Fluctuations in the number of points on smooth plane curves over finite fields

In this note, we study the fluctuations in the number of points on smooth projective plane curves over a finite field Fq as q is fixed and the genus varies. More precisely, we show that these fluctuations are predicted by a natural probabilistic model, in which the points of the projective plane impose independent conditions on the curve. The main tool we use is a geometric sieving process introduced by Poonen (2004) [8].     

Direct imaging of zero-field dipolar structures in colloidal dispersions of synthetic magnetite

Magnetite (Fe3O4) forms the basis of most dispersions studied in the field of magnetic fluids and magnetic colloids. Despite extensive theory and simulations on chain formation in dipolar fluids in zero field, such structures have not yet been imaged in laboratory-made magnetite dispersions. Here, we present the first direct observation of dipolar chain formation in zero field in a ferrofluid containing the largest synthetic single-domain magnetite particles studied so far. To our knowledge, this is the only ferrofluid system available at present that allows quantifying chain length and ring-size distributions of dipolar structures as a function of concentration and particle size.     

Electrogeneration of a poly(pyrrole)-NTA chelator film for a reversible oriented immobilization of histidine-tagged proteins

This contribution reports, for the first time, the synthesis and electropolymerization of a pyrrole N-substituted by a nitrilotriacetic acid acting as a chelating center of Cu2+. A step-by-step approach for protein immobilization was developed via the successive coordination of Cu2+ and histidine-tagged proteins. The self-assembly of histidine-tagged glucose oxidase led to the formation of a close-packed enzyme monolayer at the poly(pyrrole) surface, and the reversibility and reproducibility of this affinity process were demonstrated.     

Highly diastereoselective synthesis and NMR characterization of natural indolizidine alkaloids

A diastereoselective, general and versatile access to disubstituted indolizidines is described. The nmr conformational analysis permits us to establish preferred conformations.     

5-azahexenoyl radicals cyclize via nucleophilic addition to the acyl carbon rather than 5-exo homolytic addition at the imine

Molecular orbital calculations predict that the 5-azahexenoyl radical ring closes via nucleophilic addition to the acyl carbon to afford the 5-exo product; CCSD(T)/cc-pVDZ/ /BHLYP/cc-pVDZ calculations predict energy barriers of 36.1 and 46.9 kJ mol-1 for the exo and endo cyclization modes of the 5-azahexenoyl radical, respectively.