11 resultados para 291601 Arithmetic and Logic Structures
em AMS Tesi di Dottorato - Alm@DL - Università di Bologna
Resumo:
Multidetector row computed tomography over the last decade is commonly used in veterinary medicine. This new technology has an increased spatial and temporal resolution, could evaluate wider scanning range in shorter scanning time, providing an advanced imaging modality. Computed tomography angiographic studies are commonly used in veterinary medicine in order to evaluate vascular structures of the abdomen and the thorax. Pulmonary pathology in feline patients is a very common condition and usually is further evaluating with computed tomography. Up to date few references of the normal computed tomographic aspects of the feline thorax are reported. In this study a computed tomographic pulmonary angiography (CTPA) protocol is reported in normal cats and is compared with the up to date anatomical references. A CTPA protocol using a 64 MDCT in our study achieved high resolution images of the pulmonary arteries, pulmonary veins and bronchial lumen till the level of minor segmental branches. Feline pulmonary bronchial parenchyma demonstrates an architecture of mixed type with a monopedial model observed in the most anatomical parts and the dichotomic aspect is seen at the accessory lobe. The arterial and venous architecture is similar to the bronchial. Statistical analysis demonstrates the linear correlation of tracheal diameter to the felines weight. Vascular variations were noticed. The pulmonary venous system enters into the left atrium through three ostia (left cranial ostia: consisted of the anastomosis of the cranial and caudal portion of the left cranial pulmonary vein; right ostia: consisted of the anastomosis of the right cranial and middle pulmonary vein; and the caudal ostia: consisted of the anastomosis of the right and left caudal pulmonary vein). In conclusion CTPA is applicable in feline patients and provides an excellent imaging of the pulmonary arterial, venous and bronchial system till the level of minor segmental branches.
Resumo:
Many combinatorial problems coming from the real world may not have a clear and well defined structure, typically being dirtied by side constraints, or being composed of two or more sub-problems, usually not disjoint. Such problems are not suitable to be solved with pure approaches based on a single programming paradigm, because a paradigm that can effectively face a problem characteristic may behave inefficiently when facing other characteristics. In these cases, modelling the problem using different programming techniques, trying to ”take the best” from each technique, can produce solvers that largely dominate pure approaches. We demonstrate the effectiveness of hybridization and we discuss about different hybridization techniques by analyzing two classes of problems with particular structures, exploiting Constraint Programming and Integer Linear Programming solving tools and Algorithm Portfolios and Logic Based Benders Decomposition as integration and hybridization frameworks.
Resumo:
This thesis deals with two important research aspects concerning radio frequency (RF) microresonators and switches. First, a new approach for compact modeling and simulation of these devices is presented. Then, a combined process flow for their simultaneous fabrication on a SOI substrate is proposed. Compact models for microresonators and switches are extracted by applying mathematical model order reduction (MOR) to the devices finite element (FE) description in ANSYS c° . The behaviour of these devices includes forms of nonlinearities. However, an approximation in the creation of the FE model is introduced, which enables the use of linear model order reduction. Microresonators are modeled with the introduction of transducer elements, which allow for direct coupling of the electrical and mechanical domain. The coupled system element matrices are linearized around an operating point and reduced. The resulting macromodel is valid for small signal analysis around the bias point, such as harmonic pre-stressed analysis. This is extremely useful for characterizing the frequency response of resonators. Compact modelling of switches preserves the nonlinearity of the device behaviour. Nonlinear reduced order models are obtained by reducing the number of nonlinearities in the system and handling them as input to the system. In this way, the system can be reduced using linear MOR techniques and nonlinearities are introduced directly in the reduced order model. The reduction of the number of system nonlinearities implies the approximation of all distributed forces in the model with lumped forces. Both for microresonators and switches, a procedure for matrices extraction has been developed so that reduced order models include the effects of electrical and mechanical pre-stress. The extraction process is fast and can be done automatically from ANSYS binary files. The method has been applied for the simulation of several devices both at devices and circuit level. Simulation results have been compared with full model simulations, and, when available, experimental data. Reduced order models have proven to conserve the accuracy of finite element method and to give a good description of the overall device behaviour, despite the