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In situ degradability of corn stover and elephant-grass harvested at four stages of maturity; Degradabilidade in situ de híbridos de milho e de capim-elefante colhidos em quatro estádios de maturidade

SILVA, Luis Felipe Prada e; CASSOLI, Laerte Dagher; ROMA JÚNIOR, Luiz Carlos; RODRIGUES, Ana Carolina de Oliveira; MACHADO, Paulo Fernando
Fonte: Piracicaba Publicador: Piracicaba
Tipo: Artigo de Revista Científica
ENG
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47.17%
Dentre as forragens, a silagem de milho é amplamente utilizada pelos fazendeiros que visam explorar o máximo do potencial genético dos animais. No entanto, outros volumosos tropicais como o capim-elefante (Pennisetum purpureum) são mais produtivos e, portanto, mais baratos do que a silagem de milho. Nosso objetivo foi comparar a degradabilidade in situ do capim-elefante com a degradabilidade de híbridos de milho, colhidos em quatro estágios de maturidade. O experimento seguiu um delineamento de blocos ao acaso com sub-parcelas. Dois híbridos de milho: AG5011 e ZN8392 foram colhidos com 25, 30, 35 e 40% matéria seca (MS) na planta toda e separados na fração colmo + bainha + folhas e espigas. Capim elefante foi colhido 30, 40, 50 e 60 dias após o corte de nivelamento. As amostras secas e trituradas foram incubadas no rúmen por 0, 6, 12, 24, 48 e 72 h para cálculo da cinética da degradação ruminal da MS e da fibra em detergente neutro (FDN). O avanço da maturidade aumentou os teores de FDN e fibra em detergente ácido (FDA) do capim elefante e reduziu a degradabilidade da MS. Entretanto, a maturidade teve pouco efeito sobre os teores de fibra e a degradabilidade da MS da fração planta dos híbridos de milho. O capim elefante apresentou maior degradabilidade da FDN do que híbridos de milho...

Xylitol production from DEO hydrolysate of corn stover by Pichia stipitis YS-30

RODRIGUES, Rita C. L. B.; KENEALY, William R.; JEFFRIES, Thomas W.
Fonte: SPRINGER HEIDELBERG Publicador: SPRINGER HEIDELBERG
Tipo: Artigo de Revista Científica
ENG
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66.9%
Corn stover that had been treated with vapor-phase diethyl oxalate released a mixture of mono- and oligosaccharides consisting mainly of xylose and glucose. Following overliming and neutralization, a d-xylulokinase mutant of Pichia stipitis, FPL-YS30 (xyl3-a dagger 1), converted the stover hydrolysate into xylitol. This research examined the effects of phosphoric or gluconic acids used for neutralization and urea or ammonium sulfate used as nitrogen sources. Phosphoric acid improved color and removal of phenolic compounds. d-Gluconic acid enhanced cell growth. Ammonium sulfate increased cell yield and maximum specific cell growth rate independently of the acid used for neutralization. The highest xylitol yield (0.61 g(xylitol)/g(xylose)) and volumetric productivity (0.18 g(xylitol)/g(xylose) l) were obtained in hydrolysate neutralized with phosphoric acid. However, when urea was the nitrogen source the cell yield was less than half of that obtained with ammonium sulfate.; CNPq, Brazil[200702/2006-8]

Response surface methodology (RSM) to evaluate moisture effects on corn stover in recovering xylose by DEO hydrolysis

Rodrigues, Rita C. L. B.; Kenealy, William R.; Dietrich, Diane; Jeffries, Thomas W.
Fonte: ELSEVIER SCI LTD; OXFORD Publicador: ELSEVIER SCI LTD; OXFORD
Tipo: Artigo de Revista Científica
ENG
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67.26%
Response surface methodology (RSM), based on a 2(2) full factorial design, evaluated the moisture effects in recovering xylose by diethyloxalate (DEO) hydrolysis. Experiments were carried out in laboratory reactors (10 mL glass ampoules) containing corn stover (0.5 g) properly ground. The ampoules were kept at 160 degrees C for 90 min.(-) Both DEO concentration and corn stover moisture content were statistically significant at 99% confidence level. The maximum xylose recovery by the response surface methodology was achieved employing both DEO concentration and corn stover moisture at near their highest levels area. We amplified this area by using an overlay plot as a graphical optimization using a response of xylose recovery more than 80%. The mathematical statistical model was validated by testing a specific condition in the satisfied overlay plot area. Experimentally, a maximum xylose recovery (81.2%) was achieved by using initial corn stover moisture of 60% and a DEO concentration of 4% w/w. The mathematical statistical model showed that xylose recovery increases during DEO corn stover acid hydrolysis as the corn stover moisture level increases. This observation could be important during the harvesting of corn before it is fully dried in the field. The corn stover moisture was an important variable to improve xylose recovery by DEO acid hydrolysis. (c) 2011 Elsevier Ltd. All rights reserved.; CNPq...

