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Surface area and porosity are the main factors that affect hydrogen storage at room temperature. However, there are several external factors such as pressure of gas, reaction time and the amount of sample used during the process that might affect the performance of the hybrid nanocomposites towards hydrogen storage. In this study, central composite design (CCD) for response surface methodology (RSM) was used in determining the optimum conditions namely mass of sample (A), pressure of hydrogen gas (B) and reaction time (C) towards the hydrogen storage at room temperature. Rice husk derived graphene-like material (GRHC) was added into zeolitic imidazolate frameworks-8 (ZIF-8) to form a hybrid nanocomposite of ZIF-8/GRHC (ZGK) via in-situ synthesis. Due to synergistic effect, the surface area of ZGK (1065.51 m2/g) shows a great enhancement as 0.04 g GRHC was introduced as compared to pristine ZIF-8 (687.32 m2/g). On the other hand, the thermal stability of ZGK improved significantly as it can withstand up to 1000 ºC as compared to pristine GRHC and ZIF-8 respectively. Due to superior physicochemical properties of ZGK, it was chosen to undergo optimization of hydrogen storage at room temperature. From the confirmatory test which was run for three times, the optimum hydrogen storage at room temperature in ZGK was 1.95 wt.% when 0.50 g of ZGK was used; 15 bar of hydrogen gas was applied and the reaction time was 60 min as per suggested from the CCD.Highlights: The addition of GRHC enhanced the surface area of ZGK up to 55 %. ZGK exhibited a smaller pore size, 0.81 nm which is desired to store hydrogen. Thermal stability of ZGK improved (~1000 ºC) as GRHC is introduced in the nanocomposites. The optimum condition for hydrogen storage was; 0.50 g of ZGK, 15 bar of hydrogen gas and 60 mins reaction time. The optimum hydrogen storage of ZGK at room temperature was around 1.95 wt. %. [ABSTRACT FROM AUTHOR]

This current research examines the behaviour of dusty Jeffrey fluid across an inclined stretching sheet with CNTs as well as aligned magnetohydrodynamic (MHD). By utilising the proper similarity transformation variables, the governing partial differential equations (PDEs) of the problem are converted to ordinary differential equations (ODEs). Then, the numerical results are produced by using the Runge-Kutta-Fehlberg (RKF45) approach with the aid of the MAPLE software. The findings include the visual illustrations of the impacts on the velocity and temperature profiles for several pertinent parameters. It clearly shows that the decline in velocity profile of fluid phase was caused by the rise in aligned angle, ratio of relaxation to retardation times, magnetic field and fluid particle interaction parameters. Meanwhile, for every parameter that is involved excluding ratio of retardation time in the fluid, the temperature profile rises in both the fluid and dusty phases. The results of this study add a unique perspective to the existing literature by offering fresh insights on the influence of CNTs and dust particles, examining their impact on two-phase flowover an inclined stretching sheet. This understanding can be utilized in the real-time application where rapid and efficient thermal management is critical such as electronics cooling or energy conversion systems. Furthermore, the inclusion of viscous dissipation andNewtonian heating (NH) effects contributes to the novelty of the research, providing a comprehensive understanding of the complex interactions in this unique fluid flow scenario. [ABSTRACT FROM AUTHOR]

The foremost objective of this study is to reflect the behaviour of hybrid nanofluid towards a permeable porous medium, with consideration of second-order velocity slip and heat absorption impacts on the fluid flow. Two distinct fluids of copper (Cu) and aluminium oxide (Al2O3) are reviewed in this study to work out as a hybrid nanofluid flow. The equations of boundary layer flow in the formof partial differential equations are reduced to a system of ODEs by conducting a similarity transformation technique, and the findings that obtained from this study are presented in the respective tables and figures. The effects of involving parameters such as suction, porous medium permeability, heat absorption and second order velocity slip are perceived, as well as our intention in observing the impact of traditional nanofluid and hybrid nanofluid on the fluid flow. Our findings revealed that the hybrid Cu-Al2O3/water nanofluid performs well on the fluid flow behaviour against the mono Al2O3/water nanofluid. Moreover, the participating parameters of porous medium permeability, suction and nanoparticle volume fraction are said to improve the boundary layer thickness, while second-order velocity slip parameter is deemed to decay the fluid flow. [ABSTRACT FROM AUTHOR]

