Faculty Publications
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Item The measurement of electrical conductivity for the investigation of the number of water molecules present in the mixed crystals of barium copper oxalate and barium ammonium oxalate lattice have been carried out in the temperature range 30 to 450 °C. The dehydration temperature and the number of water molecules removed out of the structure at a particular temperature is estimated from the sharp increase in conductivity at these points. The almost steep increase of conductivity is attributed to the increase in the number of mobile charge carriers H+ and OH– ions generated from the escaping water molecules. The study of electrical conductivity in association with the thermal behaviour has been used to understand the mechanism of conduction. Copyright © 1995 WILEY?VCH Verlag GmbH & Co. KGaA(Electrical Conductivity and Thermal Dehydration Studies of Mixed Single Crystals of BaCu(C2O4)2 · 6 H2O, Ba1–xCuxC2O4 · 4 H2O and Ba1–2x(NH4)2xC2O4 · 4 H2O) Kasthuri, V.B.; Mohan Rao, P.1995Item Electro-oxidation of nimesulide at 5% barium-doped zinc oxide nanoparticle modified glassy carbon electrode(Elsevier B.V., 2016) Bukkitgar, S.D.; Shetti, N.P.; Kulkarni, R.M.; Doddamani, M.R.Development of methods for the detection of an analyte at low concentration with less time for analysis has become a prior point of interest to every analyst. In reflection of this fact, an effort has been made to synthesize 5% barium doped zinc oxide nanoparticles and was characterized by using XRD, EDX, SEM, and TEM. Further, 5% barium doped zinc oxide nanoparticle modified glassy carbon electrode was used for investigating the electro-chemical behavior of nimesulide. Voltammograms obtained in a range of 3.0-11.2 (I = 0.2 M) pH had a maximum peak current at pH 7.0. Various physio-chemical parameters such as, process on the surface of the electrode, which was found to be diffusion controlled, heterogeneous rate constant, number of electrons transferred and charge transfer coefficient were estimated. Further, a method for nimesulide determination in a linear range of 1.0 × 10- 5 to 1.0 × 10- 7 M with LOD 1.794 nM was proposed. This technique was later used for analytical application. © 2015 Elsevier Ltd. All rights reserved.Item Optical absorption, mechanical properties and FTIR studies of silver-doped barium phosphate glasses(Society of Glass Technology christine@glass.demon.co.uk, 2016) Narayanan, M.K.; Shashikala, H.D.Silver-doped barium phosphate glasses, of composition 50BaO-50P2O5-4Ag2O-4SnO, were prepared by conventional melt quenching and subsequent heat treatment. Prepared glasses were heat treated for a fixed duration of 10 h at different temperatures 400, 450 and 500°C to develop silver nanoparticles of different sizes. Formation and the size of the silver nanoparticles were evaluated using the surface plasmon resonance (SPR) band of the optical absorption spectrum, which revealed that both of them were temperature dependent. Spectral positions of the SPR peaks of the glass samples heat treated at 450 and 500°C were observed around 3.0 eV. Absence of significant size dependent shift in SPR peaks of these samples from 3.0 eV indicates the formation of spherical silver nanoparticles smaller than 20 nm inside the glass matrix, which falls in the quasi-static regime of Mie theory. The effect of heat treatment on the local network structure of the phosphate glass matrix assessed using FTIR spectra shows that formation and growth of silver nanoclusters do not affect the basic metaphosphate network structure. A slight improvement is observed in density as well as in the mechanical properties of the heat treated samples due to densification of the glass matrix by dispersed silver nanoparticles.Item Effect of BaO addition on the structural and mechanical properties of soda lime phosphate glasses(Elsevier Ltd, 2016) Edathazhe, A.; Shashikala, H.D.The phosphate glasses of composition (26-x)Na2O-xBaO-29CaO-45P2O5 (x = 0,5,10,15 mol%) are prepared by melt-quenching technique. The variations in structural and mechanical properties are studied on glasses prepared at 1000, 1100 and 1200? C. The density of glasses increases with barium content for glasses prepared at different temperatures. The molar volume is nearly constant with compositional parameter. The amorphous nature of samples is confirmed by XRD. The calculated values of mass percentage of elements in the batch composition and EDS data are in a reasonable agreement. The FTIR spectra show that the main structural units in these glasses are Q1 and Q2 phosphate units. The frequency of the P[sbnd]O[sbnd]P band remains constant with barium substitution. The