Making the most of matter By probing matter down to the atomic level, science reveals its essential properties. Better understanding of the resistance of materials, new pathways for chemical synthesis, and ceramics with novel optical properties are among the results of this research at the very small scale. 36 Schematic representation of a membrane that has been torn (impact in orange) and immediately repaired by water flowing across it (blue). Novel ceramics with new optical properties Researchers in Orléans have developed an innovative and economical process for the synthesis of transparent polycrystalline ceramics, based on the complete crystallisation of a glass with the same composition as the required crystalline phase. These novel ceramics also display improved optical performance thanks to the addition of various ions (doping). This method opens the way to a host of applications, such as materials for lasers, scintillators and optical lenses, as well as to novel optical properties for these materials. An international patent application has been filed. Advanced Materials August 2012 online Self-healing dynamic membrane Researchers have developed a membrane for water filtration that can self-repair. Made up of an assembly of micelles, macromolecular structures with an affinity for one another, the membrane can repair a tear 85 times greater than its own thickness. In addition, its structure – and hence the size of its pores – varies according to the water pressure flowing through it. It can therefore be used to filter anything from viruses and salts to bacteria and suspended particulate matter. Angewandte Chemie International Edition June 2012 online Nitrenes finally enter the industrial era ------------------------------------------------------------------------------------------------------------------------------------------------------------ Some chemical entities are so unstable that they are only ever observed as reaction intermediates. This is the case for nitrenes, which were thought to be stable only at very low temperatures. Nitrenes are a category of molecules made up of a radical and a nitrogen atom that is so electron-deficient that it is extremely reactive. However, by altering the chemical environment of the nitrogen atom in certain nitrenes, an international team has shown that it is possible to stabilize the molecule and isolate it in crystalline form at room temperature. This finding is particularly interesting because it shows that such nitrenes are able to transfer their nitrogen atom to organic molecules. It therefore opens a new pathway for the synthesis of nitrogen products such as ammonia, a key industrial chemical, and also a host of pharmaceutical compounds in which nitrogen plays a pivotal role in fine-tuning pharmacodynamic properties. No doubt the stable nitrene saga has only just begun. Science September 2012 A year at CNRS 2012
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