A study on soil physico-chemical, microbial and metal content in Sukinda chromite mine of Odisha, India   总被引：1，自引：1，他引：0  

S. Das  S. S. Ram  H. K. Sahu  D. S. Rao  A. Chakraborty  M. Sudarshan  H. N. Thatoi 《Environmental Earth Sciences》2013,69(8):2487-2497

Soil samples from chromite mining site and its adjacent overburden dumps and fallow land of Sukinda, Odisha, were analysed for their physico-chemical, microbial and metal contents. Chromite mine soils were heterogenous mixture of clay, mud, minerals and rocks. The pH of the soils ranges between 5.87 and 7.36. The nutrient contents of the mine soils (N, P, K and organic C) were found to be extremely low. Analysis of chromite mine soils revealed accumulation of a number of metals in high concentrations (Fe > Cr > Mn > Ni > Zn > Pb > Sr) which exceeded ecotoxicological limits in soil. Correlation and cluster analysis of metals revealed a strong relation between Cr, Ni, Fe, Mn among the different attributes studied. Assessment of different microbial groups such as fungi, actinomycetes and bacteria (heterotrophic, spore forming, free-living nitrogen fixing, phosphate solubilising and cellulose degrading) from mine soils were found to be either extremely low or absent in some soil samples. Further chromium tolerant bacteria (CTB) were isolated using 100 mg/L Cr(VI) enriched nutrient agar medium and were screened for their tolerance towards increasing concentrations of hexavalent chromium and other toxic metals. Out of 23 CTB isolates, three bacteria tolerated up to 900 mg/L, 6 up to 500 mg/L, 20 up to 200 mg/L of Cr(VI). These bacteria were also found to be sensitive towards Cu > Co > Cd and very few CTB strains could show multiple metal tolerance. These strains have great scope for their application in bioremediation of toxic chromium ions in presence of other metals ions, which needs to be explored for their biotechnological applications.  相似文献   

Linear dichroism in ALD layers of TiO2     

C. Das  M. Tallarida  D. Schmeißer 《Environmental Earth Sciences》2013,70(8):3785-3795

We prepare TiO₂ film by ALD and study their electronic properties by soft X-ray absorption spectroscopy (XAS) and photoelectron spectroscopy. We focus on XAS and X-ray linear dichroism to indentify band onset and learn about local distortion of the Ti–O octahedral atomic and about defects which cause Ti-based electronic states within the band gap.  相似文献   

The Anorthosites of Angul, India: A Clue to Proterozoic Diapiric Emplacement     

M. Das  A.K. Paul  P. Biswal 《Gondwana Research》2001,4(4):602-603

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Modelling the bar in the centre of the starburst galaxy M82     

K. A. Wills  M. Das  A. Pedlar  T. W. B. Muxlow  T. G. Robinson 《Monthly notices of the Royal Astronomical Society》2000,316(1):33-48

We present VLA A-array 21-cm atomic hydrogen (H  i ) absorption observed against the central region of the starburst galaxy M82 with an angular resolution of ∼1.3 arcsec (≃20 pc). These observations, together with MERLIN H  i absorption measurements, are compared with the molecular (CO) and ionized ([Ne  ii ]) gas distributions and are used to constrain the dynamics and structure of the ionized, neutral and molecular gas in this starburst.
A position–velocity diagram of the H  i distribution reveals an unusual 'hole' feature which, when previously observed in CO, has been interpreted as an expanding superbubble contained within a ring of gas in solid body rotation. However, we interpret this feature as a signature of a nearly edge-on barred galaxy. In addition, we note that the CO, H  i and [Ne  ii ] position–velocity diagrams reveal two main velocity gradients, and we interpret these as gas moving on x₁- and x₂-orbits within a bar potential. We find the best fit to the data to be produced using a bar potential with a flat rotation curve velocity v _b=140 km s⁻¹ and a total length of 1 kpc, a non-axisymmetry parameter q =0.9, an angular velocity of the bar Ω_b=217 km s⁻¹ arcsec⁻¹, a core radius R _c=25 pc, an inclination angle i =80° and a projected angle between the bar and the major axis of the galaxy φ '=4°. We also discuss the orientation of the disc and bar in M82.  相似文献   

Comparison of mapping approaches for estimating extreme precipitation of any return period at ungauged locations     

Das  Samiran  Zhu  Dehua  Yin  Yixing 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(8):1175-1196

Stochastic Environmental Research and Risk Assessment - Reliable estimation of return period values of extreme precipitation at ungauged locations is considered to be a key exercise in...  相似文献   

Influence of Lode angle‐dependent failure criteria on shear localization analysis in sand          下载免费PDF全文

Mitul Sisodiya  Arghya Das 《国际地质力学数值与分析法杂志》2018,42(8):979-998

Geotechnical experiments show that Lode angle‐dependent constitutive formulations are appropriate to describe the failure of geomaterials. In the present study, we have adopted one such class of failure criteria along with a versatile constitutive relationship to theoretically analyze the effects of Lode angle on localized shear deformation or shear band formation in loose sand for both drained and undrained conditions. We determine the variation in the possible stress states for shear localization due to the introduction of Lode angle by considering the localized deformation as a bifurcation problem. Further, similar bifurcation analysis is performed for the stress states along a specific loading path, namely, plane strain compression at the constitutive level. In addition, the plane strain compression tests have been simulated as a boundary value finite element problem to see how Lode angle affects the post‐localization response. Results show that the inclusion of a Lode angle parameter within the failure criterion has considerable effects on the onset, plastic strain, and propagation of shear localization in loose sand specimens. For drained condition, we notice early inception of shear localization and multiple band formation when the Lode angle‐dependent failure criterion is used. Undrained localization characteristics, however, found to be independent of Lode angle consideration.  相似文献   

A study of solar modulation of medium energy primary cosmic ray nuclei     

Projit K. Das  T. D. Goswami 《Journal of Astrophysics and Astronomy》1985,6(1):57-60

The energy spectra of primary cosmic rays were studied in the energy interval 150 to 450 MeV/nucl by using balloon-borne cellulose-nitrate solid-state plastic detector. Effects of solar modulation were studied using the theoretical spectrum ofH ₁ nuclei near the solar minimum in 1964 as the demodulated spectrum. The ‘force-field’ potential which fit the experimental results was estimated to be 270 MeV/nucl.  相似文献   

An elliptical asperity in shear: fracture process and seismic radiation     

S. Das  B. V. Kostrov 《Geophysical Journal International》1985,80(3):725-742

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A note on large amplitude non-linear radial oscillation in polytropic stellar models     

A. K. Chaudhary  M. K. Das  V. B. Bhatia 《Astrophysics and Space Science》1993,206(2):171-178

The periodic solutions of inharmonic oscillators describing the systematics of large amplitude single mode radial pulsator have been obtained using modified Lindstedt-Poincaré method for different values of the amplitude,a.  相似文献   

Exact solution of the transport equation in finite media with a plane and uniform point source and flux normally incident at the faces from outside     

S. Bishnu  S. R. Das Gupta 《Astrophysics and Space Science》1991,176(2):217-262

In this paper we apply the Wiener-Hopf technique combined with the method of the Laplace transform, to derive an exact solution of the transport equation for neutron diffusion in an isotropically scattering plane-parallel medium of finite thickness in which are situated a plane source at the middle and a uniformly distributed point source, there being flux of beams normally incident from outside on the two extreme parallel surfaces of the medium.  相似文献