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Search Results: 1 - 10 of 489385 matches for " Rubens A. Oliveira "
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Effect of Ultrasound and Xylanase Treatment on the Physical-Mechanical Properties of Bleached Eucalyptus Kraft Pulp  [PDF]
Larisse A.R. Batalha, Juliana C. da Silva, Carolina M. Jardim, Rubens C. Oliveira, Jorge L. Colodette
Natural Resources (NR) , 2011, DOI: 10.4236/nr.2011.22017
Abstract: The modification on the fiber structure of bleached eucalyptus kraft pulp is a very attractive alternative for improve- ments in the properties of paper production. The enzymatic treatment by xylanases and ultrassonic treatments modify the characteristics of the fibers, has been reported. Therefore, the purpose of this study was to evaluate the influence of ultrasonic waves as a facilitator of the action of enzymes (hemicellulase) by modifying the physicochemical nature of fiber eucalyptus Kraft pulp, in order to improve the physical and mechanical properties of the paper. But it was observed the that idea of ultrasound acts as facilitator for action of enzymes can’t be affirmed, since in most properties XA-1 and XA-2 were equal statistically. It may be noted that the junction of ultrasound and xylanase provided improves on tensile index, specific elastic modulus and tensile energy absorption and a decrease of tear index on the mechanical properties of handsheet and it increased the opacity when the ultrasound was applied before xylanase.
Obstru o e uniformidade de aplica o em sistemas de irriga o por gotejamento aplicando-se efluente da suinocultura Clogging and uniformity of application in drip irrigation systems operating with swine wastewater
Rafael O. Batista,Rubens A. Oliveira,Delfran B. dos Santos,Adriana de F. M. Oliveira
Revista Brasileira de Engenharia Agrícola e Ambiental , 2013,
Abstract: Neste trabalho buscou-se analisar o efeito de diferentes manejos de água residuária de suinocultura e de água de abastecimento na obstru o de emissores e na uniformidade de aplica o de sistemas de irriga o por gotejamento. O experimento foi realizado na Universidade Federal de Vi osa (UFV) e montado em esquema de parcelas subsubdivididas tendo, nas parcelas, os manejos (1E3A - uma hora de aplica o de efluente mais três horas de aplica o de água limpa, 2E2A - duas horas de aplica o de efluente mais duas horas de aplica o de água limpa, 3E1A - três horas de aplica o de efluente mais uma hora de aplica o de água limpa e 4E - quatro horas de aplica o de efluente), nas subparcelas os tipos de gotejador (G1, G2 e G3) e, nas subsubparcelas, os tempos das avalia es (0, 20, 40, 60, 80, 100, 120, 140 e 160 h) em delineamento inteiramente casualizado com três repeti es. Os resultados obtidos indicaram que na água residuária de suinocultura as características sólidos suspensos, ferro total e popula o bacteriana, representaram risco severo de entupimento de gotejadores e que houve redu o elevada da uniformidade de aplica o de efluente quando o tempo de aplica o de água residuária foi igual ou superior ao da água de abastecimento. This study aimed to evaluate the effect of different managments of swine wastewater and clean water on clogging of emitters and application uniformity of drip irrigation systems. The experiment was conducted in the experimental area of the Federal University of Vi osa (UFV) and mounted in a split split-plots, having in the plots the managments (1E3A - one hour of application of effluent and three hours of application of clean water, 2E2A - two hours of application of effluent and two hours of application of clean water, 3E1A - three hours of application of effluent and one hour of application of clean water and 4E - four hours of application of effluent), in the subplots the types of drippers (G1, G2 and G3) and in the subsubplots the evaluation times (0, 20, 40, 60, 80, 100, 120, 140 and 160 h) in a completely randomized design with three replications. The results indicated that in the swine wastewater the characteristics suspended solids, total iron and bacterial population represented severe risk of clogging of drippers; and that there was a high reduction of the uniformity of application of effluent when the time of application of wastewater is equal to or greater than the water supply.
