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Several studies indicate that epoxy resin exhibits a very wide range of mechanical behavior, in particular its strength, as a function of stress state. Especially when epoxy resin is used as matrix material for fiber reinforced composites (FRC), this becomes relevant due to complex stress conditions in the matrix. However, the knowledge about the behavior of epoxy resin under uni, bi, and triaxial stress conditions is lacking. Therefore, the mechanical properties of a typical epoxy resin for the production of FRC were investigated given such load conditions. The determined strengths were compared with the predictions of the extended paraboloid criterion. Uniaxial tension and compression tests, torsion tests with overlaid tension and compression, and triaxial tension tests were performed. An elastoplastic material model and a nonlocal damage model were formulated to demonstrate the application of the extended paraboloid strength criterion. In particular, large plastic strains under shear stress conditions, as well as a perfectly brittle material behavior with significantly reduced strength under triaxial tension, could be shown.
In the field of modern drive technology, conventional form-fit shaft-hub connections, such as the standardized keyway connection, are reaching their mechanical limits due to the space-saving design. The trochoidal profiles are elegant modern shaft-hub connections with a compact design for high-power transmission. This article deals with an analytical approach to determining the stress state in trochoidal profiles under shear bending. The solution completes the existing analytical attempts at the load cases of pure bending and torsion. Similar to the torsional loading case, a conformal mapping must be found that can completely transform the unit circle to the non-circle profile area. The conformal mapping function is deduced from the contour equation of the profile. To check the analytical results, in addition, numerical investigations were carried out. The results of the complementary numerical studies show very good agreement with the analytical solutions. The equations derived for the maximum stresses enable a reliable and cost-effective design of the profile shafts subjected to shear force loading.
Tender coconut water is a beverage distinguished from mature coconut water as it's harvested during the early stages of coconut development. It's a well-liked natural drink in tropical regions where coconut trees are abundant. This study aimed to characterize the physicochemical, nutritional and antioxidant properties of different varieties of tender coconut water such as tall, dwarf, intermediate and hybrid varieties with a maturity stage of 5–7 months old. Standard assays assessed nutritional and antioxidant properties. The results of this study showed that the King coconut (Intermediate variety), had significantly higher total protein (0.59 mg BSA/ ml), Total soluble solids (5.0° Brix) and Total sugar content (63.58 mg/ml). The coconut water of Ran thembili (Tall variety) showed significantly higher antiradical activity (DPPH) (82.75 %), total tannin content (22.32 µg TE/ml) and reducing sugar content (43.80 mg/ml). Nawasi (Tall variety) showed significantly higher total flavonoid content (1.23 µg QE/ ml). Total phenolic content and total antioxidant activity were significantly higher for Ran thembili and King coconut. In essence, our findings illuminated the diverse and appealing attributes of tender coconut water. Importantly, the distinct coconut varieties examined in this study exerted a noticeable impact on the composition and properties of tender coconut water.
Increasing human population and extreme consumption of fossil fuels create the potential to generate alternative energy sources. Bioethanol is an alternative and renewable energy resource for fossil fuels, which can be generated from low-cost raw materials. The objective of the study is to optimize pretreatment and culture conditions to enhance bioethanol production from Azolla filiculoides substrate using Saccharomyces cerevisiae. The A. filiculoides was collected from fresh-water ponds, cleaned, dried, milled to fine powder and then autoclaved for 15 min at 121 ℃. When A. filiculoides substrate was pre-treated with different acids and alkaline separately and alcohol production was monitored, significantly higher alcohol (0.1%) was produced with 1 M H2SO4, thus it was selected as the best pre-treatment agent.
The consumer demand for healthier alternative sweeteners to replace modern confectionery continues to increase. Jaggery is a traditional non-centrifugal cane sugar used as a sweetener. This study investigates the physicochemical parameters, antioxidants, and phenolic contents of a confectionery developed by replacing refined sugar with sugarcane jaggery. Hence, its proximate composition, antioxidant activity, total phenolic content, mineral content, colour and texture were determined compared to a control sample made with refined sugar. In the samples made with refined sugar and jaggery the mean value for percentage content of moisture (6.2,7.4), protein (11.3,11.0), crude fibre (0.74,0.78), fat (23.9,25.6), and ash (2.6,3.0) were not significantly different (p > 0.05). The jaggery confectionery sample had significantly higher (p > 0.05) mean values for Mg (76.30 ppm), Ca (65.47 ppm), K (423.70 ppm), Fe (3.61 ppm), and Cu (0.25 ppm) contents than the control sample (Mg (49.38 ppm), Ca (49.30 ppm), K (308.50 ppm), Fe (3.24 ppm), and Cu (0.21 ppm). Total phenolic content and antioxidant activity based on the IC50 value of the developed product were significantly different from that of the control sample (p < 0.05). Collectively, results indicate that the jaggery confectionery sample has promising healthier attributes than the normal confectionery product made using refined sugar.
Plastic pollution, mainly due to single-use food packaging materials, has become a drastic environmental issue around the world. As a consequence of their accumulation, naturally balanced ecosystems may undergo various types of vulnerabilities, and eventually, it may lead to the annihilation of flora, and fauna. Hence, there is an urgent need to find alternative ways of packaging food with environmentally friendly materials. Currently, there are considerable numbers of research being done to prove that biodegradable packaging materials can be produced from plant leaves and sheaths. However, the large-scale production and application of eco-friendly packaging materials is still a challenge and more studies are further required to accomplish it. Hence, this review is done to identify initiatives made in the field of biodegradable packaging material and directs them towards practical application. In the end, it proves that there is a huge potential to produce biodegradable packaging materials from plant sources economically.
Plant leaves, especially from bananas, have been used in food packing for a long time, and it has been proven that banana leaves possess the best attributes in developing bio-degradable packaging materials. The current study aims to determine the effects of four types of chemical treatments on the mechanical properties of banana leaves and to optimize the treatment conditions. Mature banana leaves were immersed in chemicals, namely glycerin (25%, 33%), citric acid (0.5%, 1%), calcium hydroxide (3%, 5%), and sodium chloride (5%, 10%) for seven days while drawing samples daily for testing. The treated samples were tested for mechanical properties such as hardness, tear resistance, and load-bearing capacity, using recommended protocols with slight modifications. The multi-response optimization was done using the statistical method named Grey Relational Analysis to select the best treatment setting. The results revealed that the treatments of citric acid solution (0.5%) for one day and two days, Glycerin (33.3%) for one day and two days, and NaCl solution (10%) for one day were among the first five in the Grey Relational Grades obtained for multi-response optimization and demonstrated a significant (p<0.05) increment for all the three mechanical properties. Hence, the selected chemical treatments positively affect the mechanical properties of banana leaves at their optimum treatment conditions.
