A New Method for the Synthesis of 1,2-bis(Pyrrol-2-yl)ethenes

1,2-Bis(2-pyrryl)ethenes were synthesized in high yields by the low-valent titanium mediated reductive coupling of pyrrole-2-carboxaldehydes. The reactions of pyrrole-2-carboxaldehyde under lowvalent titanium conditions were different from those of pyrrole-3-carbonyl compounds.     

Die Bestimmung des Arsens in organischen Verbindungen

Ohne Zusammenfassung     

Die Bestimmung des Kohlenoxydes in atmosph?rischer Luft

Ohne Zusammenfassung(Mitteilung aus dem Havemeyer-Laboratorium der Columbia-Universität, New-York U. S. A.)Aus dem Englischen übersetzt von der Redaktion.     

Copolymerization of sec‐butenyl acetate with styrene via emulsion polymerization

The incorporation of allylic monomers into highly reactive vinyl polymerizations provides a means to control molecular weight, conversion, and Trommsdorff effect to produce copolymers with desirable performance characteristics. The copolymerization behavior of styrene with sec‐butenyl acetate, whose copolymerization properties have not been reported, is investigated. Copolymers were produced via semicontinuous emulsion polymerization and characterized via NMR, gel permeation chromatography, differential scanning calorimetry, dynamic light scattering, and atomic force microscopy. A high degree of chain termination due to allylic hydrogen abstraction was observed, as expected, with resultant decreases in molecular weight and in monomer conversion. However, high conversions were achieved, and it was possible to incorporate high percentages of the allylic acetate comonomer into the polymer chain. Copolymer thermal properties are reported. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3191–3203, 2007     

Algorithms for the q-model clustering problem with application in switching cabinet manufacturing

The model configuration problem (MCP) is a combinatorial optimization problem with application in the telecommunications manufacturing industry. The product is a switching cabinet, defined by a number of positions (slots) in which specific circuit packs are installed according to the customer requirements (configurations). Variety of customer requirements leads to a relatively large number of distinct configurations. In order to streamline the manufacturing process, a large number of switching cabinets with identical configurations (model cabinets) are produced in advance. A customer order is then filled by selecting a model cabinet whose configuration is relatively close to the customer configuration and performing any necessary circuit pack exchanges to make its configuration identical to the customer requirement. The manufacturing costs are proportional to the number of these circuit pack exchanges, and the q-model configuration problem is to design q different model configurations so as to minimize the total number of exchanges for a given collection of customer orders. We propose three heuristic algorithms for solving the q-model configuration problem and carry out a computational experiment to evaluate their effectiveness.     

Detection of Al(III) and Ga(III) complexes with morin by electrospray ionization mass spectrometry.

The Al(III) and Ga(III) complexes formed by morin (M) in aqueous solution were investigated by means of electrospray ionization mass spectrometry (ESI-MS). In the full scan mass spectra, Al:M showed 1:2 and 2:3 stoichiometric ratios. When (S)-N-acetylserine methyl ester (Ser), as a partial mimic of the serine residue in silk, was added to Al:M and Ga:M complexes in aqueous solution, the mass spectra of Ser:Al:M showed 1:1:1 and 1:1:2 stoichiometric ratios. The patterns of the mass spectra of Ga:M and Ser:Ga:M complexes were similar to those for the corresponding Al(III) complexes. Calculated heats of formation of potential structures of the complexes, with and without bound water, were obtained using semiempirical PM3 calculations.     

Uniform Approximation of Functions with Discrete Approximation Functionals

Hoffman, Kouri, and collaborators have calculated nonrelativistic quantum scattering amplitudes by numerically evaluating Feynman path integrals. They observed that the errors introduced by their numerical scheme were uniform in coordinate space, implying that their scheme accurately reproduces both the shape and the phase of functions. Furthermore, they observed that the size and the uniform nature of the errors were preserved when the functions were allowed to evolve in time under the action of the kinetic energy operator. In this paper it is established that these observed properties of the errors are not numerical artifacts but follow from analytical properties of a general class of approximations that include those of Hoffman, Kouri, and collaborators as a special case.     

The Quest for Cold and Ultracold Molecules

Cool molecules: The cooling of molecules to sub‐Kelvin temperatures promises to have a great impact in chemistry and physics. Recently, the first experimental realizations of samples of deeply bound molecules that are approaching the ultracold regime were reported. In this contribution, these interesting results are briefly discussed.