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Cs-Pb-Br Core-shell Perovskite Microcrystals for Stability Improvement
No full textLead halide perovskite nanocrystals (LHP NCs) have been developed since 2014. Due to their intrinsic ionic salts and lead-halogen composition, they have high molar absorbance coefficient, high defect tolerance, and ultra-fast carrier mobility, and their material structure and optical properties can be precisely controlled through ion exchange, which have aroused great research interest of scientific researchers as well as new thinking on the ion salt nanocrystal. Among LHP NCs family, CsPbBr3 NCs are quite outstanding as they exhibit better luminescence properties, etc. They also demonstrate promising application prospects in the fields of optoelectronic devices, photovoltaics, and photocatalysis, occupying a central position in the current research of LHP NCs. However, their lack of stability to external elements, including light, humidity, and heat limits their use in practical applications. Heterostructure development is one of several approaches to overcome these limits. Combining two or more materials at the nanoscale results in new heteronanocrystals that outperform the pure material. To improve the stability of LHP NCs against environmental stress, core-shell NCs can be created by growing a shell on the surface of core NCs, drawing inspiration from chalcogenide semiconductor NCs. In this sense, there are multiple organic materials (e.g., phenylpropylammonium bromide and polymethyl methacrylate) and inorganic materials (such as NaBr, TiO2, and metal chalcogenides, as well as perovskites, e.g., Cs4PbBr6, CsPb2Br5, and Rb4PbBr6) used for covering a perovskite core.
In this paper, the most promising approach involves coating perovskite NCs (PeNCs) with a crystalline perovskite shell by in situ synthesis, resulting in high-density NCs with a perovskite/perovskite core-shell configuration. This efficiently corrects the lattice mismatch between the core and shell. Because of its indirect band gap, photoluminescence (PL) intensity, water resistance, and minimum lattice mismatch with CsPbBr3 NCs, 0D Cs4PbBr6 and 2D CsPb2Br5 perovskite materials are thought to be promising coating materials. The changes in luminescence properties and stability were studied and the application of the composite material in the field of anti-counterfeiting was studied. This paper describes the synthesis and characterisation of two core-shell structures based on CsPbBr3 NCs, with a particular focus on enhancing their stability and physical properties. The research successfully achieved the in situ formation of a protective shell on the surface of CsPbBr3 NCs using a simple room-temperature synthesis method, thereby overcoming lattice mismatch issues arising from stepwise synthesis. Research into this system not only aids in understanding interfacial chemistry but also provides strategies for the low-cost synthesis of stable luminescent materials. This resolves the issue of the extremely complex fabrication process for core-shell structures, which is prone to generating interface defects and incomplete passivation, thereby leading to variations in their optical properties. Notably, in-situ spectroscopic and structural techniques were employed to investigate the exceptional performance of the synthesised core-shell structures under high-temperature and water immersion challenges. This demonstrates the critical role of the core-shell architecture in CsPbBr3 NCs, effectively passivating the crystals while substantially enhancing environmental stability
La portata generale dell’art. 107 TFUE e il rapporto con le norme sulla libera circolazione delle merci
No full textThe land use-climate change-biodiversity nexus in the perceptions of European islands stakeholders
No full textTo promote climate adaptation and mitigation strategies, it is crucial to understand the perspectives and knowledge gaps of stakeholders involved in functions affected by or addressing land use and climate changes. A large number of stakeholders across 21 European islands were consulted regarding their views on climate change and land use change issues affecting ecosystem services on their island. Climate change characteristics perceptions included variables such as temperature, precipitation, humidity, extremes, and wind. Land use change characteristics perceptions included deforestation, coastal degradation, habitat protection, renewable energy facilities, wetlands and other variables. Other environmental and societal problem perceptions such as invasive species, water or energy scarcity, problems in infrastructures or austerity were also included. Climate and land use change impact perceptions were analysed with machine learning to quantify their importance on the perception outcome. For example if a stakeholder perceives that pollution, coastal degradation, deforestation, precipitation decrease, and increase of humidity are occurring on the island, and austerity is the biggest problem how likely is that the impact of climate change or land use change will be quantified by the stakeholder as negative, unclear, neutral, or positive? The predominant climatic change characteristic is related with temperature, and the predominant land use change characteristic with deforestation. Water-related problems are top priorities for stakeholders. Energy-related problems, such as energy deficiency but also wind and solar energy facilities problems, rank high as combined climate change and land use change risks. Stakeholders generally perceive climate change impacts on ecosystem services as negative, with natural habitat destruction and biodiversity loss identified as the top variables. Land use change impacts are also negative but also more complex to explain, with a higher number of explanatory variables associated with the impact outcome. Stakeholders have common perceptions regarding climate change and land use change impacts on the benefits of biodiversity despite the geographic disparity. Stakeholders differentiate between factors related to climate change impacts and land use change impacts. Water, energy, and renewable energy related issues pose serious concerns to island stakeholders and management measures are needed to address them
