1,720,960 research outputs found
Stress responses and nickel and zinc accumulation in different accessions of Stellaria media (L.) Vill. in response to solution pH variation in hydroponic culture
Full text linkIn most non-hyperaccumulating plants, Ni and Zn uptake is negatively correlated with soil pH, however, few studies so far have investigated how pH influences the activity and uptake of Ni and Zn in plants grown in a hydroponic system, which generally allows culture variables to be singularly manipulated. In this study, the non-accumulator Stellaria media (L.) Vill. (Caryophyllaceae) had opposite trends of Ni and Zn uptake along a pH gradient (between 5 and 8 for Zn and between 5 and 6.5 for Ni), when grown in hydroponics. In all treatments, the solution metal concentration was fixed at 0.1\ua0mM Ni or 0.55\ua0mM Zn. Nickel accumulation increased with increasing pH with an average concentration in shoots of 167 μg/gDW at pH 5 and of 250 μg/gDW at pH 6.5. In contrast, Zn accumulation decreased with increasing pH, with an average concentration in shoots varying from 1640 μg/gDW, at pH 5, to 435 μg/gDW at pH 8. Assessment of total polyphenol and flavonoid contents and of antioxidant activity showed that these parameters were positively correlated with Ni or Zn accumulation in S. media shoots, while photosynthetic pigments content and root and shoot biomass were negatively correlated with Ni and Zn accumulation. The study was carried out on five different S. media populations, which did not show differences in relation to the accumulation of metals and synthesis of antioxidant compounds, nonetheless showing a different biomass production under control conditions
Nickel hyperaccumulator plants and nickel phytomining - fundamental root-associated mechanisms and potential applications
No full textNickel-hyperakkumulierende und -tolerante Pflanzen haben verschiedene Mechanismen entwickelt, um auf Nickel-reichen Böden wachsen zu können. Hyperakkumulatoren können extrem hohe Ni Konzentrationen in ihrer oberirdischen Biomasse aufnehmen, während Exkluder die Ni-Aufnahme und -Translokation in den Spross weitgehend verhindern. Die dabei involvierten Prozesse sind teilweise noch unbekannt. Die Klärung der Mechanismen hinter der Hyperakkumulation ist auch im Hinblick auf Anwendungen wie zum Beispiel Phytomining wichtig. Im ersten Teil dieser Arbeit wurde untersucht, wie das Wurzelsystem von Hyperakkumulator- und Exkluder-Pflanzen mit der räumlichen Verteilung von Ni im Substrat interagiert. Räumlich differenziertes Wurzelwachstum kann Hinweise auf Nährstoffbedarf sowie die Reaktion auf heterogene Metall-Konzentrationen liefern und damit das Verständnis der Metallhyperakkumulations- und -exkludermechanismen verbessern. Um die Reaktion des Wurzelsystems, also gezieltes Wachstum oder Vermeidungsreaktionen, in Bezug auf die räumliche Verteilung von Nickel im Boden zu erfassen, wurden die Wurzelwachstumsreaktionen des Hyperakkumulators Noccaea caerulescens und der metalltoleranten Art Stellaria media untersucht. Der zweite Teil dieser Arbeit befasst sich mit der Eignung von Ni Hyperakkumulator für Phytomining auf Ni- reichen Abfallstoffen. Die Hyperakkumulatorpflanze Odontarrrhena chalcidica wurde auf verschiedenen galvanischen Schlämmen kultiviert und das Akkumulationsverhalten untersucht. Kapitel 3 bietet eine Übersicht über den derzeitigen Kenntnisstand zu Nickel-Phytomining auf Abfällen. Insgesamt wurden in der vorliegenden Arbeit neue Kenntnisse zur Hyperakkumulation sowie zu Nickel-Vermeidungsstrategien gewonnen und dazu beigetragen, das Wissen über mögliche Anwendungen zu erweitern. Durch die Zusammenfassung des aktuellen Wissens über Phytomining auf Abfallsubstraten hat diese Arbeit außerdem eine klarere Orientierung für das Phytomining von Abfällen geliefert.Nickel hyperaccumulator and tolerant plants have developed mechanism to tolerate substrates enriched with Ni. Hyperaccumulator plants are capable to uptake extremely high Ni concentrations in their above ground biomass, while excluder plants are able to prevent Ni uptake at the root level. Nickel hyperaccumulation and exclusion processes are still not fully clarified and research is needed in this direction. Clarifying the mechanisms behind hyperaccumulation would also be beneficial in terms of applications as Ni phytomining. In the first part of this work, it was investigated how the root system of hyperaccumulator and excluder plants interacts with Ni in the substrate. Root behaviour can reveal the metabolic needs and adaptations of plant species and indirectly enhance the understanding of the metal hyperaccumulation and exclusion mechanisms. In order to observe root foraging vs avoidance responses to Ni, the root growth responses of the hyperaccumulator Noccaea caerulescens and of the metal tolerant Stellaria media have been investigated. The second part of this work considers the use of Ni hyperaccumulator plants for phytomining applications on Ni-rich waste materials; to test its adaptation and phytomining potential, the hyperaccumulator plant Odontarrrhena chalcidica was cultivated on different types of galvanic sludges. Additionally, a review about waste phytomining was included in the second part of this work, summarizing the current state of the art about metal phytomining on waste materials and merging knowledge and experiences gained from recent studies. By studying three different metalliferous species, this work has clarified new features of Ni hyperaccumulators and excluder plants and has contributed to enhance the knowledge about their physiology, adaptation and potential applications. Furthermore, by reviewing current knowledge about phytomining on waste substrates, this work has provided a clearer orientation on waste phytomining.submitted by: Alice TognacchiniDissertation Universität für Bodenkultur Wien 2021Zusammenfassung in deutscher Sprach
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
Ethylenediamine-N,N′-Disuccinic Acid (EDDS)—Enhanced Flushing Optimization for Contaminated Agricultural Soil Remediation and Assessment of Prospective Cu and Zn Transport
Full text linkThis paper presents the results of an experimental study aimed at investigating the effect of operative parameters on the efficiency of a soil flushing process, conducted on real contaminated soil containing high amounts of Cu and Zn. Soil flushing tests were carried out with Ethylenediamine-N,N'-disuccinic acid (EDDS) as a flushing agent due to its high biodegradability and environmentally friendly characteristics. Process parameters such as Empty-Bed Contact Time (EBCT) and EDDS solution molarity were varied from 21-33 h and from 0.36-3.6 mM, respectively. Effects on the mobility of cations such as Fe and Mn were also investigated. Results showed that very high performances can be obtained at [EDDS] = 3.6 mM and EBCT = 33 h. In these conditions, in fact, the amount of removed Cu was 53%, and the amount of removed Zn was 46%. Metal distribution at different depths from the top surface revealed that Cu has higher mobility than Zn. The process results were strongly dependent on the exchange of metals due to the different stability constants of the EDDS complexes. Finally, results from a comparative study showed that soil washing treatment reached the same removal efficiency of the flushing process in a shorter time but required a larger amount of the EDDS solution
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
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