Improved properties & fatigue resistant behaviour OF Ba(Zr0.15Ti0.85)O3 ferroelectric ceramics

M.L.V. Mahesh,Prem Pal,V.V. Bhanu Prasad,A.R. James 한국물리학회 2020 Current Applied Physics Vol.20 No.12

The microstructure, dielectric and piezoelectric properties of Zr doped BaTiO3 ceramics sintered at optimum temperature, are investigated. High energy ball milling technique is adopted to realize nano-sized powders of Ba (Zr0.15Ti0.85)O3 ceramics. Increased boundary mobility of fine powders aided to obtain a relative density of >98.8% of theoretical density corresponding to ceramics under study. Internal stresses in these ceramics are found to be relieved by grain-boundary sliding. The Ba(Zr0.15Ti0.85)O3 ceramics synthesized at relatively low sintering temperatures exhibit remarkable, enhanced dielectric properties viz. improved polarization, high unipolar strain values comparable to Zr doped BaTiO3 single crystals of same composition, at relatively lower electric fields and also exhibit better fatigue tolerant properties. The underlying mechanisms responsible for superior dielectric, ferroelectric and piezoelectric properties are discussed.

Geometrical thickness of titania photoanode as an influential parameter in controlling the photovoltaic performance of CdS Quantum Dot Sensitized Solar cells

M.B. Rajendra Prasad,Parvin S. Tamboli,Ravi V. Ingle,Kiran D. Diwate,Prashant K. Baviskar,B.R. Sankpal,K.C. Mohite,Sandesh R. Jadkar,Habib M. Pathan 한국물리학회 2017 Current Applied Physics Vol.17 No.12

Geometrical thickness of photoelectrode is one of the important design considerations that can substantially improve the device performance in Quantum Dot Sensitized Solar cells. The present work deals with the influence of the Photoanode (PA) thickness on the photovoltaic performance of these excitonic solar cells. Optical, morphological and electrochemical properties of these films are studied using UV eVisible spectroscopy, Scanning electron microscopy and Cyclic Voltammetry. Sandwich solar cells assembled using these PAs are further characterized using Electrochemical Impedance Spectroscopy and Chronoamperometry to investigate the electron transfer processes occurring at the sensitized photoelectrode/ Electrolyte interface. These cells are then evaluated for their photovoltaic performance using JV characteristics. The results obtained are explained qualitatively invoking the thickness dependent parameters like Light harvesting efficiency and Electron transfer yield to establish the effect of PA thickness on the solar cell performance.

Self compacting reinforced concrete beams strengthened with natural fiber under cyclic loading

Prasad M.L.V,Prasenjit saha,P.R.Kumar 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.5

The present work focuses on the use of coconut fiber in self compacting concrete. Self- Compacting Concrete (SCC) is a highly flowable, stable concrete which flows readily into place, filling formwork without any consolidation and without undergoing any significant segregation. Use of fibers in SCC bridge the cracks and enhance the performance of concrete by not allowing cracks to propagate. They contribute to an increased energy absorption compared to plain concrete. Coconut fiber has the highest toughness among all natural fibers. It is known that structures in the seismic prone areas are always under the influence of cyclic loading. To justify the importance of strengthening SCC beams with coir fiber, the present work has been undertaken. A comparison is made between cyclic and static loading of coconut fiber reinforced self compacting concrete (FRSCC) members. Using the test data obtained from the experiment, hysteresis loops were drawn and comparison of envelope curve, energy dissipation, stiffness degradation were made and important conclusions were draw to justify the use of coconut fiber in SCC.

