L’oxydation troposphérique des composés organiques volatils (COV) constitue une contribution importante à la formation de photooxydants. L’évaluation de l’impact environnemental des COV rend indispensable d’acquérir une bonne compréhension des processus en jeu. Ce travail porte donc sur l’étude en atmosphère simulée de la réactivité troposphérique avec le radical nitrate (NO3) de COV oxygénés appartenant à une série homogène d’éthers vinyliques aliphatiques (méthyl, éthyl, propyl et butyl vinyl éthers), et à une série de trois esters (acétates d’isopropényle, de vinyle, et d’allyle), auxquelles s’ajoute le 2,3,2 méthylbutènol (MBO). Pour tous ces composés, des études cinétiques (destinées à mesurer la constante d’oxydation par NO3 des produits étudiés) ont été menées selon la méthode relative, et pour certains composés selon la méthode absolue. Des études mécanistiques (destinées à identifier et quantifier les produits de la réaction, et à élucider le mécanisme réactionnel) ont également été menées. Une réévaluation de la constante cinétique d’oxydation du propène par NO3, qui a été mesurée selon la méthode absolue, a également été faite. Les expériences ont été menées dans la chambre de simulation atmosphérique du LISA, à température ambiante et à pression atmosphérique. Les durées de vie des composés étudiés vis-à-vis de NO3 ont été calculées, et comparées à celles vis-à-vis du radical OH et de l’ozone. Les résultats montrent que NO3 peut constituer un puits majeur pour les COV les plus réactifs, comme les éthers vinyliques. Par ailleurs, les apports de nos résultats aux règles de réactivité des COV ont été discutés / The tropospheric oxidation of the volatile organic compounds (VOC) constitutes an important contribution to the formation of photooxydants. It is necessary to acquire a good comprehension of the concerned chemical processes in order to correctly evaluate the environmental impact of the VOC. This work thus concerns the study under simulated conditions of the tropospheric reactivity with the nitrate radical (NO3) of oxygenated VOC pertaining to a homologous series of aliphatic vinyl ethers (methyl, éthyl, propyl and butyl vinyl ethers), and to a series of three esters (allyl and vinyl, isopropenyl acetates). In addition, the 2,3,2 méthylbutènol (MBO) has been studied too. For all these compounds, kinetic studies (in order to measure the rate constant of NO3 oxidation of the studied products) were performed according to the relative rate method, and for some compounds according to the absolute method. Mechanistic studies (in order to identify and quantify the reaction products, and to elucidate the chemical mechanism) were also performed. A revaluation of the rate constant of NO3 oxidation of propene, which was measured according to the absolute method, was also performed. The experiments were carried out in the LISA atmospheric simulation chamber, at room temperature and atmospheric pressure. The lifetimes of the studied compounds with respect to NO3 were calculated, and were compared to those with respect to OH radical and to ozone. The results show that NO3 can be a major sink for the most reactive VOC, like the vinyl ethers. In addition, the contributions of our results to the rules of reactivity of the VOC were discussed

No description available.

Ministerio de Ciencia y Tecnología, DGES (proyecto PB97-0133); Generalitat Valenciana (CTIDIB/2002/318)

