Dispersal distances from splash-cup plants depend on the cup's angle and contents

Splash-cup plants disperse propagules via raindrops striking cup-shaped fruiting bodies. The seeds are ejected at velocities up to five times the impact speed of the raindrop and are dispersed up to 1 m from the parent plant. Here, we examine the effects of cup angles and the presence of seed mimics to understand the dynamics of this unique method of dispersal. Our findings demonstrate that: (i) cup angles that launched seeds the furthest ranged from approximately 30° to 50°, matching the range of angles seen in splash-cup plants. (ii) Seeds travel shorter distances than water droplets alone, and this distance depends on the number of seeds in the cup. (iii) Not all seeds are ejected from initially dry cups, leaving cups with some seeds and some water. (iv) Nearly all seeds are ejected from cups that contain both water and seeds, and those that are ejected travel significantly further than those from dry cups. These results confirm the possibility that the conical shape of splash cup plants may be adapted to maximize dispersal distance and benefit from multiple splash events. Our results also illustrate that future work on these plants should include seeds rather than water droplets alone.

Understanding the Role of Surface Charge on Nanobubble Capillary Bridging during Particle-Particle Interaction

The interactions between particles due to long-range hydrophobic forces have been extensively investigated. The hydrophobic force is likely a capillary force that arises from the formation of capillary bridges due to the merging of nanobubbles. In this study, we aim to investigate the impact of the nanobubble surface charge on the capillary bridge and, subsequently, the interaction between particles. The surface charge of the nanobubbles was altered in the presence of various surfactants (cationic, anionic, and nonionic) and salts (mono-, di-, and trivalent). The particle-particle interaction was quantified by measuring the aggregate size of the hydrophobized glass particles. Both experimental and theoretical findings confirm that the interaction between particles was enhanced when the surface potential of the nanobubble was around the neutral regime. This is probably because, when the surface potential was close to neutral, the interaction between two surface-deposited nanobubbles dominated over electrostatic repulsion, which was more conducive to the formation of the nanobubble capillary bridge. The estimation of the constrained Gibbs potential also showed the capillary bridge to be more stable when surface charge density along the bridge gas-liquid interface was minimal.

Foldable low-cost point-of-care device for testing blood coagulation using smartphones

Cardiovascular diseases (CVDs) caused by thrombotic events are a significant global health concern, affecting millions of people worldwide. The international normalized ratio (INR) is the most widely used measure of coagulation status, and frequent testing is required to adjust blood-thinning drug dosage, requiring hospital visits and experts to perform the test. Here we present a low-cost and portable smartphone-based device for screening INR levels from whole blood samples at the point of care. Our device uses a 3D printed platform and light-emitting diode backlight modules to create a uniform optical environment, and its foldable design allows for easy transport. Our device also features an algorithm that allows users to acquire and process video of sample flow in a microfluidic channel on their smartphone, providing a cost-effective and convenient option for blood coagulation monitoring at the point of care. We tested the performance of our smartphone-based INR device using both commercially available control samples and clinical human blood samples, demonstrating high accuracy and reliability. Our device has the potential to improve patient outcomes by enabling more frequent monitoring and, as appropriate, dosage adjustments of blood-thinning drugs, providing an affordable and portable option for screening INR levels at the point of care.

The Motion Behavior of Micron Fly-Ash Particles Impacting on the Liquid Surface

The motion behavior of particles impacting on the liquid surface can affect the capture efficiency of particles. It was found that there are three kinds of motion behaviors after particle impact on the liquid surface: sinking, rebound, and oscillation. In this paper, the processes of micron fly-ash particles impacting on the liquid surface were experimentally studied under normal temperature and pressure. The impact of fly-ash particles on the liquid surface was simulated by a dynamic model. Based on force analysis, the dynamic model was developed and verified by experimental data to distinguish between three motion behaviors. Then, the sinking/rebound critical velocity and rebound/oscillation critical velocity were calculated by the dynamic model. The critical velocities of particles impacting on the liquid surface under different particle sizes, receding angles, and surface tension coefficients were analyzed. As the particle size increased, sinking/rebound critical velocity and rebound/oscillation critical velocity decreased. As the receding angle increased, sinking/rebound critical velocity remained unchanged, and the rebound/oscillation critical velocity decreased. As the liquid surface tension coefficient increased, sinking/rebound critical velocity and rebound/oscillation critical velocity increased. On this basis, the behaviors of particles impacting on the liquid at low velocity were analyzed.

Impact Behavior of Hydrophilic Micron Particles on a Planar Gas-Liquid Interface

The behavior of hydrophilic micron particles impacting on the gas-liquid interface has been further experimentally studied using a high-speed camera at different surface tensions and dynamic viscosities of liquids. The results show that the impact behavior exhibits suspension and submergence modes, whose boundary cannot be clearly identified because the overlap between the impact velocity ranges occurs because of the unstable pinning of the three-phase contact line on the surface of hydrophilic particles. The liquid properties have little effect on the wettability of hydrophilic particles but greatly influence the hydrodynamic and capillary force exerted on the particles, leading to the expansion of the suspension mode range. In addition, the penetration probability changes little with the decrease in surface tension, while it significantly reduces with the increase in dynamic viscosity. A penetration probability model is predicted as an exponential function of the inertial and supporting forces, and the experimental values agree well with the predicted values. The outcomes of this research will be helpful for understanding the mechanism of particle-interface interaction and providing guidance for enhancing the separation of hydrophilic fine ash via a bubble scrubbing system.