Showing papers by "Jadavpur University published in 1980"

Geologic setting, genesis and transformation of sulfide deposits in the northern part of Khetri copper belt, Rajasthan, India — an outline

Abstract: The present study is confined to the northern part of the Khetri copper belt that extends for about 100 km in northern Rajasthan. Mineralization is more or less strata-bound and is confined to the garnetiferous chlorite schist and banded amphibolite quartzite, occurring towards the middle of the Proterozoic Delhi Supergroup. Preserved sedimentary features and re-estimation of the composition of the pre-metamorphic rocks suggest that the latter were deposited in shallow marine environment characterized by tidal activity. Cordierite-orthoamphibole-cummingtonite rock occurring in the neighbourhood of the ores is discussed, and is suggested to be isochemically metamorphosed sediment. The rocks together with the ores were deformed in two phases and metamorphosed in two progressive and one retrogressive events of metamorphism. Study of the host rocks suggests that the maximum temperature and pressure attained during metamorphism are respectively 550–600°C and 491°C. Sulfide assemblages are explained in terms of fS2 during metamorphism. Co-folding of the ore zone with the host rocks, confinement of the ores to the carbonaceous pelites or semi-pelitic rocks, strata-bound and locally even stratiform nature of the orebodies, lack of finite ‘wall rock alteration’, metamorphism of the ores in the thermal range similar to that for the host rocks, absence of spatial and temporal relationship with the granitic rocks of the region led the authors to conclude that the entire mineralization was originally sedimentary-diagenetic. Any loss of primitive features and development of incongruency are due to subsequent deformation and metamorphism to which the ores and their hosts were together subjected.

Adsorption of proteins at the polar oil—water interface

Abstract: Adsorption isotherms of BSA and gelatin at the polar peanut oil—water interface have been studied as a function of biopolymer concentration, ionic strength of the medium, pH, and temperature For BSA, the maximum amount adsorbed at saturation (Γ p m ) is found to be affected appreciably by the presence of various neutral salts such as KSCN, Na 2 SO 4 , LiCl, and CaCl 2 Ionic strength has little effect on the isotherms near the isoelectric pH 50 Γ p m for BSA is affected by the change in pH, and the extent of adsorption decreases with temperature increase However, the isotherm for gelatin is insensitive to change in pH and temperature After initial saturation, Γ p for gelatin further increases sharply without limit even when the equilibrium protein concentration has been brought to 16% The values of the standard free energy change for adsorption have been calculated on the basis of the Gibbs equation The standard entropy and enthalpy changes calculated therefrom are positive

Lossless inductor simulation: novel configurations using d.v.c.c.s.

Abstract: Novel lossless grounded and floating inductor simulating networks using only one grounded capacitor and the differential voltage-controlled current source (d.v.c.c.s.) active elements are proposed.

Storm Deposits in the Late Proterozoic Lower Bhander Sandstone of Vindhyan Supergroup Around Maihar, Satna District, Madhya Pradesh, India

Abstract: Intertidal late Proterozoic Lower Bhander Sandstone around Maihar, Satna district, Madhya Pradesh, characteristically displays three orders of sandstone/shale alternations. The lowest order millimeter-thick alternations can be explained as related to tidal rhythms. The second-order alternations in the range of centimeters appear to be related to processes with periodicities greater than tidal rhythms-storm/calm condition. That these centimeter-thick sandstones are possible product of suspension-laden storm surge ebb current is supported by 1) the presence of various types of tool marks, scour marks, and load structures, 2) the presence of sharp, erosional bases and diffused tops, 3) gradual transition from parallel lamination to ripple lamination up the sequence, 4) sporadic preservat on of larger dune bedforms, and finally by 5) consistent seaward directed paleocurrent. This contention is further strengthened by the fact that the vertical lithofacies change is nonmarkovian in character. The uncommon overthickened first order sandstones in the range of decimeters are composite in character and appear to be product of storms coming at close intervals or of complete erosion of mud interlayers.

Stratigraphy and Structure of the Precambrian Banded Iron Formation and Chromite-Bearing Ultramafic Rocks of Sukinda Valley, Orissa

Abstract: The Sukinda Valley of Orissa is underlain by the banded iron formation (BlF) and chromite-bearing ultramafic rocks of Precambrian age. Besides these, local exposure of a quartz-arenite bed with basal conglomerate is correlated with the Kolhans. A basal quartzite horizon is conformably overlain by the BIF. lhe quartz-arenite (Kolhans?) with a conglomerate at the base lies with a local disconformity over the BIF. Chromitebearing ultramafites are pre-kinematic intrusives into the iron formation and have been co-folded with the older sediments. Orthopyroxenite and granitic rocks are intrusive into the chromiferous ultramafites. Occasional intrusive dolerite dykes in the valley may be correlated with the Newer Dolerites of Singhbhum. The regional structure of the Precambrian rocks of the Sukinda Valley, as established by the present authors, is a cross-folded doubly plunging syncline with the culminated fold axis striking ENE-WSW which is parallel to the main fold axis of the Eastern Ghats Orogenic belt. The plunge of the main fold axis is towards NE and wsw. The cross-folded axis, lying between Tungaisuni and Champajhar villages, trends NNW-SSE and is subparallel to the cross-folded axes of the Eastern Ghat Orogenic belt.

