1,720,965 research outputs found
Determination of Zirconium(IV) Based on Flow Injection Analysis with The Xylenol Orange As A Complexing
Full text linkThe development of spectrophotometry method based on Flow Injection Analysis (FIA) to determine Zr(IV) in tin ore accompanying mineral has been done using xylenol orange as complexing agent. The complex between Zr(IV) and xylenol orange 0,05% was formed at pH 2 (1:1). The complex formed having maximum absorbance at wavelength 554 nm. The mineral decomposition has been done by fusion method using Na2CO3 and Na2O2 as fluxs for open system and the close system decomposition using HNO3, HClO4 and HF as solvents. FIA-spectrophotometry that has been developed was able to show good analytical performance, with precision of %KV not more than 5% at concentration level mg/L, was 3,98%, with sensitivity was 2,79 ppm and the detection limits of calculated (S/N = 3) was 0,21 ppm. This method has been aplicated for analyzing Zr(IV) in zircon mineral sample with analysis result 20,26% of ZrO2 and recovery percentage was 100,7%.
 
Lead (Pb) Reduction Efficiency in Used Lubricating Oil in Ship Using The Acid Clay Treatment Method: Perspective of Environmental Pollution Control at Paotere Port, South Sulawesi, Indonesia
Full text linkThe number of watercrafts in the sea will have an impact on the amount of waste lubricant oil that is discharged into the sea, which ultimately results in pollution. The increasing level of hazardous and toxic materials (B3 waste) is concerned to have a wider impact on public health and environment quality. One of the B3 wastes that requires special handling due to its high quantities is used lubricating oil. Utilization and processing of waste lubricant oil discharged from the ship is an alternative that can be applied to reach efficient consumption of petroleum which is shrinking from year to year. Therefore, we need a processing method that can reduce the pollutants generated from the waste, one of which is the Acid Clay Treatment method. This treatment aims to determine the best conditions for reducing heave metal lead (Pb) through Acid Clay Treatment method and to assess the decrease in Pb concentration contained in used lubricating oil from ship. The adsorbent used was clay that has been activated with sulphuric acid. The processing of used lubricating oil was carried out using three variations, including adsorbent concentration, contact time, and acidity (pH). The test results of used oil lubricating oil processing were 15 gram of adsorbent concentration, 90 minutes of contact time, and pH 4. The Pb reduction efficiency obtained from Acid Clay Treatment method in the best conditions was 53.72%
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
Penentuan Nilai Kalor Briket Dengan Memvariasikan Berbagai Bahan Baku
Full text linkLimitations of the availability of non-renewable energy sources. Cocoa shell waste and sawdust widespread everywhere and can be used as an alternative energy source that is to cultivate and make fuel, one of which briquetting. The composition of the material that is (90: 10 75: 25 and 50: 50). After mixing the briquettes are printed using a printer briquettes. From this study, the best calorific value contained in the ratio of sawdust 90: Water Hyacinth 10 is 6223.20 cal/g, the ratio of sawdust 90: 10 cocoa skin is 5953.72 cal / g and Leather Cocoa 90 : Water Hyacinth 10 ie 6066, 09 cal/g. The best density value in comparison sawdust: cocoa skin (75:25) ie 1.05 kg/cm3. Best values compressive strength in comparison cocoa skin: water hyacinth (50:50) ie 2.32 kg/cm3. Best water content ratio of sawdust : water hyacinth (90 : 10) ie 3. 89% ash content. Value best comparison Leather cocoa : water hyacinth (90 : 10) is 0.66%. Volatile matter best value comparison cocoa skin: water hyacinth (90:10) ie 13.1%. The best comparison value of fixed carbon sawdust: cocoa skin (90 :10) is 62,34 %
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
Analisis Antioksidan Ekstrak Etil Asetat Dari Kulit Buah Rambutan (Nephelium Lappaceum) dengan Menggunakan Metode dpph (1,1 difenil-2-pikrilhidrakzil)
Full text link Rapiah rambutan fruit leather (Nephelium lappaceum) is one of the traditional medicine to cure various diseases such as fever and dysentery. Scientific research previously stated rambutan fruit peel skin Rapiah rambutan (Nephelium lappaceum) potentially have antioxidant content. Through this research can know the effect of solvent ethyl acetate to extract optimal rambutan fruit skin in antioxidants withdrawal. The method used for extraction is macerated using methanol and partitioned with liquid-liquid extraction using ethyl acetate solvent with a ratio (1:3), (1:4) and (1:5) which produces a thick rind extract rambutan. The extract was tested color and separated by thin layer chromatography (TLC) using the eluent butanol: glacial acetic acid: water (BAA) (4: 1: 5). Antioxidants are determined by testing against DPPH free radicals by measuring the absorbance of DPPH (1,1-diphenyl-2-pikrilhidraksil) at a wavelength of 517 nm. So that the results of this study showed the highest % reduction obtained at a ratio (1:3)
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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