1,720,976 research outputs found
Magnetic Analysis of MgFe Hydrotalcites as Powder and Dispersed in Thin Films within a Keratin Matrix
No full textHydrotalcites (HTlcs) are a class of nanostructured layered materials that may be employed in a variety of applications, from green to bio technologies. In this paper, we report an investigation on HTlcs made of Mg and Fe, recently employed to improve the growth in vitro of osteoblasts within a keratin sponge. We carried out an analysis of powder materials and of HTlcs dispersed in keratin and spin-coated on a Si/SiO2 substrate at different temperatures. A magnetic study of the powders was carried out with a Quantum Design Physical Property Measurement System equipped with a Vibrating Sample Magnetometer. The data gathered prove that these HTlcs are fully paramagnetic, and keratin showed a very small magnetic response. Optical and Atomic Force Microscopy analyses of the thin films provide a detailed picture of clusters randomly dispersed in the films with various dimensions. The magnetic properties of these films were characterized using the Nano Magneto Optical Kerr Effect (NanoMOKE) down to 7.5 K. The data collected show that the local magnetic properties can be mapped with a micrometric resolution distinguishing HTlc regions from keratin ones. This approach opens new perspectives in the characterization of these composite materials
Evaluating two series of layered double hydroxides in the fight against microorganisms
No full textThe increasing prevalence of antimicrobial resistance has created a need for the development of innovative antimicrobial strategies beyond traditional antibiotics. Layered double hydroxides, with their tunable chemical composition and controlled ion release capabilities, have emerged as promising candidates for facing multidrug-resistant pathogens. In this study, layered double hydroxides were synthesized using co-precipitation and double microemulsion methods to produce nanoparticles with distinct particle sizes (diameter and thickness) and intercalated anions. Their antimicrobial activity was evaluated against different bacterial and fungal strains, including Staphylococcus aureus and Candida albicans. The results revealed that layered double hydroxides with smaller particle sizes and intercalated bromide anions demonstrated superior antibacterial efficacy, attributable to enhanced ion release and increased interaction with microbial membranes. Notably, layered double hydroxides prepared by double microemulsion and containing Mg(II), Cu(II), Al(III) and bromide anions exhibited the highest antimicrobial activity, highlighting the impact of particle dimensions and intercalated anion properties on performance. This work highlights the potential of layered double hydroxides based materials as versatile antimicrobial agents, offering a sustainable solution to address the challenges of antimicrobial resistance in clinical and environmental applications
Silk fibroin and pomegranate by-products to develop sustainable active pad for food packaging applications
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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
Keratin-hydrotalcites hybrid films for drug delivery applications
No full textIn this work novel hybrid materials for drug delivery purposes are obtained by combining keratin with hydrotalcite nanoparticles containing diclofenac. The hybrid films showed a less pronounced swelling, porosity and degradation and a greater thermal stability compared to pure keratin films containing free diclofenac. These results, together with the slight shift towards smaller wavelength numbers of amide I band led to the hypothesis of a probable cross-linking between hydrotalcites and the protein mediated by glutaraldehyde, which results in a total reinforcing action on the hybrid material. In addition, diclofenac release profiles of the hybrid film in physiological conditions were higher than those of the non-hybrid compound. Furthermore, keratin/hydrotalcite were able to support fibroblast cells adhesion and growth suggesting their potential use as drug delivery systems for wound healing and tissue engineering applications
Developing keratin sponges with tunable morphologies and controlled antioxidant properties induced by doping with polydopamine (PDA) nanoparticles
Get PDFhis work investigates the preparation of wool keratin sponges by freeze-drying procedure starting form keratin aqueous solutions. The study highlights the correlations between process parameters (protein concentration and freezing rate) and the chemical-physical properties of the final sponges.
In particular, as the keratin concentration increases from 1 to 20% wt, the mean pore size and the porosity decrease from 62 to 37 mu m and from 94 to 50% respectively, while the chemical stability in physiological conditions increases, as well as the thermal stability and the elastic modulus. On the other hand, the increase of the freezing rate affects the design of sponges that appear as stacked leaflets structures with oriented pores.
Moreover, in order to confer to keratin sponges antioxidant properties, polydopamine (PDA) nanoparticles were used as fillers. To this end, PDA nanoparticles of about 130 nm were successfully dispersed in the sponges, bestowing time-dependent anti-oxidant properties on the scaffolds, with no significant modification of sponges morphological structure as well as reduction of the thermal stability and mechanical behaviour
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
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