Two-phase flow problem has attracted considerable attention of many researchers due to its potential in investigating the flow characteristics of binary mixture of fluid and solid particles. In line with this, a mathematical model of convective flow of Casson fluid embedded with solid particles (dust) is formulated in order to study the interaction between the fluid phase and dust phase under the influences of non-linear thermal radiation and convective boundary condition (CBC) which is moving over a vertical stretching sheet. Through the use of similarity transformations, governing equations of fluid and dust phases are reduced into ordinary differential equations, which are then solved numerically by employing the Runge-Kutta Fehlberg (RKF45) method. The effects of radiation parameter and temperature ratio on velocity and temperature profiles, together with skin friction coefficient and Nusselt number are presented graphically as well as in tabular form. Findings reveal that, both effects improve the motion and temperature of fluid and dust phases, respectively. [ABSTRACT FROM AUTHOR]

The Cu2O-based homostructure thin film was successfully fabricated on FTO glass substrate using conventional electrodeposition method. Prior to the p-Cu2O thin film deposition, cyclic voltammetry (CV) measurement was carried out in order to obtain optimum deposition parameter. Based on the CV result, p-Cu2O thin film was deposited on n-Cu2O with deposition potential of -0.4 V vs Ag/AgCl, solution temperature of 40 °C and pH 12.5, respectively. The deposition time was varied and it was found that the optimum deposition time for Cu2O-based homostructurethin film was 2 h. Structural, morphological, and optical properties were characterized using Xray diffraction, field emission-scanning electron microscope and ultraviolet and visible absorption spectroscopy, respectively. The successful fabrication of homostructure was confirmed using photoelectrochemical measurement. [ABSTRACT FROM AUTHOR]

High productivity of cultivars is still the main goal inbreeding programs of many crops in Indonesia. Efforts to increase maize productivity can be undertaken through systematical management of heterosis and combining ability from heterotic pool for establishing new prosperous hybrid cultivars. Hence, the aims of this research were to construct heterotic groups of maize inbred lines and to elucidate the role of the combining ability in the hybrid performance. Hundred hybrids were developed by crossing inbred lines in a complete diallel fashion. The combining ability of inbred lines was evaluated and analyzed by employing Griffing's method 1, cluster analysis and GGE biplot. The result revealed that the general and specific combining abilities could assign inbred lines into three heterotic groups and had a critical role in the hybrid performance for grain yields. Data recorded from reciprocal crosses tended to show better mean and gave more valuable information for hybrid breeding than direct crosses. The use of the combining ability analysis based on Griffing's and GGE biplot has clearly elucidated all characters observed in both general combining ability and specific combining ability. It would provide comprehensive information for genetic analysis in maize breeding. Three heterotic groups were created. The group 1 consisted of three inbred lines, group 2 had only one inbred line and rest were assigned into group 3. [ABSTRACT FROM AUTHOR]

Corn is the most productive cereal crop in the world. It is suitable to be planted at the area of high temperature, as ear (cob) maturation is determined by the accumulation of heat gained by the plant. In Indonesia, field corn is the second staple food following rice, though the purple corn has not been found abundantly in this region. This research was carried out during two planting seasons (March to December 2014) at the Brawijaya University, Malang, East Java, Indonesia. Most of the current research discussed about the anthocyanin as favorable antioxidant for health and is reported to have for specific anti-cancerous effect. Efforts were made to determine the trait changes in purple corn plant following pollen mutation with gamma ray irradiation. The observations regarding amylopectin and anthocyanin contents including morphological and agronomic traits were recorded. The pollen of 40 purple corn genotypes have been irradiated with gamma irradiation with the given doses of 0 Gy, 25 Gy, 50 Gy, and 100 Gy per 10 genotypes at National Nuclear Energy Agency (BATAN), Indonesia. After pollination with irradiated pollen, 200 generated seeds in each irradiation level were used for planting material. Gamma irradiation affected on purple corn crops will all given doses except 0 Gyand observed some unique plants of curly glume stalk at 25 Gy, three-pronged ears at 50 Gy, and an extra-ordinary long for ear stalk at 100 Gy. The regression of gamma irradiation dose with amylopectin was y = -0.001x2 + 0.171x + 40.17 (R2 = 0.802), while that with anthocyanin was y = -0.001x2+ 0.026x + 0749 (R2 = 0.617). [ABSTRACT FROM AUTHOR]

