133 research outputs found
Paramagnetic 18-Valence-Electron Alkylcyclopentadienylnickel(II) Bromide Dimers
No full textThe paramagnetic behavior of 18-electron cyclopentadienylnickel(II) complexes of the [CpNi(mu-Br)](2) type with two unpaired electrons per metal ion has been investigated by H-1 and C-13 NMR spectroscopy of [Cp''Ni(mu-Br)](2) (1; Cp'' = 1,3,4-(Bu3C5H2)-Bu-t), [(CpNi)-Cp-3(mu-Br)](2) (2; Cp-3 = 1,3,4-iPr(3)C(5)H(2)), and [(CpNi)-Cp-4(mu-Br)](2) (3; Cp-4 = 2,3,4,5-iPr(4)C(5)H). The tri-tert-butylcyclopentadienyl derivative 1 crystallizes in the triclinic space group P (1) over bar and has been investigated by X-ray crystallography. Solid-state magnetic susceptibility measurements of 3 revealed an effective magnetic moment at room temperature of 4.04 mu(B),confirming the presence of two d(8) nickel(II) ions. While antiferromagnetic coupling via the bromo bridges is weak (J = 2.4 cm(-1)), zero-field splitting is substantial (D = +48.2 cm(-1)). NMR spectra of complexes 1-3 show signals with half-widths up to 3600 Hz within a spectral window exceeding 500 ppm (H-1) or 2200 ppm (C-13). An analysis of the spectra gave insight into the spin delocalization, the equilibrium orientation of the iPr substituents, and the presence of different conformers of compound 3. Paramagnetic behavior has also been observed for the Cp derivative [Cp Ni(mu-Br)](2) (Cp = C5Me5) by H-1 NMR spectroscopy. The presence of two unpaired electrons is discussed in terms of the weak ligand field originating from the combined interaction of poorly pi accepting allcylcyclopentadienyl and pi donating bromo ligands with the nickel(II) center
Improving Ego-Lane Detection by Incorporating Source Reliability
No full textThis paper presents a framework for robust lane detection towards automated driving using multiple sensors. Since every single source (e.g., camera, digital map, etc.) can fail in certain situations, several independent sources need to be combined. Moreover, the reliability of each source strongly depends on environmental conditions, e.g., existence or visibility of lane markings. Thus, we introduce a concept of estimating and incorporating reliability into the fusion. First, a new sensor-independent error metric is applied to assess the quality of the estimated ego-lanes based on the angle deviation. Secondly, we deploy a boosting algorithm to select the highly discriminant features among the extracted information. Based on the selected features, we apply different classifiers to learn the reliabilities of the sources. Thirdly, we use Dempster-Shafer evidence theory to stabilize the estimated reliabilities over time. Using a big collection of real data recordings from different situations, the experimental results support our concept
Merging Cobalt-Catalyzed C-H Activation with the Mannich Reaction: An Efficient and Modular Approach to a-Substituted Sulfonamides
No full textA three-component synthesis of alpha-substituted sulfonamides from aryl aldehydes, primary sulfonamides and (hetero)arenes is described. This transformation enables a straightforward and modular synthesis of pharmaceutically relevant scaffolds in good yields. The direct functionalization of C(sp2)-H bonds via cobalt-catalyzed C-H-activation offers an appealing and atom-economical alternative to classical methods for the synthesis of alpha-arylated amines such as the Petasis or Mannich-type reactions
Comparison of Euler Calculations with Flight Measurements of the Static Pressure Distribution on a Natural Laminar Flow Nacelle
No full textThe requirement to reduce the specific fuel consumption of future advanced transport aircraft, have resulted in dedicated activities in two fields of aeronautics. In the area of propulsion the current trend in the development of turbofan engines is directed towards higher bypass ratios. In the area of aerodynamics the objective is an extensive laminarization. Since with the higher bypass ratios of the advanced powerplants is associated a growth in the engine nacelle dimensions, not only the skin friction drag rises, but the problem of engine-airframe integration is also intensified due to negative engine-airframe interactions. The paperdeals with the Euler code validation by flight trials with reference to the static pressure distributions on a Natural Laminar Flow nacelle
Identification of essential oils with antioxidant capacity in the genus <i>Mentha</i> L.
No full text14 anhand chemotaxonomischer Merkmale bestimmte Mentha-Arten bzw. Hybriden wiesen hinsichtlich ihrer etherischen Ölgehalte und -zusammensetzungen deutliche Unterschiede auf. In zwei in vitro-Testsystemen zur Prüfung der antioxidativen Kapazität (Lipidperoxidation im Blutplasma und ABTS-Entfärbeassay) erzielten die Öle von Minzen mit höheren D-Germacren-, Piperitonoxid- und Piperitenonoxid-Gehalten gute Ergebnisse. Alle untersuchten Mentha-Spezies zeigten eine grundsätzliche Eignung für den kommerziellen Anbau.14 Mentha species and hybrides classified by their chemotaxonomical characteristics exhibited remarkable differences regarding their essential oil contents and compositions. Oils with higher contents of D-Germacrene, Piperitone-Oxide and Piperitenone-Oxide showed good results in ABTS-Decoloration-Assay and in an assay to observe lipidperoxidation in blood-plasma, which are two in vitro assays to investigate antioxidant capacity. All the Mentha species examined appear to be suitable for commercial cultivation
Anforderungsprofil in der Position des leitenden Krankenhauschirurgen — aus der Sicht des Kostenträgers
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