Modeling ternary fluids in contact with elastic membranes

We present a thermodynamically consistent model of a ternary fluid interacting with elastic membranes. Following a free-energy modeling approach for the fluid phases, we derive the governing equations for the dynamics of the ternary fluid flow and membranes. We also provide the numerical framework for simulating such fluid-structure interaction problems. It is based on the lattice Boltzmann method for the ternary fluid (Eulerian description) and a finite difference representation of the membrane (Lagrangian description). The ternary fluid and membrane solvers are coupled through the immersed boundary method. For validation purposes, we consider the relaxation dynamics of a two-dimensional elastic capsule placed at a fluid-fluid interface. The capsule shapes, resulting from the balance of surface tension and elastic forces, are compared with equilibrium numerical solutions obtained by surface evolver. Furthermore, the Galilean invariance of the proposed model is proven. The proposed approach is versatile, allowing for the simulation of a wide range of geometries. To demonstrate this, we address the problem of a capillary bridge formed between two deformable capsules

Snap evaporation of droplets on smooth topographies

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a “stick-slip” sequence—a combination of pinning and de-pinning events dominated by static friction or “pinning”, caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications

Impact Dynamics of Non-Newtonian Droplets on Superhydrophobic Surfaces

Droplet impact behavior on a solid surface is critical for many industrial applications such as spray coating, food production, printing, and agriculture. For all of these applications, a common challenge is to modify and control the impact regime and contact time of the droplets. This challenge becomes more critical for non-Newtonian liquids with complex rheology. In this research, we explored the impact dynamics of non-Newtonian liquids (by adding different concentrations of Xanthan into water) on superhydrophobic surfaces. Our experimental results show that by increasing the Xanthan concentration in water, the shapes of the bouncing droplet are dramatically altered, e.g., its shape at the separation moment is changed from a conventional vertical jetting into a “mushroom”-like one. As a result, the contact time of the non-Newtonian droplet could be reduced by up to ∼50%. We compare the impact scenarios of Xanthan liquids with those of glycerol solutions having a similar apparent viscosity, and results show that the differences in the elongation viscosity induce different impact dynamics of the droplets. Finally, we show that by increasing the Weber number for all of the liquids, the contact time is reduced, and the maximum spreading radius is increased

dispersal and reception in northern italy comparing systems along the brenner route

In the last decades, policy restrictions and practices at national and local levels have curtailed the rights of seekers and holders of international protection, thus impacting on their lives and on the territories they transit through. This is particularly evident in border contexts. Various border areas have gradually transformed into internal hotspots, with increasing border enforcement. This includes Brenner, situated at the border between Italy and Austria. In the wider Brenner route area, particularly in the nearby Italian cities of Verona, Trento and Bolzano, "spaces of transit" have emerged and both public and humanitarian actors have been "forced" to deal with it. This chapter draws upon the work of the multilevel governance of migration (Caponio and Borkert 2010), and on the proliferation of borders (Mezzadra and Neilson 2016), to present a comparative analysis of the reception scenario in these three cities. By building on qualitative data analysis (legal analysis of policy documents, content analysis of interviews and newspaper articles), it discusses to what extent and how the respective local systems of reception have managed to cater for migrants that transit through them. Similarities and differences are pointed out, as well as the relevance of factors such as geographical proximity in influencing the respective approaches

Biogeographic problem-solving reveals the Late Pleistocene translocation of a short-faced bear to the California Channel Islands

An accurate understanding of biodiversity of the past is critical for contextualizing biodiversity patterns and trends in the present. Emerging techniques are refining our ability to decipher otherwise cryptic human-mediated species translocations across the Quaternary, yet these techniques are often used in isolation, rather than part of an interdisciplinary hypothesis-testing toolkit, limiting their scope and application. Here we illustrate the use of such an integrative approach and report the occurrence of North America’s largest terrestrial mammalian carnivore, the short-faced bear, Arctodus simus, from Daisy Cave (CA-SMI-261), an important early human occupation site on the California Channel Islands. We identified the specimen by corroborating morphological, protein, and mitogenomic lines of evidence, and evaluated the potential natural and anthropogenic mechanisms of its transport and deposition. While representing just a single specimen, our combination of techniques opened a window into the behavior of an enigmatic species, suggesting that A. simus was a wide-ranging scavenger utilizing terrestrial and marine carcasses. This discovery highlights the utility of bridging archaeological and paleontological datasets to disentangle complex biogeographic scenarios and reveal unexpected biodiversity for island systems worldwide.Open Access fees paid for in whole or in part by the University of Oklahoma Libraries Radiocarbon and isotope laboratory work was supported in part by the NSF Archaeometry Program BCS-1460369 (to D.J.K. and B.J.C). M.B was supported by a Royal Society fellowship. Additional funding was provided by the University of Oklahoma, the University of Oregon, and the Smithsonian Institution.Ye

Drop Dynamics on Liquid Infused Surfaces: The Role of the Lubricant Ridge

We employ a free energy lattice Boltzmann method to study the dynamics of a ternary fluid system consisting of a liquid drop driven by a body force across a regularly textured substrate, infused by a lubricating liquid. We focus on the case of partial wetting lubricants and observe a rich interplay between contact line pinning and viscous dissipation at the lubricant ridge, which become dominant at large and small apparent angles respectively. Our numerical investigations further demonstrate that the relative importance of viscous dissipation at the lubricant ridge depends on the drop to lubricant viscosity ratio, as well as on the shape of the wetting ridge

Valors típics de pH i DP del suport de tela en la pintura de cavallet

Podeu consultar el document complet del congrès a: http://hdl.handle.net/2445/58643Ja fa varies decades que els conservadors-restauradors de paper van comenc;ar a tenir en compte el pH de les obres que tractaven, ja que es va veure que I'acidesa incidia molt directament en com de rapid I'objecte es debilitava mecimicament. De fet, trobem tant aviat com el 1936, una patent en registrada per OJ. Schierholtz per desacidificar el paper d'empaperar parets (Porck, 1996). La tela d'un quadre, essent un teixit fet a base de fibres vegetals compastes majoritariament per ceHulosa, com les fibres del paper, és lógicament també facilment degradable si I'ambient ñes acid (te un baix pH). Sorprenentment, pero, I'acidesa de la tela deis quadres, tot i que en ocasions puntuals ha estat analitzada (Bajocchi, 2009; Young, 1999), encara no és un parametre que es miri de forma rutinaria i per tant, fins recentment, no se sabia quins eren els valors de pH més típics que pot tenir un quadre. Aquest estudi és una primera recopilació sistematica d'aquest t ipus d' in formació per a partir d'aquí crear un banc de dades que vagi recollint aquest t ipus d'informació sobre el majar nombre possible de quadres. Si I'acidesa present en la tela ens indica com de rapid es degradara aquesta en el futur, la mesura del grau de polimerització de la tela (DP), ens indica si la tela té una al ta o baixa resistencia mecanica en el moment actual. Així doncs, aquests dos parametres ens aporten informació molt úti l sobre I'estat de conserva ció del suporto Aquesta recerca pretén respondre a les preguntes de quins són els valors de pH i DP que típicament podem trabar en la tela deis quadres, així com analitzar la relació entre aquests dos parametres i també la relació entre la data de producció deis quadres i els valors de pH i DP