Alberto Cardoso Arruda - Academia.edu (original) (raw)
Papers by Alberto Cardoso Arruda
Revista da Sociedade Brasileira de Medicina Tropical, 2014
The aim of this study was to investigate the effects of Rosmarinus officinalis essential oil on g... more The aim of this study was to investigate the effects of Rosmarinus officinalis essential oil on germ tube formation by Candida albicans isolated from denture wearers. Ten C. albicans isolates recovered from denture wearers were tested using 10% fetal bovine serum with or without 4% R. officinalis essential oil. The essential oil from R. officinalis completely inhibited germ tube formation in the investigated C. albicans isolates. The results demonstrate that the essential oil of R. officinalis modulates C. albicans pathogenicity through its primary virulence factor (i.e., germ tube formation was suppressed).
The interest in studying magnetic properties of systems of mixed spin Ising has been grown in las... more The interest in studying magnetic properties of systems of mixed spin Ising has been grown in last years. This is due to such systems have less translational symmetry than their single-spin counterparts. This property is very important to study some type of ferrimagnetism, which are of current interest. One of the most interesting features of the ferrimagnetism is that they can exhibit compensation temperature. Spin systems mixed with spins in the two sublattices and with random anisotropies are not commonly studied. Monte Carlo method have been proven to be reliable and relatively simple technique to analyze mixed Ising model. In this work, we performed Monte Carlo simulations to study a mixed system ferrimagnetism on a square lattice. The model system consists of two interpenetrating sublattices with spins spin-1 and spin-3/2 in the presence of random anisotropies. The magnetic properties such as magnetization, susceptibility and Binder cumulant, were determined to obtain the crit...
DESCRIPTION Our contribution in this paper is to estimate the static critical exponents of the or... more DESCRIPTION Our contribution in this paper is to estimate the static critical exponents of the original Vicsek model as a function of density, velocity and orientation radius. We employ finite-size scaling arguments in order to obtain a complete picture in terms of each of these parameters.
Journal of Magnetism and Magnetic Materials
In this work we study the quantum spin-1/2 Heisenberg model in two dimensions, with a nearest-nei... more In this work we study the quantum spin-1/2 Heisenberg model in two dimensions, with a nearest-neighbor short-range antiferromagnetic exchange (J) and a long-range ferromagnetic dipole–dipole (Ed) coupling. Using the double-time Green's function method within the random phase approximation (RPA) we obtain the magnon dispersion relation as function of frustration parameter δ (δ being the ratio between exchange and dipolar interactions δ=J/Ed). We study the competition between long-range ferromagnetic dipole–dipole interaction and short-range antiferromagnetic exchange in stabilizing the magnetic long-range order in a two-dimensional system. We find that the ferromagnetic order is stable at small k up to critical value of frustration δc=0.04375. For frustration higher than the critical value (δ>δc) our magnetic system is disordered.
International Journal of Modern Physics C, 2012
A disordered binary Ising model, with only nearest-neighbor spin exchange interactions J > 0 on t... more A disordered binary Ising model, with only nearest-neighbor spin exchange interactions J > 0 on the square lattice, is studied through Monte Carlo simulations. The system consists of two di®erent particles with spin-1/2 and spin-1, randomly distributed on the lattice. We found the critical temperatures for several values of the concentration x of spin-1/2 particles, and also the corresponding critical exponents. Int. J. Mod. Phys. C Downloaded from www.worldscientific.com by UNIVERSIDADE FEDERAL DE MATO GROSSO on 07/23/12. For personal use only. 1240015-3 Monte Carlo Simulations of a Disordered Binary Ising Model Int. J. Mod. Phys. C Downloaded from www.worldscientific.com by UNIVERSIDADE FEDERAL DE MATO GROSSO on 07/23/12. For personal use only.
