Model reduction and clustering techniques for crash simulations

Model reduction in car crash simulations is a fairly new research field. In this paper, a possible workflow is presented: Since nonlinear behavior can occur, parts with linear and nonlinear behavior need to be separated with clustering methods such as k-means or spectral clustering. For the latter, a nonlinear reduction technique such as POD-DEIM needs to be applied. A longitudinal chassis beam of a 2001 Ford Taurus is used to examine the different clustering methods. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solvent-free self-assembly of C60 and cucurbit[7]uril using high-speed vibration milling

The synthesis of a cucurbit[7]uril-[60]fullerene supramolecular complex using a simple, green, and efficient pathway is reported for the first time. In the complex, which was found to be of the 1:2 type, the compounds interact weekly with each other. Since the complexation can be achieved by a solid-solid reaction without solvent both the waste and contact with harmful solvents can be reduced to a minimum. A significant increase of reaction rate and yield compared to the heterogeneous complexation was observed.     

New aromatic musk odorants: Design and synthesis

By appropriate structural modification of known musk odorants, new strong musk odorants have been discovered. Incorporation of supplementary CH₃ or CH₂ groups into the basic musk skeleton of type G only slightly modifies the global shape of the molecule but leads to densely packed structures of enhanced lipophilicity. For the construction of these highly substituted 1,2,3,4-tetrahydronaphthalenes, new annulation sequences (intramolecular mono- and dialkylations; see Schemes 3,6, and 8) have been developed and, in certain cases, the design of the target molecules was dictated by both structure-activity-relationship and synthetic considerations (e.g. 46 and 47 , Scheme 6). This work also presents an original solution to an analytical problem: the distinction between a C₂- and a C_s-symmetrical aromatic hydrocarbon (viz. 71 and 72 ) by conversion into a [Cr(CO)₃arene]complex.     

Formation and structure of the microemulsion phase in two-dimensional ternary AB+A+B polymeric emulsions

We present an analysis of the structure of the fluctuation-induced microemulsion phase in a ternary blend of balanced AB diblock copolymers with equal amounts of A and B homopolymers. To this end, graphical analysis methods are employed to characterize two-dimensional configuration snapshots obtained with the recently introduced field-theoretic Monte Carlo method. We find that a microemulsion forms when the mean curvature diameter of the lamellar phase coincides roughly with the periodicity of the lamellar phase. Further, we provide evidence to the effect of a subclassification of the microemulsion into a genuine and a defect-driven region.     

Formation of Fluorescent and Nonfluorescent Difluoroboron Complexes in the Reaction of BF3Etherate with 21H,24H-Bilin-1,19-dione Derivatives

On reaction with BF₃ etherate, in the presence of base, bile pigments of the biliverdin and 2,3-dihydrobiliverdin type form two kinds of difluoroboron chelates. In one of them, which displays intensive photoluminescence, the boron atom is complexed through the nitrogen atoms of the dipyrrin moiety of the ligand molecule. In the second type of chelates, which have been characterized in the present work for the first time, the boron atom is complexed through the nitrogen atoms of the pyrrole and one of the terminal lactam rings. These BF₂ complexes are devoid of manifest fluorescence. Their ¹H-NMR spectra show clear through-space ¹H-¹⁹T spin-spin couplings that served for structure elucidation. Bile pigment analogs, in which the pyrrolic HN group has been replaced by N-CH₃ or by divalent heteroatoms, such as an O or S atom, form only the latter type of BF₂ chelates.     

Indicator displacement assays as molecular timers

Dynamic mixtures of Rh-dye complexes can be used to determine the history of chemical events such as the addition of ATP and ADP by UV-vis spectroscopy.     

Oxidative Fluorination of Cu/ZnO Methanol Catalysts

The influence of a mild difluorine treatment on Cu/ZnO precatalysts for methanol synthesis was investigated. It led to the incorporation of 1.2…1.3±0.1 wt % fluoride into the material. Fluorination considerably increased the amount of ZnO_x related defect sites on the catalysts and significantly increased the space‐time yields. Although the apparent activation energy E_A,app for methanol formation from CO₂ and H₂ was almost unchanged, the E_A,app for the reverse water‐gas shift (rWGS) reaction increased considerably. Overall, fluorination led to a significant gain in methanol selectivity and productivity. Apparently, also the quantity of active sites increased.