1,720,988 research outputs found
Abundance, distribution and bioaccumulation of microplastics and its potential impacts in mangrove environment / Priya Mohan
No full textPlastic pollution has become a global issue of transboundary contamination, necessitating comprehensive interdisciplinary research to comprehend the negative impacts. This research aims to identify the mobility of plastic bottles in the open oceans using GPS, to determine the prevalence and distribution of microplastics in mangrove sediment, water and Anadara granosa, to determine the microplastic uptake in Daphnia magna and A. granosa, and to evaluate the feasibility of valorisation plastic waste through hydrothermal liquefaction (HTL). To achieve the first objective, five tracking devices in PET bottles (B1, B2, B3, B4, and B5) were deployed in Cherating, Matang, and Kuala Selangor and their trajectory movement was monitored using a GPS system. For the second objective, sediment, water, and A. granosa were collected from Matang, Kuala Selangor, Sedili Besar, and Cherating mangroves. The sediment was collected using an auger at a depth of 1-50cm, and the microplastics in water were obtained by submerging a plankton net with a mesh size of 90μm for one hour. While A. granosa were obtained from the study sites. The microplastics from sediment, water and A. granosa were extracted using vacuum filtration and analyzed under a dissecting microscope to categorize them based on sizes, shapes, and colours, while polymer types were determined via FTIR. For the third objective, Daphnia magna and A. granosa were exposed to various shapes and sizes of PP microplastics for 96 and 264 hours, respectively. Microplastic uptake by Daphnia magna and A. granosa was observed using fluorescent and dissecting microscopes, respectively. As for the depolymerization of PP and PET (objective four), the experiment involved different alkaline concentrations and reaction times via a 2-factorial experimental design. The deployment of the tracking device revealed that B2 deployed in the Straits of Malacca travelled the longest distance of 8984 km. Conversely, the remaining B1, B3, B4 and B5 bottles beached at vegetation areas in Tittu Island (Philippines), Ao Talo Malaka (Thailand), Maldives Island and Mersing (Malaysia), respectively. Plastic beaching can cause polymer fragmentation and microplastic accumulation in the marine environment. Studies on microplastic pollution in mangroves found the highest levels in sediment (151 ± 1.91 particles/kg) during the Southwest Monsoon and in water (43400 ± 9.19 particles/m3) during the Intermonsoon. This study also found that A. granosa from Matang had the highest amount of microplastics (0.40 ± 0.2 particles/g). Overall, the dominant microplastic in the sediment, water and A. granosa were particles of <0.1mm, fragment, blue, and rayon polymer. A. granosa also accumulated microorganisms (Pseudomonas, Rhodococcus, Mycoplasma, and Candidatus thiophysa) and chlorinated organic pollutants (1-propene, 1,2,3-trichloro-, (Z)-; 1,1,2,3,3-pentachloropropane, and 1,1,1,2-tetrachloroethane) from its environment. Further laboratory investigation revealed that Daphnia magna and A. granosa preferred uptaking 0.1mm fragment particles. Microplastics pose a significant adverse impact on the marine environment and organisms. Thence, to address plastic pollution and reduce microplastic dispersion, depolymerizing PP (tetrapentacontane, 1,54-dibromo-, 1,54-dibromo-hexacontane, and acetic acid (2,4-dichlorophenyl) methyl ester) and PET (tetrapentacontane, 1,54-dibromo, and dotriacontane) produced fuel byproducts, highlighting sustainable approaches. Further research endeavours are essential to develop effective strategies for mitigating plastic pollution sustainably
Isolation of plastic-degrading fungi from landfill and determining the selected plastics biodegradation capability / Priya Mohan
No full textPolyethylene Terephthalate (PET), Low Density Polyethylene (LDPE) and High Density Polyethylene (HDPE) are the most important polymers used predominantly in present world. Since synthetic polymers hardly undergo degradation and remain in the environment for a very long time, up to 1000 years, these drawbacks increase the percentage of solid wastes in landfill and threaten the environment. To date, Municipal Solid Waste (MSW) landfill is the most favored disposal method especially among the developing countries. The aim of present study is to evaluate the potential of fungus isolated from landfilled plastics to degrade PET, LDPE and HDPE. Besides, effect of different concentrations of the selected inoculum was carried out to investigate the biodegradation of PET, LDPE and HDPE polymers. A total of eight fungi strains were isolated from untreated dumped plastics. In this study, two liquid media (BOD and Bushnell Haas) were used to determine the most desirable broth media by the fungus to perform their degradation activity. The biodegradation of the plastics were confirmed by average radial diameter of fungi colonies and weight loss of the incubated polymers after 30 days of incubation period at 28⁰C. Based on the results obtained, the maximum degradation of mixed plastics (PET, LDPE and HDPE) was attributed to Aspergillus fumigatus (FI 5) strain in both BOD and Bushnell Haas media with an average weight loss of 1.76% and 2.03% respectively. Considering the cost and biodegradability potential of the isolates in the broth media, BOD media was selected over Bushnell Haas media to evaluate the suitability of the media for the fungus to perform the biodegradation activities. On treatment with different concentrations of A. fumigatus, 1% (w/v) inoculum gave highest weight loss for PET plastics (1.5%), while 5% (w/v) noculum showed highest weight loss for LDPE (21.9%) and HDPE (1.31%) films after 30 days of incubation period. The concentrations of inoculum strongly suggest that the factor has a great effect on biodegradation by fungi. Hence, further FTIR analysis was conducted to study the structural changes of the plastic films with maximum reduction in weight loss treated with A. fumigatus. The results showed the potentiality of A. fumigatus to consume these polymers (PET, LDPE and HDPE) as carbon and energy source and the effectiveness of the strains to perform their biodegradation activity can be clearly seen during the optimal condition
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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