Faculty Publications
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Item Green Synthesis of Nanomaterials(Elsevier, 2018) Devatha, C.P.; Thalla, A.K.The nanotechnology industry is increasingly promoting nano as a “green” technology that will improve the environmental performance of existing industries, reduce consumption of resources and energy, and allow achievement of environmentally benign economic expansion. Eco-friendly solutions are gaining popularity in the contemporary world. A green method for nanoparticle synthesis should be assessed considering three aspects: the solvent, the capping agent, and the reducing agent compared to physical and chemical methods. Particularly, the plant extracts mediated process is a good and advantageous method for the development of metal nanoparticles compared to using microorganisms, in which the cell maintenance time is limited. Synthesis and characterization of nanoparticles are important steps to be adopted to apply nanoparticles in field applications, and these steps include preparation of leaf extract, Phytochemical screening, and preparation of precursor. Various factors affecting the synthesis of nanoparticles, such as pH, temperature, and time, will be discussed. The degradation of any organic compounds by the green approach (plant extracts) is mainly due to the presence of polyphenols in the biodegradable material. Although the synthesis of nanoparticles has been trending higher, their application in the area of waste water treatment has been limited until recently. Hence, the application of nanoparticles to waste water treatment will be discussed with a view toward paving the way for an alternate source of water. © 2018 Elsevier Ltd. All rights reserved.Item Synthesis, growth and characterization of 1-(5-chlorothiophen-2-yl)-3-(2,4, 5-trimethoxyphenyl) prop-2-en-1-one single crystal: A potential NLO material(2011) Prabhu, A.N.; Upadhyaya, V.; Arasalike, A.; Maddasani, M.; Manjunatha, K.B.; Umesh, G.A potentially useful nonlinear optical (NLO) organic material, 1-(5-chlorothiophen-2-yl)-3-(24,5-trimethoxyphenyl)prop-2-en-1-one(CTTMP), has been synthesized and grown as a high-quality single crystal by the slow evaporation technique. The grown crystals were characterized by UV-visible spectroscopy. The material has thermal stability up to its melting point. Single beam Z-scan technique was employed to study the third order NLO properties of the material. © 2011 American Institute of Physics.Item A detailed study on hybrid plant fibers for packaging applications(2012) Saravana Bavan, D.; Mohan Kumar, G.C.Natural fibers are the most economic and usable fibers in upcoming generation of composite industries. They are valid in several applications of automotive sectors, structural field, and packaging industries. The present work is focussed on processing a hybrid plant fiber of vetiver and maize that can be used for packaging industries. The hybrid fiber is processed through Vacuum Assisted Resin Transfer Molding (VARTM) method. The obtained fiber is a biocomposite material of plant fiber and bio resin of epoxodized soya bean oil. The material is tested for mechanical, thermal and morphology properties and it can be summarized that these novel hybrid fibers are good looking and have appreciable properties that can be used for packaging applications. These materials are green and less harm to environment compared to synthetic fibers.Item Mechanical characterization of adhesive layer using Double strap joint specimens(Elsevier Ltd, 2022) Sahana, T.S.; Kaliveeran, V.; Kundapura, S.In practical applications, most of our mechanical and civil structures are subjected to either oscillatory or static load. To design those structures, stress analysis is needed to withstand the design loads. In experimental stress analysis, strain gauges are mounted on those structures to determine stress at a point. Usually, strain gauges are mounted on the substrate using proper adhesives. The quality of strain data is a function of proper mounting. The thickness of adhesives used for mounting techniques should be optimum and very thin to ensure quality results. The underlying adhesive layer acts as an interface between the substrate and the strain gauge. This adhesive layer receives the maximum shear stress when the member is loaded in tension. Therefore, in this research work, the main focus is on characterizing the Araldite adhesive material. A tension test was conducted on the prepared bulk specimen to characterize the