Investigating the influence of temperature-dependent rheological properties on nanofluid behavior in heat transfer

Nanofluids are advanced heat transfer fluids whose performance is influenced by various thermo-physical properties, including nanoparticle volume fraction, base fluid, and temperature. Rheological mathematical models have been established by using empirical data in order to characterize these features as dependent on parameters such as volume fraction, base fluid composition, and temperature. These models have been integrated into transport equations. Nanofluids composed of metallic oxides (Al2O3, SiO2) and carbon nanostructures (PEG-GnP, PEG-TGr) dispersed in deionized H2O, with nanoparticle concentrations ranging from 0.025% to 0.1%, and temperatures between 30 °C and 50 °C, were utilized to investigate flow over thin needle. The rheological models contained transport equations include the partial differential equations. The transport equations were simplified through various transformations and then solved numerically. The results in form of velocity and temperature distributions were obtained, along with boundary layer parameters, Nusselt number and coefficient of skin friction. The present study contributes to the existing knowledge by elucidating the intricate relationship between nanoparticle volume fraction, base fluid properties, and temperature in nanofluid behavior.

Unraveling the nature of nano-diamonds and silica in a catheterized tapered artery: highlights into hydrophilic traits

In this work, we observe the behavior of a hybrid nanofluidic model containing nanodiamonds and silica nanoparticles. The nanofluid propagates through a catheterized tapered artery with three distinct configurations: converging tapered, non-tapered and diverging tapered arteries. In order to assess the rheological properties of the blood, the third-grade non-Newtonian fluid is employed in the flow model such that the Newtonian versus non-Newtonian effects are revealed. The system of equations governing the flow is modeled under magnetic field and with heat transfer, then solved in a closed form using the perturbation approach for the pertinent parameters. The interpretations of the physical variables of interest, such as the velocity, temperature and wall shear stress, are explained. The integration of diamonds and silica nanoparticles give rise to diverse of biological applications since they are used in the drug delivery and biological imaging in genetic materials due to their hydrophilic surfaces. The present mathematical analysis lays a solid foundation on possible therapeutic applications in biomedicine.

Entropy Generation and Radiation Analysis on Peristaltic Transport of Hyperbolic Tangent Fluid with Hybrid Nanoparticle Through an Endoscope

The current study explores the impact of entropy generation, thermal jump, radiation, and inclined magnetic field on the peristaltic transport of hyperbolic tangent fluid containing molybdenum disulfide and silver nanoparticles through an endoscope with a long wavelength and low Reynolds number assumptions. Between two coaxial tubes, a non-Newtonian hyperbolic tangent fluid with silver nanoparticles is considered. The Second law of thermodynamics is used to examine the entropy generation. The Homotopy perturbation method (HPM) is applied to describe the solution of nonlinear partial differential equations. We were able to arrive at analytical solutions for velocity, temperature, and nanoparticle concentration. In the end, the impact of various physical parameters on temperature, nanoparticle concentration, velocity, entropy generation, and Bejan number was graphically depicted. The significant outcome of the present study is that the impact of Hartmann number and Brownian motion parameter declines the velocity profile, but the thermal Grashoff number enhances velocity, whereas Platelet-shaped nanoparticles achieve a higher speed as compare to Spherical-shaped nanoparticles.

Cilia-assisted flow of viscoelastic fluid in a divergent channel under porosity effects

Cilia-driven laminar flow of an incompressible viscoelastic fluid in a divergent channel has been conducted numerically using the BVP4C technique. The non-Newtonian Jeffrey rheological model is utilized to characterize the fluid. The flow equations are formulated in a curvilinear coordinate system, and the porosity effects are simulated with a body force term in the Navier-Stokes equation. The flow equations are transformed into a wave frame from a fixed frame of reference using a linear mathematical relationship. A biological approximation of creeping phenomena and the long-wavelength assumption is used in the flow analysis. The flow analysis is carried out by using a complex (wavy) propulsion of cilia beating. The two-dimensional flow is controlled by physical parameters-Darcy's number, curvature parameter, viscoelastic parameter, phase difference, cilia length, and divergent parameter. They also examined the ciliated pumping and bolus trapping in their flow analysis. The boundary layer phenomena in the velocity profile are noticed under more significant porosity and time relaxation effects. The bolus circulations are reduced for a larger porosity medium and larger numeric values of the time relaxation parameter.

