1,721,166 research outputs found
Karakterisasi Optik Bahan Ba0.5sr0.5tio3 Yang Ditumbuhkan Di Atas Substrat Silikon Tipe-P (111) Yang Didadah Niobium Oksida Dan Klorofil.
No full textBarium Stronsium Titanat (BST) merupakan bahan yang memiliki konstanta dielektrik yang tinggi, serta kapasitas penyimpanan muatan yang tinggi. Penelitian tentang material ferroelektrik BST telah dikembangkan dan dilakukan sejak tahun 1999 oleh Irzaman dan kawan – kawan, pembuatan BST menggunakan peralatan yang cukup sederhana, biaya murah, dan dilakukan dalam waktu yang relatif singkat.
BST dibuat dengan 3 variasi yaitu BST, BST didadah Niobium Oksida dan BST didadah klorofil. Persentase massa pendadah yaitu 5%, 10% dari massa BST. Metode yang digunakan adalah Chemical Solution Deposition (CSD). Proses penumbuhan film tipis dilakukan dengan menggunakan spin Coating, dengan kecepatan 3000 rpm selama 30 detik. Proses penetesan dilakukan sebanyak 3 kali. BST diannealing pada suhu 850oC selama 22 jam waktu penahanan.
Hasil karakterisasi XRD menunjukan tidak terjadi pergeseran struktur dari BST yang dibuat, hal ini dilihat dari nilai parameter kisi yang didapatkan yaitu : 4.07 Ǻ untuk BST, 4.07 Ǻ BST didadah 5% niobium oksida, 4.07 Ǻ BST didadah 10% niobium okdida, 4.06 Ǻ BST didadah 5% klorofil dan 4.08 Ǻ BST didadah 10% klorofil. Karakterisasi sifat optik menunjukan dengan adanya penambahan pendadah niobium oksida dan klorofil menyebabkan sifat absorbansi dari BST menjadi menurun, nilai indeks bias naik, dan nilai energi gap mengalami penurunan. Nilai energi gap adalah 2.23 eV BST didadah 5% niobium oksida, 2.05 eV BST didadah 10% niobium oksida, 2.46 eV BST didadah 5% klorofil dan 2.47 eV BST didadah 10% klorofil, dimana nilai energi gap berdasarkan literatur 3.45 eV
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
Sifat Listrik Arang Aktif Dari Tumbuhan Eceng Gondok (Eichornia Crassipes) Sebagai Bahan Semikonduktor
No full textEceng gondok (Eichornia crassipes) merupakan salah satu jenis tumbuhan
air mengapung. Eceng gondok memiliki kecepatan tumbuh yang tinggi sehingga
tumbuhan ini dianggap sebagai gulma yang merusak lingkungan perairan.
Pertumbuhan eceng gondok yang cepat terutama disebabkan oleh air yang
mengandung nutrien yang tinggi, terutama yang kaya akan nitrogen, fosfat dan
potassium. Batang eceng gondok memiliki kandungan selullosa 50%, lignin 30%
dan sisanya adalah hemiselullosa dan zat- zat yang lainnya. Supaya tidak lagi
menjadin gulma, eceng gondok dapat dimanfaatkan sebagai arang aktif untuk bahan
semikonduktor yang nantinya dapat diaplikasikan sebagai komponen elektronik.
Tahap awal dalam penelitian ini adalah karbonisasi atau pengarangan,
kemudian dilanjutkan aktivasi kimia dengan variasi konsentrasi NaOH 25%, 30%
dan 35% selanjutnya dilakukan aktivasi fisika menggunakan hidrotermal pada suhu
250ᵒ C hingga terbentuknya arang aktif. Hasil aktivasi dilakukan uji serap iodin
untuk mengetahui kerekatifan arang, kemudian dilakukan karakterisasi sifat listrik
menggunakan Inductance, Capacitance and Resistance (LCR meter), Scanning
Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) untuk
mengetahui morfologi pori arang dan untuk mengetahui komposisi unsur yang
terkandung pada arang.
