Étude du comportement à la flexion de dalles unidirectionnelles en béton armé de PRF : application aux dalles structurales du stationnement Laurier-Taché (Gatineau, Québec)

La présente recherche a pour objet l’étude du comportement à la flexion de dalles unidirectionnelles armées de barres en matériaux composites à base de fibres de verre et de carbone. Ce type de renforcement permet d’éviter la corrosion (survenant dans le cas d’armature d’acier) et d’allonger la durée de vie de ces éléments de structure. Aussi, ce projet de recherche s’inscrit dans le cadre des travaux de reconstruction des dalles structurales du Stationnement Laurier-Taché situé à Gatineau (Québec). Le programme expérimental consistait à mettre à l’essai cinq dalles unidirectionnelles renforcées en PRF de verre et de carbone et une sixième armée en acier conventionnel pour des fins de contrôle. Toutes les dalles ont été sollicitées à un chargement de flexion à 4 points et instrumentées pour la lecture des différentes valeurs de la déflexion, la fissuration et les déformations en vue de mieux comprendre leur performance à la flexion. Ces résultats ont été comparés à ceux obtenus par la dalle renforcée en acier et aux prédictions théoriques. Due à la relative faiblesse des modules d’élasticité des PRF par rapport à celui de l’acier, les exigences en matière de déflexion et largeurs de fissures gouvernent en général le design des dalles (États limites de service). Les résultats obtenus nous ont permis de conclure que : 1) Les modèles théoriques prédisent en toute sécurité le comportement à la flexion des dalles renforcées en PRF; 2) Toutes les dalles testées ont bien satisfait les exigences en termes d’états limites de résistance et d’états limites de service conformément aux codes en usage et par conséquent on peut affirmer que les dalles renforcées en PRF se comportent bien à la flexion et que les résultats obtenus pourront être utilisés comme outils afin d’étudier le comportement de ce type de dalles. Aussi, cette étude a mené à la publication d’un article dans la revue canadienne de génie civil (voir Annexe)

Blind separation of complex-valued satellite-AIS data for marine surveillance: a spatial quadratic time-frequency domain approach

In this paper, the problem of the blind separation of complex-valued Satellite-AIS data for marine surveillance is addressed. Due to the specific properties of the sources under consideration: they are cyclo-stationary signals with two close cyclic frequencies, we opt for spatial quadratic time-frequency domain methods. The use of an additional diversity, the time delay, is aimed at making it possible to undo the mixing of signals at the multi-sensor receiver. The suggested method involves three main stages. First, the spatial generalized mean Ambiguity function of the observations across the array is constructed. Second, in the Ambiguity plane, Delay-Doppler regions of high magnitude are determined and Delay-Doppler points of peaky values are selected. Third, the mixing matrix is estimated from these Delay-Doppler regions using our proposed non-unitary joint zero-(block) diagonalization algorithms as to perform separation

Structure and Activity of the Type VI Secretion System

International audienceThe type VI secretion system (T6SS) is a multiprotein machine that uses a spring-like mechanism to inject effectors into target cells. The injection apparatus is composed of a baseplate on which is built a contractile tail tube/sheath complex. The inner tube, topped by the spike complex, is propelled outside of the cell by the contraction of the sheath. The injection system is anchored to the cell envelope and oriented towards the cell exterior by a trans-envelope complex. Effectors delivered by the T6SS are loaded within the inner tube or on the spike complex and can target prokaryotic and/or eukaryotic cells. Here we summarize the structure, assembly, and mechanism of action of the T6SS. We also review the function of effectors and their mode of recruitment and delivery

Acinetobacter type VI secretion system comprises a non-canonical membrane complex

A. baumannii can rapidly acquire new resistance mechanisms and persist on abiotic surface, enabling the colonization of asymptomatic human host. In Acinetobacter the type VI secretion system (T6SS) is involved in twitching, surface motility and is used for interbacterial competition allowing the bacteria to uptake DNA. A. baumannii possesses a T6SS that has been well studied for its regulation and specific activity, but little is known concerning its assembly and architecture. The T6SS nanomachine is built from three architectural sub-complexes. Unlike the baseplate (BP) and the tail-tube complex (TTC), which are inherited from bacteriophages, the membrane complex (MC) originates from bacteria. The MC is the most external part of the T6SS and, as such, is subjected to evolution and adaptation. One unanswered question on the MC is how such a gigantesque molecular edifice is inserted and crosses the bacterial cell envelope. The A. baumannii MC lacks an essential component, the TssJ lipoprotein, which anchors the MC to the outer membrane. In this work, we studied how A. baumannii compensates the absence of a TssJ. We have characterized for the first time the A. baumannii’s specific T6SS MC, its unique characteristic, its membrane localization, and assembly dynamics. We also defined its composition, demonstrating that its biogenesis employs three Acinetobacter-specific envelope-associated proteins that define an intricate network leading to the assembly of a five-proteins membrane super-complex. Our data suggest that A. baumannii has divided the function of TssJ by (1) co-opting a new protein TsmK that stabilizes the MC and by (2) evolving a new domain in TssM for homo-oligomerization, a prerequisite to build the T6SS channel. We believe that the atypical species-specific features we report in this study will have profound implication in our understanding of the assembly and evolutionary diversity of different T6SSs, that warrants future investigation.This work was funded by the Centre National de la Recherche Scientifique, the Aix-Marseille Université, and grants from the Agence Nationale de la Recherche (ANR-18-CE11-0023-01) and European Society of Clinical Microbiology and Infectious Diseases (ESCMID) to ED. ED is supported by the Institut National de la Santé et de la Recherche Médicale (INSERM). YC is funded by a Doctoral school PhD fellowship from the FRM (ECO20160736014 & FDT201904008052). OK is funded by a Doctoral school PhD fellowship from DGA and Aix-Marseille University and by the FRM (01D19024292-A AID & FDT202204014851). PS post-doctoral fellowship was supported by the European Respiratory Society under the ERS Long-Term Fellowship grant agreement LTRF - 202101-00862. IFM is funded by ANR-17-CE11-0039. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer ReviewedPostprint (published version

