Faculty Publications

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Effect of Temperature on Solid-State Reaction of Prawn Shell-Derived Phase-Pure β-Tricalcium Phosphate
(Springer, 2024) Satish, P.; Praveen, L.L.; Gautam, V.; Hadagalli, K.; Mandal, S.
Over the past three decades, bioresorbable ceramics such as beta-tricalcium phosphate (β-TCP)-based porous scaffolds have been extensively studied. β-TCP-based scaffolds or cements for bone tissue applications have proved to be an outstanding alternative to repair and regenerate bone tissue defects caused by trauma or injury. In this study, an investigation on submicron β-TCP powders derived from prawn shell (Fenneropenaeus indicus, a source of marine biowaste) via solid-state reaction approach was carried out, which has calcite (CaCO3) in its exoskeleton (nonedible). The prawn shell-derived β-TCP can be prepared conventionally with dicalcium phosphate (CaHPO4) at different temperatures 900, 1000, 1100, and 1200 °C. The EDX spectra detect the Ca:P ratio of 1.5 confirming the formation of pure β-TCP at 1100 °C, which is in complete agreement with theoretical ratio. X-ray diffraction pattern revealed the phase-pure crystalline rhombohedral crystal structure of β-TCP with an average crystallite size of ~ 25.8 nm, prepared at 1100 °C. The field emission scanning electron microscopy images showed a homogeneous distribution of β-TCP powders with an average grain size of 3.07 µm at 1100 °C. Furthermore, Raman spectroscopy and Fourier transform infrared spectroscopy confirm the characteristics peaks of β-TCP. Differential scanning calorimetry and thermogravimetric analysis are performed to study the thermal behavior of the initial precursors mixture to synthesize β-TCP. β-TCP scaffolds sintered at 1100 °C exhibited compressive strength of ~ 6.2 MPa, for which Ca/P ratio is 1.51. Biodegradation study conducted on β-TCP scaffolds sintered at 1100 °C has shown slow degradation rate up to 5 days. Therefore, the prawn shell-derived β-TCP has physical and morphological properties which projects it as a promising implantable biomaterial for synthetic bone graft substitutes. © ASM International 2024.
A comparative analysis of crustacean exoskeletons: structural, microstructural, morphological, and UV absorption studies
(Institute of Physics, 2024) Nowl, M.S.; Praveen, L.L.; Ambili, V.; Singh, S.; Samad, U.; Seikh, A.H.; Dutta, S.; Mandal, S.
This study aims to investigate the structural, thermal, and spectral characteristics, along with the ultra-violet (UV) absorption of various marine benthos exoskeletons, such as various species of crabs (Portunus sanguinolentus, Portunus pelagicus, Charybdis feriata) and mantis shrimp (Oratosquilla oratoria). Their unique properties and ability to survive in harsh oceanic environments make them interesting research subjects. This research utilized powder x-ray diffraction (XRD) analysis to determine the crystal structure of the benthic varieties. The sample surface was analyzed using high-resolution micrographs obtained from field-emission scanning electron microscopy (FESEM), which identified the presence of chitin and calcite in the marine benthos. This was further confirmed by differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The optical characteristics were investigated using UV-visible spectroscopy. The proximate analysis revealed high protein content in the mantis shrimp exoskeleton compared to other crab species, highlighting its excellent UV absorption characteristics. Overall, this research has the potential to broaden our understanding of marine organisms, which can have potential applications in biotechnology and materials science to develop nature-inspired innovative materials sustainably. © 2024 The Author(s). Published by IOP Publishing Ltd.
Exploring the protection of spray-pyrolysed tungsten oxide hydrophobic coating on stainless steel in a marine environment
(Springer, 2024) Gautam, V.; Praveen, L.L.; Vardhan, R.V.; Mandal, S.
Tremendous potential in the field of anti-biofouling coatings to prevent stainless steel (SS)-based underwater pipelines, sea vessels and other marine structures have been recognized to protect from biofouling, which is often initiated by algae attachment over the surface. In this work, hydrophobicity in spray-pyrolysed tungsten oxide (TO) coating on SS-316 substrate has been reported for the first time, via post-processing treatment using octadecyltrimethoxysilane (ODTMS) to induce self-assembled monolayer (SAM). Initially, structural and vibrational characteristics of ODTMS and ODTMS-treated TO (OTO) coating on SS were analysed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies. OTO-coating depicted a water contact angle (WCA) of 121°, revealing its hydrophobic nature, with further affirmation from X-ray photoelectron spectroscopy (XPS). Durability of the TO-coating was explored using the scratch hardness (Hs) test at different loading conditions (5, 10 and 15 N). Biofouling study was conducted by culturing blue-green algae (BGA, Phormidium sp.) in an in-house laboratory setup for 40 days, using seawater (collected from the Arabian Sea, Karnataka). The SS, TO- and OTO-coatings were immersed for 14 days in a controlled sea-water environment in the laboratory with the presence of BGA. A comparative study on the areal-algae attachment was keenly analysed over SS-, TO- and OTO-coatings. This work can be projected as a promising application providing multi-dimensional solutions in creating scratch-resistant and anti-biofouling coatings on SS in the shipbuilding industry. © Indian Academy of Sciences 2024.

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