Chiral ‘Frustrated Lewis Pair’ systems for practical enantioselective hydrogenation and hydrosilylation

The chemistry of ‘Frustrated Lewis Pairs’ (FLPs) has been the subject of intense investigation for over a decade now, this activity following the seminal report of Stephan et al. concerning the use of a system capable of reversibly binding hydrogen gas in the absence of a transition metal.1 The explosive development in the field was marked by the discovery of numerous systems which display FLP reactivity and engage in small molecule activation and catalytic reactivity, most notably hydrogenation. To a lesser extent, enantioselective versions of such transformations have also been reported. Perhaps the major limitation which deterred extensive investigation in this area has been the challenging synthesis required to assemble chiral catalysts. This thesis presents efforts towards the development of practical FLP systems for enantioselective hydrogenation and hydrosilylation as follows: Chapter 1 surveys the development of the FLP field, with notable developments in terms of structure, reactivity, and mechanistic understanding being covered. Particular attention is given to enantioselective FLP catalysts and to the work carried out for elucidating mechanisms of chirality transfer. Chapter 2 describes the development of NHC-stabilised borenium ions as catalysts for the FLP hydrogenation and hydrosilylation of N-alkyl ketimines, a poorly explored substrate class. Chapter 3 describes the synthesis of a chiral stannylium ion equivalent and investigations into its catalytic ability in the hydrogenation reaction. Chapter 4 describes the use of BINOL-derived phosphate salts as Lewis bases in FLP hydrogenation.Open Acces

Brexit tweets suggest nationalism and austerity - rather than populism - motivated voters

What do tweets posted in the run-up to the EU referendum reveal about the motivations for the vote? Marco Bastos and Dan Mercea (City, University of London) found that nationalist and economic concerns dominated people's concerns, but populist sentiments were less apparent. As the referendum got closer, there was an upsurge in globalist tweets

New Biomarkers in Screening Anthracycline-Induced Cardiotoxicity Only with Peripheral Blood Sampling

Because oxidative stress after administration of doxorubicin was identified as playing a central role in cardiac dysfunction, we hypothesized that the expression (or overexpression) of TLR2 and TLR4 contributes to the pathogenesis of doxorubicin-induced cardiac dysfunction. Toll-like receptors (TLRs) are members of the interleukin-1 receptor family (IL1) and are involved in the ability to react to the molecular trigger associated with pathogenic microorganisms. Recent studies have shown that TLR receptors are activated by endogenous signals, such as heat shock proteins and oxidative stress, which can contribute to congestive heart failure. Until recently, the best detection method for cardiotoxicity induced by anthracyclines was myocardial biopsy. Other early screening and early diagnosis methods (biomarkers—cardiac troponins and natriuretic peptide) have not yet proven their efficacy. Our proposed method is a new, revolutionary one that does not imply any kind of physical (and psychic) aggression on the patient: the targeted genetic (TLR2/TLR4) analysis of the human peripheral blood (which is a minimally invasive procedure)

Parametrizing Brexit: Mapping Twitter Political Space to Parliamentary Constituencies

In this paper, a proof of concept study is performed to validate the use of social media signal to model the ideological coordinates underpinning the Brexit debate . We rely on geographically - en rich ed Twitter data and a purpose - built , deep learning algorithm to map the political value space of users tweeting the referendum onto Parliamentary Constituencies. We find a significant incidence of nationalist sentiments and economic views expressed on Twitter , which pers ist throughout the campaign and are only offset in the last days when a globalist upsurge brings the British Twittersphere closer to a divide between nationalis t and globalis t standpoints . Upon combining demographic variables with the classifier scores , we f i nd that the model explains 41% of the variance in the referendum vote, an indi cation that not only material inequality, but also ideological readjustments have contributed to the outcome of the referendum . We conclude with a discussion of conceptual and methodological challenges in signal - processing social media data as a source for the measurement of public opinion

Tents, tweets, and events: The interplay between ongoing protests and social media

Recent protests have fuelled deliberations about the extent to which social media ignites popular uprisings. In this article, we use time-series data of Twitter, Facebook, and onsite protests to assess the Granger causality between social media streams and onsite developments at the Indignados, Occupy, and Brazilian Vinegar protests. After applying Gaussianization to the data, we found contentious communication on Twitter and Facebook forecasted onsite protest during the Indignados and Occupy protests, with bidirectional Granger causality between online and onsite protest in the Occupy series. Conversely, the Vinegar demonstrations presented Granger causality between Facebook and Twitter communication, and separately between protestors and injuries/arrests onsite. We conclude that the effective forecasting of protest activity likely varies across different instances of political unrest

The Brexit Botnet and User-Generated Hyperpartisan News

In this paper we uncover a network of Twitterbots comprising 13,493 accounts that tweeted the U.K. E.U. membership referendum, only to disappear from Twitter shortly after the ballot. We compare active users to this set of political bots with respect to temporal tweeting behavior, the size and speed of retweet cascades, and the composition of their retweet cascades (user-to-bot vs. bot-to-bot) to evidence strategies for bot deployment. Our results move forward the analysis of political bots by showing that Twitterbots can be effective at rapidly generating small to medium-sized cascades; that the retweeted content comprises user-generated hyperpartisan news, which is not strictly fake news, but whose shelf life is remarkably short; and, finally, that a botnet may be organized in specialized tiers or clusters dedicated to replicating either active users or content generated by other bots

Persistent Activist Communication in Occupy Gezi

We revisit the notion of activist persistence against the backdrop of protest communication on Twitter. We take an event-based approach and examine Occupy Gezi, a series of protests that occurred in Turkey in the early summer of 2013. By cross-referencing survey data with longitudinal Twitter data and in-depth interviews, we investigate the relationship between biographical availability, relational and organisational ties, social and personal costs to persistent activism online and on-location. Contrary to expectations, we find no clear-cut relationship between those factors and sustained commitment to participation in the occupation. We show that persistent activist communication did not feed into enduring organisational structures despite the continuous online activity observed during and beyond the peak of the Gezi occupation. The article concludes with reflections on the organisational ramifications of persistent communication and its significance in a political context posing high risks to participation in dissident politics

Movement Social Learning on Twitter: The Case of the People’s Assembly

The article examines the U.K.movement People’s Assembly against Austerity. It probes the extent to which opposition to austerity expressed on Twittercontributes to building bridges among disparate social groups affected by austerity politics and to enabling their jointcollective action. The studyaims toadd to the scholarship on anti-austerityprotests since the credit crunch. Numerous of those protests have been accompanied by vibrant activity on social media. Rather than to propose yet another examination of participant mobilisation on social media, theanalysis delineates and seeks to evidence a processof social learning among the social media following of a social movement.Relying on a combination of social network, semantic and discourse analysis, we discuss movement social learning as a diffusion process transpiringin the communication over an extended period of substantive and organisational issues, strategy and critical reflections that crystallised a cohesivein-group among the participant entities in the People’s Assembly

Protest communication ecologies

The flurry of protests since the turn of the decade has sustained a growth area in the social sciences. The diversity of approaches to the various facets and concerns raised by the collective action of aggrieved groups the world over impresses through multidisciplinarity and the wealth of insights it has generated. This introduction to a special issue of the international journal Information, Communication and Society is an invitation to recover conceptual instruments — such as the ecological trope — that have fallen out of fashion in media and communication studies. We account for their fall from grace and explicate the rationale for seeking to reinsert them into the empirical terrain of interlocking media, communication practices and protest which we aim to both capture with theory and adopt as a starting point for further analytical innovation