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Search Results: 1 - 10 of 14412 matches for " Mauricio Moura Silveira "
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Influence of medium composition and pH on the production of polygalacturonases by Aspergillus oryzae
Malvessi, Eloane;Silveira, Mauricio Moura da;
Brazilian Archives of Biology and Technology , 2004, DOI: 10.1590/S1516-89132004000500004
Abstract: a liquid medium containing wheat bran, salts and a source of inducer (pectin) was found to be suitable for the production of exo- and endo-polygalacturonases by aspergillus oryzae cct3940. induction of polygalacturonases by purified pectin was significantly higher than when rinds of citrus fruits were used as inducer. a. oryzae growth was favoured by ph close to 4, although a drop of ph to around 3 was needed for enzymes production. afterwards, decreasing activities were observed with the normal increase in ph to near neutrality. the highest activities were achieved with an initial ph of 4 and controlled when it decreased to a value slightly below 3 (159 units endo-pg.ml-1 at 83 h and 45 units exo-pg.ml-1 at 64 h), being the loss in polygalacturonases activities strongly reduced at this condition. the best values of ph and temperature for the action of exo-pg (4.5/57oc) and endo-pg (4.3/40oc) were assessed.
Production and characterization of endo-polygalacturonase from Aspergillus niger in solid-state fermentation in double-surface bioreactor
Hendges, Diogo Henrique;Montanari, Queli;Malvessi, Eloane;Silveira, Mauricio Moura da;
Brazilian Archives of Biology and Technology , 2011, DOI: 10.1590/S1516-89132011000200005
Abstract: endo-polygalacturonase (endo-pg) production by aspergillus niger t0005/007-2 in solid medium with 170 mm of height was evaluated in a cylindrical double surface bioreactor in 96-h experiments. cell concentration close to 92 mg.g -1 dm (mg per g of dry medium) in the standard condition (static) was achieved, whereas in tests under forced aeration of 1.4 and 2.8 l.min-1. kg-1 mm (l of air per minute per kg of moist medium) and with the central shaft fungal biomass attained approximately 100 mg.g-1 dm. superior endo-pg activity was obtained with the central-shaft system, 78 u.g-1 dm (units per g of dry medium). forced aeration and pressure pulse showed no positive effect on the production of endo-pg, 45 u.g-1 dm and 28 u.g-1 dm, respectively. none of the conditions evaluated was efficient for medium temperature control. endo-pg was stable up to 40oc. the activity decreased in 50% after 120 minutes at 50oc, which is a temperature normally found during this process.
Cellulase and Xylanase Production by Penicillium echinulatum in Submerged Media Containing Cellulose Amended with Sorbitol
Carla Eliana Todero Ritter,Marli Camassola,Denise Zampieri,Mauricio Moura Silveira,Aldo José Pinheiro Dillon
Enzyme Research , 2013, DOI: 10.1155/2013/240219
Abstract: The present work investigated the use of sorbitol as a soluble carbon source, in association with cellulose, to produce cellulases and xylanases in submerged cultures of Penicillium echinulatum 9A02S1. Because cellulose is an insoluble carbon source, in cellulase production, there are some problems with rheology and oxygen transfer. The submerged fermentations containing media composed of 0, 0.25, 0.5, 0.75, and 1% (w/v) sorbitol and cellulose that were added at different times during the cultivation; 0.2% (w/v) soy bran; 0.1% (w/v) wheat bran; and a solution of salts. The highest filter paper activity (FPA) ( ?IU·mL?1) was obtained on the seventh day in the medium containing 0.5% (w/v) sorbitol and 0.5% (w/v) cellulose added 24 h after the start of cultivation. However, the CMCases showed an activity peak on the sixth day ( ?IU·mL?1) in the medium containing 0.75% (w/v) sorbitol and 0.75% (w/v) cellulose added after 12 h of cultivation. The xylanases showed the highest activity in the medium with 0.75% (w/v) sorbitol and 0.25% (w/v) cellulose added 36 h after the start of cultivation. This strategy enables the reduction of the cellulose concentration, which in high concentrations can cause rheological and oxygen transfer problems. 1. Introduction Lignocellulosic biomass has been projected to be one of the main resources for economically attractive bioethanol production, and enzymatic hydrolysis is the most potent alternative process for the saccharification of its polymers. Cellulase is an enzyme complex capable of hydrolyzing cellulose into glucose molecules [1], and xylanases degrade xylan, the main carbohydrate present in some hemicelluloses, into xylose [2]. Although cellulases and xylanases have several industrial uses, the greatest potential use of these enzymes is in the enzymatic hydrolysis of lignocellulosic materials to produce second-generation ethanol [3]. The cellulase complex has three major hydrolases: the endo- -1,4-glucanases (EG I, EG II, EG III, EG IV, and EG V; EC 3.2.1.4), which hydrolyze the glucosidic bonds randomly in cellulose fiber; the exo- -1,4-glucanases or cellobiohydrolases (CBH I and CBH II; EC 3.2.1.91), which act on the reducing and nonreducing ends of polymers, releasing cellobiose; and the -1,4-glucosidases (BG I and BG II; EC 3.2.1.21), which hydrolyze oligosaccharides and cellobiose into glucose [4]. The xylanolytic complex capable of hydrolyzing xylan is usually composed of several enzymes, such as -1,4-endoxylanase, -xylosidase, -L-arabinofuranosidase, -glucuronidase, acetyl xylan esterase, and the phenolic,
