RESUMO
A comprehensive study of actinide cation paramagnetism in acidic aqueous solution has been completed in perchlorate media. Employing the Evans method, all the readily accessible actinide cations have been studied using our specially outfitted NMR spectrometer equipped for use with radioactive samples. The effective magnetic moments observed, ranging from 0 to 13 µB, differ from the isoelectronic lanthanides, previous solid actinide studies, and older solution studies. Actinide (IV) and (V) ions show less paramagnetic character, while some actinide (III) ions exhibit greater paramagnetic behavior than predicted from free-ion calculation. Temperature dependence of actinide magnetic susceptibilities from 5 to 80 °C are in good agreement with a Curie-like law except for U(VI), which appears to be temperature-independent. Diamagnetic behavior of Th(IV) exhibits a very low temperature dependence of the magnetic susceptibility. Some explanations for the observations are offered, and the 5f electron behavior is compared to the 4f analogues.
RESUMO
There is renewed interest in the potential contribution of community health workers to child survival. Community health workers can undertake various tasks, including case management of childhood illnesses (eg, pneumonia, malaria, and neonatal sepsis) and delivery of preventive interventions such as immunisation, promotion of healthy behaviour, and mobilisation of communities. Several trials show substantial reductions in child mortality, particularly through case management of ill children by these types of community interventions. However, community health workers are not a panacea for weak health systems and will need focussed tasks, adequate remuneration, training, supervision, and the active involvement of the communities in which they work. The introduction of large-scale programmes for community health workers requires evaluation to document the impact on child survival and cost effectiveness and to elucidate factors associated with success and sustainability.