Revista Brasileira de Farmacognosia, 2006
RESUMO: O fracionamento do extrato hexânico do caule de um espécime de refl orestamento de Tecton... more RESUMO: O fracionamento do extrato hexânico do caule de um espécime de refl orestamento de Tectona grandis (Verbenaceae), através de procedimentos fi toquímicos clássicos, levou ao isolamento das naftoquinonas lapachol e desidro-α-lapachona e das antraquinonas tectoquinona e obtusifolina. As estruturas das substâncias foram caracterizadas através da análise de métodos espectrométricos de RMN. Este é o primeiro estudo fi toquímico de um espécime de refl orestamento de Tectona grandis, no Brasil, sendo o objetivo principal deste trabalho a comprovação da presença de tectoquinona em espécimes cultivados.
Phytochemistry, 1997
4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known pl... more 4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known plant constituents, were obtained from the trunk bark of Brosimum acutifolium. Their structures were elucidated by spectroscopic methods, including 2D NMR spectroscopic techniques. 7
Phytochemistry, 2000
4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known pl... more 4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known plant constituents, were obtained from the trunk bark of Brosimum acutifolium. Their structures were elucidated by spectroscopic methods, including 2D NMR spectroscopic techniques. 7
Química Nova, 2008
Recebido em 10/11/06; aceito em 20/9/07; publicado na web em 10/3/08 ALLELOPATHIC POTENTIAL OF CA... more Recebido em 10/11/06; aceito em 20/9/07; publicado na web em 10/3/08 ALLELOPATHIC POTENTIAL OF CATECHINS OF THE Tachigali myrmecophyla (Leguminosae). Two compounds, (+)-catechin and epicatechin, were isolated from leaves of T. myrmecophyla, using chromatographic techniques. The structural identification was carried out on the basis of 1 H and 13 C NMR spectral data and comparison with literature data. The compounds (+)-catechin and epicatechin were submitted to germination inhibition and radicle and hypocotyl growth assays. Results showed some significant activities confirming the initial hypothesis about allelopathic properties of that plant.
Physical Review B, 2013
ABSTRACT Based on a careful perusal of data, we revisit the longstanding issues of transport anis... more ABSTRACT Based on a careful perusal of data, we revisit the longstanding issues of transport anisotropy and incoherence-coherence crossovers in graphite. Using a realistic many-body approach, we unearth surprising but distinctive signatures of band-selective Kondoesque physics in graphite. The intricate interplay between local multiband Coulomb and effectively enhanced residual spin-orbit interactions comprehensively rationalizes these anomalies in terms of a manifestation of a multiband Kondo effect with a small Fermi liquid coherence scale.
Physica B: Condensed Matter, 2007
The phase diagram of an Ising metamagnet in a random magnetic field is studied by using mean-fiel... more The phase diagram of an Ising metamagnet in a random magnetic field is studied by using mean-field equations from Bogoliubov's variational principle. The trimodal probability distribution is applied. The phase diagram in the t2h plane presents continuous and firstorder transition lines. The phase transition lines, together with the critical points, were obtained for several random field values. r Arruda). are given in Section 2. In Section 3 we argue the technique of the expansion of landau for attainment of the line of second order and calculation of the tricritical point. The results are discussed in Section 4.
Physica B: Condensed Matter, 2007
... Monte Carlo studies of the cubic lattice mixed-bond Ising model. ... Keywords: Monte Carlo me... more ... Monte Carlo studies of the cubic lattice mixed-bond Ising model. ... Keywords: Monte Carlo method; Effective field theory; Ising model. ...
Physica A: Statistical Mechanics and its Applications, 2013
h i g h l i g h t s
Natural Product Research, 2013
Natural Product Letters, 1997
Page 1. Natural Product Lerters Volume 9, pp. 237-244 Reprints available directly from the publis... more Page 1. Natural Product Lerters Volume 9, pp. 237-244 Reprints available directly from the publishcr Photocopying permitted by license only 0 1997 OPA (Overseas Publishers Association) Amsterdam BV Published in The Netherlands ...
