1,720,967 research outputs found
Influence of light-curing parameters on biofilm development and flexural strength of a silorane-based composite
No full textObjectives: The aim of this study was to evaluate the differences in biological and mechanical performances of a silorane-based and a methacrylate-based composite. Another aim was to assess the influence of light-curing time and light-curing intensity on in vitro biofilm formation and flexural strength of the two
tested composites. Methods: Experiment 1: 432 specimens obtained from a silorane-based composite and from a standard methacrylate-based composite were divided into six groups and light-cured for 10, 20, 30, 40, 60, or 80 seconds, using one of two light-curing intensities, 400 mW/cm2 or 800 mW/cm2. At 24 hours, a monospecific Streptococcus mutans biofilm adherent to the surfaces of the samples was obtained. Then, a colorimetric technique (MTT assay) was used to evaluate the adherent viable biomass. Two samples per group were observed using confocal laser scanning microscopy. Analysis of variance ANOVA) and Tukey tests were used to analyze the results (p,0.05). Experiment 2: 192 bar-shaped specimens were obtained and light-cured as in the previous experiment. A three-point bend test using a universal testing machine was performed to obtain flexural strength values. ANOVA and Tukey tests were used to analyze the results (p,0.05). Results: In experiment 1, a highly significant difference (p,0.0001) in biofilm development was shown between silorane-based and methacrylate-based composites. In fact, the silorane-based composite exhibited better biological performance. Significant differences were also found between the two light-curing intensities (p,0.018) and for curing times (p,0.0001): silorane-based composite light-cured for 80 seconds at 800 mW/cm2 light-curing intensity showed the lowest biofilm development. In experiment 2, a significant difference in flexural strength (p,0.0318) was only found between
the different composites. Nevertheless, both resin composites showed flexural strength values in accordance with International Organization for Standardization guidelines even after 10 seconds of light-curing time. Conclusions: Silorane-based composite was less prone to biofilm development compared with a methacrylate-based composite. Acceptable flexural strength values for both composites were obtained after 10 seconds of lightcuring time
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
Surface properties of resin-based composite materials and biofilm formation : a review of the current literature
No full textPurpose: To evaluate the state of art on the relations between surface properties (surface roughness, topography, surface free energy and chemistry) of resin-based composite materials and microbial adhesion and biofilm formation.
Methods: An electronic search using Scopus and PubMed (until May 2015) was conducted applying the following search items: “Plaque OR Biofilm AND Surface chemistry”,” Plaque OR Biofilm AND Surface-free energy”,” Plaque OR Biofilm AND roughness”, ”Surface characteristics AND Composites”, ”Biofilm AND Surface characteristics”.
Results: Surface properties of resin-based composite materials as well as surface treatments can strongly affect bacterial adhesion and biofilm formation, although the “ideal” surface features have not been identified yet. Moreover, investigations highlighted that cariogenic biofilm formation may alter materials surface properties thus encouraging bacterial adhesion and biofilm formation, starting a “vicious cycle” which might compromise restoration longevity.
Clinical significance: The comprehension of the complex interactions between oral microorganisms and resin-based composite materials could be of great importance to guide the development of new materials able to modulate microbial adhesion and biofilm formation
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
Nuovi materiali odontoiatrici da restauro a effetto antimicrobico = New dental restorative materials featuring antimicrobial activity
No full textObiettivi. Il presente lavoro si propone di fornire una panoramica sugli approcci al problema dell’interazione tra i nuovi materiali utilizzati in odontoiatria restaurativa e il biofilm microbico orale. Materiali e metodi. Un inquadramento del problema della carie secondaria, dei biofilm orali, delle loro interazioni con i materiali da restauro viene proposto grazie a una revisione della letteratura. Risultati. Lo sviluppo di materiali bioattivi può prevedere la presenza di inibizione da contatto dei batteri orali, oppure il rilascio di agenti antimicrobici. Altri approcci prevedono l’ottimizzazione delle superfici di materiali già esistenti per migliorare le loro proprietà microbiologiche. Un ulteriore approccio, infine, prevede la sintesi di materiali biomimetici, ovvero di materiali che dal punto di vista meccanico, biologico e microbiologico si comportano in maniera simile ai tessuti dentali che sostituiscono. Conclusioni. Ciascuno degli approcci sopracitati presenta vantaggi e svantaggi e a oggi non esiste un materiale che soddisfi appieno le richieste cliniche. Le generazioni di materiali a venire saranno caratterizzate dalla presenza di bioattività, cioè dalla capacità del materiale di interfacciarsi in maniera positiva sia con i tessuti dell’ospite sia con il biofilm che lo colonizza.Objectives. This dossier aims to provide a modern overview on how to approach the interactions between new restorative materials and oral biofilms. Materials and methods. A literature review on secondary caries, oral biofilms and their interactions with restorative materials is shortly presented. Results. The development of bioactive materials can involve contact-inhibition of oral bacteria, or the release of antimicrobial agents. Other approaches focus on surface optimization of already existing materials to enhance their microbiological behaviour. An additional approach deals with the synthesis of biomimetic materials, namely materials behaving similarly to dental tissues, as they are able to replace them from a mechanical, biological and microbiological point of view. Conclusions. Each approach has pros and cons, and to date no material has proven to fully meet all clinical demands. New generations of materials yet to come will presumably be characterized by the presence of bioactivity, that is the ability of a material to actively and positively interact both with the host tissues and with the colonizing biofilm
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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