Cylindrical Nanoparticles Research Articles

Effective thermal conductivity of nanostructures: A review

We present a synthesis of recent results on thermal heat conductivity in nano-composites and nano-structures. The model is a mixt of the Effective Medium Approximation (EMA) and Extended Irreversible Thermodynamics (EXIT). The latter is particularly well adapted to the description of small scaled systems and will be used to derive the expression of the thermal conductivity of nanoparticles. The model is applied to spherical, cylindrical (nanowires) and porous nanoparticles, respectively, being embedded in host media, like polymeric matrices and semi-conductors. Good agreement is observed with other models, experimental data and Monte-Carlo simulations.

Significance of Temperature Dependent Viscosity, Nonlinear Thermal Radiation and Viscous Dissipation on the Dynamics of Water Conveying Cylindrical and Brick Shaped Molybdenum Disulphide Nanoparticles

In this study, the problem of heat transfer in the transport phenomenon of water conveying molybdenum disulphide nanoparticles is presented. The flow takes place over a flat plate along with nonlinear thermal radiation, viscous dissipation and variable viscosity influence. The governing model is simplified as ordinary differential equations with the help of bunch of similarity transformations. Simplified model is treated numerically using Runge–Kutta–Fehlberg fourth fifth order technique for the solution. The influence of related parameters and their physical resultant interpretations are presented and discussed in detail. It is found that, the heat transfer augmentation is more for cylinder shape nanoparticle than brick shape. Moreover, it is obtained that, heat transfer phenomena is more significant for nonlinear thermal radiation. Furthermore, enhancement of heat transfer rate is seen due to the impact of viscous dissipation and temperature ratio parameter.

Stimulated Low-Frequency Scattering of Light in an Aqueous Suspension of the Tobacco Mosaic Virus

Stimulated low-frequency scattering of light by aqueous suspensions of the tobacco mosaic virus with the scattering frequency depending on the concentration of the virus is observed for the first time. For concentrations of ∼1 × 1012 and ∼2 × 1012 cm–3, the Stokes components of scattered light are shifted by ∼43.99 and ∼31.08 GHz, respectively. At the same time, the competing process of stimulated Brillouin scattering in these heterogeneous media is suppressed. The theory of stimulated emission resulting from normal-mode vibrations of solvent-molecule-loaded cylindrical nanoparticles driven by ponderomotive forces in the field of two copropagating pump electromagnetic waves is developed for the first time. The theoretically estimated frequency shift of the Stokes component is ∼50 GHz, which agrees with the experimental result. It remains unclear why a decrease in the thickness of the liquid layer with a simultaneous increase in concentration selectively favors a decrease in the frequency of coherent normal-mode vibrations of the virus participating in stimulated low-frequency scattering.

Photostable Helical Polyfurans

This report describes the design and synthesis of a new class of polyfurans bearing ester side chains. The macromolecules can be synthesized using catalyst-transfer polycondensation, providing precise control over molecular weight and molecular weight distribution. Such obtained furan ester polymers are significantly more photostable than their alkyl analogues owing to the electron-withdrawing nature of the attached subunit. Most interestingly, they spontaneously fold into a compact π-stacked helix, yielding a complex multilayer cylindrical nanoparticle with a hollow, rigid, conjugated core composed of the polyfuran backbone and a soft, insulating outer layer formed by the ester side chains. The length of polymer side chains dictates the outer diameter of such nanoparticles, which for the hexyl ester groups used in the present study is equal to ∼2.3 nm. The inner cavity of the conjugated core is lined with oxygen atoms, which set its effective diameter to 0.4 nm. Furthermore, installation of bulkier, branched chiral ester side chains on the repeat unit yields structures that, upon change of solvent, can reversibly transition between an ordered chiral helical folded and disordered unfolded state.

