1,720,989 research outputs found
Active-template synthesis of small functionalised rotaxanes for sensing applications
No full textInterlocked molecules, the archetypal examples of which are catenanes, and rotaxanes, have progressed over the last half-century from a significant synthetic challenge to readily accessible chemical species. The interest for these supramolecular architectures, which started from a purely aesthetic point of view, has further developed due to the high degree of freedom between its individual components. Controlling this motion via chemical or physical stimuli has resulted in the development of many stimuli-responsive interlocked systems with applications in wide range of field such as switches, molecular machinery and sensing. The latter is of particular interest as the mechanical bond within a catenane or rotaxane molecule creates a well-defined three-dimensional environment that can be readily functionalised to accommodate a variety of guest molecules. This thesis presents an investigation into the design and synthesis of novel functional rotaxane receptors and their application in the sensing of metal ions, anions and small chiral molecules.The introductory chapter presents the active template approach to interlocked molecules. It highlights its key advantages and outline recent advances that have been made using this methodology. The following three chapters focus on the study of rotaxane receptors synthesised using this approach. Chapter two reports the synthesis of a sulfur-functionalised rotaxane and the investigation of its selective response for Zn2+ ion over other transition metal cations. Chapter three on the other hand focuses on a urea-based rotaxane that binds ion-pairs. This section will introduce preliminary results obtained with a simple model rotaxane before presenting its evolution into a stimuli-responsive receptor. The binding behaviour of both the rotaxane and related non-interlocked axle will be investigated to demonstrate the impact of the mechanical bond on the properties of the receptor. In the fourth chapter, the project was expanded toward chirality and more specifically enantioselective sensing. The development of a novel synthetic route to access functionalised mechanically planar chiral rotaxanes will be presented and it will conclude on preliminary binding studies of simple chiral anionic guest that shows enantioselectivity
The active template approach to interlocked molecules
No full textThe active template approach to interlocked molecules takes advantage of the ability of metal ions to both organize precursor fragments for mechanical bond formation and to mediate the final covalent bond-forming reaction that captures the interlocked structure. Since its inception just a decade ago, this new methodology has expanded rapidly from a single reaction for rotaxane synthesis to a range of metal-mediated bond formations for the synthesis of complex interlocked molecules. In this Review, we introduce the active template concept, its key advantages for the synthesis of interlocked molecules and outline recent advances that have been made using this technology. We will conclude with comments about future directions and challenges
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Characterisation data for An Auxiliary Approach for the Stereoselective Synthesis of Topologically Chiral Catenanes
No full textNMR, CD, HPLC, MS data for novel compounds reported in: Goldup, S. M., Denis, M., Modicom, F., & Lewis, J. E. M. (2019). An auxiliary approach for the stereoselective synthesis of topologically chiral catenanes. Chem, 5(6), 1512-1520. https://doi.org/10.1016/j.chempr.2019.03.008</span
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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