Activity of glucose-fructose oxidoreductase in fresh and permeabilised cells of Zymomonas mobilis grown in different glucose concentrations
Erzinger, Gilmar Sidnei;Silveira, Mauricio Moura da;Costa, José Paulo Castilho Lopes da;Vitolo, Michele;Jonas, Rainer;
Brazilian Journal of Microbiology , 2003, DOI: 10.1590/S1517-83822003000400008
Abstract: previously grown cells of the ethanologenic bacterium zymomonas mobilis produce sorbitol and gluconic acid, in reactions catalysed by the periplasmic enzymes glucose-fructose oxidoreductase (gfor) and glucono-d-lactonase (gl). the gfor/gl system activity, in cells to be used in this bioconversion, depends on growth conditions. in batch runs, with initial glucose concentrations (s0) from 42 to 230 g/l, the highest specific and total gfor/gl activities were obtained with s0 = 153 g/l (12.6 u/g cells and 62 u/l). higher s0 led to decreasing activities in fresh cells. with s0 = 209 g/l, the final specific activity was only 7.0 u/g. after disruption of cells, however, an activity over 15 u/g was revealed. since growth inhibition with s0 over 153 g/l was observed in batch mode, fed-batch runs, equivalent to a batch of 230 g/l, were done. although no growth inhibition occurred in fed-batch cultivation, enzyme activity remained low (5.2 u/g). a further fed-batch experiment, carried out under low pressure to remove ethanol from the medium, resulted in a specific activity of 9.8 u/g and a total activity of 68.7 u/l. these results indicate that the low gfor/gl activities in z. mobilis cells grown on higher s0 were due to changes in the cell wall, caused by high concentration of ethanol, that hindered the transport of the substrate to the intracellular enzymes in biconversion runs. this conclusion was confirmed by bioconversion runs with cells cultivated under different conditions.
Varia??o espacial como mecanismo promotor da coexistência em comunidades de insetos necrófagos
Moura, Mauricio O.;
Revista Brasileira de Zoologia , 2004, DOI: 10.1590/S0101-81752004000300001
Abstract: coexistence in local communities could be mediated through several mechanisms such as interespecific competition, temporal and spatial heterogeneity. in this paper we analyse a highly diverse guild of necrophagous insects to determine the role played by aggregation on community structure. an experiment was designed to test predictions derived from aggregation model of coexistence that in short require that in the balance between intra and interespecific competition, the first one must be greater than interespecific competition in order to make coexistence more likely. the data gathered comprise two protocols: collecting adults visiting carcasses and rearing maggots collected from carcasses. the results showed a total of 21 necrophagous species reared and 18 collected. all species showed clumped patterns of distribution over resources and even though several negative values were found in association indices, the overall trend was a neutral covariation between species. the analysis also confirms that aggregation could maintain diversity in this community.
Abiotic correlates of temporal variation of Hypsiboas leptolineatus (Amphibia: Hylidae)
Hiert, Cristiane;Moura, Mauricio Osvaldo;
Zoologia (Curitiba) , 2010, DOI: 10.1590/S1984-46702010000500006
Abstract: studies of anuran population dynamics are key to uncovering the mechanisms responsible for temporal fluctuations in abundance and those that shape population structure. population structure and population fluctuations can result from species specific demographic and behavioral characteristics, reproductive microhabitat availability (which is influenced by local environment and climate), as well as from responses to populations of other, sympatric species. in view of this, our study aimed to ascertain the temporal trends in a population of hypsiboas leptolineatus, to describe how abundance changes between seasons, and to uncover the effects of environmental variables in shaping seasonal variations in abundance. although h. leptolineatus occurs throughout the year, abundance showed a clear seasonal pattern linked to an interaction between temperature, relative air humidy, and moon phase.
