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Synthesis of some substituted pyrazole-1- carbothioamides and spectral correlations in 3-(2,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1- carbothioamides
G. Thirunarayanan,K. G.Sekar
QScience Connect , 2013, DOI: 10.5339/connect.2013.18
Abstract: Background: This study aims to synthesise a series of 1-thiocarbomyl pyrazolines, including 3-(2,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides, using solvent-free fly-ash:PTS catalyzed cyclization between chalcones and thiosemicarbazide, under microwave irradiation. Then to characterize them using analytical, physical and spectroscopic data. Methods: Solvent-free microwave assisted cyclization was adopted for the synthesis of 1-thiocarbomyl, including 3-(2,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1Hpyrazole-1-carbothioamides, using fly-ash:PTS as the catalyst. They were characterised by IR, NMR and mass spectroscopic data. The infrared (IR) and nuclear magnetic resonance (NMR) spectral data was correlated with substituent constants, F and R parameters, using Hammett equation, to study the effect of substituents. Results: The yields of the synthesised chalcones were more than 85%. The spectral data of these 3-(2,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1- carbothioamides had been correlated, using single and multi-linear regression analysis. These gave a satisfactory or fair degree of correlation with some parameters. Conclusion: Easy handling, non-hazardous and environmentally benign cyclization method had been adopted for the synthesis of 1-thiocarbomyl pyrazolines using fly-ash:PTS as catalyst, with better yields. Some of the Hammett spectral correlations were found to be satisfactory, with the observed spectroscopic data. Keywords: 3-(2,4-dibromophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1- carbothioamides, fly-ash:PTS, Solvent-free synthesis, Hammett correlations.
Oxidation of S-phenylmercaptoacetic acid by quinoxalinium dichromate
G. Manik,K. G. Sekar
- , 2013,
Abstract: The conversion of S-phenylmercaptoacetic acid to the corresponding sulfoxide was performed in 50% (v/v) wateraceticacid mixture in the presence of perchloric acid medium. The order with respect to S-phenylmercaptoacetic acid and quinoxalinium dichromate were both one and inverse first order with respect to hydrogen ion concentration. Decrease in dielectric constant of the medium increased the rate of reaction. Ionic strength had a considerable influence on a reaction rate, indicating the involvement of a dipole in the rate-limiting step. A suitable mechanism and rate law in consonance with the observed facts is propose
The Influence of Combined Uphill and Downhill Running on Speed Parameters
Shambhulingayya swamy,K Sekar Babu,G Ravindran
World Journal of Science and Technology , 2011,
Abstract:
Invasive Alien Plants of Indian Himalayan Region—Diversity and Implication  [PDF]
K. Chandra Sekar
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.32021
Abstract: The present study deals with comprehensive list of Invasive alien plants of Indian Himalayan Region with background information on family, habit and nativity. A total of 190 invasive alien species under 112 genera, belonging to 47 families have been recorded. Among these, the dicotyledons represent by 40 families, 95 genera and 170 species; monocotyledons represent by 7 families, 17 genera and 20 species. The analysis of invasive species reveals that 18 species have been introduced intentionally, while the remaining species established unintentionally through trade. In terms of nativity, amongst 13 geographic regions, the majority of invasive plants reported from American continent (73%). While in life form analysis, the herbs (148 species) are dominant, followed by shrubs (19 species), Grass (11 species), Trees (4 species), sedges and climber (3 species each). Most of the invasive species are annual habit (63%). Apart from these, 90 species (47%) are being used by locals for medicinal purposes. A better planning is needed for early detection to control and reporting of infestations of spread of new and naturalized weeds to be monitored.
Role of Strontium on the Crystallization of Calcium Hydrogen Phosphate Dihydrate (CHPD)  [PDF]
K. Suguna, C. Sekar
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.107048
Abstract: Calcium hydrogen phosphate dihydrate (CHPD, CaHPO4· 2H2O) or brushite is found quite frequently in urinary calculi (stones). Crystallization of brushite has been carried out in sodium metasilicate (SMS) gel with and without adding ‘Sr’ as additive. In pure system, dicalcium phosphate anhydrous (DCPA, CaHPO4) or monetite and hydroxyapatite (HA, Ca5(PO4)3(OH)) grew along with brushite. The presence of Sr suppressed the formation of HA and enhanced the number and size of monetite crystals and changed the morphology of brushite crystals from needle shape to octopus-like shape. The samples were characterized by powder & single crystal X-ray diffraction (XRD), scanning electron microscopy (SEM), Xray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA).
