Browsing by Author "Kumar, K."

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A 0.5–5 Gb/s Wide Range, 160 fJ/Pulse Fully Integrated 13th-Order CMOS IR-UWB Transmitter for Wireless Capsule Endoscopy Systems
(John Wiley and Sons Ltd, 2025) Akuri, N.; Kumar, K.; Kumar, S.; Nikhil, K.S.; Song, H.
This paper proposes a novel technique based fully integrated 13th-order derivative CMOS impulse-radio ultrawideband (IR-UWB) transmitter with wide range of adaptive data rates for wireless capsule endoscopy systems (WCE). The proposed IR-UWB transmitter involves BPSK modulator-integrated RF power amplifier (PA) approach for WCE in first time as per author's best knowledge. The CMOS BPSK modulator with resonator technique generates 13th-order Modulated Gaussian pulse without the pulse generator. It has a peak-to-peak value of 25 mV and PSD level of ?72.60 dBm/MHz, data rate variability from 500 Mbps to 5 Gbps. The BPSK modulator with resonator is designed by time constant analysis in first time. In addition, a proposed CMOS PA is designed using four stacked transistors, which achieves a high output power as well as high efficiency for entire frequency band of operation from 3 to 16 GHz and wide impedance matching. The PA achieved an excellent gain of 16.55 dB with gain ripple of 0.25 dB only. Moreover, the PA achieved the saturated output power of 18.2 to 19.3 dBm with OP1dB of 15.96 to 16.72 dBm across entire bandwidth. Without violating FCC guidelines, PA strengths both peak-to-peak values, and PSD level of BPSK modulated signal to 80 mV and ?46.42 dBm/MHz. An IR-UWB transmitter has been implemented and fabricated using 65-nm CMOS Process, which consumes of only 160 fJ/pulse for generating Gaussian pulses order ranging from third-order to more than 13th-order at various data rates. © 2025 John Wiley & Sons Ltd.
A highly robust RF 65 nm CMOS power amplifier design using Quasi-Newton control algorithm for wireless system
(Elsevier B.V., 2023) Kumar, K.; Kumar, S.; Kumar Kanaujia, B.K.
This article reports a novel robust approach towards CMOS power amplifier (PA) using Quasi-newton (QN) control algorithm in 65 nm CMOS process which provides best performance parameters over redundant wide bandwidth ranging from 2.4 to 16.4 GHz frequency band. Each stage are designed and optimized using QN algorithm to get desired goals such as high linearity, small group delay variations and high PAE across the entire frequency band of interest. Moreover, pole-zeros compensation technique is adopted and derived to get better stability of the proposed PA. The simulation and measurement results of PA achieved a small signal power gain of 10.5–16.8 dB with input return loss of better than 10 dB over the frequency band of 2.4 GHz to 16.4 GHz. A small group delay variation of ±58 ps over full frequency band of operation is achieved by optimizing the design parametric analysis. It is also observed that within the frequency of 6.5 to 14.6 GHz, an excellent small group delay variation of only ±11 ps is achieved and this is due to stage-2 tuning compensation technique. It also demonstrates the achieved input power in 1 dB compression points are −3.1 to 4.3 dBm, leading to maximum power added efficiency of 36.3%, respectively. The proposed PA consumes a lower DC power of 20.5 mW under supply voltage of 1.5. In addition, Process, voltage and temperature (PVT) analysis is executed at different conditions in order to achieve a robustness of the proposed PA over the entire band of operation. © 2023 Elsevier B.V.
A L/S/C/X/Ku-Band Three-Stack, Two stages Fully Integrated CMOS Power Amplifier with 20.9 % PAE Using T-Network
(Institute of Electrical and Electronics Engineers Inc., 2023) Kumar, K.; Kumar, S.; Gupta, M.P.
