Showing papers by "Jadavpur University published in 1982"

Rectangular microstrip antenna on a ferrite substrate

Abstract: The bandwidth and radiation characteristics of a simple quarter wave microstrip antenna on a typical ferrite substrate are measured and compared with the theoretical results in the lower range of ultrahigh frequency (UHF). A method has also been discussed for impedance matching of the antenna to the feed line.

Geochemistry of banded iron formation of Orissa, India

Abstract: Major and trace element analyses of representative samples of various types of banded iron-formation and its various minerals, associated sediments, iron ores and volcanic tuff from different localities of Orissa, India, are presented in this paper. The Orissa banded iron-formation is classified as Precambrian banded iron formation and is similar to the oxide facies iron formation of Lake Superior type. The Orissa iron formation consists only of iron oxide and silica with total absence of iron silicate, sulfide and carbonate minerals, and is devoid of terrigenous material. The trace element content suggests the source of the underlying quartzite to be a continental igneous rock mass, while the interbedded tuff are of undoubted volcanic origin. The overlying iron formation were chemically precipitated as oxidate sediments in which the principal iron mineral — magnetite — was formed at low temperature in a shallow marine environment. From the overwhelming similarity of major and trace element contents of all the samples from the different localities, it is postulated that these detached outcrops originated in the same continous basin.

Uranium (-Nickel-Cobalt-Molybdenum) Mineralization Along the Singhbhum Copper Belt, India, and the Problem of Ore Genesis

Abstract: Uranium mineralization is present at many places along the 200 km long Singhbhum copper belt, but the mineralization is relatively concentrated at the central part of it. The belt is characterized by many shear zone features, such as mylonites, phyllonites, and L-S type of structures and of course, copious metasomatism. Country rocks are basic schists, metapelites, quartzose rocks and albite schist/gneiss (‘Soda Granite’). Orebodies are sheet-like, conformable with the pervasive planar structures in the host rocks. No pronounced ‘wall rock alteration’ accompanied the mineralization. Grade of the ore is low (<0.1% U3O8). The principal uraniferous mineral uraninite occurs as dissemination. Other uranium-bearing minerals include pitchblende, allanite, xenotime, davidite, clarkeite, autunite (-metaautunite), torbernite, schoepite (-metaschoepite) and uranophane. Uranium is also present in a number of refractory phases either as inclusion of uraninite or in the crystal structure. Additionally, nickel, cobalt and molybdenum are present at Jaduguda-Bhatin in the form of millerite, gersdorffite, melonite, nickel-bearing pyrite, molybdenite etc. Dominance of uraninite over pitchblende and the larger cell-edge of uraninite, development of hematite-bearing quartz and Na-oligoclase at places in the ore zone, association of uranium mineralization with Ni-Co-Mo(-S-As) mineralization at Jaduguda-Bhatin and continuation of the orebodies to considerable depths, suggest that the uranium mineralization along the Singhbhum belt belongs to moderate to high temperature ‘vein type’. The age obtained by Pb207/Pb206 ratio and the concordia method suggest that the uranium mineralization in Singhbhum took place 1500–1600 Ma ago and this age is not far different from the age of formation of uranium-vein deposits in many other Precambrian shields of the world. The following two mechanisms of the formation of the deposits are discussed: 1) uranium precipitated in the Dhanjori basal sediments was mobilized during deformation and metamorphism into ore deposits, 2) the hydrodynamic system that leached out copper from the metabasic rocks to form the copper deposits at an earlier stage, could, in one of the oxidised pulses leach out uranium from the basal sediments and precipitate it in the favourable situations. Subsequent small-scale redistribution is possible. Constituents of the Ni-Co-(-S-As) mineralization appear to have been contributed by the volcanic-sedimentary pile.

Partial Structure of Liquid Sodium—Cesium Alloys

Abstract: The partial structure factors defined by Ashcroft and Langreth and also the number–number, number–concentration, and concentration–concentration structure factors of Bhatia and Thornton are calculated for liquid sodium–cesium alloys at various concentrations with a square-well potential. The total structure factor obtained from these partials compares very well with experimental results. Isothermal compressibilities obtained from the partial structures in the long wave limit are also found to compare satisfactorily with those calculated from sound velocity data. Die von Ashcroft und Langreth definierten Teil-Strukturfaktoren sowie die Zahl–Zahl-, Zahl-Konzentrations- und Konzentrations–Konzentrations-Strukturfaktoren von Bhatia und Thornton werden fur flussign Natrium–Caesium-Legierungen bei verschiedenen Konzentrationen mit einem Rechteck-Potential berechnet. Die aus diesen Partialfaktoren erhaltenen Gesamtstrukturfaktoren stimmen sehr gut mit experimentellen Werten uberein. Es wird gefunden, das die isothermen Kompressibilitaten aus den Partialstrukturen im Grenzfall langer Wellen befriedigend mit denen aus Schallgeschwindigkeitswerten ubereinstimmen.