adhesive. The Double Strap Joint (DSJ) tests were conducted to investigate the interfacial shear strength and failure modes according to ASTM D 3528 standards. Two sets of specimens, such as plain and knurled straps, were used in this research work. The failure mode in the plain strap joint shows cohesive failure, and the knurled strap joint shows adhesive failure. © 2022Item Iron Ore Characterization Techniques in Mineral Processing(Springer, 2024) Poojari, M.; Vardhan, H.; Jathanna, H.M.While iron is a pivotal metal that is exploited commercially, its extraction from ores, subsequent processing and purification follows a series of steps, and material characterization in terms of physical, chemical and mineralogical features and behavior is imperative at each stage. Some characterization tests rely solely on physical measurements, while others are based on optical and chemical data. Thus, employing these techniques is critical for gaining a complete understanding of ore characteristics such as physical, chemical, textural, mineralogical, granulometric, etc., in order to forecast its behavior during processing operations, and as a result, to optimize the process. Consequently, this review highlights some of the primary characterization tests such as SEM (Scanning Electron Microscopy), XRD (X-ray Diffraction), and FTIR (Fourier Transform Infrared spectroscopy) used in iron ore processing and their significance in analyzing various properties such as elemental composition, porosity, mineral association, and liberation, among others, while also introducing additional and emerging techniques used in iron ore mineralogical assays and processing operations. Characterization tests are presented used not just for high-grade iron ores, but also for low-grade discard materials such as fines and tailings. While optical microscopy and SEM aid in micro-morphological examinations, and XRD, FTIR, and other techniques aid in detailed chemical investigations, TGA and BET assist in physical characterization. A combination of these techniques may be deemed ideal for gaining a thorough understanding of ore characteristics as well as ore processing. © The Institution of Engineers (India) 2023.Item Electroslag remelting experiments have been carried out on En 24 steel using two slag compositions in indigeneously constructed 350 KVA DC and 50 KVA AC ESR units. Detailed quantitative characterisation of the inclusions of different types has been carried out using Quantimet Image Analyser. The inclusion content in terms of volume fraction and density (No/mm2) and their size distribution in the refined ingot and the unrefined steel have been assessed. The chemical composition of selected inclusions has been established by electron probe microanalyser (EPMA). These studies are supplemented by scanning electron microscopy on typical fractured specimens. The present study shows that the DC reverse polarity mode of melting using a slag with higher silica content (10 wt%) offers the best conditions with particular reference to removal of inclusions and modification of inclusion morphology as compared to the ingots produced by DC straight polarity and AC modes of melting.(Studies on inclusion characterization in electroslag refined En24 steel) Udupa, K.R.; Subramanian, S.; Sastry, D.H.; Iyengar, G.N.K.1994Item Semiconducting thin films of cadmium telluride, both p-type and n-type, have been prepared by conventional thermal evaporation technique. The influence of various growth parameters such as the rate of deposition, deposition temperature, post-deposition heat treatment, and source material composition has been investigated. The films deposited at high deposition rates and low substrate temperatures exhibited an excess of tellurium and showed a p-type conductivity, whereas those deposited at high substrate temperature and low deposition rates contained excess cadmium and are n-type in nature. An intrinsic bandgap of 1.49 eV for stoichiometric films obtained by both electrical and optical characterization is reported.(Growth and characterization of vacuum deposited cadmium telluride thin films) Shreekanthan, K.N.; Kasturi, V.B.; Shivakumar, G.K.2003Item Synthesis and characterization of nanocrystalline Mo-V-W-Fe-O mixed oxide catalyst and its performance in selective methanol oxidation(2007) Badekai Ramachandra, B.; Choi, J.-S.; Kim, T.