Interfacial instability of two layers of thin (<100-nm) immiscible liquid films on a solid substrate is studied using the long-wave equations. Instability is derived from the van der Waals interactions among the substrate and the films. The stability characteristics are classified on the basis of the different combinations of surface tensions of the liquid layers and the solid. Depending on the surface tensions and the film thicknesses, two distinct modes of instability, namely, squeezing and bending, are manifested. Nonlinear simulations are presented to describe the various modes of initial evolution and film rupture in such systems.

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The purpose of this study was to determine levels of oral health knowledge and factors associated with adequate oral health knowledge in adults with diabetes. A convenience sample of 253 adult US residents with diabetes completed an oral health survey to assess their knowledge. Results showed that only 47% of the participants answered five or more (out of a maximum of seven) oral health knowledge items related to diabetes correctly. Participants who received oral health information related to diabetes have 2.9 times the odds of possessing adequate oral health knowledge (i.e., answered five or more items correctly) compared to participants who did not received that information controlling for education and race (OR = 2.86, 95% CI 1.26-6.24, P = 0.008). Given that oral health information provided by health professionals (dental and/or medical) contributes to improve oral health knowledge among adults with diabetes, health professionals should take the opportunity to educate patients with diabetes about the oral manifestations (e.g., dry mouth) and complications (e.g., periodontitis and oral candidiasis) of diabetes and to promote proper oral health behaviors.

A long-wave nonlinear analysis of dewetting of thin (<100 nm) liquid bilayers on solid substrates is presented. The short and the long time dynamics, interfacial morphologies, and the pathways of rupture and dewetting are studied to assess the roles of interfacial energies, film thicknesses, and viscosities. The twin interfaces (liquid-liquid and liquid-air) of bilayers under the influence of attractive van der Waals forces show a variety of dewetting pathways which, depending on the interfacial energies and film thicknesses, initially start with one of the two basic modes of instability--in-phase bending and out-of-phase squeezing. These short time modes of evolution and the extent of relative deformations at the interfaces are predicted from the linear stability analysis and verified by the nonlinear simulations. Simulations also show that in the later nonlinear regime, the intermolecular and viscous forces can profoundly modify the initial mode of instability and its growth rate leading to different pathways of dewetting and late stage morphologies. The complex late time patterns such as embedded droplets, inversion of top and bottom phases, and encapsulation of one fluid into the other are also engendered by tuning the intermolecular forces.

A Pd nanoparticle‐containing polymer microsphere moves with increasing speed across a pH gradient, following differential catalytic decomposition of aqueous hydrogen peroxide. The directional motion is akin to the pH taxis of living microorganisms. The artificial pH taxis exhibits random walk, translation, vertical, hopping, and pulsed motion, when the size of the motor and the imposed pH gradient are modulated.