13 resultados para Fibras de polietileno

em Repositório da Produção Científica e Intelectual da Unicamp


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This research studied the effect of low density polyethylene packaging and storage temperature on the preservation of fresh-cut (minimally processed) cabbage. The cabbages, previously cooled to a temperature of 10 ºC, were selected, washed, cut in four parts (with the central stalk removed), sanitized, cut in strips, rinsed, put in the centrifuge, weighed and stored in plastic packaging of low density polyethylene (70 µm), and then stored in cold chambers at temperatures of 1 and 10 ºC for 20 days. The following aspects were evaluated: carbon dioxide, oxygen and ethylene in the internal atmosphere of the package as well as, pH, titratable acidity, total soluble solids, vitamin C, loss of fresh mass and the total soluble solids/acidity in the fresh-cut cabbage ratio. The experimental design was entirely casual, with three repetitions. The analysis parameters, except for the vitamin C, loss of fresh mass and ethylene, presented significant variation between the temperatures and days of storage. The cabbage stored at a temperature of 1 ºC presented a shelf life of around 15 days, significantly higher than that stored at 10 ºC. At this temperature, on the 8th day of storage, the product was completely decayed, unfit for commercialization or consumption.

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The covering of the soil is an agricultural practice that intends to control the harmful herbs, to reduce the losses of water by evaporation of the soil, and to facilitate the harvest and the commercialization, once the product is cleaner and healthier. However, when the soil is covered important microclimatic parameters are also altered, and consequently the germination of seeds, the growth of roots, the absorption of water and nutrients, the metabolic activity of the plants and the carbohydrates storage. The current trial intended to evaluate the effect of soil covering with blue colored film on consumptive water-use in a lettuce crop (Lactuca sativa, L.). The experiment was carried out in a plastic greenhouse in Araras - São Paulo State, Brazil from March 3rd, 2001 to May 5th, 2001. The consumptive water-use was measured through two weighing lysimeter installed inside the greenhouse. Crop spacing was 0.25 m x 0.25 m and the color of the film above soil was blue. Leaf area index (IAF), was measured six times (7; 14; 21; 28; 35; 40 days after transplant) and the water-use efficiency (EU) was measured at the end. The experimental design was subdivided portions with two treatments, bare soil and covered soil. The average consumptive water-use was 4.17 mm day-1 to the bare soil treatment and 3.11 mm day-1 to the covered soil treatment. The final leaf area index was 25.23 to the bare soil treatment and 24.39 to the covered soil treatment, and there was no statistical difference between then.

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PURPOSE: To evaluate changes in retinal nerve fiber layer thickness as measured by scanning laser polarimetry (SLP) after the use of medication to reduce intraocular pressure (IOP) in glaucomatous or ocular hypertensive patients. METHODS: The authors prospectively enrolled 37 eyes of 37 patients in whom IOP was reduced by more than 25% after the use of medication. The images were obtained before and 15 to 30 days after the introduction of medication. The SLP parameters measured before and after the use of medication were compared using paired Student's t Test. RESULTS: The mean IOP was significantly reduced from 26.57±4.23 mmHg to 16.54 ±2.92 mmHg after the use of medication (p<0.05). None of the 10 SLP analyzed parameters was significantly affected by the reduction of IOP with medication (p>0.05). CONCLUSION: The retinal nerve fiber layer thickness, as measured by SLP, is not affected by the reduction of IOP with medication in patients with glaucoma or ocular hypertension.

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The aim of this work was to describe the morphology and ontogeny of P. riedelii fruits to aid in taxonomic, ecological and phylogenetic studies in Apocynaceae. Fruits were fixed in FAA, embedded in plastic resin, sectioned at 10 ìm and stained with toluidine blue, for structural analysis. The fruit of P. riedelii is a follicarium, with two follicular fruitlets. The epicarp is one-cell-layered, with trichomes and thick cuticle. The mesocarp, originating from fundamental ovary tissue, is parenchymatous with laticifers, non-lignified fibers and vascular bundles. The endocarp sensu lato is two-celllayered of crossed sclereids, originating from the inner ovary epidermis and from a single layer of parenchyma cells of fundamental ovary tissue. Follicle dehiscence is lateral and the dehiscence process involves anatomical characteristics such as a dehiscence zone with thin-walled cells, non-lignified fibers in the mesocarp and crossed sclereids in the endocarp.

