Effect Of Nanoparticle Shape Research Articles

Investigation of Effect of Platinum Nanoparticle Shape on Oxygen Transport in PEMFC Catalyst Layer Using Molecular Dynamics Simulation.

For the widespread adoption of polymer electrolyte membrane fuel cells, it is compelling to investigate the influence of the Pt nanoparticle shapes on the electrocatalytic activity. In this study, a catalyst layer was modeled by incorporating four types of Pt nanoparticles: tetrahedron, cube, octahedron, and truncated octahedron, to investigate the relationship between the shapes of the nanoparticles and their impact on the oxygen transport properties using molecular dynamics simulations. The results of our study reveal that the free volume, which has a substantial impact on the oxygen transport properties, exhibited higher values in the sequence of the tetrahedron, cube, octahedron, and truncated octahedron model. The difference in free volume following the formation of less dense ionomers was also related to the surface adsorption of Pt nanoparticles. Consequently, this led to an improved facilitation of oxygen transport. To clarify the dependence of the oxygen transport on the shape of the Pt nanoparticles in detail, we analyzed the structural properties of different Pt shapes by dividing the Pt nanoparticle regions into corners, edges, and facets. Examination of the structural properties showed that the structure of the ionomer depended not only on the shape of the Pt nanoparticles but also on the number of corners and edges in the upper and side regions of the Pt nanoparticles.

Numerical solution of Al2O3–H2O with shape effects and unsteady flow over a solid rotating disk

In this paper, we examine the shape effects of different nanoparticles of an incompressible, unsteady flow of a nanofluid [Formula: see text] with water [Formula: see text] as the base fluid over a rotating disk. Magnetic field results are also added. In this research, four distinct shapes of [Formula: see text] nanoparticles, i.e., sphere, blade, cylinder and brick, have been employed. Every shape is suspended at the same volume. After using the Von Karman transformation, the Navier–Stokes equation, along with the magnetic field effect and the thermal energy equation, is numerically solved by using the bvp4c MATLAB solver. The effects of various parameters on the velocity field and temperature profile are illustrated graphically. This analysis is validated by comparing it to the previously described research. Furthermore, increasing the volume fraction parameter [Formula: see text] causes the radial, tangential, and axial velocities near the disk for the shapes brick, cylinder, and blade to decrease and increase for the shape sphere. The fluid rotating in front of the disk rotates more slowly for small values of the unsteadiness parameter [Formula: see text]. The magnetic field M has a significant influence on the axial flow when the suction parameter values are small, but this impact is limited when the suction parameter values are large.

Shape effects of gold nanoparticles on squeezing nanofluid flow and heat transfer between parallel plates

The current paper examines how the form of gold (Au) nanostructures affects the compression of nanofluids and heat transmission across parallel surfaces. Water has been used as the porous medium to explore the various morphologies of nanomaterials, including columns, spheres, hexahedron, tetrahedron, and lamina. In order to create (ODEs), proper modifications must be applied to (PDEs). To solve nonlinear boundaries value regular differential equations statistically, the homotopy analysis method (HAM) guarantees converging of the numerical integration. On temperature and velocity profiles the impacts of several variables, including a solid volume fraction, thermal radiation, Reynolds number, magnetic field, Eckert number, sucking component, and slope angle, are represented graphically. The Nusselt is studied graphically for different values of the relevant factors. The obtained data show that, in comparison to other shapes of nanoparticles, lamina-shaped nanoparticles have the highest rate of heat transport and that sphere-shaped nanoparticles have played a significant role in thermal dispersion.

