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  • Electronic Resource  (11)
  • 1990-1994  (3)
  • 1980-1984  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Geochemistry of braunite and associated phases in metamorphosed non-calcareous manganese ores of India (1984)
    Springer
    Contributions to mineralogy and petrology 87 (1984), S. 65-71 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In the metamorphosed manganese oxide ores of India, braunite is ubiquitous in all assemblages from chlorite to sillimanite grades. Chemical analyses of braunite from different prograde assemblages confirm the presence of a fixed R2+ (=Mn2++Mg+Ca) SiO3 molecule in the mineral. Element partitioning between coexisting braunite and bixbyite indicates a near-ideal mixing of Fe+3/ -Mn+3 in the phases. This also indicates that braunite became relatively ferrian while equilibrating with associated phases such as bixbyite, hollandite and jacobsite during prograde reactions. Petrogenetic studies show that as a general trend, prograde lower oxide phases appeared by deoxidation of higher oxide phases. But braunite, a more reduced phase than bixbyite, appeared early from deoxidation of pyrolusite in presence of quartz. Bixbyite could appear later from the reacting pyrolusite-braunite-quartz assemblage. Inferred mineral reaction paths and the general trend of pro-grade deoxidation reactions suggest that the composition of ambient fluid phase was internally buffered during metamorphism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371403
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of static charge on the tarnishing behaviour of silver in iodine atmosphere at low temperatures (1990)
    Springer
    Journal of materials science 25 (1990), S. 1318-1324 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The kinetics of Agl film growth on silver under the action of applied static charge of both the polarities, as well as under normal iodination conditions in the temperature range of 294 to 338 K and in the iodine partial pressure range of 0.03 to 0.22kPa, conform to parabolic rate law. Compared to normal iodination, an enhancement in rate under both positive and negative surface charge conditions at the Ag/Agl interface and a decrease in rate under either surface charge condition at the Agl/l2 interface have been observed. The increased rate with negative charge at the Ag/Agl interface and the decreased rate with same kind of charge at the Agl/l2 interface, compared to normal iodination, can be explained on the basis of positive hole transport, while the observed effects with positive charge at either of the interfaces receive reasonable support from cation migration as the rate limiting factor during the film growth process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585443
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  • 3
    Electronic Resource
    Electronic Resource
    Unsteady hydromagnetic laminar flow of a conducting dusty fluid between two parallel plates started impulsively from rest (1981)
    Springer
    Acta mechanica 39 (1981), S. 171-182 
    Details
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es wird die instationäre, laminare Bewegung eines elektrisch leitenden, viskosen, inkompressiblen, staubhaltigen Fluids zwischen zwei unendlich ausgedehnten, nichtleitenden, parallelen Platten unter einem einheitlichen Quermagnetfeld, welches relativ zum Fluid festgehalten wird, behandelt. Die untere und die obere Platte werden stoßartig aus der Ruhe beschleunigt und bewegen sich anschließend mit gleichförmigen, aber unterschiedlichen, Geschwindigkeiten. Es werden die Geschwindigkeiten für das leitende, staubhaltige Fluid und die nichtleitenden Staubpartikel in Abhängigkeit dreier dimensionsloser Parameter, der Konzentrationl, des Relaxationsparameters σ und der HartmannzahlM erhalten. Die Ausdrücke für den Durchsatz pro Breiteneinheit der Platte und die Schichtreibung an der unteren Platte werden berechnet. Die numerischen Ergebnisse zeigen, daß mit wachsender Hartmannzahl die Geschwindigkeiten des Gases und der Staubpartikel anwachsen wenn beide Platten in Bewegung sind und die Geschwindigkeit der oberen Platte gleich, größer oder kleiner ist als die der unteren Platte und die gleiche Richtung hat. Im Fall der Couette-Bewegung nehmen sie ab.
