Faculty Publications

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Publications by NITK Faculty

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    Evaluation of feeding strategies for enhanced cell-associated tannase production by serratia ficaria dtc
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Belur, P.D.; Goudar, D.C.
    Batch studies on Cell-associated tannase production showed 2.6 U/L activity in the declining phase of growth in the bioreactor. It was observed that Cell-associated tannase production under declining phase was depending upon the bacterial biomass produced under exponential phase and gallic acid level. The peak production of enzyme was always accompanied by a sharp rise in dissolved oxygen concentration. Based on these observations, fed batch fermentation by feeding a mixture of nutrients (glucose and tryptose) and Dissolved oxygen (DO) based feeding strategy of gallic acid were designed. Nutrient feeding strategy showed 10 U/L of enzyme activity at 14th h of fermentation. DO based feeding strategy of gallic acid resulted in the production of 14.4 U/L enzyme activity in the 12th h of fermentation. The enzyme production rate of 1.2 U/L.h achieved in this mode was 4.6–fold greater than the values observed in batch process and 1.68 fold greater than the productivity achieved by feeding nutrients. Hence, DO based feeding strategy of gallic acid was proved to be an effective strategy for enhanced cell-associated tannase production by Serratia ficaria DTC. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    Design and construction of BCH codes for enhancing data integrity in multi level flash memories
    (Inderscience Publishers, 2012) Rajesh Shetty, K.; Ramakrishna, K.; Prashantha Kumar, H.; Sripati, U.
    Flash memories have found extensive application for use in storage devices. The storage capacity and reliability of these devices have increased enormously over the years. With increase in density of data storage, the raw bit error rate (RBER), associated with the storage device increases. Error control coding (ECC) can be used to reduce the RBER to acceptable values so that these devices can be employed to store information in applications where data corruption is unacceptable. In this paper, we describe the synthesis of BCH codes for flash memories based on multi level cell (MLC) concept. This is in continuation of our work on synthesis of BCH codes for improving the performance of flash memories based on single level cells (SLC). The improvement in device integrity resulting from the use of these codes has been quantified in this paper along with computation of parameters which allows modelling of flash memory as an equivalent channel. While synthesising codes, we have adhered to the limitations imposed by the memory architecture. Use of these codes in storage devices will result in considerable enhancement of device reliability and consequently open up many new applications for this class of storage devices. © 2012 Inderscience Enterprises Ltd.
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    Production of propyl gallate in nonaqueous medium using cell-associated tannase of Bacillus massiliensis: Effect of various parameters and statistical optimization
    (2013) Aithal, M.; Belur, P.D.
    Enzymatic synthesis of propyl gallate in an organic solvent was studied using cell-associated tannase (E.C. 3.1.1.20) of Bacillus massiliensis. Lyophilized biomass showing tannase activity was used as a biocatalyst. The influence of buffer pH and strength, water activity, temperature, biocatalyst loading, gallic acid concentration, and 1-propanol concentration was studied by the one-factor-at-a-time method. Subsequently, response surface methodology was applied based on a central composite design to determine the effects of three independent variables (biocatalyst loading, gallic acid concentration, and 1-propanol concentration) and their mutual interactions. A total of 20 experiments were conducted, and a statistical model was developed, which predicted the maximum propyl gallate yield of 20.28 ?g/mL in the reaction mixture comprising 40.4 mg biocatalyst, 0.4 mM gallic acid, and 6.52 % (v/v) 1-propanol in 9.5 mL benzene at 30°C. The subsequent verification experiments established the validity of the model. Under optimal conditions, 25% conversion of gallic acid to propyl gallate was achieved on a molar basis. The absence of the need for enzyme purification and subsequent immobilization steps and good conversion efficiency makes this enzyme system an interesting one. Reports on the applications of bacterial whole cell systems for synthetic reactions in organic solvents are scarce, and perhaps this is the first report on bacterial cell-associated tannase-mediated esterification in a nonaqueous medium. © 2013 International Union of Biochemistry and Molecular Biology, Inc.
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    Enhancing gallic acid content in green tea extract by using novel cell-associated tannase of Bacillus massiliensis
    (2013) Palabhanvi, B.; Belur, P.D.
