Liquid–liquid extraction of uranium from Egyptian phosphoric acid using a synergistic D2EHPA–DBBP mixture

Extraction of uranium from Egyptian phosphoric acid with synergistic mixture of di-2-ethylhexylphosphoric acid (D2EHPA) and di-butyl butyl phosphonate (DBBP) is reported in this paper. The influence of various factors such as D2EHPA concentration, DBBP concentration, phosphoric acid concentration, contact time, aqueous: organic phase’s ratio (aq:org) and temperature on the degree of extraction has been established. The data on the effect of temperature on the extraction showed that the enthalpy change is −23.12 kJ/mol. Uranium extracted by D2EHPA–DBBP is further subjected to a second cycle of extraction and scrubbing impurities. The uranium is finally converted to a high purity UO₃ product using precipitation with hydrogen peroxide and heat treatment at 375 °C.     

Chemical studies on uranium extraction from concentrated phosphoric acid by using PC88A and DBBP mixture

The activity concentration of beryllium-7 (⁷Be), a naturally occurring cosmogenic radionuclide produced in the upper atmosphere, was measured in plants on the Loess plateau of China during the growing season of 2005. The ⁷Be mass activity concentration on July 27 ranged from 34.8 to 147.1 Bq kg⁻¹ in herbaceous plants, from 47.6 to 116.1 Bq kg⁻¹ in subshrubs, and from 15.7 to 56.8 Bq kg⁻¹ in crop plants. The ⁷Be mass and areal activity concentrations of a mixture of herbaceous plants increased from 66.8 to 288.7 Bq kg⁻¹ and from 0.7 to 46.5 Bq m⁻², respectively, during the growing season. On an areal basis, the fraction of ⁷Be in plants in the soil–plant system increased from 0.4 to 8.4% during the growing season. Positive linear correlations were found between the increases of ⁷Be mass and areal activity concentrations in the inter-sampling intervals and the amount of precipitation.     

Interplay of information quantifiers and the modified Jaynes-Cummings model

The dynamics of the Buck and Sukumar model (B. Buck and C. V. Sukumar, Phys. Lett. A 81, 132 (1981)) is investigated using different semi-classical information-theory tools. Their interplay reveals somewhat unexpected features. A new signature for the classical-quantum barrier is encountered thereby.     

Entanglement Sudden Death and Sudden Birth in Semiconductor Microcavities

We explore the dynamics of the entanglement in a semiconductor cavity QED containing a quantum well. We show the presence of sudden birth and sudden death for some particular sets of the system parameters.     

Quantum Phase and Nonlocal Correlations for a Three-Level System Interacting with Laser Light in a Nonlinear Kerr Medium Under Decoherence

In this paper, we study the time evolution of the geometric phase and nonlocal correlations for a three-level atom interacting with the quantum field emerged in a nonlinear Kerr medium. We discuss the dependence of the physical quantifiers on the phase damping effect. We examine the effects of the initial state and different system parameters on the evolution of the nonlocal correlation and geometric phase with and without the phase damping effect. Furthermore, we explore the link between the geometric phase and the nonlocal correlation during the time evolution. Finally, we show that the model proposed will be very useful to avoid the phase damping effect by a proper choice of the physical parameters in the field for both cases of the initial pure and mixed states of the three-level atom.     

Dynamical Properties of Some Statistical Quantities for a Quantum System in Generalized Negative Binomial States

We estimate the quantum state of a qubit and a quantized radiation field yielding a generalized negative binomial distribution (GNBD). We give an explicit form for various generalized negative binomial states associated to superposition, even, odd, and q-deformed states. We investigate the dynamical properties of the Mandel parameter as a quantifier of the statistical properties for the radiation field corresponding to its dynamics. We obtain the quantum Fisher information based on the estimation of the atomic state and compare it with the Mandel parameter for different instances of the GNBD. The link between the statistical quantities for different parameters of the GNBD is explored.     

Solvent effect on the kinetics of oxidation of ferrocyanide by lodate in water-methanol mixtures

Summary The kinetics of oxidation of ferrocyanide by iodate ion in water-methanol solvent mixtures have been studied spectro-photometrically in the range 0.0 to 54wt% methanol, at five different temperatures ranging from 10 °C to 30 °C. The rate of reaction is increased with increasing of the methanol content in the mixture. Thermodynamic activation parameters have been calculated. An appropriate mechanism, consistent with the kinetic results, is suggested.     

Inner-sphere oxidation of ternary iminodiacetatochromium(III) complexes involving DL-valine and L-arginine as secondary ligands. Isokinetic relationship for the oxidation of ternary iminodiacetato-chromium(III) complexes by periodate

Background  

In this paper, the kinetics of oxidation of [Cr^III(HIDA)(Val)(H₂O)₂]⁺ and [Cr^III(HIDA)(Arg)(H₂O)₂]⁺ (HIDA = iminodiacetic acid, Val = DL-valine and Arg = L-arginine) were studied. The choice of ternary complexes was attributed to two considerations. Firstly, in order to study the effect of the secondary ligands DL-valine and L-arginine on the stability of binary complex [Cr^III(HIDA)(IDA)(H₂O)] towards oxidation. Secondly, transition metal ternary complexes have received particular focus and have been employed in mapping protein surfaces as probes for biological redox centers and in protein capture for both purification and study.