Mahendraprabhu K.,Pondicherry UniversityPuducherry |
Elumalai P.,Pondicherry UniversityPuducherry
Sensors and Actuators, B: Chemical | Year: 2017
Niobium pentoxide (Nb2O5) powder was synthesized by citrate-based sol-gel method using niobium pentachloride as precursor and citric acid as gelling agent. The synthesized powder was characterized by X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FT-IR) and scanning electron microscope (SEM). Yttria-stabilized zirconia (YSZ)-based electrochemical sensor was fabricated using the Nb2O5 powder as sensing electrode (SE) and Pt as reference electrode (RE), and its sensing characteristics were examined in the temperature range of 750–850 °C under each of various O2 concentrations (5, 10, 15 and 21 vol%). It was observed that the YSZ-based sensor attached with Nb2O5-SE exhibited selective and sensitive response to NO2 at 800 °C in all the measured O2 concentrations. The sensor showed the highest sensitivity and selectivity to NO2 in 5 vol% O2. The NO2 sensing mechanism of the present sensor was confirmed to be mixed potential-type. The sensor exhibited stable response to NO2 for the examined period of more than a month. © 2016 Elsevier B.V.
Rao M.V.,Pondicherry UniversityPuducherry |
Shanmugavelu B.,Pondicherry UniversityPuducherry |
Kumar V.V.R.K.,Pondicherry UniversityPuducherry
Journal of Luminescence | Year: 2017
Dy3+ doped alkaline earth bismuth borate glasses were prepared by the conventional melt-quenching method. The prepared glasses were characterized by absorption, excitation, emission and decay curves. Judd–Ofelt parameters were obtained from the absorption spectra recorded at 400–2000 nm. All the samples were excited at different wavelengths from UV (350 nm) to blue (450–470 nm) light and respective emission spectra are recorded. The intensity ratio of yellow to blue (Y/B) indicates that Dy3+ ions are present in low symmetry site. B2O3–Bi2O3RO (R = Ba, Sr & Ca) glasses emit efficient white light under different excitation wavelengths, which match well with the emission of commercial GaN-based blue LEDs and InGaN-based LEDs respectively. CIE coordinates were calculated from the emission spectra and found that they fall in white light region. Decay curves show single exponential nature up to 1 mol% of Dy3+ concentrations and then turn into non-exponential for 2 mol% of Dy3+ ions. Lifetime of these glasses decreases with increase of Dy3+ ion concentration. © 2016 Elsevier B.V.
Kirubasankar B.,Pondicherry UniversityPuducherry |
Murugadoss V.,Pondicherry UniversityPuducherry |
Angaiah S.,Pondicherry UniversityPuducherry
RSC Advances | Year: 2017
Cobalt selenide-graphene (CoSe-G) nanohybrid was successfully synthesised by a simple and facile one-pot hydrothermal method and used as a positive electrode for an asymmetric supercapacitor. The CoSe-G nanohybrid electrode exhibits a higher specific capacitance of 1037 F g-1 at 5 mV s-1 than CoSe. The electrochemical impedance studies revealed that the graphene in the nanohybrid not only reduced the contact resistance of the electrode but also significantly increases the electrons transport. The good electrochemical performance of CoSe-G is the synergy between CoSe and graphene. In addition, the asymmetric supercapacitor (ASC) was fabricated using CoSe-G and activated carbon as the positive electrode and negative electrode, respectively, and electrospun PVdF membrane containing 6 M KOH as the separator as well as electrolyte. The fabricated ASC delivered an extended operating voltage window of 1.6 V. It also provides a higher energy density of 45.5 W h kg-1 and a power density of 1.1 kW kg-1 and retains 81% of its initial specific capacitance even after 5000 cycles. © 2017 The Royal Society of Chemistry.
