Optically assembled droplet interface bilayer (OptiDIB) networks from cell-sized microdroplets

We report a new platform technology to systematically assemble droplet interface bilayer (DIB) networks in user-defined 3D architectures from cell-sized droplets using optical tweezers. Our OptiDIB platform is the first demonstration of optical trapping to precisely construct 3D DIB networks, paving the way for the development of a new generation of modular bio-systems

Divergence of critical fluctuations on approaching catastrophic phase inversion in turbulent emulsions

Catastrophic phase inversion, the sudden breakdown of a dense emulsion, occurs when the dispersed majority phase irreversibly exchanges role with the continuous minority phase. This common process has been extensively studied over the past decades and yet its fundamental physical mechanism has remained largely unexplored. Here we experimentally and numerically study the dynamics of catastrophic phase inversion as it occurs when the volume fraction of the dispersed phase exceeds a critical volume fraction (typically around 92% in experiments). Our data accurately quantify the abrupt change of both the global torque and average droplet size at approaching and across the phase inversion point, exhibiting strong hysteresis. Most importantly, we reveal that the fluctuations in the global torque diverge as a power-law while approaching the critical volume-fraction and we connect their growth to the formation of highly heterogeneous spatial droplet structures. The present finding, unveiling the tight connection between fluctuations in dynamic heterogeneity and the critical divergence of torque fluctuation, paves the way to a quantitative description of catastrophic phase inversion as an out-of-equilibrium critical-like phenomena

Characterisation of the dynamic behaviour of lipid droplets in the early mouse embryo using adaptive harmonic generation microscopy

<p>Abstract</p> <p>Background</p> <p>Lipid droplets (LD) are organelles with an important role in normal metabolism and disease. The lipid content of embryos has a major impact on viability and development. LD in Drosophila embryos and cultured cell lines have been shown to move and fuse in a microtubule dependent manner. Due to limitations in current imaging technology, little is known about the behaviour of LD in the mammalian embryo. Harmonic generation microscopy (HGM) allows one to image LD without the use of exogenous labels. Adaptive optics can be used to correct aberrations that would otherwise degrade the quality and information content of images.</p> <p>Results</p> <p>We have built a harmonic generation microscope with adaptive optics to characterise early mouse embryogenesis. At fertilization, LD are small and uniformly distributed, but in the implanting blastocyst, LD are larger and enriched in the invading giant cells of the trophectoderm. Time-lapse studies reveal that LD move continuously and collide but do not fuse, instead forming aggregates that subsequently behave as single units. Using specific inhibitors, we show that the velocity and dynamic behaviour of LD is dependent not only on microtubules as in other systems, but also on microfilaments. We explore the limits within which HGM can be used to study living embryos without compromising viability and make the counterintuitive finding that 16 J of energy delivered continuously over a period of minutes can be less deleterious than an order of magnitude lower energy delivered dis-continuously over a period of hours.</p> <p>Conclusions</p> <p>LD in pre-implantation mouse embryos show a previously unappreciated complexity of behaviour that is dependent not only on microtubules, but also microfilaments. Unlike LD in other systems, LD in the mouse embryo do not fuse but form aggregates. This study establishes HGM with adaptive optics as a powerful tool for the study of LD biology and provides insights into the photo-toxic effects of imaging embryos.</p

Simulation and Modeling of High Energy Laser-Induced Droplet Shattering In Clouds

The process of a megawatt laser passing through a cloud is modeled. Specifically, the potential for droplet shattering is explored as a method for clearing a path through a cloud through which a second laser may be sent unobstructed. The paraxial approximation, an approximation to Maxwell\u27s equations, is used to model the beam propagation. The simplified cloud model has assumed a distribution of pure, timescale restricted, droplets evenly distributed with uniform radius and initial temperature. All of the radiative heating is assumed to heat the droplet, neglecting radius change and vaporization based upon characteristic time scales. A 1+1 dimensional model is solved analytically over time and used to verify a numerical model which is then scaled up and applied to the 2+1-dimensional, radially symmetric case. The process is shown to create a cleared channel in a realistic amount of time given the constraining assumptions