The experimental and simulation result of tensile tests of the different specimen has been displayed, as shown in Fig. 4. The simulation results have been calculated based on the input mechanical properties of the different fibers, which are listed in Table 1. Figure 4 shows the tensile load versus displacement curve. It is clear that the maximum load withstanding capacity is for Kevlar/Abaca, followed by the Glass/Hemp, and lastly for Glass/Abaca. All declination of the curve has been displayed in all specimens near the peak load, which may be considered the material’s yield point. In all the specimens, the breaking and ultimate point have been same, the ultimate load of Kevlar/Abaca and Glass/Hemp composites were 267.74% and 6.45% higher, respectively, compared to Glass/ Abaca based composites. The initial displacement of the Kevlar/Abaca and Glass/Hemp corresponds to the load applied, which is higher than Glass/Abaca . It may be due to percentage of elongation of the Kevlar and Abaca, which is higher than the Glass and the Hemp. In kevlar/Abaca curve, as shown in Fig. 4, small fall of load at 2600 N is been displayed due to the difference in the tensile strength of Abaca and Kevlar fibers. It may be due to the load transferred, which is as per the order, i.e., matrix, natural fiber, and synthetic fiber. The failure of the Abaca layer takes place before the Kevlar layer, which is shown in, Fig. 3, the remaining are the fractured specimen after flexural and impact loads shown in Fig. 3. The results show that the load-carrying capacity of the Kevlar/Abaca is very much higher, followed by the Glass/ Hemp and Glass/Abaca due to the higher interfacial bonding between the natural, synthetic, synthetic, and matrix. Apa t from that, there is also a higher load transfer capacity from matrix to the fibers.
The results obtained from the flexural tests of the different specimen has been displayed in Fig. 5. It is clear from the figure that the sequence of the maximum flexible load withstanding capacity, as displayed in Fig. 5, is as follows, Kevlar/Abaca, N Glass/Hemp, Glass/Hemp, and Glass/Abaca. For all the fabricated composites, the flexural loads increase linearly, grow tent kit corresponding to the maximum load’s displacement, and it starts decreasing up to the fracture point. The flexural load withstanding capacity of the Kevlar/Abaca and Glass/Hemp are 340% and 30%, respectively, which is higher than the Glass/ Abaca based composites. Mohanvel et al. reported the same result trend with three different fibers stacking alternatively. They concluded that the effect of the flexural strength varies due to the transfer of forces from inner less force resistive material to outer more resistive material. A sudden fall of load at 70 Kgf in the Kevlar/Abaca added composite after the ultimate load is illustrated in Fig. 5. This is due to the lower stiffness of the Abaca fiber, but herein the load may be transferred to Kevlar . Hen e, the displacement may increase from 18 mm to 21 mm before fracture, as shown in Fig. 5. For Glass/Abaca composite, the same trend has been followed, and there is a small load fall at 18 Kgf, as shown in Fig. 5. The displacement value increases from 5.2 mm to 6 mm before fracture due to the load being transferred from low stiffness material to higher stiffness material. The order of larger displacement of the composites corresponds to the applied flexural load, which is as follows, Kevlar/Abaca, Glass/Abaca, and Glass/Hemp. This order is due to the percentage elongation of the fibers. A good agreement has been found between the experimental and simulation results of flexural load versus displacement of Glass/Hemp composite.The impact test has been conducted for all the specimens, namely, Kevlar/Abaca, Glass/Hemp, and Glass/Abaca. Three times the impact test has been repeated for all the specimens and reported as shown in Fig. 6. The error bar has shown in Fig. 6 for the result variation during each test. The impact has been repeated three times, and the deviation is shown in Fig. 6 as the error bar. The energy absorbed by the composite specimens is shown in Fig. 6. The Kevlar/Abaca specimen absorbs more energy, followed by the Glass/Hemp and the Glass/Abaca. The energy absorbed by Kevlar/Abaca and Glass/ Hemp composites is 63.34% and 55.74%, respectively, which is higher than the Glass/Abaca composite specimens.
The author has reported the same trend of results for impact test: load transferred from less toughness materials to higher toughness materials. The composites’ high energy absorption is load transferred from the matrix, natural fibers, and synthetic fibers, due to the higher inter-facial bonding between matrix, natural fibers, and synthetic fibers.The analysis of variance has been carried out using statistical software for flexural and tensile tests, as shown in Table 2. Three factors are assigned for flexural strength in the ANOVA table: load, extension, and time. In the ANOVA table, two factors are considered for tensile strength: displacement and load. For flexural test, statistical significance was obtained in the order of Glass/Hemp, Glass/Abaca, and Kevlar/Abaca. On the contrary, statistical significant of the tensile test was obtained in the order of Kevlar/Abaca, Glass/Abaca, and Glass/ Hemp. Error associated with the flexural test is comparatively higher than the tensile test for all samples. The error related to the Kevlar/Abaca during flexural test is very high, this is due to the property difference between Kevlar and Abaca. The variation of the bending strength of the natural and synthetic fibers may be the reason for the higher error. It is recommended to apply artificial intelligence tools to model and predict the behavior of those materials.Free radicals, generated in oxidation processes, are essential for the production of energy to fuel biological processes in most of the living organisms. However, the excessive productions of free radicals such as superoxide, hydroxyl and peroxy radicals etc., which responsible for the damage of lipids, proteins and DNA in cells, leading to several degenerative diseases, including inflammation, cardiovascular diseases, cancer, diabetes, and neurological disorders. Generally, all the organisms are well protected against free radical damage by endogenous oxidative enzymes, such as superoxide dismutase , glutathione peroxidase , glutathione reductase and catalase . However, these enzymes are commonly insufficient when it comes to completely preventing degenerative diseases and other health problems. In addition, several non-enzymatic antioxidant compounds such as ascorbic acid, tocopherol, glutathione and other dietary compounds play an important role in defending the body against free radicals damage by scavenge or neutralize the oxidizing molecules and maintaining redox balance.