introduced approximations. In addition, simulation is very fast, both at device and circuit level. A combined process-flow for the integrated fabrication of microresonators and switches has been defined. For this purpose, two processes that are optimized for the independent fabrication of these devices are merged. The major advantage of this process is the possibility to create on-chip circuit blocks that include both microresonators and switches. An application is, for example, aswitched filter bank for wireless transceiver. The process for microresonators fabrication is characterized by the use of silicon on insulator (SOI) wafers and on a deep reactive ion etching (DRIE) step for the creation of the vibrating structures in single-crystal silicon and the use of a sacrificial oxide layer for the definition of resonator to electrode distance. The fabrication of switches is characterized by the use of two different conductive layers for the definition of the actuation electrodes and by the use of a photoresist as a sacrificial layer for the creation of the suspended structure. Both processes have a gold electroplating step, for the creation of the resonators electrodes, transmission lines and suspended structures. The combined process flow is designed such that it conserves the basic properties of the original processes. Neither the performance of the resonators nor the performance of the switches results affected by the simultaneous fabrication. Moreover, common fabrication steps are shared, which allows for cheaper and faster fabrication.
Resumo:
Reasoning under uncertainty is a human capacity that in software system is necessary and often hidden. Argumentation theory and logic make explicit non-monotonic information in order to enable automatic forms of reasoning under uncertainty. In human organization Distributed Cognition and Activity Theory explain how artifacts are fundamental in all cognitive process. Then, in this thesis we search to understand the use of cognitive artifacts in an new argumentation framework for an agent-based artificial society.
Resumo:
I Max Bill is an intense giornata of a big fresco. An analysis of the main social, artistic and cultural events throughout the twentieth century is needed in order to trace his career through his masterpieces and architectures. Some of the faces of this hypothetical mural painting are, among others, Le Corbusier, Walter Gropius, Ernesto Nathan Rogers, Kandinskij, Klee, Mondrian, Vatongerloo, Ignazio Silone, while the backcloth is given by artistic avant-gardes, Bauhaus, International Exhibitions, CIAM, war events, reconstruction, Milan Triennali, Venice Biennali, the School of Ulm. Architect, even though more known as painter, sculptor, designer and graphic artist, Max Bill attends the Bauhaus as a student in the years 1927-1929, and from this experience derives the main features of a rational, objective, constructive and non figurative art. His research is devoted to give his art a scientific methodology: each work proceeds from the analysis of a problem to the logical and always verifiable solution of the same problem. By means of composition elements (such as rhythm, seriality, theme and its variation, harmony and dissonance), he faces, with consistent results, themes apparently very distant from each other as the project for the H.f.G. or the design for a font. Mathematics are a constant reference frame as field of certainties, order, objectivity: ‘for Bill mathematics are never confined to a simple function: they represent a climate of spiritual certainties, and also the theme of non attempted in its purest state, objectivity of the sign and of the geometrical place, and at the same time restlessness of the infinity: Limited and Unlimited ’. In almost sixty years of activity, experiencing all artistic fields, Max Bill works, projects, designs, holds conferences and exhibitions in Europe, Asia and Americas, confronting himself with the most influencing personalities of the twentieth century. In such a vast scenery, the need to limit the investigation field combined with the necessity to address and analyse the unpublished and original aspect of Bill’s relations with Italy. The original contribution of the present research regards this particular ‘geographic delimitation’; in particular, beyond the deep cultural exchanges between Bill and a series of Milanese architects, most of all with Rogers, two main projects have been addressed: the realtà nuova at Milan Triennale in 1947, and the Contemporary Art Museum in Florence in 1980. It is important to note that these projects have not been previously investigated, and the former never appears in the sources either. These works, together with the most well-known ones, such as the projects for the VI and IX Triennale, and the Swiss pavilion for the Biennale, add important details to the reference frame of the relations which took place between Zurich and Milan. Most of the occasions for exchanges took part in between the Thirties and the Fifties, years during which Bill underwent a significant period of artistic growth. He meets the Swiss progressive architects and the Paris artists from the Abstraction-Création movement, enters the CIAM, collaborates with Le Corbusier to the third volume of his Complete Works, and in Milan he works and gets confronted with