Study and development of BaCe0.65Zr0.20Y0.1503-Δ (BCZY) – Gd0.2Ce0.8O2-Δ (GDC) dense ceramic membranes sysyem for high temperature H2 purification

The first main conclusion drawn from this dissertation concerns the amount of Pt deposited on the asymmetric layer of membrane produced by tape casting porosity shaping method. Three different amounts were investigated (0.15, 1.5 and 4.5 mg cm-2 ). The most optimal performance, based on H2 permeation performances, was attained when 1.5 mg cm-2 of Pt was deposited on the porous layer, resulting in a 0.642 mL min-1 cm-2 permeated H2 when 80% H2 in He was employed as the feed. Pt deposition method is influenced by the concentration of the Pt precursor, which results in different morphology of the catalyst. The second development focused on further optimization on tape casting membranes concerning the solvent employed for the Pt catalyst deposition. The same concentration of Pt was employed, depositing 1.5 mg cm-2 on the porous side of the membrane, but a mixture of acetone and water was employed as solvent. This mixture allowed the suppression of effects leading to poorly dispersed particles. As a result, it was possible to achieve 0.74 mL min-1 cm-2 at 750°C with 50% H2 in He. Lastly, first-ever permeation performance measurements into an innovative ceramic membrane type for hydrogen separation was investigated. In-depth research was done on a group of hierarchically-structured BaCe0.65Zr0.20Y0.15O3-δ(BCZY) - Gd0.2Ce0.8O2-δ(GDC) membranes produced by freeze casting porosity shaping method. Membranes were investigated observing the effect of deposition solvent and the effect of porous layer thickness. Employing a mixture of Acetone and water resulted in better hydrogen permeation at temperatures (T > 650°C), reaching 0.26 mL min-1 cm-2 at 750°C with 50% H2 in He. The reduction of porous layer thickness led to a hydrogen flow of 0.33 mL min-1 cm-2 , at 750°C with 50% H2 in He.

Innovative Al Alloys for High Performance Automotive Pistons: Enhancement of Specific Strength at High Temperature and Resistance to Knock Damage

The increasingly strict regulations on greenhouse gas emissions make the fuel economy a pressing factor for automotive manufacturers. Lightweighting and engine downsizing are two strategies pursued to achieve the target. In this context, materials play a key role since these limit the engine efficiency and components weight, due to their acceptable thermo-mechanical loads. Piston is one of the most stressed engine components and it is traditionally made of Al alloys, whose weakness is to maintain adequate mechanical properties at high temperature due to overaging and softening. The enhancement in strength-to-weight ratio at high temperature of Al alloys had been investigated through two approaches: increase of strength at high temperature or reduction of the alloy density. Several conventional and high performance Al-Si and Al-Cu alloys have been characterized from a microstructural and mechanical point of view, investigating the effects of chemical composition, addition of transition elements and heat treatment optimization, in the specific temperature range for pistons operations. Among the Al-Cu alloys, the research outlines the potentialities of two innovative Al-Cu-Li(-Ag) alloys, typically adopted for structural aerospace components. Moreover, due to the increased probability of abnormal combustions in high performance spark-ignition engines, the second part of the dissertation deals with the study of knocking damages on Al pistons. Thanks to the cooperation with Ferrari S.p.A. and Fluid Machinery Research Group - Unibo, several bench tests have been carried out under controlled knocking conditions. Knocking damage mechanisms were investigated through failure analyses techniques, starting from visual analysis up to detailed SEM investigations. These activities allowed to relate piston knocking damage to engine parameters, with the final aim to develop an on-board knocking controller able to increase engine efficiency, without compromising engine functionality. Finally, attempts have been made to quantify the knock-induced damages, to provide a numerical relation with engine working conditions.

