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[en] Lignin has a significant and largely unrealized potential as a source for the sustainable production of fuels and bulk high-value chemicals. It can replace fossil-based oil as a renewable feedstock that would bring about socio-economic and environmental benefits in our transition to a biobased economy. The efficient utilization of lignin however requires its depolymerization to low-molecular weight phenolics and aromatics that can then serve as the building blocks for chemical syntheses of high-value products. The ability of laccase to attack and degrade lignin in conjunction with laccase mediators is currently viewed as one of the potential “breakthrough” applications for lignin valorization. Here, we review the recent progress in lignin biodegradation with laccase-mediator systems, and research needs that need to be addressed in this field.
[en] The absolute density of plant fibres excludes all pores and lumen and therefore is a measure of the solid matter of the fibres. On the other hand the bulk density, which is being discussed here, includes all the solid matter and the pores of the fibres. In this work, the apparent density of the fibre was measured by using the Archimedes principle, which involves the immersion of a known weight of fibre into a solvent of lower density than the fibre. Toluene with a density of about 860 kg/m3 was chosen as a solvent. A tuft of fibre was weighed and recorded as Wfa. The fibre was then immersed in toluene, which wetted the fibre, and made to rest on the weighing pan submerged in the solvent and the weight of the immersed fibre was recorded as Wfs. The apparent density was then calculated using the equation. All the measurements were taken at room temperature. The fibre samples were not oven dried prior to measurement. (Author)
[en] Owing to homogeneous hollow tube shape and hydrophobicity of kapok fiber, the usages of this fiber are various such as fiberfill in pillows, quilts, non-woven fabric for oil spill cleanup and plastic green house. Even though kapok fiber is able to apply various industrial usages, it has a serious disadvantage which is the extreme sensitivity to spark or flame. Therefore, we try to make flame-resistant kapok fiber using gamma ray. The radiation caused loss of hydrophobic compounds in kapok fiber and no morphological change, especially fine hollow tube shape, was observed. The lignin contents were negligible changed after gamma irradiation. However, the building units of lignin polymer such as coniferyl alcohol, and sinapyl alcohol were significantly changed that is, functional group as a methoxyl group from lignin polymer was cleaved by gamma irradiation. Based on the results of removal of hydrophobic compounds and cleavage of methoxyl group from lignin polymer, kapok fiber can be converted into a flame-resistant fiber by gamma ray treatment.
[en] Ionic liquid tagged salen ligands containing two proximal 1,3-disubstituted imidazolium ionic liquid cores form cobalt(III) complexes capable of selectively oxidizing veratryl alcohol, a lignin model compound, to veratraldehyde using air or pure oxygen as the source of oxygen. Entrainment of these catalysts in either 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6], or 1-butyl-3-methylimidazolium bistriflimide, [bmim][NTf2], hydrophobic ionic liquid solvents, results in biphasic reactions when water is used as the second solvent allowing the catalyst/ionic liquid phase to be recycled. (author)
[en] The acid prehydrolysis of the lignocellulosic biomass from thistle O. nervosum has been conducted to determine the conditions for maximum yield of pentoses with minimum yield of hexoses. Variables studied were acid concentration (H2SO4, 1, 3, 4 and 5%), temperature (10000 and 1200C) time, solid to liquid ratio and degree of fineness of thistle (4 to 65 mesh). (author)
[en] Kenaf (Hibiscus cannabinus) retting were separated from a kenaf bast fiber by a combination of Electron beam irradiation (EBI) and NaOH solution treatment. The methods were based on a 6% NaOH solution treatment after various doses of EBI. FT-IR spectroscopy demonstrated that the content of lignin and hemicellulose in the retted kenaf fibers decreased as the EBI dose increased. Specifically, the lignin in the retted kenaf fiber treated with 300 kGy of EBI was almost completely removed. The morphology of retted kenaf fibers were characterized by SEM image, and the studies showed that the fibrillated degree of retted kenaf fibers treated with various EBI doses and was increased as EBI dose increased. The retted kenaf fibers treated with the EBI at 300 kGy was uniformly fibrillated with 10 ∼ 30 μm diameters
[en] This research aimed to evaluate the potential of several native white rot fungi (WRF) isolated from subtropical environments of Misiones (Argentina) to produce different ligninolytic enzymes. Coriolus versicolor f. antarcticus BAFC 266, Pycnoporus sanguineus BAFC 2126 and Phlebia brevispora BAFC 633 showed the highest phenoloxidase activity. Ganoderma applanatum strain E, P. sanguineus BAFC 2126 and P. brevispora BAFC 633 revealed marked laccase and peroxidase activity. C. versicolor f. antarcticus, G. applanatum (strain A) and Trametes villosa, gave high positive reactions with 2,6-dimethoxyphenol oxidation at the lowest tested pH. C. versicolor f. antarcticus, G. applanatum strains D and F, T. elegans BAFC 2127 and T. villosa, showed the highest manganese peroxidase activity. C. versicolor f. antarcticus also produced the highest lignin peroxidase activity. Tyrosinase activity was mostly evident in G. applanatum strains (D and F) and Phanerochaete chrysosporium HHB 11741. Kraft liquor decolorisation results were variable and depended on the fungus and the liquor concentration. Some fungi with moderate ligninolytic activity showed high decolorisation rates (e.g. Pleurotus sajor-caju and Steccherinium sp. BAFC 1171) indicating the significance of additional approach to evaluate a potential biotechnological application.
[en] Blue laccase from the white-rot basidiomycete P. tigrinus, an enzyme involved in lignin biodegradation, has been crystallized. The crystals obtained give diffraction data at 1.4 Å, the best resolution to date for this class of enzymes, which may assist in further elucidation of the catalytic mechanism of multicopper oxidases