Faculty Publications
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Item Characterization of thin film Al/p-CdTe schottky diode(2008) Mahesha, M.G.; Kasturi, V.B.; Shivakumar, G.K.A study has been made on the behavior of Al/p-CdTe thin film junction grown by thermal evaporation method. I-V characteristics show that the Al makes Schottky contact with p-CdTe. The variation of junction capacitance with frequency and voltage has been studied to evaluate the barrier height. The activation energy and band gap have been estimated by studying variation of resistivity with temperature. Using all these data, band diagram of Al/p-CdTe has been proposed. © TÜB?TAK.Item Interparticle interactions and lacunarity of mechano-chemically activated fly ash(Elsevier, 2015) Patil, A.G.; Shanmugharaj, A.M.; Anandhan, S.A class F fly ash was subjected to high-energy ball milling-induced mechano-chemical activation aided by a surfactant. The resultant nanostructured fly ash was characterized by various techniques. X-ray fluorescence results showed that the amount of iron oxide was reduced from 4.39% to 2.75% after pre-treatment of fly ash by magnetic separation. Ethyl acetate as the milling medium, a ball to powder ratio of 12:1 and 2wt% of surfactant reduced the average particle size of fly ash to 329nm and led to a specific surface area of 8.73m2/g. The decrease in crystallite size of mechano-chemically activated fly ash was confirmed from a reduction in peak intensity with a broadened amorphous phase by X-ray diffraction studies. X-ray photoelectron spectroscopic characterization illustrated that peak area of major elements (O, Si and Al) increased after milling. Morphological and FTIR studies revealed that the smooth and inert surface of the fly ash was converted to a rough and more reactive one after mechano-chemical activation. The surface modification of fly ash with the surfactant was determined from FTIR spectroscopy. Also, a fractal approach was used to characterize the lacunarity of the agglomerates in the nanostructured fly ash. © 2014 Elsevier B.V.Item Influence of planetary ball milling parameters on the mechano-chemical activation of fly ash(Elsevier, 2015) Patil, A.G.; Anandhan, S.This study illustrates the design of statistical analysis by Taguchi methodology to obtain nanostructured fly ash by planetary ball milling. An orthogonal array and analysis of variance were employed to analyze the effect of milling parameters. A class-F fly ash was subjected to planetary ball milling induced mechano-chemical activation aided by a surfactant. Ball milling parameters, such as ball-to-powder weight ratio, type and quantity of surfactant and type of medium were varied as guided by the Taguchi design. The nanostructured fly ash was characterized by dynamic light scattering, BET surface area analysis, X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy. The ball-to-powder weight ratio and the surfactant type are the major influencing factors on lower crystallite size and average particle size and higher specific surface area. The surface modification of fly ash was confirmed by FTIR spectroscopy. The nano fly ash produced by this method has a wide application potential in polymer industries as reinforcement in composites. © 2015 Elsevier B.V.Item Nanostructured Fly Ash as Reinforcement in a Plastomer-Based Composite: A New Strategy in Value Addition to Thermal Power Station Fly Ash(Springer Netherlands, 2016) Patil, A.G.; Mahendran, A.; Anandhan, S.Class-F fly ash (FA) from a coal-fired thermal power station was subjected to high energy ball milling-induced mechanochemical activation aided by a surfactant. Subsequently, ethylene-octene copolymer/mechanochemically activated FA (EOC/MCA-FA) composites were prepared by solution casting. The surface modification of FA was confirmed from contact angle measurements and FTIR spectroscopy, which accounts for a good interaction between MCA-FA and the polymer matrix. X-ray diffraction reveals that the crystallite size of quartz phase present in FA got reduced, while the relative lattice strain on it increased during milling. Morphological studies revealed that interfacial adhesion between the polymer and MCA-FA is good and this accounts for the improvement in mechanical properties of the composites even at the minimum filler loading. Flame retardance of the matrix polymer is improved by the addition of either fresh FA or MCA-FA. The results imply that FA is a valuable reinforcing filler for ethylene-octene copolymer and its mechanochemical activation is an effective strategy for its future use. © 2014, Springer Science+Business Media Dordrecht.Item Effect of electrolyte temperature on the formation of highly ordered nanoporous alumina template(Elsevier B.V., 