An unprecedented surface oxidation of polystyrene substrates by wet chemistry under basic conditions

The surface of polystyrene substrates has been modified by wet chemistry consisting of a treatment with sodium hydroxide in a water-methanol solution at 50 degrees C for 15 h, under air atmosphere. The resulting samples were analyzed by XPS and AFM. The surface functional groups (hydroxyl and carboxyl functions) were assayed by radiolabeling. All the results are consistent with a surface oxidation process.     

A polyoxometallate-templated coordination polymer: synthesis and crystal structure of [Cu3(4,4'-bipy)5(MeCN)2]PW12O(40).2C6H5CN

The spherical phosphotungstate ion, PW12O40(3-), has been used as a non-coordinating anionic template for the construction of a novel, three-dimensional Cu(I) coordination polymer.     

On labeled vertex-transitive digraphs with a prime number of vertices

We enumerate, up to isomorphism, several classes of labeled vertex-transitive digraphs with a prime number of vertices.     

Trap spectrum taking part in the electroluminescent process

The study of electroluminescence of ZnS powders versus the frequency of the applied voltage, performed at several temperatures, leads to the measurement of trap depths for the traps acting in the impact ionization process. Numerical results are given for ZnS:Mn and ZnS:Cu,Mn samples.     

Electron transfer rates in DNA films as a function of tether length

A homologous series of DNA-modified electrodes has been investigated in which the molecular tether length varies. Using intercalated, covalently bound daunomycin as a redox probe, an exponential dependence of electron transfer rates on the number of intervening methylene groups in the sigma-bonded tether is observed. In contrast, variation in DM position within DNA yields no detectable change in rate. These data confirm that overall electron transfer rates in DNA films are limited by the tether, not the DNA.     

Synthesis of polysubstituted 4-fluoroquinolinones

[reaction: see text] A convenient one-pot synthesis of 4-fluoroquinolinones that are active against KDR kinase is described. The mechanism of the reaction is believed to involve the formation of a quinone methide intermediate.