Time filter

Source Type

Azeezaa V.,Sathyabama University | Azeezaa V.,SRR Engineering College | Arul Pragasam A.J.,Sathyabama University | Sunitha T.G.,Pachaiyappas College | And 2 more authors.
Acta Physica Polonica A | Year: 2015

Nonlinear optical single crystals of L-cysteine hydrochloride monohydrate (LCB) were grown by slow evap-oration technique. Single crystal X-ray diffraction analysis revealed the crystal system and helped to determine lattice parameter values. Powder X-ray diffraction analyses were carried out and the diffraction patterns were indexed. The optical properties of the crystals were determined using UV-visible spectroscopy. Optical con-stants such as refractive index, extinction coeffcient and electric susceptibility were determined from UV-visible spectroscopy. The Fourier transform infrared studies confirmed the various functional groups present in the grown crystal. The mechanical behaviour of the grown crystals was studied using Vicker's microhardness tester. The ther-mal analysis confirmed that the crystal was stable up to 108.7°C. The dielectric constant and the dielectric loss measurements were carried out for different temperatures and frequencies. Second harmonic generation of LCB crystal was investigated by the Kurtz powder technique.

Nayeemunisa S.M.,Justice Basheer Ahmed Sayeed College for Women | Nayeemunisa S.M.,Presidency College at Chennai | Kiruthika S.,SRM University | Ponmani K.,Presidency College at Chennai | And 2 more authors.
International Journal of ChemTech Research | Year: 2015

A systematic investigation of alcohol adsorption and oxidation on binary and ternary electrocatalysts in acid medium was performed in membraneless methanol fuel cell (MLMFC). The different nominal compositions of binary Pt–Sn/C, Pt–Rh/C and ternary Pt– Sn–Rh/C electrocatalysts were characterized by TEM, EDX, and XRD techniques. Energy dispersive X-ray spectroscopy and X-ray diffractometry confirmed the formation of Pt–Sn– Rh/C, Pt–Sn/C, Pt–Rh/C metal catalyst having typical Pt crystalline structure and the formation of Pt–Sn alloy. Electrochemical analyses obtained at room temperature by cyclic voltammetry and chronoamperometry showed that Pt–Sn–Rh/C (50:10:40) gives higher current density compared to that of Pt–Sn–Rh/C (50:40:10), Pt–Sn/C (50:50) and Pt–Rh/C (50:50). The power density obtained using Pt–Sn–Rh/C (50:10:40) (33.93 mW cm−2) as anode catalyst in MLMFC was higher than that for Pt–Sn–Rh/C (50:40:10), Pt–Sn/C (50:50) and Pt–Rh/C (50:50) at room temperature, with catalyst loading of 2 mg cm−2. In this work, carbon-supported binary Pt−Sn/C, Pt−Rh/C and ternary Pt−Sn−Rh/C anode catalysts were successfully tested in a single membraneless fuel cell using 1.0 M methanol as the fuel and 0.1 M sodium percarbonate as the oxidant in the presence of 0.5 M H2SO4 as the electrolyte at room temperature. Based on the experimental results, we conclude that the trimetallic combination of Pt–Sn–Rh/C (50:10:40) shows superior methanol electro-oxidation than bimetallic combinations of Pt–Sn/C (50:50) and Pt–Rh/C (50:50). © 2015, Sphinx Knowledge House, All rights reserved.

Sadhiya Banu I.,University of Madras | Sadhiya Banu I.,Justice Basheer Ahmed Sayeed College for Women | Prakash H.,University of Madras | Natarajan P.,University of Madras
Inorganica Chimica Acta | Year: 2011

