Faculty Publications
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Item Cu-44Ni-5Cr alloy has been subjected to thermomechanical treatment which consisted of plastic deformation of as-quenched material by 50, 65 and 80% reduction in thickness followed by ageing in the interval of 500 to 650 °C for various durations of time. Progress in age-hardening was studied by means of hardness measurement and X-ray diffraction studies. The wavelength of composition modulation and strain amplitude were measured. It was found that age-hardening was a result of interaction between spinodal decomposition and recovery processes. Prior deformation was found to enhance the kinetics of both spinodal decomposition and coarsening. It was concluded that this resulted from increased vacancy concentration and increased coherency strain in the cold-worked material. © 1994 Chapman & Hall.(Kluwer Academic Publishers, Effect of thermomechanical treatment on the phase transformation in Cu-44Ni-5Cr alloy) Raghavendra Bhat, R.; Prasad Rao, P.1994Item Progress in spinodal decomposition of a Cu-32Ni-2Cr alloy subjected to quench?age and quench?work?age treatments have been studied through hardness measurements as well as by X-ray diffraction techniques. It is found that recovery processes occur during early stages of aging which are interpreted in terms of the migration of matrix dislocations to interfaces. The kinetics of spinodal decomposition is found to be enhanced by prior deformation. Thermomechanical treatment results in a substantial increase in strength.(Publ by Carl Hanser Verlag GmbH & Co, Thermomechanical treatment of spinodal Cu-32Ni-2Cr alloy) Bhat, R.Raghavendra; Prasad Rao, P.1994Item Conversion of waste polypropylene to liquid fuel using acid-activated kaolin(SAGE Publications Ltd, 2014) Panda, A.K.; Singh, R.K.Waste polypropylene was subjected to thermal degradation in the presence of kaolin and acid-treated kaolin, with different catalyst-to-plastics ratios, in a semi-batch reactor at a temperature range of 400-550°C to obtain optimized process conditions for the production of liquid fuels. The effects of process temperature, catalyst and feed composition on yield and quality of the oil were determined. For a thermal decomposition reaction at up to 450°C, the major product is volatile oil; and the major products at a higher temperature (475-550°C) are either viscous liquid or wax. The highest yield of condensed fraction in the thermal reaction is 82.85% by weight at 500°C. Use of kaolin and acid-treated kaolin as a catalyst decreased the reaction time and increased the yield of liquid fraction. The major product of catalysed degradation at all temperatures is highly volatile liquid oil. The maximum oil yield using kaolin and acidtreated kaolin is 87.5% and 92%, respectively, at 500°C. The oil obtained was characterized using GC-MS for its composition and different fuel properties by IS methods. © The Author(s) 2014.Item Adsorption and photocatalytic properties of NiO nanoparticles synthesized via a thermal decomposition process(Cambridge University Press, 2018) Ramesh, M.; Rao, M.P.C.; Anandan, S.; Nagaraja, H.S.NiO nanoparticles (NPs) were synthesized at different annealing temperatures via a thermal decomposition process and characterized using X-ray diffraction, scanning electron microscopy, and UV-vis spectroscopy. The NiO NPs prepared at higher annealing temperature (400 °C) were shown excellent adsorption and photocatalytic activity toward textile dyes reactive black 5 (RB-5) and methylene blue (MB). About 87.2% of RB-5 in 60 min and 70.2% of MB in 5 h was removed using NiO NPs synthesized at 400 °C. The photocatalytic degradation of MB was found to increase with an increase in the annealing temperature of the catalyst. Moreover, the kinetic study revealed that the adsorption and photocatalytic activity of NiO NPs followed the second and first-order kinetics, respectively. The enhanced performance of NiO NPs toward dye removal might be related to its optical and structural properties. © Materials Research Society 2018.Item Triboelectric effect based self-powered compact vibration sensor for predictive maintenance of industrial machineries(IOP Publishing Ltd, 2021) Hosangadi Prutvi, H.P.; Meti, S.; Bhat K, U.K.; Gupta, D.This article showcases a compact self-powered contact-mode triboelectric (TE) phenomenon-based vibration sensor for predictive maintenance of industrial machinery. The sensor has a suspended proof-mass that oscillates under external vibration and causes contact-separation between Teflon and zinc oxide (ZnO) films creating tribo