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.

Predation by Asian bullfrog tadpoles, Hoplobatrachus tigerinus, against the dengue vector, Aedes aegypti, in an aquatic environment treated with mosquitocidal nanoparticles.

Abstract: Aedes aegypti is a primary vector of dengue and chikungunya. The use of synthetic insecticides to control Aedes populations often leads to high operational costs and adverse non-target effects. Botanical extracts have been proposed for rapid extracellular synthesis of mosquitocidal nanoparticles, but their impact against predators of mosquito larvae has not been well studied. We propose a single-step method for the biosynthesis of silver nanoparticles (AgNP) using the extract of Artemisia vulgaris leaves as a reducing and stabilizing agent. AgNP were characterized by UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). SEM and XRD showed that AgNP were polydispersed, crystalline, irregularly shaped, with a mean size of 30–70 nm. EDX confirmed the presence of elemental silver. FTIR highlighted that the functional groups from plant metabolites capped AgNP, stabilizing them over time. We investigated the mosquitocidal properties of A. vulgaris leaf extract and green-synthesized AgNP against larvae and pupae of Ae. aegypti. We also evaluated the predatory efficiency of Asian bullfrog tadpoles, Hoplobatrachus tigerinus, against larvae of Ae. aegypti, under laboratory conditions and in an aquatic environment treated with ultra-low doses of AgNP. AgNP were highly toxic to Ae. aegypti larval instars (I–IV) and pupae, with LC50 ranging from 4.4 (I) to 13.1 ppm (pupae). In the lab, the mean number of prey consumed per tadpole per day was 29.0 (I), 26.0 (II), 21.4 (III), and 16.7 (IV). After treatment with AgNP, the mean number of mosquito prey per tadpole per day increased to 34.2 (I), 32.4 (II), 27.4 (III), and 22.6 (IV). Overall, this study highlights the importance of a synergistic approach based on biocontrol agents and botanical nano-insecticides for mosquito control.

The preparation of MnFe2O4 decorated flexible graphene wrapped with PANI and its electrochemical performances for hybrid supercapacitors

Abstract: A modest, cost effective and eco-friendly method is employed for the preparation of MnFe2O4 nanocube decorated, flexible graphene sheets, followed by polyaniline (PANI) which is wrapped by an in situ chemical oxidative polymerization method. The formation of the hybrid composites and their individual constituents are realized through X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR) and Raman spectroscopy. The MnFe2O4 nanocube decorated flexible graphene and PANI wrapped composite is visualised through transmission electron microscopic (TEM) images. The decorated MnFe2O4 particles have sizes in the range of 75–100 nm. The capacitive properties of the ternary composite is investigated and it has the obtained specific capacitance of 338 F g−1 at 0.5 mA cm−2 in 1 M NaCl aqueous electrolyte, which is 10 times greater than the pristine MnFe2O4 (32 F g−1). Similarly, the fabricated hybrid supercapacitor (MGP‖AC) provides the specific capacitance of about 51.87 F g−1 at 5 mV s−1 and its energy density is 10.25 W h kg−1 at 10 mA cm−2. Thus the obtained significant properties of the ternary composite are due to the distinctive characteristics of the individual constituents which leads to enhanced electrochemical properties like reducing the internal resistance and diffusion path length via the synergistic effect.

Synthesis and improved electrochemical performances of nano β-NiMoO4–CoMoO4·xH2O composites for asymmetric supercapacitors

Abstract: Nano-sized β-NiMoO4–CoMoO4·xH2O composites were synthesized by a solution combustion synthesis (SCS) technique. The effect of weight ratio of transition metal on the electrochemical capacitive performance of the nanocomposites was investigated by cyclic voltammetry and galvanostatic charge–discharge methods. The NiMoO4–CoMoO4·xH2O nanocomposite with weight ratio of 3:1 (Ni:Co) exhibits enhanced capacitive behaviour relative to other composites and delivered a maximum specific capacitance of 1472 Fg−1 at a current density of 5 mAcm−2. The enhancement in specific capacitance is due to the small particle size, uniform size distribution, high surface area and high weight fraction of Ni. The synergistic effect of nickel and cobalt improves the electrochemical behaviour relative to pure nickel and cobalt molybdates. A full cell was fabricated using the β-NiMoO4–CoMoO4·xH2O nanocomposite (3:1) and activated carbon (AC) as a positive and negative electrode, respectively. The cell delivered high capacitance (80 Fg−1) and energy density (28 Wh kg−1) and good cycling stability up to 1000 cycles.