The photoreactions of tris(2,2′-bipyridine)nickel(II) complex, Ni(II)(bpy3)2+ were studied and compared with that of the photoreactions of 2,2′-bipyridine ligand. Continuous photolysis of the complex shows that the photodecomposition corresponds to the absorption of light by the complex in the ligand centered excited state. Flash photolysis of the complex using a 248 nm excimer laser yields bipyridine cation radical and solvated electron as transients. Absorption spectra of the transient observed for the complex is found to be similar to that observed for the ligand on flash excitation using a 248 nm laser suggesting that the transients observed in the case of complex is due to the coordinated bipyridine in the complex. The formation of solvated electron is observed to be monophotonic and that of the bipyridine cation radical is found to be a biphotonic process. Significant change in Ni-N bond distance upon oxidation of Ni(bpy3)2+ ion when compared to that observed in nickel(II)tetraazamacrocyclic complexes suggests that the formation of the trivalent complex by photolysis is not favored for the Ni(bpy3)2+ ion and CTTS excited state in the complex is not observed in the present system. © 2011 Elsevier B.V. All rights reserved.

Veerabadran U.,Quaid E Milleth Government Arts College for Women | Venkatraman A.,Justice Basheer Ahmed Sayeed College for Women | Souprayane A.,University of Madras | Narayanasamy M.,University of Madras | And 5 more authors.
Asian Pacific Journal of Tropical Disease | Year: 2013

Objective: To investigate the antioxidant and antiproliferative potential of Leonotis nepetifolia (L. nepetifolia) leaves. Methods: The leaves of L. nepetifolia were subjected to extraction using three different solvents and the antioxidant potential of those extracts were tested by using various in vitro assays. Further, the best screened extract was analyzed for its phytochemical profile by both qualitative and quantitative assays. In order to determine its anti-proliferative activity, the best screened extract was treated with breast and laryngeal cancer cell lines such as MCF-7 cells and Hep2 cells, respectively. The cytotoxicity of the extract was also studied using MTT assay. The inhibitory effect of the extract of leaves of L. nepetifolia on the selected cell-line DNA was determined by DNA fragmentation assay. Also, the extract was subjected to TLC and bioautography analysis. Results: The DPPH assay showed methanol extract of L. nepetifolia leaves to be more significant in scavenging free radicals with inhibition percentage of 60.57. %. From the data obtained, the methanol extract proved to be significant in all anti-oxidant assays and this effect was well comparable with the standard used in the study. The predominant phytochemicals such as phenols and flavonoids were further quantified as 0.107. % and 0.089. %. The cytotoxicity assay showed that the cell viability increased with increasing concentration of methanol extract. In addition, the extract caused dose dependent damage to the cancer cell lines MCF-7 and Hep2. Conclusions: Our study suggests that the leaves of L. nepetifolia were significant in scavenging free radicals and causing damage to proliferative cells. Further mechanistic studies would help in proving the efficiency of the selected plant under in vivo conditions. © 2013 Asian Pacific Tropical Medicine Press.

Ponmani K.,Presidency College at Chennai | Nayeemunisa S.M.,Presidency College at Chennai | Nayeemunisa S.M.,Justice Basheer Ahmed Sayeed College for Women | Kiruthika S.,SRM University | Muthukumaran B.,Presidency College at Chennai
Ionics | Year: 2015

In the present work, carbon-supported Pt–Sn, Pt–Ru, and Pt–Sn–Ru electrocatalysts with different atomic ratios were prepared by alcohol-reduction method to study the electro-oxidation of ethanol in membraneless fuel cells. The synthesized electrocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses. The prepared catalysts had similar particle morphology, and their particle sizes were 2–5 nm. The electrocatalytic activities were characterized by cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results obtained at room temperature showed that the addition of Sn and Ru to the pure Pt electrocatalyst significantly improved its performance in ethanol electro-oxidation. The onset potential for ethanol electro-oxidation was 0.2 V vs. Ag/AgCl, in the case of the ternary Pt–Sn–Ru/C catalysts, which was lower than that obtained for the pure Pt catalyst (0.4 V vs. Ag/AgCl). During the experiments performed on single membraneless fuel cells, Pt − Sn − Ru/C (70:10:20) performed better among all the catalysts prepared with power density of 36 mW/cm2. The better performance of ternary Pt–Sn–Ru/C catalysts may be due to the formation of a ternary alloy and the smaller particle size. © 2015 Springer-Verlag Berlin Heidelberg

Discover hidden collaborations