Rapidity-gap and rapidity-correlation study in 400-GeV/ c proton-nucleus interactions

Abstract: This paper presents a detailed study of the rapidity gaps and the rapidity correlations among the relativistic particles produced in proton-nucleus interaction in emulsion at 400 GeV/c. The study includes (a) cumulative rapidity-gap distribution and hence the cluster characteristics, (b) distribution of shower width (rapidity), (c) distribution of maximum rapidity gap, and (d) two-particle rapidity correlation. The experimental data have been compared with a Monte Carlo simulation assuming an independent-emission model. The target-nucleus dependence of correlation has also been studied.

Velocity auto-correlation and hot-electron diffusion constant in GaAs and InP

Abstract: Auto-correlation functions of the fluctuations in the electron velocities transverse and parallel to the applied electric field are calculated by the Monte Carlo method for GaAs and InP at three different values of field strength which are around three times the threshold field for negative differential mobility in each case. From these the frequency-dependent diffusion coefficients transverse and parallel to the applied field and the figure of merit for noise performance when used in a microwave amplifying device are determined. The results indicate that the transverse auto-correlation functionC t (s) falls nearly exponentially to zero with increasing intervals while the parallel functionC p (s) falls sharply, attains a minimum and then rises towards zero. In each case a higher field gives a higher rate of fall and makes the correlation functions zero within a shorter interval. The transverses diffusion coefficient falls monotonically with the frequency but the parallel diffusion coefficient generally starts with a low value at low frequencies, rises to a maximum and then falls. InP, with a larger separation between the central and the satellite valleys, has a higher value of the low frequency transverse diffusion coefficient and a lower value of its parallel counterpart. The noise performance of microwave semiconductor amplifying devices depends mainly on the low frequency parallel diffusion constant and consequently devices made out of materials like InP with a large separation between valleys are likely to have better noise characteristics.

Novel variable-frequency oscillator with single resistor control using DVCCS/DVCVS

Abstract: A variable-frequency sinewave RC-oscillator configuration using the DVCCS/DVCVS active element is proposed. The realisation is novel as only one resistor and two capacitors are required in the circuit and independent resistor control of ω0 is possible at low active and passive sensitivities.

Effective Pair Potential and Thermodynamic Properties of Liquid Noble Metals

Abstract: The variational method associated with the Gibbs-Bogolyubov inequality in the thermodynamic perturbation method allows the determination of the thermodynamic properties of liquid noble metals. The interionic potentials are generated from the energy-wave-number characteristics obtained from a model pseudopotential in conjunction with the dielectric response function of the interacting electron gas. The variation of the packing density with volume and temperature shows a relatively hard core pseudoatom and it is shown that under pressure, along the melting line, the packing density actually increases for noble metals unlike the simple metals. In addition, the results compare favourably with experiments as well as the calculations of Moriarty based on Harrison's generalised transition metal pseudopotential. Die mit der Gibbs-Bogolyubov-Ungleichung verknupfte Variationsmethode der thermodynamischen Storungsrechnung erlaubt die Bestimmung der thermodynamischen Eigenschaften von flussigen Edelmetallen. Die interionaren Potentiale werden aus den Energie-Wellenzahl-Charakteristiken gewonnen, die aus Modell-Pseudopotentialen in Verbindung mit der dielektrischen Responsefunktion des wechselwirkenden Elektronengases erhalten werden. Die Anderung der Packungsdichte mit dem Volumen und der Temperatur zeigt ein Pseudoatom mit relativ hartem Kern und es wird gezeigt, das unter Druck die Packungsdichte fur Edelmetalle entlang der Schmelzkurve tatsachlich zunimmt im Gegensatz zu den simplen Metallen. Zusatzlich stimmen die Ergebnisse befriedigend sowohl mit den Experimenten als auch mit den Rechnungen von Moriarty oberein, die auf Harrisons verallgemeinerten Ubergangsmetallpseudopotential beruhen.

