Oxygen Diffusion in Tungsten
INFORMATION concerning oxygen diffusion in tungsten is technologically valuable for many reasons. One such reason is its important role in the development of the structural properties of tungsten for high-temperature applications.
The effects of dilute concentrations of substitutional Re or Os on the thermodynamics and kinetics of oxygen in tungsten
Abstract Tungsten is a candidate material for use in plasma-facing components of fusion reactors. Under operating conditions, transmutation occurs through exposure to neutrons giving rise to rhenium and osmium. Since oxidation is a major operational concern leading to material degradation, it is important to study this issue. In this work, the effects of dilute concentrations of rhenium and osmium on oxygen binding and diffusion in tungsten were investigated using multi-scale modeling. It was determined that the addition of dilute levels of Re or Os (less than 1 at%) led to complex, attractive and long range interactions with the interstitial oxygen. The cases where the interstitial oxygen occupied the 1st, 2nd, and 5th nearest neighboring T-sites were associated with the most favorable binding. Oxygen diffusivity in the material was found to decrease with increasing the substitutional defect concentrations. Finally, osmium was found to have a larger impact on the energy landscape.
As práticas profissionais no campo público de atenção à saúde bucal: o caso de dois municípios da Bahia
This paper examines the working facilities and processes of dentists in the primary healthcare systems of two towns in Bahia State, Brazil, striving to analyze the extent to which factors related to dental care, training, placement and professional profiles influence their practices. Semi-structured interviews were conducted with nine dentists in both towns, with work process organization patterns in Municipality C being closer to the structuring principles of Brazil's National Health System than in Municipality E. This seems to be related to management characteristics, with networking links among individual, collective, and preventive clinical activities and planning noted in Municipality C. Despite these differences, the practitioners presented similarities in terms of dual militancy and perceptions of the public and private healthcare fields. The hegemony of the private sector seems to be influencing the professional practices of dentists in the public health system.