Inorganic polar blocks into controlled acentric assemblies.

We show here a strategy to predict the crystal structure, formulate, and prepare new noncentrosymmetric (NCS) bismuth-phosphate based compounds. It is based on the cooperative-arrangement of polar building units (BUs) which can be created at particular stoichiometric conditions. The arrangement of such BUs into NCS compounds arise from the shortest-periodicity of repartition of the cationic charges in NCS structures than in the plausible, but never observed centrosymetric polytypes. This work validates the possibilities for the prediction of an extended series of novel compounds, tuning the size of BUs within a variety of controlled edifices. Despite their closed chemical composition, all the predicted terms appeared strikingly stable at precise stoichiometries.

[Not Available]. / Mise au point d'une methode dynamique d'extraction et de dosage de l'oxyde d'ethylene residuel dans les oxygenateurs et circuits extracorporels.

Ethylene oxide is extracted by circulation with distilled water in a closed circuit at 37 degrees . The circulation time, volume and flow of the water are previously determined as a function of the apparatus characteristics. The extract is analysed either by gas-liquid chromatography (direct injection with propylene oxide as internal standard) or by spectrophotometry. The latter method consists in the periodate oxidation of ethylene glycol in two samples of the same extract, with and without acid hydrolysis, followed by determination of formaldehyde with chromotropic acid. The difference between the absorbances of the two samples gives the quantity of ethylene oxide in the extract. A reasonable correlation of the two sets of results is observed, and the choice between these two simple methods depends on the number of samples to be analysed and on the equipment available. The spectrophotometric method is the longer of the two.