Wall-shear-stress and near-wall turbulence measurements up to single pixel resolution by means of long-distance micro-PIV

A digital large-format long-distance micro-particle image velocimetry system (μ-PIV) was developed to measure the wall-shear-stress and the near-wall flow properties in a laminar, transitional and turbulent boundary layer flow along a flat plate, non-intrusively with high accuracy and spatial resolution. To achieve the desired measurement accuracy and spatial resolution, all experimental limitations associated with the seeding, light-sheet, out-of-focus particles, optical aberrations and distortions were successfully solved and various spatial correlation image analysis approaches based on the two-point or single-pixel ensemble correlation were developed, analyzed and compared with the state-of-the-art spatial correlation techniques. The instrument is well suited to prove fundamental fluid mechanical hypotheses such as the universality of the constants κ and B of the logarithmic law. However, for the analysis of flows at large Reynolds and Mach numbers, where small spatial dimensions and strong flow gradients prevent accurate measurements, this technique can be applied as well.     

Synthesis of Stereochemically Flexible Cyclic Biphenylbisphosphinite Ligands: Control of the Dynamics and Selectivity

Novel l -tartaric acid based stereodynamic biphenylbisphosphinite ligands with anilino linkers were prepared as cyclic diamide compounds. The influence of the constitutional substitution pattern of the amino group at the aniline moiety on the diastereoselective formation of the ligand was investigated. While the meta-anilino bridged ligands showed a highly dynamic behavior and no discrimination between (R_ax) and (S_ax) configuration, l -tartaric acid substitution on ortho-anilino bridged ligands leads to diastereoselective self-alignment of the central biphenol axis, which controls the stereoselectivity of the ligand and catalyst. The experimental findings were corroborated by theoretical calculations. In the rhodium-catalyzed enantioselective hydrogenation of methyl 2-acetamidoacrylate (MAA), an enantiomeric ratio of 75 : 25 (R/S) was obtained for the ortho-substituted ligand.     

Idealklassen und Einheiten in kubischen Körpern

Ohne Zusammenfassung     

Zur Bestimmung des Gesammtkohlenstoffs des Harns auf nassem Wege

Ohne Zusammenfassung     

Determining the Gibbs energy of ion transfer across water-organic liquid interfaces with three-phase electrodes.

Ions can be transferred between immiscible liquid phases across a common interface, with the help of a three-electrode potentiostat, when one phase is an organic droplet attached to a solid electrode and containing a redox probe. This novel approach has been used in studies to determine the Gibbs energy of anion and cation transfer, ranging from simple inorganic and organic ions to the ionic forms of drugs and small peptides. This method of studying ion transfer has the following advantages: (1) no base electrolytes are necessary in the organic phase; (2) the aqueous phase contains only the salt to be studied; (3) a three-electrode potentiostat is used; (4) organic solvents such as n-octanol and chiral liquids such as D- and L-2-octanol can be used; (5) the range of accessible Gibbs energies of transfer is wider than in the classic 4-electrode experiments; (6) the volume of the organic phase can be very small, for example, 1 microL or less; (7) the experiments can be performed routinely and fast. Herein, the basic 5 principle is outlined, as well as a summary of the results obtained to date, and a discussion on the theoretical treatments concerning the kinetic regime of the three-phase electrodes with immobilized droplets.     

Karl Fischer-Reagentien ohne Pyridin (7)

Zusammenfassung Unter Verwendung von Imidazol als Base wurden 6 verschiedene Solvent-Formulierungen hergestellt und erprobt. Wir fanden bei allen Formulierungen eine stöchiometrische Reaktion mit Wasser. Sie sind deshalb als KF-Reagentien geeignet. Die Reagentien ermöglichen eine sehr schnelle Titration und geben stabile Endpunkte. Sie scheinen unbeschränkt lagerfähig zu sein.

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Karl fischer reagents without pyridine (7)Two-component reagents containing imidazole

Summary Six different KF-reagents were prepared using imidazole as base component. All reagents give a stoichiometric reaction with water and can be used for the KF-titration. The reagents show a high speed of reaction and lead to stable endpoints. The shelflife seems to be unlimited.

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Teil 6: Fresenius Z Anal Chem (1982) 310:423–426