1,721,060 research outputs found
Synthesis of CaTiO3 by Using Eggshell as Source of CaO.
No full textUntil now, eggshells are wasted and pollute the environment without further utilization. The high content of CaCO3 makes eggshell a high potential commodity for precursors in the synthesis of materials, such as calcium titanate (CaTiO3). CaTiO3 is often used as dielectric material for capacitors, as catalyst in photocatalysis and photoluminescence process. CaTiO3 could be synthesized by reacting CaO obtained from eggshell calcination and TiCl4 through hydrothermal method. The synthesis was conducted at three pH conditions, i.e. pH 1, 4, and 14, at temperature of 150 °C for 8 hours. Based on X-ray diffraction analysis result, synthesis at pH 1 and pH 4 only gave TiO2 crystals. CaTiO3 was obtained at pH 14 condition. The result of particle size analyzer test showed that CaTiO3 crystals was not homogeneous with crystal size ranges between 400 and 1400 nm.Selama ini, cangkang telur hanya menjadi limbah yang berpotensi mencemari lingkungan tanpa dimanfaatkan lebih lanjut. Tingginya kandungan CaCO3 menjadikan cangkang telur sebagai komoditas yang berpotensi sebagai prekursor dalam sintesis material, seperti kalsium titanat (CaTiO3). CaTiO3 sering digunakan sebagai bahan dielektrik untuk kapasitor, selain itu juga berfungsi sebagai katalis pada proses fotokatalis dan fotoluminesens. CaTiO3 dapat disintesis dengan mereaksikan CaO dari kalsinasi cangkang telur dan TiCl4 melalui metode hidrotermal. Sintesis dilakukan pada 3 kondisi pH, yaitu pH 1, 4, dan 14, dengan suhu 150 oC selama 8 jam. Berdasarkan hasil analisis difraksi sinar-X, sintesis pada pH 1 dan pH 4 hanya menghasilkan kristal TiO2. Kristal CaTiO3 berhasil disintesis pada kondisi pH 14. Hasil uji penganalisis ukuran partikel menunjukkan bahwa kristal CaTiO3 yang terbentuk masih belum homogen dengan ukuran kristal 400–1400 nm
Sintesis ZnO dengan Tambahan Surfaktan Kationik dan Anionik Menggunakan Metode Hidrotermal
No full textZnO is a semiconductor material that has been widely used in various applications, such as solar cell. This study aimed to synthesis ZnO with ZnSO4 and KOH using hydrothermal method and evaluate the effect of surfactants on the synthesis process. First, ZnO was synthesized with various concentrations of ZnSO4:KOH (1:2, 1:3, 1:4 and 1:5). The best result was chosen by X-ray diffraction analysis. Synthesis of ZnO with the best ratio was carried out again with the addition of cationic surfactant, cetyltrimethylammonium bromide (CTAB), and anionic surfactant, sodium dodecyl sulphate (SDS). Based on the diffractograms, the best ratio was 1:2 with 86.29% crystallinity. This ratio was chosen due to the high crystallinity and the least impurities. Synthesis with the addition of CTAB and SDS gave higher crystallinity, 88.76% and 89.13%, respectively. Based on calculation using Scherrer’s equation, it showed that the addition of CTAB resulted the smallest crystal size. Based on those data, it can be concluded that surfactants have improved the characteristics ZnO by increasing the crystalinity and reducing the crystal size
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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