1,720,985 research outputs found
Self-template derived ZnFe2O4 double-shell microspheres for chemresistive gas sensing
No full textPorous ZnFe2O4 double-shell, york-shell, and solid microspheres are synthesized using a combination of hydrothermal method and thermal treatment (carried out at appropriate temperature determined via gravimetry). The specific surface area is varied by adopting different heating rates during the thermal treatment; double-walled structure is formed at higher heating rates. Gas sensors based on ZnFe2O4 double-shell microspheres showed a promising response (when compared to york-shell and solid microspheres), when tested with similar to 20 ppm acetone (R-air/R-gas = 13.6). There is little or no response to interferential gases, including ethanol, methanol, xylene, toluene, benzene, carbon monoxide, hydrogen sulfide and nitrogen dioxide. The gas sensor showed an almost linear response to acetone concentration and a low detection limit for acetone of 0.13 ppm (making it compliant with analytic requirements for acetone-threat or diabetes-breathalyzer tests). The observed gas sensing performance (includes response time similar to 6-10 s at 206 degrees C operating temperature and good cyclability) suggests that the ZnFe2O4 double shell microspheres presented here are prospective sensing materials for acetone detection. (C) 2018 Elsevier B.V. All rights reserved
Aliovalent Fe(iii)-doped NiO microspheres for enhanced butanol gas sensing properties
No full textFe-Doped NiO multi-shelled microspheres have been synthesized via a facile hydrothermal reaction. Various characterization techniques were introduced to investigate the structure and morphology of the as-prepared Fe-doped NiO multi-shelled microspheres. SEM and TEM observations showed that NiO microspheres are about 500 nm in diameter and with three shells. The Fe-doped NiO multi-shelled microspheres were investigated systematically as gas sensing materials for chemiresistive semiconductor-based gas sensors. The results showed that the 1.92 at% Fe-doped NiO (1.92Fe-NiO) multi-shelled microspheres exhibited enhanced gas sensing performance compared to the pure NiO multi-shelled microspheres. The gas response of 1.92Fe-NiO multi-shelled microspheres to 100 ppm butanol was 45.1 at 140 degrees C, which revealed a remarkable improvement over the pure NiO multi-shelled microspheres (6.80). The increased response of 1.92Fe-NiO multi-shelled microspheres may be attributed to the incorporation of Fe ions into NiO nanocrystals, which adjusted the carrier concentration and caused an increase in the oxygen species on the adsorbed surface. Therefore, the Fe-doped NiO multi-shelled microspheres should be a promising material for high performance butanol gas sensors
Aliovalent Fe(iii)-doped NiO microspheres for enhanced butanol gas sensing properties
No full textFe-Doped NiO multi-shelled microspheres have been synthesized via a facile hydrothermal reaction. Various characterization techniques were introduced to investigate the structure and morphology of the as-prepared Fe-doped NiO multi-shelled microspheres. SEM and TEM observations showed that NiO microspheres are about 500 nm in diameter and with three shells. The Fe-doped NiO multi-shelled microspheres were investigated systematically as gas sensing materials for chemiresistive semiconductor-based gas sensors. The results showed that the 1.92 at% Fe-doped NiO (1.92Fe-NiO) multi-shelled microspheres exhibited enhanced gas sensing performance compared to the pure NiO multi-shelled microspheres. The gas response of 1.92Fe-NiO multi-shelled microspheres to 100 ppm butanol was 45.1 at 140 degrees C, which revealed a remarkable improvement over the pure NiO multi-shelled microspheres (6.80). The increased response of 1.92Fe-NiO multi-shelled microspheres may be attributed to the incorporation of Fe ions into NiO nanocrystals, which adjusted the carrier concentration and caused an increase in the oxygen species on the adsorbed surface. Therefore, the Fe-doped NiO multi-shelled microspheres should be a promising material for high performance butanol gas sensors
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
Facile synthesis of In2O3 microcubes with exposed {100} facets as gas sensing material for selective detection of ethanol vapor
No full textThe rational designs of metal oxides with well exposed facets have stimulated tremendous attentions due to their vital importance for practical applications. In2O3 microcubes (In2O3 MCs) were synthesized by a simple hydro-thermal method with cubic structure and high surface area. Various techniques were employed for characterization of the structure and morphology of the as-prepared In2O3 MCs. The as-synthesized In2O3 MCs, when utilized as gas sensing material, exhibited high sensitivity and selectivity towards ethanol vapor. Such outstanding gas sensing performance of In2O3 MCs benefits from their large specific surface area and exposure of {1 0 0} facets. (C) 2017 Elsevier B.V. All rights reserved
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
- …