    Notes: Summary The unsteady laminar motion of an electrically conducting, viscous and incompressible dusty fluid between two infinitely extended non-conducting parallel plates under a uniform transverse magnetic field, fixed relative to the fluid has been considered. The lower and the upper plate are started impulsively from rest and thereafter move with different but uniform velocities. The velocity fields for the conducting dusty fluid and non-conducting dust particle have been obtained in terms of three non-dimensional parametersl (concentration), σ (relaxation time parameter) andM (Hartmann number). The expressions for the discharge per unit breadth of the plate and the skin-friction at the lower plate are calculated. It is observed, from numerical calculations, that as the Hartmann number increases velocities of the dusty gas and dust particle increase when both the plates are in motion (velocity of the upper plate being equal to, greater than and less than that of the lower plate in the same direction) and decrease in case of Couette motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01170340
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  • 4
    Electronic Resource
    Electronic Resource
    Spin diffusion and spin echo in normal liquid3He (1983)
    Springer
    Journal of low temperature physics 51 (1983), S. 265-278 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The problem of spin diffusion in normal liquid3He in the presence of precessional effects is reexamined taking into account the energy dependence of the quasiparticle relaxation time. This leads to a generalization of Leggett's relation for the successive height of the echoes in a φ-180°-180° experiment. Reanalyzing the experiment of Corruccini et al. (including finite-temperature corrections) leads to almost exact and model-independent values for F 1 a and λD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683556
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  • 5
    Electronic Resource
    Electronic Resource
    Anomalous specific heat of liquid 3He above the superfluid transition temperature (1981)
    Springer
    Journal of low temperature physics 43 (1981), S. 17-24 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: The contribution to the specific heat due to order parameter fluctuations in liquid 3He just above the superfluid transition temperature T c is calculated exactly within a Landau theory approach. The effect turns out to be unobservably small and thus cannot explain the large (∼9%) rise in specific heat above the normal state value at the saturated vapor pressure in a recently reported experiment. We do not find the divergence of the specific heat at T cobtained earlier by Thouless from a microscopic calculation and indicate how the difference can be reconciled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00118619
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  • 6
    Electronic Resource
    Electronic Resource
    Surfactant stabilised colloidal cholesterol (1993)
    Springer
    Colloid & polymer science 271 (1993), S. 793-798 
    Details
    ISSN: 1435-1536
    Keywords: Cholesterol colloids ; surfactants ; surface charge ; zeta potential ; stability ; shape ; size ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Cholesterol colloids stabilised by Tween 20 (Colloid I), SDS-Et4 NBr (Colloid II), and CTAB-Nac (Colloid III) were prepared. Moving boundary electrophoresis established Colloid III to be positively charged with a zeta potential of 12.2 mV. Addition of 5 mmol dm−3 Na2SO4 and 0.1 mmol dm−3 bilirubin dye (Na-salt) decreased the zeta potential to 9.7 mV and 9.5 mV, respectively, by screening the surface charge of the colloidal particles. Higher concentrations of Na2SO4 and bilirubin (Na-salt) made making electrophoretic measurements difficult, and such a situation was also faced in the case of Colloid II even without external addition of an electrolyte. Addition of several electrolytes revealed that Colloids II and II were coagulated by the neutralisation of their positive charge, but Colloid I was destabilised by salting-out effect. Measured intrinsic viscosity values and electron microscopic measurements supported overall spherical shape of the colloid particles. Colloid II exibited structural viscosity; higher concentration of NaSO4 decreased the viscosities of Colloid II and II by electroviscous effect which helped indirect determination of the electrokinetic potential (23.7 mV) of Colloid II.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00660097
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  • 7
    Electronic Resource
    Electronic Resource
    Theoretical study of the flow field inside a hydrocyclone with vortex finder diameter greater than that of apex opening—I. Laminar case (1980)
    Springer
    Flow, turbulence and combustion 36 (1980), S. 197-212 
    Details
    ISSN: 1573-1987
