1,720,959 research outputs found
Behavior of TiO2 nanoparticles during incineration of solid paint waste: a lab-scale test
No full textIn order to assess the potential impacts posed by products containing engineered nanoparticles, it is essential to generate more data about the release of these particles from products' life cycle. Although first studies were performed to investigate the release of nanoparticles from use phase, very few data are available on the potential release from recycling or disposal of nano-enhanced products. In this work, we investigated the behavior of TiO2 nanoparticles from incineration of solid paint waste containing these particles. Solid paint debris with and without TiO2 nanoparticles were treated in a lab scale incineration plant at 950°C (combustion temperature) and in oxidizing atmosphere. The obtained ashes were also vitrified with additives and the release of Ti was finally evaluated by leaching test. From our incineration lab-scale experiment, we did not observe a release of TiO2 nanoparticles into the atmosphere, and Ti was attached to the surface of obtained solid residues (i.e. ashes). The characterization of ashes showed that TiO2 nanoparticles reacted during the incineration to give calcium titanate. Finally, a very low release of Ti was measured, less 1mg/kg, during the leaching test of ashes vitrified with glass cullet and feldspathic inert. Our work suggests that TiO2 nanoparticles added in paints may undergo to physicochemical transformation during the incineration, and that Ti found in ashes may be strongly immobilized in glass matrix. Since this conclusion is based on lab-scale experiment, further research is required to identify which nanoparticles will be emitted to the environment from a real-word-incineration system of household hazardous waste.In order to assess the potential impacts posed by products containing engineered nanoparticles, it is essential to generate more data about the release of these particles from products’ life cycle. Although first studies were performed to investigate the release of nanoparticles from use phase, very few data are available on the potential release from recycling or disposal of nano-enhanced products.
In this work, we investigated the behavior of TiO2 nanoparticles from incineration of solid paint waste containing these particles. Solid paint debris with and without TiO2 nanoparticles were treated in a lab scale incineration plant at 950 °C (combustion temperature) and in oxidizing atmosphere. The obtained ashes were also vitrified with additives and the release of Ti was finally evaluated by leaching test. From our incineration lab-scale experiment, we did not observe a release of TiO2 nanoparticles into the atmosphere, and Ti was attached to the surface of obtained solid residues (i.e. ashes). The characterization of ashes showed that TiO2 nanoparticles reacted during the incineration to give calcium titanate. Finally, a very low release of Ti was measured, less 1 mg/kg, during the leaching test of ashes vitrified with glass cullet and feldspathic inert. Our work suggests that TiO2 nanoparticles added in paints may undergo to physicochemical transformation during the incineration, and that Ti found in ashes may be strongly immobilized in glass matrix. Since this conclusion is based on lab-scale experiment, further research is required to identify which nanoparticles will be emitted to the environment from a real-word-incineration system of household hazardous waste
Indagini sui processi di dissoluzione di infusi alluminosi nel vetro cavo industriale
No full textNel presente lavoro si è cercato di approfondire lo studio degli injùsi alluminosi, un tipo di difetto di produzione di vetro cavo
industriale piuttosto comune e al tempo stesso pericoloso. Gli infusi analizzati sono dovuti principalmente all'utilizzo di
miscele vetrificabili accidentalmente contaminate da granuli di bauxite, a granuli di origine ceramica apportati dall'uso di
rottame da riciclo, a refrattari e a malte impiegate nelle riparazioni. I campioni sono stati analizzati tramite microscopia elettronica a scansione (SEM) per l'individuazione delle caratteristiche microstrutturali e microanalisi ai raggi X a dispersione d'energia EDS, per determinare le composizioni chimiche delle diverse fasi (fasi cristalline primarie e secondarie e zonature vetrose). Particolare attenzione è stata riposta nell'analisi delle reazioni che hanno luogo tra gli infusi alluminosi ed il vetro
fuso ed i meccanismi di diffusione che governano i processi di dissoluzione dell'inclusione. A tal fine, sono stati anche eseguiti dei test di corrosione in laboratorio, per approfondire il meccanismo di dissoluzione di materiale ceramico e refrattario a contatto con un vetro cristallino. Sulla base di dati microtessiturali e microanalitici raccolti, si è potuto correlare le caratteristiche di infusi alluminosi alle diverse tipologie d'inquinanti. L'inquinante bauxitico dà luogo ad infusi con contorni molto lobati, caratterizzati da fasi globulari nefeliniche ed una intensa zonatura composizionale. Gli infusi di origine ceramica si presentano invece molto trasformati e circondati da un'estesa zonatura composizionale. Anche gli infusi da refrattario risultano molto trasformati con residue fasi cristalline secondarie. Infrne, gli infusi da malta si presentano compatti, con un'estesa zonatura composizionale e fasi secondarie nefeliniche in prossimità delle lobature.
Le analisi hanno permesso di ricostruire la possibile evoluzione del difetto da materiale cristallino originario fino alla completa trasformazione in un nodulo vetroso. Parametri come il tempo di permanenza nel forno, la cinetica delle reazioni e la
composizione e natura del materiale alluminoso si sono rivelati critici per tale evoluzione. Le prove di laboratorio hanno per-
messo di ipotizzare che anche piccole percentuali di potassio siano fattori catalitici nei processi di dissoluzione degli infusi.
E' stato inoltre possibile dimostrare come indagini di tipo chimico-mineralogico accuratamente condotte risultino estrema-
mente importanti per una completa caratterizzazione dei difetti.
Aluminous stones are a quite common, dangerous defect in container glass. The stones analysed in the present work are due
to the use ofinvoluntarily contaminated batches containing bauxite grains, ceramic grains introduced by recycled cullet, or grains coming from refractories and mortars used in repairs. The samples were analysed by SEM and EDS-X ray microanalysis to determine microstructural characteristics and the chemical composition of the different phases. In arder to understand the reactions occurring between the aluminous stones and the molten glass, and the diffùsion mechanisms governing the dissolution process, laboratory corrosion tests were carried out on ceramic and refractory materials in contact with a crystal glass. The microtextural and microanalytical data obtained allowed a correlation to be established between the characteristics of the examined stones and the different IJIpes of contaminant. The results showed that the reaction kinetics greatly affect the transformation process of these hetorogenities. The dwelling rime in the furnace, the reaction kinetics, and the composition and nature of the aluminous material, are criticai parameters affecting the transformation of the defect from the originai crystalline material into a completely glassy knot. The laboratory tests also suggested that even small percents of potassium have a catalytic effect on the stone dissolution processo Properly performed chemical-mineralogical investigations were shown to be extremely useful far an exhaustive characterization of these defects
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
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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