Directe Bestimmung der Prote?nstoffe in Futtermitteln

Ohne Zusammenfassung     

Korrosion

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Einen Apparat zur Bestimmung des specifischen Gewichts der Gase, speciell des Leuchtgases

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A note on “Location of hubs in a competitive environment”

This note suggests modifications to two models for locating hubs in a competitive environment introduced by Marianov et al. [European Journal of Operational Research 114 (1999) 363–371]. They make it possible to provide optimal solutions much faster. It is also shown that the implementation of the heuristic proposed by Marianov et al. contains a flaw. Yet the heuristic itself is correct.     

Enantiodivergent Chemoenzymatic Dynamic Kinetic Resolution: Conversion of Racemic Propargyl Alcohols into Both Enantiomers

Natural lipases typically recognize enantiomers of alcohols based on the size differences of substituents near the carbinol moiety and selectively react with the R enantiomers of secondary alcohols. Therefore, lipase-catalyzed dynamic kinetic resolution (DKR) of racemic secondary alcohols produces only R enantiomers. We report herein a method for obtaining S enantiomers by DKR of secondary 3-(trialkylsilyl)propargyl alcohols by using a well-known R-selective Pseudomonas fluorescens lipase in combination with a racemization catalyst VMPS4, in which the silyl group reverses the size relationship of substituents near the carbinol moiety. We have already reported R-selective DKR of the corresponding propargyl alcohols without substituents on the ethynyl terminal carbon, and the presence of an easily removable silyl group has enabled us to produce both enantiomers of propargyl alcohols in high chemical yields and with high enantiomeric excess. In addition, immobilization of the lipase on Celite was found to be important for achieving a high efficiency of the DKR.     

Structural optimization of an asymmetric automotive brake disc with cooling channels to avoid squeal

Brake squeal is still a major issue in the automotive industry due to comfort complaints of passengers and resulting high warranty costs. Many measures to avoid squeal have been discussed in the engineering community reaching from purely passive measures like the increase of damping, e.g. by the application of shims, to the active or semiactive suppression of squeal. While active measures can be effective but are elaborate and therefore more expensive, passive measure are less complex in most cases. This leads to the necessity to develop passive, economic and robust measures to avoid squeal. Asymmetry of the brake rotor has been proposed to achieve this goal and the resulting split of all double eigenfrequencies of the brake rotor has lately been shown to stabilize the system.     

Synthesis and Characterization of Oxazaborinin Phosphonate for Blue OLED Emitter Applications

A blue-light emitting material based on a boron complex containing heteroaromatic phosphonate ligand is synthesized and characterized. The Phospho-Fries rearrangement is used in the synthesis route of the ligand as a convenient method of introducing phosphonate groups into phenols. Structural, thermal and photophysical properties of the resulting oxazaborinin phosphonate compound have been characterized. DFT geometry optimizations were studied as well as the spatial position and symmetry of the HOMO and LUMO. Good thermal stability up to 250 °C enables vacuum deposition methods next to solution processing. Combining the work function with the optical band gap from UV-Vis measurements shows that band alignment is possible with standard contact materials. Photoluminescence reveals an emission peak at 428 nm, which is suitable for a blue light-emitter.     

Parareal for index two differential algebraic equations

Numerical Algorithms - This article proposes modifications of the Parareal algorithm for its application to higher index differential algebraic equations (DAEs). It is based on the idea of applying...     

Hydrogen-Bond Structure and Dynamics of TADDOL Asymmetric Organocatalysts Correlate with Catalytic Activity

The catalytic efficiency of diol-based organocatalysts has been shown to strongly depend on the diols molecular structure including hydrogen-bonding, yet, the underlying molecular-level origins have remained elusive. Herein a study on the inter- and intramolecular hydrogen-bonding of two isomeric diol-based catalysts (TADDOLs) in solution is presented: 1-Naphthyl substituted TADDOL (1nTADDOL), which exhibits high catalytic efficiency, and 2-naphthyl substituted TADDOL (2nTADDOL), which is a poor catalyst. Using nuclear magnetic resonance and infrared spectroscopy, comparable hydrogen-bond strengths for both TADDOLs in solution were found, however, significantly slower bonding dynamics for 1nTADDOL. In aromatic solvents, 1nTADDOL forms less, but longer-lived, intermolecular OH⋅⋅⋅π bonds to solvent molecules, as compared to 2nTADDOL. Thus, rather than previously suggested differences in intermolecular hydrogen-bonding strengths, the results suggest that the hydrogen-bonding kinetics and entropies differ for both TADDOLs, which also explains their vastly different catalytic activities.