Effect of particle shape on the heat transfer of magnetohydrodynamic nanofluid with dissipative energy and inertial drag

This investigation focuses on the nanoparticle shape effect on the flow of conducting non-Newtonian Maxwell nanoliquid through an absorptive expanding surface. Insertion of inertial drag due to the Darcy–Forchheimer model and the dissipative heat in the flow phenomena supplements the work. The thermal properties of the fluid show its important role because of the use of various thermophysical models such as the Gharesim model of viscosity and the Mintsa model of thermal conductivity. The proposed mathematical model is designed by the implementation of suitable similarity transformations and then a numerical scheme is adopted to solve the transformed phenomena. In particular, shooting-based traditional Runge–Kutta (RK) fourth order is implemented for the solution. The behavior of the parameters that are participating in the flow phenomena is deployed via graphs and the computation of the engineering coefficients is displayed in tables. The impression of innumerable governing flow constraints is interpreted with the validation of these investigations with the earlier investigation. However, the major outcomes are; the particle concentration contributes its significant characteristics in enhancing the fluid velocity as well as temperature for the increasing shape. The dissipative heat formulated by the Eckert number also augments the fluid temperature in association with the thermal radiation whereas the unsteadiness parameter retards it significantly.

Thermal optimization and magnetization of nanofluid under shape effects of nanoparticles

The measurements of thermal transport are complex to optimize from high temperatures; this is because increased thermal-management performance have typically been accompanied for the sake of applicability in thermal barriers and heat dissipation. In this manuscript, an investigation for the flow of Brinkman nanofluid is carried out in which shapes of nanoparticles are suspended in ethylene glycol and their thermophysical properties have been emphasized. In order to have an optimized heat and mass transfer, the mathematical modeling is traced out for temperature, concentration and velocity profiles through non-singularized fractional technique. The analytical solutions for temperature, concentration and velocity profiles have been derived by invoking integral transforms. Special analytical solutions have been traced out for Stoke's first and second problems by varying boundary conditions of the problem. The rheological parameters have shown the pertinent effects on the basis of numerical variations and similarities. The results suggested that velocity of ethylene glycol-alumina is slower than ethylene glycol-copper, ethylene glycol-gold and ethylene glycol-silver during non-magnetization process.

Effects of Particle Size, Charge, Shape, Animal Disease State, and Sex on the Biodistribution of Intravenously Administered Nanoparticles

AbstractThe relationship between nanoparticle size, charge, shape, and in vivo biodistribution is of great importance for the rational design and selection of intravenously administered nanoparticles. A resource that aids in the selection and design of nanomaterials for this purpose would be a valuable tool. Previous literature reviews have examined narrow categories of nanomaterials or have not statistically analyzed a broad range of nanomaterial literature. Here, data regarding the biodistribution of intravenously administered synthetic and organic nanomaterials in animal models from literature available in PubMed is collected. This work outlines the effect of nanoparticle size, charge, shape, animal sex, and animal disease status on biodistribution of intravenously administered nanomaterials. Particle size and charge are found to significantly and independently influence biodistribution to several organs. Finally, animal sex and disease state are observed to function as effect modifiers for biodistribution.

Nanoparticle shape effects on MHD Cu–water nanofluid flow over a stretching sheet with thermal radiation and heat source/sink

This study provides an insight into the effects of various nanoparticle shape factors on magnetohydrodynamic boundary layer flow and heat transfer over a stretching sheet. Choosing appropriate nanoparticles can control velocity and heat transfer. A magnetic field is part of the momentum equation, and the effects of radiation and heat source/sink are part of the energy equation. Equations governing the problem are converted into nonlinear ODEs by similarity transformation. Afterwards, Runge–Kutta fourth-order scheme combined with shooting technique is employed. A magnetic field and porosity decrease the velocity. Radiation and a heat source/sink both escalate temperature. The Eckert number and porosity also improve the temperature. As nanoparticle volume fraction increases, the Nusselt number decreases and skin friction increases. Among the nanoparticle shapes considered in this study, platelet-shaped nanoparticles have the best flow and heat transfer performance. According to the studies we examined, the results obtained are consistent with those previously published.

