/D ratio was also higher. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Electroanalytical Chemistry, 2004

Revista Brasileira De Otorrinolaringologia, 2008

Revista Brasileira De Otorrinolaringologia, 2007

Revista Brasileira De Medicina Do Esporte, 2007

INTRODUÇÃO: A capacidade de variar a freqüência cardíaca representa importante papel fisiológico ... more INTRODUÇÃO: A capacidade de variar a freqüência cardíaca representa importante papel fisiológico na vida diária. As variações dos intervalos RR estão na dependência de moduladores biológicos, como o sistema nervoso autônomo. Essas variações constituem a variabilidade da freqüência cardíaca (VFC). MÉTODOS: 10 indivíduos atletas (Atl) e 10 sedentários (Sed) (20-35 anos) foram submetidos a eletrocardiografia digital, em repouso, antes, durante e após a manobra. Os valores de RR foram tratados (software Matlab 6.1), no domínio do tempo. RESULTADOS: Os grupos Sed e Atl apresentaram freqüência cardíaca média igual a 73,59bpm ± 2,5 e 51,01bpm ± 2,4, respectivamente. Quanto aos intervalos RR, o grupo de Sed apresentou média de 826,58ms ± 5,3 e o grupo Atl, 1.189,18 ± 6,9. O tempo de retorno simpático após a manobra 72 ± 12s (Sed) 37 ± 6s (Atl). O tempo de retorno parassimpático foi de 80 ± 11s (Sed) 40 ± 8s (Atl). O pNN50 foi de 10 ± 3,3 (Sed) e 42,10 ± 6,9 (Atl). O valor da variação dos RR acima da média de todo o sinal foi de 343 ± 40ms (Sed) e 175 ± 39ms (Atl). A variação abaixo da média de todo o sinal foi de 281 ± 27ms (Sed) e 425 ± 26ms (Atl). CONCLUSÕES: A análise da VFC associada à manobra de Valsalva pode representar uma ferramenta simples, mas importante, para possíveis inferências sobre aptidão física.

Physica Status Solidi-rapid Research Letters, 2007

Physica Status Solidi-rapid Research Letters, 2007

Physica Status Solidi B-basic Solid State Physics, 2007

In the present work we first report on a successful incorporation of single-walled carbon nanotub... more In the present work we first report on a successful incorporation of single-walled carbon nanotubes (SWCNTs) into silica matrix prepared using an inorganic sol–gel method. Through this route non-aqueous solvents are avoided and the stability of the carbon nanotubes suspensions is not affected. SWCNTs produced by Catalytic Chemical Vapor Deposition (CCVD) were dispersed in deionized water using an amphilic surfactant. As a precursor for the silica matrix an inexpensive silicic acid was used. By this route SWCNTs/silica composites were produced in the form of films and pellets. Microhardness measurements and electron microscopy suggest an important interaction between SWCNTs and the silica matrix what is important from the application point of view. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Materials Chemistry, 2007

Physica Status Solidi B-basic Solid State Physics, 2007

The production of Fe–Mo/MgO by Solution Combustion Synthesis (SCS) for use as catalysts in single... more The production of Fe–Mo/MgO by Solution Combustion Synthesis (SCS) for use as catalysts in single-walled carbon nanotube (SWNT) synthesis was evaluated. Glycine, urea, citric acid and polyethylene glycol 200 and 400 were tested as combustible agents (CA). Iron and magnesium nitrates and ammonium molybdate were used as catalyst precursors. Four different proportion ratios of combustible/metals salts were tested. The addition of CA greatly effects the morphology and density of the produced catalyst. Carbon nanotubes were evaluated using thermogravimetric analysis, Raman spectroscopy, scanning and transmission electron microscopes and by measuring the electrical conductivity of the carbon nanotubes dispersed in chloroform. The highest absolute carbon yield was obtained with the urea, but carbon nanotubes with higher G/D ratios were produced with glycine as the CA. However, the higher yield of carbon per volume of catalyst was produced using polyethylene glycol. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Materials Chemistry, 2008

Physica Status Solidi B-basic Solid State Physics, 2007

A new method for continuous production of carbon nanotube (CNT) catalysts is proposed in this stu... more A new method for continuous production of carbon nanotube (CNT) catalysts is proposed in this study. The method is a modification of the solution combustion synthesis and was called continuous solution combustion synthesis (CSCS). The method consists of the atomization of the modified combustion synthesis precursor solution in a pilot flame. A combustible, like ethanol, is added to the precursor solution to improve the evaporation of the solvent and the atomization. The ignition of the precursor solution is self-sufficient. A fine and porous powder is produced. The powder, collected through an electrostatic precipitator, has superior performance as a carbon nanotube catalyst. When comparing the production of Fe–Mo/MgO catalyst synthesized by the continuous method with the conventional route, it was observed that the amount of carbon nanotubes increased by 52 wt%, and the G/D ratio was also higher. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal of Electroanalytical Chemistry, 2004

Revista Brasileira De Otorrinolaringologia, 2008

Revista Brasileira De Otorrinolaringologia, 2007