Study of slow light in a composite consisting of core-shell cylindrical nanoparticles doped in a dielectric

Study of slow light in a composite consisting of core-shell cylindrical nanoparticles doped in a dielectric

The Effect of the Liquid Layer Around the Spherical and Cylindrical Nanoparticles in Enhancing Thermal Conductivity of Nanofluids

In this work, the equilibrium molecular dynamics (MD) simulation combined with the Green–Kubo method is employed to calculate the thermal conductivity and investigate the impact of the liquid layer around the solid nanoparticle (NP) in enhancing thermal conductivity of nanofluid (argon–copper), which contains the liquid argon as a base fluid surrounding the spherical or cylindrical NPs of copper. First, the thermal conductivity is calculated at temperatures 85, 85.5, 86, and 86.5 K and for different volume fractions ranging from 4.33% to 11.35%. Second, the number ΔN of argon atoms is counted in the liquid layer formed at the solid–liquid interface with the thickness of Δr = 0.3 nm around the NP. Finally, the number density n of argon atoms in this layer formed is calculated in all cases. Also, the results for spherical and cylindrical NPs are compared with one another. It is observed that the thermal conductivity of the nanofluid increased with the increasing volume fraction and the number ΔN. Likewise, the thermal conductivity of nanofluid containing spherical NPs is higher than that of nanofluid containing cylindrical NPs. Furthermore, the number density n of argon atoms near the surface of spherical NPs is higher than that of argon atoms attached in the curved surface of cylindrical NPs. As a result, the liquid layer around the solid NP has been considered one of the mechanisms responsible contributing to the thermal conductivity enhancement in nanofluids.

Hydrothermal analysis of turbulent boehmite alumina nanofluid flow with different nanoparticle shapes in a minichannel heat exchanger using two-phase mixture model

Exploring the effect of nanoparticle shape on the fluid flow characteristics of boehmite alumina nanofluid in a horizontal double-pipe minichannel heat exchanger is the goal of this study. The proposed boehmite alumina nanofluid could consist of dispersed cylindrical, brick, blade, platelet, and spherical shape nanoparticles in a mixture of water/ethylene glycol. In this study, the water and nanofluid pass through the annulus and tube side of the heat exchanger, respectively. To accurately simulate the behavior of nanofluid, the two phase mixture model is utilized in the simulation. In this investigation, the effect of different Reynolds numbers, nanoparticle concentrations and shapes versus important hydrothermal properties are investigated. The results show that, the spherical and platelet shape lead to the highest and lowest performance index of heat exchanger, respectively. Moreover, it is found that the rates of heat transfer, overall heat transfer coefficient, pressure drop, and pumping power increases with increase in Reynolds number and nanoparticle concentration, while the opposite trend is observed for performance index of the heat exchanger. For instance, at the Reynolds number of 20000, by boosting the nanoparticle concentration from 0.5 to 2%, the performance index for nanofluid containing platelet shape and spherical shape nanoparticles reduces by 130.63 and 3.88%, respectively.

Polarization control of colors in resonant evanescent field scattering by silicon nanodisks [Invited

Using the multipole decomposition method, we study resonant evanescent field scattering by cylindrical silicon nanoparticles illuminated in the total internal reflection configuration. Scattering cross sections of nanodisks in the visible spectral range are considered, and the corresponding color representations of scattered radiation under white light illumination are simulated. It is demonstrated that the scattered light color can efficiently be controlled and tuned by the incident light polarization, with the relative contributions of nanodisk multipole moments playing a crucial role in the color formation. The polarization color control in resonant scattering by silicon nanodisks with different aspect ratios is studied in detail. The results obtained suggest new avenues for and exciting prospects in the development of color printing and multicolor displays operating on the basis of all-dielectric nanostructures.

Optical Absorption of Plasmonic Cylindrical Gold Nanoparticle in Hexagonal Geometry

A high quality solar cell depends on how good the design of the solar cell can absorb light. In this study, cylindrical gold nanoparticles were embedded into indium tin oxide (ITO) layer and silicon layer arranged in hexagonal geometry on plasmonic solar cell simulation design. The aim is to investigate the optical absorption percentage in terms of wavelength and angle of incidence for the solar cell design. The numerical results showed that the highest absorption has occurred in 480 nm in the range of visible spectrum. In this wavelength, the highest absorption occurred at the incidence angle of 48 degree.

