1,720,959 research outputs found
Étude de matériaux photocatalytiques à base de phosphates et d'oxychlorures de bismuth x Bi3O4Cl / (1-x) BiPO4 pour la dégradation de polluants organiques sous irradiation visible
No full textThe main aim of this thesis was to develop materials based on bismuth phosphates and oxychlorides (BiPO4, Bi3O4Cl and Bi24O31Cl10) for photocatalytic applications in aqueous media. From these basic phases, particular attention was paid to the properties of two-phases or composite systems, likely to exhibit heterojunctions. The applications targeted were the photodegradation of organic pollutants, dyes such as rhodamine B, methylene blue, Methyl orange and Congo red on the one hand, and drugs such as amoxicillin and sulfadiazine on the other. The materials developed were subjected to thermal, structural, microstructural, optical, vibrational, electronic and photoluminescent characterizations.In the first stage, BiPO4 bismuth phosphates, obtained by co-precipitation in an acid medium, followed by thermal treatment at 400 to 550°C, were used to photodegrade the various organic pollutants selected: the two-phases system of monoclinic polymorphs nMBIP/mMBIP, obtained at 500°C, showed the best photocatalytic efficiency of the series under UV irradiation. This improved efficiency was attributed to the formation of heterojunctions between polymorph phases. In a second step, the synthesis of Bi3O4Cl and Bi24O31Cl10 oxychlorides and Bi3O4Cl/Bi24O31Cl10 two-phases system was undertaken, and their photocatalytic properties were compared. The Bi3O4Cl/Bi24O31Cl10 system performed best. This enhanced performance was attributed to the formation of Z-scheme heterojunctions between Bi3O4Cl and Bi24O31Cl10. These heterojunctions were visualized by the growth process of 2D Bi3O4Cl nanosheets on the 3D surface of Bi24O31Cl10 micro-grains. In a third step, composite systems [xBi3O4Cl + (1-x)BiPO4] with variable composition with 0 < x < 1 were elaborated by the solid-state reaction, and their photocatalytic efficiencies under visible irradiation were analyzed. The composite with composition x = 0.7 (0.7Bi3O4Cl/0.3BiPO4) revealed the highest photocatalytic efficiencies of the series. This performance was partly attributed to the formation of [Bi3O4Cl/BiPO4] heterojunction type P-N between the original Bi3O4Cl and BiPO4 materials. The mechanisms of photodegradation of organic pollutants, induced by the various photocatalysts, as well as the effect of acid/base environment on photocatalytic performance were discussed in this work.L'objectif principal de la thèse était de développer des matériaux à base de phosphates et d'oxychlorures de bismuth (BiPO4, Bi3O4Cl et Bi24O31Cl10) pour applications photocatalytiques en milieu aqueux. A partir de ces phases de base, une attention particulière s’est portée sur les propriétés de systèmes biphasés ou composites, susceptibles de présenter des hétérojonctions. Les applications visées portaient sur la photodégradation de colorants comme la rhodamine B, le bleu de méthylène, l’hélianthine, le rouge Congo d’une part, et des médicaments comme l’amoxicilline et la sulfadiazine d’autre part. Les matériaux développés ont fait l'objet de caractérisations thermiques, structurales, microstructurales, optiques, vibrationnelles, électroniques et photoluminescentes.Dans une première étape, les phosphates de bismuth BiPO4, obtenus par coprécipitation en milieu acide, puis traitements thermiques de 400 à 550 °C ont été utilisés pour photodégrader les divers polluants organiques choisis : le système biphasé de polymorphes monocliniques nMBIP/mMBIP, obtenu à 500 °C, a montré, la meilleure efficacité photocatalytique de la série sous irradiation UV. Cette amélioration d’efficacité a été attribuée à la formation d’hétérojonctions entre phases polymorphes. Dans une seconde étape, la synthèse