903 resultados para Silicone oils


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

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Neste estudo observamos a reação tecidual após implantação de próteses de silicone associadas à poliglactina 910. Telas de borracha de silicone com 1,5 x 1,5cm de diâmetro e 0,7mm de espessura, polifenestradas, foram implantadas no subcutâneo do dorso de ratos.Dois grupos foram observados, no primeiro apenas telas fenestradas eram implantadas, no segundo as fenestrações das telas eram preenchidas com fios de poliglactina 910. Os animais foram observados por 30, 60 e 90 dias quando eram sacrificados e as telas mais o tecido adjacente ressecados. Não se observou diferenças na quantidade de fibras colágenas entre os subgrupos de um mesmo grupo e ou quando comparados com os subgrupos do grupo em estudo. No grupo controle, onde se usou apenas as telas fenestradas de silicone houve uma diferença significante entre as fibras reticulares, em maior número nos grupos de 30 e 60 dias de observação, quando comparadas ao grupo de 90 dias. A poliglactina 910 associada ao silicone não alterou o número de fibras do tecido conjuntivo, contadas nas fenestrações das telas.

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Background. Thin study evaluated the effects of a silicone membrane on the treatment of the raw flesh area in wounds.METHODS. The experimental study was carried out with 30 male Wistar rats divided into three groups: in the G(G) group, the raw area was treated with gauze, in the G(H) group with homograft, and in the G(S) group with a silicone membrane. Animals were sacrificed at fourteen days of postoperative. The studied attributes were body mass variation, histological study quantifed by morphometric analysis evaluating the number of neovessels, fibroblasts, collagen fibers, leucocytes, monocytes; and using a micrometric ruler measurement of the raw area thickness. Data were then submitted to statistical analysis.RESULTS. There was no significant difference between the animals' mass (p=0.0685). Predominance of neovessels (p<0.01), fibroblasts (p<0.001) and thickness of the raw flesh were observed in G(S) animals. There was predominance of leucocytes (p<0.021) and monocytes (p<0.0001) in G(H) animals. Also, no significant difference between the groups as for collagen fibers (p=0.0536) was observed.CONCLUSION. The silicone membrane promoted granulation tissue with a large number of neovessels, fibroblasts and greater thickness.

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In this work it was investigated the effect of the exposure to different plasmas on the wettability of silicone samples. We have observed that oxygen. argon, and hydrogen glow discharges are quite effective in reducing the water contact angle of such polymer. However, indifferently to efficiency of the treatment, practically all the modified surfaces recovered great part of their original hydrophobicity. We have investigated this hydrophobic recovery using surface energy measurements and theoretical simulations based on the exponential decay of the population of polar groups on the surface. According to our results such recovery can be attributed to the decrease of polar species at the interface water-polymer surface.

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Oils from Buriti (Mauritia flexuosa), Cupuacu (Theobroma grandiflora), Passion Fruit (Passiflora alata), Andiroba (Carapa gitianensis), Brazilian Nut (Bertholletia excelsa) and Babassu (Orbignya spp.) were evaluated as carbon sources for rhamnolipid production by Pseudomonas aeruginosa LBI. The highest rhamnolipid concentrations were obtained from Brazilian Nut (9.9 l(-1)) and Passion Fruit (9.2 g l(-1)) oils. Surface tension varied from 29.8 to 31.5 mN m(-1), critical micelle concentration from 55 to 163 mg l(-1) and the emulsifying activity was higher against toluene (93-100%) than against kerosene (70-92%). Preliminary characterization of the surfactant mixtures by mass spectrometry revealed the presence of two major components showing m/z of 649 and 503, which corresponded to the dirhamnolipid (Rha(2)C(10)C(10)) and the monorhamnolipid (RhaC(10)C(10)), respectively. The monorhamnolipid detected as the ion of m/z 503 is predominant in all samples analyzed. (c) 2005 Elsevier Ltd. All rights reserved.

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The composition of essential oils from leaves, stems and fruits of Piper aduncum, P arboreum and P. tuberculatum was examined by means of GC-MS and alltifungal assay. There was a predominance of monoterpenes in P aduncum and P tuberculatum and of sesquiterpenes in P arboreum. P aduncum showed the richest essential oil composition, including linalool. The essential oils from fruits of P. aduncum and R tuberculatum showed the highest antifungal activity with the MIC of 10 mu g as determined against Cladosporium cladosponoides and C. sphaerospermum, respectively. This is the first report of the composition of essential oils from P. tuberculatum.

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A. suite of 10 different marine evaporitic oil samples from Sergipe-Alagoas Basin, Brazil was studied for its biomarker content, in particular its acidic constituents. The oils showed different molecular distributions and relative abundances of n-alkanoic, isoprenoid and hopanoic acids. The observed differences were assigned to the incorporation of immature organic matter in the oils and fractionation along the migration pathway. The diagenetic precursor functionality (alcohol/ether or acid) was proposed based on the comparison of the relative abundances of the neutral and acidic biomarkers (hopanoids, isoprenoids, alkyl-steranes, monoaromatic alkyl-steroids). In the acidic fraction, 3 series of steroid-alkanoic acids and monoaromatic steroid-alkanoic acids (steroid-methanoic, ethanoic and propanoic acids and monoaromatic steroid-methanoic, ethanoic and propanoic acids) were detected, while in the neutral fraction only 2 series of each corresponding class could be observed (methyl and ethyl-steranes and monoaromatic methyl and ethyl-steroids). These carbon shifts suggest that decarboxylation is an important process in the formation of the alkyrsteranes and monoaromatic alkyl-steroids, and we infer that carboxylic acids are the diagenetic precursors of these classes of compounds. When alcohol or ether are the diagenetic precursors (isoprenoids and hopanoids), no significant differences in the molecular distributions between neutral and acidic fractions were observed. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

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In this work we report on the use of the Thermal Lens method to verify the evolution of the thermal diffusivity of sunflower and soybean vegetable oils utilized in preparation of twenty five snacks portions. Our results show that the thermal diffusivity for sunflower oil does not change between 1 and 25 portions of fried snacks. By another hand, the soybean thermal diffusivity exhibits a little decrease for higher portion of fried snacks, indicating that for this oil the triglyceride level is reduced as a degradation process.

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Fourier Transform Infrared Photoacoustic Spectroscopy was used to determine the mid-infrared vibrational modes of biodiesel and vegetable oils. Our results indicate that this method can contribute significantly to the biodiesel wash process during the sample preparation. Besides, by analyzing the spectra of vegetable oils used to fry snacks we could to monitor the degradation in function of the fried time.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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A rapid and simple method was developed for quantitation of polar compounds in fats and oils using monostearin as internal standard. Starting from 50 mg of oil sample, polar compounds were obtained by solid-phase extraction (silica cartridges) and subsequently separated by high-performance size-exclusion chromatography into triglyceride polymers, triglyceride dimers, oxidized triglyceride monomers, diglycerides, internal standard and fatty acids. Quantitation of total polar compounds was achieved through the internal standard method and then amounts of each group of compounds could be calculated. A pool of polar compounds was used to check linearity, precision and accuracy of the method, as well as the solid-phase extraction recovery. The procedure was applied to samples with different content of polar compounds and good quantitative results were obtained, especially for samples of low alteration level.