the events related to post-war reconstruction. In these years Bill defines his own working methodology, attaining an artistic maturity in his work. The present research investigates the mentioned time period, despite some necessary exceptions. II The official Max Bill bibliography is naturally wide, including spreading works along with ones more devoted to analytical investigation, mainly written in German and often translated into French and English (Max Bill himself published his works in three languages). Few works have been published in Italian and, excluding the catalogue of the Parma exhibition from 1977, they cannot be considered comprehensive. Many publications are exhibition catalogues, some of which include essays written by Max Bill himself, some others bring Bill’s comments in a educational-pedagogical approach, to accompany the observer towards a full understanding of the composition processes of his art works. Bill also left a great amount of theoretical speculations to encourage a critical reading of his works in the form of books edited or written by him, and essays published in ‘Werk’, magazine of the Swiss Werkbund, and other international reviews, among which Domus and Casabella. These three reviews have been important tools of analysis, since they include tracks of some of Max Bill’s architectural works. The architectural aspect is less investigated than the plastic and pictorial ones in all the main reference manuals on the subject: Benevolo, Tafuri and Dal Co, Frampton, Allenspach consider Max Bill as an artist proceeding in his work from Bauhaus in the Ulm experience . A first filing of his works was published in 2004 in the monographic issue of the Spanish magazine 2G, together with critical essays by Karin Gimmi, Stanislaus von Moos, Arthur Rüegg and Hans Frei, and in ‘Konkrete Architektur?’, again by Hans Frei. Moreover, the monographic essay on the Atelier Haus building by Arthur Rüegg from 1997, and the DPA 17 issue of the Catalonia Polytechnic with contributions of Carlos Martì, Bruno Reichlin and Ton Salvadò, the latter publication concentrating on a few Bill’s themes and architectures. An urge to studying and going in depth in Max Bill’s works was marked in 2008 by the centenary of his birth and by a recent rediscovery of Bill as initiator of the ‘minimalist’ tradition in Swiss architecture. Bill’s heirs are both very active in promoting exhibitions, researching and publishing. Jakob Bill, Max Bill’s son and painter himself, recently published a work on Bill’s experience in Bauhaus, and earlier on he had published an in-depth study on ‘Endless Ribbons’ sculptures. Angela Thomas Schmid, Bill’s wife and art historian, published in end 2008 the first volume of a biography on Max Bill and, together with the film maker Eric Schmid, produced a documentary film which was also presented at the last Locarno Film Festival. Both biography and documentary concentrate on Max Bill’s political involvement, from antifascism and 1968 protest movements to Bill experiences as Zurich Municipality councilman and member of the Swiss Confederation Parliament. In the present research, the bibliography includes also direct sources, such as interviews and original materials in the form of letters correspondence and graphic works together with related essays, kept in the max+binia+jakob bill stiftung archive in Zurich. III The results of the present research are organized into four main chapters, each of them subdivided into four parts. The first chapter concentrates on the research field, reasons, tools and methodologies employed, whereas the second one consists of a short biographical note organized by topics, introducing the subject of the research. The third chapter, which includes unpublished events, traces the historical and cultural frame with particular reference to the relations between Max Bill and the Italian scene, especially Milan and the architects Rogers and Baldessari around the Fifties, searching the themes and the keys for interpretation of Bill’s architectures and investigating the critical debate on the reviews and the plastic survey through sculpture. The fourth and last chapter examines four main architectures chosen on a geographical basis, all devoted to exhibition spaces, investigating Max Bill’s composition process related to the pictorial field. Paintings has surely been easier and faster to investigate and verify than the building field. A doctoral thesis discussed in Lausanne in 1977 investigating Max Bill’s plastic and pictorial works, provided a series of devices which were corrected and adapted for the definition of the interpretation grid for the composition structures of Bill’s main architectures. Four different tools are employed in the investigation of each work: a context analysis related to chapter three results; a specific theoretical essay by Max Bill briefly explaining his main theses, even though not directly linked to the very same work of art considered; the interpretation grid for the composition themes derived from a related pictorial work; the architecture drawing and digital three-dimensional model. The double analysis of the architectural and pictorial fields is functional to underlining the relation among the different elements of the composition process; the two fields, however, cannot be compared and