155 resultados para polyvinyl chloride (PVC)
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The objective of this trial was to evaluate the effect of ascorbic acid (AA) and calcium chloride (CaCl2) applied by immersion at temperatures of 20 and 40 degrees C on the physicochemical and sensory characteristics of minimally processed cabbage, stored under refrigeration. Cabbages were processed in an industrial food processing equipment to be cut in slices with thickness of 3 mm. Slices were immersed in sodium hypochlorite (50 ppm) during 5 minutes for sanitization. After, the following treatments were carried out T1= control (immersion in water during 5 minutes at 20 degrees C); T2= immersion in 1% AA solution, during 5 minutes at 20 degrees C; T3= immersion in 2% AA solution, during 5 minutes at 20 degrees C; T4= immersion in 1% CaCl2 solution during 5 minutes at 20 degrees C; T5= immersion in 2% CaCl2 solution during 5 minutes at 20 degrees C, T6= immersion in 1% CaCl2 solution during 5 minutes at 40 degrees C; and T7= immersion in 2% CaCl2 solution during 5 minutes at 40 degrees C; with four replications each one. After application of treatments, cabbage was centrifuged during one minute, wrapped with polyvinyl chloride, 20 mu m, in trays of expanded polystyrene and maintained in refrigerated environment, at 6 +/- 1 degrees C and 85-90% of relative humidity, during eight days. Little increasing was observed in pH and titratable acidity values and reduction in soluble solids during conservation period on all treatments. Treatment with AA did not differ from control for color and general appearance, while treatment with 2% CaCl2 at 20 degrees C maintained the best quality, with less intensity of browning, best general appearance and purchase intent and least strange odor at the end of evaluation period.
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Estudou-se o efeito do tratamento de sementes de algodão com cloreto de mepiquat sobre o crescimento inicial de raízes e parte aérea. O experimento, realizado em casa de vegetação, utilizou vasos de PVC adaptados com uma parede frontal de vidro e os tratamentos foram constituídos por cinco doses do cloreto de mepiquat (CM) do ingrediente ativo (i.a.): 0, 3, 6, 9 e 12 g kg-1 de sementes, pulverizado sobre as sementes, e a cultivar FM 993. Massa de matéria seca da parte aérea (folhas, pecíolos e haste), massa de matéria seca da raiz, área foliar, relação parte aérea:raiz, relação área foliar:crescimento radicular, o comprimento da parte aérea foram avaliados aos 21 dias após a semeadura. Crescimento radicular foi avaliado a cada três dias até os 18 dias. O CM aplicado às sementes do algodão promove redução da altura da planta e da área foliar, sem, contudo, afetar produção de massa de matéria seca da parte aérea e raiz, relação parte aérea:raiz, relação área foliar:crescimento radicular e comprimento total de raízes do algodoeiro. Assim, no presente experimento não foi observado efeito negativo do CM aplicado às sementes do algodoeiro na absorção de água pela planta.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Films made from a blend of poly(epsilon-caprolactone) and poly(vinyl chloride) (PCL/PVC) retained high crystallinity in a segregated PCL phase. Structural and morphological changes produced when the films were exposed to high potency ultraviolet (UV) irradiation for 10 h were measured by UV-Vis spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). They were different to those observed with homopolymer PCL and PVC films treated under the same conditions. The FTIR spectra of the PCL/PVC blend suggest that blending decreased the susceptibility of the PCL to crystallize when irradiated. Similarly, although scanning electron micrographs of PCL showed evidence of growth of crystalline domains, particularly after UV irradiation, the images of PCL/PVC were fairly featureless. It is apparent that the degradation behavior is strongly influenced by the interaction of the two polymers in the amorphous phase.
