154 resultados para Cellulose nanofibers
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Neste trabalho, avaliou-se a fermentação da cana-de-açúcar queimada, ensilada com ou sem uso de aditivo seco. Os tratamentos (seis no total) consistiram da silagem de cana crua ou queimada, adicionada de 0, 50 ou 100 g/kg de milho desintegrado com palha e sabugo (MDPS), com base no peso verde da forragem. Foram determinados os teores de MS, PB, nitrogênio insolúvel em detergente ácido (NIDA), FDN, FDA, celulose, hemicelulose e lignina. Na avaliação das características fermentativas, foram determinados os valores de carboidratos solúveis, o poder tamponante, o pH e as concentrações de nitrogênio amoniacal e etanol. Como características microbiológicas, avaliou-se o desenvolvimento de leveduras. A inclusão de MDPS elevou os teores de MS e reduziu discretamente os teores de N-NH3 e etanol das silagens, não ocasionando efeito nos valores de pH e na população de leveduras. A presença do fogo reduziu a concentração de MS das silagens, elevou os teores de etanol e leveduras e diminuiu os teores de N-NH3. A fermentação etanólica durante a ensilagem não foi controlada com a inclusão de aditivo seco ou com o uso do fogo.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Dois condicionadores químicos, a carboximetilcelulose, nas dosagens de 0,1% e 0,25% em relação ao peso do solo seco, e o silicato de sódio, de relação sílica-álcali igual a 3,2, a 0,6% e 1,2% em peso, foram pesquisados quanto aos seus efeitos sobre os índices físicos dos solos argiloso e barro arenoso empregados neste trabalho. Os dados obtidos foram estatisticamente analisados e os resultados permitiram que se chegassem a algumas conclusões. O tratamento 0,25% de carboximetilcelulose diminuiu o peso específico aparente seco e aumentou, consequentemente, o índice de vazios e porosidade dos solos estudados. O efeito dos tratamentos 1,2% de silicato de sódio e 0,1% de carboximetilcelulose sobre o peso específico aparente seco dos solos argilosos e barro arenoso, respectivamente, foi semelhante ao do tratamento 0,25% de carboximetilcelulose.
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Leucoagaricus gongylophorus, the fungus cultured by the leaf-cutting ant Atta sexdens, produces polysaccharidases that degrade leaf components by generating nutrients believed to be essential for ant nutrition. We evaluated pectinase, amylase, xylanase, and cellulase production by L. gongylophorus in laboratory cultures and found that polysaccharidases are produced during fungal growth on pectin, starch, cellulose, xylan, or glucose but not cellulase, whose production is inhibited during fungal growth on xylan. Pectin was the carbon source that best stimulated the production of enzymes, which showed that pectinase had the highest production activity of all of the carbon sources tested, indicating that the presence of pectin and the production of pectinase are key features for symbiotic nutrition on plant material. During growth on starch and cellulose, polysaccharidase production level was intermediate, although during growth on xylan and glucose, enzyme production was very low. We propose a possible profile of polysaccharide degradation inside the nest, where the fungus is cultured on the foliar substrate.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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O objetivo deste trabalho foi avaliar os teores de lignina e celulose em plantas de cana-de-açúcar após a aplicação de dois maturadores para a colheita. O experimento foi conduzido em uma área de cana-soca, cultivar SP 803280, no município de Igaraçu do Tietê/SP. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Os tratamentos constituíram-se da aplicação de dois maturadores: sulfometuron-methyl (Curavial) e glyphosate (Roundup original). As doses utilizadas foram: glyphosate a 72 g e.a. ha-1; glyphosate a 144 g e.a. ha-1 ; glyphosate a 72 g e.a. ha-1 + sulfometuron methyl a 10 g p.c. ha-1; glyphosate a 108 g e.a. ha-1 + sulfometuron-methyl a 12 g p.c. ha-1; sulfometuron-methyl a 20 g p.c. ha-1; e a testemunha sem aplicação de maturadores. As análises de lignina e celulose foram realizadas pelo método lignina em detergente ácido modificado. O glyphosate e o sulfometuron-methyl alteraram os níveis de lignina no momento da colheita, e esse efeito foi observado também durante o crescimento da cana-de-açúcar (meses após a aplicação desses produtos). O glyphosate a 72 g e.a. ha-1 promoveu reduções nos teores de lignina, na colheita e durante o crescimento da cana-de-açúcar, quando comparados com os da testemunha, enquanto o sulfometuron-methyl isolado na menor dose (10 g ha-1) promoveu aumento nos teores desse biopolímero na soqueira da cana-de-açúcar.
