Banaras Hindu University

About: Banaras Hindu University is a education organization based out in Varanasi, Uttar Pradesh, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 11858 authors who have published 23917 publications receiving 464677 citations. The organization is also known as: Kashi Hindu Vishvavidyalay & Benares Hindu University.

Antialgal activity of a hepatotoxin-producing cyanobacterium, Microcystis aeruginosa

Abstract: Antimicrobial activity of toxin produced by a freshwater bloom-forming cyanobacterium Microcystis aeruginosa has been studied. When tested against certain green algae, cyanobacteria, heterotrophic bacteria and fungi, the toxin inhibited growth of only green algae and cyanobacteria. The toxin has been partially purified employing Thin layer chromatography (TLC) and High-performance liquid chromatography (HPLC) techniques and appears to be microcystin-LR (leucine–arginine). Both crude and purified toxins showed toxicity to mice, the clinical symptoms in test mice being similar to those produced by hepatotoxin. Purified toxin at a concentration of 50 μg ml−1 caused complete inhibition of growth followed by cell lysis in Nostoc muscorum and Anabaena BT1 after 6 days of toxin addition. Addition of toxin (25 μg ml−1) to the culture suspensions of the Nostoc and Anabaena strains caused instant and drastic loss of O2 evolution. Furthermore a marked reduction (about 87%) in the 14CO2 uptake was also observed at a concentration of 50 μg ml−1. Besides its inhibitory effects on photosynthetic processes, M. aeruginosa toxin (50 μg ml−1) also caused 90% loss of nitrogenase activity after 8 h of its addition. Experiments performed with 14C-labelled toxin indicate that the toxin uptake by cyanobacterial cells occurs both in light and dark. These results demonstrate that the toxin is strongly algicidal and point to the possibility that it may have an important role in establishment and maintenance of toxic blooms of M. aeruginosa in freshwater ecosystems. The relative significance of the hepatotoxic effect and the algicidal effect of the toxin is discussed with reference both to survival and dominance of M. aeruginosa in nature.

Poly-3-hexylthiophene based organic field-effect transistor: Detection of low concentration of ammonia

Abstract: The soluble poly-3-hexylthiophene (P3HT) based organic field effect transistors (OFETs) are fabricated and sensitivity of the device to ammonia vapour at room temperature is subsequently tested. The performance parameters of the OFET in air, water vapour and ammonia have been studied in order to explore the potential of this device as an ammonia sensor. The device parameters like drain–source current, mobility and threshold voltage are found to change significantly when the device is exposed to various concentrations of ammonia. The P3HT based OFET shows excellent response to ammonia in the range of 0.1–25 ppm at room temperature.