Archivio Istituzionale della Ricerca - Università degli Studi di Pavia
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Compositional and Defect Engineering of Metal Halide Perovskite‐Based Heterojunctions for Efficient Nitrogen Photofixation
No full textDesigning innovative photocatalysts for nitrogen photofixation is becoming crucial for the development of carbon-neutral ammonia production. Metal halide perovskites (MHPs) provide a rich library of materials with an easy tuning of the semiconductor bandgap in order to integrate them in devices with different functionalities. An under-explored path is their exploitation to run a wide range of photoredox reactions mediated by solar light. Herein, heterojunction is developed based on the vacancy-ordered double-perovskite Cs2SnBr6 and carbon nitride nanosheets and demonstrate its ability in running the nitrogen photofixation reaction to produce ammonia under solar light. An investigation is done on full Cs2SnBr6/g-C3N4 system and an optimal range providing an outstanding ammonia evolution rate up to 270 μmol g−1 h−1is identified, which is quantified by means of ion selective electrode. Mechanistic insight into the photofixation reaction is obtained through a combination of advanced spectroscopy and computational modeling. Efficient ammonia production stems from an effective charge transfer from the perovskite to the nitrogen vacancies on the carbon nitride enabled by the proposed absence of self-trapped excitons in Cs2SnBr6, which also provides additional reactive sites through bromide vacancies. This work paves the way to MHP-based catalyst design strategy for sustainable ammonia production
Present and Projected Suitability of Olive Trees in a Currently Marginal Territory in the Face of Climate Change: A Case Study from N-Italy
No full textExpected climate change will impact the environmental suitability of different territories. This will be of particular importance for crop sustainability in agriculture, especially in territories that are currently marginal in the biogeographic distribution of cultivated crops; in some cases, the growing conditions may become more suitable due to the projected modified climatic conditions. This paper aims to reconstruct different scenarios of environmental suitability of olive trees under current and future climatic scenarios, considering for the first time a marginal area for this tree plant in Europe. This study represents a first attempt to assess the possible evolution of the suitability of one of the most important Mediterranean crop trees in a current marginal area. This area corresponds to a territory (Oltrep & ograve; Pavese, South Lombardy) located at northern edge of the typical geographical distribution. The results of the suitability scenarios, obtained by applying a data-driven method based on predictors representative of the main geological, geomorphological, climatic, and plant cover variables influencing olive tree presence in a territory, show that the future projections at different periods (short-term at 2050; medium-term at 2070; long-term at 2100) suggest an increase in the suitable areas for olive tree cultivation. The increased suitability in this geographical area is related to an increase in air temperature and a parallel decrease in the number of frost days projected for the future scenarios, guaranteeing an increase in suitable areas for olive trees especially in those sectors located at higher latitudes and altitudes than the ones currently more suitable to olive trees. This study could represent a useful basis to implement effective and sustainable strategies of land planning and of mitigation measures to limit the impacts of the climate change effects on cultivation, making the developed method a potential operational tool for the evaluation of the territories that are and will be more adapted to this cultivation according to actual and future climatic scenarios
Development of a nasal spray based on cyclodextrin/hydrophobically-modified hydroxypropyl-methyl cellulose for the prevention of viral respiratory infections
No full textThe work aims to develop mucoadhesive and thermo-responsive in situ gelling systems, using hydrophobically-modified hydroxypropyl-methyl cellulose (Sangelose, SG) and beta-cyclodextrin (β-CD) derivatives, for preventing viral respiratory infections. Eight SG/CD systems with varying CD concentrations were evaluated for rheological properties, mucoadhesiveness, spreadability and sprayability via nasal devices; cytotoxicity was in vitro investigated on reconstituted nasal epithelia. Additionally, droplet size distribution and spray deposition were assessed for the most promising systems. The addition of β-CD derivatives to SG solution was responsible for a rapid sol-gel transition within a physiological temperature range (29–34 °C). SG/CD systems were characterized by a prevalence of the elastic properties on the viscous ones at 37 °C, functional to the formation of a protective gel barrier on the mucosa. The most promising systems showed sprayability and spreadability suitable for nasal administration, while in vitro tests demonstrated their non-toxicity. All the sprays were characterized by droplets with size >100 μm, functional to avoid droplet exhalation or lung deposition; spray deposition studies confirmed uniform distribution across nasal turbinates, crucial for trapping inhaled particles. In conclusion, a mucoadhesive and thermo-responsive in situ gelling system consisting of SG and β-CD derivatives was successfully developed as promising nasal spray for the prevention of respiratory infections
