Biosynthesis of silver nanoparticles using pre-hydrolysis liquor of Eucalyptus wood and its effective antimicrobial activity.

Herein, we described for the first time, biosynthesis of silver nanoparticles (AgNPs) using pre-hydrolyzed liquor of Eucalyptus wood under ambient conditions. The pre-hydrolyzed liquor containing a high amount of metabolites such as polyphenols, hemicelluloses and its derivatives are mainly assisted for the reduction and stabilization process of Ag+ ions to AgNPs. The formation of AgNPs is monitored by recording the UV-vis spectrophotometer for surface plasmon resonance (SPR) peak observed at ∼415nm. The intensity of SPR increased linearly with increasing the reaction time at ambient condition. X-ray diffraction (XRD) pattern of AgNPs reveals the formation of face-centered cubic structure. Field emission electron microscopy (FESEM) and transmission electron microscopy (TEM) images show the spherical shaped particles and narrow size distribution with an average diameter of 25-30nm. The elemental analysis by energy dispersive X-ray (EDAX) analysis confirms the presence of Ag as the major amount and is found to be 82%. Analysis of the fourier transform infrared (FT-IR) spectra of the NPs revealed the presence of phytoconstituents from pre-hydrolyzed liquor adsorbed on the surface of AgNPs. Moreover, in vitro, antimicrobial activity is found to be effective for as-synthesized AgNPs on tested bacteria (viz., P. aeruginosa, S. aureus and E. coli) followed by fungus (C. oxysporum, P. chrysogenum, C. albicans and A.niger). Thus, these results suggest the use of biosynthesized AgNPs as effective growth inhibitors for various biomedical applications.

Mathematical modeling for dissolved oxygen prediction in mixing zone--a case study.

Quality of water is of utmost importance for its intended use for any purpose. The river or stream ecology completely depends on DO concentration levels, and any absence or below the critical value will adversely affect the ecology of the river, and hence the flora and fauna of the water body. A 24 km stretch of Malaprabha river, near Belgaum in Karnataka State of India was selected for the application of mathematical modeling to predict the DO variation, due to the impact of organic loading from the Khanapur town. The entire stretch was divided into 16 transects, and variation in DO was predicted through the application of mathematical modeling, and simulated with the observed values of DO at each transect. The results agreed with the observed DO concentrations at each transect with little variation. Average DO values recorded at Station Slis 7.44 mg/L, the lowest DO value recorded at Station S2 with the minimum value of 6.98 mg/L due to the sewage disposal from Kanapur town. The predicted DO values at station S1 and S2 are 7.4 mg/L and 6.95 mg/L respectively. The measured values are in agreement with predicted values from the modeling. This study was conducted during the pre-monsoon season of 2005 - 2006 in which the DO values generally would be minimum. The application of predicting the DO in mixing zone of river may be the best strategy for waste load allocation to guide the practicing engineers and administrators to limit the organic loading in rivers and streams. This will help the decision makers in implementing the pollution prevention schemes of the region and to maintain the health of the riverine system.

Physico-chemical properties of Malaprabha River.

The quality of surface water of Malaprabha river with respect to physico-chemical parameters was investigated as part of a research work for the award of Ph.D. under Visveswaraya Technological University. 25 different parameters were analyzed, during the last one year. Quality of this surface water with regard to pH, TDS, chlorides, nitrates and Dissolved Oxygen is discussed in this paper. The concentrations of pH, TDS and chlorides were found to be within the safe limits for 95% of the samples collected at the Station 1, and were found on the higher side at the Station 2. DO level was found to be 7 mg/L, and more at Station 1 and varied in the range of 5 mg/L, at Station 2. This study was conducted during the year 2004-05. pH value for the Station 2 was found to be less than 7.0 for all the samples. Other parameters, viz. TDS, chlorides and nitrates also shpwed marked variations between the two Stations selected for the study.

Nitrate and fluoride levels in ground waters of Davanagere Taluka in Karnataka.

The quality of ground water supplies in Davanagere Taluk, situated in central part of Karnataka has been investigated with respect to pH, dissolved solids, chlorides, nitrates and fluorides. The levels of pH, dissolved solids and chlorides were found within the safe limits as prescribed by BIS, for more than 95% of the samples. Out of the 61 different borewell samples analysed, selected from different areas of Davanagere taluk, 26% of the samples are found to contain fluorides less than 0.50 PPM (lower safe limit prescribed by BIS) and 11.5% of the samples are found to contain more than 1.5 PPM of fluorides (higher safe limit prescribed by BIS). Further, it was also found during study that, 16.00% of the borewell samples analyzed, were found to contain more than 100.00 PPM of nitrates (measured as NO3 mg/L, safe limit prescribed by BIS). The values of fluorides and nitrates observed in different samples were in the range of 0.19 - 2.06 PPM and 0.08 - 308 PPM, respectively.