1,720,975 research outputs found
Preparazione di nanocompositi polimerici a base di grafene tramite esfoliazione di grafite nanostrutturata in soluzione di metilmetacrilato/polimetilmetacrilato
No full textIn questo lavoro è riportato l’utilizzo di una soluzione di metilmetacrilato/polimetilmetacrilato come mezzo esfoliante per la grafite nanostrutturata. Tecniche di spettroscopia ottica combinata con microscopia a trasmissione elettronica sono state utilizzate per dimostrare l’esfoliazione della grafite e la dispersione omogenea di grafene nella matrice polimerica. La concomitante esfoliazione e dispersione dei fogli di grafite ha consentito di realizzare nanocompositi polimerici conduttori e trasparenti allo stesso tempo
LIGHT INDUCED CHANGE IN CONDUCTIVITY OF GRAPHENE OXIDEFILMS PATTERNED BY METAL MASKS
No full textMicron-scale ordered gold patterns were deposited through a metallic copper grid positioned onto graphene oxide (GO) film. The
exposure to a xenon light source results in the formation of conductive GO/metal interface with photocurrent generation. It is
suggested that such simple method might serve as an efficient path for the formation of multifunctional patterned metal-carbon
interconnects
Flexible triboelectric generator and pressure sensor based on poly[(R)-3-hydroxybutyric acid] biopolymer
No full textThe utilization of poly[(R)-3-hydroxybutyric acid] (PHB) biopolymer for a device that uses charging process in friction to convert mechanical energy into electric power is reported. The triboelectric generator (TEG) is fabricated by stacking a drop cast PHB film between indium tin oxide coated poly(ethylene terephthalate) (PET) and PET sheet. The charge transfer takes place through an established general rule according to which the material with higher dielectric constant becomes positively charged. Furthermore, the utilization of such TEG as pressure sensor is illustrated. TEGs have the potential of harvesting energy from touch screen, mechanical vibration, and more, with great applications in self-powered sensors for heat and environmental monitoring and even large-scale applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 859-863 Electronic products that have become non-working or obsolete, and have essentially reached the end of their useful life are now a serious problem for the environment. In this article, we report the proof of the concept that a biopolymer can be used as an active component of a triboelectric generator. The involvement of a biodegradable polymer may probably bring new applications in biodegradable/biocompatible electronics. Copyright © 2014 Wiley Periodicals, Inc.Peer Reviewe
Anisotropic Electrical Transport Properties of Graphene Nanoplatelets/Pyrene Composites by Electric-Field-Assisted Thermal Annealing
No full textDispersion of graphene nanoplatelets (GNPs) with a pyrene derivative compound (1,3,6,8-tetrakis(4-t-butylphenyl)pyrene (TBPP)) in tetrahydrofuran as solvent medium is investigated. Field emission electron microscopy and atomic force microscopy demonstrated the π-π stacking interaction between the TBPP compound and the GNPs resulting in the deposition of the TBPP compound onto the exfoliated graphene sheets. We found that the electrical conductivity of the films obtained by the prepared dispersions can be activated in temperature and oriented by the application of an external electric field. We found an increase of the composite conductivity measured along the substrate with respect to the composite conductivity measured perpendicular to the substrate. This result provides an initial understanding of how electric fields can be used to control the bulk physical properties of such composites
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
Glass beads retro-reflective coating for building application: albedo assessment in urban canyon configurations
No full textMaterials for urban pavements and building coatings have a direct impact on urban thermal environment: low-reflective and highly absorptive materials, in fact, could contribute
to the exacerbation of the Urban Heat Island (UHI) phenomenon, which negatively affects building energy consumptions and indoor and outdoor thermal comfort. These effects could be
worsened especially in Urban Heat Canyon configurations, where the inter-building effect becomes more relevant. As regards UHI mitigation strategies, high-reflective (HR) and retroreflective
(RR) materials have been studied for their application as urban coatings, in order to provide a cooling effect inside urban canyons. In this framework, this study aims at comparing the albedo performance of HR and RR materials applied on a small scale urban canyon facility. To this aim, an in-field experimental campaign was conducted in two days during summer 2020. Different canyon coating combinations and height/width (H/W) ratios were investigated and compared in terms of albedo. Results show that an albedo worsening occurs when the RR coating was applied to the canyon’s surfaces, because of the lower global reflectance of the RR with respect to the HR. Nevertheless, the application of RR coating on walls, coupled with HR paint on pavement, lead to higher albedo values of up to 4.7%, with respect to the opposite mixed coating combination. Future developments may concern the investigation of the optimum design of a glass bead RR material for building application, by studying the correlation between its optical capabilities and the dimensions and density of the glass beads
Outdoor thermal comfort improvements due to innovative solar awning solutions: An experimental campaign
No full textUrban areas are increasingly affected by the Urban Heat Island (UHI) phenomenon, which is mainly due to highly dense urban environments and to solar and radiative properties of outdoor surfaces. UHI has a strong impact on urban microclimate, significantly contributing to the deterioration of outdoor human thermal comfort. Solutions based on high reflective materials in outdoor applications, e.g. solar awnings, could represent an important issue for mitigating UHI and improving pedestrians’ thermal comfort. For this purpose, the present research aims to investigate the effect of different radiative properties of solar awning textiles on microclimate and outdoor thermal comfort below them. High reflective materials are usually used for awning textile, but they are often characterized by high emissivity properties downward that may affect the pedestrians’ thermal comfort. The proposed solution consists in an awning textile with highly-reflective, highly-emissive properties upward and highly-reflective but low-emissive properties downward. Different solar awning configurations were tested by a microclimate experimental campaign on summer 2019. Outdoor thermal comfort under each awning was assessed by evaluating Physiological Equivalent Temperature (PET). Results show that a daily average PET reduction up to 2.5 °C is achieved thanks to the proposed solutions, proving benefits to pedestrians’ thermal comfort
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