5,679 research outputs found

    Dynamic Characterization of Crystalline Supramolecular Rotors Assembled through Halogen Bonding

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    A modular molecular kit for the preparation of crystalline molecular rotors was devised from a set of stators and rotators to gain simple access to a large number of structures with different dynamic performance and physical properties. In this work, we have accomplished this with crystalline molecular rotors self-assembled by halogen bonding of diazabicyclo[2.2.2]octane, acting as a rotator, and a set of five fluorine-substituted iodobenzenes that take the role of the stator. Using variableerature 1H T1 spin-lattice relaxation measurements, we have shown that all structures display ultrafast Brownian rotation with activation energies of 2.4-4.9 kcal/mol and pre-exponential factors of the order of (1-9) × 1012 s-1. Line shape analysis of quadrupolar echo 2H NMR measurements in selected examples indicated rotational trajectories consistent with the 3-fold or 6-fold symmetric potential of the rotator

    Psilocybin occasioned mystical‐type experiences

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    Objective Research into psychedelic therapy models has shown promise for the treatment of specific psychiatric conditions. Mystical‐type experiences occasioned by psilocybin have been correlated with therapeutic benefits and long‐term improvements in positive mental outlook and attitudes. This article aims to provide an overview of the topic, highlight strengths and weaknesses in current research, generate novel perspectives and discussion, and consider future avenues for research. Design This narrative review was designed to summarise and assess the state of research on psilocybin occasioned mystical‐type experiences and applications for the treatment of specific psychiatric conditions. Results Contemporary methods on the quantification of mystical‐type experiences and their acute subjective effects are discussed. Recent studies provide some understanding of the pharmacological actions of psychedelics although the neurological similarities and differences between spontaneous and psychedelic mystical‐type experiences are not well described. Applicability to modern clinical settings is assessed. Potential novel therapeutic applications include use in positive psychology interventions in healthy individuals. Conclusions Since 2006 significant advancements in understanding the therapeutic potential of psilocybin‐assisted psychotherapy have been made; however, more work is required to understand the neuromechanistic processes and applicability in modern clinical settings. Despite promising results in recent studies, funding issues for clinical trials, legal concerns and socio‐cultural resistance provide a counterpoint to experimental evidence

    Three body systems with strangeness and exotic systems

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    We report on four Σ\Sigma's and three Λ\Lambda's, in the 1500 - 1800 MeV region, as two meson - one baryon S-wave (1/2)+(1/2)^+ resonances found by solving the Faddeev equations in the coupled channel approach, which can be associated to the existing SS = -1, JP=1/2+J^P= 1/2^+ low lying baryon resonances. On the other hand we also report on a new, hidden strangeness NN^* state, mostly made of KKˉNK \bar{K} N, with mass around 1920 MeV, which we think could be responsible for the peak seen in the γpK+Λ\gamma p \to K^+ \Lambda around this energy. Finally we address a very novel topic in which we show how few body systems of several ρ\rho mesons can be produced, with their spins aligned up to J=6, and how these states found theoretically can be associated to several known mesons with spins J=2,3,4,5,6.Comment: Talk at the 21st European Conference on Few Body Problems in Physics, Salamanca, Sep. 201

    A new perspective on the Faddeev equations and the KˉNN\bar{K}NN system from chiral dynamics and unitarity in coupled channels

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    We review recent work concerning the KˉN\bar{K}N interaction and Faddeev equations with chiral dynamics which allow us to look at the KˉNN\bar{K}NN from a different perspective and pay attention to problems that have been posed in previous studies on the subject. We show results which provide extra experimental evidence on the existence of two Λ(1405)\Lambda(1405) states. We then show the findings of a recent approach to Faddeev equations using chiral unitary dynamics, where an explicit cancellation of the two body off shell amplitude with three body forces stemming from the same chiral Lagrangians takes place. This removal of the unphysical off shell part of the amplitudes is most welcome and renders the approach unambiguous, showing that only on shell two body amplitudes need to be used. With this information in mind we use an approximation to the Faddeev equations within the fixed center approximation to study the KˉNN\bar{K}NN system, providing answers within this approximation to questions that have been brought before and evaluating binding energies and widths of this three body system. As a novelty with respect to recent work on the topic we find a bound state of the system with spin S=1, like a bound state of Kˉ\bar{K}-deuteron, less bound that the one of S=0, where all recent efforts have been devoted. The width is relatively large in this case, suggesting problems in a possible experimental observation.Comment: 18 pages, 7 figures, one misprint corrected, Nuclear Physics A in pres
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