signals, which are used for both sensing and powering mechanisms. For these sensors to be implemented in real-time applications, the sensor must be cost-effective, reliable, and repeatable. Hence, the active layer (ZnO film) is fabricated by an efficient process of microwave-assisted thermal decomposition followed by the established screen printing method. The sensor operates up to 400 Hz and is highly robust with no significant decay in signal strength even after 120 000 cycles tested at elevated stress values. The device produces a maximum voltage (V) of ±30 V, short circuit current of ±3 ?A, and can deliver a maximum power density of 0.5 W m-2, at 8 M? load resistance. In the frequency domain, the device generates a maximum V at 55 Hz and can charge 1 µF capacitor to 3.5 V in 25 s. To demonstrate the functionality of the sensor in a real application, it is implemented on a lab-scale vacuum pump to capture the system faults by analyzing the harmonic signatures. Thus, in this article, we have showcased end-to-end development of the sensor from material synthesis to device testing along with its signal processing techniques and proved that the sensor can readily be implemented in industrial environments as is. This article thus emphasis bridging the lab-to-market gap for TE devices as a self-powering sensor. © 2021 IOP Publishing Ltd.Item A novel approach to the synthesis of semiorganic ammonium hydrogen oxalate oxalic acid dihydrate single crystal and its characterization(Springer Science and Business Media B.V., 2021) Mahendra, K.; Fernandes, J.M.; Udayashankar, N.K.A different approach used in the synthesis of ammonium hydrogen oxalate oxalic acid dihydrate (NH4H3(C4O8)·2H2O) single crystals is presented. The crystals are synthesized using solvent evaporation technique. The analysis of the synthesized NH4H3(C4O8)·2H2O single crystals has been carried out through measurements such as single-crystal X-ray diffraction (SCXRD), powder XRD, UV–Vis and photoluminescence spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis (TG–DTA), Vickers microhardness measurements and current versus voltage (I–V) characteristics. The evaluation of the molecular structure of the crystals using SCXRD shows that they belong to the triclinic crystal system with space group P-1. The structural properties of the crystals are also evaluated using powder XRD measurements on their finely crushed powder. These measurements corroborate the results of SCXRD and confirm the triclinic system of the crystals. The optical properties like absorbance and emission of these crystals are determined using UV–Vis and photoluminescence spectroscopy, respectively. These measurements show that the crystals exhibit substantial emission in the blue region. The thermal stability and the decomposition mechanism of the crystals is studied using TG–DTA analysis. The mechanical strength of the crystals is determined using Vickers microhardness technique. The photoresponse of the NH4H3(C4O8)·2H2O crystals is analyzed from light-dependent I–V characteristics, and it is observed that the crystals exhibit photoresistive behavior. © 2020, Akadémiai Kiadó, Budapest, Hungary.Item Click chemistry assisted synthesis of imidazo[1,2-a]pyrimidine-1,2,3-triazole hybrids as promising antitubercular agents: Design, characterization, in-vitro biological evaluation, molecular docking, DFT and in-silico ADME studies(Elsevier B.V., 2025) P, D.; Naik, S.; Veeranagaiah, N.S.; Udayakumar, U.In this work, the molecular hybridization approach was employed to design a series of imidazo[1,2-a]pyrimidine -1,2,3-triazole derivatives (P1-P18), and the designed hybrid molecules were synthesized using a click chemistry protocol. The structure of one of the final compounds P10, was validated by single-crystal X-ray diffraction investigation. Among these 18 compounds, P3, P13, and P15 demonstrated encouraging antitubercular action against the M. tuberculosis H37Rv strain with minimum inhibitory concentrations (MIC) of 12.05 and 11.95 µM of (P3 and P13) or 6.75 µM (P15). In addition, at various concentrations, the target compounds demonstrated strong antifungal activity against P. anomala and A. flavus and antibacterial activity against S. aureus and Escherichia coli. The potent anti-TB agents (P3, P13, and P15) are non-toxic in the toxicity test performed using VERO cell lines. Furthermore, In-silico ADME, molecular docking (with InhA and CYP121), and DFT analysis data revealed that the active compounds have substantial potential as candidates for the development of novel antitubercular medicines. © 2025 Elsevier B.V.