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Search Results: 1 - 10 of 614285 matches for " A. C. PEREIRA "
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Aqueous Two-Phase Systems Applied to Partition Proteins from Goat Milk Whey In-Nature  [PDF]
Luziany A. C. Freire, Camila G. Pereira
Advances in Bioscience and Biotechnology (ABB) , 2016, DOI: 10.4236/abb.2016.79034
Abstract: The proteins coming from the milk whey have numerous functional properties. Among the proteins with high bioactivity, α-lactoalbumin (α-La) and β-lactoglobulin (β-Lg) are present in large quantities in the milk whey. In the separation process of proteins, it is important to choose techniques which besides ensuring purity and high yield will not affect the molecule biological activity. The aqueous two-phase systems (ATS) have been utilized with success in the partition of these proteins, however, the studies were performed using protein in its pure form. Studies using milk whey in-nature and goat milk whey have not been found yet. In this context, the objective of this study was to evaluate the liquid liquid equilibrium of aqueous two-phase systems (ATS) in the partition of α-La and β-Lg from goat milk whey in-nature. Equilibrium data were performed considering ATS comprised of polyethylene glycol, potassium phosphate and water at 25°C and pH 7.0. The influence of the polymer molecular weight and amount of goat milk whey in-nature on the partition coefficient of these proteins were assessed. The partition coefficient, selectivity, process yield and purity of α-lactoalbumin and β-lactoglobulin proteins were determined. The results showed that the separation technique by aqueous biphasic systems is applicable indicating high efficiency in the whey proteins separation process.
Bayesian Analysis of Simple Random Densities  [PDF]
Paulo C. Marques F., Carlos A. de B. Pereira
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.45037
Abstract:

A tractable nonparametric prior over densities is introduced which is closed under sampling and exhibits proper posterior asymptotics.

Predictive Analysis of Microarray Data  [PDF]
Paulo C. Marques F., Carlos A. de B. Pereira
Open Journal of Genetics (OJGen) , 2014, DOI: 10.4236/ojgen.2014.41009
Abstract:

Microarray gene expression data are analyzed by means of a Bayesian nonparametric model, with emphasis on prediction of future observables, yielding a method for selection of differentially expressed genes and the corresponding classifier.

