1,720,987 research outputs found
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
Development of Organic Polymer Interfacial Materials to Improve the Stability of Solution-Processed Photovoltaic Cells
No full textPhotovoltaic cells have been considered as a promising alternative of clean and renewable energy production to solve serious environmental and energy problems. To commercialize the photovoltaic devices, high stability should be significantly considered because there are several issues limiting the stability of photovoltaic devices such as moisture, oxygen, reaction and diffusion of electrode, irradiation, heating, and mechanical stress. Interfacial materials could be one of the crucial strategies to enhance the stability of solar cells due to their key roles such as energy level tuning at the organic/electrode interface, improving charge transporting and electrode selectivity, introducing optical effects to enhance light-trapping, and modulating bulk heterojunction (BHJ) morphology evolution. Despite the frantic efforts to develop new organic interfacial materials, more stable materials are still required.
In chapter 1, an overview of photovoltaics and interfacial materials in photovoltaics are generally explained.
In chapter 2, rational designed small molecule semiconductors (SMs) were investigated for use as donors in organic solar cells through truncation approach. In general, SMs have many advantages over polymers including well-defined molecular structures, monodispersity, and no batch-to-batch dependence. Although SM semiconductors can be designed by truncation from polymers, such examples have rarely been reported. Herein we designed SM semiconductors by truncating a representative polymer, Poly[4-(4,8-bis((2-hexyldecyl)oxy)benzo[1,2-b:4,5-b’]dithiophen-2-yl)-alt-benzo[c][1,2,5]thiadiazole] (PBDTBT). Based on density functional theory (DFT) calculations, 2,1,3-benzothiadiazole (BT) was chosen as an electron acceptor subunit instead of thieno[3,4-c]pyrrole-4,6-dione (TPD). The SM semiconductors were end-capped with pyridine derivatives. In particular, the benzyloxypyridine-capped semiconductor (SM1) exhibited power conversion efficiency (PCE) of 1.92% which is higher than those shown by the corresponding polymer PBDTBT (0.90% and 1.71%).
In chapter 3, newly designed polymers were applied to the dopant-free hole transporting materials (HTMs) in perovskite solar cells (PSCs) with maintaining high stability. To overcome device instability without deteriorating PCE, dopant-free HTMs are needed to separate the air-sensitive perovskite layer from extrinsic factors which induce its degradation. Herein we developed novel conjugate polymers of benzo[1,2-b:4,5-b′]dithiophene (BDT) and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) for use as HTMs without dopants. The pBDT-BODIPY polymer allows individual “dialing” of the HOMO or LUMO levels with small modifications to the molecular structure, enabling the study of the impact of the frontier molecular orbital on PSC performance. Different alkyl chains on BDT can minutely adjust the HOMO level, and meso-substituents on BODIPYs can selectively set the LUMO level of the resulting polymers. Application of BODIPY-containing polymer into the perovskite solar cell as an HTM leads to a high PCE value (16.02%) and exceptional solar cell stability shown by the fact that over 80% of its original PCE value maintained after 10 days under ambient air conditions.
In chapter 4, a series of polyethyleneimine (PEI) derivatives were synthesized for use as cathode interfacial materials (CIMs) in organic solar cells. Despite an excellent contribution to the development of fullerene-based solar cells (FSCs), PEI as a representative CIM shows inferior stability in nonfullerene-based solar cells (NFSCs) due to reactive amines. To solve this problem, there are a few attempts. Nevertheless, a clear reason underlying the side reaction is not demonstrated yet, and more stable NFSCs and more facile synthesis of new CIMs are required. Here, we synthesized new PEI derivatives through a simple imine formation reaction to control work function values and a simple methylation reaction to shield reactivity of a secondary amine. To confirm the possibility for use as CIMs, the density functional theory (DFT) calculation and the fundamental characterization was conducted. These PEI derivatives applied to CIMs in FSCs and NFSCs. The highest power conversion efficiency (PCE) values are achieved 9.61% in FSCs and 12.34% in NFSCs, respectively, which is better performance compared to ZnO-based devices. Furthermore, the methylated CIMs-containing NFSCs show improved thermal stability as well as enhancement of the device performance after thermal treatment.Docto
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
Development of Chiral Pyridine-Dihydroisoquinoline (PyDHIQ) Ligands and Application to Palladium-Catalyzed Asymmetric Conjugate Additions
No full textTransition metal-catalyzed asymmetric conjugate additions have been widely applied to the construction of tertiary or quaternary stereocenters. Especially, palladium catalysis in the reaction could provide operationally practical transformations using air- and moisture-stable catalytic systems using arylboronic acids. Moreover, quaternary stereocenters could be generated in the palladium catalytic system with high enantioselectivity by use of chiral bidentate (N,N)-ligands such as PyOx or BOx ligand scaffolds. Nevertheless, the substrates in the palladium-catalyzed conjugate addition are still limited. Heterocyclic acceptors or heterocyclic nucleophiles were underdeveloped despite their numerous bioactivities. We anticipated that the development of well-designed chiral ligands could address these challenges remained in the field, and chiral dihydroisoquinoline scaffolds were chosen for the potential ligand candidates in the palladium-catalyzed conjugate addition.
This thesis describes the development of chiral pyridine-dihydroisoquinoline (PyDHIQ) ligands and their application to palladium-catalyzed asymmetric conjugate addition. Chapter 2 explores the design and synthesis of chiral PyDHIQ ligands. Initial developments of palladium-catalyzed asymmetric conjugate addition using synthesized PyDHIQ ligands were also described. In chapter 3, the substrates were successfully expanded to 2-substituted chromones in aqueous media, affording tetrasubstituted stereocenters at the C2 position of chromanones. Notably, this is the first example of asymmetric conjugate addition to 2-substituted chromanones. In chapter 4, the developed catalytic system was applied to β-substituted α,β-unsaturated δ-lactams, providing chiral β-quaternary δ-lactams. This methodology was successfully applied to the first asymmetric formal synthesis of (-)-picenadol. In addition, it was found that there are attractive noncovalent interactions between N-Cbz-δ-lactams and PyDHIQ ligands in an enantioselectivity-determining step by DFT calculations and NCI plot analysis.Docto
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
Ethenolysis of a, b-Unsaturated Ester by NHC-Ruthenium Catalysts
No full textEthenolysis of , - unsaturated ester has a potential as sustainable acrylate producing method. Especially, dimethyl maleate, cheap and abundant source, is one of the attractive substrates of ethenolysis of , - unsaturated
ester. However, ethenolysis of electron-deficient alkene is known to challenging reaction and still underexplored. In these reports, report of the The Togni group reports the highest TON (5200) with HG-2 and polyphenol resin on ethenolysis of , - unsaturated ester. However, it is still a low TON to be economically feasible. So, in this thesis, other catalysts developed for ethenolysis (F-ImPy, F-aImPy, AAOC) that have stronger donor ability were tested to increase TON. In contrast to our expectation, all the catalysts show lower TON than HG-2 although the condition optimization and the test of some additives (polyphenol, BHT, PCy3-CuCl). By the results of reaction time optimization experiments, it is presumed that a decomposition of the catalysts is reason for lower TON.Maste
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