Ramakumar S.,Pondicherry UniversityPuducherry |
Deviannapoorani C.,Pondicherry UniversityPuducherry |
Dhivya L.,Pondicherry UniversityPuducherry |
Shankar L.S.,Pondicherry UniversityPuducherry |
Murugan R.,Pondicherry UniversityPuducherry
Progress in Materials Science | Year: 2017
Inorganic solid fast Li+ conductors based batteries are expected to overcome the limitations over safety concerns of flammable organic polymer electrolytes based Li+ batteries. Hence, an all-solid-state Li+ battery using non-flammable solid electrolyte have attracted much attention as next-generation battery. Therefore, in the development of all-solid-state lithium rechargeable batteries, it is important to search for a solid electrolyte material that has high Li+ conductivity, low electronic conductivity, fast charge transfer at the electrode interface and wide electrochemical window stability against potential electrodes and lithium metal. Hence, significant research effort must be directed towards developing novel fast Li+ conductors as electrolytes in all-solid-state lithium batteries. Among the reported inorganic solid Li+ conductive oxides, garnet-like structural compounds received considerable attention in recent times for potential application as electrolytes in all-solid-state lithium batteries. The focus of this review is to provide comprehensive overview towards the importance of solid fast lithium ion conductors, advantages of lithium garnets over other ceramic lithium ion conductors and understanding different strategies on synthesis of lithium garnets. Attempts have also been made to understand relationship between the structure, Li+ conduction and Li+ dynamics of lithium garnets. The status of lithium garnets as solid electrolyte in electrochemical devices like all-solid state lithium battery, lithium-air battery and sensor are also discussed. © 2017 Elsevier Ltd
Achari K.M.M.,Pondicherry UniversityPuducherry |
Ramanathan C.R.,Pondicherry UniversityPuducherry
Tetrahedron Asymmetry | Year: 2017
A conformationally rigid chiral molecule LB-I with Lewis basic site has been designed and synthesized in racemic form from ferrocene via Lewis acid mediated diastereoselective cyclization of hydroxy lactam. Both isomers were successfully obtained in enantiomerically pure form through classical resolution using dibenzoyl-D-tartaric acid as the chiral resolving agent in acetone. The nature of the diastereomeric salt formed in the resolution process was investigated by single crystal X-ray crystallographic studies. The absolute configuration of (+)-LB-I was unambiguously assigned as (S,Rp) by single crystal analysis of the salt I obtained from precipitate fraction containing (+)-LB-I and dibenzoyl-D-tartaric acid. © 2017 Elsevier Ltd
Venkatanna K.,Pondicherry UniversityPuducherry |
Ramanathan C.R.,Pondicherry UniversityPuducherry
Tetrahedron Letters | Year: 2017
Allylation of 2-aminophenol-derived aldimines using allyltrichlorosilane under catalyst free conditions has been developed. This reaction afforded the corresponding homoallylic amines in good to excellent yields (68–94%). The salicylaldehyde-derived aldimines as well as benzoylhydrazone also found to react with allyltrichlorosilane smoothly under the same conditions, to furnish the corresponding homoallylic amine derivatives. This study suggests that the phenolic –OH group acts as an anchoring group for the transfer of allyl group from allyl silane reagent. © 2017 Elsevier Ltd
Subashree K.,Pondicherry UniversityPuducherry |
Sundarapandian S.,Pondicherry UniversityPuducherry
Taiwania | Year: 2017
Carbon inventory was done on two savannah ecosystems (sites I & II) of Kanyakumari Wildlife Sanctuary, Western Ghats, India. Ten plots of 20 m × 20 m each were laid in each site to study woody vegetation and a total of forty quadrats (4 in each plot) of 1 m × 1 m were laid in each site for the understorey. Both sites showed remarkable variations in biomass and carbon accumulation patterns. Site I (213 Mg C/ha) had higher woody biomass carbon than site II (185.9 Mg C/ha). However, the latter had greater understorey biomass carbon (site I – 3.2 Mg C/ha; site II –20.7 Mg C/ha). Overall, the total vegetation carbon accounted to 216.2 Mg C/ha in site I and 206.6 Mg C/ha in site II. On the other hand, soil carbon was higher in site II (183.5 Mg C/ha) than site I (172.3 Mg C/ha). Soil bulk density increased with increase in soil depth in both sites. Cumulatively, even though both sites had almost equal carbon stocks, they show considerable variation in the amount of carbon stocked in their carbon pools. Woody biomass was the largest carbon pool, followed by soil and understorey biomass. The observed variations could be due to differences in terrain characteristics, edaphic factors, incidence of fires, etc. The study emphasizes the important role of savannahs in stocking considerable amounts of carbon in their different carbon pools. © 2017, College of Life Science. All rights reserved.