Effect of the application of different water depths and nitrogen and potassium doses on quality of Tanzania grass
Oliveira Filho, Jair da C.;Oliveira, Rubens A. de;Oliveira, Ednaldo M. de;Cecon, Paulo R.;Martins, Carlos E.;
Engenharia Agrícola , 2012, DOI: 10.1590/S0100-69162012000400007
Abstract: the objective of this study was to evaluate the effects of the application of different water depths and nitrogen and potassium doses in the quality of tanzania grass, in the southern of the state of tocantins. the experiment was conducted on strips of traditional sprinklers, and used, as treatments, a mixture of fertilizer combinations of n and k2o always in the ratio of 1 n:0.8 k2o. this study determined throughout the experiment: plant height (ph), the crude protein (cp) and neutral detergent fiber (ndf). the highest plant height obtained was 132.4 cm, with a fertilizer dose of 691.71 kg ha-1 in the proportion of n:0.8 k2o, in other words, 384.28 kg ha-1 of n and 307.43 kg ha-1 of k2o, and water depth of 80% of the etc. the highest crude protein content was 12.2%, with the fertilizer dose application of 700 kg ha-1 yr-1 in the proportion of 1 n to 0.8 of k2o, in other words, 388.89 kg ha-1 of n and 311.11 kg ha-1 of k2o and absence of irrigation. the lowest level of neutral detergent fiber was 60.7% with the application of the smallest dose of fertilizer and highest water depth. it was concluded in this study that there was an increase in plant height by increasing the fertilizer dose and water depth. the crude protein content increased 5.4% in the dry season, by increasing the fertilizer dose and water depth. in the dry season, there was an increase of ndf content by 4.5% by increasing the application of fertilizer and water depth.
Influência de um polímero hidroabsorvente sobre a reten??o de água no solo
Oliveira, Rubens A. de;Rezende, Lucimar S.;Martinez, Mauro A.;Miranda, Glauco V.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2004, DOI: 10.1590/S1415-43662004000100023
Abstract: the objective of this research was to evaluate the effect of the concentration of a hydrogel polymer on the water retention characteristics of a sandy clay loam and a clay soil. water retention curves were obtained for the two soils and for a mixture of these soils with the terracottem? at 0.01, 0.05, 0.10, 0.15 and 0.20 dag kg-1 concentrations. the evaluation of the changes in water retention characteristics was done considering the values of the total water availability (twa), field capacity and the wilting point. for both soils, there was no effect of the hydrogel polymer concentration on the water retention when the matric potentials were less than -1.0 mpa. however, for matric potentials higher than -1.0 mpa, the water retention increased as the concentration of the hydrogel polymer in the mixture increased. the hydrogel polymer, at 0.20 dag kg-1 concentration, increased the water retention, at the 0.03 mpa matric potential, by 41% for the sandy clay loam and 37% for the clay soils, when compared to the soils without hydrogel polymer (control treatment) and increment in the available water retention made the twa of the two soils to increase by 123 and 135%, respectively.
Avalia??o de métodos de estimativa da evapotranspira??o horária para alface cultivada em sistema hidrop?nico em ambiente protegido
Moura, Carlos R. W.;Zolnier, Sérgio;Ribeiro, Aristides;Oliveira, Rubens A. De;
Engenharia Agrícola , 2010, DOI: 10.1590/S0100-69162010000400009
Abstract: the objective of this work was to evaluate the precision and accuracy of different methods for estimating hourly values of evapotranspiration (etc) for hydroponic lettuce under protected environment conditions. to determine the necessary parameters for different estimating methods, and their subsequent validation, two sets of experimental data were obtained from measurements carried out with cultivars grand rapids, regina and great lakes. evapotranspiration estimates were conducted with the following methods: penman-monteith parameterized by fao in 1998 (pmf); penman-monteith modified for aerodynamic characteristics in protected environment (pmap); simplified penman-monteith (pmaps); priestley-taylor (pt); solar radiation (rs) and simplified solar radiation (rss). the results demonstrated that the pmap and pmaps methods allowed better estimates of the hourly values of etc, both in the morning and in the afternoon period.
Fungicidas, doses e volumes de calda no controle químico da ferrugem da folha da aveia (Puccinia coronata f. sp. avenae)
Oliveira, Ana R. de;Boller, Walter;Forcelini, Carlos A.;Blum, Rubens;Lopes, André;
Engenharia Agrícola , 2007, DOI: 10.1590/S0100-69162007000200008
Abstract: crown rust (puccinia coronata f. sp. avenae) is the most important disease of oats in brazil. in susceptible oat cultivars, fungicides are needed to control the disease efficiently. however, spray at low volumes may reduce fungicide performance significantly. a field experiment with the oat cultivar upfa-20 was carried out at the famv/upf to evaluate the influence of fungicides, rates, and spray volumes on the efficacy of the chemical control for crown rust. the tested treatments combined two fungicides (tebuconazole, folicur, 0,75 l ha-1; epoxiconazole + pyraclostrobin, opera, 0,5 l ha-1), four rates (40; 60; 80 and 100% of the commercial rate), and two spray volumes (100 and 200 l ha-1). the field plots were arranged according to a factorial block design (2′4′2) with four replicates. the assessments included the disease severity, disease control, grain quality and grain yield. the net profit of each treatment was also determined based upon the application costs and the sale price of oats at the harvest. at the same rate, for both fungicides, the volume of 200 l ha-1 provided better disease control. at this volume, the 50% rate controlled crown rust as good as the full (100%) rate with 100 l ha-1. the net profit differed between fungicides but not for spray volumes. the rate effects were fungicide dependent.
