1,720,963 research outputs found
PELATIHAN PRAKTIKUM KIMIA SEDERHANA MENGGUNAKAN BAHAN-BAHAN DI SEKITAR KITA: “TERMOKIMIA”
No full textPELATIHAN PRAKTIKUM KIMIA SEDERHANA MENGGUNAKAN BAHAN-BAHAN DI SEKITAR KITA: “TERMOKIMIA
PELATIHAN PRAKTIKUM KIMIA SEDERHANA MENGGUNAKAN BAHAN-BAHAN DI SEKITAR KITA: “TERMOKIMIA”
No full textPELATIHAN PRAKTIKUM KIMIA SEDERHANA MENGGUNAKAN BAHAN-BAHAN DI SEKITAR KITA: “TERMOKIMIA
Transpor Fenol dalam Teknik Membran Cair Fasa Ruah Menggunakan Ion Logam Transisi sebagai Fasa Penerima
No full textFenol merupakan salah satu polutan berbahaya yang terakumulasi dalam perairan dan bersifat stabil. Penelitian ini menggunakan teknik membran cair fasa ruah untuk mengurangi kadar fenol pada perairan sehingga konsentrasinya tidak melebihi ambang batas yang diperbolehkan oleh yakni 1 mg/L. FeCl3 dan kloroform berperan sebagai fasa penerima dan membran dalam penelitian ini. Pengaruh berbagai macam variasi seperti jenis fasa penerima, konsentrasi fasa sumber, konsentrasi fasa penerima dan pH fasa penerima serta lama waktu pengadukan telah dipelajari. Kondisi optimum percobaan diperoleh pada konsentrasi fasa sumber 5 x 10-4 M dengan pH 2, konsentrasi fasa penerima 1,2 x 10-4 M dengan pH 6, serta waktu pengadukan selama 90 menit. Efisiensi transpor fenol yang diperoleh pada fasa penerima sebesar 93,28%. Konsentrasi fenol pada fasa sumber dan fasa penerima diukur menggunakan spektrofotometer UV-Vis pada panjang gelombang maksimum 270 nm. Hasil HPLC menunjukkan bahwa fenol yang tertranspor ke fasa penerima lebih banyak dibandingkan yang tinggal di fasa sumber ditandai dengan tinggi puncak pada kromatogram. Hal ini menunjukkan bahwa teknik membran cair fasa ruah efektif menurunkan kadar fenol dengan menggunakan ion logam Fe sebagai fasa penerima
Diazo Red B Dye Removal by Electrocoagulation Method using Aluminum Electrode
Full text linkThe removal of diazo red B dye was studied in water using the electrocoagulation method with an aluminum electrode. The study aimed to reduce the presence of harmful diazo red B dyes in the environment and their impact on living organisms. This study was conducted by testing various parameters with specified values. The initial dye concentrations were set at 10, 20, 30, 40, and 50 mg/L, while the electrocoagulation times were varied at 30, 60, 90, 120, 150, and 180 minutes. The initial pH levels were adjusted to 5, 6, 7, and 8. The applied voltages were 2.5, 5, 7.5, 12.5 V, and the distances between electrodes varied at 1, 1.25, 1.5, 1.75, and 2 cm. The study also examined the effects of initial dye concentration on electrocoagulation time, its interaction with pH, and the influence of pH on electrocoagulation time. These parameters aim to determine the optimum conditions for diazo red B removal, as measured by a UV-Vis spectrophotometer at a wavelength of 420 nm. The optimum removal efficiency of diazo red B was achieved with 94.32% for an initial dye concentration of 30 mg/L, 94.13% for an electrocoagulation time of 180 minutes, 96.00% at a pH of 6, 95.32% for a voltage of 7.5 V, and 95,75% for an electrode distance of 1.5 cm. Additionally, the efficiencies were 99.5% for concentration relative to time was 99.5%, for concentration relative to pH was 97.85%, and for pH relative to time was 96.00%. Additionally, the coagulant analysis of the electrocoagulation results was carried out using FTIR and morphological analysis of the surface of the damaged aluminum anode using an optical microscope
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
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