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cDNA arrays are a powerful tool for discovering gene expression patterns. Nylon arrays have the advantage that they can be re-used several times. A key issue in high throughput gene expression analysis is sensitivity. In the case of nylon arrays, signal detection can be affected by the plastic bags used to keep membranes humid. In this study, we evaluated the effect of five types of plastics on the radioactive transmittance, number of genes with a signal above the background, and data variability. A polyethylene plastic bag 69 μm thick had a strong shielding effect that blocked 68.7% of the radioactive signal. The shielding effect on transmittance decreased the number of detected genes and increased the data variability. Other plastics which were thinner gave better results. Although plastics made from polyvinylidene chloride, polyvinyl chloride (both 13 μm thick) and polyethylene (29 and 7 μm thick) showed different levels of transmittance, they all gave similarly good performances. Polyvinylidene chloride and polyethylene 29 mm thick were the plastics of choice because of their easy handling. For other types of plastics, it is advisable to run a simple check on their performance in order to obtain the maximum information from nylon cDNA arrays.

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The objective of the work was to evaluate the effects of environment, recipients, and substrate compositions in passion fruit (Passiflora edulis Sims f. flavicarpa Deg.) seedlings biomass production in Pantanal region from September to November of 2006. Experimental trials were conducted in four protected environments, in two types of containers and three different substrate compositions. The environments were: A1 (greenhouse covered with low-density, 150-microns-thick polyethylene film), A2 (monofilament black screened with mesh for 50% of shade), A3 (aluminized screened with mesh for 50% of shade) and A4 (environment covered with straw of native coconut palm); the recipients were: polyethylene bags (R1) (15 x 25 cm) and polystyrene trays (R2) (with 72 cells). There substrates were: S1 (soil + organic compost + vermiculite, 1:1: 1 v/v), S2 (soil + organic compost + sawdust, 1:1: 1 v/v) and S3 (soil + organic compost + vermiculite + sawdust, 1:1: 1/2: 1/2 v/v). The experimental design was completely randomized statistical analysis in split-split-plot, with fifteen replications. The treatments in the plot were environments, in the subplots were pots, and subsubplots were substrates (4 x 2 x 3 = 24 treatments). Fresh and dry mass of aerial and root system parts were evaluated. Environments with screen showed better results for seedlings of yellow passion fruit biomass in polyethylene bags. Polyethylene bags promoted higher biomasses. The substrate with vermiculite showed better results for both types of containers. The substrate with a higher percentage of sawdust showed the worst result.

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Shelled, roasted and salted cashew nut kernels were packaged in three different flexible materials (PP/PE= polypropylene / polyethylene; PETmet/PE= metallized polyethylene terephthalate / polyethylene; PET/Al/LDPE= polyethylene terephthalate / aluminum foil / low density polyethylene ), with different barrier properties. Kernels were stored for one year at 30° C and 80% relative humidity. Quantitative descriptive sensory analysis (QDA) were performed at the end of storage time. Descriptive terms obtained for kernels characterization were brown color, color uniformity and rugosity for appearance; toasted kernel, sweet, old and rancidity for odor; toasted kernel, sweet, old rancidity, salt and bitter for taste, crispness for texture. QDA showed that factors responsible for sensory quality decrease, after one year storage, were increase in old aroma and taste, increase in rancidity aroma and taste, decrease in roasted kernel aroma and taste, and decrease of crispness. Sensory quality decrease was higher in kernels packaged in PP/PE.

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PURPOSE: To evaluate the sensitivity and specificity of machine learning classifiers (MLCs) for glaucoma diagnosis using Spectral Domain OCT (SD-OCT) and standard automated perimetry (SAP). METHODS: Observational cross-sectional study. Sixty two glaucoma patients and 48 healthy individuals were included. All patients underwent a complete ophthalmologic examination, achromatic standard automated perimetry (SAP) and retinal nerve fiber layer (RNFL) imaging with SD-OCT (Cirrus HD-OCT; Carl Zeiss Meditec Inc., Dublin, California). Receiver operating characteristic (ROC) curves were obtained for all SD-OCT parameters and global indices of SAP. Subsequently, the following MLCs were tested using parameters from the SD-OCT and SAP: Bagging (BAG), Naive-Bayes (NB), Multilayer Perceptron (MLP), Radial Basis Function (RBF), Random Forest (RAN), Ensemble Selection (ENS), Classification Tree (CTREE), Ada Boost M1(ADA),Support Vector Machine Linear (SVML) and Support Vector Machine Gaussian (SVMG). Areas under the receiver operating characteristic curves (aROC) obtained for isolated SAP and OCT parameters were compared with MLCs using OCT+SAP data. RESULTS: Combining OCT and SAP data, MLCs' aROCs varied from 0.777(CTREE) to 0.946 (RAN).The best OCT+SAP aROC obtained with RAN (0.946) was significantly larger the best single OCT parameter (p<0.05), but was not significantly different from the aROC obtained with the best single SAP parameter (p=0.19). CONCLUSION: Machine learning classifiers trained on OCT and SAP data can successfully discriminate between healthy and glaucomatous eyes. The combination of OCT and SAP measurements improved the diagnostic accuracy compared with OCT data alone.

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas . Faculdade de Educação Física

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Universidade Estadual de Campinas. Faculdade de Educação Física