Construction and Testing of an Innovative Concrete Bridge Deck Totally Reinforced with Glass FRP Bars: Val-Alain Bridge on Highway 20 East

The Val-Alain Bridge, located in the Municipality of Val-Alain on Highway 20 East, crosses over Henri River in Québec, Canada. The bridge is a slab-on-girder type with a skew angle of 20° over a single span of 49.89?m and a total width of 12.57?m. The bridge has four simply supported steel girders spaced at 3,145?mm. The deck slab is a 225-mm-thick concrete slab, with semi-integral abutments, continuous over the steel girders with an overhang of 1,570?mm on each side. The concrete deck slab and the bridge barriers were reinforced with glass fiber reinforced polymer (GFRP) reinforcing bars utilizing high-performance concrete. The Val-Alain Bridge is the Canada’s first concrete bridge deck totally reinforced with GFRP reinforcing bars. Using such nonmetallic reinforcement in combination with high-performance concrete leads to an expected service life of more than 75?years. The bridge is well instrumented with electrical resistance strain gauges and fiber-optic sensors at critical locations to record internal strain data. Also, the bridge was tested for service performance using calibrated truckloads. Design concepts, construction details, and results of the first series of live load field tests are presented.     

In vitro inhibition of Escherichia coli O157:H7 by bifidobacterial strains of human origin

The ability of bifidobacteria isolated from infant feces to inhibit enterohemorrhagic Escherichia coli serotype O157:H7 in vitro and reduce its adhesion to human enterocyte-like Caco-2 cells was evaluated in comparison to American Type Culture Collection bifidobacterial reference strains. Five Bifidobacterium isolates from infant feces were identified and characterized by morphology, fructose-6-phosphate phosphoketolase (F6PPK) assay, polymerase chain reaction using bifidobacterial 16S rDNA specific primers, carbohydrate fermentation patterns, resistance to lysozyme, acid, bile and hydrogen peroxide as well as their ability to inhibit E. coli O157:H7 using the agar spot technique. Infant isolates showed greater resistance to bile, acid, lysozyme and more antimicrobial activity against E. coli O157:H7 than ATCC strains. Two infant isolates identified as B. bifidum RBL 71 and B. bifidum RBL 460 showed good adhesion and significant potential for reducing adhesion of E. coli O157:H7 to Caco-2 cells. This effect was dependent on bifidobacterial cell concentration. These results show that bifidobacteria isolated from infants may be useful for improving probiotic formulae with respect to protection against E. coli O157:H7 infection.     

Testing of a new solar coating for solar water heating applications

A novel and affordable solar selective coating exhibiting higher solar absorption efficiency compared to the commercial black paint coating used in most ordinary solar water heating systems (SWHSs) has been developed. The coating is fabricated by embedding a metallic particle composed of a nickel-aluminium (NiAl) alloy into the black paint. The optical behaviour of several percentages of the NiAl alloy in the coating is studied using UV-Vis and IR spectroscopies. The chemical composition of the coating was characterized using XRD and thermo-gravimetric analysis (TGA) for both the black and alloy-containing paint. The results allowed deducing that the optimum composition to consider for further testing was 6% NiAl alloy by mass. The applicability of the coating in a real thermosyphonic SWHS was evaluated throughout the year, spanning both hot and cold seasons. It is found that the new coating shows better performance compared to the untreated black paint by an average of 5 °C over a period of 1 year. The corrosion resistance of the coating was investigated using electrochemical polarization and weight-loss measurements in the corrosive medium of 3% NaCl in 0.50 M HCl. Higher inhibition efficiency of corrosion was found for the alloy-containing paint compared to the untreated paint by more than 12%. Finally, Scanning Electron Microscopy (SEM) was used to explore the morphology of the modified coating surface, and compared to the untreated surface.     