This work proposes an L/S/C/X/Ku-Band three-stack two stages fully integrated CMOS power amplifier (PA) that realized in 65nm and achieves high efficiency, high output power over wide impedance bandwidth from 2-20 GHz. The proposed PA circuit comprises of T-network broadband input power match design, interstage tuning network and output power stage. The interstage tuning network is employed to achieve an excellent gain (|S21|) flatness of 16.3 Â± 0.9 dB. The proposed PA design is employed 3-stack of transistor under supply of 3V at stage-1 followed LC and stage-2 to achieve high output power. The load pull analysis is performed to optimize the T- type output matching network for achieving PAE of 20.9 % and output power of 15.97 dBm at 7 GHz with 50 Î© load impedance. Besides, this PA provides 1 dB output compression point of 11.2 Â± 0.8 dBm over full frequency band and also achieves the output third order intercept point of 23.2 dBm at 7 GHz using two tone signal. Â© 2023 IEEE.
A novel approach to enhance the combustion quality of C5 alcohol with 2-Ethylhexyl nitrate as a cetane enhancer in common rail direct ignition diesel engine
(Elsevier Ltd, 2024) Santhosh, S.; Kumar, K.; Bedar, P.
The purpose of this investigation is to explore the effect of 1-Pentanol and 2-Ethylhexyl nitrate (2-EHN), on the characteristics of a common rail direct injection (CRDI) diesel engine. The major feedstock for the production of 1-pentanol (bio-alcohol) is non food biomass waste. The conversion of waste biomass into useful energy contributes to the cleaner production of fuel and its utilization. The trial was conducted in a 2-cylinder CRDI test rig. The engine was fuelled with diesel, 40P60D (40% 1-Pentanol & 60% diesel v/v) and then 500, 1000 and 2000 ppm of 2-EHN was doped to 40P60D. The addition of 1-Pentnaol showed a slight negative effect on combustion at low and medium loads. Furthermore, an extension in the delay period (DP) and combustion duration (CD) was seen for 1-Pentanol blend. The doping of 2-EHN, enhances the cetane count and leads to improvement in the combustion parameters and a reduction in DP and CD was noted. The 1000 ppm of 2-EHN doped blend showed 8.7% of higher BTE and 8.61% lower BSEC compared to 40P60D, also 1.89% and 50% lower HC and CO at 80% load and 36.9% lower NO at 60% load in contrast to diesel. Among all the concentrations 1000 ppm of 2-EHN showed satisfactory results. It is concluded that 40% of 1-Pentanol with 1000 ppm of 2-EHN can be used as an alternative fuel to pure diesel without compromising in performance of the engine. © 2024 Elsevier Ltd
A Novel Enzymatic Process to Produce Oxalate Depleted Starch From Taro
(Wiley-VCH Verlag info@wiley-vch.de, 2018) Kumar, K.; Belur, P.D.
A novel process comprising treatment of Taro (Colocasia esculenta (L.) Schott) tuber flour with oxalate oxidase enzyme is developed to deplete the oxalate content. Oxalate oxidase enzyme produced by an endophyte, Ochrobactrum intermedium CL6 is employed to treat taro tuber flour. The treatment followed by extraction of starch results in a 97% reduction in total oxalate content. Further, several physicochemical properties such as paste clarity, swelling power, solubility, amylose content, granule size of starch produced out of enzyme treatment are studied and compared with properties of taro starch produced without enzyme treatment. The study reveals that enzyme treatment does not bring appreciable changes in the studied parameters. The taro starch produced by enzyme treatment shows very low paste clarity (9.38%), high swelling power (15.32 g/g), very low solubility (21.66%), and low amylose content (7.52%) at 100 °C compared to potato and sweet-potato starches. X-ray diffraction data reveal that taro starch possesses an A-crystalline form, unlike the B-crystalline form found in potato and sweet potato starch. To the best of the authors knowledge, for the first time, the use of oxalate oxidase to produce oxalate depleted taro starch is reported. One of the interesting food industry applications of oxalate-depleted taro starch, among many other uses could be for baby food formulation because of its small granule size. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
A semantic search engine for answering domain specific user queries
(2013) Kamath Sâ€¤, S.S.; Piraviperumal, D.; Meena, G.; Karkidholi, S.; Kumar, K.