    Gallic acid content in green tea extract was enhanced by using a novel cell-associated tannase of Bacillus massiliensis. Biomass that contains tannase was used for this study. The activity of the cell-associated tannase was stable during 1 week of storage in the refrigerator. Response surface methodology was applied based on central composite design to determine the effects of three independent variables (pH, temperature and incubation time) and their mutual interactions. A total of 16 experiments were conducted; and a statistical model was developed, which predicted 475.74mg/L gallic acid production at pH6.2, 36C and incubation period of 16.71h. The subsequent verification experiments confirmed the validity of the model. Under optimal conditions, 84.7% of the total hydrolyzable tannins were converted to gallic acid and glucose. This naturally immobilized tannase was stable enough to be used for up to 12 runs. Practical Applications: The current study shows that naturally immobilized tannase of Bacillus massiliensis can be used instead of artificially immobilized tannase. Such naturally immobilized tannase has many advantages as it avoids expensive and laborious isolation, purification and immobilization. Ease of separation of cell-associated enzyme from the reaction mixture and absence of any detectable extracellular tannase activity after enzymatic treatment are some of the encouraging facts. Stability during storage up to 7 days, 85% tannic acid hydrolyzing efficiency, activity at pH3.5-8.0 and operational stability for 12 runs are some of the interesting features of this naturally immobilized enzyme. However, its application for tea treatment will be limited until Bacillus massiliensis gets "Generally Recognized As Safe" status. It can be employed, however, for production of gallic acid from agro residues and production of propyl gallate. © 2012 Wiley Periodicals, Inc.
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    Differential delivery of vincristine to A549 cells using Chitosan capped silver nanoparticles under the pH trigger
    (American Scientific Publishers order@aspbs.com, 2017) Venkatramanan, V.; Arulvel, A.; Bose, R.; Arumugam, G.K.S.
    This study reports chitosan capped biogenically synthesized silver nanoparticles (Chit@AgNPs) of Diameter=12 nm for efficient delivery of vincristine (VCR) to A549 cells under the pH trigger. About 48% w/w of VCR could be loaded to Chit@AgNP without any conjugation system. The infrared spectroscopy indicated the presence of abundant quantities of the hydroxyl group on the surface of VCR loaded Chit@AgNP and it was confirmed by its negative zeta potential (-11.7 mV). Under in vitro condition, the release of VCR from Chit@AgNP into aqueous solution strictly followed first order kinetics with high preference to acidic pH. Significant cytotoxicity was observed in A549 cells than MDCK cells at p > 0-05 when incubated with VCR loaded Chit@AgNP, promoting high specificity towards cancer cells.
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    Investigation on cascade multilevel inverter with symmetric, asymmetric, hybrid and multi-cell configurations
    (Ain Shams University editor@eng.asu.edu.eg, 2017) Yellasiri, Y.; Venkataramanaiah, J.; Panda, A.K.; Dhanamjayulu, C.; Pakala, P.
    In recent past, numerous multilevel architectures came into existence. In this background, cascaded multilevel inverter (CMLI) is the promising structure. This type of multilevel inverters synthesizes a medium voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltage and current waveforms. However, when the number of levels increases switching components and the count of dc sources are also increased. This issue became a key motivation for the present paper. The present paper is devoted to investigate different types of CMLI which use less number of switching components and dc sources and finally proposed a new version of Multi-cell based CMLI. In order to verify the proposed topology, MATLAB – simulations and hardware verifications are carried out and results are presented. © 2016 Ain Shams University
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    A Zero Index Based Meta-Lens Loaded Wideband Directive Antenna Combined with Reactive Impedance Surface
    (Institute of Electrical and Electronics Engineers Inc., 2018) Majumder, B.; Kandasamy, K.; Ray, K.P.
