1,720,977 research outputs found
Valorizzazione delle biomasse e dei rifiuti per la sintesi di "top value chemicals" e materiali sostenibili
No full textL'esaurimento delle risorse della Terra, tra cui sostanze chimiche, minerali e combustibili fossili, unito alle crescenti preoccupazioni ambientali, ha determinato l'urgente necessità di una transizione verso modelli economici e industriali più sostenibili. Questa trasformazione è guidata dai principi dell'economia circolare, che cerca di minimizzare i rifiuti e ridurre l'inquinamento promuovendo la riprogettazione dei prodotti, l'efficienza delle risorse e il riutilizzo dei materiali. Il fulcro di questo approccio è la progettazione ecologica di prodotti, servizi e sistemi di nuova generazione, in cui i materiali vengono reintegrati nel ciclo tecnico-industriale (attraverso il riutilizzo e il riciclaggio, o nel ciclo biologico, attraverso il compostaggio e la biodegradazione). Un esempio significativo è il framework Cradle to Cradle, che sostiene il riutilizzo continuo dei prodotti mantenendo l'integrità delle materie prime in più cicli di vita, in contrasto con i processi di riciclaggio tradizionali che spesso portano alla degradazione dei materiali. Questo concetto enfatizza anche l'uso di sostanze chimiche non tossiche e sicure per l'ambiente. La biomassa è diventata una risorsa cruciale nel quadro dell'economia circolare, con applicazioni che includono la produzione di biocarburanti, prodotti chimici a base biologica e polimeri. Esempi di fonti di biomassa sono il legno e le colture energetiche, come la soia. Il rapido aumento della produzione di combustibili e materiali derivati interamente dalla biomassa ne evidenzia l'importanza, ma questo spostamento ha sollevato preoccupazioni riguardo all'eccessivo sfruttamento del suolo per applicazioni non alimentari, all'aumento dei costi delle materie prime (soprattutto nei Paesi in via di sviluppo), alla perdita di biodiversità, all'erosione del suolo e all'aumento della suscettibilità a parassiti e malattie. La biomassa di scarto rappresenta una valida soluzione a queste sfide. Derivata da fonti quali residui forestali, rifiuti agricoli e scarti alimentari urbani, la biomassa di scarto offre una fonte abbondante e a basso costo di carboidrati, lipidi e proteine. A livello globale, si stima che ogni anno vengano prodotte centinaia di megatonnellate (Mt) di biomassa di scarto, con un potenziale significativo per la lavorazione in loco, che la rende una promettente alternativa alle colture di biomassa dedicate. L'obiettivo principale della mia ricerca di dottorato è allineato con questi principi di economia circolare, incentrato sulla valorizzazione dei materiali di scarto (in particolare biomassa e rifiuti plastici) in prodotti chimici di alto valore, materiali polimerici sostenibili e prodotti a zero rifiutiThe depletion of Earth's finite resources, including chemicals, minerals, and fossil fuels, coupled with escalating environmental concerns, has driven the urgent need for a transition towards more sustainable economic and industrial models. This transformation is guided by the principles of the circular economy, which seeks to minimize waste and reduce pollution by promoting product redesign, resource efficiency, and material reuse. At the core of this approach is the eco-design of next-generation products, services, and systems, where materials are reintegrated into either the technical industrial cycle (through reuse and recycling, or the biological cycle, through composting and biodegradation). A notable example is the Cradle to Cradle framework, which advocates for the continual reuse of products while maintaining raw material integrity over multiple life cycles, contrasting with traditional recycling processes that often result in material degradation. This concept also emphasizes the use of non-toxic, environmentally safe chemicals. Biomass has become a critical resource within the circular economy framework, with applications including the production of biofuels, bio-based chemicals, and polymers. Examples of biomass sources include wood and energy crops, such as soy. The rapid increase in the production of fuels and materials derived entirely from biomass highlights its importance, yet this shift has raised concerns regarding soil overexploitation for non-food applications, rising raw material costs (especially in developing nations), loss of biodiversity, soil erosion, and increased susceptibility to pests and diseases. Waste biomass provides a viable solution to these challenges. Derived from sources such as forest residues, agricultural waste, and municipal food scraps, waste biomass offers a low-cost, abundant source of carbohydrates, lipids, and proteins. Globally, it is estimated that hundreds of megatonnes (Mt) of waste biomass are produced annually, with significant potential for on-site processing, making it a promising alternative to dedicated biomass crops. The primary focus of my Ph.D. research is aligned with these circular economy principles, centered on the valorization of waste materials (specifically biomass and plastic waste) into high-value chemicals, sustainable polymeric materials, and zero-waste products. Waste biomass, in particular, holds considerable potential for emerging economies, offering dual benefits in energy production and raw material sourcing without exacerbating land-use conflicts, as it capitalizes on byproducts rather than dedicated agricultural land. In my research, we developed novel protocols for converting biomass waste into valuable chemicals while achieving a zero-waste process. Additionally, we synthesized carbon quantum dots (CQDs) and polyol-polyesters from industrial byproducts using sustainable methods and catalysts, including a scandium-silica-based catalyst for polyol-polyester production.
