1,721,004 research outputs found
Chemical recycling of waste pet into polyester polyol for the production of semi-rigid pu foams / Asmalina Mohd Darus
Full text linkOne of the biggest problems caused by soft drink poly(ethylene terephthalate)
PET bottles is the waste problem resulting in environmental pollution. To economically
reduce this waste, this study presents a method to recycle the PET bottle by glycolysis
and convert it into a polyester polyol that can be used to make polyurethane foam.
Common soft-drink PET bottles were glycolysed by glycerol in the presence of zinc
acetate as a catalyst. Dependence on glycolysis conversion on reaction temperature and
the Arrhenius plot, activation energy obtained of 36.5 kJ/mol. The new polyester
polyols namely glycolysed PET have hydroxyl value of 500-800 mg KOH/g.
Miscibility of the glycolysed PET with a commercial polyol designated for
flexible polyurethane foam synthesis was investigated. The result helps in estimating
the appropriate amount of glycolysed PET in the polyol mixture. Certain amount of
surfactant, catalyst and blowing agent were then added in the preparation of polyol
component before reacting with MDI in the formation of polyurethane (PU) foam.
Results showed that the semi-rigid polyurethane foams obtained have density of 50-90
kg m-3, with open cell content and good compression strength in the range of 90-120
kPa and comparable with other studies. The polyurethane foams synthesized could be
used in automotive applications such as insulation materials
Synthesis and characterization of partially phosphorylated poly (Vinyl Alcohol) – aluminum phosphate (PPVA – AlPO4) nanocomposite / Asmalina Mohamed Saat
Full text linkPartially phosphorylated polyvinyl alcohol - aluminum phosphate (PPVA-AlPO4) composite were synthesized through continuous stirring and condensation at 80 °C. Interaction of pure polyvinyl alcohol (PVA) with phosphoric acid (PA) produced partially phosphorylated poly vinyl alcohol (PPVA) and the addition of aluminum (Al) source produces a PPVA-AlPO4 composite. Fourier Transform Infrared (FTIR) and Raman spectra of PPVA confirmed the phosphate group in PPVA-AlPO4 composite. The phosphate group had bonded with aluminum at C-O-P- AlPO4, O-P-O- AlPO4 and also OH-Al. The optical properties of these PPVA and PPVA-AlPO4 nanocomposite samples were examined by UV-visible and photoluminescence (PL) spectroscopy. UV analysis of PPVA shows single peak at 274 nm while in PPVA-AlPO4, the peak was shifted to lower wavenumber of 208 nm. PL spectra of PPVA-AlPO4 shows broad peak at range of 304-371, 450-550 and 560-700 nm. This confirmed that the phosphate group in PPVA created bonding with aluminum. Transgravimetric (TGA) analysis shows that the weight residue of PPVA-AlPO4 composite was higher than PPVA and PVA. X-ray diffraction (XRD) pattern of PVA shows a single peak at angle of 20°. However, the peak become broadened as PA added. Meanwhile, the addition of aluminum source produced multiple peaks referring to the multiple phases of AlPO4 in the nanocomposite. Field Emission Scanning Electron Microscopy (FESEM) confirmed the existence of multiple geometrical phases and nanosize of spherical particles. The influence of important synthesis parameters such as, effect of PPVA, effect of aluminum sources, pH and crystallization time are also studied
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
Keberkesanan poster iklan dalam mempengaruhi masyarakat: kajian kes pusat membeli-belah (sekitar Kuala Lumpur) / Asmalina Abd. Malik
Full text linkTesis ini merupakan satu penyelidikan serta kajian tentang poster iklan keberkesanannya terhadap masyarakat. Kajian kes: pusat membeli-belah di sekitar Kuala Lumpur. Dari apa yang diketahui, poster adalah suatu media yang memaparkan berita-berita dan maklumat-maklumat serta memberitahu perkara-perkara baru. Misalnya dalam memperkenalkan produk dan perkhidmatan kepada khalayak ramai
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
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
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