249 research outputs found

    Vingança e temporalidade: os Tupinambás

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    Dóceis, os Tupinambás3 convertiam-se à fé dos jesuítas. Dóceis, decerto, mas inconstantes, queixavam-se os padres: “ lo que yo tengo por maior obstáculo para la gente de todas estas naciones es su propia condición, que ninguna cosa sienten mucho, ni pérdida espiritual ni temporal suya, de ninguna cosa tienen sentimiento mui sensible, ni que les dure; y así sus contricciones, sus deseos de seren buenos, todo es tan remiso, que no se puede hombre certificar de él” (Pe. Luís da Grã a Pe. Inácio de Loyola. Piratininga, 8 de junho de 1556, CPJB 11:294). Uma mesma inconstância não os incitava a resistir à conversão, mas tampouco a perseverar: “com hum anzol que lhea dê, os converterei a todos, e com outro os tornarei a desconverter” ... (Diálogo da Conversão do Gentio, CPJB II: 320)

    Three Dimensional de Sitter Gravity and the Correspondence

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    Certain aspects of three dimensional asymptotically de Sitter spaces are studied, with emphasis on the mapping between gravity observables and the representation of the conformal symmetry of the boundary. In particular, we show that non-real conformal weights for the boundary theory correspond to space-times that have non-zero angular momentum. Some miscellaneous results on the role of the holonomies and isometry groups are also presented.Comment: 10 pages, 1 figure, uses epsf. Added references and a discussion on the (dis)similarities with previous work

    Immobilization of b-galactosidase from kluyveromyces lactis onto a polysiloxane–polyvinyl alcohol magnetic (mPOS–PVA) composite for lactose hydrolysis

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    β-Galactosidase from Kluyveromyces lactis was covalently immobilized onto a mPOS–PVA, using glutaraldehyde as activating agent and its properties were evaluated. The enzymatic water insoluble derivative displayed the same optimum pH (6.5) and optimum temperature (50 °C) of the soluble enzyme. The apparent Km app and activation energy for both soluble and immobilized enzyme derivative were found to be not significantly different. The mPOS–PVA β-galactosidase preparation presented a higher operational and thermal stability than the soluble enzyme. This immobilized β-galactosidase also was effective in hydrolyzing lactose from milk. Hence, one can conclude that mPOS–PVA is an attractive and efficient support for β-galactosidase immobilization.Alban, the European Union Programme of High Level Scholarships for Latin America; Brazilian National Research Council (CNPq)

    Physical properties of edible coatings and films made with a polysaccharide from Anacardium occidentale L.

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    The effect of the concentrations of the polysaccharide from Anacardium occidentale L. (Policaju) and a surfactant (Tween 80) on relevant properties of edible coatings/films, in view of their application on apples (cv. Golden) was evaluated. The influence of the interactions between those two constituents on apples’ surface properties and on the coating/film’s wettability, water vapor permeability, opacity and mechanical properties was evaluated. The effects of the studied variables (polysaccharide and surfactant concentrations) were analyzed according to a 2² factorial design. Pareto bar charts were used to understand the most significant factors on the studied properties. The addition of surfactant reduced the cohesion forces, therefore reducing the surface tension and increasing the wettability; this resulted in an improved compatibility between the solution and the fruit skin surface. The opacity was also reduced. The results of each of the analyzed properties were adjusted to a polynomial, multifactor model, which provided a good fitting accuracy. This model is important once it will reduce the characterization work needed in subsequent applications of these coatings/films on foods.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes, Brazil)Fundação para a Ciência e a Tecnologia (FCT)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazi

    Production and characterization of protease from Penicillium aurantiogriseum URM 4622

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    Proteases with new properties are required due to their increasing industrial importance. In this work, the optimal fermentation conditions for the production of a protease from Penicillium aurantiogriseum dierchx (URM-4622) are presented together with partial characterization of the protease catalytic properties. The batch fermentation conditions that allow for the highest specific proteolytic activity are 26 ºC, pH 7.0, and 25 % saturation dissolved O2 concentration. The obtained protease is stable over a wide range of pH (5.8 to 9.5) and temperature (25 to 40 ºC) values. In the presence of Zn2+ a 26 % reduction in the enzyme proteolytic activity occurs and, in contrast, Mn2+ enhances its activity by 28.9 %. 96.2 % and 70.8 % of the protease activity are maintained after 90 min incubation in 5 and 10 % (v/v) H2O2 aqueous solutions, respectively. PMSF inhibition reveals that this enzyme is a serine protease. Protease is able to hydrolyze different proteins

