kaCombined effect of volume fractions of nanofillers and filler-polymer interactions on 3D multiscale dispersion of nanofiller and Payne effect

Aceclofenac (ACE) is NSAIDs of a phenyl acetic acid class. It is indicated in arthritis and osteoarthritis, rheumatoid arthritis, ankylosing spondylitis. It has short elimination half life of 4 hours. The objective of the study is to design, characterize and evaluate bioadhesive microspheres of ACE employing carbopol (CP) as bioadhesive polymer. Bioadhesive microspheres of ACE were prepared by solvent evaporation method. The prepared microspheres were free flowing and spherical in shape and characterized for drug loading, mucoadhesion test, infrared spectroscopy (IR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in-vitro release studies were performed using pH 6.8 phosphate buffer. The drug loaded microspheres in a ratio of 1:5 showed 47% of drug entrapment; percentage mucoadhesion was 81% and 89% release in 10 h. The infrared spectra and DSC showed stable character of aceclofenac in the drug loaded microspheres and revealed the absence of drug-polymer interactions. SEM studies showed that the microspheres are spherical and porous in nature. The in vitro release profiles from microspheres of different polymer-drug ratios followed Higuchi model.

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Thermoelectric Generation with Impinging Nano-Jets

Energies ◽

10.3390/en14020492 ◽

2021 ◽

Vol 14 (2) ◽

pp. 492

Author(s):

Fatih Selimefendigil ◽

Hakan F. Oztop ◽

Mikhail A. Sheremet

Keyword(s):

Fluid Dynamics ◽

Power Generation ◽

Computational Fluid Dynamics ◽

Reynolds Number ◽

Conversion Efficiency ◽

Reynolds Numbers ◽

Thermoelectric Generation ◽

Volume Fractions ◽

Water Jets ◽

Conversion Efficiencies

In this study, thermoelectric generation with impinging hot and cold nanofluid jets is considered with computational fluid dynamics by using the finite element method. Highly conductive CNT particles are used in the water jets. Impacts of the Reynolds number of nanojet stream combinations (between (Re1, Re2) = (250, 250) to (1000, 1000)), horizontal distance of the jet inlet from the thermoelectric device (between (r1, r2) = (−0.25, −0.25) to (1.5, 1.5)), impinging jet inlet to target surfaces (between w2 and 4w2) and solid nanoparticle volume fraction (between 0 and 2%) on the interface temperature variations, thermoelectric output power generation and conversion efficiencies are numerically assessed. Higher powers and efficiencies are achieved when the jet stream Reynolds numbers and nanoparticle volume fractions are increased. Generated power and efficiency enhancements 81.5% and 23.8% when lowest and highest Reynolds number combinations are compared. However, the power enhancement with nanojets using highly conductive CNT particles is 14% at the highest solid volume fractions as compared to pure water jet. Impacts of horizontal location of jet inlets affect the power generation and conversion efficiency and 43% variation in the generated power is achieved. Lower values of distances between the jet inlets to the target surface resulted in higher power generation while an optimum value for the highest efficiency is obtained at location zh = 2.5ws. There is 18% enhancement in the conversion efficiency when distances at zh = ws and zh = 2.5ws are compared. Finally, polynomial type regression models are obtained for estimation of generated power and conversion efficiencies for water-jets and nanojets considering various values of jet Reynolds numbers. Accurate predictions are obtained with this modeling approach and it is helpful in assisting the high fidelity computational fluid dynamics simulations results.

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An Intrinsic Material Tailoring Approach for Functionally Graded Axisymmetric Hollow Bodies Under Plane Elasticity

Journal of Elasticity ◽

10.1007/s10659-021-09822-y ◽

2021 ◽

Author(s):

Hassan Mohamed Abdelalim Abdalla ◽

Daniele Casagrande

Keyword(s):

Optimization Problem ◽

Volume Fraction ◽

Minimum Principle ◽

Equivalent Stress ◽

Micromechanical Model ◽

Plane Elasticity ◽

Functionally Graded ◽

Pontryagin Minimum Principle ◽

Volume Fractions ◽

Material Tailoring

AbstractOne of the main requirements in the design of structures made of functionally graded materials is their best response when used in an actual environment. This optimum behaviour may be achieved by searching for the optimal variation of the mechanical and physical properties along which the material compositionally grades. In the works available in the literature, the solution of such an optimization problem usually is obtained by searching for the values of the so called heterogeneity factors (characterizing the expression of the property variations) such that an objective function is minimized. Results, however, do not necessarily guarantee realistic structures and may give rise to unfeasible volume fractions if mapped into a micromechanical model. This paper is motivated by the confidence that a more intrinsic optimization problem should a priori consist in the search for the constituents’ volume fractions rather than tuning parameters for prefixed classes of property variations. Obtaining a solution for such a class of problem requires tools borrowed from dynamic optimization theory. More precisely, herein the so-called Pontryagin Minimum Principle is used, which leads to unexpected results in terms of the derivative of constituents’ volume fractions, regardless of the involved micromechanical model. In particular, along this line of investigation, the optimization problem for axisymmetric bodies subject to internal pressure and for which plane elasticity holds is formulated and analytically solved. The material is assumed to be functionally graded in the radial direction and the goal is to find the gradation that minimizes the maximum equivalent stress. A numerical example on internally pressurized functionally graded cylinders is also performed. The corresponding solution is found to perform better than volume fraction profiles commonly employed in the literature.

