Extraction of certain elements from aqueous methanol, ethanol and acetone by tridodecylamine and tributyl phosphate

The extraction of silver, mercury, selenium, zinc, cobalt and iron with tridodecylamine (TDA) and tributyl phosphate (TBP) from hydrochloric acid solutions in aqueous methanol, ethanol and acetone is reported. The presence of these additives increases extraction for some elements and decreases it for others. The effect is generally greater with TDA than with TBP.     

Back titration with mercuric nitrate in alkaline medium

Summary Potentiometric back titration of excess EDTA than required to chelate with gallium or indium using mercuric nitrate as the back titrant provides an excellent method for the determination of amounts of both metal ions in the order of 0.07 to 11 and 0.05 to 18 mg, respectively. The method is further successfully applied for analysis of binary and ternary mixtures of gallium or indium with some other cations using simple procedures.

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Zusammenfassung Gallium oder Indium können in Mengen von 0,07–11 bzw. 0,05 bis 18 mg bestimmt werden, wenn man mit einem überschuß an äDTA versetzt und mit Quecksilber(II)-nitratlösung potentiometrisch zurücktitriert. Auf einfache Weise können auch binäre und ternäre Mischungen von Ga oder In mit einigen anderen Kationen erfolgreich analysiert werden.

     

BackTitration with mercuric nitrate in alkaline medium

Summary Potentiometric back titration of excess EDTA than required to chelate with lanthanum using mercuric nitrate as the back titrant provides an excellent method for the estimation of this metal. By aid of the method amounts of lanthanum in the order of 50 g up to 60 mg were determined with high accuracy in most cases. The method is further successfully applied for analysis of pairs of La with Th, Ba, Hg^II, Mn^II, Cu, Zn, Cd, Ni, Co or Bi using a suitable precipitant or masking agent or selective P_H. NH₄F has proved to be a suitable masking agent for small amounts of lanthanum.See also Z. analyt. Chem. 169, 109 (1959).     

Electrochemical reduction of oxygen at a porous flow-through electrode

The electrochemical reduction of oxygen at a porous flow-through electrode is described with emphasis on the effects of concentration, flow speed and surface area. On a packed bed copper electrode in sulfuric acid, it was found that oxygen undergoes a two electron reduction process giving rise to H₂O₂.     

Quantum Zeno and anti-Zeno paradoxes

Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox). We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure change of state: an anti-Zeno paradox.     

Some Analytical Solutions for Groundwater Flow and Transport Equation

This paper presents the use of symmetry reduction method resulting in new exact solutions for the groundwater flow and transport equation. It is assumed that the radionuclides are transported by advection-diffusion in a single fracture and diffusion in the surrounding rock-matrix. The application of one-parameter group reduces the number of independent variables, and consequently the governing PDE of (1+2)-dimension reduces to set of ODEs which are solved analytically. This enables us to present some new exact time-dependent solutions of the advection-diffusion equation.