Structural, magnetic and electrical properties of Al substituted Ni-Zn ferrite nanoparticles

Nanocrystalline ferrite materials having the general formula Ni_0.7Zn_0.3Fe_2−xAl_xO₄ (0.0 ≤ x ≤ 0.5) have been synthesized by citrate-gel auto combustion method and characterized using X-ray diffraction (XRD), energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), dc magnetization, dielectric and impedance spectroscopy measurements. XRD studies confirm that all the samples show single phase cubic spinel structure. The crystallite size of Ni_0.7Zn_0.3Fe_2−xAl_xO₄ (0.0 ≤ x ≤ 0.5) nanoparticles calculated using the Debye-Scherrer formula was found in the range of 13-17 nm. The value of lattice parameter ‘a’ is found to decrease with increasing Al³⁺ content. EDX patterns confirm the compositional formation of the synthesized samples. FE-SEM micrographs show that all the samples have nano-crystalline behavior and particles show spherical shape. The variation of dielectric properties ?′,?″, and tan δ with frequency shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop's phenomenological theory. The dc magnetization studies infer that magnetic moment of Ni_0.7Zn_0.3Fe_2−xAl_xO₄ (0.0 ≤ x ≤ 0.5) nanoparticles was found to decrease with Al doping. Impedance spectroscopy techniques have been used to investigate the effect of grain and grain boundary on the electrical properties of the synthesized compounds.     

Management of natural gas resources and search for alternative renewable energy resources: A case study of Pakistan

Energy usage in Pakistan has increased rapidly in past few years due to increase in economic growth. Inadequate and inconsistent supply of energy has created pressure on the industrial and commercial sectors of Pakistan and has also affected environment. Demand has already exceeded supply and load shedding has become common phenomenon. Due to excessive consumption of energy resources it would become difficult to meet future energy demands. This necessitates proper management of existing and exploration of new energy resources. Energy resource management is highly dependent on the supply and demand pattern. This paper highlights the future demands, production and supply of energy produced from natural gas based on economic and environmental constraints in Pakistan with special emphasis on management of natural gas. An attempt has been made by proposing a suitable course of action to meet the rising gas demand. A mechanism has been proposed to evaluate Pakistan's future gas demand through quantitative analysis of base, worst and best/chosen option. CO₂ emission for all cases has also been evaluated. The potential, constraints and possible solutions to develop alternative renewable energy resources in the country have also been discussed. This work will be fruitful for the decision makers responsible for energy planning of the country. This work is not only helpful for Pakistan but is equally important to other developing countries to manage their energy resources.     

Facile CO2 Separation in Composite Membranes

CO₂ emission from anthropogenic sources has raised worldwide environmental concerns and hence proficient energy paradigm has tilted towards CO₂ capture. Membrane technology is one of the efficient technologies for CO₂ separation since it is environmentally friendly, inexpensive, and offers high surface areas. Various approaches are discussed to improve membrane performance focusing mainly on permeability and selectivity parameters. Different types of fillers are incorporated to reach the Robeson's upper bound curve. In this review, polymer‐inorganic nanocomposite membranes for the separation of CO₂, CH₄, and N₂ from various gas mixtures are comprehensively discussed. Metal organic frameworks (MOFs) and ionic liquid (ILs) mixed‐matrix membranes are also considered.     

Preparation and Characterization of Organically Modified Montmorillonite-Filled High Density Polyethylene/Hydroxyapatite Nanocomposites for Biomedical Applications

The study investigated the introduction of organically modified montmorillonite (MMT) in high density polyethylene/hydroxyapatite (HDPE/HA) composites for biomedical applications. The addition of HA and MMT increased the strength and stiffness of HDPE/HA composites with deterioration in impact strength and elongation at break values. XRD and TEM analysis provided evidence of exfoliated MMT layers in HDPE/HA composites and the MMT layers remained exfoliated even with further addition of HA. Simulated body fluid (SBF) analysis revealed that the size of apatite layer increased with increasing immersion time and the formation of apatite layers on the surface of composites indicates excellent biocompatibility properties.     