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Drug–polymer interactions and their effect on thermoresponsive poly(N-isopropylacrylamide) drug delivery systems

International Journal of Pharmaceutics ◽

10.1016/j.ijpharm.2006.02.005 ◽

2006 ◽

Vol 313 (1-2) ◽

pp. 163-174 ◽

Cited By ~ 86

Author(s):

D COUGHLAN ◽

O CORRIGAN

Keyword(s):

Drug Delivery ◽

Drug Delivery Systems ◽

Delivery Systems ◽

Polymer Interactions

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Correlations of nanoscale film morphologies and topological confinement of three-armed cage block copolymers

Polymer Chemistry ◽

10.1039/d1py00421b ◽

2021 ◽

Author(s):

Brian J. Ree ◽

Yusuke Satoh ◽

Takuya Isono ◽

Toshifumi Satoh

Keyword(s):

Block Copolymers ◽

Volume Fractions ◽

Nanoscale Films

Three-armed cage block copolymers composed of immiscible blocks in near equivalent volume fractions formed topologically controlled sub-10 nm cylindrical and lamellar nanostructures in nanoscale films.

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Turbulence Intensity Modulation by Micropolar Fluids

Fluids ◽

10.3390/fluids6060195 ◽

2021 ◽

Vol 6 (6) ◽

pp. 195

Author(s):

George Sofiadis ◽

Ioannis Sarris

Keyword(s):

Reynolds Number ◽

Turbulence Intensity ◽

Fluid Flows ◽

Turbulent Channel Flow ◽

High Volume ◽

Reynolds Numbers ◽

Intensity Modulation ◽

Wall Turbulence ◽

Volume Fractions ◽

Physical Phenomena

Fluid microstructure nature has a direct effect on turbulence enhancement or attenuation. Certain classes of fluids, such as polymers, tend to reduce turbulence intensity, while others, like dense suspensions, present the opposite results. In this article, we take into consideration the micropolar class of fluids and investigate turbulence intensity modulation for three different Reynolds numbers, as well as different volume fractions of the micropolar density, in a turbulent channel flow. Our findings support that, for low micropolar volume fractions, turbulence presents a monotonic enhancement as the Reynolds number increases. However, on the other hand, for sufficiently high volume fractions, turbulence intensity drops, along with Reynolds number increment. This result is considered to be due to the effect of the micropolar force term on the flow, suppressing near-wall turbulence and enforcing turbulence activity to move further away from the wall. This is the first time that such an observation is made for the class of micropolar fluid flows, and can further assist our understanding of physical phenomena in the more general non-Newtonian flow regime.

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Fully Developed Opposing Mixed Convection Flow in the Inclined Channel Filled with a Hybrid Nanofluid

Nanomaterials ◽

10.3390/nano11051107 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1107

Author(s):

Xiangcheng You ◽

Shiyuan Li

Keyword(s):

Flow Reversal ◽

Convection Flow ◽

Uniform Heat Flux ◽

Hybrid Nanofluid ◽

Type Ii ◽

Inclined Channel ◽

Volume Fractions ◽

Type Iii ◽

Hybrid Nanofluids ◽

Temperature And Pressure

This paper studies the convective heat transfer of a hybrid nanofluid in the inclined channel, whose walls are both heated by the uniform heat flux. The governing ordinary differential equations are made nondimensional and solved analytically, in which explicit distributions of velocity, temperature and pressure are obtained. The effects of flow reversal, wall skin friction and Nusselt number with the hybrid nanofluid depend on the nanoparticle volume fractions and pressure parameters. The obtained results indicate that the nanoparticle volume fractions play a key role in delaying the occurrence of the flow reversal. The hybrid nanofluids hold more delayed range than conventional nanofluids, which is about 2.5 times that of nanofluids. The calculations have been compared with the base fluid, nanofluid and two kinds of hybrid models (type II and type III). The hybrid model of type III is useful and simplified in that it omits the nonlinear terms due to the interaction of different nanoparticle volumetric fractions, with the relative error less than 3%. More results are discussed in the results section below.

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