Avaliação de parâmetros agronômicos e nutricionais em híbridos de milho (Zea mays L.) para silagem.; Agronomic and nutritional characteristics of corn hybrids for silage.

Dias, Francisco Nogueira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/07/2002 PT
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46.97%
A porcentagem de grãos na MS é um dos principais parâmetros utilizados na determinação da qualidade do milho para silagem. A partir da década de 80 alguns trabalhos mostraram a importância da porção volumosa da planta na digestibilidade e valor nutritivo da silagem. Este trabalho avaliou as características agronômicas, frações químicas, digestibilidade da planta e potencial de produção de leite em vinte híbridos testados em quatro localidades do Estado de São Paulo. O material foi colhido quando os grãos atingiram o ponto de maturidade (2/3 da linha de leite), sendo esse dividido em grãos, espiga, haste e folhas, para análise posterior. Primeiramente, todas as amostras foram analisadas por espectroscopia (NIRS), para definir quais delas deveriam ser analisadas pela metodologia convencional com a finalidade de melhorar as curvas de predição. Segundo, as amostras selecionadas foram analisadas para se determinar os teores de FDN, FDN digestível, amido e amido digestível. E em terceiro, esses resultados obtidos foram utilizados para calcular a equação de regressão para estimar os teores de MS, FDN, FDN digestível, FDA, amido, amido digestível, EE, MM, proteína e digestibilidade “in vitro” da haste e da planta toda. Estes resultados foram utilizados para se determinar as correlações entre dados agronômicos e frações químicas...

Molybdenum mixed with glyphosate and alone via foliar spray in no-tillage common bean grown on corn stover

Camelo,Gessimar Nunes; Araújo,Geraldo Antonio de Andrade; Fontes,Renildes Lucio Ferreira; Dias,Luiz Antonio dos Santos; Carneiro,José Eustáquio de Souza; Lisboa Júnior,Jamir de Moraes de; Damato Neto,José
Fonte: Universidade Federal de Viçosa Publicador: Universidade Federal de Viçosa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2014 EN
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46.59%
The effect of molybdenum (Mo) on common bean grown in desiccated corn stover in a no-tillage system was evaluated under two application modes: Mo mixed with the desiccant glyphosate and Mo direct spray to the bean leaves. The treatments (four replicates) were assigned to a completely randomized block design in a split-plot arrangement with the application of Mo (0, 100, 200, 400 and 800 g ha-1) mixed with glyphosate in the main plots and Mo foliar spray (0 and 100 g ha-1) in the sub-plots. The field experiments were carried out in 2009 and 2010 in the municipality of Coimbra, Minas Gerais State, with the common bean cultivar Ouro Vermelho. Mo mixed with glyphosate had neither an effect on common bean yield nor on the Mo and N contents in leaves, however it increased the Mo and N contents in seeds. Application of Mo via foliar spray increased Mo content in leaves and Mo and N contents in seeds. The reapplication of molybdenum with glyphosate for desiccation in subsequent crops caused a cumulative effect of Mo content in bean seeds.

Caracterização de membranas assimétricas de acetato de celulose produzidas a partir do aproveitamento do resíduo da palha de milho para uso em ultrafiltração

Ribeiro,Elaine Angélica Mundim; Rodrigues Filho,Guimes; Vieira,Júlia Graciele; Sousa,Raquel Maria Ferreira de; Assunção,Rosana Maria Nascimento de; Meireles,Carla da Silva; Duarte,Jocelei; Zeni,Mara
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 PT
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46.96%
Cellulose acetates (CA) with different degrees of acetylation were synthesized from cellulose extracted from corn stover. Membranes were prepared for the ultrafiltration process with pure polymers and blend form of CA utilizing a dioxane/acetone system. The membranes were characterized according to their transport properties. The blend form materials presented the best results for application in ultrafiltration experiments. M-TAC/DAC (corn stover triacetate and diacetate) and M-TAC/DAC-Rho (corn stover triacetate and Rhodia diacetate) presented rejection to egg albumin protein of 87.39% and 80.50%, respectively. Thus, MWCO of 45 kDa was determined for these materials.