With the exponential growth in web content and due to its sheer volume, the answers provided by traditional search engines by query specific keywords to content has resulted in markedly high recall and low precision. In order to alleviate this problem, the notion of incorporating semantics in content and in Search Engines, i.e., a Semantic Search Engine is increasingly crucial. Several Semantic Search Engines (SSEs) have been proposed and deployed till date and each is inherently different from the other. As such, the objective of this paper is to present a discussion on semantically enhanced search engines for intelligent web content discovery. We also present the architecture of a new SSE based on a bottom up approach that focuses on building a semantic base for Web content first and then carry out the process of querying it for attaining high precision and lower recall. Â© 2013 IEEE.
A study of influence of material properties on magnetic flux density induced in magneto rheological damper through finite element analysis
(EDP Sciences edps@edpsciences.com, 2018) Gurubasavaraju, T.M.; Kumar, K.; Arun, M.
Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force) is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dependent on materials properties of components of MR damper (such as piston head, outer cylinder and piston rod). The present paper discus about the influence of different materials selected for components of the MR damper on magnetic effect using magnetostatic analysis. Different materials such as magnetic and low carbon steels are considered for piston head of the MR damper and magnetic flux density induced at fluid flow gap (filled with MR fluid) is computed for different DC current applied to the electromagnetic coil. Developed magnetic flux is used for calculating the damper force using analytical method for each case. The low carbon steel has higher magnetic permeability hence maximum magnetic flux could pass through the piston head, which leads to higher value of magnetic effect induction at the annular gap. From the analysis results it is observed that the magnetic steel and low carbon steel piston head provided maximum magnetic flux density. Eventually the higher damping force can be observed for same case. Â© The Authors, published by EDP Sciences, 2018.
Advertisement detection in commercial radio channels
(2016) Koolagudi, S.G.; Sridhar, S.; Elango, N.; Kumar, K.; Afroz, F.
In this paper, real time identification of advertisement segments in a radio broadcast is performed. There are certain distinctive characteristics of advertisements that distinguish from the rest of the broadcasting information, Speech technology related to recognition of specific patterns in speech signal can characterize this distinction. Machine learning tools such as Hidden Markov Models, Artificial Neural Networks and Ensemble Method are used to classify advertisement and non-advertisement patterns. An ensemble classification technique gave a better classification performance. The system was created using blind audio segmentation for optimization of real time analysis. This work is done mainly using audio characteristics and can be extended to visual data. � 2015 IEEE.
Advertisement detection in commercial radio channels
(Institute of Electrical and Electronics Engineers Inc., 2016) Koolagudi, S.G.; Sridhar, S.; Elango, N.; Kumar, K.; Afroz, F.
In this paper, real time identification of advertisement segments in a radio broadcast is performed. There are certain distinctive characteristics of advertisements that distinguish from the rest of the broadcasting information, Speech technology related to recognition of specific patterns in speech signal can characterize this distinction. Machine learning tools such as Hidden Markov Models, Artificial Neural Networks and Ensemble Method are used to classify advertisement and non-advertisement patterns. An ensemble classification technique gave a better classification performance. The system was created using blind audio segmentation for optimization of real time analysis. This work is done mainly using audio characteristics and can be extended to visual data. Â© 2015 IEEE.
Analytical modelling of ultra-small group delay variation of ultra-broadband RF power amplifier using NSGA-II algorithm
(John Wiley and Sons Ltd, 2024) Kumar, K.; Kumar, S.; Kumar Kanaujia, B.K.
