The performance of surfactant mixtures at low temperatures

Optimising detergency at lower temperatures is of increasing interest due to environmental and economic factors, and requires a greater understanding of the effects of temperature on the adsorption of surfactant mixtures at interfaces. The adsorption properties of surfactant mixtures and biosurfactant/surfactant mixtures have been studied at room temperatures and at temperatures below ambient using surface tension and neutron reflectivity measurements. For the ternary surfactant mixture of octaethylene monododecyl ether, C12E8, sodium dodecyl 6-benzene sulfonate, LAS, and sodium dioxyethylene glycol monododecyl sulfate, SLES, the surface tension at the air-water interface increases with decreasing temperature. In contrast, there is a notable reduction in the increase in the surface tension with a decrease in temperature from 25 °C to 10 °C for the 5 component rhamnolipid/surfactant mixture of the mono-rhamnose, R1, and di-rhamnose, R2, with C12E8/LAS/SLES. The associated neutron reflectivity data for the ternary C12E8/LAS/SLES mixture and the significant observation is that the 3, 4, and 5-component mixtures containing rhamnolipids in conjunction with the other surfactants show changes in composition and adsorbed amounts of the individual components which are close to the experimental error. However the significant observation is that the neutron reflectivity data indicate that the improved surface tension tolerance at lower temperatures is associated with the dominance of the rhamnolipid adsorption in such mixtures. Hence the introduction of the rhamnolipids provides a tolerance to the adverse effects associated with reduced temperatures, and a potential for improved detergency at relatively low temperatures

The effect of stress and anxiety associated with maternal prenatal diagnosis on feto-maternal attachment

<p>Abstract</p> <p>Background</p> <p>A couple's decision to undergo an invasive test based on a screening test result is a process associated with anxiety. The aim of this study was to determine whether anxiety and prenatal attachment were affected by undergoing an invasive test compared to women in early pregnancy and after a reassuring anomaly scan.</p> <p>Methods</p> <p>200 women were recruited at booking, 14 women and 20 partners after an invasive test and 81 women following an anomaly scan. A questionnaire was completed using the Beck Anxiety Inventory and Maternal or Paternal Antenatal Attachment Scales.</p> <p>Results</p> <p>Women who have had an invasive test have higher levels of anxiety compared to women at booking (P < 0.01) and after an anomaly scan (P = 0.002). Anxiety declines from booking to the time of an anomaly scan (P = 0.025), whilst attachment increases (P < 0.001). There is a positive correlation between anxiety and attachment in women who have had an invasive test (r = 0.479). Partners of women undergoing an invasive test experience lower levels of anxiety (P < 0.05).</p> <p>Conclusions</p> <p>Women undergoing prenatal diagnostic procedures experience more psychological distress, which may be currently underestimated. Establishment of interdisciplinary treatment settings where access to psychological support is facilitated may be beneficial.</p