Microstrip rectangular resonators on ferrimagnetic substrates

Abstract: The resonant frequency, bandwidth, efficiency and resonant length of a rectangular microstrip resonator on a ferrimagnetic substrate are derived theoretically and are computed for a typical ferrite substrate. The computed values are compared with those of a similar microstrip antenna on a dielectric substrate.

Short-range repulsion in hypernuclei and calculation using K harmonics

Abstract: The $K$-harmonics method is used to determine the $\ensuremath{\Lambda}$ separation energy ${B}_{\ensuremath{\Lambda}}$ for the hypertriton and the $\ensuremath{\Lambda}\ensuremath{\Lambda}$ separation energy ${B}_{\ensuremath{\Lambda}\ensuremath{\Lambda}}$ for $_{\ensuremath{\Lambda}\ensuremath{\Lambda}}^{6}\mathrm{He}$. ${B}_{\ensuremath{\Lambda}}$ is calculated by retaining twelve harmonics and using $\ensuremath{\Lambda}\ensuremath{-}N$ and $N\ensuremath{-}N$ local potentials of the Volkov type fitted to Nagel's meson theoretic (model B) values of the scattering lengths and effective ranges. It gets reduced from 0.33 to 0.13 MeV by the addition of suitable repulsive terms. Retaining only nine harmonics, a convergent result for ${B}_{\ensuremath{\Lambda}\ensuremath{\Lambda}}$ is obtained with Tang and Herndon's $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\Lambda}$ potential and a two-term $\ensuremath{\Lambda}\ensuremath{-}\ensuremath{\Lambda}$ potential of the Volkov type. The experimental ${B}_{\ensuremath{\Lambda}\ensuremath{\Lambda}}$ value of 10.8 MeV can be reproduced with a $\ensuremath{\Lambda}\ensuremath{-}\ensuremath{\Lambda}$ potential that gives rise to the scattering length of - 2.23 fm and an effective range of 3.31 fm.NUCLEAR STRUCTURE Short-range repulsion, $K$ harmonics, $_{\ensuremath{\Lambda}}^{3}\mathrm{H}$, $\ensuremath{\Lambda}$ separation energy, $_{\ensuremath{\Lambda}\ensuremath{\Lambda}}^{6}\mathrm{He}$, $\ensuremath{\Lambda}\ensuremath{\Lambda}$ separation energy, scattering length, effective range.

Novel insensitive lossless inductor simulation through inverse function generation

Abstract: This communication describes a new method of active lossless single-element controlled inductor simulation by realising a function H = [1 - (Y2/Y1)]-1 with a negative impedance convertor block (n.i.c.) and then generating 1/H by an infinite-gain operational amplifier (o.a.). Suitable resistive feedback is then applied to synthesise Yin = Yo (1 - H-1) = Y0 Y2/Y1 which yields a lossless inductor with Y1 = sC, Y0 = 1/R0 and Y2 = 1/R2. The lossless inductor is shown to be insensitive to active parameter changes with an appropriate choice of the active elements such as the n.i.c. implementation with a second generation current conveyor (c.c.II) and inverse generation by an o.a.

A New Method for the Demodulation of FM Signals

Abstract: A novel time-domain semidigital approach for frequency demodulation is described This conceptually simple method, utilizing a couple of engineering approximations, has excellent linearity for small frequency deviation, an undeteriorating sensitivity even for very small frequency deviation, is self-timed and is highly suitable for circuit integration; however, with the present day circuit technology, the usefulness of the method is limited to low frequency FM only

Unsteady Magnetohydrodynamic Couette Flow between Two Plates When One of the Plates is Subjected to Random Pulses

Abstract: Previous investigators have studied the unsteady hydrodynamic and magnetohydrodynamic flow of viscous fluid between plates, cylinder etc. Generally these problems are solved assuming pressure gradient, external forces etc., of deterministic nature. 1-3) Recently attempts are being made to solve mechanical and hydrodynamic problems under stochastic body and surface forces. 4) Here we shall study a similar flow problem between two plates when one of the plates is kept fixed and the other is subjected to pulses of random strength applied at random instants of time parallel to the other plate. We can easily extend this solution to similar flow problems of elastic viscous fluid.

