Faculty Publications
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Item Biosynthesis of cobalt oxide nanoparticles using endophytic fungus Aspergillus nidulans(Academic Press, 2018) Vijayanandan, A.S.; Mohan Balakrishnan, R.M.Metallic oxide nanoparticles have profound applications in electrochemical devices, supercapacitors, biosensors and batteries. Though four fungi were isolated from Nothapodytes foetida, Aspergillus nidulans was found to be suitable for synthesis of cobalt oxide nanoparticles, as it has proficient tolerance towards metal under study. The broth containing precursor solution and organism Aspergillus nidulans had changed from pink to orange indicating the formation of nanoparticles. Characterization by x-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and energy dispersive x-ray analysis (EDX) confirmed the formation of spinel cobalt oxide nanoparticles at an average size of 20.29 nm in spherical shape with sulfur-bearing proteins acting as a capping agent for the synthesized nanoparticles. The nanoparticles could be applied in energy storage, as a specific capacitance of 389 F/g showed competence. The study was a greener attempt to synthesize cobalt oxide nanoparticles using endophytic fungus. © 2018 Elsevier LtdItem Evaluation of photothermal properties for absorption of solar energy by Co3O4 nanofluids synthesized using endophytic fungus Aspergillus nidulans(Elsevier Ltd, 2020) Vijayanandan, A.S.; Kandath Valappil, R.S.; Mohan Balakrishnan, R.M.An attempt has been made to compare the optical properties of cobalt oxide (Co3O4) nanoparticles using experimental values and theoretical predictions. Optical transmittance of the nanoparticles obtained was higher than 65% in 550–850 nm containing visible spectrum and the experimental results were in accordance with the predictive datum. The absorption coefficient peak observed is close to the predictive value and is present in the visible region of the light. In addition, there was an excellent agreement between theoretical and experimental results in extinction coefficient and refractive index. Besides, this work proposes and validates a novel idea of using Co3O4 nanofluids to enhance solar thermal conversion efficiency. Co3O4 nanofluids synthesized using endophytic fungus Aspergillus nidulans isolated from a medicinal plant, Nothapodytes foetida has been used to illustrate the energy storage capacity of nanofluids. Experimental results reveal that Co3O4 nanofluids have good specific absorption rate (SAR) and better photo-thermal conversion efficiency than water. Nanofluid exhibited a greater temperature gradient than pure water, which is desired. Thus the good absorption ability of Co3O4 nanofluids for solar energy indicated that it is suitable for direct absorption solar thermal energy systems. © 2019Item Photostability and electrical and magnetic properties of cobalt oxide nanoparticles through biological mechanism of endophytic fungus Aspergillus nidulans(Springer, 2020) Vijayanandan, A.S.; Mohan Balakrishnan, R.M.The study elaborates magnetic and electrical properties of greenly synthesized cobalt oxide (Co3O4) nanoparticles through endophytic fungus Aspergillus nidulans isolated from medicinal plant Nothapodytes foetida, which examines the ability of the nanoparticles to be magnetized and electrified, being one of the yardsticks for energy application. On increasing the precursor concentration from 2 to 10 mM, there is a shift in paramagnetic to weak ferromagnetic behavior of nanoparticles with the increase in saturation magnetization (Ms) from 0.161 to 7.75 emu/g. Frequency dependence of dielectric constant is found to increase with an increase in frequency, and the aforementioned nanoparticles can be used as a dielectric up to 1,50,000 Hz as dissipation factor is lesser than one. Besides, photostability study has indicated that the particles are stable for at least 45 days. Through liquid chromatography–mass spectrometry (LC–MS) analysis, phytochelatins are identified to be involved in the biosynthesis of nanoparticles. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.