La tradizione delle opere di Boccaccio. Cantieri aperti e prospettive di ricerca. Atti del Convegno Napoli, Convento di S. Domenico Maggiore Sala del Capitolo (21-23 novembre 2023), a cura di C. Ceccarelli, L. Giglio, E. Moretti e R. Vitolo, Firenze, Olschki, 2025
No full textGreen strategies for the design and the development of hybrid systems based on innovative synthetic clays
No full textThe research project involved the design and development of new green strategies to produce hybrid polymer-based systems containing innovative synthetic clays for skin tissue regeneration. The thesis is divided into five chapters. Chapter I provides an overview of the most well-known clays, both of natural and synthetic origin, used in the biomedical and pharmaceutical fields as drug delivery systems or for applications in tissue engineering. Chapter II describes innovative and sustainable strategies for the synthesis of Layered Double Hydroxides (LDH), synthetic clays, for use in tissue engineering. Chapters III and IV illustrate the design and development of microparticle polymeric systems containing previously synthesized LDH, either alone or in comparison with other types of clays. Particular attention has been paid to the use of green continuous production techniques to increase use in the industrial sector. Chapter V describes the development of polymeric microfibers through the innovative technique of centrifugal spinning. Synthetic zeolites have been loaded inside these microfibers to reinforce the polymer matrix and to promote the skin regeneration process
Pencils of plane cubics with one base point
No full textWe study pencils of plane cubics with only one base point and general member smooth, giving a complete classification. Under the additional hypothesis that all members are irre- ducible, we prove that there exists a unique non-isotrivial pencil with these properties up to projective transformations. We compare our construction with the classical approaches given by Gattazzo, Beauville and Miranda-Persson
Design of Neutral Chemistry Approaches for Li-ion and beyond Lithium Batteries of the Future
No full textTecnologia chiave per la transizione energetica sono le batterie a ioni litio. Si sono applicati due approcci, self-healing e scavenger, per garantire alle batterie di prossima generazione prestazioni, sicurezza e longevità sempre migliori. La tecnologia self-healing è impiegata in elettroliti polimerici, uno gel e uno quasi-solido, in cui l’unità riparante è il gruppo ureido-pyrimidone, che compie l’azione di riparazione mediante la formazione di un legame idrogeno quadruplo. Entrambi gli elettroliti manifestano la capacità di riparare danni meccanici in poche ore e di migliorare le prestazioni elettrochimiche rispetto ai sistemi liquidi convenzionali. Per la tecnologia scavenger si è lavorato sulla neutralizzazione di HF e H2O che portano alla dissoluzione degli ioni metallici dal catodo. Per HF si sono sviluppate nanoparticelle di Al2O3 funzionalizzate con chitosano capaciti di reagire direttamente con HF, neutralizzandolo, mentre il chitosano può coordinare i metalli dissolti, intrappolandoli. Per H2O è impiegato un MOF a base di rame che agisce come setaccio molecolare. Con questi scavenger si ottengono importanti miglioramenti nelle prestazioni elettrochimiche e nella riduzione della dissoluzione dei metalli.Lithium ion batteries are a key technology in the energy transition. Two approaches, self-healing and scavenger, were implemented with the objective of ensuring enhanced performance, safety, and longevity for next-generation batteries. The self-healing technology was applied in a gel polymer electrolyte and a quasi-solid polymer electrolyte, wherein the repair unit was the ureido-pyrimidone group, whose self-healing action is based on a quadrupole hydrogen bond. Both the electrolytes demonstrated the capacity to repair mechanical damage within a few hours and exhibited enhanced electrochemical performance compared to conventional liquid systems. With regard to scavenger technology, research was conducted on the neutralization of HF and H2O, harmful species that cause the dissolution of transition metal ions from the cathode. For HF, chitosan-functionalized Al2O3 nanoparticles were synthetized cause they are capable of reacting directly with HF, neutralizing it, while the chitosan can coordinate the dissolved metals, trapping them. A copper-based MOF acting as a molecular sieve was used for H2O. The use of these scavengers in cells resulted in notable enhancements in electrochemical performance and a reduction in metal dissolution
PIERRES ERRANTES. STONES JOURNEYS FROM CLASSICAL ANTIQUITY TO MIDDLE AGES, FROM EASTERN MEDITERRANEAN TO THE ALPS
No full textierres errantes. Stones Journeys from
Classical Antiquity to Middle Ages, from Eastern Mediterranean to the Alps was selected
among the worthy projects receiving funding from the 2022 prin-pnrr call, obtaining
ninth place in the national ranking.