microhardness is measured using Vickers indentation method by applying 0.98 N for 10 s. The hardness and fracture toughness are independent of composition. The nature of crack formations is examined by SEM. The brittleness and crack length are correlated with plastic flow in the material. © 2016 Elsevier B.V.Item Source apportionment of PM2.5 particles: Influence of outdoor particles on indoor environment of schools using chemical mass balance(AAGR Aerosol and Air Quality Research hhyang@cyut.edu.tw, 2017) Kalaiarasan, G.; Mohan Balakrishnan, R.M.; Sethunath, N.A.; Manoharan, S.Children have higher lung function than adults and they spend most of their day time in schools. Also, children studying at schools located in the vicinity of busy roadways are vulnerable to childhood asthma and respiratory disorders. The present study is focused on estimating the sources of PM2.5 particles present in the indoor air quality in schools which are located adjacent to urban and suburban roadways. The indoor PM2.5 samples from all the four schools were collected using fine dust sampler from 8 a.m. to 4 p.m. The sampling was carried out for one complete week during various seasons including both working and non-working days. The chemical compositions of the PM2.5 samples were analyzed for certain elements like Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti, V and Zn using Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) and ions like F-, Cl-, NO3-, PO43-, SO42-, K+, Ca2+, Mg2+, NH4+, Na+ using Ion Chromatography (IC). Source apportionment study using Chemical Mass Balance was carried out using the species concentration of the collected samples. The major sources were found to be Paved Road Dust, Soil Dust, Gasoline Vehicle Emissions, Diesel Vehicle Emissions and Marine Source Emissions. Among these, vehicular emissions contribution was found to be higher for the schools located close to roadways rather than the school located at a considerable distance from highway. The difference in source type contribution at each school clearly depicts the difference in nature of location and type of activities in the vicinity of the sampling sites. © Taiwan Association for Aerosol Research.Item Synthesis, structural, optical and electrical (DC) properties of a semiorganic Thiourea Barium Chloride (TBC) single crystal(Elsevier GmbH journals@elsevier.com, 2017) Mahendra, K.; D'Souza, A.; Udayashankar, N.K.In the present study, TBC single crystals were synthesized using solution evaporation method. The structural analysis of TBC crystal was studied using Powder X-ray diffraction. Optical properties of TBC crystals were carried out using UV–vis, FTIR, Raman and photoluminescence (PL) spectra. The crystal shows absorbance maxima at 209 nm and transparent in the visible region 300–900 nm. The various optical constants such as refractive index, reflectance, speed of light, extinction coefficient, electrical susceptibility, dielectric constant, optical and electrical conductivity were evaluated. Thus results revealed that all these optical constants shows a strong dependence on optical absorption coefficient. Using single oscillator model (Wemple ?Didomenico), lattice dielectric constant and the ratio of free charge carrier to their effective mass were evaluated. The PL study of TBC crystals shows two emission peaks (419 nm ?S, 441 nm- Ba) in blue region. The DC resistivity and conductivity of the crystal was investigated in the temperature range 26 °C–115 °C. © 2017 Elsevier GmbHItem Silver doped barium titanate nanoparticles for enhanced visible light photocatalytic degradation of dyes(Elsevier Ltd, 2024) Bhava, A.; Shenoy, U.S.; Bhat, D.K.Due to the rapid growth of global population, new, fast and reliable methods must be developed to purify contaminated water. Various photocatalysts have been developed to remove organic dyes from water. Herein, Ag doped BaTiO3 has been synthesized using a facile solvothermal method and its excellent photocatalytic activities were demonstrated in degradation of both anionic and cationic dyes under visible light illumination. Ag doped BaTiO3 nanoparticles showed greater efficacy in the degradation of methylene blue (MB) and eosin yellow (EY) than undoped BaTiO3 nanoparticles, which makes them a better candidate for photocatalysis. 1.0 AgBT sample showed the highest photocatalytic activity for MB (99.1 % in 100 min) and EY (99.3 % in 60 min) dye degradation compared with those of other samples. Further, the trapping experiments revealed that hydroxyl radicals and holes are the active species in the photocatalytic process of MB and EY dye degradation and recycle test showed excellent stability of the synthesized material. © 2024 Elsevier Ltd