In situ degradability of corn stover and elephant-grass harvested at four stages of maturity

Silva,Luis Felipe Prada e; Cassoli,Laerte Dagher; Roma Júnior,Luiz Carlos; Rodrigues,Ana Carolina de Oliveira; Machado,Paulo Fernando
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
57.18%
Among tropical forages, corn silage is largely used by farmers trying to explore the maximum genetic potential from the animals. However, other tropical forages, such as elephant-grass (Pennisetum purpureum), are more productive and therefore cheaper to use than corn silage. Our objective was to compare the in situ degradability of elephant-grass with that from corn hybrids, all harvested at four stages of maturity. The experimental design followed a randomized block design with nested subplots. Two corn hybrids: AG5011, ZN8392 were harvested with 25, 30, 35, and 40% dry matter (DM) in the whole plant, and separated in stem + leaf sheath + leaf blade (stover), and cobs. Elephant-grass was harvested with 30, 40, 50 and 60 days after a leveling cut. Dried and ground samples were incubated in nylon bags inside the rumen for 0, 6, 12, 24, 48 and 72 h to estimate the kinetics of ruminal DM and neutral detergent fiber (NDF) degradation. The advance of maturity increased the NDF and acid detergent fiber (ADF) content in elephant-grass, and reduced its DM degradability. However, maturity had little or no effect on fiber content and DM degradability of corn stover. Elephant-grass had a higher NDF degradability than corn stover, and there was no effect of maturity on NDF degradability of either elephant-grass or corn stover. Fiber degradability of elephant-grass was not worse than that of corn stover...

Cellulosic ethanol production from AFEX-treated corn stover using Saccharomyces cerevisiae 424A(LNH-ST)

Lau, Ming W.; Dale, Bruce E.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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46.59%
Current technology using corn stover (CS) as feedstock, Ammonia Fiber Expansion (AFEX) as the pretreatment technology, and Saccharomyces cerevisiae 424A(LNH-ST) as the ethanologenic strain in Separate Hydrolysis and Fermentation was able to achieve 191.5 g EtOH/kg untreated CS, at an ethanol concentration of 40.0 g/L (5.1 vol/vol%) without washing of pretreated biomass, detoxification, or nutrient supplementation. Enzymatic hydrolysis at high solids loading was identified as the primary bottleneck affecting overall ethanol yield and titer. Degradation compounds in AFEX-pretreated biomass were shown to increase metabolic yield and specific ethanol production while decreasing the cell biomass generation. Nutrients inherently present in CS and those resulting from biomass processing are sufficient to support microbial growth during fermentation. This platform offers the potential to improve the economics of cellulosic ethanol production by reducing the costs associated with raw materials, process water, and capital equipment.

Comparison of Ultrasonic and CO2 Laser Pretreatment Methods on Enzyme Digestibility of Corn Stover

Tian, Shuang-Qi; Wang, Zhen-Yu; Fan, Zi-Luan; Zuo, Li-Li
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 29/03/2012 EN
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46.82%
To decrease the cost of bioethanol production, biomass recalcitrance needs to be overcome so that the conversion of biomass to bioethanol becomes more efficient. CO2 laser irradiation can disrupt the lignocellulosic physical structure and reduce the average size of fiber. Analyses with Fourier transform infrared spectroscopy, specific surface area, and the microstructure of corn stover were used to elucidate the enhancement mechanism of the pretreatment process by CO2 laser irradiation. The present work demonstrated that the CO2 laser had potential to enhance the bioconversion efficiency of lignocellulosic waste to renewable bioethanol. The saccharification rate of the CO2 laser pretreatment was significantly higher than ultrasonic pretreatment, and reached 27.75% which was 1.34-fold of that of ultrasonic pretreatment. The results showed the impact of CO2 laser pretreatment on corn stover to be more effective than ultrasonic pretreatment.

