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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.

Balaganapathi T.,Pondicherry UniversityPuducherry | KaniAmuthan B.,Pondicherry UniversityPuducherry | Vinoth S.,Pondicherry UniversityPuducherry | Thilakan P.,Pondicherry UniversityPuducherry
Materials Research Bulletin | Year: 2017

Titanium Di-Oxide (TiO2) was synthesized using PEG template assisted sol-gel synthesis process. Role of Poly ethylene Glycol (PEG) and the corresponding porous evolution was studied with respect to calcination temperatures. PEG evaporation and optimum pore formation was deduced from DTA, TGA and BET studies. Crystallization was studied using X-ray powder diffraction and Micro-Raman measurements. Field Emission Scanning Electron Microscope (FESEM) and HRTEM studies revealed that the porosity arises from the voids between the assemblies of nanocrystallites. Highest surface area of 133 m2/g and 159 m2/g were recorded for both brookite and brookite mixed with rutile respectively. The phase transition root was identified as(i) from brookite to rutile and (ii) mixed brookite with rutile to pure rutile phases. Photodegradation studies reveal identical degradation sequence of MB > MO > RhB for brookite and P25 samples and a different degradation sequence of MB > RhB > MO for brookite mixed with rutile sample. © 2017 Elsevier Ltd

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.

Anbazhagan R.,Pondicherry UniversityPuducherry | Rangaswamy N.,Pondicherry UniversityPuducherry
Advances in Intelligent Systems and Computing | Year: 2014

In this paper, the contention performance of message- and code-based initial ranging is investigated for two different scenarios or cases when idle mode is activated at the mobile stations (MSs). First scenario assumes a chosen set of MSs to follow mobility waypoint between the base stations (BSs), while other MSs remain stationary. Second scenario (worst case) presumes that all the MSs served by the BSs follow either mobility waypoint or random waypoint between the BSs. Under these scenarios, during periodic location update, MSs undergo contentionbased network re-entry process. When more than one MSs undergo location update, it causes high contention amid MSs. Hence, this paper investigates the contention performance of message- and code-based ranging during periodic network re-entry. Simulations validate that the MSs in worst-case scenario with code ranging perform better in terms of idle-mode energy consumption (57.97%) and percentage of time in idle mode (68.11%) than message ranging under Rayleigh fading channel. © Springer India 2014.

Mata R.,Pondicherry UniversityPuducherry | Nakkala J.R.,Pondicherry UniversityPuducherry | Sadras S.R.,Pondicherry UniversityPuducherry
Colloids and Surfaces B: Biointerfaces | Year: 2016

Green synthesized gold nanoparticles have received substantial attention owing to their biomedical applications, particularly in cancer therapy. Although anticancer activities of green synthesized gold nanoparticles have been reported earlier, the underlying mechanism behind their anticancer activity is still to be understood. The present study, describes the green synthesis of Abutilon indicum gold nanoparticles (AIGNPs) from Abutilon indicum leaf extract (AILE) and their cytotoxic mechanism in colon cancer cells. Dimensions of spherical shaped AIGNPs were found to be in the range of 1–20 nm as determined by TEM. GC–MS and FTIR analysis indicated the presence of polyphenolic groups in AILE, which might have been involved in the stabilization of AIGNPs. In vitro free radical scavenging analysis revealed the radical quenching activity of AIGNPs. Further, the AIGNPs exhibited cytotoxicity in HT-29 colon cancer cells with IC50 values of 210 and 180 μg/mL after 24 and 48 h. This was mediated through nuclear morphological changes and cell membrane damage as evidenced by acridine orange/ethidium bromide, propidium iodide and AnnexinV-Cy3 staining methods. Mechanism of the observed cytotoxicity of AIGNPs was explained on the basis of increased levels of reactive oxygen species and simultaneous reduction in cellular antioxidants, which might have caused mitochondrial membrane potential loss, DNA damage and G1/S phase cell cycle arrest. Expression of cleaved Caspase-9, Caspase-8, Caspase-3, Lamin A/C and PARP, provided the clues for the induction of intrinsic and extrinsic apoptosis pathways in AIGNPs treated HT-29 cells. The study provides a preliminary guidance towards the development of colon cancer therapy using green synthesized gold nanoparticles. © 2016 Elsevier B.V.

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.

Gupta K.K.,Pondicherry UniversityPuducherry | Sethi G.,Pondicherry UniversityPuducherry | Jayaraman M.,Pondicherry UniversityPuducherry
Journal of Vector Borne Diseases | Year: 2016

Background & objectives: It is well reported that exhaled CO2 and skin odour from human being assist female mosquitoes to locate human host. Basically, the receptors for this activity are expressed in cpA neurons. In both Aedes aegypti and Anopheles gambiae, this CO2-sensitive olfactory neuron detects myriad number of chemicals present in human skin. Therefore, manipulation of gustatory receptors housing these neurons may serve as important targets for behavioural intervention. The study was aimed towards virtual screening of small molecules in the analyzed conserved active site residues of gustatory receptor and molecular dynamics simulation study of optimum protein-ligand complex to identify a suitable lead molecule for distracting host-seeking behaviour of mosquitoes. Methods: The conserved residue analysis of gustatory receptor (GR) of Ae. aegypti and An. gambiae was performed. The structure of GR protein from Ae. aegypti was modeled and validated, and then molecular docking was performed to screen 2903 small molecules against the predicted active residues of GR. Further, simulation studies were also carried out to prove protein-ligand stability. Results: The glutamine 154 residue of GR was found to be highly conserved in Ae. aegypti and An. gambiae. Docking results indicated that the dodecanoic acid, 1,2,3-propanetriyl ester (dynasan 112) was interacting with this residue, as it showed better LibDock score than previously reported ethyl acetate used as mosquito repellant. Simulation studies indicated the structural instability of GR protein in docked form with dynasan 112 suggesting its involvement in structural changes. Based on the interaction energies and stability, this compound has been proposed to be used in mosquitoes’ repellant. Interpretation & conclusion: A novel effective odorant acting as inhibitor of GR is proposed based on its stability, docking score, interactions and RMSD, considering ethyl pyruvate as a standard inhibitor. Host preference and host-seeking ability of mosquito vectors play key roles in disease transmission, a clear understanding of these aspects is essential for preventing the spread of the disease. © 2016, Malaria Research Center. All rights reserved.

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.

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