RESUMO:Este trabalho teve como objetivo avaliar a qualidade da madeira e do carvão vegetal de algumas espécies de ocorrência do cerrado mineiro visando o uso siderúrgico. Foram utilizadas cinco espécies de madeiras de ocorrência no cerrado procedentes do Estado de Minas Gerais. Na madeira foram avaliadas a densidade básica e os teores de lignina, extrativos totais, holocelulose e cinzas. No carvão vegetal foram avaliados os rendimentos em carvão vegetal e em carbono fixo, os teores de carbono fixo, materiais voláteis e cinzas, o poder calorífico superior e a densidade relativa aparente. Na avaliação do experimento utilizou-se o delineamento inteiramente casualizado com quatro repetições. Utilizou-se ainda a análise multivariada de componentes principais. As espécies Casearia sylvestris e Luehea divaricata apresentaram os maiores rendimentos gravimétricos em carvão vegetal e em carbono fixo, bem como elevados teores de lignina na madeira. O carvão vegetal da espécie Trema micrantha possui elevado poder calorífico superior, mas a menor densidade relativa aparente. A espécie Guazuma ulmifolia se destacou pelo elevado teor de carbono fixo e grande potencial para uso siderúrgico, juntamente com a espécie Casearia sylvestris. Palavras-chave: carvão vegetal, espécies nativas, qualidade da madeira WOOD QUALITY OF FIVE SPECIES FROM CERRADO FOR PRODUCTION OF CHARCOAL

A wide range of alternative cellulose fibers for the development of new green nanomaterials can be obtained from Brazil's natural resources. The objective of the work is to evaluate the influence of the chemical composition of hardwoods on the nanofibrillation process and optical quality of nanofiber films. Wood wastes were selected from three native Amazonian species and from exotic planted Eucalyptus grandis species. Wood sawdust was submitted to chemical alkali and bleaching pretreatments. Nanofibers were produced from the bleached fibers after 10, 20, 30 and 40 passes through a Super Mass Colloider grinder, and films were produced by the casting method. Raw sawdust, alkali-treated fibers and bleached fibers were evaluated by the major chemical components, syringyl/guaiacyl ratio, Fourier transformed infrared spectroscopy, oxygen/carbon ratio and scanning electron microscopy. Morphological characteristics of nanofibers and films were analyzed by transmission and scanning electron microscopies. Optical parameters studied for the films were the opacity, total color difference and b value. The main challenge to delignification was attributed to the low syringyl/guaiacyl ratio. The different chemical natures of Amazonian and eucalyptus hardwoods greatly affected pretreatments and, consequently, the nanofibrillation and optical quality of the films. Consequences observed for highly purified cellulose starting fibers are: (1) lower diameters for individual nanofiber elements; (2) fewer opaque and colored films produced from nanofibers; (3) a tendency to stabilization of the nanofibrillation process after 20 passes through the grinder. For species whose chemical nature hindered cellulose purification, the increased number L. Bufalino (of passes through the grinder continuously decreased the opacity.

RESUMOA relação entre a presença de lignina e a dormência de sementes foi avaliada para três espécies de leguminosas arbóreas ocorrentes na Mata Atlântica. As espécies estudadas foram: Cassia grandis L.f., Anadenanthera macrocarpa (Benth.) Brenan e Enterolobium contortisiliquum (Vell.) Morong. Os procedimentos anatômicos indicaram presença de lignina nas células paliçádicas da exotesta, nos osteoesclereídeos e nas células parenquimáticas da mesotesta. Valores elevados do conteúdo de lignina corresponderam à baixa taxa de dormência. Apesar de a lignina ser uma substância hidrofóbica, a presença no tegumento das sementes permite maior fluxo de líquidos diretamente relacionados com a ocorrência de lignina.Palavras-chave: semente, lignina, dormência. Lignin and Dormancy in Seeds of Three Legumes Species of Atlantic Forest ABSTRACTThe relationship between the presence of lignin and seed dormancy was evaluated in three legume tree species occurring in the Atlantic forest. The species studied were: Cassia grandis L.f., Anadenanthera macrocarpa (Benth.) Brenan and Enterolobium contortisiliquum (Vell.) Morong. The anatomical procedures indicated the presence of lignin in the palisade cells of the exotesta, in the osteosclereids and in the parenchymatic cells of the mesotesta. The high values of lignin content corresponded to the low rate of dormancy. Although lignin is a hydrophobic substance its presence in the integument of the seeds allows a higher flux of liquids directly related to the occurrence of lignin.

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The aim of this work was to determine the best fibrillation intensity that should be used to produce high crystalline and thermal stable microfibrillated cellulose (MFC) and nanocellulose films fromC. goeldianaveneer wastes. The number of passages (cycles) of cellulose suspension tested in grinder were 10, 20, 30 and 40. Important properties to be analyzed included changes in morphology from the raw wood to the nanocellulose films, increases/decreases in cellulose crystalline index for inference on biomaterial strength, and thermal behavior changes to support conclusions on biomaterials processing and application possibilities. After chemical treatments for cellulose isolation, mechanical shearing was applied to produce cellulose nanostructures; hence nanocellulose films could be successfully produced fromC. goeldianawood wastes. Influence of more refining cycles on thermal properties, indicated higher stability for 40-cycles nanocellulose films. In general, grinder refining process decreased crystalline index of cellulose.