1,720,980 research outputs found
Live long and phosphor: extending absorptive cross-sections and excited-state lifetimes through benzannulation
No full textThere are several strategies in modifying the electronic structure of molecules. Functional group modification is perhaps the most used approach. In this thesis, I explore a different approach through the expansion of ligand π-systems by fusing benzene rings (benzannulation). Benzannulation introduces physicochemical and photophysical changes in molecules without significant changes in the parent framework. In this work, I use computational analysis to investigate the impact of benzo-fused pyridines, quinoline and phenanthridine. Phenanthridine introduces a lower-lying unoccupied molecular orbital (LUMO) compared with quinoline, red-shifting the absorption spectra of complexes. Combining phenanthridines with π-donor ligands enabled the isolation of iron complexes with panchromatic absorption. In addition, benzannulation enables more efficient mixing between the excited singlet and triplet states facilitating the direct Tn←S0 transition. Interestingly, the luminescent properties of the complexes supported by phenanthridine exhibit blue-shifted emission compared with the quinoline-supported analogues. The enhanced rigidity provided by phenanthridine contributes to the observed higher energy shift.
Building on these findings, a series of new phenanthridine-containing ligands and their boron, zinc and platinum complexes were then pursued. Some of these complexes exhibit long-live emissive excited states originating from triplet states. In addition, new phenanthridine precursors bearing water-soluble and surface-anchoring groups were introduced. Finally, the antineoplastic activity of Pt(II) complexes supported by N^N^O ligands was explored, leading to the discovery of complexes with enhanced cytotoxicity compared with cisplatin both in dark and upon exposure to light.February 202
The molecular structure of monofluorobenzaldehydes
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Previous issue date: 6The pure rotational spectra of 2- and 3-fluorobenzaldehyde have been investigated using a chirped pulse Fourier transform microwave (FTMW) spectrometer in the range of 8-18 GHz and a Balle-Flygare FTMW spectrometer in the range of 4-26 GHz. As in a previous study of monofluorobenzaldehydes,footnote{Jos'{e} L. Alonso and Rosa M. Villama~{n}'{a}n, J. Chem. Soc., Faraday Trans. 2, 1989, 85(2), 137-149} only transitions due to a single planar conformer were observed for 2-fluorobenzaldehyde (O-trans) whereas two planar conformers (O-trans and O-cis) of 3-fluorobenzaldehydes were confirmed. Transitions due to the seven unique C isotopologues of each of the three molecules have been observed for the first time. Their rotational constants were used to derive the effective ground state (r) and substitution (r) structures. The results compare favourably with the equilibrium (r) geometries which were determined following geometry optimization at the MP2/aug-cc-pVTZ level of theory
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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