4,810 research outputs found

    Synthesis, properties and applications of all-cis-pentafluorocyclohexane 'Janus' ring building blocks

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    Strategically fluorinated compounds such as the all-cis-pentafluorocyclohexane ‘Janus’ rings, the subject of this research, can have strong molecular dipole moments because the electronegative fluorines polarise the geminal hydrogens rendering them electropositive. In Chapter 1, a general discussion of the dominant interactions associated with organofluorine compounds is given. This is followed by an examination of the variety of fluorination methods available. The role of fluorine in medicinal chemistry is explored including in positron emission tomography (PET). A summary of previous work from the St Andrews group provides the contextual basis on which the following chapters build. Chapter 2 explores a recently reported Rh-catalysed hydrogenation reaction of fluoroarenes to access all-cis-fluorocyclohexanes in excellent diastereoselectivity. The scope of this reaction is expanded to generate novel cyclohexane products such as alcohol 2.47 and methyl ester 2.60. Derivatisation of these products has furnished a library of all-cis-pentafluorocyclohexane building blocks for further study. These include alkyl bromide 2.82, organoazide 2.83 and aldehyde 2.87. In Chapter 3, the elaboration of these building blocks to higher order molecular structures is explored. Ugi 4-component reactions (Ugi-4CR) with aldehyde 2.87 provide combinatorial access to medicinally relevant bis-amides 3.20-3.27. The Ugi-4CR, optimised by microwave assistance, can be completed within 45 mins. Using an HPLC method the Log P of three of these Ugi products (3.23, 3.25 and 3.27) was measured and in each case the Log P value reduced relative to phenyl ring analogues. This finding suggests a potential application of the ‘Janus’ ring as an arene isostere in medicinal chemistry. Other methods of elaboration explored in Chapter 3 include amide coupling, Wittig and CuAAC ‘click’ reactions. Chapter 4 reports the preparation of ‘Janus’ ring bearing novel amphiphiles, the long chain carboxylic acid 4.1 and alcohol 4.2 as well as analogous hydrocarbon reference compounds 4.4 and 4.5. A Langmuir isotherm study examined the influence of the ring system on phase behaviour at the air-water interface. Evidence is presented of molecular self-assembly for the long chain 4.1 and 4.2, unlike the classical behaviour observed for the hydrocarbon counterparts 4.4 and 4.5. This analysis is supported by a thorough examination of X-ray crystal structures and presents a platform for the further development of the ‘Janus’ ring motif for supramolecular chemistry. Finally, Chapter 5 summarises the findings of the previous chapters and explores possible avenues for future work such as the development of a ‘pull-down’ assay using biotinylated affinity probes 5.1 and 5.2 to better understand interactions between the ‘Janus’ ring and proteins of interest."The research underpinning this thesis has received funding from the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (CRITICAT, Grant Number EP/L016419/1)." -- Fundin

    Cultures of Citizenship in the Twenty-First Century: Literary and Cultural Perspectives on a Legal Concept

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    In the early twenty-first century, the concept of citizenship is more contested than ever. As refugees set out to cross the Mediterranean, European nation-states refer to "cultural integrity" and "immigrant inassimilability," revealing citizenship to be much more than a legal concept. The contributors to this volume take an interdisciplinary approach to considering how cultures of citizenship are being envisioned and interrogated in literary and cultural (con)texts. Through this framework, they attend to the tension between the citizen and its spectral others - a tension determined by how a country defines difference at a given moment

    Activating Methane and Other Small Molecules: Computational study of Zeolites and Actinides

