Gaschromatographischer Vergleich verschiedener Branntweine

Zusammenfassung Durch Direktinjektion von 5–20 l verschiedener Branntweine wurden auf gaschromatographischen Trennsäulen in Verbindung mit Flammenionisationsdetektoren die Verbindungen Acetaldehyd, Essigsäure-methylester, Essigsäure-äthylester, Methanol, Butanol-2, Propanol-1, 2-Methylpropanol-1, Butanol-1, 2-Methyl-butanol-1, 3-Methyl-butanol-1 und Hexanol-1 aufgetrennt und quantitativ bestimmt. Vergleiche der Analysenzahlen zeigen, daß sich die Branntweingruppen Obstbrände, Weinbrände und Getreidebrände deutlich voneinander abgrenzen und darüber hinaus z.B. zwischen Cognacs und Weinbränden bzw. zwischen schottischen, amerikanischen und kanadischen Whiskies unterschieden werden kann.

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Summary By direct injection of 5–20 l of various spirits the following compounds can be separated and determined on gas-chromatographic columns using flame-ionization detectors: acetaldehyde, methyl acetate, ethyl acetate, methanol, butanol-2, propanol-1, 2-methyl-propanol-1, butanol-1, 2-methyl-butanol-1, 3-methyl-butanol-1 and hexanol-1. A comparison of the analytical results reveals distinct differences between spirits from fruit, wine and grain. Moreover, different analytical results are obtained for cognacs and (German) brandies, and for Scotch, American and Canadian whiskies.

     

A linearized Eulerian sound propagation model for studies of complex meteorological effects

Outdoor sound propagation is significantly affected by the topography (including ground characteristics) and the state of the atmosphere. The atmosphere on its part is also influenced by the topography. A sound propagation model and a flow model based on a numerical integration of the linearized Euler equations have been developed to take these interactions into account. The output of the flow model enables the calculation of the sound propagation in a three-dimensionally inhomogeneous atmosphere. Rigid, partly reflective, or fully absorptive ground can be considered. The linearized Eulerian (LE) sound propagation model has been validated by means of four different scenarios. Calculations of sound fields above rigid and grass-covered ground including a homogeneous atmosphere deviate from analytic solutions by < or = 1 dB in most parts of the computed domain. Calculations of sound propagation including wind and temperature gradients above rigid ground agree well with measured scale model data. Calculations of sound propagation over a screen including ground of finite impedance show little deviations to measured scale model data which are probably caused by an insufficient representation of the complex ground impedance. Further calculations included the effect of wind on shading by a screen. The results agree well with the measured scale model data.     

A highly water-soluble 2:1 beta-cyclodextrin-fullerene conjugate

A novel 2:1 (permethylated-beta-cyclodextrin)-fullerene conjugate has been synthesised; highly soluble in cold water with formation of aggregates, it displays a negative solubility coefficient and has a partition coefficient between octanol and water (Log P = 1.58) in the suitable range for biological studies.     

Adsorbate band dispersions for C on Ru(0001)

We have studied carbon-induced two-dimensional energy bands on Ru(0001) using angleresolved photoelectron spectroscopy and have compared them with ab initio calculations. We find a nearly parabolic band (bottom at E_F ?9.8 eV at k_∥ = 0, effective mass ～ 1.5 m_e) which we assign to the C 2p_z valence states of a graphitic carbon overlayer. Compared to graphite, these states are bound more tightly by 2.3 eV.     

Band-selective measurements of electron dynamics in VO2 using femtosecond near-edge x-ray absorption

We report on the first demonstration of femtosecond x-ray absorption spectroscopy, made uniquely possible by the use of broadly tunable bending-magnet radiation from "laser-sliced" electron bunches within a synchrotron storage ring. We measure the femtosecond electronic rearrangements that occur during the photoinduced insulator-metal phase transition in VO2. Symmetry- and element-specific x-ray absorption from V2p and O1s core levels (near 500 eV) separately measures the filling dynamics of differently hybridized V3d-O2p electronic bands near the Fermi level.     

Observing photochemical transients by ultrafast x-ray absorption spectroscopy

Accurate determination of the transient electronic structures, which drive photochemical reactions, is crucial in chemistry and biology. We report the detection of transient chemical changes on the picosecond time scale by x-ray-absorption near-edge structure of photoexcited aqueous [Ru(bpy)(3)](2+). Upon ultrashort laser pulse excitation a charge transfer excited state having a 300 ns lifetime is formed. We detect the change of oxidation state of the central Ru atom at its L3 and L2 edges, at a temporal resolution of 100 ps with the zero of time unambiguously determined.