Asymptotic behavior of smooth solutions for partially dissipative hyperbolic systems with a convex entropy

We study the asymptotic time behavior of global smooth solutions to general entropy, dissipative, hyperbolic systems of balance laws in m space dimensions, under the Shizuta‐Kawashima condition. We show that these solutions approach a constant equilibrium state in the L^p‐norm at a rate O(t^{? (m/2)(1 ? 1/p)}) as t → ∞ for p ∈ [min{m, 2}, ∞]. Moreover, we can show that we can approximate, with a faster order of convergence, the conservative part of the solution in terms of the linearized hyperbolic operator for m ≥ 2, and by a parabolic equation, in the spirit of Chapman‐Enskog expansion in every space dimension. The main tool is given by a detailed analysis of the Green function for the linearized problem. © 2007 Wiley Periodicals, Inc.     

The propargylic route as efficient entry to monofluoro and gem-difluoro compounds: mechanistic considerations

The dehydroxy-fluorination of propargylic alcohols occurs with a complete regiocontrol and a good to complete stereocontrol, in contrast to the reactions performed on allylic alcohols. The gem-difluorination of propargylic ketones occurs smoothly in contrast to enones which have a very low reactivity towards DAST or Deoxo-fluor™. It is proposed that the large differences in the stabilization energies of the key carbonium ion intermediates (either propargylic or allylic) could explain these strong differences in reactivity during nucleophilic fluorination. The calculations of isodesmic reactions are in full agreement with this proposal.     

Electrochemical nucleation of gold nanoparticles in a polymer film at a liquid-liquid interface

Simultaneous nucleation of gold nanoparticles and polymerization of tyramine has been carried out at an immiscible electrolyte interface. By transferring the gold ion of tetraoctylammoniumtetracloroaurate (TOAAuCl(4)) from the organic to the aqueous phase, a fast homogeneous electron transfer from the tyramine monomer reduces the gold ion. Electropolymerization then proceeds, and gold nanoparticles form. The newly formed nanoparticles act as nucleation sites for the deposition of the oligomers/polymer (and possibly vice versa). This results in gold nanoparticles stabilized in a polytyramine matrix. The size of the nanoparticles is controlled by the concentration of oligomers/polymer in solution. The polymer nanoparticle composite film was analyzed with TEM, XPS, and AFM.     

Target identification for a promising anti-lupus drug

Target identification is one of the more difficult aspects of modern chemical genetics. In this issue of Chemistry & Biology, Johnson et al. provide a compelling case for going through the trouble. As a byproduct of their identification of the cellular target of an anti-lupus compound, they have uncovered a powerful tool for the characterization of a fascinating molecular machine, the F1F0-ATP synthase.     

Remarkably improved complexation of a bisparaquat by formation of a pseudocryptand-based [3]pseudorotaxane

Significant improvement of complexation of a bisparaquat guest was achieved by the formation of a pseudocryptand-based [3]pseudorotaxane.     

Fluorescence studies of the intra-cellular distribution of zinc bis(thiosemicarbazone) complexes in human cancer cells

The uptake of zinc bis(thiosemicarbazone) complexes in human cancer cells has been studied by fluorescence microscopy and the cellular distribution established, including the degree of uptake in the nucleus.