59 research outputs found
Effect of heat treatment on bioelectronic coordinates and antibacterial activities of natural and synthetic clays
Our work consists in studying the effect of the thermal treatment at 900°C of three clays âtwo anionic clays of synthesis ' Double lamellar hydroxide' Zn3Al-CO3 and Mg3Al-CO3, and another natural cationic: Ghassoul (Gh)â, on their antibacterial and bioelectronic power. Their chemical characteristics such as pH at zero charge point (pHzcp), redox potential (Eh), index of oxidizing/reducing power (rH2), and electrochemical potential to dissipate energy (W), as well as the type of oxide formed as a result of this treatment; were also determined. The materials were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), and scanning electron microscopy (SEM). Antibacterial activity was tested for four bacteria: two Gram positive (Staphylococcus aureus, Enterococcus faecalis) and two Gram negative (Escherichia coli, Salmonella spp). The antibacterial power of the three clays was evaluated by their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), using the microtiter plate technique. The results showed that the pHzcp, rH2, W and antibacterial power of the two lamellar double hydroxides increased as a result of heat treatment. While the test on the heat treated cationic clay showed an opposite result. It thus appears that the changes in the physicochemical and electrochemical characteristics of the clays following their calcination at 900°C; are at the origin of the change in their antibacterial powe
Solvent-free aldol condensation of furfural and acetone on calcined Mg-Al hydrotalcites
Une sĂ©rie de matĂ©riaux de type hydrotalcite Mg X Al-CO 3 , oĂč X correspond au rapport molaire nominal Mg / Al (X: 2, 2,5, 3 et 3,5), ont Ă©tĂ© prĂ©parĂ©s et caractĂ©risĂ©s par fluorescence X (XRF ), X - diffraction des rayons (XRD), spectroscopie infrarouge (FT-IR) et analyse thermique (TG-DTA). L'oxyde mixte (Mg X Al-O) avec un rapport Mg / Al de 3,5 dĂ©rivĂ© de l'hydrotalcite calcinĂ©e Ă 450 ° C s'est avĂ©rĂ© ĂȘtre le catalyseur optimal qui peut donner la basicitĂ© la plus Ă©levĂ©e et la plus grande activitĂ© catalytique pour la condensation aldolique sans solvant du furfural et de l'acĂ©tone.L'activitĂ© des hydrotalcites de Mg-Al calcinĂ© pour cette rĂ©action Ă©tait corrĂ©lĂ©e Ă leur basicitĂ© telle que dĂ©terminĂ©e par l'adsorption de phĂ©nol. La meilleure conversion du furfural et la sĂ©lectivitĂ© du furfural-acĂ©tone (FA) ont Ă©tĂ© obtenues Ă 90 ° C aprĂšs 2 heures sur le Mg 3,5 Al-O avec 98% de conversion et une sĂ©lectivitĂ© de 78% en (FA). L'activation pour la condensation d'aldol entre le furfural et l'acĂ©tone s'est avĂ©rĂ©e ĂȘtre de 24,8 KJ / mol en catalyze hĂ©tĂ©rogĂšne avec des hydrotalcites de Mg-Al calcinĂ© par rapport Ă la valeur augmentĂ©e en catalyze homogĂšne avec NaOH qui Ă©tait de 55,8 KJ / mol
From Functional Analysis to CAD Modelling Based on Knowledge Transformation Driven by the Design Process
Part 5: Modelling for PLMInternational audienceMost of industries currently spend too much time to find information on past product design process. This considerably reduces the time it can devote to innovation. The authors assume that the design process meta-model seems very interesting for modelling the design rational and then for accelerating information retrieval. Indeed, the model of the design process partly supports every resources involved in decision making activities (i.e. who, what, when, why, where, how). The authors therefore propose the use of a MBE architecture for driving the product modelling based on the design process model. The UML activity diagrams and the IDEFĂ meta-model are linked for supporting automatic generation ofproduct models using specific transformation knowledge. The CAD model is partly generated from the product functional analysis
Operational framework based on modeling languages to support product repository implementation.
Part 3: Tools and MethodologiesInternational audienceEmbracing Product Lifecycle Management approach involves integrating a product repository in the company information system. From customer's needs to disposal stage, several product representations exist. The product repository purpose is to secure consistency of one product representation with the others. This paper presents an operational modeling framework that supports product repository implementation. In order to ensure consistency, this framework identifies correspondences between entities of languages (âtradeâ languages and standard languages). The presented concepts are illustrated with correspondences between language entities of product designed and productplanned to be built Bills of Materials
Efficacy of once daily darunavir/ritonavir 800/100 mg in PI/r-experienced HIV-1 infected patients with suppressed HIV-1 replication: the RADAR study
International audiencen.
From Functional Analysis to CAD Modelling Based on Knowledge Transformation Driven by the Design Process
Most of industries currently spend too much time to find information on past product design process. This considerably reduces the time it can devote to innovation. The authors assume that the design process meta-model seems very interesting for modelling the design rational and then for accelerating information retrieval. Indeed, the model of the design process partly supports every resources involved in decision making activities (i.e. who, what, when, why, where, how). The authors therefore propose the use of a MBE architecture for driving the product modelling based on the design process model. The UML activity diagrams and the IDEFĂ meta-model are linked for supporting automatic generation of product models using specific transformation knowledge. The CAD model is partly generated from the product functional analysis
Mechanisms explaining transitions between tonic and phasic firing in neuronal populations as predicted by a low dimensional firing rate model
Several firing patterns experimentally observed in neural populations have
been successfully correlated to animal behavior. Population bursting, hereby
regarded as a period of high firing rate followed by a period of quiescence, is
typically observed in groups of neurons during behavior. Biophysical
membrane-potential models of single cell bursting involve at least three
equations. Extending such models to study the collective behavior of neural
populations involves thousands of equations and can be very expensive
computationally. For this reason, low dimensional population models that
capture biophysical aspects of networks are needed.
\noindent The present paper uses a firing-rate model to study mechanisms that
trigger and stop transitions between tonic and phasic population firing. These
mechanisms are captured through a two-dimensional system, which can potentially
be extended to include interactions between different areas of the nervous
system with a small number of equations. The typical behavior of midbrain
dopaminergic neurons in the rodent is used as an example to illustrate and
interpret our results.
\noindent The model presented here can be used as a building block to study
interactions between networks of neurons. This theoretical approach may help
contextualize and understand the factors involved in regulating burst firing in
populations and how it may modulate distinct aspects of behavior.Comment: 25 pages (including references and appendices); 12 figures uploaded
as separate file
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