I aim to provide a satisfying response to radical scepticism, a view according to which our knowledge of the external world is impossible. In the first chapter I investigate into the nature and the source of scepticism. Radical scepticism is motivated both by the closureRK-based and the underdeterminationRK-based sceptical arguments. Because these two sceptical arguments are logically independent, any satisfying anti-sceptical proposal must take both of them into consideration. Also, scepticism is a paradox, albeit a spurious one, so we need to provide a diagnosis as to why we are lead into the paradox and why the alleged paradox misrepresents our epistemic standings. Hence, I advocate an obstacle-dissolving strategy for combating the sceptical problem. In chapter two, I discuss the anti-sceptical import of transcendental arguments. Although ambitious transcendental arguments are vulnerable to Stroud’s dilemma, I argue that modest transcendental arguments are promising. Modest transcendental arguments start from an undoubted psychological fact and then reveal some necessary theoretical commitments that we must make. Regarding these commitments, I submit that we are type II epistemically justified in believing them. Our commitments are type II justified in the sense that making these commitments can promote our epistemic goals, namely, the attainment of true beliefs and the avoidance of false beliefs. After that, in light of Cassam’s objection to transcendental arguments, I contend that a modest transcendental argument should be used as a stepping stone for a diagnostic anti-sceptical proposal. In chapter three, I develop a Davidsonian response to closureRK-based radical scepticism. This form of sceptical argument rests on the idea that there is no limitation on our acquisition of rationally grounded knowledge. I discuss Davidson’s theory of radical interpretation, the principle of charity and triangulation. Crucially, he argues that the content of a knowledge-apt everyday belief is determined by its typical cause and other relevant beliefs. Further, among different propositional attitudes, belief is prior to doubt. What follows is that doubt must be local because it must presume other content-determining beliefs. Also, I explore Davidson’s view on the concept of belief. On his view, in order to have a knowledge-apt belief, we must have the concept of knowledge-apt belief. We can command this concept by having the concept of objective truth. Objective truth requires that we are aware of and are capable of appreciating the possibility of a belief’s being true or false. And this possibility cannot be appreciated unless we have some related contentful beliefs to identify the content of the very belief. However, we are committed to, as opposed to believing, the proposition that the sceptical hypothesis does not obtain. It is impossible to appreciate the possibility of our fundamental commitments being false from our own perspective, because fundamental commitments specify the general cause of our beliefs. A change in this regard would cause a total change of the content of all beliefs, which leaves us no contentful belief at all to make this possibility intelligible. Therefore, the closureRK principle is not applicable to the evaluation of the sceptical hypothesis. Hence, we can retain the closureRK principle while evading the closureRK-based sceptical challenge. Unfortunately, the Davidsonian response cannot deal with the underdeterminationRK-based sceptical challenge, because we are not shown whether our rational support in the good case favours one’s everyday belief over its sceptical counterpart. In chapter four, I examine how epistemological disjunctivism can deal with underdeterminationRK-based radical scepticism. This form of sceptical argument assumes that our rational support provides at best inconclusive support for our beliefs. Therefore, a belief’s being rationally supported, no matter in the good case or in the bad case, is compatible with the belief’s being false. Epistemological disjunctivism claims that in paradigm cases of perceptual knowledge, our rational support can be both factive and reflectively accessible. The factive rational support at issue is one’s propositional seeing. I discuss both McDowell’s and Pritchard’s proposals for motivating factive seeing, and I argue for epistemological disjunctivism against three prime facie objections, i.e., the distinguishability problem, the basis problem and the access problem. When epistemological disjunctivism is shown to be a plausible view, I argue that underdeterminationRK-based radical scepticism can be dismissed. In particular, in the optimal case, factive rational support favours our everyday belief over the sceptical hypothesis. However, regarding closureRK-based radical scepticism, epistemological disjunctivism seems to licence a robust answer. The ambitious answer is that, in the good case, we can after all know the denial of the sceptical hypothesis in virtue of possessing factive rational support. And it is the immodesty of this answer that renders this response unpalatable. In the last chapter, I propose a combined treatment of the sceptical problem. Although both the Davidsonian response and the epistemological disjunctivist response can only deal with one aspect of the sceptical problem, their views are in fact mutually supportive. On the one hand, the Davidsonian response, together with a Wittgensteinian insight, shows that why rational support can only be provided in a local manner; on the other hand, epistemological disjunctivism reminds us that rational support can be factive in the good case. Putting these two points together allows us to answer the whole sceptical challenge in a uniform way. This combined proposal has three claims. First, our rational support can be both local and factive, so we can dismiss both sceptical arguments in one go. Second, the sceptical problem is a spurious paradox, so the combined treatment involves a diagnosis. This diagnosis starts from a modest transcendental argument which reveals some necessary commitments that we must make, and then proceeds to expose faulty assumptions in the sceptical paradox. Third, once the dubious assumptions are dislodged, we can evade the sceptical problem once and for all. In the end, we are offered with a satisfying response to radical scepticism.