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Steam explosion process is employed for the successful extraction of cellulose nanofibrils from pineapple leaf fibres for the first time. Steam coupled acid treatment on the pineapple leaf fibres is found to be effective in the depolymerization and defibrillation of the fibre to produce nanofibrils of these fibres. The chemical constituents of the different stages of pineapple fibres undergoing treatment were analyzed according to the ASTM standards. The crystallinity of the fibres is examined from the XRD analysis. Characterization of the fibres by SEM. AFM and TEM supports the evidence for the successful isolation of nanofibrils from pineapple leaf. The developed nanocellulose promises to be a very versatile material having the wide range of biomedical applications and biotechnological applications, such as tissue engineering, drug delivery, wound dressings and medical implants. (C) 2010 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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BACKGROUND: Baru (Dipteryx alata Vog.) is a fruit distributed throughout the Brazilian savanna and contains a seed with a high protein content, whose properties have been rarely explored. The purpose of this study was to characterize this protein, especially by isolation and quantifying its fractions and measuring some of its molecular properties.RESULTS: Baru seeds contain 244 g kg(-1) protein on a dry weight basis. Solubility profiles showed a preponderance of globulins. This fraction dominated the seed composition, with 61.7 wt% of the total soluble proteins. Albumins and glutelins accounted for 14 and 3.3 wt%, respectively. SDS-PAGE resolution of albumin and globulin showed main bands with molecular weights of 84 kDa and 64,66 and 73 kDa, respectively. The total protein of the flour and the globulin showed values of in vitro digestibility of 85.59% and 90.54%, relative to casein. Total globulin produced only one chromatographic peak, both on Sepharose CL-6B gel filtration and on DEAE-cellulose ion-exchange columns, eluted at a concentration of 0.12 mol L(-1) NaCl.CONCLUSION: The baru seed had high protein content with large quantities of storage proteins. The chromatographic and solubility profiles indicate the predominance of a fraction with characteristics of a legumin-type protein. (C) 2011 Society of Chemical Industry
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Soluble, ionically bound peroxidase (POD) and polyphenoloxidase (PPO) were extracted from the pulp of peach fruit during ripening at 20degreesC Ionically bound form was purified 6.1 -fold by DEAE-cellulose and Sephadex G-100 chromatography. The purified enzyme showed only one peak of activity on Sephadex G-100 and PAGE revealed that the enzyme was purified by the procedures adopted. The purified enzyme showed a molecular weight of 29000 Da, maximum activity at pH 5.0 and at 40degreesC the calculated apparent activation energy (Ea) for the reaction was 10.04 kcal/mol. The enzyme was heat-labile in the temperature range of 60 to 75degreesC with a fast inactivation at 75degreesC Measurement of residual activity showed a stabilizing effect of sucrose at various temperature/sugar concentrations (0, 10, 20 %, w/w), with an activation energy (Ea) for inactivation increasing with sucrose concentration from 0 to 20% (w/w). The Km and V-max values were 9.35 and 15.38 mM for O-dianisidine and H2O2, respectively. The bound enzyme was inhibited competitively by (.)ferulic, caffeic and protocatechuic acids with different values of Ki,. L-cysteine, p-coumaric and indolacetic acid and Fe++ also inhibited the enzyme but at a lower grade. N-ethylmaleimide and p-CMB were not effective to inhibit the enzyme demonstrating the non-essentiality of SH groups.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Drug delivery systems based on natural polysaccharides, such as chitosan (CS) and pectin (PC), rather than on synthetic polymers, have been widely studied. Some reasons for that are low toxicity and costs and high biodegradability of the formers. A multiparticulate system based on CS and PC was developed in our laboratories, including the addition of an enteric polymer, cellulose acetate phtalate (CAP). Such improvement promoted stronger gastric and enteric resistances, as assessed in vitro, making the systems more selective to enzymatic degradation in the colon. Although in vitro dissolution tests can simulate some properties concerning the gastrointestinal transit (GT), collaborating to characterize the systems behavior in the biological fluids, frequently they do not result in satisfactory in vitro/in vivo correlations. The objective of this work was to follow in vivo the GT of the particles developed by means of AC biosusceptometry (ACB), a non-invasive and of low cost methodology. The particles containing ferrite in powder form were prepared by complex coacervation using an ideal 3:1:1 mass ratio for PC:CS:CAP. The magnetic particles were administered to healthy volunteers by oral route. The GT was monitored by using multi-sensor ACB system and the signal acquisition was performed every IS min until the colonic region was reached. By means of ACB technique, it was possible to acquiring images generated by the magnetic particles within the whole gastrointestinal tract including the colonic region. Variable particles transit times were observed among the volunteers, but without interference on the mapping of the particles until the colonic region. The particles were able to produce magnetic field strong enough to generate signals adequate for mapping the particles. The results suggest that integral particles reached the colon, after they resisted against gastric and enteric media. Studies associating transit time and in vivo drug release are in development in order to confirm the efficiency of the systems.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)