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The photodegradation of a 1:1 w/w blend of polycaprolactone and poly(vinyl chloride) has been studied by following carbon dioxide emission during UV exposure. Similar measurements were performed for polycaprolactone and poly(vinyl chloride) homopolymers which were prepared and irradiated in the same way. It was found that the blend gave lower CO2 emission than either of the two homopolymers, indicating that the interaction of the two components in the blend provided a beneficial reduction of photodegradation. It is therefore deduced that the detailed morphological characteristics of the blend have a controlling influence over the photo-oxidation. (c) 2007 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Ciências Biológicas (Microbiologia Aplicada) - IBRC
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This paper presents results describing the physical, mechanical, and thermal properties (melt flow index - MFI and oxidative induction time - OIT) of high density polyethylene and poly (vinyl chloride) after weathering exposure (6, 12, 18, and 30 months). The materials exposed were geomembranes of two thicknesses: 1.0 and 2.0 mm (PVC) and 0.8 and 2.5 mm (HDPE). The climate parameters (average) obtained were 25 degrees C (temperature), 93 mm (precipitation), 66% (relative humidity), and 19 MJ/m(2). day (intensity of global radiation). Some results showed, for instance, that the behavior of the geomembranes changed after the exposures. A few minor variations in physical properties occurred. The density and thickness, for instance, varied 0.5-1.0% (average) for both the PVC and HDPE geomembranes. The mechanical properties changed as a function of the period of exposure. In general, some decreases were verified by the deformation of PVC. The samples became more rigid. In contrast, HDPE geomembranes became more ductile. Despite the variations in elasticity, some increases in deformability were verified. An MFI test showed some degradation in HDPE geomembranes. OIT tests revealed small values for both intact and exposed samples.
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A adição de sal à água tem sido utilizada para a mitigação de estresse e aumento da taxa de sobrevivência em peixes. O presente estudo avaliou o efeito do cloreto de sódio (0,0; 1,0; 3,0 e 6.0 g/l) nas concentrações de cortisol plasmático, glicemia, triglicerídios, proteínas total plasmática, hematócrito, hemoglobina, número de eritrócitos, glicogênio e lipídio hepáticos, e lipídio muscular em matrinxã Brycon amazonicum adultos após quatro horas de transporte e durante período de recuperação de 96 h. Amostras foram coletadas antes e depois do transporte, bem como 24 e 96 h após a chegada. O nível de cortisol plasmático estava mais elevado logo após o transporte quando comparado à condição inicial (pré-transporte), exceto para os peixes transportados com sal nas concentrações 3,0 e 6,0 g/l. Comportamento semelhante foi observado para a glicemia, porém os peixes dos tratamentos 0,0, 1,0 e 3,0 g/l necessitaram de período superior a 24 h para recuperar a condição inicial. Foram registrados níveis mais baixos de glicogênio hepático em peixes do tratamento controle (0,0 g/l). Os parâmetros hemoglobina, número de eritrócitos, proteína plasmática total e lipídio hepático não apresentaram alterações durante o período experimental. Os valores de hematócrito diminuíram logo após o transporte em todos os tratamentos, retornando aos níveis iniciais após 24 h. Todos os tratamentos apresentaram redução nos níveis de lipídio muscular e triglicerídios durante o período de recuperação. Os resultados sugerem que a adição de 6,0 g/l de sal na água de transporte reduz as alterações fisiológicas de estresse e que é necessário período de 96 h após o transporte para a recuperação da condição inicial de matrinxãs transportados sem a adição de sal.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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From January to October 1995, chloride content determinations were accomplished in 2,218 samples of milk collected from 67 quarters of 17 lactating cows, in initial, middle and final stages of lactation, in the morning and afternoon milking. The highest means of chloride contents were observed among the milk samples collected in the final stage of lactation (0,203 gC1/100ml), in the summer (0,212 gC1/100ml) and in the morning milking (0,189 g C1/100ml). The differences observed between the chloride contents in the samples obtained in the different stages of lactation and the seasons of the year were statistically significant (P<0.0001). The gratest occornce of chloride at rates superior to 0.22 gC1100ml was observed in the final stge of lactation (31.4%), summer (44.2%) and after the morning milking (27.8%). These results evidentiate the influence of physiological and external factors (stage of lactation and season of the year) on the concentration of chloride of milk.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)