A microscopic description of acid-base equilibrium

Acid-base reactions are ubiquitous in nature. Understanding their mechanisms is crucial in many fields, from biochemistry to industrial catalysis. Unfortunately, experiments only give limited information without much insight into the molecular behaviour. Atomistic simulations could complement experiments and shed precious light on microscopic mechanisms. The large free energy barriers connected to proton dissociation however make the use of enhanced sampling methods mandatory. Here we perform an ab initio molecular dynamics (MD) simulation and enhance sampling with the help of methadynamics. This has been made possible by the introduction of novel descriptors or collective variables (CVs) that are based on a conceptually new outlook on acid-base equilibria. We test successfully our approach on three different aqueous solutions of acetic acid, ammonia, and bicarbonate. These are representative of acid, basic, and amphoteric behaviour

Metadynamics with Discriminants: a Tool for Understanding Chemistry

We introduce an extension of a recently published method\cite{Mendels2018} to obtain low-dimensional collective variables for studying multiple states free energy processes in chemical reactions. The only information needed is a collection of simple statistics of the equilibrium properties of the reactants and product states. No information on the reaction mechanism has to be given. The method allows studying a large variety of chemical reactivity problems including multiple reaction pathways, isomerization, stereo- and regiospecificity. We applied the method to two fundamental organic chemical reactions. First we study the \ce{S_N2} nucleophilic substitution reaction of a \ce{Cl} in \ce{CH_2 Cl_2} leading to an understanding of the kinetic origin of the chirality inversion in such processes. Subsequently, we tackle the problem of regioselectivity in the hydrobromination of propene revealing that the nature of empirical observations such as the Markovinikov's rules lies in the chemical kinetics rather than the thermodynamic stability of the products

PET studies on the aetiology of Parkinson's disease and on the efficacy of cell transplantation therapy

Imperial Users onl

Relevant results from the NA48 experiment

We report relevant results from NA48 experiment at CERN SPS. NA48 was proposed in 1990 \cite{proposal} to study direct CP violation in $K^0\to\pi\pi$ to a level of accuracy sufficient to resolve the inconclusive status left by the previous measurements performed by NA31 \cite{NA31} and E731 \cite{E731}. In 2002 NA48 published the final result \cite{NA48epsoeps}. Small modification to the experimental setup have allowed NA48 to go forward with an extensive investigation of $K^0$ rare decays and hyperon decays. Some results are already available and reported here together with the final CP violation measurement.Comment: 3 pages, 1 eps figure, XXIII Physics in collisio

Gestione Chirurgica di Cisti e Fistole Cervicali in bambini e adolescenti: uno studio retrospettivo dal 2004 a oggi

la tesi si sviluppa analizzando un numero di pazienti pediatrici pari a circa 160, ricoverati negli ospedali di Cisanello e Anna Meyer per patologie cervicali. vengono analizzate caratteristiche come presentazione clinica, diagnosi, terapia, complicanze e recidive, confrontando tali statistiche con quelle più recenti, mediante una revisione della letteratura

"Australia’s most evil and repugnant nightspot” Foco Club and transnational politics in Brisbane’s ‘68’

This paper locates Brisbane – traditionally seen as a backwater both politically and culturally – within the transnational flows of people, ideas and actions which constituted global sixties activism. Host to a wide assortment of youth dissidents, Brisbane provided a plethora of streets and spaces in which activists became part of an imagined community of global revolt. Through investigating such locations, ranging from cultural centres such as the disco-cum-movie and poetry spot Foco Club to bookshops like Red and Black, radicals are revealed as engaging in a sophisticated and globally conscious urban politics of occupation and creative transformation – seeking to invent a differentially youthful social geography and everyday life in the face of overt hostility from the establishment. © 2011 The University of Queenslan

Travel, Politics and the Limits of Liminality During Australia’s Sixties

Victor Turner describes the individual experience of travel as ‘liminal’. Opening new vistas of possibility, it upturns ordinary social conventions and codes, constructing in their place new communities of hope and change. Such utopian moments of encounter are, however, just that—moments that are fleeting and generally inconsequential. This paper seeks to understand and critique Turner’s ideas of liminality, pilgrimage and communitas within the context of Australian social movements in the ‘long’ and ‘global’ 1960s. Though often ignored or marginalised in local and international scholarship, Australia had a much more complex and interesting experience of this period than the paucity of scholarly work would indicate. In fact, a variety of activists in areas ranging from Indigenous rights to the peace and workers movements pushed the boundaries of political discourse during a period marked by stultifying social and cultural climates. Through a focus on three travel narratives—those of Brisbane radical Brian Laver and young Communist Party of Australia (CPA) members to Czechoslovakia and Bulgaria during 1968, Sydney Trotskyite Denis Freney to Algeria in the early 1960s and five Indigenous activists to a Black Power conference in Atlanta, Georgia in 1970—this paper will highlight the importance of global connections to Australian social movements. The notion of liminality will initially be critiqued through a focus on pre-histories to travel: the ideas, rumours and local problems that can be glossed over in work heralding the power of the moment. Such moments of encounter were, however, still transformative for these activists, with their variety of experiences facilitating what Turner called communitas, spontaneous affinities and solidarities across borders of race, culture and understanding. The pilgrims’ return concludes this discussion, with their ‘translation’ of global ideas into new, local contexts giving them the role not just of a missionary, but also a mediator—disrupting travel’s supposed fleetingness and locating its importance to the transnational flow of ideas during the Sixties

The Secret of the World Remains Hidden: Roberto Bolańo as an Antiliterary Author

The Chilean author Roberto Bolańo cultivated a contentious (and contradictory) attitude to literature, believing that it conceals the fear and self-interest that coordinates its meaningfulness. For Bolańo, great writers should face the abyss of meaninglessness while standing tall, a directive which prohibits drawing conclusions that might ultimately be elevated to the level of fact. Instead, Bolańo commits to a category of truth that cannot be described by inscribing its contingent effects in his writing through what I will call his ‘antiliterature.’ Acknowledging this inaccessible truth, Bolańo’s writing reveals an aversion to all-encompassing literary forms that can be seen in the same light as Jacques Lacan’s term ‘antiphilosophy,’ describing the French psychoanalyst’s position against philosophy. Just as Lacanian antiphilosophy continues to contribute to twenty-first-century philosophical critiques, Bolańo’s antiliterature renders possible novel literary trajectories. Bolańo’s 2009 novel 2666 exemplifies his antiliterary approach, subverting the literary genre of crime fiction by refusing to supply an object to fulfil the reader’s desire for closure and by universalising guilt