Hydrolysis of polydimethylsiloxane fluids in controlled aqueous solutions.

Accelerated degradation tests were performed on polydimethylsiloxane (PDMS) fluids in aqueous solutions and in extreme chemical conditions (pH 2-4 and 9-12). Results confirmed that silicones can be degraded by hydrolysis. Higher degradation levels were achieved in very acidic and alkaline conditions.

Silicone-based surfactant degradation in aqueous media.

The increasing use of surfactants, such as modified polydimethylsiloxane-graft-polyethylene oxide (PDMS-g-PEO), requires studies on the fate of these compounds in the environment, and in particular in wastewater systems. A kinetic study, performed under three different pH conditions (pH2, 5.3 and 11) and using (1)H NMR (Nuclear Magnetic Resonance), proves that hydrolysis of the siloxane chain takes place in all cases, with higher rates for the two extreme conditions.

[Assessment of sub-clinical thyroid disfunction in aged hospitalized patients in Limousin].

Unlabelled: The aims of the study were to assess the prevalence of sub-clinical thyroid dysfunction in older patients and to analyze morphological and immunological thyroid abnormalities.

Subjects And Methods: The effect of aging on thyroid function morphology and immunology was studied in 102 french patients (70 women and 32 men) with a mean age of 81.7 +/- 7.

Elevated levels of paf-acether in blood of patients with type 1 diabetes mellitus.

Infusion of paf-acether (paf, first described as platelet-activating factor) into animals stimulates glycogenolysis and lipolysis and decreases insulin levels. This study reports a 50-fold increase in blood levels of paf in patients with Type 1 insulin-dependent diabetes mellitus without micro or macrovascular complications (1.07 +/- 0.