Perturbations of the Depth of Liquid Penetration Into the Capillary During Bubble Departures

In the present paper, the influence of bubble size on liquid penetration into the capillary was experimentally and numerically studied. In the experiment, bubbles were generated from a glass capillary (with an inner diameter equal to 1 mm) in a glass tank containing distilled water, tap water or an aqueous solution of calcium carbonate. These liquids differ in the value of their surface tension, which influences the bubble size. During experimental investigations, air pressure fluctuations in the gas supply system were measured. Simultaneously, the videos showing the liquids’ penetration into the capillary were recorded. Based on the videos, the time series of liquid movements inside the capillary were recovered. The numerical models were used to study the influence of bubble size on the velocity of liquid flow above the capillary and the depth of liquid penetration into the capillary. It was shown that the air volume flow rate and the surface tension have the greatest impact on the changes of pressure during a single cycle of bubble departure (Δp). The changes in pressure during a single cycle of bubble departure determine the depth of liquid penetration into the capillary. Moreover, the values of Δp and, consequently, the depth of liquid penetration can be modified by perturbations in the liquid velocity above the capillary outlet.

Influence of paper properties on adhesive strength of starch gluing

The effect of paper properties on the strength of starch gluing for Kraft sack papers has been investigated. We analyzed the effect of surface roughness, wettability and glue penetration. Surface roughness was found not to be related to gluing strength, also surface wetting measured by contact angle showed only a weak relation. Liquid penetration measured by ultrasound (ULP) was found to have a substantial correlation to gluing strength. Comparing ULP liquid penetration speed with actual glue uptake during the gluing process we found that they are only moderately connected. We are attributing this to the fact that the penetration and spreading of the glue on the paper is driven by applying an external pressure during the gluing process, which is not the case for the liquid penetration measurement. Investigating how asymmetrical glue penetration affects gluing strength we found that the relationship was low. The best indication for gluing strength turned out to be the surface wetting/substrate swelling parameter from the ultrasonic liquid penetration measurement. We conclude that the main parameter capturing gluing strength combines the influence of fiber wetting and penetration of the glue into the fibers.

The Influence of Water Hardness Perturbations on Bubble Departure Dynamics

The influence of small changes to water hardness on the nonlinear behaviour of liquid penetration into a capillary and the resulting air pressure fluctuations during air bubble formation are examined in this paper. Experiments were undertaken in which bubbles were generated both in water having a surface tensile force of σ = 72.2 mN/m and in an aqueous solution of calcium carbonate having a surface tensile force of σ = 75.4 mN/m, each contained in a glass capillary with an internal diameter of 1 mm. It is shown that both the maximum value of liquid penetration into the capillary and bubble growth time are affected by perturbations to the water hardness. The time it takes for the bubble to depart the capillary was estimated using the following nonlinear data analysis methods: time delay (τ), attractor reconstructions, correlation dimension (D), and largest Lyapunov exponent (λ). All estimates demonstrate that the pressure fluctuations in the c-c aqueous solutions and extent of liquid solution penetration into the capillary during the time between subsequent bubble departures behave chaotically.

Insights into the Control of Drug Release from Complex Immediate Release Formulations

The kinetics of water transport into tablets, and how it can be controlled by the formulation as well as the tablet microstructure, are of central importance in order to design and control the dissolution and drug release process, especially for immediate release tablets. This research employed terahertz pulsed imaging to measure the process of water penetrating through tablets using a flow cell. Tablets were prepared over a range of porosity between 10% to 20%. The formulations consist of two drugs (MK-8408: ruzasvir as a spray dried intermediate, and MK-3682: uprifosbuvir as a crystalline drug substance) and NaCl (0% to 20%) at varying levels of concentrations as well as other excipients. A power-law model is found to fit the liquid penetration exceptionally well (average R2>0.995). For each formulation, the rate of water penetration, extent of swelling and the USP dissolution rate were compared. A factorial analysis then revealed that the tablet porosity was the dominating factor for both liquid penetration and dissolution. NaCl more significantly influenced liquid penetration due to osmotic driving force as well as gelling suppression, but there appears to be little difference when NaCl loading in the formulation increases from 5% to 10%. The level of spray dried intermediate was observed to further limit the release of API in dissolution.

Fabrication of MnO2 nanowires@Ag/cellulose laminated membrane with unidirectional liquid penetration for personal thermal management applications

Controllable and reliable fabrication of wearable materials with tunable structures and integrated functionalities are urgently required for personal thermal management. Herein, this highlight presents the fabrication of MnO2 nanowires@Ag/cellulose laminated membrane with infrared insulation, antibacterial and unidirectional liquid penetration properties via orderly vacuum filtration of hydrophobic cellulose, hydrophilic cellulose and ultra-long MnO2 nanowires coated with silver (MnO2 nanowires@Ag). To do this, hydrophobic sugarcane cellulose was obtained by surface modification with silane coupling agent (A151), while hydrophilic sugarcane cellulose was obtained by HNO3 treatment. Silver coated MnO2 nanowires, as the building blocks of laminated membranes, were prepared by magnetron sputtering of silver nanoparticles onto the surfaces of MnO2 nanowires. The characterizations indicated that silver nano coating with high infrared radiation reflectivity and excellent electrical conductivity were successfully fabricated onto MnO2 nanowires surfaces, resulting in infrared insulation properties of the laminated cellulose membranes. In addition, the laminated membranes exhibit excellent unidirectional liquid penetration properties that can enhance the wearing comfort for the laminated cellulose membranes. In the antibacterial tests against Escherichia coli and Staphylococcus aureus, the laminated membranes exhibit large diameters of inhibition zones, revealing the high antibacterial activity. Moreover, excellent electrical conductivity of silver coating grants the superior Joule heating, generating rapid thermal response and uniform electrical heating at low supply voltage for extra warmth. These results indicate a promising potential of the laminated cellulose membranes for tackling personal thermal management issues related to wearable applications.