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  • Author or Editor: L. Rao x
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Abstract  

We study the influence of production on utilization functions. A concrete example of this is the influence of the growth of literature on the obsolescence (aging) of this literature. Here, synchronous as well as diachronous obsolescence is studied. Assuming an increasing exponential function for production and a decreasing one for aging, we show that, in the synchronous case, the larger the increase in production, the larger the obsolescence. In the diachronous case the opposite relation holds: the larger the increase in production the smaller the obsolescence rate. This has also been shown previously byEgghe but the present proof is shorter and yields more insight in the derived results. If a decreasing exponential function is used to model production the opposite results are obtained. It is typical for this study that there are two different time periods: the period of production (growth) and — per year appearing in the production period — the period of aging (measured synchronously and diachronously). The interaction of these periods is described via convolutions (discrete as well as continuous).

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Abstract  

In this paper, growth models are classified and characterised using two types of growth rates: from time t to t+1 and from time t to 2t. They are interesting in themselves but can also be used for a quick prediction of the type of growth model that is valid in a particular case. These ideas are applied on 20 data sets collected byWolfram, Chu andLu. We determine (using the above classification as well as via nonlinear regression techniques) that the power model (with exponent>1) is the best growth model for Sci-Tech online databases, but that Gompertz-S-shaped distribution is the best for social sciences and humanities online databases.

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Abstract  

Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the Np(V)/sulfate complex and determine the equilibrium constants and enthalpy of complexation at 10–70°C. Results show that the complexation of Np(V) with sulfate is weak but slightly enhanced by the increase in temperature. The complexation is endothermic and becomes more endothermic with the increase in temperature. The enhanced complexation at elevated temperatures is due to the increasingly larger entropy of complexation that exceeds the increase in enthalpy, indicating that the complexation of Np(V) with sulfate is entropy-driven.

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Abstract  

Complexation of neptunium(V) with fluoride in aqueous solutions at elevated temperatures was studied by spectrophotometry and microcalorimetry. Two successive complexes, NpO2F(aq) and NpO2F2 , were identified by spectrophotometry in the temperature range of 10–70°C. Thermodynamic parameters, including the equilibrium constants and enthalpy of complexation between Np(V) and fluoride at 10–70°C were determined. Results show that the complexation of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature — a two-fold increase in the stability constants of NpO2F(aq) and more than five-fold increase in the stability constants of NpO2F2 as the temperature is increased from 10 to 70°C.

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Abstract  

The homogeneity of four reference materials was evaluated for Se by cyclic instrumental neutron activation analysis (CINAA). The relative standard deviation for Se measurements at ppb levels by CINAA was <12% for NIST Wheat Flour (SRM 1567) in 5–10 mg samples, while it was <11% for Chinese Hair (HH–CH-1), <13% for IAEA Animal Muscle (H-4) and 25% for IAEA Animal Blood (A-13) in 50 mg samples. The highest relative subsampling uncertainties were observed in the mass range of samples 50 mg for Chinese Hair, 100 mg for Wheat Flour and Animal Muscle and 300 mg for Animal Blood. The results of a one-way analysis of variance indicate that all reference materials above these mass ranges are adequately homogeneous with respect to Se distribution. Our data suggest that these materials, except Animal Blood, can be used as reference standards for Se in Quality assurance programs well below the sample masses re commended by the issuing agencies.

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Abstract  

4-(21-Thiazolylazo) resacetophenone oxime forms a pink colored soluble complex with uranium(VI) in buffer solutions of pH 6.0. The colored complex has a maximum absorbance at the wavelength 572 nm and the color is stable for about 48 h. The system obeys Beer's law over the concentration range 0.2–6.0 g of uranium cm–3. The molar absorptivity and the Sandell sensitivity of the complex are 6.2×104 dm3.mol–1.cm–1 and 0.0038 g cm–2, respectively. Effect of various diversions has been studied and the method was successfully applied for the determination of uranium in rock samples.

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We characterize the normal distribution based on the Q-independence of linear forms based on infinite sequences of Q-independent random variables.

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