Novel grounded-capacitor ideal FDNR and oscillator using current conveyors

Abstract: This communication describes the realisation of an ideal frequency-dependent negative-resistance (FDNR) element using the second generation current conveyor (CC II), and its application as a sinewave oscillator with single-grounded-resistor control. The realisation is novel because of the use of a minimum number of passive components with equal-valued grounded capacitors and low active ω0-sensitivity.

Interaction of Cetyltrimethylammonium Bromide with Sodium Dodecyl-Sulfate in Electrolyte and Nonelectrolyte Environments

Abstract: Results of interaction between cetyltrimethylammonium bromide(CTAB) and sodium dodecylsulfate(SDS) at levels below and above their critical micelle concentrations (CMCs) in aqueous medium and in the presence of additives like NaCl, glucose, urea, p-tert-alkyl-phenoxypolyoxyethyleneether(Triton X 100), polyoxyethylenesorbitanmonolaurate(Tween 20), polyoxyethylenesorbitanmonooleate(Tween 80) and polyethyleneglycol (M.W. 600, PEG 600) are presented. Above certain concentrations, the product of formation (the complex, CTA+…DS−) became insoluble. The formation of the precipitate could be greatly influenced by the additives. Both NaCl and urea decreased the solubility, whereas glucose increased it. The effects of the nonionic surfactants TX 100, Tween 20 and Tween 80 showed some peculiarities when SDS was taken below and above its CMC in solutions containing both CTAB and nonionics above their CMCs. Below the CMC of SDS, TX 100 decreased the solubility while Tweens and PEG increased it.

Insensitive minimal-RC sinewave generators with single resistor control

Abstract: Some new RC-oscillator configurations using the second generation current conveyor (CC II) and unity-gain voltage-follower active elements are reported. The circuits are novel because they use only the minimum passive-RC components, single grounded resistor tunability and extremely low active and passive ω0-sensitivities. A comparative study on voltage-follower block implementation with the usual op-amp and the relatively newer CC II element, along with their sensitivity characteristics, has also been included.

Polarographic studies on the hydroxamic acid complexes

Abstract: The Molybdenum complex of benzohydroxamic acid is completely extracted with a chloroform solution of 2-aminoethanol. The extract when subjected to d.c. and Tast polarography after mixing with appropriate volumes of aqueous acetic acid and methanolic lithium chloride furnish a well-defined reduction wave which can be utilised for the determination of the metal. The method is sensitive and highly selective. Different parameters like acids, and solvents have been studied and the nature of the electrode process has been discussed. The metal can be determined in presence of a host of foreign ions and the method can be applied to determine traces of molybdenum in steel (rel. standard deviation ±1.19%).

Kinetics and mechanism of the oxidation of some neutralized α-Hydroxy acids by hexachloroiridate(IV)

Abstract: The kinetics of oxidation of some neutralized α-hydroxy acids such as lactic (LA), mandelic (MA), α-hydroxyisobutyric (IB) and benzilic (BA) acid by hexachloroiridate(IV) have been studied. The oxidation products are acetaldehyde, benzaldehyde, acetone and benzophenone for the respective reactions, which are first order with respect to each substrate and to iridium(IV). The reaction rate increases with increase in pH and salt concentrations. The temperature influence is quite marked in all these reactions. A mechanism involving the formation of an unstable complex, which decomposesvia a free radical pathway to give the respective reaction products, is proposed.

Soft-sediment Deformation Fabric in the Precambrian Bhander Oolite, Central India

Abstract: Chertified oolite in the lower part of the Precambrian Bhander Limestones, around Maihar, Madhya Pradesh, India, shows extensive compaction-deformation of ooids into oblate bodies, lying preferably parallel to bedding. Chertification, though begun locally when compaction was only slight, continued through and outlasted compaction-deformation in most parts. Unusual deformation of ooids is caused by overpressurization of ooids against a preburial rigid emersion surface below the chertified oolite. Unlike common fabrics of tectonically deformed rocks, compaction-deformation fabrics are uneven with respect to both shape and orientation of ooids. Though there is a strong tendency for preferred orientation of the deformed ooids parallel to bedding, directional variability is not uncommon. T is difference of soft-sediment deformation fabric from that of tectonically deformed rocks mainly stems from the fact that overburden stress is transmitted heterogeneously from grain to grain in unconsolidated sediments. Lithification, on the other hand, homogenizes stress distribution leading to greater uniformity of shape and orientation of fabric elements in tectonically deformed rocks. In addition, the soft-sediment deformation fabric lacks relationship with the external geometry of the rocks.

