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2010 - 2011 The increase in dietary-intake-related illnesses, such as obesity, cardiovascular diseases, hypertension, diabetes and cancer, have made in recent years the development of health-and-wellness promoting foods a priority of the food industry. Clinical studies have demonstrated tangible health benefits that may be derived from the intake of bioactive compounds. However many difficulties are associated with their inclusion in food matrices, due to a very low solubility in water and easy degradation by hostile environmental conditions once extracted from plant tissues. Furthermore, poor solubility also means lower absorption in the gastrointestinal tract and, therefore, limited bioavailability. In the food industry, it has become apparent that there is a pressing need for edible delivery system to efficiently encapsulate, protect and release bioactive compounds when developing functional foods. This thesis was addressed to the study and engineering of nanoencapsulation systems, above all nanoemulsions and solid lipid nanoparticles, with superior capabilities of a) protecting the encapsulated bioactive compounds from interaction with food ingredients, keeping their functional properties and preventing the deterioration of the food itself (i.e. oxidation of fat), b) reducing the impact on the organoleptic properties of food and c) improving the absorption and bioavailability of the bioactives, due to the subcellular size of the nanocapsules, which may potentially enhance passive transport mechanisms (i.e. related to the concentration gradient) across the intestinal wall. The research activity has contributed to the advance of the knowledge in the field of the science of colloids, through the specific investigation of the effects of formulation and process parameters, which influence nanoemulsion production, as well as to a deeper comprehension of the technological and biological aspects of the incorporation of the nanoencapsulated compounds in food matrices and explication of their activity. Three different classes of bioactive compounds were chosen as model systems of the experimental work, namely curcumin, resveratrol and essential oils. Both curcumin and resveratrol are antioxidant compounds with markedly low solubility both in aqueous and lipid phase, hence requiring the development of specific formulations. In contrast, essential oils can be easily blended with oils, but require their diffusion through the aqueous phase to attack the cell membrane of microorganisms and act as antimicrobials. Therefore, novel formulations were developed using a combination of hydrophilic (sugar ester, defatted soy lecithin, polysorbate 20) and lipophilic emulsifiers (soy lecithin, glycerol monooleate) to encapsulate resveratrol in peanut oil droplets and disperse it in aqueous systems at a concentration of 100 mg/L, ten times higher than the therapeutic blood concentration. In the same way, curcumin has been encapsulated in solid lipid particles, using stearic acid as lipid phase, at a maximum concentration 1600 times higher than the solubility of curcumin in water (0.6 mg/L). Once the formulation was defined, the issue of the actual fabrication of the nanometric delivery systems was faced from a fundamental point of view. In particular, the production of food nanoemulsions by high pressure homogenization (HPH) has been investigated, focusing on the effect on droplet nanonization of emulsifier type and concentration, as well as of the geometry of the homogenization chamber. The reported results showed that the kinetic parameters of the emulsification process can be primarily correlated with the interfacial and dynamic properties of the emulsifiers, while the fluid-dynamics regime established in the homogenization chamber contributes only to a lesser extent. Nevertheless, the correct design of the homogenization chamber may help in obtaining uniform fluid-dynamic conditions, which ensure a narrow droplet size distribution. The issues related to the physicochemical stability of nanoencapsulated bioactive compounds was faced for resveratrol and curcumin, trying to improve the formulation based on the inputs derived from accelerated ageing studies, that could simulate the food processing and the shelf life of the final product. The results obtained demonstrated that the nanoemulsions based on soy lecithin/sugar esters and Tween 20/glycerol monooleate can better encapsulate resveratrol in the lipid matrix, protecting it both during accelerated ageing and gastro-intestinal digestion and promoting a sustained release. Moreover, these formulations, having smaller mean droplet diameters (below 200 nm), remained physically stable also after the digestion process, allowing the resveratrol to reach the intestinal wall entrapped in the lipid droplets. The subcellular dimension and the compatibility with cell membranes of the developed formulations also resulted in a higher permeability through the intestinal wall, which was simulated studying the transport through Caco-2 cell monolayers grown on permeable supports. Generally, the apparent permeability of most compounds falls in a range of 1×10-7 cm/sec (poorly transported compound) to 1×10-5 cm/sec (well-transported compound). The apparent permeability of resveratrol encapsulated in different nanoemulsion-based delivery systems resulted always in the range indicated, demonstrating that nanoencapsulation can improve passive transport mechanisms. In particular, soy lecithin/sugar esters-based formulation showed an higher permeability due to the presence of soy lecithin, which, having a structure similar to the phospholipid bilayers of the cellular membrane, favours the absorption and the entrapment of the oil droplets in the microvilli and their consequent transport through the cell membrane. Another remarkable result of the present thesis is that for the first time the effect of the delivery systems on the antioxidant activity of nanoencapsulated compounds was investigated, using a biological-based approach that integrated the classical chemical approaches. More specifically, an improved cellular assay was developed, that enabled to measure exclusively the residual activity of nanoencapsulated bioactive that penetrated inside Caco-2 cells, giving precious information on the combination of the mass transfer promotion and protection by the delivery systems. Finally, the technological issue related to the incorporation into fruit juices of essential oils encapsulated into nanometric delivery systems was investigated, having as goal the design of systems that are able to enhance antimicrobial activity of the bioactive compounds, while minimizing the impact on the quality attributes of the final product. The results showed that, due to the higher antimicrobial activity of the nanoencapsulated essential oils, lower antimicrobial concentrations are required for a bactericidal action with a minimal alteration of the organoleptic properties of the juice. [edited by author] X n.s.

