The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
Tasawar Hayat - One of the best experts on this subject based on the ideXlab platform.
-
nonlinear convection and joule heating impacts in magneto thixotropic nanofluid stratified flow by convectively heated variable thicked surface
Journal of Molecular Liquids, 2020Co-Authors: Muhammad Waqas, S A Shehzad, Tasawar Hayat, Ijaz M Khan, A S Dogonchi, A AlsaediAbstract:Abstract The modeling of magnetohydrodynamic (MHD) nonlinear convected flow of thixotropic non-Newtonian material is carried out in this piece of research. The aspects of Joule dissipation, heat generation and thermal radiation are considered to analyze the heat transportation analysis. The combination of stratified and convective conditions phenomenon is accounted first time. The model non-dimensional quantities are calculated with the help of optimal homotopy procedure. The optimal values of non-zero auxiliary constraints are calculated and visualized. We observed that the increasing values of radiation, Eckert and Biot numbers lead to higher profile of temperature and stronger thickness of temperature boundary-layer. Further, presence of thermophoretic and Brownian Movement factors have opposite nature for nanomaterials concentration.
-
entropy generation minimization and binary chemical reaction with arrhenius activation energy in mhd radiative flow of nanomaterial
Journal of Molecular Liquids, 2018Co-Authors: Muhammad Ijaz Khan, Tasawar Hayat, Muhammad Imran Khan, M Waqas, Sumaira Qayyum, Ahmed AlsaediAbstract:Abstract Our aim here is to investigate the MHD radiative nanomaterial flow of Casson fluid towards a stretched surface. Heat transport mechanism is examined through thermal radiation and heat source/sink. Entropy generation is explored as a function of concentration, temperature and velocity. Total entropy generation rate is inspected for various flow parameters. Impacts of Brownian Movement and thermophoresis on entropy generation have been also scrutinized. Nanofluid model with Brownian motion and thermophoresis mechanisms are analyzed. Additionally, activation energy and chemical reaction are also implemented. Governing flow expressions consist of momentum, energy and concentration of nanoparticles. Appropriate similarity transformations are utilized to convert the flow expressions to ordinary ones. The obtaining coupled nonlinear differential equations have been tackled with the help of BPV4c. Attention is particularly given to the entropy generation and Bejan number. The graphical outcomes are discussed for velocity, concentration, temperature, entropy generation and Bejan number. From graphical outcomes, it is examined that velocity and temperature fields show contrast behavior for higher magnetic variable. It is found that radiative variable increases the effective thermal diffusivity and temperature enhances. To our knowledge the flow of nanomaterial with entropy generation minimization and activation energy is just investigated in this paper.
-
modeling and analyzing flow of third grade nanofluid due to rotating stretchable disk with chemical reaction and heat source
Physica B-condensed Matter, 2018Co-Authors: Tasawar Hayat, Salman Ahmad, Ijaz M Khan, Ahmed AlsaediAbstract:Abstract This article addresses flow of third grade nanofluid due to stretchable rotating disk. Mass and heat transports are analyzed through thermophoresis and Brownian Movement effects. Further the effects of heat generation and chemical reaction are also accounted. The obtained ODE's are tackled computationally by means of homotopy analysis method. Graphical outcomes are analyzed for the effects of different variables. The obtained results show that velocity reduces through Reynolds number and material parameters. Temperature and concentration increase with Brownian motion and these decrease by Reynolds number.
-
entropy generation minimization egm in nonlinear mixed convective flow of nanomaterial with joule heating and slip condition
Journal of Molecular Liquids, 2018Co-Authors: Muhammad Ijaz Khan, Tasawar Hayat, Muhammad Waqas, Muhammad Imran Khan, A AlsaediAbstract:Abstract Main emphasis here is to investigate the novel characteristics of entropy generation in nonlinear mixed convective flow of nanofluid between two stretchable rotating disks. Buongiorno nanofluid model of nanomaterial is implemented in mathematical modeling. Nanofluid aspects for thermophoresis and Brownian Movement are considered. Heat transport mechanism is examined subject to convective condition and Joule heating. Velocity slip is considered at the lower and upper disks. Total entropy generation rate is discussed. Systems of PDEs is first converted into ODEs and then tackled by for convergent solutions. The impacts of Reynold number, Prandtl number, Hartman number, velocity slip parameter, Biot numbers of heat and mass transfer, thermophoresis, Brownian motion, nonlinear convection parameters for temperature and concentration, mixed convection parameter and Schmidt number on velocities, temperature, Bejan number, concentration and total entropy generation rate are graphically examined. Our investigation reveal that entropy generation rate and Bejan number have inverse behavior for higher estimation of Hartman number. Moreover velocity and temperature gradients are physically interpreted.