Furthermore, significant efforts were devoted to the development of a rapid, reliable, and environmentally sustainable method for the characterization of simple sugars using gas chromatography-mass spectrometry (GC-MS). This method enhances the future identification of monosaccharides present in biomass, a key raw material for the production of chemicals and innovative materials. In parallel, we explored the valorization of plastic waste through the development of a recyclable core-shell silica-based catalyst with ionic liquid and zinc oxide confined in the core, which effectively depolymerizes plastic waste into simple monomers suitable for reuse in new material synthesis or industrial chemical production. Overall, my research contributes to the transition towards a circular economy, demonstrating how waste materials (whether from biomass or plastics) can be transformed into valuable resources, thereby fostering a more sustainable and resource-efficient industrial system
Innovative materials and systems for energy harvesting applications
No full textWearable electronics, wireless devices, and other mobile technologies have revealed a deficit and a necessity for innovative methods of gathering and utilizing power. Drawing on otherwise wasted sources of energy, such as solar, thermal, and biological, is an important part of discovering future energy solutions. Innovative Materials and Systems for Energy Harvesting Applications reports on some of the best tools and technologies available for powering humanity's growing thirst for electronic devices, including piezoelectric, solar, thermoelectric, and electromagnetic energies. This book is a crucial reference source for academics, industry professionals, and scientists working toward the future of energy
SIW cavity-backed patch antenna for Ku band applications
No full textA broadband cavity-backed microstrip patch antenna in Ku Band is designed. In particular, in order to increase the operating bandwidth a modified rectangular patch having truncated corners and two cuts in the lateral sides has been conceived. The substrate integrated waveguide (SIW) technology is chosen to realize the cavity below the patch allowing low-cost implementation, fast prototyping, and precise manufacturing. Accurate electromagnetic investigation has been performed by using two different 3D tools: CST Microwave Studio® and ANSOFT HFSS®. The performance and efficiency of the proposed antenna have been evaluated in terms of radiation pattern, bandwidth, and matching. Results show that the antenna could be used for future applications in digital radio, TV broadcast and broadband internet services. Further work will be devoted to prototype fabrication and optimizatio
Design of Mid-IR Er3+-doped microsphere laser
Get PDFA mid-IR lasing system based on a tapered fiber coupled to an Er3þ-doped
microsphere has been modeled and numerically investigated. In order to design and optimize
the device performance, a dedicated 3-D numerical code exploiting the coupled mode theory
and the rate equations model has been developed. The main energy level transitions among
the Er3þ ions, the most relevant secondary ion–ion interactions, the amplified spontaneous
emission, and the fiber-microsphere coupling phenomena have been taken into account. In
order to optimize the lasing performance, several parametric simulations have been carried
out. The obtained numerical results show that a laser threshold of about 55m Wand an output
power of about 17.8 dBm can be obtained by using small microspheres
Antenna Calibration Methods for Antenna Factor Measurements
No full textIn the fields of electromagnetic interference and electromagnetic compatibility, it is important to measure the strength of the electric field originating from electric devices. For this purpose, knowledge of the antenna factor of a receiving antenna is necessary. According to international standards, the accurate measurement of the antenna factor involves the use of calibration test sites characterized by very large sizes of both the ground plane and the empty space volume above it. As a consequence, these setup conditions make the antenna factor measurements quite expensive for the customer. In this paper, the authors discuss the well know antenna-based and site-based methods as well as recently measurement method called Antenna Impedance Method as able to obtain the free-space antenna factor. Moreover, the authors investigate on the suitability of semi-anechoic chamber for reliable antenna factor calibrations. In particular, the experimental measurements of the antenna factor obtained by using the antenna impedance method were compared with Standard Field Method and the data provided by the manufacturer of three antennas (Biconical, Log-periodic and Horn antenna) founding an agreement with the international standard ANSI C63.5-2006
