Particle-Based Dynamic Water Drops with High Surface Tension in Real Time

Surface tension has a great influence on the shape of the fluid interface, and is an important physical characteristic in expressing not only liquids but also liquid metals such as mercury and gallium. In the field of physics-based particle fluid simulations, it is a challenging problem to express the high surface tension generated by fluid-air or fluid-solid interaction in real time. The main reasons for this are (1) The magnitude of the force that can be stably expressed in real-time fluid simulation is limited, so when the magnitude of the surface tension increases at a large time-step, the simulation stability decreases, and (2) If we use a small time-step, a stronger force can be expressed. However, it becomes difficult to operate in real time because the computational cost increases. Techniques were proposed to solve this problem for a few specific scenes, but there has not yet been a general approach that can reliably express high surface tension in various scenarios. In this paper, we propose a real-time particle-based fluid simulation framework that can efficiently and stably express high surface tension. Unlike the previous methods, we newly model the surface tension so that the strong surface tension force generated in the droplet area with a large curvature is applied evenly in the normal and tangent directions regardless of the size of the droplet. We also propose new pressure constraints that converge quickly and accurately using this force. Our method can be effectively used in various physics-based simulation scenarios because it can easily express and control surface tension effects that appear in materials such as liquid metal as well as water.

Surfactant Protein B Deficiency Induced High Surface Tension: Relationship between Alveolar Micromechanics, Alveolar Fluid Properties and Alveolar Epithelial Cell Injury

High surface tension at the alveolar air-liquid interface is a typical feature of acute and chronic lung injury. However, the manner in which high surface tension contributes to lung injury is not well understood. This study investigated the relationship between abnormal alveolar micromechanics, alveolar epithelial injury, intra-alveolar fluid properties and remodeling in the conditional surfactant protein B (SP-B) knockout mouse model. Measurements of pulmonary mechanics, broncho-alveolar lavage fluid (BAL), and design-based stereology were performed as a function of time of SP-B deficiency. After one day of SP-B deficiency the volume of alveolar fluid V(alvfluid,par) as well as BAL protein and albumin levels were normal while the surface area of injured alveolar epithelium S(AEinjure,sep) was significantly increased. Alveoli and alveolar surface area could be recruited by increasing the air inflation pressure. Quasi-static pressure-volume loops were characterized by an increased hysteresis while the inspiratory capacity was reduced. After 3 days, an increase in V(alvfluid,par) as well as BAL protein and albumin levels were linked with a failure of both alveolar recruitment and airway pressure-dependent redistribution of alveolar fluid. Over time, V(alvfluid,par) increased exponentially with S(AEinjure,sep). In conclusion, high surface tension induces alveolar epithelial injury prior to edema formation. After passing a threshold, epithelial injury results in vascular leakage and exponential accumulation of alveolar fluid critically hampering alveolar recruitability.

Perfluorocarbon Liquids in Vitreoretinal Surgery

Perfluorocarbon (PFC) liquids are hydrocarbons in which all the hydrogen atoms are replaced with the fluorine atoms. PFC liquids are stabilized liquids that can stay as a single piece with their high surface tension and are heavier than water. Perfluoro-n-octane, perfluorodecalin, perfluoro-phenanthrene are frequently used liquid PFC derivatives used in a clinical ophthalmology practice. Intraoperative use of PFC liquids in vitreoretinal surgery for proliferative vitreoretinopathy and complicated retinal detachment provides surgical ease and increase anatomical and functional success. Long-term exposure to PFC liquids results in complications such as inflammation and degenerations of ocular tissues. Studies are needed for PFC liquids which are suitable for long-term intraocular use.

