1,720,956 research outputs found
Flammability Studies on Biopolymer Blends Containing Phosphate Based Flame Retardants
No full textThe aim of this study was to evaluate the efficiency of diammonium phosphate (DAP) and silicate dispersion (SILIC) as a flame retardant system in polylactic acid (PLA)-polycaprolactone (PCL) blends. First polylactic acid and polycaprolactone respectively were mixed in different ratios in order to create the matrix of our polymer. PCL was used to enhance the processability and biodegradability of PLA. Diammonium phosphate was used as a flame retardant additive to create a char protective layer on the polymer’s surface, as it is safe, inexpensive, and more efficient than other phosphorus compounds. Finally silicate dispersion was used as a coating to inhibit pyrolysis gases and to retard thermal degradation and oxidation. The thermal stability and the flame retardant properties were evaluated by thermogravimetric analysis (TGA) and cone calorimeter, respectively. Differential scanning calorimetry was used to study the thermal transition of the samples. Finally, optical microscope (OM) was used to analyse the external char structure, and scanning electron microscopy (SEM) for morphological study of the char. The samples containing DAP and SILIC showed a compact structure and the results from TGA and cone calorimeter suggested that there was a synergistic effect with the addition of the DAP and the coating. The morphological study showed that the addition of DAP along with the coating created a char residue more homogenous and dense than the other composites The cone calorimeter analysis confirms the formation of an intumescent structure for the blends containing DAP and SILIC. The best results were obtained for (PLA-PCL)-30DAP coated, with a final residue corresponding to 64% of the initial sample mass and also a decrease in the peak of heat release (PHRR) rate and total heat release (THR) of 91% and 85% respectively.Validerat; 20141021 (global_studentproject_submitter
Use of nanoscaled cellulose for water purification
No full textThe study explores the potential of cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) to remove positive metal ions from contaminated water. Several methods are available in the market for the removal of heavy metal pollutants from aqueous solutions or industrial effluents, such as chemical precipitation, electroplating, ion exchange, and membrane processes (1). However, these methods are inefficient or expensive when heavy metals are present in the water at low concentrations, therefore new environmentally friendly technologies are still in demand. The aim of this project is to study the adsorption and desorption of heavy metal ions by nanocellulose. We carried out different experiments in order to analyse the adsorption capacity of different metal ions such Ag+, Cu2+, Fe(III) and As (V). Arsenic was studied with Chitin CNC. Experiments showed that all nanopolysaccharides had adsorption capacity for metal ions, however phosphorylated CNC had the most outstanding capacity (144.5 mg Fe/g, 119.4 mg Ag/g and 114 mg Cu/g), which means almost 100 % of the metal ions were removed. The machineries used in the experiments were ICP-‐OES and EDS. ICP-‐OES was used to verify de adsorption of the heavy metal ions and EDS to study the possibility of desorption in order to recover the metals.Outgoin
Use of nanoscaled cellulose for water purification
No full textThe study explores the potential of cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) to remove positive metal ions from contaminated water. Several methods are available in the market for the removal of heavy metal pollutants from aqueous solutions or industrial effluents, such as chemical precipitation, electroplating, ion exchange, and membrane processes (1). However, these methods are inefficient or expensive when heavy metals are present in the water at low concentrations, therefore new environmentally friendly technologies are still in demand. The aim of this project is to study the adsorption and desorption of heavy metal ions by nanocellulose. We carried out different experiments in order to analyse the adsorption capacity of different metal ions such Ag+, Cu2+, Fe(III) and As (V). Arsenic was studied with Chitin CNC. Experiments showed that all nanopolysaccharides had adsorption capacity for metal ions, however phosphorylated CNC had the most outstanding capacity (144.5 mg Fe/g, 119.4 mg Ag/g and 114 mg Cu/g), which means almost 100 % of the metal ions were removed. The machineries used in the experiments were ICP-‐OES and EDS. ICP-‐OES was used to verify de adsorption of the heavy metal ions and EDS to study the possibility of desorption in order to recover the metals.Outgoin
Use of nanoscaled cellulose for water purification
No full textThe study explores the potential of cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) to remove positive metal ions from contaminated water. Several methods are available in the market for the removal of heavy metal pollutants from aqueous solutions or industrial effluents, such as chemical precipitation, electroplating, ion exchange, and membrane processes (1). However, these methods are inefficient or expensive when heavy metals are present in the water at low concentrations, therefore new environmentally friendly technologies are still in demand. The aim of this project is to study the adsorption and desorption of heavy metal ions by nanocellulose. We carried out different experiments in order to analyse the adsorption capacity of different metal ions such Ag+, Cu2+, Fe(III) and As (V). Arsenic was studied with Chitin CNC. Experiments showed that all nanopolysaccharides had adsorption capacity for metal ions, however phosphorylated CNC had the most outstanding capacity (144.5 mg Fe/g, 119.4 mg Ag/g and 114 mg Cu/g), which means almost 100 % of the metal ions were removed. The machineries used in the experiments were ICP-‐OES and EDS. ICP-‐OES was used to verify de adsorption of the heavy metal ions and EDS to study the possibility of desorption in order to recover the metals.Outgoin
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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