978 resultados para Physical and chemical characteristics


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De-inking sludge can be converted into useful forms of energy to provide economic and environmental benefits. In this study, pyrolysis oil produced from de-inking sludge through an intermediate pyrolysis technique was blended with biodiesel derived from waste cooking oil, and tested in a multi-cylinder indirect injection type CI engine. The physical and chemical properties of pyrolysis oil and its blends (20 and 30 vol.%) were measured and compared with those of fossil diesel and pure biodiesel (B100). Full engine power was achieved with both blends, and very little difference in engine performance and emission results were observed between 20% and 30% blends. At full engine load, the brake specific fuel consumption on a volume basis was around 6% higher for the blends when compared to fossil diesel. The brake thermal efficiencies were about 3-6% lower than biodiesel and were similar to fossil diesel. Exhaust gas emissions of the blends contained 4% higher CO2 and 6-12% lower NOx, as compared to fossil diesel. At full load, CO emissions of the blends were decreased by 5-10 times. The cylinder gas pressure diagram showed stable engine operation with the 20% blend, but indicated minor knocking with 30% blend. Peak cylinder pressure of the 30% blend was about 5-6% higher compared to fossil diesel. At full load, the peak burn rate of combustion from the 30% blend was about 26% and 12% higher than fossil diesel and biodiesel respectively. In comparison to fossil diesel the combustion duration was decreased for both blends; for 30% blend at full load, the duration was almost 12% lower. The study concludes that up to 20% blend of de-inking sludge pyrolysis oil with biodiesel can be used in an indirect injection CI engine without adding any ignition additives or surfactants.

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Waste cooking oils can be converted into fuels to provide economical and environmental benefits. One option is to use such fuels in stationary engines for electricity generation, co-generation or tri-generation application. In this study, biodiesel derived from waste cooking oil was tested in an indirect injection type 3-cylinder Lister Petter biodiesel engine. We compared the combustion and emission characteristics with that of fossil diesel operation. The physical and chemical properties of pure biodiesel (B100) and its blends (20% and 60% vol.) were measured and compared with those of diesel. With pure biodiesel fuel, full engine power was achieved and the cylinder gas pressure diagram showed stable operation. At full load, peak cylinder pressure of B100 operation was almost similar to diesel and peak burn rate of combustion was about 13% higher than diesel. For biodiesel operation, occurrences of peak burn rates were delayed compared to diesel. Fuel line injection pressure was increased by 8.5-14.5% at all loads. In comparison to diesel, the start of combustion was delayed and 90% combustion occurred earlier. At full load, the total combustion duration of B100 operation was almost 16% lower than diesel. Biodiesel exhaust gas emissions contained 3% higher CO2 and 4% lower NOx, as compared to diesel. CO emissions were similar at low load condition, but were decreased by 15 times at full load. Oxygen emission decreased by around 1.5%. Exhaust gas temperatures were almost similar for both biodiesel and diesel operation. At full engine load, the brake specific fuel consumption (on a volume basis) and brake thermal efficiency were respectively about 2.5% and 5% higher compared to diesel. Full engine power was achieved with both blends, and little difference in engine performance and emission results were observed between 20% and 60% blends. The study concludes that biodiesel derived from waste cooking oil gave better efficiency and lower NOx emissions than standard diesel. Copyright © 2012 SAE International.

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In the present work, the physical and chemical characteristics of the fruit of the oily palm coming from the river basin of the Manitf (Region Loreto - Peru) were studied. Also, the fractionation of the palm oil and the interesterification of mixtures of palm oil/estearin was carried out. Physico- chemical properties of the crude oil and of the products obtained and fatty acids were analysed by gas chromatography The level of saturated fatty acids increased from 51,17% in the palm oil to 54,31% in the stearin. The best products for the food industry were the interesterified samples as they had melting points close to 37 degrees C.

