Rattan Singh

Disorder induced semiconductor to metal transition and modifications of grain boundaries in nanocrystalline zinc oxide thin film

This paper report on the disorder induced semiconductor to metal transition (SMT) and modifications of grain boundaries in nanocrystalline zinc oxide thin film. Disorder is induced using energetic ion irradiation. It eliminates the possibility of impurities induced transition. However, it is revealed that some critical concentration of defects is needed for inducing such kind of SMT at certain critical temperature. Above room temperature, the current-voltage characteristics in reverse bias attributes some interesting phenomenon, such as electric field induced charge transfer, charge trapping, and diffusion of defects. The transition is explained by the defects induced disorder and strain in ZnO crystallites created by high density of electronic excitations.

Phosphorus Nutrition and Nitrogen Assimilation in Chickpea (Cicer arietinum L.)

Summary Assimilation of nitrogen and phosphorus was studied in chickpea ( Cicer arietinum L. cv. GL-769) plants grown in pots under different P levels: Control (P 0 ), 7.5 μg Pg -1 soil (P 1 ) and 15.0 μg Pg -1 soil (P 2 ). Both P 1 and P 2 levels increased nodule nitrate reductase (NR) activity per plant and leaf NR activities at 51 (pre-flowering) days after sowing (DAS). At 88 DAS (flowering stage), nitrogenase (N 2 ase) and nodule acid phosphatase (APase) activities were stimulated by P application while NR activity decreased in the leaves. Root P and leaf P increased due to P 1 and P 2 levels at 71 DAS while only root P increased at 88 DAS. At 106 DAS (post-flowering stage), both P levels increased leaf NR activity and the concentrations of total N, chlorophyll (Chl) and sugars in leaves, suggesting improved translocation of reduced N from leaves to pods, which is needed for protein synthesis at this stage.

Phosphorus assimilation i mycorrhizal moong (Vigna radiata L.) plants under different phosphorus levels

Abstract Influence of phosphorus on its assimilation was studied in a pot experiment at two growth stages at different phosphorous (P) levels control (P 0 ), 10 μg P g −1 soil (P 10 ) and 20 μg P g −1 soil (P 20 ) in non-mycorrhizal (NM) and mycorrhizal (M) moong plants. The response of M plants to P application varied both with growth stage and P level. In NM plants, total P, shoot fresh weight (FW) and exopoly-phosphatase (ExoPase) activity in roots was enhanced with both P levels while root peroxidase and acid phosphatase activities (APase) in leaves increased with P 20 level only. Ester P, root FW, inorganic phosphate (P i ) and APase activity in roots were not affected at P 10 level. Total P and P i in leaves were enhanced with MP 10 but were unaltered with MP 20 treatment at 38 days after sowing (DAS). ExoPase and peroxidase activities increased but total P in leaves decreased with MP 10 and MP 20 plants at 50 DAS. APase activity and ester P in leaves increased with MP 20 while Chl concentration decreased at 38 as well as 50 DAS. Soil available P increased with both levels in M plants but only with P 20 with NM plants. The comparison of M and NM plants showed that M plants had greater P i at both samplings whereas root total P and Chl only at 50 DAS at each P level. Shoot FW and root ExoPase activity were greater in M plants with P 0 and P 10 levels. NM plants accumulated ester P more in roots while M plants in leaves at 50 DAS.

High efficiency hybrid solid state blended dyes sensitized solar cell based on zinc oxide nanostructures

This paper reports on the development of high efficiency hybrid solid state blended dye sensitized solar cell (HssBDSSC) using ultrasonification process. Cell synthesized using conducting organic polymer as organic hole-transporting material together with BDs, while Poly (3-Octylthiopehene) (P3OT) and zinc oxide nanostructures (ns-ZnO) as electron-transporting material. BD is made in a composition, so that it can absorbed light in the entire visible region and provided the high electron injection. The HssBDSSC device structure such as indium tin oxide (ITO)/PEDOT:PSS/ns-ZnO+P3OT/BDs/Electrode is developed and an ultrathin layer of PEDOT:PSS is deposited on ITO for making Schottky contact. Device shows a very high conversion efficiency of 4.67%, Fill Factor (FF) 52.9%, open-circuit photo voltages 0.58 V and short-circuit photocurrents 15.1 mA/cm2 under 100 mW/cm2 visible band illumination. We propose an energy level alignment diagram to understand the photophysics of hybrid nanocomposites, which include ch...

Effect of seed encapsulation on the mobilization of the reserve material during germination in groundnut Arachis hypogea seeds

Abstract Encapsulation of groundnut seed with nitrocellulose (NC) or ethyl cellulose (EC) has some profound effects on the mobilization of reserve material during seed germination. Seed encapsulation, in general, increases lipase, α-amylase and invertase activity and decreases the protease activity as observed by low protein degradation during early stages of germination (0–9 days after sowing). Encapsulation with EC enhances the activity of isocitrate lyase and that with NC increased the rate of starch and lipid degradation and the transport of hydrolysate to the growing axis.