Idempotency of Extensions via the Bicompletion

Let Top ₀ be the category of topological T ₀-spaces, QU ₀ the category of quasi-uniform T ₀-spaces, T : QU ₀ → Top ₀ the usual forgetful functor and K : QU ₀ → QU ₀ the bicompletion reflector with unit k : 1 → K. Any T-section F : Top ₀ → QU ₀ is called K-true if KF = FTKF, and upper (lower) K-true if KF is finer (coarser) than FTKF. The literature considers important T-sections F that enjoy all three, or just one, or none of these properties. It is known that T(K,k)F is well-pointed if and only if F is upper K-true. We prove the surprising fact that T(K,k)F is the reflection to Fix(TkF) whenever it is idempotent. We also prove a new characterization of upper K-trueness. We construct examples to set apart some natural cases. In particular we present an upper K-true F for which T(K,k)F is not idempotent, and a K-true F for which the coarsest associated T-preserving coreflector in QU ₀ is not stable under K. We dedicate this paper to the memory of Sérgio de Ornelas Salbany (1941–2005).     

Nontransitive quasi-uniformities in the Pervin quasi-proximity class

We show that each topological space that does not admit a unique quasi-uniformity possesses a Pervin quasi-proximity class containing at least nontransitive members.

     

Kongruenzen zwischen Koeffizienten trigonometrischer Reihen und Klassenzahlen quadratisch imaginärer Körper

Ohne Zusammenfassung Prof.Rolf Nevanlinna gewidmet     

The Ultra-Quasi-Metrically Injective Hull of a T 0-Ultra-Quasi-Metric Space

Jointly with E. Kemajou, in previous work we constructed the so-called Isbell-hull of a T ₀-quasi-metric space. In this article we continue these investigations by presenting a similar construction in the category of T ₀-ultra-quasi-metric spaces and contracting maps. Comparable studies in the area of ultra-metric spaces have been conducted before by Bayod and Martínez-Maurica.     

Reactivity of methacrylates in insertion polymerization

Polymerization of ethylene by complexes [{(P^O)PdMe(L)}] (P^O = κ(2)-(P,O)-2-(2-MeOC(6)H(4))(2)PC(6)H(4)SO(3))) affords homopolyethylene free of any methyl methacrylate (MMA)-derived units, even in the presence of substantial concentrations of MMA. In stoichiometric studies, reactive {(P^O)Pd(Me)L} fragments generated by halide abstraction from [({(P^O)Pd(Me)Cl}μ-Na)(2)] insert MMA in a 1,2- as well as 2,1-mode. The 1,2-insertion product forms a stable five-membered chelate by coordination of the carbonyl group. Thermodynamic parameters for MMA insertion are ΔH(++) = 69.0(3.1) kJ mol(-1) and ΔS(++) = -103(10) J mol(-1) K(-1) (total average for 1,2- and 2,1-insertion), in comparison to ΔH(++) = 48.5(3.0) kJ mol(-1) and ΔS(++) = -138(7) J mol(-1) K(-1) for methyl acrylate (MA) insertion. These data agree with an observed at least 10(2)-fold preference for MA incorporation vs MMA incorporation (not detected) under polymerization conditions. Copolymerization of ethylene with a bifunctional acrylate-methacrylate monomer yields linear polyethylenes with intact methacrylate substituents. Post-polymerization modification of the latter was exemplified by free-radical thiol addition and by cross-metathesis.     

Über periodische Enden mit mehrfach zusammenhängendem Existenzgebiet

Ohne Zusammenfassung     

Transitivity is neither hereditary nor finitely productive

We construct a transitive space that is the union of two subspaces homeomorphic to the (non-transitive) Kofner plane. Moreover, we show that the product of two transitive spaces need not be transitive. Finally, we observe that results of E.K. van Douwen establish that, under b = c, there exists a locally countable locally compact non-transitive zero-dimensional space. It follows that under b = c neither a locally transitive nor a compact space need be transitive.     

A note on sequentially compact quasi-pseudo-metric spaces

It is asked in [3] whether sequential compactness is equivalent to compactness in a quasi-pseudo-metric space. In this note we give a counterexample and a proposition relating to this question.     

Ammonolysis of Nitroarginine and Nitroarginine-Containing Peptides; Some Side Reactions

Ammonolysis of nitroarginine-containing peptides leads to the formation of ornithine-containing side products. The structure of these side products has been deduced from model experiments. This side reaction can be avoided by using the N^G-tosyl or the N^G-dicarbobenzoxy protecting groups.