Flow and Heat Transfer in Nanofluid Flow through a Cylinder Filled with Foam Porous Medium under Radial Injection

The Darcy flow and heat convection in nanofluid through a cylinder filled with a foam porous medium subject to local non-thermal equilibrium (LNTE) condition and uniform radial injection on the outer wall of the cylinder is studied. The momentum and two-energy equations are solved by differential transformation method (DTM) in the form of stream function using similarity variables. The effect on flow and heat transfer of different types of nanofluids and involved physical parameters Prandtl number Pr, Reylond number Re, Darcy number Da, Biot number Bi, Ratio of thermal conductivities Rk, porosity parameter ε, solid volume fraction parameter φ and shape of nanoparticles are analyzed through graphs. The viscous drag force and heat convection at the wall of the cylinder is calculated in terms of non-dimensional skin-friction coefficient and Nusselt number respectively. Decreasing the porosity of foam porous medium causes increment in magnitude of heat transfer rate for both the phases. Spherical shape of nanoparticles transfers more heat in comparison of cylindrical shape nanoparticles. Amongst the nanofluid H2O-Ag, H2O-Cu and H2O-Al2O3 the magnitude of heat transfer for fluid phase Nuf is lowest for nanofluid H2O-Al2O3.

Second law analysis of turbulent convection flow of boehmite alumina nanofluid inside a double-pipe heat exchanger considering various shapes for nanoparticle

The main objective of this research is to study the effects of nanoparticle shape on the entropy generation characteristics of boehmite alumina nanofluid flow in a horizontal double-pipe heat exchanger. The examined boehmite alumina nanofluids include dispersed cylindrical, brick, blade, platelet and spherical nanoparticles in a mixture of water/ethylene glycol. The nanofluid and water flow through the tube side and annulus side of the heat exchanger, respectively. Two-phase mixture model is applied to precisely simulate the behavior of nanofluid. The effects of the various Reynolds numbers, nanoparticle concentrations and nanoparticle shapes on the frictional, thermal and total entropy generation rates as well as the Bejan number are numerically investigated. The results indicated that the highest and lowest frictional entropy generation rate belongs to the nanofluids with platelet shape and spherical shape nanoparticles, respectively, while the nanofluid containing spherical shape and platelet shape nanoparticles represented the maximum and minimum thermal and total entropy generation rates. Furthermore, it was inferred that the frictional entropy generation rate is enhanced with an increase in nanoparticle concentration, whereas except for nanofluid with spherical shape nanoparticles, the opposite is true for thermal and total entropy generation rates and Bejan number.

Shape effects of MoS2 nanoparticles on rotating flow of nanofluid along a stretching surface with variable thermal conductivity: A Galerkin approach

This article examines the influence of molybdenum disulfide (MoS2) nanoparticles shapes on rotating flow of nanofluid along an elastic stretched sheet. This nanofluid flow is considered in the presence of magnetic effects, thermal radiation and variable thermal conductivity. Platelet, cylindrical and brick shapes nanoparticles are discussed. Feasible similarity variables are introduced to convert the constructed set of partial differential equations (PDEs) into the system of simplified set of nonlinear ordinary differential equations (ODEs). The obtained set of ODEs are tacked by well-known Galerkin technique. The comparison of the achieved results with the published work also pondered. The comprehensive discussion regarding the effects of physical parameters on velocities, temperature, skin friction coefficient and local Nusselt number also presented with graphs. It is observed that with an increase in the thermal radiation parameter and Prandtl number, local Nusselt number decreases while the it is increases with an increase in variable thermal conductivity parameter. Moreover, the shape effects of various kinds of MoS2 nanoparticles are studied and we observed that the rate of heat transfer is enhanced when the platelet shape of molybdenum disulfide (MoS2) nanoparticles are considered. The comparison and convergence analysis shows that it can be further extended for major finding of developed model.

