Semarak International Journal of Nanotechnology

Synthesized Hybrid CNT Polymer Composite in Reducing EMI Pollution at Gigahertz Frequency Range

Mon, 10 Jun 2024 00:00:00 +0000

Modern digital systems are seriously impacted by the electromagnetic (EM) danger caused by various EM wave that interfere one another, either internally or externally. The electromagnetic interference (EMI) pollution has become an attention among researchers since it not only affects the devices, but also affecting human and biological systems. Thus, synthesizing an EM wave absorber that able to absorb the unwanted EM wave signal is crucial. This research highlight on the materials’ properties and characterization of the synthesized nanometer size hybrid Carbon Nanotubes (CNTs) of individual ferrite (Ni_0.5Zn_0.5Fe₂O₄ or Carbonyl iron) and mixed ferrite (Ni_0.5Zn_0.5Fe₂O₄ + Carbonyl iron) as catalyst to grow CNTs by using Chemical Vapour Deposition (CVD) method. The synthesized hybrid CNTs used as fillers were mixed with epoxy resin and hardener as the matrix at certain ratio of thickness fixed at 1 mm, 2 mm, and 3 mm. The hybrid CNTs was analysed by using X-ray diffractometer (XRD), a Field emission Scanning Electron Microscope (FeSEM) and RAMAN spectrometer to determine the phase formation, microstructural and structural analysis respectively. On the other hand, the Vector Network Analyzer (VNA) measured at 8 to 18 GHz frequency range was used to measure and analyse the microwave characterization. The phase analysis confirmed the existence of Carbon and Iron Carbide, whereas the microstructural shows the synthesized hybrid CNTs are mostly straight like, twisted and spiral fiber. Moreover, the structural analysis shows more defective structure with the formation of multiwalled CNTs that helps in absorbing the EM wave. The reflection loss (RL) of the growth individual Ni_0.5Zn_0.5Fe₂O₄ and Carbonyl Iron shows the RL value of -18 dB and -15 dB of thickness 2 mm respectively. The RL result also show improvement in the RL values for the growth of mixed ferrite with RL reach until -26 dB (thickness=3mm). Consequently, it indicates that using both single and mixed ferrite as a catalyst to grow CNT produces better EM wave performance appropriate for various applications.

Porosity and Slip Velocity Effects on MHD Pulsatile Casson Fluid in a Cylinder

Wan Faezah Wan Azmi, Ahmad Qushairi Mohamad, Lim Yeou Jiann, Sharidan Shafie — Mon, 10 Jun 2024 00:00:00 +0000

Numerous researchers have extensively numerically investigated Casson fluid flow in a slip cylinder, resembling blood flow in human arteries. However, no study has successfully derived an analytical solution to validate the accuracy of the complex mathematical models obtained through numerical methods. This study focuses on utilizing Casson fluid to model blood flow in arteries with diameters ranging from 130 to 1300μm by analytical approach. The considered slip velocity is significant, closely mimicking challenges in real-world blood flow applications. Additionally, this research addresses the influence of magnetohydrodynamics (MHD), a porous medium simulating cholesterol plaque, and pulsatile pressure gradients simulating the rhythmic contraction of the heart. The problem is tackled using dual methods, incorporating Laplace and finite Hankel transform techniques. These techniques leverage versatile integral transformations to analytically resolve boundary value problems associated with time and cylindrical domains. The noteworthy outcomes emphasize that blood flow escalates with increasing slip velocity and pulsatile pressure gradient. This phenomenon is attributed to the increased velocity gradient between blood particles and the solid boundary as slip velocity rises. Furthermore, an elevated pressure gradient in blood flow leads to an increased force within blood vessels, directly accelerating blood flow. These findings are essential for addressing mathematical challenges related to blood diseases.

Flow and Heat Transfer Analysis of Hybrid Nanofluid over a Rotating Disk with a Uniform Shrinking Rate in the Radial Direction: Dual Solutions

Mon, 10 Jun 2024 00:00:00 +0000

Rotating machinery, gas turbine rotators, and air cleaning equipment are some industrial and electronic applications of hybrid nanofluids as heat transfer fluids. Considering these potential applications, the axisymmetric flow of a hybrid nanofluid towards a permeable rotating disk with a uniform shrinking rate is analysed in the current study. Nonlinear ordinary differential equations and boundary conditions are generated, using Von Kármán’s transformations, from the governing partial differential equations and boundary conditions. Then, a sophisticated bvp4c solver containing finite difference code is utilized for solving the boundary value problem numerically. Following the discovery of dual solutions, stability analysis is performed, and only the first solution is stable. Besides that, the magnitude of the local skin friction coefficient is found to increase with the rise of shrinking and injection parameters. However, the augmentation of the shrinking and injection parameters reduces and enhances the local Nusselt number. Meanwhile, the enhancement of injection parameter is observed to reduce the hybrid nanofluid’s momentum and thermal boundary layer thickness.

Mxene and Strontium Titanate Hybrid Casson Nanofluid with CMC Base via the Caputo-Fabrizio Fractional Derivative over a Vertical Riga Plate

Mon, 10 Jun 2024 00:00:00 +0000

Mxene nanoparticles possess desirable properties such as high electrical conductivity, aqueous stability, and thermal stability, making them highly sought-after in various fields including manufacturing, renewable energy, and chemical engineering. Similarly, Strontium Titanate (SrTiO₃) is a versatile material with high electrical conductivity and low thermal expansion properties, applicable in electronics, solar energy, and biomedical engineering. This study aims to investigate the effects of a hybrid nanofluid consisting of Mxene and Strontium Titanate in a Carboxymethyl Cellulose (CMC) base, using the Caputo-Fabrizio fractional derivative, over a Riga plate. The fractional derivative is a concept with future applications, while Riga plates act as actuators for fluid flow in marine vessels. Laplace transform is used to find solutions from the governing PDEs, analytically. The resulting integral solution is analysed graphically and numerically. According to the study, a rise in the fractional parameter, α, causes an increase in fluid temperature and velocity. Because of the unique features of SrTiO₃, the thermal radiation parameter N has a distinct effect on velocity and temperature. As N increases, the temperature rises but velocity declines. Due to the high electrical conductivity of Mxene and SrTiO₃, the modified Hartmann number, E, favourably influences velocity. Skin friction increases due to SrTiO₃whereas the Nusselt number falls with increasing N due to CMC base characteristics.