The thesis aims primarily to analyse the communication strategies of radical right parties. More specifically, the research examines three cases of radical right parties in Western Europe during the first decade of the twenty-first century with particular emphasis on the political communication along with marketing and branding techniques used to engage with the electorate to gain and maintain electoral support. These case studies comprise the Greek Popular Orthodox Rally (LA.O.S.), the Swiss People’s Party (SVP) and the Italian National Alliance (AN). Different forms of content analysis are used in order to pinpoint the characteristics that identify the parties as members of the radical right family. Through this approach the thesis provides evidence that the parties, in their effort to become more appealing to their audiences, avoid direct engagement with issues, which reflect traditional ideological tenets of the radical right issues such as fascism, racism or xenophobia. Rather, they attempt to present a more mainstream and competitive profile in the political arena. From a market-oriented perspective, the thesis addresses questions on marketing and related explanations which focus both on how the parties choose to communicate with the electorate, what is their message and, through comparative analysis, whether there are similarities in communication techniques among the three parties and whether it can be argued that parties in the radical right family project a common profile in terms of their communication strategies. Furthermore, the application of such an approach to the use of political communication techniques of the selected radical right parties can contribute to a wider understanding of how the concept of ‘consumption’ has come to be applied increasingly in activities undertaken in the political arena.

"In situ polymerizing hydrogel systems play an important role in many tissue engineering applications. They have proven to be useful in biomedical applications that require conversion of liquid macromer solution to tissue compliant hydrogel under physiological conditions. A series of poly(ethylene glycol)-co-poly(lactate) diacrylate macromers were synthesized with variable PEG molecular weight and lactate content. The macromer compositions were confirmed by NMR spectroscopy and ion chromatography. These macromers were polymerized to form hydrogels by free radical polymerization using either redox or photochemical initiators. The current study focused on the optimization of polymerization conditions. Compressive modulus and residual acrylate analysis were used to evaluate polymerization efficiency. To characterize the network structure, the swelling ratio values were converted to the average molecular weight between crosslinks ( ) and mesh sizes (ξ) using Flory-Rehner theory. Current study suggested hydrophobic modification is desired to achieve high polymerization efficiency. Electrospinning is a developing technique to produce ultra fine fibrous structures from polymer solutions. Current research efforts have focused on understanding the effects of principal parameters such as molecular weight distribution (MWD) and polymer surfactant interactions on the morphology of the electrospun patterns. Fundamental understanding of the dilute solution rheology of the polydisperse polymer/solvent and polymer/solvent/surfactant systems was first established. Using viscometry, the on-set of entanglement concentrations could be obtained for various systems. Electrospinning was then carried out to evaluate the effects of polymer molecular weight, molecular weight distribution (MWD) and the polymer-surfactant interaction on the fiber formation and morphological features. The importance of increased chain entanglements due to high molecular weight component within the polydisperse system and the expansion of the coil dimension by binding the surfactant micelles have been recognized. The critical concentrations for incipient as well as stable fiber formation were determined. "