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The axi-symmetric laminar boundary layers, formed on the conical surface and under the cyclone roof, have been calculated by Pohlhausen's method assuming that the tangential velocity outside boundary layers varies as r −n up to the point where boundary layers meet solid body rotating liquid column and thereafter as r—as found in experiments—where r is the distance from the axis of the cone and n is flow pattern constant. Point of interaction of the boundary layers with solid body rotating liquid column has been taken from experimental results obtained with a hydrocyclone having vortex finder diameter greater than that of apex opening. Results show that there is no possibility of separation of boundary layers from cyclone wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386471
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  • 8
    Electronic Resource
    Electronic Resource
    Theoretical study of the flow field inside a hydrocyclone with vortex finder diameter greater than that of apex opening—II. Turbulent case (1980)
    Springer
    Flow, turbulence and combustion 36 (1980), S. 213-225 
    Details
    ISSN: 1573-1987
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As in the laminar case (see previous paper), the axi-symmetric turbulent boundary layers have been studied inside a hydrocyclone having overflow diameter greater than that of underflow. This type of hydrocyclone is generally used in practical applications. Calculating total flux through the boundary layers, formed on the conical surface and under the roof of the hydrocyclone, a mathematical model of the flow field has been obtained which agrees very well with previous experimental findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386472
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and lysis of formate by immobilized cells of Escherichia coli (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 775-780 
    Details
    ISSN: 0006-3592
    Keywords: formate ; Escherichia coli ; formate hydrogenlyase ; cell immobilization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Formate hydrogenlyase (FHL) activity was induced in a strain of Escherichia coli S13 during anaerobic growth in yeast extract-tryptone medium containing 100 mM formate. The cells obtained at the optimum growth phase were immobilized in 2.5% (w/v) agar gel when 50-60% of the whole cell FHL activity was retained. The immobilized FHL system had good storage stability and recycling efficiency. In the lysis of formate, an increase of formate concentration to 1.18M increased QH2 (initial) value of the immobilized cell, and subsequently cells, hydrogen evolution, in general, ceased after 6 to 8 of incubation, resulting in incomplete lysis of formate. Presence of small amount of glucose (28 mM) was more or less quantitatively lysed with concomitant disappearence of glucose from the medium. Synthesis of formate from hydrogen and bicarbonate solution by the immobilized cells was also characterized. Presence of glucose (10 mM) in 50 mM bicarbonate solution stimulated formate synthesis by immobilized cells. The pH optimum range, Km, and specific activity of the immobilized cells for the lysis of formate were 6.8-7.2 0.4M, and 66 mL/g cell-h, respectively. The cells could fix hydrogen to the extent of 24.4% (w/w) of its own wet cell mass in a 72-h reaction cycle. Potentiality of the immobilized FHL system for biotechnological exploitation was discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260390710
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics of the oxidation of U (IV) by hydrogen peroxide in sulfuric acid medium (1981)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 385-401 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reaction have been investigated in H2SO4 medium under different conditions. The observed bimolecular rate constant kobs, has been found to depend on [H+]-0.55 and to increase with the initial concentration ratio of the reactants R0 = [H2O2]0/[U (IV)]0 above 0.49. The activation energy of the overall reaction has been determined as 13.79 and 14.3 kcal/mol at R0 = 1 and 0.35, respectively. Consistent with experimental data, a detailed reaction mechanism has been proposed where the hydrolytic reaction (4) followed by the rate-controlling reaction (10) and subsequent fast reactions of U (V) and OH radicals are involved: A kinetic expression has been derived from which a graphical evaluation of (kK4)-1 and k-1 has been made at R0 = 1 as (12.30 ± 0.09) × 10-3 M min, (6.23 ± 2.19) × 10-4 M min; and at R0 = 0.35 as (12.63 ± 2.13) × 10-3 M min, (8.32 ± 6.62) × 10-4 M min, respectively. Indications of some participation of a chain reactionat R0 = 1 have been obtained without affecting thesecond-order kinetics as observed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550130405
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