Patil H.P.,Pondicherry UniversityPuducherry |
Raja V.,Pondicherry UniversityPuducherry
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016
The purpose of this paper is to introduce the new family of H-graphs that generalizes the existing notions of trees, higher dimensional trees and k-ctrees. Further, we establish the characterizations of both the wheel-graphs G〈Wn〉 for n ≥ 6 and Tk-graphs for k ≥ 4, where Tk is not a star. Finally, we determine the conditions under which the Tk-graphs are split graphs and also propose some open problems for further research. © Springer International Publishing Switzerland 2016.
Manivannan V.,Pondicherry UniversityPuducherry |
Padmanaban R.,Pondicherry UniversityPuducherry
Chemical Physics | Year: 2016
We investigate the initial state-selected dynamics of the title reaction on its ground (1 3A″) and first excited (1 3A′) triplet potential energy surfaces (PESs) by a time-dependent wavepacket propagation method, employing the ab initio analytical PESs developed by Gamallo et al. (2003). All partial wave contributions up to the total angular momentum J=140 are found to be necessary for the scattering of NO diatom in its vibrational and rotational ground state up to a collision energy ∼0.9 eV. The converged initial state-selected reaction attributes viz., reaction probabilities, integral cross sections and thermal rate constants are obtained within the centrifugal sudden (CS) approximation and the convergence of the results are carefully checked by varying all parameters used in the numerical calculations. The dynamical results are compared with the other reported theoretical and experimental findings. Investigation on the energy-resolved channel-specific reaction probabilities infers that the N2 formation channel is very much favorable than the N-exchange channel. The reaction proceeds via some metastable resonances, observed from the oscillatory probability curves, which is more in the latter channel compared to the former. The effect of rotational and vibrational excitations of the reagent (NO diatom) on the dynamics is examined. We also examine the effect of isotopic substitution of N-atom (14N by 15N) on the reaction dynamics. © 2016 Elsevier B.V.
Kavitha S.,Pondicherry UniversityPuducherry |
Jeevaratnam K.,Pondicherry UniversityPuducherry
Food Biotechnology | Year: 2016
ABSTRACT: Traditionally Piper betle L. leaves have been used in India for fermenting certain foods. In our previous study, while fermenting Uttapam batter along with Piper betle L. var. Pachaikodi leaves led to suppression of gas formation and altered Lactic acid bacteria profile, especially in bacilli isolates compared to those observed in plain Uttapam batter fermentation. Hence, the aim of the present study was to understand the rationale behind these changes through characterization of Lactobacillus isolates from Piper betle L. var. Pachaikodi and also the leaves extracts for antimicrobial activity. Out of 72 isolates obtained from the betel leaves, only 10 isolates were bacilli which were chosen for their molecular characterization and to elucidate their inhibitory effects against major food borne pathogens and gas-forming bacteria and to compare with the effect of betel leaves extract. Random amplified polymorphic DNA (RAPD)-PCR and phenotype analysis was used to differentiate the isolates at strain level, 16S rRNA gene sequence for phylogenetic analysis and species-specific multiplex PCR analysis for sub-species identification. All isolates were identified as Lactobacillus plantarum subsp. plantarum. All Lactobacillus isolates were indigenous to leaf as they were resistant to betel leaves extract and showed maximum activity against some LAB and non-LAB indicator strains except Lactobacillus plantarum MTCC 6160 which was resistant. Among them, KJB23, 36 and 47 were the most effective. Particularly, the isolate KJB23 and ethanolic betal leaf extract showed rivaling inhibitory activity against major food borne pathogens, while dissimilar activity against gas forming bacteria. This study revealed that either Piper betle L. leaf or Lactobacillus strains from the leaves can be valuable for food applications when added to fermented products. © 2016 Taylor & Francis.