Background and aims The world is currently facing multifaceted problems due to the emergence of the COVID-19 (coronavirus) pandemic. Blockchain technology (BT) plays a vital role in creating a platform for adequately managing the COVID-19 pandemic. Methods The latest information on the blockchain and its application in solving challenging problems due to the COVID-19 pandemic are collected and discussed from the available literature searched through PubMed, Scopus, and Google scholar. Results In this paper, we propose a blockchain-based platform to combat this pandemic. Furthermore, we have identified and discussed nine significant applications of blockchain in solving the problem arising from the COVID-19 pandemic. Conclusions The severity of COVID-19 was so tremendous that the World Health Organization (WHO) had to declare it as a pandemic within a month of its full-scale expansion. The greatest challenge most governments are suffering from is the lack of a precise mechanism to detect the newly infected cases and predict coronavirus infection risk. So, we need a technologyempowered solution to fight during this COVID-19 crisis. The various features of blockchain technology, such as decentralization, transparency, and immutability, can help control this pandemic by early detection of outbreaks, fast-tracking drug delivery, and protecting user privacy during treatment. Keywords Blockchain technology (BT). COVID-19. Coronavirus. Healthcare Highlights • Blockchain technology (BT) provides a better platform for effective management of the COVID-19 pandemic. • Blockchain technology helps create decentralization, transparency, immutability, and early detection of infected cases. • Blockchain technology is useful for disease control, patient traceability, and improved management of the healthcare system.

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Weldability of heat-treatable 6061-T6 aluminum alloy results in deterioration of mechanical properties due to dissolution of strengthening precipitates in the nugget zone of friction stir welded joints. These properties were improved by addition of reinforcement particles in the weld joint line. In the present work, attempts were made to produce 6061-T6 Al-based nanocomposites using the friction stir welding process by incorporating titanium oxide nanoparticles into the aluminum matrix for microstructure refining of the nugget zone and prevent the grain growth in the heat-affected zone. The effect of addition of nanoparticles on the evolution of grains structure and mechanical behavior of friction stir welded samples based on different combinations of rotational and travel speed was studied and discussed. Results revealed that the unreinforced samples were successfully welded at both low and high heat inputs, whereas the reinforced samples are not feasible at tool rotational speed (ω) < 2000 r/min and transverse speed (v) > 70 mm/min, respectively. The significant refining of grains in the nugget zone is possible with addition of nanoparticles via the Zener-pinning effect. A more pronounced increment in tensile strength, microhardness, and wear properties was observed compared to sample without nanoparticles under the same processing parameters due to embedment of nano-sized particles in the weld nugget zone.

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Purpose This study aims to purpose the suitable location of slip boundary condition and microscale surface textures to enhance the tribological performance of the hydrodynamic journal bearings. Design/methodology/approach Mass conserving Elrod cavitation algorithm with considering slip boundary condition has been used for predicting the static performance characteristics (load carrying capacity, coefficient of friction and volumetric inflow rate) of finite cylindrical shape textured journal bearings. Findings It has been observed that the full textured bearing with slip boundary condition in between 0°–180° circumferential region gives a significant reduction in the lubricant rupture zone. However, the introduction of textures up to the interface of slip and the no-slip region is increasing the load-carrying capacity and reduces the shear stress. This reduction in shear stress with combined slip and surface textures is effective in increasing the volumetric inflow rate of the lubricant. Practical implications The combined effect of slip boundary condition and surface texturing is increasing the scope of liquid lubricants in hydrodynamic journal bearings and further contributing toward the development of small-scale rotating machines. Originality/value The study related to the use of mass conserving Elrod cavitation algorithm for finding the optimum location of slip and surface texture zones has been found rare in the literature. Previous studies show that the mass conserving Elrod cavitation algorithm gives realistic results for textured bearings and its findings show good agreement with the experimental observations.

The objective of the present study is to investigate the effect of Al 2 O 3 nanoparticles volume percentage on tribological, mechanical and microstructural characteristics of 6061-T6 aluminum alloy based particulate-nanocomposite (P-NCs) fabricated using friction stir welding (FSW) process. Optical microscopy (OM) and scanning electron microscopy (SEM) was employed to evaluate the (a) microstructures of the produced nanocomposites to ascertain the distribution of Al 2 O 3 nanoparticles in the nugget zone; (b) nanocomposite depth formed on Al-alloy matrix, and (c) fractured and wear characteristics. Results reveal that the produced P-NCs had a depth of 3286 mm across the perpendicular x-section of the weld nugget zone of P-NCs. With the increase in a volume percentage of Al 2 O 3 nanoparticles there was a tremendous increment in the microhardness up to 125 HV which is higher than as-received AA6061-T6. It was also noticed that the tensile strength and the wear resistance of produced P-NCs were significantly increased at 0.3 vol% of Al 2 O 3 nanoparticles as compared to 0.2 and 0.4 vol%. The corresponding mechanical and wear properties results were correlated to microstructure and fractography results.