1,720,990 research outputs found
Filtration des nanoparticules : application aux appareils de protection respiratoire
No full textThis study aims to determine how the respiratory protective devices (RPD), whose performances are qualified for particles above 100 nm, are effective for nanoparticles. Indeed, if the use of a collective filtration is inadequate, wearing a RPD is the last protection recommended. A literature review showed that no research concerned the effectiveness of half-masks for nanoparticles. The test bench ETNA has been sized and built to overcome these lacks. Two half masks were tested according to different configurations: constant flow rate and cyclic flow rate (average flow of 84 L /min) ; particle size (from 5 to 100 nm) ; positions of the mask (sealed, usual, or with calibrated leaks). The results show that, since the RPD contain high efficiency filter media (without charged fibers) for the most penetrating particle size (100 nm - 300 nm), the RPD is more efficient for nanoparticles. Furthermore, the results obtained in the presence of actual and calibrated leaks, highlighted the importance of faceseal leakages in determining the performance of RPD. A model for calculating the protection factor was established based on the balance between the airflow through the filter and the leak. This model was validated using measurements obtained in the presence of calibrated leaks, and applied for the analysis of our results in usual positionCette étude a pour objectif de déterminer dans quelle mesure les APR, dont les performances sont qualifiées pour des particules supérieures à 100 nm, sont efficaces pour des nanoparticules. En effet, dans le cas où l'utilisation d'une filtration collective est insuffisante, le port d'un Appareil de Protection Respiratoire (APR) est le dernier rempart préconisé. Une synthèse bibliographique a montré qu'aucune recherche n'a porté sur l'efficacité de demi-masques avec filtres pour des nanoparticules. Le banc d'ETude des NAnoparticules a été dimensionné et réalisé afin de pallier ces manques. Deux demi-masques ont été testés selon différentes configurations d'essais : débit constant et débit cyclique (débit moyen de 84 L/min) ; taille des particules (de 5 à 100 nm) ; pose du masque (scellée, libre, ou avec des fuites calibrées). Les résultats montrent que, dès lors que les APR utilisés contiennent des media (non électrets) efficaces pour des particules de la zone MPPS (100 nm - 300 nm), les APR sont plus efficaces pour les particules nanométriques. De plus, les résultats obtenus, en présence de fuites réelles et calibrées, ont mis en évidence l'importance des fuites au visage dans la détermination des performances des APR. Un modèle de calcul du facteur de protection a été établi, basé sur la différenciation des débits d'air traversant la fuite et le filtre. Cette modélisation a été validée à l'aide des mesures obtenues en présence des fuites calibrées, et appliquée pour l'analyse de nos résultats en pose libr
Filtration of nanoparticles : Application to Respiratory Protecting Devices
No full textCette étude a pour objectif de déterminer dans quelle mesure les APR, dont les performances sont qualifiées pour des particules supérieures à 100 nm, sont efficaces pour des nanoparticules. En effet, dans le cas où l'utilisation d'une filtration collective est insuffisante, le port d'un Appareil de Protection Respiratoire (APR) est le dernier rempart préconisé. Une synthèse bibliographique a montré qu'aucune recherche n'a porté sur l'efficacité de demi-masques avec filtres pour des nanoparticules. Le banc d'ETude des NAnoparticules a été dimensionné et réalisé afin de pallier ces manques. Deux demi-masques ont été testés selon différentes configurations d'essais : débit constant et débit cyclique (débit moyen de 84 L/min) ; taille des particules (de 5 à 100 nm) ; pose du masque (scellée, libre, ou avec des fuites calibrées). Les résultats montrent que, dès lors que les APR utilisés contiennent des media (non électrets) efficaces pour des particules de la zone MPPS (100 nm - 300 nm), les APR sont plus efficaces pour les particules nanométriques. De plus, les résultats obtenus, en présence de fuites réelles et calibrées, ont mis en évidence l'importance des fuites au visage dans la détermination des performances des APR. Un modèle de calcul du facteur de protection a été établi, basé sur la différenciation des débits d'air traversant la fuite et le filtre. Cette modélisation a été validée à l'aide des mesures obtenues en présence des fuites calibrées, et appliquée pour l'analyse de nos résultats en pose libreThis study aims to determine how the respiratory protective devices (RPD), whose performances are qualified for particles above 100 nm, are effective for nanoparticles. Indeed, if the use of a collective filtration is inadequate, wearing a RPD is the last protection recommended. A literature review showed that no research concerned the effectiveness of half-masks for nanoparticles. The test bench ETNA has been sized and built to overcome these lacks. Two half masks were tested according to different configurations: constant flow rate and cyclic flow rate (average flow of 84 L /min) ; particle size (from 5 to 100 nm) ; positions of the mask (sealed, usual, or with calibrated leaks). The results show that, since the RPD contain high efficiency filter media (without charged fibers) for the most penetrating particle size (100 nm - 300 nm), the RPD is more efficient for nanoparticles. Furthermore, the results obtained in the presence of actual and calibrated leaks, highlighted the importance of faceseal leakages in determining the performance of RPD. A model for calculating the protection factor was established based on the balance between the airflow through the filter and the leak. This model was validated using measurements obtained in the presence of calibrated leaks, and applied for the analysis of our results in usual positio
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
Performance of different classes of filtering facepiece respirators toward nanoparticles
No full textIntroduction: In the case of exposure to harmful substances and the use of a filtering facepiece respirator (FFR) to protect workers, it is important to know the performance of commercial FFR. In previous studies, the authors investigated a series of parameters on the effectiveness of a standard N95 FFR: particle diameter, airflow rate intensity, breathing simulation, time of use, relative humidity. It remains uncertain whether previous results can be extrapolated to all commercial FFRs.
Objective: To determine whether previous conclusions apply to other FFRs, an expanded selection of models was evaluated in this study. The initial penetrations are then measured in order to compare the penetrations amongst the different FFRs.
Methods: To do so, an experimental setup generates NaCl nanoparticles before introducing them into a test chamber containing the FFR. A constant flow of 85 L/min is drawn through the FFR and particle concentration is measured upstream and downstream of the FFR with a Scanning Mobility Particle Sizer. This setup allows penetration to be measured as a function of the particle diameter from 10 to 200 nm. Pressure drop was also measured across the FFR.
Results: The benchmark established in this study confirms that penetration measurements align with previously reported values. All tested FFRs exhibit comparable trends: the most penetrating particle size (MPPS) remains between 30 and 50 nanometers, with penetration decreasing for particles smaller or larger than this range.
Conclusion: The results obtained thus indicate that the outcome achieved previously for the standard N95 FFRs can be extrapolated to the other FFRs presented here
Filtration des nanoparticules (application aux appareils de protection respiratoire)
No full textCette étude a pour objectif de déterminer dans quelle mesure les APR, dont les performances sont qualifiées pour des particules supérieures à 100 nm, sont efficaces pour des nanoparticules. En effet, dans le cas où l'utilisation d'une filtration collective est insuffisante, le port d'un Appareil de Protection Respiratoire (APR) est le dernier rempart préconisé. Une synthèse bibliographique a montré qu'aucune recherche n'a porté sur l'efficacité de demi-masques avec filtres pour des nanoparticules. Le banc d'ETude des NAnoparticules a été dimensionné et réalisé afin de pallier ces manques. Deux demi-masques ont été testés selon différentes configurations d'essais : débit constant et débit cyclique (débit moyen de 84 L/min) ; taille des particules (de 5 à 100 nm) ; pose du masque (scellée, libre, ou avec des fuites calibrées). Les résultats montrent que, dès lors que les APR utilisés contiennent des media (non électrets) efficaces pour des particules de la zone MPPS (100 nm - 300 nm), les APR sont plus efficaces pour les particules nanométriques. De plus, les résultats obtenus, en présence de fuites réelles et calibrées, ont mis en évidence l'importance des fuites au visage dans la détermination des performances des APR. Un modèle de calcul du facteur de protection a été établi, basé sur la différenciation des débits d'air traversant la fuite et le filtre. Cette modélisation a été validée à l'aide des mesures obtenues en présence des fuites calibrées, et appliquée pour l'analyse de nos résultats en pose libreThis study aims to determine how the respiratory protective devices (RPD), whose performances are qualified for particles above 100 nm, are effective for nanoparticles. Indeed, if the use of a collective filtration is inadequate, wearing a RPD is the last protection recommended. A literature review showed that no research concerned the effectiveness of half-masks for nanoparticles. The test bench ETNA has been sized and built to overcome these lacks. Two half masks were tested according to different configurations: constant flow rate and cyclic flow rate (average flow of 84 L /min) ; particle size (from 5 to 100 nm) ; positions of the mask (sealed, usual, or with calibrated leaks). The results show that, since the RPD contain high efficiency filter media (without charged fibers) for the most penetrating particle size (100 nm - 300 nm), the RPD is more efficient for nanoparticles. Furthermore, the results obtained in the presence of actual and calibrated leaks, highlighted the importance of faceseal leakages in determining the performance of RPD. A model for calculating the protection factor was established based on the balance between the airflow through the filter and the leak. This model was validated using measurements obtained in the presence of calibrated leaks, and applied for the analysis of our results in usual positionMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF
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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