Empty Spaces, What Are We Living For? Conservazione e valorizzazione del patrimonio industriale perduto = Empty Spaces, What Are We Living For? Conservation and Enhancement of Lost Industrial Heritage
No full textThe title, echoing the opening line of Queen’s “The Show Must Go On”, evokes a sense of disorientation and questions the persistence of the void left by what no longer exists. This image describes the condition of disused industrial architectures: once central to the productive and social identity of communities, today silent witnesses of a declining past, often reduced to mutilated fragments, erased by new developments, or turned into urban voids. Industrial heritage, frequently considered obsolete or marginal, instead represents a crucial component. Its preservation concerns not only the tangible
fabric but also the intangible legacy of relationships, knowledge, and memories that shape collective identity. This paper reflects on the reasons behind the enduring undervaluation of industrial heritage, an attitude that has too often led to incongruous transformations or even complete demolitions. The analysis investigates the residual capacities of spaces emptied of function and identity, or of surviving architectures profoundly altered. The hypothesis is that such capacities may serve as levers to reactivate meanings and to guide processes of enhancement, conservation, and reuse in ways that remain faithful to historical memory
Definizione di una metodologia integrata per la stima delle emissioni di PM da superfici di materiali granulari esposte all’erosione eolica
No full textWind erosion is a key mechanism responsible for the emission of particulate matter (PM) from granular surfaces (industrial wind erosion). In industrial environments such as mining and metallurgical plants, granular materials, typically stored in open yards, can act as fugitive dust sources and affect air quality in surrounding environments. This work develops an integrated methodology that combines experimental measurements and numerical modelling to estimate PM emissions from erodible surfaces exposed to wind action under site-specific conditions. The methodology integrates the physical–chemical characterization of the materials, the experimental determination of the threshold friction velocity, and the CFD-based modelling of the wind field over the exposed surfaces. At its core is a physical–mathematical model implemented in MATLAB, which simulates the saltation, impact, and release of fine particles generated by the saltation process, using as input data the results of experimental analyses preliminary performed on the materials under investigation. The PM10 emissions estimated through numerical simulations showed qualitative agreement with the results of the emission tests carried out in the Environmental Wind Tunnel (DICAAR EWT). The developed methodology represents a significant step toward the development of predictive tools for the management and mitigation of dust emissions, offering a flexible and scientifically robust basis for environmental impact studies
Disordered descent into sleep: microstructural divergence across arousal-linked conditions
No full textSleep onset is an unstable transition whose microstructure may distinguish clinical phenotypes. Using Hori 4-second microstaging in patients with narcolepsy type 1, idiopathic REM sleep behaviour disorder, NREM parasomnia and an exploratory fibromyalgia cohort, each with matched controls (n = 48 pairs), we quantified timing, entropy, hemispheric laterality and sequence ordering. Narcolepsy showed compressed, irregular onset, fibromyalgia prolonged divergent onset, and the remaining groups near-normative trajectories, suggesting disorder-specific signatures of arousal instability
Experimental Investigation of the Influence of a Sloped Bottom on the Behavior of Inclined Dense Jets
No full textInclined dense jets are widely used in outfall systems, yet their behavior over sloped bottoms remains insufficiently understood. This study investigated the influence of sloped bottom on jet dynamics and mixing through 36 experiments using Laser Induced Fluorescence (LIF), with discharge angles of 30°, 45°, and 60°, bottom slopes of 0°, 1°, 3°, and 5°, and densimetric Froude numbers of 17.3, 22.1, and 28.1. The results show that jet trajectories are unaffected by the sloped bottom before the return point; however, after impingement, the impact-point location, local dilution, and lateral spreading all increase with increasing slope. Flow visualization showed a strong ring-shaped vortex at impingement, followed by Kelvin–Helmholtz vortices, which became more pronounced on sloped bottoms. The energy spectra along the bottom follow Kolmogorov’s − 5/3 law. The variance and energy spectra analyses consistently showed that shear-induced turbulence is significantly enhanced over the sloped bottom, leading to higher fluctuations and turbulence energy and thereby enhancing mixing. The length of mixing zone and spreading layer thickness also increased with slope angle. The dilution enhancement over the sloped bottom is more pronounced for jets with a higher ratio of the initial momentum flux to the buoyancy flux. These findings clarify slope–momentum–buoyancy and jet–bottom interactions, provide practical guidance for outfall design, and highlight the importance of accounting for seabed slope and bottom conditions to optimize mixing efficiency
