Evaporation from thin porous Coatings: Pore size effects and predictive equation for homogeneous coatings.

Evaporation of small water droplets on solids is hindered because surface tension pulls the droplet into a spherical cap that has a small perimeter. Our solution is to coat a solid with a very thin, porous layer into which the droplet flows to create a large-area disk with concomitant high rate of evaporation. We investigate evaporation by varying factors that have not been previously considered: pore size and distribution, contact angle, temperature, and relative humidity (RH).

Data-driven modelling makes quantitative predictions regarding bacteria surface motility.

In this work, we quantitatively compare computer simulations and existing cell tracking data of P. aeruginosa surface motility in order to analyse the underlying motility mechanism. We present a three dimensional twitching motility model, that simulates the extension, retraction and surface association of individual Type IV Pili (TFP), and is informed by recent experimental observations of TFP.

Antimicrobial activity of cuprous oxide-coated and cupric oxide-coated surfaces.

Background: Disease can be spread through contact with contaminated surfaces (fomites). For example, fomites have been implicated in the spread of meticillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Antimicrobial surface treatments are a potential method of reducing disease transmission from fomites, and broad-spectrum activity is desirable.

Molecular Diffusion of Ions in Nanoscale Confinement.

We measured the diffusion of an anion, fluorescein, confined to a nanoscale (10-100 nm) aqueous film between two glass walls. The two glass walls were very slightly angled to form a crack. The diffusion of fluorescein was strongly influenced by the presence of an inert electrolyte, NaCl, in the film prior to the diffusion of charged fluorescein into the crack.

Transparent Anti-SARS-CoV-2 and Antibacterial Silver Oxide Coatings.

Transparent antimicrobial coatings can maintain the aesthetic appeal of surfaces and the functionality of a touch-screen while adding the benefit of reducing disease transmission. We fabricated an antimicrobial coating of silver oxide particles in a silicate matrix on glass. The matrix was grown by a modified Stöber sol-gel process with vapor-phase water and ammonia.

SARS-CoV-2 virus transfers to skin through contact with contaminated solids.

Transfer of SARS-CoV-2 from solids to fingers is one step in infection via contaminated solids, and the possibility of infection from this route has driven calls for increased frequency of handwashing during the COVID-19 pandemic. To analyze this route of infection, we measured the percentage of SARS-CoV-2 that was transferred from a solid to an artificial finger. A droplet of SARS-CoV-2 suspension (1 µL) was placed on a solid, and then artificial skin was briefly pressed against the solid with a light force (3 N).

Reduction of Infectivity of SARS-CoV-2 by Zinc Oxide Coatings.

We developed antimicrobial coatings from ZnO particles that reduce the infectivity of SARS-CoV-2 suspensions by >99.9% in 1 h. The advantage of a coating is that it can be applied to a variety of objects, e.

A Surface Coating that Rapidly Inactivates SARS-CoV-2.

SARS-CoV-2, the virus that causes the disease COVID-19, remains viable on solids for periods of up to 1 week, so one potential route for human infection is via exposure to an infectious dose from a solid. We have fabricated and tested a coating that is designed to reduce the longevity of SARS-CoV-2 on solids. The coating consists of cuprous oxide (CuO) particles bound with polyurethane.

Effect of Topographical Steps on the Surface Motility of the Bacterium .

Bacteria traverse surfaces as part of colonizing solids, and it is of interest to hinder this motion to potentially thwart infections in humans. Here, we demonstrate that topographical steps hinder the ability of PAO1 () to traverse a solid-liquid interface. Using time-lapse fluorescence microscopy and image analysis, we analyzed the motion of that were challenged with steps ranging in height from 0.

Removal of Bacteria from Solids by Bubbles: Effect of Solid Wettability, Interaction Geometry, and Liquid-Vapor Interface Velocity.

Air bubbles are a promising means of controlling fouling for a range of applications, particularly delaying fouling in marine environments. This work investigates the mechanism by which the collision of an air bubble with a solid removes adsorbed bacteria. A key feature of the work is that the numbers of bacteria were monitored via video microscopy throughout the collision; so, we were able to explore the mechanism of bacteria removal.

Adsorption at Confined Interfaces.

We describe measurements of adsorption between two flat plates when the plates are separated by 0-65 nm. The objective is to examine how adsorption is affected by confinement in very thin films. It is well known that adsorption of simple ions can change with the thickness of a thin film (charge regulation); here, we describe a direct method to measure adsorption as a function of confinement and results for one example.

Surface Topography Hinders Bacterial Surface Motility.

We demonstrate that the surface motility of the bacterium, Pseudomonas aeruginosa, is hindered by a crystalline hemispherical topography with wavelength in the range of 2-8 μm. The motility was determined by the analysis of time-lapse microscopy images of cells in a flowing growth medium maintained at 37 °C. The net displacement of bacteria over 5 min is much lower on surfaces containing 2-8 μm hemispheres than on flat topography, but displacement on the 1 μm hemispheres is not lower.

Effects of Colloidal Crystals, Antibiotics, and Surface-Bound Antimicrobials on Surface Density.

We examined the effect of a crystalline layer of silica particles in the size range 0.5-4 μm on the adsorption and surface growth of . Growth on these colloidal crystal monolayers (CCMs) was compared to growth on a flat plate of silica.