Desempenho do irrigametro na estimativa da evapotranspira??o de referência
Oliveira, Rubens A.;Tagliaferre, Cristiano;Sediyama, Gilberto C.;Materam, Franklin J. V.;Cecon, Paulo R.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2008, DOI: 10.1590/S1415-43662008000200009
Abstract: the objective of this work was to test the "irrigametro" to estimate the reference evapotranspiration in comparison to the penman-monteith method - fao 56, and to compare its potential with the modified methods of penman - fao 24, radiation - fao 24, class a pan and hargreaves-samani (1985). the irrigameter is an evapo-pluviometric apparatus recently developed at the federal university of vi?osa to be used in irrigation water management. the reference evapotranspiration data obtained from the apparatus are compared with the data obtained from the method of penman-monteith, in intervals of one, three, five and seven days. according to the results, the irrigameter presented satisfactory data to estimate eto in all time intervals studied. its low cost, high practicairty and inexistence of any additional calculations make it very suitable for irrigation water management in agriculture. the methods of modified penman, radiation and hagreaves-samani overestimated the eto values obtained by the method of penman-monteith, while the class a pan presented the opposite behavior.
Perda de carga em tubula??o de polietileno, conduzindo água residuária de suinocultura
Tagliaferre, Cristiano;Oliveira, Rubens A. de;Denículi, Wilson;Cecon, Paulo R.;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2006, DOI: 10.1590/S1415-43662006000300003
Abstract: the objective of this work was to adjust equations to calculate continuous head loss in polyethylene pipelines carrying swine wastewater with concentrations of 1.15; 1.24; 1.43 and 1.75 g l-1 of total solids. the head loss was determined in polyethylene pipelines, with internal diameters of 12.62; 15.47; 19.79 and 25.76 mm, by means of four piezometers, 4 m apart along the pipelines. the results indicated that the empirical equations adjusted with the methodologies of duffy & titchener and hazen-williams modified gave good results with coefficient of determination equivalent to 0.99, therefore, its application is recommended to design of projects with polyethylene pipelines.
Anti-mitotic activity towards sea urchin eggs of dichloromethane fraction obtained from Allamanda schottii Pohl (Apocynaceae)
Sousa, Louisa M. A.;Monte Neto, Rubens L.;Schmidt, Dionezine F. Navarro;Oliveira, Márcia R.;
Revista Brasileira de Farmacognosia , 2009, DOI: 10.1590/S0102-695X2009000300002
Abstract: allamanda (apocynaceae) is a genus of climbing shrubs known for producing compounds with a range of biological activities. previous works have shown the anti-proliferative effect of the ethanolic extract of allamanda schottii on leukemic cells. the present work was conducted to evaluate the effects of dichloromethane fraction, obtained from allamanda schottii, on sea urchin echinometra lucunter eggs, as a multicellular model for evaluating anti-tumor activity. our results show an inhibition of sea urchin development in a dose-dependent manner in the presence of dichloromethane fraction. the ic50 values for first and third cleavage and blastulae stage were 103.7 μg/ml, 33.1 μg/ml and 10.2 μg/ml, respectively. these results also demonstrate the cumulative effect of this fraction on sea urchin embryos. in the present work, the expressive anti-mitotic activity of dichloromethane fraction towards sea urchin eggs, a multicellular model, reinforces the anti-tumor potential of the allamanda schotti.
Efeitos da remo??o da túnica adventícia da aorta descendente em suínos
Fagundes, Almondi;Pereira, Adamastor Humberto;Corrêa, Rose Karina;Oliveira, Marília Teresa de;Rodriguez, Rubens;
Revista do Colégio Brasileiro de Cirurgi?es , 2012, DOI: 10.1590/S0100-69912012000200009
Abstract: objective: to investigate the effects of removal of the adventitia on the tunica media in a pig model. methods: the experiment was performed in eight pigs. the adventitia of the descending aorta was removed. following euthanasia, at two, four, six and eight weeks, the aortic segment was removed. next, slices of the aorta were stained with hematoxylin and eosin (he) and weigert - van gieson. results: after two weeks there was a slight cellular breakdown in the outer third of the media. after four weeks structural breakdown of elastic fibers was observed in the outer two thirds of the same layer. in six weeks, several areas of necrosis and almost complete disruption of elastic fibers were identified. finally, after eight weeks, there was fibrosis of the entire wall with disruption of the internal elastic lamina. conclusion: the removal of the adventitia leads to degeneration of the media, determining loss of the normal structure of the aortic wall that is variable in its location, intensity and shape, depending on the length and duration of the ischemic insult.
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