    In this paper, an aperture efficient wideband high-gain patch antenna is designed using a novel multilayer-based metamaterial structure combined with a reactive impedance surface (RIS)-backed patch antenna. The metamaterial unit cell is a two-layer structure which is stacked one after other to form the overall unit cell. The microscopic behavior of the proposed unit cell has been investigated. This unit cell gives low refractive index over a wide bandwidth with a negligible loss. An RIS-backed patch antenna has been designed in the required frequency band to feed the multilayer zero-index metamaterial medium. The introduction of this surface is to provide unidirectional radiation over a wideband in the zero refractive index region. The proposed antenna gives a 14% fractional bandwidth over the $C$ - and $X$ -bands. The proposed antenna enhances the peak gain of the conventional patch antenna by an amount of 8.5 dB at 8 GHz. Finally, the antenna has been fabricated and its performance is verified experimentally. © 2013 IEEE.
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    Semiconducting B13C2 system: Structure search and DFT-based analysis
    (Institute of Physics, 2019) Pillai, H.G.; Madam, A.K.; Chandra, S.; Cheruvalath, V.M.
    DFT calculation on Boron Carbide in B13C2 stoichiometry using a 15-atom unit cell necessarily results in metallic ground state regardless of the crystal structure. This is because such a unit cell consists of odd number of electrons, and hence complete filling of the top most band(s) of nonzero occupancy is impossible. This is in contrast to the observed semiconducting nature. If the crystal structure of B13C2 is made of a 30-atom unit cell which cannot be reduced to a 15 atom cell, there is a possibility of obtaining either a metallic or a semiconducting state as such a cell consists of an even number of electrons. In this work the evolutionary algorithm based structure search using 30-atom unit cells has yielded a previously unreported semiconducting system of B13C2 with unique bonding pattern. The mechanical and dynamical stability of the system have been properly established through the computation of elastic constants and phonon spectra. Its bond lengths, elastic moduli, hardness and infrared spectrum are in good agreement with experimental data. ©2019 IOP Publishing Ltd.
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    A new hybrid key pre-distribution scheme for wireless sensor networks
    (Springer New York LLC barbara.b.bertram@gsk.com, 2019) Kumar, A.; Pais, A.R.
    This article presents a novel hybrid key pre-distribution scheme based on combinatorial design keys and pair-wise keys. For the presented scheme, the deployment zone is cleft into equal-sized cells. We use the combinatorial design based keys to secure intra-cell communication, which helps to maintain low key storage overhead in the network. For inter-cell communication, each cell maintain multiple associations with all the other cells within communication range and these associations are secured with pair-wise keys. This helps to ensure high resiliency against compromised sensor nodes in the network. We provide in-depth analysis for the presented scheme. We measure the resiliency of the presented scheme by calculating fraction of links effected and fraction of nodes disconnected when adversary compromises some sensor nodes in the network. We find that the presented scheme has high resiliency than majority of existing schemes. Our presented scheme also has low storage overhead than existing schemes. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
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    A new combinatorial design based key pre-distribution scheme for wireless sensor networks
    (Springer Verlag service@springer.de, 2019) Kumar, A.; Pais, A.R.
    In this paper we present a new Combinatorial Design based Key Pre-Distribution scheme (CD-KPD). For the scheme, the network region is divided into cells of equal size and each cell has two types of sensor nodes namely, normal sensor nodes and cluster heads. Within a particular cell, normal sensor nodes can communicate with each other directly and cluster heads are used for inter-cell communication. To ensure secure communication we use CD-KPD to assign keys to all the sensor nodes including cluster heads. We further modify CD-KPD to propose Combinatorial Design based Reduced Key Pre-Distribution scheme (CD-RKPD) by reducing the number of keys stored in each cluster head. The CD-RKPD was need of the hour when we consider to limit the inter-cell communication of each cell within its Lee sphere region. We give in-detail analysis of both the proposed schemes. We measure the resiliency of both proposed schemes by calculating fraction of links disrupted and fraction of cells disconnected when few sensor nodes are compromised in the network. We found that CD-KPD and CD-RKPD outperforms (Ruj and Roy in ACM Trans Sens Netw 6(1):4, 2009) by 59 and 6.5% respectively in terms of Global Resiliency and 5 and 9.7% respectively in terms of fraction of cell disconnected in the network. Further, we found that both our proposed schemes achieves high resiliency than majority of existing schemes. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.