2016) Boominathasellarajan, B.; Sharma, M.; Ghosh, S.K.; Nagaraja, H.S.; Barshilia, H.C.; Chowdhury, P.In this work, we present a systematic influence of electrolyte temperature along with anodizing potential on the pore parameters during two-step anodization of Al in H2SO4 electrolyte. Top surface morphology of the nanoporous templates was examined with the help of field emission scanning electron microscope and atomic force microscope. Three-dimensional (3D) Fast Fourier Transform (FFT) image analysis was then employed to quantify pore regularity and pore periodicity as a function of both the bath temperature (1-15 °C) and the anodic potential (15-25 V). A highest pore regularity ratio of 5 × 108 was obtained at 3°C and 25 V with a pore diameter of 32 ± 3 nm and inter-pore distance of 65 nm. With further increase in temperature, the pore regularity ratio was found to decrease drastically. It was found that higher temperature favored the dissolution of compact aluminum oxide layer isotropically along the pore length. This process in effect enhanced the pore size, growth rate, and template top surface roughness without affecting much inter-pore distance. Self-ordering of the pores was found to improve with increasing anodizing potential with a critical influence of the current density along with inter-pore distance. The mechanism of pore growth was discussed in terms of temperature-dependent activation energy controlled dissolution of aluminum. The typical activation energy evaluated at 25 V was 72.8 kJ/mol at 3°C. © 2015 Elsevier Inc. All rights reserved.Item Corrosion behavior of 6061/Al-15 vol. pct. SiC(p) composite and the base alloy in sodium hydroxide solution(Elsevier B.V., 2016) Reena Kumari, P.D.; Nayak, J.; Nityananda Shetty, A.The corrosion behavior of 6061/Al-15 vol. pct. SiC(p) composite and 6061 Al base alloy was investigated in a sodium hydroxide solution. The electrochemical parameters were derived from potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) techniques. The results showed that the corrosion resistance of the composite was lower than that of the base alloy in selected corrosion media. The corrosion rates of both the composite and the base alloy increased with the increase in the concentration of sodium hydroxide and also with the increase in temperature. The surface morphology of the metal surface was investigated using scanning electron microscope (SEM). Activation energy was evaluated using Arrhenius equation, and enthalpy of activation and entropy of activation values were calculated using transition state equation. © 2012Item Comparative evaluation of phosphate abatement using laterite soil and activated carbon(Center for Environmental and Energy Research and Studies editor@ijest.org, 2019) Sreekumar, U.; Thalla, A.K.; Nair, V.V.Abstract: The present study aims to evaluate and compare the suitability of thermally activated laterite soil (TAL) and activated carbon (AC) as adsorbents in the abatement of phosphates (PO4 3?) from synthetic wastewater. The AC was derived from the wasted sludge of an activated sludge process by subjecting it to an activation temperature of 600 °C. The impregnation ratio of 1 (sewage sludge): 1 (KOH) was used for the present study. The soil and wasted sludge were characterized to determine the constituents, and the adsorbents were prepared by thermal and chemical activation, respectively. The AC exhibited a maximum iodine number of 837.51 mg/g using KOH as an activating agent. Batch and column studies were conducted to determine the dependency on pH, contact time, adsorbent dosage and initial PO4 3? concentration. An optimum PO4 3? removal using TAL and AC was achieved around pH 6. The removal efficiency of AC was found to be slightly higher than the efficiency obtained from TAL. The percentage removal of PO4 3? obtained from batch adsorption studies was found to be higher than that obtained by column studies. The equilibrium adsorption data from batch studies were attempted to fit with linear, Langmuir and Freundlich isotherm models. Residual and least square analysis confirms the Freundlich isotherm to be the best fit. Graphical abstract: [Figure not available: see fulltext.] © 2018, Islamic Azad University (IAU).Item Ductility and Flame Retardancy Enhancement of PVC by Nanostructured Fly Ash(Springer editorial@springerplus.com, 2019) Patil, A.G.; Mahendran, A.; SelvaKumar, M.; Anandhan, S.Fly ash (FA) obtained from a coal-fired local thermal power station was converted into a nanostructured material by mechano-chemical activation using a high energy planetary ball mill. Contact angle measurements and FTIR spectroscopy confirmed the surface modification of mechano-chemically activated FA (MCA-FA). Subsequently, a solution casting method was used to prepare