Narrow Results

Gold nanoparticles (1–100nm) are minute particles and are safer to disperse into blood to deal with many internal ailments. Magnetized gold nanoparticles with their promising effect in biomedicines are the epicenter of research for many scientists. This study is an attempt to apply nanomaterials in the field of bio-medicine. Particularly, the study surrounds around heat and mass transfer property of blood nanofluid in porous artery of narrow diameter. This work involves modeling a layer of gold nanoparticles in blood flow along porous surface as well as effect of reaction. Flow of blood is assumed to be non-Newtonian (in vessels of small diameter). Magnetic effect is also clubbed with the study. Standard procedure of reducing equations is used. Nanoparticles’ layering concentration in the range of 2–9% delivers noticeable effects on conduction of heat and performance of blood flow. Numerical solution was obtained by MATLAB after shooting an appropriate guess. Accounting effect of layering of nanoparticle on Casson parameter leaves a noticeable impact on results. Graphical plots are used to extract impact of each parameter on heat conduction and velocity of the blood. The findings threw light on importance of magnetic parameters in relocating heat. The increase in thickness of layer of nanoparticle from 2nm to 6nm, increased heat conductivity and performance significantly. The information from this work can be basis of novel method of treatment in medical field and can deliver the base for future experimentation.

This research aims to explore the free vibration behavior of functionally graded porous (FGP) plates resting on a Kerr-type elastic foundation. This investigation employs an innovative trigonometric shear deformation (ITSD) theory with five variables. The study encompasses various plate configurations, including homogeneous FGP plates, hard-core FGP sandwich plates, and soft-core FGP sandwich plates with both regular and irregular pore structures. The ITSD theory naturally addresses shear stress concerns at the outer surfaces, while also considering the thickness stretching effect, all without the need for correction factors. To formulate the governing equations for the free vibration of such plates on an elastic foundation, Hamilton’s principle is employed. The Navier double trigonometric series approach is then utilized to solve this problem. To validate the plate theory and methodologies used in this work, a comparative analysis is conducted with existing studies. Additionally, comprehensive parametric simulations are employed to examine the impact of different factors, such as geometric properties, material characteristics, sandwich schemes, and parameters of the Kerr-type foundation, on the dimensionless natural frequencies of simply supported rectangular FGP plates.

Invasion percolation is studied on correlated square networks described through a site-bond model which has proven to be useful for the characterization of real heterogeneous media. It is shown how the correlation degree affects the mean front velocity, the number of islands of trapped defender fluid (which are completely surrounded by invaded elements), their size distribution and total number of steps to reach the final state. The correlation degree seems to affect the fractal dimension of the percolating cluster. A characteristic correlation length is found to exist which maximizes the mean invasion velocity.

The micro-pores with size of 0.2 to 1.8 µm, which randomly distribute in a 316L stainless steel substrate, were fabricated by the transfer of the porous structure of anodic porous alumina. The mask anodic porous alumina was directly prepared by anodizing of aluminum film, which was deposited on 316L substrate by DC magnetron sputtering. The transfer of the porous structure of anodic alumina into the 316L substrate could be achieved without the additional through-hole treatment to the barrier layer. The localized priority dissolution on porous alumina is observed during the anodizing. And this process is considered to lead to the micro-pores formation on 316L substrate. In addition, the effect of anodizing time on the pores size and number on 316L substrate also was discussed.

In the present paper, we have studied the propagation of axial symmetric cylindrical surface waves through rotating cylindrical bore in a micropolar porous medium of infinite extent possessing cubic symmetry. The frequency equation for surface wave propagation in the micropolar porous medium has been derived and liquid filled bore are derived. The effect of the rotation on phase velocity of surface wave has been studied in detail. Radius of bore and other material parameters for empty and liquid filled bore are derived. A particular case of interest has been deduced. Numerical results have been obtained and illustrated graphically to understand the behavior of phase velocity versus wave number of a wave. The results have indicated that the effect of rotation on phase velocity is highly pronounced. Comparisons are made in the absence of rotation.

Porous Anodic Aluminum Oxide (AAO) films were prepared by two-step anodizing in sulfuric and oxalic acid solutions and observed by transmission electron microscope (TEM) and X-ray diffraction. The results show that the form of AAO film is affected by the varieties and concentrations of electrolyte, anodizing voltage, and the anodizing time; the formation and evolution processes of the AAO film are relative with the anodizing voltage severely, and the appropriate voltage is helpful to the ordering of the holes. The formation of the AAO film could be explained based on the present experiment and some former models.

