Centro Universitario da Zona Oeste
Centro Universitario da Zona Oeste
Castello D.A.,Federal University of Rio de Janeiro |
Borges L.A.,Federal University of Rio de Janeiro |
Santos V.O.B.,Federal University of Rio de Janeiro |
Soares B.G.,Federal University of Rio de Janeiro |
And 2 more authors.
Journal of the Brazilian Society of Mechanical Sciences and Engineering | Year: 2017
The present work presents a general approach for viscoelastic material characterization. The standard solid model and the fractional Zener model are taken into consideration. Model calibration is performed under the formalism of the inverse problems. Model validation and model selection are guided by the philosophy of the verification and validation field. Comparisons between measured data and model predictions take model uncertainties into account through Monte Carlo simulation analysis. This approach is used to calibrate models for two diglycidyl ether of bisphenol A (DGEBA) based epoxy systems modified by the incorporation of hydroxyl-terminated polybutadiene (HTPB), namely: DGEBA/HTPB blend (EPH) and DGEBA/HTPB blend modified with NCO groups (EPI). Three different types of tests are considered and a large group of test specimens are analyzed. The constitutive models are used to provide predictions for the loss factor of the materials as well as their confidence intervals. Predictions indicate that EPI presents better performance concerning mechanical energy dissipation than EPH which is highly correlated with the fact that EPI presents rubber particles distributed uniformly in nanometric scale within the epoxy matrix. © 2016, The Brazilian Society of Mechanical Sciences and Engineering.
Oliveira A.P.,Centro Universitario da Zona Oeste |
Cruz R.A.S.,Centro Universitario da Zona Oeste |
Botas G.S.,Centro Universitario da Zona Oeste |
Kuster R.M.,Federal University of Rio de Janeiro |
Rocha L.,Federal University of Fluminense
Latin American Journal of Pharmacy | Year: 2013
In a search for potential acetylcholinesterase inhibitors (IAChE), the dichloromethane ex-tract from Sideroxylon obtusifolium leaves demonstrated a marked enzyme inhibition. A TLC bioauto-graphic assay and Ellman's reaction were used as bioassays to guide the isolation of IAChE. Three com-pounds were purified sufficiently to allow structural analysis and determination of their half inhibitory concentration (IC50). The structures of these compounds were elucidated by spectrometric methods in-cluding EIMS, 1H, 13C and 2D NMR experiments. Ursolic acid has been identified as the compound re-sponsible for that inhibition. Two other molecules -the triterpernoids betulin and lupeol-were also isolat-ed and characterized for the first time from S. obtusifolium. The IC50 value of ursolic acid was found to be 34.3 μM/mL.
de Abreu Martins S.,Centro Universitario da Zona Oeste |
de Abreu Martins S.,Instituto Superior Of Educacao Do Rio Of Janeiro Iserj Faetec |
de Abreu Martins C.,ArcelorMittal |
Fonstein N.,ArcelorMittal |
Barbosa Godefroid L.,Federal University of Ouro Preto
Materials Science Forum | Year: 2016
Steel is the main material used in the automotive industry, mainly due to its excellent mechanical properties. However, with the development of new materials and technologies in recent decades, there is a demand to improve steel competitiveness to face the market of materials and achieve improvements in quality and performance of cars. In this work it was produced on pilot scale C-Mn-V steels with Cr or Mo addition. The main objective was to evaluate the effects of Cr or Mo addition on microstructure and mechanical properties. These steels were submitted to tensile, bending and hole expansion tests, while microstructure was analyzed using OM and SEM. It could be seen that addition of Cr or Mo resulted in improvements on mechanical properties. However, C-Mn-V steel with Mo performed better, showing excellent behavior in tensile and bending tests, increasing around 30% of mechanical resistance. © 2016 Trans Tech Publications, Switzerland.
Dos Santos C.K.,Institute Pesquisas da Marinha IPqM |
Espindola R.P.,Centro Universitario da Zona Oeste |
Evsukoff A.G.,Federal University of Rio de Janeiro
IEEE Latin America Transactions | Year: 2015
This paper investigates the use of three external feedback connections in the development of new recurrent fuzzy models for prediction of nonlinear dynamic systems. These models are formulated by state space equations. The state transition function is a TSK recurrent fuzzy system with an external feedback connection and adaptive delayed operators, and the output function is a polynomial function of the states. The identification of the model's parameters is carried out by a canonical differential evolution algorithm. The model performance was evaluated in benchmark problems found in the literature and the results demonstrated that the aiding of external feedbacks enhanced the recurrent fuzzy system quality, yielding models with good performance. © 2003-2012 IEEE.