Journal of the Brazilian Chemical Society, 2001
Journal of the Brazilian Chemical Society, 2009
Derris urucu é uma planta da Amazônia com propriedades inseticida e ictiotóxica. Estudos com esta... more Derris urucu é uma planta da Amazônia com propriedades inseticida e ictiotóxica. Estudos com esta espécie reportam a presença de flavonóides, principalmente rotenóides, bem como de estilbenos. A partir do extrato etanólico das folhas de Derris urucu (Leguminosae), três novos diidroflavonóides, denominados urucuol A (1), B (2) e C (3) e o diidroflavonol isotirumalina (4), foram isolados e identificados. As estruturas destes compostos foram elucidadas por uma extensiva análise espectroscópica de RMN uni e bidimensional, UV, IV e dados de EM, além de comparação com dados da literatura. Os compostos isolados (1-4) foram avaliados quanto ao seu potencial sequestrador do radical DPPH • e apresentaram baixo poder antioxidante quando comparados ao antioxidante comercial trans-resveratrol.
Journal of the Brazilian Chemical Society, 2013
Das folhas de Vatairea guianensis Aublé foram isoladas quatro isoflavonas identificadas como, 5,3... more Das folhas de Vatairea guianensis Aublé foram isoladas quatro isoflavonas identificadas como, 5,3',-diidroxi-4'-metoxi-2",2"-dimetilpirano-(5",6":8,7)-isoflavona (1), 5,7-diidroxi-3',4 'metilenodioxi-8-prenil-isoflavona (2) , juntamente com cinco triterpenos identificados em mistura de lupeol, α-amirina, β-amirina, germanicol e ácido betulínico. As substâncias 1-3 são novos produtos naturais, porém 1 e 2 já foram citados como produtos de síntese. No entanto, todas essas substâncias são relatadas pela primeira vez para essa espécie. Suas estruturas químicas foram elucidadas com base nos seus dados de ressonância magnética nuclear (RMN) 1D e 2D e por espectrometria de massas de alta resolução. O extrato etanólico das folhas e os compostos 1-3 foram avaliados quanto ao seu potencial sequestrador do radical DPPH• (2,2-difenil-1-picril-hidrazila) e os resultados mostram que o extrato apresentou alta atividade (CI 50 = 6,2 ± 0,4 µg mL -1 ), enquanto as substâncias testadas apresentaram baixo poder antioxidante (CI 50 ≥ 29,5 ± 2,5 µg mL -1 ) quando comparadas com TROLOX (CI 50 = 4,5 ± 0,4 µg mL -1 ).
Revista da Sociedade Brasileira de Medicina Tropical, 2014
The aim of this study was to investigate the effects of Rosmarinus officinalis essential oil on g... more The aim of this study was to investigate the effects of Rosmarinus officinalis essential oil on germ tube formation by Candida albicans isolated from denture wearers. Ten C. albicans isolates recovered from denture wearers were tested using 10% fetal bovine serum with or without 4% R. officinalis essential oil. The essential oil from R. officinalis completely inhibited germ tube formation in the investigated C. albicans isolates. The results demonstrate that the essential oil of R. officinalis modulates C. albicans pathogenicity through its primary virulence factor (i.e., germ tube formation was suppressed).
The interest in studying magnetic properties of systems of mixed spin Ising has been grown in las... more The interest in studying magnetic properties of systems of mixed spin Ising has been grown in last years. This is due to such systems have less translational symmetry than their single-spin counterparts. This property is very important to study some type of ferrimagnetism, which are of current interest. One of the most interesting features of the ferrimagnetism is that they can exhibit compensation temperature. Spin systems mixed with spins in the two sublattices and with random anisotropies are not commonly studied. Monte Carlo method have been proven to be reliable and relatively simple technique to analyze mixed Ising model. In this work, we performed Monte Carlo simulations to study a mixed system ferrimagnetism on a square lattice. The model system consists of two interpenetrating sublattices with spins spin-1 and spin-3/2 in the presence of random anisotropies. The magnetic properties such as magnetization, susceptibility and Binder cumulant, were determined to obtain the crit...
DESCRIPTION Our contribution in this paper is to estimate the static critical exponents of the or... more DESCRIPTION Our contribution in this paper is to estimate the static critical exponents of the original Vicsek model as a function of density, velocity and orientation radius. We employ finite-size scaling arguments in order to obtain a complete picture in terms of each of these parameters.
