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[en] A single droplet rotation in the steam flow field in the gravity separation space was researched. According to the mechanism of gravity separation, the force and torque on droplet in steam flow were analysed and solved by employing the single droplet model taking into account rotation. The effects of droplet rotation, diameter and velocity as well as the vapor flow on droplet trajectory were described, laying the basis for establishing the dynamic single droplet model. (authors)
[en] Binder jetting additive manufacturing is one of the 3D printing technologies currently used to manufacture 3D geometries. In this process, a liquid binder agent is ejected to a desired position of a substrate. The binder’s properties and the jetting condition used for form droplets can affect the formability of the geometries. Herein, we optimized the solid content and jetting condition of a sodium silicate-based inorganic binder, for 3D printing. To observe the range of single droplet formation, the behavior of the discharged droplets was analyzed by Z value, which is the inverse of the Ohnesorge number. As the solid content increased, a higher driving voltage was required to form the droplets to overcome viscous dissipation. For 40S(Z = 4.33) with a content of 40 wt%, the droplet tail from the nozzle was stretched further. The droplets of 25S(Z = 15.09) with a content of 25 wt% were accompanied by satellite droplets. The jetting condition was optimized for 25S, which was capable of ejection at various driving voltages. Stable single droplets were formed at a driving voltage of 20 V and a dwell time of 4 μs. In addition, when ethylene glycol and glycerol were added into 25S as a humectant, stable droplets were formed under the optimum jetting condition, and each droplets was in the range of 2.70 < Z < 15.09.
[en] Highlights: • Synthesis of PEG functionalized luminescent lipid particles by microemulsion route. • Good stability of luminescent probe inside lipid particles. • Excellent cellular imaging capability of luminescent lipid particles. We report here the synthesis, characterization and cellular uptake of luminescent micelle-like particles with phospholipid core and non-ionic PEG based surfactant polysorbate 80 shell. The adsorption of polysorbate 80 at the interface of lipid containing microemulsion droplets and its solidification upon removal of solvent leads to anchoring of PEG chain to the lipid particles. Hydrophobic partitioning of luminescent molecules, sodium 3-hydroxynaphthalene-2-carboxylic acid to the phospholipid core offers additional functionality to these particles. Thus, the cooperative assembly of lipid, non-ionic amphiphile and organic luminescent probe leads to the formation of multifunctional biocompatible particles which are useful for simultaneous imaging and therapy.
[en] We calculate the corrections to the thermodynamic limit of the critical density for jamming in the Kob-Andersen and Fredrickson-Andersen kinetically-constrained models, and find them to be finite-density corrections, and not finite-size corrections. We do this by introducing a new numerical algorithm, which requires negligible computer memory since contrary to alternative approaches, it generates at each point only the necessary data. The algorithm starts from a single unfrozen site and at each step randomly generates the neighbors of the unfrozen region and checks whether they are frozen or not. Our results correspond to systems of size greater than 107 × 107, much larger than any simulated before, and are consistent with the rigorous bounds on the asymptotic corrections. We also find that the average number of sites that seed a critical droplet is greater than 1
[en] A magnetic fluid droplet immersed in oil in an applied harmonic electric field is studied experimentally and theoretically. It is shown that deformations of the droplet observed experimentally are not described by the well-known theory. New double-layer droplet model which describes experimental data well is proposed. - Highlights: • The magnetic fluid droplet in the oil in a harmonic electric field is studied. • The paradoxical flattening effect of the droplet is observed experimentally. • For explaining this effect the model of the double-layer droplet is proposed. • Numerical and experimental data coincide qualitatively and quantitatively.
[en] Superhydrophobic surfaces have shown inspiring applications in microfluidics, and self-cleaning coatings owing to water-repellent and low-friction properties. However, thermodynamic mechanism responsible for contact angle hysteresis (CAH) and free energy barrier (FEB) have not been understood completely yet. In this work, we propose an intuitional 3-dimension (3D) droplet model along with a reasonable thermodynamic approach to gain a thorough insight into the physical nature of CAH. Based on this model, the relationships between radius of three-phase contact line, change in surface free energy (CFE), average or local FEB and contact angle (CA) are established. Moreover, a thorough theoretical consideration is given to explain the experimental phenomena related to the superhydrophobic behavior. The present study can therefore provide some guidances for the practical fabrications of the superhydrophobic surfaces.
[en] What is the minimum number of atoms needed for superfluidity? According to the results of a remarkable molecular spectroscopy experiment, there is definite proof that a system of only 60 atoms can be superfluid. Slava Grebenev and colleagues at the Max Planck Institute for Fluid Dynamics in Goettingen, Germany, found that small molecules dissolved in droplets of liquid helium can rotate freely, just like they do in a vacuum (S Grebenev, J P Toennies and A Vilesov 1998 Science 279 2083). The molecules rotate freely because the surrounding helium is a ''superfluid'' - a liquid without viscosity. In effect, the liquid helium acts as a vacuum. (UK)
[en] A classical model of fluid dynamics is considered which describes the shape evolution of a viscous liquid droplet on a homogeneous substrate. All equilibria are characterized and their stability is analyzed by a geometric reduction argument. (paper)