998 resultados para Propriedades qualitativas de solucoes


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The behaviour of the non conserved and 98% glycerin conserved specimens for periods of 30, 60 and 90 days of bovine diaphragma's tendinous center, fibrous pericardium and parietal peritoneum submitted to mechanical tests of traction, was observed in ten bovines between 30 months and 36 months of age, crossbreeds, males and females, collecting fragments of these aforesaid membranes in each animal. The diaphragma's tendinous center and parietal peritoneum did not suffered significant modification (p>0.05) in the values of tension when compared to the resistance tests of traction of non conserved and 98% glycerin conserved membranes. However, all the evaluated tissues showed significant increase (p£0.05) of the elongation values when conserved in 98% glycerin for until 90 days. It was also observed that fibrous pericardium is the one which supports greaters tensions. So, it to was concluded, that glycerin is efficient to the conservation of biological membranes besides modifying its mechanical properties.

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The high rate of mineralization of organic matter on savannah soils, which is reached fi ve times faster than in temperate regions, leads us to the challenge of electing the best system of management that maintains and/or increase it in soil, guaranteeing its quality and sustainability. In this sense the present research aimed to study the effects of green, organic and mineral manure on the chemical properties on the chemical properties of an Oxisol, on Savannah area, cultivated with cotton (Gossypium hirsutum) under conventional tillage and no-tillage in the pasture fi eld (Brachiaria decumbens) for 20 years. The experimental design was a randomized block design with split plots. The main plots consisted of two treatments: conventional tillage and no-tillage, and the subplots of six treatments: control (no fertilizer), mineral fertilizer recommended for the crop, according to the soil chemical analysis, organic fertilizer (cattle manure - 20 t ha-1), organic fertilizer (cattle manure - 20 t ha-1) + 1/2mineral fertilization recommended according to the analysis of soil, green manure-1 (Crotalaria juncea) and green manure-2 (Pennisetum americanum). There were studied the following soil chemical properties: P, OM, pH, K, Ca, Mg, Al, Al + H, S, exchange capacity cations and base saturation. The soil samples for the analysis were performed on layers of 0,00-0,05 m, 0,05-0,10 and 0,10-0,20 m. Then it came the following conclusions: the fertilization interfere in soil chemical properties and the preparation did not interfere, the cattle manure and its association with the mineral fertilizer caused increasing level elements in the soil, Crotalaria juncea and Pennisetum americanum did not infl uence on soil chemical properties.

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The intensive use of the land for agricultural propose causes a series of modifications in attributes, which can take to soil degradation. In this context, the main goal of this research was to evaluate the influence of the soil tillage systems and management on its physical and hydric characteristics. The evaluations were carried out in July of 1999, at experimental plots of a Latossolo vermelho, a clay oxisoil, in the Faculdade de Engenharia Agrícola of the UNICAMP, at the county of Campinas, state of São Paulo. These plots were managed with the following treatments, along a period of eight years: no-tillage, chisel ploughing, conventional system with disk ploughing and revolving hoe. The evaluated physical and hydric parameters of the soil were: soil bulk density, particle density, total porosity, macro-porosity, micro-porosity, soil-water retention curve, hydraulic conductivity and basic infiltration. Significant differences were observed between the treatments on soil bulk density, infiltration, total porosity, macro-porosity and the micro-porosity. The chisel ploughing and no-tillage systems presented the higher values of soil bulk density; nevertheless in these conservationist systems were observed the higher values of basic infiltration.

