Etude structurale des sulfotellurures de terres rares (LS)2Te1+x (L = Tb,Dy, Ho,Er, Tm et Y). I. Sous-structure de la phase ordonnée de (HoS)2Te1,34. Structure de la phase desordonnée de (TbS)2Te

The lanthanide sulfotellurides (LS)₂Te_1+x (0 ≤ x < 0.50) show order-disorder phenomena. Above 450°C, they crystallize in a partially disordered structure, orthorhombic with cell parameters a, b, and c close to 4.1, 5.2, and 13.6 Å, respectively. This structure is determined from diffractometer data on a (HoS)₂Te_1.34 crystal (R = 0.061). It is built up along the c axis from (L₄S) tetrahedra layers, separated by Te planes. Disorder and nonstoichiometry are related to the two vacant Te sites.     

The uniqueness of solutions of perturbed backward stochastic differential equations

We prove a result on the preservation of the pathwise uniqueness property for the adapted solution to backward stochastic differential equation under perturbations.     

Gravimetric determination of zirconium with a new azopyrazolone derivative

3-Methyl-5-oxo-1-phenyl-2-pyrazolin-4-ylazo-2'-(6',8'-naphthalenedisulfonic acid) (disodium salt) is proposed as a new reagent for the gravimetric determination of zirconium. The precipitate formed at pH 1–1.5 can be weighed directly and there are few interferences.     

Moclobemide-selective membrane electrode and its pharmaceutical applications

A liquid membrane electrode prepared with moclobemide-dipicrylamine ion-pair complex, dissolved in nitrobenzene as solvent, was studied for analytical performance. The linear response covers the range 10(-3)-10(-6) M moclobemide solution, with a slope of 50.7 mV decade(-1) (pH range 3.5-8). The detection limit is 3 x 10(-7) M. The electrode shows stability, good reproducibility and fast response. The selectivity of the electrode is good. There are two important interfering ions: mianserin and thiamine (Vitamin B(1)). The compression excipients (such as Mg(2+), starch, talcum powder) do not interfere. These characteristics of the electrode enabled it to be used for the determination of moclobemide in drugs and as an active substance, via indirect and direct potentiometric methods. Via an indirect potentiometric method moclobemide, as an active substance, can be determined with an average recovery of 99.96% and a relative standard deviation of 0.85%, and this method can also be used for its determination in drugs with a relative standard deviation of < 2%. The electrode is useful for the determination of the dissolution rate of moclobemide tablets. The physical processes are numerically simulated by typical equations. The apparent first-order rate constants for disintegration and dissolution were calculated.     

Construction and analytical applications of an extractive electrode sensitive to mercury(I)

The construction and characteristics of a new type of extractive electrode sensitive to Hg(2+)(2) are described. The performance of the electrode is compared with that of an ion-selective electrode with mercurous dithizonate as the active substance. The Hg(2+)(2) -extractive electrode contains Pd(HDz)(2) in its membrane. Its stability and sensitivity are remarkable. It has been used as indicator electrode for the titration of halides alone and in mixtures, and for determination of mercury(I), mercury(II), silver, and of substances containing or reacting with mercury. The basis of the electrode response is discussed.     

Analytical contributions to the evaluation of painting authenticity from Princely church of Curtea de Arges

The present study contains the analyses performed for pigment samples taken from the Princely church of Curtea de Arges, one of the oldest churches in Romania. The results of our investigations have shown the source of these samples, thus being identified the pigments: natural ultramarine, cinnabar, red earth, and calcium carbonate in the painting from the 14th century, the pigments: lead white, zinc white, and Prussian blue in the repainting from the 19th century and the pigments zinc white, titanium dioxide white, bone white, yellow ochre, red ochre, green earth, artificial ultramarine, and mars red in the interventions carried out in the 20th century. The analyses consisted of light microscopy (LM) and microchemical tests, as well as energy dispersive X-ray (EDX) analysis. This system of analyses allows one to precisely determine the authenticity of certain pigments, thus avoiding the dating errors for different interventions carried out on the original mural painting from the Saint Nicholas Princely church of Curtea de Arges.     

E ⊗ ϵ Jahn–Teller anharmonic coupling for an octahedral system

The coupling between doubly degenerate electronic states and doubly degenerate vibrations is analyzed for an octahedral system on the basis of the introduction of an anharmonic Morse potential for the vibronic part. The vibrations are described by anharmonic coherent states and their linear coupling with the electronic states is considered. The matrix elements of the vibronic interaction are built and the energy levels corresponding to the interaction Hamiltonian derived. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Polarometrische bestimmung von zirkonium(IV) mit tartrazin

A new polarimetric procedure has been developed for the rapid determination of zirconium in the presence of tartrazin as reagent This determination is possible in the presence of uranium.     

Nachweis von Anthracen und Anthrachinon neben einigen anderen aromatischen Verbindungen

Zusammenfassung Durch Oxydation und Nitrierung mit Mischsäure werden Anthracen und Anthrachinon in Dinitroanthrachinone überführt, die mit Formaldehyd und Natriumhydroxid zu roten Diaminen reduziert werden. Diese werden mit Amylalkohol extrahiert. Die Empfindlichkeit beträgt 2g. Die Färbung wird von Benzol und Homologen, Naphthalin, Phenanthren, Acenaphthen, Fluoren, Chrysen, Acridin und Phenolen, sowie von den im Kokereipech vorhandenen Verbindungen, nicht gegeben.

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Summary Anthracene and anthraquinone are converted by oxidation and nitrification with nitric-sulphuric acid to dinitro anthraquinones which are reduced to red diamines by formaldehyde and sodium hydroxide. These are extracted by amyl alcohol. Sensitivity is 2g. Benzene and its homologues, naphthalene, phenanthrene, acenaphtene, fluorene, chrysene, acridine, phenols and compounds contained in pitch do not interfere with the colour reaction.