Machining of metal-matrix composites (MMCs) is difficult owing to their superior characteristics compared with the their parent materials. A specific application of modern laser technology is the drilling of cooling holes in aircraft engine 'hot-end components' such as combustion chambers, nozzle guide vanes, and turbine blades, which are made up of MMCs. Laser-drilled holes in aero-engine components must comply with strict quality standards that determine them suitable for in-service use. The current paper presents an effective approach for the optimization of neodymium-yttrium aluminium garnet (Nd:YAG) laser drilling of aluminium matrix/silicon carbide particulate (Al/SiC p ) MMCs in regard to multiple characteristics, i.e. taper, spatter, and heat-affected zone (HAZ), based on response surface methodology and grey relational grades. Twenty runs based on the response surface methodology are performed to determine factorial interactions and decide the best factor level settings. In addition to response surface methodology, grey relational grades and desirability functions are used for multiple response optimizations. Laser drilling parameters such as pulse width and number of pulses, and MMC parameters like concentration of SiC p , are optimized with consideration to taper, spatter, and HAZ. By analysing the grey relational grade, optimal parametric settings for various responses are determined.

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Red blood cells (RBCs) are the most abundant cell types in the circulatory system of vertebrates. In fish, RBCs retain their nuclei throughout their lifetime and remain transcriptionally and translationally active. While their primary function is typically associated with gas exchange, recent reports indicate that nucleated red blood cells can play a significant role in regulating the body's innate immune response. The current article describes the innate immune role of red blood cells in rohu (Labeo rohita), a freshwater fish species that holds significant commercial importance in India and South‐East Asian nations. From the whole blood and mucosal surface RBCs have been isolated through density gradient centrifugation with HiSep™LSM 1077 (density 1.007 ± 0.0010) and their purity has been confirmed by the Giemsa staining followed by microscopical observations. Toll‐like receptors (TLR2, 3, 4, 5) and nucleotide oligomerization domain (NOD)‐like receptors (NOD1 and NOD2) in RBCs of rohu fingerlings were observed to be significantly activated (P < 0.05) on infection with Aeromonas hydrophila and Edwardsiella tarda. This activation resulted in increased expression of interleukins (IL‐8, IL‐1β) and interferon (IFN)‐I genes. The activation of TLR4, NOD1 and NOD2, as well as the expression of interleukins and IFN‐I genes have been observed in both in vivo and in vitro stimulation of rohu RBCs with lipopolysaccharides. These findings highlight the importance of fish RBCs in enhancing innate immunity against various pathogenic invasions in rohu.

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