poly(vinyl chloride) (PVC) matrix composites with varying amounts of fresh FA and MCA-FA. Mechanical testing results of the composites revealed that incorporation of fresh FA in PVC resulted in a higher tensile strength with brittle failure; addition of MCA-FA to PVC resulted in higher elongation at break values while retaining the ductility of the PVC. We have proposed a plausible mechanism explaining the influence of fresh FA and MCA-FA on the mechanical behavior of these composites. As fresh FA and MCA-FA contain basic oxide materials, they tend to improve the fire retardancy of PVC even at a very small loading. Overall, the nanostructured MCA-FA could find application as a filler in PVC-based products. © 2016, Springer Science+Business Media Dordrecht.Item Real-time microscopy image-based segmentation and classification models for cancer cell detection(Springer, 2023) Devi, T.G.; Patil, N.; Rai, S.; Philipose, C.P.Image processing techniques and algorithms are extensively used for biomedical applications. Convolution Neural Network (CNN) is gaining popularity in fields such as the analysis of complex documents and images, which qualifies the approach to be used in biomedical applications. The key drawback of the CNN application is that it can’t call the previous layer output following the layer’s input. To address this issue, the present research has proposed the novel Modified U-Net architecture with ELU Activation Framework (MU-EAF) to detect and classify cancerous cells in the blood smear images. The system is trained with 880 samples, of which 220 samples were utilized in the validation model, and 31 images were utilized to verify the proposed model. The identified mask output of the segmentation model in the predicted mask fits the classification model to identify the cancer cell occurrence in the collected images. In addition, the segmentation evaluation is done by matching each pixel of the ground truth mask (labels) to the predicted labels from the model. The performance metrics for evaluating the segmentation of images are pixel accuracy, dice coefficient (F1-score), and Jaccard coefficient. Moreover, the model is compared with VGG-16 and simple modified CNN models, which have four blocks, each consisting of a convolutional layer, batch normalization, and activation layer with RELU activation function that are implemented and for assessing the same images used for the proposed model. The proposed model shows higher accuracy in comparison. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Biomass waste-derived porous graphitic carbon for high-performance supercapacitors(Elsevier Ltd, 2024) Hegde, S.S.; Badekai Ramachandra, B.R.Porous carbons possess considerable appeal and are in high demand as materials that can be produced from biomass waste. This study presents the transformation of Tectona grandis (Teak) sawdust into porous carbon materials, referred to as Tectona grandis sawdust-derived porous carbon (TPC), through a cost-effective FeCl3-assisted carbonization process, followed by a KOH activation. TPC samples were synthesized by carbonization at different temperatures (650–850 °C) and characterized comprehensively. Structural analysis via X-Ray diffraction (XRD), Raman, and Fourier Transform Infrared Spectroscopy (FTIR) revealed a progressive enhancement in graphitic structure and reduction of functional groups with increasing activation temperature. Field emission scanning electron microscopy (FESEM) displayed the development of intricate hollow tube-like porous networks in TPC-850, with the highest specific surface area (1767.66 m2/g) and pore volume (1.43 cm3/g). Electrochemical investigations showcased the superior performance of TPC-850 as a supercapacitor electrode due to its high graphitic nature, large surface area, and well-structured porosity. The galvanostatic charge-discharge (GCD) measurements exhibited a high specific capacitance of 572 F/g at 0.5 A/g in a 6 M KOH electrolyte. The high-frequency semicircle and low-frequency steeper region in electrochemical impedance spectroscopy (EIS) further indicated reduced resistance and enhanced ion diffusion in TPC-850. Significantly, TPC-850 demonstrated remarkable electrochemical cyclic stability, retaining 95.83 % of its initial capacity even after undergoing 4500 cycles at a scan rate of 500 mV/s. The findings underscore the viability of TPC-850 as a high-performance supercapacitor electrode material, providing insights into harnessing renewable resources for advanced energy solutions. This work highlights the potential of utilizing waste biomass for energy storage applications and demonstrates the feasibility of converting it into efficient porous carbon materials with substantial graphitization and porosity. © 2023 Elsevier Ltd