Synthesis and Supramolecular Architectures of Lipophilic Derivatives of Guanine

Self-assembly relies on the association of pre-programmed building blocks through non-covalent interactions to give complex supramolecular architectures. Previous studies provided evidence for the unique self-assembly properties of semi-synthetic lipophilic guanosine derivatives which can sequestrate ions from an aqueous phase, carry them into an organic phase where they promote the generation of well-defined supramolecular assemblies. In the presence of cations lipophilic guanosines form columnar aggregates while in their absence they generate supramolecular ribbons. The aim of this thesis has been the synthesis of guanine derivatives, in particular N9-alkylated guanines and a guanosine functionalized as a perchlorotriphenylmetil moiety (Gace-a-HPTM) in order to observe their supramolecular behaviour in the absence of sugar (ribose or deoxyribose) and in the presence of a bulky and chiral substituent respectively. By using guanine instead of guanosine, while maintaining all the hydrogen bond acceptor and donor groups required for supramolecular aggregation, the steric hindrance to supramolecular aggregation is notably reduced because (i.e. guanines with groups in N9 different from sugar are expected to have a greatest conformational freedom even in presence of bulky groups in C8). Supramolecular self-assembly of these derivatives has been accomplished in solutions by NMR and CD spectroscopy and on surface by STM technique. In analogy with other guanosine derivatives, also N9-substituted guanines and GAceHPTM form either ribbon-like aggregates or cation-templated G-quartet based columnar structures.

Nanoscale-electrical and optical properties of iii-nitrides

III-nitrides are wide-band gap materials that have applications in both electronics and optoelectronic devices. Because to their inherent strong polarization properties, thermal stability and higher breakdown voltage in Al(Ga,In)N/GaN heterostructures, they have emerged as strong candidates for high power high frequency transistors. Nonetheless, the use of (Al,In)GaN/GaN in solid state lighting has already proved its success by the commercialization of light-emitting diodes and lasers in blue to UV-range. However, devices based on these heterostructures suffer problems associated to structural defects. This thesis primarily focuses on the nanoscale electrical characterization and the identification of these defects, their physical origin and their effect on the electrical and optical properties of the material. Since, these defects are nano-sized, the thesis deals with the understanding of the results obtained by nano and micro-characterization techniques such as atomic force microscopy(AFM), current-AFM, scanning kelvin probe microscopy (SKPM), electron beam induced current (EBIC) and scanning tunneling microscopy (STM). This allowed us to probe individual defects (dislocations and cracks) and unveil their electrical properties. Taking further advantage of these techniques,conduction mechanism in two-dimensional electron gas heterostructures was well understood and modeled. Secondarily, origin of photoluminescence was deeply investigated. Radiative transition related to confined electrons and photoexcited holes in 2DEG heterostructures was identified and many body effects in nitrides under strong optical excitations were comprehended.

La comunicazione chimica in Blattaria: contributo al miglioramento della lotta

CHEMICAL COMMUNICATION IN BLATTARIA: CONTRIBUTION TO THE IMPROVEMENT OF THE CONTROL TECNIQUES The management of cockroach infestations in urban environment has undergone some changes in recent years by moving to the predominant use of baits, thanks to the awareness of the risks connected with the use of spray insecticides. The effectiveness of a bait is determined by the collective performance of its components, including active and inert ingredients, the food attractant and any other attractive odour. This research has focused on the behavioral responses of Italian sinanthropic cockroaches to semiochemicals and food attractants, for the purpose of evaluating a possible practical application and of contributing to the improvement of control techniques. Behavioral and morphological studies have been carried out on Supella longipalpa (F.), a small cockroach that is spreading in Italy. Behavioral assays showed that the fourth and fifth tergites of females are significantly more attractive than other region of the body. Cuticular pores and ducts ending in glandular structures (observed with a S.E.M. = Scanning Electron Microscope) are present in large number on these tergites, suggesting that they could be involved in the production and the release of sexual pheromone. Cockroaches produce an aggregation pheromone that is excreted along with their frass and that consists of volatile and non-volatile compounds, mainly amines and steroidal glycosides. The effectiveness of faecal extracts obtained from excrements of Blattella germanica (L.), Blatta orientalis L., Periplaneta americana (L.) and S. longipalpa was evaluated, both at intraspecific and interspecific level, using a "Y" tube olfactometer. Bioassays showed that faecal extracts obtained with methanol have a good intraspecific attractiveness and, in some cases, they showed also interspecific behavioral responses. A gel was prepared, having physical characteristics that could give a good resistance to dehydration, as a potential basis for a new bait; the gel was then added faecal extracts, obtained with methanol from B. germanica and S. longipalpa frass. Arena-tests showed that the new gel containing faecal extracts is more attractive than some commercial gel formulations used as comparison: it was the only product that could attract 100% of insects placed in the arenas in 4-5 days. In conclusion, the substances involved in chemical communication of Blattaria may be able to effectively increase the attractiveness of products for monitoring and controlling cockroaches.

