Effects of ramped wall temperature and concentration on viscoelastic Jeffrey’s fluid flows from a vertical permeable cone

In thermo-fluid dynamics, free convection flows external to different geometries such as cylinders, ellipses, spheres, curved walls, wavy plates, cones etc. play major role in various industrial and process engineering systems. The thermal buoyancy force associated with natural convection flows can exert a critical role in determining skin friction and heat transfer rates at the boundary. In thermal engineering, natural convection flows from cones has gained exceptional interest. A theoretical analysis is developed to investigate the nonlinear, steady-state, laminar, non-isothermal convection boundary layer flows of viscoelastic fluid from a vertical permeable cone with a power-law variation in both temperature and concentration. The Jeffery’s viscoelastic model simulates the non-Newtonian characteristics of polymers, which constitutes the novelty of the present work. The transformed conservation equations for linear momentum, energy and concentration are solved numerically under physically viable boundary conditions using the finite-differences Keller-Box scheme. The impact of Deborah number (De), ratio of relaxation to retardation time (λ), surface suction/injection parameter (fw), power-law exponent (n), buoyancy ratio parameter (N) and dimensionless tangential coordinate (Ѯ) on velocity, surface temperature, concentration, local skin friction, heat transfer rate and mass transfer rate in the boundary layer regime are presented graphically. It is observed that increasing values of De reduces velocity whereas the temperature and concentration are increased slightly. Increasing λ enhance velocity however reduces temperature and concentration slightly. The heat and mass transfer rate are found to decrease with increasing De and increase with increasing values of λ. The skin friction is found to decrease with a rise in De whereas it is elevated with increasing values of λ. Increasing values of fw and n, decelerates the flow and also cools the boundary layer i.e. reduces temperature and also concentration. The study is relevant to chemical engineering systems, solvent and polymeric processes

Network electro-thermal simulation of non-isothermal magnetohydrodynamic heat transfer from a transpiring cone with buoyancy and pressure work

The steady, axisymmetric laminar natural convection boundary layer flow from a non-isothermal vertical circular porous cone under a transverse magnetic field, with the cone vertex located at the base, is considered. The pressure work effect is included in the analysis. The governing boundary layer equations are formulated in an (x,y) coordinate system (parallel and normal to the cone slant surface), and the magnetic field effects are simulated with a hydromagnetic body force term in the momentum equation. A dimensionless transformation is performed rendering the momentum and also heat conservation equations. The thermal convection flow is shown to be controlled by six thermophysical parameters- local Hartmann number, local Grashof number, pressure work parameter, temperature power law exponent, Prandtl number and the transpiration parameter. The transformed parabolic partial differential equations are solved numerically using the Network Simulation Method (NSM) based on the electrical-thermodynamic analogy. Excellent correlation of the zero Hartmann number case is achieved with earlier electrically non-conducting solutions. Local shear stress function (skin friction) is found to be strongly decreased with an increase in Prandtl number (Pr), with negative values (corresponding to flow reversal) identified for highest Pr with further distance along the streamwise direction. A rise in local Hartmann number, is observed to depress skin friction. Increasing temperature power law index, corresponding to steeper temperature gradient at the wall, strongly reduces skin friction at the cone surface. A positive rise in pressure work parameter decreases skin friction whereas a negative increase elevates the skin friction for some distance along the cone surface from the apex. Local heat transfer gradient is markedly boosted with a rise in Prandtl number but decreased principally at the cone surface with increasing local Hartmann number. Increasing temperature power law index conversely increases the local heat transfer gradient, at the cone surface. A positive rise in pressure work parameter increases local heat transfer gradient while negative causes it to decrease. A rise in local Grashof number boosts local skin friction and velocity into the boundary layer; local heat transfer gradient is also increased with a rise in local Grashof number whereas the temperature in the boundary layer is noticeably reduced. Applications of the work arise in spacecraft magnetogas dynamics, chemical cooling systems and industrial magnetic materials processing

Epigenetic polypharmacology: from combination therapy to multitargeted drugs

The modern drug discovery process has largely focused its attention in the so-called magic bullets, single chemical entities that exhibit high selectivity and potency for a particular target. This approach was based on the assumption that the deregulation of a protein was causally linked to a disease state, and the pharmacological intervention through inhibition of the deregulated target was able to restore normal cell function. However, the use of cocktails or multicomponent drugs to address several targets simultaneously is also popular to treat multifactorial diseases such as cancer and neurological disorders. We review the state of the art with such combinations that have an epigenetic target as one of their mechanisms of action. Epigenetic drug discovery is a rapidly advancing field, and drugs targeting epigenetic enzymes are in the clinic for the treatment of hematological cancers. Approved and experimental epigenetic drugs are undergoing clinical trials in combination with other therapeutic agents via fused or linked pharmacophores in order to benefit from synergistic effects of polypharmacology. In addition, ligands are being discovered which, as single chemical entities, are able to modulate multiple epigenetic targets simultaneously (multitarget epigenetic drugs). These multiple ligands should in principle have a lower risk of drug-drug interactions and drug resistance compared to cocktails or multicomponent drugs. This new generation may rival the so-called magic bullets in the treatment of diseases that arise as a consequence of the deregulation of multiple signaling pathways provided the challenge of optimization of the activities shown by the pharmacophores with the different targets is addressed