The two-dimensional mathematical model of water-based hybrid nanofluid, where the nanoparticles of the model are alumina (Al2O3) and copper (Cu) is analyzed in this article. It describes the heat and mass transfer which are induced by concentration and temperature differences, respectively. The current mathematical model extended the works by implementing both directions of moving sheet in the boundary conditions: stretching and shrinking, and use the exponential variations of the sheet velocity, temperature, and concentration of the hybrid nanofluid at the sheet. The final numerical solutions can be obtained by implementing Matlab bvp4c, which involves the step of choosing the most reliable solution in an actual fluid situation. This selection technique on numerical solutions is known as stability analysis and only needs to apply when more than one numerical solution appears in the Matlab bvp4c program. Finally, the controlling parameters such as nanoparticle solid volume fraction, suction, shrinking/stretching, Soret and Dufour cause an increment or decrement in the flow, heat and mass transfer in the hybrid nanofluid. For the stable solution, fluid velocity becomes slower whereas temperature and concentration of the fluid increase when the percentage of Cu, as well as Al2O3, rises into the water. Moreover, in case of local Nusselt number and local Sherwood number it is proved that Soret effect is the opposite phenomenon of Dufour effect. [ABSTRACT FROM AUTHOR]

The main aim of this work was to assess the frying strength of the enzymatically synthesized palm-based medium- and long-chain triacylglycerols (MLCT) oil with the aid of different antioxidants under deep-frying conditions. Palm-based MLCT oil in the presence of synthetic or natural antioxidants showed significantly better ( P < 0.05) thermal resistance and oxidative strength than refined, bleached, and deodorized (RBD) palm olein throughout the five consecutive days of frying. Rancimat induction period, free fatty acid content, anisidine value, $$E^{{\text{1\% }}} _{1{\text{cm}}} $$ at 232 and 268 nm, color, percentage of oil uptake, and viscosity measurement can be used as oil quality parameters to indicate the degree of oil deterioration under continuous stressed frying conditions. No significant changes ( P > 0.05) in the saturated/unsaturated fatty acids ratio across frying periods indicated good oxidative stability of the palm-based MLCT oil. Due to the polarity of medium- and long-chain triacylglycerols in palm-based MLCT oil, total polar compounds determination may not be a suitable oil quality measures. Sensory evaluation of fried chips showed no significant differences ( P > 0.05) between chips fried in RBD palm olein and palm-based MLCT oil over the 3-month storage period. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of non-uniform temperature gradient and magnetic field on Marangoni convection in a horizontal fluid layer heated from below and cooled from above with a constant heat flux. A linear stability analysis is performed. The influence of various parameters on the convection onset is analyzed. Six non-uniform basic temperature profiles are considered, and some general conclusions about their destabilizing effects are presented. [ABSTRACT FROM AUTHOR]

Linear stability theory is applied to the problem of the onset of oscillatory Marangoni convection in a horizontal layer of electrically conducting fluid heated from below in the presence of a vertical magnetic field. The fluid layer is bounded from below by a rigid boundary and from above by a deformable free surface. The critical Marangoni number M[subc], the critical wavenumber a[subc] and the critical frequency w[subc] are obtained for wide ranges of the Prandtl number P[sub1], the magnetic Prandt[subl] number P[sub2], the crispation number C[subr] and the Chandrasekhar number Q. We present numerically a necessary and sufficient condition for oscillatory Marangoni convection to occur. [ABSTRACT FROM AUTHOR]

The present study focuses on the design and finite element analysis of a novel hip prosthesis comprising truss structures intended to equally distribute the stress along the prosthesis. The prosthesis is designed to suit three different inclination angles of 20°, 40° and 60°. The three designs were subjected to loading conditions that emulate walking, jogging, and cycling activities via finite element simulations. Using the von Mises yield criterion and Goodman relation for fatigue, it is found that the safety factor and the life cycle of the proposed prosthesis design was within the acceptable range. Furthermore, the truss structures incorporated in the prosthesis appear to reduce the stress levels in the femur. [ABSTRACT FROM AUTHOR]