Study of Ultrasonic Dispersion of Graphene Nanoplatelets

Graphene has outstanding mechanical properties due to its unique structure, and is regarded as an ideal reinforcement of metal matrix composites. However, it is always in an agglomerate form due to its large specific surface area, and thus, it must be first dispersed prior to combining with a matrix, and ultrasonic treatment is considered to be the most effective way. In this work, the effects of parameters of tip ultrasonic treatment, such as ultrasonic time, ultrasonic power, solvent kind, and its temperature, on dispersion and structure of graphene nanoplatelets (GNPs) were studied. The results show that increasing ultrasonic time or ultrasonic power can enhance the dispersion and exfoliation effects of GNPs, but also increase fragmentation degree and disorder degree of C-atom distribution simultaneously. Solvents with low temperature, low viscosity, or high surface tension have similar effects to those of increasing ultrasonic time or power. However, for tap water, a high-surface-tension solvent, it has relatively low fragmentation degree, and good dispersion and exfoliation effects due to the hydrophilicity of GNPs. However, ethyl alcohol is a more suitable solvent because it has excellent volatility and inert reaction characteristics with GNPs and matrix alloys besides a good dispersion effect. The GNPs can achieve the expected status when they are ultrasonically treated for 4 h under a power of 960 W in EA solvent at 35 °C.

The size-responsive phase transition mechanism and upconversion/downshifting luminescence properties of KLu2F7:Yb3+/Er3+ nanocrystals

With the decrease of grain size, high surface tension triggers anisotropic KLu2F7:Yb3+/Er3+ to phase transition to isotropic KLu3F10:Yb3+/Er3+ ignoring the doping ion radius.

Rheological Properties of Liquid Metals and Semisolid Materials at Low Solid Fraction

Rheological properties of liquid metals are difficult to investigate experimentally because of the extreme border conditions to consider. One difficulty is related to the low viscosity of liquid metals. Surface tension effects can cause forces that can be considerably higher than the viscous forces in the liquid metals. Evaluating the experimental data without considering these effects leads to an apparent shear thinning behavior of the material. In the present study, experiments were performed by means of a Searle rheometer changing the dimension of the measuring system with metals of high surface tension, as mercury and tin. It became evident that surface tension plays a significant role in the effects that falsify measurements at low shear rate. Conclusions can be drawn to what extent measurements of semi-solid metals are affected.

Surfactant dysfunction during overexpression of TGF-β1 precedes profibrotic lung remodeling in vivo

Transforming growth factor-β1 (TGF-β1) is involved in regulation of cellular proliferation, differentiation, and fibrogenesis, inducing myofibroblast migration and increasing extracellular matrix synthesis. Here, TGF-β1 effects on pulmonary structure and function were analyzed. Adenovirus-mediated gene transfer of TGF-β1 in mice lungs was performed and evaluated by design-based stereology, invasive pulmonary function testing, and detailed analyses of the surfactant system 1 and 2 wk after gene transfer. After 1 wk decreased static compliance was linked with a dramatic alveolar derecruitment without edema formation or increase in the volume of septal wall tissue or collagen fibrils. Abnormally high surface tension correlated with downregulation of surfactant proteins B and C. TTF-1 expression was reduced, and, using PLA (proximity ligand assay) technology, we found Smad3 and TTF-1 forming complexes in vivo, which are normally translocated into the nucleus of the alveolar epithelial type II cells (AE2C) but in the presence of TGF-β1 remain in the cytoplasm. AE2C show altered morphology, resulting in loss of total apical surface area per lung and polarity. These changes of AE2C were progressive 2 wk after gene transfer and correlated with lung compliance. Although static lung compliance remained low, the volume of septal wall tissue and collagen fibrils increased 2 wk after gene transfer. In this animal model, the primary effect of TGF-β1 signaling in the lung is downregulation of surfactant proteins, high surface tension, alveolar derecruitment, and mechanical stress, which precede fibrotic tissue remodeling and progressive loss of AE2C polarity. Initial TTF-1 dysfunction is potentially linked to downregulation of surfactant proteins.

Using Semi-Solid Extrusion for the Production of Aluminum-Nanocomposite Master Alloys

The production of nanoreinforced aluminum alloys in volume and quality suitable for subsequent shape casting has been problematic. Large specific surface area and high interfacial energy of the particles combined with high surface tension of the aluminum melt makes it difficult to add appreciable numbers of particles to the melt, even when later de-agglomerated by techniques such as ultrasonic cavitation. Previous work by the authors used semi-solid squeeze casting to produce master alloys for dilution into the casting alloy. While the technique was shown to be effective, the master alloy proved difficult to remelt and was expensive to produce. The objective of this new work was to use an extrusion process that could be more readily scaled to produce nanoreinforced aluminum master alloys. This paper describes the process developed for incorporation of nanoparticles using semi-solid extrusion and the results of alloys produced using that process.