The activities of catalase, peroxidase, and polyphenoloxidase were studied in attached and detached rice (Oryza satva L. cv. Ratna) leaves. Catalase activity decreased while peroxidase and polyphenoloxidase activities increased during senescence of both attached and detached rice leaves. Kinetic (5 EAM) and benzimidazole (1 1M), which are known to delay the senescence of detached rice leaves, retarded the decrease of catalase activity during detached leaf senescence. On the other hand, these chemicals accelerated the increase of peroxidase and polyphenoloxidase activities over the water control. Total phenoUics accumulated in detached and darkened rice leaves, but in attached leaf senescence in light no accumulation of phenolics was observed.

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Our paper reviews the use of conductive polymer composite materials in various applications for semi conductive, static-dissipative, anti-corrosive, electromagnetic interference (EMI) shielding and stealth composite coatings. The composite consists of conductive fillers and the insulating polymer network. The composite becomes electrically conductive as the filler content exceeds a certain critical value, generally called as Percolation Threshold Value (PTV). The PTV for a particular polymer composite can be drastically reduced by using nano-sized conductive fillers. The higher the aspect ratio (length:width) of the nano-fillers, the lower is the concentration for achieving the PTV. Traditionally the metals, carbon-black particles and alloys have been used as electrically conductive fillers; however, very high level of these fillers can be detrimental for the process ability, surface quality of the material, density, the cost and mechanical properties of the composite. By the use of nano conductive fillers, good conductivity will be achieved while retaining the original properties. Recently, one and two dimensional nano-creatures based on carbon such as carbon nanotubes and graphene respectively have received significant attention, due to their outstanding thermal, electronic and mechanical properties. In this paper we have compared different conductive filler materials, their dispersion techniques, and compatibility in polymer matrix and suitability in various above mentioned applications. The proliferation of mobile towers and electronic devices in the world results in harmful EMI and radio frequency interference (RFI) ultimately causing operational malfunction to electronic devises and also harmful to living beings, signifies the importance of this detailed review for EMI/RFI shielding applications.