1,720,998 research outputs found
Production of Fungal Laccase Using Orange Peelings as Substrate by Submerged Static Fermentation
Full text linkLaccases are diphenol oxidases that have numerous applications in biotechnological
processes. In this work, the production of fungal laccase using organic and inorganic feed
substrates in submerged static fermentation was investigated.
Study Design: One-factor-at-a-time strategy was adopted to optimize the cultural parameters for
enhanced laccase production.
Place and Duration of Study: Department of Microbiology, Faculty of Science, University of Port
Harcourt, Nigeria, between October 2014 and November 2015.
Methodology: A total of nine fungal isolates were obtained from wood decaying sites of University
of Port Harcourt forest areas and subjected to laccase screening with 2,2-Azinobis-3-
ethyl(benzthiazoline-6-sulphonate) (ABTS). The influence of medium components using the basal
medium at pH 5.0 as base was evaluated and these cultural parameters include carbon sources
(glycerol, rice bran, glucose and ground orange peelings), nitrogen sources (yeast extract, potassium nitrate, peptone and ammonium chloride), metal ions (copper sulfate and manganese
sulfate) and inducer compounds (ABTS, Tween 80 and soya oil). Time course study was
conducted with the unoptimized and optimized cultural medium.
Results: Out of nine cultures tested, seven were found to be laccase-positive with isolates CF-1
and CF-2 being the best potential cultures. Isolate CF-1 which had the highest laccase activity was
identified as Pleurotus ostreatus and was chosen for further studies. Ground orange peelings (0.1%
w/v) and NH4Cl (0.1% w/v) were the most suitable carbon and nitrogen source for laccase
production by the fungus. Maximum laccase production was obtained with Cu2+ at a concentration
of 0.05%w/v among other metal ions. Soya oil at concentration of 0.05% (v/v) was the best inducer
of the enzyme. The highest laccase production was achieved at an Initial pH 4.5. Under optimal
culture medium, the maximum laccase activity was determined to be 7.21 U ml-1 on the 7th day of
cultivation; which was approximately three times higher than that in basal medium (2.5 U ml-1). The
results obtained indicate that the extracellular laccase production is dependent on various cultural
parameters.
Conclusion: One-factor-at-a-time strategy adopted in this study proved that the optimum
conditions enhanced laccase production by three folds using orange peelings. The results obtained
are very interesting since orange peelings are common agricultural wastes in several countries and
imply that their re-utilization in the production of enzymes would help solve pollution problems
caused by their improper disposal. In addition, Pleurotus ostreatus having shown promise for
laccase production using low-cost lignocellulosic substrates could be suggested as a prospective
candidate for higher laccase production for several biotechnological applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Impacts of pharmaceutical effluents on aquatic ecosystems
Full text linkThe discharge of raw, contaminated, and inadequately treated pharmaceutical wastewa- ter into water supplies and river channels contribute to short, medium, and long- term environmental and human health impacts. The deterioration and depletion of natural re- sources exemplified in recipient surface water systems, entirely account for the poor qual- ity of pharmaceutical wastewater effluent. Consequently, to ensure the safety of commu- nities from polluted environments, this review outlines the different anticipated exposure routes to the environment, situates the impact and fate of some pharmaceutical wastes on the aquatic environment. We highlighted some of the current measures for detecting phar- maceutical effluents and the future trends in the treatment of pharmaceutical effluent
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