Boundary and thermal non-equilibrium effects on convective instability in an anisotropic porous layer

The effects of boundary and local thermal non-equilibrium on the criterion for the onset of convection in a sparsely packed horizontal anisotropic porous layer are investigated. A two-field temperature model each representing the solid and fluid phases separately is used and the flow in the porous medium is described by the Brinkman extended-Darcy model. The lower boundary is rigid, while the upper boundary is considered to be either rigid or free with fixed temperature conditions at the boundaries. The stability equations are solved numerically using the Galerkin method to extract the critical stability parameters. The influence of local thermal non-equilibrium, mechanical and thermal anisotropy parameters representing the fluid and solid phases is assessed on the stability characteristics of the system. The existing results are obtained as limiting cases from the present study.     

Penetrative ferroconvection in a porous layer

Penetrative convection in a horizontal ferrofluid-saturated porous layer in the presence of a uniform applied vertical magnetic field has been investigated via the internal heating model using the Brinkman-extended Darcy equation. The rigid-isothermal boundaries of the porous layer are considered to be either paramagnetic or ferromagnetic. The eigenvalue problem is solved numerically using the Galerkin method with either thermal or magnetic Rayleigh number as the eigenvalue. The stability of the system is significantly affected by the internal heating in the porous layer. It is noted that the paramagnetic boundaries with large magnetic susceptibility delay the onset of penetrative ferroconvection the most when compared to very low magnetic susceptibility as well as ferromagnetic boundaries. An increase in the value of magnetic Rayleigh number (R _m ), heat source strength (N _S ) and non-linearity of magnetization (M ₃) is to hasten the onset of ferroconvection. In addition, the stability of the system when heated from above and also in the absence of thermal buoyancy has been discussed in detail.     

Effective face recognition using dual linear collaborative discriminant regression classification algorithm

Multimedia Tools and Applications - In recent decades, face recognition is an attractive and emerging research area in computer vision and pattern recognition applications. Still, facial...     

Double diffusive LTNE porous convection with Cattaneo effects in the solid

The impact of Cattaneo heat flux law in the solid on the onset of double‐diffusive Darcy porous convection with local thermal nonequilibrium temperatures is investigated. The Fourier law of heat transfer is invoked for the fluid, whereas the Cattaneo heat flux law used to transfer heat in solid skeleton alters the temperature equation from parabolic to hyperbolic. The results are obtained for porous skeletons of aluminum and copper oxides. Both Cattaneo and solute concentration effects reinforce in controlling the onset of oscillatory convection and some novel consequences are observed. Compared with the results perceived in the absence of solute concentration, a manifestation of oscillatory convection with scaled‐interphase heat transfer coefficient as well as solid thermal relaxation time parameter initiates earlier in its presence. The effect of increasing interphase heat transfer coefficient and the Lewis number is to delay and hasten the onset of stationary and oscillatory convection. Besides, the increase in the value of solid thermal relaxation time parameter advances the oscillatory onset. Although the increase in the solute Darcy–Rayleigh number is to delay the stationary onset, it shows a twofold behavior on the onset of oscillatory convection. Before the onset of oscillatory convection, the size of the convection cell gets narrower and after which it becomes much wider. The existing results are retrieved as limiting cases from the current study.     

The onset of Brinkman ferroconvection using a thermal non-equilibrium model

The onset of ferroconvection in a horizontal layer of ferrofluid saturated Brinkman porous medium heated uniformly from below in the presence of a uniform vertical magnetic field is investigated when the solid and fluid phases of the porous medium are in local thermal non-equilibrium (LTNE) using linear stability theory. The modified Brinkman–Forchheimer-extended Darcy equation is employed to describe the flow in the porous medium and a two-field model for energy equation each representing the solid and fluid phases separately is used. It is established that the principle of exchange of stability is valid. The authenticity of LTNE model over LTE model and also the ferromagnetic effects on the stability of the system are discussed in detail. The system is found to be more stable when the magnetic forces alone are present. Asymptotic analysis for both small and large values of scaled inter-phase heat transfer coefficient H_t is presented and the results are found to be in good agreement with those obtained from the exact formula. The established results in the literature have been reproduced as particular cases from the present study.     

