412 resultados para acidity in solids


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A study of the preconcentration of tioethers in air by means of the passage of gas flow on solid sorbents coated with sodium tetrachloropalladate was undertaken with the aim of achieving chemical fixation. This fixation presented high specificity and blocked the migration of the sorbed compound through the other active sites. The species obtained were selectively dissolved in organic solvents, resulting in the sulfur reduced compound concentration in the organic phase, which could be determined spectrophotometrically.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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An experimental study of fragmentation of brittle solids under the application of repeated impulsive force is made, emphasizing the behavior of the diversity of fragments. Several scaling relations involving diversity and number of fragments are obtained from experiments and the results are compared with computer simulations. © 1998 Elsevier Science B.V. All rights reserved.

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Introduction. Breeding studies for acerola (Malpighia glabra) improvement aim at obtaining plants that produce fruits with uniform chemical and physical attributes, including high levels of vitamin C, which can provision the market with fresh fruit and frozen pulp. High variability in fruit quality is observed in Brazilian acerola crops, especially those propagated by seeds. In this context, the objective of our research was to evaluate the physical and chemical characteristics of Brazilian acerola genotype fruits. Materials and methods. Sixteen acerola genotypes were studied in Jaboticabal, São Paulo State, Brazil. A completely randomized design with sixteen treatments and six replications was adopted. Each treatment was represented by one genotype. Several parameters related to fruit quality, such as width, length, weight, pulp percentage, soluble solids (SS), titratable acidity (TA), [SS / TA] ratio and vitamin C content, were evaluated in fruits of the acerola genotypes. The results were submitted to variance analyses, the Tukey test and cluster analysis. Results and discussion. There was a statistical difference between the acerola genotypes studied. Three of them stood out as natural sources of vitamin C. In spite of fruit size, two acerola genotypes were found to have potential for fresh fruit production. In a general form, genotypes that presented a high [SS / TA] ratio had low vitamin C content. Conclusion. The acerola genotypes studied in Jaboticabal presented high variability, forming eleven groups in relation to fruit quality parameters. © 2007 Cirad/EDP Sciences All rights reserved.

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Mangoes in the Brazilian semi-arid stands out in the national scenario due to high yields and fruit quality, and also to the possibility of all-year production taking advantage of the climatic conditions as well as management technique (irrigation, pruning and growth regulators application) for plant growth and blossom control. Paclobutrazol soil drench applied is normally used for production management of mangoes. This research deals with the evaluation of the effect of foliar applied growth regulators to mango, cultivar 'Kent', as regard to their efficiency for blossom management, in order to allow off season mango production. Three growth regulators (prohexadione-Ca, trinexapac-ethyl and chlormequat chloride) were foliar applied, at two dosages and compared to paclobutrazol applied as soil-drench. In order to compare the effects of the treatment, data were recorded related to panicle emission (percentage and length), period of time until blossom and production, yield (number and plant weight) and post-harvest quality of the fruit (total soluble solids, titratable acidity, pH, firmness, flesh and skin color and appearance). The results showed that prohexadione-Ca and chlormequat chloride induced a 15-day early harvest, while paclobutrazol, alone or combined with prohexadione-Ca, allow to harvest 25 days in advance, when compared to trinexapac-ethyl and control trees. Growth regulators foliar applied and paclobutrazol applied as soil-drench delayed mangoes fruit ripening in post-harvest.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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This work evaluated the quality of the fruit in peach and nectarine cultivars with and without the application of hydrogenated cyanamide and mineral oil, for two production cycles (2009 and 2010). The experiment was carried out at the School of Agricultural Science of the São Paulo State University (UNESP), at Botucatu in the Brazilian state of São Paulo, located at latitude 22º51'55 S and longitude 48º26'22 E, at an altitude of 810 m. The predominant climate type is warm temperate (mesothermal) with rains in the summer and dry in the winter. The following were evaluated: soluble solids, titratable acidity, pH, ratio, firmness, vitamin C and pulp yield. The use of hydrogenated cyanamide and mineral oil had no effect on the quality attributes of the fruit, except for pH, where those fruits under application of the products showed higher values. The cultivars all had a pulp yield greater than 90%, with 'Tourmaline' showing the highest yield (96 %). The levels of vitamin C varied according to the cultivars, where 'Marli' (16.9 mg 100 g-1) and 'Dourado-2' (16.5 mg 100 g-1), stood out for having the highest levels.

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This paper aims to contribute to the three-dimensional generalization of numerical prediction of crack propagation through the formulation of finite elements with embedded discontinuities. The analysis of crack propagation in two-dimensional problems yields lines of discontinuity that can be tracked in a relatively simple way through the sequential construction of straight line segments oriented according to the direction of failure within each finite element in the solid. In three-dimensional analysis, the construction of the discontinuity path is more complex because it requires the creation of plane surfaces within each element, which must be continuous between the elements. In the method proposed by Chaves (2003) the crack is determined by solving a problem analogous to the heat conduction problem, established from local failure orientations, based on the stress state of the mechanical problem. To minimize the computational effort, in this paper a new strategy is proposed whereby the analysis for tracking the discontinuity path is restricted to the domain formed by some elements near the crack surface that develops along the loading process. The proposed methodology is validated by performing three-dimensional analyses of basic problems of experimental fractures and comparing their results with those reported in the literature.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Pós-graduação em Agronomia (Horticultura) - FCA

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The aim of this work was to evaluate the quality of yellow melon inodorus Valenciano Amarelo (CAC) fresh cut submitted to two cut types and with application postharvest of calcium chloride. After preparation cubes and slices melon were immersed in solution with different calcium chloride (CaCl2) concentrations for two minutes, afterwards they were conditioned in trays of expanded polystyrene (EPS), covered by plastic film of low density polyethylene (PEBD), stored in cold camera to 5 degrees C +/- 1 and analyzed for 8 days. They were evaluated pH, firmness, tritable acidity (AT), soluble solids (SS) sugar reducer and ratio. The pH values varied from 5.27 to 5.68. The sugars reducers content and the ratio were superior in the slices compared to the cubes. The melon slices maintained larger firmness values compared to the cubes and in general there was reduction in the values of this parameter along the storage period for all treatments. Concentrations of 1.0 and 1.5% of CaCl2, result in larger values of firmness. The storage temperature and modified passive atmosphere they contributed to quality maintenance of MP melon. Concentrations of up to 1.0% of CaCl2 they could be recommended to maintain the melon quality MP melon yellow inodorus (CAC).

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The active modified atmosphere effect was evaluated in the quality of squash fresh-cut (MP).. The squash pieces were conditioned in plastic packings and submitted the gases application in the following concentrations: 0.03% CO2 and 21% O-2 (controls T1); 5% CO2 and 4% O-2 (T2); 6% CO2 and 4% O-2 (T3); 7% CO2 and 4% O-2 (T4); 8% CO2 and 4% O-2 (T5). In T6 it was made vacuum application in the packing. The packings containing the squash were stored in to the temperature of 10 degrees C and relative humidity of 75% for 12 days. The evaluated analyses were weigth loss, total acidity (AT), pH, soluble solids (SS), ratio, firmness, color, antioxidant activity for DPPH and carotenoids content. The weigth loss was gradual and low until the ninth day of storage. The values of AT increased along the experimental period being superior for T1 and T2. The increase of SS during the storage of the fresh-cut squash went smaller for T3 and T4. The brightness stayed during the storage being superior for T5, already the color components red and yellow decreased along the experimental period.