The formation of the indolizino[1,2-c]quinolinium system by a novel nucleophilic reaction

2-Methyl-3-(2-pyridyl)quinoline (1) with a bromomethyl ketone or ethyl bromoacetate yields 6-methyl-12-acylindolizino[1,2-c]quinolinium bromides ( 5–9 ). The acyl derivatives can be deacylated in acid yielding 6-methyl indolizino[1,2-c]quinolinium salts ( 4 ). Benzoylation of 4 yields the 12-benzoyl derivative ( 6 ). The deacylation product ( 4 ) has been synthesized from 2-acetamidophenacyl bromide ( 10 ) and 2-pyridylacetone ( 12 ).     

Strukurell neuartige 4-phenyl-benzopyran-2-one aus pityrogramma calomelanos (L.) link

From the fern Pityrogramma calomelanos a new Pigment has been isolated and structurally elucidated as a 8- or 6-dihydrocinnamoyl-5,7-dihydroxy-4-phenyl-2H-1-benzopyran-2-one mainly by spectroscopic methods and by comparison with the synthesized monomethyl derivative. From the same plant two other Phenyl-benzopyran-2-one-derivatives with an additional 2-phenyl-γ-pyron (ol)-ring system could be isolated.     

The influence of stereochemistry on the mass spectra of some trimethylsilylated pyranoses

The relative intensities of certain ions in the mass spectra of trimethylsilylated pyranoses have been observed to depend on the stereochemistry of the molecule. A system has been developed which is capable of explaining the differences between the anomeric forms of D-glucose, D-galactose, D-mannose and D-xylose.     

Guarantee structures for problems of fair division

We study the problem of fair division in situations where the number of individuals involved may vary while the resources at their disposal remain fixed. We are interested in minimizing the loss that an agent originally present may incur in such circumstances. Given a solution, i.e., a systematic method of solving any division problem in some class, we introduce the notion of its guarantee structure as a measure of the protection it offers to the original agents. We show that the Kalai-Smorodinsky solution offers greater guarantees than any weakly Pareto-optimal and anonymous solution and in particular than the Nash solution.     

Independence of irrelevant expansions

Nash characterized the only bargaining solution to satisfy a well-known list of axioms. Independence of Irrelevant Alternatives states invariance of the solution outcome under certain contractions of the bargaining problem. A dual of this axiom is proposed here, stating invariance under certainexpansions of the bargaining problem andNash's solution is characerized by substituting this axiom for IIA in Nash's original list. After a transposition from the domain of bargaining solutions to the domain of choice rules, and a weakening of Invariance with respect to Positive Affine Transformations toTranslation Invariance, this new list of axioms is shown to characterizeUtilitarian rules.     

Composite hollow fiber membranes for gas separation: the resistance model approach

A model is developed to explain the behavior of composite gas separation membranes which consist of a porous asymmetric substrate of one polymer, and a coating of a second polymer. An analogy between gas permeation and electrical flow is made, and the various portions of the composite membrane are described in terms of their resistance to gas permeation. It is shown that substrate porosity can vary significantly without altering the separating properties of such a composite, and that substrate and coating properties can be matched to optimize the flux and separation factor. Several major problems previously associated with the development of useful hollow fibers for gas separation are discussed, and it is shown that the use of Resistance Model composites can help to resolve these problems.