A digital phase-locked loop for generating frequency discriminating digital words

Abstract: The circuit configuration of the DPLL described in this paper is a modified version of the DPLL recently reported by the authors. Fast and symmetrical tracking has been achieved by the modified DPLL retaining the original properties of wide locking range and low frequency capability as an FM discriminator and frequency multiplier. Also, it is operable in a number of modes defined by their phases (0°, 180°, and 90°) and the frequency discriminating code X is scalable by the phase-lock logic design.

Cosmic rays from Jupiter

Abstract: I t was s u g g e s t e d b y PIZZELLA a n d 3*rENDITTI (1) a n d PIZZELLA (2) t h a t J u p i t e r m a y be a source of cosmic r ays o b s e r v e d a t t h e E a r t h . A c c o r d i n g to t h i s sugges t ion , protons are acce le ra ted to h i g h energ ies in J u p i t e r ' s m a g n e t o s p h e r e w h i c h t h e n l e ak out a long i n t e r p l a n e t a r y magne t ic f i e ld l ines e v e n t u a l l y r e a c h i n g t h e E a r t h , p r o v i d e d i t is a p p r o p i a t e l y l oca t ed on t h e s ame field l ine. I)IZZELLA (2) e x a m i n e d n e u t r o n moni to r d a t a for t h e yea r s 1961-65 for seve ra l s t a t i o n s w i t h h i g h cut-off energies . He f o u n d ev idence t h a t t h e cosmic ray flux is g r e a t e r for a c e r t a i n E a r t h l o n g i t u d e in a r e fe rence sys tem w i t h cen t r e a t t h e Sun a n d co r o t a t i ng w i t h J u p i t e r . T h e e jec t ion of h i g h e n e r g y e lec t rons a n d also p r o t o n s b y J u p i t e r ' s m a g n e t o s p h e r e in to t he i n t e r p l a n e t a r y space h a s been o b s e r v e d (2). Quie t t i m e inc reases of h i g h e n e r g y e lec t rons h a v e been r e c o r d e d b y I M P a n d the se inc reases show a 13 m o n t h pe r iod i c i t y , i nd i ca t i ng t h e i r J o v i a n o r ig in fa l l on t h e p r e d i c t e d t i m e of cross ing of J u p i t e r ' s magnet ic-f ie ld l ine b y t he E a r t h (a). SwL~s0.~" (s) p o i n t e d ou t t h a t if cosmic r ays do r e a c h t h e E a r t h f r o m J u p i t e r , t h e pe r iod w h e n E a r t h a n d J u p i t e r a re close to t he same field l ine shou ld show an e n h a n c e d so lar d i u r n a l v a r i a t i o n w i t h t h e p h a s e of m a x i m u m occur ing s o m e w h a t l a t e r as comp a r e d to t h e o t h e r pe r iods . SwI~'SO_~ a n a l y s e d t en yea r s {1965-1975) of d a t a f r o m E m b u d o u n d e r g r o u n d rouen te lescope to e x a m i n e t h i s effect , a s s u m i n g a v a l u e of t h e E a r t h S u n J u p i t e r angle of 125 ~ acco rd ing to t h e r e su l t s of P izzc l la , w h e n t h e two p l a n e t s are on t h e s ame i n t e r p l a n e t a r y m a g n e t i c f i e l d l ine. Hi s ana lys i s of t he d a t a d id no t show dif ference in d i u r n a l v a r i a t i o n of t h e e x p e c t e d n a t u r e , w h e n c e he conc luded t h a t the effect of J u p i t e r on cosmic r a d i a t i o n a t t he E a r t h is m in ima l . T h e p r e s e n t work is a n a t t e m p t to t h r o w some l i g h t on t h i s c o n t r o v e r s i a l i ssue of w h e t h e r a n y p a r t of t h e h i g h e n e r g y cosmic rays r ece ived a t t h e E a r t h o r ig ina t e a t Jup i t e r .

Kinetics and mechanism of the oxidation of ethylene glycol, 2,3-butanediol and pinacol by hexachloroiridate(IV)

Abstract: The kinetics of oxidation of ethylene glycol, 2,3-butanediol and pinacol have been studied spectrophotometrically under different experimental conditions. The reactions seem to occur through the formation of an intermediate complex between each diol and iridium(IV). The complexes decompose through intermediate free radicals to form formaldehyde, acetaldehyde and acetone, respectively. Thermodynamic parameters have been calculated.

