Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: B. R. Arora x
  • Refine by Access: All Content x
Clear All Modify Search

Reaction between two oxides leading to the formation of a new compound through a change in weight can be studied by TG methods. However, for catalyst preparations, in most of the cases the starting materials are not oxides. The more common methods of coprecipitation or kneading of the precipitated oxides are employed. In such cases the TG and DTG curve of the composites are of a complex nature for several possible reasons including the formation of new compounds. The interpretation of the conventional DTG curve of such a sample and identification of temperature regions for any new thermal activity thus presents problems. For such studies the use of a derived derivative thermogravimetric curve is suggested as described in this paper. This curve indicates the differences between the experimental thermal behaviour of the composite vis-a-vis theoretical thermal behaviour of the composite computed from the thermal behaviour of its constituents. The regions of a new thermal activity can be readily located and interpretated. Two systems are described, MgO-Cr2O3 and MgO-Fe2O3.

Restricted access

The hydrated oxides which are formed by the addition of ammonium bi-carbonate to a solution of Zn(NO3)2 and Fe(NO3)3, and drying the precipitates at 110° are zinc hydroxy carbonate(I) and iron(III) oxide gel(II), respectively. A new, derived derivative thermogravimetric curve along with conventional DTA and DTG methods have been used to study the reaction between (I) and (II) in two components system.

Restricted access
Cereal Research Communications
Authors: S. Gupta, R. Yadav, K.B. Gaikwad, A. Arora, A. Kumar, A. Kushwah, and N.K. Bainsla

Physiological breeding complementing the conventional approach is increasingly being explored in wheat in view of stagnating annual genetic yield gain. Designing improved plant types required knowledge about physiological traits associated with yield gain in the past. Fourteen wheat varieties including 12 historically important and popular (mega) wheat cultivars and two recently registered varieties were observed for various physiological traits for two years. Both breeding period and genotypes within breeding period accounted for significant differences for most of the physiological traits. Regression analysis indicated curvilinear trend for leaf area index (LAI), flag leaf area, and root length and root weight. Near perfect leaf area index (LAI 5.94) with semi-erect leaves and higher flag leaf area was observed in all time mega variety HD 2967 indicated the importance of plant architecture and crop canopy in yield maximization. Linear declining trend was observed for coleoptile length, number of stomata per cm2 and flag leaf length. Increasing trend for total chlorophyll content and normalized difference for vegetative indices (NDVI) at both vegetative and flowering stage indicated the importance of leaf greenness in yield improvement. Root length has continuously declined except for the latest released varieties, however no such trend was observed for root weight. We propose that grain yield stabilization at still higher level can be achieved by increasing photosynthetic capacity, optimizing the crop canopy slightly less than the optimum, and better partitioning to grain yield through directed physiological based breeding.

Restricted access

Abstract  

This paper presents the results of measurement of natural and fallout radioactivity in soil samples of Chamba and Dharamshala areas in Himachal Pradesh, India. Spatial distribution of 238U, 226Ra, 232Th, 40K, 137Cs was determined using High resolution gamma-ray spectrometry. The mean activity concentration in Chamba region due to 238U, 232Th, 40K and 137Cs was 32.3, 58.4, 588.3, and 10.9 Bq kg−1, respectively, whereas in Dharamshala it was 35.7, 61.3, 594.9, 10.0 Bq kg−1, respectively. Absorbed gamma dose rate (D) in air was calculated using appropriate dose conversion factors, which was varying from 45 to 103 nGy h−1. To control the radiation exposure due to natural radioactivity in soil, if it is used as building materials, radium equivalent activity (Raeq) and activity index were also evaluated. Radium equivalent activity calculated for the soil ranged from 95.5 to 234.2 Bq kg−1 with average of 171.0 Bq kg−1.The calculated Activity concentration index was ranged from 0.34 to 0.85 with an average value of 0.64. The natural and fallout radioactivity in soil of this region is comparable with Indian average and other parts of the world. The percentage contribution of 238U, 232Th and 40K and 137Cs to the average external gamma dose rate was 22, 46, 32, 2%, respectively. This shows that the dose contribution due to fallout radioactivity is negligible as compared to the natural radioactivity.

Restricted access

Abstract  

This study presents the high purity germanium (HPGe) gamma spectrometric measurement of natural radioactivity mainly due to 226Ra, 232Th and 40K in soil samples collected in Ferozepur and Faridkot district of Punjab, India. 226Ra activity varied from 28.6 to 51.1 Bq kg−1 with the mean of 39.7 Bq kg−1. The range and mean activity of 232Th were 42.9–73.2 and 58.2 Bq kg−1, respectively. 40K activity was in the range of 470.9–754.9 Bq kg−1 with the mean of 595.2 Bq kg−1. The air kerma rate (AKR) at 1 m height from the ground was also measured using gamma survey meter in all the sampling locations, which was ranging from 92.1 to 122.8 nGy h−1 with the mean of 110.6 nGy h−1. The radiological parameters such as Raeq and activity index of the soil samples were also evaluated, which are the tools to assess the external radiation hazard due to building materials. The mean and range of the Raeq values were 168.7 and 132.9–210.4 Bq kg−1, respectively, whereas the activity index varied from 0.5 to 0.8 with the mean value of 0.62. These indices show that the indoor external dose due to natural radioactivity in the soil used for the construction will not exceed the dose criteria. The AKR was also evaluated from soil activity concentration and altitude correction of cosmic radiation contribution. The statistical tests such as Pearson correlation, spearman rank correlation, box and whisker plot, the Wilcoxon/Mann–Whitney test and chi-square test, were used to compare the measured AKR with evaluated AKR, which indicates good correlation.

Restricted access