-H.A mixed oxide catalyst containing Mo, V, W and Fe with the composition of 63, 23, 09 and 06 wt% respectively for the selective oxidation of the methanol to formaldehyde is in reported in this paper for the first time. The characterization of the catalyst was done using BET surface analysis, X-ray diffraction (XRD), Infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Energy dispersive X-ray (EDX). The mixed oxide after calcination at 673 K in N2 which was subjected for the thermal activation in N 2flow at 813 K was used for the methanol selective oxidation. The thermal treatment shows enhanced catalytic performance. Thermal activation of the nanocrystalline Mo0.63V23W0.09Fe 0.06O x precursor oxide in nitrogen atmospheres induces partial crystallization of a Mo5O14-type oxide only in a narrow temperature range up to 813 K. XRD showed that the thermally activated mixed oxide consists of a mixture of a majority of crystalline Mo 5O14-type oxide and of small amounts of crystalline MoO3-type and MoO2-type oxides. The structural analysis suggests that the improvement of the catalytic performance of the MoVWFe oxide catalyst in the selective oxidation of methanol is related to the formation of the catalytic active site such as Mo5O14-type mixed oxide. © 2007 Springer Science+Business Media, LLC.Item Characterization of a coastal aquifer—a case study(2009) Saldanha, J.P.; Vyshali; Mahesha, A.The present study deals with the characterization of the coastal aquifer in the Pavanje river sub-basin through the pumping tests and the electrical resistivity tests. The electrical resistivity tests are also used to study the geology of the aquifer and possible saltwater intrusion. The transmissivity of the region varies from 50 m2/d—160 m2/d and the specific yield up to 8%. The results of the electrical resistivity tests indicate that the top surface is having a resistivity of 400—1000 ohm-m with an average thickness of 5 m and the bottom layer is having the resistivity of 80—300 ohm-m with an average depth of 20 m. Additionally, an attempt was made to model the groundwater flow in the region using FEFLOW software for the period between June, 2006 and April, 2007. The model is run for different pumping scenarios considering the probable developments in the region. Saltwater intrusion is predicted at some specific locations due to low water table condition during the summer. The water budget estimation indicates that there is significant groundwater outflow from the area during June to November. Hence, it is necessary to carry out investigations to arrest this outflow which may be utilized during the lean season. © 2009 Taylor & Francis Group, LLC.Item Production and characterization of biosurfactant produced by a novel Pseudomonas sp. 2B(2012) Aparna, A.; Srinikethan, G.; Smitha, H.Biosurfactant-producing bacteria were isolated from terrestrial samples collected in areas contaminated with petroleum compounds. Isolates were screened for biosurfactant production using Cetyl Tri Ammonium Bromide (CTAB)-Methylene blue agar selection medium and the qualitative drop-collapse test. An efficient bacterial strain was selected based on rapid drop collapse activity and highest biosurfactant production. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, 2B, identified the bacterium as Pseudomonas sp. Five different low cost carbon substrates were evaluated for their effect on biosurfactant production. The maximum biosurfactant synthesis (4.97g/L) occurred at 96h when the cells were grown on modified PPGAS medium containing 1% (v/v) molasses at 30°C and 150rpm. The cell free broth containing the biosurfactant could reduce the surface tension to 30.14mN/m. The surface active compound showed emulsifying activity against a variety of hydrocarbons and achieved a maximum emulsion index of 84% for sunflower oil. Compositional analysis of the biosurfactant reveals that the extracted biosurfactant was a glycolipid type, which was composed of high percentages of lipid (~65%, w/w) and carbohydrate (~32%, w/w). Fourier transform infrared (FT-IR) spectrum of extracted biosurfactant indicates the presence of carboxyl, hydroxyl and methoxyl functional groups. The mass spectra (MS) shows that dirhamnolipid (l-rhamnopyranosyl-l-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C 10-C 10) was detected in abundance with the predominant congener monorhamnolipid (l-rhamnopyranosyl-?-hydroxydecanoyl-?-hydroxydecanoate, Rha-C 10-C 10). The crude oil recovery studies using the biosurfactant produced by Pseudomonas sp. 2B suggested its potential application in microbial enhanced oil recovery and bioremediation. © 2012 Elsevier B.V..