Thermal co-reduction approach to vary size of silver nanoparticle: its microbial and cellular toxicology

In recent years, silver nanoparticles (AgNPs) have attracted considerable interest in the field of food, agriculture and pharmaceuticals mainly due to its antibacterial activity. AgNPs have also been reported to possess toxic behavior. The toxicological behavior of nanomaterials largely depends on its size and shape which ultimately depend on synthetic protocol. A systematic and detailed analysis for size variation of AgNP by thermal co-reduction approach and its efficacy toward microbial and cellular toxicological behavior is presented here. With the focus to explore the size-dependent toxicological variation, two different-sized NPs have been synthesized, i.e., 60 nm (Ag60) and 85 nm (Ag85). A detailed microbial toxicological evaluation has been performed by analyzing minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), diameter of inhibition zone (DIZ), growth kinetics (GrK), and death kinetics (DeK). Comparative cytotoxicological behavior was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It has been concluded by this study that the size of AgNPs can be varied, by varying the concentration of reactants and temperature called as “thermal co-reduction” approach, which is one of the suitable approaches to meet the same. Also, the smaller AgNP has shown more microbial and cellular toxicity.     

Multivariate statistical and GIS-based approaches for toxic metals in tropical mangrove ecosystem,southeast coast of India

The heavy metal concentrations in water and sediment samples were investigated in the tropical Muthupet mangrove ecosystem, southeast coast of India. The results demonstrated that, ranges of metals in water comprise of Cd—0.05 to 3.72; Cu—0.5 to 4.43; Pb—6.31 to 17.87; Zn—0.0 to12.91 ppm and sediment comprises of Cd—0.06 to 0.57; Cu—4.46 to 20.59; Pb—2.90 to 21.35; Zn—4.41 to 39.18 ppm. In all the three sites, heavy metals in sediment exhibited significant higher concentrations compared to water, except Cd. The spatial distribution of metals in water and sediment samples followed a similar pattern except Cd with the preponderance of Zn (75% of total metals) followed by Cu and Pb. Muller’s Geoaccumulation indexes (Igeo) showed Cd is a potent pollutant in the ecosystem and moderately contaminated the study area. The aquaculture and agricultural culture practices follow improper disposal of municipal wastages, and idol immersion activities are the potent metallic sources for heavy metal pollution were identified by performing principle component analysis. In order to protect the ecosystem from further contamination, regular monitoring is needed to in order to control the anthropogenic discharges.

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Environmental,economic, and performance assessment of solar air heater with inclined and winglet baffle

Environmental Science and Pollution Research - To investigate the solar air heater’s (SAH) effectiveness, experiments are conducted using flat plate and artificially roughened plate in terms...     

Bacterial community structure analysis of sediment in the Sagami River, Japan using a rapid approach based on two-dimensional DNA gel electrophoresis mapping with selective primer pairs

A rapid approach based on two-dimensional DNA gel electrophroesis (2-DGE) mapping with selective primer pairs was employed to analyze bacterial community structure in sediments from upstream, midstream and downstream of Sagami River in Japan. The 2-DGE maps indicated that Alpha- and Delta-proteobacteria were major bacterial populations in the upstream and midstream sediments. Further bacterial community structure analysis showed that richness proportion of Alpha- and Delta-proteobacterial groups reflected a trend toward decreasing from the upstream to downstream sediments. The biomass proportion of bacterial populations in the midstream sediment showed a significantly difference from that in the other sediments, suggesting that there may be an environmental pressure on the midstream bacterial community. Lorenz curves, together with Gini coefficients were successfully applied to the 2-DGE mapping data for resolving evenness of bacterial populations, and showed that the plotted curve from high-resolution 2-DGE mapping became less linear and more an exponential function than that of the 1-DGE methods such as chain length analysis and denaturing gradient gel electrophoresis, suggesting that the 2-DGE mapping may achieve a more detailed evaluation of bacterial community. In conclusion, the 2-DGE mapping combined with the selective primer pairs enables bacterial community structure analysis in river sediment and thus it can also monitor sediment pollution based on the change of bacterial community structure.     

