Over a long time, non-steroidal anti-inflammatory drugs (NSAIDs) play a vital role in medical field. Indomethacin is a NSAID mainly used against inflammation and pain. But the poor solubility of indomethacin limits its therapeutic usage. Hydrotropy is a solubilization technique used to enhance the drug solubilization. Microscopic solvent effect is considered to be a part of hydrotropy in which hydrogen bond (H-bond) networks are formed with an isolated molecule with solvent molecules such as water. A comprehensive theoretical investigation was performed under density functional theory (DFT) to explore the isolated and monohydrated indomethacin complexes. The geometries were optimized on B3LYP method with 6-311G (2d,2p) basis set. The interaction energies of hydrated indomethacin complexes were computed by correcting the basis set superposition error. Natural bond orbital (NBO) study was performed in order to deepen the knowledge on O-H···O and C-H···O type H-bonds. A linear relationship between H-bond length and the stabilization energy (E(2))was observed in the solvated indomethacin complexes with a correlation coefficient of 0.8346. It identifies maximum E(2) (95.33 Kcal/mol) in INDO-12 complex. The molecular electrostatic potential mapping (MESP) for the optimized structures was also analyzed.

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The main objective of this study is to investigate the influence of the tool rotation speed (TRS) and tool traverse speed (TTS) on the microstructure, microhardness and the tensile strength of the copper – MWCNT welded joints. MWCNT particles were successfully incorporated in the weld zone of the copper plate through the holes drilled at the sides of the abutting copper plates. The joints were welded using a tool with tapered cylindrical pin profile. The TRS was varied between 1200 and 1300 rpm. The TTS was varied between 50 mm/min and 100 mm/min. The parametric limits were fixed based on the trial runs conducted for obtaining defect free welds. The defect free welds were evaluated for microhardness in the nugget zone as per ASTM E384. The tensile strength of the joints was tested as per ASME Section IX-2019. Microstructural investigations revealed the formation of intercalated banded structures indicating homogeneous mixing and distribution of MWCNTs in the copper matrix. Maximum tensile strength of 175 MPa was achieved for the joint fabricated with 1200 rpm TRS and TTS of 30 mm/min. Weldment with maximum microhardness of 100.21 Hv was achieved for the same combination of process parameters. The sample processed at a higher TRS of 1300 rpm and lower TTS of 20 mm/min yielded the second best tensile and microhardness. The tensile strength of the welded joints was observed to increase with increasing the TTS and the TRS.