Characterization of lithographically printed resistive strain gauges
This paper reports progress in sensor fabrication by the conductive lithographic film (CLF) printing process. Work describing strain-sensitive structures manufactured using a modified printing process and conductive inks is addressed. The performance of a "single-ink" strain-sensitive structure when printed on six alternative substrates (GlossArt, PolyArt, Teslin, Mylar C, Melinex, and Kapton) is analyzed. Though not intending to compete with conventional gauges in high-tolerance measurement, the structures exhibit properties that indicate suitability for novel applications.
Thermally induced delay and reversal of liquid film dewetting on chemically patterned surfaces.
A thin liquid film resting on a solid substrate that is heated or cooled from below experiences surface tension gradients, which lead to Marangoni flows. We explore the behavior of such a film on a chemically patterned substrate which drives film dewetting in order to determine how surface patterning and applied temperature gradients can be designed to influence the behavior of thin-film coatings. A nonlinear partial differential equation for the film height based on lubrication theory is solved numerically for a broad range of problem parameters. Uniform cooling of the substrate is found to significantly delay dewetting that is driven by wettability gradients. Uniform heating speeds up dewetting but can destroy the near-perfect templating imposed by the surface patterning. However, localized heating and cooling together can accelerate dewetting while maintaining templating quality. Localized heating and cooling can also be used to drive liquid onto areas that it would dewet from in the absence of heating. Overall, these results indicate that applied temperature gradients can significantly influence dewetting driven by surface patterning, and suggest strategies for the creation of spatially patterned thin-film coatings and flow control in microfluidic devices.
Access to antenatal care and children’s cognitive development: a comparative analysis in Ethiopia, Peru, Vietnam and India
ObjectivesEarly life interventions are considered essential for reducing the burden of health inequalities over the life course. This paper tests this issue empirically focusing on whether access to antenatal care can later reduce children’s health and educational inequalities.MethodsData came from the Young Lives Project for Ethiopia, Peru, Vietnam, and the State of Andhra Pradesh in India. We selected children born in early 2001/2002 and who were followed longitudinally in 2006/2007. We used multilevel mixed effects linear regression models to estimate the parameters of interest.ResultsWe found a positive and significant relationship between mothers’ access to antenatal care and their children’s cognitive development in all countries. In addition, we found a positive and significant relationship between antenatal care and children’s cognitive development for stunted children but only in Peru and Vietnam.ConclusionsWe conclude that (1) antenatal care has the potential to change the negative consequences of early nutritional deficiencies on later cognitive development in Peru and Vietnam; (2) differentials in the quality of antenatal care services could explain the cross-country differentials in the role of early life interventions found here.