Browsing by Author "I.B. Singh"

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100 kyr sedimentary record of Marginal Gangetic Plain: Implications for forebulge tectonics
(Elsevier B.V., 2019) Rupa Ghosh; Pradeep Srivastava; U.K. Shukla; R.K. Sehgal; I.B. Singh
The Gangetic Foreland is a consequence of continent-continent collision and formation of the Himalayan thrust and fold belt. In the more distal part of the peripheral Gangetic foreland basin, the Late Quaternary sedimentary architecture analysis from 17 stratigraphic successions together with optically stimulated luminescence dating (OSL) divulge interaction of peripheral bulge tectonics and climate over the past ~100 kyr. These sections exhibit three sedimentary packages formed under different environmental conditions. Detailed vertical and lateral sedimentary architecture delineates nine lithofacies that are grouped into three facies associations, (i) flood plain facies association, (ii) channel facies association, and (iii) interfluve facies association. The basal package-I, >114 ka old, was deposited by sandy meandering channels and overlying to this with a hiatus of ~30 ka is package-II, ~80–54 ka, deposited by gravelly rivers. The sediments of both the packages-I, II are derived from rocks exposed in the peripheral bulge region. Overlain package- III, deposited by small meandering channels, consist of the sediments derived from the Himalaya. The results indicate that the duration of 80–54 ka was a period of forebulge uplift when gravelly fans prograded basinward. Below the fan sediments lies a peripheral bulge unconformity marked by regionally significant pedogenic horizon. This pedogenic horizon qualifies as to be termed as peripheral bulge uncomformity. After 54 ka, the fine Himalayan sediments onlap the cratonic sediments implying rather a stable forebulge tectonics coupled with fluctuating climatic conditions, occasionally bringing micaceous gray coloured sand-silt of Himalayan origin. © 2019 Elsevier B.V.
CORROSION RESISTANCE OF TWO MAGNETIC METALLIC GLASSES IN ACIDIC AND NEUTRAL AQUEOUS SOLUTIONS.
(1986) I.B. Singh; R.S. Chaudhary; T.K.G. Namboodhiri
The corrosion resistance of two magnetic metallic glasses, viz. Fe//4//0Ni//4//0B//2//0 and Fe//3//9Ni//3//9Mo//2 (SiB)//2//0 was evaluated in H//2SO//4 and NaCl solutions by weight loss measurement and electrochemical techniques. In exposures up to six days the corrosion rate of Fe//4//0Ni//4//0B//2//0 was about 5 mpy while Fe//3//0Ni//3//9Mo//2 (SiB)//2//0 corroded about two times faster in 0. 1 M H//2SO//4 solution. In 3. 5% NaCl both alloys corroded at about the same rate, nearly 2 mpy. In potentiostatic polarization measurements the Mo bearing alloy passivated in the potential range plus 0. 45 V to plus 1. 45 V with respect to saturated calomel electrode in H//2SO//4 solutions of concentration 0. 001 M to 0. 1 M, but both alloys failed to passivate in NaCl solutions.
Effect of alloying on the corrosion behaviour of FeB metallic glasses in sulphuric acid
(1986) I.B. Singh; R.S. Chaudhary; T.K.G. Namboodhiri
The corrosion behaviour of seven metallic glasses based on the FeB system, namely (i) Fe40Ni40B20 (Vitrovac 0040), (ii) Fe40Ni38Mo4B18 (Metglas 2826MB), (iii) Fe39Ni39Mo2(SiB)20 (Vitrovac 4040), (iv) Fe40Ni40P14B6 (Metglas 2826), (v) Fe32Ni36Cr14P12B6 (Metglas 2826A), (vi) Fe78B13Si9 (Metglas 2605-S-2) and (vii) Fe67Co18B14Si1 (Metglas 2605Co), was investigated in H2SO4 solutions of various concentrations (0.001-0.1 M) using mass loss and electrochemical techniques. In exposures of up to 6 days the corrosion rate in 0.1 M H2SO4 changed in the following order: 2826A < 2826 < 0040 < 2826MB < 4040 < 2605Co < 2605-S-2. During anodic polarization the alloys 2605-S-2, 2605Co and 0040 did not exhibit passivation whereas the remaining four alloys passivated in all the H2SO4 solutions used. Icorr, Icrit and Ipass for these metallic glasses were found to be dependent on the concentration of the corrodent. Icorr and Icrit for all the alloys decreased with decreasing H2SO4 concentration. Ipass for Metglas 2826 and 2826MB increased with decreasing acid concentration while the opposite effect was found for the other two passivating alloys. The present results showed that the corrosion resistance of FB-based metallic glasses depends on the alloying elements present in them. Their corrosion resistance increased by alloying with metals whose effectiveness increased in the following order: cobalt, molybdenum, nickel and chromium. Similarly, metalloids were effective in increasing corrosion resistance in the following order: silicon, boron and phosphorus. The passive film formed on Metglas 2826A alloy was found to be more stable than those on alloys 2826, 2826MB and 4040. © 1986.
EFFECT OF SOME ANIONS ON THE CORROSION CHARACTERISTICS OF Fe//4//0Ni//4//0B//2//0 METALLIC GLASS.
