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Search Results: 1 - 10 of 220017 matches for " Cleison C. Lobato "
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Evaluation of Quantum Chemical Methods and Basis Sets Applied in the Molecular Modeling of Artemisinin  [PDF]
Cleydson B. R. dos Santos, Cleison C. Lobato, Josinete B. Vieira, Davi S. B. Brasil, Alaan U. Brito, Williams J. C. Macêdo, José Carlos T. Carvalho, José C. Pinheiro
Computational Molecular Bioscience (CMB) , 2013, DOI: 10.4236/cmb.2013.33009
Abstract: In this paper, we evaluate semiempirical methods (AM1, PM3, and ZINDO), HF and DFT (B3LYP) in different basis sets to determine which method best describes the sign and magnitude of the geometrical parameters of artemisinin in the region of the endoperoxide ring compared to crystallographic data. We also classify these methods using statistical analysis. The results of PCA were based on three main components, explaining 98.0539% of the total variance, for the geometrical parameters C3O13, O1O2C3, O13C12C12a, and O2C3O13C12. The DFT method (B3LYP) corresponded well with the experimental data in the hierarchical cluster analysis (HCA). The experimental and theoretical angles were analyzed by simple linear regression, and statistical parameters (correlation coefficients, significance, and predictability) were evaluated to determine the accuracy of the calculations. The statistical analysis exhibited a good correlation and high predictive power for the DFT (B3LYP) method in the 6-31G** basis set.
Application of Hartree-Fock Method for Modeling of Bioactive Molecules Using SAR and QSPR  [PDF]
Cleydson B. R. Santos, Cleison C. Lobato, Francinaldo S. Braga, Sílvia S. S. Morais, Cesar F. Santos, Caio P. Fernandes, Davi S. B. Brasil, Lorane I. S. Hage-Melim, Williams J. C. Macêdo, José C. T. Carvalho
Computational Molecular Bioscience (CMB) , 2014, DOI: 10.4236/cmb.2014.41001
Abstract:
The central importance of quantum chemistry is to obtain solutions of the Schr?dinger equation for the accurate determination of the properties of atomic and molecular systems that occurred from the calculation of wave functions accurate for many diatomic and polyatomic molecules, using Self Consistent Field method (SCF). The application of quantum chemical methods in the study and planning of bioactive compounds has become a common practice nowadays. From the point of view of planning it is important to note, when it comes to the use of molecular modeling, a collective term that refers to methods and theoretical modeling and computational techniques to mimic the behavior of molecules, not intend to reach a bioactive molecule simply through the use of computer programs. The choice of method for energy minimization depends on factors related to the size of the molecule, parameters of availability, stored data and computational resources. Molecular models generated by the computer are the result of mathematical equations that estimate the positions and properties of the electrons and nuclei, the calculations exploit experimentally, the characteristics of a structure, providing a new perspective on the molecule. In this work we show that studies of Highest Occupied Molecular Orbital Energy (HOMO), Low Unoccupied Molecular Orbital Energy (LUMO) and Map of molecular electrostatic potential (MEP) using Hatree-Fock method with different basis sets (HF/3-21G*, HF/3-21G**, HF/6-31G, HF/6-31G*, HF/6-31G** and HF/6-311G), that are of great importance in modern chemistry, biochemistry, molecular biology, and other fields of knowledge of health sciences. In order to obtain a significant correlation, it is essential that the descriptors are used appropriately. Thus, the quantum chemical calculations are an attractive source of new molecular descriptors that can, in principle, express all the geometrical and electronic properties of molecules and their interactions with biological receptor.
A SAR and QSAR Study of New Artemisinin Compounds with Antimalarial Activity
Cleydson Breno R. Santos,Josinete B. Vieira,Cleison C. Lobato,Lorane I. S. Hage-Melim,Raimundo N. P. Souto,Clarissa S. Lima,Elizabeth V. M. Costa,Davi S. B. Brasil,Williams Jorge C. Macêdo,José Carlos T. Carvalho
Molecules , 2014, DOI: 10.3390/molecules19010367
Abstract: The Hartree-Fock method and the 6-31G** basis set were employed to calculate the molecular properties of artemisinin and 20 derivatives with antimalarial activity. Maps of molecular electrostatic potential (MEPs) and molecular docking were used to investigate the interaction between ligands and the receptor (heme). Principal component analysis and hierarchical cluster analysis were employed to select the most important descriptors related to activity. The correlation between biological activity and molecular properties was obtained using the partial least squares and principal component regression methods. The regression PLS and PCR models built in this study were also used to predict the antimalarial activity of 30 new artemisinin compounds with unknown activity. The models obtained showed not only statistical significance but also predictive ability. The significant molecular descriptors related to the compounds with antimalarial activity were the hydration energy (HE), the charge on the O11 oxygen atom (QO11), the torsion angle O1-O2-Fe-N2 (D2) and the maximum rate of R/Sanderson Electronegativity (RTe +). These variables led to a physical and structural explanation of the molecular properties that should be selected for when designing new ligands to be used as antimalarial agents.
