Buchbesprechungen

Ohne Zusammenfassung     

Über die photometrische Bestimmung des Kupfergehaltes eines Eisenmeteoriten

Zusammenfassung Zur Bestimmung kleiner Kupfergehalte in Eisenmeteoriten wurde eine geeignete photometrische Methode ausgearbeitet. Sie beruht auf der Abscheidung des Kupfersulfids mit Schwefelwasserstoff aus der mit Natriumacetat und Monochloressigsäure gepufferten Lösung der Chloride. Die Endbestimmung erfolgt dann durch photometrische Messung der mit Chloroform extrahierten grÜnen Verbindung [Cu(Py)₂] [SCN]₂.Der Kupfergehalt des Mount Joy-Eisenmeteoriten ergab sich auf diese Weise zu 0,032%.

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Summary A suitable method for the determination of small copper contents of iron-meteorites has been elaborated. It is based on the precipitation of copper sulfide with hydrogen sulfide from a solution of chlorides buffered with sodium acetate and monochloric acetic acid. The green compound [Cu(Py)₂] [SCN]₂ extracted with chloroform is finally determined by photometric measurement.By this method the copper contents of the Mount Joy ironmeteorite was found to be 0,032%.

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Résumé On a élaboré une méthode photométrique convenable pour la détermination de petites quantités de cuivre dans des météorites de fer. La méthode est basée sur la précipitation du sulfide de cuivre avec l'hydrogène sulfuré dans une dissolution des chlorures tamponnés avec l'acétate de sodium et acide monochlor-acétique. Le dosage se produit par la mesure photométrique de la combinaison verte [Cu(Py)₂] [SCN]₂ extraite à l'aide de chloroforme. Par cette méthode on trouvait la teneur du météorite de Mount Joy comme 0,032% Cu.

     

The micro-volumetric determination of lead with thionalide and its application to the analysis of tin-base and lead-base alloys

The authors have elaborated an exact micro-volumetric method for the determination of lead with thionalide. The method has been successfully applied to the determination of lead in tin-base and lead-base alloys, following the isolation of lead as lead sulphate and its redissolution in ammonium acetate.     

Practical synthesis of an amphiphilic, non-ionic poly(para-phenyleneethynylene) derivative with a remarkable quantum yield in water

Aggregation of poly(para-phenyleneethynylene)s is efficiently suppressed by introduction of branched oligoethyleneglycol side chains rendering the polymer backbone, which is readily obtained using an A2 + BB' polycondensation protocol, soluble and highly emissive in aqueous environments.     

Error estimates on anisotropic elements for functions in weighted Sobolev spaces

In this paper we prove error estimates for a piecewise average interpolation on anisotropic rectangular elements, i.e., rectangles with sides of different orders, in two and three dimensions.

Our error estimates are valid under the condition that neighboring elements have comparable size. This is a very mild assumption that includes more general meshes than those allowed in previous papers. In particular, strong anisotropic meshes arising naturally in the approximation of problems with boundary layers fall under our hypotheses.

Moreover, we generalize the error estimates allowing on the right-hand side some weighted Sobolev norms. This extension is of interest in singularly perturbed problems.

Finally, we consider the approximation of functions vanishing on the boundary by finite element functions with the same property, a point that was not considered in previous papers on average interpolations for anisotropic elements.

As an application we consider the approximation of a singularly perturbed reaction-diffusion equation and show that, as a consequence of our results, almost optimal order error estimates in the energy norm, valid uniformly in the perturbation parameter, can be obtained.

     

Coherent-state theory for the proton-neutron quasispin group

An extended coherent-state theory ^{1, 2}) is used to give a simple construction for the matrix elements of the proton-neutron sp(4) quasispin algebra. A very simple analytical expression is given for the matrix elements of the sp(4) generators valid for all cases where initial and final states are multiplicity-free with respect to the U(1) × SU(2) n, T subalgebra. In the more general case, involving multiplicity, the most natural orthonormal basis constructed by the coherent-state method leads to many-nucleon states in the seniority scheme which are approximately labelled by T_p, the isospin of the p nucleon pairs coupled to J = 0, T = 1.     

Aktivierungsanalytische Untersuchungen an standardisierten Eisenlegierungen. II

Zusammenfassung Der Gehalt an Kupfer, Arsen, Antimon und Lanthan wurde in den standardisierten Legierungen NBS-1138 (Cast Steel 1) und NBS-1140 (Ductile Iron 1) quantitativ bestimmt, und zwar sowohl zerstörungsfrei als auch nach einer schnellen Gruppentrennung auf extraktionschromatographischem Wege im System Tri-n-octylamin — Salzsäure. Für Kupfer lagen Zertifikatswerte für beide Legierungen vor, für Arsen nur für eine Legierung. Unter Berücksichtigung der angegebenen Unsicherheitsgrenzen zeigten unsere Analysenwerte gute Übereinstimmung mit den Zertifikaten. Zusätzlich, das heißt ohne Zertifikats werte, wurden von uns quantitativ Antimon und Lanthan in beiden Proben, Arsen in einer Probe bestimmt.

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Activation analytical studies of standardized iron alloys. II

Summary The content of copper, arsenic, antimony and lanthanum was quantitatively determined in the standardized alloys NBS-1138 (CaS + Steel 1) and NBS-1140 (Ductile Iron 1), and in fact without destruction and likewise after a rapid group separation by means of a rapid extraction Chromatographic method in the system tri-n-octylamine-hydrochloric acid. Certificated values for copper were available in the case of both alloys, but such values were available for arsenic only in one alloy. Our analytical values showed good agreement with the certificated values if the uncertainties are taken into account. In addition, i. e. with no certificated values, we quantitatively determined antimony and lanthanum in both samples, arsenic in one sample.

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Herrn Prof. Dr. Hans Nowotny zum 60. Geburtstag gewidmet.