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Ganguly A.,National Institute of Technology Agartala | Mondal A.,National Institute of Technology Agartala | Dhar J.C.,National Institute of Technology Agartala | Singh N.K.,National Institute of Technology Agartala | Choudhury S.,North East Hill University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2013

Well patterned Ag nanoparticle (NP) arrays were fabricated on TiO 2 thin film (TF). Scanning electron microscopy shows Ag NPs distribution on the TiO2 TF surface. The overall Raman scattering intensity increased for the Ag/TiO2 TF system. The enhanced Raman scattering of Ag/TiO2 TF was due to the formation of strong electromagnetic field around the Ag NPs under photon excitation. Optical absorption measurement shows three times enhancement in visible light absorption for the Ag NPs containing samples as compared to bare TiO2 TF. The photoluminescence emission intensity from the Ag NPs/TiO2 TF sample reduced due to the formation of Ag-O complex on the TiO2 surface. © 2013 Elsevier B.V. All rights reserved.

Roy P.S.,University of Hyderabad | Behera M.D.,Indian Institute of Technology Kharagpur | Murthy M.S.R.,International Center for Integrated Mountain Development | Roy A.,International Center for Integrated Mountain Development | And 94 more authors.
International Journal of Applied Earth Observation and Geoinformation | Year: 2015

A seamless vegetation type map of India (scale 1: 50,000) prepared using medium-resolution IRS LISS-III images is presented. The map was created using an on-screen visual interpretation technique and has an accuracy of 90%, as assessed using 15,565 ground control points. India has hitherto been using potential vegetation/forest type map prepared by Champion and Seth in 1968. We characterized and mapped further the vegetation type distribution in the country in terms of occurrence and distribution, area occupancy, percentage of protected area (PA) covered by each vegetation type, range of elevation, mean annual temperature and precipitation over the past 100 years. A remote sensing-amenable hierarchical classification scheme that accommodates natural and semi-natural systems was conceptualized, and the natural vegetation was classified into forests, scrub/shrub lands and grasslands on the basis of extent of vegetation cover. We discuss the distribution and potential utility of the vegetation type map in a broad range of ecological, climatic and conservation applications from global, national and local perspectives. Weused 15,565 ground control points to assess the accuracy of products available globally (i.e., GlobCover, Holdridge's life zone map and potential natural vegetation (PNV) maps). Hence we recommend that the map prepared herein be used widely. This vegetation type map is the most comprehensive one developed for India so far. It was prepared using 23.5m seasonal satellite remote sensing data, field samples and information relating to the biogeography, climate and soil. The digital map is now available through a web portal (http://bis.iirs.gov.in). © 2015 Elsevier B.V.

Singh M.,Indian Institute of Technology Guwahati | Roy B.,North East Hill University | Tandon V.,North East Hill University | Chaturvedi R.,Indian Institute of Technology Guwahati
Plant Biosystems | Year: 2014

This study reports the antioxidant and anthelmintic activities of Spilanthes cell cultures. Murashige and Skoog medium supplemented with 5.0 μM N6-benzylaminopurine, 1.0 μM 2,4-dichlorophenoxyacetic acid and 1.0 μM α-naphthaleneacetic acid was found to be the best medium to induce dedifferentiation from the leaf cells and for further maintenance of the callus cultures. These cell cultures and in vivo leaves were subjected to solvent extraction by hexane, ethyl acetate, methanol and water, and their extraction yield and total phenolic contents were evaluated. The antioxidant activity of extracts was determined by using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay. The methanol extracts of in vitro callus and in vivo leaf showed an apparent antioxidant activity and their IC50 values were 1342.9 and 1085.1 μg/ml, respectively. The anthelmintic efficacy of the extracts was also tested using live trematode (fluke) parasites of cattle as the model test material. The aqueous extract of dedifferentiated callus showed a strong anthelmintic activity, which was higher than the activity of the water extract of the field-grown plant. The results of this study verify the potential of Spilanthes as a reservoir of bioactive agents and also substantiate the value of callus cultures as a new source of anthelmintic and antioxidant compounds. © 2013 © 2013 Società Botanica Italiana.

Adhikari S.,National Institute of Technology Durgapur | Rakshit I.,National Institute of Technology Durgapur | Pal M.,NFET | Sarkar P.,North East Hill University | Ghatak R.,National Institute of Technology Durgapur
CODEC 2012 - 5th International Conference on Computers and Devices for Communication | Year: 2012

In this paper a UWB band pass filter using multiple mode resonator (MMR) with a notch band is reported. The MMR is realized by loading an open stub at the center of a uniform impedance resonator. Two modes are located within UWB passband to achieve UWB band pass response. The resonator is coupled via input output feed line through interdigital coupled line with a high degree of coupling. In order to incorporate a notch band in UWB passband one arm of the interdigital coupled line is extended in outward direction. Out of phase cancellation model is implemented for notch band insertion at 6.8 GHz RFID frequency. The proposed UWB band pass filter is simulated and tuned to improve in band, out of band performance and also the notch characteristics. © 2012 IEEE.

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