(1986) I.B. Singh; T.K.G. Namboodhiri; R.S. Chaudhary
The corrosion behavior of Fe//4//0Ni//4//0B//2//0(0040) metallic glass in the presence of sodium salts of Na//2SO//4, Na//2CO//3, Na//2HPO//4, NaNO//3, Na//2MoO//4, Na//2WO//4 and Na//2CrO//4 was investigated. The open circuit potential (OCP) variation in solutions containing these salts in concentration from 0. 1 M to 0. 001 M were measured up to 2 hours. The anodic polarization curves of the alloy have been recorded under potentiostatic condition. The OCP shifted towards the noble direction in presence of chromate and tungstate while towards the active direction in the case of the other anions in ennobling the alloy under OCP conditions.
ELECTROCHEMICAL AND AES INVESTIGATIONS OF SOME METALLIC GLASSES IN SULPHURIC ACID SOLUTION.
(1987) I.B. Singh; R.D.K. Misra; T.K.G. Namboodhiri; R.S. Chaudhary
No passivation is observed for 0040 alloy whereas all the other alloys passivated in sulphuric acid solutions. Initial dissolution of the alloy in the active region is essential for passivation in molybdenum containing alloys and the concentration of Mo in the passive film is less than that of in the bulk of the alloys. Better passivation is observed in 2826 alloy when the dissolution rate is high in the active region. Prepassive film on 2826MB and 2826 alloys is nickel rich which changes to iron rich passive film at higher anodic potentials. In 2826A alloy, chromium and phosphorous concentrations are higher in the passive film.
ELECTROCHEMICAL AND AES INVESTIGATIONS OF SOME METALLIC GLASSES IN SULPHURIC ACID SOLUTION.
(1987) I.B. Singh; R.D.K. Misra; T.K.G. Namboodhiri; R.S. Chaudhary
No passivation is observed for 0040 alloy whereas all the other alloys passivated in sulphuric acid solutions. Initial dissolution of the alloy in the active region is essential for passivation in molybdenum containing alloys and the concentration of Mo in the passive film is less than that of in the bulk of the alloys. Better passivation is observed in 2826 alloy when the dissolution rate is high in the active region. Prepassive film on 2826MB and 2826 alloys is nickel rich which changes to iron rich passive film at higher anodic potentials. In 2826A alloy, chromium and phosphorous concentrations are higher in the passive film.
Migration of the Ganga River and development of cliffs in the Varanasi region, India during the late Quaternary: Role of active tectonics
(2012) U.K. Shukla; P. Srivastava; I.B. Singh
The lithofacies constitution of unconsolidated sediments exposed in Ramnagar cliff indicates sedimentation in sinuous channels, associated flood plain areas and ponds that were developed within the Ganga River valley. The Khadar surface represents a raised river valley terrace into which the main river channel along with its narrow floodplain is incised. Ramnagar cliff section has revealed a variety of deformation structures that indicate repeated tectonic activity in the area. Important tectonic features exposed by the cliff section are reverse faults, folds, cracks filled with sparry calcite and soft sediment structures indicating liquefaction of sediments affected by faulting and folding. Optically stimulated luminescence (OSL) dating of sediments and field relationships of tectonic elements indicate that the Ganga River migrated near to Varanasi 40. ka following a tectonic event in the area. Since then, it meandered freely within its valley until 7. ka when another tectonic event took place and Ramnagar cliff was raised to its present heights. The cliff surface was degraded by gulling activity for about 4000. years before it was occupied by man at around 3000. years. BP. © 2012 Elsevier B.V.
Signatures of Palaeofloods in Sandbar-Levee Deposits, Ganga Plain, India
(2004) U.K. Shukla; I.B. Singh
Based on architectural element analysis of sandbar-levee deposits an attempt has been made to identify recurring floods in the alluvial rivers. Point bar deposits characterized by low-angled lateral accretion (LA) elements exhibit some channel-ward steeply dipping (18-20°) discordant surfaces. These high-angled surfaces are erosional and show change of facies across them. Such discordant planes present within the bar deposits most probably indicate phases of exceptional floods, when the bar was mostly eroded abd remodelled under high-energy conditions. Similarly, in the braid bar deposits superimposed bar-building events separated either by mud drapes or marked erosional contacts are testimony to high-energy floods. At flood times, a new bar may form and can migrate over pre-existing sand bar, forming huge sandflat. Alternately, a new channel may develop cutting across the existing bar complex producing a channel bar having a different orientation. Multi-storied levee deposits developed at the bank of the channels, and characterized by decimeter to meter scale fining-up sequences, are the best indicators of exceptionally large floods overtopping the channels. The flood events are commonly separated by erosional contacts and mottled horizons containing organic matter, root burrows and faecal-pellet filled earthworm burrow network. © Geol. Soc. India.
Two photon absorption spectrum of p-dichlorobenzene
(Springer India, 1995) I.B. Singh; S.B. Rai; D.K. Rai
Two photon absorption spectrum of p-dichlorobenzene has been studied in the spectral region 497-552 nm (one photon wavelength). Bands involving several frequencies of the excited electronic state not detected in the one photon absorption are seen. The observed two photon spectrum indicates that the electronic transition retains, to a large extent, the salient features of the two photon absorption spectrum of benzene and thus confirms chlorine as weak perturber (in the sense of Goodman and Rava [1]). © 1995 Indian Academy of Sciences.
Two-photon spectrum of o-dichlorobenzene
(1994) I.B. Singh; S.B. Rai; D.K. Rai
The two-photon absorption spectrum of O-dichlorobenzene has been recorded in the spectral region 485-540 nm (one-photon wavelength). Nearly 70 hands are observed in the spectrum. These bands are analyzed in terms of frequencies known from earlier studies. Bands involving ν14, ν7a, and ν12 (Wilson′s numbering) have been observed for the first time. © 1994 Academic Press, Inc.