Les mastics polysulfures sont très utilisés dans l'aéronautique, ceci grâce à leur bonne tenue au froid et leur résistance au carburant. La plupart d'entre eux sont des bicomposants (un polymère polysulfure et un durcisseur avec éventuellement un catalyseur dans l'un des composants). Les formulations de mastic, réticulé au MnO2, permettent d'avoir des temps de gel de 2 jours, avec une réticulation complète au bout de 70 jours. Cependant, ce temps de gel long induit un temps de réticulation trop long. Ainsi, l'objectif de cette thèse était de créer un nouveau type de mastic, qui serait idéalement monocomposant avec un temps de gel toujours long, voir infini et qui réagirait sur demande après stimulus avec un temps de réticulation court. C'est ce qui est appelé le concept SCOD (sealant cure on demand). Pour cela, il faut bloquer un des trois réactifs, et que celui-ci soit déblocable sur demande à l'aide d'un stimulus simple industriellement tel que la température (cible entre 60-80°C). Le concept de blocage choisi est la réaction de Diels-Alder sur des composés accepteurs de Michaël. En effet, cette réaction est réversible et la cycloréversion permet la déprotection de la double liaison réactive. Après déblocage, l'accepteur de Michaël peut réagir avec le polysulfure. Une première étude, sur les accepteurs de Michaël, a permis de déterminer que les fonctions maléimides, en présence de DABCO, donnent les meilleures cinétiques pour la réaction avec les thiols du polysulfure. Une deuxième étude, sur la réaction de Diels-Alder et rétroDiels-Alder, a prouvé la faisabilité du projet et a permis de sélectionner les dérivés du furane comme agents bloquants pour répondre à la fourchette de température imposée. Ensuite, des durcisseurs polymaléimides aliphatiques ont été synthétisés à l'aide des Jeffamines® d'Huntsman et bloqués avec le furfuryl acétate, afin d'être utilisés pour la création de matériaux suivant le concept SCOD. Le temps de gel obtenu avec les durcisseurs bloqués, était de 7 jours et un matériau était obtenu après 17 heures de chauffe. Le concept SCOD a donc été démontré. Cette étude a, ensuite, été extrapolée au Centre de Recherche d'Hutchinson en formulation modèle sur de plus grandes quantités. Aussi, les propriétés des mastics obtenus ont été déterminées et répondaient à une majorité des critères du cahier des charges.. Le déblocage a été amélioré après ajout d'un thiol tétrafonctionnel (PETMA, co-agent) et l'utilisation d'un autre catalyseur (DBU), Le temps de déblocage étant encore trop long et le bloquant, relargué dans la formulation, forme des porosités dans le mastic et dégrade, de fait, les propriétés de celui-ci. Ainsi une dernière partie d'amélioration a été effectuée. En effet, dans celle-ci, une nouvelle génération de durcisseur, cette fois-ci aromatique, et d'agent bloquant, jouant le rôle de plastifiant non volatil, a été créée et testée en laboratoire. Ceux-ci ont présenté de très bons résultats préliminaires avec des temps de déprotection plus courts et des bloquants moins volatils à la température de déblocage comparé au furfuryl acétate. L'extrapolation doit se poursuivre fin 2014-début 2015 sur ces nouveaux durcisseurs en formulation mastic modèle. / Polysulfide sealants are widely used in aviation because of their good resistance to low temperature and to fuels. Most of them are bycomponent (a polysulfide polymer and a crosslinking agent and, eventually a curing catalyst in one of them). These sealant formulations, crosslinked with MnO2, have a gel time of two days, with a full curing after 70 days. However, because of this short gel time, the curing time is too long. Thus, the objective of this thesis was to create a new type of sealant, monocomponent, with still a long gel time, ideally infinite, that could react on demand after stimulus, in order to have a short curing time. This concept is called SCOD concept (sealant cure on demand). These criteria require to block one of the three products, and this one should be unblocked on demand using an ease stimulus such as temperature. The system chosen as blocking principle is the Diels-Alder reaction of a Michaël acceptor. Indeed, this reaction is reversible and the cycloreversion allows to unprotect the reactive double bond. After the unblocking reaction, the Michaël acceptor may react with the polysulfide. A primary study, on Michael acceptors, allowed to determine that maleimide function, in the presence of triethylamine, gives the best kinetics for reaction with polysulfide's thiol. A second study, this time on the Diels-Alder and retroDiels-Alder reaction, proved the feasibility of the project and allowed to select furan derivatives as blocking agents. Then, aliphatic polymaleimides hardeners were synthesized using Huntsman's Jeffamine and were blocked with the acetate furfuryl, so as to be used for creating SCOD materials. The gel time obtained with blocked hardener was 7 days at room temperature and after heating for 17 hours, a material was obtained; the SCOD concept has been demonstrated. The study was, then, extrapolated to Hutchinson's research and development department on bigger quantities to do some basic formulation. In addition, the sealant's characteristics have been determined and have shown very interesting results. Unblocking time was improved after adding tetrafunctional thiols (co-agent) and one another catalyst (DBU). The unblocking time was too long and the blocking agent, once released into the formulation, formed porosities into the sealant and, because of it, damaged the properties of the sealant. A latter part was done to improve the SCOD concept. Two new generations of hardener, aromatic this time, and blocking agent, acting as a non-volatile plasticizer, were created and tested in laboratory. These have presented very good preliminary results. Indeed, the unblocking time is much shorter and the unblocking agent is less volatile at high temperature compare to acetate furfuryl. The scaling up to pilot level is under way (end of 2014).

