1,720,994 research outputs found
Quantification des fluoroquinolones, du triclosan et du triclocarban dans les eaux usées et les biosolides par SPE en ligne couplée à l’UHPLC MS/MS
Full text linkLes répercussions de la propagation de la résistance aux antimicrobiens (RAM) sont préoccupantes et requièrent une mobilisation mondiale coordonnée et urgente. L’utilisation de biosolides contaminés en tant qu’engrais dans le cadre de l’économie circulaire favorise le retour des produits pharmaceutiques consommés par les humains aux sols agricoles, créant une voie de contamination connue sous le nom de « feces-to-farm » (des excréments à la ferme). Ce mémoire se concentre sur la quantification de 33 produits pharmaceutiques dans les sous-produits des stations de traitement des eaux usées (STEP) comme source potentielle de dissémination de la RAM. À cette fin, deux méthodes analytiques ont été développées, utilisant la SPE en ligne couplée à l'UHPLC-MS/MS, pour l’analyse simultanée et ciblée des 33 composées dans les eaux usées, les boues et les biosolides. Les composés ciblés comprennent 31 antibiotiques de la famille des fluoroquinolones ainsi que deux antibactériens le triclosan (TCS) et le triclocarban (TCC).
Les méthodes mises au point ont été validées dans les matrices correspondantes, et leurs limites spécifiques de détection (LOD) et de quantification (LOQ) étaient jusqu'à 400 fois inférieures à celles des méthodes rapportées dans la littérature, utilisant une instrumentation similaire et visant un nombre restreint d'antibiotiques dans les deux matrices. En outre, la méthode développée pour l'analyse des échantillons d'eaux usées permet une analyse directe, sans nécessiter d'étape de préparation d’échantillon manuelle, contrairement aux techniques disponibles dans la littérature. L'extraction des échantillons de biosolides a été réalisée grâce à une extraction assistée par ultrasons (UAE). Les méthodes développées se distinguent par leur grande sensibilité, une large gamme de linéarité (de 10 ng·L⁻¹ à 5 µg·L⁻¹ et de 0,6 µg·kg⁻¹ à 1 mg·kg⁻¹), ainsi qu'une grande précision, avec des RSD inférieurs à 3 % pour la majorité des antibiotiques ciblés.
Les méthodes ont été mises en œuvre avec succès pour la quantification des antimicrobiens ciblés dans des échantillons de biosolides ainsi que dans des échantillons d'eaux usées d’influents d’effluents, provenant de 12 STEPs situées dans 6 provinces canadiennes. Les résultats révèlent la présence d'antibiotiques FQs, ainsi que les agents antibactériens TCS et TCC dans l'ensemble des échantillons analysés. Les concentrations observées dans les biosolides variaient de 0,96 μg·kg⁻¹ à 4,4 mg·kg⁻¹ pour les FQs, de 1,9 à 10 mg·kg⁻¹ pour le TCS, et de 3,4 à 1,3 mg·kg⁻¹ pour le TCC. En revanche, les concentrations dans les échantillons d'eaux usées étaient plus faibles, allant de 12 à 73 ng·L⁻¹ pour les FQs, de 4 à 35 ng·L⁻¹ pour le TCS et de 24 à 44 ng·L⁻¹ pour le TCC.The impact of the spread of antimicrobial resistance (AMR) is alarming and requires urgent and coordinated global mobilization. The use of contaminated biosolids as fertilizer within the circular economy initiative promotes the return of pharmaceuticals consumed by humans to agricultural soils, creating a contamination pathway known as “feces-to-farm”. This thesis focuses on the quantification of pharmaceuticals in wastewater treatment plant (WWTP) by-products as a potential source of AMR dissemination. To this end, two analytical methods have been developed, using on-line SPE coupled to UHPLC-MS/MS, for the simultaneous analysis of 33 targeted pharmaceuticals in wastewater, sludge and biosolids. Targeted compounds include 31 different fluoroquinolones antibiotics as well as two antimicrobials, triclosan (TCS) and triclocarban (TCC).
The methods developed have been validated in the corresponding matrices, and their specific limits of detection (LOD) and quantification (LOQ) were up to 400 times lower than those of methods reported in the literature using similar instrumentation, while targeting a smaller number of antibiotics. The method developed for the analysis of wastewater samples enables direct analysis, without a manual preparation step, unlike most techniques in the literature. Biosolids samples were extracted using ultrasonic-assisted extraction (UAE). Both methods feature high sensitivity, a wide linearity range (10 ng·L-1 – 5.0 μg·L-1 and 0.6 μg·kg-1 - 1 mg·kg-1), and high precision, with RSDs below 3% for most of the targeted antibiotics.
