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981.
982.
983.
The instability of the plane interface between two viscoelastic (Oldroydian) superposed conducting fluids permeated with suspended particles in porous medium is studied when the whole system is immersed in a uniform magnetic field. The dispersion relation for the Oldroydian viscoelastic fluid is obtained which also yields dispersion relations for Maxwellian and Newtonian fluids in special cases, in the presence of suspended particles in porous medium in hydromagnelics. The system is found to be stable for potentially stable case. The presence of magnetic field stabilizes certain wave number band whereas the system was unstable for all wave numbers in the absence of magnetic field, for the potentially unstable configuration. The growth rates increase (for certain wave numbers) and decrease (for other wave numbers) with the increase in stress relaxation time, strain retardation time, suspended particles number density and medium permeability. 相似文献
984.
H. S. Dang D. D. Jaiswal K. B. S. Murthy R. C. Sharma P. P. V. J. Nambiar C. M. Sunta 《Journal of Radioanalytical and Nuclear Chemistry》1992,156(1):55-64
This paper compares the urinary excretion levels of Th obtained in bio-assay monitoring using the neutron activation technique with those predicted by applying the ICRP metabolic model to the measured Th activity in chest and total body of a group of Thorium plant workers. The results indicated much lower urinary Th excretion as compared to what was expected on the basis of the ICRP model. Lower urinary excretion in occupational subjects is explained in terms of negligible contribution of skeleton and soft tissue to the activity excreted in urine. It is suggested that the existing model should be modified to enable it to be applicable to the bio-assay monitoring of occupational workers. 相似文献
985.
986.
H. S. Sharma R. B. Manolkar J. V. Kamat S. G. Marathe 《Fresenius' Journal of Analytical Chemistry》1993,347(12):486-490
Summary Graphite has been employed as a working electrode in the controlled potential coulometric determination of uranium and plutonium. The couples U(VI)/U(IV) and Pu(IV)/Pu(III) employed for analysis have diverse redox potentials and commonly the working electrodes employed are mercury and platinum. A graphite electrode in the shape of a beaker showed satisfactory performance for the quantitative reduction of U(VI) to U(IV) and Pu(IV) to Pu(III) and also for quantitative oxidation of Pu(III) to Pu(IV). Studies on the levels of the background current, blank values and their reproducible behaviour in acid media have been carried out with a view to achieve good precision and accuracy. A software-based predictive evaluation technique of end-point charge has been investigated. The results have shown that the graphite electrode can be used for the determination of both uranium and plutonium in the presence of each other with a precision and accuracy of better than ±0.5%. 相似文献
987.
Luis Esquivias Rocío Litrán Julián Rodríguez-Ortega Eduardo Blanco Milagrosa Ramírez-del-Solar Nicolás de la Rosa-Fox 《Journal of Sol-Gel Science and Technology》1998,11(3):217-227
The influence of using TMOS or TEOS in the formation of CdS quantum dots in a silica matrix have been studied by X-ray absorption spectroscopy (XAS). The amount of Cd-S bonds have been monitored as a function of the nominal Cd concentration. The relative amount of CdS crystals depends on the precursor. The use of TEOS is not recommended because it gives a poor yield, especially for high Cd concentration. A discussion of the influence of CdS concentration in matrices from TMOS is carried out from structural models created from their pore volume distribution. The mean pore size becomes smaller and the size distribution more uniform when CdS concentration increases but the nanocrystals of low CdS nominal content present a more efficient quantum confinement. 相似文献
988.
The oxide system Bi2.2Ca2.8−x
Sr
x
Cu2O
y
has been investigated for superconductivity as a function of Ca/Sr ratio withx=0.7, 1.0, 1.4 and 1.8. All these compositions are found to be superconducting with onset temperature in the range of 80–90
K implying a large homogeneity range between Sr and Ca for the superconductivity to occur in this system. Effect of partial
replacement of Bi by rare earths has been studied and it is observed that 20% replacement of Bi by Nd and Eu does not significantly
affect the superconducting transition temperature. 相似文献
989.
In this paper a variation in density of states (DOS) of the substrate due to chemisorption of hydrogen on transition metals
using composite Anderson-Newns model has been investigated for different coverages in quasi-chemical approximation of Fowler
and Guggenhiem, which in the limitz→∞ gives the Bragg-Williams approximation as a special case. Variation in density of states has been studied for one-dimensional
periodic substrate with change in adatom interaction energy and coverage. With increase in coverage, the bonding and antibonding
(B-AB) peaks are found to shift towards higher energies and at the same time relative height of the peaks also increases.
The interesting feature to observe is that both approximations for a particular coverage, give split-off states with different
height for both (B-AB) peaks. It particularly indicates change in B-AB states, representing amount of chemisorption, with
the change in interaction energy between adatoms. At the same time bond strength is also found to decrease with interaction
between adatoms. 相似文献
990.