Uji serap iodin menghasilkan nilai tertinggi pada sampel arang aktif dengan
konsenstrasi NaOH 25% yaitu 510.687 mg/g, hal ini berarti bahwa pada konsentrasi
NaOH 25% memiliki kualitas arang terbaik. Pengujian SEM untuk mengetahui
ukuran pori pada arang sebelum dan setelah dilakukan aktivasi, hasil pengujian
menunjukkan bahwa pada arang aktif dengan konsentrasi NaOH 30% tampak
ukuran pori arang paling besar yaitu 118.2 μm, kemudian pada pengujian EDX
terdapat pada arang aktif dengan konsentrasi NaOH 30% memiliki kandungan
unsur karbon tertinggi yaitu 86.57%, hal ini dapat disimpulkan bahwa perlakuan
aktivasi dapat meningkatkan ukuran pori arang serta meningkatkan kandungan
unsur karbon dan menghilangkan pengotor pada arang. Karakterisasi sifat listrik
yang dilakukan menunjukkan hasil bahwa pada konsentrasi NaOH 25% memiliki
nilai konduktivitas tertinggi yaitu 5.70 x 10-8 S/cm , nilai konduktivitas ini terletak
pada daerah nilai konduktivitas listrik yang dimiliki oleh material semikonduktor
(10-8 S/cm sampai 103 S/cm) sesuai dengan penelitiannya sebelumnya yang
dilakukan Irzaman et al. 2014 dan Kwok 1995
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
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
Optimization of Excess Magnesium Addition and Heating Rate on Silicon Dioxide and Silicon Extraction Based Rice Husk
No full textIndonesia is an agricultural country that produces rice sufficiently large. According to Central Agency on Statistics (BPS 2013) data, in 2012 rice production in Indonesia amounted to 69.05 million tonnes of milled rice, an increase of 3.29 million tonnes (5.00%) compared to 2011. Each tonne of rice containing 72% rice, 5% -8% bran and 20% - 22% husk (Muthadhi 2007). Seeing these data would appear a lot of agricultural waste,one of them is rice husk waste . Waste destruction process naturally progresses slowly (Nugraha and Setiawati 2006). Rice husk generated from most of the countries that produce rice just burned and disposed of as waste (Azadi et al. 2010). Rice husk, a waste product of the rice industry is rich in silica. (Kalapathy et al. 2000). Utilization of rice husk stove developed by IPB from 2007, produces another form of waste (Irzaman et al 2007). Rice husk charcoal from rice husk stove IPB, can be used to produce silica. The Silica resulting from the incineration process can be used as a source of silicon (Rohaeti et al.2010). This research is aimed to optimize of the speed of temperature increase (0.5 0C/menit and 1.5 0C/menit) to obtain high-purity silicon dioxide and optimization of addition of excess magnesium by chemical reduction method by comparing the amount of magnesium and silica (49: 60) to obtain high-purity silicon . Silicon dioxide and silicon obtained will be analyzed using Energy Dispersive X-ray (EDX) and FTIR Spectroscopy. Preparation of silicon through three (3) phases, husk charcoal, silica / silicon dioxide and silicon. Making husk charcoal through several stages. At first the rice husk is dried with the aid of sunlight with the aim of accelerating the combustion process. Then the rice husks were weighed at 4000 grams, entered into a husk stove and continued with the combustion process (Ahmad 2012), rice husk and then weighed. In this process produced husk charcoal at 1370 grams (34.25%). Rice husk charcoal as much as 60 grams put in of porcelain bowls and burned in a furnace at a temperature of 400 °C initially for 2 hours, subsequent heating to a temperature of 950 °C for 1 hour with a temperature increase rate setting of 0.5 ° C / min and 1.5 °C / min. After the ash obtained by burning weighed, then washed rice husk ash by using hydrochloric acid (HCl) 3% technical (12 mL 3% HCl technical for 1 gram of rice husk ash), and then heated over a hotplate with a temperature setting of 200 °C and stirred with a magnetic stirrer at a speed of 240 rpm for 2 hours. Subsequently washed with hot distilled water (temperature around 100 °C) repeatedly until the free acid (tested with litmus paper), and then filtered through ash-free paper. Screening results (residues separated from the filter paper) included in the of porcelain bowls and then heated in a furnace at temperatures of 1000 °C for 1 hour with the temperature rise and 5 oC/menit 1 oC/menit remaining until the white silica. The samples were cooled in the furnace and weighed, then the results are tested EDX and FTIR Spectroscopy. The next process to obtain silicon, silica mixed with reducing agents, namely magnesium powder with a ratio 49:60. Once mixed, the sample is heated in a furnace for 1 hour at a temperature of 650 oC. Once heated, the mixture obtained is weighed, then washed with 75 mL of 3% HCl technical. Then heated on a hotplate with a temperature setting of 200 °C and stirred with a magnetic stirrer at a speed of 240 rpm for 2 hours. Then the samples were washed again with 3% HCl technical 300 mL, 1 hour, 240 rpm (Hikmawati 2010). Samples were filtered and washed with hot distilled water (temperature around 100 °C) repeatedly so that the free acid, and then dried in a furnace at 110 °C for 12 hours (Hikmawati 2010, Ahmad 2012 and Otto 2013). The results of EDX analysis, produces silicon dioxide with a purity of 99.15% (for a heating rate of 0.5 ° C / min) and 78.96% (for a heating rate of 1.5 ° C / min). Chemical reduction of silica with magnesium excess magnesium and silica in the ratio 49: 60 has resulted in silicon with a purity of 44.03%. Characterization of silicon dioxide using FTIR spectroscopy showed siloxane functional groups. Peaks of FTIR spectra showed specific peaks associated with silicon dioxide at wave number 1110 cm-1 to 467 cm-1
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