Quantitative imaging of Ra ultratrace distribution using digital autoradiography: Case of doped celestines.

The ability of the autoradiographic device BeaQuant™ is evaluated herein to quantitatively map the ultratrace element Ra distributed spatially in celestine (SrSO) grains/crystals. Ra doped celestines have been obtained from coprecipitation and recrystallization experiments, and have been characterized with high purity germanium gamma detector (HPGe), giving specific activities ranging from 3251 to 32523 Bq.g.

Nanostructuration of phenylenevinylenediimide-bridged silsesquioxane: from electroluminescent molecular J-aggregates to photoresponsive polymeric H-aggregates.

A new approach to control molecular aggregation of pi-conjugated chromophores in the solid state has been investigated. Our strategy was to use a modifiable bulky fragment which should induce a J-aggregation and offer the possibility to reach an H-aggregation upon its chemical modification by lateral slip of pi-conjugated molecules. The chosen fragment for that purpose was the hydrolyzable triethoxysilane function (Si(OEt)3).

[Ultrasonographic aspect of the rectal wall in liver cirrhosis].

The aim of this study was to assess the ultrasonographic abnormalities of the rectal wall and surrounding structures in patients with cirrhosis and to correlate these findings with endoscopy. From November 1992 to May 1993, 53 cirrhotic patients and 30 control subjects were examined by transrectal ultrasonography and rectoscopy. In addition to rectoscopy and transrectal ultrasonography, patients with cirrhosis underwent an upper gastrointestinal endoscopy.