Cattaneo–Christov based study of $${\text {TiO}}_2$$ TiO 2 –CuO/EG Casson hybrid nanofluid flow over a stretching surface with entropy generation

In the present research, a simplified mathematical model is presented to study the heat transfer and entropy generation analysis of thermal system containing hybrid nanofluid. Nanofluid occupies the space over an infinite horizontal surface and the flow is induced by the non-linear stretching of surface. A uniform transverse magnetic field, Cattaneo–Christov heat flux model and thermal radiation effects are also included in the present study. The similarity technique is employed to reduce the governing non-linear partial differential equations to a set of ordinary differential equation. Keller Box numerical scheme is then used to approximate the solutions for the thermal analysis. Results are presented for conventional copper oxide–ethylene glycol (CuO–EG) and hybrid titanium–copper oxide/ethylene glycol ( $${\text {TiO}}_2$$ –CuO/EG) nanofluids. The spherical, hexahedron, tetrahedron, cylindrical, and lamina-shaped nanoparticles are considered in the present analysis. The significant findings of the study is the enhanced heat transfer capability of hybrid nanofluids over the conventional nanofluids, greatest heat transfer rate for the smallest value of the shape factor parameter and the increase in Reynolds number and Brinkman number increases the overall entropy of the system.

Plasmon-induced demagnetization and magnetic switching in nickel nanoparticle arrays

We report on the manipulation of magnetization by femtosecond laser pulses in a periodic array of cylindrical nickel nanoparticles. By performing experiments at different wavelengths, we show that the excitation of collective surface plasmon resonances triggers demagnetization in zero field or magnetic switching in a small perpendicular field. Both magnetic effects are explained by plasmon-induced heating of the nickel nanoparticles to their Curie temperature. Model calculations confirm the strong correlation between the excitation of surface plasmon modes and laser-induced changes in magnetization.

Simulation and Visualization of Flows Laden with Cylindrical Nanoparticles in a Mixing Layer

The motion of cylindrical particles in a mixing layer is studied using the pseudospectral method and discrete particle model. The effect of the Stokes number and particle aspect ratio on the mixing and orientation distribution of cylindrical particles is analyzed. The results show that the rollup of mixing layer drives the particles to the edge of the vortex by centrifugal force. The cylindrical particles with the small Stokes number almost follow fluid streamlines and are mixed thoroughly, while those with the large Stokes number, centrifugalized and accumulated at the edge of the vortex, are poorly mixed. The mixing degree of particles becomes worse as the particle aspect ratio increases. The cylindrical particles would change their orientation under two torques and rotate around their axis of revolution aligned to the vorticity direction when the shear rate is low, while aligning on the flow-gradient plane beyond a critical shear rate value. More particles are oriented with the flow direction, and this phenomenon becomes more obvious with the decrease of the Stokes number and particle aspect ratio.

Nano-Cylinder-Metal Biochemical Sensor Based on the Square Arrangement

This paper presents a novel geometrical structure of NPs on optical fiber for high-sensitivity biochemical sensors, which comprised a single-mode fiber and a cylindrical metallic nanoparticle array. The sensor performed detection through a metallic nanoparticle array, which was arranged in a pattern that rendered the sensor highly sensitive. To effectively reduce the resource of the simulation server, both finite element method and the eigenmode expansion method were performed in combination with a perfectly matched layer, a perfectly reflecting boundary, an object meshing method, and a boundary meshing method. With the area of the triangular elements used as a basis, the object boundary, small object, medium object, and large objects were meshed at a ratio of 1: 10: 146: 728. Results of the simulations indicated that the proposed sensor was short in physical length (approximately 320 $\mu \text{m}$ ), high in resolution (approximately −140 dB), and high in sensitivity (135221.334 nm/RIU).