Earth Long-Wave Infrared Emission, New Ways to Harvest Energy
No full textThis chapter summarizes the physical properties of THz antennas, provides a summary of some of the most important recent developments in the field of energy harvesting of Earth long-wave infrared radiation, discusses the potential applications and identifies the future challenges and opportunities. In particular, a THz antenna is designed in order to transform the thermal energy, provided by the Sun and re-emitted from the Earth, in electricity. The proposed antenna is a square spiral of gold printed on a low cost dielectric substrate. Simulations have been conducted in order to investigate the behavior of the antenna illuminated by a circularly polarized plane wave with an amplitude chosen according to the Stefan-Boltzmann radiation law. Moreover, these THz antennas could be coupled with other components to obtain direct rectification of T radiation. As a consequence, these structures further optimized could be a promising alternative to the conventional photovoltaic solar cells
Design of optical antenna for solar energy collection
No full textIn this paper, an antenna array is designed in order to transform the thermal energy, provided by the Sun
and re-emitted from the Earth, in electricity. The proposed antenna array is constituted by four square
spirals of gold printed on a low cost dielectric substrate. A microstrip line, embedded into the substrate,
is used to feed the array and to collect the thermal radiation. The dispersive behavior of gold at infrared
frequencies has been taken into account through the LorentzeDrude model. Simulations have been
conducted in order to investigate the behavior of the antenna array illuminated by a circularly polarized
plane wave with an amplitude chosen according to the StefaneBoltzmann radiation law. An output
current of about 3.8 mA has been simulated at 28.3 THz, i.e. at the frequency of the Earth emitted
radiation. Moreover, these infrared antennas could be coupled with other components to obtain direct
rectification of infrared radiation. As a consequence, these structures further optimized could be
a promising alternative to the conventional photovoltaic solar cells
Measurements in the hyperpolarized helium-3 for medical applications
No full textHyperpolarized helium-3 (3He) gas, is a new contrast agent for lung imaging diagnostic in functional Magnetic Resonance Imaging (fMRI) becoming an important technique to diagnose diseases and abnormalities in the respiratory tract. In this paper is described a new modular production method of 3He gas, hyperpolarized using the Metastability Exchange Optical Pumping Technique (MEOP). A standard set of measurements has been collected considering a prototype developed by ITEL Telecomunicazioni srl, able to produce one litre of 3He polarized gas at the pressure of 1000 mbar. A 27% of polarization at a pressure of 1 mbar is obtained in the optical pumping cell in a single run, while a time of about 20 minutes is needed to pump the gas at a final pressure of 1000 mbar in the storage cell
A new scandium based catalyst for the green synthesis of polyols-polyesters starting from waste raw materials
No full textFollowing our previous studies aimed at the valorization of cellulose waste and glycerol, biobased polyols-polyesters were synthesized using both a "green approach" and a novel heterogeneous catalyst based on scandium silicate thortveitite. The latter showed an enhanced linear selectivity compared with most of the analogous catalysts reported in recent studies. Polymers obtained were tested in two important reactions with potential industrial applications: as co-monomers for the synthesis of polyurethanes and as binders for 3D printers. The polyols-polyesters were obtained, with the average molecular weight ranging from 440 to 1050 Da. It is worth noting that the typical polyol polyester used in coatings is branched and has an average molecular weight of 2000-4000 Da.A new scandium-based catalyst was prepared under sustainable conditions, for the controlled synthesis of polyols-polyesters at low temperature and under solvent-free conditions
Compact double-layer substrate integrated waveguide magic Tee for X-band applications
No full textA substrate integrated waveguide Magic Tee with very compact size and operating over a wide band is proposed. The circuit is made of two stacked substrates connected by cutting a small aperture between them. This solution presents slightly higher complexity compared to a single substrate magic Tee but it avoids the radiation losses because the circuit is completely closed. A simple and effective procedure is used to design the circuit. A prototype is built and experimental results show a good agreement with simulations
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