1,720,954 research outputs found
Superabsorbent polymer nanocomposites as water reservoir for the sustained release of active agents
No full textGlobally, 80% of all farmlands is rainfed, making irregular rainfall regimes a significant threat to food security. Farmers urgently need technologies that minimize water loss toalleviate yield loss in times of drought. Fertilizers and plant protection products (PPPs)are crucial for improved yields. However, the bulk application of these agrochemicals can lead to environmental leaching due to runoff and evaporation. Sustained delivery canimprove the efficiency of agrochemicals.To address the above-mentioned challenges, we propose superabsorbent polymer (SAP)nanocomposites as underground water reservoirs with the ability to integrate water andactive agent delivery. SAPs absorb water during rainfall and release it during dry spells.Composite SAPs can allow sustained delivery of agrochemicals, prevent their runoff due to heavy rainfalls, and keep them closer to the root area for optimum plant uptake.In this study, fertilizer-SAP composites containing 17 wt% micronutrients have achievedsuperior water absorption capacities of 1460-1630 g/g, compared to 500 g/g for traditional SAPs.Commercial SAPs have very limited biodegradability. Developing biodegradable SAP formulations is important to combat plastic accumulation in agricultural lands. There is a lack of studies on bio-SAPs with 25-70 wt% biomaterial contents. We have incorporated 5-60 wt% carboxymethyl cellulose (CMC) into an otherwise polyacrylate-based SAP formulation. A maximum water absorption of 600 g/g was achieved with SAP containing 10 wt% CMC. Up to 40 wt% CMC, SAPs exhibited waterabsorption comparable to commercial SAPs. SAPs with 40 wt% or more CMCbiodegraded completely by cellulase enzyme within 3 days
Synergistic incorporation of calcium and zinc fertilizers in superabsorbent polymers
No full textMineral fertilizers and water are essential for food production, and their sustained delivery is imperative to maximize crop yields. During heavy rainfalls, fertilizers can leach into the environment. During drought, fertilizers cannot dissolve in the soil. Superabsorbent polymers (SAP) can improve soil water retention capacity, by absorbing water during rainfall and releasing it during dry periods. In this study, we have integrated varying levels of calcium nitrate and zinc sulfate in an SAP to achieve fertilizer-SAP composites. Fertilizer-SAP composites can both help alleviate fertilizer leaching during heavy rainfall and facilitate their dissolution during dry periods, thank to moisture they absorb from the soil. SAP composites can also slow down the release of nutrients and keep them closer to the root area, for optimum plant uptake. Furthermore, we have observed a synergistic effect of nutrient incorporation in SAP, manifested by the enhanced water uptake of composites compared to pure SAP. For instance, SAP composites with 17 wt% zinc sulfate and calcium nitrate achieved superior water absorptions of 1462 and 1626 g/g, respectively. In comparison, pure SAP in this study reached approximately 800 g/g, and most commercial SAPs have water absorption capacities of 500 g/g. Suggested SAP application is often reported as 15–45 kg per hectare, in the literature. In comparison, the recommended zinc and calcium doses are as low as 3–5 kg/ha. Therefore, by a single fertilizer-SAP application, farmers can cover both the SAP and zinc, or calcium demands of their fields
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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