1,720,959 research outputs found
“Synthesis of Nanostructured Metal-Chitosan Hybrids by Laser Ablation in Liquid”
Get PDFThe growing focus on environmental sustainability, coupled with the need to enhance technological performance across various industrial sectors, has led to an increasing interest in the development of innovative materials. In this scenario, composite materials are emerging as key players, owing to their ability to combine superior properties through the synergistic interaction of different components. Among composites, biopolymers stand out as a particularly promising class, as they merge biodegradability and biocompatibility characteristics with a reduced environmental impact compared to traditional materials. Specifically, chitosan, a polysaccharide derived from chitin, is renowned for its exceptional biological and chemical properties, making it an ideal candidate for applications ranging from biomedical to agri-food, environmental, and industrial fields.
Concurrently, nanomaterial production techniques have rapidly evolved in recent decades, with a particular emphasis on sustainable and non-toxic methods. Among these techniques, laser ablation in liquids (LAL) has garnered interest as a versatile and eco-friendly approach for nanomaterial synthesis. LAL enables the control of the properties of the nanoparticles produced without the use of harmful chemicals, thereby minimizing waste and environmental emissions. This study explores the innovative potential of composite materials, focusing on the synergy between metallic nanoparticles (AgNPs and CuNPs) and chitosan. The research primarily centres on the synthesis and characterization of these materials through laser ablation in liquids (LAL), a technique that offers fine and precise control over the properties of the obtained nanoparticles, allowing for the modulation of their size, morphology, and chemical composition.
A significant aspect of this study is the utilization of chitosan derived from Hermetia illucens, an alternative and sustainable source compared to traditional marine sources, thus promoting a more ecological and responsible approach in biomaterial production. The in-depth analysis of LAL process parameters has enabled a detailed understanding of their influence on the morphological and physicochemical characteristics of metal-chitosan composites. In particular, the crucial role of chitosan in modulating the formation, growth, and stability of metallic nanoparticles has been highlighted, significantly affecting their final properties. The experimental results obtained have demonstrated the antimicrobial efficacy of the silver composites, with a particular focus on their biocompatibility with fibroblast cell lines, representative of connective tissue. Furthermore, the ability of these composites to inhibit the growth of common and clinically relevant pathogens, such as Staphylococcus aureus and Escherichia coli, has been evaluated, paving the way for potential applications in infection prevention.
An additional area of investigation has been the application of these materials as coatings for bone implants, using the electrophoretic deposition (EPD) technique. This method has proven its effectiveness in producing thin and uniform films on implant surfaces, imparting enhanced antibacterial and biocompatible properties, which are fundamental for promoting osseointegration and reducing the risk of implant failure. The investigation has also extended to the environmental domain, evaluating the efficacy of silver-chitosan nanocomposites in the photocatalytic degradation of organic dyes, such as methylene blue, present in industrial wastewater. The results obtained have highlighted their potential as efficient catalysts for the removal of organic pollutants, under both UV and visible light irradiation, suggesting their possible application in water purification processes.
In conclusion, this study underscores the crucial importance of integrating sustainable technologies, such as LAL and the use of alternative chitosan sources, with biocompatible materials to develop innovative and sustainable solutions across various sectors, including biomedicine and the environment
Enhanced relaxation dynamics in silver-doped chitosan nanocomposites: Probing the charge carrier dynamics and terahertz dielectric response
Get PDFThis study investigates the influence of silver nanoparticle incorporation on the electro-optical properties of chitosan, a biocompatible and versatile polymer with promising applications in biomedicine, energy storage, and sensing technologies, to name a few. Silver nanoparticles were synthesized by nanosecond laser ablation of the silver target in the polymeric solution. Terahertz time-domain spectroscopy was used to determine the complex dielectric function of pure chitosan and chitosan-silver nanocomposite films over a broad frequency range. The experimental data were analyzed using theoretical models, based on the Drude-Smith and Havriliak-Negami equations, to elucidate the underlying charge carrier dynamics and dielectric relaxation processes. Additionally, complex impedance and complex dielectric modulus analyses were conducted, incorporating Cole-Cole plots. The findings reveal a significant enhancement in the relaxation dynamics of the nanocomposite compared to pure chitosan, evidenced by a shift towards higher frequencies in the imaginary part of the dielectric function and a characteristic quarter-circle arc in the Cole-Cole plot. This study provides valuable insights into the structure-property relationships governing the electro-optical behavior of chitosan-based nanocomposites, paving the way for their tailored design and optimization for advanced technological 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
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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