they stay, in Max Bill’s works as in the present research, interdependent though self-sufficient. IV An important aspect of Max Bill production is self-referentiality: talking of Max Bill, also through Max Bill, as a need for coherence instead of a method limitation. Ernesto Nathan Rogers describes Bill as the last humanist, and his horizon is the known world but, as the ‘Concrete Art’ of which he is one of the main representatives, his production justifies itself: Max Bill not only found a method, but he autonomously re-wrote the ‘rules of the game’, derived timeless theoretical principles and verified them through a rich and interdisciplinary artistic production. The most recurrent words in the present research work are synthesis, unity, space and logic. These terms are part of Max Bill’s vocabulary and can be referred to his works. Similarly, graphic settings or analytical schemes in this research text referring to or commenting Bill’s architectural projects were drawn up keeping in mind the concise precision of his architectural design. As for Mies van der Rohe, it has been written that Max Bill took art to ‘zero degree’ reaching in this way a high complexity. His works are a synthesis of art: they conceptually encompass all previous and –considered their developments- most of contemporary pictures. Contents and message are generally explicitly declared in the title or in Bill’s essays on his artistic works and architectural projects: the beneficiary is invited to go through and re-build the process of synthesis generating the shape. In the course of the interview with the Milan artist Getulio Alviani, he tells how he would not write more than a page for an essay on Josef Albers: everything was already evident ‘on the surface’ and any additional sentence would be redundant. Two years after that interview, these pages attempt to decompose and single out the elements and processes connected with some of Max Bill’s works which, for their own origin, already contain all possible explanations and interpretations. The formal reduction in favour of contents maximization is, perhaps, Max Bill’s main lesson.
Resumo:
The present work tries to display a comprehensive and comparative study of the different legal and regulatory problems involved in international securitization transactions. First, an introduction to securitization is provided, with the basic elements of the transaction, followed by the different varieties of it, including dynamic securitization and synthetic securitization structures. Together with this introduction to the intricacies of the structure, a insight into the influence of securitization in the financial and economic crisis of 2007-2009 is provided too; as well as an overview of the process of regulatory competition and cooperation that constitutes the framework for the international aspects of securitization. The next Chapter focuses on the aspects that constitute the foundations of structured finance: the inception of the vehicle, and the transfer of risks associated to the securitized assets, with particular emphasis on the validity of those elements, and how a securitization transaction could be threatened at its root. In this sense, special importance is given to the validity of the trust as an instrument of finance, to the assignment of future receivables or receivables in block, and to the importance of formalities for the validity of corporations, trusts, assignments, etc., and the interaction of such formalities contained in general corporate, trust and assignment law with those contemplated under specific securitization regulations. Then, the next Chapter (III) focuses on creditor protection aspects. As such, we provide some insights on the debate on the capital structure of the firm, and its inadequacy to assess the financial soundness problems inherent to securitization. Then, we proceed to analyze the importance of rules on creditor protection in the context of securitization. The corollary is in the rules in case of insolvency. In this sense, we divide the cases where a party involved in the transaction goes bankrupt, from those where the transaction itself collapses. Finally, we focus on the scenario where a substance over form analysis may compromise some of the elements of the structure (notably the limited liability of the sponsor, and/or the transfer of assets) by means of veil piercing, substantive consolidation, or recharacterization theories. Once these elements have been covered, the next Chapters focus on the regulatory aspects involved in the transaction. Chapter IV is more referred to “market” regulations, i.e. those concerned with information disclosure and other rules (appointment of the indenture trustee, and elaboration of a rating by a rating agency) concerning the offering of asset-backed securities to the public. Chapter V, on the other hand, focuses on “prudential” regulation of the entity entrusted with securitizing assets (the so-called Special Purpose vehicle), and other entities involved in the process. Regarding the SPV, a reference is made to licensing requirements, restriction of activities and governance structures to prevent abuses. Regarding the sponsor of the transaction, a focus is made on provisions on sound originating practices, and the servicing function. Finally, we study accounting and banking