Aortic Disease in the Young: Genetic Aneurysm Syndromes, Connective Tissue Disorders, and Familial Aortic Aneurysms and Dissections
Marcelo Cury,Fernanda Zeidan,Armando C. Lobato
International Journal of Vascular Medicine , 2013, DOI: 10.1155/2013/267215
Abstract:
Aortic Disease in the Young: Genetic Aneurysm Syndromes, Connective Tissue Disorders, and Familial Aortic Aneurysms and Dissections
Marcelo Cury,Fernanda Zeidan,Armando C. Lobato
International Journal of Vascular Medicine , 2013, DOI: 10.1155/2013/267215
Abstract: There are many genetic syndromes associated with the aortic aneurysmal disease which include Marfan syndrome (MFS), Ehlers-Danlos syndrome (EDS), Loeys-Dietz syndrome (LDS), familial thoracic aortic aneurysms and dissections (TAAD), bicuspid aortic valve disease (BAV), and autosomal dominant polycystic kidney disease (ADPKD). In the absence of familial history and other clinical findings, the proportion of thoracic and abdominal aortic aneurysms and dissections resulting from a genetic predisposition is still unknown. In this study, we propose the review of the current genetic knowledge in the aortic disease, observing, in the results that the causative genes and molecular pathways involved in the pathophysiology of aortic aneurysm disease remain undiscovered and continue to be an area of intensive research. 1. Introduction The aortic aneurysmal disease is defined as focal dilation of the aorta, based on its original diameter. The dilatation must be at least one and one-half times the normal diameter. Thus, generally, a segment with a diameter of greater than 3.5?cm is considered as an aortic aneurysm. Thoracic aneurysms are those located above the diaphragm and may involve one or more aortic segments (aortic root, ascending aorta, arch, or descending aorta) and are classified accordingly. When they are located under diaphragm, aneurysms are classified as abdominal. The second ones are much more prevalent than thoracic aortic aneurysms. About 80% of aortic aneurysms occur between the renal arteries and the aortic bifurcation. Aortic aneurysm rupture represents the 13th cause of death in the USA, accounting for nearly 15,000 of deaths annually [1]. Although, often a late onset disease, there are a significant proportion of patients with presentation at age less than 60. Cases of aortic aneurysms in children have also been reported; however, they are very rare [2]. In this group, the proportion of thoracic or abdominal aortic aneurysms and dissections resulting from a geneticpredisposition is unknown. In the absence of an identifiable genetic syndrome, familial aggregation of these aneurysms is well established. The first-degreerelatives of an individual with an aortic aneurysm have a ten to twelvefold increased risk of developing aortic aneurysms [3–5]. There are multiple genetic syndromes associated with aortic aneurysmal disease (Table 1). The Key syndromes to consider in any patient who presents at a young age an aortic aneurysm include Marfan syndrome (MFS), Ehlers-Danlos syndrome (EDS), Loeys-Dietz syndrome (LDS), familial thoracic aortic aneurysms
Exponential Decay to the Degenerate Nonlinear Coupled Beams System with Weak Damping
R. F. C. Lobato,D. C. Pereira,M. L. Santos
ISRN Mathematical Physics , 2012, DOI: 10.5402/2012/659289
Abstract:
Contribui??o para o conhecimento da taxonomia, ecologia e fitogeografia de Briófitas da Amaz?nia Oriental
Alvarenga, Lisi Dámaris Pereira;Lisboa, Regina Célia Lobato;
Acta Amazonica , 2009, DOI: 10.1590/S0044-59672009000300003
Abstract: this paper presents the floristic survey of bryophytes from ferreira penna scientific station (ecfpn), located in the flona caxiuan? (1o42'30"s - 51o31'45"w), melga?o - pará, that was undertaken in the first stage of the residence program in amazonian studies, a project of the museu paraense emílio goeldi. mosses and liverworts were collected in non-flooded forest (terra firme), flooded forest (várzea and igapó), secondary forest and savanna ecosystems. they were analyzed for composition, richness and diversity. one thousand eighty one occurrences of 120 bryophytes species (79 liverworts and 41 mosses) were recorded; and among them eight liverworts are new references from the state of pará. the richest and most frequently encountered families were lejeuneaceae (58 spp.), calymperaceae (13 spp.), sematophyllaceae (9 spp.) and plagiochilaceae (7 spp.). the most representative communities were the epiphytic (97 species/ 565 occurrences) and epixylic (65 spp./ 242 ocurr.), followed by foliicolous (27 spp./ 174 ocurr.) and terricolous (15 spp./ 96 ocurr.); and the richest and most diverse ecosystem was the terra firme forest. the composition analysis of the surveyed substrates showed a gradual inversion in the richness ratio between liverworts/mosses, where the liverworts were strongly dominant in leaves, slightly dominant in live and dead trunks and the mosses were dominant in the others substrates. the results of this study, like the new references, contribute for understanding patterns of richness and diversity in amazonia and increase the bryophyte flora of pará.