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    Exploring the catalytic properties and reactivity of actinide complexes towards activation of small molecules is important as human activities have led to the increased distribution of these species in nature. Toward this end, it is important to have a computational protocol for studying these species, in this thesis we provide details on the performance of multiconfigurational pair-density functional theory (MC-PDFT) in actinide chemistry. MC-PDFT and Kohn-Sham Density Functional Theory (KS-DFT) perform well for these species with indications that the former can be used for species with even greater static electron correlation effect. In addition, we study the activity of organometallic trans-uranium complexes towards the electrocatalytic reduction of water. We conclude that, with a guided choice of ligand, neptunium complexes can provide similar reactivity when compared to organometallic uranium complexes.Conversion of methane to methanol has been a major focus of research interest over the years. This is largely due to the abundance of natural gas, of which methane is the major constituent. Copper-exchanged zeolites have been shown to be able to kinetically trap activated methane as strongly-bound methoxy groups, preventing over-oxidation to CO2, CO and HCOOH. In this stepwise process, there are three cycles; an initial activation step to form the copper oxo active site, methane C-H activation and lastly simultaneous desorption of methanol and re -activation of the active site.. We provide detailed description of the pathway for the formation of over oxidation products. It is observed that to ensure high selectivity to methanol and prevent further hydrogen atom abstraction by extra-framework species, the methyl group must be stabilized from the copper-oxo active sites. There is a temperature gradient between the steps in the methane-to-methanol conversion cycle which is an impediment to industrial adoption of this approach for methane-to-methanol conversion. To mitigate this, we have investigated the impact of heterometallic extra-framework motifs on the temperature gradients of each step. Using periodic DFT, we provide detailed descriptions of the mechanistic pathways for each of the three steps. We were subsequently able to design motif(s) with great methane C-H activities as well as the abilities to be formed and regenerated at nearly the same temperatures. We found [Cu-O-Ag] and [Cu-O-Pd] to be potential candidates for isothermal or near-isothermal operations of the methane-to-methanol conversion cycle. Finally, we provide insights to the changes in optical spectra of activated copper-exchanged zeolites, gaining an understanding of the evolution of these systems on a molecular level will provide opportunities to achieve improved reactivity

    A new global media order? : debates and policies on media and mass communication at UNESCO, 1960 to 1980

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    Defence date: 24 June 2019Examining Board: Professor Federico Romero, European University Institute (Supervisor); Professor Corinna Unger, European University Institute (Second Reader); Professor Iris Schröder, UniversitĂ€t Erfurt (External Advisor); Professor Sandrine Kott, UniversitĂ© de GenĂšveThe 1970s, a UNESCO report claimed, would be the “communication decade”. UNESCO had started research on new means of mass communication for development purposes in the 1960s. In the 1970s, the issue evolved into a debate on the so-called “New World Information and Communication Order” (NWICO) and the democratisation of global media. It led UNESCO itself into a major crisis in the 1980s. My project traces a dual trajectory that shaped this global debate on transnational media. The first follows communications from being seen as a tool and goal of national development in the 1960s, to communications seen as catalyst for recalibrated international political, cultural and economic relations. The second relates to the recurrent attempts, and eventual failure, of various actors to engage UNESCO as a platform to promote a new global order. I take UNESCO as an observation post to study national ambitions intersecting with internationalist claims to universality, changing understandings of the role of media in development and international affairs, and competing visions of world order. Looking at the modes of this debate, the project also sheds light on the evolving practices of internationalism. Located in the field of a new international history, this study relates to the recent rediscovery of the “new order”-discourses of the 1970s as well as to the increasingly diversified literature on internationalism. With its focus on international communications and attempts at regulating them, it also contributes to an international media history in the late twentieth century. The emphasis on the role of international organisations as well as on voices from the Global South will make contributions to our understanding of the historic macro-processes of decolonisation, globalisation and the Cold War

    Under construction: infrastructure and modern fiction

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    In this dissertation, I argue that infrastructural development, with its technological promises but widening geographic disparities and social and environmental consequences, informs both the narrative content and aesthetic forms of modernist and contemporary Anglophone fiction. Despite its prevalent material forms—roads, rails, pipes, and wires—infrastructure poses particular formal and narrative problems, often receding into the background as mere setting. To address how literary fiction theorizes the experience of infrastructure requires reading “infrastructurally”: that is, paying attention to the seemingly mundane interactions between characters and their built environments. The writers central to this project—James Joyce, William Faulkner, Karen Tei Yamashita, and Mohsin Hamid—take up the representational challenges posed by infrastructure by bringing transit networks, sanitation systems, and electrical grids and the histories of their development and use into the foreground. These writers call attention to the political dimensions of built environments, revealing the ways infrastructures produce, reinforce, and perpetuate racial and socioeconomic fault lines. They also attempt to formalize the material relations of power inscribed by and within infrastructure; the novel itself becomes an imaginary counterpart to the technologies of infrastructure, a form that shapes and constrains what types of social action and affiliation are possible

