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Vengatesan, M. R.,Shen, Tian-Zi,Alagar, M.,Song, Jang-Kun American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.1
<P>We report a cost effective and easy chemical reduction method for exfoliated individual graphene oxide (GO) and GO paper using p-toluene sulfonic acid (PTSA) under mild conditions. Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photon spectroscopy (XPS), thermo gravimetric analysis (TGA) and transmission electron microscopy (TEM) analysis were performed to investigate the quality of GO reduction. Data resulting from the spectral analysis suggest that the reduction method using PTSA is an efficient method to remove oxygen functionalities in the GO and also as an alternative to commonly used reducing agents. We also fabricated chemically reduced GO (RGO) film from GO film using this method. The RGO film exhibits an electrical conductivity of about 10587 Sm-1. These results suggest that this method is very useful for the reduction of GO and GO film or paper using PTSA in a solution process for flexible electronics due to its facile, efficient and cost-effective features.</P>
Vengatesan, G.,Shanmugam, P.,Venkatesan, R.,Vedachalam, N.,Joseph, Jossia K. Techno-Press 2020 Ocean systems engineering Vol.10 No.2
Cyclone Heat Potential (CHP) is an essential parameter for accurate prediction of the intensity of tropical cyclones. The variability of the heat storage in the near-surface layers and the vertical stratification near the surface due to large fresh water inputs create challenges in predicting the intraseasonal and interannual evolution of monsoons and tropical cyclones in the Bay of Bengal. This paper for the first time presents the D26- referenced cyclone heat potential observed in the Bay of Bengal during the period 2012-17 based on the in-situ data collected from 5.5 million demanding offshore instrument-hours of operation in the Ocean Moored Buoy Network for Northern Indian Ocean (OMNI) buoy network by the National Institute of Ocean Technology. It is observed that the CHP in the Bay of Bengal varied from 0-220 kJ/㎠ during various seasons. From the moored buoy observations, a CHP of ~ 90 kJ/㎠ with the D26 isotherm of minimum 100m is favorable for the intensification of the post-monsoon tropical cyclones. The responses of the D26 thermal structure during major tropical cyclone events in the Bay of Bengal are also presented.
Effects of curing condition of solution cast Nafion® membranes on PEMFC performance
Singaram Vengatesan,김형준,임태훈,Eunae Cho 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
To study the feasibility of applying solution-cast membranes to polymer electrolyte membrane fuel cells (PEMFCs), single cells prepared with solution-cast membranes were tested. The solution cast membranes were fabricated from a commercial Nafion solution under various conditions. Effects of annealing temperature on characteristics of the solution-cast membranes were investigated by measuring water uptake and ionic conductivity of the membranes. Performance of the single cells using the prepared solution cast membranes was evaluated in terms of i-V curves, Nyquist plots, and H2 crossover current density. Based on the results, solution-cast membranes were fabricated by being cured at 150℃ for different hours to examine effects of curing time on cell performance. Finally, durability of solutioncast membranes was investigated with operating the single cells for 1,000 hr.
Singaram Vengatesan,조은애,오인환 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.5
Active and stable cobalt-based non-precious metal catalysts for the oxygen reduction reaction (ORR) in PEM fuel cells were developed through high-temperature pyrolysis of metal-porphyrins supported on carbon. The roles of substituted porphyrins, carbon support, and catalyst loading on ORR activity were studied using rotating disc electrode (RDE) measurements. It was observed that the carbon support plays a major role in improving the catalytic activity. The results showed that among the supported catalysts, the homemade mesocarbon-supported cobalt-porphyrin catalyst with 20 wt% loading displayed higher ORR activity; the cell performance showed maximum current density of 1.1 A cm−2 at 0.13 V in H2/O2 fuel cells.
