Foram analisados clones de Eucalyptus de última geração, pertencentes às principais empresas brasileiras de celulose. Os estudos consistiram numa caracterização tecnológica detalhada da qualidade das madeiras utilizadas no processamento fabril das empresas. Foram realizadas análise químicas detalhadas das madeiras e cozimentos kraft, simulando-se uma das modernas técnica de digestor contínuo. Os resultados indicaram a alta qualidade dos clones de Eucalyptus atualmente plantados no Brasil para produção de celulose.

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Foram estudados dois clones de Eucalyptus com densidades básicas de 447 e 552 kg/m³. O processo kraft foi utilizado para a produção de celulose, tendo sido aplicadas diferentes cargas de álcali para se obterem polpas com número kappa 18 ± 0,5. As polpas foram branqueadas pela seqüência ODEopDD, a alvuras de 90 ± 1% ISO, e refinadas, sendo suas propriedades físico-mecânicas e ópticas analisadas. A madeira de baixa densidade mostrou-se mais recomendável para a produção de celulose, por ter apresentado maior rendimento depurado, viscosidade da polpa mais elevada, ter requerido menor carga de álcali no cozimento, ter proporcionado menor teor de sólidos no licor residual e menor consumo de reagentes químicos no branqueamento. As propriedades mecânicas e estruturais das polpas não foram afetadas significativamente pela densidade básica das madeiras.

N e K 2 O), sobre a produção e composição bromatológica de lâminas foliares em pastagem de capim-elefante. O delineamento experimental foi o de blocos ao acaso com três repetições para os tratamentos de sequeiro e irrigado. As baixas temperaturas e as menores horas de luz no período seco do ano determinaram o baixo crescimento da planta forrageira, mesmo com a irrigação. No entanto, no verão, constatou-se rápido crescimento da planta forrageira sob irrigação, privilegiando o desenvolvimento de colmos em relação às lâminas foliares, determinando as menores relações para as maiores doses dos fertilizantes. As lâminas foliares sob irrigação também apresentaram os menores valores de proteína bruta e os maiores de FDN e FDA. Assim, manejos mais freqüentes em pastagens sob irrigação poderiam controlar o desenvolvimento dos colmos e disponibilizar material de melhor composição bromatológica.Palavras-chave: água, composição bromatológica, nitrogênio, Pennisetum purpureum, potássio Effect of Irrigation and Fertilization in the Availability and Chemical Composition of Leaf Lamina Dry Mass of ElephantgrassABSTRACT -An experiment was carried out to evaluate the effect of irrigation, followed by increasing levels of nitrogen and potassium (100-80; 200-160; 300-240; 400-320, respectively N and K 2 O), on the production and chemical composition of the leaf lamina at the elephantgrass. The experimental delineation was of blocks randomized with three repetitions for treatments irrigated and dry land. The low temperatures and the smallest light hours in the dry season determined the low plant forage growth, even with the irrigation. However, in the summer, there was fast growth of plant forage under irrigation, emphasizing the culm growth in relation to leaf laminas, determining the lower relations to the higher fertilizer levels. The leaf laminas under irrigation also showed the lower crude protein contents and higher NDF and ADF contents. So, more frequent managing in the irrigated pastures could control the culm growth and available material of better chemical composition.

Three different birchwood-based xylan biomaterials were used in the current study to deconvolve the heretofore unknown effects of these modified adsorbed xylans on the processability of eucalyptus pulp: a 4-Omethylglucuronic acid xylan (MeGlcA-xylan); then, the MeGlc moiety was modified to provide an enriched hexenuronic acid xylan (HexA-xylan) and a low uronic acid content xylan (LowUrA-xylan). The study illustrates how the composition of xylan, in terms of the type and content of uronic acid, strongly influences the physical properties of cellulose fibers. NMR was used to confirm these structures and their M w s were measured by gel permeation chromatography. The three different xylan types were adsorbed onto bleached kraft pulp under controlled times and temperatures and examined by atomic force microscopy and scanning electron microscopy. It was found that LowUrA-xylan had greater adsorption on eucalyptus pulp, especially at high temperatures and times, while HexA-xylan adsorbed more onto eucalyptus pulp than MeGlcA-xylan. Water retention values of xylan-enriched eucalyptus pulps increased, while their hornification decreased. In general, xylan-enriched pulps demonstrated improved processability (beatibility) while displaying acceptable physical properties. These findings may have important implications for the overall efficiency and energetics of downstream biomass transformation processes such as pretreatment within the context of a biofuel application.

Wood autohydrolysis for xylan removal prior to kraft pulping and the consequences of this practice downstream in a kraft pulp mill has been investigated. Chip autohydrolysis for 60 min at 165 °C removed 61% of the xylans, but subsequent kraft cooking produced a 9.4% lower yield than reference. Pulp from 60-min autohydrolyzed chips showed 75% efficiency in oxygen delignification compared to 43.6% from the reference, resulting in a subsequent ECF bleaching cost reduction of 36% and significant effluent improvement. The chip autohydrolysis process resulted in a pulp of higher bulk, lower beatability and strength in relation to the reference, and an acid hydrolysate of low xylan concentration. Pulp cellulose and xylan derived from autohydrolyzed chips are less stable during kraft pulping because of their low molecular weight and high polydispersity. Xylan−lignin and cellulose−lignin complexes from kraft pulps derived from autohydrolyzed chips contain lignin of higher molecular weight than that of regular kraft pulp.

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Based on an observed decrease of effective thermal conductivity of milk during coagulation, a heated thermistor sensor was developed for monitoring curd formation. The thermistor was heated with a constant direct current, and its voltage was measured during milk coagulation, indicating a drop after the enzymatic reaction. The sensor was studied in the laboratory for different milk acidities, rennet concentrations, added calcium chloride, and coagulation temperatures. It was also tested in a commercial cheese plant for more than a month. The cutting time established by the cheesemaker in 16 experiments was compared with a prediction equation, and the standard error of prediction was 1.9 min.