1,720,955 research outputs found
Microbial generation of highly magnetic iron sulphide for heavy metal recovery
No full textBiosorption of heavy metals using microbial biomass sorbents has been extensively studied in the laboratory with the view, to eventual commercial application. Microbially produced iron sulphide biosorbents are known to have a high affinity for heavy metals and magnetic properties which have the potential for use in biomagnetic separation processes. However, unwillingness to change from conventional methods, combined with the poor economic viability of the biomass separation has stalled commercial exploitation. This study examined the use of a mixed sulphate reducing bacteria population to produce a highly magnetic sulphide to enable easy, magnetic separation recovery. Sorption/desorption behaviour of the microbially produced sulphide on typical heavy metals found in commercial effluents was also investigated. low cost Culturing of the magnetic biosorbent using a mixed iron, ferrous rich modified Postgate growth medium and an alternating batch-continuous growth cycle produced a material with a magnetic susceptibility an order of magnitude greater than previously documented. and x-ray diffraction tests indicated the presence of iron, sulphur (elemental and sulphide) and phosphate. Mackinawite (FeSi-x) was inferred as the magnetic iron sulphide. Characterisation using chemical metals to the sulphide followed the Langmuir isotherm model Sorption of suggesting the occurrence of monolayer binding. uptake affinity followed the order Cd>Zn>Cu>Ni, with the maximum calculated sorption capacity being an order of magnitude greater than other commercially tested biomasses, indicating its efficiency on a single application and suitability for commercial applications. Ethylenediamine-tetra-acetic acid (EDTA) was found to eluting 30-90% of the bound metal. be the most However the biomass oxidised during the process and subsequent sorption efficiency was poor. effective desorbing agent The studied metal In summary, this thesis describes a pathway to produce a highly magnetic iron sulphide and characterises its biosrobent properties. The work has demonstrated the potential of this material to be applied to heavy metal pollutant recovery.</p
Fluorescent tracers - a tool for landfill investigation and management
No full textThe paper presents a three-stage framework for assessment of fluorescent dyes as tracers for use within Municipal Solid Waste (MSW) landfills. The value of tracer testing as a means of determining leachate behaviour and guiding leachate management strategies is explained. In the first stage, the fluorescence spectra of 27 leachates were compared with 30 fluorescent dyes, to find those dyes for which there was little interference from leachate. Fluorescein (Uranine), Eosin-Y and Rhodamine WT were selected. In a second stage, the dyes’ resistance to biodegradation by anaerobes was tested. Fluorescein and Rhodamine resisted degradation but Eosin was moderately degraded. In the final stage, all three dyes were sorbed on shredded MSW, with results fitted to Freundlich isotherms. It was concluded that Rhodamine WT was the most suitable quantitative tracer, as modelling its behaviour would require only a single parameter to be fitted. Eosin would require parameters for linear sorption and degradation. Fluorescein was shown to be an excellent qualitative tracer
Development of a highly magnetic iron sulphide for metal uptake and magnetic separation
No full textMicrobial iron sulphide (FeS) is a well-known absorbent for heavy metals which has the potential to be used in biomagnetic separation. This paper illustrates that highly magnetic Fes can be produced from bioreactors which are continually switched between batch and continuous culture modes. Cadmium metal uptake studies highlight the sulphide absorbent properties of the Fes produced
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
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