Shape Transition in the Epitaxial Growth of Gold Silicide in Au Thin Films on Si(111)
K. Sekar,G. Kuri,P. V. Satyam,B. Sundaravel,D. P. Mahapatra,B. N. Dev
Physics , 1994, DOI: 10.1103/PhysRevB.51.14330
Abstract: Growth of epitaxial gold silicide islands on bromine-passivated Si(111) substrates has been studied by optical and electron microscopy, electron probe micro analysis and helium ion backscattering. The islands grow in the shape of equilateral triangles up to a critical size beyond which the symmetry of the structure is broken, resulting in a shape transition from triangle to trapezoid. The island edges are aligned along $Si[110]$ directions. We have observed elongated islands with aspect ratios as large as 8:1. These islands, instead of growing along three equivalent [110] directions on the Si(111) substrate, grow only along one preferential direction. This has been attributed to the vicinality of the substrate surface.
Rhododendrons in Indian Himalayan Region: Diversity and Conservation  [PDF]
K. Chandra Sekar, Sunil Kumar Srivastava
American Journal of Plant Sciences (AJPS) , 2010, DOI: 10.4236/ajps.2010.12017
Abstract: The genus Rhododendron of Indian Himalayan Region (IHR) has been enumerated in the present paper. A total of 87 species, 12 subspecies and 8 varieties of Rhododendrons recorded in IHR, among these 6 species and one subspecies are reported from Western Himalaya. The maximum concentration of 86% observed in Arunachal Pradesh (75 species). The species of Rhododendrons exhibit significant diversity in habit and broad range of distribution from the altitude of 800-6000 m. and the best range is observed in 3001-3500 m altitudes. In analysis revealed 20 taxa are endemic, 30 are rare, 24 are threatened / endangered, 3 are vulnerable and 47 taxa have to be assessed. The major threats to rhododendrons are deforestation and unsustainable extraction for firewood and incense by local people has been discussed.
EVALUATION OF BIVOLTINE SILKWORM GENETIC RESOURCES THROUGH CLUSTER ANALYSIS AND IDENTIFICATION OF BETTER PERFORMING BIVOLTINE ACCESSIONS
LOKESH, G.,MAHESWARI, M.,MISHRA, R.K.,MURTHY, G.N.,SEKAR, S.,SOMAPRAKASH, D.S.
- , 2019,
Abstract: The evaluation of germplasm is essential for its effective utilization in the silkworm crop improvement and sustainable maintenance of silkworm genetic resources. In the present study, bivoltine silkworm genetic resources comprising of 369 bivoltine silkworm genotypes (209 indigenous and 160 exotic) were evaluated on 11 important quantitative & qualitative parameters. Based on the performance, silkworm genotypes have been grouped into 20 clusters by Ward’s minimum variance cluster analysis. High variability was observed in the different genotypes for different parameters studied ranging 3.83 to 14.64% showing highly heterozygous in nature. Further the accessions are assigned the ranking based on the evaluation index of the performance in particular trait
On regular generalized b-closed set
K. Mariappa,S. Sekar
International Journal of Mathematical Analysis , 2013,
Abstract: In this paper, the authors introduce a new class of sets called regulargeneralized b-closed sets in topological spaces (briefly rgb-closed set). Also wediscuss some of their properties and investigate the relations between theassociated topology.
Stability analysis of soret effect on thermohaline convection in dusty ferrofluid saturating a Darcy porous medium
K. Raju,R. Sekar
- , 2015, DOI: 10.14419/gjma.v3i1.3086
Abstract: The Soret–driven ferro thermoconvective instability of multi–component fluid in a porous medium heated from below and salted from above in the presence of dust particles subjected to a transverse uniform magnetic field has been analyzed using Darcy model for various values of permeability of the porous medium. The salinity effect has been contained in magnetization and density of the ferrofluid. A small thermal perturbation imparted on the basic state and a linear stability analysis is used for this model for which normal mode technique is applied. An exact solution is obtained for the case of two free boundaries and both stationary and oscillatory instabilities have been investigated. It is found that the system destabilizes only through stationary mode. The non-buoyancy magnetization parameter, the dust particle parameter and the permeability of the porous medium are found to destabilize the system. The results are depicted graphically.
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