1,720,987 research outputs found
Biochemical characterization of a maize stover beta-exoglucanase and its use in lignocellulose conversion
No full textPlant is one of the important resources for glycosyl hydrolase production. A beta-exoglucanase with molecular weight of 63.1 kDa was purified from fresh maize stover and subjected to enzymatic characterization. The optimal temperature and pH of the beta-exoglucanase was 40 degrees C and 6.0, respectively. The beta-exoglucanase was active against p-nitrophenyl-cellobiose (p-NPC), laminarin, cellotriose, cellotetraose, cellopentaose, Avicel, filter paper, and cotton cellulose. The analysis of hydrolytic mode suggested that the beta-exoglucanase removed cellobiose from the ends of beta-glucan. Kinetic parameters of the beta-exoglucanase for laminarin and p-NPC were determined. The effects of metal ions and chemical reagents on the beta-exoglucanase activity were also studied. The biochemical characterization of the beta-exoglucanase makes it an appealing cellulase additive in converting lignocelluloses to ethanol through simultaneous saccharification and fermentation. The synergism of the beta-exoglucanase or crude cell wall proteins of fresh maize stover with Trichoderma reesei cellulase was observed in ethanol production from lignocellulose. (C) 2010 Elsevier Ltd. All rights reserved
Synergism between hydrophobic proteins of corn stover and cellulase in lignocellulose hydrolysis
No full textTo investigate the characteristics and Values of plant proteins for lignocellulose conversion, cellulase synergetic proteins for lignocellulose hydrolysis were separated from fresh corn stover. The synergetic proteins have strong hydrophobic characterization, yet no cellulose hydrolytic activity. Mass spectrometry analysis indicated that the hydrophobic protein with highest abundance might be cell membrane protein of Zea mays. Compared with steam-exploded corn stover hydrolysis with microbial cellulase mixture, the glucose production was improved by 31.88% with hydrophobic proteins addition. Synergetic mechanism analysis indicated that the hydrophobic proteins reduced unspecific cellulase adsorption onto non-cellulose component of lignocelluloses during hydrolysis. The effect is more significant for exoglucanase and beta-glucosidase. The amount of hydrophobic proteins in fresh corn stover is large. Therefore, Supplementing microbial cellulase complex with hydrophobic proteins of plant for lignocellulose hydrolysis is a promising way for cost reduction in lignocellulose conversion. (C) 2009 Elsevier B.V. All Fights reserved
A beta-xylosidase from cell wall of maize: Purification, properties and its use in hydrolysis of plant cell wall
No full textTo study the potential of plant glycoside hydrolase for hemicelluloses hydrolysis, a beta-xylosidase with molecular weight of 68.5 kDa was purified from the maize during senescent stage. The optimal conditions for the beta-xylosidase were 37 degrees C and pH 4.5. In absence of substrate, the beta-xylosidase was comparatively stable at 37 degrees C and pH 4.5-5.5. At the optimum condition, the K(m) and k(cat) values of the beta-xylosidase against p-nitrophenyl-xyloside were 2.5 mM and 6.5 s(-1), respectively. The enzyme activity was promoted by LiCl, CaCl(2), MnCl(2), MgCl(2), KCl. and NaCl, however severely inhibited by CuCl(2), ZnCl(2), AgNO(3), HgCl(2), and NiCl(2). The purified beta-xylosidase was active against xylobiose, xylotriose, xylotetraose, and xylopentaose. In hydrolysis of corn stover hemicellulose, the xylose production increased by 94.9% and 140% when Trichoderma reesei hemicellulase supplemented with purified beta-xylosidase and crude cell wall proteins of corn stover, respectively. The biochemical characterization of the maize beta-xylosidase makes it a promising candidate enzyme additive for hemicelluloses hydrolysis. (C) 2010 Elsevier By. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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