In this research, the natural frequency behavior of functionally graded (FG) porous joined hemispherical–cylindrical–hemispherical shell vessels reinforced by graphene platelet (GPLs) has been studied for the first time. Three various types of porosity distribution are assumed through the thickness direction of shell vessel. In the two types of porosity patterns, a pattern of porosities in metal matrix is symmetric and the other one is uniform. Besides, five GPL patterns are assumed for dispersing of GPLs in metal matrix. Extended role of mixture and Tsai-Halpin is used to determine the mass density and Young’s modulus of elasticity of the structure, respectively. By employing 3D elasticity theory, Hamilton’s Principal and FEM in conjunction with Rayleigh–Ritz method, the governing equations of motion of the joined shell vessel are obtained and natural frequencies are extracted. The impact of various factors such as coefficient of porosity, several porosity patterns along with different GPLs distributions and weight fraction of graphene nanofillers on natural frequency behavior of FG porous joined hemispherical–cylindrical–hemispherical shell vessels reinforced by GPLs nanofillers has been reported for the first time.

This paper researches the free vibrations and corresponding material parameters of a functional gradient graphene platelets-reinforced composite (FG-GPLRC) cantilever torsional plates with both pore and graphene variations in the transverse direction. Utilizing the feature of closed-cell cellular solids, the mixture rule, and the modified Halpin–Tsai model, the material parameters of the composite are determined for different volume fractions of component materials. Then, using the classical plate theory (CLPT), the Rayleigh–Ritz technique and polynomials, the dynamic equation that can be used to obtain the free vibration mode shapes and frequencies of the rotating cantilever torsional plate is given. Comparison studies with the previous calculation results from available literature and the finite element (FE) models of cantilever plates are conducted, and the correctness of the present theoretical formulation and numerical calculation is verified. Finally, the effects of graphene platelet (GPL) distribution, porosity distribution (PD), GPL content, rotational speed, and average geometric size of GPL on free vibrations of the system are studied in depth.

This paper describes the nonlinear vibration of a novel smart plate with an auxetic metamaterial core and piezoelectrically actuated multiscale hybrid nanocomposite porous layers (GPL/CF/PVDF) using Reddy’s higher-order shear deformation theory (HSDT). Using the rule of mixture (ROM) and Halpin–Tsai model (HT), the current properties of electroelastic layers were determined. Smart plate equations are detected using Hamilton’s principle, Maxwell’s law, and von Karman nonlinearity terms. The generalized differential quadrature method (GDQM) is then employed to discretize the governing equations of a sandwich plate for various boundary conditions. In addition, the smart plate’s nonlinear frequency ratio and nonlinear natural frequency are detected using the angle of auxetic cell, the electric voltage, and the graphene nanoplatelet weight fraction. In addition, the influence of the porosity constant, the thickness of the auxetic core, and the thickness of the smart graphene-reinforced hybrid nanocomposite layer on $({\omega }_{\mathrm{\text{nl}}}/{\omega }_l)$ and ${\omega }_{\mathrm{\text{nl}}}$ were computed and presented in each figure.

The vibrations of rotating joined conical–conical shells with classical supported conditions have been studied extensively. As a matter of fact, in some cases, these classical boundary conditions cannot exactly model actual situations. Moreover, theoretical frameworks on them are still limited. This research aims to investigate the fundamental frequencies and dynamic mode shapes of the traveling wave of the rotating porous metal material joined conical–conical thin shells (PJCS) with elastic supports. By utilizing artificial spring technology, arbitrary elastic supported boundary conditions and classical boundary conditions are achieved efficiently. A new dynamic model has been formulated with the help of the first-order shear deformation theory (FSDT) and Hamilton’s principle. By employing the generalized differential quadrature (GDQ) method along with stress boundary conditions and generalized eigenvalues, various factors such as porosity, semi-vertex angles and stiffness are analyzed for their impact on the fundamental frequencies of forward wave (FW), backward wave (BW) and mode shapes. The presented results are validated through the convergence and comparison studies from literatures. The interesting and novel results indicate that the in-plane displacement constraints have the most significant impact on the critical speed, while the lateral displacement constraint has the least effect. The vibrations are more easily excited for the part with a larger half vertex angle. Rotating PJCS with Type 1 has the biggest critical rotating speed.

In this research, a thick hollow cylindrical shell made of bidirectional functionally graded open cell porous materials under internal thermal shock according to the classical theory of linear thermo-elasticity is examined for the first time. The cylinder is made of a porous cellular material and its porosity varies along both radial and axial directions continuously. The governing motion equations are obtained by using 2D-axisymmetric theory of linear thermo-elasticity rather than shell theories. This theory represents thickness stretching and gives more precise results. Graded finite element method is employed to model the problem. Applying this method rather than conventional FEM leads to more accurate results, especially for dynamic analyses. The cubic higher order element is used for dividing the solution domain. To obtain transient temperatures, Crank–Nicolson algorithm is used and then the Newmark procedure is used to derive time responses of displacement and stress components. The time history of displacements and stress components for different radial and axial power law exponents, porosity coefficient, boundary conditions, length-to-thickness ratio and two different porosity patterns are investigated in detail. The obtained results show that thermal-induced vibration is generally caused by hoop stress, and frequency and amplitude of vibrations and velocity of stress waves are considerably influenced by the porosity distribution, porosity coefficient and power law exponents in both directions.

