156 research outputs found

    Are compliance constants ill-defined descriptors for weak interactions?

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    Just as the potential energy can be written as a quadratic form in internal coordinates, so it can also be expanded in terms of generalized forces. The resulting coefficients are termed compliance constants. In this article, the suitability of compliance constants as non-covalent bond strength descriptors is studied (a) for a series of weakly bound hydrogen halide–rare gas complexes applying a configuration interaction theory, (b) for a double stranded DNA 4-mer using approximate density functional methods and finally (c) for a double stranded DNA 20-mer using empirical force fields. Our results challenge earlier studies, which concluded the inappropriateness of compliance constants as soft matter descriptors. The discrepancy may be ascribed, inter alia, to the application of an oversimplified potential function in these earlier studies, assuming a central forces approximation

    molecular recognition of naphthalene diimide ligands by telomeric quadruplex dna the importance of the protonation state and mediated hydrogen bonds

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    How important are mediated hydrogen bonds in terms of molecular recognition? Compliance Constants (relaxed force constants) give the answer

    Novel atrazine-binding biomimetics inspired to the D1 protein from the photosystem II of Chlamydomonas reinhardtii

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    Biomimetic design represents an emerging field for improving knowledge of natural molecules, as well as to project novel artificial tools with specific functions for biosensing. Effective strategies have been exploited to design artificial bioreceptors, taking inspiration from complex supramolecular assemblies. Among them, size-minimization strategy sounds promising to provide bioreceptors with tuned sensitivity, stability, and selectivity, through the ad hoc manipulation of chemical species at the molecular scale. Herein, a novel biomimetic peptide enabling herbicide binding was designed bioinspired to the D1 protein of the Photosystem II of the green alga Chlamydomonas reinhardtii. The D1 protein portion corresponding to the QB plastoquinone binding niche is capable of interacting with photosynthetic herbicides. A 50-mer peptide in the region of D1 protein from the residue 211 to 280 was designed in silico, and molecular dynamic simulations were performed alone and in complex with atrazine. An equilibrated structure was obtained with a stable pocked for atrazine binding by three H-bonds with SER222, ASN247, and HIS272 residues. Computational data were confirmed by fluorescence spectroscopy and circular dichroism on the peptide obtained by automated synthesis. Atrazine binding at nanomolar concentrations was followed by fluorescence spectroscopy, highlighting peptide suitability for optical sensing of herbicides at safety limits

    A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters

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    We report herein the use of a dual catalytic system comprising of a Lewis base catalyst such as quinuclidin-3-ol or 4- dimethylaminopyridine combined with a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react via radical addition with electron-deficient olefins to efficiently form C–C coupled products in a redox neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either boronic esters or the trimeric form of the boronic acids (boroxines) in solution.We are grateful to Novartis Pharma AG (F.L.), the Erasmus Scholarship Scheme (L.G. and S.J.), and the EPSRC (S.V.L., Grants EP/K009494/1, EP/K039520/1, and EP/M004120/1) for financial support. U.K.S. and D.S. are thankful to the University of Leuven for postdoctoral funding and the FWO for a visiting postdoctoral scholarship (U.K.S.) at the University of Cambridge. E.V.V.d.E. would like to thank the Ministry of Education and Science of the Russian Federation for financial support (agreement number 02.a03.0008). We thank Dr. Berthold Schenkel and Dr. Gottfried Sedelmeier for insightful discussions. We thank Merck Rahway USA for the generous gift of the PC(1) photoredox catalyst

    Affection, virtue, pleasure, and profit: Developing an understanding of friendship closeness and intimacy in western and Asian societies

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    The development of friendship understanding has rarely been explored from a cross-cultural perspective. In this study, children and adolescents from Iceland, China, Russia, and the former East Germany were investigated in one longitudinal and three cross-sectional samples. Children from three different Chinese ecologies were interviewed to account for within-culture variation. Participants were interviewed about friendship closeness and intimacy at ages 7, 9, 12, and 15 years. Their statements were scored according to (a) structural-developmental stages and (b) content aspects of friendship reasoning. Results reveal that the development of friendship reasoning of participants from all societies could be captured by the cognitive-structural stages and content categories developed in western cultures. At the same time, distinct cultural differences emerged, especially between the Russian and Chinese participants, on the one hand, and the Icelandic and East German participants, on the other hand. The within-China analyses reveal little differences for the content aspects of friendship understanding between the three ecologies, but differences in the cognitive-structural aspects of friendship reasoning were found. © 2008 The International Society for the Study of Behavioural Development