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The oxygenation of human Hb (HbA) demands a three state model: two deoxy states To and Tx, free and complexed with anions respectively, and an oxy R state. The regulation between these states is modulated by the presence of anions, such as chloride, that binds to T state. The b inding if chloride, however, remains controversial. The aim of this work is the study of arginines 92a (a1ß2 interface) and 141a (C-terminal) as chloride binding sites. To investigate that, we have studied 92 and 141 site directed mutant species: natural mutants Hb J-Cape-Town (R92Q), desArg (R141Δ), Chesapeake (R92L), and the constructed Chesapeake desArg (R92L,141Δ). We expressed Hbs in Escherichia coli and purified. Through oxygen binding curves we measured affinity and cooperativity, in function of water effect and Bohr effect in presence and absence of chloride. Structural features were obtained through 1H NMR spectroscopy Oxygen binding properties and Bohr effect measured indicated a higher affinity and lower cooperativity in absence and presence of chloride for all mutants. Structural changes represent functional aspects of mutant Hbs, such as a significant rise in affinity or a change in cooperativity. Water activity studies conducted as a function of chloride concentration showed that the only Hb desArg follows the thre state model. The other mutant Hbs do not exhibit the Tx state, a fact confirmed by the number of water molecules bound to each Hb during the deoxy-oxy transition. This behavior suggests that the Arginine 92 site could be responsible for chloride binding to Hb, since oxygenation of 92 mutant Hbs cannot be adjusted by the three state model. However, Bohr effect showed that all mutant Hbs released~1 proton in chloride presence, different from HbA that releases ~2, suggesting a role for 141 arginine in the tertiary and quaternary Bohr effect.

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The objective of this research is to assess the influences of basal canker on wood properties for the kraft pulp production. The material consisted of seeded E. grandis trees classified into 4 levels of basal canker severity (0, 1, 2 and 3) and installed in three soil types classified by texture (AQ1 and AQ2 - 10 to 15% clay, and LEm2 - 26 to 35 clay). The sampling consisted of randomly selecting five trees for each for each canker severity level and soil type, totaling 60 trees (4 canker levels x 3 soil types x 5 trees). These trees were fallen and cut into sections at 0, 25, 50, 75 and 100% of the commercial height for the collection of disk and logs of wood. The results showed that the soil texture influences in the Eucalyptus canker severity and this fact should be considered when assessing the wood properties and their final destination. The texture of the soil and the severe levels of basal canker influence the wood properties, and therefore the kraft pulping.

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The rapid growth of agriculture, promoted by public government initiatives, favored an out of control deforestation of our forests; today, reforestation of permanent preservation areas are necessary for the conservation of our natural resources, and recovery of such areas are required by public laws. In an area of 5.26 acres of riparian reforestation in the savanna soil chemical properties were evaluated after twenty years of planting. It was analyzed the following variables: (P, organic matter (MO), pH, K, Ca, Mg, H+Al, Al and S) in 13 modules, with three replicas in two depths (0 - 20 and 20 - 40 cm) in a randomized block design in hierarchical scheme. Reforestation with tree species on the edge of Parana river in Selvíria (MS) contributes to chemical soil attributes, under riparian reforestation, as similar as a soil without human disturbance in this region; it is also possible to verify that forestry plantation promotes deposition of organic material which is essential for nutrient cycling, which keep the chemical properties of such soil in good condition for the establishment of riparian vegetation.

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The soybean culture is part of crop rotation used by irrigators from the southwestern region of São Paulo State that perform no-tillage soil management as a form of sustainable soil use. The objective of this work was to evaluate the effect of this conservationist practice on physicalhydric properties, soil compaction, root development, and soybean culture production components in relation to the conventional management. The experiment was conducted at the Buriti-Mirim Farm, Angatuba, SP, in Brazil, using an area irrigated by a center pivot system divided into two types of soil management: conventional and no-tillage. Although the no-tillage management presented higher soil density, lower water available and lower soil resistance to penetration, both soil managements showed no difference in relation to root development.