Advances in High-Temperature Molten Salt-Based Carbon Nanofluid Research

Molten salt is an excellent medium for heat transfer and storage. The unique microstructure of carbon nanomaterials leads to good mechanical stability, low density, high thermal conductivity, and high strength, etc. The addition of carbon nanomaterials to molten salt to form molten salt nanofluid can remarkably enhance the specific heat capacity and thermal conductivity of molten salt and reduce the molten salt viscosity, which is of great importance to increase the heat storage density and reduce the heat storage cost. Nevertheless, some challenges remain in the study of such nanofluids. The main challenge is the dispersion stability of carbon nanomaterials. Therefore, to improve research on carbon nanofluids, this paper summarizes the progress of carbon-based molten salt nanofluid research worldwide including the preparation methods of molten salt nanofluids, the improvement of heat transfer performance, and the improvement of heat storage performance. The effects of carbon nanoparticle concentration, size, and type on the heat transfer and storage performance of molten salt are derived, and the effects of nanoparticle shape on the heat transfer performance of molten salt are analyzed while more promising preparation methods for carbon-based molten salt nanofluids are proposed. In addition, the future problems that need to be solved for high-temperature molten salt-based carbon nanofluids are briefly discussed.

Nanoparticles impacts on natural convection nanofluid flow and heat transfer inside a square cavity with fixed a circular obstacle

Many significant applications may be acquired in specific nanoparticle shapes as well as size range or size. The shape of nano-sized particles is significant in every field of trace metal detection, for biomolecular assays, molecular labeling and the application of nanotechnology. The nanoparticle's shape effects are very noteworthy on the thermal conductivity of suspension. The main focus of the current study is to elaborate the nanoparticles shape impacts on nanofluid flow in a lid-driven square cavity with a fixed circular obstacle at the center. The top wall of the square cavity is adiabatic and moving. The circular cavity and bottom wall of the cavity is heated, while the remaining walls of the cavity are cold. The diamond-water nanofluid contained three kinds of nanoparticles shape namely Sphere, Column (nonspherical) and Lamina (nonspherical). The flow-modeled phenomena is governed in form of coupled partial differential equations and is tackled with finite element method (FEM). The flow distribution analysis is deliberated in form of streamlines, isothermal contour patterns, velocity distribution, temperature distribution, kinetic energy and Nusselt number. The graphical results indicate that the Lamina (nonspherical) shape nanoparticles have higher performance in (diamond-water) temperature distribution and heat transfer.

Thermal transport in nanofluid across a radiated permeable sheet with irreversible effects based on the shape of the particles

Purpose The purpose of this study is to examine the flow and heat transfer performance of titanium oxide/water and copper/water nanofluids with varying nanoparticle morphologies by considering magnetic, Joule heating and viscous dissipation effects. Furthermore, it studies the irreversibility caused by the flow of a hydromagnetic nanofluid past a radiated stretching sheet by considering different shapes of TiO2 and Cu nanoparticles with water as the base fluid. Design/methodology/approach In this study, the authors investigated entropy production in an unsteady two-dimensional magneto-hydrodynamic nanofluid regime using water as the base fluid and five unique TiO2 and Cu nanoparticle morphologies. Using appropriate similarity transformations, the controlling nonlinear system of partial differential equations is transformed into a system of ordinary differential equations. The shooting technique with Runge–Kutta method was then used to solve these equations quantitatively. The findings of this study are depicted graphically, and the skin friction corresponding to various nanoparticle geometries and physical parameter variations is tabulated. Findings To assess the reliability of the current findings, a tabular representation of the data was compared to that of previously published studies. It is noted that a reduction in thermal energy was detected as a result of the higher levels of Prandtl number (Pr). It is further analysed that the highest heat energy generation of TiO2 nanoparticles was larger than that of Cu nanoparticles. The most important finding was that the sphere-shaped Cu/H2O nanofluid had the lowest velocity and greatest temperature. Also, Cu nanoparticles in the shape of platelets generate the most entropy, while TiO2 nanoparticles in the shape of spheres generate the least. Originality/value To the best of the knowledge of the authors, the attempt to investigate the previously unexplored shape effects of TiO2 and Cu nanoparticles on the heat transfer enhancement and inherent irreversibility caused by hydromagnetic nanofluid flow past a radiated stretching sheet with magnetic, Joule heating and viscous dissipation effects. This study fills this gap in the existing literature and encourages scientists, engineers and businesses to do more research in this area. This model can be used to improve heat transfer in systems that use renewable energy, thermal management in industry and the processing of materials.