In industrial processes such as the paper production, reservoir engineering and thermal retrieval process, combined Soret and Dufour effects are involved. Also, the Soret-Dufour effect has been used in the chemical industry for detachment, purification, and radioactive nuclear waste material. Therefore, a mathematical model of Soret-Dufour effects in a Casson fluid flow caused by a shrinking sheet is presented in this paper. This model is subjected to an inclined magnetic field, along with the exponential variations of the variables at the sheet, i.e. velocity, temperature, and concentration. Ordinary differential equations for momentum, energy, and concentration are solved numerically using the bvp4c MATLAB program. At the end of the calculations, the profiles of velocity, temperature and concentration are displayed. In addition, the skin friction coefficient, the local Nusselt number and the local Sherwood number are also considered. Numerical results of velocity, temperature, and concentration profiles, together with the skin friction coefficient, local Nusselt number and local Sherwood number are shown in the form of tables and graphs. The numerical results show that the skin friction coefficient and the local Sherwood number decrease, whereas the temperature profile and the local Nusselt number for the first solution increase with the increment of the Soret number. Velocity and concentration profiles decrease with the increment of the Dufour number. [ABSTRACT FROM AUTHOR]

Research on heat transfer problems is important in view of applications in industries and engineering. As a result, the present study examines numerically the steady MHD stagnation point flow and heat transfer over a shrinking sheet in the presence of suction, thermal radiation, viscous dissipation and velocity slip. The flow for this problem is considered in nanofluids and a Buongiorno's model is used. The boundary layer equation is derived by reducing the governing equations to an ordinary differential equation. An appropriate similarity transformation is used to convert from PDEs to ODEs. The numerical results were then processed using the bvp4c package in Matlab. The impacts of the characteristics studied were graphically represented and extensively described in this study. Dual solutions occur within a particular range of a, according to the numerical results. Finally, a stability analysis proves that there are two solutions to the problem and only one of them is stable. [ABSTRACT FROM AUTHOR]

This paper presents a numerical analysis of a steady three-dimensional fluid flow and heat transfer towards a permeable shrinking sheet. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, which are then solved numerically by a shooting method. The effects of the governing parameters on the skin friction and heat transfer from the surface of the shrinking surface are illustrated graphically. It is found that dual solutions exist for the shrinking case. A comparison with known results from the open literature has been done and it is shown to be in excellent agreement. [ABSTRACT FROM AUTHOR]

The problem of steady laminar magnetohydrodynamic (MHD) mixed convection stagnation-point flow of an incompressible viscous fluid over a vertical stretching sheet is studied. The effect of an externally magnetic field is taken into account. The transformed boundary layer equations are solved numerically by using an implicit finite-difference scheme. Numerical results are obtained for various values of the mixed convection parameter, Hartmann number, and Prandtl number. The effects of an externally magnetic field on the skin friction coefficient, local Nusselt number, velocity, and temperature profiles for both A > 1 and A < 1, where A is the velocity ratio parameter, are presented graphically and discussed in detail. Both assisting and opposing flows are considered, and it is found that dual solutions exist for the opposing flow. [ABSTRACT FROM AUTHOR]

Combined effect of magnetic field and internal heat generation on the onset of Rayleigh-Bénard convection in a horizontal micropolar fluid layer is studied. The bounding surfaces of the liquids are considered to be rigid-free, rigid-rigid, and free-free with combination isothermal on the spin-vanishing boundaries. A linear stability analysis is used and the Galerkin method is employed to find the critical stability parameters numerically. The influence of various parameters on the onset of convection has been analyzed. It is shown that the presence of magnetic field always has a stability effect on the Rayleigh-Bénard convection in micropolar fluid. [ABSTRACT FROM AUTHOR]

The problem of thermal diffusion and diffusion thermo effects on thermosolutal Marangoni convection flow of an electrically conducting fluid over a permeable surface is investigated. Using appropriate similarity transformations, the governing system of partial differential equation is transformed to a set of nonlinear ordinary differential equations, then solved numerically using the Runge-Kutta-Fehlberg method. The effects of thermal diffusion and diffusion thermo, magnetic field parameter, thermosolutal surface tension ratio, and suction/injection parameter on the flow field, heat transfer characteristic, and concentration are thoroughly examined. Numerical results are obtained for temperature and concentration profiles as well as the local Nusselt and Sherwood numbers are presented graphically and analyzed. It is found that these governing parameters affect the variations of the temperature and concentration and also the local Nusselt and Sherwood numbers. [ABSTRACT FROM AUTHOR]

