Efficient machinery operation relies on the performance of high-quality lubricants. Currently, mineral oils of different grades are widely employed for lubricating machine components, but their environmental impact is a concern. Biolubricants are potential alternatives to mineral oils due to environmental factors. The present study focuses on assessing the rheological characteristics of SiO₂ nanoparticle (NP)-enhanced ecofriendly biolubricants for near zero and high-temperature conditions. Pure neem oil, pure castor oil and a 50:50 blend of both oils were considered as the base oils. Nanobiolubricants with enhanced dispersion stability were prepared for varied concentrations of NPs using an ultrasonification method. Viscosity analysis was conducted using an MCR-92 rheometer, employing the Herschel Bulkley model to precisely characterize the viscosity behavior of bio-oils. Due to the fluid–solid interaction between SiO₂ NPs and bio-oils, a crossover trend was observed in the flow curves generated for different base oils enriched with SiO₂ NPs. For neem oil, a significant increase in viscosity was noted for 0.2 wt% of NPs. Using the multilayer perceptron (MLP) algorithm, an artificial neural network (ANN) model was developed to accurately predict the viscosity variations in nanobiolubricants. The accuracy of the predicted values was affirmed through experimental investigations at the considered nanoSiO₂ weight concentrations.

Nanoparticle applications have revolutionized tribological aspects and provided innovative answers to age-old questions of friction, wear, and lubrication. With their unique physico-chemical properties in terms of their high surfaces, tunable sizes, and shape, nanoparticles can be used to achieve much better lubrication with lower friction and wear resistance. Nanoparticles are additives to lubricants, fillers for composite coatings, and agents for surface modification, providing much better tribological performance than conventional materials. Advancements in the synthesis and functionalization of nanoparticles have expanded their applicability beyond automotive and aerospace engineering to many areas of manufacturing. Thus, this review makes comprehensive coverage of nanoparticles in tribology, including action mechanisms with a focus on lubrication enhancement, surface modification, reduction of friction, and improvement of wear resistance. The review touches on current problematic issues, such as environmental and cost-effectiveness, while exploring research and development opportunities in this rapidly emerging domain. Graphical Abstract

Cowpea seed-derived CQDs enhance the tribological and thermal properties of Pongamia oil bio-lubricant by reducing friction and wear. Thus, demonstrating their potential as sustainable nano-additives for green lubrication.

Mild steel is extensively employed in various industries due to its affordability and versatility. However, its susceptibility to corrosion poses a significant challenge. This study explores the efficacy of protecting mild steel by applying coatings composed of highly noble copper and its alloys. In this direction, Ni–Cu alloy and Ni–Cu–Fe₂O₃ coating have been developed from a sulfate citrate bath on mild steel through the electrodeposition method. The alloy and composite coating deposition was done at different current densities 1 A dm⁻², 2 A dm⁻², 3 A dm⁻², and 4 A dm⁻². The copper content of the coating has increased with an increase in current density in both alloy and composite coatings. The deposit with a high Copper content showed lower crystallite size with a lower corrosion rate value at a current density of 3 A dm⁻². The trace addition of Fe₂O₃ into the Ni–Cu alloy matrix has improved the overall corrosion resistance of the mild steel materials as compared to bare Ni–Cu alloy coating.

Food additives are widely used to enhance food quality, safety, and shelf life; however, excessive or unauthorized use may pose health risks, requiring accurate and continuous monitoring. Conventional analytical techniques such as chromatography and spectroscopy provide high sensitivity but often involve complex sample preparation, expensive instrumentation, and skilled personnel, limiting rapid and on-site analysis. Electrochemical sensing has emerged as an effective alternative due to its simplicity, low cost, rapid response, portability, and high sensitivity. This review presents electrochemical sensing strategies for food additive detection, emphasizing nanomaterial-enabled performance enhancement. The classification of food additives, health impacts, and regulatory aspects are discussed, followed by fundamental electrochemical sensing principles. The influence of nanomaterial properties on electrocatalytic activity, sensitivity, and selectivity is examined. Recent advances in nanomaterial-based electrochemical sensors for detecting food additives, including colorants, preservatives, antioxidants, and flavoring agents, as well as selected food contaminants relevant to food safety, are summarized, highlighting fabrication strategies, analytical performance, and real-sample applications.