Oxidation of hydroxynaphthalenes by means of Co(III) acetate

1,4-Dihydroxynaphthalene can be quantitatively oxidized to 1,4-naphthoquinone with Co(III) acetate in glacial acetic acid. Analytical determination can be carried out both directly potentiometrically, as well as indirectly using excess of the oxidant and back titrating the unconsumed amount of the reagent with Fe(II) sulfate.     

Caesium salts of titanium,zirconium and thorium cyanoferrates(II)

The synthesis of cyanoferrates of quadrivalent metals and the sorption of caesium ions by these materials have been studied. It has been found that the compositions of the compounds and their properties are strongly influenced by the degree of hydrolysis of the metal. These is no sorption of caesium by Zr⁴⁺ and Th⁴⁺ cyanoferrates, while the compounds of oxygencontaining bivalent complex cations exhibit behaviour similar to that of the other bivalent metals. The sorption of caesium by (TiO)₂R is govermed by an ion-exchange mechanism; with (ZrO)₂R changes occur in the crystal lattice, and (ThO)₂R exhibits a low affinity towards caesium.     

Anwendung von Silicagel in der anorganischen Analyse. Abtrennung des Thoriums von Zirkonium

Zusammenfassung Die Sorption des Thoriums und Zirkoniums an Silicagel aus ÄDTA und Weinsäure wurde verfolgt. Bei ph 7 in Gegenwart von Weinsäure durchläuft das Zirkonium die Silicagelkolonne, während Th(IV) quantitativ sorbiert wird. Diese Tatsache wurde zur Trennung des Thoriums von Zirkonium im Konzentrationsverhältnis 1200 angewandt. Da Zr(IV) aus 0,5-n HCl quantitativ sorbiert wird, woraus die Th(IV)-sorption praktisch gleich Null ist, kann auf diese Weise Zr(IV) von einem beträchtlichen Überschuß an Th(IV) getrennt werden. Die Trennung ist noch im Verhältnis 11000 quantitativ.

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Summary The sorption of thorium and zirconium on silica gel from EDTA and tartaric acid was followed. At ph 7 and in the presence of tartaric acid, the zirconium passes through the silica gel column, whereas Th(IV) is sorbed quantitatively. This finding was employed for the separation of thorium from zirconium in a concentration ratio of 1200. Because Zr(IV) is quantitatively sorbed from 0.5N HCl, while the sorption of Th(IV) is practically zero from this medium, Zr(IV) can be separated from a considerable excess of Th(IV) in this way. The separation is still quantitative at a ratio of 11000.

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Résumé On a suivi l'adsorption du thorium et du zirconium sur silicagel à partir d'EDTA et d'acide tartrique. A pn 7, en présence d'acide tartrique, le zirconium traverse la colonne de silicagel, alors que le thorium-IV est adsorbé quantitativement. On a mis à profit cet état de fait pour séparer le thorium du zirconium pour des concentrations dans le rapport 1200. Comme le zirconium-IV est adsorbé quantitativement à partir d'HCl 0,5N, tandis que l'adsorption du thorium-IV est alors pratiquement nulle, on peut séparer de cette manière le zirconium-IV d'un excès important de thorium-IV. La séparation est encore quantitative pour le rapport 11000.

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Herrn Prof. Dr. Ing.M. Jureek zum 60. Geburtstag gewidmet.     

New methods in synthesis of acetylcholinesterase reactivators and evaluation of their potency to reactivate cyclosarin-inhibited AChE

Nine potential AChE reactivators were synthesized using modification of currently known synthetic pathways. Their potency to reactivate AChE inhibited by cyclosarin nerve agent was tested in vitro. According to the previous results, 1,4-bis(2-hydroxyiminomethylpyridinium)butane dibromide seems to be the most potent AChE reactivator. The reactivation potency of these compounds depends on structural factors such as presence of quaternary nitrogens, length of the linking chain between both pyridinium rings, and position of the oxime moiety at the pyridinium ring.     

Thermal analysis of ternary gypsum-based binders stored in different environments

Although gypsum belongs to the low-energy environmentally friendly binders, its wider applications in building constructions are limited due to the negative effect of moisture on its mechanical properties. When calcined gypsum (CaSO₄·1/2H₂O) transforms into its hydrated form (CaSO₄·2H₂O), it is partially soluble in water and it has a relatively low strength. This problem can be resolved when gypsum is used as a part of binary or ternary binders. In this paper, a system consisting of calcined gypsum, lime, and silica fume is presented as a functional solution for a wider utilization of gypsum in wet environments. For this purpose, the newly designed materials were stored in different environments (laboratory conditions in air or water) up to 182 days. The effect of silica fume on the hydration process and the growth of the main products is evaluated by using differential scanning calorimetry and thermogravimetry in the temperature range from 25 to 1000 °C with a heating rate of 5 °C min^?1 in an argon atmosphere. The carbonation level of studied materials is also evaluated. Besides this, the information about the thermal stability of studied materials is provided. These results are supported by evolved gas analysis, X-ray diffraction, and scanning electron microscopy. The basic physical and mechanical properties are determined to provide more detailed information about the behavior of the designed materials under various conditions at selected days of hydration. The addition of silica fume to the gypsum–lime system activates the pozzolanic reaction of the analyzed pastes, which is proved by the presence of the CSH phase and by the consumption of portlandite in the mixtures. Wet environment speeds up the hydration processes and prevents samples from carbonation.     

Observation of two charged bottomoniumlike resonances in Υ(5S) decays

We report the observation of two narrow structures in the mass spectra of the π(±)Υ(nS) (n=1, 2, 3) and π(±)h(b)(mP) (m=1, 2) pairs that are produced in association with a single charged pion in Υ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M(1)=(10,607.2±2.0) MeV/c2, Γ(1)=(18.4±2.4) MeV, and M(2)=(10,652.2±1.5) MeV/c2, Γ(2)=(11.5±2.2) MeV. The results are obtained with a 121.4 fb(-1) data sample collected with the Belle detector in the vicinity of the Υ(5S) resonance at the KEKB asymmetric-energy e+ e- collider.     

Separation of trace amounts of titanium by the sorption of the titanium peroxocomplex on silica gel

Summary The possibility of the analytical use of the sorption of titanium peroxocomplex on silica gel for the determination of trace amounts of titanium was studied. The exchange capacity of silica gel in dependence on the time and the composition of the titanium peroxocomplex sorbed were described. A simple and very efficient separation procedure has been developed for the determination of traces of titanium in various waters and water-soluble salts.