Dicyanamido-metal(II) complexes. Part 5: First example for a unit cell containing dinuclear and 1-D polymeric Cu(II) complexes bridging by dicyanamide

The reaction of Cu(ClO₄)₂, N,N,N′,N″,N″-pentamethylethylenetriamine (pmedien) and sodium dicyanamide (Nadca) in aqueous medium led to the isolation of {[Cu(pmedien)(μ_1,5-dca)]₂(ClO₄)₂,[Cu(pmedien)(μ_1,5-dca)]_n(ClO₄)_n} (1). The complex was structurally and magnetically characterized. Single X-ray crystallography for 1 reveals the existence of two independent molecules in the unit cell: dinuclear doubly bridging complex and a 1-D polymeric chain with dca in both cases acting as a μ_1,5-bridging ligand via the terminal nitrile nitrogen atoms. Magnetic susceptibility measurements of the complex showed that the Cu(II) ions are weakly coupled with ferromagnetic interaction in the dinuclear unit (J_d = 0.9 cm^–1) and antiferromagnetic interaction in the polymeric chain (J_c = ? 0.6 cm^? 1).     

Proficiency test on the determination of mineral oil in sunflower oil

Following the discovery of mineral oil contamination of Ukrainian sunflower oil in April 2008, the Institute for Reference Materials and Measurements (IRMM) of the European Commission's Joint Research Centre (JRC) was requested by the Directorate General Health and Consumers (DG SANCO) to organise a proficiency test on the determination of mineral oil in sunflower oil. The aim of this test was to evaluate the comparability of analysis results gained by laboratories in the EU and the Ukraine. The organisation of the study and the evaluation of the results were done in accordance with “The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories” and ISO Guide 43. Altogether 62 laboratories from 19 EU member states, Switzerland and the Ukraine subscribed for participation in the study. Four test samples at concentration levels between about 100 and 350 mg/kg, comprising contaminated crude sunflower oil, contaminated refined sunflower oil, and spiked sunflower oil, and a solution of mineral oil in n‐heptane were dispatched to the participants. The participants were asked to determine the mineral oil content of the test samples by application of their in‐house analysis methods. In total, 55 sets of results were reported to the organisers of the study. The performance of laboratories was expressed by z‐scores for the oil samples and by relative bias for the mineral oil solution in n‐heptane. The percentage of successful laboratories in the determination of the mineral oil content of sunflower oil was for all sunflower oil test materials about 80%.     

Scale‐down des Strahlzonen‐Schlaufenreaktors: Entwicklung eines Screening‐Tools für transportlimitierte chemische Reaktionen

The jet zone loop reactor (JZR) is a high performance loop reactor in which it was shown on different reactions that the use of multiscale transport phenomena leads to a significant increase in the space‐time yield and selectivity. As the use of a JZR in a semi‐industrial scale means a high effort, the development of a comparable screening tool in a laboratory scale is the logical step in which the new technology can be estimated easily and quickly. Experimental hydrodynamic studies of the laboratory reactor showed that significant integral and local parameters are similar to the reactor in semi‐industrial scale, so that the reactor could be used to study a consecutive fast chlorination.     

Alternative Anschlußbewehrung für im Fundament eingespannte Stützen und Wände

Alternative Detail of the Connection Reinforcement for Columns and Walls fixed at the Footing The paper suggests an alternative detail for the connection reinforcement transferring the bending moments at the base of fixed columns and walls to their foundation. In contrast to the typically used interlocking L‐shaped starter bars, the suggested connection reinforcement is in the form of U‐bars, thus greatly improving the constructability. The performance of U‐shaped starter bars was experimentally investigated in two test series and by comparative parameter studies using nonlinear finite element analyses. The results of these investigations are presented and discussed herein.     

Betontechnik für die Stelen des Holocaust‐Mahnmals in Berlin

Summary The 2711 concrete stelae of the Holocaust Memorial erected in the centre of Berlin, have to satisfy high requirements with respect to their appearance and durability. Therefore the invitation to tender provided for a reinforced structural concrete having a minimum compressive strength of 40 MPa and a maximum acceptable crack width of 0.1 mm at the surface of the stelae. Comprehensive analyses on the actions upon the stelae showed that the requirements may be fulfilled significantly more reliable, if no reinforcement is used and if undesired crack formations are restricted only by appropriate concrete technological measures. As a result a dark coloured high‐performance concrete having self‐compacting properties has been developed and used.     

Non-Isothermal NOx Storage/Release over Manganese Based Traps: Mechanistic Considerations

The NO storage properties of MnO _x /support materials (5–50 wt% MnO _x loading) was experimentally investigated in the presence of O₂ and H₂O between 50 and 700 °C applying a non-isothermal temperature-programmed method. In dependence on MnO _x loading and NO supply, the materials show an intermediate decrease of NO storage capacity between 200 and 300 °C. This effect is caused by decomposition of surface nitrites with release of NO into the gas phase as proved by in situ DRIFT measurement. The interpretation is corroborated by modelling of the underlying adsorption/desorption reaction steps, considering the different thermal stability of nitrite/nitrate surface species.