d’oxychlorures Bi3O4Cl et Bi24O31Cl10 ainsi que de système biphasé Bi3O4Cl/Bi24O31Cl10 a été entreprise, et leurs propriétés photocatalytiques ont été comparées. Le système biphasé Bi3O4Cl/Bi24O31Cl10 s'est avéré le plus performant sous irradiation visible. Cette meilleure performance a été attribuée à la formation d’hétérojonctions à schéma en Z entre Bi3O4Cl et Bi24O31Cl10. Ces hétérojonctions ont été visualisées par le processus de croissance de nanofeuillets 2D de Bi3O4Cl sur la surface 3D des micro-grains Bi24O31Cl10. Dans une troisième étape, les systèmes composites [xBi3O4Cl + (1-x)BiPO4] à composition variable avec 0 < x < 1 ont été élaborés par la voie solide-solide, et leurs efficacités photocatalytiques sous irradiation dans le visible ont été analysées. Le composite de composition x = 0,7 (0,7Bi3O4Cl/0,3BiPO4) a révélé les efficacités photocatalytiques les plus performantes de la série. Cette performance a été en partie attribuée à la formation d’hétérojonction P-N [P-Bi3O4Cl/N-BiPO4] entre les matériaux primitifs Bi3O4Cl et BiPO4. Les mécanismes de photodégradation des polluants organiques, induits par les divers photocatalyseurs, ainsi que l’effet d’environnement acide/base sur les performances photocatalytiques ont été discutés dans ce travail
Étude de matériaux photocatalytiques à base de phosphates et d'oxychlorures de bismuth x Bi3O4Cl / (1-x) BiPO4 pour la dégradation de polluants organiques sous irradiation visible
No full textThe main aim of this thesis was to develop materials based on bismuth phosphates and oxychlorides (BiPO4, Bi3O4Cl and Bi24O31Cl10) for photocatalytic applications in aqueous media. From these basic phases, particular attention was paid to the properties of two-phases or composite systems, likely to exhibit heterojunctions. The applications targeted were the photodegradation of organic pollutants, dyes such as rhodamine B, methylene blue, Methyl orange and Congo red on the one hand, and drugs such as amoxicillin and sulfadiazine on the other. The materials developed were subjected to thermal, structural, microstructural, optical, vibrational, electronic and photoluminescent characterizations.In the first stage, BiPO4 bismuth phosphates, obtained by co-precipitation in an acid medium, followed by thermal treatment at 400 to 550°C, were used to photodegrade the various organic pollutants selected: the two-phases system of monoclinic polymorphs nMBIP/mMBIP, obtained at 500°C, showed the best photocatalytic efficiency of the series under UV irradiation. This improved efficiency was attributed to the formation of heterojunctions between polymorph phases. In a second step, the synthesis of Bi3O4Cl and Bi24O31Cl10 oxychlorides and Bi3O4Cl/Bi24O31Cl10 two-phases system was undertaken, and their photocatalytic properties were compared. The Bi3O4Cl/Bi24O31Cl10 system performed best. This enhanced performance was attributed to the formation of Z-scheme heterojunctions between Bi3O4Cl and Bi24O31Cl10. These heterojunctions were visualized by the growth process of 2D Bi3O4Cl nanosheets on the 3D surface of Bi24O31Cl10 micro-grains. In a third step, composite systems [xBi3O4Cl + (1-x)BiPO4] with variable composition with 0 < x < 1 were elaborated by the solid-state reaction, and their photocatalytic efficiencies under visible irradiation were analyzed. The composite with composition x = 0.7 (0.7Bi3O4Cl/0.3BiPO4) revealed the highest photocatalytic efficiencies of the series. This performance was partly attributed to the formation of [Bi3O4Cl/BiPO4] heterojunction type P-N between the original Bi3O4Cl and BiPO4 materials. The mechanisms of photodegradation of organic pollutants, induced by the various photocatalysts, as well as the effect of acid/base environment on photocatalytic performance were discussed in this work.L'objectif principal de la thèse était de développer des