Kousik Das

Green synthesis of silver nanoparticles and its application for mosquito control

Objective To synthesize and characterize silver nanoparticles from aqueous root extract of Parthenium hysterophorus (P. hysterophorus) and also to evaluate the potentiality of synthesized silver nanoparticles as larvacidal agent against Culex quinquefasciatus (Cx. quinquefasciatus).

An approach to polymer degradation through microbes

Inertness and indiscriminate uses as well as growing water and land pollution problems have lead to concern about plastics. Present paper investigates the possibility of plastic degradation by microbes isolated from forest soil and automobile washout sludge. The in-vivo degradation was studied by litter bag experiment by taking 1 g of each plastic and buried under forest soil and automobile wash-out sludge at a depth of 15 cm from the surface during the month of September to February, 20102011. An in-vitro experiment was started after collecting the plastic samples from the litter bag experiment and the microbes were isolated from the surface of the plastic. Then the isolated microbes inoculated in the Burk’s medium without carbon source in two sets, one with plastic and the other with polyethylene glycol (PEG). Result showed that no variety of plastic comfortable degraded under burial condition during six months. But interesting result was recorded from Scanning Electron Microscopy (SEM) study. The preliminary screening of biodegradation capability was done by Fourier Transform Infra Red (FTIR) Spectroscopy for surface changes. Again, degradation of PEG by microbes clearly indicates their existence in the said medium. Therefore it can be speculated that microbes has enough potential to degrade plastic with due course of time.

ARSENIC CONTAMINATION IN GROUNDWATER: A STATISTICAL MODELING

Mathematical modeling of water quality in rivers is an important tool for the planning and management of water resources. Nevertheless, the available models frequently show structural and functional limitations. With the objective of reducing these drawbacks, a new model has been developed to simulate water quality in rivers under unsteady conditions; this model runs on the Vensim PLE ® software and can also be operated for steady-state conditions. The following eighteen water quality variables can be simulated: DO, BODc, organic nitrogen (No), ammonia nitrogen (Na), nitrite (Ni), nitrate (Nn), organic and inorganic phosphorus (Fo and Fi, respectively), inorganic solids (Si), phytoplankton (F), zooplankton (Z), bottom algae (A), detritus (D), total coliforms (TC), alkalinity (Al.), total inorganic carbon (TIC), pH, and temperature (T). Methane as well as nitrogen and phosphorus compounds that are present in the aerobic and anaerobic layers of the sediment can also be simulated. Several scenarios were generated for computational simulations produced using the new model by using the QUAL2K program, and, when possible, analytical solutions. The results obtained using the new model strongly supported the results from the QUAL family and analytical solutions.