Pseudoboiling in supercritical fluid (SF) has been paid great attention in recent years. Available works mainly focus on thermodynamics analysis. Fewer studies were reported on the spatial time phase distribution. Here, SF is investigated in a multiphase fluid framework using molecular dynamics (MD) simulations. A simulation box contains 10 976 argon atoms, with periodic boundary conditions applied on all the box surfaces. Pressure and temperature are well controlled. Based on MD simulation results, an onset pseudoboiling temperature and a termination pseudoboiling temperature are defined using the neighboring molecules method, the radial distribution function method, and the two-body excess entropy method. The two transition temperatures divide the whole phase diagram into three regimes of liquidlike, two-phase-like (TPL), and gaslike, and the MD determined and well matched the thermodynamics-determined values. In the TPL regime, nanovoids are observed to have two distinct characteristics: (1) Particles are sparsely distributed to have gas density inside the void, but are densely populated to have liquid density outside the void. (2) Voids have a curved interface. These characteristics are very similar to bubble characteristics in subcritical pressure. Hence, voids in the supercritical state are called “bubblelike” in this paper. Nonlinear dynamics demonstrates chaotic behavior in the TPL regime, similar to the two-phase regime in the subcritical domain. The above findings give strong evidence that SF in the TPL regime consists of a mixture of bubblelike voids and surrounding liquids. Our work highlights the multiphase feature of a SF, hence, the well-established multiphase theory in subcritical pressures can be introduced to handle the complex SF.
Background: Low muscle mass likely results in reduced capacity for glucose disposal, leading to a significant but under-appreciated contribution to increasing the risk of diabetes. But few prospective studies have investigated the association between the loss of muscle mass and the occurrence of diabetes. We aimed to investigate whether short-term changes in muscle mass affect the incidence of diabetes in a Chinese population. Methods: This study included 1275 individuals without evident diabetes at baseline. In the baseline and re-examination, individuals completed the risk factors survey and underwent body composition measurement. Muscle mass index was defined as the percentage skeletal muscle mass, which was measured by an automatic bioelectric analyzer. Results: After a median follow-up of 2.1 years, 142 individuals developed diabetes (11.1%). There was an inverse association between basal skeletal muscle mass index and the risk of diabetes in participants with impaired glucose regulation but not in those with normal glucose tolerance. Multivariate-adjusted hazard ratios for the risk of developing diabetes were 0.85 (95% CI: 0.74–0.98) and 1.15 (95% CI: 0.98–1.34), respectively. Furthermore, Cox regression analysis revealed that a two-year change in skeletal muscle mass was also inversely associated with the incidence of diabetes in both participants with normal glucose tolerance and with impaired glucose regulation (HR: 0.76, 95% CI: 0.65–0.89; HR: 0.81, 95% CI: 0.71–0.91). Conclusions: These findings emphasized the importance of early detection and control of muscle mass loss for the prevention of diabetes.
Leidenfrost droplet possesses ultra-low flow resistance, but it is challenging to obtain large thrust force for fast transportation and regulate the direction of droplet motion. Here, for the first time, we demonstrate a novel mechanism for the control of droplet dynamics by explosive boiling. Our system consists of two surfaces that have different functions: a smooth surface running in the Leidenfrost state for droplet levitation and a skirt ring edge surface (SRES) as an explosive boiling trigger. For droplet-wall collision with SRES, micro/nanoscale roughness not only enhances energy harvesting from the skirt ring to the droplet due to increased radiation heat transfer but also provides nucleation sites to trigger explosive boiling. The symmetry breaking of explosive boiling creates a thrust force that is sufficient to propel the droplet. The suppression of the thrust force relative to the inertia force regulates the droplet trajectory as it passes through a target location. We show orbit lines passing through a focusing spot that is ∼1% of the Leidenfrost surface area around its center with a maximum traveling speed of ∼85 cm/s, which is ∼2 times of that reported in the literature. The scale law analysis explains the droplet size effect on the self-propelling droplet dynamics. Our work is attractive for applications under the conditions of the required traveling speed and direction of the droplet.
24 April 2024 in International Journal of Heat and Mass Transfer