Journal of Magnetism and Magnetic Materials
In this work we study the quantum spin-1/2 Heisenberg model in two dimensions, with a nearest-nei... more In this work we study the quantum spin-1/2 Heisenberg model in two dimensions, with a nearest-neighbor short-range antiferromagnetic exchange (J) and a long-range ferromagnetic dipole–dipole (Ed) coupling. Using the double-time Green's function method within the random phase approximation (RPA) we obtain the magnon dispersion relation as function of frustration parameter δ (δ being the ratio between exchange and dipolar interactions δ=J/Ed). We study the competition between long-range ferromagnetic dipole–dipole interaction and short-range antiferromagnetic exchange in stabilizing the magnetic long-range order in a two-dimensional system. We find that the ferromagnetic order is stable at small k up to critical value of frustration δc=0.04375. For frustration higher than the critical value (δ>δc) our magnetic system is disordered.
International Journal of Modern Physics C, 2012
A disordered binary Ising model, with only nearest-neighbor spin exchange interactions J > 0 on t... more A disordered binary Ising model, with only nearest-neighbor spin exchange interactions J > 0 on the square lattice, is studied through Monte Carlo simulations. The system consists of two di®erent particles with spin-1/2 and spin-1, randomly distributed on the lattice. We found the critical temperatures for several values of the concentration x of spin-1/2 particles, and also the corresponding critical exponents. Int. J. Mod. Phys. C Downloaded from www.worldscientific.com by UNIVERSIDADE FEDERAL DE MATO GROSSO on 07/23/12. For personal use only. 1240015-3 Monte Carlo Simulations of a Disordered Binary Ising Model Int. J. Mod. Phys. C Downloaded from www.worldscientific.com by UNIVERSIDADE FEDERAL DE MATO GROSSO on 07/23/12. For personal use only.
Revista Brasileira de Farmacognosia, 2006
RESUMO: O fracionamento do extrato hexânico do caule de um espécime de refl orestamento de Tecton... more RESUMO: O fracionamento do extrato hexânico do caule de um espécime de refl orestamento de Tectona grandis (Verbenaceae), através de procedimentos fi toquímicos clássicos, levou ao isolamento das naftoquinonas lapachol e desidro-α-lapachona e das antraquinonas tectoquinona e obtusifolina. As estruturas das substâncias foram caracterizadas através da análise de métodos espectrométricos de RMN. Este é o primeiro estudo fi toquímico de um espécime de refl orestamento de Tectona grandis, no Brasil, sendo o objetivo principal deste trabalho a comprovação da presença de tectoquinona em espécimes cultivados.
Phytochemistry, 1997
4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known pl... more 4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known plant constituents, were obtained from the trunk bark of Brosimum acutifolium. Their structures were elucidated by spectroscopic methods, including 2D NMR spectroscopic techniques. 7
Phytochemistry, 2000
4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known pl... more 4 '- dihydrofuran]¯avan and 4 ',7-dihydroxy-8-(3,3-dimethylallyl)¯avan, together with 10 known plant constituents, were obtained from the trunk bark of Brosimum acutifolium. Their structures were elucidated by spectroscopic methods, including 2D NMR spectroscopic techniques. 7
Química Nova, 2008
Recebido em 10/11/06; aceito em 20/9/07; publicado na web em 10/3/08 ALLELOPATHIC POTENTIAL OF CA... more Recebido em 10/11/06; aceito em 20/9/07; publicado na web em 10/3/08 ALLELOPATHIC POTENTIAL OF CATECHINS OF THE Tachigali myrmecophyla (Leguminosae). Two compounds, (+)-catechin and epicatechin, were isolated from leaves of T. myrmecophyla, using chromatographic techniques. The structural identification was carried out on the basis of 1 H and 13 C NMR spectral data and comparison with literature data. The compounds (+)-catechin and epicatechin were submitted to germination inhibition and radicle and hypocotyl growth assays. Results showed some significant activities confirming the initial hypothesis about allelopathic properties of that plant.
Physical Review B, 2013
ABSTRACT Based on a careful perusal of data, we revisit the longstanding issues of transport anis... more ABSTRACT Based on a careful perusal of data, we revisit the longstanding issues of transport anisotropy and incoherence-coherence crossovers in graphite. Using a realistic many-body approach, we unearth surprising but distinctive signatures of band-selective Kondoesque physics in graphite. The intricate interplay between local multiband Coulomb and effectively enhanced residual spin-orbit interactions comprehensively rationalizes these anomalies in terms of a manifestation of a multiband Kondo effect with a small Fermi liquid coherence scale.