New Insight into AuNP Applications in Tumour Treatment and Cosmetics through Wavy Annuli at the Nanoscale

The purpose of this study is to probe the peristaltic propulsion of a non-Newtonian fluid model with suspended gold nanoparticles. The base fluid is considered to simulate blood using the Carreau fluid model. We model a small annulus as a tube with a peristaltic wave containing a clot propagating towards the tube wall. An external variable magnetic field is also considered in the governing flow. An approximation for long wavelengths and small Reynolds numbers is employed to formulate the governing flow problem. The resulting nonlinear equations are solved using a perturbation scheme. Series solutions are obtained for the velocity profile, temperature profile, pressure rise and streamlines. The results indicate an enhancement in the temperature profile that can be utilized in eradicating tumour cells.

Interaction between blood and solid particles propagating through a capillary with slip effects

This article describes the interaction between solid particles and blood propagating through a capillary. A slip condition is considered on the walls of the capillary. The rheological features of the blood are discussed by considering as a two-phase Newtonian fluid model, i.e., the suspension of cells in plasma. A perturbation method is successfully applied to obtain the series solution of the governing coupled differential equations. The series solution for both fluid and particle phase are presented up to second order approximation. The expressions for the velocity and pressure distributions under slip effects are determined within a tube. Furthermore, the current results are beneficial to understand the rheological features of blood which will be helpful to interpret and analyze more complex blood flow models.

Heat transfer analysis on peristaltically induced motion of particle-fluid suspension with variable viscosity: Clot blood model

In this article, heat transfer analysis on clot blood model of the particle-fluid suspension through a non-uniform annulus has been investigated. The blood propagating along the whole length of the annulus was induced by peristaltic motion. The effects of variable viscosity and slip condition are also taken into account. The governing flow problem is modeled using lubrication approach by taking the assumption of long wavelength and creeping flow regime. The resulting equation for fluid phase and particle phase is solved analytically and closed form solutions are obtained. The physical impact of all the emerging parameters is discussed mathematically and graphically. Particularly, we considered the effects of particle volume fraction, slip parameter, the maximum height of clot, viscosity parameter, average volume flow rate, Prandtl number, Eckert number and fluid parameter on temperature profile, pressure rise and friction forces for outer and inner tube. Numerical computations have been used to determine the behavior of pressure rise and friction along the whole length of the annulus. The present study is also presented for an endoscope as a special case of our study. It is observed that greater influence of clot tends to rise the pressure rise significantly. It is also found that temperature profile increases due to the enhancement in Prandtl number, Eckert number, and fluid parameter. The present study reveals that friction forces for outer tube have higher magnitude as compared to the friction forces for an inner tube. In fact, the results for present study can also be reduced to the Newtonian fluid by taking ζ → ∞.

Simultaneous effects of coagulation and variable magnetic field on peristaltically induced motion of Jeffrey nanofluid containing gyrotactic microorganism

In this article, simultaneous effects of coagulation (blood clot) and variable magnetic field on peristaltically induced motion of non-Newtonian Jeffrey nanofluid containing gyrotactic microorganism through an annulus have been studied. The effects of an endoscope also taken into consideration in our study as a special case. The governing flow problem is simplified by taking the approximation of long wavelength and creeping flow regime. The resulting highly coupled differential equations are solved analytically with the help of perturbation method and series solution have been presented up to second order approximation. The impact of all the sundry parameters is discussed for velocity profile, temperature profile, nanoparticle concentration profile, motile microorganism density profile, pressure rise and friction forces. Moreover, numerical integration is also used to evaluate the expressions for pressure rise and friction forces for outer tube and inner tube. It is found that velocity of a fluid diminishes near the walls due to the increment in the height of clot. However, the influence of magnetic field depicts opposite behavior near the walls.

Simultaneous determination of phenytoin, carbamazepine, and 10,11-carbamazepine epoxide in human plasma by high-performance liquid chromatography with ultraviolet detection

The Bioanalytical Chemistry Department at the Madison facility of Covance Laboratories, has developed and validated a simple and sensitive method for the simultaneous determination of phenytoin (PHT), carbamazepine (CBZ) and 10,11-carbamazepine epoxide (CBZ-E) in human plasma by high-performance liquid chromatography with 10,11 dihydrocarbamazepine as the internal standard. Acetonitrile was added to plasma samples containing PHT, CBZ and CBZ-E to precipitate the plasma proteins. After centrifugation, the acetonitrile supernatant was transferred to a clean tube and evaporated under N2. The dried sample extract was reconstituted in 0.4 ml of mobile phase and injected for analysis by high-performance liquid chromatography. Separation was achieved on a Spherisorb ODS2 analytical column with a mobile phase of 18:18:70 acetonitrile:methanol:potassium phosphate buffer. Detection was at 210 nm using an ultraviolet detector. The mean retention times of CBZ-E, PHT and CBZ were 5.8, 9.9 and 11.8 min, respectively. Peak height ratios were fit to a least squares linear regression algorithm with a 1/(concentration)2 weighting. The method produces acceptable linearity, precision and accuracy to a minimum concentration of 0.050 micrograms ml-1 in human plasma. It is also simple and convenient, with no observable matrix interferences.

