1,720,956 research outputs found
Fluorescent silica nanoparticles for multidimensional barcoding in droplets : towards high-throughput screening in two-phase microfluidics
No full textLe criblage à haut débit a connu des avancées significatives en 20 ans. Néanmoins, les technologies microplaque ou microarray ne sont pas toujours optimales. C’est pourquoi de nouvelles plates-formes, basées sur la microfluidique en gouttes, pourraient significativement augmenter le débit et réduire les coûts. Cependant, une fois en dehors de la puce, les gouttes perdent leur information spatiale : il est donc nécessaire de marquer les molécules encapsulées pour les identifier. Nous avons choisi un marquage fluorescent, car cette technique est très utilisée en biologie. Le but de ce travail était de fabriquer un matériau fluorescent compatible avec la microfluidique en gouttes, puis de produire plusieurs banques de gouttes encodées avec ce matériau. Nous avons opté pour des nanoparticules de silice comprenant un fluorophore organique attaché de manière covalente. Notre nouvelle synthèse a produit des particules de 2,5 nm, les plus petites jamais synthétisées. Elles sont plus brillantes que les fluorophores organiques, résistent mieux au photoblanchiment et ont une polarisation modulable. Nous avons ensuite étudié les propriétés de surface des particules, en particulier leur interaction avec le tensioactif. A temps longs, une compétition se produit. De plus, des effets osmotiques ont été mis en évidence, si la concentration en particules varie entre d’une goutte à l’autre. Enfin, nous avons examiné les paramètres majeurs dans l’élaboration du code, les optimisations possibles et des stratégies pour réduire le recouvrement spectral. Nous avons produit des banques de gouttes encodées avec deux et trois couleurs, qui peuvent être utilisées dans de nombreuses applications.High-throughput screening has seen significant advances in the last 20 years. However, microtiter plate or microarray technologies are not optimal for all types of assays. Hence, implementation of droplet-based microfluidic platforms could bring a breakthrough in terms of throughput and reduction of costs. However, once out of the chip, droplets lose positional information to identify drop contents. It is thus necessary to label the encapsulated compounds. Since fluorescence is a common assay readout method, we opted for this strategy. The goal of this PhD was to produce a fluorescent material compatible with the specificities of droplet microfluidics, then to generate several optically encoded droplet libraries with it.
We opted for silica nanoparticles (SNPs) covalently encapsulating organic fluorophores. We developed a novel synthesis route that enabled us to reach sizes down to 2.5 nm, the smallest ever synthesized. The SNPs are brighter than starting fluorophores, better resist photobleaching and have tunable fluorescence polarization. Then, we studied the surface properties of these particles, especially their interaction with the surfactant. At long time scales, competition between particles and surfactant was shown. In addition, dramatic osmotic effects were highlighted in case of unequal particle concentration across droplets. Last, we investigated crucial parameters in fluorescent code design, then generated two-and three-color encoded droplet libraries. We also discussed optimizations and on-the-fly identification. We finally identify many applications would benefit from this encoding system
Nanoparticules de silice fluorescentes pour l'encodage multidimensionnel de gouttes,vers le criblage à haut débit en microfluidique biphasique
No full textLe criblage à haut débit a connu des avancées significatives en 20 ans. Néanmoins, les technologies microplaque ou microarray ne sont pas toujours optimales. C est pourquoi de nouvelles plates-formes, basées sur la microfluidique en gouttes, pourraient significativement augmenter le débit et réduire les coûts. Cependant, une fois en dehors de la puce, les gouttes perdent leur information spatiale : il est donc nécessaire de marquer les molécules encapsulées pour les identifier. Nous avons choisi un marquage fluorescent, car cette technique est très utilisée en biologie. Le but de ce travail était de fabriquer un matériau fluorescent compatible avec la microfluidique en gouttes, puis de produire plusieurs banques de gouttes encodées avec ce matériau. Nous avons opté pour des nanoparticules de silice comprenant un fluorophore organique attaché de manière covalente. Notre nouvelle synthèse a produit des particules de 2,5 nm, les plus petites jamais synthétisées. Elles sont plus brillantes que les fluorophores organiques, résistent mieux au photoblanchiment et ont une polarisation modulable. Nous avons ensuite étudié les propriétés de surface des particules, en particulier leur interaction avec le tensioactif. A temps longs, une compétition se produit. De plus, des effets osmotiques ont été mis en évidence, si la concentration en particules varie entre d'une goutte à l'autre. Enfin, nous avons examiné les paramètres majeurs dans l'élaboration du code, les optimisations possibles et des stratégies pour réduire le recouvrement spectral. Nous avons produit des banques de gouttes encodées avec deux et trois couleurs, qui peuvent être