The developed methods were successfully applied to the quantification of the targeted pharmaceuticals in biosolids samples as well as in influent and effluent wastewater samples from 12 wastewater treatment plants located in 6 Canadian provinces. The results reveal the presence of fluoroquinolone antibiotics, as well as antimicrobial agents such as TCS and TCC in all the samples analyzed. Concentrations in biosolids ranged from 0.96 mg·kg-1 to 4.4 mg·kg-1 for fluoroquinolones (FQ), from 1.9 to 10 mg·kg-1 for TCS, and from 3.4 to 1.3 mg·kg-1 for TCC. In contrast, concentrations in wastewater samples were lower, ranging from 12 to 73 ng·L-1 for fluoroquinolones, 4 to 35 ng·L-1 for TCS and 24 to 44 ng·L-1 for TCC
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
Molecular and phenotypic characterization of the microbial communities in two pulp and paper wastewater treatment systems
No full textPhylogenetic hybridization and phenotypic fingerprinting were applied to the analysis of bacterial communities in wastewater treatment systems. These approaches were aimed at (i) developing monitoring tools able to foresee operational problems, and (ii) providing the rationale to optimize the operation of bioreactors. The work presented is intended to first describe the community found in two reactors treating pulp and paper mill effluent, and second evaluate the possibilities of these techniques with respect to the development of new monitoring tools.Phylogenetic membrane hybridization showed that the bacterial communities were dominated by Alpha and Beta Proteobacteria, a structure probably linked to the low F:M ratio. Other important factors determining the community structure were the proportion of COD in the high molecular weight fraction, the sludge age, phosphate addition, and the concentration of specific compounds (alcohols, phenols, volatile fatty acids) in the influent. The community structure partly determined the sludge characteristics demonstrating its potential value in the assessment of reactor performance. The results obtained by phylogenetic membrane hybridization suggest that the probes used in a monitoring tool would not need to be targeted to the species level to provide relevant information. However, they also suggest that the technique is more sensitive to changes in population density as opposed to changes in bacterial metabolism.Phenotypic fingerprinting measured a smaller difference between the communities of the two reactors studied than what was measured by phylogenetic membrane hybridization. However, differences in heterotrophic activities observed between the two communities were linked to differences in influent composition
Proposed Mechanism Explaining Seasonal Biological Foaming in Activated Sludge Systems; Foam-Causing Bacteria Specialize in Consuming Lipids
No full text239 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.The validity of this mechanism was first tested by studying the relationship between lipase (lipid hydrolyzing enzyme) activity, temperature, and foam occurrences. Lipase activity was found to be higher in foaming plants and very sensitive to temperature, substantiating the role of temperature in seasonal biological foaming. The validity of the assumption that the mycolata specialize in consuming lipids, which are slowly degradable substrates, was also tested. To this end, a model capable the predicting the dynamics of the cellular rRNA pool was developed and validated. This model predicted that the diurnal rRNA profile of a population consuming slowly degradable substrates remains stable throughout the day. Conversely, the diurnal rRNA profile of a population consuming readily degradable substrates varies due to variations in COD loading rates. Thus, the modeling exercise linked the molecular identification of microbial populations and the determination of their ecological function. Diurnal rRNA profiles were then measured for bacterial populations found in full-scale activated sludge wastewater treatment plants, and the experiment support the assumption that mycolata specialize in consuming lipids.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD
Proposed Mechanism Explaining Seasonal Biological Foaming in Activated Sludge Systems; Foam-Causing Bacteria Specialize in Consuming Lipids
No full textThe validity of this mechanism was first tested by studying the relationship between lipase (lipid hydrolyzing enzyme) activity, temperature, and foam occurrences. Lipase activity was found to be higher in foaming plants and very sensitive to temperature, substantiating the role of temperature in seasonal biological foaming. The validity of the assumption that the mycolata specialize in consuming lipids, which are slowly degradable substrates, was also tested. To this end, a model capable the predicting the dynamics of the cellular rRNA pool was developed and validated. This model predicted that the diurnal rRNA profile of a population consuming slowly degradable substrates remains stable throughout the day. Conversely, the diurnal rRNA profile of a population consuming readily degradable substrates varies due to variations in COD loading rates. Thus, the modeling exercise linked the molecular identification of microbial populations and the determination of their ecological function. Diurnal rRNA profiles were then measured for bacterial populations found in full-scale activated sludge wastewater treatment plants, and the experiment support the assumption that mycolata specialize in consuming lipids.Made available in DSpace on 2015-09-25T21:03:57Z (GMT). No. of bitstreams: 2
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Previous issue date: 2005Embargo set by: Seth Robbins for item 84540
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only239 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005
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