This study focused on maximizing the extraction yield of total phenolics and flavonoids from Curcuma Zedoaria leaves as a function of time (80–120 min), temperature (60–80 °C) and ethanol concentration (70–90 v/v%). The data were subjected to response surface methodology (RSM) and the results showed that the polynomial equations for all models were significant, did not show lack of fit, and presented adjusted determination coefficients (R2) above 99%, proving their suitability for prediction purposes. Using desirability function, the optimum operating conditions to attain a higher extraction of phenolics and flavonoids was found to be 75 °C, 92 min of extraction time and 90:10 of ethanol concentration ratios. Under these optimal conditions, the experimental values for total phenolics and flavonoids of Curcuma zedoaria leaves were 125.75 ± 0.17 mg of gallic acid equivalents and 6.12 ± 0.23 mg quercetin/g of extract, which closely agreed with the predicted values. Besides, in this study, the leaves from Curcuma zedoaria could be considered to have the strong antioxidative ability and can be used in various cosmeceuticals or medicinal applications.

Objective: To investigate the in vitro anti-elastase, anti-collagenase, and antimicrobial activities of the red pitaya peel extract for cosmetic application focusing on skin aging.Methods: Extraction was performed by the reflux method for 103 minutes at 56°C with 82% aqueous ethanol solution and the red pitaya peel extract was evaporated using a rotary evaporator. Anti-elastase and anti-collagenase properties were evaluated using the drug discovery kits (neutrophil elastase colorimetric and matrix metalloproteinase-1 colorimetric, respectively). The antimicrobial potential was analyzed using agar well diffusion method against 10 selected microorganisms, and the presence or absence of the inhibition zones was identified.Results: The red pitaya peel extract exhibited remarkable inhibition percentage 87.62±0.05% and 96.92±0.02% for anti-elastase and anti-collagenase activities, respectively. Red pitaya peel extract showed significant inhibition against the Gram-positive Bacillus subtilis B29 with an inhibition zone diameter of 8.0±0.3 mm.Conclusion: The excellent anti-aging properties displayed by the underutilized red pitaya peel extract highlighted its potential as a natural source of anti-aging agent for cosmetic formulations.

An artificial neural network (ANN) was applied in conjunction with experimental data from mixture experimental design to predict the melting point of lipstick formulation. The experimental data were utilized for training and testing of the suggested model. By using performance of ANN, the optimum parameters were pitaya seed oil 25 w/w%, virgin coconut oil 37 w/w%, beeswax 17 w/w%, candelilla wax 2 w/w% and carnauba wax 2 w/w%. The relative standard error under these parameters is only 0.8772%. It was found that batch back propagation (BBP) as the optimal algorithm and topology with configuration of 5 inputs, 2 hidden and 1 output nodes; respectively with the most importance relative parameter is carnauba wax 24.5%.

The nonlinear stability analysis of a ferrofluid layer system is formulated mathematically. This system considered the upper and lower free isothermal boundary with the system heated from below. A mathematical formulation is produced to study the behaviour of the chaotic convection in a ferrofluid layer system using Galerkin truncated expansion. The Boussinesq approximation is opted with the existence of internal heating and the magnetic number. It is found that the transition to chaos in this present study is identical to the Lorenz attractor and thus validate the method and analysis of this study. The impact of elevating the internal heat generation is found to hasten the instability of the system and as for the magnetic number, at M1 = 2.5 the homoclinic bifurcation occurs and thus accelerates the convection process.

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The influences of feedback control and internal heat source on the onset of Rayleigh-Bénard convection in a horizontal nanofluid layer is studied analytically due to Soret and Dufour parameters. The confining boundaries of the nanofluid layer (bottom boundary-top boundary) are assumed to be free-free, rigid-free, and rigid-rigid, with a source of heat from below. Linear stability theory is applied, and the eigenvalue solution is obtained numerically using the Galerkin technique. Focusing on the stationary convection, it is shown that there is a positive thermal resistance in the presence of feedback control on the onset of doublediffusive convection, while there is a positive thermal efficiency in the existence of internal heat generation. The possibilities of suppress or augment of the Rayleigh-Bénard convection in a nanofluid layer are also discussed in detail.

A linear stability analysis has been carried out to examine the effect of internal heat source on the onset of Rayleigh-Bénard convection in a rotating nanofluid layer with double diffusive coefficients, namely, Soret and Dufour, in the presence of feedback control. The system is heated from below and the model used for the nanofluid layer incorporates the effects of thermophoresis and Brownian motion. Three types of bounding systems of the model have been considered which are as follows: both the lower and upper bounding surfaces are free, the lower is rigid and the upper is free, and both of them are rigid. The eigenvalue equations of the perturbed state were obtained from a normal mode analysis and solved using the Galerkin method. It is found that the effect of internal heat source and Soret parameter destabilizes the nanofluid layer system while increasing the Coriolis force, feedback control, and Dufour parameter helps to postpone the onset of convection. Elevating the modified density ratio hastens the instability in the system and there is no significant effect of modified particle density in a nanofluid system.

The neutral convection in a double-diffusive fluid layer subject to the internal heat source (internal heating) and thermodiffusion or also known as Soret effect is studied analytically. The influence of the internal heating is supplied by an internal volumetric source with a uniform distribution. Results show that the presence of internal heating in the binary fluid layer which is fluid layer heated and salted has a significant influence on the neutral convection where increasing the internal heating will destabilize the fluid system. Despite the destabilizing factor, an increase of the Solutal Rayleigh number spikes the critical Rayleigh number and thus ensures greater stability of the system. The instability gets fluctuate depending on values of Soret parameter in the presence of internal heating.