Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: V. Jha x
  • Refine by Access: All Content x
Clear All Modify Search

The formation and thermal behaviour of pyropolymers based on novolak resin synthesized under carefully controlled processing conditions have been studied by various thermoanalytical techniques. A suitable reaction scheme has been proposed for the formation of these pyropolymers. Only a small (3–8%) weight loss has been observed up to 800 °C in static air. DTA curves confirmed multistage exothermic processes predominantly due to two different linkages which control their thermo/thermo-oxidative stability. Hot metal filtration (≈700 °C) in an inert atmosphere exhibited only negligible weight loss.

Restricted access

Abstract  

In this study, an accurate faster gamma spectrometry method for measuring the low level activity concentrations of 137Cs using in situ pre-concentration technique on copper ferrocyanide cartridge was standardized. Due to unavailability of reference standard in the copper ferrocyanide matrix, efficiency calibration curves were plotted using RGU and RGTh reference standards. To harmonize the difference in density of standard and sample the required density correction factors for photo peak efficiency were generated. The in situ pre-concentration technique followed by gamma-ray spectrometry was applied for activity determination in surface seawater from eight locations in the coastal marine environment of Arabian Sea. The mean activity concentration of 137Cs ranged between 0.71 and 0.91 Bq/m3. Higher activity concentrations were observed at location with latitude, longitude of 21.6°N, 69.57°E as compared to concentration observed at location with latitude, longitude 16.98°N, 73.25°E. The observed concentrations were found to be in range of data reported in Asia–Pacific Marine radioactive database (ASPARMARD). The results will fill up the gaps in the existing database. The generated data will be useful for monitoring fresh input of anthropogenic radionuclide into coastal marine environment for post Fukushima environmental assessment.

Restricted access

Abstract  

An investigation on the distribution of radium activity levels in the entire south eastern coast of Tamil Nadu, India, from Chennai to Kanyakumari was carried out. Insitu preconcentration technique was adopted by passing 1,000 L of seawater through MnO2 impregnated cartridge filters at all the locations. In the coastal waters, 226Ra and 228Ra concentration was observed to be in the range of 1 to 1.81 and 3.1 to 7.5 mBq/L, respectively with an average of 1.52 and 4.53 mBq/L. respectively, while the sediment samples showed 226Ra activity levels from 8.1 to 129.0 Bq/kg and 228Ra varied from 14.7 to 430.01 Bq/kg. The Kd values for 226Ra was observed to be from 5.3E03 to 3.5E05 L/kg and for 228Ra it was in the range of 2.3E03 to 5.9E04. It was observed that the concentration of 228Ra was more than 226Ra in all the locations. The spatial distribution of the activity with respect to location is discussed in the paper. The radioactive database obtained, represents reference values for coastal environment of Tamil Nadu.

Restricted access

Hydroxycitric acid made the genus Garcinia economically important. Genetic and chemical diversity has been studied in Garcinia species using molecular markers, HCA and antioxidant activity. Nine species were collected and screened for molecular diversity and six were subjected to analyse antioxidant and HCA content and its interspecies variability. A total of 129, 125 and 89 bands with polymorphism of 78.74%, 78.4% and 93.36% were obtained using ISSR, RAPD and EST-SSR, respectively. The average PIC value obtained with ISSR, RAPD and EST-SSR markers was 0.9161, 0.9440 and 0.8903, respectively. Determined HCA content by HILIC-HPLC system using 0.1% orthophosphoric acid and acetonitrile (30:70) as mobile phase in fruit powder of various Garcinia species was found to be significantly different. G. gummi-gutta, G. indica and G. xanthochymus are rich of HCA containing 12.44±1.04%, 7.92±0.83% and 6.3±0.286%, respectively. G. morella, G. talbotii and G. celebica contained very negligible amount of HCA, 0.023±0.012%, 0.083±0.034% and 0.34±0.013%, correspondingly. G. talbotii showed high antioxidant capacity (95.40±0.720). Below that G. indica and G. xanthochymus were showing significant amount of total phenols (1.23±0.015 and 1.07±0.008), flavonoids (11.17±0.075 and 12.35±0.219) and antioxidant activity (90.73±0.976 and 91.37±0.854). Correlation analysis found significant association between molecular and chemical variation indicating influence of genetic background on the observed HCA and antioxidant profiles. The conducted analysis showed the most distinct species at the genetic and chemical levels were G. gummi-gutta, G. indica and G. xanthochymus. This study signifies the utility of molecular and chemical fingerprints for commercial exploitation of HCA from Garcinia species.

Restricted access
Cereal Research Communications
Authors: N. Jain, G.P. Singh, R. Yadav, R. Pandey, P. Ramya, M.B. Shine, V.C. Pandey, N. Rai, J. Jha, and K.V. Prabhu

Under limiting water resources, root system response of genotypes to soil-water conditions with enhanced shoot biomass holds the key for development of improved genotypes. Based on the hypothesis of root biomass contribution to higher yields under limiting conditions which might be attributed to the root system plasticity of genotypes, a set of thirty-four genotypes were evaluated under three moisture regimes in a pot experiment for root system traits. Total root dry matter had a positive association with total shoot dry matter (0.35). The identified genotypes showed greater yields and higher stress tolerance index (STI) in an independent field experiment. Root dry matter positively correlated with stress tolerance index on grain yields in both the years. The total variation was partitioned into principal components and GGE biplots were studied to identify the best performing genotypes under the three environments for root dry biomass and related traits. HD2932 appeared to be the winner genotype under different regimes. These results might be helpful in identifying donors for moisture stress tolerance that can be utilized in wheat breeding programmes for accelerated development of varieties with improved root systems.

Restricted access