Optimization of mechanical properties of polypropylene (PP)/ethylene- propylene-diene monomer rubber (EPDM)/scrap rubber tire (SRT) ternary mixtures under tensile and impact using the response surface methodology (RSM) [Otimização de Propriedades Mecânicas de Misturas Ternárias de Polipropileno (PP)/Borracha de Etileno-Propileno-Dieno (EPDM)/Pó de Pneus (SRT) sob Tração e Impacto usando a Metodologia da Superfície de Resposta (MSR)]
Da Costa H.M.,State University of Rio de Janeiro |
Ramos V.D.,State University of Rio de Janeiro |
Da Silva W.S.,State University of Rio de Janeiro |
Da Silva Sirqueira A.,Centro Universitario da Zona Oeste
Polimeros | Year: 2012
The response surface methodology (RSM) is a collection of statistical and mathematical techniques for developing, improving and optimizing processes. In this study, RSM technique was applied to the investigation of the mechanical behavior of different PP/EPDM/SRT ternary mixtures. After appropriate processing in a co-rotating twin extruder and injection molding, the mechanical properties, such as tensile strength and impact strength, were determined and used as response variables. Scanning electron microscopy (SEM) was used for investigating the morphology of the different blends and to interpret the results. With specific statistical tools, a minimum number of experiments allowed the response surface model to be developed and the concentrations of the components to be optimized according to the mechanical performance. High values of impact strength were reached (>80 J.m -1) when the PP/EPDM/SRT mixture had a EPDM/SRT ratio of around 25%.
Moreira Da Costa L.,Canadian National Institute For Nanotechnology |
Moreira Da Costa L.,Federal University of Rio de Janeiro |
Moreira Da Costa L.,Federal University of Fluminense |
Moreira Da Costa L.,Centro Universitario da Zona Oeste |
And 7 more authors.
Journal of Physical Chemistry A | Year: 2014
Density functional theory (DFT), Møller-Plesset second-order perturbation theory (MP2), and semiempirical methods are employed for the geometry optimization and thermochemistry analysis of π-π stacked di-, tri-, tetra-, and pentamer aggregates of the fused polycyclic aromatic hydrocarbons (PAHs) naphthalene, anthracene, phenanthrene, tetracene, pyrene, and coronene as well as benzene. These aggregates (stabilized by dispersion interactions) are highly relevant to the intermolecular aggregation of asphaltenes, major components of heavy petroleum. The strength of π-π stacking interaction is evaluated with respect to the π-stacking distance and thermochemistry results, such as aggregation enthalpies, entropies, and Gibbs free energies (ΔG298). For both π-stacking interplanar distances and thermochemistry, the ωB97X-D functional with an augmented damped R-6 dispersion correction term and MP2 are in the closest agreement with the highly accurate spin-component scaled MP2 (SCS-MP2) method that we selected as a reference. The ΔG298 values indicate that the aggregation of coronene is spontaneous at 298 K and the formation of pyrene dimers occurs spontaneously at temperature lower than 250 K. Aggregates of smaller PAHs would be stable at even lower temperature. These findings are supported by X-ray crystallographic determination results showing that among the PAHs studied only coronene forms continuous stacked aggregates in single crystals, pyrene forms dimers, and smaller PAHs do not form π-π stacked aggregates. Thermochemistry analysis results show that PAHs containing more than four fused benzene rings would spontaneously form aggregates at 298 K. Also, round-shaped PAHs, such as phenanthrene and pyrene, form more stable aggregates than linear PAHs, such as anthracene and tetracene, due to decreased entropic penalty. These results are intended to help guide the synthesis of model asphaltene compounds for spectroscopic studies so as to help understand the aggregation behavior of heavy petroleum. © 2014 American Chemical Society.
Souza A.R.,Estácio de Sá University |
Cardoso M.E.O.,Estácio de Sá University |
Braga I.G.,Estácio de Sá University |
Albuquerque A.C.,Estácio de Sá University |
And 15 more authors.
