Simultaneous determination of uranium(IV) and thorium(IV) ions with Arsenazo III by partial least squares method

A multivariate calibration method, Partial Least Squares Type 1 (PLS-1), is proposed for simultaneous spectrophotometric determination of uranium and thorium ions as their complexes with arsenazo III in hydrochloric acid medium. Several data characteristics are taking into account in order to minimize the optimum number of factors required for the construction of calibration model, while using various statistical criterions of selection. Finally, the evaluated calibration model is satisfactorily applied to determination of these ions in samples that resemble sulfuric acid leach solution obtained from a uranium ore.     

On the thermodynamic equivalence of the Dicke maser model and a certain spin system

We prove the thermodynamic equivalence of the Dicke two-level model and a van der Waals spin system. This serves to show that there are cases where the Wang-Hioe procedure and the Power-Zienau transformation may be applied in any order.     

The influence of thiourea on the electroreduction of Zn2+ ions in various supporting electrolytes in respect to the cap-pair effect

The mechanism of the cap-pair effect was examined with respect to its acceleration of the electro-reduction of Zn²⁺ ions in NaCIO₄, NaCl and NaBr. It was found that the presence of thiourea in the solution increased the rate of the electrode process; a role is played in the acceleration by the composition of zinc complexes formed in the bulk of the solution.     

Extension of Bernstein's theorem for polynomial maps of complex Banach spaces

Bernstein's inequality (1) will be extended to polynomial maps of arbitrary complex Banach spaces; cf. (3). We also give conditions for equality in (3). The extension of Bernstein's inequality to the case of polynomial maps of ℂ into ℂ was given byTung [4] and [5].     

Der papierchromatographische Nachweis von ε-Caprolactam neben ε-Aminocapronsäure

Zusammenfassung Die Möglichkeiten der papierchromatographischen Trennung und Identifizierung des Caprolactams neben -Aminocapronsäure wurden untersucht. Die beste Trennung beider Substanzen wurde bei Anwendung wäßrig-alkoholischer Lösungen erzielt. Caprolactam und seine Derivate wurden mit Kaliumwismutjodid identifiziert. Das mit Kaliumwismutjodidreagens gesättigte Filterpapier kann als Indikatorpapier für Caprolactam dienen. Die Empfindlichkeit dieser Reaktion liegt unter 10 g.

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Summary A study was made of the possibilities of the paper chromatographic separation and identification of caprolactam in the presence of -aminocapronic acid. The best separation of the two compounds is from water-alcohol solutions. Caprolactam and its derivatives were identified with potassium bismuth iodide. Filter paper saturated with the potassium bismuth iodide reagent can serve as indicator paper for caprolactam. The sensitivity of this reaction is below 10 g.

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Résumé Recherches sur les possibilités de séparation et d'identification par chromatographie sur papier de la caprolactame en présence de l'acide -aminocaproïque. La meilleure séparation des deux substances est réalisée par l'emploi de solutions hydroalcooliques. La caprolactame et ses dérivés sont identifiés par l'iodure de bismuth et de potassium. Du papier-filtre saturé du réactif iodure de bismuth-potassium peut être utilisé comme papier indicateur de la caprolactame. La sensibilité de cette réaction est inférieure à 10 g.

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Ich fiihle reich verpfhchtet, Herrn Professor J. Poloowicz fiir sein Interesse an meiner Arbeit zu danken.     

Endpoints of set-valued dynamical systems of asymptotic contractions of Meir–Keeler type and strict contractions in uniform spaces

In this paper, we introduce the concepts of the set-valued dynamical systems of asymptotic contractions of Meir–Keeler type and set-valued dynamical systems of strict contractions in uniform spaces and we present a method which is useful for establishing conditions guaranteeing the existence and uniqueness of endpoints of these contractions and the convergence to these endpoints of all generalized sequences of iterations of these contractions. The result, concerning the investigations of problems of the set-valued asymptotic fixed point theory, include some well-known results of Meir and Keeler, Kirk and Suzuki concerning the asymptotic fixed point theory of single-valued maps in metric spaces. The result, concerning set-valued strict contractions (in which the contractive coefficient is not constant), is different from the result of Yuan concerning the existence of endpoints of Tarafdar–Vyborny generalized contractions (in which the contractive coefficient is constant) in bounded metric spaces and provides some examples of Tarafdar–Yuan topological contractions in compact uniform spaces. Definitions and results presented here are new for set-valued dynamical systems in uniform, locally convex and metric spaces and even for single-valued maps. Examples show a fundamental difference between our results and the well-known ones.     

Simulation of a single collision of two bose-einstein condensates

We propose a method for simulating a single realization of a collision of two Bose-Einstein condensates. Recently [Phys. Rev. Lett. 94, 200401 (2005)], we introduced a quantum model of incoherent elastic scattering in a collision of two counterpropagating atomic Gaussian wave packets. Here we show that this model is capable of generating data that can be interpreted as results of a single collisional event. We find a range of parameters, including relative velocity, population, and the size of colliding condensates, where the structure of the halo of scattered atoms in a single realization strongly differs from that averaged over many realizations.     

Self-diffusion and density of liquid hexafluorobenzene as a function of pressure and temperature

Measurements of self-diffusion coefficients to pressures of 2000 bar? 1 bar ≡ 10⁵ N m^-2. and densities to 2600 bar, except where limited by freezing, have been made for liquid hexafluorobenzene C₆F₆ at eight temperatures from 15°C to 150°C. The N.M.R. spin echo technique was used for the self-diffusion measurements, and the densities were determined with a densitometer of the bellows-slidewire type. The density data have been fitted satisfactorily to a modified form of the Tait equation, and the self-diffusion results were reproduced by a polynominal in pressure for each isotherm.

Several models of transport in liquids were evaluated. All models depend sensitively upon a quantity ν-ν₀, the difference between the specific volume of the liquid and that of a hypothetical dense solid. The free volume model describes the data only if ν₀ is allowed to depend upon pressure. The hard sphere model failed to describe our results for C₆F₆ at temperatures above 70°C even when the effective hard sphere diameter was treated as an adjustable parameter.     

Determination of sulfur forms in wine including free and total sulfur dioxide based on molecular absorption of carbon monosulfide in the air–acetylene flame

A new method for the determination of sulfur forms in wine, i.e., free SO₂, total SO₂, bound SO₂, total S, and sulfate, is presented. The method is based on the measurement of the carbon monosulfide (CS) molecular absorption produced in a conventional air–acetylene flame using high-resolution continuum source absorption spectrometry. Individual sulfur forms can be distinguished because of the different sensitivities of the corresponding CS molecular absorption. The sensitivity of free SO₂ is about three times higher than the value for bound SO₂ and sulfate. The method makes use of procedures similar to those used in classic reference methods. Its performance is verified by analyzing six wine samples. Relative standard deviations are between 5 and 13% for free SO₂ and between 1 and 3% for total SO₂. For the validation of the accuracy of the new method, the results are compared with those of reference methods. The agreement of the values for total SO₂ with values of the classic method is satisfactory: five out of six samples show deviations less than 16%. Due to the instability of free SO₂ in wine and the known problems of the used reference method, serious deviations of the free SO₂ results are found for three samples. The evaluation of the limits of detection focuses on the value for free SO₂, which is the sulfur form having by far the lowest concentration in wine. Here, the achievable limit of detection is 1.8 mg L⁻¹. Figure Detection of non-metal elements using continuum source flame absorption spectrometry