1,721,000 research outputs found
Enhancing the performance and mechanical stability of 2D-based hybrid micro-supercapacitors using dendritic-gold as framework layer
Full text linkIn recent years scaling-down approaches on supercapacitors has led to the definition of Micro-Supercapacitors (μSC). The demand for these devices is increasing for many applications in microelectronics, such as wearable energy storage and self-powered sensors. Recently, many efforts have been made to achieve good results in terms of power and energy densities. However, the current research challenge is to develop a sustainable chain production, involving eco-friendly materials, such as water-based electrolytes, organic binders and low-impact active material. This work presents a hybrid μSC using low impact materials and a fully water-based solution. Different approaches were adopted for patterning the current collectors and for the deposition of the active materials. The material chosen as anode was MnO2 deposited by electroplating, which presents pseudocapacitive behavior. The active material used for the cathode was Activated Carbon (AC), deposited by drop-casting, which works through the electric double layer (EDL) capacitance effect. The electrolyte was 1 M Na2SO4 in water. We investigated the addition of an interlayer micro-structure made of Dendritic-Gold (D-Gold). The results show that such a layer seems to have positive effects in terms of wettability and mechanical stability, enhancing the adhesion of the active material. Electron microscopy measurement shows the characteristic tree-like shape of the layer. The device reports a capacitance of about 14 to 23 mF cm-2 and a large voltage window equal to 1.6 V. The present research explores, for the first time, the effects of dendritic gold in planar electrochemical capacitors. The findings should give an important contribution for boost energy storage densities in the field of 2D micro-supercapacitors
Direct Online Environment Monitoring of Water Pollution
Full text linkWater pollution is one of the most serious ecological threats we face today. Each water body is affected by some organic, inorganic or adioactive pollutant, coming from direct or indirect sources. Surface water and ground water must currently be monitored in all countries on a very large scale by public authorities, but also private companies, to enforce pollution reduction and environmental law compliance. Most of the controls are
performed by manually sampling the waters and by sending the samples to an authorized laboratory for the analysis, with high costs, long response times, low sampling frequency and consequent low monitoring data resolution.
The research aims to develop methods and to design a device able to perform the sampling, preparation and detecting automatically. The proposed system in fact can be easily installed on site and, once configured and positioned, smart sensors can send analytical data direct ly to the customer with no human intervention. It involves no costs for sampling activities, response times reduced to few minutes and the possibility to achieve
high sampling frequency and a consequent strict monitoring of the evolution of the site status. Moreover, the device will be able to collect and share data, according to IoT technology
Miniaturization and Optimization of the Standard Spectrophotometric Analysis for Autonomous, Continuous and On-site Heavy Metal Detection in Water
Full text linkWater environmental monitoring is an important key to control both human life and environment health. When water quality is poor, it affects not only aquatic life but the surrounding ecosystem as well. The greatest limitation of detection devices, today on the market, is that they are limited to the measurement phase, burdening the operator of the previous sample treatment.
The development of a threshold monitoring device, designed for real time water environmental monitoring, was the aim of this study. The focus was on the design of an autonomous system for detection of dissolved heavy metals in water by spectrophotometric analysis. The ground-breaking idea is the implementation of a system inspired to the latest innovative techniques in the field of the microfluidic analysis, based on Lab-on-Chip concept. Such a choice is due to the unique advantages in terms of reduction of sample and reagents volumes, energy budget and analysis times, besides the possible multi-element analysis on the same sample
Effect of electrode materials on resistive switching behaviour of NbOx-based memristive devices
Full text linkMemristive devices that rely on redox-based resistive switching mechanism have attracted great attention for the development of next-generation memory and computing architectures. However, a detailed understanding of the relationship between involved materials, interfaces, and device functionalities still represents a challenge. In this work, we analyse the effect of electrode metals on resistive switching functionalities of NbOx-based memristive cells. For this purpose, the effect of Au, Pt, Ir, TiN, and Nb top electrodes was investigated in devices based on amorphous NbOx grown by anodic oxidation on a Nb substrate exploited also as counter electrode. It is shown that the choice of the metal electrode regulates electronic transport properties of metal–insulator interfaces, strongly influences the electroforming process, and the following resistive switching characteristics. Results show that the electronic blocking character of Schottky interfaces provided by Au and Pt metal electrodes results in better resistive switching performances. It is shown that Pt represents the best choice for the realization of memristive cells when the NbOx thickness is reduced, making possible the realization of memristive cells characterised by low variability in operating voltages, resistance states and with low device-to-device variability. These results can provide new insights towards a rational design of redox-based memristive cells
Evaluating Bicarbonate Electrolyzer Configurations for Energy‐Efficient Formate Production
Full text linkReactive carbon capture (RCC) by direct conversion of CO2 capture solutions has emerged as a promising alternative to gas-fed electrolyzers. Leveraging bicarbonate electrolyzers (BEs), RCC eliminates energy-intensive steps such as CO2 regeneration and pressurization. Additionally, BEs prevent failures like carbonate salt deposition common in gas-fed systems. However, intrinsic challenges in BEs, such as higher cell voltages and lower faradaic efficiencies (FEs), result in greater energy consumption during electrolysis compared to gas-fed electrolyzers. To evaluate whether an RCC chain (RCCC) is more energy-efficient for formate production than a gas-fed carbon chain (GFCC), the study optimizes the BE configuration and compares it to a valorization chain requiring a pure, pressurized CO2 stream for gas-fed electrolyzers. This study shows the most efficient BE setup employs a cation exchange membrane paired with a buffer layer, achieving a FE for formate of ≈75% at a current density of 100 mA cm−2 and a cell potential of 3.1 V. Using this optimized BE, the RCCC demonstrates an energetic advantage over GFCCs in scenarios without CO2 recycling. Even with 100% CO2 utilization enabled by recycling systems, RCCC remains competitive. With potential improvements in BE performance, RCCC emerges as a promising strategy for converting CO2 into formate efficiently
Electrostimulation of a 3D in vitro skin model to activate wound healing
Full text linkThe aim of the work is to propose a methodology for the stimulation of a 3D in vitro skin model to activate wound healing. The presented work is in the frame of the national research project, CronXCov, “Checking the CHRONIC to prevent COVID-19”, devoted to understand how physiologic and inflamed skin on chip 3D models evolve upon a range of physical (e.g., electrical, mechanical, optical) stimulations, over time. Thanks to the 3D modelling, using Next Generation Sequencing and the network medicine frame of analysis to process the data, we will systematically characterize the effects of the applied stimuli, offering new insight for the exploitation of wound healing
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
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