The Effect of Carbon Nanotubes Based Nanolubricant on Stick–Slip Behavior

In this article, stick–slip behavior of a metal–metal interface is investigated in presence of a lubricant mixed with multiwalled carbon nanotubes (MWCNTs). The friction experiments are carried out to determine the critical pulling velocity at which stick–slip motion disappears and steady sliding follows thereafter. The sliding experiments show that the critical velocity decreases with increase in concentration of MWCNTs in the lubricant up to 1.6% (wt./vol.), but further addition of the nanoparticles in the lubricant leads to increase in the critical velocity. Also, the critical velocity is found to be nearly independent of normal stress at the optimal concentration of the nanoparticles. Moreover, amplitude of stick–slip motion decreases with increase in concentration of MWCNTs up to the optimal value at a fixed velocity but the same begin to increase after the optimal concentration. The results are explained in light of the rolling-sliding mechanism of the spherical or cylindrical nanoparticles reported in literature. The present study reveals that the stick–slip instability can also be eliminated by using an optimal concentration of the nanoparticles in the lubricant.

Cylindrical and Spherical Active Coated Nanoparticles as Nanoantennas: Active Nanoparticles as Nanoantennas

In this article, we review the fundamental properties of several spherical and cylindrical, passive, and active coated nanoparticles (CNPs) with an emphasis on their potential for nanoantenna and nanoamplifier synthesis. For the spherical geometries, the nanoparticles are excited by an electric Hertzian dipole (EHD), which represents, e.g., a stimulated atom or molecule. The cyl indr ical nanoparticles are excited by a magnetic line source (MLS). In the active cases, gain is added to the core region of the particle. For simplicity, it is represented by a canonical, frequency-independent gain model. We demonstrate that specific CNPs can be designed to be resonant and well matched to their respective excitation sources. With active cores, these designs can lead to extremely large total radiated powers. For both configurations, insights into the effects of the nanoparticle material composition, source location, and orientation will be given on the basis of studying their near-field and power-flow density distributions, total radiated powers, and directivity properties.

Parametric study of sweetening process of sour gas by Molybdenum oxide nanoparticles

Abstract The purpose of this work is to study the application of nano-molybdenum oxide adsorbent in gas sweetening process. Experiments were made to evaluate the operating and geometrical parameters in the adsorption process. The process performance of H2S removal from methane gas on molybdenum oxide nanoparticles was defined as the ratio of final concentration of H2S on the initial concentration of H2S. The effects of operating conditions such as operating temperature, pressure, the size of nanoparticles, the amount of H2S concentration in feed stream, feed superficial velocity, and the bed length were studied in this paper. Different temperature values (65, 75, 85, 87 and 89 °C) and pressure values (10, 13, 16 and 19 bar) were applied on the adsorption bed with 19 cm length and 10 cm diameter. Two types of spherical and cylindrical nanoparticles were applied and the effect of different adsorbents diameters (54, 58, 73, 77 and 83 nm) on the process quality (C/C 0 ) was investigated. Also, the effect of initial concentration of H2S in the feed gas stream was surveyed. The optimum operating conditions for spherical and cylindrical types were the same, 16 bar and 85 °C. The adsorption capacity of 0.22 g H2S/g MoO2 and 0.19 g H2S/g MoO2 was achieved at the optimum conditions using nano-spherical and nano-cylindrical MoO2 sorbent, respectively. Applying in our study two adsorption isotherms, the Langmuir and Freundlich isotherms, analysis of variance displayed a high coefficient of determination (R2) value of 0.989 for the Freundlich isotherm, indicating the satisfactory adjustment of the experimental data. The results can be interesting for related industries and can be applicable in process optimization.

Low-frequency laser spectroscopy of cylindrical nanoparticle suspensions

A theory of generation of anti-Stokes radiation on the eigenvibrations in a suspension of cylindrical nanoparticles in the field of two copropagating electromagnetic pump waves has been developed. Surface ponderomotive forces are shown to induce acoustic vibrations and dipolemoments of nanoparticles at the anti-Stokes frequency. Under these conditions, the scattering efficiency depends on the dielectric characteristics of the solution and the acoustic parameters of the liquid and solid fractions of the suspension. Experiments on stimulated low-frequency Raman scattering of laser radiation in aqueous suspensions of tobacco mosaic virus in a buffer solution have been performed. A coherent signal of the Stokes component with a frequency shift of ≈60GHz is detected; this value is in good agreement with the estimated frequency shift for stimulated excitation of eigenvibrations of cylindrical nanoparticles in a liquid: ≈50 GHz.