Time filter

Source Type

Abade G.C.,University of Warsaw | Abade G.C.,Campus Universitario Darcy Ribeiro | Cichocki B.,University of Warsaw | Ekiel-Jeewska M.L.,Polish Academy of Sciences | And 2 more authors.
Journal of Chemical Physics | Year: 2010

We determine the high-frequency limiting shear viscosity, η∞, in colloidal suspensions of rigid, uniformly porous spheres of radius a as a function of volume fraction φ and (inverse) porosity parameter x. Our study covers the complete fluid-state regime. The flow inside the spheres is modeled by the Debye-Bueche-Brinkman equation using the boundary condition that fluid velocity and stress change continuously across the sphere surfaces. The many-sphere hydrodynamic interactions in concentrated systems are fully accounted for by a precise hydrodynamic multipole method encoded in our HYDROMULTIPOLE program extended to porous particles. A truncated virial expansion is used to derive an accurate and easy-to-use generalized Saitô formula for η∞. The simulation data are used to test the performance of two simplifying effective particle models. The first model describes the effective particle as a nonporous sphere characterized by a single effective radius aeff (x)


Abade G.C.,University of Warsaw | Abade G.C.,Campus Universitario Darcy Ribeiro | Cichocki B.,University of Warsaw | Lekiel-Jezewska M.L.,Polish Academy of Sciences | And 2 more authors.
Journal of Physics Condensed Matter | Year: 2010

We study the high-frequency limiting shear viscosity, η ∞ of colloidal suspensions of uncharged porous particles. An individual particle is modeled as a uniformly porous sphere with the internal solvent flow described by the Debye-Bueche-Brinkman equation. A precise hydrodynamic multipole method with a full account of many-particle hydrodynamic interactions encoded in the hydromultipole program extended to porous particles, is used to calculate η∞ as a function of porosity and concentration. The second-order virial expansion for η∞ is derived, and its range of applicability assessed. The simulation results are used to test the validity of generalized Stokes-Einstein relations between η∞ and various short-time diffusion coefficients, and to quantify the accuracy of a simplifying cell model calculation of η∞ .An easy-to-use generalized Saito formula for η∞ is presented which provides a good description of its porosity and concentration dependence. © 2010 IOP Publishing Ltd.


Lunardi V.O.,University of Brasilia | Lunardi V.O.,Rural University | MacEdo R.H.,Campus Universitario Darcy Ribeiro
Wilson Journal of Ornithology | Year: 2010

The Wilson's Plover (Charadrius wilsonia) is widely distributed along the coast of the Americas. We present the first reproductive record in Baa de Todos os Santos, Brazil, broadening the southernmost limit of its breeding area along the Atlantic Coast to 12° 44′ S, 38° 45′ W. We recorded a family with a subadult in 2007, and a family with chicks and a nest in 2008. The female invested more time in incubation than the male in 96 hrs of diurnal nest observations. There were 102 interruptions during incubation due to the approximation of domestic animals (cattle and horses). The nest was abandoned 9 days after egg laying. An experiment with artificial nests suggests that 30 of Wilson's Plover nests may be destroyed by free-ranging domestic animals in this Baa. © 2010 by the Wilson Ornithological Society.


PubMed | Campus Universitario Darcy Ribeiro, Catholic University of Brasília, University of Sao Paulo and University of Brasilia
Type: Journal Article | Journal: Microbial cell factories | Year: 2016

