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Fabrication and growth mechanism of ultra‑crystalline C60 on silicon substrate in vacuum
Hongyu Wang,Ashutosh Rath,Shu Hearn Yu,Meng Seng Tan,Stephen J. Pennycook,Daniel H. C. Chua 한국탄소학회 2021 Carbon Letters Vol.31 No.2
We report a simple procedure to fabricate single crystals 3D C60 having an FCC structure on silicon substrates using a vapour–solid set-up in vacuum conditions. The morphology of the deposited film can be tuned by controlling the temperature and position of the substrate. The as-fabricated samples are extensively characterised by transmission electron microscopy, scanning electron microscope, X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and nanoindentation, which allow us to shed light on the recrystallization process of the C60. In addition, the growth mechanism of the formation of crystalline 3D structure of the C60 film is discussed in detail. Based on the newly gained knowledge of mechanism and its unique properties, fullerene has shown huge potential as a solid lubricant on various kinds of substrates.
( Manoranjan Nayak ),( Swagat S Rath ),( Manikkannan Thirunavoukkarasu ),( Prasanna K Panda ),( Barada K Mishra ),( Rama C Mohanty ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.9
A series of experiments were carried out with three native strains of microalgae to measure growth rates, biomass, and lipid productivities. Scenedesmus sp. IMMTCC-6 had better biomass growth rate and higher lipid production. The growth, lipid accumulation, and carbon dioxide (CO2) consumption rate of Scenedesmus sp. IMMTCC-6 were tested under different NaOH concentrations in modified BBM. The algal strain showed the maximum specific growth rate (0.474/day), biomass productivity (110.9 mg l-1d-1), and CO2 consumption rate (208.4 mg l-1d-1) with an NaOH concentration of 0.005 M on the 8th day of cultivation. These values were 2.03-, 6.89-, and 6.88-fold more than the algal cultures grown in control conditions (having no NaOH and CO2). The CO2 fixing efficiency of the microalga with other alternative carbon sources like Na2CO3 and NaHCO3 was also investigated and compared. The optimized experimental parameters at shake-flask scale were implemented for scaling up the process in a self-engineered photobioreactor. A significant increase in lipid accumulation (14.23% to 31.74%) by the algal strain from the logarithmic to stationary phases was obtained. The algal lipids were mainly composed of C16/C18 fatty acids, and are desirable for biodiesel production. The study suggests that microalga Scenedesmus sp. IMMTCC-6 is an efficient strain for biodiesel production and CO2 biofixation using stripping solution of NaOH in a cyclic process.
Thermal transition behaviour of iron oxide-polypyrrole nanocomposites
KomillaSuri,S.Annapoorni,R.P.Tandon,C.Rath,V.K.Aggrawal 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3
Distinct thermal transitions have been observed in nanocomposites based on iron oxide–polypyrrole prepared by simultaneous gelation and polymerization process. The transition behaviour for various iron oxide–polypyrrole compositions was investigated with the help of differential scanning calorimetery. It has been observed that the samples show a magnetic to nonmagnetic transition at 410 C. The presence of exothermic peak at 410 C is a strong indication of magnetic transition corresponding to c-Fe2O3 phase of iron oxide to a nonmagnetic a-Fe2O3 phase in these nanocomposites. However such a transition was not observed in nanocomposites containing lesser concentration of conducting polymer. 2002 Elsevier Science B.V. All rights reserved.