utilisées dans de nombreuses applications.High-throughput screening has seen significant advances in the last 20 years. However, microtiter plate or microarray technologies are not optimal for all types of assays. Hence, implementation of droplet-based microfluidic platforms could bring a breakthrough in terms of throughput and reduction of costs. However, once out of the chip, droplets lose positional information to identify drop contents. It is thus necessary to label the encapsulated compounds. Since fluorescence is a common assay readout method, we opted for this strategy. The goal of this PhD was to produce a fluorescent material compatible with the specificities of droplet microfluidics, then to generate several optically encoded droplet libraries with it. We opted for silica nanoparticles (SNPs) covalently encapsulating organic fluorophores. We developed a novel synthesis route that enabled us to reach sizes down to 2.5 nm, the smallest ever synthesized. The SNPs are brighter than starting fluorophores, better resist photobleaching and have tunable fluorescence polarization. Then, we studied the surface properties of these particles, especially their interaction with the surfactant. At long time scales, competition between particles and surfactant was shown. In addition, dramatic osmotic effects were highlighted in case of unequal particle concentration across droplets. Last, we investigated crucial parameters in fluorescent code design, then generated two-and three-color encoded droplet libraries. We also discussed optimizations and on-the-fly identification. We finally identify many applications would benefit from this encoding system
Nanoparticules de silice fluorescentes pour l'encodage multidimensionnel de gouttes (vers le criblage à haut débit en microfluidique biphasique)
No full textLe criblage à haut débit a connu des avancées significatives en 20 ans. Néanmoins, les technologies microplaque ou microarray ne sont pas toujours optimales. C est pourquoi de nouvelles plates-formes, basées sur la microfluidique en gouttes, pourraient significativement augmenter le débit et réduire les coûts. Cependant, une fois en dehors de la puce, les gouttes perdent leur information spatiale : il est donc nécessaire de marquer les molécules encapsulées pour les identifier. Nous avons choisi un marquage fluorescent, car cette technique est très utilisée en biologie. Le but de ce travail était de fabriquer un matériau fluorescent compatible avec la microfluidique en gouttes, puis de produire plusieurs banques de gouttes encodées avec ce matériau. Nous avons opté pour des nanoparticules de silice comprenant un fluorophore organique attaché de manière covalente. Notre nouvelle synthèse a produit des particules de 2,5 nm, les plus petites jamais synthétisées. Elles sont plus brillantes que les fluorophores organiques, résistent mieux au photoblanchiment et ont une polarisation modulable. Nous avons ensuite étudié les propriétés de surface des particules, en particulier leur interaction avec le tensioactif. A temps longs, une compétition se produit. De plus, des effets osmotiques ont été mis en évidence, si la concentration en particules varie entre d une goutte à l autre. Enfin, nous avons examiné les paramètres majeurs dans l élaboration du code, les optimisations possibles et des stratégies pour réduire le recouvrement spectral. Nous avons produit des banques de gouttes encodées avec deux et trois couleurs, qui peuvent être utilisées dans de nombreuses applications.High-throughput screening has seen significant advances in the last 20 years. However, microtiter plate or microarray technologies are not optimal for all types of assays. Hence, implementation of droplet-based microfluidic platforms could bring a breakthrough in terms of throughput and reduction of costs. However, once out of the chip, droplets lose positional information to identify drop contents. It is thus necessary to label the encapsulated compounds. Since fluorescence is a common assay readout method, we opted for this strategy. The goal of this PhD was to produce a fluorescent material compatible with the specificities of droplet microfluidics, then to generate several optically encoded droplet libraries with it. We opted for silica nanoparticles (SNPs) covalently encapsulating organic fluorophores. We developed a novel synthesis route that enabled us to reach sizes down to 2.5 nm, the smallest ever synthesized. The SNPs are brighter than starting fluorophores, better resist photobleaching and have tunable fluorescence polarization. Then, we studied the surface properties of these particles, especially their interaction with the surfactant. At long time scales, competition between particles and surfactant was shown. In addition, dramatic osmotic effects were highlighted in case of unequal particle concentration across droplets. Last, we investigated crucial parameters in fluorescent code design, then generated two-and three-color encoded droplet libraries. We also discussed optimizations and on-the-fly identification. We finally identify many applications would benefit from this encoding system.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF
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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