1,721,031 research outputs found
Investigating the Interaction of Water Vapour with Aminopropyl Groups on the Surface of Mesoporous Silica Nanoparticles
No full textThe interaction of water molecules with the surface of hybrid silica-based mesoporous materials is studied by 29Si, 1H and 13C solid-state NMR and IR spectroscopy, with the support of ab initio calculations. The surface of aminopropyl-grafted mesoporous silica nanoparticles is studied in the dehydrated state and upon interaction with controlled doses of water vapour. Former investigations described the interactions between aminopropyl and residual SiOH groups; the present study shows the presence of hydrogen-bonded species (SiOH to NH2) and weakly interacting “free” aminopropyl chains with restricted mobility, together with a small amount of protonated NH3 + groups. The concentration of the last-named species increased upon interaction with water, and this indicates reversible and fast proton exchange from water molecules to a fraction of the amino groups. Herein, this is discussed and explained for the first time, by a combination of experimental and theoretical approaches. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei
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
Synthesis and Characterization of Lignin-Derived Porous Materials from Phyllostachys edulis (Bamboo Moso) for the Removal of Aromatic Pollutants
Full text linkIn recent decades, pollution from dyes has increasingly attracted the attention of researchers. For this reason, the development of new materials capable of sequestering this type of pollutant has been extensively studied, especially as research using plant biomass to produce new materials. Considerable
attention has been directed toward bamboo moso, which has been the focus of extensive studies. The chemical composition of bamboo culms indicates that cellulose and hemicellulose comprise 65−70%, whereas lignin accounts for 18−30%. In this study, lignin has been extracted from bamboo culms using the hydrothermal methodology under basic conditions. Water-soluble lignin was dispersed in a porogenic organic solvent and polymerized via the Friedel-Craft alkylation reaction. 13C CPMAS NMR spectroscopy was used to study the modification of the water-soluble lignin before and after polymerization; the peaks related to the linker reaction were detected and confirmed the successful cross-linking reaction. The biopolymer-composite was also characterized by FTIR spectroscopy to explore the surface functionality and its interaction with the aromatic molecules, using toluene as a model compound. To gain a deeper understanding of the surface properties, N2 physisorption analysis was performed at 77 K. To evaluate the material’s capacity to act as an adsorbent for organic dyes, the adsorption kinetics of organic pollutants were simulated using Crystal Violet as a model molecule, tracking the adsorption trends through UV−vis spectroscopy. In this context, the adsorption capacity of Crystal Violet was determined to exceed 98% within the initial 4 h period
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
Durability of blended cements containing sulfoaluminate clinker
No full textThe cement industry is strongly committed to a very ambitious "zero emission"trajectory maintaining the highest level of quality and durability performances. Zero emission target will be reached using several leverages, including the reduction of the clinker content in cement. Low clinker cement represent a market solution and are already efficiently implemented in many European countries, however, the strength development of low clinker cement at early age is lower compared to Ordinary Portland Cements (OPC) with higher clinker contents. The use of blends of low clinker Portland cement and Calcium Sulfoaluminate Cement (CSA) could support the need for low CO2 binder with high early strength. The behavior of four blended cements containing CSA clinker, OPC clinker, limestone, fly ash, pozzolana and slag has been characterized using different techniques in terms of resistance to carbonation, chloride migration and sulfate attack. The findings indicate that the durability performances are enhanced when supplementary cementitious materials (SCMs) with pozzolanic or latent hydraulic activity are present, as opposed to the presence of limestone. SCMs exhibit an active role also in an OPC-CSA matrix. Blend of CSA-OPC cement and slag represents a system characterized by both high early and late strengths, along with favorable durability behavior
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