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The study aimed to assess the physical and physiological characteristics of soybean seeds collected in grain tank and the outlet of the discharge tube of the harvester, depending on the year and the forward speed of the harvester. The experimental design was completely randomized in a factorial 2 x 2 x 2 tested two harvesters of different years, two displacement's speeds and two locations of sample collection, totaling eight treatments with four replications. The harvest of soybean cv. COODETEC 217, was performed with two tangential harvesters, aged three and four years, with 900 rpm rotation of the cylinder, operating at forward speeds of 4 ± 0.5 km h-1 and 7 ± 0.5 km h-1. Seed samples (approximately 3 kg) were withdrawn at the grain tank and the outlet of the discharge tube of the harvester and subjected to determinations of water content in field and laboratory. Subsequently, we evaluated purity, mechanical damage, germination and seed vigor. The younger harvester had a higher percentage of pure seed and lowest percentage of inert material. The increase in forward speed provides the higher the bands percentage and reduction of percentages of pure seed and inert material. The percentage of inert material was higher for seeds collected in the discharge pipe. The speed increase has positively influenced the emergence in sand for the harvester oldest (4 years) and negatively to the harvester youngest (3 years). At lower speeds the youngest harvester higher percentage of germination in sand.

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The main purpose of this study was to analyze the modified physical properties of an educational resource for facilitating the handling of a child with dyskinetic cerebral palsy. The participant of the study was a six year old child with dyskinetic cerebral palsy enrolled in a regular early childhood education classroom. The educational resource that was selected was a brick game, in which the physical properties of weight, size and texture had been modified. The analysis was made regarding the quality of upper limb movement to the variables: righting index, scalar displacement (s), average speed (As) and time (t). The results showed that combined large size and heavy weight did not have a satisfactory outcome, affecting both grasping the educational resource and fitting. There was also inconsistency in children with cerebral palsy's responses. There is variation in the results, though a standard cannot be established. Thus, this study contributed to understanding the motor responses of a child with dyskinetic cerebral palsy when participating in a fitting activity with educational resources in which the physical properties had been modified.

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This study aimed to evaluate the carcass quantitative characteristics, tissue composition of carcass cuts and meat quality of lambs receiving sunflower seeds in the diet. Twenty-one lambs 7/8 Ile de France 1/8 Ideal, not castrated, with initial body weight of 17 kg were housed in individual pens and distributed in three diets (0,7.5 and 15% of sunflower seeds inclusion) in a completely randomized design in 3 x 2 factorial arrangement (three diets and two carcass cuts). At the end of the experimental period, the animals were slaughtered; weights and hot and cold carcass yields and commercial and biological carcass dressing were collected. The carcasses were split lengthways and left half carcass divided into six anatomical parts. The leg and loin were removed for evaluation of tissue composition, meat color, water holding capacity, cooking losses and shearing force. Difference was detected in the commercial carcass yield; with higher value (46.82% of total weight) for carcasses of lambs fed without sunflower seeds when compared with carcass yield (44.11%) of lambs fed with 15% of sunflower seed inclusion. The proportion of muscle and total fat, as muscle:fat ratio were affected (P<0.05) by feeding, with higher quantity of muscle (63.15%) and less fat (16.63%) in the leg and loin cuts of lambs fed without sunflower seeds. In the leg was observed higher proportions of muscle (67.27%), muscle:bone ratio (4.08) and muscle:fat ratio (4.92) when compared with the loin cut. The water retention capacity and shearing force of Longissimus lumborum muscle showed better results when compared with Semimembranosus muscle. The inclusion of sunflower seeds in the diet of feedlot lambs increased the fat deposition in carcass cuts, however did not affect the other parameters of meat quality.

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Corn cultivation is part of crop rotation used by irrigation farmers from the southwestern region of São Paulo state, Brazil, who use no-tillage soil management as a kind of sustainable use of soil. The effect of this conservative practice on physical and hydrical properties of the soil, root development and corn crop yield compared to the conventional management was the objective of this work. The experiment was held at the Buriti-Mirim Farm, Angatuba, SP, Brazil, using an irrigated area with a center pivot system and two types of soil management: conventional and no-tillage systems. Although the no-tillage management had higher soil density and less water availability, no significant difference was found for both management systems concerning soil resistance to penetration, root development and crop yield. In both systems of soil management, 90% of roots were concentrated in the first 0-20cm of soil layer.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)