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Ratnadurai R.,University of South Florida | Niemann M.U.,University of South Florida | Phani A.R.,Nano Research for Advanced Materials and Technologies | Goswami D.Y.,University of South Florida | Stefanakos E.K.,University of South Florida
International Journal of Hydrogen Energy | Year: 2010

Due to its many physisorption sites as well as chemisorption sites, polyaniline (PANI) has been investigated for hydrogen storage purposes. The PANI was produced in house via traditional chemical synthesis methods and then electrospun to produce fibers. These PANI fibers were investigated and compared with standard bulk PANI and found to be stable up to 150 °C. When investigating PANI fibers, using PCT measurements, it was found that a reversible hydrogen storage capacity of ∼3-10 wt.% could be obtained at different temperatures. Hydrogen kinetic sorption measurements in prolonged cycles (up to 66 cycles) reveal an uptake and release of >6-10 wt.% on these PANI materials. The importance of the type of measurement is discussed as to its effect on the morphology and structure of the PANI nanofibers. The surface morphologies before and after hydrogen sorption on these PANI fibers encompass significant changes in the microstructure (nanofibrallar swelling effect). Detailed chemical and physical characterization of the PANI fibers is reported as part of this work. © 2009 Professor T. Nejat Veziroglu. Source


Rakesh Kumar R.,Indian Institute of Science | Narasimha Rao K.,Indian Institute of Science | Rajanna K.,Indian Institute of Science | Phani A.R.,Nano Research for Advanced Materials and Technologies
Advanced Materials Letters | Year: 2013

Silicon nanowires were grown on tin (Sn) coated Si substrates using electron beam evaporation technique at a growth temperature of 350°C. The as grown Si nanowires were characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscopy attached with Energy Dispersive X-Ray Analyser (TEM-EDX) for their morphological, structural, and compositional properties, respectively. The grown Si nanowires were randomly oriented on the substrate with a length of ~ 500 nm for a deposition time of 15 min. Silicon nanowires have shown tin nanoparticle (capped) on top of it confirming the Vapor-Liquid-Solid (VLS) growth mechanism responsible for Si nanowires growth. The nanowire growth rate was measured to be ~30 nm/min. Transmission Electron Microscope (TEM) measurements have revealed single crystalline nature of Si nanowires. The obtained results have indicated good progress towards finding alternative catalyst to gold for the synthesis of Si nanowires. © 2013 VBRI press. Source


Sahoo S.,Plnayak Research Foundation | Sasmal A.,Plnayak Research Foundation | Nanda R.,Plnayak Research Foundation | Phani A.R.,Nano Research for Advanced Materials and Technologies | Nayak P.L.,Plnayak Research Foundation
Carbohydrate Polymers | Year: 2010

In the present research work chitosan has been blended with different amounts of polycaprolactone (PCL) (80:20, 75:25, 60:40 and 50:50) for using them for control delivery of ofloxacin. The blends were characterized by Fourier transmission infra red spectroscopy (FTIR), UV-visible spectroscopy (UV), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis. From the FTIR spectra the various groups present in chitosan and PCL blend were monitored. The homogeneity, morphology and crystallinity of the blends were ascertained from SEM and XRD data, respectively. The swelling studies have been measured at different drug loading. The kinetics of the drug delivery system has been systematically studied. Drug release kinetics was analyzed by plotting the cumulative release data vs. time by fitting to an exponential equation which indicated the non-Fickian type of kinetics. The drug release was investigated at different pH medium and it was found that the drug release depends upon the pH medium as well as the nature of matrix. © 2009 Elsevier Ltd. Source


Kumar R.R.,Indian Institute of Science | Rao K.N.,Indian Institute of Science | Phani A.R.,Nano Research for Advanced Materials and Technologies
Materials Letters | Year: 2012

For the first time silicon nanowires have been grown on indium (In) coated Si (100) substrates using e-beam evaporation at a low substrate temperature of 300 °C. Standard spectroscopic and microscopic techniques have been employed for the structural, morphological and compositional properties of as grown Si nanowires. The as grown Si nanowires have randomly oriented with an average length of 600 nm for a deposition time of 15 min. As grown Si nanowires have shown indium nanoparticle (capped) on top of it confirming the Vapor Liquid Solid (VLS) growth mechanism. Transmission Electron Microscope (TEM) measurements have revealed pure and single crystalline nature of Si nanowires. The obtained results have indicated good progress towards finding alternative catalyst to gold for the synthesis of Si nanowires. © 2011 Elsevier B.V. Source


Kumar R.R.,Indian Institute of Science | Rao K.N.,Indian Institute of Science | Phani A.R.,Nano Research for Advanced Materials and Technologies
Materials Letters | Year: 2012

Silicon nanowires (NWs) have been grown in the vapor phase for the first time with bismuth (Bi) as a catalyst using the electron beam evaporation method at a low substrate temperature of 280 °C. The grown Si nanowires were randomly oriented on the substrate with an average length of 900 nm for a deposition time of 15 min. Bi faceted nanoparticles (crowned) at the end of the grown Si nanowires have been observed and attributed to the Vapor-Liquid-Solid (VLS) growth mechanism. Transmission Electron Microscopy analysis on the nanowires revealed their single crystalline nature and interestingly bismuth particles were observed in Si nanowires. The obtained results have shown a new window for Si nanowires growth with bismuth as a catalyst. © 2012 Elsevier B.V. All rights reserved. Source

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