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  • Author or Editor: H. Singh x
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Geophysical data are specific physical responses of geological formations distributed over an area. These data are normally the physical parameters such as density, velocity, resistivity, susceptibility etc. of geological sources and hence bring a pattern of geological structures. It is conceived accordingly that this pattern recognition of such geophysical data will throw light on the spatial distribution and physical attributes of their geological sources. The well logging method considered as one of the geophysical method for the exploration of hydrocarbon, coal and base-metals, also has a strong role in finding the location and evaluation of geological resources.A novel approach known as Adaptive Neurofuzzy Inference System technique (ANFIS) is made to identify stratigraphy of Prydz Bay basin, east Antarctica. A geological stratum in terms of 1D model is made using datasets obtained from this area. The 1D model deduced as an ANFIS result is able to make geological sense of even additional thin sand sandwiched between clayey silt strata seams which unable to be resolved by other conventional methods. The analysed ANFIS results deduced to map horizons for hydrocarbon prospecting is verified with known coring datasets. These results are encouraging and provide stable and consistent solutions.

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Cololejeunea chenii Tixier, is reported for the first time from India. A detailed taxonomic description along with line drawing plate is provided for its easy identification.

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Abstract  

The etching and annealing behaviour of heavy ion nuclear tracks have been studied in glass detectors namely sodalime, phosphate and quartz using optical absorption spectroscopy. All these glass detectors were exposed at 90° and 45° for different ions, with collimated beams of varying energies. The absorption difference spectrum was employed to describe the annealing kinetics. A mathematical relation proposed in our laboratory was used to explain the annealing behaviour of radiation damage due to heavy ion beams in glass detectors. The activation energy was obtained from a new formulation and is found to be 0.16 eV in sodalime, 0.56 eV for phosphate and 0.69 eV for quartz glass detectors.

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Abstract  

The extraction behavior of uranium (VI) from chloride medium with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in dodecane has been investigated under wide range of conditions. Attempts have been made to establish the extraction mechanism of uranium(VI) with PC-88A. Treatment of the distribution data by slope analysis technique showed the formation of a monomeric complex of the nature [UO2(A2H)2]. Formation of this species was also confirmed by non-linear least square regression of the distribution data to the mathematical expression correlating percentage extraction and acidity. In this investigation attempts have also been made to develop a mathematical model for the system (UO2Cl2-HCl-H2O-PC-88A-dodecane) using experimental data on the distribution of uranium against initial aqueous acidity at different initial metal concentration. The mathematical model D = 37.547±0.223/C i 1/2×[H i]2 can be used to predict the concentration of uranium in organic as well as in aqueous phases at any initial concentration of uranium [C i] and initial hydrogen ion concentration [H i]. The extraction constant (K ex) has been calculated.

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The CERES-rice model (version 4.0) was calibrated and validated using the data from a field experiment carried out during the rainy season of 2004 and 2005 at Shalimar, Srinagar (35° 5′ N latitude and 74° 89′ E longitude, 1587 m above the mean sea level, India. The experiment included six rice cultivars each transplanted on 25 May, 10 June and 25 June. Data of 25 May transplanting was used for model calibration and development of the genetic coefficients of the rice cultivars. The predicted and observed dates of phenological events were in close agreement with root mean square error (RMSE), mean absolute error (MAE) and D-index of 5.0 days, 4.3 days and 0.91, respectively, for anthesis and 3.7 days, 3.1 days and 0.91, respectively, for physiological maturity of the crop. The predicted and observed grain yields were also very close with a RMSE of 0.63 Mg ha −1 , MAE of 0.58 Mg ha −1 and D-index of 0.89, respectively. Corresponding values for above ground biomass was 1.17 Mg ha −1 , 1.01 Mg ha −1 and 0.82. Sensitivity test showed that simulated yield responded to temperature and atmospheric CO 2 concentration. Nitrogen 240 kg ha −1 at 25 May transplanting, recorded highest simulated grain yield (9.71 Mg ha −1 ). Further, 3 seedlings hill −1 produced highest simulated grain yield. The results suggest that the model can be applied in the temperate Kashmir to estimate crop productivity and optimize the management practices.

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Time dependent seismicity investigation in six seismogenic sources of Nepal and its adjoining areas in the Central Himalaya reveal that there is intermediate time clustering of the moderate size shallow earthquake in each seismogenic source. The inter-event times, between the successive shallow mainshocks, of the magnitude equal to or larger than certain cut-off magnitudes for each of these sources are used for long-term earthquake hazard prediction corresponding to individual sources of the region. For the hazard estimation, the following relations have been established here as: log T t = 0.46 M min +0.07 M p +0.02 log m 0 −2.38, and M f = 0.78 M min −0.25 M p −0.04 log m 0 + 4.32, where T t is the inter-event time measured in years; M min is the moment magnitude of the smallest mainshock considered; M p is the magnitude of preceding main shock, M f is the magnitude of the following mainshock and m 0 is the moment rate in each source per year. The value of σ = 0.22 and multi-correlation coefficient, R = 0.62 for the first equation and σ = 0.30 and R = 0.59 for the second equation are estimated.Based on these relations and using the magnitude and time of occurrence of the last main shocks in each seismogenic source, time dependent conditional probabilities of the next shallow main shocks during the next 10, 20 and 30 years as well as the magnitude of the expected main shocks are forecast.

