1,721,020 research outputs found
Photocatalytic Activity of P-doped TiO2 Coatings Obtained at Room Temperature on Pre-treated Corona Polypropylene Films
No full textn this work, P-doped TiO2 (P-TiO2) photocatalyst was prepared by a modified sol-gel method at room temperature and then coated on corona discharge pre-treated polypropylene films (P-TiO2/PP). The obtained photoactive P-TiO2/PP was characterized with different techniques (XRD, SEM and SSA) and the photocatalytic effect under UV and visible light was analyzed in the degradation of methylene blue (MB), used as model organic pollutant. The photocatalytic tests were carried out in a batch photoreactor irradiated by a visible lamp (nominal power of 32 W and wavelength emission > 400 nm).
The experimental results showed that the coating of P-TiO2 onto PP films allowed to achieve a MB discoloration of 63% after about 240 min of visible light irradiation
Analysis of nascent silicon phase-change gratings induced by femtosecond laser irradiation in vacuum
No full textThe formation of periodic surface structures is a general effect of femtosecond laser irradiation of solid targets showing promising interest in material science and technology. However, the experiments are typically carried out in air, a condition in which the target surface becomes densely decorated with nanoparticles that can influence the formation of the surface structures in the early stage of the irradiation process. Here we report an investigation of structures generation on a silicon surface irradiated in vacuum (10-5 mbar) with a low number of laser pulses (N ≤ 10) that exploits several microscopy techniques (optical, atomic force, electron and Raman). Our analyses allow identifying the creation of silicon phase-change gratings consisting of alternating amorphous and crystalline periodic lines, with almost no material removal, located at the periphery of a shallow ablation crater. These gratings originate from two different kinds of defects: (i) the first is characterized by a peculiar lobed shape that is produced by the first few laser pulses; (ii) the second is provided by the one-dimensional, linear singularity defined by the ablation edge of the nascent crater. Both kind of defects lead to grating structures extending outwards the amorphous central area of the crater along the direction of the laser polarization. Comparative analysis with the surface formed in air, in the same experimental conditions, evidences the important role played by nanoparticles densely decorating the target in air and the striking variation occurring in vacuum
Hydrogen-evolving photoanode of TiO2 nanoparticles film deposited by a femtosecond laser
No full textTiO2 nanoparticles (NPs) were deposited on Ti foil by fs-PLD at room temperature under different chamber pressure from high vacuum (similar to 10(-6) mbar) to oxygen pressure (0.1 mbar, 1 mbar). The present work focuses on investigating the effects of deposition conditions on crystalline phase, morphology and photoelectrochemical properties of the resulting TiO2 NPs-assembled films electrode. The results show that the morphology of the sample obtained in 1 mbar shows the sparser nanoagglomerates than that of TiO2 NPs deposited under vacuum or in 0.1 mbar. Moreover, TiO2 NPs films with pure rutile phase and the thickness of less than 400 nm exhibited the higher photocurrent densities and the greater charge carrier densities. Combined with the analysis of the photovoltage, it can be deduced that the optimal deposition condition for better PEC performance of TiO2 NPs films produced by fs-PLD is the higher chamber pressure (1 mbar) and longer deposition time (3 h
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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