1,720,999 research outputs found
Pyrrole βC−B−N Fused Porphyrins: Molecular Structures and Opto‐Electrochemical Studies
Full text linkHerein, we report the design, synthesis, structure, and electrochemical study of doubly βC-B-N fused Ni(II) porphyrins (1-trans, 1-cis, 2-trans, and 2-cis). These compounds have been synthesized from A2B2 type dipyridyl Ni(II) porphyrins (Ar=Ph for 1 a; Ar=C6F5 for 2 a) via Lewis base-directed electrophilic aromatic borylation reactions. The solution state structures of these compounds have been established using 1H NMR, 11B NMR, 1H-1H COSY, 1H-13C HSQC, and 19F-13C HSQC NMR techniques. Single crystal X-ray analysis have revealed that 1-trans, 1-cis, and 2-trans adopt ruffled conformations, with alternate meso-carbons on the opposite sides of the mean porphyrin plane. The Soret bands in the absorption spectra of the B-N fused molecules are ~40 nm redshifted compared to unfused Ni(II) porphyrin precursors. The B-N fusion have diminished the redox potential of fused porphyrins. Although 1-trans and 1-cis, show four oxidation processes, 2-trans and 2-cis show only three oxidation processes. DFT studies have revealed that the tetrahedral geometry of the boron has induced a twist in the π-conjugation, which destabilizes the HOMO and stabilizes the LUMO in 1-trans, 1-cis, 2-trans, and 2-cis
Axial chirality-induced rigidification in aminoboranes enhances persistent room-temperature phosphorescence and circularly polarized luminescence
No full textLong-lived triplet exciton harvesting materials are of immense interest for applications in bioimaging, optoelectronics, anticounterfeiting, and sensing. However, achieving persistent room-temperature phosphorescence (pRTP) in metal-free systems remains a significant challenge. Herein, we present purely organic axially chiral aminoboranes (R/S-(BN)2) with enhanced pRTP properties and circularly polarized luminescence (CPL). By introducing axial chirality, the dual-core (R/S-(BN)2) system achieves steric-hindrance-caused rigidity, which restricts molecular motions, leading to superior phosphorescence properties. Notably, R-(BN)2 demonstrates a phosphorescence quantum yield (ΦP) of 9.2% (S-(BN)2 : ΦP = 8.7%) and an extended lifetime of 0.9 sec at room temperature, significantly outperforming its mono-core counterpart (BN)1 (ΦP = 3.0% and τP = 0.6 s). Theoretical analysis corroborates the observed improvements, revealing the synergistic role of borylation and axial chirality in stabilizing triplet states. Furthermore, the axially chiral aminoboranes exhibited CPL in dichloromethane solutions with a dissymmetry factor of ~10-3. These findings highlight the potential of axially chiral frameworks in designing efficient metal-free pRTP materials, as demonstrated in the security writing application, further paving the way for their use in bioimaging, anti-counterfeiting technologies, and next-generation organic electronics
Phytochemicals for Preventing and Treating Chronic Diseases
No full textThe rise of chronic noncommunicable diseases (NCDs) as the leading threat to global health is clear, as these conditions cause nearly two-thirds of deaths worldwide, mostly in low and middle-income countries. NCDs are chronic conditions requiring ongoing medical care and lifestyle changes for at least 1 year. Diet is one factor contributing to NCDs. While diets high in fruits, vegetables, nuts, and whole grains protect against developing several NCDs, increased mortality has been associated with a high intake of fried food, red meat, and processed meats. Phytochemicals, plant-derived bioactive compounds, have gained attention for their potential to benefit health and prevent or treat NCDs. Interestingly, phytochemicals interact with the gut microbiota that colonizes the human digestive system, which plays a crucial role in maintaining health and preventing diseases like metabolic syndrome and associated risk factors like insulin resistance and hypertension. This chapter aims to provide a comprehensive understanding of the role of phytochemicals in some chronic diseases and their prevention.Fil: Guerrero Flores, Gerardo Nataniel. Universidad Adventista del Plata. Secretaría de Ciencia y Técnica. Centro Interdisciplinario de Investigaciones En Ciencias de la Salud y del Comportamiento.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Carlino, Belén. Universidad Adventista del Plata. Secretaría de Ciencia y Técnica. Centro Interdisciplinario de Investigaciones En Ciencias de la Salud y del Comportamiento.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Gili, Rocio Victoria. Universidad Adventista del Plata. Secretaría de Ciencia y Técnica. Centro Interdisciplinario de Investigaciones En Ciencias de la Salud y del Comportamiento.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Leeson, Sara. Universidad Adventista del Plata. Secretaría de Ciencia y Técnica. Centro Interdisciplinario de Investigaciones En Ciencias de la Salud y del Comportamiento.; ArgentinaFil: Mayta, Martín Leonardo. Universidad Adventista del Plata. Secretaría de Ciencia y Técnica. Centro Interdisciplinario de Investigaciones En Ciencias de la Salud y del Comportamiento.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin
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
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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