Crude glycerol is the main byproduct of the biodiesel industry. Although it can have different applications, its purification is costly. Therefore, in this study a biotechnological route has been proposed for further utilization of crude glycerol in the fermentative production of lactic acid. This acid is largely utilized in food, pharmaceutical, textile, and chemical industries, making it the hydroxycarboxylic acid with the highest market potential worldwide. Currently, industrial production of lactic acid is done mainly using sugar as the substrate. Thus here, for the first time, Pichia pastoris has been engineered for heterologous L-lactic acid production using glycerol as a single carbon source. For that, the Bos taurus lactate dehydrogenase gene was introduced into P. pastoris. Moreover, a heterologous and a novel homologous lactate transporter have been evaluated for L-lactic acid production.Batch fermentation of the P. pastoris X-33 strain producing LDHb allowed for lactic acid production in this yeast. Although P. pastoris is known for its respiratory metabolism, batch fermentations were performed with different oxygenation levels, indicating that lower oxygen availability increased lactic acid production by 20%, pushing the yeast towards a fermentative metabolism. Furthermore, a newly putative lactate transporter from P. pastoris named PAS has been identified by search similarity with the lactate transporter from Saccharomyces cerevisiae Jen1p. Both heterologous and homologous transporters, Jen1p and PAS, were evaluated in one strain already containing LDH activity. Fed-batch experiments of P. pastoris strains carrying the lactate transporter were performed with the batch phase at aerobic conditions followed by an aerobic oxygen-limited phase where production of lactic acid was favored. The results showed that the strain containing PAS presented the highest lactic acid titer, reaching a yield of approximately 0.7g/g.We showed that P. pastoris has a great potential as a fermentative organism for producing L-lactic acid using glycerol as the carbon source at limited oxygenation conditions (below 0.05% DO in the bioreactor). The best strain had both the LDHb and the homologous lactate transporter encoding genes expressed, and reached a titer 1.5 times higher than the strain with the S. cerevisiae transporter. Finally, it was also shown that increased lactic acid production was concomitant to reduction of acetic acid formation by half.


Francoso R.D.,University of Brasilia | Haidar R.F.,Campus Universitario Darcy Ribeiro | Machado R.B.,University of Brasilia
Acta Botanica Brasilica | Year: 2016

Biological knowledge is important for guidance of conservation polices. In the Cerrado, an extremely diverse biome, the last synthesis of floristic knowledge has more than ten years. To understand the progress on the information, our aim was quantify the tree species of the Cerrado, and assess their distribution. We compiled 167 inventories and rapid surveys of tree species, corresponding to 625 sites. We accessed the species distributions in the Brazilian biomes, and estimated the number of species in the savannas of Cerrado using four algorithms. We observed a greater local richness in more central regions of the biome, but due to high beta diversity, more peripheral regions presented a greater cumulative richness. The Atlantic Forest was the most important neighbouring biome, influencing the floristic composition of the Cerrado. The proportion of typical Cerrado species was 16%. The highest proportion of endemic species is possibly found in other life forms, and it is crucial that these species are included in inventories and floristic surveys. To guide new studies and help supplement the knowledge of the Cerrado’s flora, we identified the main sampling gaps, located mainly in ecotonal regions, which are responsible for the largest number of species recorded in studies of the Cerrado. © 2016, Sociedade Botanica do Brasil. All rights reserved.


Roa A.C.,Campus Universitario Darcy Ribeiro | De Santana J.P.,Organizacao Pan Americana da Saude
Revista Panamericana de Salud Publica/Pan American Journal of Public Health | Year: 2012

This paper analyzes whether south-south cooperation is legitimately a recent practice or merely an improved version of previous regional integration processes in Latin America and the Caribbean. The authors reviewed and systematized the historic development of subregional integration processes in Latin America and the Caribbean and focused on health cooperation in the following contexts: the Central American Integration System, the Andean Community of Nations, the Caribbean Community, the Amazon Cooperation Treaty Organization, the Southern Common Market, and the Union of South American Nations. The study concludes that the conceptual and methodologic foundations of south-south cooperation in health were born from and nurtured by the processes of regional integration in Latin America and the Caribbean. This paper posits that regional political and economic integration initiatives bring potential benefits to the health sector and act as an important mechanism to develop south-south cooperation in this domain. The study recommends furthering this type of research to provide information that will allow national and multilateral agencies, or other stakeholders, to formulate and implement better policies for international health cooperation that target reducing inequities and promoting health and wellbeing for all people.


