1,720,979 research outputs found
Electrochemical Performance of Biopolymer-Based Hydrogel Electrolyte for Supercapacitors with Eco-Friendly Binders
No full textAn environmentally friendly hydrogel based on gelatin has been investigated as a gel polymer electrolyte in a symmetric carbon-based supercapacitor. To guarantee the complete sustainability of the devices, biomaterials from renewable resources (such as chitosan, casein and carboxymethyl cellulose) and activated carbon (from coconut shells) have been used as a binder and filler within the electrode, respectively. The electrochemical properties of the devices have been compared by using cyclic voltammetry, galvanostatic charge/discharge curves and impedance spectroscopy. Compared to the liquid electrolyte, the hydrogel supercapacitors show similar energy performance with an enhancement of stability up to 12,000 cycles (e.g., chitosan as a binder). The most performant device can deliver ca. 5.2 Wh/kg of energy at a high power density of 1256 W/kg. A correlation between the electrochemical performances and charge storage mechanisms (involving faradaic and non-faradaic processes) at the interface electrode/hydrogel has been discussed
Indium Tin Oxide–Based Fully Spray-Coated Inverted Solar Cells with Nontoxic Solvents: The Role of Buffer Layer Interface on Low-Bandgap Photoactive Layer Performance
No full textIn bulk heterojunction solar cells, the morphology of the interfaces between the photoactive layer (PAL) and charge transporting layers during the deposition process plays a key role in achieving high-efficiency devices. Herein, an inverted fully spray-coated solar cell fabricated on an indium tin oxide (ITO)-glass substrate is presented. It is demonstrated that a spray-coated double electron transporting layer composed of zinc oxide (ZnO) nanoparticles coated with polyethylenimine ethoxylated (PEIE) improves the morphology of the spray-coated active layer on top of the spray-coated cathode. Moreover, focusing on the hole transporting layer and anode, the performance obtained using a commercial poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) blend is compared with a high-conductive anhydrous PEDOT:PSS (A-PEDOT) mixed with a commercial PEDOT:PSS (CPP-105D) as transporting layer. By optimizing the spray deposition of all the layers, a fully scalable spray process is used to produce polymer solar cells with ITO/ZnO/PEIE/poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2- [(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl]] (PTB7): [6,6]-phenyl-C70-butyric-acid-methyl-ester (PC70BM)/CPP:A-PEDOT structure, achieving a power conversion efficiency (PCE) of 3.6%. Such result is significant if compared to a spray-coated structure with evaporated anode (MoO3-Ag). In this case (ITO/ZnO/PEIE/PTB7:PCBM/MoO3-Ag), a power conversion efficiency of 5.5% is obtained
Hybrid and organic photovoltaics for greenhouse applications
No full textReducing the energy demand and dependency on fossil fuels is crucial for improving the sustainability of greenhouses, which are the most energy intensive systems in the agricultural sector. Renewable technologies represent a key option to meet the greenhouse energy demands. Agrivoltaics has recently emerged as a strategy to combine farming activity and power generation through photovoltaics (PV). However, PV systems retrofitting needs to consider the interactions with the existing greenhouse structure, as well as the energy requirements of the equipment for climate control. The influences of PV shading on agronomic parameters have also to be carefully considered. Firstly, this review examines the response of plants to the light and the fundamental aspects of greenhouse facilities. Then, the state-of-the-art of PV systems applied to greenhouses is thoroughly analysed. Simulation studies and experimental works are examined to highlight the effects of PV technologies and module arrangements on energy production and plant growth. Particular attention is devoted to new PV technologies, i.e. organic, dye-sensitized and perovskite solar cells, because of their semi-transparency and flexibility, allowing the easy integration of PV modules into existing or newly conceived greenhouse structures.
The review has highlighted that the new PV technologies have an enormous potential due to the possibility of tuning their spectral features according to the characteristics of plants and to the capability of optimizing the use of solar energy into high-tech greenhouses. Shading through these innovative systems has also demonstrated to create a suitable atmosphere for crop growth especially in hot and tropical regions.
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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
Designing a Platform for Energy Recovery and Monitoring in Building Applications
No full textEnergy efficiency measures are pivotal in addressing the high energy consumption and gas emissions of the building sector. Moreover, increasing attention is given to indoor environmental quality to ensure comfort and healthy conditions for the occupants. Sustainable and energy-efficient solutions are needed to avoid the extensive use of battery-based wireless network sensors. In this work, a platform has been conceived and designed to recover unused indoor energy sources and convert them into useful power for environmental sensors to monitor buildings. A preliminary energy analysis of the main components of such a platform has been carried out to demonstrate the feasibility of the system
Fully-sprayed flexible polymer solar cells with a cellulose-graphene electrode
No full textOrganic photovoltaic (OPV) technology provides energy where conventional photovoltaics are difficult to implement. The rise of efficiency due to the introduction of new polymers and the definition of strategies for the scale-up push OPV devices towards large-scale manufacturing. Here, spray coating has been employed as an easy and versatile scalable technique to deposit all the layers of flexible polymer solar cells starting from PET/ITO/Ag/ITO substrates. A foldable nanocomposite based on cellulose and sprayed graphene nanoplatelets has been applied as top electrode through lamination. The overall fabrication process has been conducted in air by using commercial materials. A significant power conversion efficiency higher than 3% has been achieved and the high quality of the lamination process has been demonstrated by bending and adhesion tests. Such photovoltaic devices are the first fully-sprayed prototypes on plastic substrate and the novel structure has also been effective for devices with active area up to 0.75 cm 2
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