Physica B: Condensed Matter, 2007
The phase diagram of an Ising metamagnet in a random magnetic field is studied by using mean-fiel... more The phase diagram of an Ising metamagnet in a random magnetic field is studied by using mean-field equations from Bogoliubov's variational principle. The trimodal probability distribution is applied. The phase diagram in the t2h plane presents continuous and firstorder transition lines. The phase transition lines, together with the critical points, were obtained for several random field values. r Arruda). are given in Section 2. In Section 3 we argue the technique of the expansion of landau for attainment of the line of second order and calculation of the tricritical point. The results are discussed in Section 4.
Physica B: Condensed Matter, 2007
... Monte Carlo studies of the cubic lattice mixed-bond Ising model. ... Keywords: Monte Carlo me... more ... Monte Carlo studies of the cubic lattice mixed-bond Ising model. ... Keywords: Monte Carlo method; Effective field theory; Ising model. ...
Physica A: Statistical Mechanics and its Applications, 2013
h i g h l i g h t s
Natural Product Research, 2013
Natural Product Letters, 1997
Page 1. Natural Product Lerters Volume 9, pp. 237-244 Reprints available directly from the publis... more Page 1. Natural Product Lerters Volume 9, pp. 237-244 Reprints available directly from the publishcr Photocopying permitted by license only 0 1997 OPA (Overseas Publishers Association) Amsterdam BV Published in The Netherlands ...
Journal of the Brazilian Chemical Society, 2001
Journal of the Brazilian Chemical Society, 2009
Derris urucu é uma planta da Amazônia com propriedades inseticida e ictiotóxica. Estudos com esta... more Derris urucu é uma planta da Amazônia com propriedades inseticida e ictiotóxica. Estudos com esta espécie reportam a presença de flavonóides, principalmente rotenóides, bem como de estilbenos. A partir do extrato etanólico das folhas de Derris urucu (Leguminosae), três novos diidroflavonóides, denominados urucuol A (1), B (2) e C (3) e o diidroflavonol isotirumalina (4), foram isolados e identificados. As estruturas destes compostos foram elucidadas por uma extensiva análise espectroscópica de RMN uni e bidimensional, UV, IV e dados de EM, além de comparação com dados da literatura. Os compostos isolados (1-4) foram avaliados quanto ao seu potencial sequestrador do radical DPPH • e apresentaram baixo poder antioxidante quando comparados ao antioxidante comercial trans-resveratrol.
Journal of the Brazilian Chemical Society, 2013
Das folhas de Vatairea guianensis Aublé foram isoladas quatro isoflavonas identificadas como, 5,3... more Das folhas de Vatairea guianensis Aublé foram isoladas quatro isoflavonas identificadas como, 5,3',-diidroxi-4'-metoxi-2",2"-dimetilpirano-(5",6":8,7)-isoflavona (1), 5,7-diidroxi-3',4 'metilenodioxi-8-prenil-isoflavona (2) , juntamente com cinco triterpenos identificados em mistura de lupeol, α-amirina, β-amirina, germanicol e ácido betulínico. As substâncias 1-3 são novos produtos naturais, porém 1 e 2 já foram citados como produtos de síntese. No entanto, todas essas substâncias são relatadas pela primeira vez para essa espécie. Suas estruturas químicas foram elucidadas com base nos seus dados de ressonância magnética nuclear (RMN) 1D e 2D e por espectrometria de massas de alta resolução. O extrato etanólico das folhas e os compostos 1-3 foram avaliados quanto ao seu potencial sequestrador do radical DPPH• (2,2-difenil-1-picril-hidrazila) e os resultados mostram que o extrato apresentou alta atividade (CI 50 = 6,2 ± 0,4 µg mL -1 ), enquanto as substâncias testadas apresentaram baixo poder antioxidante (CI 50 ≥ 29,5 ± 2,5 µg mL -1 ) quando comparadas com TROLOX (CI 50 = 4,5 ± 0,4 µg mL -1 ).