1,720,955 research outputs found
Characterization of sol-gel prepared WO3 thin films as a gas sensor
No full textTungsten trioxide (WO3) thin films have been prepared by the sol-gel process and annealed at different temperatures of 400, 500, 600, and 700 degrees C for 1 h. The morphology, microstructure crystalline structure, and composition of the films have been analyzed using scanning electron microscopy (SEM), x-ray diffraction, Rutherford backscattering spectroscopy (RBS), and x-ray photoelectron spectroscopy (XPS) techniques. The SEM analysis showed that the films annealed at 400 degrees C are smooth and uniform. However, these evolved as granular at an annealing temperature of 500 degrees C. The films annealed at still higher temperatures have two distinct grains of different shapes and sizes. The films annealed below 400 degrees C are amorphous. Annealing at 500 degrees C resulted in the films having polycrystalline structure. RES and XPS characterization have revealed that the films annealed at 400 degrees C are stoichiometric. Annealing above this temperature resulted in the films becoming off-stoichiometric. The electrical resistance of the films annealed at 500 degrees C increased 18 times when exposed to 175 ppb O-3 gas compared to the air exposure, with the response time being as short as 1-2 min. (C) 1999 American Vacuum Society. [S0734-2101(99)08804-1]. RI li , yongxiang/C-5059-200
Investigation on the cross sensitivity of NO2 sensors based on In2O3 thin films prepared by sol-gel and vacuum thermal evaporation
No full textIn2O3 thin films have been prepared from commercially available pure In2O3 powders by high vacuum thermal evaporation (HVTE) and from indium iso-propoxide solutions by sol-gel techniques (SG). The films have been deposited on sapphire substrates provided with platinum interdigital sputtered electrodes. The as-deposited HVTE and SG films have been annealed at 500 degrees C for 24 and I h, respectively. The film morphology, crystalline phase and chemical composition have been characterised by SEM, glancing angle XRD and XPS techniques. After annealing at 500 degrees C the films' microstructure turns from amorphous to crystalline with the development of highly crystalline cubic In2O3-x (JCPDS card 6-0416). XPS characterisation has revealed the formation of stoichiometric In2O3 (HVTE) and nearly stoichiometric In2O3-x (SG) after annealing. SEM characterisation has highlighted substantial morphological differences between the SG (highly porous microstructure) and HVTE (denser) films. All the films show the highest sensitivity to NO2 gas (0.7-7 ppm concentration range), at 250 degrees C working temperature. At this temperature and 0.7 ppm NO2 the calculated sensitivities (S = R-g/R-a) yield S = 10 and S = 7 for SG and HVTE, respectively. No cross sensitivity have been found by exposing the In2O3 films to CO and CH4. Negligible H2O cross has resulted in the 40-80% relative humidity range, as well as to I ppm Cl-2 and 10 ppm NO. Only 1000 ppm C2H5OH has resulted to have a significant cross to the NO2 response. (C) 1999 Published by Elsevier Science Ltd. All rights reserved
NO2 response of In2O3 thin film gas sensors prepared by sol-gel and vacuum thermal evaporation techniques
No full textIn2O3 thin films have been prepared by high vacuum thermal evaporation (HVTE) and by sol-gel (SG) techniques. The deposited HVTE and SG films have been annealed at 500 degrees C for 24 and 1 h, respectively. After annealing at 500 degrees C, the films are highly crystalline cubic In2O3. XPS characterization has revealed the formation of stoichiometric In2O3 (HVTE) and nearly stoichiometric In2O3-x (SG). SEM characterization has highlighted substantial morphological differences between the SG (highly porous microstructure) and HVTE (denser) films. All the films show the highest sensitivity to NO2 gas (0.7-7 ppm concentration range), at 250 degrees C working temperature. Negligible H2O cross has resulted in the 40-80% relative humidity range. Only 1000 ppm C2H5OH has resulted in a significant cross to the NO2 response. (C) 2000 Elsevier Science S.A. All rights reserved
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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