regulations, including the Basel I and Basel II Frameworks, which determine the consolidation of the SPV, and the de-recognition of the securitized asset from the originating company’s balance-sheet, as well as the posterior treatment of those assets, in particular by banks. Chapters VI-IX are concerned with liability matters. Chapter VI is an introduction to the different sources of liability. Chapter VII focuses on the liability by the SPV and its management for the information supplied to investors, the management of the asset pool, and the breach of loyalty (or fiduciary) duties. Chapter VIII rather refers to the liability of the originator as a result of such information and statements, but also as a result of inadequate and reckless originating or servicing practices. Chapter IX finally focuses on third parties entrusted with the soundness of the transaction towards the market, the so-called gatekeepers. In this respect, we make special emphasis on the liability of indenture trustees, underwriters and rating agencies. Chapters X and XI focus on the international aspects of securitization. Chapter X contains a conflicts of laws analysis of the different aspects of structured finance. In this respect, a study is made of the laws applicable to the vehicle, to the transfer of risks (either by assignment or by means of derivatives contracts), to liability issues; and a study is also made of the competent jurisdiction (and applicable law) in bankruptcy cases; as well as in cases where a substance-over-form is performed. Then, special attention is also devoted to the role of financial and securities regulations; as well as to their territorial limits, and extraterritoriality problems involved. Chapter XI supplements the prior Chapter, for it analyzes the limits to the States’ exercise of regulatory power by the personal and “market” freedoms included in the US Constitution or the EU Treaties. A reference is also made to the (still insufficient) rules from the WTO Framework, and their significance to the States’ recognition and regulation of securitization transactions.
Resumo:
The present Thesis studies three alternative solvent groups as sustainable replacement of traditional organic solvents. Some aspects of fluorinated solvents, supercritical fluids and ionic liquids, have been analysed with a critical approach and their effective “greenness” has been evaluated from the points of view of the synthesis, the properties and the applications. In particular, the attention has been put on the environmental and human health issues, evaluating the eco-toxicity, the toxicity and the persistence, to underline that applicability and sustainability are subjects with equal importance. The “green” features of fluorous solvents and supercritical fluids are almost well-established; in particular supercritical carbon dioxide (scCO2) is probably the “greenest” solvent among the alternative solvent systems developed in the last years, enabling to combine numerous advantages both from the point of view of industrial/technological applications and eco-compatibility. In the Thesis the analysis of these two classes of alternative solvents has been mainly focused on their applicability, rather than the evaluation of their environmental impact. Specifically they have been evaluated as alternative media for non-aqueous biocatalysis. For this purpose, the hydrophobic ion pairing (HIP), which allows solubilising enzymes in apolar solvents by an ion pairing between the protein and a surfactant, has been investigated as effective enzymatic derivatisation technique to improve the catalytic activity under homogeneous conditions in non conventional media. The results showed that the complex enzyme-surfactant was much more active both in fluorous solvents and in supercritical carbon dioxide than the native form of the enzyme. Ionic liquids, especially imidazolium salts, have been proposed some years ago as “fully green” alternative solvents; however this epithet does not take into account several “brown” aspects such as their synthesis from petro-chemical starting materials, their considerable eco-toxicity, toxicity and resistance to biodegradation, and the difficulty of clearly outline applications in which ionic liquids are really more advantageous than traditional solvents. For all of these reasons in this Thesis a critical analysis of ionic liquids has been focused on three main topics: i) alternative synthesis by introducing structural moieties which could reduce the toxicity of the most known liquid salts, and by using starting materials from renewable resources; ii) on the evaluation of their environmental impact through eco-toxicological tests (Daphnia magna and Vibrio fischeri acute toxicity tests, and algal growth inhibition), toxicity tests (MTT test, AChE inhibition and LDH release tests) and fate and rate of aerobic biodegradation in soil and water; iii) and on the demonstration of their effectiveness as reaction media in organo-catalysis and as extractive solvents in the recovery of vegetable oil from terrestrial and aquatic biomass. The results about eco-toxicity tests with Daphnia magna, Vibrio fischeri and algae, and toxicity assay using cultured cell lines, clearly indicate that the difference in toxicity between alkyl and oxygenated cations relies in differences of