1,720,972 research outputs found
SYNTHESIS OF MAGNESIUM SILICATE FROM WHEAT HUSK ASH: EFFECTS OF PARAMETERS ON STRUCTURAL AND SURFACE PROPERTIES
No full textTERZIOGLU, Pinar/0000-0003-4114-7044WOS: 000311336800077In the present study, magnesium silicate was produced by using wheat husk ash. Wheat husk was burned at 600 degrees C to obtain an amorphous ash structure, and the ash was processed with sodium hydroxide solution with heat to extract silica. Sodium silicate solution and magnesium salts were used to synthesize magnesium silicate. The present study investigates effects of the feeding rate on magnesium silicate production (0.6 mL/min, 35 mL/min, 70 mL/min), the type of magnesium salt (MgSO4 center dot 7H(2)O or MgCl2 center dot 6H(2)O), temperature (25 degrees C or 50 degrees C), and the washing agent ( water and acetone) on the chemical composition and surface characteristics of magnesium silicate. The results demonstrated that all of the variables affected the surface characteristics of magnesium silicate, such as surface area, particle size, and pore volume. However, it was also observed that the studied parameters did not affect the chemical composition of magnesium silicate. The wheat husk ash-based magnesium silicates obtained in the experimental study had a BET surface area ranging from 79 to 91 m(2)/g and a particle size varying from 42 to 63 mu m.Yildiz Technical University, Coordination of Scientific Research Projects (BAP)Yildiz Technical University [29-07-04-YL05]This study was funded by Yildiz Technical University, Coordination of Scientific Research Projects (BAP) with project number 29-07-04-YL05
EFFECT OF ACID TYPE AND GELATION pH ON THE STRUCTURAL PROPERTIES OF SILICA AEROGELS PREPARED BY USE OF RICE HULL BIOSILICA
No full textTERZIOGLU, Pinar/0000-0003-4114-7044; Ikizler, Burcu Karakuzu/0000-0002-8786-579X;WOS: 000379848700004In this study, the experimental results of the surface area, morphology, and density of silica aerogels obtained at different preparation conditions are reported. The aerogels have been produced by sol-gel process followed by ambient pressure drying. Rice hull ash silicate solution was used as an inexpensive precursor. The type of acids and gelation pH has strongly affected the structural properties of the final products. The silica aerogels have a well-developed nanoporous structure and a high specific surface area. The densities, pore sizes and specific surface areas of the silica aerogels were in the range of 0.273-0.849 g cm(-3), 3.24-10.22 nm, and 238-726 m(2)g(-1), respectively.Yildiz Technical University Projects Office [2015-07-04-KAP-05]The authors are grateful to the Yildiz Technical University Projects Office for the financial support through an extensive research project (Project No: 2015-07-04-KAP-05)
Characterization of Wheat Hull and Wheat Hull Ash as a Potential Source of SiO2
No full textTERZIOGLU, Pinar/0000-0003-4114-7044;WOS: 000323370400097Wheat is a very important agricultural product, and is among the grains that has the highest sustenance value in the world. Every year large amounts of wheat hull is produced which has a low economic value. The present study aimed to characterize the structure of wheat hull and wheat hull ash obtained after burning wheat hull at 400 to 1000 degrees C for 5 h. This study also investigated the potential of wheat hull as a source for the production of silica xerogel. X-ray diffraction patterns, scanning electron microscope micrographs, the chemical properties, the particle morphology, particle size, surface chemistry of wheat hull, wheat hull ash, and its silica xerogels were determined by the use of various instruments and analysis techniques. A temperature of 700 degrees C was found to be the optimum ashing temperature with maximum amorphous silica content. The BET surface area of ashes ranged from 7.21 to 0.11 m(2)/g. The study demonstrated that silica xerogel powder with 93.9% silica content was obtained by the use of wheat hull after heat treating at 700 degrees C for 5 h.Yildiz Technical University, Coordination of Scientific Research Projects (BAP)Yildiz Technical University [29-07-04-YL05]This study was funded by Yildiz Technical University, Coordination of Scientific Research Projects (BAP) with the project number 29-07-04-YL05
CHANGES IN THE CELL GROWTH, LIPID CONTENT AND LIPID PROFILE OF CHLORELLA PROTOTHECOIDES UNDER DIFFERENT MEDIUMS
No full textTERZIOGLU, Pinar/0000-0003-4114-7044;WOS: 000379848700005Chlorella protothecoides is a precious lipid source that can be used as a biodiesel feedstock. Calcium, carbon, iron, hydrogen, magnesium, nitrogen, oxygen, phosphorus, potassium and sulfur are among the various elements have to be supplied for the growth of microalgae. Especially, nitrogen and phosphorus have significance in handling the growth ratio and lipid production of microalgae. In this study, the effect of different mediums (with/without nitrogen) on cell growth and lipid content of Chlorella protothecoides was investigated. Highest lipid extraction efficiency was obtained by using hexane at ambient temperature. The maximum lipid content of Chlorella protothecoides fed with the nitrogen free Bold Basal medium was 48% (dry weight percent). The composition of fatty acid methyl esters was influenced by alteration of medium.Yildiz Technical University Projects Office [2015-07-04-KAP-03]The authors are grateful to the Yildiz Technical University Projects Office for the financial support through an extensive research project (Project No: 2015-07-04-KAP-03)
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
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
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