Optical and Structural Characteristics of Glancing Angle Deposition Synthesized Er2O3 Nanowires.

The Er2O3 nanowires (NWs) were synthesized on Si substrate by using glancing angle deposition technique inside E-beam evaporator. The field-emission gun scanning electron microscopy (FEG-SEM) images showed perpendicular and highly porous Er2O3 NWs with average diameter ∼50 nm and length ∼350 nm. The crystallinity of the Er2O3 NWs improved with annealing but degraded at higher temperature annealing at 900 °C. Transmission electron microscopy (TEM) images show the unsymmetrical NW growth and grain size enhancement with increasing annealing temperature. In addition, two-fold enhanced absorption was observed for as deposited as compared to the annealed samples. A low intense photoluminescence was obtained for the as deposited sample as compared to the annealed samples due to the presence of defects and dangling bonds. The as deposited Er2O3 NW also showed a hydrophobic surface property with a contact angle of as high as 107.4° due to the air trapped in between Er2O3 NWs and oxygen vacancies which turned to hydrophilic surface with contact angle 27° and 25° when annealed at higher temperature of 750 °C and 900 °C respectively.

Carbon density and accumulation in agroecosystem of Indo-Gangetic Plains and Vindhyan highlands, India.

In agroecosystems, the annual carbon (C) inputs to soil are one of the most promising greenhouse gas mitigation options. Net primary productivity (NPP) provides the inputs of C in ecosystems that can potentially be sequestered in soil organic matter. In this study, we estimates the C density and accumulation rate in rice-wheat agroecosystem at four sites of Indo-Gangetic Plains and Vindhyan highlands through amalgamation of ground truth (GT) and remote sensing (RS) approach. In addition to this, we validated field-measured aboveground net production (ANP) with remotely sensed SPOT-Vegetation data. ANP of the sites ranged from 6.8 to 11.1 and 3.3 to 8.8 t-C ha(-1) year(-1) for GT and RS, respectively. Both estimates (GT and RS) were linearly and significantly related with each other (y = 1.33x - 5.82, R (2) = 0.93, P = 0.04; where x = GT ANP and y = RS ANP). For the whole region, total NPP (rice + wheat) was ranged from 7.9 to 12.5 t-C ha(-1) year(-1). The C accumulation potential of the present agroecosystems was 9.1 and 1.9 t-C ha(-1) year(-1) in the form of ANP and belowground NPP (BNP), respectively. The aboveground C stock of agroecosystem allocated in foliage (7.8 %), stem (57.6 %), and grain (35.1 %). Survey about the fate of post-harvested materials indicated that aboveground portion of the crop is almost used completely within the year for different purposes including human consumption and cattle feeding. Therefore, only BNP and litter contribute to long-term C sequestration. Since agroecosystem has enormous potential to sequester C, better management of aboveground portion NPP of the crop may enhance C sequestration potential of agroecosystem.

Spectral modelling near the 1.6 µm window for satellite based estimation of CO2.

Measurements of inter annual CO2 variability are important inputs for modelling global carbon cycle. Satellite observations play important role in quantification and modelling of CO2 fluxes in the atmosphere, where observed radiances in narrow spectral channels are used to estimate the trace gas concentration using spectroscopic principles. The 1.6 µm spectral window is important for CO2 detection and study of the two CO2 bands in this region is performed at different spectral resolutions. In order to select the optimum spectral resolution and wavelength positions, suitable for CO2 estimation from satellite platform, sensitivities of different spectral lines to changes in CO2 concentration are studied. Analysis is carried out using a line by line FASCOD radiative transfer model in tropical atmospheric and rural aerosol conditions. The CO2 concentration is varied from 200 to 1000 ppmv and spectral resolution is varied from 0.025 nm to 10 nm. It is observed that atmospheric transmittances reduce sharply with increase in CO2 concentration. With decrease in resolution initially the sensitivity steeply reduces but at resolutions lower than 0.15 nm the sensitivity remains nearly constant. The Continuum Interpolated Band Ratio method is used for inverse concentration retrieval. Based on the study it is evaluated that 0.2 nm is the optimum limit for resolution.

A new technique for localization of cellulase in situ using silver nitrate.

A new staining technique has been developed for the histochemical localization of cellulase in plant tissues by light microscopy. The products of cellulolysis are reducing sugars which can reduce the salts of heavy metals under appropriate conditions. The present technique relies on the deposition of black silver oxide due to reduction of alkaline silver nitrate to detect cellulase in tissues.