Numerical Study About Nanofluids of Spherical and Tube-Shaped TiO2 Nanomaterials on the Thermal Performance and Entropy Generation of Different Cross-Section Microchannel Heat Sinks

We numerically evaluated the thermal performance of microchannel heat sinks, considering rectangular, hexagonal, and circular cross-sections. Moreover, as a passive heat transfer augmentation technique, dimples were added to improve the rectangular microchannel heat sinks. These simulations use nanofluids based on TiO2 nanoparticles or nanotubes dispersed in bidistilled water as working fluids. The mathematical model considered variable thermophysical properties of the nanofluids; for this purpose, polynomial fittings correlate the dependence of the thermophysical properties on the temperature. We considered a heat flux of q″ = 50 W/cm2 at the microchannel’s lower surface as a boundary condition along with laminar flow conditions. The numerical simulations allowed the Nusselt numbers and entropy generation calculation, which were the basis for the thermal performance calculation. Regarding the effect of TiO2 nanoparticles shape, spherical TiO2 nanoparticles based nanofluids using rectangular microchannels improve the Nusselt number. Moreover, the frictional entropy decreases with nanofluids based on TiO2 nanotubes, but the thermal entropy decreases with nanofluids based on TiO2 nanotubes. Incorporating dimples in the rectangular microchannel enhances the Nusselt numbers and lowers the entropy generation. Considering the Reynolds number range and from the perspective of Nusselt number and entropy generation, we concluded that the microchannels must be operated at a high Reynolds number to improve the microchannel heat sinks thermal performance.

Shape Effect of Nanoparticles on Nanofluid Flow Containing Gyrotactic Microorganisms

In this paper, we discussed the effect of nanoparticles shape on bioconvection nanofluid flow over the vertical cone in a permeable medium. The nanofluid contains water, Al2O3 nanoparticles with sphere (spherical) and lamina (non-spherical) shapes and motile microorganisms. The phenomena of heat absorption/generation, Joule heating and thermal radiation with chemical reactions have been incorporated. The similarity transformations technique is used to transform a governing system of partial differential equations into ordinary differential equations. The numerical bvp4c MATLAB program is used to find the solution of ordinary differential equations. The interesting aspects of pertinent parameters on mass transfer, energy, concentration, and density of the motile microorganisms’ profiles are computed and discussed. Our analysis depicts that the performance of sphere shape nanoparticles in the form of velocity distribution, temperature distribution, skin friction, Sherwood number and Motile density number is better than lamina (non-spherical) shapes nanoparticles.

Nanoparticle Shape Effect on a Sodium–Alginate Based Cu–Nanofluid under a Transverse Magnetic Field

Sodium-alginate (SA) based nanofluids represent a new generation of fluids with improved performances in terms of heat transfer. This work examines the influence of the nanoparticle shape on a non–Newtonian viscoplastic Cu–nanofluid pertaining to this category. In particular, a stretching/shrinking sheet subjected to a transverse magnetic field is considered. The proposed Cu–nanofluid consists of four different nanoparticles having different shapes, namely bricks, cylinders, platelets, and blades dispersed in a mixture of sodium alginate with Prandtl number Pr = 6.45. Suitable similarity transformations are employed to reduce non–linear PDEs into a system of ODEs and these equations and related boundary conditions are solved numerically by means of a Runge–Kutta–Fehlberg (RKF) method. Moreover, analytical solutions are obtained through the application of a MAPLE built–in differential equation solver (Dsolve). The behavior of prominent parameters against velocity and temperature is analyzed. It is found that the temperature increases for all shapes of nanoparticles with the viscoplastic parameter and the Eckert number.

Behavior of Au Nanoparticles under Pressure Observed by In Situ Small-Angle X-ray Scattering

The mechanical properties and stability of metal nanoparticle colloids under high-pressure conditions are investigated by means of optical extinction spectroscopy and small-angle X-ray scattering (SAXS), for colloidal dispersions of gold nanorods and gold nanospheres. SAXS allows us to follow in situ the structural evolution of the nanoparticles induced by pressure, regarding both nanoparticle size and shape (form factor) and their aggregation through the interparticle correlation function S(q) (structure factor). The observed behavior changes under hydrostatic and nonhydrostatic conditions are discussed in terms of liquid solidification processes yielding nanoparticle aggregation. We show that pressure-induced diffusion and aggregation of gold nanorods take place after solidification of the solvent. The effect of nanoparticle shape on the aggregation process is additionally discussed.