Ruolo dei glicosaminoglicani su struttura e funzione dei crimps nei tendini e nei legamenti

The biomechanical roles of both tendons and ligaments are fulfilled by extracellular matrix of these tissues. In particular, tension is mainly transmitted and resisted by fibrous proteins (collagen, elastin), whereas compressive load is absorbed by water-soluble glycosaminoglycans (GAGs). GAGs spanning the interfibrillar spaces and interacting with fibrils also seem to play a part in transmitting and resisting tensile stresses. Apart from different functional roles and collagen array, tendons and ligaments share the same basic structure showing periodic undulations of collagen fibers or crimps. Each crimp is composed of many knots of each single fibril or fibrillar crimps. Fibrillar and fiber crimps act as shock absorbers during the initial elongation of both tendons and ligaments and assist the elastic recoil of fibrils and fibers when the tensile stress is removed. The aim of this thesis was to evaluate whether GAGs directly affect the 3D microstructural integrity of fibrillar crimp and fiber crimps in both tendons and ligaments. Achilles tendons and medial collateral ligaments of the knee from eight female Sprague-Dawley rats (90 days old) were digested with chondroitinase ABC to remove GAGs and observed under a scanning electron microscope (SEM). In addition, isolated fibrils from these tissues obtained by mechanical homogenization were analyzed by a transmission electron microscope (TEM). Both samples digested with chondroitinase ABC or mechanically disrupted still showed crimps and fibrillar crimps comparable to tissues with a normal GAGs content. All fibrils in the fibrillar crimp region always twisted leftwards, thus changing their running plane, and then sharply bent, changing their course on a new plane. These data suggest that GAGs do not affect structural integrity or fibrillar crimps functions that seem mainly related to the local fibril leftward twisting and the alternating handedness of collagen from a molecular to a supramolecular level.

Advanced SPM studies on the growth of ultrathin films of organic semiconductors at metal and dielectric interfaces

Many studies on the morphology, molecular orientation, device performance, substrate nature and growth parameter dependence have been carried out since the proposal of Sexithiophene (6T) for organic electronics [ ] However, these studies were mostly performed on films thicker than 20nm and without specifically addressing the relationship between morphology and molecular orientation within the nano and micro structures of ultrathin films of 0-3 monolayers. In 2004, the observation that in OFETs only the first few monolayers at the interface in contact with the gate insulator contribute to the charge transport [ ], underlined the importance to study submonolayer films and their evolution up to a few monolayers of thickness with appropriate experimental techniques. We present here a detailed Non-contact Atomic Force Microscopy and Scanning Tunneling Microscopy study on various substrates aiming at the investigation of growth mechanisms. Most reported similar studies are performed on ideal metals in UHV. However it is important to investigate the details of organic film growth on less ideal and even technological surfaces and device testpatterns. The present work addresses the growth of ultra thin organic films in-situ and quasi real-time by NC-AFM. An organic effusion cell is installed to evaporate the organic material directly onto the SPM sample scanning stage.

Problemi di diagnostica e restauro dei materiali decorativi nell'architettura Liberty in Emilia-Romagna