    Tachyon Effective Dynamics and de Sitter Vacua

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    We show that the DBI action for the singlet sector of the tachyon in two-dimensional string theory has a SL(2,R) symmetry, a real-time counterpart of the ground ring. The action can be rewritten as that of point particles moving in a de Sitter space, whose coordinates are given by the value of the eigenvalue and time. The symmetry then manifests as the isometry group of de Sitter space in two dimensions. We use this fact to write the collective field theory for a large number of branes, which has a natural interpretation as a fermion field in this de Sitter space. After spending some time building geometrical insight on facts about the condensation process, the state corresponding to a sD-brane is identified and standard results in quantum field theory in curved space-time are used to compute the backreaction of the thermal background.Comment: 28 pages, 1 eps figure. Uses graphicx, setspace. v2:corrected typos, added references, clarified discussion on backreactio

    Construction of a biocompatible and antioxidant multilayer coating by layer-by-layer assembly of -carrageenan and quercetin nanoparticles

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    The present work aimed at the construction and characterization of a multilayer coating based on -carrageenan and quercetin-loaded lecithin/chitosan nanoparticles (Np) by the layer-by-layer technique and the evaluation of its antioxidant capacity and potential cytotoxicity in vitro. The multilayered coating was successfully self-assembled, as confirmed by UV-Vis spectroscopy, contact angle, atomic force microscopy (AFM), and scanning electron microscopy (SEM). Multilayered coatings showed to have antioxidant capacity, with a DPPH radical scavenging activity of 31.32±3.13% and a result of the FRAP assay of 799.41±95.39 M of ferrous ion (Fe2+) equivalent. These coatings were also shown to be devoid of cell toxicity, as evaluated by determination of nitric oxide production and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test. The alveolar macrophages culture was tested in the presence of the -carrageenan/quercetin-Np multilayer coating and showed a cell viability of 91.3±9.6%. These results suggest that this multilayered coating is adequate for surfaces modification in view of biomedical and food industry applications.This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors would also like to thank the Brazilian Government for support given by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Carneiro-daCunha, M.G. expresses her gratitude to the CNPq for research grant.info:eu-repo/semantics/publishedVersio

    Development of galactomannan-based films from Cassia grandis for the immobilization of biomolecules: physicochemical characterization

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    Galactomannans are polysaccharides formed by a β(1 4)-D-mannan backbone attached to α(1 6)- D-galactose units. They are commonly extracted from leguminous seeds and used as alternative sources for the production of films. Lactoferrin (Lf), bioactive peptides (BAPs), and phytosterols are biomolecules with functional properties and potential immobilization into films. The use of galactomannan films as immobilization systems is unexplored and emerges as an alternative for the incorporation of biomolecules for several biotechnological applications. This work aims evaluating the effect of different concentrations of LF, BAPs and phytosterols on the properties of galactomannan films obtained from Cassia grandis seeds. Colour parameters (L*, a* and b*) and opacity were determined using a digital colorimeter. Solubility in water was expressed as percentage of the film dry matter solubilized after 24 h immersion in distilled water and water vapour permeability (WVP) was determined gravimetrically based on ASTM E96-92 method. Contact angle (CA) was measured by the sessile drop method and mechanical properties were measured using a texture analyzer following the guidelines of ASTM D882-02. All the studied films had a strong whiteness tendency. The presence of Lf increased (p<0.05) the redness appearance of the films, even considering their evident yellowness tendency. All the studied films presented low opacity values (ranged between 11.53±0.15 and 12.37±0.16), however the films with immobilized phytosterols were more opaque than the other films. Solubility values decreased with the addition of Lf, while the incorporation of BAPs and phytosterols did not lead to statistical differences (p>0.05) between the films. The presence of Lf and phytosterols significantly increased the WVP values, leading to values 3.9 and 1.7-fold higher than the control film, respectively. Lf and BAPs increased (p<0.05) the CA values when compared to the results of the control film. Young′s modulus and tensile strength increased with the addition of biomolecules, improving the stiffness of the films, while the control films were more flexible due to the highest values of elongation at break. Galactomannan-based films from C. grandis showed to be a promising structure for the immobilization of biomolecules foreseeing a great number of possible applications in food and pharmaceutical industries

    Optimized extraction of a lectin from Crataeva tapia bark using AOT in isooctane reversed micelles

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    Crataeva tapia bark lectin was extracted from a crude extract into a reversed micelle phase of the anionic surfactant AOT in isooctane and back-extracted, to a final aqueous phase by addition of butanol. The effects of pH, ionic strength and surfactant concentration on the protein transfer process from the aqueous to the organic phase were characterized, being the best results obtained after 5 min of contact, under agitation, between the two phases, at pH 5.5 (10 mM citrate-phosphate buffer), 30 mM NaCl, and 5 mM AOT. Recovery to a new aqueous phase was performed with 5 min of contact, under agitation, 10 mM citrate-phosphate buffer at pH 5.5, 500 mM KCl and 5% of butanol. The overall yield obtained for the process was 80% for lectin activity and 56% for protein recovery. The efficiency of the process was confirmed by SDS-PAGE analysis.ALFA/VALNATURA; CNPq
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