1,720,986 research outputs found
High-temperature behaviour of fluorcarletonite, KNa4Ca4Si8O18(CO3)4(F,OH)⋅H2O, from the Murun Alkaline Complex, Russia, appraised by experimental and theoretical methods
No full textThe thermal behaviour of fluorcarletonite, KNa4Ca4Si8O18(CO3)4(F,OH)⋅H2O, from the charoitites of the Severny district at the Malyy Murun massif, Murun complex, NW Aldan Shield, Siberia, Russia, has been investigated in order to understand the temperature-induced changes in the crystal structure of this rare silicate. The study has been carried out combining in situ high-temperature single-crystal X-ray diffraction (T range 25–550°C), ex situ high-temperature Fourier-transform infrared spectroscopy (25–700°C) and ab initio calculations. An increasing trend of lattice parameters and cell volume was observed in the 150–550°C temperature range, when the mineral underwent a progressive dehydration process. At 550°C ~40% water loss was detected. If compared with the fluorcarletonite structure at room temperature, the partially dehydrated fluorcarletonite shows: the same space group (P4/mbm); increased distances between the oxygens of the H2O molecules (O11w and O12w) and their Na-centred octahedral cations (Na1 and Na2, respectively); distortion of the four- and six-member tetrahedral rings of the double silicate layer. The dehydration process mainly involves the oxygen at the O11w site which has a different local environment with respect to the oxygen at the O12w site. At T > 600°C, the complete dehydration is accompanied by deprotonation of the OH groups substituting for the F atoms and by the collapse of the structure when the CO2 is released. The adopted approach allowed definition of the temperature thresholds at which modifications occur in the fluorcarletonite crystal structure when subjected to controlled heating conditions. Our findings contribute to assessment of stability, reactivity and, more generally, the thermal behaviour of sheet silicates with fluorcarletonite-like topology
Doronzo MD, Schingaro E, Armstrong-Altrin J S, Zoheir B (Editors) 2019 Petrogenesis and Exploration of the Earth's Interior . Proceedings of the 1st Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Tunisia 2018. Springer 2019 ISSN 2522-8714 ISSN 2522-8722 (electronic) Advances in Science, Technology & Innovation IEREK Interdisciplinary Series for Sustainable Development ISBN 978-3-030-01574-9 ISBN 978-3-030-01575-6 (eBook) https://doi.org/10.1007/978-3-030-01575-6
No full textThe Earth’s interior is a source of heat, which attributes our planet a uniquely distinctive feature. It is actually the heat source that helps regulate the formation and evolution of rocks toward larger scales, while trending minerals and sediments toward minutely smaller scales. In this respect, the exploration of georesources (by-products) has to be closely related to pet- rogenesis (processes). Indeed, one of the major challenges encountered in quantitative geo- sciences lies in the eager attempt to retrieve the unknown causes of well-known effects, or inversely, predicting the unknown effects of well-known causes. It is actually in this junction that the beauty of science generally resides. More particularly, our planet is an ever-lasting stronghold of surprises worth of exhaustive studies, ranging from the inner thermodynamic processes affecting rocks evolution to the outer by-products characterizing exploration. Noteworthy, also, is that any geodynamic context proves to display peculiar geological, mineralogical, and petrological aspects, which help characterize the wide range of geographic areas lying on the surface.
These proceedings’ volume is an outcome of the best-selected papers, accepted for pre- sentation at the first Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Tunisia 2018. The book exhibits a selection of the most recently conducted studies dealing with the area of rocks’ petrogenesis and exploration of georesources, elaborated by experi- enced researchers from, but not limited to, well-established research institutes based in the Mediterranean and Mid-Eastern regions. The major raised themes and issues include, mainly, the composition and thermodynamics of rocks, mineralogy and mineral resources, geology and exploration of ore deposits, geochemistry, and provenance of sediments. This volume should provide new insights into the processes and products associated with the Earth’s interior and the relating georesources. More specifically, the most recently drawn observations and proxy datasets, as figured in the book, should help fill some important gaps persisting in the existing mineralogical, geochemical, petrological, and volcano-logical records across, but not restricted to, the Mediterranean and Mid-Eastern regions.
Barcelona, Spain Domenico M. Doronzo
Bari, Italy Emanuela Schingaro
Mexico City, Mexico John S. Armstrong-Altrin Benha, Egypt/Kiel, Germany Basem Zoheir
July 201
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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