ASSESSMENT OF TOTAL PHENOLIC, FLAVONOID CONTENT, ANTIOXIDANT POTENTIAL AND HPLC PROFILE OF THREE MORINGA SPECIES LEAF EXTRACTS

In the current investigation, three selected Moringa species (M. stenopetala, M. peregrina and M. oleifera) grown at Orman Botanical Garden, Giza, Egypt were tested to quantify spectrometrically, the total phenolic compounds according to Folin–Ciocalteu's assay and flavonoids content to assess their corresponding effect on their antioxidative activity. Different leaf extracts (hexane, ethyl acetate and ethanol 70%) of the three studied species were prepared. The obtained results revealed that M. peregrina gave the best extract yield for the leaves extracted by the different solvents. Regarding the total phenolic compounds, data exposed ethanol 70% extract of M. peregrina leaves as the highest value among other species (11.66 g GAE/100 g extract), while it was for hexane extract that showed the highest value among other species in flavonoids content (7.21 g QE/100 g extract). Antioxidant activity of leaf extracts was evaluated by means of 2,2-dyphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) scavenging assays. Data exhibited M. peregrina as the highest species to afford free radical scavenging activity with DPPH and ABTS assays in all concentrations of all extracts especially, 1000 μg/ml of ethanol (70%) with 97.00 and 92.67% inhibition, respectively. Moreover, HPLC with UV detection was employed for the identification and quantification of the phenolic compounds and flavonoid content, present in leaf methanolic extracts of the studied species. HPLC assay identified 25 phenolic compounds and 11 flavonoids in the leaves. It was noticed that M. stenopetala leaves emerged the highest values in most of the phenolic compounds and flavonoids. Eventually, it can be concluded that Moringa leaves showed their certain nutritional value and therefore had the potential as source of natural antioxidants. In addition, their regular consumption in diet could provide health benefits to humans by their protection role against oxidative stress

Flexural Performance of Encased Pultruded GFRP I-Beam with High Strength Concrete under Static Loading

There is an interesting potential for the use of GFRP-pultruded profiles in hybrid GFRP-concrete structural elements, either for new constructions or for the rehabilitation of existing structures. This paper provides experimental and numerical investigations on the flexural performance of reinforced concrete (RC) specimens composite with encased pultruded GFRP I-sections. Five simply supported composite beams were tested in this experimental program to investigate the static flexural behavior of encased GFRP beams with high-strength concrete. Besides, the effect of using shear studs to improve the composite interaction between the GFRP beam and concrete as well as the effect of web stiffeners of GFRP were explored. Encasing the GFRP beam with concrete enhanced the peak load by 58.3%. Using shear connectors, web stiffeners, and both improved the peak loads by 100.6%, 97.3%, and 130.8%, respectively. The GFRP beams improved ductility by 21.6% relative to the reference one without the GFRP beam. Moreover, the shear connectors, web stiffeners, and both improved ductility by 185.5%, 119.8%, and 128.4%, respectively, relative to the encased reference beam. Furthermore, a non-linear Finite Element (FE) model was developed and validated by the experimental results to conduct a parametric study to investigate the effect of the concrete compressive strength and tensile strength of the GFRP beam. The developed FE model provided good agreement with the experimental results regarding deformations and damaged patterns

Impact Behavior of Composite Reinforced Concrete Beams with Pultruded I-GFRP Beam

The present study experimentally and numerically investigated the impact behavior of composite reinforced concrete (RC) beams with the pultruded I-GFRP and I-steel beams. Eight specimens of two groups were cast in different configurations. The first group consisted of four specimens and was tested under static load to provide reference results for the second group. The four specimens in the second group were tested first under impact loading and then static loading to determine the residual static strengths of the impacted specimens. The test variables considered the type of encased I-section (steel and GFRP), presence of shear connectors, and drop height during impact tests. A mass of 42.5 kg was dropped on the top surface at the mid-span of the tested beams from five different heights: 250, 500, 1000, 1500, and 1900 mm. Moreover, nonlinear Finite Element (FE) models were developed and validated using the experimental data. Static loading was defined as a displacement-controlled loading and the impact loading was modeled as dynamic explicit analysis with different drop velocities. The validated models were used to conduct a parametric study to investigate the effect of the concrete compressive strength on the performance of the composite beams under static and impact loadings. For the composite specimen with steel I-sction, the maximum impact force was 190% greater than the reference specimen NR-I at a drop height of 1900 mm, whereas the maximum impact forces for the specimens composite specimens with GFRP I-sction without and with shear connectors were 19% and 77%, respectively, more significant than the reference beam at the same drop height. The high stiffness for the steel I-beams relative to the GFRP I-beam was the reason for this difference in behavior. The concrete compressive strength was more effective in improving the impact behavior of the composite specimens relative to those without GFRP I-beams