2010 - 2011 Changes of cohesive flow properties of powders at high temperature are observed in many industrial process units, such as fluidized bed reactors, granulators and dryers. Many authors investigated the behaviour of powders at high temperature through fluidization experiments (Formisani et al., 1998 and 2002; Lettieri et al., 2000 a d 2001), measurements of the interparticle forces (Pagliai et al., 2004 and 2007) and direct measurements at the bulk level (Kamiya et al., 2002). However, the understanding of the effect of temperature on interparticle interactions and flow properties of bulk solid is not clear yet. A common approach in engineering science consists of the direct characterization of the rheology of powders like bulk solids by means of shear cells. In this work a High Temperature Annular Shear Cell, originally designed at University of Salerno, was set-up and used to measure yield loci up to 500°C and to directly evaluate the effect of temperature on the macroscopic flow properties of sample of fluid cracking catalyst powder, fly ashes, corundum, synthetic porous -alumina and glass beads. Different behaviour was observed for each material. The flowability of the FCC powder, fly ashes and corundum did not show change as the temperature increased differently from glass beads and, at lower extent, porous alumina for which an increment of the cohesive behaviour was observed. In order to give an interpretation of the effect of temperature on the interparticle interactions, a theoretical framework was developed according to the particle-particle approach of Rumpf (1974) and Molerus (1985 and 1993). Furthermore, the availability of a microscopic model able to estimate quantitatively the 2 interparticle interactions might extend the experimental findings to different compaction conditions, in particular lower than within the powder tester. For this purpose, the tensile strength of the powder experimentally evaluated was related to contact forces acting between particles by coupling the Rumpf equation with the equation of the contact force. Only van der Waals’ forces were assumed as present inside the bulk solid, according to DSC analysis performed in this work that revealed no melting points and formation of liquid bridges for all materials in the range of operating temperature. With this regard two alternative assumptions of elastic or plastic deformation at the contact point of particles were considered. Both the assumptions provide correct order of magnitude results in terms of tensile strength, provided that a plausible value of the local curvature at contact points of particles is taken into account by correctly considering the effect of surface roughness and asperities, according to SEM magnification performed for all the materials. A sensitivity analysis on the main parameters of the theoretical framework was performed. Both the increasing cohesive consolidation and the slight increase of the cohesive behaviour with the temperature suggest the occurrence of the plastic deformation of the contact points and, therefore, that the plastic deformation assumption should be adopted to explain the effect of the temperature on the interparticle interactions. However, at room temperature, the effect of consolidation seems to be correctly represented considering also the decrease of the voidage. Finally, a significant increase of the macroscopic cohesive behaviour of powder with the temperature was measured in presence of a liquid phase which promoted the aggregation of the particles, as verified with shear tests and SEM magnifications performed on sample of glass beads mixed with the low-melting temperature high-density polyethylene (HDPE) powder. [edited by author] X n.s.

2010 - 2011 This research work rises from collaborative activities between Alenia Aeronautica (Pomigliano D’Arco, Napoli) and the Industrial Engineering Department of University of Salerno. One of the biggest challenge facing materials scientists is the idea to put in action self-healing composites in aeronautical applications. Polymeric composite materials, recently introduced in aeronautics, are subject to weakening due to mechanical, chemical, thermal, stress. This could lead to the formation of microcracks deep within the structure where detection and external intervention are difficult or impossible. The presence of the microcracks in the polymer matrix can affect both the fiber and matrix dominated properties of a composite. In the case of a transport vehicle, the propagation of microcracks may compromise the structural integrity of the polymeric components, and so threatening passengers’ safety. In this work, we have developed a multifunctional autonomically healing composite with a selfhealing functionality active at the severe operational conditions of aircrafts (temperature range: -50 °C/80 °C). The self-repair function in this new self-healing system, inspired by the design of White et al., is based on the metathesis polymerization of ENB (or ENB/DCPD blend) activated by Hoveyda-Grubbs’1st generation catalyst. The self-healing epoxy mixture, containing Hoveyda-Grubbs’1st generation catalyst, allows a cure temperature up to 180 °C without becoming deactivated. A quantitative assessment of self-healing functionality showed very high values of selfhealing efficiency. Before reaching these amazing results several systems were investigated that differ for the nature and the composition of the epoxy matrix, catalysts and active monomers used:these systems have been gradually improved to suit performance requirements for a structural advanced material to be applied to aeronautical vehicles. [edited by the author] X n.s.

