Evaluation of physical and durability characteristics of new headed glass fiber–reinforced polymer bars for concrete structures

This paper presents the results of a collaborative research project with Quebec’s Ministry of Transportation and the Ontario’s Ministry of Transportation, which aimed at characterizing a new type of headed glass-fiber-reinforced-polymer (GFRP) reinforcing bar and evaluating its suitability as internal reinforcement for concrete structures. To achieve these objectives, the project was implemented in three stages: (1) evaluation of the physical and mechanical properties; (2) determination of the pullout behavior in concrete; and (3) characterization of the long-term durability of the headed GFRP bars. A total of 57 specimens embedded in a 200 mm concrete cube were tested with the direct pullout test to investigate the effect of confinement, bar size, concrete compressive strength, and exposure conditions on the pullout behavior of the headed GFRP bars. Simultaneously, microstructural analyses and measurements of the physicochemical and mechanical properties were carried out on conditioned and unconditioned headed GFRP bars. The results show that the materials, geometry, and interface configuration of the head provided very good mechanical interlocking to the GFRP bars. Up to 63% and 53% of the guaranteed tensile strength of the straight GFRP bars were achieved for 15.9 mm and 19 mm diameter bars with headed ends, respectively. Scanning electron microscopy and differential scanning calorimetry showed no material changes in the head and bars after exposure to alkaline solution and freeze–thaw cycling. Exposure to the alkaline solution under sustained loading had the most detrimental effect, with the bar retaining 79.4% of its pullout strength. The results indicate that the tested headed GFRP bar has suitable mechanical and durability properties for use as reinforcement in concrete bridge components

Polycaprolactone (PCL) chains grafting on the surface of cellulose nanocrystals (CNCs) during in situ polymerization of ε-caprolactone at room temperature

This work aimed at investigating the feasibility of surface modification of cellulose nanocrystals (CNCs) using in situ ring opening polymerization of ε-caprolactone (ε-CL) at room temperature. Residues of flax and milkweed (Asclepias syriaca) stem fibers were used as a source of cellulose to obtain and isolate CNCs. The cationic ring opening polymerization (CROP) of the monomer ε-CL was used to covalently graft polycaprolactone (PCL) chains at the CNCs surface. Silver hexafluoroantimonate (AgSbF6) was used in combination with the extracted CNCs to initiate, at room temperature, the polymerization and the grafting reactions with no other stimulus. Fourier-Transform InfraRed (FTIR), X-ray Photoelectron Spectrometry (XPS), UV/visible absorption and Gel Permeation Chromatography (GPC) analyses evidenced the presence of PCL chains covalently grafted at CNCs surface, the formation of Ag(0) particles as well as low or moderate molecular weight free PCL chains

Insight into the prebiotic concept: lessons from an exploratory, double blind intervention study with inulin-type fructans in obese women

Objective To highlight the contribution of the gut microbiota to the modulation of host metabolism by dietary inulin-type fructans (ITF prebiotics) in obese women. Methods A double blind, placebo controlled, intervention study was performed with 30 obese women treated with ITF prebiotics (inulin/oligofructose 50/50 mix; n=15) or placebo (maltodextrin; n=15) for 3 months (16 g/day). Blood, faeces and urine sampling, oral glucose tolerance test, homeostasis model assessment and impedancemetry were performed before and after treatment. The gut microbial composition in faeces was analysed by phylogenetic microarray and qPCR analysis of 16S rDNA. Plasma and urine metabolic profiles were analysed by 1H-NMR spectroscopy. Results Treatment with ITF prebiotics, but not the placebo, led to an increase in Bifidobacterium and Faecalibacterium prausnitzii; both bacteria negatively correlated with serum lipopolysaccharide levels. ITF prebiotics also decreased Bacteroides intestinalis, Bacteroides vulgatus and Propionibacterium, an effect associated with a slight decrease in fat mass and with plasma lactate and phosphatidylcholine levels. No clear treatment clustering could be detected for gut microbial analysis or plasma and urine metabolomic profile analyses. However, ITF prebiotics led to subtle changes in the gut microbiota that may importantly impact on several key metabolites implicated in obesity and/or diabetes. Conclusions ITF prebiotics selectively changed the gut microbiota composition in obese women, leading to modest changes in host metabolism, as suggested by the correlation between some bacterial species and metabolic endotoxaemia or metabolomic signatures

Irrigation enterrée de l'asperge en Languedoc Roussillon en présence d'une nappe peu profonde, premiere approche

[Notes_IRSTEA]bibl., ann., tabl., phot. [Diplôme_IRSTEA]Rapport de stage, ENITA Dijon, 1989Irrigation souterraine : un systeme de micro-irrigation dt les caractéristiques st adoptées à la conduite de la culture de l'asperge. Un programme d'étude du comportement ds le sol des divers matériels d'irrigation enterrée et réponse de l'asperge a été mis au pt par le Centre Expérimental de Marsillargues (34). Les résultats obtenus lors de l'expérimentation démontrent l'intérêt d'irriguer culture d'asperge malgré présence d'1 nappe phréatique peu profonde, l'effet de la qualité du matériel utilis

