1,720,956 research outputs found
Modeling Hybrid Nanosystems of Interacting Molecules and Plasmonic Nanoparticles
Full text linkStrong light-matter coupling provides a clean and effective means to modify the accessible energy landscapes of molecular species, impacting both spectroscopic observables and chemical reactivity. Beyond optical cavities, localized plasmonic modes supported by noble metal nanostructures have become widely used in this field. The ability to tune and exploit the resulting light-matter hybrid states (polaritons, or more precisely, plexcitons) for manipulating molecular properties and behavior has sparked the flourishing area of Polaritonic Chemistry.
This thesis focuses on modeling complex systems of molecules and plasmonic nanoparticles, characterized by multiple interactions between the constituent species. The most distinctive feature is the coupling of molecular (electronic) excitations with plasmonic modes, enabling the mixing of plasmonic and molecular characters in the resulting hybrid eigenstates. Since many molecules, relatively close to each other, can be collectively coupled to the same plasmon, intermolecular interactions must also be considered.
A novel, state-of-the-art strategy was developed to evaluate molecule-plasmon coupling for each individual dye. This strategy was applied to both well-known nanohybrids and molecular substrates that had not yet been examined for polaritonic applications.
For the well-known nanohybrids, the results confirmed that the implemented extensions, compared to standard quantum optics models, not only allowed for more refined and realistic modeling but also provided valuable insights for guiding the interpretation of available experimental data and directing the design of further investigations. These insights included the inhomogeneous contributions within a molecular assembly collectively coupled to the same plasmon mode and the intermixing of spectral branches that are well-separated for the isolated chromophore.
For the molecular substrates not previously examined for polaritonic applications, a thorough investigation of the relevant excited states revealed a highly dynamic scenario. This finding paves the way for ongoing explorations of the impact of interactions with tailored plasmonic platforms
Molecularly Detailed View of Strong Coupling in Supramolecular Plexcitonic Nanohybrids
No full textPlexcitons constitute a peculiar example of light-matter hybrids (polaritons) originating from the (strong) coupling of plasmonic modes and molecular excitations. Here we propose a fully quantum approach to model plexcitonic systems and test it against existing experiments on peculiar hybrids formed by Au nanoparticles and a well-known porphyrin derivative, involving the Q branch of the organic dye absorption spectrum. Our model extends simpler descriptions of polaritonic systems to account for the multilevel structure of the dyes, spatially varying interactions with a given plasmon mode, and the simultaneous occurrence of plasmon-molecule and intermolecular interactions. By keeping a molecularly detailed view, we were able to gain insights into the local structure and individual contributions to the resulting plexcitons. Our model can be applied to rationalize and predict energy funneling toward specific molecular sites within a plexcitonic assembly, which is highly valuable for designing and controlling chemical transformations in the new polaritonic landscapes
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
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
Probing the environmental sensitivity of thymine C=O vibrations through infrared spectra simulations
No full textInfrared spectroscopy is widely used to probe the structural organization of biologically relevant molecules, including peptides, proteins, and nucleic acids. The latter show significant structural diversity, and specific infrared bands provide insights into their conformational ensembles. Among DNA/RNA infrared bands, the CO stretching modes are especially useful, as they are sensitive to the distinct structural arrangements within nucleic acids. However, the relationship between different spectral lineshapes and specific structural features is often non-trivial, especially in highly flexible systems such as single-stranded DNA. In this work, we propose a hybrid quantum-classical computational approach based on the perturbed matrix method for calculating infrared bands in nucleic acids. This approach, previously applied to calculate CO stretching modes in peptides and proteins, is applied here for the first time to DNA. Specifically, using molecular dynamics simulations combined with density functional theory (B3LYP) calculations, we calculate the spectrum arising from the two CO stretching modes of the thymine base, both in water and deuterated water, with a specific focus on the sensitivity of the spectral lineshape to the systems' conformational ensemble. We compute the spectra for 1-methylthymine, thymidine 5 '-monophosphate, and a single-stranded oligomer composed of ten thymine bases, and critically compare them to their corresponding experimental signals. Our results indicate that the difference in the relative intensity of the two bands experimentally observed between the spectrum of a single solvated base and that of the oligomer, also captured in the calculated spectra, results from stacking and hydrogen bonding interactions among the bases
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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