Pesticide residue in water--a challenging task in India.

Modern agriculture practices reveal an increase in use of pesticides to meet the food demand of increasing population which results in contamination of the environment. In India, crop production increased to 100 %, but the cropping area has increased marginally by 20 %. Pesticides have played a major role in achieving the maximum crop production but maximum usage and accumulation of pesticide residues is highly detrimental to aquatic and other ecosystem. Pesticide residues in drinking water have become a major challenge over the last few years. It has been monitored in public water supply resources in National capital territory, i.e., Delhi. Organochlorine pesticides (OCPs), mainly isomers of hexachlorohexane (HCH), dichloro-diphenyl-trichloroethane (DDT), endosulphan, endrin, aldrin, dieldrin, and heptachlore, were identified from potable water samples. Results suggested that continuous consumption of contaminated water can pose severe health threats to local residents of this area. Central Pollution Control Board (CPCB), Delhi, had found α and ß isomers of endosulphan residues in the Yamuna river. High concentrations of γ-HCH (0.259 µg/l) and malathion (2.618 µg/l) were detected in the surface water samples collected from the river Ganga in Kanpur, Uttar Pradesh (UP). High concentration of methyl parathion, endosulfan, and DDT were observed in water samples collected from the river at Bhagalpur, Bihar. The Industrial Toxicology Research Centre (ITRC), Lucknow (UP) study also found 0.5671 ppb concentrations of endosulfan in the river at Allahabad, UP. Similar results were found in other water samples in India.

Study of the Electrical Properties of Cu2ZnSnS4 (CZTS) Thin Film Using Atomic Force Microscopy (AFM) Techniques.

CZTS is a compound semiconductor made from elements which are plainly available and nonpoisonous having favorable optoelectronic properties for thin film solar cell (TFSC) applications. In this study, Cu-poor CZTS thin film was fabricated on soda lime glass (SLG)/Mo-deposited substrate using cosputtering followed by post sulfurization in H2S atmosphere. Local electrical transport study was carried out by using conductive atomic force microscopy (C-AFM) for small bias voltage (100 mV). Here we observed that most of the dark current (Idark) flow through grain boundaries (GBs) than grain interiors. The positive high current about 3.4 nA and sharp C-AFM signal at the GBs, dips to the zero (0) value at the grain interior. Local surface potential (Vsurface) study was carried out using kelvin probe force microscopy (KPFM), which showed that the positive Vsurface potential about 175 mV in the vicinity of GBs in a Cu-poor CZTS sample. On the basis of these results we inferred a potential landscape (VL) around the GBs. All result shows that due to variation in elemental composition which creates Cu-deficit or CuZn anti site defects at GBs, leads reduced effective band gap (Eeff) than the bulk towards grain inner to GBs.[-2pt].

Luminomagnetic bifunctionality of Mn(2+)-bonded graphene oxide/reduced graphene oxide two dimensional nanosheets.

Herein, we report the luminomagnetic bifunctional properties of two-dimensional (2D) Mn(2+) bonded graphene oxide (GO)/reduced graphene oxide (RGO) nanosheets synthesized using a facile route of oxidation followed by a solvothermal reduction method. Photoluminescence (PL) studies (excited by different wavelengths) revealed that the resonant energy transfer between Mn(2+) and sp(3)/sp(2) clusters of GO/RGO is responsible for the enhancement of emissions. Moreover, pH-sensitive PL behaviors have also been investigated in detail. The ferromagnetic behavior is believed to arise due to defects in Mn(2+) bonded GO composites. Thus, present reduction method provides a direct route to tune and enhance the optical properties of GO and RGO nanosheets bonded with Mn(2+) ions, which creates an opportunity for various technological applications.