Scrutinization of Stefan suction/blowing on thermal slip flow of ethylene glycol/water based hybrid ferro-fluid with nano-particles shape effect and partial slip

This study is aimed to examine thermal slip flow of mixture based hybrid ferro-fluid with shape effect of nano-particles and partial slip under the constant influence of Stefan suction/blowing impacts. Thermal slip flow is magnetized with applied time-dependent magnetic force in transverse direction of flow. Partial slip impact is considered on magnetized hybrid ferro-fluid. Additionally, spherical shaped nano-particles have been accounted to constitute the desired hybrid ferro-fluid whereas distinct shape nano-particle effect is analyzed and discussed for heat transfer efficiency. The flow governing highly nonlinear equations are transformed into ordinary differential equations using suitable similarity transform. Furthermore, motion and temperature profile for spherical shaped nano-particles of hybrid ferro-fluid are analyzed and discussed under the impression of suction and blowing effect. It is observed that in the event of mass suction S=1 and partial slip 0.2≤Sf≤0.6 reduced shear stress rates and high rates of heat transfer are obtained. It is concluded that high Lorentz force under suction/blowing effect contract thermal boundary of flow. Laminar shape nano-particle increase temperature profile when compared with other shapes of nano-particles.

Shape effects on the mixed convective hybrid nanoliquid flow over a rough slender cylinder with convective condition

This paper presents the nanoparticle's shape effects on heat and fluid flow characteristics over a slender cylinder with a rough surface. Despite this, the impacts of convective boundary constraints and magnetohydrodynamics (MHD) are included in this analysis. The problem is formulated as a set of nonlinear coupled partial differential equations with boundary constraints. The non-similar transformations have been utilized to convert these dimensional equations into non-dimensional forms. Further, the implicit finite difference scheme and the technique of quasi-linearization are employed for mathematical simplification. In this work, Hamilton and Crosser's model is employed to define the effective viscosity and thermal conductivity of the hybrid nanoliquid. It is observed that heat transfer rate is pronounced to be more for the brick shape of copper and alumina nanoparticles followed by cylinder, platelet, and blade shape nanoparticles. The magnetic parameter is more favourable to the heat transfer rate than to the skin-friction coefficient for the positive values of the Eckert number, i.e. fluid heating case. The temperature of the fluid and heat transfer rate are enhanced for larger values of the Biot number. The skin-friction coefficient is higher for the platelet shape nanoparticles, followed by cylinder, brick, and blade shape nanoparticles.

Shape-dependent gold nanoparticle interactions with a model cell membrane.

Customizable gold nanoparticle platforms are motivating innovations in drug discovery with massive therapeutic potential due to their biocompatibility, stability, and imaging capabilities. Further development requires the understanding of how discrete differences in shape, charge, or surface chemistry affect the drug delivery process of the nanoparticle. The nanoparticle shape can have a significant impact on nanoparticle function as this can, for example, drastically change the surface area available for modifications, such as surface ligand density. In order to investigate the effects of nanoparticle shape on the structure of cell membranes, we directly probed nanoparticle-lipid interactions with an interface sensitive technique termed sum frequency generation (SFG) vibrational spectroscopy. Both gold nanostars and gold nanospheres with positively charged ligands were allowed to interact with a model cell membrane and changes in the membrane structure were directly observed by specific SFG vibrational modes related to molecular bonds within the lipids. The SFG results demonstrate that the +Au nanostars both penetrated and impacted the ordering of the lipids that made up the membrane, while very little structural changes to the model membrane were observed by SFG for the +Au nanospheres interacting with the model membrane. This suggests that the +Au nanostars, compared to the +Au nanospheres, are more disruptive to a cell membrane. Our findings indicate the importance of shape in nanomaterial design and provide strong evidence that shape does play a role in defining nanomaterial-biological interactions.

Numerical Analysis of the Effect of Nanoparticles Size and Shape on the Efficiency of a Micro Heatsink.

