1,720,959 research outputs found
The influence of solid-phase organic carbon on the sorption of hydrophobic organic pollutants in landfill barriers, UK
No full textThe Oxford Clay from Bletchley, the Kimmeridge Clay from Kimmeridge Bay, Dorset, and Tertiary mud (Wittering Formation) from Whitecliff, Isle of Wight, United Kingdom were used as sorbent samples because of their distinctive organic material characteristics (Amorphous organic matter rich and/or phytoclast rich). Organic material was isolated for identification and analysis using a non-acid extraction method (heavy liquid) extraction and traditional methods involving HF digestion. These organic materials were then used to determine influences of extraction on hydrophobic organic contaminants, (toluene and naphthalene) sorption. Organic petrology classification was applied to identify the various types of isolated organic material. Amorphous organic matter from the Kimmeridge Clay displayed a higher sorption capacity (Sorption–desorption distribution coefficient (Kd), Kd = 6,481, 59, 670; for toluene and naphthalene, respectively) compared to literature values. Amorphous organic matter-rich sorbent extracts demonstrated a higher absorption capacity than the phytoclast-rich sorbents (e.g., Wittering Formation, Kd = 219, 10, 134; for toluene and naphthalene, respectively). Implications of results in landfill design/risk assessment and modelling are discussed
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
Assessment of the anaerobic biodegradation potential of MSW
No full textA series of laboratory tests was performed to characterise the anaerobic biodegradation potential of a fresh well-characterised sample of municipal solid waste (MSW). This characterisation included measurement of the quality and quantity of biogas produced, determination of the loss of cellulose and hemicellulose (as indicated by measurements of neutral detergent fibre (NDF) and acid detergent fibre (ADF)) and assessment of various leachate chemical characteristics at key phases during the biodegradation process. Twelve 1-litre high-density polyethylene reactors were filled with 100 g of prepared MSW together with a methanogenic mineral media and a bacterial seed derived from an anaerobic digester. Two other reactors, containing no MSW, were used as blanks. Relationships between the chemical composition of the waste and the capacity for predicting the biochemical methane potential (BMP) of fresh waste are discussed. The methane recovery is presented and discussed in the context of the theoretical yield expected from these reactors and from larger consolidating anaerobic reactors (CARs) used in a parallel study.<br/
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
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