polarity, according to the general trend of decreasing toxicity by decreasing the lipophilicity. Independently by the biological approach in fact, all the results are in agreement, showing a lower toxicity for compounds with oxygenated lateral chains than for those having purely alkyl lateral chains. These findings indicate that an appropriate choice of cation and anion structures is important not only to design the IL with improved and suitable chemico-physical properties but also to obtain safer and eco-friendly ILs. Moreover there is a clear indication that the composition of the abiotic environment has to be taken into account when the toxicity of ILs in various biological test systems is analysed, because, for example, the data reported in the Thesis indicate a significant influence of salinity variations on algal toxicity. Aerobic biodegradation of four imidazolium ionic liquids, two alkylated and two oxygenated, in soil was evaluated for the first time. Alkyl ionic liquids were shown to be biodegradable over the 6 months test period, and in contrast no significant mineralisation was observed with oxygenated derivatives. A different result was observed in the aerobic biodegradation of alkylated and oxygenated pyridinium ionic liquids in water because all the ionic liquids were almost completely degraded after 10 days, independently by the number of oxygen in the lateral chain of the cation. The synthesis of new ionic liquids by using renewable feedstock as starting materials, has been developed through the synthesis of furan-based ion pairs from furfural. The new ammonium salts were synthesised in very good yields, good purity of the products and wide versatility, combining low melting points with high decomposition temperatures and reduced viscosities. Regarding the possible applications as surfactants and biocides, furan-based salts could be a valuable alternative to benzyltributylammonium salts and benzalkonium chloride that are produced from non-renewable resources. A new procedure for the allylation of ketones and aldehydes with tetraallyltin in ionic liquids was developed. The reaction afforded high yields both in sulfonate-containing ILs and in ILs without sulfonate upon addition of a small amount of sulfonic acid. The checked reaction resulted in peculiar chemoselectivity favouring aliphatic substrates towards aromatic ketones and good stereoselectivity in the allylation of levoglucosenone. Finally ILs-based systems could be easily and successfully recycled, making the described procedure environmentally benign. The potential role of switchable polarity solvents as a green technology for the extraction of vegetable oil from terrestrial and aquatic biomass has been investigated. The extraction efficiency of terrestrial biomass rich in triacylglycerols, as soy bean flakes and sunflower seeds, was comparable to those of traditional organic solvents, being the yield of vegetable oils recovery very similar. Switchable polarity solvents as been also exploited for the first time in the extraction of hydrocarbons from the microalga Botryococcus braunii, demonstrating the efficiency of the process for the extraction of both dried microalgal biomass and directly of the aqueous growth medium. The switchable polarity solvents exhibited better extraction efficiency than conventional solvents, both with dried and liquid samples. This is an important issue considering that the harvest and the dewatering of algal biomass have a large impact on overall costs and energy balance.
Resumo:
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.
Resumo:
The study defines a new farm classification and identifies the arable land management. These aspects and several indicators are taken into account to estimate the sustainability level of farms, for organic and conventional regimes. The data source is Italian Farm Account Data Network (RICA) for years 2007-2011, which samples structural and economical information. An environmental data has been added to the previous one to better describe the farm context. The new farm classification describes holding by general informations and farm structure. The general information are: adopted regime and farm location in terms of administrative region, slope and phyto-climatic zone. The farm structures describe the presence of main productive processes and land covers, which are recorded by FADN database. The farms, grouped by homogeneous farm structure or farm typology, are evaluated in terms of sustainability. The farm model MAD has been used to estimate a list of indicators. They describe especially environmental and economical areas of sustainability. Finally arable lands are taken into account to identify arable land managements and crop rotations. Each arable land has been classified by crop pattern. Then crop rotation management has been analysed by spatial and temporal approaches. The analysis reports a high variability inside regimes. The farm structure influences indicators level more than regimes, and it is not always possible to compare the two regimes. However some differences between organic and conventional agriculture have been found. Organic farm structures report different frequency and geographical location than conventional ones. Also different connections among arable lands and farm structures have been identified.