The institutions involved are Università
degli Studi di Pavia, Università del Piemonte Orientale (upo) and Accademia di
Belle Arti di Brera.
The interdisciplinary research project involving archaeologists, photographers, art
historians, restorers, geographers and petrographers, focuses on the lithic materials
(limestone, slate, marble) with which the
cities of Mediolanum and Vercellae were
built, as well as some monuments of the
surrounding area, from the early Roman
imperial era to the Middle Ages
Analysis and Design of Next - Generation Ground Stations
No full textThis thesis, developed at the Antennas and Microwave Laboratory of the University of Pavia, focuses on the design and analysis of a new generation of ground stations related to the evolution of space exploration. On one hand, the frequency bands used for space communications, both for data transfer, telemetry and commands, are higher than in the past: we are transitioning from the historical S and X bands to the K and Ka bands. On the other hand, space exploration, both human and robotic, is expected to reach further and more consistently than in the recent past. Therefore, it is necessary to develop ground stations capable of supporting radio links for the transmission of the constantly increasing amount of data required from future space missions. These missions can include both deep space robotic missions (i.e. JUICE) and potential human settlements on the Moon. Specifically, this thesis describes the work done on two main projects: the first involves the design of a new antenna of the European Space Agency for deep space communications, while the second concerns a possible design for a ground station intended to maintain contact with future lunar missions.
NNO3 (New Norcia 3) is a project funded by the European Space Agency and carried out by a consortium of European companies to develop a new Deep Space Antenna in Australia, able to operate at the X, K, and Ka frequency bands. NNO3 marks the first step in a process that will double Europe's capabilities to support deep space missions. Moreover, it is also the first time, after the construction of the first European Deep Space Antenna in the late 1990s, that the entire antenna design restarts from scratch with the intent to improve the actual performance thanks to technological advancements of the last two decades. In particular, the thesis follows the various stages of development of the antenna optics and its performance, also considering the realization of specific structures such as dichroic mirrors, struts and their consequent impact on the antenna behavior. Additionally, the thesis includes the design of a system for aberration induction at the high frequencies of the Ka band, where the main lobe of the antenna radiation pattern is extremely small (about 17 millidegrees). This characteristic, combined with the huge distance from the Earth of the probes exploring the solar system, makes necessary the separation of the transmission beam from the reception one in order to avoid extremely high pointing losses that would make the communication link impossible. The thesis also provides insights into some topics that, due to the timeline of an industrial project, were not included in NNO3 but could lead to further improvements if applied to future Deep Space antennas and properly developed.
The second project addressed by the author in this thesis involves a study for a possible design of a ground station intended for lunar communications. Currently, there is a rapid increase in interest towards our satellite, and numerous missions are expected in the coming years with the goal of bringing the human being back on the Moon surface, possibly for extended periods of time as it is now a standard situation on the International Space Station. This requires a ground segment that meets the needs of these new milestones in space exploration and thus the design of more high-performance and reliable antennas. Specifically, the design of a dual-reflector antenna based on a ring focus configuration that can operate across three different frequency bands (S, X, and K) is reported. Various analyses are presented and discussed along with the obtained performance
Social practices for active solar implementation in heritage environments
No full textThe integration of modern technology into historical architecture necessitates a delicate balance between preservation and innovation, resulting in intricate endeavors to safeguard the visual esthetics, heritage significance, and cultural value of these structures. Conservation issues gain even more significance with the integration of active solar energy in the heritage built environment and protected landscapes, raising information, legislative, technical, and economic barriers to their acceptance. Addressing these challenges involves multifaceted strategies, encompassing informative campaigns, legislative measures, and technical innovations. To effectively boost the integration of these technologies, diverse approaches have been proposed, including comprehensive surveys and questionnaires, interactive focus groups, and user experience models. This chapter critically analyzes each social practice, exposing its methodologies, tools, and practical applications. The primary focus lies in delineating the implications of each technique for active solar implementation in the built environment