This paper proposes a ± 9.4 ps ultra-small group delay (GD) variation of fully integrated 65 nm complementary metal oxide semiconductor (CMOS) power amplifier (PA) over 6.5–17 GHz broadband for wireless application. The proposed CMOS PA is realised by using broadband stage, RLC inter-stage and power stage topologies. The non-dominated sorting genetic algorithm (NSGA-II) is employed for PA parameter optimisation to ensure a small GD variation of ±9.4 ps over broadband with an excellent small signal gain flatness of 23.65 ± 1.85 for 6.5–17 GHz. The small GD variation of ±9.4 ps and ± 11.05 ps are attained under two cases of DC supply voltages of 2.4/1.2 V and 1.2/1.2 V, respectively. To the best of author's knowledge, the achieved GD variations are lowest among all CMOS PAs as reported so far. In addition, an analytical modelling of GD is derived to validating the minimum GD variation using zero-pole compensation. With supply voltages of 2.4/1.2 V at 6.5 GHz, the large signal power gain, Psat and OP1dB are 26 dB, 19.3 dBm and 17.94 dBm, respectively, while peak power added efficiency (PAE) is 38.196%. At reduced supply voltages of 1.2/1.2 V, the PA achieves maximum power gain of 17.7 dB and peak PAE of 35% at 6.5 GHz. The CMOS PA occupies an area of 0.206 mm2. © 2023 John Wiley & Sons Ltd.
Compositionally modulated multilayer Cu-Zn alloy coatings fabricated using eco-friendly non-cyanide pulse electrochemical deposition
(Elsevier Ltd, 2023) Bharadishettar, N.; Kumar, K.; Udaya Bhat, K.
Pulse electrodeposition of Cu-Zn compositional modulated multilayer alloy (CMA) coatings was carried out onto AISI 304 stainless steel substrate using an environmentally friendly alkaline non-cyanide electrolytic bath. Cu-Zn alloy multilayer coating was co-electrodeposited using a trapezoidal pulse current. Multilayer coatings can have two different metals in layers or two-phase mixtures. Different sets of multilayers of 10, 20, 50, and 100 were done using a trapezoidal pulse current. In the trapezoidal pulse current module, during the higher current stage (0.1 A) Zn was deposited as compared to the lower current module (0.02 A) where Cu was deposited. Microstructural and structural analysis of the coatings confirmed nanocrystalline morphology with peaks corresponding to crystallographic planes of (002), (111), (020), and (022). Deposited coatings are hydrophilic in nature. The microhardness of the coatings is decreased with an increase in the number of layers deposited. Â© Â© 2023 Elsevier Ltd. All rights reserved.
Enhanced Power Density of Graphene Oxide–Phosphotetradecavanadate Nanohybrid for Supercapacitor Electrode
(Springer, 2021) Maity, S.; Anandan Vannathan, A.A.; Kumar, K.; Das, P.P.; Mal, S.S.
Successful exploration of supercapacitor (SC) material to integrate with high energy and high power density storage device still remains a daunting challenge. Conducting carbon nanostructures have been primarily used for this purpose; however, most of their surface area remains unutilized throughout the storage process. Herein, a new type of hybrid material has been reported by effectively using active sides of carbon nanostructures. Insertion of faradaic-type polyoxometalates (POMs), namely phosphotetradecavanadate (Na7[H2PV14O42], hereafter described as PV14), into the graphene oxide (GO) matrix creates a novel hybrid material for SC applications. Owing to the formation of nanohybrid, it can store charges both electrostatically and electrochemically. PV14/GO composite’s electrochemical behavior in different electrolyte (acidic/neutral) solutions shows different types of characteristics. The PV14/GO composite as a working electrode exhibits a high galvanostatic capacitance of 139 F/g while maintaining at a power density of 97.94 W/kg in 0.25 M H2SO4 electrolyte. The specific energy density was also found out to be around 56.58 Wh/kg at a 5 mV/s scan rate for the same electrolyte. Furthermore, in 1 M Na2SO4 solution, PV14/GO composite demonstrates a specific capacitance of 85.4 F/g at a scan rate of 5 mV/s. The equivalent series resistance for the device was found to be approximately 0.51 ? with a circuit resistance of 3.881 ?, using electrochemical impedance spectroscopy. The cell capacitance, employing the Nyquist plot, was calculated to be around 2.78 mF. © 2021, ASM International.