Binary Cu/ZnO decorated graphene nanocomposites as an efficient anode for lithium ion batteries
Liyamol Jacob,K. Prasanna,M.R. Vengatesan,P. Santhoshkumar,이창우,Vikas Mittal 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-
Binary metal/metal oxide doped graphene nanocomposites have received wide attention as an effective anode material in Li-ion batteries. The binary composition metal/metal oxide improves the storage space and the conductivity of the electrode. The doped graphene enhances the structural and electronic properties of the electrode. In the present work, we report a Cu/ZnO hybrid nanoparticle-decorated graphene nanocomposite as an advanced anode material for the high-performance Li-ion batteries. Three different compositions of the hybrid Cu/ZnO/graphene nanocomposites have been synthesized by changing the concentration of Cu precursors in the hybrid. The nanocomposite of 0.05 M Cu precursor and 0.1 M ZnO precursor shows higher surface area (SBET = 168.7 g/m2) and excellent electrochemical results. X-ray photoelectron spectroscopy (XPS) analysis revealed that the Cu nanoparticle exists in +2 oxidation state on the ZnO lattice with the graphene nanostructure. Transmission electron microscopy (TEM) analysis shows the distribution of Cu/ZnO nanoparticles over the graphene sheets with a size of around 10–50 nm. From the electrochemical analysis, we inferred that the hybrid possesses a stable and specific capacity of 630 mAh g−1 at a current rate of 100 mA g−1 with almost 95% capacity retention for up to 100 cycles. To highlight the importance of binary Cu/ZnO doped graphene nanocomposites, their respective base namely, ZnO/graphene and Cu/graphene composites have also been studied.
Chemical Investigations and Anti-inflammatory Activity of Fixed Oil of Butea monosperma Seeds
A. Gunakunru,K. Padmanaban,P. Thirumal,N. Vengatesan,N. Gnanasekar,S. Raja,A.T. Rajarajan,S.G. Vijaya Kumar,J. Britto Perianayagam 한국생약학회 2004 Natural Product Sciences Vol.10 No.2
The fruit and seeds of Butea monosperma (Lam) Kuntze (Fabaceae) are useful in piles, anthelmintic, eye diseases, and inflammation in the Indian system of medicine. Hence, we have evaluated the anti-inflammatory activity of the fixed oil, mixed fatty acids, and unsaponifiable matter of B. monosperma against carrageenan-induced paw oedema and cotton pellet-induced granuloma in rats. The fixed oil, mixed fatty acids, and unsaponifiable matter of the oil exhibited significant anti-inflammatory activity on the tested experimental animal models. The unsaponifiable matter of the oil produced higher protection compared to fixed oil and mixed fatty acids. Phytochemical analysis of the fixed oil revealed the presence of steroids and terpenoids while unsaponifiable matter of the oil showed the presence of β-sitosterol. Also, four fatty acids were identified in the fixed oil by gas liquid chromatography. The anti-inflammatory activity of the fixed oil may be due to unsaponifiable matter or combination of unsaponifiable matter and mixed fatty acids.
Wijewardhana, K. Rohana,Shen, Tian-Zi,Vengatesan, M.R.,Kim, Joosung,Lee, Hyoyoung,Song, Jang-Kun Elsevier 2017 Carbon Vol.119 No.-
<P>Transport, relocation, and self-assembly of nano and microparticles in colloidal systems are highly demanded in nanotechnology, photonics, microfluidics, and biotechnology; topological charges can provide an effective means for these purposes. We report that crumpled two-dimensional (2D) graphene oxide (GO) particle sheets in nematic fields can serve as a nest for complicated topological defect loops, which, in turn, provide mobility and inter-adhesiveness to the GO particles. The application of electric fields actuated the GO particles orthogonally, inducing their coalescence into large radial clusters upon absorption of other GO particles. In contrast, in the isotropic phase, where no topological defects existed, the GO particles electrostatically repelled each other owing to the presence of surface charges with equal sign. We also demonstrate that predesigned shallow surface trenches on a substrate can anchor seed GO particles, which attract other GO particles to create a macroscopic structure along the trench. (C) 2017 Elsevier Ltd. All rights reserved.</P>