Eco-geomorphological and hydrodynamic analysis of Mediterranean microtidal beaches in Southern Sardinia
No full textGlobal climate change is increasingly having an impact on the marine and coastal environment, with rising sea levels and a growing frequency and intensity of extreme weather and marine events. These phenomena threaten the stability of coastal systems, accelerating beach erosion, damaging infrastructure and exposing ecosystems and economic activities to significant risks. In this context, integrated coastal management strategies become essential, as they play a key role in predicting, mitigating and adapting to potential impacts on coastal areas. Therefore, ensuring the long-term resilience of coastal systems requires strategic planning grounded in robust scientific knowledge. This thesis carries out a multidisciplinary study on the geomorphological, morphometric, hydrodynamic and ecological aspects of the microtidal beaches of Southern Sardinia, Italy (Western Mediterranean Sea). Given the geomorphological variability along this coastal stretch, as well as the differing wave conditions and exposures, an initial morphometric analysis and classification was carried out on 79 microtidal beaches (natural or influenced by the presence of artificial structures), providing an estimation of their level of embaymentisation and the prevailing hydrodynamic circulation in the surf zone. In addition, the spatio-temporal variation of the shorelines was investigated to estimate the accretion and retreat rates for each identified beach. The results highlighted that, over approximately 70 years, changes in shoreline position reflect dynamics associated with the levels of naturalness or human modification of the beach. In fact, some beaches exhibited more pronounced shoreline evolution trends, probably due in part to possible human influence (e.g., construction of artificial structures, damage to the Posidonia oceanica meadow, and others). From a hydrodynamic perspective, a further contribution of this thesis was the numerical modelling of currents circulation within the surf zone of embayed beaches (a common beach type along the studied coastlines). Numerical modelling highlighted that wind forcing on the sea surface plays a crucial role in the formation and location of rip currents, as well as in determining their intensity and their longshore and cross-shore extent. Finally, considering the widespread presence of Posidonia oceanica meadow along the entire coastline, the role of beach-cast in coastal flooding events was investigated. For this purpose, a coastal video monitoring system, located on a microtidal urban beach (Poetto), and numerical modelling were used to analyse two storm events and their effects on morphodynamic processes, such as the interaction between wave motion and beach-cast (mainly composed of Posidonia oceanica and Arundo donax remains)
Innovative energy systems and processes based on hydrogen from RES and its derivatives in the energy transition process
No full textThis thesis investigates the integration of green hydrogen and ammonia production in renewable energy-powered energy systems, as a decarbonization pathway in the energy sector. Climate change mitigation and the transition to carbon-free energy systems are challenged by the inherent intermittency of renewable sources, which affects grid stability and can lead to energy curtailment. By converting surplus renewable electricity into chemical energy carriers such as hydrogen and ammonia, it is possible to enhance system flexibility, support grid services, and provide carbon-free fuels for hard-to-abate sectors and power generation.
In this research, mathematical modeling is used to develop, optimize and analyze integrated energy systems based on variable renewable energy generation, water electrolysis, energy storage and ammonia production. Two main approaches to system integration are examined: the first combines green hydrogen production with mechanical energy storage (via compressed air energy storage or pumped hydro energy storage) to provide grid balancing and minimize curtailment, while the second analyzes a fully dedicated green ammonia production plant. The performance of each configuration is assessed to identify the optimal system design and operational strategies.
With reference to green hydrogen and mechanical storage integrated solutions, two different configurations are analyzed in detail. In the first configuration, a photovoltaic plant is integrated with a compressed air energy storage system fueled by green hydrogen produced on-site. This approach achieves a round-trip efficiency of approximately 62%, a reduction of photovoltaic curtailment to 4%, while delivering grid flexibility services using carbon-free fuel. On the other hand, the second system integrates hydrogen production in a floating photovoltaic-powered pumped hydro energy storage plant, using surplus energy to maximize self-consumption utilizing 99.2% of renewable energy generation.
Finally, a green ammonia production system is optimized using a mixed integer linear programming approach, allowing for the simultaneous optimization of component size and operation scheduling to minimize production costs. The analysis achieves temporal decoupling of yearly ammonia production from fluctuating photovoltaic input with minimal intermediate storage, with a system efficiency of 45.5% and a levelized cost of ammonia of 995 €/ton