Face Detection and Recognition Using OpenCV and Vision Transformer
(Institute of Electrical and Electronics Engineers Inc., 2023) Kumar, K.; Pingale, N.; Rudra, B.
Face recognition technology is vital in the real world with diverse applications. It is primarily used for security, law enforcement, personalization, healthcare, and education. Face recognition systems use biometric features like facial landmarks, texture, and shape to identify and verify individuals. The suggested approach employs a transformer-based architecture that solely relies on self-attention and does not utilize Convolutional Layers. This design choice enables the model to be trained efficiently with minimal computational power and fewer parameters than a CNN. The application of Vision Transformer (ViT) in various computer vision tasks has been highly successful, making it a state-of-the-art approach. Given its superior performance, we are interested in exploring whether ViT can enhance the accuracy of sheep face recognition.In this paper, we show that ViT can be a useful technique for facial recognition. Since there was no predefined dataset for face recognition, a PCI dataset was built for this investigation. Along with the PCI dataset, two more well-known datasets, AT&T and 5-Celebrity, we used to examine performance. In our model was seen that ViT could identify human faces on the PCI dataset with a 99% accuracy rate and perform much better than other face recognition algorithms like Eigenface, FisherFace, and LBPH. Â© 2023 IEEE.
Fault Diagnosis of Face Milling Tool using Decision Tree and Sound Signal
(Elsevier Ltd, 2018) Madhusudana, C.K.; Kumar, K.; Narendranath, S.
The monitoring of machining process can improve the quality of product and economy of production. The monitoring system helps to recognize and monitor the surface roughness, dimensional tolerance and tool condition. In this way, the condition monitoring system provides precise dimensional products, high productivity and enhanced machine tool life. This paper presents the classification of healthy and faulty conditions of the face milling tool using Decision tree (J48 algorithm) technique through machine learning approach. The sound signals of the face milling tool under healthy and faulty conditions are acquired. A set of discrete wavelet features are extracted from the sound signals using discrete wavelet transform (DWT) method. Decision tree technique is used to select prominent features out of all extracted features. The selected features are fed to the same algorithm for classification. Output of the algorithm is used to study and categorize the tool conditions. The decision tree model has provided a good classification accuracy of about 81% for the given sound signals and can be considered for fault diagnosis/condition monitoring. From the experimental results, it is suggested that the proposed method which comprises of decision tree and DWT techniques with sound signals can be recommended for the applications of fault diagnosis of the face milling tool. Â© 2017 Elsevier Ltd. All rights reserved.
High Gain Ultra-Low NF Wideband CMOS Low Noise Amplifier Design Using 2-Stage Series-Parallel LC Matching Network
(Institute of Electrical and Electronics Engineers Inc., 2023) Sudhanva, P.V.C.S.; Yugandhar, B.; Kumar, S.; Kumar, K.; Bhat, K.G.
The focus of this work is the development of a sub-6 GHz (2-6 GHz) low noise amplifier (LNA) for 5G applications, using a 65 nm CMOS process. A novel two stage common source (CS) cascode source degeneration LNA topology by incorporating a contemporary series parallel LC network and two stage LC network for input and output matching respectively is proposed. The circuit implementation, simulations and evaluation of the LNA's performance are done utilizing the RF Spectre Cadence Virtuoso. According to the evaluation results, the LNA dissipates a total power of 19.6 mW at the supply voltage of 0.7 V. It offers an operational wide bandwidth (BW) of 3.2 GHz which ranges from 2.8 GHz to 6 GHz. The LNA has a peak gain of 36 dB and minimum noise figure (NF) of 1.1 dB across the sub-6 GHz spectrum. The proposed LNA also performs well in terms of stability and linearity measures. The layout of the proposed LNA occupies an area of 0.182mm2 Â© 2023 IEEE.
