1,720,956 research outputs found
Physical, structural and mechanical properties of wollastonite-based foam glass ceramics using eggshell and soda-lime-silica glass waste
Get PDFFoam glass-ceramics represents a highly valuable solution for lightweight fill
material, which has a low density, incombustible, and good in mechanical strength.
In this work, foam glass-ceramics were prepared by the solid-state conventional
method, using soda-lime-silica (SLS) glass waste as a matrix glass and eggshell (ES)
as a foaming agent. The purpose of this study is to synthesize and study the changes
that occur in physical, structural, and mechanical properties of foam glass-ceramic
derived from waste materials by varying the ES content, sintering temperature, and
sintering duration. Both of the raw materials were milled and sieved to the particle
size of 45 μm. The powders then were homogenized with the empirical formula,
[ES]x[SLS]100-x where x = 1, 3, 6, and 9 wt.%. and uniaxially pressed with 5 MPa.
The obtained compact powders were heat-treated at 700, 800, and 900 °C for 30, 60,
and 120 min with the constant heating rate at 10 °C/min. The foam-glass ceramic
samples were then analyzed based on physical properties; measured by density,
linear expansion, and porosity. The structural properties of the foam glass-ceramic
samples were determined by X-Ray Diffraction (XRD), Field Emission Scanning
Electron Microscopy (FESEM), and Fourier Transform Infrared Spectroscopy
(FTIR). Then, the mechanical properties of the sample were measured using
Universal Testing Machine (UTM). The optimum parameter of the foam glassceramics
was obtained at 800 °C for 60 min with the substitution of 3 to 6 wt.% ES
content. In fact, the optimum temperature was supported by the thermogravimetric
analyzer (TGA) which indicates that the mass loss of CaCO3 in ES occurs at the
temperature of 800 °C. The samples prepared this way to provide a minimum bulk
density of 0.326 – 0.421 g/cm3 with the maximum porosity of 87.2 – 83.16 %.
Furthermore, XRD analysis revealed that the formation and growth of cristobalite
(SiO2) and wollastonite (CaSiO3) crystal phases after the heat-treatment process at
800 °C. Meanwhile, the FTIR analysis indicates the strong intensity of Ca‒O bond
at 620 to 650 cm‒1 of wavenumber associate with decreasing the intensity peak of C‒O after the heat-treatment process at 800 °C. FESEM analysis showed that the
pores are larger and abundant distributed with the size of the diameter’s pore is 861
– 1200 μm in the samples with 3 to 6 wt.% of ES content. The results of compressive
strength for the sample with 3 and 6 wt.% ES content increases from 0.04 and 0.42
MPa, respectively, depending on the crystalline phase content. Therefore, 6 wt.% ES
is an appropriate ratio for fabricating foam glass-ceramics with a low density and
high compressive strength. The preparation of foam glass-ceramics using solid
wastes provide a promising way to prepare ceramic aggregate for the construction
application as well as giving benefit to the economy and environment issue
Determination the concentrations of heavy metals in silver catfish (pangasiussp.) from Sungai Semantan and Sungai Tembeling / Dur Iffa Saparuddin
Get PDFThis study conducted to determine the concentration of heavy metal such as Cu,
Zn, Ni and Cd in the muscle of silver catfish (Pangasius sp.) collected from Sungai
Semantan and Sungai Tembeling. The fish feed and water samples were taken
from both sites that act as additional sources of metal accumulation in fish and to
assess the transfer factor.. The heavy metals in silver catfish and fish feed were
analysed by Energy Dispersive X-Ray Fluorescence (EDXRF) while the level of
heavy metals in water was analysed by Inductively Coupled Plasma-Mass
Spectrometry (lCP-MS). The highest and lowest concentrations of heavy metal
from both sites were zinc and nickel respectively. The concentration of heavy
metal in the fish from both site were in the increasing order for nickel, cadmium,
copper and zinc. Estimated daily intake (EDI) for selected heavy metal was below
the reference dose (RfD) for fish and the level for each heavy metal was below the
permissible limit set by FAO/WHO except cadmium. The values of transfer factor
indicate that the accumulated metal in fish is from water
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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