Applications: The nanofluids and their upgraded version (ternary and tetra nanofluids) have a very rich thermal mechanism and convinced engineers and industrialist because of their dominant characteristics. These broadly use in chemical, applied thermal, mechanical engineering, and biotechnology. Particularly, heat transfer over a cylindrical surface is important in automobiles and heavy machinery. Purpose and Methodology: Keeping in front the heat transfer applications, a model for Tetra-Composite Nanofluid [(Al₂O₃-CuO-TiO₂-Ag)/water]_tetra is developed over a vertically oriented cylinder in this study. The existing traditional model was modified with innovative effects of nonlinear thermal radiations, magnetic field, absorber surface of the cylinder, and effective thermophysical characteristics of tetra nanofluid. Then, a new heat transfer model was achieved successfully after performing some mathematical operations. Major Findings: The mathematical analysis was performed via RK and determined the results graphically. The study gives suitable parametric ranges for high thermal efficiency and fluid movement. Applied magnetics forces were observed excellent to control the fluid motion, whereas curvature and buoyancy forces favor the motion. Thermal mechanism in Tetra nanofluid is dominant over ternary nanoliquid and nonlinear thermal radiations increased the heat transfer rate.

Polymeric nanocomposites have been outstanding functional materials and have garnered immense attention as sustainable materials to address multi-disciplinary problems. MXenes have emerged as a newer class of 2D materials that produce metallic conductivity upon interaction with hydrophilic species, and their delamination affords monolayer nanoplatelets of a thickness of about one nm and a side size in the micrometer range. Delaminated MXene has a high aspect ratio, making it an alluring nanofiller for multifunctional polymer nanocomposites. Herein, we have classified and discussed the structure, properties and application of major polysaccharide-based electroactive hydrogels (hyaluronic acid (HA), alginate sodium (SA), chitosan (CS) and cellulose) in biomedical applications, starting with the brief historical account of MXene’s development followed by successive discussions on the synthesis methods, structures and properties of nanocomposites encompassing polysaccharides and MXenes, including their biomedical applications, cytotoxicity and biocompatibility aspects. Finally, the MXenes and their utility in the biomedical arena is deliberated with an eye on potential opportunities and challenges anticipated for them in the future, thus promoting their multifaceted applications.

Despite the extensive use of carbon steel in all industrial sectors, particularly in the petroleum industry, its low corrosion resistance is an ongoing problem for these industries. In the current work, two malonyl dihydrazide derivatives, namely 2,2’-malonylbis (N-phenylhydrazine-1-carbothiamide (MBC) and N’1, N’3-bis(-2-hydroxybenzylidene) malonohydrazide (HBM), were examined as inhibitors for the carbon steel corrosion in 1.0 M HCl. Both MBC and HBM were characterised using thin-layer chromatography, elemental analysis, infrared spectroscopy, and nuclear magnetic resonance techniques. The corrosion tests were performed using mass loss measurements, polarisation curves, and electrochemical impedance spectroscopy. It is obtained from the mass loss studies that the optimal concentration for both inhibitors is 2.0 × 10⁻⁵ mol/L, and the inhibition efficiencies reached up to 90.7% and 84.5% for MBC and HBM, respectively. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) indicate an increased impedance in the presence of both MBC and HBM and mixed-type inhibitors, respectively. Both inhibitors can mitigate corrosion in the range of 298–328 K. Values of free energy changes obtained from the Langmuir model suggest that the inhibitors suppress the corrosion process principally by chemisorption. The computational investigations were conducted to identify the factors connected with the anti-corrosive properties of the examined inhibitors.

The study of variety of Newtonian nanofluids subject to various physical model parameters gained much interest of engineers and scientists. Owing to their coolant and absorption characteristics, these are broadly found in chemical engineering, biomedical engineering (expansion and contraction of veins and arteries), detection of cancer cells through magnetic nanoparticles, microchips, and particularly in petroleum industry. This study focuses on investigation of nanofluid heat transfer applications inside a channel formed by expanding/contracting walls. A new heat transport model is introduced by adding the effects of nanoparticles and molecular diameters, thermal radiations, and walls permeability. Then, numerical code for the model is developed and executed to analyze the dynamics of the model from physical aspects. For expanding (${\alpha }_1 = 1.0,2.0,3.0,4.0$) and contracting (${\alpha }_1 = - 1.0, - 2.0, - 3.0, - 4.0$) walls, the velocity is examined maximum in the channel center. However, the fluid movement in the working domain is in reverse proportion for ${Re} = 1.0,3.0,5.0,7.0$. Further, high absorbent walls (${A}_1 = 0.1,0.3,0.5,0.7$) controlled the motion for both ${\alpha }_1 > 0$ and ${\alpha }_1 < 0$, respectively. The addition of thermal radiation number ${Rd} = 0.1,0.3,0.5,0.7$ played the role of catalytic parameter which imperatively increased the fluid temperature. Further, contracting walls and temperature ratio number ${\theta }_r = 0.1,0.3,0.5,0.7$ reduced the temperature and this decrease is rapid in conventional fluid.

Applications: Flow-through permeable media have a wide range of applications in biomedical engineering, geophysical fluid dynamics, and recovery and refinement of underground reservoirs and large-scale chemical applications such as filters, catalysts, and adsorbents. Therefore, this study on a nanoliquid in a permeable channel is conducted under physical constraints. Purpose and Methodology: The key purpose of this research is to introduce a new biohybrid nanofluid model (BHNFM) with (Ag-G)_{hybridnanoparticles} with additional significant physical effects of quadratic radiation, resistive heating, and magnetic field. The flow configuration is set between the expanding/contracting channels, which has broad applications, especially in biomedical engineering. The modified BHNFM was achieved after the implementation of the bitransformative scheme, and then to obtain physical results of the model, the variational iteration method was applied. Core Findings: Based on a thorough observation of the presented results, it is determined that the biohybrid nanofluid (BHNF) is more effective than mono-nano BHNFs in controlling fluid movement. The desired fluid movement for practical purposes can be achieved by varying the wall contraction number (α₁ = -0.5, -1.0, -1.5, -2.0) and with stronger magnetic effects (M = 1.0,9.0,17.0,25.0). Furthermore, increasing the number of pores on the surface of the wall causes the BHNF particles to move very slowly. The temperature of the BHNF is affected by the quadratic radiation (R_d), heating source (Q₁), and temperature ratio number (θ_r), and this is a dependable approach to acquire a significant amount of heat. The findings of the current study can aid in a better understanding of parametric predictions in order to produce exceptional heat transfer in BHNFs and suitable parametric ranges to control fluid flow inside the working area. The model results would also be useful for individuals working in the fields of blood dynamics and biomedical engineering.