1,720,954 research outputs found
Enhancing The Sustainability of Thermally Induced Phase Separation and Non-Solvent-Induced Phase Separation Techniques for Membrane Fabrication
No full textMembranes are widely used in industrial applications to provide an alternative separation technique to thermally driven separations. Ultrafiltration membranes, in particular, are typically made using phase separation techniques, such as thermally induced phase separation (TIPS) and non-solvent-induced phase separation (NIPS). However, these membrane fabrication strategies pose significant environmental challenges due to the use of hazardous solvents and high energy consumption. This dissertation aims to enhance the sustainability of membrane fabrication by utilizing eco-friendly solvents as such as terpineol, non-toxic plant-based solvent, commonly found in perfumes and cosmetics, and Rhodiasolv® PolarClean, a byproduct of Nylon-66 production that also has a low-hazard profile. Additionally, this research explores the use of recycled plastics.
The first study of this dissertation successfully investigated the impact of the small molecules as additives on the polystyrene terpineol system exhibiting an upper critical solution temperature (UCST). This research highlights a new path to reduce the phase transition temperature for TIPS by managing hydrogen bonding interactions and polymer solubility by decreasing the transition from 65 °C to room temperature. This approach allows membrane formation at room temperature, resulting in lower energy consumption. The fabricated membranes were characterized by analyzing their pore size, morphology, and filtration performance, showing comparable or improved properties over conventionally fabricated membranes.
The second study investigated the fabrication of poly(acrylonitrile-co-butadiene-co-styrene) (ABS) membrane using green solvent and the effect of the diluents on the ABS membrane. Rhodiasolv® PolarClean was used as the primary solvent, and ethanol and acetone were used as additives to study the fabrication of ABS membrane using the NIPS. Using PolarClean as the primary solvent and varying the additive ratios allowed for the control of the membrane morphology and performance. Whereas, using only PolarClean for fabrication ABS resulting fingerlike pore morphology and relatively low bovine serum albumin (BSA) rejection. The additive addition impacts the volatility and stability of the system therefore impacting the kinetic phase inversion, and membrane morphology.
In the third study, recycled polymers from LEGO® blocks, including high impact polystyrene (HIPS), ABS, and poly(methyl methacrylate-co-acrylonitrile-co-butadiene-co-styrene) (MABS), were employed to fabricate membrane via NIPS . There are limited studies of the impact of different polarity segments in HIPS, ABS, and MABS on phase separation of recycled polymer membranes. Membranes were fabricated from recycled LEGO blocks using NIPS with Rhodiasolv® PolarClean and acetone. Blending MABS and ABS allowed to control the ratio of acrylonitrile and methyl methacrylate in the sample. The increase in the ratio of MABS in the blended samples altered the membrane structure from sponge-like to finger-like, likely due to the increased hydrophilicity attributed to the polar block, which allowed water to penetrate as a nonsolvent and caused growth in the lean polymeric phase, resulting in a stretched finger-like sublayer. Blended membranes exhibited only modest changes in their thermal stability and tensile strength, likely due to the similar chemical structures of some segments.
Overall, this dissertation establishes that the sustainability of the membrane fabrication can be improved using small molecular weight additives, green solvent, and recycled polymers resulting in more environmentally friendly polymeric membranes with comparable performance to conventionally synthesized structures
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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