Irrigation enterrée de l'asperge en Languedoc Roussillon en présence d'une nappe peu profonde : premiere approche

[Notes_IRSTEA]bibl., ann., graph., tabl. [Diplôme_IRSTEA]Rapport de stage, ENITRTS Dijon, 1989Présentation de l'irrigation souterraine, les limites. Applications. La culture de l'asperge. Expérimentation, résultats agronomique

ETUDE DES FORMES CIRCULANTES DE LA SEX HORMONE-BINDING GLOBULIN (SHBG) HUMAINE, PROTEINE DE LIAISON DES HORMONES STEROIDES SEXUELLES ; MESURE DES CLAIRANCES METABOLIQUES

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Effect of modified graphene oxide on the mechanical, thermal, and barrier properties of vinylester

Graphene, which is a one atom thick layer of graphite, has been considerably studied in the past decade due to its extraordinary physical properties. The development of new routes of synthesis facilitates the use of graphene in polymer nanocomposite. The addition of very small amounts (<1%) of graphene in a polymer matrix does not only increase its thermal and mechanical properties, but it would also enhance permeability, by limiting the diffusion of water through the material. Graphene-polymer nanocomposite would be an interesting alternative to conventional polymer nanocomposite such as nanoclay-polymer nanocomposite. In this study, graphene oxide is synthesized from graphite flakes, following the Tour method, and modified with silane to improve its compatibility with the polymer. Polymer nanocomposite made from vinylester resin and 0.5 wt% graphene oxide is prepared as well as other types of typically used polymer nanocomposite such as graphite flake, silica fume or nanoclay based composite. Samples are soaked in a water bath to study the water absorption of these nanocomposites. Mechanical property measurements and thermal analyses are performed to evaluate the benefit of using graphene oxide. Results show a significant enhancement of the mechanical and thermal properties with a graphene oxide content ten times lower than the one needed with conventional nanoparticles. Moreover, unlike nanoclay-based polymer nanocomposite, graphene oxide does not increase water absorption at saturation

Effect of modified graphene oxide on the mechanical, thermal, and barrier properties of vinylester

\u3cp\u3eGraphene, which is a one atom thick layer of graphite, has been considerably studied in the past decade due to its extraordinary physical properties. The development of new routes of synthesis facilitates the use of graphene in polymer nanocomposite. The addition of very small amounts (&lt;1%) of graphene in a polymer matrix does not only increase its thermal and mechanical properties, but it would also enhance permeability, by limiting the diffusion of water through the material. Graphene-polymer nanocomposite would be an interesting alternative to conventional polymer nanocomposite such as nanoclay-polymer nanocomposite. In this study, graphene oxide is synthesized from graphite flakes, following the Tour method, and modified with silane to improve its compatibility with the polymer. Polymer nanocomposite made from vinylester resin and 0.5 wt% graphene oxide is prepared as well as other types of typically used polymer nanocomposite such as graphite flake, silica fume or nanoclay based composite. Samples are soaked in a water bath to study the water absorption of these nanocomposites. Mechanical property measurements and thermal analyses are performed to evaluate the benefit of using graphene oxide. Results show a significant enhancement of the mechanical and thermal properties with a graphene oxide content ten times lower than the one needed with conventional nanoparticles. Moreover, unlike nanoclay-based polymer nanocomposite, graphene oxide does not increase water absorption at saturation.\u3c/p\u3

Performance Analysis of CGS, a k-Coverage Algorithm based on One-hop Neighboring Knowledge

Controlled Greedy Sleep (CGS) is a recent k-coverage algorithm based on one-hop neighboring knowledge. This paper presents the Controlled Greedy Sleep algorithm and highlights its best use cases thanks to performance analysis. Studies have been performed within a ring topology. This specific topology enables CGS validation and the design of an energetic model. They are used to compare CGS performance results with the maximal performances that could be expected. The ring topology allows us to determine analytically the minimum, maximum and relative values of our performances criteria which are: the quality, the cost and the duration of the k-coverage. According to the previous criteria we show in this paper that CGS is before anything designed to guarantee the maximum quality of coverage. We prove the CGS robustness when there are message losses. We show that CGS relative performances are improved when the overdosing and the communication cost increase. This is mostly because sensors just need to send at most three CGS messages per period and only need to know their one-hop neighbors

Volailles axéniques : des modèles originaux pour l'étude du microbiote

Résumé de la communication présentée lors du 42ème Congrès de l'AFSTAL en octobre 2016 à NantesVolailles axéniques : des modèles originaux pour l'étude du microbiot