Separation of technetium from rhenium by liquid-liquid extraction with potassium xanthate

A method is described for separating technetium from rhenium in hydrochloric acid medium by liquid-liquid extraction with potassium xanthate and carbon tetrachloride. The effects of the concentration of various acids, concentration of xanthate, different solvents and diverse ions have been investigated.     

Reaction of a diphosphene with various halogens

Bis(2,4,6-tri-$\text{tert}$-butylphenyl) diphosphene reacts with various halogens to give the corresponding phosphoric dihalides, haloarene, and arene depending upon the halogen and solvent used.     

A study on the utilization of the Youden plot to evaluate proficiency test results

Methods of utilizing the Youden plot obtained from interlaboratory comparison tests are proposed. The Youden plot is a powerful tool for visually evaluating between- or within-laboratory errors. However, there are no generally applicable methods to indicate the anomalies in the between- and the within-laboratory errors in qualitative terms. An evaluation frame was therefore developed in this study as an indication method. Moreover, the Youden plot is considered to be useful for visually assessing the comprehensive performance of laboratories using two types of results. Although the confidence ellipse has been proposed in ISO 13528:2005 for this purpose, robust determination of the parameters has not yet been implemented. In the present study, robust determination of one of the parameters, the correlation coefficient, was developed. Our proposals were analytically validated using two types of statistical models. In addition, the properties were evaluated through computational simulations. From the results obtained, it can be concluded that our proposals are practically applicable to actual interlaboratory comparison tests.     

Detecting a sodium chloride ion pair in ice using terahertz time-domain spectroscopy.

The hydrogen bond resonance of a sodium chloride (NaCl) ion pair trapped in aqueous ice has been observed by transmission terahertz time-domain spectroscopy. The absorption peak of a sodium chloride ion pair in ice is 1.65 THz at 83 K. By investigating the interaction of the cation and anion with other chemical compounds, we deduce that the absorption peak originates from the hydrogen bond resonance of sodium chloride and water molecules. The charge redistribution that occurs when other ion pairs are added to aqueous salt solution changes the absorption spectrum. Furthermore, the results also indicate that simple molecules such as sodium halides have fingerprints in the terahertz region when the ions are trapped in ice. NaCl ion pairs in seawater and in Ringer's solution were examined.     

Construction of a portfolio with shorter downside tail and longer upside tail

The purpose of this paper is to propose an algorithm for solving Rachev ratio optimization problem which is intended to construct a portfolio with shorter downside tail and longer upside tail. Moreover, we propose modified Rachev ratio to remove the theoretical flaw of Rachev ratio. Also, we will compare several portfolio models using the market data in Tokyo Stock Exchange. We believe that this paper is of interest to researchers and practitioners in the field of portfolio optimization.     

Linear viscoelastic behavior of perfluorooctyl sulfonate micelles: effects of counter-ions

Linear viscoelastic behavior was investigated for aqueous solutions of perfluorooctyl sulfonate (C₈F₁₇SO⁻ ₃; abbreviated as FOS) micelles having a mixture of tetraethylammonium (N⁺(C₂H₅)₄; TEA) and lithium (Li⁺) ions as the counter-ions. The solutions had the same FOS concentration (0.1 mol l⁻¹) and various Li⁺ fractions in the counter-ions, φ_Li = 0−0.6, and the FOS micelles in these solutions formed threads which further organized into dendritic networks. At T ≤ 15 °C, the terminal relaxation time τ and the viscosity η, governed by thermal scission of the networks, increased with increasing φ_Li up to 0.55. A further increase of φ_Li resulted in decreases of τ and η and in broadening of the relaxation mode distribution. These rheological changes are discussed in relation to the role of TEA ions in thermal scission: Previous NMR studies revealed that only a fraction of TEA ions were tightly bound to the FOS micellar surfaces and these bound ions stabilized the thread/network structures. The concentration of non-bound TEA ions, C_TEA ^*, decreased and finally vanished on increasing φ_Li up to φ_Li ^* ≅ 0.6, and the concentration of the bound TEA ions significantly decreased on a further increase of φ_Li. The non-bound TEA ions appeared to catalyze the thermal scission of the FOS threads, and the observed increases of τ and η for φ_Li < 0.55 were attributed to the decrease of C_TEA ^*. On the other hand, the decreases of τ and η as well as the broadening of the mode distribution, found for φ_Li > 0.55 (where C_TEA ^* ≅ 0), were related to destabilization of the FOS threads/networks due to a shortage of the bound TEA ions and to the existence of concentrated Li⁺ ions. Viscoelastic data of pure FOSTEA and FOSTEA/FOSLi/TEACl solutions lent support to these arguments for the role of TEA ions in the relaxation of FOSTEA/FOSLi solutions. Received: 12 October 1999/Accepted: 1 November 1999     

Maxwell speed distribution and analogue Hawking–Unruh temperature in an ontological model of a Harmonic oscillator ground state

Within an ontological (hidden variable) model of quantum fluctuation, one can discuss the actual   properties of a system regardless (independent) of measurement. Here we apply an ontological model proposed earlier to investigate a Harmonic oscillator in the quantum mechanical ground state. We first show that the actual speed of the oscillator fluctuates randomly following the Maxwell–Boltzmann distribution. On the other hand, the actual energy obeys a broad Gamma distribution with an average 3?ω/2$3?\omega /2$, where ω$\omega$ is the classical angular frequency, so that one may conclude that the outcome of a single energy measurement reveals the average of the actual energy. The distribution of actual speed (energy) thus formally resembles the distribution of speed (energy) of an ideal gas in thermal equilibrium of temperature T_g=?ω/2$T_g=?\omega /2$. We shall then argue that T_g$T_g$ can be written in a form analogous to the Hawking temperature for a Schwarzschild black hole in which the average distance of the oscillator from the origin plays the analogous role of the radius of the black hole event horizon. It can also be written in a form analogous to the Unruh temperature experienced by a body moving with a uniform acceleration. In the analogy, the oscillator suffers an effective acceleration which balances the attractive force of the trapping Harmonic potential, thus keeps its average position away from the origin.     

An efficient and versatile synthesis of all structural types of acylpolyamine spider toxins

An efficient and versatile synthesis of acylpolyamine spider toxins of all structural types classified by extensive MS analysis has been achieved. By using 2-nitrobenzenesulfonamide as an effective activating and/or protecting group (the Nosyl strategy), the naturally occurring toxins 1-8 corresponding to Types A-F were concisely synthesized in high overall yield.