Complex Physiology and Compound Stress Responses during Fermentation of Alkali-Pretreated Corn Stover Hydrolysate by an Escherichia coli Ethanologen

Schwalbach, Michael S.; Keating, David H.; Tremaine, Mary; Marner, Wesley D.; Zhang, Yaoping; Bothfeld, William; Higbee, Alan; Grass, Jeffrey A.; Cotten, Cameron; Reed, Jennifer L.; da Costa Sousa, Leonardo; Jin, Mingjie; Balan, Venkatesh; Ellinger, James
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/2012 EN
Relevância na Pesquisa
46.59%
The physiology of ethanologenic Escherichia coli grown anaerobically in alkali-pretreated plant hydrolysates is complex and not well studied. To gain insight into how E. coli responds to such hydrolysates, we studied an E. coli K-12 ethanologen fermenting a hydrolysate prepared from corn stover pretreated by ammonia fiber expansion. Despite the high sugar content (∼6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate, E. coli ceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses during an exponential growth phase, a transition phase, and the glycolytically active stationary phase. During the exponential and transition phases, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate. However, after the majority of amino acids were depleted, the cells entered stationary phase, and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic...

Complete Genome Sequence of Clostridium sp. Strain BNL1100, a Cellulolytic Mesophile Isolated from Corn Stover

Li, Luen-Luen; Taghavi, Safiyh; Izquierdo, Javier A.; van der Lelie, Daniel
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2012 EN
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46.59%
We present the full genome sequence of Clostridium sp. strain BNL1100, a Gram-positive, endospore-forming, lignocellulolytic bacterium isolated from a corn stover enrichment culture. The 4,613,747-bp genome of strain BNL1100 contains 4,025 putative protein-coding genes, of which 103 are glycoside hydrolases, the highest detected number in cluster III clostridia.

Efficient production of polymer-grade L-lactic acid from corn stover hydrolyzate by thermophilic Bacillus sp. strain XZL4

Xue, Zhangwei; Wang, Limin; Ju, Jiansong; Yu, Bo; Xu, Ping; Ma, Yanhe
Fonte: Springer International Publishing AG Publicador: Springer International Publishing AG
Tipo: Artigo de Revista Científica
Publicado em 29/10/2012 EN
Relevância na Pesquisa
46.96%
Lactic acid has been identified as one of the top 30 potential building-block chemicals from biomass. Therefore, the search for cheap raw materials is an objective to reduce the production costs. Efficient polymer-grade L-lactic acid production was achieved in this report by a thermophilic strain Bacillus sp. XZL4 using corn stover hydrolyzate as sole carbon source. High L-lactic acid concentration (81.0 g L-1) was obtained from 162.5 g L-1 concentrated corn stover hydrolyzate (total reducing sugar of 83.0 g L-1) with a volumetric productivity of 1.86 g L-1 h-1 (0–36 h) and a product yield of 0.98 g g-1 total reducing sugars. This is the highest L-lactic acid concentration and yield reported from corn stover hydrolyzate. And the high optical purity of L-lactic acid obtained in this study also indicated that Bacillus sp. XZL4 is a promising polymer-grade L-lactic-acid producer from cellulosic biomass.

Efficient extraction of xylan from delignified corn stover using dimethyl sulfoxide

Rowley, John; Decker, Stephen R.; Michener, William; Black, Stuart
Fonte: Springer Berlin Heidelberg Publicador: Springer Berlin Heidelberg
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.59%
Xylan can be extracted from biomass using either alkali (KOH or NaOH) or dimethyl sulfoxide (DMSO); however, DMSO extraction is the only method that produces a water-soluble xylan. In this study, DMSO extraction of corn stover was studied at different temperatures with the objective of finding a faster, more efficient extraction method. The temperature and time of extraction were compared followed by a basic structural analysis to ensure that no significant structural changes occurred under different temperatures. The resulting data showed that heating to 70 °C during extraction can give a yield comparable to room temperature extraction while reducing the extraction time by ~90 %. This method of heating was shown to be the most efficient method currently available and was shown to retain the important structural characteristics of xylan extracted with DMSO at room temperature.

Multiscale deconstruction of molecular architecture in corn stover

Inouye, Hideyo; Zhang, Yan; Yang, Lin; Venugopalan, Nagarajan; Fischetti, Robert F.; Gleber, S. Charlotte; Vogt, Stefan; Fowle, W.; Makowski, Bryan; Tucker, Melvin; Ciesielski, Peter; Donohoe, Bryon; Matthews, James; Himmel, Michael E.; Makowski, Lee
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 20/01/2014 EN
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46.82%
Lignocellulosic composite in corn stover is a candidate biofuel feedstock of substantial abundance and sustainability. Its utilization is hampered by resistance of constituent cellulose fibrils to deconstruction. Here we use multi-scale studies of pretreated corn stover to elucidate the molecular mechanism of deconstruction and investigate the basis of recalcitrance. Dilute acid pretreatment has modest impact on fibrillar bundles at 0.1 micron length scales while leading to significant disorientation of individual fibrils. It disintegrates many fibrils into monomeric cellulose chains or small side-by-side aggregates. Residual crystalline fibrils lose amorphous surface material, change twist and where still cross-linked, coil around one another. Yields from enzymatic digestion are largely due to hydrolysis of individual cellulose chains and fragments generated during pretreatments. Fibrils that remain intact after pretreatment display substantial resistance to enzymatic digestion. Optimization of yield will require strategies that maximize generation of fragments and minimize preservation of intact cellulosic fibrils.