This research study aims to delve into the effects of carbon nanotubes (CNTs) agglomeration on the dynamic characteristics of smart functionally graded (FG) porous sandwich plates. The structure of the sandwich plate comprises a core layer that incorporates dispersed CNTs within a polymer matrix. In addition, two layers are equipped with piezoelectric sensors and actuators. The agglomeration of CNTs is mathematically modeled using the Eshelby–Mori–Tanaka approach, accounting for both complete and partial agglomeration states. Moreover, the study takes into account the thermal-dependent behavior of CNTs. Subsequently, an optimal nonlinear proportional-integral-derivative (PID) control scheme based on the Bat optimization algorithm is applied to mitigate vibrations within the composite structure. Unlike the fixed gains of the classical PID, the nonlinear version dynamically adjusts its parameters in real time, ensuring enhanced responsiveness and stability. Furthermore, a comprehensive numerical investigation is conducted to assess the impact of several parameters on the natural frequencies in the frequency domain. These parameters encompass porosity distributions, porosity coefficients, reinforcement patterns, weight fractions of nanofillers, temperature, and the agglomeration of CNTs. The vibration attenuation performance of both nonlinear and classical PID controllers is evaluated through numerical simulations. The findings indicate the robustness and rapid disturbance rejection of the proposed control scheme.

Zinc oxide and dye are utilized to absorb and convert incident photons to electric energy using a sandwich construction with an active area of 1.5 × 1.5 cm², which improves the photodetector’s performance as a light sensor. A variable variation of solution concentration according to the ratio of mass and volume was used to extract natural dye from Barago officinalis. The Barago officinalis absorbance was investigated by spectrophotometer at a wavelength of 200–1000 nm. This indicates that UV absorption has occurred, and note that when an increase in the spectral response at concentration of 1, there appears an improvement in the infrared region with a wave length of 950 nm and the enhanced sensitivity in the long wavelength region could be attributed to formation of dye aggregates within the devices which led to the highest value of qualitative detection up to 1.3 × 10${}^{13}$ W${}^{-1}$ cm Hz${}^{1/2}$ thus increasing quantum efficiency to (119)% at the wavelength (950 nm).

This study describes the application of porphyrin-embedded porous organosilicate materials to the adsorption of ammonia gas. Organosilicate scaffolds were synthesized through a surfactant-templating process combined with a phase separation technique. The structure offers a macro-textured scaffold to facilitate flow through the sorbent material and provide enhanced access to the available surface area provided by a combination of micro- and mesopores distributed over a range of sizes. The materials were grafted post-synthesis to provide sites for covalent immobilization of porphyrins. These porphyrins were utilized for incorporation of metal sites into the organosilicate materials. The removal of ammonia was evaluated for a number of materials incorporating copper metalloporphyrins of varied structure at varied loading levels. Results have been compared to removal of ammonia by a carbon material. Copper deuteroporphyrin IX bis-ethylene glycol provided the strongest interactions with ammonia. High loading levels of this porphyrin within the sorbent structure showed increasing evidence of stacking and did not improve the performance of the material.

In this study, the vibration of functionally graded porous truncated conical shell reinforced with graphene platelets (GPLs) is investigated. The GPLs nanofillers and pores are considered to be uniform and nonuniform throughout the thickness direction. Using Hamilton’s principle, the governing equations are derived based on Love’s first approximation theory. The generalized differential quadrature method is applied to solve the governing equations of motion and to obtain the natural frequencies of the shells for various boundary conditions. Applying the Halpin–Tsai model and the rule of mixture, the effective elastic modulus, the Poisson’s ratio and the density of nanocomposite shell reinforced with GPLs are computed. The effects of porosity coefficients, distribution patterns of porosity, GPL weight fraction, geometry and size of GPLs, semi-vertex angle as well as boundary conditions on the natural frequency of the system are analyzed. It was observed in the results that the shells with symmetric porosity distribution reinforced by graphene platelet pattern A predict the highest natural frequencies. Furthermore, it was found that the natural frequencies of nanocomposite conical shell can be decreased by increasing the porosity coefficient. Besides, the geometry and size of GPLs as well as weight fraction of GPLs have significant effects on the natural frequencies.