The plant kingdom offers a wide range of natural antioxidant molecules including phenolic acids, flavonoids, and other secondary metabolites. These metabolites are commonly found in a variety of fruits, vegetables, herbs, cereals, sprouts and seeds. In recent years, there has been increasing interest in obtaining natural dietary antioxidants especially from plants. Previous studies have been reported that the compounds from plants provide potential health benefits, such as antioxidant, anti-inflammatory, antitumor, anticarcinogenic, and antimicrobial activities. They can also be used for the treatment of various ailments including, atherosclerosis, arthritis and diabetes. Hemp is an annual herbaceous plant belongs to Cannabaceae family and originated in Central Asia. The plant has been grown cultivated widely for the purposes of fiber, food and medicine. The seed of hemp is a rich source of nutrition, containing 25%–35% of lipid, 20%–25% of protein, 20%–30% of carbohydrate, 10%–15% of insoluble fiber and a rich array of minerals.The cannabinoids are the most studied constituents from the hemp seed, in particular delta-9-tetrahydrocannabinol is the main psychoactive component. In addition, several other bioactive compounds have been reported from Cannabis include terpenes, sugars, steroids, flavonoids, nitrogenous compounds and non-cannabinoid phenols. In south China, hemp milk is a popular traditional drink that obtained from the crashed hemp seed meal. In Chinese traditional medicine, the kernel of hemp seed is used for the treatments of constipation, gastrointestinal diseases, and antiageing. Hemp seed has several positive health benefits,indoor grow tent including the lowering of cholesterol and high blood pressure. Hemp seed oil produced significant changes in plasma fatty acid profiles and improved clinical symptoms of atopic dermatitis. Further, Nissen et al studied the antimicrobial activity of essential oil of industrial hemp seed and found that the essential oil effectively inhibited the growth of the food-borne and phytopathogens. Recent studies have reported that the hemp seed has been identified as a valuable antioxidant food. However, there is no study in related to expression of antioxidant enzymes by hemp seed. Hence, the present study was carried out to investigate the in vitro antioxidant and expression of antioxidant enzymes activities by ethanol and SF extract of hemp seed.In the present study, ethanol and SF extracts of hemp seed were assayed for their total antioxidant activity as well as the ability to induce activity of antioxidant enzymes such as SOD, GPx and CAT.
Among them, DPPH and ABTS radical scavenging methods are the oldest and frequently used in vitro methods for the evaluation of the antioxidant potential of various natural products based on the transfer of hydrogen between the free radicals and the antioxidants. The results of the in vitro antioxidant studies revealed that the SF extract showed higher DPPH and ABTS radical scavenging activities when compared to those of ethanol extract. It appears that the ethanol extract and SF extracts of hemp seed possess hydrogen donating capabilities to act as antioxidant. The chemical constituents are important factors governing the efficacy of natural antioxidants. Radical scavenging activities by the sample might be due to the presence of the hydroxyl groups in their structure and their electron donating ability. The scavenging properties of antioxidant compounds are often associated with their ability to form stable radicals[26]. In vitro radical scavenging of different varieties and extracts of hemp seed were determined by Chen et al and reported that the IC50 of DPPH ranged from 0.09 to 4.55 mg/mL and IC50 of ABTS ranged from 0.012 to 0.485. Further, the authors isolated two potent free radical scavenging compounds, N-trans-caffeoyltyramine and cannabis in B from the seeds of hemp. Girgih et al reported the antioxidant potential of protein hydrolysate fractions of hemp seed using various in vitro assays such as DPPH and hydroxyl radical scavenging, metal chelating, ferric reducing, and inhibition of linoleic acid oxidation. In addition, methanol extract of cold-pressed hemp seed oil possessed significant antioxidant and free radical scavenging activities. Antioxidant enzymes are considered to be most important in cellular defenses because they balance the redox status in cells by remove the excessive free radicals. Previous studies have stated that intracellular generation of H2O2 is an important mediator of apoptosis. Various enzymes including superoxide dismutase, peroxidases and catalase are effectively involved in H2O2 modulation. Previous studies have been reported that up-regulating the expression of antioxidant enzymes in HepG2 cells promotes a protective effect against cytotoxicity or apoptosis induced by oxidative stress. SOD reacts with superoxide anion radical to produce oxygen and the less-reactive H2O2. H2O2 in turn can be neutralized by both GPx and catalase. Landis and Tower reported that the level of catalase is lowered in several tumor cells, which results in a decreased detoxifying capacity for H2O2 in tumors. Similar to our results, Bak et al reported that the essential oil of red ginseng significantly restored the expression of antioxidant enzymes in HepG2 cells. Therefore, induction of expression of these antioxidant enzymes seems to be essential for prevention of various free radical-mediated diseases such as cancer, arthrosclerosis, and chronic inflammation. In addition, Valko et al suggested that the expression of these antioxidant enzymes may also be regulated by upstream proteins such as mitogen-activated protein kinases like c-Jun N-terminal kinase, extracellular-regulated kinase and p38 etc. The effect of ethanol and SF extracts of hemp seed on the expression activity of antioxidant enzymes that modulate H2O2 levels, such as superoxide dismutase , glutathione peroxidase and catalase in HepG2 cells had not been previously investigated. Several authors have studied that the antioxidant and free radical scavenging potentials of hemp seed. In addition, biological activities of the sample are directly related to their chemical composition. Previous investigations have been reported that the hemp seed and its oil contain numerous health promoting chemical substances including flavonoids, terpenes, steroids etc..