Avalia o de programas e políticas públicas
Fagundes, Helenara Silveira,Moura, Alessandra Ballinhas de
Textos & Contextos (Porto Alegre) , 2009,
Abstract: A necessidade de conhecer do ser humano está diretamente vinculada ao seu desejo de compreender, explicar, julgar e alterar o real. A natural curiosidade humana direciona o pensamento a um julgamento de valor. é certo que qualquer forma de avalia o envolve necessariamente um julgamento, vale dizer, trata-se precipuamente de atribuir um valor, uma medida de aprova o ou desaprova o a uma política ou programa público. O processo avaliativo deve ser um tema de estudo constante frente à demanda colocada na realidade, onde as políticas públicas devem responder às necessidades da popula o, implantando e implementando a es com qualidade. O presente artigo pretende contextualizar a evolu o do processo de avalia o e analisar os aspectos metodológicos que devem ser utilizados nos programas e políticas públicas, enfatizando os modelos analíticos de efetividade, eficácia e eficiência.
Crescimento pró-pobre: análise dos estados brasileiros entre 1995 e 2007
Pinto, Mauricio Silveira;Oliveira, Julio Cesar de;
Revista de Economia Contemporanea , 2010, DOI: 10.1590/S1415-98482010000200005
Abstract: this article analyzes the pro-poor growth in the 27 brazilian states between 1995 and 2007. initially, it examines the recent literature about the subject and presents three indicators to quantify the relationship among growth, inequality and poverty. following, it calculates, through panel data analysis, the growth elasticity of poverty in brazil and across its states. finally, it estimates growth incidence curves (gic) and rates of pro-poor growth (rppg) for three periods: 1995-2007, 1995-2001 and 2001-2007. the results show that poverty has been rapidly diminishing in brazil since 2001, but there is still a huge discrepancy among some states and regions. moreover, there comes up a clear difference between the headcount index and the "deepness" of poverty.
New bird records from Lagoa do Peixe National Park, southern Brazil
Mauricio da Silveira Pereira,Filipe Poerschke
Biotemas , 2010,
Abstract: The Lagoa do Peixe National Park, situated on the coastal plain of the state of Rio Grande do Sul, had its avifauna investigated initially in the 1970s and 1980s, and the first published list of the species of the park appeared in 1995. Several following papers reported the occurrence of additional species in the park, resulting in a total of 211 species known in the area. The present note adds 19 species to the list of birds of the park, increasing the known richness of its avifauna to 230 species. Three of these (Tachybaptus dominicus, Buteo albicaudatus and Petrochelidon pyrrhonota) are also new records for the entire Mostardas peninsula, the long and narrow sand ridge separating the Patos lagoon from the Atlantic Ocean.
Mobile Robot Indoor Autonomous Navigation with Position Estimation Using RF Signal Triangulation  [PDF]
Leonimer Flávio de Melo, Jo?o Mauricio Rosário, Almiro Franco da Silveira Junior
Positioning (POS) , 2013, DOI: 10.4236/pos.2013.41004
Abstract: In the mobile robotic systems a precise estimate of the robot pose (Cartesian [x y] position plus orientation angle theta) with the intention of the path planning optimization is essential for the correct performance, on the part of the robots, for tasks that are destined to it, especially when intention is for mobile robot autonomous navigation. This work uses a ToF (Time-of-Flight) of the RF digital signal interacting with beacons for computational triangulation in the way to provide a pose estimative at bi-dimensional indoor environment, where GPS system is out of range. It’s a new technology utilization making good use of old ultrasonic ToF methodology that takes advantage of high performance multicore DSP processors to calculate ToF of the order about ns. Sensors data like odometry, compass and the result of triangulation Cartesian estimative, are fused in a Kalman filter in the way to perform optimal estimation and correct robot pose. A mobile robot platform with differential drive and nonholonomic constraints is used as base for state space, plants and measurements models that are used in the simulations and for validation the experiments.
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