Solution properties of capsular polysaccharides from Streptococcus pneumoniae

Capsular polysaccharides from ten different serotypes of Streptococcus pneumoniae have been studied with regards their hydrodynamic properties in solution, namely their sedimentation coefficient and molar mass distributions, solution conformations and flexibilities (persistence lengths Lp), important properties for the construction of polysaccharide and glycoconjugate vaccines. Sedimentation and molar mass distributions (obtained by sedimentation velocity and equilibrium analysis in the analytical ultracentrifuge supported by size exclusion chromatography coupled to multi-angle light scattering measurements) were generally unimodal, with weight (mass) average molar masses ranging from 100×10(3) to 1300×10(3) g/mol. Estimates of chain flexibilities from three different procedures applied to intrinsic viscosity, sedimentation coefficient and molar mass data, showed that the polysaccharides from all the serotypes studied had semi-flexible structures in solution with persistence lengths in the range from ∼4 to 9 nm.

Discovery of novel and selective tertiary alcohol containing inhibitors of the norepinephrine transporter

A novel series of tertiary alcohol containing 2-substituted benzyl morpholines have been discovered as potent and selective inhibitors of the norepinephrine transporter. Efficient synthetic routes were developed featuring a highly diastereoselective nucleophilic addition of benzyl Grignard reagents to enantiopure (4-benzylmorpholin-2-yl)phenylmethanone (11) as the key synthetic step. In vitro binding affinity for the norepinephrine, dopamine and serotonin transporters and in vivo examination of a select compound (16) in a pharmacodynamic animal model for norepinephrine reuptake inhibition are presented.

Granular flow trapped on an incline: dynamics of the sandpile

Experimental results have been recently reported for the dynamics of two-dimensional sand fronts formed by the trapping of a flow running down an inclined plane. We explain the scaling law observed for the front profiles and give their analytic expression using a simple phenomonelogical model for interfacial shapes and interfacial flows of granular materials.

Random sequential adsorption of binary mixtures on a line

A jamming coverage for the random sequential adsorption of binary mixtures of segments on the infinite line is derived. It always appears to be smaller than the coverage associated with the car parking problem. This has to be contrasted with dicrete models, where the coverage of the lattice by mixtures of segments of different sizes is more efficient than by single species.

Static A+B-->0 annihilation process in arbitrary dimension

The pair annihilation A+B-->0 of static particles distributed at random in a d-dimensional space is studied in the large time regime for a tunneling law. The consequences of a superposition approximation used to close the hierarchy of equations describing the process are analytically explored. It is shown that the density and pair correlations of surviving particles have scaling expressions which display the ordering and clustering effects.