Influence of water-methanol injection and turbocharging on the performance of a hydrogen-fueled spark ignition engine
(John Wiley and Sons Inc, 2024) Chitragar, P.R.; Shivaprasad, K.V.; Ichchangi, M.; Ravi, R.; Yadav, M.S.; Kumar, K.
This article presents a study that compares the performance and emission characteristics of a four-stroke, four-cylinder spark ignition (SI) engine fueled by gasoline and neat hydrogen. The engine was equipped with turbocharging to optimize ignition timing for power boosting and vaporized water–methanol injection to reduce emissions. Engine tests were conducted at speeds ranging from 2000 to 6000 rpm, with a fixed intake pressure and varying quantities of hydrogen and spark advance timings. The study compared the results of non-turbocharged and turbocharged engines with water–methanol injection in terms of combustion, performance, and emissions. The findings showed that the turbocharged water–methanol hydrogen operation had a higher brake thermal efficiency (BTE) than its counterpart, while the brake power of the hydrogen engine operation increased with turbocharging but slightly decreased with water–methanol injection. Additionally, volumetric efficiency improved by 7% for turbocharged and 4% for water-injected hydrogen engine operation compared to the counterpart. The cylinder pressure for turbocharging with water–methanol operation yielded 16.32% higher compared with counterpart gasoline engine operation. Finally, nitrogen oxides (NOx) emissions were reduced with turbocharging and water–methanol injection compared to the counterpart non-turbocharged hydrogen engine operation. © 2023 Wiley Periodicals LLC.
Molecular surface-dependent light harvesting and photo charge separation in plant-derived carbon quantum dots for visible-light-driven OH radical generation for remediation of aromatic hydrocarbon pollutants and real wastewater
(Academic Press Inc., 2024) Meena, S.; Sethi, M.; Saini, S.; Kumar, K.; Saini, P.; Meena, S.; Kashyap, S.; Yadav, M.; Meena, M.L.; Dandia, A.; Nirmal, N.K.; Parewa, V.
Despite the growing emphasis on eco-friendly nanomaterials as energy harvesters, scientists are actively searching for metal-free photocatalysts to be used in environmental remediation strategies. Developing renewable resource-based carbon quantum dots (CQDs) as the sole photocatalyst to harvest visible light for efficient pollutant degradation is crucial yet challenging, particularly for addressing the escalating issue of water deterioration. Moreover, the photocatalytic decomposition of H2O2 under visible light irradiation remains an arduous task. Based on this, we designed two types of CQDs, C-CQDs (carboxylic-rich) and A-CQDs (amine-rich) with distinct molecular surfaces. Owing to the higher amount of upward band bending induced by amine-rich molecular surface, A-CQDs efficiently harvest the visible light and prevent recombination kinetics resulting in prolonged lifetimes (25 ps), and augmented charge carrier density (35.7 × 1018) of photoexcited charge carriers. A-CQDs enabled rapid visible-light-driven photolysis of H2O2 (k = 0.058 min−1) and produced higher quantity of •OH radicals (0.158 μmol/sec) for the mineralization of petroleum waste, BETX (i.e. Benzene, Ethylbenzene, Toluene and Xylene) (k = 0.017–0.026 min−1) and real textile wastewater (k = 0.026 min−1). To assess comparative toxicities of both remediated and non-remediated real wastewater samples in a time and dose depended manner, Drosophila melanogaster was used as a model organism. The findings unequivocally demonstrate the potential of remediated wastewater for watering urban forestry. © 2024 Elsevier Inc.
New extracellular thermostable oxalate oxidase produced from endophytic Ochrobactrum intermedium CL6: Purification and biochemical characterization
(2016) Kumar, K.; Belur, P.D.