Pharmacokinetics of the enantiomers of verapamil after intravenous and oral administration of racemic verapamil in a rat model

Verapamil is a chiral calcium channel blocking drug which is useful clinically as the racemate in treating hypertension and arrhythmia. The published pharmacokinetic data for verapamil enantiomers in the rat model are limited. Utilizing a stereospecific high-performance liquid chromatographic (HPLC) assay, the enantiomeric disposition of verapamil is reported after intravenous (1.0 mg kg-1) and oral (10 mg kg-1) administration of racemic verapamil to the rat model. After intravenous administration the systemic clearance of R-verapamil was significantly greater than that of S-verapamil; 34.9 +/- 7 against 23.7 +/- 3.7 mL min-1 kg-1 (mean +/- SD), respectively. After oral administration, the clearance of R-verapamil was significantly greater than that of S-verapamil, 889 +/- 294 against 351 +/- 109 mL min-1 kg-1, respectively. The apparent oral bioavailability of S-verapamil was greater than that of R-verapamil, 0.074 +/- 0.031 against 0.041 +/- 0.011, respectively. These data suggest that the disposition of verapamil in the rat is stereoselective; verapamil undergoes extensive stereoselective first-pass clearance after oral administration and the direction of stereoselectivity in plasma is opposite to that observed in the human.

Pharmacokinetics of verapamil and norverapamil enantiomers after administration of immediate and controlled-release formulations to humans:evidence suggesting input-rate determined stereoselectivity

Verapamil is a racemic calcium channel-blocking drug that undergoes extensive hepatic first-pass metabolism to an active metabolite, norverapamil. The enantiomers of verapamil and norverapamil have differing negative inotropic, chronotropic, and dromotropic activities and differing effects on vascular smooth muscles; the S-enantiomers having greater activity. It is hypothesized that the R/S concentration ratio of verapamil enantiomers may be input-rate dependent. The pharmacokinetics of verapamil and norverapamil enantiomers were studied in 11 young, healthy male and female volunteers after oral administration of 80 mg immediate-release (IR) verapamil every 8 hours, and a 240 mg dose once daily of controlled-release (CR) formulation on two separate occasions. Both dosage regimens were continued for 1 week with a minimum 1-week period between the two drug treatments. After the last dose of each regimen, plasma samples were collected over the period corresponding to the dosing interval. Enantiomer concentrations were determined using a microwave-facilitated precolumn derivatization with high performance liquid chromatographic quantification. Stereospecific assay revealed that: (1) stereoselective R- and S-enantiomer disposition occurred regardless of formulation administered; (2) a trend of R:S concentration ratios of verapamil differed between the two formulations; and (3) fluctuations between Cmax and Cmin values of the two formulations were statistically different over respective dosing intervals (greater fluctuation after CR administration). Using nonstereospecific data analyses, however, the pharmacokinetic parameters for verapamil and norverapamil were similar for both formulations over a 24-hour period. We suggest that kinetic differences can be attributed to differences in release rates of drug from the tablet matrices. The relative bioavailabilities of verapamil and norverapamil from the two products may, therefore, be subject to input rate-dependent processes.

Stereospecific high-performance liquid chromatographic assay of metoprolol

A valid, sensitive high-performance liquid chromatographic technique is reported for the separation of the two enantiomers of metoprolol in human plasma. The procedure involves pre-column derivatization with the homochiral reagent S-(+)-1-(1-naphthyl)ethyl isocyanate. Once formed, the diastereomers are separated using normal-phase high-performance liquid chromatography. Fluorescence detection (220 nm excitation; no emission filter) was utilized, resulting in baseline resolution (Rs greater than 1.5). The peaks corresponding to metoprolol enantiomers were free from interference throughout the examined range of 5-500 ng/ml; accuracy and precision were within approximately 10%. Analysis of a plasma sample collected from a healthy volunteer demonstrated that the assay is applicable to clinical studies.