Browsing by Author "Gurumurthy Hegde"

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Effect of carbonaceous oil palm leaf quantum dot dispersion in nematic liquid crystal on zeta potential, optical texture and dielectric properties
(Springer Medizin, 2021) Ayushi Rastogi; Fanindra Pati Pandey; Avanish Singh Parmar; Shri Singh; Gurumurthy Hegde; Rajiv Manohar
In the present work, the dispersion of oil palm leaf based carbonaceous quantum dots (OPL QDs) in nematic liquid crystal (NLC) E 48 eutectic mixture has been reported. The dispersed systems with concentrations 0.1, 0.2, and 0.3 wt% are designated respectively, as MIX 1, MIX 2, and MIX 3. The objective of this study is to analyze the results on the zeta potential, optical texture, dielectric constant, dielectric loss, conductivity, dielectric strength, relaxation frequency, specific power loss and total power loss of pure and OPL QDs dispersed nematic E 48 system. Zeta potential measurement has been performed in the solution state to ensure dispersion stability. The optical textures and dielectric results are recorded after filling the respective samples in sample cells. The core findings in the present study show that the zeta potential varies from − 23.43 mV to + 28.07 mV that signifies the stability of OPL QDs suspension in LCs. Specific power loss (SPL) and total power loss (TPL) are found to be least for MIX 1 which shows that the problem of high power consumption in LCDs can be resolved by dispersing a small weight percent concentration of OPL QDs in LC medium (MIX 1). Improved molecular alignment in the dispersed system has been observed from the textural study which finds its application in good contrast display devices. The color change in the aligned textures with temperature has been attributed to the birefringence change. The porous nature of carbonaceous OPL QDs has its application in supercapacitors. The benchmark results of this study highlight the effect of temperature and frequency on dielectric parameters for both planar and homeotropic state of E 48 LCs. OPL QDs dispersed system display increased conductivity for MIX 3. The decrease in the activation energy for OPL QDs dispersed system in comparison to pure LC material E 48 is a consequential result of the potential barrier change. The increment in the dielectric strength and relaxation frequency of OPL QDs dispersed system is noticed in comparison to pure E 48. These outcomes open the door for the applicability of present LCs in the field of both display and non-display devices like sensors, supercapacitors, low power consumption displays, energy conversion, and electrical storage devices as well as advanced smart systems. Graphical abstract: [Figure not available: see fulltext.]. © 2021, Islamic Azad University.
Green synthesized cobalt nanoparticles from Trianthema portulacastrum L. as a novel antimicrobials and antioxidants
(Taylor and Francis Ltd., 2024) Anand Prakash; Srija Sur; Vivek Dave; Prashansa Sharma; Suvadra Das; Partha Roy; Gurumurthy Hegde
Trianthema portulacastrum is a dietary and medicinal plant that has gained substantial importance due to its pharmacological properties. This plant was used for its various healing properties since the ancient period in ayurvedic system of medicine. The green synthesis technique is an eco-friendly as well as cost effective technique which can produce more biocompatible nanoparticles when compared with those fabricated by physio-chemical methods. Therefore, nanoparticles produced by green synthesis are credible alternatives to those which are produced by conventional synthesis techniques. This research mainly aims to produce nanoparticles with the methanolic leaf extract of T. portulacastrum. The optimized nanoparticles were further analyzed for anti-fungal, anti-bacterial and antioxidant properties. Disk diffusion assay was used for the determination of the antimicrobial property and on the other hand, DPPH radical scavenging assay as well as hydrogen peroxide scavenging activity proved the antioxidant property of the formulation. The study revealed that Escherichia coli (gram negative strain) shows greater zone of inhibition when compared with Bacillus subtilis (gram positive bacteria). The nanoparticles have also been reported to show significant anti-fungal activity against the strains of Aspergillus niger and Fusarium oxysporum which proves its desirability for its further use against both bacterial as well as fungal infections. The novel formulation can be explored dually as antimicrobial and antioxidant agent. © 2023 Taylor & Francis Group, LLC.
Time-resolved fluorescence and UV absorbance study on Elaeis guineensis/oil palm leaf based carbon nanoparticles doped in nematic liquid crystals
(Elsevier B.V., 2020) Ayushi Rastogi; Fanindra Pati Pandey; Gurumurthy Hegde; Rajiv Manohar
Time resolved fluorescence measurement and UV absorbance study on oil palm leaf based nanoparticles (OPL) doped with nematic liquid crystal E 48 in 0.1, 0.2 and 0.3 wt/wt% concentration abbreviated as mixture 1 (MIX 1), mixture 2 (MIX 2) and mixture 3 (MIX 3) were conducted. OPL biomolecule loaded graphene oxide –nematic E 48 liquid crystal system has been fabricated for biosensor application. The interaction of OPL nanoparticles with E 48 nematic liquid crystal having different concentration of nanoparticles has been explored. Pure nematic E 48 and its doped system have been examined by time- resolved fluorescence spectroscopy (TRFS) technique. Variation in the nanoparticles concentration strappingly affects the fluorescence emissions. Lack of Förster resonance energy transfer (FRET) was found in all composites. This manuscript unveils the purpose of a range of factors, such as dipolar interface between donor and acceptor molecules, nanoparticles orientation and its proximity distance that may be accountable for the non-appearance of FRET. Nematic nanoparticles doped system forms an antique composition of luminescent material even though the fluorescence characteristics of host are customized in the existence of nanoparticles by the molecular alignment modification. Variation in lifetimes of nematic nanoparticles doped system has been observed. These results find its applicability in photonic displays, photovoltaic devices, biosensors etc. © 2020