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Continuing our series of papers on the three-dimensional (3D) structure and accurate distances of planetary nebulae (PNe), we present here the results obtained for PN NGC 40. Using data from different sources and wavelengths, we construct 3D photoionization models and derive the physical quantities of the ionizing source and nebular gas. The procedure, discussed in detail in the previous papers, consists of the use of 3D photoionization codes constrained by observational data to derive the 3D nebular structure, physical and chemical characteristics, and ionizing star parameters of the objects by simultaneously fitting the integrated line intensities, the density map, the temperature map, and the observed morphologies in different emission lines. For this particular case we combined hydrodynamical simulations with the photoionization scheme in order to obtain self-consistent distributions of density and velocity of the nebular material. Combining the velocity field with the emission-line cubes we also obtained the synthetic position-velocity plots that are compared to the observations. Finally, using theoretical evolutionary tracks of intermediate-and low-mass stars, we derive the mass and age of the central star of NGC 40 as (0.567 +/- 0.06) M(circle dot) and (5810 +/- 600) yr, respectively. The distance obtained from the fitting procedure was (1150 +/- 120) pc.

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The strawberry is as non-climacteric fruit, but has a high post-harvest respiration rate, which leads to a rapid deterioration at room temperature. This study aimed to evaluate the application of biodegradable coating on postharvest conservation of organic strawberries, cv. Camarosa, packed in plastic hinged boxes and stored at 10ºC. The treatments consisted of: a) control; b) 2% cassava starch; c) 1% chitosan; and d) 2% cassava starch + 1% chitosan. Physical and chemical characteristics of fruits were evaluated at 3, 6 and 9 days of storage, and microbiological and sensory analyses were carried out at the end of the storage period. The treatments influenced positively the post-harvest quality of organic strawberries. The coating cassava starch + chitosan provided the best results, with less than 6% of loss in fruit mass, lower counts of yeast and psychrophilic microorganisms and the best appearance according to the sensory analysis.

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Lakes play an important role in biogeochemical, ecological and hydrological processes in the river-floodplain system. The aim of this study was to evaluate the dynamics of the limnological conditions of Catalão Lake, an Amazon floodplain lake. Thus, some of the main limnological environment variables (O2, temperature, pH, nutrient, electrical conductivity) of the Catalão Lake were analyzed under temporal and spacial scales. The study was conducted between November/2004 and August/2005. Sampling excursion were carried out every three months; one excursion for each of the four different hydrological periods (low water, rising water, high water and falling water). Sampling points were chosen so that it could be obtained a gradient of the distance from Negro River. Limnological profiles in Catalão Lake showed generally acidic to slightly alcaline water, with low levels of dissolved oxygen and low concentrations of soluble reactive phosphorous. The Negro River seems to exert the main influence during the rising water period, while the Solimões River is the principal controlling river during peak water. The Principal Component Analysis (PCA) grouped the seasonal collections by hydrological period, showing the formation of a north-south spatial gradient within the lake in relation to the limnological variables. Multivariate dispersion analysis based on distance-to-centroid method demonstrated an increase in similarity over the course of the hydrological cycle, as the lake was inundated in response to the flood pulse of the main river channels. However, the largest spatial homogeneity in the lake was observed in the epilimnion layer, during the falling water period. The daily analysis of variation indicated an oligomitic pattern during the years in which the lake was permanently connected to the Negro River. Although Catalão Lake receives large quantities of both black water from the Negro River and sediment-filled water from the Solimões River, the physical and chemical characteristics of the lake are more similar to those of the Solimões (várzea lake) than the Negro (blackwater lake).

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The thermal springs of Acquarossa and the nearby mineral springs of Soia have outlet temperatures of 12 degrees to 25 degrees C, TDS of 2290 to 3000 mg/kg and Ca-SO4 to Ca-SO4-HCO3 composition. Chemical geothermometers suggest reservoir temperatures close to 60 degrees C. P-CO2 values at depth are estimated to range from 0.3 to 2 bar. delta D and delta(18)O values indicate a meteoric origin and recharge elevations of 1600 +/- 150 m above sea level (a.s.l.) for these thermal and mineral waters. All these waters discharge from the overturned limb of the Simano nappe, probably dose to the contact between basement and underlying cover rocks. They therefore represent rain waters that descend slowly, heat at depth and locally rise relatively quickly to the surface, preserving part of their physical and chemical characteristics. (C) 1999 CNR. Published by Elsevier Science Ltd. All rights reserved.

