1,720,967 research outputs found
Novel products for multilayer coating cycles used as smart strategy to increase energy efficiency and environmental sustainability of buildings: formulation, development and simulation models
No full textToday, crude oil derivatives are worldwide used as raw materials for the synthesis of carbon-based chemicals. However, the environmental sustainability of their entire life cycles, from the extraction to the application, has been recognized as poor. For what concerns the building sector, synthetic polymers obtained from crude oil are traditionally used inside the coatings formulations. Considering the concern about their environmental impact, it is mandatory and urgent to find more environmentally friendly alternatives. Without any doubt, the most promising alternative to carbon source is biomass, either in its natural state, i.e., biopolymers, or as waste material from agriculture and the food industry. Despite the wide availability of biomass, and the large research on its extraction and modification, the production of bio-based chemicals and the related substitution of the traditional ones is still far to be obtained. Along with the impact of single compounds, another concern about building sustainability lies on the construction processes and the impact of their life cycle. For example, household heating systems mainly depend on fossil fuels and for low thermal insulation building envelopes, the energy consumption in the EU accounts for around 36 % of greenhouse gas emissions.
With these premises, the present PhD Thesis foresees two different goals, namely the development of construction materials for the building sector by using biomass derivatives and recycled components to increase sustainability, and the improvement of energy efficiency for existing and new buildings by enhancing the thermal insulation properties of the building envelopes. The raw materials chosen in this project to replace some of the traditional components are alginate, a biopolymer extracted from seaweed, natural zeolite, naturally occurring porous volcanic rocks, and organic based aerogels from food waste.
For what concerns alginate, the key idea is that its well-known gelling ability, so far mainly used in biomedical and food industries, can be exploited inside coatings formulations as well to improve flow properties during the storage and application phase. The role of its molecular weight, concentration and counterion type has been deeply evaluated through rheological, spectroscopic and tensile tests. According to the obtained results, it can be concluded that such a biopolymer represents a suitable bio-based thickener with an associative like character.
Regarding natural zeolites and organic-based aerogels, they were investigated as a sustainable approach to achieve coating formulations with a low thermal conductivity taking inspiration from highly porous synthetic materials (e.g, synthetic zeolite and silica aerogels). In this context, natural zeolites purchased from national mines and aerogels obtained by recycling food wastes, specifically spent ground coffee and apple pomace, perfectly fit in this research. Considering their natural origin and the lack of literature, the use of these materials as thermal filler inside a coating formulation is ambitious. Moreover, their hydrophilic character does not harmonize with common water based coatings. To overcome this problem, a surface modification of both zeolites and aerogels was carried out to enhance their hydrophobic character. Thermal properties of both zeolite and aerogel-based plaster were enhanced, with resulting thermal conductivity being lower than that of a standard mineral plaster.
Due to its high novelty, despite the research is still at a preliminary phase, this project can be considered an important step towards the development of coating formulations with a higher amount of bio-based or recycled components and promising thermal insulating properties
Interaction of sodium alginate thickener with components of architectural water-based coatings
No full textNon-ionic polysaccharides, mainly cellulose ethers, have been extensively studied as thickeners in paint formulation. Their mechanism of interaction with the surrounding system is well known and, due to their easy dissolution properties and availability on the market, they are the most used thickening agents. On the other hand, ionic polysaccharides, having possible interaction with the components of the formulation, are less used. In this work, the role of an anionic polysaccharide, sodium alginate (SA), as a thickener, was investigated in a typical wall paint formulation by evaluating its interaction with the principal components of the formulation: water, binder, pigment and extender. Rheology and FTIR spectroscopy were used to evaluate the occurrence of chemical bonds between the polysaccharide chains and the surrounding system. Contemplating the results, so- dium alginate, depending on its molecular weight, Mw, and concentration, turns out to be a suitable thickener for wall paint formulations. In particular, the possibility of building-up a network due to the presence of entan- glements, and the interaction with water molecules and extender, demonstrated that the formulation prepared with 0.2 wt. % of a medium Mw alginate was the most promising one. On the other hand, low Mw alginate exhibited a weaker gel structure and only if present at 0.4 wt. % was appropriate concentration for a ready-to-use product
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
