1,720,956 research outputs found
Self-Healing Polyurethane Elastomers Based on a Disulfide Bond by Digital Light Processing 3D Printing
No full textA type of polyurethane elastomer with excellent self-healing ability has been fabricated through digital light processing 3D printing. First, a type of polyurethane acrylate containing disulfide bonds is synthesized and then compounded with reactive diluent and photoinitiators to get a photopolymer resin. Due to the good fluidity and high curing rate, the photopolymer resin can be applied in DLP 3D printing, and various 3D objects with complicated structures, high printing accuracy, and remarkable self-healing ability have been printed. The tensile strength and elongation at break of the polyurethane elastomer are 3.39 ± 0.09 MPa and 400.38 ± 14.26%, respectively, and the healing efficiency can get to 95% after healing at 80℃ for 12 h and can be healed for multiple times. With the ease of fabrication and excellent performance, the polyurethane elastomers from DLP 3D printing have great potential applications in flexible electronics, soft robotics, and sensors
Blends of Epoxidized Alkyd Resins Based on Jatropha Oil and the Epoxidized Oil Cured with Aqueous Citric Acid Solution: A Green Technology Approach
Get PDFAlkyd resins were made from jatropha oil using a two-step method that included alcoholysis and polyesterification reactions, using 100% Phthalic Anhydride. To enhance their performance properties, the resins were mixed with different wt % of epoxidized jatropha oil (EJO) and aqueous citric acid, without the need for additional catalysts or solvents. Blending was facilitated via epoxidation of the alkyd resins. The prepared blends were characterized by Fourier transform infrared and NMR (1 H and 13C) spectroscopy studies. It was noted that blending led to significant improvements in properties such as curing time, chemical resistance, scratch hardness, thermal stability, and tensile strength of the alkyd resins. In particular, there was a noticeable increase in tensile strength by 3.18 MPa and thermal stability by 42°C when the blends contained 50% EJO. The results indicate the strong influence of the amount of EJO and citric acid on the performance of the alkyd resins. Additionally, the thermal and mechanical properties of the cured films could be further enhanced through post-curing at 160°C. Overall, the results of this study suggest suitability of these blends in surface coating applications
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
Mechanically Robust, Self-Healing, and Reprocessable Geraniol Based Epoxy Vitrimer by Dynamic Boronic Ester Bonds
No full textCovalent Adaptable Networks (CANs) are an emerging class of polymers with reversible covalent crosslinks that respond dynamically to external stimuli. Unlike conventional thermosets, CANs-particularly vitrimers- exhibit self-healing, reprocessability, shape memory, and recyclability due to their adaptable crosslinking chemistry. The widespread use of thermosets has led to growing concerns over the depletion of petroleum-based resources and environmental impact. To address these challenges, bio-based alternatives offer a sustainable pathway for developing high-performance materials. Geraniol, a naturally occurring monoterpenoid alcohol found in various plant oils, serves as a promising renewable feedstock for polymer synthesis. This study presents the first development of a geraniol-based epoxy vitrimer synthesized via a thermally activated thiol-epoxy click reaction between a geraniol-derived epoxy resin and a diboronic ester dithiol (DBDT) cross-linker. The incorporation of dynamic boronic ester bonds facilitates topological rearrangements, enabling efficient self-healing and reprocessability. The vitrimer demonstrates excellent thermal stability and mechanical strength, with a glass transition temperature (Tg) of 38.43℃ determined through Dynamic Mechanical Analysis (DMA). Additionally, it exhibits a tensile strength of approximately 19 MPa, shape memory behavior, solvent-based recyclability, and outstanding mechanical strength retention after reprocessing. The vitrimer also features a rapid relaxation time of 9 seconds at 140C and an activation energy of 22.44 kJ/mol, highlighting its efficient bond exchange capability. These attributes make the developed vitrimer a strong candidate for sustainable, high-performance applications, offering a viable alternative to traditional thermosets with enhanced environmental benefits
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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