    The Exhibition as an Experiment: An Analogy and its Implications

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    The analogy of the exhibition as an experiment suggests innovative curatorial approaches that challenge institutional practices. This analogy has however a historical precedence in modernism when itbecame paradigmatic of the exhibitions at the Museum of ModernArt in New York in the 1940s, defining the curatorial approach of its founding director Alfred J Barr. This article considers this early useof the analogy of the exhibition as an experiment and further reflects on its redefinition at the turn of the 20th century by examining how both the notions of the exhibition and of the experiment havechanged over time. In particular, the article examines the different meanings and practices inferred by the concepts of the exhibition and the experiment in the first decades of the 20th century and in the present. It outlines how correspondences between cultural and scientific paradigms can be deployed to tease unacknowledged synergies between two modes of knowledge production (i.e. the art exhibition and the experiment) and address questions of presentness, authority and legitimacy that they imply

    “Wearing me place on me face”: Scousebrows, placemaking and everyday creativity

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    This paper emerges from a multidisciplinary research project called “Brews and Brows: Shaping Stories from Eyebrows to Scousebrows” that entailed gathering stories about eyebrow grooming from women and men from the city of Liverpool, UK, and creating a new taxonomy of the eyebrow where none currently exists. The point of departure for this paper is to challenge the negative commentary on the Scousebrow in the press and social media by engaging people in discussions surrounding the personal significance of eyebrow shaping and styling. In challenging this denigration, this paper uses data from in-depth interviews with eyebrow artists and clients and ethnographic interviews at a four-day event held in Liverpool. This paper argues that the everyday (little c) creative practice of eyebrow grooming is not only an important part of crafting and performing identity, particularly for Scouse women, but also an example of bottom-up placemaking in the city of Liverpool

    Crafting place: Women’s everyday creativity in placemaking processes

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    Amid a resurgence of domestic craft, this article contends that everyday creative practices of women are part of placemaking processes in the creative city. Specifically, the research focuses on Liverpool in the Northwest of England, the so-called (and self-proclaimed) ‘centre of the creative universe’. This article utilized in-depth semi-structured interviews with members of knitting groups and the city centre Women’s Institute to explore how women use craft practice to create a sense of self and attachment to place. The idea of women gathering to craft is enduring, and is examined here to understand affective labour and the role that creativity plays in the urban experience of women. It is argued that the groups demonstrate a lack of engagement with the wider market and official placemaking processes, but instead demonstrate an element of self-valorization. The article challenges thinking around culture-led placemaking in cities like Liverpool, where discourses of creativity have been used as a driver for regeneration by shifting the emphasis onto seemingly banal settings on the edges of the so-called creative city. While urban placemakers have been more recently concerned with developing hubs of creative industries, the role of these groups that are not producing a profitable ‘product’ should not be underestimated or exploited

    Efficacy of Messenger RNA-1273 Against Severe Acute Respiratory Syndrome Coronavirus 2 Acquisition in Young Adults From March to December 2021

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    BACKGROUND: The efficacy of messenger RNA (mRNA)-1273 against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is not well defined, particularly among young adults. METHODS: Adults aged 18-29 years with no known history of SARS-CoV-2 infection or prior vaccination for coronavirus disease 2019 (COVID-19) were recruited from 44 US sites from 24 March to 13 September 2021 and randomized 1:1 to immediate vaccination (receipt of 2 doses of mRNA-1273 vaccine at months 0 and 1) or the standard of care (receipt of COVID-19 vaccine). Randomized participants were followed up for SARS-CoV-2 infection measured by nasal swab testing and symptomatic COVID-19 measured by nasal swab testing plus symptom assessment and assessed for the primary efficacy outcome. A vaccine-declined observational group was also recruited from 16 June to 8 November 2021 and followed up for SARS-CoV-2 infection as specified for the randomized participants. RESULTS: The study enrolled 1149 in the randomized arms and 311 in the vaccine-declined group and collected >122 000 nasal swab samples. Based on randomized participants, the efficacy of 2 doses of mRNA-1273 vaccine against SARS-CoV-2 infection was 52.6% (95% confidence interval, -14.1% to 80.3%), with the majority of infections due to the Delta variant. Vaccine efficacy against symptomatic COVID-19 was 71.0% (95% confidence interval, -9.5% to 92.3%). Precision was limited owing to curtailed study enrollment and off-study vaccination censoring. The incidence of SARS-CoV-2 infection in the vaccine-declined group was 1.8 times higher than in the standard-of-care group. CONCLUSIONS: mRNA-1273 vaccination reduced the incidence of SARS-CoV-2 infection from March to September 2021, but vaccination was only one factor influencing risk. CLINICAL TRIALS REGISTRATION: NCT04811664
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