Involutive Brauer groups of a Krull domain

In this text, we introduce and study involutive class groups and Brauer groups of a Krull domain R. We derive some exact sequences, connecting these groups and linking them to classical invariants, thus allowing to calculate them in concrete situations. We provide a geometric interpretation in terms of etale cohomology with respect to the sheaf of square roots of unity on Spec(R), as another useful tool to calculate these invariants.     

The Direct Conversion of Carboxylic Acids to Carboxamides via Reaction with Unsolvated Bis(Diorganoamino) Magnesium Reagents

It has been found that unsolvated bis (diorganoamino) magnesium compounds react smoothly with carboxylic acids to give the corresponding carboxamides directly in good to excellent yields.     

Numerical calculations of the driving force on an Abrikosov vortex

The driving force on an Abrikosov vortex is calculated numerically from the London equation and involved energies for a vortex perpendicular to the screening current near the surface of a superconductor. Compared with previous analytical derivation of the total force, the partial magnetic, kinematic, and external forces are also obtained so that the nature of the driving force may be deeply discussed. It is shown that the force is neither a Lorentz force nor a Magnus force as often believed and that in order to get a correct result, the image effects and the work done by the applied field must be taken into account. A name of London force is suggested for the driving force. A deep understanding of the nature of the driving force on Abrikosov vortices may also be important in the study of vortex pinning and dynamics in type-II superconductors.     

Aromatische Aminoverbindungen

Ohne Zusammenfassung     

Isomer shifts of sp impurities in metallic hosts

Isomer shifts for¹¹⁹Sn and¹²¹Sb impurities in different metallic hosts are compared. In the frame of the Miedema and van der Woude model three contributions to the isomer shifts due to the charge transfer, electron density mismatch and volume adjustment are calculated.     

Zum Nachweis des Thoriums mit Alizarin S und seine Bestimmung am Ringofen nach Weisz

Zusammenfassung Zum Nachweis des Thoriums bewährte sich als Reagens eine wäßrige, perhydrol- und ammomumnitrathaltige Alizarin S-Lösung. Da Alizarin kein spezifisches Reagens für Thorium ist, wird ein Analysengang beschrieben, der sich zur Entfernung störender Substanzen aus Mineralen eignet. Das dabei erhaltene Thoriumnitrat kann am Ringofen quantitativ bestimmt werden.

---

Summary Aqueous alizarin S solution along with perliydrol and ammonium nitrate was found suitable for the detection of thorium. Since alizarin is not a specific reagent for thorium, an analytical procedure is described, which is suitable for the removal of interfering substances from minerals. The thorium nitrate obtained in this way can be determined quantitatively on the ring oven.

---

Résumé On a utilisé pour la recherche du thorium, une solution aqueuse d'alizarine S avec le perhydrol et le nitrate d'ammonium. Comme l'alizarine n'est pas un réactif spécifique du thorium, on a décrit un procédé d'analyse qui permet l'élimination des substances gênantes à partir des minéraux. On peut doser quantitativement le nitrate de thorium alors obtenu, à l'aide du four annulaire.

---

---

Wir danken an dieser Stelle dem Conselho Nacional de Pesquisas von Brasilien, der uns die Durchführung dieser Arbeiten ermöglicht hat.     

Study of the electron transfer reaction between [Co(EDTA)]− and [Ru(NH3)5py]2+ in methanol–water mixtures

The title reaction was studied in different water–cosolvent (methanol) mixtures. The results have been rationalized employing the Marcus–Hush treatment. To apply this treatment, the true, unimolecular, electron‐transfer rate constants (k_et) were obtained from the experimentally measured rate constants after calculation of the equilibrium constant for the processes of formation of the encounter complex. This calculation was carried out using Eigen–Fuoss (EF) and exponential mean spherical (EMSA) approaches employing effective values of the solvent dielectric constant. These effective values were obtained from the measured association constants corresponding to other ion pairs. The results reveal that in these media there is an additional component of reorganization energy, absent in neat solvents. An explanation of the origin of this component is given. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 658–666, 2009     

The electrochemical behaviour of the altenuene mycotoxin and its acidic properties

The electrooxidation of altenuene (ALT), one of the mycotoxins of the Alternaria alternata genus, on a glassy carbon disk electrode is studied for the first time by using cyclic and square wave voltammetry. From the electrochemical responses, a complex reaction mechanism could be inferred. Values of 1.06×10⁻⁵ cm² s⁻¹, 1.116 V and 2 were determined for the diffusion coefficient, the apparent formal potential and the electron number, respectively, for the overall electrode process by convolution analysis of linear scan voltammograms. Square wave voltammetry was used to generate I_p versus c_ALT* calibration curves for this fungal metabolite. A detection limit of 4.0×10⁻⁷ M was determined for a 2:1 signal to noise ratio. The acid dissociation constant for ALT was determined from conventional UV–vis spectrophotometric measurements. Experimental variations of absorbance as a function of pH at a given wavelength were fitted by using the exact equation that describes the system. Good agreement between the experimental absorbance versus pH plots and the curves generated by the fitting process was found.