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Seismically Kutch peninsula is very active. The distribution of seismicity in Peninsular Shield region from 1902 to 2001 show 12 earthquakes of M ≥ 6. The energy ratio from Kutch basin to Deccan trap is 20:1 and from trap to rest of the shield is 5:1. The last one hundred years seismicity data show Kutch basin is seismically more active than Deccan trap and the rest of the Peninsular Shield. The maximum magnitude of earthquake in the Kutch region is 7.7. The generations of large earthquakes in the region are difficult to explain, as plate boundary does not exist. In order to understand the physical processes that are taking place in the region to generate such large events the detailed analyses of geophysical and geological data have been examined in the light of development of rift, subsidence of basin, vertical tectonics and recent geophysical findings. In such regions, petrologic model can provide better explanation for release of fluid that generates large earthquakes, sprouting of sands, liquefaction, and large number of aftershocks activities and direction of stresses for aftershock sequences. The presence of magma in the Kutch upper mantle could be derived from various geological (subsidence of basin, development of rift faults) and geophysical observations (high heat flow over Cambay region, prominent positive Bouguer gravity anomalies and low shear velocity in the upper mantle). The inspection of seismological data shows all the medium size to large earthquake have occurred in shear zone of large gravity gradients or along the four major faults of the region. In view of geological and geophysical observations, petrologic model is proposed for generation of earthquakes in the region. The number of aftershocks and direction of stresses in the focal region of aftershocks would depend on the direction of movement of fluid incursion in the focal region after the occurrence of the main events. The recent Bhuj earthquake also shows more than 3000 aftershocks from Jan 29 to April 15, 2001. The expanding swarm activity in the focal region and the direction of stresses derived from first motion data of aftershocks for focal depths 2 to 8 km, 8 to 25 km, and 25 to 38 km supports the proposed model. Also, shear wave tomography studies in this region have revealed low shear wave velocity in the upper mantle of Cambay from shallow depth to 200 km depth showing high temperature zone. The analyses reveal the presence of conducting fluid in the focal zone, which is the main cause for generation of medium size to large earthquake in the region.

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Movement and abstraction of groundwater in the geological formations are dependent on the hydro-geological parameters of the aquifers. The purpose of any aquifer test is to determine the hydro-geological parameters. Among the basic parameters are the specific storage, permeability and leakage coefficients. The hydro-geological parameters are hidden in the field test data and their identification is possible using the available physically plausible models suitable for the prevailing field circumstances. In this context, a generalized theoretical solution for the effect of partial penetration superimposed over the full penetration on draw-down in a large-diameter well in artesian aquifer discharging at a constant rate has been presented for non-dimensional quantities describing the variable geometries of wells. The well-function curves are developed by varying the percentage amount of drilling and the percentage amount of casing lowered which then control to vary the percentage amount of open-hole or screened interval for the three categories: when the diameter of the cased interval in which the water level changes is greater than, equal to, and less than the diameter of the open interval. The skin effect and the effect of leakage are neglected. A comparison of results with the published works has also been presented. The present study is useful in such areas where wells are located either in harder or in collapsible loose formations; and a decision is required that, at the planning, construction, or development stage, as to what extent the amount of drilling be reduced, and/or an additional amount of casing be lowered within the aquifer. Also this reduces the cost of well construction and development in a specific situation.

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The outcome of various solvent extraction (water, methanol, acidic 50% methanol, 70% acetone, acidic 50% methanol followed by 70% acetone) on the total phenolic content (TPC) and antioxidant capacity of fruit pulp, seeds, leaves and stem bark of seabuckthorn (Hippophae rhamnoides L.) was investigated. The seabuckthorn extracts possess high phenolic content, 1666–13769 mg GAE/100 g d.w. The mean TPC was found highest in seeds (11148) followed by stem bark (10469), leaves (6330) and pulp (3579 mg GAE/100 g d.w.). In general, the 70% acetone and acidic 50% methanol followed by 70% acetone extracts was found to contain significantly higher TPC than those obtained in other extracting solvents. Antioxidant capacity in terms of IC50 value of pulp (3.39 mg ml−1) was up to 7.8 times higher than those reported for stem bark (0.43 mg ml−1) and up to 2.4 times higher than those found in seeds (1.4 mg ml−1). Further, antioxidant capacity by FRAP assay showed that the stem bark possess maximum antioxidant capacity (16.83) followed by seeds (15.26), leaves (12.73) and pulp (12.61), all as mM FeSO4. Significant correlation was found between TPC and antioxidant capacity by DPPH and FRAP assays.

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