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Freestanding conducting polyaniline film for the controlof electromagnetic radiations
K.K. Satheesh Kumar,S. Geetha,D.C. Trivedi 한국물리학회 2005 Current Applied Physics Vol.5 No.6
Electromagnetic interference is pollution generated due to dense nature of circuitry in electronic devices and is required to becontrol at its source. Polyaniline is an environmentally stable conducting polymer which can be cast as thin lm, which can replacethe corrosive metals as a shield for the control of electromagnetic radiations. In this communication we discuss our results on thepreparation of exible freestanding conducting polyaniline lm of varied thickness using eitherp-toluenesulphonic acid (PTSA) orcamphor-10-sulphonic acid as a primary dopant and 4-chloro-3-methyl phenol (CMC) as a secondary dopant. The resulting lmswere characterized by conductivity, scanning electron micrograph and shielding eectiveness measurements (SE). The SE measure-ments were carried out using co-axial transmission line method in the frequency range of 0.11000MHz. We noticed that only thechange of 2% in the shielding eectiveness of these lms over the period of 3 years indicating the environmental stability of poly-aniline lms..
S. Geetha,S.K. Sharma,G. Ilavazhagan,P.K. Banerjee,R.C. Sawhney,M. Sai Ram 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.1
This study was designed to determine the cytoprotective activity of flavones of seabuckthorn (Hippophae rhamnoides L.) against tert-butyl hydroperoxide (tert-BOOH), used as an oxidant to induce oxidative damage, with lymphocytes as the model system. Addition of tert-BOOH (250 μM) to the cells resulted in enhanced cytotoxicity and free radical production. The intracellular calcium levels, caspase activity, and apoptosis were significantly increased following tert-BOOH treatment. Seabuckthorn flavones at the concentration of 100 μg/mL significantly inhibited tert-BOOH-induced cytotoxicity and free radical production and also restored the antioxidant status to that of control cells. Seabuckthorn flavones also significantly restricted tert-BOOH-induced apoptosis by decreasing intracellular calcium levels and caspase activity. The extract also decreased tert-BOOH-induced formation of DNA breaks by 30%. These observations suggest that the flavones of seabuckthorn have marked cytoprotective properties, which could be attributed to the antioxidant activity.
Geetha, S.,Ram, M.Sai,Sharma, S.K.,Ilavazhagan, G.,Banerjee, P.K.,Sawhney, R.C. The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.1
This study was designed to determine the cytoprotective activity of flavones of seabuckthorn (Hippophae rhamnoides L.) against tert-butyl hydroperoxide (tert-BOOH), used as an oxidant to induce oxidative damage, with lymphocytes as the model system. Addition of tert-BOOH ($250\;{\mu}M$) to the cells resulted in enhanced cytotoxicity and free radical production. The intracellular calcium levels, caspase activity, and apoptosis were significantly increased following tert-BOOH treatment. Seabuckthorn flavones at the concentration of $100\;{\mu}g/mL$ significantly inhibited tert-BOOH-induced cytotoxicity and free radical production and also restored the antioxidant status to that of control cells. Seabuckthorn flavones also significantly restricted tert-BOOH-induced apoptosis by decreasing intracellular calcium levels and caspase activity. The extract also decreased tert-BOOH-induced formation of DNA breaks by 30%. These observations suggest that the flavones of seabuckthorn have marked cytoprotective properties, which could be attributed to the antioxidant activity.
Water Soluble Polyaniline as Biocide
Kumar, K. K. Satheesh,Ponmariappan, S.,Geetha, S.,Trivedi, D. C. 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.3
The microbial fouling of a submerged object is a complex phenomenon and its control requires the use of potentially hazardous chemicals. The effective control of microbial films on a submerged object is essential to prevent its corrosion. The microbial fouling not only accelerates the rate of corrosion due to imbalance of oxygen by creating electrochemical cell. The currently available biocides are for the control of planktonic microorganisms is based on tri-organic tin compounds, which are not friendly to aquatic life. Our preliminary study indicates that polyaniline doped with fhctionalized dopan? at concentration of 4×10^-6 g/ml is able to control the growth of microorganism in the area of 140㎜². In this paper we present our study on synthesis and use of water-soluble polyaniline as a biocide to control bio fouling.
Graphene quantum dots synthesis and energy application: a review
S. Akash Prabhu,V. Kavithayeni,R. Suganthy,K. Geetha 한국탄소학회 2021 Carbon Letters Vol.31 No.1
Graphene Quantum Dots (GQDs), zero-dimensional nanoparticles which are derived from carbon-based sources owned the new pavement for the energy storage applications. With the varying synthesis routes, the in-built properties of GQDs are enhanced in different categories like quantum efficiency, nominal size range, and irradiation wavelength which could be applied for the several of energy and optoelectronics applications. GQDs are especially applicable in the specific energy storage devices such as super capacitors, solar cells, and lithium-ion batteries which were demonstrated in this work. This paper critically reviews about the synthesis techniques used for the GQDs involving energy storage applications with increased capacitance, energy conversion, retention capability, and stability.
P. Geetha,S. Krishnan,R.K. Natarajan,V. Chithambaram 한국물리학회 2015 Current Applied Physics Vol.15 No.3
L-Valine Ferric Chloride single crystal is a new semi organic nonlinear optical material. It has been grown from a mixture of aqueous solutions of L-Valine and Ferric Chloride by slow evaporation solution growth technique at room temperature for the first time. Single crystal XRD analysis revealed that the crystal system belongs to Cubic P with cell parameters are a = 24.38 Å, b = 24.38 Å, c = 24.38 Å and volume is 14,485 Å3. The UV spectrum shows existence of wide transparency window suitable for optoelectronic applications. Thermal stability and melting temperature of the as grown crystal was identified from TGDTA analysis. Spectroscopic studies have been carried out for analyzing the presence of functional groups, thermal stability and phase transition of the grown crystal. The dielectric loss and the dielectric constant of the crystals were measured as a function of frequency. Photoluminescence study was carried out for grown crystals and the maximum emission occurs has good optical transmission in the entire visible region. Second harmonic generation (SHG) conversion efficiency has been estimated.