    Revolution Beyond the Event

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    Revolution Beyond the Event brings together leading international anthropologists alongside emerging scholars to examine revolutionary legacies from the MENA region, Latin America and the Caribbean. It explores the idea that revolutions have varied afterlives that complicate the assumptions about their duration, pace and progression, and argues that a renewed focus on the temporality of radical politics is essential to our understanding of revolution. Approaching revolution through its relationship to time, the book is a critical intervention into attempts to define revolutions as bounded events that act as sequential transitions from one political system to another. It pursues an ethnographically driven rethinking of the temporal horizons that are at stake in revolutionary processes, arguing that linear views of revolution are inextricably tied to notions of progress and modernity. Through a careful selection of case studies, the book provides a critical perspective on the lived realities of revolutionary afterlives, challenging the liberal humanist assumptions implicit in the ‘modern’ idea of revolution, and reappraising the political agency of people caught up in revolutionary situations across a variety of ethnographic contexts

    Subtitling Francophone World Cinema: Narratives of Identity, Alterity and Power in Audiovisual Translation

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    Cinematic representations of multilingualism raise questions about communication and mutual understanding not only between characters in films but also between films and their audiences, for whom it is typically necessary to facilitate access to foreign dialogues through different forms of translation. Where languages are pitted against one another, however, or juxtaposed in ways that serve to reveal and explore tensions and hierarchies between different linguistic, cultural and social groups, translation becomes entangled in issues of identity, alterity and power. This thesis untangles and explores these complex interactions between languages and translation as they arise in the practice of subtitling. Specifically, it asks questions about how subtitling can play an active part in the shaping of identity by mediating differences between the local, the national and the global, and how subtitles intersect with the relations of power that exist between different cultures. In turn, the thesis exposes the semiotic and narrative dynamics that subtitles add to films and considers the implications of these findings for the ways we think of audiovisual translation and of its relationship with creative processes and accessibility practices. These questions are considered in the context of multilingualism, not only because issues of language, identity and power relations are inextricably involved in discussions thereof, but because multilingualism is an increasingly common experience for many subtitlers and film audiences alike. This is particularly true of francophone world cinema, from whose corpus the thesis analyses six films across three case studies: Bienvenue chez les Ch’tis (Dany Boon 2008), L’esquive (Abdellatif Kechiche 2003), Inch’Allah dimanche (Yamina Benguigui 2001), Dheepan (Jacques Audiard 2015), Le grand voyage (IsmaĂ«l Ferroukhi 2004) and Exils (Tony Gatlif 2004). Methodologically, the thesis combines semiotic, narrative, and linguistic analysis of the subtitled audiovisual texts, drawing on a range of perspectives within Audiovisual Translation Studies, Postcolonial Translation Studies, Film Studies, French and Francophone Studies and Cultural Studies

    Elucidating the Role of Quorum Sensing (QS) and Developing QS Modulators for Streptococcus pneumoniae and Its Close Commensal Relative, Streptococcus mitis

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    Quorum sensing (QS) is a ubiquitous communication mechanism in bacteria that controls bacterial group behavior phenotypes, such as competence, biofilm formation, and virulence factor production. Streptococcus pneumoniae, an opportunistic pathogen, and Streptococcus mitis are prototypes of commensal bacteria in the Mitis group and share >80% of their genes. Both S. mitis and S. pneumoniae utilize a peptide pheromone (competence stimulating peptide, CSP), which binds to its membrane bound ComD receptor to induce QS responses and different pathogenic phenotypes. The aim of this study was to target this non- essential bacterial communication pathway through impediment of the peptide-receptor interaction by using synthetic CSP analogs, thereby circumventing a key issue with traditional antibiotics, the introduction of selective pressure for resistance development. To this end, I have conducted comprehensive structure-activity relationship (SAR) analyses of both S. pneumoniae and S. mitis CSPs to gain a deeper understanding of the molecular mechanisms that drive these QS circuitries. The SAR results revealed several interesting activity trends and uncovered several CSP-based QS modulators with distinct activity profiles. Additionally, I evaluated several phenotypes that can be utilized to assess the effect of lead peptide analogs on the expression of group behavior genes. In addition to yielding a series of new QS activators and inhibitors, key SAR knowledge of the CSP pheromones obtained through this study, can be utilized for the rational design of highly potent, pharmacologically stable CSP-based QS modulators with therapeutic potential
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