Maleated High Density Polyethylene Compatibilized High Density Polyethylene/Hydroxyapatite Composites for Biomedical Applications: Properties and Characterization

The study investigated the use of maleated high density polyethylene (mHDPE) as a compatibilizer in high density polyethylene/hydroxyapatite (HDPE/HA) composites for biomedical applications. The addition of HA increased the strength and stiffness of HDPE/HA composites while the use of mHDPE in HDPE/HA composites improved its elongation at break values. The SEM images revealed that the addition of mHDPE has induced the formation of HDPE fibrils in mHDPE/HA composites. The size of apatite layer increased with simulated body fluid (SBF) immersion time and the formation of apatite layers on the surface of composites indicates excellent biocompatibility properties.     

Thermally radiative slip flow of viscous fluid through a microfluidic vessel having sinusoidal walls with variable viscosity

This article explores the influence of variable viscosity on the peristaltic movement of viscous fluid through a tapered microfluidic vessel having sinusoidal walls. The aspect of slip velocity has been considered on the channel walls. Furthermore, the heat transfer phenomenon is explored under the effectiveness of thermal radiation and viscous dissipation. The nonlinearity of the problem is scrutinized by the lubrication approximation hypothesis. Analytic outcomes have been acquired for liquid velocity, temperature, pressure rise, and streamlines. The impact of dissimilar physical parameters influencing the liquid flow features is revealed and deliberated through graphs. The study revealed that the velocity at the central region diminishes with increasing values of the velocity slip parameter. The number of boluses in the streamlines pattern is enhanced by enhancing the viscosity parameter. The current model has been used in bio-engineering processes, industrial fluid mechanics, thermal processing, and cooling systems.     

Experimental and thermodynamic studies of the catalytic partial oxidation of model biogas using a plasma-assisted gliding arc reactor

The present work is an investigation of the influence of process conditions on the production of synthesis gas (H₂ and CO) from model biogas (molar ratio of CH₄/CO₂ = 60/40) through partial oxidation over a granular Ni-based catalyst. The investigations were performed in a partially adiabatic plasma-assisted (non-thermal) Gliding Arc (GlidArc) reactor in a transitional flow regime at a fixed pressure (1 bar) and electric power (0.3 kW). The emphasis of this investigation was on an experimental study and a comparative thermodynamic analysis. The equilibrium compositions were calculated using a Lagrange multiplier and resulted in the development of systems of non-linear algebraic equations, which were solved numerically using the MATLAB^® function “fmincon”. Two cases were studied: normal air (molar ratio of O₂/N₂ = 21/79) and enriched air (O₂/N₂ = 40/60). The individual effects of the O₂/CH₄ molar ratio and the bed exit temperature (T_exit) were studied in both cases. The main trends of the CH₄ conversion, the synthesis gas yield, the H₂/CO ratio and the thermal efficiency of the reactor were analyzed, and it was shown that any deviations from equilibrium could be explained by temperature gradients and irregular gas flows. The results of this study revealed that CO₂ could be used as a neutral gas in this process. When normal air was used, an O₂/CH₄ molar ratio of 0.66, a gas hour space velocity (GHSV) of 1.26 NL/g_cat/h, a maximal temperature (T_max) of 870 °C and an exit temperature (T_exit) of 630 °C were found to be optimal parameters, and when enriched air was used, these ideal parameters were an O₂/CH₄ molar ratio of 0.64, a GHSV of 0.86 NL/g_cat/h, a T_max of 860 °C and a T_exit of 635 °C.     

Bio-Inspired Computational Methods for the Polio Virus Epidemic Model

In 2021, most of the developing countries are fighting polio, and parents are concerned with the disabling of their children. Poliovirus transmits from person to person, which can infect the spinal cord, and paralyzes the parts of the body within a matter of hours. According to the World Health Organization (WHO), 18 million currently healthy people could have been paralyzed by the virus during 1988–2020. Almost all countries but Pakistan, Afghanistan, and a few more have been declared polio-free. The mathematical modeling of poliovirus is studied in the population by categorizing it as susceptible individuals (S), exposed individuals (E), infected individuals (I), and recovered individuals (R). In this study, we study the fundamental properties such as positivity and boundedness of the model. We also rigorously study the model’s stability and equilibria with or without poliovirus. For numerical study, we design the Euler, Runge–Kutta, and nonstandard finite difference method. However, the standard techniques are time-dependent and fail to present the results for an extended period. The nonstandard finite difference method works well to study disease dynamics for a long time without any constraints. Finally, the results of different methods are compared to prove their effectiveness.