Three‐Component Synthesis of Highly Functionalized 5‐Acetyloxazoles

By a flexible three‐component synthesis, alkoxy‐substituted enamides are easily available from lithiated alkoxyallenes, nitriles and carboxylic acids (see scheme). The treatment of these versatile intermediates with trifluoroacetic acid provided 5‐acetyloxazoles in moderate to good yields. Different substituents are possible at C‐2 and C‐5 and the 5‐acetyl group is a suitable handle for further synthetic transformations.

     

Comparing contact and dipolar interactions in a Bose-Einstein condensate

We have measured the relative strength epsilon dd of the magnetic dipole-dipole interaction compared with the contact interaction in a dipolar chromium Bose-Einstein condensate. We analyze the asymptotic velocities of expansion of the condensate with different orientations of the atomic magnetic moments. By comparing the experimental results with numerical solutions of the hydrodynamic equations for dipolar condensates, we obtain epsilon dd = 0.159+/-0.034. We use this result to determine the s-wave scattering length a = (5.08+/-1.06 x 10(-9)) m = (96+/-20) a0 of 52Cr. This is fully consistent with our previous measurements on the basis of Feshbach resonances and therefore confirms the validity of the theoretical approach used to describe the dipolar Bose-Einstein condensate.     

Chemikalien für die Lederherstellung. Vom Kollagen tierischer Häute zum Werkstoff Leder

Leather is a valuable material manufactured from collagen network of hides and skins by suitable chemical and physical processes. The article describes structure and reactivity of the most important leather chemicals, necessary to convert collagen into leather.     

On the influence of aggressive driving behavior on the dynamics of traffic flow

The car following model under discussion is a system of ordinary differential equations describing N cars moving around a circular road. We extend the stability analysis of the model in two directions: variable reaction time (depending on the headway) and an additional part describing the aggressive driving tendency. We study the global bifurcation dynamics and in particular its dependence on these two new ingredients. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Computation of the Delta of European options under stochastic volatility models

Computational Management Science - We employ Malliavin calculus techniques to compute the Delta of European type options in the presence of stochastic volatility. We obtain a general formula for...     

Low Temperature Dry Etching of Graphite Anodes in Hydrogen Glow Discharges

To discribe the temperature dependence of the etching rate of graphite in a hydrogen glow discharge a model is discussed taking into accout the transition from CH₄ to CH as the main etching product with increasing temperature.     

Der Einfluß der Stoßkenndaten auf die Elektronenkinetik in schwachionisierten Mischplasmen

The Influence of the Characteristic Quantities of the Collision Processes on the Electron Kinetics in the Low Ionized Mixture Plasm Starting from former investigations concerning the electron kinetics in the pure molecular plasma of N₂ and H₂ and in the mixtures of N₂/Ne and N₂/H₂ the influence of the important characteristic quantities of the collision processes on the isotropic distribution function and the energy balance of the electrons was studied for binary mixtures. The conclusions obtained were verified by results calculated numerically for the energy balance in the three mixtures He/Ne, N₂/H₂ and N₂/Ne which were investigated in the relevant range of the normalized electric field strength E/p₀ as a function of the mixture ratio. This analysis demonstrates the sensitive dependence of the macroscopic properties of the binary mixtures on the characteristic quantities of the collision processes of the electrons with the two components of the binary mixture.     

The oxidation of carbon monoxide on polycrystalline rhodium under knudsen conditions: I. Reaction with oxygen

The reaction between oxygen and carbon monoxide on a polycrystalline rhodium ribbon under stationary conditions is followed by mass spectrometry. At temperatures from 300–1100 K the ratio of the partial pressures of reactants varies between 0.1 < p_O2/p_CO < 100. The value of the total pressure in the reactor varies between 10^?5 and 10^?4 Torr. The reaction on rhodium shows similar features as in the case of platinum. The results are consistent with a simple elementary reaction sequence but quantitative agreement by model calculations was not obtained.     

Time-resolved detection of atoms diffracted from a standing light wave

We present a time-resolved experimental observation of the diffraction of metastable helium atoms from a nearly resonant standing light wave. The application of a time-resolved detection technique and a pulsed source allows to resolve high diffraction orders, which are populated in the atom-light interaction. Furthermore, the rms momentum transfer from the light field on the atom as a function of the interaction time is investigated. Future applications of this technique may be the detailed investigation of the motion of atoms in standing light waves and the detection of correlations between spontaneously emitted photons and atoms.Dedicated to H. Walter on the occasion of his 60th birthday