Stem Cell | Year: 2010
Objective: The Saccharomyces cerevisiae, a species of yeast, is used as a model of study for several types of purposes, exceeding then, as a model of biological application to the glucose human metabolism. The microcurrent can produce the lesser amount of measurable electric chains with similar and compatible electric signals to the electromagnetic field of the human body when these are recovering from tissue injury or has disruption of its normal electric activity. Also, it would stimulate a metabolic alteration to the point where it produces significant amounts and until the modulating of energy in the form of Adenosine Triphosfate - (ATP). The goal of this study was to evaluate the effect of the microcurrent through the parameters of the absorbance and pH in the metabolism of the glucose to explore the human similarities and the capacity of inquiry that the Saccharomyces cerevisiae supplies. Methods: One of the methods of glucose determination in used liquid samples more in the world and widely used in assays biochemists of dosage of reducing sugars and for studies of kinetic enzymatic is of the acid dinitrosalicylic (DNS), discovered in the end of the decade of 50 (Miller, L., 1959). The pH measurements have been performed in the chemistry from the very beginning; in this case it was used for H+ detection and the pH measured correlated to the total glucose concentration present in the sample. First, we apply the microcurrent of three distinct intensities in liquid samples of saccharomyces; later the glucose for the metabolization was added. Second, we submit the samples for the analysis of the absorbance and pH for possible verification of the metabolization of the glucose and evaluation of the results. Results: In this study, it could be observed that the treatment, depending on the intensity of the applied microcurrent, caused an increase of the absorbance and pH when observed for the intensities of 100μA, 500μA and 900μA, showing that the cells had absorbed little glucose. Conclusion: From the analysis of the acquired results, it can be suggested that the evaluated microcurrent is capable of modifying the glucose and calcium captation in the leavenings with the increase of the absorbance and pH.
Fidelis Q.C.,Federal Rural University of Rio de Janeiro |
Castro R.N.,Federal Rural University of Rio de Janeiro |
Guilhon G.M.S.P.,Federal University of Pará |
Rodrigues S.T.,Embrapa Amazonia Oriental |
And 3 more authors.
Molecules | Year: 2012
The chemical study of the extracts from leaves and stems of Ouratea ferruginea allowed the identification of a new isoflavone, 5-hydroxy-7, 3′4′5′-tetramethoxyisoflavone, and twenty two known compounds, including friedelin, 3ß-friedelinol, lupeone, a mixture of sitosterol, stigmasterol and campesterol, sitosteryl- and stigmasteryl-3-O-b- Dglucopyranosides, 5, 4′-dihydroxy-7, 5′, 3′- trimethoxyisoflavone, 5, 4′-dihydroxy-7, 3′-dimethoxyisoflavone (7, 3′-di-O-methylorobol), 5, 7, 4′-trihydroxy-3′, 5′-dimethoxyisoflavone (piscigenin), 2R, 3R-epicatechin, syringic acid, 2, 6-dimethoxybenzoquinone, 2, 6-dimethoxyhydroquinone, syringic and ferulic aldehyde, a mixture of vanillic acid, 1-hydroxy-2-methoxy-4-(1E-3-hydroxy-1- propenyl)-benzene and 3, 5-dimethoxy-4-hydroxydihydrocinamaldehyde, besides amenthoflavone and 7-O-methylamenthoflavone (sequoiaflavone) which are considered as chemotaxonomic markers of Ouratea. The structures were identified by IR, 1H- and 13CC-NMR and GC-MS, HPLC-MS, besides comparison with literature data. The inhibitory effects of 5, 4′-dihydroxy-7, 5′, 3′- trimethoxyisoflavone, 7, 3′-di-O-methylorobol, piscigenin and 7-O-methylamenthoflavone on cytochrome P450-dependent 7-ethoxycoumarin O-deethylase (ECOD) and glutathione S-transferase (GST) were evaluated in vitro. The 5, 4′-dihydroxy-7, 5′, 3′-trimethoxyisoflavone was the best inhibitor, inhibiting almost 75% of GST activity. Sequoiaflavone was the most potent inhibitor, inhibiting ECOD assay in 75%. These activities allow us to consider both these flavonoids as potential anticancer and chemopreventive agents. © 2012 by the authors.
Costa M.,Federal University of Rio de Janeiro |
Costa M.,Centro Universitario da Zona Oeste |
Zavaleta J.,Federal University of Rio de Janeiro |
Da Cruz S.M.S.,Federal University of Rio de Janeiro |
And 5 more authors.
Proceedings - IEEE Symposium on Computer-Based Medical Systems | Year: 2013
This paper aims to present a computational tool based on neural networks to detect people with possible learning disabilities (dyslexia). Participants were aged from nine to 18 years old with or without the diagnosis of dyslexia. Neural networks technique showed consistency in dealing with the problems of pattern recognition in the screening of dyslexia. © 2013 IEEE.