Light energy management in peach: utilization, photoprotection , photodamage and recovery. Maximizing light absorption in orchard is not always the best solution

The relation between the intercepted light and orchard productivity was considered linear, although this dependence seems to be more subordinate to planting system rather than light intensity. At whole plant level not always the increase of irradiance determines productivity improvement. One of the reasons can be the plant intrinsic un-efficiency in using energy. Generally in full light only the 5 – 10% of the total incoming energy is allocated to net photosynthesis. Therefore preserving or improving this efficiency becomes pivotal for scientist and fruit growers. Even tough a conspicuous energy amount is reflected or transmitted, plants can not avoid to absorb photons in excess. The chlorophyll over-excitation promotes the reactive species production increasing the photoinhibition risks. The dangerous consequences of photoinhibition forced plants to evolve a complex and multilevel machine able to dissipate the energy excess quenching heat (Non Photochemical Quenching), moving electrons (water-water cycle , cyclic transport around PSI, glutathione-ascorbate cycle and photorespiration) and scavenging the generated reactive species. The price plants must pay for this equipment is the use of CO2 and reducing power with a consequent decrease of the photosynthetic efficiency, both because some photons are not used for carboxylation and an effective CO2 and reducing power loss occurs. Net photosynthesis increases with light until the saturation point, additional PPFD doesn’t improve carboxylation but it rises the efficiency of the alternative pathways in energy dissipation but also ROS production and photoinhibition risks. The wide photo-protective apparatus, although is not able to cope with the excessive incoming energy, therefore photodamage occurs. Each event increasing the photon pressure and/or decreasing the efficiency of the described photo-protective mechanisms (i.e. thermal stress, water and nutritional deficiency) can emphasize the photoinhibition. Likely in nature a small amount of not damaged photosystems is found because of the effective, efficient and energy consuming recovery system. Since the damaged PSII is quickly repaired with energy expense, it would be interesting to investigate how much PSII recovery costs to plant productivity. This PhD. dissertation purposes to improve the knowledge about the several strategies accomplished for managing the incoming energy and the light excess implication on photo-damage in peach. The thesis is organized in three scientific units. In the first section a new rapid, non-intrusive, whole tissue and universal technique for functional PSII determination was implemented and validated on different kinds of plants as C3 and C4 species, woody and herbaceous plants, wild type and Chlorophyll b-less mutant and monocot and dicot plants. In the second unit, using a “singular” experimental orchard named “Asymmetric orchard”, the relation between light environment and photosynthetic performance, water use and photoinhibition was investigated in peach at whole plant level, furthermore the effect of photon pressure variation on energy management was considered on single leaf. In the third section the quenching analysis method suggested by Kornyeyev and Hendrickson (2007) was validate on peach. Afterwards it was applied in the field where the influence of moderate light and water reduction on peach photosynthetic performances, water requirements, energy management and photoinhibition was studied. Using solar energy as fuel for life plant is intrinsically suicidal since the high constant photodamage risk. This dissertation would try to highlight the complex relation existing between plant, in particular peach, and light analysing the principal strategies plants developed to manage the incoming light for deriving the maximal benefits as possible minimizing the risks. In the first instance the new method proposed for functional PSII determination based on P700 redox kinetics seems to be a valid, non intrusive, universal and field-applicable technique, even because it is able to measure in deep the whole leaf tissue rather than the first leaf layers as fluorescence. Fluorescence Fv/Fm parameter gives a good estimate