Gene delivery can potentially treat acquired and genetic diseases such as cystic fibrosis, haemophilia and cancer. Non-viral gene delivery vectors are attractive candidates over viral vectors such as recombinant viruses, due to their lower cytotoxicity and immunogenicity, despite significantly lower transfection efficiencies. To improve efficiency of non-viral vectors, the investigation of the various parameters influencing DNA transfection is essential. The present study developed a versatile gene delivery system with tailored physicochemical and biological properties. The system used polymer brushes synthesised via atomic transfer radical polymerisation (ATRP), grafted from silica nanoparticles, whose charge density, grafting density, chemistry, length of brush, the size and shape can be altered. The primary focus of the study was poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), known for its positive charge and DNA condensation. The ability of PDMAEMA to interact with DNA was characterised using dynamic light scattering, electrophoretic light scattering methods, surface plasmon resonance and in situ ellipsometry whilst its interaction with cells was studied via cell viability assays. The brush behaviour in response to pH and ionic strength was also studied. The charge density was altered by copolymerising with poly[oligo(ethylene glycol) methyl ether methacrylate](POEGMA) and the effect of such modification on DNA interaction was studied. PDMAEMA-grafted nanoparticles gave the highest transfection efficiency compared to other synthesised polymer brushes, but still displaying almost 2-fold lower transfection efficiency than the commercially available reagent jetPEI®. Different brush chemistries were also investigated. Poly(glycidyl methacrylate) (PGMA) decorated with oligoamines: allylamine, diethylenetriamine and pentaethylene hexamine, and PDMAEMA quaternized with alkyl halides: methyl iodide, allyl iodide and ethyl iodoacetate did not show any significant transfection, despite their performance reported in the literature. The robust system developed is a promising platform for further investigation of parameters influencing cellular uptake and gene expression, and important milestone to develop non-viral gene delivery systems.

This thesis seeks to create a more robust concept of resistance that may respond to the crisis of liberal democracy in contemporary neoliberal society. The crisis comes as a result of increasing dissatisfaction with the liberal democratic institutions, which are viewed by citizens as unrepresentative and unresponsive to their political demands. I argue that the post-2008 wave of protest movements represents an important attempt at challenging neoliberalism through the political project of radicalising democracy. Drawing upon different post-Marxist and poststructuralist approaches in contemporary political theory, the key theoretical contribution of the thesis is to elucidate the relationship between radical politics of protest movements and the existing political institutions. I suggest that the relation between the two is antagonistic largely due to the tension in liberal democracy between liberal institutions and rights and popular sovereignty. To this end, I argue that the political project of theorising radical democracy needs to be complemented with a political economy analysis. The political project of radicalising democracy responds to the limitations of the pluralist-elitist conception of politics in contemporary democratic theory and points towards social movement and new radical left literature as a fruitful way for constructing an alternative model of democracy. In response to the objection to power in parts of the radical left, I maintain that a more nuanced understanding of resistance is needed, which accounts for the structural relation between resistance and power. Finally, to properly account for the structural conditions and obstacles facing the radical left in the struggle against neoliberalism, the thesis also provides an economic-institutional analysis, which explains the ideological relationship between liberal democracy and neoliberalism from a historical perspective. The different theoretical contributions together help elucidate the empirical case of radical politics in Southern Europe and the challenges lying ahead.