Asymptotic behavior for semi-linear wave equation with weak damping
D. C. Pereira,C. A. Raposo
International Journal of Mathematical Analysis , 2013,
Abstract: In this work we study the asymptotic behavior as t → ∞ of thesolutions for the initial boundary value problem associated to the semilinearwave equation with weak damping.
Resveratrol Reverses the Impaired Vasodilation Observed in 2K-1C Hypertension through Endothelial Function Improvement  [PDF]
B. F. M. Pereira, A. C. Scalabrini, T. S. Marinho, C. R. K. Antonietto, C. B. A. Restini
Open Journal of Medicinal Chemistry (OJMC) , 2014, DOI: 10.4236/ojmc.2014.42004
Abstract:
Background: The production of endothelial-derived factors induces either vasoconstriction or vasodilation; nitric oxide (NO) is the most distinguished relaxing factor. Endothelial dysfunction is associated with hypertension. The partial loss in the NO-promoted vasodilation is due to its decreased bioavailability and/or to an activity reduction of endothelium NO synthase (eNOS). Reactive oxygen species (ROS), present in oxidative stress, seize NO and diminish its bioavailability. Transresveratrol (RESV) has been proved to increase NO and eNOS levels. Thus, RESV could be capable of improving NO dependent vascular relaxation on aortic rings isolated from treated 2K-1C animals through ROS damage reduction. Aim: Evaluate the effects of RESV treatment on the relaxation of aortic rings isolated from treated 2K-1C rats while focusing on the effects of the treatment on systolic blood pressure. Methods: Male Wistar rats (180 g) were grouped: two 2K-1C and two Sham groups, one of each was treated with RESV (20 mg/kg, gavage) dissolved in Tween 80 and one of each was treated with water plus Tween 80 (control) for six weeks. The rats had their systolic blood pressure (SBP) measured before and after the treatments. Vascular reactivity studies were conducted in order to observe and compare acetylcholine (ACh)-induced relaxations in the presence and absence of the NOS inhibitor L-NAME (10-4 mol/L). Results: SBP for 2K-1C was significantly reduced in the treated group (179.13 ± 4.90 mmHg, n = 23) when compared to the untreated group (196.66 ± 6.06 mmHg, n = 15, p < 0.01). The maximum relaxation of aortic rings isolated from the 2K-1C treated group showed a higher efficacy (116.63% ± 1.72%, n = 12) than that from the untreated group (85.97% ± 0.69%, n = 6, p < 0.001); L-NAME exposure was responsible for a significant decrease in each group’s maximum relaxation efficacy. Conclusions: SBP reduction observed after RESV treatment in rat renal hypertension could be due to the reestablishment of vascular relaxation depend of NO.
Adittional levels between Landau bands due to vacancies in graphene: towards a defect engineering
A. L. C. Pereira,P. A. Schulz
Physics , 2008, DOI: 10.1103/PhysRevB.78.125402
Abstract: We describe the effects of vacancies on the electronic properties of a graphene sheet in the presence of a perpendicular magnetic field: from a single defect to an organized vacancy lattice. An isolated vacancy is the minimal possible inner edge, showing an antidotlike behaviour, which results in an extra level between consecutive Landau levels. Two close vacancies may couple to each other, forming a vacancy molecule tuned by the magnetic field. We show that a vacancy lattice introduce an extra band in between Landau levels with localization properties that could lead to extra Hall resistance plateaus.
Hemoglobin S Polymerization Effect on Water Self-Diffusion Coefficient  [PDF]
Manuel A. Lores Guevara, Juan C. García-Naranjo, Yulianela Mengana, Jorge Pereira
Advances in Biological Chemistry (ABC) , 2014, DOI: 10.4236/abc.2014.46044
Abstract: The transversal relaxation time, the effective transversal relaxation time and the water self-diffusion coefficient are evaluated during hemoglobin S polymerization. One homogeneous permanent magnet and one inhomogeneous and portable unilateral magnet with a very strong and constant static magnetic field gradient were utilized. The Carr-Purcell-Meiboom-Gill method was used before and after placing the studied samples 24 hours at 36°C to guarantee the polymerization. The transversal relaxation shows two exponents after polymerization supporting the concept of partially polymerized hemoglobin. The effective transversal relaxation time decreases around 40%, which can be explained by the increase of water self-diffusion coefficient 1.8 times as a main value. This result can be explained considering the effects of the agglutination process on the obstruction and hydration effects in a partially polymerized solution.
Asymptotic Behaviour to a Von Kármán System with Internal Damping  [PDF]
Ducival C. Pereira, Carlos A. Raposo, Celsa H. M. Maranh?o
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.33033
Abstract: In this work we consider the Von Kármán system with internal damping acting on the displacement of the plate and using the Theorem due to Nakao [1] we prove the exponential decay of the solution.
Investiga??o do comportamento eletrocr?mico de filmes finos de Nb2O5 por método quimiométrico
Rosário, A. V.;Pereira, E. C.;
Ceramica , 1999, DOI: 10.1590/S0366-69131999000100008
Abstract: nb2o5 electrochromic films were produced by the pechini method and deposited by dip-coating. the influence of the preparation conditions on the materials properties was investigated by a fractional factorial design based on eight variables. the films had their electrochromic properties investigated by cyclic voltammetry and uv-vis spectrophotometry "in situ", in acetonitrile solution containing liclo4 0.1 m as supporting electrolyte . during the reduction, a blue coloration is formed in the nb2o5 electrode. this coloration process is associated to the nb5+ to nb4+ reduction and the intercalation of li+ ions. a density charge of 45 mc/cm2 was obtained during cathodic sweeping at v=10 mv/s. the same film showed good optical reversibility, with variation of transmittance of approximately 60%. x-ray diffraction reveals that the films which presented best electrochromic response are those that possess higher crystalline character.
Investiga o do comportamento eletrocr mico de filmes finos de Nb2O5 por método quimiométrico
Rosário A. V.,Pereira E. C.
Ceramica , 1999,
Abstract: Filmes de Nb2O5 eletrocr micos foram produzidos através do método de Pechini e deposi o por "dip-coating". A influência das condi es de prepara o sobre as propriedades do material foi investigada por um planejamento fatorial fracionário com base em oito variáveis. Os filmes tiveram suas propriedades eletrocr micas investigadas por medidas de voltametria cíclica e espectrofotometria UV-Vis "in situ", em solu o de acetonitrila contendo LiClO4 0,1 M como eletrólito suporte. Durante a redu o, uma colora o azul é observada no eletrodo eletrocr mico. Este processo de colora o está associado à redu o Nb5+ Nb4+ e à intercala o de íons Li+ na matriz do óxido, sendo que uma densidade de carga superior a 45 mC/cm2 foi obtida durante varredura catódica à v=10 mV/s. O mesmo filme mostrou boa reversibilidade óptica, com varia o de transmitancia de aproximadamente 60%. As medidas de difra o de raios X revelam que os filmes que apresentaram melhor resposta eletrocr mica s o aqueles que possuem maior caráter cristalino. As variáveis de composi o da resina s o os fatores de maior influência sobre as propriedades dos filmes de Nb2O5.
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