Spheroid mechanics and implications for cell invasion

Spheroids are widely used in vitro 3D multicellular model systems that mimic complex physiological microenvironments of tissues. As different cell types vary in deformability and adhesion, the choice of (heterogeneous) cell composition will define overall spheroid mechanics, including their viscoelasticity and effective surface tension. These...

Self-folding using capillary forces

Self-folding broadly refers to the assembly of 3D structures by bending, curving, and folding without the need for manual or mechanized intervention. Self-folding is scientifically interesting because examples of self-folded structures, from plant leaves to gut villi to cerebral gyri, abound in nature. From an engineering and technological...

Microscale surface tension and its applications

Artificial cell membranes interfaced with optical tweezers: A versatile microfluidics platform for nanomanipulation and mechanical characterization

Cell lipid membranes are the site of vital biological processes, such as motility, trafficking, and sensing, many of which involve mechanical forces. Elucidating the interplay between such bioprocesses and mechanical forces requires the use of tools that apply and measure piconewton-level forces, e.g., optical tweezers. Here, we introduce the...

Slow growth of the Rayleigh-Plateau instability in aqueous two phase systems

This paper studies the Rayleigh-Plateau instability for co-flowing immiscible aqueous polymer solutions in a microfluidic channel. Careful vibration-free experiments with controlled actuation of the flow allowed direct measurement of the growth rate of this instability. Experiments for the well-known aqueous two phase system (ATPS, or aqueous...

Thermodynamic properties of acid gases in mixture with natural gas and water

The reliable removal of acid gas components, such as carbon dioxide (CO2) and hydrogen sulfide (H2S) from natural gas is an important technical challenge. Crude oil and hydrocarbon gas streams may contain high levels of CO2 and/or H2S as contaminants. It is desirable to prevent any contaminant to reach the surface, or to considerably reduce the...

A density functional theory for vapor-liquid interfaces using the PCP-SAFT equation of state

A Helmholtz energy functional for inhomogeneous fluid phases based on the perturbed-chain polar statistical associating fluid theory (PCP-SAFT) equation of state is proposed. The model is supplemented with a capillary wave contribution to the surface tension to account for long-wavelength fluctuations of a vapor-liquid interface. The functional...

Experiments on single event electrospraying

In order to use electrospraying as an on demand deposition method, well defined and reproducible single electrospraying events have been studied. To generate a single electrospraying event, rectangular voltage pulses superimposed on a constant bias voltage were applied, and optimum settings of the bias dc voltage for starting such an event were...

A local mass conservation method for the level set method applied to capillary incompressible flow

In the case of incompressible flow, the level set method does not ensure mass conservation and it has to be enforced. The usual global mass conservation presents unacurracy in the case of separated phases of one fluid. In this paper, we propose an alternative local mass conservation based local volume fluxes. We apply our method to test cases...

Electron-beam-induced deformations of SiO2 nanostructures

The imaging beam of a transmission electron microscope can be used to fine tune critical dimensions in silicon oxide nanostructures. This technique is particularly useful for the fabrication of nanopores with single-nanometer precision, down to 2 nm. We report a detailed study on the effect of electron-beam irradiation on apertures with various...

Free-Surface Boundary Layer and the Origin of Bow Vortices

The boundary layer that exists due to the boundary conditions at a curved free surface of a viscous liquid ahead of a body in motion is analyzed. It is shown that surface tension and viscous effects are important and together explain the occurrence of vortices which have been observed on ship bows. The equations of the free-surface boundary...

Two-dimensional modelling of capillary liquid flow in a thin annulus

One of the experiments performed on board Spacelab, involves a partially filled annular cylinder which is subjected to prescribed motions (Ref. 1). The interest in this configuration arises from its practical use; for instance, the coolant in IRAS was stored in an annulus-like tank. In this report, a mathematical model for the transient liquid...