Controlling the spacing of the linked graphene oxide system with dithiol linkers under confinement.

2D nanoscale confined systems exhibit behavior that is markedly different from that observed at the macroscale. Confinement can be tuned by controlling the interlayer spacing between confining layers using organic dithiol linkers. Adjusting spacing and selective intercalation have important impacts for catalysis, superconductivity, spin engineering, sodium ion batteries, 2D magnets, optoelectronics, and many other applications.

Photocatalytic CO Reduction with Dissolved Carbonates and Near-Zero CO(aq) by Employing Long-Range Proton Transport.

Photocatalytic CO reduction (COR) in ∼0 mM CO(aq) concentration is challenging but is relevant for capturing CO and achieving a circular carbon economy. Despite recent advances, the interplay between the CO catalytic reduction and the oxidative redox processes that are arranged on photocatalyst surfaces with nanometer-scale distances is less studied. Specifically, mechanistic investigation on interdependent processes, including CO adsorption, charge separation, long-range chemical transport (∼100 nm distance), and bicarbonate buffer speciation, involved in photocatalysis is urgently needed.

Erratum: Obtaining self-similar scalings in focusing flows [Phys. Rev. E 92, 043016 (2015)].

This corrects the article DOI: 10.1103/PhysRevE.92.

Constitutive relation for the system-spanning dynamically jammed region in response to impact of cornstarch and water suspensions.

We experimentally characterize the impact response of concentrated suspensions consisting of cornstarch and water. We observe that the suspensions support a large normal stress-on the order of MPa-with a delay after the impactor hits the suspension surface. We show that neither the delay nor the magnitude of the stress can yet be explained by either standard rheological models of shear thickening in terms of steady-state viscosities, or impact models based on added mass or other inertial effects.

System-spanning dynamically jammed region in response to impact of cornstarch and water suspensions.

We experimentally characterize the structure of concentrated suspensions of cornstarch and water in response to impact. Using surface imaging and particle tracking at the boundary opposite the impactor, we observed that a visible structure and particle flow at the boundary occur with a delay after impact. We show the delay time is about the same time as the strong stress response, confirming that the strong stress response results from deformation of the dynamically jammed structure once it spans between the impactor and a solid boundary.

Testing constitutive relations by running and walking on cornstarch and water suspensions.

The ability of a person to run on the surface of a suspension of cornstarch and water has fascinated scientists and the public alike. However, the constitutive relation obtained from traditional steady-state rheology of cornstarch and water suspensions has failed to explain this behavior. In another paper we presented an averaged constitutive relation for impact rheology consisting of an effective compressive modulus of a system-spanning dynamically jammed structure [R.

Highly stiff yet elastic microcapsules incorporating cellulose nanofibrils.

Microcapsules with high mechanical stability and elasticity are desirable in a variety of contexts. We report a single-step method to fabricate such microcapsules by microfluidic interfacial complexation between high stiffness cellulose nanofibrils (CNF) and an oil-soluble cationic random copolymer. Single-capsule compression measurements reveal an elastic modulus of 53 MPa for the CNF-based capsule shell with complete recovery of deformation from strains as large as 19%.

Obtaining self-similar scalings in focusing flows.

The surface structure of converging thin fluid films displays self-similar behavior, as was shown in the work by Diez et al. [Q. Appl.

Packings of deformable spheres.

We present an experimental study of disordered packings of deformable spheres. Fluorescent hydrogel spheres immersed in water together with a tomography technique enabled the imaging of the three-dimensional arrangement. The mechanical behavior of single spheres subjected to compression is first examined.

Evolution of droplets of perfectly wetting liquid under the influence of thermocapillary forces.

We consider the evolution of sessile droplets of a nonvolatile perfectly wetting liquid on differentially radially heated solid substrates. The heating induces thermocapillary Marangoni forces that affect the contact line dynamics. Our experiments involving a particular heating pattern reveal that the Marangoni effect suppresses the spreading of a drop, typical for perfectly wetting liquids.

Wetting dynamics of thin liquid films and drops under Marangoni and centrifugal forces.

This paper presents an experimental study on thin liquid drops and films under the combined action of centrifugal forces due to rotation and radial Marangoni forces due to a corresponding temperature gradient. We shall examine thinning of a given liquid layer both with and without rotation and also consider the onset of the fingering instability in a completely wetting liquid drop. In many of the experiments described here, we use an interferometric technique which provides key information on height profiles.

Instabilities in droplets spreading on gels.

We report a novel surface-tension driven instability observed for droplets spreading on a compliant substrate. When a droplet is released on the surface of an agar gel, it forms arms or cracks when the ratio of surface-tension gradient to gel strength is sufficiently large. We explore a range of gel strengths and droplet surface tensions and find that the onset of the instability and the number of arms depend on the ratio of surface tension to gel strength.

Dynamics of perfectly wetting drops under gravity.

We study the dynamics of small droplets of polydimethylsiloxane silicone oil on a vertical, perfectly wetting, silicon wafer. Interference videomicroscopy allows us to capture the dynamics of these droplets. We use droplets with a volumes typically ranging from 100 t o500nl (viscosities from 10 to 1000 cSt) to understand long time derivations from classical solutions.