Dutra J.D.L.,Federal University of Sergipe | Ferreira J.W.,Federal University of Sergipe | Rodrigues M.O.,Campus Universitario Darcy Ribeiro | Freire R.O.,Federal University of Sergipe
Journal of Physical Chemistry A | Year: 2013

When Judd-Ofelt intensity parameters of polynuclear compounds with asymmetric centers are calculated using the current procedure, the results are inconsistent. The problem arises from the fact that the experimental intensity parameters cannot be determined for each asymmetric polyhedron, and this precludes the individual theoretical adjustment. In this study, we then propose three different methods for calculation of these parameters of polyeuropium systems. The first, named the centroid method, proposes the calculation considering the center of the dimeric system as the half distances between the two europium centers. The second method, called the overlapped polyhedra method, proposes the calculation considering the overlapping of both europium polyhedra, and the last one, the individual polyhedron method, proposes the use of theoretical mean values of charge factors and polarizabilities associated with each europium-ligand atom bond to calculate the intensity parameters. One symmetric polyeuropium system and one asymmetric system were assessed by using the three methods. Among the methods assessed, the one based on the overlapped polyhedra produced more consistent results for the study of both kinds of systems. © 2013 American Chemical Society.


Amato A.A.,Campus Universitario Darcy Ribeiro | De Assis Rocha Neves F.,Campus Universitario Darcy Ribeiro
PPAR Research | Year: 2012

The incidence of type 2 (T2D) diabetes and other chronic conditions associated with insulin resistance is increasing at an alarming rate, underscoring the need for effective and safe therapeutic strategies. Peroxisome-proliferator-activated receptor gamma (PPAR) has emerged as a critical regulator of glucose homeostasis, lipid homeostasis, and vascular inflammation. Currently marketed drugs targeting this receptor, the thiazolidinediones (TZDs), have proven benefits on insulin resistance and hyperglycemia associated with T2D. Unfortunately, they have been associated with long-term unfavorable effects on health, such as weight gain, plasma volume expansion, bone loss, cardiovascular toxicity, and possibly cancer, and these safety concerns have led to reduced interest for many PPAR ligands. However, over the last years, data from human genetic studies, animal models, and studies with ligands have increased our understanding of PPARs actions and provided important insights into how ligand development strategies could be optimized to increase effectiveness and safety of PPAR-based therapies. Copyright © 2012 Angélica Amorim Amato and Francisco de Assis Rocha Neves.


do Nascimento W.F.,Campus Universitario Darcy Ribeiro | Garrafa V.,Campus Universitario Darcy Ribeiro
Saude e Sociedade | Year: 2011

This paper aims to discuss some concepts - developed within the Coloniality Studies by a group of thinkers in Latin America - about how Modernity emerged structured as a way to dispose power, knowledge and being, so that a hierarchy between center and periphery, installed in a colonial perspective, organizes our way of dealing with politics, with science and - this is the main focus of this paper - with life. Intervention Bioethics (IB), whose proposal is to politicize in an ethical manner the method of dealing with biotechnoscientific, sanitary, social and environmental conflicts from the Latin American reality, develops a line of research that can accommodate the contributions, as well as the criticisms, from Coloniality Studies, particularly with regard to conceptual frameworks related to the ethical and epistemological theories that support it. Among these conceptual frameworks, this paper deals specifically with the relationship between the utilitarianism accepted by IB through a supportive consequentialism and its interrelations with the idea of Coloniality.


Cunha F.R.,Campus Universitario Darcy Ribeiro | Gontijo R.G.,Campus Universitario Darcy Ribeiro | Sobral Y.D.,Campus Universitario Darcy Ribeiro
Journal of Magnetism and Magnetic Materials | Year: 2013

This work presents a numerical study of the relative trajectories of two magnetic particles interacting in a dilute suspension. The suspension is composed of magnetic spherical particles of different radius and density immersed in a Newtonian fluid. The particles settle relative to one another under the action of gravity and, when in close proximity, exert on each other magnetic force and torque due to their permanent magnetization. The equations of motion for both translation and rotation of the particles are solved and particle inertia is included in the calculation. The numerical simulations are based on the direct computations of the hydrodynamic and of the magnetic interactions between the rigid particles in the regime of non-zero Stokes number. A detailed study of the relative trajectories of two magnetic particles in a dilute suspension allows us to explore irreversible interactions that lead to particle aggregation and particle migration induced by the breaking of the time reversibility of the creeping flow due to magnetic effects. The calculation shows that the rotation of the particles produced by magnetic interactions change significantly the dynamics of collisions of magnetic particle. © 2012 Elsevier B.V.

Loading Campus Universitario Darcy Ribeiro collaborators
Loading Campus Universitario Darcy Ribeiro collaborators