The problem of the steady magnetohydrodynamic (MHD) stagnation-point flow of an incompressible viscous fluid over a stretching sheet is studied. The effect of an induced magnetic field is taken into account. The nonlinear partial differential equations are transformed into ordinary differential equations via the similarity transformation. The transformed boundary layer equations are solved numerically using the shooting method. Numerical results are obtained for various magnetic parameters and Prandtl numbers. The effects of the induced magnetic field on the skin friction coefficient, the local Nusselt number, the velocity, and the temperature profiles are presented graphically and discussed in detail. [ABSTRACT FROM AUTHOR]

Mixed convection is commonly used in electronic cooling processes and nuclear reactor technology. As a result, this study aims to demonstrate the mathematical formulation of fluid flow, heat and mass transfer under the controlling physical parameters such as mixed convection, buoyancy ratio, suction, magnetic field, and rotation angle of the sheet. The variation in the wall shrinking velocity, temperature and concentration is expressed as an exponential function. Since controlling equations are partial differential equations, similarity transformations convert these partial differential equations to ordinary differential equations. Finally, these ordinary differential equations are considered as a non-linear and non-dimensional boundary value problem. The final solution of these ordinary differential equations is obtained numerically by applying the Matlab bvp4c programme. Stability analysis which determines the most stable numerical solution between duel solutions is also made using the Matlab bvp4c programme. Comparing the obtained computational results to previously published data shows a good agreement. All numerical results are graphically illustrated and explained, including the velocity, temperature and concentration profiles, skin friction coefficient, local Nusselt number, and local Sherwood number. [ABSTRACT FROM AUTHOR]

This paper discussed the study of unsteady three-dimensional boundary layer rotating flow and heat transfer in Copper-water nanofluid over a stretching sheet. The partial differential equations are transformed to ordinary differential equations using the appropriate similarity variables and are then solved numerically by shooting method. The effects of unsteady parameter A, suction and injection parameter s, rotating parameter Ω and volume fraction parameter ϑ on the skin friction coefficient, local Nusselt number together with dual velocity as well as temperature profiles are shown graphically [ABSTRACT FROM AUTHOR]

In this paper, the steady magnetohydrodynamic (MHD) mixed convection stagnation point flow of an incompressible, viscous, and electrically conducting fluid over a vertical flat plate is investigated. The effect of induced magnetic field is taken into account. Numerical results are obtained using an implicit finite-difference scheme. Both assisting and opposing flows are considered. The results for skin friction, heat transfer, and induced magnetic field coefficients are obtained and discussed for various parameters. The velocity, temperature, and induced magnetic field profiles are also presented. For the case of the opposing flow, it is found that dual solutions exist for a certain range of the buoyancy parameter. Dual solutions are also obtained for the assisting flow. [ABSTRACT FROM AUTHOR]

The steady magnetohydrodynamic (MHD) mixed convection stagnation-point flow toward a vertical heated surface is investigated in this study. The external velocity impinges normal to the vertical surface and the surface temperature are assumed to vary linearly with the distance from the stagnation point. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions also exist for the assisting flow, besides that usually reported in the literature for the opposing flow. [ABSTRACT FROM AUTHOR]

The main objective of this study was to understand the effects and relationship amongst four factors, which are reaction temperature, reaction time, enzyme load, and substrate mole ratio with the purpose of producing healthy functional cooking oil for long-term dietary treatment. Lipozyme RM IM lipase-catalyzed esterification of medium- and long-chain triacylglycerols (MLCT) from glycerol and mixtures of capric and oleic acid was optimized using response surface methodology (RSM) with a five-level, four-factorial design. Reaction temperature, reaction time, and substrate mole ratio strongly affected MLCT synthesis (P<0.01). However, enzyme load did not have a significant (P>0.01) effect on MLCT yield. Comparison between predicted and experimental value from central composite rotatable design optimization procedures revealed good correlation, implying that the reduced cubic polynomial model with backward elimination statistically expressed the percent MLCT yield obtained. The optimum MLCT yield was 59.76% by using 10 wt% enzyme load, reaction temperature of 70°C, reaction time of 14 h, and substrate mole ratio of 3.5:1. Experiments to confirm the predicted results using the optimal parameters showed an MLCT yield of 56.35% (n=2). The choice on the types of fatty acids used in MLCT optimization work greatly influenced the physical and chemical properties of MLCT oil produced. The refined MLCT oil characteristics study showed this oil is suitable to be used for cooking/frying purposes as a high-value added product. [ABSTRACT FROM AUTHOR]