Nonmonotonic Rayleigh-Taylor instabilities driven by gas-liquid CO2 chemisorption.

Density variations induced by gas absorption in reactive aqueous solutions often trigger buoyancy-induced motions, generally in the form of plumes monotonically sinking into the bulk liquid and enhancing the absorption rate. Here, we contrast two types of CO2-absorbing alkaline solutions, studying their dynamics inside a vertical Hele-Shaw cell by interferometry. While the first one indeed behaves as expected, the second one leads to a quite unusual oscillatory (phase-slipping) dynamics of convective plumes, which moreover does not lead to a significant transfer enhancement. Thanks to a simplified model of momentum and species transport, we show that this particular dynamics is related to a nonmonotonic density stratification, resulting in a stagnant layer close to the interface. Conditions for this to occur are highlighted in terms of the ratios of species' diffusivities and their contribution to density, a classification deemed to be useful for optimizing chemisorption (e.g., for CO2 capture or sequestration) processes.

Families affected by HIV: parents' and children's characteristics and disclosure to the children.

The reduced risk of mother-to-child transmission due to improved HIV treatment has resulted in an increasing number of healthy children born to mothers living with HIV. The study's objective was to identify the number of parents or caregivers in a sample of persons living with HIV in Flanders, the number of HIV-affected children as well as specific family-related characteristics. Using a structured survey quantitative data were assessed on a total of 628 patients at three Flemish Aids reference centres. Qualitative data were collected in a small sub-sample of African caregivers living in Flanders. Twenty-seven per cent of the overall sample had children younger than 18 years, totalling 165 HIV-affected families with 279 children. Parents from developing countries had significantly more children than European parents. One hundred and eighty-two (68%) of all children were HIV-negative, while the HIV status of 75 (28%) was unknown. Disclosure rate was low: 26 (10%) children were aware of the parental HIV disease. The study shows that HIV-affected families have to deal with complex psychosocial issues such as migration, family illness, family secrecy around HIV and disclosure. Service implications are discussed.