Tears Of Wine Research Articles

Bifurcation and Transposition of the Wicking Front of Binary Solutions Infiltrating into Chromatography Paper Associated with Their Evaporation.

Nonequilibrium fluid patterns, such as Marangoni contraction, coffee rings, and tears of wine, are generated in binary solutions spread on a substrate during their evaporation. In this study, we observed another type of nonequilibrium behavior exhibited by binary solutions as they infiltrate porous materials and undergo evaporation. A binary solution comprising hexane and ethanol was brought into contact with the chromatography paper to facilitate infiltration into the paper's pores. Because the experimental setup was in an open environment, infiltration and evaporation occurred simultaneously. The wicking front exhibited an initial rapid advancement, followed by subsequent receding and readvancing. Additionally, the bifurcation of the wicking front after the onset of its readvancement was confirmed by monitoring the temporal evolution of the spatial luminance distribution and temperature distribution on the surface of the chromatography paper. Chromatographic development of a hydrophilic dye was conducted in this experimental setup in an open environment. Additionally, it was confirmed that the receding and readvancing of the wicking front represented the transposition of the bifurcated wicking fronts.

Marangoni effect and its potential utilization in supporting lunar habitats and other extraterrestrial endeavors

Tears of wine is a phenomenon frequently observed as a ring of wine formed near the top of the glass generates droplets that fall back into the wine. This phenomenon can be explained by the Marangoni effect driven by the surface tension created via gradient on concentration and temperature along the interface between two phases. Besides being observed while drinking wine, the Marangoni effect is crucial for welding metals, manufacturing integrated circuits, and growing crystals. This paper aims to establish that the Marangoni effect has the potential to be also crucial supporting lunar habitats and other extraterrestrial endeavors, as vacuum and reduced gravity are expected to augment the Marangoni effect on extraterrestrial molten soil leading to sustainable extraterrestrial in-situ resources utilization (ISRU). The authors conducted a Marangoni effect assessment on molten lunar regolith via JSC-1A lunar regolith simulant under vacuum yielding a spontaneous upwards migration of a uniform molten thin-film front as well as at bulk scale that climbed the crucible wall covering the entire wall’s surface and reaching the crucible’s top end. This unique formation and self-migration of a thin-film front could enable key ISRU processes such as, thin-film coating, crystal growth, and feedstock generation for additive 3D printing. Further assessment on higher-temperature vacuum-driven decomposition of the uniform thin-film front as it climbed the crucible’s wall revealed a significant decomposition of various simulant’s metal-oxide components into their respective oxygen and metal elements strengthening the feasibility of extraterrestrial generation and fractional separation of oxygen and metals/alloys with none or minimal need for terrestrial precursors. These two-coupled phenomena, spontaneous material transportation at both thin-film and bulk scales via Marangoni effect and vacuum-driven decomposition open novel pathways in extraterrestrial mining and manufacturing. Future extraterrestrial mining will require an operational approach completely different from the terrestrial one that heavily relies on not only mechanical excavation and transportation but also on a stand-alone refinery process to extract the mineral components. In this paper, the authors propose an extraterrestrial all-in-one mining process in which the Marangoni effect would allow non-mechanical transportation of the extraterrestrial mineral to feed an also in-situ pyrolysis-based refinery unit.

Directional Liquid Transport from the Cold Region to the Hot Region on a Topological Surface.

Manifested from the "tears of wine" to the "coffee-ring effect", the directional transport of a liquid governed by the Marangoni effect is highly pervasive in our daily life and has brought a great number of applications. Similar to this surface tension gradient-dominated process, the fluid preferentially flows from the hot region to the cold region. In contrast to this perception, in this study, we report that water liquid deposited on a specially designed topological surface can flow from the low-temperature region to the high-temperature region in a spontaneous, long-range, and unidirectional manner. We show that such a behavior is mainly owing to a strong topological effect that outweighs the thermal gradient imposed along the surface. Moreover, the specific temperature range applied on the topological surface for the occurrence of such a unidirectional liquid transport phenomenon is also identified. Our findings would find important insights for developing next-generation cooling devices where a rapid flow from the condensation region to the evaporation/boiling region is preferred.

DRY & WET: meniscus splitting from a mixture of polysaccharides and water

Drying-induced patterns, “meniscus splitting”, are introduced through a series of experiments using self-assembled polysaccharides. When physicochemical factors such as the geometry of the evaporative air–liquid interface are controlled, the depositing polymer bridges the gap between two substrates to create multiple nuclei at specific positions for membrane growth. These phenomena were first discovered by our group based on viscous fingering, known as tears of wine. By developing interfacial instability, meniscus splitting causes partitioning of a space by membranes, similar to dissipative structures seen in nature, “from one space into multiple spaces.” In the field of advanced biomimetic materials, the method of convective meniscus splitting would be useful for devising a powerful strategy for the preparation of hierarchically self-assembled materials from a variety of polymeric materials. Drying-induced patterns, “meniscus splitting,” are introduced through a series of demonstrations using self-assembled polysaccharides as a method for the preparation of advanced biomimetic materials. Under the control of physicochemical factors, the depositing polymer bridges the gap between two substrates to make multiple nuclei at specific positions for membrane growth. By developing interfacial instability, meniscus splitting causes partitioning of a space, similar to dissipative structures seen in nature, from one space into multiple spaces.

Theory for undercompressive shocks in tears of wine

Tears of wine, in which a thin layer of a water-ethanol mixture travel up an inclined surface against gravity and then fall down in the form of tears, have been observed in wine glasses for centuries. It has been modeled with a conservation law with a nonconvex flux and higher order diffusion due to the bulk surface tension. The resulting nonclassical ``undercompressive'' shock solutions are the main driver of the destabilizing front forming the ``wine tears''. Prior modeling did not address the wine tears but rather the behavior of the film at earlier stages and the behavior of the meniscus.