Homogeneous isotropic cosmological model in a new scalar-tensor theory

Abstract: A Friedmann-Robertson-Walker (FRW) model is studied in the new scalar-tensor theory of gravitation proposed by Schmidt et al. There is an assumption of a particular functional relationship between the cosmological expansion factor of the FRW model and the scalar field. Exact solutions are given, and it is observed that at least in one case $k=\ensuremath{-}1$ it is possible to obtain a model with oscillation between finite limits.

Identification of an active principle of antitumor antibiotic jawaharene with a mixture of long chain fatty acids

Abstract: Jawaharenel' an antitumor antibiotic complex was obtained from the mycelia of a strain of Aspergillus niger. Its antitumor2-7), antiviral1,8) and antimicrobial9,10' properties were studied in detail. In the present study, jawaharene has been fractionated by silica gel column chromatography and an antitumor active fraction designated JF1 has been obtained. This fraction shows a single spot in thin-layer chromatorgram (TLC) using different solvent systems. JF1 has been found by others to inhibit Ehrlich ascites carcinoma (EAC) and sarcoma-180 (S-180) ascites tumor in Swiss mice. It also inhibits the oxygen uptake and glucose uptake by EAC and S-180 cells, in vitro. The results will be published in a separate communication. The methyl esters of JF1 were made with diazomethane11) and the ester-mixture was purified by silica gel column chromatography and preparative TLC. All the eluates were concentrated and dried in: vacuo. The indication that JF1 is a mixture of long chain fatty acids was obtained from its various spectral data. The IR spectrum suggested the presence of carboxylic acid groups, long methylene chains and olefinic double bonds. The same conclusions could be drawn from the NMR spectrum of the methyl esters of JF1. The mass spectrum of the methyl ester preparation indicated it to be a mixture of methyl esters of straight chain aliphatic acids. The molecular ion peaks corresponding to the constituent fatty acid methyl esters were observed at m/z 214, 242, 268, 270, 296 and 298. Finally the methyl esters of the fatty acids constituting JF1 were quantitatively determined by GLC in Pye Unicam, GCDchromatograph, using a 15 % DEGS column on Gaschrom Z (80100 mesh). Methyl esters of fatty acids were identified by comparison with authentic samples. The peaks 1, 2, 3, 4, 5 and 6 corresponding to lauric, myristic, palmitic, palmitoleic, stearic and oleic acid were observed (Fig. 1) with their relative abundance of 0.2. 0.86, 43.26, 2.0, 11.6 and 42.5 %, respectively. Thus JF, the antitumor active fraction of jawaharene, has been found to consist of six different long chain fatty acids of which palmitic (43.26 %) and oleic (42.5 %) are the major constituents. Among these six fatty acids oleic acid (commercial) has been found to be most active against EAC and S-180 cells comparable to JFr. There are reports of antitumor active fatty acids (palmitic, stearic, octadecaenoic and octadecadienoic) isolated from the mycelia of some fungi12,13) viz. Penicillium crustosuin, P. tardum, Cepltalosporium diospvri, Sepedoniunr wnpullosporum. The fatty acids constituting JF1 occur commonly in the lipids of almost every organism. However, the antitumor properties of such fatty acids and their role as dietary constituents warrant further investigation in detail.

Liquid-liquid extraction of ruthenium(III) thiocyanate with hexamethylphosphoramide: Direct spectrophotometric determination in the organic phase

Abstract: Ru(III)-thiocyanate has been extracted with hexamethylphosphoramide (HMPA) in methyl isobutyl ketone (MIBK). Thus the extractability, sensitivity and selectivity are improved over the simple binary Ru(III) thiocyanate system in spectrophotometric determination of ruthenium in the organic phase. The maximum colour develops on the steam bath, at the acidity range of 1.5–2.5M with HCl and ammonium thiocyanate concentration range of 0.25–0.5M. The colour is completely extractable in MIBK when 1.5–3.0 ml HMPA is used and show maximum absorbance at 570 nm. The colour system obeys Beer's law for 0.7–13 νg Ru/ml and the optimum concentration range is 2–13 νg/ml. The molar absorptivity and sensitivity are 69401-mole−1 cm−1 and 0.0145 νg/cm2 respectively. The percent relative error is 2.72%. The method is very simple and does not require oxidation and subsequent distillation. The method can be applied in the presence of osmium.