Preparation, Characterization and Application of Leather Particulate-Polymer Composites (LPPCs)

The present study describes the preparation and characterization of leather particulate-polymer composites (LPPCs) from solid wastes (chrome shavings/buffing dusts) generated during leather manufacturing processes. Nitrile butadiene rubber (NBR), Styrene butadiene rubber (SBR) and neoprene rubber were the polymers used at different concentrations. Pretreatment of leather wastes with suitable alkaline reagents enhances the binding efficiency with polymers chosen and the high interfacial bonding prevailing reduces the chromium leaching. Mechanical properties of the resultant polymer composites showed good machinable and nailing properties. Addition of poly vinyl chloride (PVC) further enhances the above said properties. Scanning electron micrograph analyses implies complete blending of components in LPPCs. The composites exhibit good machinable and nailing properties and are easily transformed to shoe heel, shoe sole and shoe last.     

Chlorinated pesticide residues in surface sediments from the River Kaveri, south India

Chlorinated compounds have preferential attraction for organic phases found in sediments. Usage of chlorinated pesticides in agriculture and vector control is more in developing countries. The residue levels of HCH isomers, and DDT, and its metabolites were quantified in surface sediments from the River kaveri and Coleroon in Tamil Nadu state, South India. The concentration of HCH ranged from 4.35 to 158.4 ng g-1 (dry wt.). Among the isomers of HCH, alpha-HCH is predominant followed by beta and gamma-HCH. The levels of DDT varied from 0.69 to 4.85 ng g-1 (dry wt.). Among the DDT compounds, p,p'-DDE quantified more (> 40%) in all the sites. This suggests that p,p'-DDE is a major breakdown (dehydrochlorination) product of DDT in the sediment compartment. Higher concentration of HCH residues reveals its large usage in agriculture. The flux of pesticide residues from land to river including downward flux to sediment is less.     

The effect of entrapped nonaqueous phase liquids on tracer transport in heterogeneous porous media: laboratory experiments at the intermediate scale

This work considers the applicability of conservative tracers for detecting high-saturation nonaqueous-phase liquid (NAPL) entrapment in heterogeneous systems. For this purpose, a series of experiments and simulations was performed using a two-dimensional heterogeneous system (10x1.2 m), which represents an intermediate scale between laboratory and field scales. Tracer tests performed prior to injecting the NAPL provide the baseline response of the heterogeneous porous medium. Two NAPL spill experiments were performed and the entrapped-NAPL saturation distribution measured in detail using a gamma-ray attenuation system. Tracer tests following each of the NAPL spills produced breakthrough curves (BTCs) reflecting the impact of entrapped NAPL on conservative transport. To evaluate significance, the impact of NAPL entrapment on the conservative-tracer breakthrough curves was compared to simulated breakthrough curve variability for different realizations of the heterogeneous distribution. Analysis of the results reveals that the NAPL entrapment has a significant impact on the temporal moments of conservative-tracer breakthrough curves.     

Pesticide Residues in Water From River Kaveri,South India

The residue levels of presistent chlorinated pesticides such as HCH (hexachlorocyclo-hexane) isomers and DDT (dichlorodiphenyl trichloroethane) compounds were quantified in water samples collected from the River Kaveri and its distributor River Coleroon in Tamil Nadu, South India. HCH showed higher levels in River Kaveri during premonsoon (July to September) and monsoon (October to December) months, reflecting the HCH usage during that season for paddy crops. But in the case of DDT no clear trend in residue level was observed. the α-HCH was detected as the dominant isomer in all the three sampling sites. Among DDT compounds, p,p'-DDT and p,p'-DDE showed higher percentage of the total. International comparison of residue levels revealed that the present values are comparable to the waters from Asian and South East Asian nations, but lower than some samples from other parts of India. the value of DDT is well below the EEC's maximum acceptable concentration for surface waters and lower than the recommended limit of 2000ng 1^-1 in USA water for protection of aquatic life (Water Quality Criteria, 1972).     

Synthesis and evaluation of antioxidant activities of some indole-2,3-dione derivatives and analogs

In the present study, a series of novel Schiff bases of isatin were synthesized by condensation of imesatin with different aromatic aldehydes. The imesatins were synthesized by reaction of isatin with p-phenylenediamine. The chemical structures of the synthesized compounds were confirmed by means of IR, 1H-NMR, 13C-NMR, mass spectroscopy, and elemental analysis. These compounds were screened for antioxidant activity by DPPH, nitric oxide and hydrogen peroxide radical scavenging activity. In all the methods, the compound 3-(4-(3,4,5-trimethoxy benzylideneamino)phenylimino) indoline-2-one (5d) showed highest antioxidant activity because of the presence of electron donating groups and the compound 3-(4-(4-nitrobenzylideneamino)phenylimino) indoline-2-one (5f) showed the least activity because of the presence of an electron withdrawing group.