1,721,019 research outputs found
Women in Science: Materials
Full text link“Women in Science: Materials” collection aims to highlight the impact of women researchers working in materials science and engineering. It gathers a selection of original articles with the lead author and/or corresponding author being a woma
Environmentally Friendly La0.6Sr0.4Ga0.3Fe0.7O3 (LSGF)-Functionalized Fly-Ash Geopolymers for Pollutants Abatement in Industrial Processes
No full textAbstract: A ready-to use, highly sustainable solution for large scale exhausts catalytic abatement was developed: the active bricks. An environmentally-friendly composite was synthesized by depositing La0.6Sr0.4Ga0.3Fe0.7O3, by combustion synthesis, on a fly ash-based geopolymer improved to bear the high temperatures (> 900 °C) required for synthesis. The geopolymer was obtained using by-products and was synthesized at RT: its production is sustainable and cost efficient. Prepared composites have been tested for methane oxidation and show good, durable activity above 400 °C. Thermal stability was also proved. Composites are a good solution for oxidation of fuel residues in industrial processes. Graphic Abstract: [Figure not available: see fulltext.]
Thermal behavior of Carrara marble after consolidation by ammonium phosphate, ammonium oxalate and ethyl silicate
No full textThe response to thermal variations is the primary cause of marble deterioration in ancient and modern buildings. In this study, the thermal behavior of Carrara marble after consolidation by an innovative hydroxyapatite-based treatment was investigated in comparison with ammonium oxalate and ethyl silicate. Samples were subjected to heating-cooling cycles up to 80 °C. All the consolidating treatments were found to be fairly compatible, as in no case the residual strain after the thermal cycles was found to increase compared to the unweathered untreated marble. Anyway, the hydroxyapatite-treatment has the advantage of causing the highest increase in marble cohesion and the lowest residual strain, besides being more chromatically compatible and durable than the alternative commercial consolidants
Atomistic Simulations of Geopolymer Models: The Impact of Disorder on Structure and Mechanics
No full textGeopolymers are hydrated aluminosilicates with excellent binding properties. Geopolymers appeal to the construction sector as a more sustainable alternative to traditional cements, but their exploitation is limited by a poor understanding of the linkage between chemical composition and macroscopic properties. Molecular simulations can help clarify this linkage, but existing models based on amorphous or crystalline aluminosilicate structures provide only a partial explanation of experimental data on the nanoscale. This paper presents a new model for the molecular structure of geopolymers, in particular for nanoscale interfacial zones between crystalline and amorphous nanodomains, which are crucial for the overall mechanical properties of the material. For a range of Si-Al molar ratios and water contents, the proposed structures are analyzed in terms of skeletal density, ring structure, pore structure, bond-angle distribution, bond length distribution, X-ray diffraction, X-ray pair distribution function, elastic moduli, and large-strain mechanics. Results are compared with experimental data and with other simulation results for amorphous and crystalline molecular models, showing that the newly proposed structures better capture important structural features with an impact on mechanical properties. This offers a new starting point for the multiscale modeling of geopolymers
Permeable and ventilated roofs: an emerging solution for building comfort and climate mitigation in urban centers. The Project LIFE SUPERHERO
No full textDuring the last 15 years, the frequency and intensity of heatwaves have
increased in all the EU. In response to warming cities, the growth in environmental
impacts and global demand for building cooling are two of the most critical energy issues
of our time. Many EU cities are already working on climate mitigation strategies, while
urban adaptation is still a novel challenge and requires the urgent development of
specific measures to change urban design and structures. Indeed, renovation of existing
buildings and design of new ones has a great urban adaptation potential against the
“heat” challenge. An effective sustainable and low-cost answer to cities and building
overheating is using building “passive cooling” technologies, which allow reducing the
temperatures of the building envelope and consequently of the surrounding air, rather
than increasing energy demands from artificial cooling. LIFE SUPERHERO seeks to
exploit a specific building passive cooling solution: the Ventilated and Permeable Roofs
(VPRs) based on roof tile designed during the previous project LIFE HEROTILE.
As the roof is the most exposed element to solar radiation, a “vented roof”,
obtained through an air space between the installed roof covering and the roof
sheathing, could limit the summer heat fluxing into the building, thus reducing roof and
wall temperatures. This space reduces heat transfer and allows the roof to “breathe”
and disperse the accumulated solar heat. If this ventilation is coupled to a “high
permeability” of the roof tiles, it is possible to obtain a considerable increase in the
cooling performance. However, current EU national regulations, standards, green rating
systems and procurements in the building sector do not recognize the cooling potential
of VPRs, mainly focusing on winter heating saving. In particular, there are two main
barriers to overcome: the lack of specific policies/legislative frameworks and the lack of
people's awareness of their potential. The goals of the project will be achieved:
- by implementing a specific EU standard (ETA) and improving building
environmental protocols and national building codes considering HBR (Herotile-
Based Roof) benefits;
- through two building demonstrators where the impact of HBR on occupants’
behavior will be monitored and consequently public and stakeholders’ awareness
promoted;
- by entailing the development of free LCA/LCC software, to facilitate the
implementation of climate change adaptation strategies and action plans at a
local level.
LIFE SUPERHERO thus promotes a synergy between climate adaptation and
mitigation actions. The VPR-HBR allows increasing building and city thermal comfort
(adaptation) due to the limitation of external building roof temperature in hot seasons,
thus reducing the Urban Heat Island phenomenon. The limitation on internal building
roof temperature in hot seasons improves occupants’ comfort, entailing a reduction of
cooling energy demand and GHG (Green House Gases) and accelerating the phasedown
of HFC (Hydro Fluor Carbon) included in refrigerants (mitigation)
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
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