1,721,013 research outputs found
Decarbonizzazione dell'economia italiana. Il catalogo delle tecnologie energetiche
No full textL’obiettivo di un Catalogo “open source”, contenente dati di tipo “qualitativo” e “quantitativo” sulle tecnologie energetiche e la loro applicazione nel settore industriale, dei trasporti e nel civile, è quello di fornire al decisore una dettagliata disamina tecnica ed economica delle tecnologie energetiche disponibili, sia di offerta sia di uso finale. Il testo raccoglie informazioni sulle eccellenze italiane, sia pubbliche che private, e sulle migliori pratiche relative alle più importanti tecnologie per la decarbonizzazione. Il lavoro assume un ruolo centrale in vista della elaborazione del prossimo “Piano nazionale Integrato per l’Energia e il Clima”, previsto dall’Unione per l’Energia, nell’ambito del quale dovrà essere fornito anche un quadro conoscitivo di riferimento a livello nazionale sui temi della “Ricerca e dell’innovazione”
Highly transparent Bi4Ti3O12 thin-film electrodes for ferroelectric-enhanced photoelectrochemical processes
No full textIn a photo-electrochemical (PEC) cell, rapid spatial separation of the photo-generated carriers and their transport kinetics within the photo-electrode materials are fundamental to achieving high-performance devices and avoiding charge recombination. Recently the use of ferroelectric potential in ferroelectric photo-active semiconductors has shown to be an effective strategy to modulate the charge transfer properties both in the bulk phase and at the surface of semiconductors. In this perspective, the Aurivillius perovskite Bi4Ti3O12 (BiTO) is of great interest owing to its excellent photocatalytic activity and strong spontaneous ferroelectric polarization. The use of BiTO powder for the photocatalytic reduction of CO2 has recently been reported, but its utilization as a photo-electrode for the photo-electrochemical (PEC) reduction of carbon dioxide has never been exploited, especially assisted by a ferroelectric potential. In this work, highly transparent BiTO-based thin film photo-cathodes were fabricated via a sol-gel/spin coating coupled process and optimized, for the first time in the literature, for CO2 PEC reduction. The influence of the number of depositions on the photo-electrochemical properties was initially accurately investigated and an optimized photo-electrode was thus obtained, which registered a maximum current density of -4.1 mA cm(2) under illumination conditions. In addition, the effect of the ferroelectric potential on the photo-electrochemical performances was accurately studied in this optimized system producing a current density increment of about 50% and an enhanced charge transfer ability, thus demonstrating the possibility of effectively adopting ferroelectric polarization in BiTO photo-electrodes to boost the photo-electrochemical reduction of CO2
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
Study of reversible SOFC/SOEC based on a mixed anionic-protonic conductor
No full textThis paper deals with the fabrication and electrochemical study of a high temperature solid electrolyte supporting cell operating as SOFC (Solid Oxide Fuel Cell) and SOEC (Solid Oxide Electrolysis Cell). The cell is based on a dual membrane (DM) electrolyte design, advantageously separating the cell into three different chambers: hydrogen side, oxygen side, and dual membrane (DM), where H2O production or splitting takes place in SOFC or SOEC mode respectively. The supporting electrolyte consists of a dense/porous/dense tri-layer, exclusively made of BaCe0.85Y0.15O3−δ (monolithic design), which is a mixed anionic-protonic conductor. The assembly was fabricated by tape casting, adding pore formers to control porosity. The cell was then electrochemically studied under different operating conditions of temperature, overpotentials and gas feeding, either in SOFC and SOEC mode. From the results presented here, it can be observed that, in spite of dense and thick electrolyte layers and platinum electrodes, the electrochemical study of the cell showed: (i) promising power density, (ii) interesting SOFC/SOEC operating mode reversibility, (iii) proved H2O production in the porous dual membrane when the cell operates as a fuel cell, and proved splitting of the H2O molecules contained in the porous dual membrane when the cell operates as an electrolyser. Investigations of cell performance degradation were also conducted
Bifunctional WO3 Photoelectrodes Decorated by Inkjet Printing for Solar Supercapacitors
Full text linkTungsten oxide-based photoelectrodes for solar supercapacitor applications are initially prepared by screen printing. After a complete functional characterization, the obtained results show the ability of these films to increase the number of stored charges when illuminated due to a diffusion mechanism and finally to produce an areal capacitance of 1.6 and 0.7 mF cm−2 under illumination or in the dark, respectively. Decorating the as-produced electrodes by inkjet printing allowed us to increase their exposed surface area, thus enhancing the areal capacitance up to 2.2 mF cm−2 while reducing charge-transfer resistances. Finally, gel-state symmetrical devices with agar-agar-based electrolyte are prepared and tested with different illumination intensities. At high illumination (1000 W m−2), an areal capacitance of 2.5 mF cm−2 is recorded, however, at low illumination conditions (500 W m−2), the highest value of 7.9 mF cm−2 is obtained (at 0.3 mA cm−2) due to reduced recombination phenomena between the photogenerated charges and the applied current density. This work demonstrates the potentiality of WO3 as a bifunctional material for solar rechargeable supercapacitors, paving the way for the development of new fully integrated devices for the energy sector
Porous apatites as novel high temperature sorbents for carbon dioxide
No full textSynthetic hydroxy-apatite was tested as a potential new material for CO2 capture at high temperature, over the operation limit of CaO-based sorbents. Some porous granules of hydroxy-apatite were prepared ad hoc. They were shown to absorb CO2 upon dehydroxylation in the very high temperature range of 900-1200°C, resulting in A-type carbonated apatite. No appreciable decay of the absorbing capacity was observed with a higher number of absorbing-desorbing cycles, differently from what happens in a conventional chemical sorbent, e.g. calcined natural calcium carbonate. The CO2 carrying capacity was maximum at 1000-1100°C and very close to the theoretical limit of 2.6% by mass. The macro-granule porosity network appeared to be effective in making the sites available for CO2 capture. At first glance, the process appeared to be chemically controlled. The pre-treatment temperature of the porous granules also had an impact on the sorption capacity. As a first proof of concept, the results obtained by thermogravimetric analysis, and supported by FTIR and XRD analysis, were confirmed by tests carried out in a laboratory-scale reactor, operated as a fixed bed
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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