Formation of radical anions and not deprotonation starts the reaction of gamma-butyrolactone with potassium anions

A mechanism is proposed for the reaction of gamma-butyrolactone with the potassium anion as a two-electron-transfer reagent. Potassium hydride and potassium 4-potassiobutyrate are formed in this process as intermediates. These compounds deprotonate gamma-butyrolactone. Potassium lactone enolate, potassium butyrate, and hydrogen are the final reaction products.     

Systematic Construction of <Emphasis Type="Italic">q</Emphasis>-Analogs of <Emphasis Type="Italic">t</Emphasis>−(<Emphasis Type="Italic">v</Emphasis>,<Emphasis Type="Italic">k</Emphasis>,λ)-Designs

In the present paper we consider a q-analog of t–(v,k,)-designs. It is canonic since it arises by replacing sets by vector spaces over GF(q), and their orders by dimensions. These generalizations were introduced by Thomas [Geom.Dedicata vol. 63, pp. 247–253 (1996)] they are called t –(v,k,;q)- designs. A few of such q-analogs are known today, they were constructed using sophisticated geometric arguments and case-by-case methods. It is our aim now to present a general method that allows systematically to construct such designs, and to give complete catalogs (for small parameters, of course) using an implemented software package. &nbsp; In order to attack the (highly complex) construction, we prepare them for an enormous data reduction by embedding their definition into the theory of group actions on posets, so that we can derive and use a generalization of the Kramer-Mesner matrix for their definition, together with an improved version of the LLL-algorithm. By doing so we generalize the methods developed in a research project on t –(v,k,)-designs on sets, obtaining this way new results on the existence of t–(v,k,;q)-designs on spaces for further quintuples (t,v,k,;q) of parameters. We present several 2–(6,3,;2)-designs, 2–(7,3,;2)-designs and, as far as we know, the very first 3-designs over GF(q).classification 05B05     

Estergruppenhaltige Polyalkenylene durch Olefin-Metathese

Ohne Zusammenfassung     

Polarisationseffekte des Fluoreszenzlichtes von Anthrazenkristallen und Plastikszintillator in Abhängigkeit von Deuteronenenergie und Temperatur

Investigations of the optical isotropic plastic scintillator showed that the fluorescence light is more polarized perpendicular than parallel to the particle impact direction. Furtheron the fluorescence light polarization of anthracene crystals proved to be dependent on particle impact direction. Both the degree of fluorescence light polarization of plastic scintillator and the dependence of fluorescence light polarization of anthracene crystals could be explained by the mechanism of energy travelling from direct excited to light emitting molecules.     

Synthese und Charakterisierung von Copolymeren aus Azo-Initiatoren und Styrol

Ohne Zusammenfassung     

Rank-based classifiers for extremely high-dimensional gene expression data

Predicting phenotypes on the basis of gene expression profiles is a classification task that is becoming increasingly important in the field of precision medicine. Although these expression signals are real-valued, it is questionable if they can be analyzed on an interval scale. As with many biological signals their influence on e.g. protein levels is usually non-linear and thus can be misinterpreted. In this article we study gene expression profiles with up to 54,000 dimensions. We analyze these measurements on an ordinal scale by replacing the real-valued profiles by their ranks. This type of rank transformation can be used for the construction of invariant classifiers that are not affected by noise induced by data transformations which can occur in the measurement setup. Our 10 \(\times \) 10 fold cross-validation experiments on 86 different data sets and 19 different classification models indicate that classifiers largely benefit from this transformation. Especially random forests and support vector machines achieve improved classification results on a significant majority of datasets.     

Arrangements on Parametric Surfaces II: Concretizations and Applications

We describe the algorithms and implementation details involved in the concretizations of a generic framework that enables exact construction, maintenance, and manipulation of arrangements embedded on certain two-dimensional orientable parametric surfaces in three-dimensional space. The fundamentals of the framework are described in a companion paper. Our work covers arrangements embedded on elliptic quadrics and cyclides induced by intersections with other algebraic surfaces, and a specialized case of arrangements induced by arcs of great circles embedded on the sphere. We also demonstrate how such arrangements can be used to accomplish various geometric tasks efficiently, such as computing the Minkowski sums of polytopes, the envelope of surfaces, and Voronoi diagrams embedded on parametric surfaces. We do not assume general position. Namely, we handle degenerate input, and produce exact results in all cases. Our implementation is realized using Cgal and, in particular, the package that provides the underlying framework. We have conducted experiments on various data sets, and documented the practical efficiency of our approach.     

Polypropylene,modified with some oligoesters

Miscibility of polypropylene with some oligoesters was evaluated by optical wedge interference microscopy. Mechanical, thermal, rheological and relaxation properties were studied. Compatibility between the polymers and modifying agents was shown to have a marked effect on stress-strain properties as well as on the structure and melting characteristics of the modified polymers.