2010 - 2011 The objective of this PhD project regards the formulation, preparation and characterization of polymeric materials in which lamellar inorganic solids containing potentially active molecules are dispersed. In particular the present work was aimed at the preparation and characterization of "Active Food Packaging Materials" using inorganic fillers modified with active molecules (antimicrobials, antioxidants) dispersed in polymeric matrices for the realization of: 1) Materials with improved barrier properties to gases and vapors 2) Systems for controlled release of active molecules, act to protect and extend the shelf life of food products. Two techniques of dispersion of active inorganic fillers in polymer matrices have been used, generating: 1) polymeric nanocomposites 2) coatings of polymeric surfaces. A screening of different polymers, from biodegradable and thermoplastic to natural, was done to compare the effect of the fillers and of the dispersion technique on the properties mentioned above.[edited by author] X n.s.

2010 - 2011 In recent decades, the concrete for years considered unchangeable and with an unlimited life, with exceptional mechanical properties which have determined principally its success, was in fact subject to phenomena of degradation which over time alter its durability. The degradation of concrete is hardly attributable to a single cause because often multiple processes can occur simultaneously, interacting in a synergistic way. Any degradation mechanism occurs, it is closely related to transport and diffusion of water in the concrete, i.e. the degree of porosity. Although the porosity of the concrete substrate is an intrinsic characteristic of the material itself, and therefore unavoidable, its control is crucial. The protective polymer-based resins are the most commonly used for concrete structures, because they are very effective to provide a physical barrier to the ingress of water, ions and gases. Despite their good efficacy in prolonging the service life of the structures, there is a need for further increase the barrier properties and their compatibility with the substrate in aggressive environmental conditions. In recent times, polymer-organoclay nanocomposites have emerged as a new class of high performance materials: in these systems nanoparticles are homogeneously dispersed in the polymer matrix in order to obtain an exfoliated structure. The high aspect ratio, which means a strong interactions between the nanofillers and the polymer, make the nanocomposites excellent organic-inorganic systems (compared to pure polymer or microcomposite systems), in terms of mechanical, thermal, optical and barrier properties. This is the reason why, it has been thought to use these systems as potentially effective protective coating for building structures, even in the most severe environmental conditions. In this thesis work different systems obtained by mixing a filler, in particular two kind of montmorillonite organically modified, with fluoro-based resins and silane-siloxane have been studied. The protective efficacy of these systems, at different charge content has been verified and the results demonstrate the potential application of polymer/organoclay nanocomposites as surface treatment materials for concrete structures. Moreover, in literature very often the use of some additives such as micro and nanoparticles is studied because it is expected that both strength and durability of a concrete could be enhanced if the overall porosity is reduced. In particular in the last years different kinds of inorganic nanoparticles, due to their physical and chemical properties, are very often integrated with cement-based building materials; in fact, thanks to their high surface area to volume ratio they can react with calcium hydroxide (Ca(OH)2) crystals, arrayed in the interfacial transition zone, and produce C–S–H gel which fills the voids to improve the density of the interfacial zone. Stable gel structures can be formed and the mechanical and the service-life properties of hardened cement paste can be improved when a smaller amount of nanoparticles is added. On the other hand, the same hydrophobic agents used as surface protective, thanks to their capability in reduction significantly the molecular attraction between the water and the concrete, could be directly added in the concrete mix in order to make the whole concrete bulk hydrophobic. Thus, in this work the research is aimed to investigate the separated and combined effect of a hydrophobic resin (silanes and siloxanes in water base) and of the nanoparticles (two montmorillonites organically modified, the Cloisite 30B and the Halloysite) on concrete durability in relation with the analysis of transport properties of cement based systems, not yet deepened in literature. [edited by author] X n.s.

Design equations are given for limestone neutralization of acid waters in fixed bed reactors. The role of diffusion is recognized and the assumption is made that the rate of dissolution of limestone is proportional to both the hydrogen ion concentration in the liquid bulk and the solid‐liquid interface area.