Characteristics of Corn Stover Pretreated with Liquid Hot Water and Fed-Batch Semi-Simultaneous Saccharification and Fermentation for Bioethanol Production

Li, Xuezhi; Lu, Jie; Zhao, Jian; Qu, Yinbo
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 24/04/2014 EN
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47.05%
Corn stover is a promising feedstock for bioethanol production because of its abundant availability in China. To obtain higher ethanol concentration and higher ethanol yield, liquid hot water (LHW) pretreatment and fed-batch semi-simultaneous saccharification and fermentation (S-SSF) were used to enhance the enzymatic digestibility of corn stover and improve bioconversion of cellulose to ethanol. The results show that solid residues from LHW pretreatment of corn stover can be effectively converted into ethanol at severity factors ranging from 3.95 to 4.54, and the highest amount of xylan removed was approximately 89%. The ethanol concentrations of 38.4 g/L and 39.4 g/L as well as ethanol yields of 78.6% and 79.7% at severity factors of 3.95 and 4.54, respectively, were obtained by fed-batch S-SSF in an optimum conditions (initial substrate consistency of 10%, and 6.1% solid residues added into system at the prehydrolysis time of 6 h). The changes in surface morphological structure, specific surface area, pore volume and diameter of corn stover subjected to LHW process were also analyzed for interpreting the possible improvement mechanism.

Assessment of the Nutritive Value of Whole Corn Stover and Its Morphological Fractions

Li, H. Y.; Xu, L.; Liu, W. J.; Fang, M. Q.; Wang, N.
Fonte: Asian-Australasian Association of Animal Production Societies (AAAP) and Korean Society of Animal Science and Technology (KSAST) Publicador: Asian-Australasian Association of Animal Production Societies (AAAP) and Korean Society of Animal Science and Technology (KSAST)
Tipo: Artigo de Revista Científica
Publicado em /02/2014 EN
Relevância na Pesquisa
47.25%
This study investigated the chemical composition and ruminal degradability of corn stover in three maize-planting regions in Qiqihaer, Heilongjiang Province, China. The whole stover was separated into seven morphological fractions, i.e., leaf blade, leaf sheath, stem rind, stem pith, stem node, ear husk, and corn tassel. The assessment of nutritive value of corn stover and its fractions was performed based on laboratory assays of the morphological proportions, chemical composition, and in situ degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF). The chemical composition of corn stover was significantly different from plant top to bottom (p<0.05). Among the whole corn stover and seven morphological fractions, leaf blade had the highest crude protein (CP) content and the lowest NDF and ADF contents (p<0.05), whereas stem rind had the lowest CP content and the highest ADF and acid detergent lignin (ADL) contents (p<0.05). Ear husk had significantly higher NDF content and relatively lower ADL content than other corn stover fractions. Overall, the effective degradability of DM, NDF, and ADF in rumen was the highest in leaf blade and stem pith, followed by ear husk. The results indicate that leaf blade...

Engineering and Two-Stage Evolution of a Lignocellulosic Hydrolysate-Tolerant Saccharomyces cerevisiae Strain for Anaerobic Fermentation of Xylose from AFEX Pretreated Corn Stover

Parreiras, Lucas S.; Breuer, Rebecca J.; Avanasi Narasimhan, Ragothaman; Higbee, Alan J.; La Reau, Alex; Tremaine, Mary; Qin, Li; Willis, Laura B.; Bice, Benjamin D.; Bonfert, Brandi L.; Pinhancos, Rebeca C.; Balloon, Allison J.; Uppugundla, Nirmal; Liu,
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 15/09/2014 EN
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46.59%
The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX)-pretreated corn stover hydrolysate (ACSH). We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution...