Strontium in Al–Si–Mg Alloy: A Review

M. R. Sai Ganesh,Nikhil Reghunath,M. J.Levin,Adarsh Prasad,Sanapala Doondi,Karthik V. Shankar 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.1

The present article reviews the development of cast aluminium alloy with highlights on improvement in the morphological,mechanical, tribological, and ageing properties of Sr modifed Al–Si and Al–Si–Mg alloys. Aluminium and its alloys fndapplication in the automobile and aviation industries. The main objective of utilizing aluminium alloys for structural application, manufacturing of pistons and engine block for automobile industries is its lightweight and low density. However, thelow hardness of these alloys results in a high wear rate. The main factor that afects the properties of aluminium alloys isits microstructure, morphological behaviour, size of the grain and phase distribution. The morphological modifcation forthese alloys is done through diferent processing techniques like casting, heat treatment, solutionising, and alloying elementaddition which augments the mechanical, corrosion, and tribological behaviour of these alloys. Of the alloying elementadditions Sr has proved to a very efective modifer for the alloy, and hence the method of modifcation was studied in detail. The unwanted efects especially porosity, being one of the main factors for failure of components, were investigated andmethods to reduce it according to many researchers were included. Reinforcing the aluminium matrix with ceramic particlesand surface modifcation also enhances the properties of aluminium alloys. The current article reviews the recent techniquesto augment the microstructure, value of hardness, tensile properties, tribological properties, and corrosion behaviour of castAl–Si and Al–Si–Mg alloys by the addition of strontium. Moreover, this review also focuses on the future scope of thesealuminium alloys for structural application in automobile and lightweight industries.

Effect of Cr3+ Substitution on Structural, Magnetic and Dielectric Properties of Nanocrystalline Ni0.5Zn0.5CrxFe(2-x)O4 Ferrite System

M. Siva Ram Prasad,B. R. Babu,K. V. Ramesh,K. Trinath 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7

Polycrystalline Ni–Zn–Cr ferrite nanoparticles with composition Ni0.5Zn0.5CrxFe2-xO4 (for x in the range of 0.00–0.25 insteps of 0.05) were prepared through the nitrate-citrate gel autocombustion method. The as-obtained powders were ground and annealed at 1000℃ for 4 h and characterized for spinel phase using X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). X-ray diffraction revealed the existence of single phase spinel while the TEM micrographs showed the presence of nearly spherical particles with soft agglomeration. Pelleted and toroidal samples of the same ferrite compound were sintered at 1000℃ for 4 h. The dielectric constant and the dielectric loss tangent decreased with frequency in the range of 1 kHz–13 MHz while the initial permeability remained almost constant at lower measuring frequencies and thereafter increased with frequency for all samples. The observed variations have been discussed in the light of existing understanding.

Trihalomethanes in the Cooling Discharge of a Power Plant on Chlorination of Intake Seawater

R. K. Padhi,S. Subramanian,A. K. Mohanty,S. N. Bramha,M. V. R. Prasad,K. K. Satpathy 대한환경공학회 2012 Environmental Engineering Research Vol.17 No.-

Trihalomethanes (THMs) formation and species distribution in the discharged chlorinated cooling seawater of a nuclear power plant was assessed during Aug 2010 to July 2011. The monthly variation of chlorine demand of the source seawater under laboratory chlorination conditions was studied for the same period. The entire period can be divided into two separate zones; viz. Feb, Mar, Apr, Sep, Oct (low chlorine demand), and May, Jun, Jul, Aug, Nov, Dec, Jan (high chlorine demand) months. Bromoform was found to be the single dominant THMs species in the chlorinated cooling seawater discharge. The THMs concentration was observed to be highest for the month of Nov 2010 (41 μg/L), and lowest for Feb 2011(12 μg/L). Under laboratory chlorination of intake seawater with 1 ppm Cl2, the concentration of THMs that was formed within 5–15 min is in agreement with the actual concentration in the discharge water. A simplified predictive approach is proposed for the total THMs concentration at the cooling discharge outlet of a power plant, based on the actual chlorine demand of source water.