of functional PSII but only when data obtained by ad-axial and ab-axial leaf surface are averaged. In addition to this method the energy quenching analysis proposed by Kornyeyev and Hendrickson (2007), combined with the photosynthesis model proposed by von Caemmerer (2000) is a forceful tool to analyse and study, even in the field, the relation between plant and environmental factors such as water, temperature but first of all light. “Asymmetric” training system is a good way to study light energy, photosynthetic performance and water use relations in the field. At whole plant level net carboxylation increases with PPFD reaching a saturating point. Light excess rather than improve photosynthesis may emphasize water and thermal stress leading to stomatal limitation. Furthermore too much light does not promote net carboxylation improvement but PSII damage, in fact in the most light exposed plants about 50-60% of the total PSII is inactivated. At single leaf level, net carboxylation increases till saturation point (1000 – 1200 μmolm-2s-1) and light excess is dissipated by non photochemical quenching and non net carboxylative transports. The latter follows a quite similar pattern of Pn/PPFD curve reaching the saturation point at almost the same photon flux density. At middle-low irradiance NPQ seems to be lumen pH limited because the incoming photon pressure is not enough to generate the optimum lumen pH for violaxanthin de-epoxidase (VDE) full activation. Peach leaves try to cope with the light excess increasing the non net carboxylative transports. While PPFD rises the xanthophyll cycle is more and more activated and the rate of non net carboxylative transports is reduced. Some of these alternative transports, such as the water-water cycle, the cyclic transport around the PSI and the glutathione-ascorbate cycle are able to generate additional H+ in lumen in order to support the VDE activation when light can be limiting. Moreover the alternative transports seems to be involved as an important dissipative way when high temperature and sub-optimal conductance emphasize the photoinhibition risks. In peach, a moderate water and light reduction does not determine net carboxylation decrease but, diminishing the incoming light and the environmental evapo-transpiration request, stomatal conductance decreases, improving water use efficiency. Therefore lowering light intensity till not limiting levels, water could be saved not compromising net photosynthesis. The quenching analysis is able to partition absorbed energy in the several utilization, photoprotection and photo-oxidation pathways. When recovery is permitted only few PSII remained un-repaired, although more net PSII damage is recorded in plants placed in full light. Even in this experiment, in over saturating light the main dissipation pathway is the non photochemical quenching; at middle-low irradiance it seems to be pH limited and other transports, such as photorespiration and alternative transports, are used to support photoprotection and to contribute for creating the optimal trans-thylakoidal ΔpH for violaxanthin de-epoxidase. These alternative pathways become the main quenching mechanisms at very low light environment. Another aspect pointed out by this study is the role of NPQ as dissipative pathway when conductance becomes severely limiting. The evidence that in nature a small amount of damaged PSII is seen indicates the presence of an effective and efficient recovery mechanism that masks the real photodamage occurring during the day. At single leaf level, when repair is not allowed leaves in full light are two fold more photoinhibited than the shaded ones. Therefore light in excess of the photosynthetic optima does not promote net carboxylation but increases water loss and PSII damage. The more is photoinhibition the more must be the photosystems to be repaired and consequently the energy and dry matter to allocate in this essential activity. Since above the saturation point net photosynthesis is constant while photoinhibition increases it would be interesting to investigate how photodamage costs in terms of tree productivity. An other aspect of pivotal importance to be further widened is the combined influence of light and other environmental parameters, like water status, temperature and nutrition on peach light, water and phtosyntate management.