Pre-organized structure of viral DNA at the binding-processing site of HIV-1 integrase

The integration of the human immunodeficiency virus type 1 DNA into the host cell genome is catalysed by the viral integrase (IN). The reaction consists of a 3′-processing [dinucleotide released from each 3′ end of the viral long terminal repeat (LTR)] followed by a strand transfer (insertion of the viral genome into the human chromosome). A 17 base pair oligonucleotide d(GGAAAATCTCTAGCAGT), d(ACTGCTAGAGATTTTCC) reproducing the U5-LTR extremity of viral DNA that contains the IN attachment site was analysed by NMR using the classical NOEs and scalar coupling constants in conjunction with a small set of residual dipolar coupling constants (RDCs) measured at the (13)C/(15)N natural abundance. The combination of these two types of parameters in calculations significantly improved the DNA structure determination. The well-known features of A-tracts were clearly identified by RDCs in the first part of the molecule. The binding/cleavage site at the viral DNA end is distinguishable by a loss of regular base stacking and a distorted minor groove that can aid its specific recognition by IN

A social business model for the provision of household ecological sanitation services in urban Haiti

Traditional sanitation alternatives like pit latrines or sewerage systems are often unsafe, economically infeasible or inappropriate for low-income populations living in urban areas characterized by lack of infrastructure, high population density, a high groundwater table, and a subsequent lack of waste treatment. Since 2012, SOIL has launched a household ecological sanitation service, called EkoLakay, in several urban areas in Haiti. This program is showing promising results in providing a sustainable, attractive, and affordable sanitation solution for urban households. Customers pay a monthly fee of $4-$5 that covers the installation of the toilet and the weekly waste collection. Waste containers are brought to a SOIL composting waste treatment facility where the wastes are safely treated and transformed into a nutrient-rich compost. As of March 2016, Ekolakay serves 721 households, or 4000 users, in Port-au-Prince and Cap-Haïtien, and demand for the service continues to grow

Snail protein inhibition by drug repositioning for recurrent breast cancer: an in-silico study

Objective: Snail is a transcription factor that promotes epithelial-mesenchymal transition (EMT) and facilitates tumor progression and metastasis in breast cancer. Therefore, it is a promising target for the development of anticancer agents. The objective of this study was to identify FDA-approved drugs that can be repurposed as Snail inhibitors. Materials and Methods: Using a virtual screening strategy, three molecules were selected among 1615 (Stivarga, Paritaprevir and Sorafenib). Molecular docking and molecular dynamics simulation were performed to examine Snail-drugs interactions. Results: Our docking analysis identified Stivarga and Sorafenib, two antineoplastic drugs, as potential repositioning drugs to treat recurrent breast cancer due to their low free binding energy values. Additional molecular dynamics simulations of the Snail-drug systems revealed that Sorafenib was the most stable, lasting from 30 to 120 ns and forming 2-4 hydrogen bonds. Conclusions: The antineoplastic drugs Stivarga and Sorafenib have better affinity and inhibition of Snail and could be a simple drug therapy for recurrent breast cancer

The Synergistic Effect of Chloride Ion and 1,5-Diaminonaphthalene on the Corrosion Inhibition of Mild Steel in 0.5 M Sulfuric Acid: Experimental and Theoretical Insights

International audienceThe inhibition efficiency of 1,5-Diaminonaphthalene (1,5DNA) compound was studied by itself as well as in a mixture that included sodium chloride (NaCl), noted [1.5DNA][Cl−], for mild steel in 0.5 M sulfuric acid. Gravimetric, electrochemical techniques and computational chemistry calculations were utilized for the assessment of corrosion inhibition efficiency and explanation of the mechanism involved during the corrosion inhibition process. The results show that inhibition efficiencies on mild steel increase with increase in concentration of the inhibitor and enhancement in inhibition efficiency was observed on addition of sodium chloride due to synergism. This inhibition has been attributed to the stabilization of adsorbed inhibitor film and, consequently, increasing its inhibitive properties. The [1.5DNA][Cl−] acts as mixed type inhibitor and the Nyquist curves show that with the increase in the concentration, the charge transfer resistance Rct increased. In addition, [1.5DNA][Cl−] obeyed Langmuir monolayer adsorption isotherm. Moreover, Molecular Dynamic Simulations and DFT calculations showed that [1.5DNA][Cl−] owned a higher adsorption ability

(Z)-2-benzylidene-2H-[1, 4] benzothiazin-3-one(T1) as New Synthesized Corrosion Inhibitor for Mild Steel in 0.5 M H2SO4

The corrosion inhibition of mild steel in 0.5 M H2SO4 solution by (Z)-2-benzylidene-2H-[1,4]benzothiazin-3-one: (T1)  has been studied using electrochemical polarization , electrochemical impedance spectroscopy (EIS) and weight loss methods. The corrosion inhibition efficiency measured by all the three techniques was in good agreement with each other. The results showed that T1 is a very good inhibitor for mild steel in acidic media. The inhibition efficiency increases with increasing inhibitor concentration. It acts as a mixed-type inhibitor. EIS plots indicated that the addition of T1 increases the charge-transfer resistance (Rct), decreases the double-layer capacitance (Cdl) of the corrosion process, and hence increases inhibition efficiency. The adsorption of the T1 on the mild steel surface in acid solution obeys the Langmuir adsorption isotherm