Ces travaux de thèse ont consisté à développer de nouvelles réactions radicalaires dans le domaine de la glycochimie. Deux cascades radicalaires, n’utilisant aucun dérivé stannylé et impliquant un transfert d’hydrogène intramoléculaire, ont été étudiées. La première permet de synthétiser des motifs spirocétaliques [6.5] nonanomériques et la deuxième consiste à débenzyler régiosélectivement un éther de benzyle par proximité. Les spirocétals [6.5] nonanomériques sont des motifs présents dans de nombreuses structures de produits naturels. Pour obtenir ce squelette, dont la synthèse est généralement difficile, nous avons développé une cascade radicalaire en chaîne impliquant des précurseurs homopropargyliques et des dérivés phosphorés non toxiques. Plusieurs étapes se succèdent dont l’addition du radical phosphoré sur la triple liaison, un transfert 1,5 d’hydrogène permettant de générer un radical anomère de O-glycoside, à l’origine de la diastéréosélectivité du centre spiranique, et une cyclisation 5-exo-trig. Cette stratégie s’est révélée particulièrement efficace puisque de bons rendements et une excellente diastéréosélectivité ont été obtenus notamment en série glucose et glucosamine. La nouvelle réaction de O-débenzylation par proximité, développée dans la deuxième partie, permet de déprotéger sélectivement un éther de benzyle en α d’un groupement hydroxyle préalablement fonctionnalisé sous forme d’éther de silyle xanthate. Cette réaction se déroule en deux étapes successives dans le même ballon. La première est une cascade radicalaire constituée, entre autres, d’un transfert 1,7 d’hydrogène et de l’addition du radical benzylique, ainsi formé, sur le peroxyde de dilauroyle. L’acétal mixte intermédiaire obtenu est alors hydrolysé lors de la deuxième étape. Cette méthodologie a été appliquée avec succès à divers mono- et disaccharides polybenzylés et s’est révélée efficace en présence de nombreuses autres fonctionnalités chimiques (acétal de benzylidène, azido..). / The aim of this thesis was the development of new tin-free radical reactions in the field of glycochemistry. For this purpose, an intramolecular hydrogen atom transfer was the key step of these methodologies. The first reaction allowed the access to nonanomeric [6.5] spiroketals and the second one is a new regioselective de-O-benzylation reaction through proximity effect. The nonanomeric [6.5] spiroketals are widely distributed in natural products and have been difficult to access. To synthesize this scaffold, we have developed a chain radical cascade involving homopropargyl precursors and non-toxic phosphorus derivatives. The phosphorus-centered radical adds to the triple bond followed by a radical translocation through intramolecular hydrogen atom transfer. This key step of the reaction provides an intermediate O-glycoside anomeric radical, which ensure the diastereoselectivity of the reaction. Finally a 5-exo-trig cyclization yields the desired spiroketal. This strategy has been proved to be highly efficient since good yields and selectivity were obtained especially in glucose and glucosamine series. The new regioselective de-O-benzylation reaction through proximity effect, developed in the second part, allowed the deprotection of a benzyl ether in α position of a hydroxyl group previously functionalized as a xanthate silyl ether. This reaction occurs in two successive steps in the same flask. The first one is a radical cascade involving an 1,7 intramolecular hydrogen atom transfer and the addition of the newly formed benzylic radical on dilauroyl peroxide. The mixed ketal intermediate thus obtained is then hydrolyzed during the second step. This methodology has been successfully applied to several polybenzylated mono- and disaccharides and tolerates the presence of various chemical functions (benzylidene ketal, azido...) showing its versatility.

Nitrogen-centred radicals (NCRs) are powerful reaction intermediates that allow key bonds to nitrogen to be formed. However, the generation of NCRs typically requires pre-functionalised precursors that can be difficult to access and harsh reaction conditions in the formation of the NCR itself which has limited synthetic application. In this thesis, the application of visible-light mediated photoredox catalysis towards the generation of iminyl and amidyl radicals is demonstrated and the advances to NCR chemistry this has facilitated. Initial work developed electron-poor O-aryl oximes as suitable precursors for hydroimination reactions, activated via single-electron reduction under photoredox conditions. These precursors are accessible by a simple condensation reaction with the commercially available hydroxylamine and can be purified by recrystallization. The realisation of a transition metal-free protocol was made possible by using the organic dye eosin Y as the photocatalyst. This activation mode was then extended to the generation of (carb)amidyl-radicals from easy-to-make O-aryl hydroxylamides. Similar transition metal-free photoredox reaction conditions could be applied in intramolecular hydroamidation reactions allowing the preparation of lactams and cyclic (thio)carbamates. For the first time N-Boc and N-Cbz protected amidyl-radicals were utilised despite the very high electrophilic nature of these species. Finally, one of the big challenges associated with NCR chemistry was addressed; the development of multicomponent reactions for the divergent synthesis of complex N-containing molecules. Previously developed O-aryl precursors proved unsuitable and instead a novel class of alpha-imino acid precursors were identified that can be activated via oxidation under photoredox conditions. This activation mode was also rendered transition metal-free by using the Fukuzumi photoredox catalyst. These new NCR precursors proved crucial in developing a divergent methodology that allows the synthesis of up to fifteen iminofunctionalised products from a single starting material. Moreover, this methodology could be applied to the modification of complex natural products such as immunosuppressant drug mycophenolic acid and alkaloid thebaine. One could envisage such an approach may be ideal for a drug discovery type situation where changes in functionality can greater alter drug activity.