Síntese, caracterização e aplicação de membranas de acetato de celulose a partir da reciclagem da palha de milho em processo de ultrafiltração

Ribeiro, Elaine Angélica Mundim
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
46.96%
Neste trabalho a palha de milho (PM) foi utilizada como fonte alternativa de celulose para produção de acetato de celulose (AC) visando, além da produção de membranas assimétricas, o estudo de suas caracteristicas morfológicas e propriedades de transporte. A PM foi previamente purificada e caracterizada de acordo com seus teores de celulose, hemicelulose e lignina. A celulose da palha de milho foi acetilada e se obteve dois tipos de AC com graus de acetilações diferentes. Estes foram caracterizados por espectroscopia de infravermelho, calorimetria diferencial exploratória (DSC), termogravimetria (TGA), difratometria de Raio-X, determinação do grau de substituição por via química e por massa molecular viscosimétrica. Os ACs da palha de milho obtidos apresentaram um grau de substituição de 2,78 e 2,49, sendo, portanto, caracterizados como triacetato de celulose e diacetato de celulose, respectivamente. As propriedades dos ACs produzidos a partir da PM foram comparados com o AC comercial (Rhodia) na forma de membranas. Estas membranas foram preparadas utilizando um sistema AC/dioxano/acetona pelo método de inversão de fases, que levou à formação de membranas assimétricas. As membranas foram caracterizadas por Microscopia Eletrônica de Varredura (MEV)...

In situ degradability of corn stover and elephant-grass harvested at four stages of maturity; Degradabilidade in situ de híbridos de milho e de capim-elefante colhidos em quatro estádios de maturidade

Silva, Luis Felipe Prada e; Cassoli, Laerte Dagher; Roma Júnior, Luiz Carlos; Rodrigues, Ana Carolina de Oliveira; Machado, Paulo Fernando
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/12/2008 ENG
Relevância na Pesquisa
57.18%
Dentre as forragens, a silagem de milho é amplamente utilizada pelos fazendeiros que visam explorar o máximo do potencial genético dos animais. No entanto, outros volumosos tropicais como o capim-elefante (Pennisetum purpureum) são mais produtivos e, portanto, mais baratos do que a silagem de milho. Nosso objetivo foi comparar a degradabilidade in situ do capim-elefante com a degradabilidade de híbridos de milho, colhidos em quatro estágios de maturidade. O experimento seguiu um delineamento de blocos ao acaso com sub-parcelas. Dois híbridos de milho: AG5011 e ZN8392 foram colhidos com 25, 30, 35 e 40% matéria seca (MS) na planta toda e separados na fração colmo + bainha + folhas e espigas. Capim elefante foi colhido 30, 40, 50 e 60 dias após o corte de nivelamento. As amostras secas e trituradas foram incubadas no rúmen por 0, 6, 12, 24, 48 e 72 h para cálculo da cinética da degradação ruminal da MS e da fibra em detergente neutro (FDN). O avanço da maturidade aumentou os teores de FDN e fibra em detergente ácido (FDA) do capim elefante e reduziu a degradabilidade da MS. Entretanto, a maturidade teve pouco efeito sobre os teores de fibra e a degradabilidade da MS da fração planta dos híbridos de milho. O capim elefante apresentou maior degradabilidade da FDN do que híbridos de milho...

Corn Stover Harvest Strategy Effects on Grain Yield and Soil Quality Indicators

Karlen,Douglas L.; Birrell,Stuart J.; Wirt,Adam R.
Fonte: Agrociencia Uruguay Publicador: Agrociencia Uruguay
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
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47.02%
Developing strategies to collect and use cellulosic biomass for bioenergy production is important because those materials are not used as human food sources. This study compared corn (Zea mays L.) stover harvest strategies on a 50 ha Clarion-Nicollet-Webster soil Association site near Emmetsburg, Iowa, USA. Surface soil samples (0 to 15 cm) were analyzed after each harvest to monitor soil organic carbon (SOC), pH, phosphorus (P) and potassium (K) changes. Grain yields in 2008, before the stover harvest treatments were imposed, averaged 11.4 Mg ha-1. In 2009, 2010, and 2011 grain yields averaged 10.1, 9.7, and 9.5 Mg ha-1, respectively. Although grain yields after stover harvest strategies imposed were lower than in 2008, there were no significant differences among the treatments. Four-year average stover collection rates ranged 1.0 to 5.2 Mg ha-1 which was 12 to 60% of the above-ground biomass. SOC showed a slight decrease during the study, but the change was not related to any specific stover harvest treatment. Instead, we attribute the SOC decline to the tillage intensity and lower than expected crop yields. Overall, these results are consistent with other Midwestern USA studies that indicate corn stover should not be harvested if average grain yields are less than 11 Mg ha-1