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.     

Fire tests on bonded post-tensioned concrete slabs

The results from eight fire tests conducted on bonded post-tensioned one-way spanning concrete slabs are presented in this paper. The fire tests were augmented with two additional tests at ambient temperature, carried out to failure on slabs with identical geometry and prestressing tendons. The different structural response between using plastic and metallic ducts, Limestone and Thames Gravel aggregates, and different axial restraint conditions to longitudinal thermal expansion, have been highlighted. Slabs with Thames Gravel aggregates were shown to have a much higher deflection compared to slabs with Limestone aggregates, with restrained slabs having a lower vertical deflection compared to equivalent unrestrained slabs. In all the fire tests, cracks directly inline and parallel to the tendons occurred due to thermal stresses at relatively low tendon temperatures, which were not observed in the ambient tests. It is shown that the use of plastic ducts resulted in slightly higher tendon temperatures due to the ease at which water migrated from the grout once the duct had melted. The fire tests have shown that the fire resistance specified in current codes of practice are generally conservative for bonded post-tensioned one-way spanning concrete slabs. The tests have provided detailed experimental data in the form of temperature distributions within the slab, vertical and horizontal displacements and strains in the tendons, which will allow validation of future computer models to predict the behaviour of bonded post-tensioned concrete slabs under fire conditions.     

Selective radiation coatings. Preparation and high temperature stability

Selective radiation coatings suitable for operation at high temperatures with focused sunlight are described. Coatings of CuO and Co₃O₄ on polished nickel, silver, and platinum have high absorptivity for solar radiation and low emissivity in the infrared when heated. They are stable at at high temperatures.     

Designing and Testing of Concrete Bridge Decks Reinforced with Glass FRP Bars

In addition to their high strength and light weight, fiber-reinforced polymer (FRP) composite reinforcing bars offer corrosion resistance, making them a promising alternative to traditional steel reinforcing bars in concrete bridge decks. FRP reinforcement has been used in several bridge decks recently constructed in North America. The Morristown Bridge, which is located in Vermont, United States, is a single span steel girder bridge with integral abutments spanning 43.90 m. The deck is a 230 mm thick concrete continuous slab over girders spaced at 2.36 m. The entire concrete deck slab was reinforced with glass FRP (GFRP) bars in two identical layers at the top and the bottom. The bridge is well instrumented at critical locations for internal temperature and strain data collection with fiber-optic sensors. The bridge was tested for service performance using standard truck loads. The construction procedure and field test results under actual service conditions revealed that GFRP rebar provides very good and promising performance.     

Field Investigation on the First Bridge Deck Slab Reinforced with Glass FRP Bars Constructed in Canada

Recently, there has been a rapid increase in using noncorrosive fiber-reinforced polymers (FRP) reinforcing bars as alternative reinforcement for bridge deck slabs, especially those in harsh environments. A new two-span girder type bridge, Cookshire-Eaton Bridge (located in the municipality of Cookshire, Quebec, Canada), was constructed with a total length of 52.08 m over two equal spans. The deck was a 200-mm-thick concrete slab continuous over four spans of 2.70 m between girders with an overhang of 1.40 m on each side. One full span of the bridge was totally reinforced using glass fiber-reinforced polymer (GFRP) bars, while the other span was reinforced with galvanized steel bars. The bridge deck was well instrumented at critical locations for internal temperature and strain data collection using fiber optic sensors. The bridge was tested for service performance using calibrated truckloads as specified by the Canadian Highway Bridge Design Code. The construction procedure and field test results under actual service conditions revealed that GFRP rebar provides very competitive performance in comparison to steel.     

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.     

Construction and performance characteristics of a metformin electrode based on the metformin phosphotungstate ion-associate

A new metformin (Mf) ion selective PVC membrane electrode based on the ion-associate of Mf with phosphotungstic acid was prepared. The electrode exhibited a mean calibration graph slope of 58 mV Mf concentration decade^?1, at 25°C, within the concentration range 2·0 × 10^?5?1·0 × 10^?2 M MfCl. The change of pH within the range 4·0–11·0 did not affect the electrode performance. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficient of the electrode (0.000352 V°C^?1). The electrode showed a very good selectivity for Mf with respect to a large number of inorganic and organic cations. The standard addition method and potentiometric titration were applied to determine Mf in pure solutions and in metformin-containing tablets.