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45 results on '"Shankar, Prabakaran"'

23. Surface Sensitivity of Ultrasonically Treated Carbon Nanotube Network towards Ammonia

Author

Lutsyk, Petro, Shankar, Prabakaran, Rozhin, Oleksiy, Kulinich, Sergei A., Lutsyk, Petro, Shankar, Prabakaran, Rozhin, Oleksiy, and Kulinich, Sergei A.

Abstract

Detection of ammonia by carbon nanotubes is an extensively studied area where tremendous progress was achieved so far in their sensing performance. In this paper, we focused on carbon nanotube network sensors of NH 3 aiming to develop better understanding of their gas detection behavior and improved sensing response. Our experiments showed improved sensing performance for single-walled carbon nanotubes of (6,5) chirality ultrasonically treated at high power and then forming bundled nanotube network upon thermal annealing. Two chemiresistive sensing pathways were observed for such networks resulting in increased and decreased resistance in presence of different ammonia concentrations from 10 2 to 10 4 ppm. This multidirectional chemiresistive response was comprehensively explained via various phenomena, such as partial and full neutralization of p-type conductivity of the nanotubes, change of the Schottky barrier, and dipoles at the interface between nanotubes and gold electrodes. The proposed sensing mechanisms are believed to provide strong support for further development of ammonia sensors with optimized performance.

Published
2019

26. Fluorine doped ZnO thin film as acetaldehyde sensor

Author

Gunasekaran, Ezhilarasan, primary, Ezhilan, Madeshwari, additional, Mani, Ganesh Kumar, additional, Shankar, Prabakaran, additional, Kulandaisamy, Arockia Jayalatha, additional, Rayappan, John Bosco Balaguru, additional, and Babu, K Jayanth, additional

Published
2018
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30. Electrocoagulants Characteristics and Application of Electrocoagulation for Micropollutant Removal and Transformation Mechanism

Author

Govindan, Kadarkarai, Angelin, Arumugam, Kalpana, Murugesan, Rangarajan, Murali, Shankar, Prabakaran, and Jang, Am

Abstract

Predominantly, the removal of dissolved contaminates via the Fe electrocoagulation (EC) process depends on the electrocoagulants stability, specific area, porosity, dissolution rate, and phase transformation kinetics. The present investigation elucidates the role of applied currents and electrolyte counteranions on the crystalline phase and surface topography of electrocoagulants generated from Fe EC. Moreover, the dissolved contaminant micropollutant removal efficiency was also evaluated by electrochemically produced coagulants. This study confirms that mixed-phase iron (oxyhydr) oxide nanostructures were consistently produced from Fe EC with predominant formation of the goethite phase. The applied current controls the morphology of the coagulants, with flake-like morphology observed with currents at and below 100 mA and spherical morphology observed with currents above 100 mA. The counteranions in the electrolyte also impacted the morphology with spherical, nanosheet, and nanorod morphologies produced by Cl−or SO42–, CO32–, and HCO3–counteranions, respectively. BET analysis revealed the formation of electrocoagulants with micro-, meso-, and macropores. Surface area was markedly reduced from 142.85 to 41.96 m2g–1by incident coagulation resulting from increased anodic dissolution. Applicability of the electrocoagulant was examined by different micropollutants (acetaminophen (AC), antipyrine (AT), and atenolol (AT)). Results suggest that >90% and >80% TOC reduction were achieved with Na2CO3and NaHCO3as electrolyte media. The lower TOC reduction was rationalized by the identified intermediate products, and possible micropollutant degradation pathways were proposed based on LC-MS/MS analysis.

Published
2020
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37. Non-enzymatic detection of glucose in fruits using TiO2-Mn3O4 hybrid nano interface.

