Synthesis and Stereochemistry of Some new Derivatives of 1,2-O-Cyclohexylidene-α-D-Xylofuranuronic Acid

Abstract

1,2-O-Cyclohexylidene-α-d-xylofuranuronic acid (2) has been converted into its 3-O-acetyl derivative and consecutively to the corresponding acid chloride and ethyl ester. Direct reaction of 2 with ethanol in the presence of p-to-luene sulphonic acid gave the ethyl ester. Reaction of 2 with phosphorus pentachloride in dry ether gave the acid chloride of 1,2-O-cyclohexylidene-3-O-dichlorophosphoryl–α-d-xylofuranuronic acid. Conformational data have been obtained from ¹H and ¹³C NMR measurements.     

Duality for Finite Hopf Algebras Explained by Corings

We give a coring version for the duality theorem for actions and coactions of a finitely generated projective Hopf algebra. We also provide a coring analogue for a theorem of H.-J. Schneider, which generalizes and unifies the duality theorem for finite Hopf algebras and its refinements. This paper was written while the first author visited the Mathematics Departments of Syracuse University and California State University Dominguez Hills. He would like to thank both departments for their hospitality.     

Über die Beständigkeit der alkalischen Phosphatasen der Rattenorgane

Ohne Zusammenfassung     

The polarographic and chronopotentiometric investigation of the copper(II)-ethylenedithioldiacetic acid system

The electrode process of the Cu(II)-ethylenedithioldiacetic acid chelatereduction occurs in two one-electron reduction steps. The reversibility of the first polarographic wave was confirmed by microcoulometry at constant potential. The second wave was found to be quasi-reversible unless the chelate forming agent is present in great excess. The kinetic parameters of these electrode processes were evaluated from the Koutecký and Matsuda-Ayabe theories. The value of activation energy at E=0 vs. NHE, was also found.The chronopotentiometric investigations of the same system gave resultswhich are in good agreement with those obtained polarographically.     

Wetting at the grain boundary in the planar Ising model

In this paper the conditions of pinning of an interface in a 2D Ising ferromagnet with defect connections in a solid-on-solid (SOS) limit are given. It is known that in this case the localisation of interface is formally equivalent to the bound state of quantum particle in temperature dependent effective potential. We show that a wetting transition occurs whenever the couplings on the two sides of the defect are different.     

Semiinvariants for hopf algebra actions

LetH be a Hopf algebra andM a representation or a corepresentation ofH. In this paper we study semiinvariants ofM. This notion generalizes the known concept of weight spaces in the context of representations of Lie algebras. Our best results are attained for pointed Hopf algebras, and semiinvariants which are related to the coradical filtration ofH.     

Positron annihilation anomaly in the high-temperature superconductor YBa2Cu3O7−x

We have measured the ac susceptibility of a wire with a Nb core (1.27 mm diam.) and a Cu cladding (0.37 mm thickness) atT50 K andB0.1 mG. Due to its proximity to Nb, the Cu becomes fully superconducting. From the data we find a breakdown fieldH _b =1.2 (mG) and a coherence length =2.2T ^–1/2 (m) for the Cu, as well as a field penetration depth -34T ^1/2 (m) at the Cu/Nb interface.