In this paper, two novel micro heat sinks (MHSs) were designed and subjected to thermal analysis using a numerical method. The fluid used was Boehmite alumina-water nanofluid (NFs) with high volume fractions (VOFs). Studies were conducted to determine the influence of a variety of nanoparticle (NP) shapes, such as platelet brick, blade, cylinder, and Os. The heatsink (HS) was made of copper, and the NFs entered it through the middle and exited via four outlets at the side of the HS. The finite element method was used to simulate the NFs flow and heat transfer in the HSs. For this purpose, Multi Physics COMSOL software was used. The maximum and middle values of HS temperature (T-MAX and T-Mid), thermal resistance (TH-R), heat transfer coefficient (h), FOM, etc., were studied for different NP shapes, and with Reynolds numbers (Re) of 300, 1000, and 1700, and VOFs of 0, 3, and 6%. One of the important outcomes of this work was the better thermal efficiency of the HS with rectangular fins. Moreover, it was discovered that a rise in Re increased the heat transfer. In general, adding NPs with high VOFs to MHSs is not appropriate in terms of heat. The Os shape was the best NP shape, and the platelet shape was the worst NP shape for high NPVOF. When NPs were added to an MHS, the temperature of the MHS dropped by an average of 2.8 or 2.19 K, depending on the form of the pin-fins contained inside the MHS (circular or square). The addition of NPs in the MHS with circular and square pin-fins enhanced the pressure drop by 13.5% and 13.3%, respectively, when the Re = 1700.

“The Effects of Silver Nanoparticle Shape on Protein Adsorption and Neural Stem Cell Viability”

Silver nanoparticles (AgNPs) are important and widely used as antimicrobials and nanodrug carriers. The increased use of AgNPs in consumer products has raised concerns about nanosafety; for instance, AgNPs may be inhaled and translocated to the brain via olfactory neural stem cells/progenitors. While the biological effects of nanoparticle size have been widely investigated, there are little data on the effects of particle shape on cellular phenotype. Therefore, here we investigated the interactions between AgNP spheres, rods, cubes, and triangles and human plasma proteins as well as their effects on the viability of NE-4C neural stem cells. Nanoparticles were synthesized by wet chemistry methods and characterized by UV-vis spectroscopy, dynamic light scattering, zeta potential measurement, transmission electron microscopy, nanoparticle tracking analysis, and differential centrifugal sedimentation. NE-4C cell viability was assessed using the MTT reduction assay, and the cellular uptake of differently shaped nanoparticles was monitored by electron microscopy. All 50 nm (in at least one dimension) AgNPs exerted toxic effects, with rods and cubes displaying greater toxicity than spheres and triangles. These cellular and physicochemical results indicate that edges on the AgNPs increase toxicity, presumably due to enhanced ion dissolution from the edges.

Silver Nanoparticle Labels for Electrochemical Detection of Bioassays

Electrochemistry plays a major role in immunosensor development because of its higher sensitivity, simplicity, portability, and rapidity compared to more common enzymatic, fluorescent and radioactive labelling methods. Silver nanoparticles (AgNPs) have been identified as potential electrochemical labels for such immunoassays. Characterizing the composition, size, shape, and surface modifications of the AgNP is important to achieve expected analytical performance of the bio assay. Here we are interested in studying the effect of nanoparticle shape towards the electrochemical detection of a metallo-immunoassay using Au-Ag galvanic exchange (GE) reaction followed by anodic stripping voltammetry. We observe that during GE between electrogenerated Au3+ and the Ag labels, a thin shell of Au forms on the surface of the NP and prevent further exchange. This shell is more porous when GE proceeds on silver nanocubes (AgNCs) compared to spherical silver nanoparticles (sAgNPs), and therefore, more exchange occurs when using AgNCs. More interestingly, optimizing the ratio of the two types of AgNP labels, we could able to decrease the LOD of a biological assay designed to detect a heart failure biomarker (NT-proBNP) without compromising the dynamic range compared to using either of the two labels independently. This made it possible to achieve the clinically relevant range for NT-proBNP analysis used by physicians for heart failure risk stratification.