Resumo:
Top1-DNA cleavage complexes (Top1ccs) trigger an accumulation of antisense RNAPII transcripts specifically at active divergent CpG-island promoters in a replication independent and Top1 dependent manner, leading to transcription-dependent genome instability and altered transcription regulation. Using different cancer cell lines of colon and osteo origins, we show that they display different sensitivity to CPT and G4 binder that is independent from Top1 level. To look at the interactions between Top1 and G4, we show that co-treatment with G4 binders potentiate the cell cytotoxicity of CPT regardless of the treatment sequences. Potentiation is indicated by a reduced inhibition concentration (IC50) with a more profound cytotoxicity in CPT-resistant cell lines, HCT15 and U2OS, hence, indicating an interaction between Top1inhibitor and G4 binders. Moreover, computational analysis confirmed the present of G4 motifs in genes with CPT-induced antisense transcription. G4 motifs are present mostly 5000 bp upstream from transcription start site and notably lower in genes. Comparisons between genes with no antisense transcription and genes with antisense transcription show that G4 motifs in this region are notably lower in the genes with antisense transcripts. Since CPT increases negative supercoils at promoters of intermediate activity, the formation of G4 is also increased in CPT-treated cells. Suprisingly, formation of G4 is regulated in parallel to the transient stabilization of R-loops, indicating a role in response to CPT-induced stress. G4 formation is highly elevated in Pyridostatin treated cells, which previous study shows increased formation of γH2Ax foci. This effect is also seen in the CPT-resistant cell lines, HCT15, indicating that the formation is a general event in response to CPT. We also show that R-loop formation is greatly increased in Pyridostatin treated cells. In order to study the role of R-loops and G4 structures in Top1cc-dependant repair pathway, we inhibited tyrosyl-phosphodiestrase 1 (TDP-1) using a TDP-1 inhibitor.
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Organic molecular semiconductors are subject of intense research for their crucial role as key components of new generation low cost, flexible, and large area electronic devices such as displays, thin-film transistors, solar cells, sensors and logic circuits. In particular, small molecular thienoimide (TI) based materials are emerging as novel multifunctional materials combining a good processability together to ambipolar or n-type charge transport and electroluminescence at the solid state, thus enabling the fabrication of integrated devices like organic field effect transistors (OFETs) and light emitting transistor (OLETs). Given this peculiar combination of characteristics, they also constitute the ideal substrates for fundamental studies on the structure-property relationships in multifunctional molecular systems. In this scenario, this thesis work is focused on the synthesis of new thienoimide based materials with tunable optical, packing, morphology, charge transport and electroluminescence properties by following a fine molecular tailoring, thus optimizing their performances in device as well as investigating and enabling new applications. Investigation on their structure-property relationships has been carried out and in particular, the effect of different π-conjugated cores (heterocycles, length) and alkyl end chain (shape, length) changes have been studied, obtaining materials with enhanced electron transport capability end electroluminescence suitable for the realization of OFETs and single layer OLETs. Moreover, control on the polymorphic behaviour characterizing thienoimide materials has been reached by synthetic and post-synthetic methodologies, developing multifunctional materials from a single polymorphic compound. Finally, with the aim of synthesizing highly pure materials, simplifying the purification steps and avoiding organometallic residues, procedures based on direct arylation reactions replacing conventional cross-couplings have been investigated and applied to different classes of molecules, bearing thienoimidic core or ends, as well as thiophene and anthracene derivatives, validating this approach as a clean alternative for the synthesis of several molecular materials.