Search

The present work demonstrated the bioactive compound recovery from Bentong ginger (Zingiber officinale Roscoe var. Bentong) using ultrasound-assisted extraction (UAE) in terms of crude yield (CY), as well as total phenolic content (TPC), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing-antioxidant power (FRAP), which reflected the antioxidant properties. These response variables were evaluated as functions of the independent variables; temperature (30 - 60°C), time (10 - 30 min), and ultrasonic intensity (1768 - 5304.10 W/cm2 ), using response surface methodology (RSM). The variables were optimised using quadratic polynomial through the correlations calculated from the regression models fitted to the experimental data. The predicted values of CY, TPC, FRAP, and DPPH under the optimal conditions (40°C, 3536.78 W/cm2 , and 25 min) were 23.42%, 778.08 mg GAE/g, 636.08 µmol Fe2+/g, and 150.01%, respectively. These experimental values were well fitted with the predicted values, except for DPPH. With UAE set at the optimal conditions, a pre-leaching step (PLS) was added to the process to investigate its effect on the extraction. It was found that PLS-UAE produced higher extraction yields (30.15%); however, the antioxidant activity of the extracts was significantly (p < 0.05) higher at the optimised condition for UAE only treatment. The PLS application led to structural cell damage which increased CY, and this was validated through scanning electron microscopy (SEM).

Quaternary glass series of nano and micro-particles europium oxide (III), i.e. Eu2O3, of composition [{(TeO2)0.7 (B2O3)0.3}0.7 (ZnO)0.3](1-y) (EnOm)y, where EnOm is nano or micro Eu2O3 particles coded as TBZEu-NPs and TBZEu-MPs with y = 1.0–5.0 mol% was prepared by melt-quenching technique. Using the pulse-echo technique, the ultrasonic velocities of the glasses were examined. The experimental value of TBZEu-NPs longitudinal, shear, bulk, and Young's modulus ranges between 53.469 and 85.259 GPa, 21.801–24.086 GPa, 24.401–54.790 GPa, and 50.394–61.419 GPa, respectively. For the TBZEu-MPs glasses, they ranged from 46.335 to 87.365 GPa, 21.645–24.649 GPa, 17.475–54.499 GPa, and 45.959–64.260 GPa, respectively. Density and elastic properties were predicted and simulated using an artificial neural network (ANN) model. The correlation coefficients for density, elastic moduli, and Poison's ratio obtained using the ANN model range from 0.9881 to 0.9997. The fitted R-squared value is greater than 95%, and the percentage error calculated is less than 7%. The obtained results were compared to those obtained using the Makishima-Mackenzie elastic model. The prepared glass sample's physical properties and elastic constants indicate that they are sufficiently strong for laser applications.

Magnetorheological elastomers (MREs) are composed of magnetizable particles (iron particles) and a soft rubber-like matrix. Their mechanical properties, including modulus and damping capability, can be controlled by an external magnetic field. The damping properties of MREs, which play an essential role in applications, depend mainly on rubber matrix and arrangement of iron particles content. This study aims to fabricate natural rubber (NR) based magnetorheological elastomers (MREs) with enhanced damping property and great MR effect. Three types of NR-based MRE with 60% iron particle contents namely SMR CV-60 (NR), Epoxidised Natural Rubber (ENR) and Deproteinised Natural Rubber (DPNR) were fabricated into anisotropic and anisotropic MREs, and their properties were compared with Butyl rubber (IIR), and Polyisoprene(IR) based MRE samples. Effects of rubber matrix, microstructure and the used conductive nanofiller on MR effect and damping properties were discussed. The results show that the MR effect of anisotropic MREs is more significant than those of isotropic MREs. Among the NR-based MRE, anisotropic ENR-based MRE exhibits the most significant MR effect (48% at 1% strain), which is close to the MR effect of IIR-based MRE. Also, the ENR-based MRE possesses the maximum loss factor as compared to the other MREs, which are 1.21 and 1.19 for isotropic and anisotropic, respectively. Furthermore, the dynamic test reveals that the ENR-based MRE exhibits the highest damping coefficient and dynamic stiffness at variable frequencies. Finally, the ability of the ENR-based MRE to offer more significant MR effect, controllable stiffness and excellent damping properties confer to it a promising potential to be the future material for an active control device as smart isolator materials, Magnetorheological elastomers (MREs) are composed of magnetizable particles (iron particles) and a soft rubber-like matrix. Their mechanical properties, including modulus and damping capability, can be controlled by an external magnetic field. The damping properties of MREs, which play an essential role in applications, depend mainly on rubber matrix and arrangement of iron particles content. This study aims to fabricate natural rubber (NR) based magnetorheological elastomers (MREs) with enhanced damping property and great MR effect. Three types of NR-based MRE with 60% iron particle contents namely SMR CV-60 (NR), Epoxidised Natural Rubber (ENR) and Deproteinised Natural Rubber (DPNR) were fabricated into anisotropic and anisotropic MREs, and their properties were compared with Butyl rubber (IIR), and Polyisoprene(IR) based MRE samples. Effects of rubber matrix, microstructure and the used conductive nanofiller on MR effect and damping properties were discussed. The results show that the MR effect of anisotropic MREs is more significant than those of isotropic MREs. Among the NR-based MRE, anisotropic ENR-based MRE exhibits the most significant MR effect (48% at 1% strain), which is close to the MR effect of IIR-based MRE. Also, the ENR-based MRE possesses the maximum loss factor as compared to the other MREs, which are 1.21 and 1.19 for isotropic and anisotropic, respectively. Furthermore, the dynamic test reveals that the ENR-based MRE exhibits the highest damping coefficient and dynamic stiffness at variable frequencies. Finally, the ability of the ENR-based MRE to offer more significant MR effect, controllable stiffness and excellent damping properties confer to it a promising potential to be the future material for an active control device as smart isolator materials