Observations on quasi-uniform products

We prove that any product of quotient maps in the category of quasi-uniform spaces and quasi-uniformly continuous maps is a quotient map. We also show that a quasi-uniformly continuous map from a product of quasi-uniform spaces into a quasi-pseudometric T₀-space depends on countably many coordinates.Furthermore we characterize those quasi-uniformities that are unique in their quasi-proximity class and prove that this property is preserved under arbitrary products in the category of quasi-uniform spaces.     

Confidence Regions on Variance Components in an Extended ANOVA Model for Combining Information

In this paper we consider a general variance components model for combining experiments that allows for a possible interaction of responses with groups. The variance estimate from each experiment cannot take into account this interaction which can additionally be different from experiment to experiment. The interaction term can be interpreted as an additional variance component so that we consider an extended ANOVA model. We derive confidence regions and test of hypotheses on the variance components which – at least approximately – hold the nominal significance level.     

Synthesis and NMD A Antagonistic Properties of the Enantiomers of 4-(3-phosphonopropyl)piperazine-2-carboxylic acid (CPP) and of the unsaturated analogue (E)-4-(3-phosphonoprop-2-enyl)piperazine-2-carboxylic acid (CPP-ene)

The (R)- and (s)-enantiomers of 4-(3-phosphonopropyl)piperazine-2-carboxylic acid (D - and L -CPP, resp.; 15 and 16 , resp.), and of its unsaturated analogue (E)-4-(3-phosphonoprop-2-enyl)piperazine-2-carboxylic acid (D - and L -CPP-ene, resp.; 13 and 14 , resp.) were prepared. The absolute configuration of the enantiomers was determined by a chemical correlation of the menthyl ester 7 with D -asparagine. The affinity of these derivatives for the NMDA receptor was determined by displacement of [³H]CPP in rat cerebral cortical membranes. In two functional tests (the frog hemisected spinal cord preparation and the sodium efflux test from rat brain slices), D -CPP-ene appears to be the most potent, enantiomerically pure, competitive NMDA antagonist known to date.     

Gemischtligandenkomplexe mit N-Acyl-thioharnstoffen: Die Struktur des [N-(Morpholinothiocarbonyl)-benzamidato] (3-amino-2-cyano-n-butyl-dithiocrotonato)nickel(II)

Mixed Ligand Complexes of N-Acyl-thioureas: The Structure of [N-(Morpholinothiocarbonyl)-benzamidato] (3-amino-2-cyano-n-butyl-dithiocrotonato)nickel(II) The reaction of a solution of N-(morpholinothiocarbonyl)benzamide and 3-amino-2-cyano-n-butyl-dithiocrotonate with nickel(II)-acetate tetrahydrate yields the first mixed ligand complex of N-acyl-thioureas. Its structure has been determined by an X-ray structure analysis. The coordination geometry is square planar. Bond lengths and angles are in good agreement with those of other bis and tris N-acyl-thiourea chelates.     

Synthesis and nucleophilic substitution of stable 6-halo-pentafulvenes

The reaction of 2,4-di-t-butyl-cyclopentadiene-1-carbaldehyde with oxalyl chloride or oxalyl bromide provides stable 6-chloro- and 6-bromo-pentafulvenes, respectively. Several nucleophilic displacement reactions of the new compounds are described.     

A new approach towards redispersable polyelectrolyte–surfactant complex nanoparticles

Redispersable and weakly cross-linked block copolymer particles with a core-shell structure were prepared by the use of a macroinitiator. Subsequent sulfonation of the polystyrene core and complex formation with a variety of cationic surfactants led to sterically stabilized, redispersable polyelectrolyte-surfactant complex particles with spherical shape and diameters of about 400 nm. Spontaneous microphase separation of the hydrophobic surfactant tails and the hydrophilic entities of the polyelectrolyte and the surfactant headgroups induces mesostructure formation within the particle cores. The characteristic lengths of the mesostructures formed depend mainly on the chain lengths of the surfactants and vary between 2 and 4 nm. For the first time, preformed nanoparticles were used as constrained nanogeometries for polyelectrolyte-surfactant complex formation.     

Elektrochemische Synthese von Kupfernitrilkomplexen

Electrochemical Synthesis of Copper Nitrile Complexes Electrochemical syntheses of copper nitrile complexes by anodic dissolution of copper and cathodic reduction of malonodinitrile in a one‐step reaction are reported. In the presence of different donors the following compounds are obtained and characterized analytically: {[Cu₂(μ‐CN) · (CH₃CN)₃]CH(CN)₂}_n ( 1 ), {[Cu₂(μ‐CN)(PPh₃)₄]CH(CN)₂}_n ( 2 ) and [Cu₂(μ‐CN)(phen)₂(PPh₃)₂]CH(CN)₂ ( 3 ). As a result of an X‐ray analysis, 3 proved to be an ionic binuclear complex in which the cyano‐bridged Cu^I atoms have distorted tetrahedral coordination sphere. Both the CN group and the dicyanomethanid anion are disordered about centres of inversion.