matériaux à base de phosphates et d'oxychlorures de bismuth (BiPO4, Bi3O4Cl et Bi24O31Cl10) pour applications photocatalytiques en milieu aqueux. A partir de ces phases de base, une attention particulière s’est portée sur les propriétés de systèmes biphasés ou composites, susceptibles de présenter des hétérojonctions. Les applications visées portaient sur la photodégradation de colorants comme la rhodamine B, le bleu de méthylène, l’hélianthine, le rouge Congo d’une part, et des médicaments comme l’amoxicilline et la sulfadiazine d’autre part. Les matériaux développés ont fait l'objet de caractérisations thermiques, structurales, microstructurales, optiques, vibrationnelles, électroniques et photoluminescentes.Dans une première étape, les phosphates de bismuth BiPO4, obtenus par coprécipitation en milieu acide, puis traitements thermiques de 400 à 550 °C ont été utilisés pour photodégrader les divers polluants organiques choisis : le système biphasé de polymorphes monocliniques nMBIP/mMBIP, obtenu à 500 °C, a montré, la meilleure efficacité photocatalytique de la série sous irradiation UV. Cette amélioration d’efficacité a été attribuée à la formation d’hétérojonctions entre phases polymorphes. Dans une seconde étape, la synthèse d’oxychlorures Bi3O4Cl et Bi24O31Cl10 ainsi que de système biphasé Bi3O4Cl/Bi24O31Cl10 a été entreprise, et leurs propriétés photocatalytiques ont été comparées. Le système biphasé Bi3O4Cl/Bi24O31Cl10 s'est avéré le plus performant sous irradiation visible. Cette meilleure performance a été attribuée à la formation d’hétérojonctions à schéma en Z entre Bi3O4Cl et Bi24O31Cl10. Ces hétérojonctions ont été visualisées par le processus de croissance de nanofeuillets 2D de Bi3O4Cl sur la surface 3D des micro-grains Bi24O31Cl10. Dans une troisième étape, les systèmes composites [xBi3O4Cl + (1-x)BiPO4] à composition variable avec 0 < x < 1 ont été élaborés par la voie solide-solide, et leurs efficacités photocatalytiques sous irradiation dans le visible ont été analysées. Le composite de composition x = 0,7 (0,7Bi3O4Cl/0,3BiPO4) a révélé les efficacités photocatalytiques les plus performantes de la série. Cette performance a été en partie attribuée à la formation d’hétérojonction P-N [P-Bi3O4Cl/N-BiPO4] entre les matériaux primitifs Bi3O4Cl et BiPO4. Les mécanismes de photodégradation des polluants organiques, induits par les divers photocatalyseurs, ainsi que l’effet d’environnement acide/base sur les performances photocatalytiques ont été discutés dans ce travail
Study of photocatalytic materials based on phosphates and bismuth oxychlorides xBi3O4Cl/(1-x)BiPO4 for the degradation of degradation of organic pollutants under visible irradiation
No full textL'objectif principal de la thèse était de développer des matériaux à base de phosphates et d'oxychlorures de bismuth (BiPO4, Bi3O4Cl et Bi24O31Cl10) pour applications photocatalytiques en milieu aqueux. A partir de ces phases de base, une attention particulière s’est portée sur les propriétés de systèmes biphasés ou composites, susceptibles de présenter des hétérojonctions. Les applications visées portaient sur la photodégradation de colorants comme la rhodamine B, le bleu de méthylène, l’hélianthine, le rouge Congo d’une part, et des médicaments comme l’amoxicilline et la sulfadiazine d’autre part. Les matériaux développés ont fait l'objet de caractérisations thermiques, structurales, microstructurales, optiques, vibrationnelles, électroniques et photoluminescentes.Dans une première étape, les phosphates de bismuth BiPO4, obtenus par coprécipitation en milieu acide, puis traitements thermiques de 400 à 550 °C ont été utilisés pour photodégrader les divers polluants organiques choisis : le système biphasé de polymorphes monocliniques nMBIP/mMBIP, obtenu à 500 °C, a montré, la meilleure efficacité photocatalytique de la série sous irradiation