Effects of MFD viscosity and LTNE on the onset of ferromagnetic convection in a porous medium

The combined effect of magnetic field dependent (MFD) viscosity and a local thermal non-equilibrium (LTNE) on the criterion for the onset of ferromagnetic convection in a ferrofluid saturated horizontal porous layer heated from below in the presence of a uniform vertical magnetic field is studied analytically using linear stability theory. A modified Darcy equation is used to describe the flow in the porous medium and a two-field model for temperature each representing the solid as well as fluid phases separately is used for energy equation. It is demonstrated that the principle of exchange of stability is valid. The results indicate that the onset of ferromagnetic convection is delayed with an increase in the MFD viscosity parameter but shows no influence on the critical wave number. Moreover, the system is found to be more stable when the magnetic forces alone are present. Asymptotic solutions for both small and large values of scaled interphase heat transfer coefficient H_t are presented and compared with those computed numerically. An excellent agreement is obtained between the asymptotic and the numerical results. Besides, the influence of magnetic and LTNE parameters on the stability characteristics of the system is also discussed.     

The onset of ferroconvection in a horizontal ferrofluid saturated porous layer heated from below and cooled from above with constant heat flux subject to MFD viscosity

The effect of magnetic field dependent (MFD) viscosity on the onset of ferroconvection in a ferrofluid saturated horizontal porous layer is investigated theoretically. The bounding surfaces of the porous medium are considered to be either rigid-ferromagnetic or stress free with constant heat flux conditions. The resulting eigenvalue problem is solved numerically using the Galerkin technique and also analytically by regular perturbation technique. It is found that increase in porous parameter, MFD viscosity parameter and decrease in the magnetic number is to delay the onset of ferroconvection, while the nonlinearity of fluid magnetization has no influence on the stability of the system.     

Synthetic Biology: Applications in the Food Sector

Synthetic biology also termed as “genomic alchemy” represents a powerful area of science that is based on the convergence of biological sciences with systems engineering. It has been fittingly described as “moving from reading the genetic code to writing it” as it focuses on building, modeling, designing and fabricating novel biological systems using customized gene components that result in artificially created genetic circuitry. The scientifically compelling idea of the technological manipulation of life has been advocated since long time. Realization of this idea has gained momentum with development of high speed automation and the falling cost of gene sequencing and synthesis following the completion of the human genome project. Synthetic biology will certainly be instrumental in shaping the development of varying areas ranging from biomedicine, biopharmaceuticals, chemical production, food and dairy quality monitoring, packaging, and storage of food and dairy products, bioremediation and bioenergy production, etc. However, potential dangers of using synthetic life forms have to be acknowledged and adoption of policies by the scientific community to ensure safe practice while making important advancements in the ever expanding field of synthetic biology is to be fully supported and implemented.     

Spectroscopic and electrochemical studies on the molecular interaction between copper sulphide nanoparticles and bovine serum albumin

The interaction of covellite hexagonal phase of copper sulphide nanoparticles (CuS NPs) with bovine serum albumin (BSA) was examined systematically by using fluorescence, UV–visible, circular dichroism (CD), Fourier transform infrared (FTIR), dynamic light scattering (DLS) and molecular modelling techniques. Electrochemical method was studied to further confirm the interaction of BSA with CuS NPs. The results of fluorescence studies demonstrated that fluorescence of BSA was quenched by CuS NPs via a static quenching mechanism. The negative values of thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the binding process is spontaneous, exothermic and van der Waals force or hydrogen bonding plays major roles in the interaction of CuS NPs with BSA. The interaction of CuS NPs with Trp residue was established by synchronous studies, and competitive binding studies revealed that Trp-212 of subdomain IIA was involved in the interaction with these nanoparticles. Further, the efficiency of energy transferred and the distance between fluorophore (BSA) and acceptor (CuS NPs) were calculated using Forster’s resonance energy transfer theory. The results of UV–visible, CD, FTIR and DLS revealed that the CuS NPs interact with BSA by inducing the conformational changes in secondary structure and reducing the α-helix content of BSA. Molecular modelling studies suggested that CuS NPs bind to site I of sub domain IIA of BSA. The results of spectroscopic and molecular docking studies were complimented by the electrochemical techniques.