Constructing two-weight codes with prescribed groups of automorphisms

We construct new linear two-weight codes over the finite field with q elements. To do so we solve the equivalent problem of finding point sets in the projective geometry with certain intersection properties. These point sets are in bijection to solutions of a Diophantine linear system of equations. To reduce the size of the system of equations we restrict the search for solutions to solutions with special symmetries.Two-weight codes can be used to define strongly regular graphs. We give tables of the two-weight codes and the corresponding strongly regular graphs. In some cases we find new distance-optimal two-weight codes and also new strongly regular graphs.     

Diastereoselective Photochemical Synthesis of α-Amino-β-hydroxyketones by Photocycloaddition of Carbonyl Compounds to 2,5-Dimethyl-4-isobutyloxazole

Summary. The photocycloaddition of aldehydes and α-ketoesters to 2,5-dimethyl-4-isobutyloxazole leads to bicyclic oxetanes with high to moderate (exo) diastereoselectivity that can be easily ring-opened to give α-amino-β-hydroxyketones.     

Membrane-immobilized haptoglobin as affinity matrix for a hemoglobin-A1c immunosensor

An amperometric immunosensor for hemoglobin-A1c (HbA1c) determination has been developed utilizing membrane-immobilized haptoglobin as affinity matrix fixed in front of a Pt-working electrode. The HbA1c assay was carried out in a two-step procedure including the selective hemoglobin enrichment on the sensor surface and the specific HbA1c detection by a glucose oxidase (GOx) labeled anti-HbA1c antibody. Hydrogen peroxide generated by the enzyme label was oxidized at +600 mV versus Ag/AgCl. A standard curve for HbA1c was obtained with a linear range between 0 and 25% HbA1c of total hemoglobin which correspond to 7.8–39 nM. ELISA studies confirmed the advantage of a sandwich-type format with haptoglobin as capture molecule for selective hemoglobin binding over the direct adsorption method. Results by the sandwich immunoassay showed a linear correlation within the clinically relevant range 5–20% (CV < 3). For sensor application the immobilization procedure of haptoglobin onto CDI-activated cellulose membranes was optimized.     

Chiral diphosphine ligands based on camphor: synthesis and applications in asymmetric hydrogenations

The synthesis of a novel class of atropisomer chiral diphosphine ligands with a bornene framework is described. The new ligands showed in Rh catalyzed asymmetric hydrogenation of α- and β-enamides very high ee’s (more than 99%).     

Quasirationale singularitäten

It Is shown that Elkik's results on deformations of rational singularities hold without Cohen-Macaulay assumptions: let f:XS be flat with normal fibres X_s and desingularisations _s:Y_sX_s; then the sets are open for all d.