1,720,963 research outputs found
Porous Polymeric Membranes with Engineered Surfaces for Water Remediation
No full textAccess to safe drinking water is one of the greatest challenges that have afflicted people
across the globe. Approximately 1.2 billion people do not have access to safe drinking water
while 2.6 billion have no access to sanitation. Around 4,000 children die per day due to
communicable diseases transmitted through contaminated drinking water. Rising population,
the burden on agriculture and technological growth has triggered rapid industrialization leading
to overexploitation and contamination of freshwater aquifers that have declined the
groundwater table. Energy efficient, low cost and effective methodology for water purification
has to be devised in order to address this challenge and reutilize the available resources. To
address this challenge, researchers have turned towards membrane-based separation technology.
Various membrane-based separation processes like microfiltration (MF), ultrafiltration (UF),
nanofiltration (NF) and reverse osmosis (RO) have been extensively used in water purification.
Although these membranes are highly efficient, they lose their performance due to bacterial and
protein fouling i.e. undesirable deposition or accumulation of contaminants such as bacteria and
protein on the membrane surface and/or inside the pores of the membrane. This thesis entitled
“Porous polymeric membranes with engineered surfaces for water remediation” addresses
these key issues using surface engineering of polymeric surfaces and by the fabrication of
new biocidal and foul release materials using polymerization techniques.
Like MF and UF based membranes, RO membranes are also susceptible to fouling and
have limited salt rejection and heavy metal removal capabilities. To address these concerns, the
concept of multilayered membranes was used wherein an antibacterial polymer will be the
active layer, mixed metal organic framework (MMOF) is the interlayer and RO membrane will
be the support layer. This is discussed in Chapter 5. To optimize the best antibacterial polymer,
different polymer tool boxes were tailored by reversible addition-fragmentation chain-transfer
(RAFT) polymerization from quaternary ammonium compound, hyperbranched amine and
phosphonium-based homo/copolymers. The result reflected that one specific polymer was
exemplary in terms of its overall performance but there was a scope of improvement of the
rejection capabilities. This was achievable by changing the interlayer material prudently.
Hence, in Chapter 6 and Chapter 7, the polymer active layer was kept as is and the interlayer
was varied from MMOF to molybdenum disulfide tethered magnetospheres and graphene oxide
anchored MOF, respectively. This mitigated fouling and yielded efficient and excellent
performance for desalination and heavy metal removal. Finally, Chapter 8 sums up the major
conclusions from each chapter and highlights the outcome of the works. It also discusses the
future work that can be undertaken in this research area and new strategies that can be devised
for novel antibacterial and antifouling membranes that can yield unimpeded flow to wate
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
Antibacterial and Antibiofouling Polymeric Membranes through Immobilization of Pyridine Derivative Leading to ROS Generation and Loss in Bacterial Membrane Integrity
No full textPorous, antibacterial and antibiofouling membranes were obtained from immiscible polymer blends using non-solvent induced phase separation. Both antibacterial and antibiofouling was mediated by immobilizing quaternized pyridine derivative on the porous membranes. This was manifested by assessing the metabolic content leakage (K+ ions and nucleic acid) monitored at different time intervals when the membranes were in contact with E.coli (gram negative) and S.aureus (gram positive). Further, the hydrophilic nature of the pyridine derivative led to antibiofouling nature. The hierarchical porous finger-like' morphology was confirmed by Scanning electron Microscopy. The trans-membrane flux was measured using a cross-flow flux setup. A quantitative study of the antibacterial activity was carried out using a standard plate count method. The modified membranes showed 3-log and 2-log reduction in E. coli and S. aureus respectively in 2h and 7-log fold reduction in both bacterial strains in 24h. The oxidative stress generated by the pyridine derivative on both the bacterial strains was assessed by measuring the Reactive Oxygen Species (ROS). The ROS was significantly higher in case of modified membranes which supported the biocidal nature of the pyridine derivative. The antifouling study was carried out by using BSA (Bovine serum albumin) as a model biofoulant. The flux recovery ratio was significantly higher in case of modified membranes
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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