Hartmu Kutha - One of the best experts on this subject based on the ideXlab platform.
-
a mathematical model of single target site location by Brownian Movement in subcellular compartments
Journal of Theoretical Biology, 2003Co-Authors: Hartmu KuthaAbstract:Abstract The location of distinct sites is mandatory for many cellular processes. In the subcompartments of the cell nucleus, only very small numbers of diffusing macromolecules and specific target sites of some types may be present. In this case, we are faced with the Brownian Movement of individual macromolecules and their “random search” forsingle/few specific target sites, rather than bulk-averaged diffusion and multiple sites. In this article, I consider the location of a distant central target site, e.g. a globular protein, by individual macromolecules executing unbiased (i.e. drift-free) random walks in a spherical compartment. For this walk-and-capture model, the closed-form analytic solution of the first passage time probability density function (p.d.f.) has been obtained as well as the first and second moment. In the limit of a large ratio of the radii of the spherical diffusion space and central target, well-known relations for the variance and the first two moments for the exponential p.d.f. were found to hold with high accuracy. These calculations reinforce earlier numerical results and Monte Carlo simulations. A major implication derivable from the model is that non-directed random Movement is an effective means for locating single sites in submicron-sized compartments, even when the diffusion coefficients are comparatively small and the diffusing species are present in one copy only. These theoretical conclusions are underscored numerically for effective diffusion constants ranging from 0.5 to 10.0 μm2 s−1, which have been reported for a couple of nuclear proteins in their physiological environment. Spherical compartments of submicron size are, for example, the Cajal bodies (size: 0.1–1.0 μm), which are present in 1–5 copies in the cell nucleus. Within a small Cajal body of radius 0.1 μm a single diffusing protein molecule (with D=0.5 μm2 s−1) would encounter a medium-sized protein of radius 2.5 nm within 1 s with a probability near certainty (p=0.98).
Efstathios E Michaelides - One of the best experts on this subject based on the ideXlab platform.
-
wall effects on the Brownian Movement thermophoresis and deposition of nanoparticles in liquids
Journal of Fluids Engineering-transactions of The Asme, 2016Co-Authors: Efstathios E MichaelidesAbstract:It is well known that the hydrodynamic drag on particles is significantly enhanced close to a plane or curved boundary. This enhancement impedes the Movement of the particles in both the parallel and the normal directions with respect to the wall. In the presence of a temperature gradient, the Brownian Movement of particles induces the phenomenon of thermophoresis, which results in the steady motion of the particles toward the colder domains of the flow field. This paper examines the effect of the enhanced wall drag on the thermophoretic Movement of the nanoparticles in a Newtonian fluid, at short distances (0–10 radii) from a flat, horizontal wall. The effect of the flow shear lift on the thermophoretic motion of the particles close to a horizontal wall is also examined. It is observed that the Movement of the particles toward the plane wall is significantly retarded because of the enhanced drag and that it, actually, causes particle accumulation close to the plane wall. It is also observed that the lift, which is induced by the relative Brownian Movement, does not have an effect on the average motion of particles toward the wall and does not play an important role on the deposition of particles.
-
Brownian Movement and thermophoresis of nanoparticles in liquids
International Journal of Heat and Mass Transfer, 2015Co-Authors: Efstathios E MichaelidesAbstract:Abstract Thermophoresis is the realization of the averaged Brownian motion of particles in a fluid, which is subject to a steady temperature gradient. At sufficiently long times, the stronger molecular impulses in the hotter fluid region drive particles towards the colder region, where the molecular impulses are weaker. The effect of the molecular impulses on the particles is described by a stochastic Brownian force. When this force is applied to an ensemble of particles the thermophoretic velocity is the average velocity of the ensemble. In this study the motion of an ensemble of 4000 spherical nanoparticles with the material properties of CNT, aluminum, aluminum oxide, copper and gold was simulated in four base liquids–water, ethyl glycol, engine oil and R134a. The ensemble-averaged results generate the thermophoretic velocity of these particles in the base liquids. It was observed that the computational results agree very well with the few experimental data available for liquids. The computational method is general and may be applied to all heterogeneous systems of nanoparticles in liquids. The numerical results yield very useful information on the process of thermophoresis in liquids as well as values of the thermophoretic coefficients in nanofluids.
Meunier, Frédéric A. - One of the best experts on this subject based on the ideXlab platform.