Giraddi, T.P.,Kadadevarmath, J.S.,Chikkur, G.C.,Rath, M.C.,Mukherjee, T. Korean Society of Photoscience 1997 Journal of Photosciences Vol.4 No.3
The effect of temperature on the fluorescence quenching of 2-(4-Methoxyphenyl)-5-(1-naphthyl)-1,3,4-oxadiazole (MPNO1), 2-(4-Methoxyphenyl)-5-(2-naphthyl)-1,3,4-oxadiazote(MPNO2), by aniline, and 2-Phenylindole (2-PI) by CCk, in toluene by steady state method and in benzene by time-resolved method have been carried out in the temperature range 30 - 70$\circ$C. The Stem-Volmer (S-V) plots, I$_0$/I against quencher concentration [Q] at different temperanares show positive deviations. The fluorescence lifetimes determined at different temperatures show no systematic variations and the variations being within the experimental error, the average values of lifetimes $ $\tau$ (t) are taken for further calculations. Rate constants such as Stem-Volmer quenching constants K$_sv}$, quenching rate parameters k$_q$ and k'$_q$, static quenching constant V and kinetic distance r are determined using the modified Stem-Volmer equation and sphere of action static quenching model. In order to see whether the reactions are diffusion limited, equations k$_q$ = e$^{-Eq/RT}$ and k'$_q$ = e$^{-Eq/RT}$ are used to determine the values of E$_q$ and E'$_q$, the activation energies for collisional quenching and the values of E$_q$ are 14.53. 17.28 and 16.20 kJ mole$^{-1}$ for MPNO1, MPNO2 and 2-PI respectively and the values of E'$_q$ are 14.62 and 17.73 for MPNO1 and MPNO2 respectively. From the magnitudes of various quantities it has been concluded that the reactions are diffusion limited and the observed positive deviations in the S-V plot are due to static and dynamic quenching.
Rath, J. J.,Veluvolu, K. C.,Defoort, M. Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>The estimation of road excitation profile is important for evaluation of vehicle stability and vehicle suspension performance for autonomous vehicle control systems. In this work, the nonlinear dynamics of the active automotive system that is excited by the unknown road excitation profile are considered for modeling. To address the issue of estimation of road profile, we develop an adaptive supertwisting observer for state and unknown road profile estimation. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is proven. Simulation results with Ford Fiesta MK2 demonstrate the effectiveness of the proposed observer for state and unknown input estimation for nonlinear active suspension system.</P>
Active Control of Nonlinear Suspension System Using Modified Adaptive Supertwisting Controller
Rath, Jagat J.,Veluvolu, Kalyana C.,Defoort, Michael Hindawi Limited 2015 Discrete dynamics in nature and society Vol.2015 No.-
<P>The suspension system is faced with nonlinearities from the spring, damper, and external excitations from the road surface. The objective of any control action provided to the suspension is to improve ride comfort while ensuring road holding for the vehicle. In this work, a robust higher order sliding mode algorithm combining the merits of the modified supertwisting algorithm and the adaptive supertwisting algorithm has been proposed for the nonlinear active suspension system. The proposed controller is robust to linearly growing perturbations and bounded uncertainties. Simulations have been performed for different classes of road excitations and the results are presented.</P>
Simultaneous Estimation of Road Profile and Tire Road Friction for Automotive Vehicle
Rath, J. J.,Veluvolu, K. C.,Defoort, M. IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.10
<P>The longitudinal motion control of automotive vehicles is heavily reliant on information about the time-varying tire road friction coefficient. In the presence of varying road roughness profiles, the effective vertical load on each wheel varies dynamically, influencing the tire friction. In this paper, we integrated the vertical and longitudinal dynamics of a quarter wheel to form an integrated nonlinear model. In the modeled dynamics, the time-varying random road profile and the tire friction are treated as unknown inputs. To estimate these unknown inputs and states simultaneously, a combination of nonlinear Lipschitz observer and modified super-twisting algorithm (STA) observer is developed. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is established. Simulation results performed with the high-fidelity vehicle simulation software CarSim demonstrate the effectiveness of the proposed scheme in the estimation of states and unknown inputs.</P>
An adaptive modified super-twisting sliding mode controller
J. J. Rath,Suneel K. Kommuri,Kalyana C. Veluvolu,M. Defoort,S. Tatinati 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
A robust higher order sliding mode algorithm combining the merits of the modified super-twisting algorithm and the adaptive super-twisting algorithm has been proposed for a class of nonlinear uncertain systems in this article. For a class of linearly growing perturbations whose upper bounds are not known, the convergence of the sliding dynamics in finite time is proven. To illustrate the effectiveness of the proposed approach, an adaptive robust controller based on the proposed algorithm is developed for the nonlinear active suspension system faced with perturbations from the road surface. Simulation results provided demonstrate the effectiveness of the proposed approach.