1,720,980 research outputs found
Bioassays for Assessing the Fate of Brassicaceae-derived Biopesticides in Soil and an Analysis of the Kinetics of Myrosinase Isoenzymes from Select Brassicaceae Species
No full textAbstract Seed meal of plants from the family Brassicaceae contains glucosinolates which are hydrolyzed by the endogenous enzyme myrosinase to toxic isothiocyanates which have been shown to be effective for treating a wide array of pest species. Current analytical methods for studying the fate of these pesticides in soil require expensive equipment which may not be affordable for many researchers. The inability of farmers, land managers, and researchers to analyze the fate of these pesticides hinders data collection and may limit the efficacy of current application methods due to the time delay between pesticide application and determination of fate. The overarching goal of this study were to understand the fate of allyl isothiocyanate (AITC) from sinigrin (2-propenyl glucosinolate) in agricultural soil. Specific objectives were 1) to explore the use of bioindicators such as wireworms, Limonius infuscatus for pesticide fate studies which could be assessed in-situ and ex-situ; 2) to study the kinetics of myrosinase isoenzymes from Brassica juncea, Sinapis alba, and Limnanthes alba using sinigrin, glucolimnanthin (m-methoxybenzyl glucosinolate), and sinalbin (4-hydroxylbenzyl glucosinolate) as substrates to assess which myrosinase source will result in the highest production of biopesticide in the soil. Two wireworm bioassays were evaluated. The first assay was used to assess the effects of soil depth and incubation period on the fate of the biopesticides. Pre weighed wireworms were used as bioindicators and isolated at specific depths in soil columns which were treated with B. juncea seed meal. The columns were incubated for 4 or 8 days, then the wireworms were assessed for mass change and mortality. The soil was analyzed for AITC, glucosinolates, sulfate, pH, and electrical conductivity. The second assay assessed the effects of tarping on the efficacy of B. juncea seed meal against wireworms. A single pre weighed wireworm was placed midway in a soil column which was treated with B. juncea seed meal. Columns were covered with a polypropylene sheet to simulate field tarping and were incubated for 2 days, then the wireworms were removed, and their mass, mortality, and vertical location were recorded. The wireworms were transferred to fresh soil with wheat seeds as a food source and monitored weekly for mass change and mortality. Soil was analyzed for AITC, electrical conductivity, and pH. In the first assay, neither depth nor incubation period significantly affected wireworm mortality and mass change; however, meal application, depth, and incubation period did significantly affect soil EC, pH, and sulfate concentration. This may be due to glucosinolate hydrolysis as well as acids and ionic compounds in the meal. In the second assay, wireworms in treated columns which were tarped showed significantly higher mortality than wireworms in treated columns which were uncovered which did not show significantly different mortality rates than those in the control columns, suggesting AITC volatilization may significantly reduce, or completely negate the effects of biopesticide. Treatment also had a significant effect on pH, and electrical conductivity. The myrosinase isoenzyme from S. alba showed the highest maximum activity of the three isoenzymes with sinigrin and glucolimnanthin as substrates. The maximum activity of S. alba with sinigrin and glucolimnanthin was significantly higher than the maximum activity of B. juncea; however, B. juncea myrosinase had a significantly greater affinity for both sinigrin and glucolimnanthin. S. alba had the greatest Vmax with sinigrin as a substrate and had similar maximum activities for both glucolimnanthin and sinalbin. This may be due to the similarity in structure of these aromatic glucosinolates. B. juncea myrosinase exhibited Michaelis Menten kinetics for sinigrin and glucolimnanthin but showed signs of substrate inhibition for sinalbin. This suggests that there may be an allosteric binding site on the B. juncea myrosinase which selectively binds sinalbin. The myrosinase extract from L. alba showed negligible activity and may have degraded prior to extraction.masters, M.S., Soil & Water Systems -- University of Idaho - College of Graduate Studies, 2022-0
ADDRESSING 2,4-DNT SOIL CONTAMINATION THROUGH AN INTEGRATED REMEDIATION APPROACH OF BIOCHAR AND ZERO-VALENT IRON (ZVI)
No full textToxic contamination of soil and groundwater from 2,4-Dinitrotoluene (2,4-DNT), a nitroaromatic used in manufacturing munitions and polyurethane foams, presents a high risk for environmental contamination and human health. To mitigate this risk, we propose employing an integrated remediation approach for 2,4-DNT contaminated soils using a combination of biochar and zero-valent iron (ZVI). Biochar, a pyrolysis product of organic biomass, has a high sorption capacity for organic contaminants, reducing their mobility and bioavailability in soil. At the same time, ZVI acts as a reductant, facilitating the breakdown of organic contaminants. The study was conducted using environmentally relevant concentrations of 2,4-DNT representing soil samples from an abandoned army ammunition plant. The sorption capacity of four biochars produced from different feedstocks for 2,4-DNT was evaluated using batch experiments. The efficacy of ZVI for the reductive degradation of 2,4-DNT was evaluated using ZVI of three grain sizes. Concentrations of 2,4-DNT and its primary degradation product 2,4-diaminotoluene (DAM) were monitored using high performance liquid chromatography with diode array detection. Based on the dissipation of 2,4-DNT, the most effective combination was biochar produced from hardwood feedstock at 900°C pyrolysis temperature paired with the finest grain size of ZVI. Both materials were effective individually and exhibited additive or synergistic interactions when combined, resulting in more than 98% removal of 2,4-DNT. The proposed approach presents a promising remediation pathway for soils contaminated with 2,4-DNT. By treating the affected soil, both mitigation of existing contamination and prevention of further leaching into groundwater can be achieved
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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