Similarity solutions for propagation of strong plane shock waves in an optically thin atmosphere

Abstract: Similarity solutions, using Planck's diffusion approximation, for propagation of strong plane shock waves in an optically thin grey atmosphere of uniform density are obtained. Solutions for the ratio of specific heats 4/3 and several values of the radiation parameter are compared with those in the absence of any radiation. Excerpts from the results of integrations for different values of the ratio of specific heats are also given in Tables I-III.

Effect of external mass transfer of activation energy of hydrolysis of BAEE and casein by trypsin immobilized on molecular sieve type 4A

Abstract: In this investigation, the activation energies of the hydrolysis of N-(α)-benzol-L-arginine ethyl ester (BAEE) and casein have been determined using trypsin immobilized on molecular sieve type 4A. There is a complete absence of intraparticle diffusion in the system, and the temperature dependence of the reaction has been studied only under external diffusional limitation. While the hydrolysis of BAEE by bound trypsin in found to be controlled by external diffusion, that of casein is kinetically controlled.

Floating inductor with two current conveyors

Abstract: There have been considerable efforts towards the realization of ideal floating inductors where mostly three active blocks are required. The reduction in the number of active blocks to two was however achieved with considerable increase in the number of resistances and passive parameter constraints. The proposed scheme suggests a method to produce a floating inductor with a series negative resistance using two current conveyors, only three resistors and one capacitor, involving only one restrictive constraint. The realized inductor was also used to design a third order Butterworth filter. Experimental results confirm the applicability of the realized immittance.

Novel active R supercapacitor simulation: applications in low sensitivity multifunction network realisation

Abstract: A new configuration containing only two operational amplifiers and a single resistor has been shown to simulate a grounded supercapacitor (D) frequency-dependent negative resistance element based on the usual one-pole rolloff characteristics of the active o.a. device. Appropriate insertion of only one additional RC section yields a novel network with multifilter function capabilities having independent Q and ω0 adjustments at very low active and passive sensitivities. With suitable design, a minimal circuit realisation of a variable frequency active R oscillator can be derived from the proposed configuration.

Static polarizabilities and shielding factors of the magnesium isoelectronic sequence

Abstract: The static dipole quadrupole polarizabilities and shielding factors of Mg, ${\mathrm{Al}}^{+}$, ${\mathrm{Si}}^{2+}$, ${\mathrm{P}}^{3+}$, ${\mathrm{S}}^{4+}$, ${\mathrm{Cl}}^{5+}$, and ${\mathrm{Ar}}^{6+}$ have been calculated using the variation perturbation technique in a coupled Hartree-Fock scheme. For the dipolar calculation the two innermost cores have been kept frozen, whereas for the quadrupolar calculation all the cores have been relaxed. The results compare favorably with the existing values. For the quadrupolar shielding factor in all cases an antishielding effect is noted. Systematic behavior is observed for the isoelectronic polarizability values.

Neutron diffraction study of liquid carbondiselenide

Abstract: A study of an orientational model approach for molecular liquid CSe2 is given. With proper selection of the centres structure factor and weighting of parallel and perpendicular orientations, an agreement comparable with the reference interaction site model (RISM) calculations can be obtained, except in the low Q region. Next, from the experimental molecular structure factor data calculations are made for the centres structure factor, centres radial distribution, centres direct correlation, intermolecular potential energy and, finally, the partial structure factor of Se in CSe2.

Moisture‐cured polyurethane based on polyester and polycarbonate polyols

Abstract: Moisture-cured polyurethanes were prepared by reacting toluene diisocyanate and sebacic acid-based hydroxy esters such as ethylene glycol sebacate, propylene glycol sebacate, diethylene glycol sebacate, and polyester polyols such as poly(ethylene glycol sebacate), poly(propylene glycol sebacate), poly(diethylene glycol sebacate), and poly(butane diol sebacate). The effect of molecular weight of the esters on film properties and the catalytic effect of 3–5% triethylamine, triethanolamine, and 2-diethylaminoethanol on curing of such films were investigated. Polyurethanes were also prepared using a blend of poly(butane diol carbonate) polyol with polyester polyols. Best polyurethane compositions were obtained when sebacic acid-based polyester polyols were blended with poly(butane diol carbonate) polyol in the ratio of 3:2. These polyurethanes show good tensile strength (120–215 kg/cm2) and elongation (340–460%) properties, having high melting points (247–268°C) and good resistance to solvents and chemicals. Moreover, they are colorless and transparent.