Xylitol is a building block for a variety of chemical commodities, besides being widely used as a sugar substitute in the food and pharmaceutical industries. The aim of this work was to develop a microbial process for xylitol production using sugarcane bagasse hydrolysate as substrate. In this context, 218 non-Saccharomyces yeast strains were screened by growth on steam-exploded sugarcane bagasse hydrolysate containing a high concentration of acetic acid (8.0 g/L). Seven new Candida tropicalis strains were selected and identified, and their ability to produce xylitol on hydrolysate at low pH (4.6) under aerobic conditions was evaluated.The most efficient strain, designated C. tropicalis JA2, was capable of producing xylitol with a yield of 0.47 g/g of consumed xylose. To improve xylitol production by C. tropicalis JA2, a series of experimental procedures were employed to optimize pH and temperature conditions, as well as nutrient source, and initial xylose and inoculum concentrations. C. tropicalis JA2 was able to produce 109.5 g/L of xylitol with a yield of 0.86 g/g of consumed xylose, and with a productivity of 2.81 g·L·h, on sugarcane bagasse hydrolysate containing 8.0 g/L acetic acid and177 g/L xylose, supplemented with 2.0 g/L yeast nitrogen base and 4.0 g/L urea. Thus, it was possible to identify a new C. tropicalis strain and to optimize the xylitol production process using sugarcane bagasse hydrolysate as a substrate. The xylitol yield on biomass hydrolysate containing a high concentration of acetic acidobtained in here is among the best reported in the literature.

In this study, we synthesized a new class of copolymeric lattices based on vinyl pivalate (VPi) and modified oleic acid (OA) through a batch emulsion polymerization process. The effects of the chemically modified OA [methacrylated methyl oleate (MAMO)] on the thermal stability, glass‐transition temperature (Tg), average molar masses [mass‐average molar mass (Mw) and number‐average molar mass (Mn)], and molar mass dispersity (Ð) of the copolymers were evaluated. The experimental results indicate that via the introduction of MAMO into the polymer chains resulted in significant reductions in Tg, Mw, Mn, and Ð; this demonstrated a decrease of Tg at approximately 40 °C when the MAMO molar fraction equaled 9% compared to the value observed for the pure poly(vinyl pivalate) (PVPi), which was equal to 80.5 °C. MAMO incorporation led to a significant decrease in the Mw value observed in the interval, with a differential from approximately 1.6 × 103 to 289.6 kg/mol, and Ð values between 2.17 to 1.55, which was when the MAMO molar fraction present in the VPi‐containing copolymers varied from zero (pure PVPi) to approximately 9 mol %. We also observed that the thermal stability of the copolymers decreased slightly when the MAMO concentration increased in the reaction medium. Despite this minor drawback, polymer lattices with a high colloidal stability were formed at a high rate of polymerization, and the elevated conversion was within the interval 90–100%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44129.

RESUMO: O artigo analisa os aspectos técnicos e econômicos da colheita em regime de desbaste seletivo em povoamento de eucalipto. O estudo foi realizado em um talhão implantado com a espécie híbrida Eucalyptus grandis x Eucalyptus urophylla originado de sementes com seis anos de idade, localizado em uma propriedade rural no município de São José do Calçado, sul do estado do Espírito Santo. Para avaliar a aplicação do desbaste, foi realizado inventário florestal por meio de parcelas distribuídas sistematicamente na área. Com isso foi possível avaliar a seleção de árvores para desbaste, qualidade e intensidade da seleção de árvores remanescentes para serraria e estimar o volume de madeira colhido e remanescente. Foi realizado levantamento dos custos de implantação, manutenção e desbaste ao longo do ciclo e posterior atualização destes dados pelo método do valor presente líquido (VPL), que juntamente com a receita obtida com o corte da madeira pôde-se determinar a viabilidade do empreendimento. O desbaste foi realizado a um nível de qualidade satisfatório. A quantidade de indivíduos abatidos foi alta, devido ao baixo número de árvores remanescentes com boa qualidade. O VPL mostrou a inviabilidade do investimento a uma taxa de juros de 6,75% ao ano. Palavras chave: qualidade, florestas plantadas, custos e receitas.

system, it is possible to enhance the final properties of polystyrene through the incorporation of lignin, which represents an important platform for developing attractive polymeric materials from renewable resources.

No abstract