In this paper, flutter and divergence instabilities of functionally graded porous plate strip reinforced with graphene nanoplatelets in supersonic flow and subjected to an axial loading are studied. The graphene nanoplatelets are distributed in the matrix either uniformly or non-uniformly along the thickness direction. Four graphene nanoplatelets distribution patterns namely, Patterns A through D are considered. Based on the modified Halpin–Tsai micromechanics model and the rule of mixture, the effective material properties of functionally graded plate strip reinforced with graphene nanoplatelets are obtained. The aerodynamic pressure is considered in accordance with the quasi-steady supersonic piston theory. To transform the governing equations of motion to a general eigenvalue problem, the Galerkin method is employed. The flutter aerodynamic pressure and stability boundaries are determined by solving standard complex eigenvalue problem. The effects of graphene nanoplatelets distributions, graphene nanoplatelets weight fraction, geometry of graphene nanoplatelets, porosity coefficient and porosity distributions on the flutter and divergence instabilities of the system are studied. The results show that the plate strip with symmetric distribution pattern (stiffness in the surface areas) and GPLs pattern A predict the highest stable area. The flutter and divergence regions decrease as the porosity coefficient increases. Besides, the critical aerodynamic loads increase by adding a small amount of GPL to the matrix.

In this study, a novel nano-electromechanical system (NEMS) mass nanosensor made from a functionally graded porous (FGP) core bonded with piezo-electro-magnetic (PEM) layers is proposed to reveal the combined effect of FGP and PEM on the sensitivity performance of mass nanosensors. First, a theoretical model for this mass nanosensor attached with single/multiple nanoparticles is established via nonlocal strain gradient plate theory. Herein, the FGP core obeying the power-law and sigmoid-law gradient patterns is taken into account, and the inside porosity is considered as even and uneven distributions. Subsequently, the natural frequency shift (NFS) behavior of this mass nanosensor with different attached nanoparticles is investigated via Galerkin method. Finally, a comprehensive parametric analysis is performed to reveal the influence of inhomogeneity index, porosity distributed pattern and porosity volume fraction of core material, size-dependent parameters, as well as the external electric voltage and magnetic potential on the NFS performance of the NEMS mass nanosensor. The obtained results have illustrated that combining PEM surface and FGP core can present significant improvement on the sensitivity of the NEMS mass nanosensor for detecting nanoparticles. The sandwich design strategy for the mass nanosensor proposed in this work would be highly valuable for designing high-performance mass nanosensor in biomedical and industrial applications.

The Bi₂O₃ sphere-like precursors were first synthesized through a simple hydrothermal reaction in the mixture of sodium cholate (SC) and hydrogen peroxide. Thermal decomposition of these precursors would result in the formation of the uniform porous Bi₂O₃ nanospheres with diameters of ca. 80 nm in air at 500°C. The amount of added H₂O₂ and the reaction time were found to play important roles in the formation of Bi₂O₃ sphere-like precursors. The as-prepared porous Bi₂O₃ nanospheres exhibited a very excellent photocatalytic activity for the degradation of rhodamine B (RB) and methyl blue (MB) dyes under visible-light irradiation, which could be attributed to their narrow band gap and high surface area.

Metal titanates have been considered as one of the most promising materials for supercapacitors because of their excellent properties. In this work, porous lithium titanate (Li₂TiO₃) nanomaterials were prepared by sol–gel method using lithiumhydroxide hydrate and tetrabutyl titanate as precursors and polystyrene spheres as a template. The Brunauer-Emmett-Teller (BET) result revealed a large specific surface area of the Li₂TiO₃ nanomaterials. More importantly, the porous Li₂TiO₃ nanomaterials were examined as the electrode materials of supercapacitors. Such porous Li₂TiO₃ nanomaterials’ electrode exhibited a specific capacitance of 195Fg${}^{-1}$ at a current density of 1Ag${}^{-1}$ with a capacity retention of 96.3% after 5000 cycles in 3M KOH aqueous electrolyte. These superior results indicate that the porous Li₂TiO₃ nanomaterials are excellent materials for high-performance energy storage devices.

A hierarchical carbon material containing nanopores (micropores and mesopores) and micrometric sized capillaries (macropores) is produced using a combination of hard and soft templates. The hard template is a polypropylene (PP) cloth which decomposes during pyrolysis leaving a macroporous structure. The soft template is a cationic polyelectrolyte which stabilizes the resorcinol/formaldehyde (RF) resin porous structure during drying to give a nanoporous RF resin. The method produces a nanocomposite of the porous RF resin with an imbibed PP cloth. The composite is then pyrolyzed in a inert gas atmosphere to render a carbon material having macropores as well as micro/mesopores. The material exhibits both a large surface area (S_BET = 742 ± 2 m²/g) due to nanopores and goof fluid permeability due to micrometric sized pores. The macropores can be oriented during fabrication. The nanoporous surface can be used to support metal nanoparticles for fuel cell while the macropores allow easy flux of gas and liquids through the monolithic material.