Technological processes study for high value health ingredients and foods production

This PhD thesis describes set up of technological models for obtaining high health value foods and ingredients that preserve the final product characteristics as well as enrich with nutritional components. In particular, the main object of my research has been Virgin Olive Oil (VOO) and its important antioxidant compounds which differentiate it from all other vegetables oils. It is well known how the qualitative and quantitative presence of phenolic molecules extracted from olives during oil production is fundamental for its oxidative and nutritional quality. For this purpose, agronomic and technological conditions of its production have been investigated. It has also been examined how this fraction can be better preserved during storage. Moreover, its relation with VOO sensorial characteristics and its interaction with a protein in emulsion foods have also been studied. Finally, an experimental work was carried out to determine the antioxidative and heat resistance properties of a new antioxidant (EVS-OL) when used for high temperature frying such as is typically employed for the preparation of french fries. Results of the scientific research have been submitted for a publication and some data has already been published in national and international scientific journals.

Materiali Ceramici per Edilizia con Funzionalità Fotocatalitica

This thesis wad aimed at the study and application of titanium dioxide photocatalytic activity on ceramic materials. As a matter of fact, photocatalysis is a very promising method to face most of the problems connected with the increasing environmental pollution. Furthermore, titanium dioxide, in its anatase crystallographic phase, is one of the most investigated photocatalytic material and results to be perfectly compatible with silicate body mixes. That goal was pursued by two different strategies: 1. the addition to a body mix used for heavy clay products of several titania powders, with different mean crystallite size, surface area, morphology and anatase/rutile ratio and a titania nanosuspension as well. The titania addition followed two procedures: bulk and spray addition over the ceramic samples surface. Titania was added in two different percentages: 2.5 and 7.5 wt.% in both of the methods. The ceramic samples were then fired at three maximum temperatures: 900, 950 and 1000 °C. Afterwards, the photocatalytic activity of the prepared ceramic samples was evaluated by following the degradation of an organic compound in aqueous medium, under UV radiation. The influence of titania morphological characteristics on the photoactivity of the fired materials was studied by means of XRD and SEM observations. The ceramic samples, sprayed with a slip containing 7.5 wt.% of titania powder and fired at 900 °C, have the best photoactivity, with a complete photo-decomposition of the organic compound. At 1000 °C no sample acted as a photocatalyst due to the anatase-to-rutile phase transformation and to the reaction between titania and calcium and iron oxides in the raw materials. 2. The second one foresaw the synthesis of TiO2-SiO2 solid solutions, using the following stoichiometry: Ti1-xSixO2 where x = 0, 0.1, 0.3 and 0.5 atoms per formula unit (apfu). The mixtures were then fired following two thermal cycles, each with three maximum temperatures. The effect of SiO2 addition into the TiO2 crystal structure and, consequently, on its photocatalytic activity when fired at high temperature, was thoroughly investigated by means of XRD, XPS, FE-SEM, TEM and BET analysis. The photoactivity of the prepared powders was assessed both in gas and liquid phase. Subsequently, the TiO2-SiO2 solid solutions, previously fired at 900 °C, were sprayed over the ceramic samples surface in the percentage of 7.5 wt.%. The prepared ceramic samples were fired at 900 and 1000 °C. The photocatalytic activity of the ceramic samples was evaluated in liquid phase. Unfortunately, that samples did not show any appreciable photoactivity. In fact, samples fired at 900 °C showed a pretty low photoactivity, while the one fired at 1000 °C showed no photoactivity at all. This was explained by the excessive coarsening of titania particles. To summarise, titania particle size, more than its crystalline phase, seems to have a relevant role in the photocatalytic activity of the ceramic samples.

Celle ad Ossidi Solidi per Elettrolisi ad Alta Temperatura

Lo scopo di questa tesi è stato la produzione di un elettrolizzatore ad ossidi solidi (SOEC) mediante tecniche economiche e facilmente industrializzabili. Fondamentale a questo scopo è stata la realizzazione di una semicella costituita da un anodo poroso a base di La0.8Sr0.2MnO3-Ce0.8Gd0.2O2-δ (LSM-GDC) ed un elettrolita denso a base di Ce0.8Gd0.2O2-δ (GDC). Le tecniche utilizzate per la produzione di questo sistema sono state il colaggio su nastro e la serigrafia. Anche se generalmente, le celle SOEC vengono prodotte catodo supportate, in questo studio, l’elemento supportante scelto è stato l’anodo poiché questo garantisce una migliore stabilità meccanica all’intera cella. Tale substrato è stato ottenuto mediante colaggio su nastro accoppiato con un metodo innovativo di sinterizzazione denominato sinterizzazione reattiva, processo che prevede la formazione della fase di interesse durante un unico trattamento termico di eliminazione degli additivi organici e consolidamento del manufatto finale. La membrana elettrolitica per l’ottenimento del bilayer anodo-elettrolita, è stata prodotta mediante sia serigrafia che colaggio su nastro. L’accurato studio dell’evoluzione di fase della polvere anodica, l’ottimizzazione della sospensione per colaggio su nastro e dei trattamenti termici hanno permesso l’ottenimento di anodi (fino a dimensioni di 10x10 cm2). Lo studio dei profili di sinterizzazione delle polveri anodica ed elettrolitica e dell’influenza della tecnica di formatura sulla sinterabilità dei layer elettrolitici prodotti hanno inoltre permesso l’ottenimento di una semicella planare costituita da un elettrodo poroso ed una membrana elettrolitica densa adatte per applicazioni SOEC.

Effects of temperature and acidity on Mediterranean benthic calcifiers, in the face of globale climate change