-
Need for speed: Super-resolving the dynamic nanoclustering of syntaxin-1 at exocytic fusion sites
'Elsevier BV', 2020Co-Authors: Padmanabha Pranesh, Ademosi, Adekunle T., Kasula Ravikira, Lauwers Elsa, Verstreke Patrik, Meunier, Frédéric A.Abstract:Communication between cells relies on regulated exocytosis, a multi-step process that involves the docking, priming and fusion of vesicles with the plasma membrane, culminating in the release of neurotransmitters and hormones. Key proteins and lipids involved in exocytosis are subjected to Brownian Movement and constantly switch between distinct motion states which are governed by short-lived molecular interactions. Critical biochemical reactions between exocytic proteins that occur in the confinement of nanodomains underpin the precise sequence of priming steps which leads to the fusion of vesicles. The advent of super-resolution microscopy techniques has provided the means to visualize individual molecules on the plasma membrane with high spatiotemporal resolution in live cells. These techniques are revealing a highly dynamic nature of the nanoscale organization of the exocytic machinery. In this review, we focus on soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) syntaxin-1, which mediates vesicular fusion. Syntaxin-1 is highly mobile at the plasma membrane, and its inherent speed allows fast assembly and disassembly of syntaxin-1 nanoclusters which are associated with exocytosis. We reflect on recent studies which have revealed the mechanisms regulating syntaxin-1 nanoclustering on the plasma membrane and draw inferences on the effect of synaptic activity, phosphoinositides, N-ethylmaleimide-sensitive factor (NSF), α-soluble NSF attachment protein (α-SNAP) and SNARE complex assembly on the dynamic nanoscale organization of syntaxin-1. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.status: publishe
-
Need for speed: Super-resolving the dynamic nanoclustering of syntaxin-1 at exocytic fusion sites
'Elsevier BV', 2019Co-Authors: Padmanabha Pranesh, Ademosi, Adekunle T., Kasula Ravikira, Lauwers Elsa, Verstreke Patrik, Meunier, Frédéric A.Abstract:Communication between cells relies on regulated exocytosis, a multi-step process that involves the docking, priming and fusion of vesicles with the plasma membrane, culminating in the release of neurotransmitters and hormones. Key proteins and lipids involved in exocytosis are subjected to Brownian Movement and constantly switch between distinct motion states which are governed by short-lived molecular interactions. Critical biochemical reactions between exocytic proteins that occur in the confinement of nanodomains underpin the precise sequence of priming steps which leads to the fusion of vesicles. The advent of super-resolution microscopy techniques has provided the means to visualize individual molecules on the plasma membrane with high spatiotemporal resolution in live cells. These techniques are revealing a highly dynamic nature of the nanoscale organization of the exocytic machinery. In this review, we focus on soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) syntaxin-1, which mediates vesicular fusion. Syntaxin-1 is highly mobile at the plasma membrane, and its inherent speed allows fast assembly and disassembly of syntaxin-1 nanoclusters which are associated with exocytosis. We reflect on recent studies which have revealed the mechanisms regulating syntaxin-1 nanoclustering on the plasma membrane and draw inferences on the effect of synaptic activity, phosphoinositides, N-ethylmaleimide-sensitive factor (NSF), α-soluble NSF attachment protein (α-SNAP) and SNARE complex assembly on the dynamic nanoscale organization of syntaxin-1
Sudipto Ghosh - One of the best experts on this subject based on the ideXlab platform.
-
on the phononic and electronic contribution to the enhanced thermal conductivity of water based silver nanofluids
International Journal of Thermal Sciences, 2013Co-Authors: V Karthik, Seshadev Sahoo, Shaymal K. Pabi, Sudipto GhoshAbstract:Abstract Nanofluids often exhibit significantly higher thermal conductivity compared to the base fluid. Contributions of the phononic and electronic thermal transport between a heat source and frequently colliding nanoparticles to the enhanced thermal conductivity have been investigated for the first time, through multi-scale modeling. Classical molecular dynamics (MD) model has been used to estimate the phononic component of thermal transport from the heat source to colliding nanoparticles. A meso-continuum model has been used to estimate the same as well as the thermal transport from heat source to colliding nanoparticle due to the combined effect of phononic and electronic mechanisms. The data on thermal pickup by colliding nanoparticles from the heat source, obtained by rationally combining the predictions of MD and meso-continuum approach, have been fed to a higher length scale stochastic model to estimate the enhancement in the conductivity. The stochastic model keeps track of Brownian Movement of nanoparticles within the base fluid and the convective heat dissipation of the absorbed thermal energy of the nanoparticles to the surrounding fluid. The present multi-scale model estimates ∼74% thermal conductivity enhancement in water-based silver nanofluid (0.1 vol%) having nanoparticles in the size range of 4–30 nm, and the results are in reasonable agreement with the experimental results reported in the literatures.