Author

Jayanth Babu, K., Sasya, Madhurantakam, Nesakumar, Noel, Shankar, Prabakaran, Bhargavi Gumpu, Manju, Lakshmishri Ramachandra, Bhat, Jayalatha Kulandaisamy, Arockia, and Balaguru Rayappan, John Bosco

Subjects
BLOOD sugar, FRUIT, PEOPLE with diabetes, DIABETES complications, CHITOSAN
Abstract

Consumption of fruits leads to increase in glucose level in blood for diabetic patients, which in turn leads to peripheral, vascular, ocular complications and cardiac diseases. In this context, a non-enzymatic hybrid glucose biosensor was fabricated for the first time to detect glucose by immobilizing titanium oxide–manganese oxide (TiO2-Mn3O4) nanocomposite and chitosan membrane on to the surface of Pt working electrode (Pt/TiO2-Mn3O4chitosan). TiO2-Mn3O4 nanocomposite catalyzed the oxidation of glucose to gluconolactone in the absence of glucose oxidase enzyme with high electron transfer rate, good biocompatibility and large surface coverage. Electrochemical measurements revealed the excellent sensing response of the developed biosensor towards glucose with a high sensitivity of 7.073 μA mM-1, linearity of 0.01-0.1 mM, low detection limit of 0.01μM, reproducibility of 1.5% and stability of 98.8%. The electrochemical parameters estimated from the anodic process were subjected to linear regression models for the detection of unknown concentration of glucose in different fruit samples. [ABSTRACT FROM AUTHOR]

Published
2017
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44. Racetrack Effect on the Dissimilar Sensing Response of ZnO Thin FilmAn Anisotropy of Isotropy

Author

Shankar, Prabakaran and Rayappan, John Bosco Balaguru

Abstract

The isotropic nature of the sensing elements decides the overall sensing performance of metal oxide gas/chemical sensors. Even a minimum deviation in the morphological and electrical characteristics of the sensing surface will lead to a nonuniform sensing performance, which in turn results in undesired figure of merits. With this background, the inhomogeneity of plasma discharge due to the racetrack effect of the magnetic field orbit in the planar magnetron and its significant influence on the formation of nanostructured ZnO thin films with desired uniformity has been investigated. The effect of the intensity of plasma discharges on the structural studies was a change in crystallite size from 11 to 35 nm. Anisotropic characteristics of the film influenced the mobility of carriers (10 and 220 cm2V–1s–1) by populating the carrier concentration (2.13 × 1011and 3.87 × 107cm–2) in the nanostructures. Furthermore, the influence of this anisotropic surface of the obtained film on the room-temperature ethanol-sensing behavior is reported. The first observation of the racetrack effect on the sensing gradient of the sputter-deposited ZnO thin film has brought out the challenge in preparing an isotropic sensing element without anisotropy.

Published
2016
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45. The Effect of ζ‐Potential and Hydrodynamic Size on Nanoparticle Interactions in Hydrogels.

Author

Kim, Si Hyun, Lee, Byoungsang, Heo, Jun Hyuk, Lee, Kyung Eun, Shankar, Prabakaran, Han, Kwon‐Hoon, and Lee, Jung Heon

Subjects
HYDRODYNAMICS, NANOPARTICLES, HYDROGELS, POTENTIAL theory (Physics), CAPPING proteins
Abstract

The ζ‐potential and hydrodynamic size (dh) of nanoparticles (NPs) are systematically controlled by capping gold NPs (AuNPs) with polymers having different charges and treating them in NaCl solutions of diverse concentrations. Interactions between AuNPs in hydrogel are caused by chemical reactions induced by 1,4‐dithiothreitol. The effect of ζ‐potential is clear, as negatively charged AuNPs can be aggregated in neutral agarose gel, but the amount of aggregation is significantly affected by the magnitude of the negative surface charge on the AuNPs. However, all positively charged AuNPs show negligible aggregation in agarose gel with slightly negative polarity. The effect of dh on AuNP aggregation is different from that of ζ‐potential. Although AuNPs with small dh generally show more aggregation than those with large dh, the amount of AuNP capping layer is critical. Thus, the amount of polymer present on NP surface needs to be considered to investigate the effect of dh on AuNP aggregation. Through extended Derjaguin, Landau, Verwey, Overbeek (XDLVO) theory, it is shown that the charges of the AuNPs and the hydrogel, as well as the dh of the NPs, are related to electrostatic repulsion and steric hindrance, which affect AuNP aggregation in hydrogel. Chemical interaction of nanoparticles in hydrogel is significantly affected by their ζ‐potential and hydrodynamic size. The charges of nanoparticles and the hydrogel and the hydrodynamic size of the nanoparticles affect the interaction of nanoparticles in hydrogel via electrostatic repulsion and steric hindrance occurring between them. [ABSTRACT FROM AUTHOR]

Published
2019
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