1,721,021 research outputs found
Investigation of the gate oxide integrity of the nitrided gate oxide using nitrogen implantation into polysilicon gate
No full textThe effect of nitrogen incorporation into the gate oxide by using shallow implantation of nitrogen and drive-in process
No full textA new series of random conjugated copolymers containing 3,4-diphenyl-maleimide and thiophene units for organic photovoltaic cell applications
No full text[[abstract]]A series of random conjugated copolymers (labeled PMLTQT, PMLT2T, and PMLT3T) consisting of 3,4-diphenyl-maleimide and various thiophene derivatives has been designed and synthesized via Stille cross-coupling for application in polymer solar cells. These copolymers were readily soluble in common organic solvents, thermally stable from 405 to 437 degrees C upon heating, and exhibited good absorption in the UV and visible regions from 300 to 650 nm. The intensities of the PL emission spectra of these copolymers in a solid film were dramatically quenched by the addition of 50 wt% [6,6]-phenyl C-61 butyric acid methyl ester (PC61BM). Their electrochemical properties indicated that the highest occupied molecular orbital levels of these copolymers were in the range of -5.63-5.73 eV, characteristic of better air stability and a high open-circuit voltage (V-oc) suitable for application to photovoltaic cells. Bulk heter-ojunction photovoltaic devices composed of an active layer of electron-donor copolymers blended with the electron acceptor PC61BM or [6,6]-phenyl C-71 butyric acid methyl ester (PC71BM) at a weight ratio of 1:3 were investigated. The photovoltaic device containing PMLT3T and PC71BM (1:3, w/w) as the active layer afforded the best performance among these copolymers, with a V-oc of 0.74 V, J(sc) of 7.4 mA cm(-2) and a PCE of 1.20% under AM 1.5 G simulated solar light. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.[[note]]SC
Synthesis of 9,9-Bis(4-aminophenyl)fluorene-Based Benzoxazine and Properties of Its High-Performance Thermoset
No full text[[abstract]]A benzoxazine (P-bapf) based on 9,9-bis(4-aminophenyl) fluorene (BAPF), phenol, and formaldehyde was successfully prepared using two-pot and one-pot procedures. In the two-pot approach, BAPF initially reacted with 2-hydroxybenzaldehyde, leading to 9,9-bis(4-(2-hydroxybenzylideneimino) phenyl) fluorene. The imine linkages of 9,9-bis(4-(2-hydroxybenzylideneimino) phenyl) fluorene were then reduced by sodium borohydride, forming 9,9-bis(4-(2-hydroxybenzylamino) phenyl) fluorene. Finally, paraformaldehyde was added to induce ring closure condensation, forming benzoxazine (P-bapf). In the one-pot approach, P-bapf was obtained directly by reacting BAPF, phenol, and paraformaldehyde in various solvents. Among the solvents, we found that using toluene/ethanol (2/1, v/v) as a solvent leads to the best purity and yield. No gelation was observed in the preparation. The structure of the resulting benzoxazine was confirmed by H-1, C-13, H-1-H-1 and H-1-C-13 NMR spectra. P-bapf exhibits a photoluminescent emission at 395 nm under an excitation of 275 nm. After curing, the resulting P-bapf thermoset exhibits T-g as high as 236 degrees C, and the T-g can be further increased to 260 degrees C by copolymerization with an equal equivalent of cresol novolac epoxy. The 5% degradation temperature of the P-bapf thermoset reaches as high as 413 degrees C (N-2) and 431 degrees C (air). The refractive index at 589 nm is as high as 1.70, demonstrating a high refractive index characteristic of fluorene linkage. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 2201-2210, 2012[[note]]SC
Bottom-Contact n-Channel Organic Thin-Film Transistors with Naphthalene-Based Derivatives
No full text[[abstract]]We investigated bottom-contact organic thin-film transistors based on n-benzyl naphthalene 1,4,5,8-tetracarboxylic diimides. The electrical characteristics were tested in both air and vacuum environments. n-Type semiconductors which are modified by fluorinated imide can be operated in ambient environment. The close packing of the fluorinated ester imide group leads to carrier mobility as high as 1.6x10(-2) cm(2) V(-1) s(-1). The short distance between each molecule can be found via a single-crystal structure.[[note]]SC
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
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