1,720,957 research outputs found
Thermogravimetric Analysis of Moisture in Natural and Thermally Treated Clay Materials
Full text linkClays are a class of porous materials; their surfaces are naturally covered by moisture. Weak thermal treatment may be considered practical to remove the water molecules, changing the surface properties and making the micro- and/or mesoporosities accessible to interact with other molecules. Herein, a modulated thermogravimetric analysis (MTGA) study of the moisture behavior on the structures of five, both fibrous and laminar, clay minerals is reported. The effect of the thermal treatment at 150 °C, which provokes the release of weakly adsorbed water molecules, was also investigated. The activation energies for the removal of the adsorbed water (Ea) were calculated, and they were found to be higher, namely, from 160 to 190 kJ mol-1, for fibrous clay minerals compared to lamellar structures, ranging in this latter case from 80 to 100 kJ mol-1. The thermal treatment enhances the rehydration in Na-montmorillonite, stevensite, and sepiolite structures with a decrease in the energy required to remove it, while Ea increases significantly in palygorskite (from 164 to 273 kJ mol-1). As a proof of concept, the MTGA results are statistically correlated, together with a full characterization of the physico-chemical properties of the five clay minerals, with the adsorption of two molecules, i.e., aflatoxin B1 (AFB1) and β-carotene. Herein, the amount of adsorbed molecules ranges from 12 to 97% for the former and from 22 to 35% for the latter, depending on the particular clay. The Ea was correlated with AFB1 adsorption with a Spearman score of -0.9. When the adsorbed water is forcibly removed, e.g., under vacuum conditions and high temperatures, the structure becomes the most important, decreasing the Spearman score between β-carotene and Ea to -0.6
Facilitating development of special clays by Machine Learning techniques
No full textTesis por compendio de publicaciones.The initial sections of Chapter 1 introduce the main goal of this Industrial PhD Thesis and offer
an insight on the physico-chemical properties of special clays and their main application fields that
are specifically targeted throughout this PhD thesis. The State-of-the-art for machine learning tools
in porous materials is also discussed. The latter includes an overview of the datasets, descriptors,
and methodology .
Chapter 2 presents this thesis's achievements, giving a general discussion of the three research
articles published within this PhD work. The discussion also discloses a novel practice of machine
learning models in capturing the synergy between compounds, which is related to the works of Chapters 4 and 5. The latter is expanded in Annex 1 and is expected to be converted into an
additional research publication in the future. A resume of the work realized during the International
stay is given and thoroughly presented in Chapter 6.
Chapter 3 includes the "Machine-Learning-Accelerated Multimodal Characterization and
Multiobjective Design Optimization of Natural Porous Materials" article published in Chemical
Science journal. The contribution demonstrates the first application of machine learning to predict
the morphology and surface activity of natural and modified clay-based materials. The suitable
proposed material representation allowed us to build predictive algorithms which can be exploited
in the design of clay-based acid nanocatalysts.
Chapter 4 moves to "Machine learning-aided design of composite mycotoxin detoxifier material
for animal feed", published in Scientific Reports journal. Random forest was educated by a
historical set of in vitro adsorption data to screen and identify the optimal formulation. The latter
was directly tested in an in vivo trial in collaboration with the Department of Pathobiology,
Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine of Ghent University.
Chapter 5 presents the advantages of coupling the advanced design of experiment tools to machine
learning in the context of rheological additive design. The work was presented in the article Datadriven
experimental design of rheological clay-polymer composites, published in the Industrial &
Engineering Chemistry Research journal. The diversity selection algorithm was arranged to identify
formulations correlated to the most different outcomes. Three top promising composites were
then prepared and tested in their rheological behavior, validating the proposed approach.
Chapter 6 demonstrated the achievements of the work done in collaboration with the Department
of Physics and Chemistry of the University of Palermo during my International stay. The work was completed by running additional experiments in Tolsa laboratories, and the whole story was
converted into a manuscript and recently submitted to Microporous and Mesoporous Materials.
By using modulated thermogravimetric analysis, the behavior of confined water on the structures
of five diverse clays was deeply investigated. The latter allowed us to calculate the activation energy
for the removal of the adsorbed water (Ea) and correlate it to adsorption properties.
Annex 1 presents an extension of the use of machine learning models in capturing the synergy
between components of nanocomposites. The concept was first explored during the development
of the work published and reported in Chapter 4. The predictions of the mycotoxin adsorption
followed a non-linear regression within a linear combination of the compounds in the detoxifier
formulation. The latter was associated with the ability of machine learning models to consider the
synergy between those compounds. The approach was then applied to the work reported in
Chapter 5, observing similar behavior. The results will be adapted as a manuscript to be published
as a research contribution.Programa de Doctorado en Ciencia e Ingeniería de Materiales por la Universidad Carlos III de MadridPresidente: Miguel Ángel Bañares.- Secretario: Diego Martínez del Olmo.- Vocal: Rocío Mercad
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
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