Author
K. G. Padmalekha
Bio: K. G. Padmalekha is an academic researcher from Indian Institute of Science. The author has contributed to research in topics: Micromagnetics & Conductivity. The author has an hindex of 2, co-authored 4 publications receiving 141 citations.
Papers
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TL;DR: In this article, a highly homogeneous ZnO/Ag nanohybrid has been synthesized by a novel route, employing chitosan as mediator by purely electrostatic interaction.
Abstract: A highly homogeneous ZnO/Ag nanohybrid has been synthesized by a novel route, employing chitosan as mediator by purely electrostatic interaction. By employing various techniques such as powder XRD, UV-visible, IR spectroscopy and electron (SEM, TEM) microscopy, the formation of the nanohybrid has been established. The synergistic antibacterial effect of ZnO/Ag nanohybrid on Gram-positive and Gram-negative bacteria is found to be more effective, compared to the individual components (ZnO and Ag). Cytotoxicity experiments are carried out and the results are correlated to the solubility of the nanohybrid. A possible mechanism has been proposed for the antibacterial activity of ZnO/Ag nanohybrid, based on TEM studies on bacteria, carried out by employing the microtome technique and by EPR measurements on the hybrid.
157 citations
TL;DR: In this article, a grid was fabricated using e-beam lithography followed by DC-Magnetron sputtering and liftoff technique to understand the spin wave dynamics and the presence of two sets of magnetic nanowires perpendicular to each other in the same device enables better control over spin waves.
Abstract: We report ferromagnetic resonance (FMR) study on a grid formed with permalloy nanowires to understand the spin wave dynamics. The presence of two sets of magnetic nanowires perpendicular to each other in the same device enables better control over spin waves. The grid was fabricated using e-beam lithography followed by DC-Magnetron sputtering and liftoff technique. It has dimensions of 800 ± 10 and 400 ± 10 nm as periods along X and Y directions with permalloy wires of width 145 ± 10 nm. FMR studies were done at X-band (9.4 GHz) with the field sweep up to 1 Tesla. The in-plane angular variation of resonant fields shows that there are two well separated modes present, indicating two uniaxial anisotropy axes which are perpendicular to each other. The variation in the intensities in the FMR signal w.r.t. the grid angle is used to describe the spin wave confinement in different regions of the grid. We also explained the asymmetry in the magnetic properties caused by the geometrical property of the rectangular grid and the origin for the peak splitting for the modes occurring at higher resonant fields. Micromagnetic simulations based on OOMMF with two dimensional periodic boundary conditions (2D-PBC) are used to support our experimental findings.
3 citations
TL;DR: In this article, a contactless method to determine the electrical conductivity of nanoparticles is presented based on the lineshape analysis of electron magnetic resonance signals which are Dysonian for conducting samples of sizes larger than the skin depth.
2 citations
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TL;DR: In this article, an in-depth overview comprising traditional photocatalysis along with Z-scheme photocatalytic systems have been exploited and discussed with respect to their facile synthesis techniques and application in environmental restoration.
339 citations
TL;DR: In this paper, a worm-like Ag/ZnO core-shell heterostructural composites were fabricated using a two-step chemical method using as-prepared silver nanowires were soaked in a solution of zinc acetate and triethanolamine.
Abstract: Novel worm-like Ag/ZnO core–shell heterostructural composites were fabricated using a two-step chemical method. As-prepared silver nanowires were soaked in a solution of zinc acetate and triethanolamine to form worm-like Ag/ZnO core–shell composites under ultrasonic irradiation. Samples were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, and UV–vis spectrophotometer. The results show that the core–shell composites are composed of single-crystal Ag nanowires serving as the core, on which dense ZnO particles grow as the shell. The surface plasmon absorption band of Ag/ZnO composites is distinctly broadened and red shifted to monometallic Ag nanowires. The PL intensity of Ag/ZnO heterostructural composites varies and has the minimum intensity for the sample prepared with Ag of 2.8 atom %. Moreover, photocatalytic tests show that the Ag/ZnO composites ...
251 citations
TL;DR: This study focuses on synthesis of silver-zinc oxide (Ag-ZnO) nanocomposites which will have a broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria.
222 citations
TL;DR: In this paper, the synthesis of silver-zinc oxide (Ag-ZnO) nanostructures with a plant extract-mediated hydrothermal method was investigated, where the eco-friendly plant extract Azadirachta indica (Neem) was used as a reducing agent.
216 citations
TL;DR: Inspired by mussels, a mild and environmentally friendly method was used to synthesize Ag nanoparticles on functionalized PDA-graphene nanosheets (PDA-GNS) with uniform and high dispersion that exhibited strong antibacterial properties to both Gram-negative and Gram-positive bacteria due to the synergistic effect of GNS and Ag NPs.
Abstract: Mussels have been shown to attach to virtually all types of inorganic and organic surfaces via their adhesive proteins. The adhesive proteins secreted by mussels contain high concentrations of catechol and amine functional groups, which have similar functional groups with polydopamine (PDA). Inspired by mussels, a mild and environmentally friendly method was used to synthesize Ag nanoparticles (Ag NPs) on functionalized PDA-graphene nanosheets (PDA-GNS) with uniform and high dispersion. First, a uniform layer of PDA was coated on graphene oxide (GO) by polymerizing dopamine (DA) at room temperature. During the process GO was reduced by the DA. The PDA layer on the surface of GNS can be used as a nanoscale guide to form uniform Ag NPs on the surface of PDA-GNS. The obtained Ag-PDA-GNS hybrid materials are characterized by atomic force microscopy, transmission electron microscopy, UV-vis spectroscopy, Raman spectroscopy, X-ray photo-electron spectroscopy, X-ray diffraction, and thermal gravimetric analysis. The resultant Ag-PDA-GNS hybrid materials exhibited strong antibacterial properties to both Gram-negative and Gram-positive bacteria due to the synergistic effect of GNS and Ag NPs.
206 citations