Phenological,Nutritional and Molecular Diversity Assessment among 35 Introduced Lentil (Lens culinaris Medik.) Genotypes Grown in Saudi Arabia

Morphological, nutritional and molecular analyses were carried out to assess genetic diversity among 35 introduced lentil genotypes (Lens culinaris Medik.). The genotypes exhibited significant differences for their field parameters and some of them showed noticeable superiority. The nutritional and proximate analysis showed that some genotypes were excellent sources of proteins, essential amino acids, minerals, anti-oxidants, total phenolic contents (TPC) and total flavonoid contents (TFC) and hence, highlights lentil nutritional and medicinal potential. Sequence-related amplified polymorphism (SRAP) and amplified fragments length polymorphism (AFLP) markers were used to estimate the genetic variability at the molecular level. The existence of a considerable amount of genetic diversity among the tested lentil genotypes was also proven at the molecular level. A total of 2894 polymorphic SRAP and 1625 AFLP loci were successfully amplified using six SRAP and four AFLP primer pair combinations. Polymorphism information content (PIC) values for SRAP and AFLP markers were higher than 0.8, indicating the power and higher resolution of those marker systems in detecting molecular diversity. UPGMA (unweighted pair group method with arithmetic average) cluster analysis based on molecular data revealed large number of sub clusters among genotypes, indicating high diversity levels. The data presented here showed that FLIP2009-64L and FLIP2009-69L could be used as a significant source of yield, total protein, essential amino acids, and antioxidant properties. The results suggest potential lentil cultivation in the central region of Saudi Arabia for its nutritional and medicinal properties, as well as sustainable soil fertility crop.     

Simultaneous reconstruction of the time-dependent Robin coefficient and heat flux in heat conduction problems

This paper aims to solve an inverse heat conduction problem in two-dimensional space under transient regime, which consists of the estimation of multiple time-dependent heat sources placed at the boundaries. Robin boundary condition (third type boundary condition) is considered at the working domain boundary. The simultaneous identification problem is formulated as a constrained minimization problem using the output least squares method with Tikhonov regularization. The properties of the continuous and discrete optimization problem are studied. Differentiability results and the adjoint problems are established. The numerical estimation is investigated using a modified conjugate gradient method. Furthermore, to verify the performance of the proposed algorithm, obtained results are compared with results obtained from the well-known finite-element software COMSOL Multiphysics under the same conditions. The numerical results show that the proposed algorithm is accurate, robust and capable of simultaneously representing the time effects on reconstructing the time-dependent Robin coefficient and heat flux.     

Durability of GFRP Bars’ Bond to Concrete under Different Loading and Environmental Conditions

In the last decade, noncorrodible fiber-reinforced polymer (FRP) reinforcing bars have been increasingly used as the main reinforcement for concrete structures in harsh environments. Also, owing to their lower cost compared with other types of FRP bars, glass-FRP (GFRP) bars are more attractive to the construction industry, especially for implementation in bridge deck slabs. In North America, bridge deck slabs are exposed to severe environmental conditions, such as freeze-thaw action, in addition to traffic fatigue loads. Although the bond strength of GFRP bars has been proved to be satisfactory, their durability performance under the dual effects of fatigue-type loading and freeze-thaw action is still not well understood. Few experimental test data are available on the bond characteristics of FRP bars in concrete elements under different loading and environmental conditions. This research investigates the individual and combined effects of freeze-thaw cycles along with sustained axial load and fatigue loading on the bond characteristics of GFRP bars embedded in concrete. An FRP-reinforced concrete specimen was developed to apply axial-tension fatigue or sustained loads to GFRP bars within a concrete environment. A total of thirty-six test specimens was constructed and tested. The test parameters included bar diameter, concrete cover thickness, loading scheme, and environmental conditioning. After conditioning, each specimen was sectioned into two halves for pullout testing. Test results showed that fatigue load cycles resulted in approximately 50% loss in the bond strength of sand-coated GFRP bars to concrete, while freeze-thaw cycles enhanced their bond to concrete by approximately 40%. Larger concrete covers were found more important in cases of larger bar sizes simultaneously subjected to fatigue load and freeze-thaw cycles.