The Mediterranean Sea is expected to react faster to global change compared to the ocean and is already showing more pronounced warming and acidification rates. A study performed along the Italian western coast showed that porosity of the skeleton increases with temperature in the zooxanthellate (i.e. symbiotic with unicellular algae named zooxanthellae) solitary scleractinian Balanophyllia europaea while it does not vary with temperature in the solitary non-zooxanthellate Leptopsammia pruvoti. These results were confirmed by another study that indicated that the increase in porosity was accompanied by an increase of the fraction of the largest pores in the pore-space, perhaps due to an inhibition of the photosynthetic process at elevated temperatures, causing an attenuation of calcification. B. europaea, L. pruvoti and the colonial non-zooxanthellate Astroides calycularis, transplanted along a natural pH gradient, showed that high temperature exacerbated the negative effect of lowered pH on their mortality rates. The growth of the zooxanthellate species did not react to reduced pH, while the growth of the two non-zooxanthellate species was negatively affected. Reduced abundance of naturally occurring B. europaea, a mollusk, a calcifying and a non-calcifying macroalgae were observed along the gradient while no variation was seen in the abundance of a calcifying green alga. With decreasing pH, the mineralogy of the coral and mollusk did not change, while the two calcifying algae decreased the content of aragonite in favor of the less soluble calcium sulphates and whewellite (calcium oxalate), possibly as a mechanism of phenotypic plasticity. Increased values of porosity and macroporosity with CO2 were observed in B. europaea specimens, indicating reduces the resistance of its skeletons to mechanical stresses with increasing acidity. These findings, added to the negative effect of temperature on various biological parameters, generate concern on the sensitivity of this zooxanthellate species to the envisaged global climate change scenarios.

Dissecting the Heat-Stress Tolerance QTLome in Durum Wheat

Heat stress negatively affects wheat performance during its entire cycle, particularly during the reproductive stage. In view of the climate change and the prediction of a continued increase in temperature in the new future, it is urgent to concentrate efforts to discover novel genetic sources able to improve the resilience of wheat to heat stress. In this direction, this study addressed two different experiments in durum wheat to identify novel QTLs suitable to be applied in marker-assisted selection for heat tolerance. Chlorophyll fluorescence (ChlF) is a valuable indicator of plant response to environmental changes allowing a detailed assessment of PSII activity in view of its non-invasive measurement and high-throughput phenotyping. In the first study (Chapter 2), the Light-Induced Fluorescence Transient (LIFT) method was used to access ChlF data to map QTLs for ChlF-related traits during the vegetative growth stage in durum wheat under heat stress condition. Our results provide evidence that LIFT consistently measures ChlF at the level of high-throughput phenotyping combined with high accuracy which is required for Genome-Wide Association Study (GWAS) aimed at identifying genomic regions affecting PSII activity. The 50 QTLs identified for ChlF-related traits under heat stress mostly clustered into five chromosomes hotspots unrelated to phenology, a feature that makes these QTLs a valuable asset for marker-assisted breeding programs across different latitudes. In the second study (Chapter 3), a set of 183 accessions suitable for GWAS, was exposed to optimal and high temperature during two crop seasons under field conditions. Important agronomic traits were evaluated in order to identify valuable QTLs for GY and its components. The GWAS analysis identified several QTLs in the single years as well as in the joint analysis. From the total QTLs identified, 13 QTL clusters can be highlighted to be affecting heat tolerance across different years and/or different traits.

High power density electrical machines with hairpin windings

Nowadays, electrical machines are seeing an ever-increasing development and extensive research is currently being dedicated to the improvement of their efficiency and torque/power density. Compared to conventional random windings, hairpin winding inherently features lower DC resistance, higher fill factor, better thermal performance, improved reliability, and an automated manufacturing process. However, several challenges need to be addressed, including electromagnetic, thermal, and manufacturing aspects. Of these, the high ohmic losses at high-frequency operations due to skin and proximity effects are the most severe, resulting in low efficiency or high-temperature values. In this work, the hairpin winding challenges were highlighted at high-frequency operations and at showing the limits of applicability of these standard approaches. Afterward, a multi-objective design optimization is proposed aiming to enhance the exploitation of the hairpin technology in electrical machines. Efficiency and volume power density are considered as main design objectives. Subsequently, a changing paradigm is made for the design of electric motors equipped with hairpin windings, where it is proven that a temperature-oriented approach would be beneficial when designing this type of pre-formed winding. Furthermore, the effect of the rotor topology on AC losses is also considered. After providing design recommendations and FE electromagnetic and thermal evaluations, experimental tests are also performed for validation purposes on a motorette wound with pre-formed conductors. The results show that operating the machine at higher temperatures could be beneficial to efficiency, particularly in high-frequency operations where AC losses are higher at low operating temperatures. The last part of the thesis focuses on comparing the main electromagnetic performance metrics for a conventional hairpin winding, wound onto a benchmark stator with a semi-closed slot opening design, and a continuous hairpin winding, in which the slot opening is open. Lastly, the adoption of semi-magnetic slot wedges is investigated to improve the overall performance of the motor.