UV. Cette amélioration d’efficacité a été attribuée à la formation d’hétérojonctions entre phases polymorphes. Dans une seconde étape, la synthèse d’oxychlorures Bi3O4Cl et Bi24O31Cl10 ainsi que de système biphasé Bi3O4Cl/Bi24O31Cl10 a été entreprise, et leurs propriétés photocatalytiques ont été comparées. Le système biphasé Bi3O4Cl/Bi24O31Cl10 s'est avéré le plus performant sous irradiation visible. Cette meilleure performance a été attribuée à la formation d’hétérojonctions à schéma en Z entre Bi3O4Cl et Bi24O31Cl10. Ces hétérojonctions ont été visualisées par le processus de croissance de nanofeuillets 2D de Bi3O4Cl sur la surface 3D des micro-grains Bi24O31Cl10. Dans une troisième étape, les systèmes composites [xBi3O4Cl + (1-x)BiPO4] à composition variable avec 0 < x < 1 ont été élaborés par la voie solide-solide, et leurs efficacités photocatalytiques sous irradiation dans le visible ont été analysées. Le composite de composition x = 0,7 (0,7Bi3O4Cl/0,3BiPO4) a révélé les efficacités photocatalytiques les plus performantes de la série. Cette performance a été en partie attribuée à la formation d’hétérojonction P-N [P-Bi3O4Cl/N-BiPO4] entre les matériaux primitifs Bi3O4Cl et BiPO4. Les mécanismes de photodégradation des polluants organiques, induits par les divers photocatalyseurs, ainsi que l’effet d’environnement acide/base sur les performances photocatalytiques ont été discutés dans ce travail.The main aim of this thesis was to develop materials based on bismuth phosphates and oxychlorides (BiPO4, Bi3O4Cl and Bi24O31Cl10) for photocatalytic applications in aqueous media. From these basic phases, particular attention was paid to the properties of two-phases or composite systems, likely to exhibit heterojunctions. The applications targeted were the photodegradation of organic pollutants, dyes such as rhodamine B, methylene blue, Methyl orange and Congo red on the one hand, and drugs such as amoxicillin and sulfadiazine on the other. The materials developed were subjected to thermal, structural, microstructural, optical, vibrational, electronic and photoluminescent characterizations.In the first stage, BiPO4 bismuth phosphates, obtained by co-precipitation in an acid medium, followed by thermal treatment at 400 to 550°C, were used to photodegrade the various organic pollutants selected: the two-phases system of monoclinic polymorphs nMBIP/mMBIP, obtained at 500°C, showed the best photocatalytic efficiency of the series under UV irradiation. This improved efficiency was attributed to the formation of heterojunctions between polymorph phases. In a second step, the synthesis of Bi3O4Cl and Bi24O31Cl10 oxychlorides and Bi3O4Cl/Bi24O31Cl10 two-phases system was undertaken, and their photocatalytic properties were compared. The Bi3O4Cl/Bi24O31Cl10 system performed best. This enhanced performance was attributed to the formation of Z-scheme heterojunctions between Bi3O4Cl and Bi24O31Cl10. These heterojunctions were visualized by the growth process of 2D Bi3O4Cl nanosheets on the 3D surface of Bi24O31Cl10 micro-grains. In a third step, composite systems [xBi3O4Cl + (1-x)BiPO4] with variable composition with 0 < x < 1 were elaborated by the solid-state reaction, and their photocatalytic efficiencies under visible irradiation were analyzed. The composite with composition x = 0.7 (0.7Bi3O4Cl/0.3BiPO4) revealed the highest photocatalytic efficiencies of the series. This performance was partly attributed to the formation of [Bi3O4Cl/BiPO4] heterojunction type P-N between the original Bi3O4Cl and BiPO4 materials. The mechanisms of photodegradation of organic pollutants, induced by the various photocatalysts, as well as the effect of acid/base environment on photocatalytic performance were discussed in this work
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
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