Oxalate oxidase (EC 1.2.3.4) catalyzes the oxidative cleavage of oxalate to carbon dioxide with the reduction of molecular oxygen to hydrogen peroxide. Oxalate oxidase found its application in clinical assay for oxalate in blood and urine. This study describes the purification and biochemical characterization of an oxalate oxidase produced from an endophytic bacterium, Ochrobactrum intermedium CL6. The cell-free fermentation broth was subjected to two-step enzyme purification, which resulted in a 58.74-fold purification with 83% recovery. Specific activity of the final purified enzyme was 26.78 U mg?1 protein. The enzyme displayed an optimum pH and temperature of 3.8 and 80 C, respectively, and high stability at 4 80 C for 6 h. The enzymatic activity was not influenced by metal ions and chemical agents (K+, Na+, Zn2+, Fe3+, Mn2+, Mg2+, glucose, urea, lactate) commonly found in serum and urine, with Cu2+ being the exception. The enzyme appears to be a metalloprotein stimulated by Ca2+ and Fe2+. Its Km and Kcat for oxalate were found to be 0.45 mM and 85 s?1, respectively. This enzyme is the only known oxalate oxidase which did not show substrate inhibition up to a substrate concentration of 50 mM. Thermostability, kinetic properties, and the absence of substrate inhibition make this enzyme an ideal candidate for clinical applications. 2016, Copyright Taylor & Francis Group, LLC.
New extracellular thermostable oxalate oxidase produced from endophytic Ochrobactrum intermedium CL6: Purification and biochemical characterization
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Kumar, K.; Belur, P.D.
Oxalate oxidase (EC 1.2.3.4) catalyzes the oxidative cleavage of oxalate to carbon dioxide with the reduction of molecular oxygen to hydrogen peroxide. Oxalate oxidase found its application in clinical assay for oxalate in blood and urine. This study describes the purification and biochemical characterization of an oxalate oxidase produced from an endophytic bacterium, Ochrobactrum intermedium CL6. The cell-free fermentation broth was subjected to two-step enzyme purification, which resulted in a 58.74-fold purification with 83% recovery. Specific activity of the final purified enzyme was 26.78 U mg?1 protein. The enzyme displayed an optimum pH and temperature of 3.8 and 80°C, respectively, and high stability at 4–80°C for 6 h. The enzymatic activity was not influenced by metal ions and chemical agents (K+, Na+, Zn2+, Fe3+, Mn2+, Mg2+, glucose, urea, lactate) commonly found in serum and urine, with Cu2+ being the exception. The enzyme appears to be a metalloprotein stimulated by Ca2+ and Fe2+. Its Km and Kcat for oxalate were found to be 0.45 mM and 85 s?1, respectively. This enzyme is the only known oxalate oxidase which did not show substrate inhibition up to a substrate concentration of 50 mM. Thermostability, kinetic properties, and the absence of substrate inhibition make this enzyme an ideal candidate for clinical applications. © 2016, Copyright © Taylor & Francis Group, LLC.
A Novel Enzymatic Process to Produce Oxalate Depleted Starch From Taro
(2018) Kumar, K.; Belur, P.D.
A novel process comprising treatment of Taro (Colocasia esculenta (L.) Schott) tuber flour with oxalate oxidase enzyme is developed to deplete the oxalate content. Oxalate oxidase enzyme produced by an endophyte, Ochrobactrum intermedium CL6 is employed to treat taro tuber flour. The treatment followed by extraction of starch results in a 97% reduction in total oxalate content. Further, several physicochemical properties such as paste clarity, swelling power, solubility, amylose content, granule size of starch produced out of enzyme treatment are studied and compared with properties of taro starch produced without enzyme treatment. The study reveals that enzyme treatment does not bring appreciable changes in the studied parameters. The taro starch produced by enzyme treatment shows very low paste clarity (9.38%), high swelling power (15.32 g/g), very low solubility (21.66%), and low amylose content (7.52%) at 100 C compared to potato and sweet-potato starches. X-ray diffraction data reveal that taro starch possesses an A-crystalline form, unlike the B-crystalline form found in potato and sweet potato starch. To the best of the authors knowledge, for the first time, the use of oxalate oxidase to produce oxalate depleted taro starch is reported. One of the interesting food industry applications of oxalate-depleted taro starch, among many other uses could be for baby food formulation because of its small granule size. 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim