Contribution à la formulation d’une pâte autoplaçante à base de matériaux locaux

Ce travail a pour but la formulation d’une pâte autoplaçante de ciment à base de matériaux locaux algériens (ciment binaire à base d’une pouzzolane naturelle algérienne et fillers calcaires de carrière). Plusieurs pâtes ont été confectionnées à partir du ciment, des fillers calcaires (substituant un taux croissant du ciment), du superplastifiant et de l’eau. L'ouvrabilité et la fluidité des pâtes formées sont déduites des essais del’étalement au mini-cône et du temps d’écoulement au cône de Marsh respectivement. A partir de ces essais considérés comme préliminaires, un domaine expérimental est déduit, a l'intérieur duquel les mesures sont possibles. Par utilisation de la méthode des plans de mélanges, le nombre d'expériences sera considérablement réduit, le problème a été mis en équations (sous forme de contraintes implicites) puis résolu numériquement. Des critères d'optimalisation sont vérifiés en plus des interactivités entre constituants pris deux à deux grâce à des essais faisant intervenir les multiples combinaisons en dosages de ces matériaux. En passant par des courbes des diagrammes ternaires, reliant les réponses étalements et temps d’écoulement des pâtes en fonction des dosages en constituants et en étudiant les fonctions de désirabilités sur chaque réponse: une composition de pâte autoplaçante est déduite.Mots-clés : Formulation, propriétés rhéologiques, plans de mélanges,  iagrammes ternaires, pâte de ciment autoplaçante

Influence des paramètres de composition sur le comportement du béton autoplaçant à l’état frais

La présente étude s’inscrit dans le cadre des travaux de recherche menés au département de génie civil de l'université de Mostaganem, en Algérie. Elle concerne l’étude de l’influence des paramètres de composition sur le comportement du béton autoplaçant à l'état frais. Elle a pour objectif de comprendre les rôles joués par les différents constituants susceptibles d’entrer dans la formulation d'un BAP à base de matériaux locaux notamment le sable de mer et le sable de carrière (considéré comme déchet naturel) et de mettre en évidence les éventuelles interactions entre constituants. Les résultats obtenus offrent de belles perspectives pour optimiser les BAP. Nos essais ont permis de développer une variété de formulations de béton autoplaçant répondant aux critères rhéologiques (bonne déformabilité, moins de ressuage, absence de ségrégation).Mots-clés : Béton autoplaçant, superplastifiant, fines calcaires, matériaux locaux, béton frais

On tacit knowledge for philosophy of education

This article offers a detailed reading Gascoigne and Thornton’s book Tacit Knowledge (2013), which aims to account for the tacitness of tacit knowledge (TK) while preserving its status as knowledge proper. I take issue with their characterization and rejection of the existential-phenomenological Background—which they presuppose even as they dismiss—and their claim that TK can be articulated “from within”—which betrays a residual Cartesianism, the result of their elision of conceptuality and propositionality. Knowledgeable acts instantiate capacities which we might know we have and of which we can be aware, but which are not propositionally structured at their “core”. Nevertheless, propositionality is necessary to what Robert Brandom calls, in Making It Explicit (1994) and Articulating Reasons (2000), “explicitation”, which notion also presupposes a tacit dimension, which is, simply, the embodied person (the knower), without which no conception of knowledge can get any purchase. On my view, there is no knowledgeable act that can be understood as such separately from the notion of skilled corporeal performance. The account I offer cannot make sense of so-called “knowledge-based” education, as opposed to systems and styles which supposedly privilege “contentless” skills over and above “knowledge”, because on the phenomenological and inferentialist lines I endorse, neither the concepts “knowledge” nor “skill” has any purchase or meaning without the other

Education, knowledge, and symbolic form

This article aims to introduce Ernst Cassirer, and his philosophy of symbolic form, to education studies, and, in doing so, to challenge the widespread but deeply flawed views of knowledge and so-called knowledge-based education that have shaped recent education policy in England. After sketching the current educational landscape, and then some of the main lines of flight in Cassirer’s work, time is given to a comparison with Heidegger—a more familiar figure by far in Anglophone philosophy than Cassirer, and who contributed to the displacement of Cassirer—in order to illustrate more clearly Cassirer’s original contribution, in particular to the relationship between knowledge and time. Cassirer’s view of knowledge stands in marked and critical contrast to that which has shaped recent educational reform in England, as he sees knowledge as a productive and expressive matter, and repudiates what I call the ‘building-blocks’ picture of knowledge and the hierarchisation of subject areas

Environmental Adaptation: Genomic Analysis of the Piezotolerant and Psychrotolerant Deep-Sea Iron Reducing Bacterium Shewanella piezotolerans WP3

Shewanella species are widespread in various environments. Here, the genome sequence of Shewanella piezotolerans WP3, a piezotolerant and psychrotolerant iron reducing bacterium from deep-sea sediment was determined with related functional analysis to study its environmental adaptation mechanisms. The genome of WP3 consists of 5,396,476 base pairs (bp) with 4,944 open reading frames (ORFs). It possesses numerous genes or gene clusters which help it to cope with extreme living conditions such as genes for two sets of flagellum systems, structural RNA modification, eicosapentaenoic acid (EPA) biosynthesis and osmolyte transport and synthesis. And WP3 contains 55 open reading frames encoding putative c-type cytochromes which are substantial to its wide environmental adaptation ability. The mtr-omc gene cluster involved in the insoluble metal reduction in the Shewanella genus was identified and compared. The two sets of flagellum systems were found to be differentially regulated under low temperature and high pressure; the lateral flagellum system was found essential for its motility and living at low temperature

High Resolution In Vivo Bioluminescent Imaging for the Study of Bacterial Tumour Targeting

The ability to track microbes in real time in vivo is of enormous value for preclinical investigations in infectious disease or gene therapy research. Bacteria present an attractive class of vector for cancer therapy, possessing a natural ability to grow preferentially within tumours following systemic administration. Bioluminescent Imaging (BLI) represents a powerful tool for use with bacteria engineered to express reporter genes such as lux. BLI is traditionally used as a 2D modality resulting in images that are limited in their ability to anatomically locate cell populations. Use of 3D diffuse optical tomography can localize the signals but still need to be combined with an anatomical imaging modality like micro-Computed Tomography (μCT) for interpretation