Kinetic study of silica gels by a new rheological ultrasonic investigation.

The last decades have seen the development of sol-gel (SG) process currently used to develop new materials in a wide range of scientific applications. The SG process leads to an oxide macromolecular network through a sol (liquid phase) to gel transition. To optimize this process, the control of the kinetic of the chemical reaction is required.

Chirp-Z analysis for sol-gel transition monitoring.

Gelation is a complex reaction that transforms a liquid medium into a solid one: the gel. In gel state, some gel materials (DMAP) have the singular property to ring in an audible frequency range when a pulse is applied. Before the gelation point, there is no transmission of slow waves observed; after the gelation point, the speed of sound in the gel rapidly increases from 0.

[Approaching the gene of mucoviscidosis. New data].

We used 5 polymorphic probes strongly linked to the gene of cystic fibrosis (CF) to perform the genotypical study of 48 families with at least one child presenting with the disease. The last Km19 and XV2c probes showed a very important linkage imbalance with the CF gene (allele 2 = 6.6 kb of Km19/Pstl, chi 2 = 56; allele 1 = 2.