1,720,965 research outputs found
Synthesis and characterisation of sol- gel based ionogels as electrolyte for supercapacitors
Get PDFWith growing public demand for consumer safety regarding electronic devices,
ionogels have recently been suggested as a safe and solid replacement for the
conventional flammable and toxic organic electrolytes used for various energy
storage devices including batteries and supercapacitors. Ionogels are porous
solid scaffolds that encapsulate ionic liquids and prevent electrolyte leakage
which can otherwise be a potential hazard to the consumer or the surrounding
circuitry. In this work, sol-gel was utilised as a manufacturing technique for 1-
ethyl-3-methylimidazolium trifluoromethanesulfonate based-ionogels. Sol-gel
chemistry is a facile and industrially relevant technology that allows the formation
of solid scaffolds from homogenous precursors including a variety of silicon
alkoxides. Previous studies have used a single or a mixture of silicon alkoxides
to fabricate ionogels. In this work, four different precursors (two
tetraalkoxysilanes and two alkyltrialkoxysilanes) were utilised to explore the influence
of the type of silicon alkoxide on the reaction kinetics, thermal stability,
microstructure and the electrochemical performance of the ionogels as electrolyte
for electric double-layer capacitors (EDLCs).
Furthermore, thermally-cured 1-ethyl-3-methylimidazolium trifluoromethanesulfonate-
based ionogels have been realised for the first time in this work. The
influence of curing temperature on the structure of the ionogels and their electrochemical
performance as the electrolyte for EDLCs have been investigated.
Ionogels were synthesised via a non-hydrolytic sol-gel route and were fully
gelled post heat-treating at 125, 150, 175 and 200°C for 60 minutes with minimal
shrinkage. Charge transfer resistance (a rate-limiting parameter in cell kinetics
during charge/discharge cycles) was reduced by ∼80% via increasing the
heat-treatment temperature; this was partially attributed to the interlocking effect
at the electrode-electrolyte interface facilitated by high curing temperature. The
fast-cure fabrication process for ionogels removes one of the major hurdles in
their industrial application, their long curing and aging time, while the improved
room temperature ion transport kinetics expands the potential application of ionic
liquid-based electrochemical systems. Finally, an exploratory investigation on
the long-term stability of the fabricated EDLCs indicated that cells with 150°C cured ionogels show an improved electrochemical performance compared to
the EDLCs with ionic liquid electrolyte without the gel network.
The results gathered in this work provide an insight into sol-gel processed ionogels
as a replacement for the conventional electrolyte formulations and further
proves that, this class of materials has the potential to be a safe, solid and durable
electrolyte for EDLCs
Corrosion behaviour of welded joints within chloride and chloride/CO[2] environments.
Get PDFElectrochemical measurements and metallographic studies were performed on welded carbon steel pipeline materials. Corrosion tests were performed within naturally chloride solution with and without CO[2] additions at ambient temperature. The pH within different environments, chloride solution alone and buffered chloride solution with CO[2] additions was measured at 6.3 +/- 0.3 and 6.2 +/-0.1 respectively. The objective of this study was to evaluate the corrosion behaviour (rates) of carbon steel welds using both traditional and novel electrochemical scanning techniques within two different chloride environments. Corrosion tests were conducted using DC steady state and scanning electrochemical techniques. These tests consisted of linear polarisation resistance (LPR), corrosion potential (Ecorr)} zero resistance ammetry (ZRA), cathodic polarisation (CP) and the scanning vibrating electrode technique (SVET), which were used to semi-quantitatively assess the corrosion activity of the different microstructures, i.e., weld metal (WM), heat-affected zone (HAZ) and parent plate (PP) respectively. Samples were freshly ground before exposure to the different aqueous chloride solutions. SVET was used during these investigations to evaluate preferential corrosion susceptibilities of weldments. SVET results were compared with results from (long term-immersion) DC-based electrochemical corrosion tests. SVET was found to be a sensitive technique with good resolution allowing differences in corrosion response to be determined within hours as compared to other corrosion tests that require several hours to days
Development of Hybrid Sol-Gel Coatings on AA2024-T3 with Environmentally Benign Corrosion Inhibitors
Get PDFAluminium alloys are still considered as one of the primary light alloys with high strength that
can be used in aerospace and marine structure with a moderate economic cost. However,
aluminium alloys are affected by atmospheric and marine corrosion which reduces their
overall reliability. The application of coatings is one of the strategies for mitigating the
corrosion on aluminium alloys. Sol-gel technology is one of the coating strategies with
potential for excellent chemical and environment stability, providing eco-friendly
performance improvement. Sol-gel coatings can enhance corrosion resistance by adopting
many corrosion inhibitors that can protect aluminium alloys substrates from corrosion.
In this project, three approaches are developed and studied to protect AA 2024 in high salinity
of 3.5% NaCl environment. The first approach involved studying the direct application of
film-forming environmentally benign corrosion inhibitors on the surface of the substrate
without any involvement of the coating, these inhibitors are benzimidazole (BZI) and oleic
acid (OA), and were studied alone and in combination. The second approach, investigated the
corrosion protection of two sets of novel hybrid organic-inorganic sol-gel derived coatings
using low-temperature cure processes at 80°C. The base sol-gel formula was made using
alkoxide silane-based precursors including; tetraethylorthosilicate silane (TEOS) and
trimethoxymethyl silane (MTMS) and this was labelled as (SBX- 80). The other enhanced
formula was developed by adding the fluorinated precursor, 1H.1H.2H.2Hperfluorodecyltriethoxy silane (PFOTS), to the base SBX-80 formula to synthesis the
fluorinated-sol-gel formula and this was labelled as (F-SBX-80). The third approach
investigated the addition of corrosion inhibitors of benzimidazole (BZI) and oleic acid (OA)
to the base SBX formula to increase the corrosion protection, either alone or in combination.
All sol-gel derived coating systems, including those modified with BZI or OA corrosion
inhibitors exhibited excellent corrosion protection as evidenced visually, or by
electrochemical methods with various levels of stability when immersed in saline solution.
The coatings exhibited high capacitance and resistance that might provide active/barrier
corrosion protection at small thicknesses less than 20 μm. Furthermore, there was an
enhancement on mechanical properties of coating films with insignificant effect on the
adhesion to the aluminium alloy substrate combined with excellent cracking-resistance. There
was also a significant increase in surface water contact angle for these systems, which
indicates the potential for enhanced easy-cleaning features
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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