Browsing by Author "Amutha, P"

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COSTUS SPECIOSUS LEAF EXTRACT ASSISTED CS-PT-TIO2 COMPOSITES: SYNTHESIS, CHARACTERIZATION AND THEIR BIO AND PHOTOCATALYTIC APPLICATIONS
(Elsevier, 2019-11-05) Surya, C; Agnel Arul John, N; Pandiyan, V; Ravikumar, S; Amutha, P; Abilio J.F.N, Sobral; Balu, Krishnakumar
The antioxidative and antidiabetic properties of Costus speciosus leaf extract assisted nanoparticles (CS–Pt modified TiO2) were compared with pristine TiO2 NPs along with standard ascorbic acid (AA). CS-Pt nanoparticles were synthesized through bioreduction process and supported on titanium dioxide semiconductor. Costus speciosus (CS) leaf extract was used as reducing and capping agent. Initially, CS-Pt nanoparticles synthesis was carried out with ethanolic extract of CS, later, two different wt% of CS-Pt supported TiO2 were prepared through sol-gel cum solvothermal process. The prepared materials have been characterized using different characterization techniques such as XRD, FT-IR, Raman, SEM, HR-TEM, EDS, DRS, PL and XPS measurements. CS-Pt-TiO2 nanocomposites showed well dispersion of Pt nanoparticles on TiO2 surface. The prepared materials have been effectively utilized for in-vitro antioxidant and in vitro antidiabetic activity. Moreover, the photocatlytic activity of the materials has been tested toward NBB degradation under visible light. CS-Pt NPs modified TiO2 composites show better activity when compared with pristine TiO2 in all cases.
A FACILE APPROACH FOR THE SYNTHESIS OF CARBON DOTS FROM HIBISCUS SABDARIFFA & ITS APPLICATION AS BIO-IMAGING AGENT AND CR (VI) SENSOR
(Elsevier, 2019) Komalavalli, L; Amutha, P; Monisha, S
An eco-friendly approach to yield fluorescent carbon dots (C-dots) from bio-precursors has received a fascinating impact on its application as heavy metal ions sensors & bio-imaging agent. The C-dots have been synthesised by hydrothermal method from Hibiscus sabdariffa and characterised by IR, TEM, UV and photo luminescent spectral studies. This approach is evident to be facile, cost-effective and non– toxic with unremitting water solubility. The blue luminescent C-dots formed reveals excitation and size dependent photo luminescent behaviour. The as-prepared C-dots have been applied to detect Cr (VI) ions in aqueous solution. Also, the cyto-toxicity and bio-imaging ability of the C-dots were examined using breast cancer cells (MDA-MB 231 cell lines). The studies affirmed low toxicity & excellent bio-imaging potentiality of the C-dots.
THERMO-PHYSICAL, TRIBOLOGICAL AND MACHINING CHARACTERISTICS OF HASTELLOY C276 UNDER SUSTAINABLE COOLING/LUBRICATION CONDITIONS
(Elsevier, 2022-08) Nimel, Sworna Ross; Srinivasan, N; Amutha, P; Munish Kumar, Gupta; Mehmet Erdi, Korkmaz
Chemical reactivity and poor heat conductivity make nickel (Ni) and its alloys difficult to process. The aerospace industry's expectations for high-quality surfaces are one of the biggest hurdles in machining nickel components. Recent studies have found some flaws in mist lubrication techniques when utilised under high-speed cutting circumstances, thus nanoparticles with higher thermal conductivity than the base fluid is now being used in minimum quantity lubrication (MQL) systems. Nanocarbon dots (CDs) blended with bio lubricant is an effective coolant to enhance the heat transfer capability by decreasing friction. The inclusion of the right nanoparticle ratio to the base liquid is one of the most important challenges that arise when machining. This research focuses on a deeper exploration of Hastelloy C276's tribological behaviour and machinability under various cutting approaches (Dry, MQL Cryo CO2 and N-MQL). Milling trials were carried out with various speed-feed pairings and cutting conditions. Outcomes show that 0.8 wt% CDs with soybean oil reduces the surface roughness by 56–69 %, 15–24 %, and 15–26 % over dry, MQl and cryo CO2 environments. According to elemental study of cutting inserts, adhesion is the primary wear mechanism in all cutting mediums. Finally, the chillness produced by cryo CO2 has a positive effect compared to the N-MQL strategy by producing fine grains.
TRIBOMECHANICAL PERFORMANCE OF MGO–ZNO NANOPARTICLES AS LUBRICATING ADDITIVES IN THE MICROEXTRUSION PROCESS
(Institution of Mechanical Engineers, 2020-04-28) Srinivasan, N; Rajenthirakumar, D; Amutha, P
The interfacial friction between tool and workpiece is unpredictable in the micromanufacturing process. It has a major influence on process workability, which determines product formability. In this study, the microtribological behavior of MgO–ZnO mixed metal oxide nanoadditive lubricant with dry friction is investigated in the microextrusion process. In the microextrusion of aluminum 6063 gear, the extrusion force reduced significantly upon using the nanoadditive lubricant. The surface roughness result shows the improved surface quality due to the existence of nanoadditives in the micromanufacturing process. The quantitative deviation due to interfacial friction is resolved with different coefficients by performing the numerical evaluation. This research contributes to the fundamental understanding about the tribological and mechanical behavior of nanoadditive lubricant in the microextrusion process and facilitates in minimizing the interfacial friction.