Nello studio del Disturbo da Deficit di Attenzione e Iperattività (DDAI) si riconosce la multifattorialità della sua eziologia: si presuppone una componente genetica o neurobiologica e l'intervento di fattori ambientali. Il mondo familiare e scolastico sono i due sistemi in cui il bambino vive. Questi sistemi sono caratterizzati da ambienti, attività, stili educativi, ritmi di vita quotidiana, che possono essere connotati da un certo grado di disordine . Per rilevare il grado di disordine strutturale e personale della famiglia e della scuola sono stati costruiti alcuni questionari. L'indagine è stata condotta su un campione di oltre 600 soggetti, maschi e femmine, della classe 1^-3^-5^ della scuola primaria elementare.Il campione è stato reclutato in tre circoli didattici, che comprendono sei scuole del territorio metropolitano della città di Torino. Dai risultati dell'indagine si evince che i fattori del disordine strutturale e personale, familiare e scolastico, sono correlati con i deficit dell'attenzione e l'iperattività dei bambini. Alcuni fattori del disordine strutturale, dell'ambiente familiare e scolastico, come un elevato grado di disordine della casa e della classe e il caos relativo al non rispettare le attività fissate per la giornata, sono correlate con il deficit di attenzione dei bambini; il caos derivato dalla numerosità di alunni in una classe e dalla elevata presenza di allievi vivaci sono in relazione con il deficit di iperattività. Le condizioni educative incoerenti, una presenza discontinua dei genitori, troppe attività extrascolastiche, l'inadeguatezza dello stile educativo familiare e scolastico, l'atteggiamento distratto e frettoloso dei genitori sono alcuni dei fattori che fanno aumentare i livelli sia della disattenzione che della iperattività. / In the study of Attention Deficit Hyperactive Disorder (ADHD) the multifactor model of its aetiology is acknowledged. It supposes a genetic or neurobiological component and environmental factors. The family and school are the two systems in which the child lives. These systems are characterized by a different environment, activities, educational methods, daily life rhythms that can show a degree of disorder . The disorder has been evaluated using some survey questionnaires designed for this purpose. The survey questionnaires measure the degree of familiar and scholastic structural and personal disorder. The inquiry has been carried out on a sample of more than 600 subjects, males and females, of 1st, 3rd and 5th grade. The sample has been recruited in three comprehensive didactic circles of six schools of the metropolitan area of Turin. The results of data report show that the both family and school structural and personal factors are related to children's attention deficit and hyperactive disorder. Some factors of familiar and scholastic structural disorder such as a high degree of house and classroom environmental chaos and the familiar and scholastic unperformed daily activities are related to students' attention deficit. Furthermore the children's hyperactivity is related to the high amount of students in the class and the presence of lively children. The incoherent educational conditions, the discontinuous parents' presence, too many extra-scholastic activities, the inadequacy of the familiar and scholastic educational methods, the distracted and hurried attitude of the parents, are some of the factors that increase the child's attention deficit and hyperactive disorder.

It is well known that communication systems employing multiple transmit and multiple receive antennas provide high data rates along with increased reliability. Some of the design criteria of the space-time block codes (STBCs) for multiple input multiple output (MIMO)communication system are that these codes should attain large transmit diversity, high data-rate, low decoding-complexity, low decoding –delay and low peak-to-average power ratio (PAPR). STBCs based on real orthogonal designs (RODs) and complex orthogonal designs (CODs) achieve full transmit diversity and in addition, these codes are single-symbol maximum-likelihood (ML) decodable. It has been observed that the data-rate (in number of information symbols per channel use) of the square CODs falls exponentially with increase in number of antennas and it has led to the construction of rectangular CODs with high rate. We have constructed a class of maximal-rate CODs for n transmit antennas with rate if n is even and if n is odd. The novelty of the above construction is that they 2n+1 are constructed from square CODs. Though these codes have a high rate, this is achieved at the expense of large decoding delay especially when the number of antennas is 5or more. Moreover the rate also converges to half as the number of transmit antennas increases. We give a construction of rate-1/2 CODs with a substantial reduction in decoding delay when compared with the maximal- rate codes. Though there is a significant improvement in the rate of the codes mentioned above when compared with square CODs for the same number of antennas, the decoding delay of these codes is still considerably high. For certain applications, it is desirable to construct codes which are balanced with respect to both rate and decoding delay. To this end, we have constructed high rate and low decoding-delay RODs and CODs from Cayley-Dickson Algebra. Apart from the rate and decoding delay of orthogonal designs, peak-to-average power ratio (PAPR) of STBC is very important from implementation point of view. The standard constructions of square complex orthogonal designs contain a large number of zeros in the matrix result in gin high PAPR. We have given a construction for square complex orthogonal designs with lesser number of zero entries than the known constructions. When a + 1 is a power of 2, we get codes with no zero entries. Further more, we get complex orthogonal designs with no zero entry for any power of 2 antennas by introducing co- ordinate interleaved variables in the design matrix. These codes have significant advantage over the existing codes in term of PAPR. The only sacrifice that is made in the construction of these codes is that the signaling complexity (of these codes) is marginally greater than the existing codes (with zero entries) for some of the entries in the matrix consist of co-ordinate interleaved variables. Also a class of maximal-rate CODs (For mathematical equations pl see the pdf file)