Bharathiar University

About: Bharathiar University is a education organization based out in Coimbatore, Tamil Nadu, India. It is known for research contribution in the topics: Thin film & Adsorption. The organization has 5812 authors who have published 8628 publications receiving 143934 citations. The organization is also known as: BU.

Ac impedance studies on proton conducting polymer electrolyte complexes (PVA+CH3COONH4)

Abstract: A proton conducting polymer electrolytes of pure polyvinyl alcohol and polyvinyl alcohol complexed with ammonium acetate having different compositions have been prepared by solution cast technique. FTIR spectrum confirms the complexation process. The conductivity of the pure polyvinyl alcohol is in the order 10−10 S/cm at ambient temperature and its value increases 104 times when complexed with 20% ammonium acetate. The Arrhenius plot for all electrolyte shows two different regions above and below the glass transition temperature. A high dielectric loss value is observed for the case of complexed PVA in comparison to pure PVA. Based on the study of relaxation spectra, it is found that the relaxation time decreases with increase in temperature and dopant concentration.

Improved sensing performance from methionine capped CdTe and CdTe/ZnS quantum dots for the detection of trace amounts of explosive chemicals in liquid media

Abstract: Water soluble methionine functionalized CdTe quantum dots (QDs) and CdTe/ZnS core–shell QD samples have been prepared by a reflux condensation method and have been used to detect explosive chemicals, such as dinitrotoluene (DNT), nitrotoluene (NT) and nitrobenzene (NB) in liquid media. Meisenheimer complex formation between the QD surface attached methionine and aromatic explosive molecules has helped to detect them selectively via a fluorescent quenching process. Fluorescence quenching occurred because of the transfer of excited electrons from QD to the explosive molecules. Depending upon the number of nitro groups present on the explosive molecule, the quenching efficiency of different analytes varied. Due to surface passivation and inductive effects, the methionine capped CdTe/ZnS core–shell quantum dot sample resulted in the maximum quenching constant.

Use of plant products and copepods for control of the dengue vector, Aedes aegypti

Abstract: The efficacy of plant extracts (neem tree, Azadirachta indica A. Juss.; Meliaceae) and copepods [Mesocyclops aspericornis (Daday)] for the control of the dengue vector Aedes aegypti L. was tested in the laboratory. Neem Seed Kernel Extract (NSKE) at 25, 50, 100, 200 and 400 ppm caused significant mortality of Ae. aegypti larvae. Lethal concentrations (LC50 and LC90) were worked out. The LC50 and LC90 values for I to IV larval instars were 111.98, 138.34, 158.93, 185.22 ppm and for pupae was 146.13 ppm, respectively. The LC90 value of I instar was 372.95 ppm, II instar was 422.77 ppm, III instar was 440.63 ppm, IV instar was 456.96 ppm, and pupae was 476.92 ppm, respectively. A study was conducted to test the whether the predatory efficiency of copepods on first instars changed in the presence of NSKE. The percentage of predatory efficiency of copepod was 6.80% in treatments without NSKE and the percentage of predatory efficiency increased up to 8.40% when copepods were combined with NSKE. This increase in predation efficiency may caused by detrimental effects of the neem active principle compound (Azadirachtin) on the mosquito larvae. Our results suggest that the combined application of copepods and neem extract to control Aedes populations is feasible. Repeated application of neem does not cause changes in copepod populations, because neem is highly degradable in the environment.

On the stability of impulsive functional differential equations with infinite delays

Abstract: In this paper, the stability problem of impulsive functional differential equations with infinite delays is considered. By using Lyapunov functions and the Razumikhin technique, some new theorems on the uniform stability and uniform asymptotic stability are obtained. The obtained results are milder and more general than several recent works. Two examples are given to demonstrate the advantages of the results. Copyright © 2014 John Wiley & Sons, Ltd.