Nanoparticles typically have dimensions of less than 100 nm. Scientists around the world have recently become interested in nanotechnology because of its potential applications in a wide range of fields, including catalysis, gas sensing, renewable energy, electronics, medicine, diagnostics, medication delivery, cosmetics, the construction industry, and the food industry. The sizes and forms of nanoparticles (NPs) are the primary determinants of their properties. Nanoparticles’ unique characteristics may be explored for use in electronics (transistors, LEDs, reusable catalysts), energy (oil recovery), medicine (imaging, tumor detection, drug administration), and more. For the aforementioned applications, the synthesis of nanoparticles with an appropriate size, structure, monodispersity, and morphology is essential. New procedures have been developed in nanotechnology that are safe for the environment and can be used to reliably create nanoparticles and nanomaterials. This research aims to illustrate top-down and bottom-up strategies for nanomaterial production, and numerous characterization methodologies, nanoparticle features, and sector-specific applications of nanotechnology.

The unsteady MHD free convection heat and mass transfer flow of a viscous, incompressible, and electrically conducting fluid passing through a vertical plate embedded in a porous medium in the presence of chemical reactions and thermal radiation is investigated. The effects of the Hall current, rotation and Soret are studied. Using the perturbation approach, one can obtain an accurate analytical solution to the governing equations for the fluid velocity, fluid temperature, and species concentration, provided that the initial and boundary conditions are acceptable. It is possible to obtain expressions for the shear stress, rate of heat transfer, and rate of mass transfer for both plates with the ramping temperature and isothermal conditions. On the one hand, the numerical values of the primary and secondary fluid velocities, fluid temperature, and species concentration are presented graphically. On the other hand, the numerical values of the shear stress and rate of mass transfer for the plate are presented in tabular form for various values of the relevant flow parameters. These values are given for a range of pertinent flow parameters. It was determined that an increase in the Hall and Soret parameters over the whole fluid area leads to a corresponding increase in the resulting velocity. The resultant velocity continually climbs to a high level due to the contributions of the thermal and solute buoyancy forces. Lowering the heat source parameter reduces the temperature distribution, resulting in a lower overall temperature. When there is a rise in the chemical reaction parameter over the whole fluid area, there is a corresponding decrease in the concentration. The concentration buoyancy force, Hall current, and Prandtl number reduce the skin friction. On the other hand, the permeability of the porous medium, rotation, chemical reaction, the Soret number, thermal buoyancy force, and mass diffusion all have the opposite effects on the skin friction.

The complete lifting of travel restrictions to KSA takes place after 3rd of January 2021.There are fears that KSA will confront a new COVID-19 wave, especially when the most of countries that resumed the international flights are suffering now from the second surge. Fortunately, more than one Covid-19 Vaccine have been rolled out. However, herd immunity could be reached only through widespread vaccination. COVID-19 vaccines need more time to be properly protective, especially in front of people refusing to get vaccinated. A modified multi-stage SEIR model, with distinct reproductive numbers corresponding to before and after lockdown is employed to predict the potential of a new pandemic wave. First, the two-stage model employed to find the best fitting for the reproductive numbers. Then, the model is extended to three-stage one to investigate the relaxation. However, the modified model detects a second wave in early stage from 28th May to 17th June 2020 before even succeeding controlling the first outbreak. Subsequently, the four-stage SEIR model is used to predict the end of the second wave. Moreover, the model is employed to test the potential of a new pandemic surge after the international flights are resumed.

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The impact of SiO2 and B4C on mechanical and morphological studies of Sansevieria trifasciata fiber (STF) reinforced in polyester composites is investigated in this study. STF fibers are reinforced with polyester composites with the addition ceramic fillers such as SiO2 and B4C in various weight fractions to improve tensile, flexural, and impact characteristics. The morphological properties are studied with the help of scanning electron microscopy (SEM). The improved mechanical properties were tensile strength (44.92 MPa), flexural strength (103.58 MPa), and impact strength (27.4 kJ/m2) obtained for 20 wt.% STF fiber and 15 wt.% SiO2 reinforcement with the polyester matrix. The mechanical characteristics of the composites were significantly influenced by increasing SiO2 up to 15 wt.%.