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ABSTRACT Preservation of mangroves, a very significant ecosystem from a social, economic, and environmental viewpoint, requires knowledge on soil composition, genesis, morphology, and classification. These aspects are of paramount importance to understand the dynamics of sustainability and preservation of this natural resource. In this study mangrove soils in the Subaé river basin were described and classified and inorganic waste concentrations evaluated. Seven pedons of mangrove soil were chosen, five under fluvial influence and two under marine influence and analyzed for morphology. Samples of horizons and layers were collected for physical and chemical analyses, including heavy metals (Pb, Cd, Mn, Zn, and Fe). The moist soils were suboxidic, with Eh values below 350 mV. The pH level of the pedons under fluvial influence ranged from moderately acid to alkaline, while the pH in pedons under marine influence was around 7.0 throughout the profile. The concentration of cations in the sorting complex for all pedons, independent of fluvial or marine influence, indicated the following order: Na+>Mg2+>Ca2+>K+. Mangrove soils from the Subaé river basin under fluvial and marine influence had different morphological, physical, and chemical characteristics. The highest Pb and Cd concentrations were found in the pedons under fluvial influence, perhaps due to their closeness to the mining company Plumbum, while the concentrations in pedon P7 were lowest, due to greater distance from the factory. For containing at least one metal above the reference levels established by the National Oceanic and Atmospheric Administration (United States Environmental Protection Agency), the pedons were classified as potentially toxic. The soils were classified as Gleissolos Tiomórficos Órticos (sálicos) sódico neofluvissólico in according to the Brazilian Soil Classification System, indicating potential toxicity and very poor drainage, except for pedon P7, which was classified in the same subgroup as the others, but different in that the metal concentrations met acceptable standards.

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The objective of this experiment was to study the effects of soil management systems on the bulk density, chemical soil properties, and on the soil microbial activity on a Latossolo Vermelho distrófico (Oxisol). Soil samples were collected from plots under the following management conditions: a) natural dense "cerrado" vegetation (savanna); b) degraded Brachiaria decumbens pasture, 20 years old; c) no-tillage treatment with annual crop sequence (bean, corn, soybean and dark-oat in continuous rotation), 8 years old; d) conventional tillage treatment with crop residues added to the soil, and annual crop sequence, 10 years old. The continuous use of no-tillage system resulted in an increase in microbial biomass and decrease in soil basal respiration, therefore displaying evident long-term effects on the increase of soil C content. The no-tillage system also provided an improvement in bulk density and chemical properties of the soil. Hence, the no-tillage management system could be an alternative for the conservation and maintenance of physical and chemical conditions and the productive potential of "cerrado" soils.

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Yield and physical and chemical characteristics of 'Paluma' guava fruit were evaluated as a function of the harvest at different maturity stages, under influence of nitrogen and potassium fertilization, in Petrolina, State of Pernambuco, Brazil. Fertilizer rates were 67 kg N + 33 kg K2O, 133 kg N + 67 kg K2O, 200 kg N + 100 kg K2O and 267 kg N + 133 kg K2O per hectare. Fruits were evaluated at maturity stages 2, 3, 4 and 5, established according to peel color. Higher doses of N and K induced higher yields. Nevertheless, fertilization with 200 kg of N + 100 kg of K per hectare improved fruit quality, delaying ascorbic acid breakdown and conserving pulp firmness. Main changes took place at maturity stages 4 and 5, when the fruit should present ideal conditions for consumption, namely the increase on soluble solids and soluble sugars content.

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The sensory, physical and chemical characteristics of 'Douradão' peaches cold stored in different modified atmosphere packaging (LDPE bags of 30, 50, 60, 75µm thickness) were studied. After 14, 21 and 28 days of cold storage (1 ± 1 ºC and 90 ± 5% RH), samples were withdrawn from MAP and kept during 4 days in ambient air for ripening. Descriptive terminology and sensory profile of the peaches were developed by methodology based on the Quantitative Descriptive Analysis (QDA). The assessors consensually defined the sensory descriptors, their respective reference materials and the descriptive evaluation ballot. Fourteen individuals were selected as judges based on their discrimination capacity and reproducibility. Seven descriptors were generated showing similarities and differences among the samples. The data were analysed by ANOVA, Tukey test and Principal Component Analysis (PCA). The atmospheres that developed inside the different packaging materials during cold storage differed significantly. The PCA showed that MA50 and MA60 treatments were more characterized by the fresh peach flavour, fresh appearance, juiciness and flesh firmness, and were effective for keeping good quality of 'Douradão' peaches during 28 d of cold storage. The Control and MA30 treatments were characterized by the mealiness, the MA75 treatment showed lower intensity for all attributes evaluated and they were ineffective to maintain good quality of the fruits during cold storage. Higher correlation coefficients (positive) were found between fresh appearance and flesh firmness (0.95), fresh appearance and juiciness (0.97), ratio and intensity of fresh peach smell (0.81), as well as higher correlation coefficients (negative) between Hue angle and intensity of yellow colour (-0.91), fresh appearance and mealiness (-0.92), juiciness and mealiness (-0.95), firmness and mealiness (-0.94).

