1,720,970 research outputs found
Separation of Mn and Fe From a Manganiferous Iron Ore Using Horse Dung as Reductant: A Zero Waste Approach
No full textTop, Soner/0000-0003-3486-4184; Kursunoglu, Sait/0000-0002-1680-5482; Altiner, Mahmut/0000-0002-7428-5999The separation of manganese and iron from a manganiferous iron ore using horse dung (biomass) as reductant was investigated in a sulfuric acid solution, and 99.80% Mn and 17.76% Fe were extracted into the solution under these leaching conditions: 1 M sulphuric acid concentration, 120 g/L biomass, 1/10 solid to liquid ratio, 300 rev/min stirring speed, 90 degrees C leaching temperature, and 3 h leaching time. In the first precipitation step, the iron and aluminum were first rejected from the solution at pH 5.04. Thereafter, 98.58% Mn was precipitated at pH 10 in the second step. The precipitate was identified as a pyrochroite mineral. After the leaching, the residue was subjected to a carbothermal reduction process conducted at 700 degrees C for 10 min in the presence of no extra reductant. The residue was converted to magnetite mineral, which can be easily recovered by magnetic separation. Based on the experimental results, a flowsheet has been proposed.Turkiye Bilimsel ve Teknolojik Arastirma Kurumu [119M690]; Cukurova Universitesi [FBA-2020-13057]Turkiye Bilimsel ve Teknolojik Arastirma Kurumu, 119M690 and Cukurova Universitesi, FBA-2020-13057
A Distinctive Determination of Circular Nozzles in Downcomer for Column Flotation
No full textAltiner, Mahmut/0000-0002-7428-5999; Top, Soner/0000-0003-3486-4184;This study aims to recover clean coal from valuable hard coal tailings (HCT), which have been used as solid fuels in a thermal power plant, through convenient conditions. The effective diameters of circular nozzles on the recovery of HCT were investigated by using the Jameson cell (JC) as the main purpose. Preliminary tests were conducted to determine the type and dosages of the collector and frother. The JC test results were evaluated by Yates and Box Behnken based on ANOVA analysis, statistically. It was observed that 3,000 g/ton of diesel oil, 300 g/ton of MIBC, 100 g/ton of Na2SiO3, and 60 cm of downcomer depth were found applicable levels of parameters. The decrease of the diameter increased the venturi effect of downcomer which provided the best recovery ratio of 97.79%. Besides, the results of kinetic models were obtained with desired efficiencies (CR infinity = 94.77%, k(coal) = 1.20, R-2 = 0.98 and SI = 2.40). The best diameter was 5 cm supplied a short time and high carrying capacity (CC) for concentrate.Cukurova University; [MMF2009YL47]This research was supported by Cukurova University [Project Code: MMF2009YL47]
Properties of Fly Ash-Based Lightweight Geopolymer Concrete Prepared Using Pumice and Expanded Perlite as Aggregates
No full textTop, Soner/0000-0003-3486-4184; Ekicibil, Ahmet/0000-0003-3071-0444; Kaya, Dogan/0000-0002-6313-7501; Vapur, Huseyin/0000-0003-4438-3982; Altiner, Mahmut/0000-0002-7428-5999The present paper aims to utilize the fly ash wastes with lightweight aggregates for geopolymer concrete production process in which sodium hydroxide (NaOH) and sodium metasilicate (Na2SiO3) were used as alkali activators, respectively. The designed experiments were examined by the Yates Analyses and so the productions of geopolymer concrete were investigated depending on curing temperature, solid/liquid rate and concentration of alkali activators. The curing temperature and alkali activator concentration were revealed as effective parameters in geopolymerization. The effects of expanded perlite (EP) and acidic pumice (AP) aggregates were discovered for the production of lightweight geopolymer concretes. The microstructural properties of each produced geopolymer concrete were characterized using SEM, EDS and laser particle size analyses. The specifications of the concrete were evaluated based on their uniaxial compressive strength (UCS), point load strength (PLS), sonic speed (SS), Mohs hardness (MH), and water absorption (WAR) ratio results. In addition, the effects of pre-wetting of EP aggregates, which have hydrophilic nature, were examined. To the best of our knowledge, this is the first time that pre-wetted lightweight EP aggregates were used to produce lightweight GP concretes. As a result of pre-wetting, chemical usage decreased by 32.5%. The UCSs of the lightweight geopolymer concretes were in a range of 10-50MPa and their unit weights changed between 1250 and 1700 kg/m(3). Lighter concretes were obtained by the addition of EP aggregates rather than AP ones. (C) 2019 Elsevier B.V. All rights reserved.Scientific Research Project Unit of Cukurova University [FBA-2017-8313]Scientific Research Project Unit of Cukurova University supported this study (Grand number: FBA-2017-8313)
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
Recovery of Vanadium and Nickel From a High Caco3 Containing Petroleum Coke Ash by Roasting and Acidic Leaching
No full textAltiner, Mahmut/0000-0002-7428-5999; Kursunoglu, Sait/0000-0002-1680-5482In this study, it was aimed to extract vanadium (V) and nickel (Ni) from a petroleum coke ash (PCA) using a roasting process without additives, followed by leaching with sulfuric acid (H2SO4). The experiments were designed based on the Taguchi approach, taking into account the parameters of temperature, acid concentration, time, and solid ratio. Additional leaching tests were conducted on the non-roasted PCA for comparison, to assess the effect of roasting on the extractions of V and Ni. The results showed that no extra reducing agent was needed as the PCA contained high levels of CaCO3, which could be used as a reducing agent during roasting. It was found that roasting was essential for high Ni extractions, but had no strong effects on V extractions. The Ni extraction was found to be between 13.3 and 80.8% for the non-roasted PCA and between 43.6 and 99.3% for the roasted PCA. The V extraction was between 36 and 97.9% for the non-roasted PCA and between 45.4 and 99.9% for the roasted PCA. The optimal leaching conditions were determined to be a sulfuric acid of 4.5 M, a solid ratio of 10%, a temperature of 75 degrees C, and a time of 75 min. In addition, it was determined that the leaching conditions had a great effect on the oxidation state of vanadium ions, and an increase in the acid concentration led to the formation of V3+ ions (green color) instead of VO2+ ions (blue color) in the pregnant leach solution. The final pregnant leach solution containing 1056.50 mg/L V, and 251.85 mg/L Ni was achieved with an extraction yields of > 98%. The experimental results were greatly fitted by the shrinking core model and the activation energy (E-a) for V and Ni was calculated as 3.60 and 4.01 kJ/mol, indicating that the leaching mechanism can be explained by the diffusion control model.The study was the part of the first author's master thesis and financially supported by Cukurova University [Project ID: FYL-2022-14905]. [FYL-2022-14905]; Cukurova UniversityThe study was the part of the first author's master thesis and financially supported by Cukurova University [Project ID: FYL-2022-14905]
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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