HALL EFFECTS ON STEADY HYDROMAGNETIC FLOW OF A COUPLE STRESS FLUID THROUGH A COMPOSITE MEDIUM IN A ROTATING PARALLELPLATE CHANNEL WITH POROUS BED ON THE LOWER HALF

M. VEERA KRISHNA,R. SIVA PRASAD,D.V. KRISHNA 장전수학회 2010 Advanced Studies in Contemporary Mathematics Vol.20 No.3

We discuss the Hall effects on steady hydro magnetic flow of couple stress fluid in a rotating parallel plate channel bounded by a porous bed on one side. The exact solutions for the velocities in the clean fluid region and porous medium have been obtained analytically. Their behaviour has been discussed computationally with reference to the various governing parameters. The shear stresses on the boundaries also obtained analytically and discussed computationally.

Experimental Heat and Mass Transfer Coefficients of a Two Stage Spray and Packed Bed Deaerator

( K. V. Suryanarayana ),( R. A. Bakar ),( Chang Sik Lee ),( D. M. Reddy Prasad ),( K. V. Sharma ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

Experiments are conducted to study the influence of mass flow rate on heat and mass transfer coefficients in a two stage deaerator consisting of a spray stage and packed bed combination. It has been observed that an increase in mass flow rate of water increases the heat transfer coefficients in both the stages of the deaerator, whereas the mass transfer coefficients increases in the first and decreases in the second stage. The heat transfer coefficient in the spray stage is 300 times greater than that obtained in the packed bed. The mass transfer coefficient decreased by 2 times in the second stage with increase in flow rate in the range of experiments conducted. It has been observed that oxygen can be reabsorbed by the outgoing feed water under certain conditions of flow.

Transgenic tomato expressing dsRNA of juvenile hormone acid O-methyl transferase gene of Helicoverpa armigera (Lepidoptera: Noctuidae) affects larval growth and its development

Navale Prakash M,Manamohan Maligeppagol,Asokan R.,Sharath Chandra G.,Prasad Babu K.,Latha J.,Krishna Kumar N.K.,Ellango R.,Krishna V. 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

Helicoverpa armigera is an important pest infesting a number of crops of high commercial value leading to huge economic losses globally. RNA interference (RNAi) is a potent tool for the control of insect pests and towards this objective, transgenic tomato expressing dsRNA of Juvenile hormone acid methyl transferase (JHAMT) gene of H. armigera was developed. The H. armigera larvae fed on HaJHAMT tomato leaves led to a severe (90%) down regulation of the cognate gene expression thus adversely affected the feeding and metamorphosis. Reduction in larval and pupal weight and inability to undergo complete metamorphosis were observed that led to larval-pupal intermediates and subsequently affected the eclosion. Thus, JH down regulation is an attractive target due to specificity to insects and its important role in insect growth and development to engineer insect resistance in crops using RNAi.

Enhanced photocatalytic activity of nanostructured titanium dioxide/polyaniline hybrid photocatalysts

Reddy, K.R.,Karthik, K.V.,Prasad, S.B.B.,Soni, S.K.,Jeong, H.M.,Raghu, A.V. Pergamon Press 2016 Polyhedron Vol.120 No.-

<P>An organo-inorganic photocatalytic nanocomposite material based on conjugated polymer, polyaniline (PANI) with titanium dioxide (TiO2) nanoparticles has been developed by performing in situ chemical oxidative polymerization of aniline with ammonium persulfate (APS) oxidant in the presence of hydrothermally synthesized TiO2 nanoparticles. The structural and morphological properties of TiO2/PANI nanocomposites were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. The TEM results of the TiO2/PANI nanocomposites showed that TiO2 nanoparticles of 5-10 nm of sizes are dispersed in the PANI matrix. FT-IR spectra show that the TiO2/PANI nanocomposites are almost identical to the structure of PANI alone. The photocatalytic activities of the nanocomposites were evaluated by the photocatalytic degradation of Rhodamine B (RhB), Methylene Blue (MB) and phenol in the presence of UV-light irradiation. The composite catalysts exhibited higher photocatalytic activity for the degradation of organic pollutants than unmodified TiO2 nanoparticles, which is due to sensitizing effect of PANI. (C) 2016 Published by Elsevier Ltd.</P>