Diversidade, taxonomia e distribui??o por estados brasileiros das famílias Bartramiaceae, Brachytheciaceae, Bryaceae, Calymperaceae, Fissidentaceae, Hypnaceae e Leucobryaceae (Bryophyta) da Esta??o Científica Ferreira Penna, Caxiuan?, Pará, Brasil
Moraes, Eryka de Nazaré Rezende;Lisboa, Regina Célia Lobato;
Acta Amazonica , 2009, DOI: 10.1590/S0044-59672009000400006
Abstract: the inventory of the species of mosses (bryophyta) was conducted in the scientific station ferreira penna, municipality of melga?o, state of pará. this station possesses 85% of its area of well conserved, terra-firme vegetation. although the phanerogams are relatively well studied, the mosses are only now moving forward with this work. besides inventorying the species of mosses inhabiting the area, other objectives are to expand knowledge regarding the geographical distribution of the species reported for the area, and to register the substratum type and ecosystem where they occur. there were identified 84 species, 37 genera and 19 families. this work is part of a series of studies accomplished with the mosses of ecfpn, just treating the 47 species belonging to the families bartramiaceae, brachytheciaceae, bryaceae, calymperaceae, fissidentaceae, hypnaceae and leucobryaceae. for each táxon they were mentioned place-type, herbarium, references of descriptions, comments regarding morphological characteristics, brazilian geographical distribution and examined material. herein we include new references for amazonian brazilian, fissidens pauperculus m. howe and octoblepharum costatum h. a. crum and for the state of pará, syrrhopodon incompletus schw?gr. var. berteroanus (brid.) w. d. reese and leucobryum crispum müll. hal.
Cololejeuneae (Lejeuneaceae, Hepaticae) na Esta??o Científica Ferreira Penna, Melga?o, PA, Brasil
Ilkiu-Borges, Anna Luiza;Lisboa, Regina Célia Lobato;
Acta Botanica Brasilica , 2004, DOI: 10.1590/S0102-33062004000400020
Abstract: a survey of the lejeuneaceae (hepaticae) family was performed at ferreira penna research station, melga?o municipality, pará state, where was observed eight species of cololejeuneae. the species aphanolejeunea truncatifolia horik., cololejeunea obliqua (nees & mont.) s.w. arnell and c. surinamensis tixier are new records for the state, while a. contractiloba (a. evans) r.m. schust., a. gracilis jov.-ast and a. winkleri morales & a. lucking are new records to brazil. the species are described and illustrated and an artificial key is presented to identifying them, as well as additional comments.
Musgos (Bryophyta) na Ilha Trambioca, Barcarena, PA, Brasil
Souza, Adriana Paula da Silva;Lisboa, Regina Célia Lobato;
Acta Botanica Brasilica , 2005, DOI: 10.1590/S0102-33062005000300008
Abstract: this work presents a survey of mosses from different ecosystems of trambioca island, municipality of barcarena, pará state, brazil. forty taxa of mosses were found, belonging to 20 genera and 13 families. the families with highest number of species were calymperaceae (12 spp.), sematophyllaceae (6 spp.), and leucobryaceae (5 spp.), which also presented the highest number of individuals. the most common species were sematophyllum subsimplex (hedw.) mitt, calymperes erosum müll. hal., pilosium chlorophyllum (hornsch.) müll. hal., callicostella pallida (hornsch.) ?rgstr., and trichosteleum papillosum (honrsch.) a. jaeger. it was observed a higher richness of species in the primary low land rainforest, confirming the preference of bryophytes for this ecosystem. philonotis gracillima ?ngstr. is mentioned as the first report to pará state.
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