Analysis of Marangoni convection in "tears of wine" by the visualization of inside flow

Analysis of Marangoni convection in "tears of wine" by the visualization of inside flow

Level-set simulations of soluble surfactant driven flows

We present an approach to simulate the diffusion, advection and adsorption–desorption of a material quantity defined on an interface in two and three spatial dimensions. We use a level-set approach to capture the interface motion and a Quad/Octree data structure to efficiently solve the equations describing the underlying physics. Coupling with a Navier–Stokes solver enables the study of the effect of soluble surfactants that locally modify the parameters of surface tension on different types of flows. The method is tested on several benchmarks and applied to three typical examples of flows in the presence of surfactant: a bubble in a shear flow, the well-known phenomenon of tears of wine, and the Landau–Levich coating problem.

The Secret of Tears of Wine

The Secret of Tears of Wine

Tears of wine: new insights on an old phenomenon.

Anyone who has enjoyed a glass of wine has undoubtedly noticed the regular pattern of liquid beads that fall along the inside of the glass, or ‘tears of wine.’ The phenomenon is the result of a flow against gravity along the liquid film on the glass, which is induced by an interfacial tension gradient. It is generally accepted that the interfacial tension gradient is due to a composition gradient resulting from the evaporation of ethanol. We re-examine the tears of wine phenomenon and investigate the importance of thermal effects, which previously have been ignored. Using a novel experiment and simple model we find that evaporative cooling contributes significantly to the flow responsible for wine tears, and that this phenomenon occurs primarily because of the thermodynamic behavior of ethanol-water mixtures. Also, the regular pattern of tear formation is identified as a well-known hydrodynamic instability.

Vapour-mediated sensing and motility in two-component droplets.

Controlling the wetting behaviour of liquids on surfaces is important for a variety of industrial applications such as water-repellent coatings and lubrication. Liquid behaviour on a surface can range from complete spreading, as in the 'tears of wine' effect, to minimal wetting as observed on a superhydrophobic lotus leaf. Controlling droplet movement is important in microfluidic liquid handling, on self-cleaning surfaces and in heat transfer. Droplet motion can be achieved by gradients of surface energy. However, existing techniques require either a large gradient or a carefully prepared surface to overcome the effects of contact line pinning, which usually limit droplet motion. Here we show that two-component droplets of well-chosen miscible liquids such as propylene glycol and water deposited on clean glass are not subject to pinning and cause the motion of neighbouring droplets over a distance. Unlike the canonical predictions for these liquids on a high-energy surface, these droplets do not spread completely but exhibit an apparent contact angle. We demonstrate experimentally and analytically that these droplets are stabilized by evaporation-induced surface tension gradients and that they move in response to the vapour emitted by neighbouring droplets. Our fundamental understanding of this robust system enabled us to construct a wide variety of autonomous fluidic machines out of everyday materials.

RGD decoration of PEGylated polyester nanocapsules of perfluorooctyl bromide for tumor imaging: Influence of pre or post-functionalization on capsule morphology

PEGylated polyester nanocapsules of perfluorooctyl bromide (PFOB) were surface-decorated with a RGD (arginine–glycine–aspartic acid) peptide by either pre-functionalization or post-functionalization strategies using carbodiimide-assisted chemistry. Both strategies allowed successful linkage of RGD at the surface of nanocapsules with up to 600–950 peptide units per nanocapsule without modifying the encapsulation efficacy of PFOB used as the 19F MRI imaging moiety. Cryo-Transmission Electron Microscopy images evidence that slight changes of the polymer used to form the capsule shell strongly influence nanocapsule morphology. While, the use of copolymer blends induces the formation of acorn morphologies, PLA-b-PEG-COOH leads to elongated and “tears of wine”-like nanoconstructs. In vivo evaluation in mice bearing CT26 tumors by 19F MRI reveals no significant difference of accumulation between PEGylated and RGD-decorated nanocapsules obtained by the post-functionalization approach (highest RGD density/capsule).

Chasing drops: Following escaper and pursuer drop couple system

We study experimentally six different systems in which Marangoni flow is induced by two chemically different drops on a solid surface in air. In such systems one drop seems to chase away the other. We show that in all the systems studied, the Marangoni flow is induced at the solid–vapor interface as opposed to the air–liquid interface. This is true even for the case of water drop and alcohol drop on a glass surface (which corresponds to the “tears of wine” classical case). Thus we explain the drop motion as a result of an interfacial tension gradient which takes place primarily at the air–surface region and less, if at all, at the two other interfaces in the problem: the liquid–substrate or liquid–air interfaces. Then we follow the motion of drops on surfaces and find that it is discontinuous, i.e. characterized by stops and jumps as in a stick slip mechanism. We explain this behavior by an increase in the Laplace pressure that creates a higher anchoring pinning effect at the front edge of the moving drop. The understanding of this process has implications for passively separating mixed liquids.

Tears of Wine

The motion of wine drops observed on the internal walls of a glass, usually called tears of wine, is perhaps the oldest known example of surface tension driven flows.

Tears of wine: the stationary state

Water-ethanol mixtures spontaneously produce strong convective effects, driving the liquid upward in thin films and downward in regular rows of drops known as tears of wine. We present here a study of this stationary state, with a specific investigation of the interfacial instability which develops at the crossover between the reservoir and the thin film. We interpret it as a Rayleigh-like instability, the wavelength of which is mainly controlled by the extension of this crossover zone.

Reflections on the ‘Tears of wine’ phenomena in materials

Surface tension effects, due to the accumulation of minor components in the surface, play an important part in the processing and properties of materials. The ‘tears of wine’ is an example of such processes.