1,720,977 research outputs found
Ultrasensitive Piezoresistive and Piezocapacitive Cellulose-Based Ionic Hydrogels for Wearable Multifunctional Sensing
Full text linkTactile sensors, namely, flexible devices that sense physical stimuli, have received much attention in the last few decades due to their applicability in a wide range of fields like the world of wearables, soft robotics, prosthetics, and e-skin. Nevertheless, achieving a trade-off among stretchability, good sensitivity, easy manufacturability, and multisensing ability is still a challenge. Herein, an extremely flexible strain sensor composed of a cellulose-based hydrogel is presented. A natural biocompatible carboxymethylcellulose (CMC) hydrogel endowed with ionic conductivity by sodium chloride (NaCl) was used as the sensitive part. Both the sensible layer and electrodes were investigated with an innovative approach for wearable sensor applications based on electrochemical impedance spectroscopy to find the best device configuration. The sensor, exploitable both as a piezoresistor and as a piezocapacitor, presents high sensitivity to external stimuli, together with an extreme stretchability of up to 600%, showing the best strain and temperature sensitivity among the ionic conductive hydrogel-based devices presented in the literature. The very high strain sensitivity enables the hydrogel to be implemented in wearable strain sensors to monitor different human motions and physiological signals, representing a valid solution for the realization of transparent, easily manufacturable, and low-environmental-impact devices
Workflow for the Validation of Geomechanical Simulations through Seabed Monitoring for Offshore Underground Activities
Full text linkUnderground fluid storage is gaining increasing attention as a means to balance energy
production and consumption, ensure energy supply security, and contribute to greenhouse gas
reduction in the atmosphere by CO2 geological sequestration. However, underground fluid storage
generates pressure changes, which in turn induce stress variations and rock deformations. Numerical
geomechanical models are typically used to predict the response of a given storage to fluid injection
and withdrawal, but validation is required for such a model to be considered reliable. This paper
focuses on the technology and methodology that we developed to monitor seabed movements and
verify the predictions of the impact caused by offshore underground fluid storage. To this end, we put
together a measurement system, integrated into an Autonomous Underwater Vehicle, to periodically
monitor the seabed bathymetry. Measurements repeated during and after storage activities can be
compared with the outcome of numerical simulations and indirectly confirm the existence of safety
conditions. To simulate the storage system response to fluid storage, we applied the Virtual Element
Method. To illustrate and discuss our methodology, we present a possible application to a depleted
gas reservoir in the Adriatic Sea, Italy, where several underground geological formations could be
potentially converted into storage in the futur
Coupling dairy wastewaters for nutritional balancing and water recycling: sustainable heterologous 2-phenylethanol production by engineered cyanobacteria
Full text linkMicroalgae biotechnology is hampered by the high production costs and the massive usage of water during large-volume cultivations. These drawbacks can be softened by the production of high-value compounds and by adopting metabolic engineering strategies to improve their performances and productivity. Today, the most sustainable approach is the exploitation of industrial wastewaters for microalgae cultivation, which couples valuable biomass production with water resource recovery. Among the food processing sectors, the dairy industry generates the largest volume of wastewaters through the manufacturing process. These effluents are typically rich in dissolved organic matter and nutrients, which make it a challenging and expensive waste stream for companies to manage. Nevertheless, these rich wastewaters represent an appealing resource for microalgal biotechnology. In this study, we propose a sustainable approach for high-value compound production from dairy wastewaters through cyanobacteria. This strategy is based on a metabolically engineered strain of the model cyanobacterium Synechococcus elongatus PCC 7942 (already published elsewhere) for 2-phenylethanol (2-PE). 2-PE is a high-value aromatic compound that is widely employed as a fragrance in the food and cosmetics industry thanks to its pleasant floral scent. First, we qualitatively assessed the impact of four dairy effluents on cyanobacterial growth to identify the most promising substrates. Both tank-washing water and the liquid effluent of exhausted sludge resulted as suitable nutrient sources. Thus, we created an ideal buffer system by combining the two wastewaters while simultaneously providing balanced nutrition and completely avoiding the need for fresh water. The combination of 75% liquid effluent of exhausted sludge and 25% tank-washing water with a fine-tuning ammonium supplementation yielded 180 mg L−1 of 2-PE and a biomass concentration of 0.6 gDW L-1 within 10 days. The mixture of 90% exhausted sludge and 10% washing water produced the highest yield of 2-PE (205 mg L−1) and biomass accumulation (0.7 gDW L−1), although in 16 days. Through these treatments, the phosphates were completely consumed, and nitrogen was removed in a range of 74%–77%. Overall, our approach significantly valorized water recycling and the exploitation of valuable wastewaters to circularly produce marketable compounds via microalgae biotechnology, laying a promising groundwork for subsequent implementation and scale-up
Self-standing polymer-functionalized reduced graphene oxide papers obtained via a UV-process
No full textGraphene based materials are attracting great attention every day due to their outstanding properties. Widening their potentialities through synergic effects in conjunction with other materials represents an intriguing challenge in order to obtain lighter and multi-functional composites. In this paper, novel self-standing graphene-based paper-like sheets are investigated, obtained via a facile dual step UV-induced process. This method, employing graphene oxide as a starting material, allows the obtaining of polymeric functionalized reduced graphene oxide papers that could be easily handled, featuring improved mechanical and peculiar electrical properties. The mechanical and thermal properties were investigated as well as their electrical response under different stimuli, such as temperature and humidity, showing remarkable changes
Oxygen-inhibition lithography for the fabrication of multipolymeric structures and multifunctional devices
No full textX-ray reflectivity spectra of ultrathin films and nanometric multilayers: Experiment and simulation
No full textDevelopment of 3D printable formulations containing CNT with enhanced electrical properties
No full textThis study demonstrates the feasibility of printing 3D composite objects based on acrylic photocurable formulations containing CNTs, by using an unmodified commercial DLP-printer. In the preliminary investigations, the most suitable formulation was developed. Viscosity and dispersion stability were adjusted by the addition of a reactive diluent to the acrylic formulation. FT-IR analyses in real time and photorheology tests allowed finding the best composition and printing parameters. Printing conditions were adjusted to get 3D structures from formulations with a content up to 0.3 wt % of CNTs. The presence of the filler causes a decrease of the crosslinking density, which could be overcome using higher intensity light sources. Electrical conductivity measurements performed on the printed samples give promising results for the use of the developed formulation for the building of 3D structures with electrical properties
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
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