Dharmveer Singh

Assessment of river water quality and ecological diversity through multivariate statistical techniques, and earth observation dataset of rivers Ghaghara and Gandak, India

ABSTRACT Water quality and ecological diversity of aquatic flora with respect to distribution in active channels and on banks of the rivers Ghaghara and Gandak have been investigated in years 2011–2012. The land use/land cover map of year 2010 showed agricultural land as the dominant class in both river basins. The appraisal of aquatic flora has indicated that the dominant plant species in numbers are as follows: macrophytic algae, aquatic angiosperms, aquatic pteridophytes, sedges, grasses, herbs, shrubs, climbers and trees collected from the banks and active channels of rivers Ghaghara and Gandak. In total, 207 plants species were reported as common in both river environments, and the remaining species have showed variability for both rivers. It was observed that the algal group showed higher species diversity in comparison to other plant groups. High numbers of macrophytic species were observed due to the alkaline pH and good level of dissolved oxygen at different sampling sites of the two rivers. Further, multivariate statistical techniques such as cluster analysis and principal component/factor analysis were applied to fulfil the knowledge gap and to identify the potential sources and types of pollutants.

Valine-Coated Magnetic Nanoparticles: Synthesis, Characterization, and Application in Removal of Cd(II) Ions from Aqueous Solution

A novel Valine coated magnetic nano-particles (MNPs-Val) has been synthesized for the removal of Cd(II) ions from aqueous solution. The MNPs-Val were developed by electrostatic attraction of valine (C5H11NO2) on the bare surface of Fe3O4 nanoparticles and characterized by using FT-IR, XRD, SEM, and TEM analysis. The morphology and average particles size 15-27 nm of MNPs-Val were analyzed by SEM and TEM. The coated MNPs were applied for adsorptive removal of Cd(II) ions from aqueous solutions. Factors affecting the adsorption of Cd(II) ions on the MNPs-Val surface such as the pH, temperature, adsorbent dosage, and contact time were investigated which have significant effect on the metal ion removal. The Cd(II) ions adsorption equilibrium on the MNPs-Val could be achieved in 35 min at the optimized pH 5 and follow the pseudo-second order kinetics model. The experimental data for the adsorption of Cd(II) was followed by the Langmuir isotherm and the maximum adsorption capacity was obtained at 0.2 g L−1 adsorbent dose at 308 K.

Design and Fabrication of a High-Voltage Thyristor

An economical, simple and reproducible process has been developed for the fabrication of high-voltage silicon thyristors. The process employs three masks for the fabrication cycle. Mesa technique is employed for pellet separation and for obtaining high-breakdown voltages. In this structure, the forward-blocking junction is positively beveled and the reverse-blocking junction is negatively beveled. The gate-cathode junction is the conventional mesa junction. For metallization, a soft solder is used. The solder itself serves as the mask for the silicon etchant.