Possibilites et limites de l'analyse par activation neutronique multielementaire d'echantillons biologiques avec ou sans separation de la matrice activable

The possibilities and limits of the multi-elemental determinations in biological samples by neutron activation analysis with and without chemical separation are discussed.      

Micelle studies using a metal ion/murexide indicator system

Summary Complex formation between divalent metal ions and the hydrophilic murexide anion in the presence of anionic micelles has been employed to study aspects of micelle formation, the binding of divalent metal ions to micelles, and the kinetics of metal-complex formation in the presence of micelles.

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Zusammenfassung Die Komplexbildung zweiwertiger Metallionen mit dem hydrophilen Indikator Murexid wurde in Gegenwart anionischer Mizellen untersucht. Die Indikatorreaktion wurde benutzt, um Aussagen über Mizellbildung, Bindung zweiwertiger Metallionen an Mizellen und die Kinetik der Metallkomplexbildung bei Anwesenheit von Mizellen zu erhalten.

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With 8 figures and 1 table

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Dedicated to Prof.G. Rehage on the occasion of his 60th birthday.     

Systematik der Seltenerdmetall-Blei-Legierungen

Zusammenfassung Das systematische Verhalten (sowie dessen Fehlen) der Seltenerdmetall-Blei-Legierungen wird untersucht. Es wurden 12 verschiedene Verbindungsstöchiometrien beobachtet. Fast alle dreiwertigen Lanthanidenelemente bilden die PhasenR ₅Pb₃,R ₅Pb₄ undRPb₃. Von den anderen möglichen Stöchiometrien kommen, mit Ausnahme vonRPb₂, nur von einigen Lanthaniden Verbindungen vor. Die bekannten kristallographischen Daten werden durchbesprochen und die Existenz und Nichtexistenz einiger Phasen auf Grund kristallchemischer Theorien diskutiert. Das Schmelzverhalten derR-reichen Eutektika und der PhasenR ₅Pb₃,RPb₂ undRPb₃ wird dargestellt. Die bekannten Informationen über diese Legierungen werden auf der Basis der relativen Volumskontraktionen und des 4f-Beitrags zur Bindung überprüft und die Ergebnisse zu Voraussagen über die relativen Stabilitäten der VerbindungenR ₅Pb₃,RPb₂ undRPb₃ verwertet.

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Systematics of the rare earth-lead alloys

The systematic behavior (and also the lack of it) in the rare earth-lead alloys is examined. Twelve different compound stoichiometries have been observed. Nearly all of the trivalent lanthanide elements form theR ₅Pb₃,R ₅Pb₄, andRPb₃ phases. For the other stoichiometries, except for possiblyRPb₂, compounds exist for only a limited number of the lanthanide elements. The known crystallographic data are reviewed, and the existence and nonexistence of some of the phases are discussed on the basis of crystal chemistry theories. The melting behaviors of theR-rich eutectic and theR ₅Pb₃,RPb₂ andRPb₃ phases are presented. The known information on these alloys is examined on the basis of the relative volume contractions and the 4f contribution to the bonding, and the results are used to predict the relative stabilities of theR ₅Pb₃,RPb₂, andRPb₃ compounds.

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Mit 8 Abbildungen

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Herrn Prof. Dr.H. Nowotny gewidmet.

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Die Arbeiten wurden im Ames-Laboratorium der US-Atomenergie-kommission durchgeführt (Beitrag Nr. 2972).     

Untersuchungen über die Oxydation von Butylbenzol in flüssiger Phase in Gegenwart von Kobalt- und Mangansalzen der Pyridincarbonsäuren

Zusammenfassung Es wurde der Einfluß der Kobalt- und Mangansalze der -, - und -Pyridincarbonsäuren auf die Luftoxydation von Rutylbenzol in flüssiger Phase untersucht. Dabei wurde festgestellt, daß das Kobaltpicolinat, Manganisonicotinat und Kobaltisonicotinat den Oxydationsverlauf zur Bildung von Carbonylverbindungen und Säuren lenken. Das Manganpicolinat weist ein selektives Oxydationsvermögen auf, vorwiegend zur Bildung von Estern.

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Liquid phase oxidation of butyl-benzene in presence of Co and Mn pyridine carboxylates

The influence of Co- and Mn-salts of -, - and -pyridinecarboxylic acids, resp., on the oxidation of butylbenzene by air has been studied. It has been found that the Co salt of picolinic acid, Mn and Co isonicotinate direct the oxidation process in favour of carbonyl compounds and acids. With the Mn salt of picolinic acid, the oxidation mainly gives esters.

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Mit 5 Abbildungen     

Die Kristallstruktur von Perowskiten ANiIIMVIO6. I. Das Sr2[NiTe]O6

The structure of the perovskite compound Sr Ni^IITe^{VI (6)}O₆ (1:1 order in the octahedral sites) is described in detail. The obtained Ni? O distance (2.04 Å a_Te–O = 1.91 Å) together with that one within the corresponding tungsten perovskite (part II) will be analyzed quantitatively with respect to the connection between structure and ligand-field as well as EPR data. The comparison of this distance and the spectroscopic results of the tellurium perovskite with corresponding data of Ni^II-doped MgO however shows already now that an interpretation on the basis of an ionic model is impossible     

Transient analysis of a vibrating reed: Error analysis

The error analysis for the transient vibrating reed test is developed based on a linearized approximation. Tables are given for the efficient utilization of the equations in evaluating the accuracy range of test data.     

An automatic absorptiometric method for the determination of nitrate

A method has been developed for the determination of nitrate with the Technicon Autoanalyser in the range 2–10 p.p.m. The method depends on the reduction of nitrate to nitrite by hydrazine in alkaline solution, with copper as a catalyst. The nitrite produced diazotises sulphanilamide and the product is coupled with N-(1-naphthyl) ethylenediamine, to give a red dye, the absorbance of which is measured at 550 mμ. A relative standard deviation of 3–4% is obtained.     

Spreading of liquid drops over saturated porous layers

Spreading of small liquid drops over thin porous layers saturated with the same liquid is investigated from both theoretical and experimental points of view. A theory is presented that shows that spreading is governed by the same power law as in the case of spreading over a dry solid substrate. The Brinkman's equations are used to model the liquid flow inside the porous substrate. An equation of the drop spreading is deduced, which shows that both an effective lubrication and the liquid exchange between the drop and the porous substrates are equally important. The presence of these two phenomena removes the well-known singularity at the moving three-phase contact line. Matching of the drop profile in the vicinity of the three-phase contact line with the main spherical part of the drop gives the possibility to calculate the pre-exponential factor in the spreading law via permeability and effective viscosity of the liquid in the porous layer. Unfortunately, the latter dependency turns out to be very weak. Spreading of silicone oils over different microfiltration membranes is carried out. Radii of spreading on time experimental dependencies confirm the theory predictions. Experimentally found coefficients agree with theoretical estimations.     

Acid-base properties of 1-acyl-5-hydroxypyrazolidines in a hydrogen bond

In solutions, 1-acyl-5-hydroxypyrazolidines form only intermolecular hydrogen bonds in which the proton acceptor is the oxygen atom of the hydroxyl group. These compounds are similar to phenols with respect to the acidity in a hydrogen bond.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 936–939, July, 1989.