Showing papers by "Kandasamy Prabakar published in 2016"

Occurrence of Antibiotic Resistance Genes and Bacterial Markers in a Tropical River Receiving Hospital and Urban Wastewaters

Abstract: The occurrence of emerging biological contaminants including antibiotic resistance genes (ARGs) and Faecal Indicator Bacteria (FIB) is still little investigated in developing countries under tropical conditions. In this study, the total bacterial load, the abundance of FIB (E. coli and Enterococcus spp. (ENT)), Pseudomonas spp. and ARGs (blaTEM, blaCTX-M, blaSHV, blaNDM and aadA) were quantified using quantitative PCR in the total DNA extracted from the sediments recovered from hospital outlet pipes (HOP) and the Cauvery River Basin (CRB), Tiruchirappalli, Tamil Nadu, India. The abundance of bacterial marker genes were 120, 104 and 89 fold higher for the E. coli, Enterococcus spp. and Pseudomonas spp., respectively at HOP when compared with CRB. The ARGs aadA and blaTEM were most frequently detected in higher concentration than other ARGs at all the sampling sites. The ARGs blaSHV and blaNDM were identified in CRB sediments contaminated by hospital and urban wastewaters. The ARGs abundance strongly correlated (r ≥ 0.36, p < 0.05, n = 45) with total bacterial load and E. coli in the sediments, indicating a common origin and extant source of contamination. Tropical aquatic ecosystems receiving wastewaters can act as reservoir of ARGs, which could potentially be transferred to susceptible bacterial pathogens at these sites.

Phase transition kinetics and surface binding states of methylammonium lead iodide perovskite.

Abstract: We have presented a detailed analysis of the phase transition kinetics and binding energy states of solution processed methylammonium lead iodide (MAPbI3) thin films prepared at ambient conditions and annealed at different elevated temperatures. It is the processing temperature and environmental conditions that predominantly control the crystal structure and surface morphology of MAPbI3 thin films. The structural transformation from tetragonal to cubic occurs at 60 °C with a 30 minute annealing time while the 10 minute annealed films posses a tetragonal crystal structure. The transformed phase is greatly intact even at the higher annealing temperature of 150 °C and after a time of 2 hours. The charge transfer interaction between the Pb 4f and I 3d oxidation states is quantified using XPS.

Flower-like ZnO@MnCo2O4 nanosheet structures on nickel foam as novel electrode material for high-performance supercapacitors

Abstract: Hierarchical flower-like ZnO@MnCo2O4 nanosheets and dandelion-like MnCo2O4 were synthesized on nickel foam using a facile and cost-effective hydrothermal approach combined with a short post-annealing treatment. The surface properties, crystalline phase, and electrochemical properties of the flower-like and dandelion-like electrodes were studied by field emission scanning electron microscopy, X-ray diffraction, cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy. The flower-like ZnO@MnCo2O4 nanosheet electrode exhibited high specific capacitance of 631.2 F g−1 and a high energy density of 56.10 W h kg−1 at a current density of 1 A g−1, which is higher than that of the dandelion-like MnCo2O4 electrode (452.5 F g−1). Impressively, as an electrode material for supercapacitors, the flower-like ZnO@MnCo2O4 also shows exceptional cycling performance over 1000 charge/discharge cycles, indicating good long-term cycling stability. These results highlight the unique ZnO@MnCo2O4 electrode as a promising electrode for energy storage applications in supercapacitors.

Simultaneous electrochemical deposition of an e-rGO/β-CD/MnO2 ternary composite for a self-powered supercapacitor based caffeine sensor

Abstract: A self-powered supercapacitor based on a caffeine sensor electrode has been developed using an electrochemically deposited rGO/β-CD/MnO2 ternary composite with ionic liquid assistance. This typical composite electrode was prepared from electrochemically reduced e-rGO followed by the addition of β-cyclodextrin and MnO2 from Mn(CH3COOH)2·4H2O on FTO surfaces. The composite material is indexed to the corresponding crystalline phase of MnO2 in the XRD investigation and Mn 3p, Mn 2p, C 1s, and O 1s signals were identified from XPS analysis. The cyclic voltammetry study reveals that the potential of the caffeine samples and the square wave voltammetry peak currents indicate an increasing trend for caffeine oxidation. The sensor expressed a sensitivity of 0.187 μA cm2 μM−1 with a linear range of 10–550 μM (n = 3.12). The corresponding supercapacitor also exhibited a specific capacitance of 352 F g−1 and it showed a very good life time from a long term cyclic test. The proposed ternary composite electrodes may be suitable electrodes for self-powered sensor devices.

Growth mechanisms and origin of localized surface plasmon resonance coupled exciton effects in Cu2−xS thin films

Abstract: We have demonstrated a robust protocol to prepare Cu2−xS thin films with a controlled crystal phase and size which exhibit localized surface plasmon resonance (LSPR) coupled exciton effects by a simple template free single step wet chemical method without any surfactant. The LSPR frequency can be tuned in the Cu2−xS thin films by the growth temperature and time which controls the free carrier density. These selectively grown Cu2−xS thin films possess a tunable band gap (2.6–1.4 eV) due to the quantum size effect. The origin of the LSPR coupled exciton effects are discussed.

Free vibration of layered cylindrical shells filled with fluid

Abstract: The vibration of the layered cylindrical shells filled with a quiescent, incompressible, and inviscid fluid is analyzed. The governing equations of the cylindrical shells are derived by Love’s approximation. The solutions of the displacement functions are assumed in a separable form to obtain a system of coupled differential equations in terms of the displacement functions. The displacement functions are approximated by Bickley-type splines. A generalized eigenvalue problem is obtained and solved numerically for the frequency parameter and an associated eigenvector of the spline coefficients. Two layered shells with three different types of materials under clamped-clamped (C-C) and simply supported (S-S) boundary conditions are considered. The variations of the frequency parameter with respect to the relative layer thickness, the length-to-radius ratio, the length-to-thickness ratio, and the circumferential node number are analyzed.

Phytochemical profiling of the aqueous leaf extracts of Blepharis maderaspatensis (L.) Heyne ex Roth its HPLC, GC-MS, and column chromatographic analysis

Abstract: Medicinal plants play an important role in treating various diseases in living organisms. A large number of the plants are suggested to possess the antibiotic properties in the traditional system and are also used ample by the tribal people worldwide. Photochemical have two categories i.e., primary and secondary constituents. Primary constituents have chlorophyll, proteins, sugar and amino acids. Secondary constituents contain terpenoids and alkaloids. Medicinal plants have antifungal, antibacterial and anti-inflammation activities. The plant for the present study is Blepharis maderaspatensis (L.) Heyne ex Roth. They belong to the family Acanthaceae. Phytochemical screening of the leaf extract was done to ascertain the phytochemical appurtenance in the versatile solvents of the leaf extract. The leaf of the selected medicinal plant was washed, air dried and then powdered. The aqueous extract of leaf sample was used for the phytochemical analysis to find out the phytochemical constituents in the plant. The main target of the research work was to reveal the presence or absence of the phytochemical appurtenance in the selected medicinal plant. The results of the phytochemical analysis of the leaf extract of medicinal plant revealed the presence of terpenoids, phlobatannins, reducing sugar, flavonoids, phenols, glycosides, starch, proteins, peptide, amino acids, tannins, anthroquinones, sterols, steroids, coumarins, quinines, saponins and alkaloids. Further analysis such as Column chromatography, HPLC and GC-MS of leaf methanol extract has revealed the presence of phenolic compounds which is a bioactive compound amenable to treat disease.