Le pietre artificiali ed i cementi artistici utilizzati durante la stagione Liberty rappresentano tutt’oggi un patrimonio artistico non ancora sufficientemente studiato. In seguito ad una ricerca bibliografica su testi e riviste dei primi anni del Novecento, è stata eseguita una ricognizione del patrimonio architettonico emiliano-romagnolo, al fine di valutarne i materiali e le tipologie di degrado più diffuse. Le città e le zone oggetto di studio sono state: Bologna, Ferrara, Modena e provincia, Reggio Emilia, Parma, Firenze, la Romagna e le Marche settentrionali. Tra gli edifici individuati sono state analizzate le decorazioni e gli intonaci di tre edifici ritenuti particolarmente significativi: il villino Pennazzi (noto anche come Villa Gina) a Borgo Panigale (Bologna), villa Verde a Bologna e l’ex-albergo Dorando Pietri a Carpi. Da tali edifici sono stati selezionati campioni rappresentativi delle diverse tipologie di decorazioni in pietra artificiale e successivamente sono stati caratterizzati in laboratorio tramite diffrattometria a raggi x (XRD), termogravimetria (TGA), microscopio ottico in sezioni lucide, microscopio elettronico a scansione (SEM) e porosimetria ad intrusione di mercurio (MIP). In particolare per Villa Verde sono state formulate e caratterizzate diverse tipologie di malte variando il tipo di legante ed il rapporto acqua/cemento, al fine di garantire la compatibilità fisico-meccanica con il supporto negli interventi di risarcimento delle lacune previsti nel restauro. L’attività sperimentale svolta ha permesso di mettere a punto un vero e proprio protocollo diagnostico per il restauro di questo tipo di decorazioni che potrà essere utilizzato sia nei casi di studio analizzati che per ogni futuro intervento.

Personalization of Electronic Nicotine Delivery Systems Toxicological impact in in-vivo model

Electronic nicotine delivery systems (ENDS) use has recently grown. E-cig generates carcinogenic chemical compounds and reactive oxygen species (ROS). Carbonyls and ROS are formed when the liquid comes into contact with the heating element. In this study the chemical and biological effects of coil resistance applied on the same device were investigated. A preliminary in-vivo study the new heat-not-burn devices (IQOS®) has been conducted to evaluate the effect of the device on antioxidant biomarkers. The amount of formaldehyde, acetaldehyde, acrolein was measured by GC-MS analysis. The two e-liquids used for carbonyls detection differed only for the presence of nicotine. The nicotine-free liquid was then used for the detection of ROS in the aerosol. The impact of the non-nicotine vapor on cell viability in H1299 human lung carcinoma cells, as well as the biological effects in a rat model of e-cig aerosol exposure, were also evaluated. After the exposure of Sprague Dawley rats to e-cig and IQOS® aerosol, the effect of 28-day treatment was examined on enzymatic and non-enzymatic antioxidant response, lung inflammation, blood homeostasis and tissue damage by using scanning electron microscope (SEM) technique. The results show a significant correlation between the low resistance and the generation of higher concentrations of the selected carbonyls and ROS in aerosols. Cell viability was reduced with an inverse relation to coil resistance. The experimental model highlighted an impairment of the pulmonary antioxidant and detoxifying machinery. Frames from SEM show disorganization of alveolar and bronchial epithelium. IQOS® exposed animals shows a significant production of ROS related to the unbalance of antioxidant defense and alteration of macromolecule integrity. This research demonstrates how several toxicological aspects can potentially occur in e-cig consumers who use low resistance device coupled with nicotine-free liquid. ENDS may expose users to hazardous compounds, which, may promote chronic pathologies and degenerative diseases.

Integration of by-products and waste from agri-food supply chains into the «water-energy-food» nexus (RECOW-ER): the role of fungi

The agricultural sector is undoubtedly one of the sectors that has the greatest impact on the use of water and energy to produce food. The circular economy allows to reduce waste, obtaining maximum value from products and materials, through the extraction of all possible by-products from resources. Circular economy principles for agriculture include recycling, processing, and reusing agricultural waste in order to produce bioenergy, nutrients, and biofertilizers. Since agro-industrial wastes are principally composed of lignin, cellulose, and hemicellulose they can represent a suitable substrate for mushroom growth and cultivation. Mushrooms are also considered healthy foods with several medicinal properties. The thesis is structured in seven chapters. In the first chapter an introduction on the water, energy, food nexus, on agro-industrial wastes and on how they can be used for mushroom cultivation is given. Chapter 2 details the aims of this dissertation thesis. In chapters three and four, corn digestate and hazelnut shells were successfully used for mushroom cultivation and their lignocellulosic degradation capacity were assessed by using ATR-FTIR spectroscopy. In chapter five, through the use of the Surface-enhanced Raman Scattering (SERS) spectroscopy was possible to set-up a new method for studying mushroom composition and for identifying different mushroom species based on their spectrum. In chapter six, the isolation of different strains of fungi from plastic residues collected in the fields and the ability of these strains to growth and colonizing the Low-density Polyethylene (LDPE) were explored. The structural modifications of the LDPE, by the most efficient fungal strain, Cladosporium cladosporioides Clc/1 strain were monitored by using the Scanning Electron Microscope (SEM) and ATR-FTIR spectroscopy. Finally, chapter seven outlines the conclusions and some hints for future works and applications are provided.