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Āgra, India

Devadoss H.A.,Stjohns College
International Journal of ChemTech Research | Year: 2014

Tranparent and colourless single crystals of phosphorous acid admixtured L-alanine (PALA) were grown by solution method for the first time at room temperature. In this work, L-alanine and phosphorous acid were used to synthesize PALA salt. XRD analysis confirms orthorhombic structure of the grown crystal. Suitability of PALA crystal for NLO application was determined by optical transmission and SHG efficiency analysis. Thermal stability of PALA crystal was determined by TG-DTA analysis. Third-order nonlinear (THG) studies of PALA crystal have been investigated by Z-scan method. The values of nonlinear refractive index (n2), the nonlinear absorption coefficient (β) and third-order nonlinear susceptibility (χ(3)) were estimated for the sample.


Nonlinear optical (NLO) single crystals of l-alanine admixtured with perchloric acid (LAPA) were grown for the first time by slow evaporation technique. The grown single crystals were subjected to different characterization analyses in order to find out its suitability for device fabrication for optoelectronic applications. Orthorhombic structure of LAPA crystal was confirmed by single crystal X-ray diffraction. The LAPA crystallizes in non-centrosymmetric structure, which is an essential criterion for second-order NLO effects. The third-order nonlinearities of LAPA crystal have been investigated by the Z-scan method. The values of nonlinear refractive index (n2), the nonlinear absorption coefficient (β) and third-order nonlinear susceptibility (Χ(3)) are estimated for the sample. The grown sample was characterized by Energy Dispersive Analysis by X-rays (EDAX) to confirm the presence of elements. The optical quality was assessed by recording UV - visible transmission spectrum. Thermal behavior and thermal stability of crystal were studied using thermogravimetric/differential thermal (TG/DTA) techniques. The dielectric constant and dielectric loss have been measured for different frequencies and at different temperatures. The mechanical properties of the grown crystals were studied using Vickers microhardness tester. © 2014 Elsevier GmbH. All rights reserved.


Saifi M.A.,Stjohns College | Singh H.B.,Stjohns College
Pollution Research | Year: 2011

Present paper deals with the physico - chemical parameters and heavy metal contents in the effluents discharged from the sugar mill under study. Most of the physico- chemical parameters such as colour, odour, temperature, pH, electrical conductivity, total dissolved solids, dissolved oxygen, COD, BOD, alkalinity, total hardness, Ca +2, Mg +2, sulphate, chloride, fluoride and concentration of heavy metals (like Cr, Mn, Ni, Zn, Cd, Fe, Cu, Pb and Hg) of the effluent collected from the various sites between the exit point at the mill and discharge point in a natural drain in different months have been determined. © EM International.


Verghese P.S.,Stjohns College | Garg M.,Stjohns College
Oriental Journal of Chemistry | Year: 2015

Water quality of Agra city is impaired by the presence of large number of industries in the city. From the observed data it is found that drinking water of Agra city is contaminated with toxic heavy metals like chromium, copper, cadmium, lead, and nickel. Among all these heavy metals, chromium is found to be in comparatively large amounts because most of the leather industries located in Agra city adopt chrome tanning procedure as their basic step for dehairing and dehiding. Presence of high concentration of chromium and other heavy metals in drinking water pose deleterious effects on the health of human beings therefore it becomes necessary to employ certain technological methods to keep the concentration of such toxic heavy metals within their desirable limits.


Sivaganesh G.,Alagappa Chettiar College of Engineering And Technology | Daniel Sweetlin M.,Stjohns College | Arulgnanam A.,Stjohns College
Journal of the Korean Physical Society | Year: 2016

In this paper, we present a numerical investigation on the robust synchronization phenomenon observed in a unidirectionally-coupled quasiperiodically-forced simple nonlinear electronic circuit system exhibiting strange non-chaotic attractors (SNAs) in its dynamics. The SNA obtained in the simple quasiperiodic system is characterized for its SNA behavior. Then, we studied the nature of the synchronized state in unidirectionally coupled SNAs by using the Master-Slave approach. The stability of the synchronized state is studied through the master stability functions (MSF) obtained for coupling different state variables of the drive and response system. The property of robust synchronization is analyzed for one type of coupling of the state variables through phase portraits, conditional lyapunov exponents and the Kaplan-Yorke dimension. The phenomenon of complete synchronization of SNAs via a unidirectional coupling scheme is reported for the first time. © 2016, The Korean Physical Society.

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