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The objective of this work was to determine the coefficients of sorption and desorption of picloram in Ultisol (PVA) and Oxisol (LVA), displaying different physical and chemical characteristics. Samples of soil were collected at the 0 20 cm depth in degraded pasture areas in Viçosa-MG. Firstly, the equilibrium time between the herbicide in solution and the herbicide which was sorbed in the soil was determined by the Batch Equilibrium method. The time required was 24 hours. Sorption and desorption studies were carried out under controlled laboratory conditions; the sorption evaluation consisted in adding 10.0 mL of herbicide solutions at different concentrations to tubes containing 2.00 g of soil, with vertical rotary agitation being maintained during the pre-determined equilibrium time. After centrifugation, supernatant extract cleaning and filtration, herbicide concentration was determined by high performance liquid chromatography (HPLC) with UV detection at 254 nm. Desorption was evaluated using the samples in the tubes after the sorption tests. The Freundlich model was used for interpretation of the sorption process. Ultisol showed higher adsorption coefficient (Kf a) compared with Oxisol, which may be attributed to the lower pH of the soil and its higher organic matter content. Desorption process occurred in both soils; the LVA allowed greater release of the previously sorbed molecules.

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The aim of this study was to evaluate the physical and chemical parameters of Williams pear, stored at 25 ºC for 15 days, with and without edible coating. Edible coatings prepared with alginate 2% and carrageenan 0.5% were tested. The analyses carried out on the samples were: weight loss, pH, soluble solids, firmness, and color. The edible coatings were characterized in terms of mechanical properties, permeability, thickness, and opacity. The results show that the application of edible coatings with carrageenan and alginate in pears influenced physical and chemical characteristics such as weight loss, pH, total soluble solids, color, and firmness of the fruit. However, the alginate coating showed the best results on pear conservation since it had lower water vapor permeability and greater tensile strength, and therefore it can be used as a protective film on these fruits.

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In many industrialized countries, including Brazil, sodium intake exceeds the nutritional recommendations. Excessive consumption is associated with hypertension and premature death by cardiovascular diseases. The industry's challenge is to produce products with reduced sodium that are similar to regular products in texture and flavor and consistent with consumers' dietary habits. The present study aimed at substituting 25 and 50% NaCl for KCl in marinated beef and chicken meat with the addition of aromatic herbs and spices. The following microbiological analyses were carried out: macronutrient, chemical composition, and sensorial analysis. The meats showed a reduction in NaCl contents without any changes in their physical and chemical characteristics, and the products´ quality and microbiological safety were maintained. Beef and chicken tenderness was maintained for both treatments. Furthermore, the use of 50% KCl did not cause any changes in the products' sensory quality, and the overall acceptance of both types of meat was maintained. Results showed that a reduction by 50% in the NaCl contents of marinated meat products with a combination of herbs and spices is possible. Future applications in other meat products and sausages are highly promising.

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Mixed flavor beverages represent a trend that is gaining the allegiance of potential fruit juice consumers. The present study proposed to prepare mixed flavor beverages and verify their consumer acceptance. Cajá beverage (sample A) was used as the standard. The other beverages were prepared by mixing the cajá-flavored product with other flavors: strawberry (B), pineapple (C), jabuticaba (D), mango (E) and cashew (F). The consumer profiles in the two regions studied were similar. Overall beverages B, A and F were the most accepted, with scores of 7.7, 6.4 and 6.2, respectively. Internal Preference Mapping showed that most of the consumers were located near beverages A, B and F, confirming the acceptance results. The consumers indicated appearance and flavor as the most appreciated characteristics in beverages A, B and F. Beverages A, B and F presented higher total soluble solids contents and viscosities than the other beverages. Consumer segmentation did not depend on the different levels of familiarity with the cajá flavor. Thus the preparation of mixed flavor beverages of cajá-strawberry and cajá-cashew is an excellent proposal because it presents flavors with good potential for marketing in different regions of Brazil.